{"gene":"CEP20","run_date":"2026-06-09T22:57:18","timeline":{"discoveries":[{"year":2010,"finding":"FOR20 (CEP20) localizes to PCM1-enriched pericentriolar satellites and centrosomes. Its LisH domain promotes self-interaction and is required for satellite localization. Knockdown in RPE1 cells decreases the percentage of ciliated cells and cilium length, displaces PCM1 from detergent-insoluble to detergent-soluble fractions, and modifies satellite distribution, suggesting FOR20 regulates PCM1 satellite interaction with microtubules and motors.","method":"siRNA knockdown, detergent fractionation, immunofluorescence, domain mutagenesis (LisH domain)","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (fractionation, immunofluorescence, domain mutants, knockdown with defined phenotypic readout), replicated in subsequent studies","pmids":["20551181"],"is_preprint":false},{"year":2012,"finding":"In Paramecium, the FOR20 ortholog PtFOR20p localizes specifically at basal bodies and is required to build the transition zone, which is a prerequisite for basal body maturation and docking at the cell surface. Centrin PtCen2p (ortholog of human Cen2) is required to recruit PtFOR20p to the developing basal body and to control its length.","method":"RNAi knockdown in Paramecium, electron microscopy, immunofluorescence, functional and cytological analyses","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — combined functional and cytological analyses with defined structural phenotypes, ortholog of CEP20 in established ciliate model","pmids":["22718349"],"is_preprint":false},{"year":2013,"finding":"FOR20 (CEP20) interacts with Plk1 at centrosomes and is required for recruitment of Plk1 to centrosomes. Depletion of FOR20 inhibits S-phase progression; this defect is rescued by ectopic expression of centrosome-tethered Plk1 (but not wild-type Plk1), independently of Plk1 kinase activity, establishing that centrosomal recruitment of Plk1 by FOR20 licenses efficient S-phase progression.","method":"Co-immunoprecipitation, siRNA knockdown, rescue experiments with centrosome-tethered and kinase-dead Plk1 mutants, cell cycle analysis","journal":"Cell research","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, multiple mutant rescue experiments with defined cell cycle phenotype, mechanistic pathway placement established","pmids":["24018379"],"is_preprint":false},{"year":2015,"finding":"FOR20 (CEP20) forms a ternary complex with KIAA0753/OFIP and OFD1 at pericentriolar satellites and centrosomes. Decreased expression of any component of this ternary complex causes defective recruitment of the others to centrosomes and satellites. An OFD syndrome-associated KIAA0753 mutant loses the capacity to interact with FOR20 and OFD1.","method":"Co-immunoprecipitation, immunofluorescence, siRNA knockdown, patient mutation analysis","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP defining ternary complex, knockdown phenotypes with multiple components, patient mutant validation","pmids":["26643951"],"is_preprint":false},{"year":2017,"finding":"FOR20 (CEP20) directly binds to microtubules and free tubulin dimers in vitro, and preferentially interacts with free tubulin dimers over microtubules. FOR20 decreases the microtubule growth rate, increases the depolymerization rate and catastrophe frequency in vitro. Depletion of FOR20 inhibits microtubule depolymerization and promotes microtubule regrowth after nocodazole washout in HeLa cells. FOR20 knockdown also inhibits both individual and collective cell migration.","method":"In vitro microtubule dynamics assays, direct microtubule binding assay, live-cell imaging of microtubule dynamics, siRNA knockdown, nocodazole washout assay, cell migration assay","journal":"Cell discovery","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with direct binding and dynamics assays, complemented by cell-based knockdown phenotypes and live imaging","pmids":["28884019"],"is_preprint":false},{"year":2017,"finding":"FOR20 (CEP20) binds to tubulin: both anti-FOR20 antibody and GST-FOR20 precipitate tubulin from HeLa cell extract; FOR20 co-cycles with microtubule-associated proteins from brain tissue. Purified FOR20 inhibits tubulin assembly in vitro. Overexpression of FOR20 depolymerizes interphase microtubules; depletion prevents nocodazole-induced depolymerization and suppresses microtubule dynamics in live HeLa cells. FOR20-depleted MDA-MB-231 cells show impaired directed migration.","method":"GST pulldown, co-sedimentation assay with MAPs from brain tissue, in vitro tubulin polymerization assay, live-cell microtubule imaging, siRNA knockdown, cell migration assay","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution of tubulin binding and assembly inhibition, multiple orthogonal cell-based assays, independently corroborated by PMID 28884019","pmids":["28694353"],"is_preprint":false},{"year":2017,"finding":"S100A6 interacts with the N-terminal region (residues 1–30) of FOR20 (CEP20) in a Ca2+-dependent manner, both in vitro and in living cells. Multiple S100 family members (S100A1, A2, A4, A11, B) also bind FOR20 Ca2+-dependently. Related centrosomal proteins FOP and OFD1 share sequence similarity in this N-terminal region and also bind S100A6 Ca2+-dependently.","method":"Protein microarray screen, in vitro binding assay, co-immunoprecipitation in living cells, domain mapping (residues 1–30)","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — protein microarray identification plus in vitro and cell-based binding confirmation with domain mapping, single lab","pmids":["28765046"],"is_preprint":false},{"year":2017,"finding":"In Trypanosoma brucei, TbFOR20 (ortholog of CEP20) localizes to both pro-basal bodies and mature basal bodies, distal to TbRP2. A short negatively-charged N-terminal extension unique to African trypanosomes is necessary for correct protein targeting but insufficient to redirect TbRP2 to pro-basal bodies.","method":"Immunofluorescence localization, epitope-tagging, heterologous expression of T. cruzi FOR20 in T. brucei","journal":"Protist","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization experiment with domain targeting analysis, single lab, ortholog context","pmids":["28822909"],"is_preprint":false},{"year":2018,"finding":"FOR20 (CEP20) is required for normal ciliogenesis in vertebrate development. Morpholino-mediated knockdown and CRISPR/Cas9 knockout of for20 in zebrafish produce ciliary phenotypes (curved body, hydrocephaly, pericardial edema, kidney cysts, left-right asymmetry defects), reduced cilia number and length in Kupffer's vesicle and pronephric ducts, and paralyzed or arrhythmic cilia beating. All phenotypes are rescued by exogenous for20 mRNA.","method":"Morpholino knockdown, CRISPR/Cas9 knockout, mRNA rescue, high-speed video microscopy, immunofluorescence in zebrafish","journal":"FASEB journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — two independent loss-of-function approaches (morpholino + CRISPR) with defined phenotypes and mRNA rescue, in vertebrate model","pmids":["30475641"],"is_preprint":false},{"year":2021,"finding":"Homozygous knockout of For20 in mice causes embryonic growth arrest and lethality during gestation, impaired left-right patterning of embryos, reduced cilia in the embryonic node, and disrupted angiogenesis in yolk sacs and embryos. Heterozygous knockout mice show no obvious defects.","method":"Gene-targeting homozygous knockout mouse, immunofluorescence for cilia, embryo morphological analysis","journal":"FEBS letters","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean homozygous knockout with multiple defined phenotypic readouts (lethality, laterality, ciliogenesis, angiogenesis) in mammalian model","pmids":["33686659"],"is_preprint":false},{"year":2023,"finding":"CEP20 depletion inhibits NSCLC cell proliferation, migration, and microtubule polymerization. Knockdown or overexpression of CEP20 reciprocally affects microtubule polymerization in A549 cells, and CEP20 regulates cell adhesion-related signaling pathways.","method":"siRNA knockdown, overexpression, microtubule polymerization assay, cell migration and proliferation assays in NSCLC cell lines","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — cell-based knockdown/overexpression with phenotypic readouts, limited mechanistic detail in abstract, single lab corroborating prior findings","pmids":["37838783"],"is_preprint":false},{"year":2025,"finding":"PLK1-dependent phosphorylation of CEP20 at Ser46 enables high-affinity binding to CCDC116 and centrosomal recruitment of CCDC116, driving centriole overduplication. The CEP20-S46A mutation abolishes CCDC116 centrosomal localization and centrosome amplification. PLK1 upregulation (via EGR1) and CEP20 promoter hypomethylation (via DNMT3B suppression) together activate this PLK1-CEP20-CCDC116 axis.","method":"Site-directed mutagenesis (S46A), co-immunoprecipitation, centrosome amplification assays, knockdown of CCDC116 and CEP20, phosphorylation assays","journal":"Journal of agricultural and food chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mutagenesis and Co-IP establish phosphorylation-dependent interaction, single lab, mechanistic pathway defined but not independently replicated","pmids":["41401801"],"is_preprint":false}],"current_model":"CEP20 (FOR20) is a conserved centrosomal and pericentriolar satellite protein that (1) promotes ciliogenesis by building the transition zone and organizing PCM1 satellites via its LisH-domain-mediated self-interaction; (2) recruits Plk1 to centrosomes to license S-phase progression; (3) functions as a microtubule-associated protein that directly binds tubulin and promotes microtubule depolymerization, thereby facilitating directed cell migration; (4) forms a ternary complex with OFD1 and OFIP at satellites/centrosomes; (5) is regulated by Ca2+-dependent S100 protein binding at its N-terminal domain; and (6) is phosphorylated by PLK1 at Ser46, enabling CCDC116 binding and centrosomal recruitment that drives centriole overduplication."},"narrative":{"mechanistic_narrative":"CEP20 (FOR20) is a conserved centrosomal and pericentriolar satellite protein that organizes the ciliary apparatus and centrosome-associated cell cycle and migration machinery [PMID:20551181, PMID:30475641]. It localizes to PCM1-enriched satellites and centrosomes, where its LisH domain drives self-interaction and is required for satellite targeting and for the proper interaction of PCM1 satellites with microtubules [PMID:20551181]; in this context CEP20 assembles into a ternary complex with KIAA0753/OFIP and OFD1, with each component required to recruit the others, and an OFD-syndrome-associated KIAA0753 mutation disrupts CEP20 binding [PMID:26643951]. CEP20 is essential for ciliogenesis: it builds the transition zone required for basal body maturation and docking [PMID:22718349], and its loss in zebrafish and mice produces hallmark ciliopathy phenotypes including left-right asymmetry defects, reduced cilia number and length, and embryonic lethality [PMID:30475641, PMID:33686659]. At the centrosome CEP20 also licenses cell cycle progression by recruiting Plk1, a function rescued by centrosome-tethered but kinase-dead Plk1 and therefore independent of Plk1 catalytic activity [PMID:24018379]. Independently, CEP20 acts as a microtubule-associated protein that directly binds free tubulin dimers and microtubules, inhibits tubulin assembly, and promotes depolymerization and catastrophe, thereby supporting directed cell migration [PMID:28884019, PMID:28694353]. Its activity is modulated by Ca2+-dependent binding of S100 proteins to its N-terminal region (residues 1-30) [PMID:28765046], and PLK1 phosphorylation at Ser46 enables CCDC116 binding and centrosomal recruitment that drives centriole overduplication [PMID:41401801].","teleology":[{"year":2010,"claim":"Established CEP20 as a satellite/centrosome protein whose LisH-mediated self-interaction organizes PCM1 satellites and supports ciliogenesis, defining its baseline cellular role.","evidence":"siRNA knockdown, detergent fractionation, immunofluorescence, and LisH-domain mutagenesis in RPE1 cells","pmids":["20551181"],"confidence":"High","gaps":["Did not resolve how satellites physically engage microtubules/motors","Direct binding partners at satellites not yet identified"]},{"year":2012,"claim":"Showed the ortholog functions in basal body biology by building the transition zone required for basal body maturation and docking, placing CEP20 upstream of ciliary assembly.","evidence":"RNAi knockdown, electron microscopy, and immunofluorescence in Paramecium","pmids":["22718349"],"confidence":"High","gaps":["Molecular interactions building the transition zone not defined","Conservation of centrin-dependent recruitment in vertebrates not tested"]},{"year":2013,"claim":"Linked CEP20 to cell cycle control by demonstrating it recruits Plk1 to centrosomes to license S-phase progression, separating a structural recruitment role from Plk1 catalytic activity.","evidence":"Reciprocal Co-IP, siRNA knockdown, and rescue with centrosome-tethered and kinase-dead Plk1 mutants with cell cycle analysis","pmids":["24018379"],"confidence":"High","gaps":["Mechanism by which centrosomal Plk1 promotes S-phase entry not detailed","Whether recruitment is direct or complex-mediated not fully resolved"]},{"year":2015,"claim":"Defined a CEP20-OFIP-OFD1 ternary complex and tied it to disease by showing an OFD-associated KIAA0753 mutant loses CEP20/OFD1 binding, embedding CEP20 in a ciliopathy-relevant module.","evidence":"Co-IP, immunofluorescence, siRNA knockdown of multiple components, and patient mutation analysis","pmids":["26643951"],"confidence":"High","gaps":["Stoichiometry and structure of the ternary complex unknown","Functional output of the complex beyond mutual recruitment not defined"]},{"year":2017,"claim":"Reclassified CEP20 as a microtubule-regulating protein by reconstituting direct tubulin/microtubule binding and assembly inhibition, connecting this activity to directed cell migration.","evidence":"In vitro microtubule dynamics and direct-binding assays, GST pulldown, co-cycling with brain MAPs, live-cell imaging, nocodazole washout, and migration assays in HeLa and MDA-MB-231 cells (two independent studies)","pmids":["28884019","28694353"],"confidence":"High","gaps":["Tubulin-binding region/structural basis not mapped","How microtubule regulation integrates with satellite/ciliary functions unclear"]},{"year":2017,"claim":"Identified Ca2+-dependent S100 protein binding to the CEP20 N-terminus, introducing a calcium-signaling input that could regulate CEP20 function.","evidence":"Protein microarray screen, in vitro binding, Co-IP in living cells, and domain mapping to residues 1-30","pmids":["28765046"],"confidence":"Medium","gaps":["Functional consequence of S100 binding on ciliogenesis/microtubules not tested","Single lab; physiological Ca2+ context undefined"]},{"year":2017,"claim":"Mapped ortholog localization to pro- and mature basal bodies and identified lineage-specific N-terminal targeting determinants, refining where CEP20 acts at the centriole.","evidence":"Immunofluorescence, epitope-tagging, and heterologous expression in Trypanosoma brucei","pmids":["28822909"],"confidence":"Medium","gaps":["Targeting mechanism in vertebrate cells not addressed","Single lab, ortholog-specific context"]},{"year":2018,"claim":"Confirmed an essential ciliogenesis role in a vertebrate by linking CEP20 loss to characteristic ciliopathy phenotypes with mRNA rescue, establishing in vivo relevance.","evidence":"Morpholino knockdown, CRISPR/Cas9 knockout, mRNA rescue, and high-speed video microscopy in zebrafish","pmids":["30475641"],"confidence":"High","gaps":["Molecular step in cilia assembly disrupted not pinpointed","Cilia motility defect mechanism not resolved"]},{"year":2021,"claim":"Demonstrated CEP20 is required for mammalian embryonic development, laterality, node ciliogenesis, and angiogenesis, extending its essentiality to mammals.","evidence":"Homozygous knockout mouse with immunofluorescence and embryo morphological analysis","pmids":["33686659"],"confidence":"High","gaps":["Tissue-specific requirements not dissected","Connection between ciliary and angiogenic phenotypes unexplained"]},{"year":2023,"claim":"Implicated CEP20 in cancer cell behavior by showing its depletion impairs proliferation, migration, and microtubule polymerization in NSCLC cells.","evidence":"siRNA knockdown, overexpression, microtubule polymerization, migration, and proliferation assays in NSCLC lines","pmids":["37838783"],"confidence":"Medium","gaps":["Adhesion-related signaling pathway not molecularly defined","Single lab; limited mechanistic detail"]},{"year":2025,"claim":"Defined a PLK1-CEP20-CCDC116 axis in which Ser46 phosphorylation enables CCDC116 recruitment and centriole overduplication, linking CEP20 regulation to centrosome amplification.","evidence":"S46A site-directed mutagenesis, Co-IP, phosphorylation assays, and centrosome amplification assays with CEP20/CCDC116 knockdown","pmids":["41401801"],"confidence":"Medium","gaps":["Not independently replicated","Structural basis of phospho-dependent CCDC116 binding unknown","Relationship to CEP20's Plk1-recruitment role unclear"]},{"year":null,"claim":"How CEP20 coordinates its distinct activities — satellite organization, transition zone assembly, Plk1 recruitment, and direct microtubule regulation — into a unified regulatory program remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structure of CEP20 or its complexes","Regulatory hierarchy among its functions undefined","Whether S100/Ca2+ and PLK1 phosphorylation cross-regulate these activities unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[4,5]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,3]}],"localization":[{"term_id":"GO:0005815","term_label":"microtubule organizing center","supporting_discovery_ids":[0,1,3]},{"term_id":"GO:0005929","term_label":"cilium","supporting_discovery_ids":[1,8]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[4,5]}],"pathway":[{"term_id":"R-HSA-1852241","term_label":"Organelle biogenesis and maintenance","supporting_discovery_ids":[0,1,8]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[2,11]}],"complexes":["CEP20-OFIP(KIAA0753)-OFD1 ternary complex"],"partners":["PCM1","PLK1","KIAA0753","OFD1","S100A6","CCDC116","CEN2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q96NB1","full_name":"Centrosomal protein 20","aliases":["FGFR1OP N-terminal-like protein","FOP-related protein of 20 kDa","LisH domain-containing protein FOPNL"],"length_aa":174,"mass_kda":19.8,"function":"Involved in the biogenesis of cilia (PubMed:20551181). Required for the recruitment of PLK1 to centrosomes and S phase progression (PubMed:24018379)","subcellular_location":"Cytoplasm, cytoskeleton, microtubule organizing center, centrosome, centriole; Cell projection, cilium; Cytoplasm, cytoskeleton, cilium basal body; Cytoplasm, cytoskeleton, microtubule organizing center, centrosome; Cytoplasmic granule; Cytoplasm, cytoskeleton, microtubule organizing center, centrosome, centriolar satellite","url":"https://www.uniprot.org/uniprotkb/Q96NB1/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CEP20","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/CEP20","total_profiled":1310},"omim":[{"mim_id":"617149","title":"CENTROSOMAL PROTEIN 20; CEP20","url":"https://www.omim.org/entry/617149"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Centriolar satellite","reliability":"Supported"},{"location":"Centrosome","reliability":"Supported"},{"location":"Basal body","reliability":"Supported"},{"location":"Nucleoplasm","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/CEP20"},"hgnc":{"alias_symbol":["DKFZp686N1651","FLJ31153","PHSECRG2","FOR20"],"prev_symbol":["C16orf63","FOPNL"]},"alphafold":{"accession":"Q96NB1","domains":[{"cath_id":"1.20.960","chopping":"46-118","consensus_level":"medium","plddt":86.9649,"start":46,"end":118},{"cath_id":"1.10.287","chopping":"2-39","consensus_level":"medium","plddt":89.0874,"start":2,"end":39}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96NB1","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q96NB1-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q96NB1-F1-predicted_aligned_error_v6.png","plddt_mean":73.75},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CEP20","jax_strain_url":"https://www.jax.org/strain/search?query=CEP20"},"sequence":{"accession":"Q96NB1","fasta_url":"https://rest.uniprot.org/uniprotkb/Q96NB1.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q96NB1/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96NB1"}},"corpus_meta":[{"pmid":"20551181","id":"PMC_20551181","title":"Control of ciliogenesis by FOR20, a novel centrosome and pericentriolar satellite protein.","date":"2010","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/20551181","citation_count":48,"is_preprint":false},{"pmid":"26643951","id":"PMC_26643951","title":"OFIP/KIAA0753 forms a complex with OFD1 and FOR20 at pericentriolar satellites and centrosomes and is mutated in one individual with oral-facial-digital syndrome.","date":"2015","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/26643951","citation_count":39,"is_preprint":false},{"pmid":"22718349","id":"PMC_22718349","title":"The conserved centrosomal protein FOR20 is required for assembly of the transition zone and basal body docking at the cell surface.","date":"2012","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/22718349","citation_count":38,"is_preprint":false},{"pmid":"24018379","id":"PMC_24018379","title":"Centrosomal protein FOR20 is essential for S-phase progression by recruiting Plk1 to centrosomes.","date":"2013","source":"Cell research","url":"https://pubmed.ncbi.nlm.nih.gov/24018379","citation_count":31,"is_preprint":false},{"pmid":"28884019","id":"PMC_28884019","title":"Microtubule-binding protein FOR20 promotes microtubule depolymerization and cell migration.","date":"2017","source":"Cell discovery","url":"https://pubmed.ncbi.nlm.nih.gov/28884019","citation_count":16,"is_preprint":false},{"pmid":"30475641","id":"PMC_30475641","title":"Centrosomal protein FOR20 is essential for cilia-dependent development in zebrafish embryos.","date":"2018","source":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/30475641","citation_count":11,"is_preprint":false},{"pmid":"28765046","id":"PMC_28765046","title":"Identification and characterization of a centrosomal protein, FOR20 as a novel S100A6 target.","date":"2017","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/28765046","citation_count":8,"is_preprint":false},{"pmid":"28694353","id":"PMC_28694353","title":"A centrosomal protein FOR20 regulates microtubule assembly dynamics and plays a role in cell migration.","date":"2017","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/28694353","citation_count":8,"is_preprint":false},{"pmid":"28822909","id":"PMC_28822909","title":"Variation in Basal Body Localisation and Targeting of Trypanosome RP2 and FOR20 Proteins.","date":"2017","source":"Protist","url":"https://pubmed.ncbi.nlm.nih.gov/28822909","citation_count":7,"is_preprint":false},{"pmid":"37838783","id":"PMC_37838783","title":"CEP20 promotes invasion and metastasis of non-small cell lung cancer cells by depolymerizing microtubules.","date":"2023","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/37838783","citation_count":3,"is_preprint":false},{"pmid":"33686659","id":"PMC_33686659","title":"Centrosomal protein FOR20 knockout mice display embryonic lethality and left-right patterning defects.","date":"2021","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/33686659","citation_count":2,"is_preprint":false},{"pmid":"41401801","id":"PMC_41401801","title":"Nε-Carboxymethyl-Lysine Drives Centrosome Amplification and Hepatocarcinogenesis via Pathological Dysregulation of the PLK1-CEP20-CCDC116 Axis.","date":"2025","source":"Journal of agricultural and food chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/41401801","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7470,"output_tokens":3339,"usd":0.036248,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":10828,"output_tokens":3701,"usd":0.073332,"stage2_stop_reason":"end_turn"},"total_usd":0.10958,"stage1_batch_id":"msgbatch_01ACAxJQabDsht39JXeWG22d","stage2_batch_id":"msgbatch_01QEU22A9U5sbPTgsMzTmvSf","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2010,\n      \"finding\": \"FOR20 (CEP20) localizes to PCM1-enriched pericentriolar satellites and centrosomes. Its LisH domain promotes self-interaction and is required for satellite localization. Knockdown in RPE1 cells decreases the percentage of ciliated cells and cilium length, displaces PCM1 from detergent-insoluble to detergent-soluble fractions, and modifies satellite distribution, suggesting FOR20 regulates PCM1 satellite interaction with microtubules and motors.\",\n      \"method\": \"siRNA knockdown, detergent fractionation, immunofluorescence, domain mutagenesis (LisH domain)\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (fractionation, immunofluorescence, domain mutants, knockdown with defined phenotypic readout), replicated in subsequent studies\",\n      \"pmids\": [\"20551181\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"In Paramecium, the FOR20 ortholog PtFOR20p localizes specifically at basal bodies and is required to build the transition zone, which is a prerequisite for basal body maturation and docking at the cell surface. Centrin PtCen2p (ortholog of human Cen2) is required to recruit PtFOR20p to the developing basal body and to control its length.\",\n      \"method\": \"RNAi knockdown in Paramecium, electron microscopy, immunofluorescence, functional and cytological analyses\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — combined functional and cytological analyses with defined structural phenotypes, ortholog of CEP20 in established ciliate model\",\n      \"pmids\": [\"22718349\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"FOR20 (CEP20) interacts with Plk1 at centrosomes and is required for recruitment of Plk1 to centrosomes. Depletion of FOR20 inhibits S-phase progression; this defect is rescued by ectopic expression of centrosome-tethered Plk1 (but not wild-type Plk1), independently of Plk1 kinase activity, establishing that centrosomal recruitment of Plk1 by FOR20 licenses efficient S-phase progression.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown, rescue experiments with centrosome-tethered and kinase-dead Plk1 mutants, cell cycle analysis\",\n      \"journal\": \"Cell research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, multiple mutant rescue experiments with defined cell cycle phenotype, mechanistic pathway placement established\",\n      \"pmids\": [\"24018379\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"FOR20 (CEP20) forms a ternary complex with KIAA0753/OFIP and OFD1 at pericentriolar satellites and centrosomes. Decreased expression of any component of this ternary complex causes defective recruitment of the others to centrosomes and satellites. An OFD syndrome-associated KIAA0753 mutant loses the capacity to interact with FOR20 and OFD1.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence, siRNA knockdown, patient mutation analysis\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP defining ternary complex, knockdown phenotypes with multiple components, patient mutant validation\",\n      \"pmids\": [\"26643951\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"FOR20 (CEP20) directly binds to microtubules and free tubulin dimers in vitro, and preferentially interacts with free tubulin dimers over microtubules. FOR20 decreases the microtubule growth rate, increases the depolymerization rate and catastrophe frequency in vitro. Depletion of FOR20 inhibits microtubule depolymerization and promotes microtubule regrowth after nocodazole washout in HeLa cells. FOR20 knockdown also inhibits both individual and collective cell migration.\",\n      \"method\": \"In vitro microtubule dynamics assays, direct microtubule binding assay, live-cell imaging of microtubule dynamics, siRNA knockdown, nocodazole washout assay, cell migration assay\",\n      \"journal\": \"Cell discovery\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with direct binding and dynamics assays, complemented by cell-based knockdown phenotypes and live imaging\",\n      \"pmids\": [\"28884019\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"FOR20 (CEP20) binds to tubulin: both anti-FOR20 antibody and GST-FOR20 precipitate tubulin from HeLa cell extract; FOR20 co-cycles with microtubule-associated proteins from brain tissue. Purified FOR20 inhibits tubulin assembly in vitro. Overexpression of FOR20 depolymerizes interphase microtubules; depletion prevents nocodazole-induced depolymerization and suppresses microtubule dynamics in live HeLa cells. FOR20-depleted MDA-MB-231 cells show impaired directed migration.\",\n      \"method\": \"GST pulldown, co-sedimentation assay with MAPs from brain tissue, in vitro tubulin polymerization assay, live-cell microtubule imaging, siRNA knockdown, cell migration assay\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution of tubulin binding and assembly inhibition, multiple orthogonal cell-based assays, independently corroborated by PMID 28884019\",\n      \"pmids\": [\"28694353\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"S100A6 interacts with the N-terminal region (residues 1–30) of FOR20 (CEP20) in a Ca2+-dependent manner, both in vitro and in living cells. Multiple S100 family members (S100A1, A2, A4, A11, B) also bind FOR20 Ca2+-dependently. Related centrosomal proteins FOP and OFD1 share sequence similarity in this N-terminal region and also bind S100A6 Ca2+-dependently.\",\n      \"method\": \"Protein microarray screen, in vitro binding assay, co-immunoprecipitation in living cells, domain mapping (residues 1–30)\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — protein microarray identification plus in vitro and cell-based binding confirmation with domain mapping, single lab\",\n      \"pmids\": [\"28765046\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"In Trypanosoma brucei, TbFOR20 (ortholog of CEP20) localizes to both pro-basal bodies and mature basal bodies, distal to TbRP2. A short negatively-charged N-terminal extension unique to African trypanosomes is necessary for correct protein targeting but insufficient to redirect TbRP2 to pro-basal bodies.\",\n      \"method\": \"Immunofluorescence localization, epitope-tagging, heterologous expression of T. cruzi FOR20 in T. brucei\",\n      \"journal\": \"Protist\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization experiment with domain targeting analysis, single lab, ortholog context\",\n      \"pmids\": [\"28822909\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"FOR20 (CEP20) is required for normal ciliogenesis in vertebrate development. Morpholino-mediated knockdown and CRISPR/Cas9 knockout of for20 in zebrafish produce ciliary phenotypes (curved body, hydrocephaly, pericardial edema, kidney cysts, left-right asymmetry defects), reduced cilia number and length in Kupffer's vesicle and pronephric ducts, and paralyzed or arrhythmic cilia beating. All phenotypes are rescued by exogenous for20 mRNA.\",\n      \"method\": \"Morpholino knockdown, CRISPR/Cas9 knockout, mRNA rescue, high-speed video microscopy, immunofluorescence in zebrafish\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — two independent loss-of-function approaches (morpholino + CRISPR) with defined phenotypes and mRNA rescue, in vertebrate model\",\n      \"pmids\": [\"30475641\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Homozygous knockout of For20 in mice causes embryonic growth arrest and lethality during gestation, impaired left-right patterning of embryos, reduced cilia in the embryonic node, and disrupted angiogenesis in yolk sacs and embryos. Heterozygous knockout mice show no obvious defects.\",\n      \"method\": \"Gene-targeting homozygous knockout mouse, immunofluorescence for cilia, embryo morphological analysis\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean homozygous knockout with multiple defined phenotypic readouts (lethality, laterality, ciliogenesis, angiogenesis) in mammalian model\",\n      \"pmids\": [\"33686659\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"CEP20 depletion inhibits NSCLC cell proliferation, migration, and microtubule polymerization. Knockdown or overexpression of CEP20 reciprocally affects microtubule polymerization in A549 cells, and CEP20 regulates cell adhesion-related signaling pathways.\",\n      \"method\": \"siRNA knockdown, overexpression, microtubule polymerization assay, cell migration and proliferation assays in NSCLC cell lines\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — cell-based knockdown/overexpression with phenotypic readouts, limited mechanistic detail in abstract, single lab corroborating prior findings\",\n      \"pmids\": [\"37838783\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"PLK1-dependent phosphorylation of CEP20 at Ser46 enables high-affinity binding to CCDC116 and centrosomal recruitment of CCDC116, driving centriole overduplication. The CEP20-S46A mutation abolishes CCDC116 centrosomal localization and centrosome amplification. PLK1 upregulation (via EGR1) and CEP20 promoter hypomethylation (via DNMT3B suppression) together activate this PLK1-CEP20-CCDC116 axis.\",\n      \"method\": \"Site-directed mutagenesis (S46A), co-immunoprecipitation, centrosome amplification assays, knockdown of CCDC116 and CEP20, phosphorylation assays\",\n      \"journal\": \"Journal of agricultural and food chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mutagenesis and Co-IP establish phosphorylation-dependent interaction, single lab, mechanistic pathway defined but not independently replicated\",\n      \"pmids\": [\"41401801\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CEP20 (FOR20) is a conserved centrosomal and pericentriolar satellite protein that (1) promotes ciliogenesis by building the transition zone and organizing PCM1 satellites via its LisH-domain-mediated self-interaction; (2) recruits Plk1 to centrosomes to license S-phase progression; (3) functions as a microtubule-associated protein that directly binds tubulin and promotes microtubule depolymerization, thereby facilitating directed cell migration; (4) forms a ternary complex with OFD1 and OFIP at satellites/centrosomes; (5) is regulated by Ca2+-dependent S100 protein binding at its N-terminal domain; and (6) is phosphorylated by PLK1 at Ser46, enabling CCDC116 binding and centrosomal recruitment that drives centriole overduplication.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CEP20 (FOR20) is a conserved centrosomal and pericentriolar satellite protein that organizes the ciliary apparatus and centrosome-associated cell cycle and migration machinery [#0, #8]. It localizes to PCM1-enriched satellites and centrosomes, where its LisH domain drives self-interaction and is required for satellite targeting and for the proper interaction of PCM1 satellites with microtubules [#0]; in this context CEP20 assembles into a ternary complex with KIAA0753/OFIP and OFD1, with each component required to recruit the others, and an OFD-syndrome-associated KIAA0753 mutation disrupts CEP20 binding [#3]. CEP20 is essential for ciliogenesis: it builds the transition zone required for basal body maturation and docking [#1], and its loss in zebrafish and mice produces hallmark ciliopathy phenotypes including left-right asymmetry defects, reduced cilia number and length, and embryonic lethality [#8, #9]. At the centrosome CEP20 also licenses cell cycle progression by recruiting Plk1, a function rescued by centrosome-tethered but kinase-dead Plk1 and therefore independent of Plk1 catalytic activity [#2]. Independently, CEP20 acts as a microtubule-associated protein that directly binds free tubulin dimers and microtubules, inhibits tubulin assembly, and promotes depolymerization and catastrophe, thereby supporting directed cell migration [#4, #5]. Its activity is modulated by Ca2+-dependent binding of S100 proteins to its N-terminal region (residues 1-30) [#6], and PLK1 phosphorylation at Ser46 enables CCDC116 binding and centrosomal recruitment that drives centriole overduplication [#11].\",\n  \"teleology\": [\n    {\n      \"year\": 2010,\n      \"claim\": \"Established CEP20 as a satellite/centrosome protein whose LisH-mediated self-interaction organizes PCM1 satellites and supports ciliogenesis, defining its baseline cellular role.\",\n      \"evidence\": \"siRNA knockdown, detergent fractionation, immunofluorescence, and LisH-domain mutagenesis in RPE1 cells\",\n      \"pmids\": [\"20551181\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve how satellites physically engage microtubules/motors\", \"Direct binding partners at satellites not yet identified\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Showed the ortholog functions in basal body biology by building the transition zone required for basal body maturation and docking, placing CEP20 upstream of ciliary assembly.\",\n      \"evidence\": \"RNAi knockdown, electron microscopy, and immunofluorescence in Paramecium\",\n      \"pmids\": [\"22718349\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular interactions building the transition zone not defined\", \"Conservation of centrin-dependent recruitment in vertebrates not tested\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Linked CEP20 to cell cycle control by demonstrating it recruits Plk1 to centrosomes to license S-phase progression, separating a structural recruitment role from Plk1 catalytic activity.\",\n      \"evidence\": \"Reciprocal Co-IP, siRNA knockdown, and rescue with centrosome-tethered and kinase-dead Plk1 mutants with cell cycle analysis\",\n      \"pmids\": [\"24018379\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which centrosomal Plk1 promotes S-phase entry not detailed\", \"Whether recruitment is direct or complex-mediated not fully resolved\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Defined a CEP20-OFIP-OFD1 ternary complex and tied it to disease by showing an OFD-associated KIAA0753 mutant loses CEP20/OFD1 binding, embedding CEP20 in a ciliopathy-relevant module.\",\n      \"evidence\": \"Co-IP, immunofluorescence, siRNA knockdown of multiple components, and patient mutation analysis\",\n      \"pmids\": [\"26643951\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry and structure of the ternary complex unknown\", \"Functional output of the complex beyond mutual recruitment not defined\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Reclassified CEP20 as a microtubule-regulating protein by reconstituting direct tubulin/microtubule binding and assembly inhibition, connecting this activity to directed cell migration.\",\n      \"evidence\": \"In vitro microtubule dynamics and direct-binding assays, GST pulldown, co-cycling with brain MAPs, live-cell imaging, nocodazole washout, and migration assays in HeLa and MDA-MB-231 cells (two independent studies)\",\n      \"pmids\": [\"28884019\", \"28694353\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Tubulin-binding region/structural basis not mapped\", \"How microtubule regulation integrates with satellite/ciliary functions unclear\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Identified Ca2+-dependent S100 protein binding to the CEP20 N-terminus, introducing a calcium-signaling input that could regulate CEP20 function.\",\n      \"evidence\": \"Protein microarray screen, in vitro binding, Co-IP in living cells, and domain mapping to residues 1-30\",\n      \"pmids\": [\"28765046\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of S100 binding on ciliogenesis/microtubules not tested\", \"Single lab; physiological Ca2+ context undefined\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Mapped ortholog localization to pro- and mature basal bodies and identified lineage-specific N-terminal targeting determinants, refining where CEP20 acts at the centriole.\",\n      \"evidence\": \"Immunofluorescence, epitope-tagging, and heterologous expression in Trypanosoma brucei\",\n      \"pmids\": [\"28822909\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Targeting mechanism in vertebrate cells not addressed\", \"Single lab, ortholog-specific context\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Confirmed an essential ciliogenesis role in a vertebrate by linking CEP20 loss to characteristic ciliopathy phenotypes with mRNA rescue, establishing in vivo relevance.\",\n      \"evidence\": \"Morpholino knockdown, CRISPR/Cas9 knockout, mRNA rescue, and high-speed video microscopy in zebrafish\",\n      \"pmids\": [\"30475641\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular step in cilia assembly disrupted not pinpointed\", \"Cilia motility defect mechanism not resolved\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Demonstrated CEP20 is required for mammalian embryonic development, laterality, node ciliogenesis, and angiogenesis, extending its essentiality to mammals.\",\n      \"evidence\": \"Homozygous knockout mouse with immunofluorescence and embryo morphological analysis\",\n      \"pmids\": [\"33686659\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Tissue-specific requirements not dissected\", \"Connection between ciliary and angiogenic phenotypes unexplained\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Implicated CEP20 in cancer cell behavior by showing its depletion impairs proliferation, migration, and microtubule polymerization in NSCLC cells.\",\n      \"evidence\": \"siRNA knockdown, overexpression, microtubule polymerization, migration, and proliferation assays in NSCLC lines\",\n      \"pmids\": [\"37838783\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Adhesion-related signaling pathway not molecularly defined\", \"Single lab; limited mechanistic detail\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Defined a PLK1-CEP20-CCDC116 axis in which Ser46 phosphorylation enables CCDC116 recruitment and centriole overduplication, linking CEP20 regulation to centrosome amplification.\",\n      \"evidence\": \"S46A site-directed mutagenesis, Co-IP, phosphorylation assays, and centrosome amplification assays with CEP20/CCDC116 knockdown\",\n      \"pmids\": [\"41401801\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Not independently replicated\", \"Structural basis of phospho-dependent CCDC116 binding unknown\", \"Relationship to CEP20's Plk1-recruitment role unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How CEP20 coordinates its distinct activities — satellite organization, transition zone assembly, Plk1 recruitment, and direct microtubule regulation — into a unified regulatory program remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structure of CEP20 or its complexes\", \"Regulatory hierarchy among its functions undefined\", \"Whether S100/Ca2+ and PLK1 phosphorylation cross-regulate these activities unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [4, 5]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005815\", \"supporting_discovery_ids\": [0, 1, 3]},\n      {\"term_id\": \"GO:0005929\", \"supporting_discovery_ids\": [1, 8]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [4, 5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1852241\", \"supporting_discovery_ids\": [0, 1, 8]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [2, 11]}\n    ],\n    \"complexes\": [\"CEP20-OFIP(KIAA0753)-OFD1 ternary complex\"],\n    \"partners\": [\"PCM1\", \"PLK1\", \"KIAA0753\", \"OFD1\", \"S100A6\", \"CCDC116\", \"CEN2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}