Affinage

CEP250

Centrosome-associated protein CEP250 · UniProt Q9BV73

Length
2442 aa
Mass
281.1 kDa
Annotated
2026-06-09
27 papers in source corpus 18 papers cited in narrative 18 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 6/6 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

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).

Mechanistic history

Synthesis pass · year-by-year structured walk · 14 steps
  1. 1998 High

    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

    PMID:9647649

    Open questions at the time
    • Functional consequence of Nek2 phosphorylation not yet defined
    • No binding partners at the centriole identified
  2. 2000 High

    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

    PMID:11076968

    Open questions at the time
    • Molecular nature of the physical linker not identified
    • Mechanism of mitotic dissociation unresolved
  3. 2002 High

    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

    PMID:12140259

    Open questions at the time
    • Specific phosphorylated residues not mapped
    • Counteracting phosphatase not identified
  4. 2005 High

    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

    PMID:16339073

    Open questions at the time
    • Stoichiometry and architecture of the linker not resolved
    • How rootletin docks onto C-Nap1 unclear
  5. 2008 Medium

    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

    PMID:18851962

    Open questions at the time
    • Direct CEP135–C-Nap1 binding interface not mapped
    • Single lab
  6. 2012 Medium

    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

    PMID:23070519

    Open questions at the time
    • Mechanism coupling DNA damage to splitting unclear
    • Single lab
  7. 2014 High

    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

    PMID:24554434 PMID:24695856

    Open questions at the time
    • How phosphorylation alters oligomer structure not shown at atomic resolution
    • Counteracting dephosphorylation pathway not yet defined
  8. 2015 Medium

    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

    PMID:25660448

    Open questions at the time
    • Spatial control of reassembly timing unclear
    • Single lab
  9. 2015 Medium

    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

    PMID:25902731

    Open questions at the time
    • Mechanism linking cohesion to migration not defined
    • Single species/allele
  10. 2017 High

    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

    PMID:28100636

    Open questions at the time
    • How C-Nap1 promotes satellite density mechanistically unclear
    • Link to amplification pathway not dissected
  11. 2018 High

    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

    PMID:29463719

    Open questions at the time
    • Molecular dimensions of the C-Nap1 ring not at atomic resolution
    • Dynamics of ring assembly not captured
  12. 2022 High

    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

    PMID:35127699 PMID:35599622

    Open questions at the time
    • How centrosome cohesion enforces polarity not molecularly resolved
    • Direct DSB-repair role versus secondary effect unclear
  13. 2023 Medium

    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

    PMID:30998843 PMID:37656476 PMID:37759551

    Open questions at the time
    • Mechanism connecting cilium gating to arginine metabolism unresolved
    • Whether ARG1 mislocalization is cause or consequence unclear
  14. 2024 Medium

    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

    PMID:39726222

    Open questions at the time
    • Whether SUN5/PMFBP1 binding is direct not established
    • Structural basis for the 2272–2442 requirement not defined

Open questions

Synthesis pass · forward-looking unresolved questions
  • 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.
  • 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

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0005198 structural molecule activity 3 GO:0060090 molecular adaptor activity 3
Localization
GO:0005815 microtubule organizing center 3 GO:0005856 cytoskeleton 2
Pathway
R-HSA-1640170 Cell Cycle 3 R-HSA-1852241 Organelle biogenesis and maintenance 2
Partners
CEP135CEP68CNTLNNEK2PMFBP1PPP1CAROOTLETINSUN5
Complex memberships
centrosome linker

Evidence

Reading pass · 18 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1998 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. Yeast two-hybrid screen, immunofluorescence, immunoelectron microscopy, in vitro kinase assay, co-expression in vivo The Journal of cell biology High 9647649
2000 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. Antibody microinjection/interference, immunofluorescence, immunoelectron microscopy, overexpression of truncated mutants The Journal of cell biology High 11076968
2002 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. Western blot cell cycle analysis, proteasome inhibitor treatment, Xenopus extract destruction assays, co-expression of active Nek2, immunofluorescence Journal of cell science High 12140259
2005 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. Co-immunoprecipitation, colocalization by immunofluorescence, ultrastructural analysis, transient overexpression of C-Nap1 fragments Molecular biology of the cell High 16339073
2008 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. siRNA depletion, overexpression of CEP135 mutants, immunofluorescence, Western blot Experimental cell research Medium 18851962
2012 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. siRNA knockdown, immunofluorescence, irradiation-induced centriole splitting assay, cilium formation assay Cell cycle (Georgetown, Tex.) Medium 23070519
2014 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. Co-immunoprecipitation, immunofluorescence colocalization, siRNA depletion, in vitro kinase assay Journal of cell science High 24554434
2014 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. In vitro kinase assay with mutagenesis, co-immunoprecipitation, cell cycle synchronization, immunofluorescence, phosphomimetic mutant analysis Journal of cell science High 24695856
2015 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. Co-immunoprecipitation, siRNA co-depletion, immunofluorescence, phospho-specific antibody western blot Biochemical and biophysical research communications Medium 25660448
2015 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. Genetic identification of truncating mutation, immunofluorescence, electron microscopy, cell migration assay in primary cells Nature communications Medium 25902731
2017 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. CRISPR/Cas9 genome editing, rescue by reexpression, immunofluorescence, centrosome amplification assays Molecular biology of the cell High 28100636
2018 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. STED (stimulated emission depletion) nanoscopy, immunofluorescence, co-immunoprecipitation Proceedings of the National Academy of Sciences of the United States of America High 29463719
2019 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. Cep250 knockin mouse model, electroretinography, histological analysis Human mutation Medium 30998843
2022 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. CEP250 knockout mouse, immunofluorescence, E-cadherin polarity assay, centrosome position analysis EMBO reports High 35599622
2022 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. CEP250 knockout mouse, immunofluorescence, TUNEL assay, γH2AX staining, meiotic spread analysis Frontiers in cell and developmental biology Medium 35127699
2023 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. Heterologous expression of truncating variant in NIH3T3 cells with immunofluorescence, Cep250 knockout mouse, auditory brainstem response Cells Medium 37759551
2023 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. Cep250 KO mouse, immunofluorescence for OS proteins, untargeted metabolomics, AAV-mediated Arg1 knockdown Investigative ophthalmology & visual science Medium 37656476
2024 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. Whole-exome sequencing, immunofluorescence, co-immunoprecipitation, Western blot, CRISPR-Cas9 knockin mouse Andrology Medium 39726222

Source papers

Stage 0 corpus · 27 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
1998 C-Nap1, a novel centrosomal coiled-coil protein and candidate substrate of the cell cycle-regulated protein kinase Nek2. The Journal of cell biology 377 9647649
2000 The centrosomal protein C-Nap1 is required for cell cycle-regulated centrosome cohesion. The Journal of cell biology 187 11076968
2005 Rootletin interacts with C-Nap1 and may function as a physical linker between the pair of centrioles/basal bodies in cells. Molecular biology of the cell 130 16339073
2002 The mechanism regulating the dissociation of the centrosomal protein C-Nap1 from mitotic spindle poles. Journal of cell science 94 12140259
2014 A homozygous nonsense CEP250 mutation combined with a heterozygous nonsense C2orf71 mutation is associated with atypical Usher syndrome. Journal of medical genetics 68 24780881
2014 Centlein mediates an interaction between C-Nap1 and Cep68 to maintain centrosome cohesion. Journal of cell science 55 24554434
2008 A novel function of CEP135 as a platform protein of C-NAP1 for its centriolar localization. Experimental cell research 55 18851962
2018 STED nanoscopy of the centrosome linker reveals a CEP68-organized, periodic rootletin network anchored to a C-Nap1 ring at centrioles. Proceedings of the National Academy of Sciences of the United States of America 53 29463719
2014 Multisite phosphorylation of C-Nap1 releases it from Cep135 to trigger centrosome disjunction. Journal of cell science 53 24695856
2018 High-throughput sequencing for the molecular diagnosis of Usher syndrome reveals 42 novel mutations and consolidates CEP250 as Usher-like disease causative. Scientific reports 40 30459346
2015 C-Nap1 mutation affects centriole cohesion and is associated with a Seckel-like syndrome in cattle. Nature communications 35 25902731
2012 C-NAP1 and rootletin restrain DNA damage-induced centriole splitting and facilitate ciliogenesis. Cell cycle (Georgetown, Tex.) 35 23070519
2018 CEP250 mutations associated with mild cone-rod dystrophy and sensorineural hearing loss in a Japanese family. Ophthalmic genetics 34 29718797
2017 Centriole splitting caused by loss of the centrosomal linker protein C-NAP1 reduces centriolar satellite density and impedes centrosome amplification. Molecular biology of the cell 26 28100636
2019 Functional characterization of CEP250 variant identified in nonsyndromic retinitis pigmentosa. Human mutation 19 30998843
2020 Involvement of NEK2 and its interaction with NDC80 and CEP250 in hepatocellular carcinoma. BMC medical genomics 13 33109182
2023 Dysregulated Arginine Metabolism Is Linked to Retinal Degeneration in Cep250 Knockout Mice. Investigative ophthalmology & visual science 11 37656476
2022 CEP250 is Required for Maintaining Centrosome Cohesion in the Germline and Fertility in Male Mice. Frontiers in cell and developmental biology 11 35127699
2023 Novel Variant in CEP250 Causes Protein Mislocalization and Leads to Nonsyndromic Autosomal Recessive Type of Progressive Hearing Loss. Cells 8 37759551
2022 Centrosome linker protein C-Nap1 maintains stem cells in mouse testes. EMBO reports 8 35599622
2015 The tumor suppressor proteins ASPP1 and ASPP2 interact with C-Nap1 and regulate centrosome linker reassembly. Biochemical and biophysical research communications 8 25660448
2023 Homozygous Knockout of Cep250 Leads to a Relatively Late-Onset Retinal Degeneration and Sensorineural Hearing Loss in Mice. Translational vision science & technology 5 36857066
2024 A homozygous loss-of-function mutation in CEP250 is associated with acephalic spermatozoa syndrome in humans. Andrology 3 39726222
2024 The phenotypic spectrum of CEP250 gene variants. Ophthalmic genetics 2 39610034
2023 RNA-Seq Analysis Reveals an Essential Role of the cGMP-PKG-MAPK Pathways in Retinal Degeneration Caused by Cep250 Deficiency. International journal of molecular sciences 2 37240188
2024 Altered centriolar cohesion by CEP250 and appendages impact outcome of patients with pancreatic cancer. Pancreatology : official journal of the International Association of Pancreatology (IAP) ... [et al.] 1 38942662
2024 Single-cell analyses reveal impaired type B spermatogonia differentiation and meiotic entry in C-Nap1-null testes. Quantitative biology (Beijing, China) 0 41675379

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