{"gene":"CEP250","run_date":"2026-06-09T22:57:18","timeline":{"discoveries":[{"year":1998,"finding":"C-Nap1 (CEP250) was identified as a novel centrosomal coiled-coil protein that localizes specifically to the proximal ends of both mother and daughter centrioles. It was first identified as a Nek2-interacting protein in a yeast two-hybrid screen, and its C-terminal domain can be phosphorylated by Nek2 in vitro and after coexpression in vivo.","method":"Yeast two-hybrid screen, immunofluorescence, immunoelectron microscopy, in vitro kinase assay, co-expression in vivo","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — multiple orthogonal methods (yeast two-hybrid, immunoelectron microscopy, in vitro kinase assay), foundational paper replicated by subsequent studies","pmids":["9647649"],"is_preprint":false},{"year":2000,"finding":"C-Nap1 is a key component of a dynamic, cell cycle-regulated structure that mediates centriole-centriole cohesion during interphase. Antibody-mediated interference with C-Nap1 function causes centrosome splitting independent of microtubule or microfilament networks, and C-Nap1 dissociates from spindle poles during mitosis and reaccumulates at centrosomes at the end of cell division.","method":"Antibody microinjection/interference, immunofluorescence, immunoelectron microscopy, overexpression of truncated mutants","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal loss-of-function and structural approaches; independently confirmed by subsequent studies","pmids":["11076968"],"is_preprint":false},{"year":2002,"finding":"Dissociation of C-Nap1 from mitotic centrosomes is regulated by M-phase-specific phosphorylation rather than ubiquitin-dependent proteolysis. Overexpression of active Nek2 substantially reduced formation of large C-Nap1 centrosome-associated structures, implicating Nek2 kinase as the key activity driving C-Nap1 centrosome dissociation at mitotic entry.","method":"Western blot cell cycle analysis, proteasome inhibitor treatment, Xenopus extract destruction assays, co-expression of active Nek2, immunofluorescence","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (proteasome inhibitors, Xenopus extracts, Nek2 co-expression) in single lab","pmids":["12140259"],"is_preprint":false},{"year":2005,"finding":"Rootletin interacts with C-Nap1 in vivo, colocalizes at basal bodies/centrioles, and functions as a physical linker between centriole pairs by binding to C-Nap1 at the proximal centriole ends. Transient expression of C-Nap1 fragments dissociated rootletin fibers from centrioles, resulting in centrosome separation.","method":"Co-immunoprecipitation, colocalization by immunofluorescence, ultrastructural analysis, transient overexpression of C-Nap1 fragments","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal co-IP plus ultrastructural analysis plus functional perturbation; replicated by subsequent linker structure studies","pmids":["16339073"],"is_preprint":false},{"year":2008,"finding":"CEP135 acts as a platform protein for C-NAP1 at the centriole. Depletion of CEP135 caused premature centrosome splitting accompanied by a specific reduction in centrosomal C-NAP1 levels, and ectopic expression of CEP135 mutant proteins caused the same effect.","method":"siRNA depletion, overexpression of CEP135 mutants, immunofluorescence, Western blot","journal":"Experimental cell research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function with defined cellular phenotype plus mutant overexpression, single lab","pmids":["18851962"],"is_preprint":false},{"year":2012,"finding":"C-NAP1 and rootletin restrain DNA damage-induced centriole splitting. siRNA depletion of C-NAP1 increased radiation-induced centriole splitting and reduced primary cilium formation, establishing C-NAP1 as part of the centriole cohesion apparatus required for normal ciliogenesis.","method":"siRNA knockdown, immunofluorescence, irradiation-induced centriole splitting assay, cilium formation assay","journal":"Cell cycle (Georgetown, Tex.)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean siRNA KD with defined cellular phenotypes (centriole splitting and ciliogenesis), single lab","pmids":["23070519"],"is_preprint":false},{"year":2014,"finding":"Centlein directly interacts with both C-Nap1 and Cep68 and functions as a molecular link between them at the proximal ends of centrioles during interphase. Depletion of centlein impairs recruitment of Cep68 to centrosomes and causes centrosome splitting. Both centlein and Cep68 are Nek2A substrates.","method":"Co-immunoprecipitation, immunofluorescence colocalization, siRNA depletion, in vitro kinase assay","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Moderate — direct interaction shown by co-IP plus loss-of-function phenotype plus in vitro kinase assay; multiple orthogonal methods","pmids":["24554434"],"is_preprint":false},{"year":2014,"finding":"Nek2 phosphorylates multiple residues within the C-terminal domain of C-Nap1, and these multisite phosphorylation events lead to loss of C-Nap1 oligomerization and centrosome association. Phosphorylation also perturbs interaction with the core centriolar protein Cep135, and endogenous C-Nap1–Cep135 interaction is specifically lost in mitosis.","method":"In vitro kinase assay with mutagenesis, co-immunoprecipitation, cell cycle synchronization, immunofluorescence, phosphomimetic mutant analysis","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — in vitro kinase assay with mutagenesis combined with reciprocal co-IP and cell-cycle-dependent interaction analysis; multiple orthogonal methods","pmids":["24695856"],"is_preprint":false},{"year":2015,"finding":"ASPP1 and ASPP2 interact with C-Nap1 and facilitate centrosome linker reassembly at the end of mitosis. ASPP1/2 facilitate the interaction between C-Nap1 and PP1α, and this interaction was reduced by co-depletion of ASPP1/2. ASPP1/2 antagonize NEK2A-mediated C-Nap1 Ser2417/2421 phosphorylation in a PP1-dependent manner, and co-depletion of ASPP1/2 inhibited dephosphorylation of C-Nap1 at the end of mitosis.","method":"Co-immunoprecipitation, siRNA co-depletion, immunofluorescence, phospho-specific antibody western blot","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP plus functional knockdown with phosphorylation readout, single lab, two orthogonal methods","pmids":["25660448"],"is_preprint":false},{"year":2015,"finding":"A truncating mutation in CEP250/C-Nap1 in cattle causes centrosome splitting and an altered cell migration phenotype, without affecting centriole ultrastructure, duplication, ciliogenesis, or mitotic spindle organization, establishing that C-Nap1-mediated centriole cohesion is specifically required for cell migration.","method":"Genetic identification of truncating mutation, immunofluorescence, electron microscopy, cell migration assay in primary cells","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — natural loss-of-function allele with defined centrosomal and cell migration phenotypes; single study but multiple cellular readouts","pmids":["25902731"],"is_preprint":false},{"year":2017,"finding":"C-NAP1-null cells generated by genome editing show premature centriole separation, reduced density of centriolar satellites, and markedly reduced centrosome amplification induced by DNA damage or PLK4/CDK2 overexpression. Reexpression of C-NAP1 rescued both centriole separation and centriolar satellite density phenotypes.","method":"CRISPR/Cas9 genome editing, rescue by reexpression, immunofluorescence, centrosome amplification assays","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean null cells by genome editing with rescue, multiple orthogonal functional readouts","pmids":["28100636"],"is_preprint":false},{"year":2018,"finding":"STED super-resolution microscopy revealed that C-Nap1 forms a ring at the proximal end of each centriole, organizing a rootletin ring and multiple rootletin/CEP68 fibers. The centrosome linker consists of a vast network of repeating rootletin units with C-Nap1 as ring organizer and CEP68 as filament modulator.","method":"STED (stimulated emission depletion) nanoscopy, immunofluorescence, co-immunoprecipitation","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct structural visualization by STED nanoscopy combined with Co-IP to confirm binding; single lab but rigorous super-resolution structural approach","pmids":["29463719"],"is_preprint":false},{"year":2019,"finding":"Disruption of Cep250 in a knockin mouse resulted in severe impairment of retinal function and significant retinal morphological alterations, establishing that CEP250 is required for photoreceptor function in vivo.","method":"Cep250 knockin mouse model, electroretinography, histological analysis","journal":"Human mutation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo loss-of-function model with functional (ERG) and structural readouts; single lab","pmids":["30998843"],"is_preprint":false},{"year":2022,"finding":"CEP250-null male mice are infertile due to premature centrosome separation in germ cells, causing failure to establish E-cadherin polarity and inability to maintain the older mother centrosome at the basal site of seminiferous tubules, prompting premature stem cell differentiation and depletion of germ stem cells.","method":"CEP250 knockout mouse, immunofluorescence, E-cadherin polarity assay, centrosome position analysis","journal":"EMBO reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean KO with defined mechanism linking centrosome cohesion to asymmetric cell division polarity; mechanistic pathway established by multiple readouts","pmids":["35599622"],"is_preprint":false},{"year":2022,"finding":"Cep250-/- mice show male infertility due to reduction in the spermatogonial pool and meiotic blockade at pachytene-like stage, with precocious centrosome splitting in meiocytes and abnormal γH2AX staining indicating unrepaired DNA double-strand breaks and synapsis defects.","method":"CEP250 knockout mouse, immunofluorescence, TUNEL assay, γH2AX staining, meiotic spread analysis","journal":"Frontiers in cell and developmental biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO with defined phenotypic readouts in germline; single lab, consistent with EMBO reports study","pmids":["35127699"],"is_preprint":false},{"year":2023,"finding":"A truncating nonsense variant in CEP250 (p.Gln1171Ter) causes mislocalization of C-Nap1 protein away from the centrosome to the cytosol, and Cep250 knockout mice show hair cell degeneration and progressive hearing loss, establishing CEP250 function at the centrosome is required for cochlear hair cell maintenance.","method":"Heterologous expression of truncating variant in NIH3T3 cells with immunofluorescence, Cep250 knockout mouse, auditory brainstem response","journal":"Cells","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — variant localization experiment plus in vivo KO model; single lab, two complementary approaches","pmids":["37759551"],"is_preprint":false},{"year":2023,"finding":"In Cep250 knockout mice, outer segment proteins are mislocalized to the outer nuclear layer, and untargeted metabolomics revealed dysregulated arginine metabolism with mislocalization of arginase 1 (ARG1). AAV-mediated retinal knockdown of Arg1 in wild-type mice recapitulated retinal degeneration, linking CEP250-dependent photoreceptor cilium gating to arginine metabolism.","method":"Cep250 KO mouse, immunofluorescence for OS proteins, untargeted metabolomics, AAV-mediated Arg1 knockdown","journal":"Investigative ophthalmology & visual science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO model with metabolomics and functional rescue-by-phenocopy experiment; single lab, multiple orthogonal methods","pmids":["37656476"],"is_preprint":false},{"year":2024,"finding":"A homozygous frameshift mutation in CEP250 (c.4710_4723del, p.E1570fs*39) causes acephalic spermatozoa syndrome. The mutant CEP250 protein shows decreased signal in the sperm neck region and reduced co-immunoprecipitation with SUN5 and PMFBP1, likely due to absence of the 2272-2442 amino acid region.","method":"Whole-exome sequencing, immunofluorescence, co-immunoprecipitation, Western blot, CRISPR-Cas9 knockin mouse","journal":"Andrology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP interaction studies combined with patient immunofluorescence and KI mouse; single lab","pmids":["39726222"],"is_preprint":false}],"current_model":"CEP250/C-Nap1 is a large coiled-coil protein that localizes as a ring at the proximal ends of centrioles and anchors rootletin/CEP68 filaments to form the interphase centrosome linker, maintaining centriole-centriole cohesion; at mitotic entry, Nek2 phosphorylates multiple C-terminal residues of C-Nap1, disrupting its oligomerization and its interaction with the scaffold protein Cep135, causing linker disassembly (centrosome disjunction), while linker reassembly at mitotic exit requires ASPP1/2-mediated PP1α-dependent dephosphorylation of C-Nap1; loss of C-Nap1-mediated cohesion impairs asymmetric stem cell division, cell migration, centriolar satellite organization, centrosome amplification, photoreceptor cilium gating, and male germ cell development."},"narrative":{"mechanistic_narrative":"CEP250 (C-Nap1) is a large centrosomal coiled-coil protein that builds the interphase centrosome linker, holding the two centrioles of a centrosome together until mitotic entry [PMID:9647649, PMID:11076968]. It localizes specifically to the proximal ends of both mother and daughter centrioles, where STED nanoscopy shows it forms a ring that organizes a rootletin ring and the rootletin/CEP68 fibers constituting the linker network [PMID:9647649, PMID:29463719]. C-Nap1 is docked at the centriole through CEP135, which acts as a platform for its centrosomal recruitment, and it anchors rootletin and CEP68 to the proximal ends, with centlein bridging C-Nap1 to CEP68 [PMID:16339073, PMID:18851962, PMID:24554434]. Centriole cohesion is controlled by cell-cycle phosphorylation: at mitotic entry Nek2 phosphorylates multiple residues in the C-terminal domain of C-Nap1, abolishing its oligomerization and centrosome association and disrupting its interaction with Cep135, thereby driving linker disassembly and centrosome disjunction [PMID:12140259, PMID:24695856]; at the end of mitosis ASPP1/2 recruit PP1α to dephosphorylate C-Nap1 and restore the linker [PMID:25660448]. Loss of C-Nap1-mediated cohesion causes premature centriole splitting and reduces centriolar satellite density and DNA-damage- or PLK4/CDK2-driven centrosome amplification [PMID:28100636]. In vivo, CEP250 cohesion function is required for cell migration, photoreceptor and cochlear hair-cell maintenance, and male germ cell development, where it supports asymmetric stem-cell division by maintaining E-cadherin polarity and basal positioning of the mother centrosome [PMID:25902731, PMID:30998843, PMID:35599622, PMID:37759551]; a homozygous frameshift mutation that disrupts its association with SUN5 and PMFBP1 causes acephalic spermatozoa syndrome [PMID:39726222].","teleology":[{"year":1998,"claim":"Established the existence and location of the protein, defining C-Nap1 as a Nek2-interacting centrosomal coiled-coil protein at centriole proximal ends and immediately linking it to a kinase.","evidence":"Yeast two-hybrid screen, immunoelectron microscopy, and in vitro kinase assay","pmids":["9647649"],"confidence":"High","gaps":["Functional consequence of Nek2 phosphorylation not yet defined","No binding partners at the centriole identified"]},{"year":2000,"claim":"Answered what C-Nap1 does by showing it mediates centriole-centriole cohesion in a cell-cycle-regulated manner independent of cytoskeletal networks.","evidence":"Antibody microinjection/interference and truncated mutant overexpression with immunofluorescence and immunoEM","pmids":["11076968"],"confidence":"High","gaps":["Molecular nature of the physical linker not identified","Mechanism of mitotic dissociation unresolved"]},{"year":2002,"claim":"Distinguished phosphorylation from proteolysis as the mechanism of mitotic dissociation, implicating Nek2 activity as the driver of linker disassembly.","evidence":"Proteasome inhibitor treatment, Xenopus extract destruction assays, and active Nek2 co-expression","pmids":["12140259"],"confidence":"High","gaps":["Specific phosphorylated residues not mapped","Counteracting phosphatase not identified"]},{"year":2005,"claim":"Identified the physical linker filament by showing rootletin binds C-Nap1 at proximal centriole ends and is dislodged when C-Nap1 is perturbed.","evidence":"Co-immunoprecipitation, colocalization, ultrastructural analysis, and C-Nap1 fragment overexpression","pmids":["16339073"],"confidence":"High","gaps":["Stoichiometry and architecture of the linker not resolved","How rootletin docks onto C-Nap1 unclear"]},{"year":2008,"claim":"Defined how C-Nap1 is anchored at the centriole, identifying CEP135 as the platform required for its centrosomal retention.","evidence":"siRNA depletion and CEP135 mutant overexpression with immunofluorescence and Western blot","pmids":["18851962"],"confidence":"Medium","gaps":["Direct CEP135–C-Nap1 binding interface not mapped","Single lab"]},{"year":2012,"claim":"Connected cohesion to genome-stress responses and ciliogenesis, showing C-Nap1 restrains DNA-damage-induced centriole splitting and supports primary cilium formation.","evidence":"siRNA knockdown with irradiation-induced splitting and cilium formation assays","pmids":["23070519"],"confidence":"Medium","gaps":["Mechanism coupling DNA damage to splitting unclear","Single lab"]},{"year":2014,"claim":"Resolved the molecular logic of disassembly by mapping multisite Nek2 phosphorylation that abolishes C-Nap1 oligomerization and disrupts its Cep135 interaction, and identified centlein as the bridge linking C-Nap1 to CEP68.","evidence":"In vitro kinase assays with mutagenesis, reciprocal co-IP, cell-cycle synchronization, and phosphomimetic mutant analysis","pmids":["24695856","24554434"],"confidence":"High","gaps":["How phosphorylation alters oligomer structure not shown at atomic resolution","Counteracting dephosphorylation pathway not yet defined"]},{"year":2015,"claim":"Closed the regulatory loop by identifying ASPP1/2 as the adaptors that recruit PP1α to dephosphorylate C-Nap1 and drive linker reassembly at mitotic exit.","evidence":"Co-immunoprecipitation, siRNA co-depletion, and phospho-specific Western blot","pmids":["25660448"],"confidence":"Medium","gaps":["Spatial control of reassembly timing unclear","Single lab"]},{"year":2015,"claim":"Assigned a discrete physiological function to cohesion using a natural truncating allele, showing C-Nap1-mediated cohesion is specifically required for cell migration without affecting centriole duplication or ciliogenesis.","evidence":"Genetic identification of truncating bovine mutation with immunofluorescence, EM, and migration assays in primary cells","pmids":["25902731"],"confidence":"Medium","gaps":["Mechanism linking cohesion to migration not defined","Single species/allele"]},{"year":2017,"claim":"Provided clean genetic confirmation in human cells that C-Nap1 maintains cohesion, sustains centriolar satellite density, and is required for stress-induced centrosome amplification.","evidence":"CRISPR/Cas9 null cells with rescue by reexpression and centrosome amplification assays","pmids":["28100636"],"confidence":"High","gaps":["How C-Nap1 promotes satellite density mechanistically unclear","Link to amplification pathway not dissected"]},{"year":2018,"claim":"Visualized the linker architecture directly, establishing C-Nap1 as a proximal ring that organizes rootletin rings/fibers with CEP68 as filament modulator.","evidence":"STED super-resolution nanoscopy with immunofluorescence and co-IP","pmids":["29463719"],"confidence":"High","gaps":["Molecular dimensions of the C-Nap1 ring not at atomic resolution","Dynamics of ring assembly not captured"]},{"year":2022,"claim":"Established an organismal role in asymmetric stem-cell division, showing CEP250 cohesion maintains E-cadherin polarity and basal mother-centrosome positioning needed for germ stem cell maintenance, with meiotic and DSB-repair defects on loss.","evidence":"CEP250 knockout mice with E-cadherin polarity and centrosome position analysis, TUNEL and γH2AX staining, meiotic spreads","pmids":["35599622","35127699"],"confidence":"High","gaps":["How centrosome cohesion enforces polarity not molecularly resolved","Direct DSB-repair role versus secondary effect unclear"]},{"year":2023,"claim":"Extended CEP250 function to sensory tissue maintenance and a downstream metabolic axis, linking photoreceptor cilium gating to arginine/ARG1 localization and showing hair-cell and retinal degeneration in vivo.","evidence":"Cep250 KO mice with ERG/ABR, immunofluorescence, untargeted metabolomics, and AAV-mediated Arg1 knockdown phenocopy","pmids":["30998843","37759551","37656476"],"confidence":"Medium","gaps":["Mechanism connecting cilium gating to arginine metabolism unresolved","Whether ARG1 mislocalization is cause or consequence unclear"]},{"year":2024,"claim":"Tied CEP250 to a human Mendelian phenotype, showing a frameshift disrupting the C-terminal region impairs SUN5/PMFBP1 association and sperm-neck localization, causing acephalic spermatozoa syndrome.","evidence":"Whole-exome sequencing, patient immunofluorescence, co-IP, and CRISPR-Cas9 knockin mouse","pmids":["39726222"],"confidence":"Medium","gaps":["Whether SUN5/PMFBP1 binding is direct not established","Structural basis for the 2272–2442 requirement not defined"]},{"year":null,"claim":"How the C-Nap1 ring's oligomeric structure is built and remodeled, and how cohesion is mechanistically translated into downstream cell-polarity and metabolic outcomes, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No atomic-resolution structure of the C-Nap1 ring or its phospho-regulated oligomerization","Mechanistic link between centrosome cohesion and E-cadherin polarity / arginine metabolism unestablished"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[1,3,11]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[3,6,11]}],"localization":[{"term_id":"GO:0005815","term_label":"microtubule organizing center","supporting_discovery_ids":[0,1,11]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[0,3]}],"pathway":[{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[1,2,7]},{"term_id":"R-HSA-1852241","term_label":"Organelle biogenesis and maintenance","supporting_discovery_ids":[10,11]}],"complexes":["centrosome linker"],"partners":["NEK2","ROOTLETIN","CEP135","CEP68","CNTLN","PPP1CA","SUN5","PMFBP1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9BV73","full_name":"Centrosome-associated protein CEP250","aliases":["250 kDa centrosomal protein","Cep250","Centrosomal Nek2-associated protein 1","C-Nap1","Centrosomal protein 2"],"length_aa":2442,"mass_kda":281.1,"function":"Plays an important role in centrosome cohesion during interphase (PubMed:30404835, PubMed:36282799). Recruits CCDC102B to the proximal ends of centrioles (PubMed:30404835). Maintains centrosome cohesion by forming intercentriolar linkages (PubMed:36282799). Accumulates at the proximal end of each centriole, forming supramolecular assemblies with viscous material properties that promote organelle cohesion (PubMed:36282799). May be involved in ciliogenesis (PubMed:28005958)","subcellular_location":"Cytoplasm, perinuclear region; Cytoplasm, cytoskeleton, microtubule organizing center, centrosome, centriole; Cytoplasm, cytoskeleton, microtubule organizing center, centrosome; Cytoplasm, cytoskeleton, cilium basal body; Cell projection, cilium, photoreceptor outer segment; Photoreceptor inner segment","url":"https://www.uniprot.org/uniprotkb/Q9BV73/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CEP250","classification":"Not Classified","n_dependent_lines":4,"n_total_lines":1208,"dependency_fraction":0.0033112582781456954},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000126001","cell_line_id":"CID000191","localizations":[{"compartment":"centrosome","grade":3}],"interactors":[{"gene":"MAPRE1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID000191","total_profiled":1310},"omim":[{"mim_id":"618358","title":"CONE-ROD DYSTROPHY AND HEARING LOSS 2; CRDHL2","url":"https://www.omim.org/entry/618358"},{"mim_id":"617236","title":"CONE-ROD DYSTROPHY AND HEARING LOSS 1; CRDHL1","url":"https://www.omim.org/entry/617236"},{"mim_id":"613428","title":"RETINITIS PIGMENTOSA 54; RP54","url":"https://www.omim.org/entry/613428"},{"mim_id":"609689","title":"CENTROSOMAL PROTEIN, 250-KD; CEP250","url":"https://www.omim.org/entry/609689"},{"mim_id":"608684","title":"NINEIN; NIN","url":"https://www.omim.org/entry/608684"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Enhanced","locations":[{"location":"Centrosome","reliability":"Enhanced"},{"location":"Basal body","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/CEP250"},"hgnc":{"alias_symbol":["C-NAP1"],"prev_symbol":["CEP2"]},"alphafold":{"accession":"Q9BV73","domains":[{"cath_id":"-","chopping":"445-505","consensus_level":"medium","plddt":71.6092,"start":445,"end":505},{"cath_id":"-","chopping":"718-947","consensus_level":"medium","plddt":70.3671,"start":718,"end":947},{"cath_id":"-","chopping":"1498-1534","consensus_level":"medium","plddt":71.1243,"start":1498,"end":1534},{"cath_id":"1.20.5","chopping":"247-345","consensus_level":"medium","plddt":70.1447,"start":247,"end":345},{"cath_id":"1.20.5","chopping":"658-708","consensus_level":"medium","plddt":71.2594,"start":658,"end":708}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BV73","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BV73-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BV73-F1-predicted_aligned_error_v6.png","plddt_mean":64.38},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CEP250","jax_strain_url":"https://www.jax.org/strain/search?query=CEP250"},"sequence":{"accession":"Q9BV73","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9BV73.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9BV73/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BV73"}},"corpus_meta":[{"pmid":"9647649","id":"PMC_9647649","title":"C-Nap1, a novel centrosomal coiled-coil protein and candidate substrate of the cell cycle-regulated protein kinase Nek2.","date":"1998","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/9647649","citation_count":377,"is_preprint":false},{"pmid":"11076968","id":"PMC_11076968","title":"The centrosomal protein C-Nap1 is required for cell cycle-regulated centrosome cohesion.","date":"2000","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/11076968","citation_count":187,"is_preprint":false},{"pmid":"16339073","id":"PMC_16339073","title":"Rootletin interacts with C-Nap1 and may function as a physical linker between the pair of centrioles/basal bodies in cells.","date":"2005","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/16339073","citation_count":130,"is_preprint":false},{"pmid":"12140259","id":"PMC_12140259","title":"The mechanism regulating the dissociation of the centrosomal protein C-Nap1 from mitotic spindle poles.","date":"2002","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/12140259","citation_count":94,"is_preprint":false},{"pmid":"24780881","id":"PMC_24780881","title":"A homozygous nonsense CEP250 mutation combined with a heterozygous nonsense C2orf71 mutation is associated with atypical Usher syndrome.","date":"2014","source":"Journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/24780881","citation_count":68,"is_preprint":false},{"pmid":"24554434","id":"PMC_24554434","title":"Centlein mediates an interaction between C-Nap1 and Cep68 to maintain centrosome cohesion.","date":"2014","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/24554434","citation_count":55,"is_preprint":false},{"pmid":"18851962","id":"PMC_18851962","title":"A novel function of CEP135 as a platform protein of C-NAP1 for its centriolar localization.","date":"2008","source":"Experimental cell research","url":"https://pubmed.ncbi.nlm.nih.gov/18851962","citation_count":55,"is_preprint":false},{"pmid":"24695856","id":"PMC_24695856","title":"Multisite phosphorylation of C-Nap1 releases it from Cep135 to trigger centrosome disjunction.","date":"2014","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/24695856","citation_count":53,"is_preprint":false},{"pmid":"29463719","id":"PMC_29463719","title":"STED nanoscopy of the centrosome linker reveals a CEP68-organized, periodic rootletin network anchored to a C-Nap1 ring at centrioles.","date":"2018","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/29463719","citation_count":53,"is_preprint":false},{"pmid":"30459346","id":"PMC_30459346","title":"High-throughput sequencing for the molecular diagnosis of Usher syndrome reveals 42 novel mutations and consolidates CEP250 as Usher-like disease causative.","date":"2018","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/30459346","citation_count":40,"is_preprint":false},{"pmid":"23070519","id":"PMC_23070519","title":"C-NAP1 and rootletin restrain DNA damage-induced centriole splitting and facilitate ciliogenesis.","date":"2012","source":"Cell cycle (Georgetown, Tex.)","url":"https://pubmed.ncbi.nlm.nih.gov/23070519","citation_count":35,"is_preprint":false},{"pmid":"25902731","id":"PMC_25902731","title":"C-Nap1 mutation affects centriole cohesion and is associated with a Seckel-like syndrome in cattle.","date":"2015","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/25902731","citation_count":35,"is_preprint":false},{"pmid":"29718797","id":"PMC_29718797","title":"CEP250 mutations associated with mild cone-rod dystrophy and sensorineural hearing loss in a Japanese family.","date":"2018","source":"Ophthalmic genetics","url":"https://pubmed.ncbi.nlm.nih.gov/29718797","citation_count":34,"is_preprint":false},{"pmid":"28100636","id":"PMC_28100636","title":"Centriole splitting caused by loss of the centrosomal linker protein C-NAP1 reduces centriolar satellite density and impedes centrosome amplification.","date":"2017","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/28100636","citation_count":26,"is_preprint":false},{"pmid":"30998843","id":"PMC_30998843","title":"Functional characterization of CEP250 variant identified in nonsyndromic retinitis pigmentosa.","date":"2019","source":"Human mutation","url":"https://pubmed.ncbi.nlm.nih.gov/30998843","citation_count":19,"is_preprint":false},{"pmid":"33109182","id":"PMC_33109182","title":"Involvement of NEK2 and its interaction with NDC80 and CEP250 in hepatocellular carcinoma.","date":"2020","source":"BMC medical genomics","url":"https://pubmed.ncbi.nlm.nih.gov/33109182","citation_count":13,"is_preprint":false},{"pmid":"37656476","id":"PMC_37656476","title":"Dysregulated Arginine Metabolism Is Linked to Retinal Degeneration in Cep250 Knockout Mice.","date":"2023","source":"Investigative ophthalmology & visual science","url":"https://pubmed.ncbi.nlm.nih.gov/37656476","citation_count":11,"is_preprint":false},{"pmid":"35127699","id":"PMC_35127699","title":"CEP250 is Required for Maintaining Centrosome Cohesion in the Germline and Fertility in Male Mice.","date":"2022","source":"Frontiers in cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/35127699","citation_count":11,"is_preprint":false},{"pmid":"35599622","id":"PMC_35599622","title":"Centrosome linker protein C-Nap1 maintains stem cells in mouse testes.","date":"2022","source":"EMBO 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technology","url":"https://pubmed.ncbi.nlm.nih.gov/36857066","citation_count":5,"is_preprint":false},{"pmid":"39726222","id":"PMC_39726222","title":"A homozygous loss-of-function mutation in CEP250 is associated with acephalic spermatozoa syndrome in humans.","date":"2024","source":"Andrology","url":"https://pubmed.ncbi.nlm.nih.gov/39726222","citation_count":3,"is_preprint":false},{"pmid":"39610034","id":"PMC_39610034","title":"The phenotypic spectrum of CEP250 gene variants.","date":"2024","source":"Ophthalmic genetics","url":"https://pubmed.ncbi.nlm.nih.gov/39610034","citation_count":2,"is_preprint":false},{"pmid":"37240188","id":"PMC_37240188","title":"RNA-Seq Analysis Reveals an Essential Role of the cGMP-PKG-MAPK Pathways in Retinal Degeneration Caused by Cep250 Deficiency.","date":"2023","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/37240188","citation_count":2,"is_preprint":false},{"pmid":"38942662","id":"PMC_38942662","title":"Altered centriolar cohesion by CEP250 and appendages impact outcome of patients with pancreatic cancer.","date":"2024","source":"Pancreatology : official journal of the International Association of Pancreatology (IAP) ... [et al.]","url":"https://pubmed.ncbi.nlm.nih.gov/38942662","citation_count":1,"is_preprint":false},{"pmid":"41675379","id":"PMC_41675379","title":"Single-cell analyses reveal impaired type B spermatogonia differentiation and meiotic entry in C-Nap1-null testes.","date":"2024","source":"Quantitative biology (Beijing, China)","url":"https://pubmed.ncbi.nlm.nih.gov/41675379","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":15294,"output_tokens":4488,"usd":0.056601,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":12397,"output_tokens":4251,"usd":0.08413,"stage2_stop_reason":"end_turn"},"total_usd":0.140731,"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\": 1998,\n      \"finding\": \"C-Nap1 (CEP250) was identified as a novel centrosomal coiled-coil protein that localizes specifically to the proximal ends of both mother and daughter centrioles. It was first identified as a Nek2-interacting protein in a yeast two-hybrid screen, and its C-terminal domain can be phosphorylated by Nek2 in vitro and after coexpression in vivo.\",\n      \"method\": \"Yeast two-hybrid screen, immunofluorescence, immunoelectron microscopy, in vitro kinase assay, co-expression in vivo\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — multiple orthogonal methods (yeast two-hybrid, immunoelectron microscopy, in vitro kinase assay), foundational paper replicated by subsequent studies\",\n      \"pmids\": [\"9647649\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"C-Nap1 is a key component of a dynamic, cell cycle-regulated structure that mediates centriole-centriole cohesion during interphase. Antibody-mediated interference with C-Nap1 function causes centrosome splitting independent of microtubule or microfilament networks, and C-Nap1 dissociates from spindle poles during mitosis and reaccumulates at centrosomes at the end of cell division.\",\n      \"method\": \"Antibody microinjection/interference, immunofluorescence, immunoelectron microscopy, overexpression of truncated mutants\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal loss-of-function and structural approaches; independently confirmed by subsequent studies\",\n      \"pmids\": [\"11076968\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Dissociation of C-Nap1 from mitotic centrosomes is regulated by M-phase-specific phosphorylation rather than ubiquitin-dependent proteolysis. Overexpression of active Nek2 substantially reduced formation of large C-Nap1 centrosome-associated structures, implicating Nek2 kinase as the key activity driving C-Nap1 centrosome dissociation at mitotic entry.\",\n      \"method\": \"Western blot cell cycle analysis, proteasome inhibitor treatment, Xenopus extract destruction assays, co-expression of active Nek2, immunofluorescence\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (proteasome inhibitors, Xenopus extracts, Nek2 co-expression) in single lab\",\n      \"pmids\": [\"12140259\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Rootletin interacts with C-Nap1 in vivo, colocalizes at basal bodies/centrioles, and functions as a physical linker between centriole pairs by binding to C-Nap1 at the proximal centriole ends. Transient expression of C-Nap1 fragments dissociated rootletin fibers from centrioles, resulting in centrosome separation.\",\n      \"method\": \"Co-immunoprecipitation, colocalization by immunofluorescence, ultrastructural analysis, transient overexpression of C-Nap1 fragments\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal co-IP plus ultrastructural analysis plus functional perturbation; replicated by subsequent linker structure studies\",\n      \"pmids\": [\"16339073\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"CEP135 acts as a platform protein for C-NAP1 at the centriole. Depletion of CEP135 caused premature centrosome splitting accompanied by a specific reduction in centrosomal C-NAP1 levels, and ectopic expression of CEP135 mutant proteins caused the same effect.\",\n      \"method\": \"siRNA depletion, overexpression of CEP135 mutants, immunofluorescence, Western blot\",\n      \"journal\": \"Experimental cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function with defined cellular phenotype plus mutant overexpression, single lab\",\n      \"pmids\": [\"18851962\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"C-NAP1 and rootletin restrain DNA damage-induced centriole splitting. siRNA depletion of C-NAP1 increased radiation-induced centriole splitting and reduced primary cilium formation, establishing C-NAP1 as part of the centriole cohesion apparatus required for normal ciliogenesis.\",\n      \"method\": \"siRNA knockdown, immunofluorescence, irradiation-induced centriole splitting assay, cilium formation assay\",\n      \"journal\": \"Cell cycle (Georgetown, Tex.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean siRNA KD with defined cellular phenotypes (centriole splitting and ciliogenesis), single lab\",\n      \"pmids\": [\"23070519\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Centlein directly interacts with both C-Nap1 and Cep68 and functions as a molecular link between them at the proximal ends of centrioles during interphase. Depletion of centlein impairs recruitment of Cep68 to centrosomes and causes centrosome splitting. Both centlein and Cep68 are Nek2A substrates.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence colocalization, siRNA depletion, in vitro kinase assay\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct interaction shown by co-IP plus loss-of-function phenotype plus in vitro kinase assay; multiple orthogonal methods\",\n      \"pmids\": [\"24554434\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Nek2 phosphorylates multiple residues within the C-terminal domain of C-Nap1, and these multisite phosphorylation events lead to loss of C-Nap1 oligomerization and centrosome association. Phosphorylation also perturbs interaction with the core centriolar protein Cep135, and endogenous C-Nap1–Cep135 interaction is specifically lost in mitosis.\",\n      \"method\": \"In vitro kinase assay with mutagenesis, co-immunoprecipitation, cell cycle synchronization, immunofluorescence, phosphomimetic mutant analysis\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — in vitro kinase assay with mutagenesis combined with reciprocal co-IP and cell-cycle-dependent interaction analysis; multiple orthogonal methods\",\n      \"pmids\": [\"24695856\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"ASPP1 and ASPP2 interact with C-Nap1 and facilitate centrosome linker reassembly at the end of mitosis. ASPP1/2 facilitate the interaction between C-Nap1 and PP1α, and this interaction was reduced by co-depletion of ASPP1/2. ASPP1/2 antagonize NEK2A-mediated C-Nap1 Ser2417/2421 phosphorylation in a PP1-dependent manner, and co-depletion of ASPP1/2 inhibited dephosphorylation of C-Nap1 at the end of mitosis.\",\n      \"method\": \"Co-immunoprecipitation, siRNA co-depletion, immunofluorescence, phospho-specific antibody western blot\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP plus functional knockdown with phosphorylation readout, single lab, two orthogonal methods\",\n      \"pmids\": [\"25660448\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"A truncating mutation in CEP250/C-Nap1 in cattle causes centrosome splitting and an altered cell migration phenotype, without affecting centriole ultrastructure, duplication, ciliogenesis, or mitotic spindle organization, establishing that C-Nap1-mediated centriole cohesion is specifically required for cell migration.\",\n      \"method\": \"Genetic identification of truncating mutation, immunofluorescence, electron microscopy, cell migration assay in primary cells\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — natural loss-of-function allele with defined centrosomal and cell migration phenotypes; single study but multiple cellular readouts\",\n      \"pmids\": [\"25902731\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"C-NAP1-null cells generated by genome editing show premature centriole separation, reduced density of centriolar satellites, and markedly reduced centrosome amplification induced by DNA damage or PLK4/CDK2 overexpression. Reexpression of C-NAP1 rescued both centriole separation and centriolar satellite density phenotypes.\",\n      \"method\": \"CRISPR/Cas9 genome editing, rescue by reexpression, immunofluorescence, centrosome amplification assays\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean null cells by genome editing with rescue, multiple orthogonal functional readouts\",\n      \"pmids\": [\"28100636\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"STED super-resolution microscopy revealed that C-Nap1 forms a ring at the proximal end of each centriole, organizing a rootletin ring and multiple rootletin/CEP68 fibers. The centrosome linker consists of a vast network of repeating rootletin units with C-Nap1 as ring organizer and CEP68 as filament modulator.\",\n      \"method\": \"STED (stimulated emission depletion) nanoscopy, immunofluorescence, co-immunoprecipitation\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct structural visualization by STED nanoscopy combined with Co-IP to confirm binding; single lab but rigorous super-resolution structural approach\",\n      \"pmids\": [\"29463719\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Disruption of Cep250 in a knockin mouse resulted in severe impairment of retinal function and significant retinal morphological alterations, establishing that CEP250 is required for photoreceptor function in vivo.\",\n      \"method\": \"Cep250 knockin mouse model, electroretinography, histological analysis\",\n      \"journal\": \"Human mutation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo loss-of-function model with functional (ERG) and structural readouts; single lab\",\n      \"pmids\": [\"30998843\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"CEP250-null male mice are infertile due to premature centrosome separation in germ cells, causing failure to establish E-cadherin polarity and inability to maintain the older mother centrosome at the basal site of seminiferous tubules, prompting premature stem cell differentiation and depletion of germ stem cells.\",\n      \"method\": \"CEP250 knockout mouse, immunofluorescence, E-cadherin polarity assay, centrosome position analysis\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean KO with defined mechanism linking centrosome cohesion to asymmetric cell division polarity; mechanistic pathway established by multiple readouts\",\n      \"pmids\": [\"35599622\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Cep250-/- mice show male infertility due to reduction in the spermatogonial pool and meiotic blockade at pachytene-like stage, with precocious centrosome splitting in meiocytes and abnormal γH2AX staining indicating unrepaired DNA double-strand breaks and synapsis defects.\",\n      \"method\": \"CEP250 knockout mouse, immunofluorescence, TUNEL assay, γH2AX staining, meiotic spread analysis\",\n      \"journal\": \"Frontiers in cell and developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO with defined phenotypic readouts in germline; single lab, consistent with EMBO reports study\",\n      \"pmids\": [\"35127699\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"A truncating nonsense variant in CEP250 (p.Gln1171Ter) causes mislocalization of C-Nap1 protein away from the centrosome to the cytosol, and Cep250 knockout mice show hair cell degeneration and progressive hearing loss, establishing CEP250 function at the centrosome is required for cochlear hair cell maintenance.\",\n      \"method\": \"Heterologous expression of truncating variant in NIH3T3 cells with immunofluorescence, Cep250 knockout mouse, auditory brainstem response\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — variant localization experiment plus in vivo KO model; single lab, two complementary approaches\",\n      \"pmids\": [\"37759551\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"In Cep250 knockout mice, outer segment proteins are mislocalized to the outer nuclear layer, and untargeted metabolomics revealed dysregulated arginine metabolism with mislocalization of arginase 1 (ARG1). AAV-mediated retinal knockdown of Arg1 in wild-type mice recapitulated retinal degeneration, linking CEP250-dependent photoreceptor cilium gating to arginine metabolism.\",\n      \"method\": \"Cep250 KO mouse, immunofluorescence for OS proteins, untargeted metabolomics, AAV-mediated Arg1 knockdown\",\n      \"journal\": \"Investigative ophthalmology & visual science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO model with metabolomics and functional rescue-by-phenocopy experiment; single lab, multiple orthogonal methods\",\n      \"pmids\": [\"37656476\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"A homozygous frameshift mutation in CEP250 (c.4710_4723del, p.E1570fs*39) causes acephalic spermatozoa syndrome. The mutant CEP250 protein shows decreased signal in the sperm neck region and reduced co-immunoprecipitation with SUN5 and PMFBP1, likely due to absence of the 2272-2442 amino acid region.\",\n      \"method\": \"Whole-exome sequencing, immunofluorescence, co-immunoprecipitation, Western blot, CRISPR-Cas9 knockin mouse\",\n      \"journal\": \"Andrology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP interaction studies combined with patient immunofluorescence and KI mouse; single lab\",\n      \"pmids\": [\"39726222\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CEP250/C-Nap1 is a large coiled-coil protein that localizes as a ring at the proximal ends of centrioles and anchors rootletin/CEP68 filaments to form the interphase centrosome linker, maintaining centriole-centriole cohesion; at mitotic entry, Nek2 phosphorylates multiple C-terminal residues of C-Nap1, disrupting its oligomerization and its interaction with the scaffold protein Cep135, causing linker disassembly (centrosome disjunction), while linker reassembly at mitotic exit requires ASPP1/2-mediated PP1α-dependent dephosphorylation of C-Nap1; loss of C-Nap1-mediated cohesion impairs asymmetric stem cell division, cell migration, centriolar satellite organization, centrosome amplification, photoreceptor cilium gating, and male germ cell development.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CEP250 (C-Nap1) is a large centrosomal coiled-coil protein that builds the interphase centrosome linker, holding the two centrioles of a centrosome together until mitotic entry [#0, #1]. It localizes specifically to the proximal ends of both mother and daughter centrioles, where STED nanoscopy shows it forms a ring that organizes a rootletin ring and the rootletin/CEP68 fibers constituting the linker network [#0, #11]. C-Nap1 is docked at the centriole through CEP135, which acts as a platform for its centrosomal recruitment, and it anchors rootletin and CEP68 to the proximal ends, with centlein bridging C-Nap1 to CEP68 [#3, #4, #6]. Centriole cohesion is controlled by cell-cycle phosphorylation: at mitotic entry Nek2 phosphorylates multiple residues in the C-terminal domain of C-Nap1, abolishing its oligomerization and centrosome association and disrupting its interaction with Cep135, thereby driving linker disassembly and centrosome disjunction [#2, #7]; at the end of mitosis ASPP1/2 recruit PP1\\u03b1 to dephosphorylate C-Nap1 and restore the linker [#8]. Loss of C-Nap1-mediated cohesion causes premature centriole splitting and reduces centriolar satellite density and DNA-damage- or PLK4/CDK2-driven centrosome amplification [#10]. In vivo, CEP250 cohesion function is required for cell migration, photoreceptor and cochlear hair-cell maintenance, and male germ cell development, where it supports asymmetric stem-cell division by maintaining E-cadherin polarity and basal positioning of the mother centrosome [#9, #12, #13, #15]; a homozygous frameshift mutation that disrupts its association with SUN5 and PMFBP1 causes acephalic spermatozoa syndrome [#17].\",\n  \"teleology\": [\n    {\n      \"year\": 1998,\n      \"claim\": \"Established the existence and location of the protein, defining C-Nap1 as a Nek2-interacting centrosomal coiled-coil protein at centriole proximal ends and immediately linking it to a kinase.\",\n      \"evidence\": \"Yeast two-hybrid screen, immunoelectron microscopy, and in vitro kinase assay\",\n      \"pmids\": [\"9647649\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of Nek2 phosphorylation not yet defined\", \"No binding partners at the centriole identified\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Answered what C-Nap1 does by showing it mediates centriole-centriole cohesion in a cell-cycle-regulated manner independent of cytoskeletal networks.\",\n      \"evidence\": \"Antibody microinjection/interference and truncated mutant overexpression with immunofluorescence and immunoEM\",\n      \"pmids\": [\"11076968\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular nature of the physical linker not identified\", \"Mechanism of mitotic dissociation unresolved\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Distinguished phosphorylation from proteolysis as the mechanism of mitotic dissociation, implicating Nek2 activity as the driver of linker disassembly.\",\n      \"evidence\": \"Proteasome inhibitor treatment, Xenopus extract destruction assays, and active Nek2 co-expression\",\n      \"pmids\": [\"12140259\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific phosphorylated residues not mapped\", \"Counteracting phosphatase not identified\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Identified the physical linker filament by showing rootletin binds C-Nap1 at proximal centriole ends and is dislodged when C-Nap1 is perturbed.\",\n      \"evidence\": \"Co-immunoprecipitation, colocalization, ultrastructural analysis, and C-Nap1 fragment overexpression\",\n      \"pmids\": [\"16339073\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry and architecture of the linker not resolved\", \"How rootletin docks onto C-Nap1 unclear\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Defined how C-Nap1 is anchored at the centriole, identifying CEP135 as the platform required for its centrosomal retention.\",\n      \"evidence\": \"siRNA depletion and CEP135 mutant overexpression with immunofluorescence and Western blot\",\n      \"pmids\": [\"18851962\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct CEP135\\u2013C-Nap1 binding interface not mapped\", \"Single lab\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Connected cohesion to genome-stress responses and ciliogenesis, showing C-Nap1 restrains DNA-damage-induced centriole splitting and supports primary cilium formation.\",\n      \"evidence\": \"siRNA knockdown with irradiation-induced splitting and cilium formation assays\",\n      \"pmids\": [\"23070519\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism coupling DNA damage to splitting unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Resolved the molecular logic of disassembly by mapping multisite Nek2 phosphorylation that abolishes C-Nap1 oligomerization and disrupts its Cep135 interaction, and identified centlein as the bridge linking C-Nap1 to CEP68.\",\n      \"evidence\": \"In vitro kinase assays with mutagenesis, reciprocal co-IP, cell-cycle synchronization, and phosphomimetic mutant analysis\",\n      \"pmids\": [\"24695856\", \"24554434\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How phosphorylation alters oligomer structure not shown at atomic resolution\", \"Counteracting dephosphorylation pathway not yet defined\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Closed the regulatory loop by identifying ASPP1/2 as the adaptors that recruit PP1\\u03b1 to dephosphorylate C-Nap1 and drive linker reassembly at mitotic exit.\",\n      \"evidence\": \"Co-immunoprecipitation, siRNA co-depletion, and phospho-specific Western blot\",\n      \"pmids\": [\"25660448\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Spatial control of reassembly timing unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Assigned a discrete physiological function to cohesion using a natural truncating allele, showing C-Nap1-mediated cohesion is specifically required for cell migration without affecting centriole duplication or ciliogenesis.\",\n      \"evidence\": \"Genetic identification of truncating bovine mutation with immunofluorescence, EM, and migration assays in primary cells\",\n      \"pmids\": [\"25902731\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism linking cohesion to migration not defined\", \"Single species/allele\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Provided clean genetic confirmation in human cells that C-Nap1 maintains cohesion, sustains centriolar satellite density, and is required for stress-induced centrosome amplification.\",\n      \"evidence\": \"CRISPR/Cas9 null cells with rescue by reexpression and centrosome amplification assays\",\n      \"pmids\": [\"28100636\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How C-Nap1 promotes satellite density mechanistically unclear\", \"Link to amplification pathway not dissected\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Visualized the linker architecture directly, establishing C-Nap1 as a proximal ring that organizes rootletin rings/fibers with CEP68 as filament modulator.\",\n      \"evidence\": \"STED super-resolution nanoscopy with immunofluorescence and co-IP\",\n      \"pmids\": [\"29463719\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular dimensions of the C-Nap1 ring not at atomic resolution\", \"Dynamics of ring assembly not captured\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Established an organismal role in asymmetric stem-cell division, showing CEP250 cohesion maintains E-cadherin polarity and basal mother-centrosome positioning needed for germ stem cell maintenance, with meiotic and DSB-repair defects on loss.\",\n      \"evidence\": \"CEP250 knockout mice with E-cadherin polarity and centrosome position analysis, TUNEL and \\u03b3H2AX staining, meiotic spreads\",\n      \"pmids\": [\"35599622\", \"35127699\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How centrosome cohesion enforces polarity not molecularly resolved\", \"Direct DSB-repair role versus secondary effect unclear\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Extended CEP250 function to sensory tissue maintenance and a downstream metabolic axis, linking photoreceptor cilium gating to arginine/ARG1 localization and showing hair-cell and retinal degeneration in vivo.\",\n      \"evidence\": \"Cep250 KO mice with ERG/ABR, immunofluorescence, untargeted metabolomics, and AAV-mediated Arg1 knockdown phenocopy\",\n      \"pmids\": [\"30998843\", \"37759551\", \"37656476\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism connecting cilium gating to arginine metabolism unresolved\", \"Whether ARG1 mislocalization is cause or consequence unclear\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Tied CEP250 to a human Mendelian phenotype, showing a frameshift disrupting the C-terminal region impairs SUN5/PMFBP1 association and sperm-neck localization, causing acephalic spermatozoa syndrome.\",\n      \"evidence\": \"Whole-exome sequencing, patient immunofluorescence, co-IP, and CRISPR-Cas9 knockin mouse\",\n      \"pmids\": [\"39726222\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether SUN5/PMFBP1 binding is direct not established\", \"Structural basis for the 2272\\u20132442 requirement not defined\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the C-Nap1 ring's oligomeric structure is built and remodeled, and how cohesion is mechanistically translated into downstream cell-polarity and metabolic outcomes, remains unresolved.\",\n      \"evidence\": null,\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No atomic-resolution structure of the C-Nap1 ring or its phospho-regulated oligomerization\", \"Mechanistic link between centrosome cohesion and E-cadherin polarity / arginine metabolism unestablished\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [1, 3, 11]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [3, 6, 11]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005815\", \"supporting_discovery_ids\": [0, 1, 11]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [0, 3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [1, 2, 7]},\n      {\"term_id\": \"R-HSA-1852241\", \"supporting_discovery_ids\": [10, 11]}\n    ],\n    \"complexes\": [\"centrosome linker\"],\n    \"partners\": [\"NEK2\", \"ROOTLETIN\", \"CEP135\", \"CEP68\", \"CNTLN\", \"PPP1CA\", \"SUN5\", \"PMFBP1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}