{"gene":"TCTN1","run_date":"2026-06-10T10:51:54","timeline":{"discoveries":[{"year":2025,"finding":"TCTN1 acts as a protein scaffold to promote binding between HADHA and HADHB, the two subunits of the mitochondrial trifunctional protein (MTP) complex, thereby activating fatty acid oxidation (FAO) and downstream p38/MAPK signaling to drive epithelial-mesenchymal transition and stemness in melanoma cells.","method":"Co-immunoprecipitation, molecular docking, TCTN1 knockdown/overexpression with in vitro invasion/migration assays and in vivo metastasis models; rescue experiments with fluprostenol (HADHA/HADHB binding blocker)","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP establishing scaffold function, multiple orthogonal methods (in vitro assays, in vivo metastasis, molecular docking confirmed experimentally), functional rescue with small molecule","pmids":["39325960"],"is_preprint":false},{"year":2025,"finding":"Full-length TCTN1 protein integrity is indispensable for ciliogenesis and transition-zone (TZ) localization; neither the conserved DUF1619 domain alone nor any truncated variant rescues ciliary morphology in tctn1-null Chlamydomonas, and deletion of the C-terminus destabilizes the protein during ciliary disassembly.","method":"Stable expression of full-length and four truncated TCTN1 constructs in Chlamydomonas reinhardtii tctn1 cells; quantitative comparison of ciliary morphology, TZ localization, and protein stability","journal":"iScience","confidence":"High","confidence_rationale":"Tier 2 / Strong — systematic domain-deletion rescue analysis in null background with multiple constructs and quantitative readouts of localization and stability","pmids":["41446745"],"is_preprint":false},{"year":2025,"finding":"TCTN1 co-localizes with vimentin and actin in vascular smooth muscle cells (VSMCs); TCTN1 overexpression reverses GA(13:0)-induced G0/G1 arrest, inhibition of cyclin D1-CDK4 and cyclin E1-CDK2 complex formation, vimentin suppression, and F-actin depolymerization, placing TCTN1 upstream of cell-cycle progression and cytoskeletal rearrangement in VSMCs. Transcription factor CTCF binds the TCTN1 promoter (site 162–176) to regulate TCTN1 transcription.","method":"Comparative proteomics, TCTN1 overexpression rescue experiments, co-immunoprecipitation of cyclin-CDK complexes, immunofluorescence co-localization, CTCF ChIP/knockout","journal":"Cells","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (proteomics, rescue, co-IP, ChIP) in a single lab study","pmids":["41369411"],"is_preprint":false},{"year":2017,"finding":"Knockdown of TCTN1 in thyroid cancer cells induces S-phase arrest accompanied by upregulation of CDK2 and cyclin A2 and downregulation of cyclin B1, and induces apoptosis via increased BAD, cleaved caspase-3, and PARP and decreased Bcl-2.","method":"Lentivirus-mediated RNAi knockdown; MTT, colony formation, flow cytometry, western blotting for cell-cycle and apoptosis proteins","journal":"Experimental and therapeutic medicine","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — clean KD with defined molecular readouts; single lab, multiple assays but no pathway rescue","pmids":["29042969"],"is_preprint":false},{"year":2015,"finding":"Lentivirus-mediated knockdown of TCTN1 in human glioma cells (U251, U87MG) inhibits proliferation and causes G0/G1 phase arrest.","method":"Lentiviral shRNA knockdown; MTT, colony formation, flow cytometry cell-cycle analysis","journal":"Applied biochemistry and biotechnology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — clean KD with defined cellular phenotype across two cell lines; single lab, no pathway rescue","pmids":["25737023"],"is_preprint":false},{"year":2017,"finding":"Knockdown of TCTN1 in colorectal cancer cells induces G2/M arrest and apoptosis via downregulation of caspase-3 and Bcl-2 and upregulation of cleaved caspase-3 and PARP.","method":"RNAi knockdown in HCT116 and SW1116 cells; MTT, colony formation, Annexin V/7-AAD flow cytometry, western blotting","journal":"Medical science monitor","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — clean KD with defined molecular readouts across two cell lines; single lab","pmids":["28123172"],"is_preprint":false},{"year":2021,"finding":"Transcription factor AP-2 alpha (TFAP2A) regulates TCTN1 mRNA expression by acting at the TCTN1 core promoter in oral squamous cell carcinoma cells.","method":"Promoter reporter assay identifying core promoter; functional association of TFAP2A with TCTN1 expression","journal":"Oncology reports","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, single method (promoter reporter), limited mechanistic depth","pmids":["34859261"],"is_preprint":false},{"year":2019,"finding":"miR-216a-5p directly targets the 3′-UTR of TCTN1 mRNA (confirmed by luciferase reporter assay), suppressing TCTN1 protein expression and downstream PCNA, Bcl-2, and Bad levels in esophageal squamous cell carcinoma cells.","method":"Luciferase reporter assay, miR-216a-5p overexpression, western blotting, rescue by TCTN1 restoration","journal":"Cellular & molecular biology letters","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — luciferase validation plus rescue experiment; single lab, two orthogonal methods","pmids":["31297133"],"is_preprint":false},{"year":2018,"finding":"miR-1256 directly targets TCTN1 (confirmed by luciferase reporter assay), suppressing TCTN1 protein and inhibiting NSCLC cell proliferation and migration.","method":"Luciferase reporter assay, immunoblotting, MTT, transwell migration assay","journal":"Oncology letters","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — luciferase validation with functional readouts; single lab, multiple assays","pmids":["30008857"],"is_preprint":false}],"current_model":"TCTN1 is a transition-zone scaffold protein required for full-length integrity to maintain ciliary architecture and gatekeeper function; in cancer and vascular contexts it acts as a protein scaffold (e.g., promoting HADHA–HADHB assembly to activate mitochondrial fatty acid oxidation and p38/MAPK signaling driving EMT) and as a regulator of cell-cycle progression (G0/G1 or G2/M) and cytoskeletal organization (vimentin/F-actin), with its transcription controlled by CTCF and TFAP2A and its mRNA targeted by miR-216a-5p and miR-1256."},"narrative":{"mechanistic_narrative":"TCTN1 functions both as a transition-zone scaffold required for ciliary integrity and as a cytoplasmic scaffold that organizes metabolic and cytoskeletal machinery to control cell behavior [PMID:41446745, PMID:39325960]. In Chlamydomonas, full-length TCTN1 is indispensable for ciliogenesis and transition-zone localization: neither the conserved DUF1619 domain alone nor truncated variants rescue ciliary morphology in tctn1-null cells, and C-terminal deletion destabilizes the protein during ciliary disassembly, establishing that intact protein architecture, not a single isolated domain, underlies its scaffolding role [PMID:41446745]. In melanoma, TCTN1 acts as a protein scaffold that promotes binding between HADHA and HADHB, the two subunits of the mitochondrial trifunctional protein, thereby activating fatty acid oxidation and downstream p38/MAPK signaling to drive epithelial-mesenchymal transition and stemness; this scaffolding is functionally interruptible by a HADHA/HADHB binding blocker [PMID:39325960]. TCTN1 also co-localizes with vimentin and actin in vascular smooth muscle cells, where it acts upstream of cyclin-CDK complex formation and cytoskeletal organization, reversing G0/G1 arrest, vimentin suppression, and F-actin depolymerization [PMID:41369411]. Consistent with a role in proliferative control, TCTN1 depletion arrests the cell cycle and triggers apoptosis across multiple cancer cell types [PMID:29042969, PMID:25737023, PMID:28123172]. Its expression is transcriptionally controlled by CTCF binding the TCTN1 promoter [PMID:41369411] and post-transcriptionally repressed by miR-216a-5p and miR-1256 acting on its mRNA [PMID:31297133, PMID:30008857].","teleology":[{"year":2015,"claim":"Whether TCTN1 influences cancer cell proliferation was unknown; depletion experiments established it as a positive regulator of cell-cycle progression in glioma.","evidence":"Lentiviral shRNA knockdown in U251 and U87MG glioma cells with proliferation and cell-cycle assays","pmids":["25737023"],"confidence":"Medium","gaps":["No molecular mechanism linking TCTN1 to cycle machinery","No rescue to confirm specificity","Restricted to glioma lines"]},{"year":2017,"claim":"It was unclear whether the proliferative requirement for TCTN1 generalized and engaged apoptotic programs; knockdown in thyroid and colorectal cancer linked loss of TCTN1 to cell-cycle arrest and caspase-dependent apoptosis.","evidence":"RNAi knockdown in thyroid and colorectal cancer cell lines with flow cytometry and western blotting of cycle/apoptosis proteins","pmids":["29042969","28123172"],"confidence":"Medium","gaps":["Arrest phase differs between contexts (S vs G2/M) without explanation","No pathway rescue","Upstream effector of TCTN1 unidentified"]},{"year":2018,"claim":"How TCTN1 levels are set was unaddressed; two studies showed direct miRNA repression, defining a post-transcriptional control layer.","evidence":"Luciferase 3'-UTR reporter assays with miR-1256 (NSCLC) and miR-216a-5p (esophageal carcinoma), plus protein-level and rescue experiments","pmids":["30008857","31297133"],"confidence":"Medium","gaps":["Endogenous physiological relevance of these miRNAs not established","No in vivo confirmation"]},{"year":2021,"claim":"The transcriptional drivers of TCTN1 were unknown; a promoter analysis implicated TFAP2A at the core promoter.","evidence":"Promoter reporter assay defining the core promoter in oral squamous cell carcinoma cells","pmids":["34859261"],"confidence":"Low","gaps":["Single method without ChIP or knockout validation","Direct binding not demonstrated","Limited mechanistic depth"]},{"year":2025,"claim":"Whether TCTN1 had a defined molecular activity beyond a proliferation phenotype was open; reciprocal Co-IP and rescue established it as a scaffold promoting HADHA-HADHB assembly to activate fatty acid oxidation and p38/MAPK-driven EMT.","evidence":"Co-immunoprecipitation, molecular docking, knockdown/overexpression with in vitro and in vivo metastasis models, and small-molecule binding-blocker rescue in melanoma","pmids":["39325960"],"confidence":"High","gaps":["Structural basis of the TCTN1-HADHA/HADHB interface not resolved","Whether scaffold function is melanoma-specific or general","Relationship between mitochondrial scaffolding and ciliary role unclear"]},{"year":2025,"claim":"The structural requirements for TCTN1's ciliary function were undefined; systematic domain-deletion rescue showed full-length integrity, not the conserved DUF1619 domain alone, is required for ciliogenesis and transition-zone localization.","evidence":"Stable expression of full-length and four truncated constructs in Chlamydomonas tctn1-null cells with quantitative ciliary morphology, localization, and stability readouts","pmids":["41446745"],"confidence":"High","gaps":["Identity of the partners stabilizing full-length TCTN1 at the transition zone not defined","Conservation of this requirement in mammalian cilia not tested"]},{"year":2025,"claim":"Whether TCTN1 connects to cytoskeleton and cycle control in non-cancer cells was unknown; in vascular smooth muscle cells it was placed upstream of cyclin-CDK assembly and cytoskeletal organization, with CTCF identified as a transcriptional regulator.","evidence":"Comparative proteomics, overexpression rescue, cyclin-CDK Co-IP, immunofluorescence co-localization with vimentin/actin, and CTCF ChIP/knockout","pmids":["41369411"],"confidence":"Medium","gaps":["Direct biochemical interaction of TCTN1 with vimentin/actin not demonstrated","Single-lab study","Mechanism linking TCTN1 to cyclin-CDK assembly unresolved"]},{"year":null,"claim":"How TCTN1's transition-zone scaffolding role mechanistically connects to its cytoplasmic metabolic and cytoskeletal scaffold functions in disease contexts remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unifying structural model of TCTN1 scaffolding","Whether ciliary and mitochondrial functions share a common partner-binding surface unknown","No human Mendelian disease linkage in the corpus"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,1]}],"localization":[{"term_id":"GO:0005929","term_label":"cilium","supporting_discovery_ids":[1]},{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[0]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[2]}],"pathway":[{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[3,4,5]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[0]}],"complexes":[],"partners":["HADHA","HADHB"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q2MV58","full_name":"Tectonic-1","aliases":[],"length_aa":587,"mass_kda":63.6,"function":"Component of the tectonic-like complex, a complex localized at the transition zone of primary cilia and acting as a barrier that prevents diffusion of transmembrane proteins between the cilia and plasma membranes. Regulator of Hedgehog (Hh), required for both activation and inhibition of the Hh pathway in the patterning of the neural tube. During neural tube development, it is required for formation of the most ventral cell types and for full Hh pathway activation. Functions in Hh signal transduction to fully activate the pathway in the presence of high Hh levels and to repress the pathway in the absence of Hh signals. Modulates Hh signal transduction downstream of SMO and RAB23 (By similarity)","subcellular_location":"Cytoplasm, cytoskeleton, cilium basal body; Secreted","url":"https://www.uniprot.org/uniprotkb/Q2MV58/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/TCTN1","classification":"Not Classified","n_dependent_lines":3,"n_total_lines":1208,"dependency_fraction":0.0024834437086092716},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/TCTN1","total_profiled":1310},"omim":[{"mim_id":"620248","title":"TRANSMEMBRANE PROTEIN 80; TMEM80","url":"https://www.omim.org/entry/620248"},{"mim_id":"617570","title":"DAZ-INTERACTING ZINC FINGER PROTEIN 1-LIKE; DZIP1L","url":"https://www.omim.org/entry/617570"},{"mim_id":"614950","title":"TRANSMEMBRANE PROTEIN 17; TMEM17","url":"https://www.omim.org/entry/614950"},{"mim_id":"614949","title":"TRANSMEMBRANE PROTEIN 231; TMEM231","url":"https://www.omim.org/entry/614949"},{"mim_id":"614173","title":"JOUBERT SYNDROME 13; JBTS13","url":"https://www.omim.org/entry/614173"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Actin filaments","reliability":"Approved"},{"location":"Primary cilium","reliability":"Approved"},{"location":"Nucleoplasm","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"choroid plexus","ntpm":31.9}],"url":"https://www.proteinatlas.org/search/TCTN1"},"hgnc":{"alias_symbol":["FLJ21127","TECT1","JBTS13"],"prev_symbol":[]},"alphafold":{"accession":"Q2MV58","domains":[{"cath_id":"-","chopping":"72-156","consensus_level":"medium","plddt":87.128,"start":72,"end":156},{"cath_id":"-","chopping":"212-369","consensus_level":"high","plddt":90.1317,"start":212,"end":369},{"cath_id":"-","chopping":"387-560","consensus_level":"high","plddt":85.3857,"start":387,"end":560}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q2MV58","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q2MV58-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q2MV58-F1-predicted_aligned_error_v6.png","plddt_mean":77.56},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=TCTN1","jax_strain_url":"https://www.jax.org/strain/search?query=TCTN1"},"sequence":{"accession":"Q2MV58","fasta_url":"https://rest.uniprot.org/uniprotkb/Q2MV58.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q2MV58/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q2MV58"}},"corpus_meta":[{"pmid":"31297133","id":"PMC_31297133","title":"MiR-216a-5p targets TCTN1 to inhibit cell proliferation and induce apoptosis in esophageal squamous cell carcinoma.","date":"2019","source":"Cellular & molecular biology letters","url":"https://pubmed.ncbi.nlm.nih.gov/31297133","citation_count":24,"is_preprint":false},{"pmid":"30008857","id":"PMC_30008857","title":"MiR-1256 suppresses proliferation and migration of non-small cell lung cancer via regulating TCTN1.","date":"2018","source":"Oncology letters","url":"https://pubmed.ncbi.nlm.nih.gov/30008857","citation_count":17,"is_preprint":false},{"pmid":"29042969","id":"PMC_29042969","title":"Silencing of TCTN1 inhibits proliferation, induces cell cycle arrest and apoptosis in human thyroid cancer.","date":"2017","source":"Experimental and therapeutic medicine","url":"https://pubmed.ncbi.nlm.nih.gov/29042969","citation_count":13,"is_preprint":false},{"pmid":"39325960","id":"PMC_39325960","title":"TCTN1 Induces Fatty Acid Oxidation to Promote Melanoma Metastasis.","date":"2025","source":"Cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/39325960","citation_count":12,"is_preprint":false},{"pmid":"28123172","id":"PMC_28123172","title":"Knockdown of TCTN1 Strongly Decreases Growth of Human Colon Cancer Cells.","date":"2017","source":"Medical science monitor : international medical journal of experimental and clinical research","url":"https://pubmed.ncbi.nlm.nih.gov/28123172","citation_count":12,"is_preprint":false},{"pmid":"34859261","id":"PMC_34859261","title":"Function and transcriptional regulation of TCTN1 in oral squamous cell carcinoma.","date":"2021","source":"Oncology reports","url":"https://pubmed.ncbi.nlm.nih.gov/34859261","citation_count":8,"is_preprint":false},{"pmid":"25737023","id":"PMC_25737023","title":"Lentivirus-Mediated Knockdown of TCTN1 Inhibits Glioma Cell Proliferation.","date":"2015","source":"Applied biochemistry and biotechnology","url":"https://pubmed.ncbi.nlm.nih.gov/25737023","citation_count":8,"is_preprint":false},{"pmid":"32486612","id":"PMC_32486612","title":"microRNA-216a-5p inhibits the development of gastric cancer through target combination with TCTN1.","date":"2020","source":"Minerva medica","url":"https://pubmed.ncbi.nlm.nih.gov/32486612","citation_count":4,"is_preprint":false},{"pmid":"28631893","id":"PMC_28631893","title":"Expanding the allelic disorders linked to TCTN1 to include Varadi syndrome (Orofaciodigital syndrome type VI).","date":"2017","source":"American journal of medical genetics. Part A","url":"https://pubmed.ncbi.nlm.nih.gov/28631893","citation_count":3,"is_preprint":false},{"pmid":"41369411","id":"PMC_41369411","title":"Ginkgolic Acid Inhibits VSMC Proliferation and Migration and Vascular Restenosis by Regulating Cell Cycle Progression and Cytoskeleton Rearrangement Through TCTN1.","date":"2025","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/41369411","citation_count":2,"is_preprint":false},{"pmid":"34980503","id":"PMC_34980503","title":"Clinical and molecular characteristics of tectonic (TCTN1) gene-related Joubert syndrome in a Saudi boy.","date":"2021","source":"Brain & development","url":"https://pubmed.ncbi.nlm.nih.gov/34980503","citation_count":1,"is_preprint":false},{"pmid":"39097279","id":"PMC_39097279","title":"[Identification of TCTN1 gene variants in a fetus with Joubert syndrome 13].","date":"2024","source":"Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/39097279","citation_count":0,"is_preprint":false},{"pmid":"41446745","id":"PMC_41446745","title":"Profiling truncated variants of TCTN1 unveils the essential role of its integrity for ciliogenesis.","date":"2025","source":"iScience","url":"https://pubmed.ncbi.nlm.nih.gov/41446745","citation_count":0,"is_preprint":false},{"pmid":"31302911","id":"PMC_31302911","title":"[Diagnosis of two cases from one family with Joubert syndrome caused by novel mutations of TCTN1 gene by whole exome sequencing].","date":"2019","source":"Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/31302911","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":8342,"output_tokens":2170,"usd":0.028788,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9180,"output_tokens":2867,"usd":0.058787,"stage2_stop_reason":"end_turn"},"total_usd":0.087575,"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\": 2025,\n      \"finding\": \"TCTN1 acts as a protein scaffold to promote binding between HADHA and HADHB, the two subunits of the mitochondrial trifunctional protein (MTP) complex, thereby activating fatty acid oxidation (FAO) and downstream p38/MAPK signaling to drive epithelial-mesenchymal transition and stemness in melanoma cells.\",\n      \"method\": \"Co-immunoprecipitation, molecular docking, TCTN1 knockdown/overexpression with in vitro invasion/migration assays and in vivo metastasis models; rescue experiments with fluprostenol (HADHA/HADHB binding blocker)\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP establishing scaffold function, multiple orthogonal methods (in vitro assays, in vivo metastasis, molecular docking confirmed experimentally), functional rescue with small molecule\",\n      \"pmids\": [\"39325960\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Full-length TCTN1 protein integrity is indispensable for ciliogenesis and transition-zone (TZ) localization; neither the conserved DUF1619 domain alone nor any truncated variant rescues ciliary morphology in tctn1-null Chlamydomonas, and deletion of the C-terminus destabilizes the protein during ciliary disassembly.\",\n      \"method\": \"Stable expression of full-length and four truncated TCTN1 constructs in Chlamydomonas reinhardtii tctn1 cells; quantitative comparison of ciliary morphology, TZ localization, and protein stability\",\n      \"journal\": \"iScience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — systematic domain-deletion rescue analysis in null background with multiple constructs and quantitative readouts of localization and stability\",\n      \"pmids\": [\"41446745\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"TCTN1 co-localizes with vimentin and actin in vascular smooth muscle cells (VSMCs); TCTN1 overexpression reverses GA(13:0)-induced G0/G1 arrest, inhibition of cyclin D1-CDK4 and cyclin E1-CDK2 complex formation, vimentin suppression, and F-actin depolymerization, placing TCTN1 upstream of cell-cycle progression and cytoskeletal rearrangement in VSMCs. Transcription factor CTCF binds the TCTN1 promoter (site 162–176) to regulate TCTN1 transcription.\",\n      \"method\": \"Comparative proteomics, TCTN1 overexpression rescue experiments, co-immunoprecipitation of cyclin-CDK complexes, immunofluorescence co-localization, CTCF ChIP/knockout\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (proteomics, rescue, co-IP, ChIP) in a single lab study\",\n      \"pmids\": [\"41369411\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Knockdown of TCTN1 in thyroid cancer cells induces S-phase arrest accompanied by upregulation of CDK2 and cyclin A2 and downregulation of cyclin B1, and induces apoptosis via increased BAD, cleaved caspase-3, and PARP and decreased Bcl-2.\",\n      \"method\": \"Lentivirus-mediated RNAi knockdown; MTT, colony formation, flow cytometry, western blotting for cell-cycle and apoptosis proteins\",\n      \"journal\": \"Experimental and therapeutic medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — clean KD with defined molecular readouts; single lab, multiple assays but no pathway rescue\",\n      \"pmids\": [\"29042969\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Lentivirus-mediated knockdown of TCTN1 in human glioma cells (U251, U87MG) inhibits proliferation and causes G0/G1 phase arrest.\",\n      \"method\": \"Lentiviral shRNA knockdown; MTT, colony formation, flow cytometry cell-cycle analysis\",\n      \"journal\": \"Applied biochemistry and biotechnology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — clean KD with defined cellular phenotype across two cell lines; single lab, no pathway rescue\",\n      \"pmids\": [\"25737023\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Knockdown of TCTN1 in colorectal cancer cells induces G2/M arrest and apoptosis via downregulation of caspase-3 and Bcl-2 and upregulation of cleaved caspase-3 and PARP.\",\n      \"method\": \"RNAi knockdown in HCT116 and SW1116 cells; MTT, colony formation, Annexin V/7-AAD flow cytometry, western blotting\",\n      \"journal\": \"Medical science monitor\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — clean KD with defined molecular readouts across two cell lines; single lab\",\n      \"pmids\": [\"28123172\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Transcription factor AP-2 alpha (TFAP2A) regulates TCTN1 mRNA expression by acting at the TCTN1 core promoter in oral squamous cell carcinoma cells.\",\n      \"method\": \"Promoter reporter assay identifying core promoter; functional association of TFAP2A with TCTN1 expression\",\n      \"journal\": \"Oncology reports\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, single method (promoter reporter), limited mechanistic depth\",\n      \"pmids\": [\"34859261\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"miR-216a-5p directly targets the 3′-UTR of TCTN1 mRNA (confirmed by luciferase reporter assay), suppressing TCTN1 protein expression and downstream PCNA, Bcl-2, and Bad levels in esophageal squamous cell carcinoma cells.\",\n      \"method\": \"Luciferase reporter assay, miR-216a-5p overexpression, western blotting, rescue by TCTN1 restoration\",\n      \"journal\": \"Cellular & molecular biology letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — luciferase validation plus rescue experiment; single lab, two orthogonal methods\",\n      \"pmids\": [\"31297133\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"miR-1256 directly targets TCTN1 (confirmed by luciferase reporter assay), suppressing TCTN1 protein and inhibiting NSCLC cell proliferation and migration.\",\n      \"method\": \"Luciferase reporter assay, immunoblotting, MTT, transwell migration assay\",\n      \"journal\": \"Oncology letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — luciferase validation with functional readouts; single lab, multiple assays\",\n      \"pmids\": [\"30008857\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"TCTN1 is a transition-zone scaffold protein required for full-length integrity to maintain ciliary architecture and gatekeeper function; in cancer and vascular contexts it acts as a protein scaffold (e.g., promoting HADHA–HADHB assembly to activate mitochondrial fatty acid oxidation and p38/MAPK signaling driving EMT) and as a regulator of cell-cycle progression (G0/G1 or G2/M) and cytoskeletal organization (vimentin/F-actin), with its transcription controlled by CTCF and TFAP2A and its mRNA targeted by miR-216a-5p and miR-1256.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"TCTN1 functions both as a transition-zone scaffold required for ciliary integrity and as a cytoplasmic scaffold that organizes metabolic and cytoskeletal machinery to control cell behavior [#1, #0]. In Chlamydomonas, full-length TCTN1 is indispensable for ciliogenesis and transition-zone localization: neither the conserved DUF1619 domain alone nor truncated variants rescue ciliary morphology in tctn1-null cells, and C-terminal deletion destabilizes the protein during ciliary disassembly, establishing that intact protein architecture, not a single isolated domain, underlies its scaffolding role [#1]. In melanoma, TCTN1 acts as a protein scaffold that promotes binding between HADHA and HADHB, the two subunits of the mitochondrial trifunctional protein, thereby activating fatty acid oxidation and downstream p38/MAPK signaling to drive epithelial-mesenchymal transition and stemness; this scaffolding is functionally interruptible by a HADHA/HADHB binding blocker [#0]. TCTN1 also co-localizes with vimentin and actin in vascular smooth muscle cells, where it acts upstream of cyclin-CDK complex formation and cytoskeletal organization, reversing G0/G1 arrest, vimentin suppression, and F-actin depolymerization [#2]. Consistent with a role in proliferative control, TCTN1 depletion arrests the cell cycle and triggers apoptosis across multiple cancer cell types [#3, #4, #5]. Its expression is transcriptionally controlled by CTCF binding the TCTN1 promoter [#2] and post-transcriptionally repressed by miR-216a-5p and miR-1256 acting on its mRNA [#7, #8].\",\n  \"teleology\": [\n    {\n      \"year\": 2015,\n      \"claim\": \"Whether TCTN1 influences cancer cell proliferation was unknown; depletion experiments established it as a positive regulator of cell-cycle progression in glioma.\",\n      \"evidence\": \"Lentiviral shRNA knockdown in U251 and U87MG glioma cells with proliferation and cell-cycle assays\",\n      \"pmids\": [\"25737023\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No molecular mechanism linking TCTN1 to cycle machinery\", \"No rescue to confirm specificity\", \"Restricted to glioma lines\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"It was unclear whether the proliferative requirement for TCTN1 generalized and engaged apoptotic programs; knockdown in thyroid and colorectal cancer linked loss of TCTN1 to cell-cycle arrest and caspase-dependent apoptosis.\",\n      \"evidence\": \"RNAi knockdown in thyroid and colorectal cancer cell lines with flow cytometry and western blotting of cycle/apoptosis proteins\",\n      \"pmids\": [\"29042969\", \"28123172\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Arrest phase differs between contexts (S vs G2/M) without explanation\", \"No pathway rescue\", \"Upstream effector of TCTN1 unidentified\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"How TCTN1 levels are set was unaddressed; two studies showed direct miRNA repression, defining a post-transcriptional control layer.\",\n      \"evidence\": \"Luciferase 3'-UTR reporter assays with miR-1256 (NSCLC) and miR-216a-5p (esophageal carcinoma), plus protein-level and rescue experiments\",\n      \"pmids\": [\"30008857\", \"31297133\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Endogenous physiological relevance of these miRNAs not established\", \"No in vivo confirmation\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"The transcriptional drivers of TCTN1 were unknown; a promoter analysis implicated TFAP2A at the core promoter.\",\n      \"evidence\": \"Promoter reporter assay defining the core promoter in oral squamous cell carcinoma cells\",\n      \"pmids\": [\"34859261\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single method without ChIP or knockout validation\", \"Direct binding not demonstrated\", \"Limited mechanistic depth\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Whether TCTN1 had a defined molecular activity beyond a proliferation phenotype was open; reciprocal Co-IP and rescue established it as a scaffold promoting HADHA-HADHB assembly to activate fatty acid oxidation and p38/MAPK-driven EMT.\",\n      \"evidence\": \"Co-immunoprecipitation, molecular docking, knockdown/overexpression with in vitro and in vivo metastasis models, and small-molecule binding-blocker rescue in melanoma\",\n      \"pmids\": [\"39325960\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of the TCTN1-HADHA/HADHB interface not resolved\", \"Whether scaffold function is melanoma-specific or general\", \"Relationship between mitochondrial scaffolding and ciliary role unclear\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"The structural requirements for TCTN1's ciliary function were undefined; systematic domain-deletion rescue showed full-length integrity, not the conserved DUF1619 domain alone, is required for ciliogenesis and transition-zone localization.\",\n      \"evidence\": \"Stable expression of full-length and four truncated constructs in Chlamydomonas tctn1-null cells with quantitative ciliary morphology, localization, and stability readouts\",\n      \"pmids\": [\"41446745\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the partners stabilizing full-length TCTN1 at the transition zone not defined\", \"Conservation of this requirement in mammalian cilia not tested\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Whether TCTN1 connects to cytoskeleton and cycle control in non-cancer cells was unknown; in vascular smooth muscle cells it was placed upstream of cyclin-CDK assembly and cytoskeletal organization, with CTCF identified as a transcriptional regulator.\",\n      \"evidence\": \"Comparative proteomics, overexpression rescue, cyclin-CDK Co-IP, immunofluorescence co-localization with vimentin/actin, and CTCF ChIP/knockout\",\n      \"pmids\": [\"41369411\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct biochemical interaction of TCTN1 with vimentin/actin not demonstrated\", \"Single-lab study\", \"Mechanism linking TCTN1 to cyclin-CDK assembly unresolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How TCTN1's transition-zone scaffolding role mechanistically connects to its cytoplasmic metabolic and cytoskeletal scaffold functions in disease contexts remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unifying structural model of TCTN1 scaffolding\", \"Whether ciliary and mitochondrial functions share a common partner-binding surface unknown\", \"No human Mendelian disease linkage in the corpus\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005929\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [3, 4, 5]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"HADHA\", \"HADHB\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":6,"faith_pct":83.33333333333333}}