Affinage

CEP68

Centrosomal protein of 68 kDa · UniProt Q76N32

Round 2 corrected
Length
757 aa
Mass
81.1 kDa
Annotated
2026-04-28
43 papers in source corpus 7 papers cited in narrative 7 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

CEP68 is a centrosome-linker protein that maintains interphase centrosome cohesion by associating with periodic rootletin filaments anchored via C-Nap1 rings at centriole proximal ends, where it modulates filament branching and thickness (PMID:18042621, PMID:29463719). CEP68 is recruited to centrosomes through a C-Nap1–centlein–CEP68–rootletin complex, with centlein acting as a molecular bridge between C-Nap1 and CEP68 (PMID:24554434). During interphase, rootletin protects CEP68 from VHL E3 ligase-dependent ubiquitination and proteasomal degradation, while at mitotic entry PLK1 phosphorylation of CEP68 Ser332 generates a phosphodegron recognized by SCF(βTrCP), triggering CEP68 destruction that releases CEP215 from the peripheral pericentriolar material and permits centriole separation and duplication licensing (PMID:25503564, PMID:28089774). MCM7 facilitates CEP68 degradation by promoting the CEP68–VHL interaction, providing an additional regulatory input into centrosome cohesion control (PMID:28578000).

Mechanistic history

Synthesis pass · year-by-year structured walk · 5 steps
  1. 2007 High

    The identification of CEP68 as a rootletin- and C-Nap1-dependent interphase centrosome protein whose depletion causes premature centrosome splitting established it as a new component of the centrosome cohesion machinery.

    Evidence Immunofluorescence, siRNA depletion with splitting phenotype, co-localization dependency experiments in human cells

    PMID:18042621

    Open questions at the time
    • How CEP68 is physically linked to C-Nap1 was unknown
    • The mitotic mechanism removing CEP68 from centrosomes was uncharacterized
    • Whether CEP68 has a structural versus signaling role in centrosome cohesion was unclear
  2. 2014 High

    Two studies resolved how CEP68 connects to the cohesion network and how it is eliminated at mitosis: centlein bridges C-Nap1 to CEP68, while PLK1 phosphorylation of CEP68 Ser332 creates a βTrCP phosphodegron that triggers SCF-mediated degradation in prometaphase, thereby releasing CEP215 from the PCM to allow centriole separation and duplication licensing.

    Evidence Co-IP, GST pulldown for direct centlein–CEP68 binding, Nek2A kinase assay, PLK1 phosphosite mutagenesis, in vivo ubiquitination assays, epistatic siRNA experiments

    PMID:24554434 PMID:25503564

    Open questions at the time
    • How CEP68 protein stability is maintained during interphase was not addressed
    • The structural arrangement of CEP68 within rootletin filaments was unresolved
    • Whether additional E3 ligases regulate CEP68 outside mitosis was unknown
  3. 2015 Medium

    Domain-mapping clarified that the C-terminal 300–500 amino acids control both interphase centrosome targeting and mitotic dissociation, and confirmed Nek2-dependent phosphorylation promotes CEP68 degradation via SCF(βTrCP).

    Evidence Deletion mapping with immunofluorescence, in vivo phosphorylation assays, Co-IP with SCF components, cell-cycle-staged degradation assays

    PMID:25704143

    Open questions at the time
    • Precise phosphosites targeted by Nek2 on CEP68 were not mapped at single-residue resolution
    • The relative contributions of PLK1 versus Nek2 to mitotic CEP68 degradation remained unresolved
  4. 2017 High

    Discovery that rootletin protects CEP68 from VHL-mediated ubiquitination during interphase, and that MCM7 promotes the CEP68–VHL interaction, revealed a dual-layer regulation of CEP68 stability: rootletin shields CEP68 from VHL, while MCM7 enhances VHL-dependent degradation.

    Evidence In vitro ubiquitination reconstitution with VHL complex, epistatic siRNA double knockdown rescuing cohesion, VHL-binding-deficient CEP68 mutants, GST pulldown for MCM7–CEP68 direct binding, overexpression/depletion of MCM7

    PMID:28089774 PMID:28578000

    Open questions at the time
    • How rootletin physically occludes VHL access to CEP68 is structurally uncharacterized
    • The physiological context in which MCM7 acts at centrosomes versus its canonical replication role is unclear
    • Whether VHL and SCF(βTrCP) act on the same or different CEP68 pools is unresolved
  5. 2018 High

    STED super-resolution imaging revealed that CEP68 decorates rootletin filaments at 75-nm periodic intervals and is required for filament branching and thickness control, establishing CEP68 as a structural modulator of the centrosome linker rather than merely a passive component.

    Evidence STED and structured illumination microscopy, domain-mapping Co-IP for rootletin spectrin repeat–CEP68 interaction, siRNA depletion

    PMID:29463719

    Open questions at the time
    • Atomic-resolution structure of the CEP68–rootletin interface is lacking
    • Whether CEP68 periodicity is self-determined or templated by rootletin is unknown
    • Functional consequences of altered filament branching for cell division fidelity have not been tested

Open questions

Synthesis pass · forward-looking unresolved questions
  • Key open questions include the structural basis of CEP68's periodic binding to rootletin, the interplay between VHL- and SCF(βTrCP)-dependent degradation pathways during the cell cycle, and whether CEP68 loss or mutation has consequences for tissue-level physiology or disease.
  • No atomic or cryo-EM structure exists for CEP68 or its complexes
  • No in vivo animal model phenotype has been reported
  • Relative timing and coordination of VHL versus SCF(βTrCP) pathways across the cell cycle is unresolved

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0005198 structural molecule activity 2 GO:0008092 cytoskeletal protein binding 2
Localization
GO:0005815 microtubule organizing center 5 GO:0005856 cytoskeleton 1
Pathway
R-HSA-1640170 Cell Cycle 2 R-HSA-1852241 Organelle biogenesis and maintenance 2
Partners
BTRCCDK5RAP2CEP250CNTLNCROCCMCM7PCNTVHL
Complex memberships
C-Nap1–centlein–CEP68–rootletin linker complexCEP68–CEP215–pericentrin PCM complex

Evidence

Reading pass · 7 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2007 CEP68 localizes to fibres emanating from the proximal ends of centrioles during interphase and dissociates from centrosomes at mitosis. CEP68 depends on both rootletin and C-Nap1 for centriole association, and depletion of CEP68 causes premature centrosome separation (splitting). Overexpressed CEP68 is recruited to ectopic rootletin fibres but does not itself induce extensive fibre formation, indicating CEP68 cooperates with rootletin and C-Nap1 in maintaining centrosome cohesion. Immunofluorescence microscopy, siRNA depletion with centrosome-splitting phenotype readout, overexpression and co-localization assays, reciprocal dependency experiments Journal of cell science High 18042621
2014 CEP68 forms a trimeric complex with CEP215 (CDK5RAP2) and pericentrin (PCNT) at the pericentriolar material. CEP68 is degraded in prometaphase via the SCF(βTrCP) ubiquitin ligase; this degradation is initiated by PLK1 phosphorylation of CEP68 on Ser332, which creates a phosphodegron recognized by βTrCP. CEP68 degradation removes CEP215 from the peripheral PCM, which is required to prevent centriole separation following disengagement, thereby licensing centrioles for duplication. Co-immunoprecipitation, mass spectrometry interactome, siRNA depletion, phosphosite mutagenesis, in vivo ubiquitination assay, PLK1 kinase assay Nature cell biology High 25503564
2014 Centlein (CNTLN) directly interacts with both C-Nap1 and CEP68 and functions as a molecular bridge between them at the proximal ends of centrioles during interphase. Depletion of centlein impairs CEP68 recruitment to centrosomes and causes centrosome splitting. Both centlein and CEP68 are substrates of the mitotic kinase Nek2A, placing CEP68 downstream of Nek2A in the cohesion-dissolution pathway. Co-immunoprecipitation, direct binding (GST pulldown), siRNA depletion with centrosome-splitting readout, Nek2A in vitro kinase assay, immunofluorescence Journal of cell science High 24554434
2015 The C-terminal 300–400 amino acids of CEP68 are necessary for its localization to interphase centrosomes, while the C-terminal 400–500 amino acid region regulates its dissociation at mitotic onset. Nek2 phosphorylates CEP68 in vivo and this phosphorylation promotes CEP68 degradation. The SCF(βTrCP) complex mediates CEP68 destruction at mitosis through βTrCP recognition. Domain deletion mapping with immunofluorescence, in vivo phosphorylation assays, co-immunoprecipitation with SCF components, cell-cycle-staged degradation assays European journal of cell biology Medium 25704143
2017 Rootletin protects CEP68 from proteasomal degradation by inhibiting VHL-mediated ubiquitination. In the absence of rootletin, the VHL E3 ligase complex ubiquitinates CEP68 in vitro and in vivo, leading to its degradation and centrosome splitting. Co-depletion of rootletin and VHL rescues CEP68 levels and centrosome cohesion. A CEP68 mutant that cannot bind the β-domain of VHL or cannot be polyubiquitinated also suppresses centrosome splitting caused by rootletin depletion. siRNA double knockdown epistasis, in vitro ubiquitination assay with VHL E3 complex, in vivo ubiquitination assay, stable CEP68 mutant rescue experiments, immunofluorescence Biochimica et biophysica acta. Molecular cell research High 28089774
2017 MCM7 directly binds CEP68 in vitro and forms a ternary complex with CEP68 and VHL in vivo. MCM7 depletion weakens the CEP68-VHL interaction, whereas MCM7 overexpression facilitates CEP68-VHL association, increasing CEP68 ubiquitination and proteasomal degradation, resulting in centrosome splitting. This identifies MCM7 as a positive regulator of VHL-mediated CEP68 degradation at the centrosome. GST pulldown (direct binding), co-immunoprecipitation, siRNA depletion, overexpression, in vivo ubiquitination assay, immunofluorescence centrosome-splitting assay Biochemical and biophysical research communications Medium 28578000
2018 Super-resolution STED microscopy revealed that CEP68 co-localizes with rootletin in periodic filaments that branch off centrioles and form a web-like interdigitating network between the two centrosomes. Rootletin binds CEP68 via its C-terminal spectrin repeat-containing region at 75-nm intervals along the filament. CEP68 is required for forming rootletin filaments that branch off centrioles and for modulating the thickness of rootletin fibers, acting as a filament modulator within a C-Nap1-anchored, periodically ordered centrosome linker network. STED super-resolution microscopy, structured illumination microscopy, siRNA depletion, co-immunoprecipitation to map rootletin-CEP68 binding domain, immunofluorescence Proceedings of the National Academy of Sciences of the United States of America High 29463719

Source papers

Stage 0 corpus · 43 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2002 Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences. Proceedings of the National Academy of Sciences of the United States of America 1479 12477932
2017 Architecture of the human interactome defines protein communities and disease networks. Nature 1085 28514442
2014 A proteome-scale map of the human interactome network. Cell 977 25416956
2020 A reference map of the human binary protein interactome. Nature 849 32296183
2003 Complete sequencing and characterization of 21,243 full-length human cDNAs. Nature genetics 754 14702039
2021 Dual proteome-scale networks reveal cell-specific remodeling of the human interactome. Cell 705 33961781
2011 Phylogenetic-based propagation of functional annotations within the Gene Ontology consortium. Briefings in bioinformatics 656 21873635
2004 The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC). Genome research 438 15489334
1996 Normalization and subtraction: two approaches to facilitate gene discovery. Genome research 401 8889548
2007 Cep68 and Cep215 (Cdk5rap2) are required for centrosome cohesion. Journal of cell science 176 18042621
2013 In-depth proteomic analyses of exosomes isolated from expressed prostatic secretions in urine. Proteomics 138 23533145
2005 A scan of chromosome 10 identifies a novel locus showing strong association with late-onset Alzheimer disease. American journal of human genetics 137 16385451
2010 Personalized smoking cessation: interactions between nicotine dose, dependence and quit-success genotype score. Molecular medicine (Cambridge, Mass.) 108 20379614
2010 A genome-wide association study of the metabolic syndrome in Indian Asian men. PloS one 95 20694148
2009 Glomus tumors in neurofibromatosis type 1: genetic, functional, and clinical evidence of a novel association. Cancer research 91 19738042
2002 Molecular analysis of expansion, differentiation, and growth factor treatment of human chondrocytes identifies differentiation markers and growth-related genes. Biochemical and biophysical research communications 91 12054597
2014 Degradation of Cep68 and PCNT cleavage mediate Cep215 removal from the PCM to allow centriole separation, disengagement and licensing. Nature cell biology 70 25503564
2006 Chondrocyte secreted CRTAC1: a glycosylated extracellular matrix molecule of human articular cartilage. Matrix biology : journal of the International Society for Matrix Biology 68 17074475
2010 Genome-wide and follow-up studies identify CEP68 gene variants associated with risk of aspirin-intolerant asthma. PloS one 62 21072201
2019 Extensive disruption of protein interactions by genetic variants across the allele frequency spectrum in human populations. Nature communications 60 31515488
2007 Comparative analysis of human conjunctival and corneal epithelial gene expression with oligonucleotide microarrays. Investigative ophthalmology & visual science 60 17460260
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 Centlein mediates an interaction between C-Nap1 and Cep68 to maintain centrosome cohesion. Journal of cell science 53 24554434
2021 The CRTAC1 Protein in Plasma Is Associated With Osteoarthritis and Predicts Progression to Joint Replacement: A Large-Scale Proteomics Scan in Iceland. Arthritis & rheumatology (Hoboken, N.J.) 52 33982893
2006 Sonic hedgehog protein promotes proliferation and chondrogenic differentiation of bone marrow-derived mesenchymal stem cells in vitro. Journal of orthopaedic science : official journal of the Japanese Orthopaedic Association 45 17013738
2010 Regulated gene expression in cultured type II cells of adult human lung. American journal of physiology. Lung cellular and molecular physiology 44 20382749
2007 Phosphoproteomics identified Endofin, DCBLD2, and KIAA0582 as novel tyrosine phosphorylation targets of EGF signaling and Iressa in human cancer cells. Proteomics 44 17570516
2023 Plasma proteomics identifies CRTAC1 as a biomarker for osteoarthritis severity and progression. Rheumatology (Oxford, England) 43 35924962
2001 Chondrocyte expressed protein-68 (CEP-68), a novel human marker gene for cultured chondrocytes. The Biochemical journal 38 11139377
2022 Cartilage Acidic Protein 1 in Plasma Associates With Prevalent Osteoarthritis and Predicts Future Risk as Well as Progression to Joint Replacements: Results From the UK Biobank Resource. Arthritis & rheumatology (Hoboken, N.J.) 28 36239377
2021 CRTAC1 (Cartilage acidic protein 1) inhibits cell proliferation, migration, invasion and epithelial-mesenchymal transition (EMT) process in bladder cancer by downregulating Yin Yang 1 (YY1) to inactivate the TGF-β pathway. Bioengineered 26 34818994
2016 Sex-Specific Protection of Osteoarthritis by Deleting Cartilage Acid Protein 1. PloS one 26 27415616
2007 Detection of bone and cartilage-related proteins in plasma of patients with a bone fracture using liquid chromatography-mass spectrometry. International orthopaedics 26 17602227
2022 Mass spectrometry-based proteomics identify novel serum osteoarthritis biomarkers. Arthritis research & therapy 25 35606786
2020 Down-regulation of CRTAC1 attenuates UVB-induced pyroptosis in HLECs through inhibiting ROS production. Biochemical and biophysical research communications 25 32838966
2016 Inhibition of Cartilage Acidic Protein 1 Reduces Ultraviolet B Irradiation Induced-Apoptosis through P38 Mitogen-Activated Protein Kinase and Jun Amino-Terminal Kinase Pathways. Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology 22 27855397
2021 Prion protein oligomers cause neuronal cytoskeletal damage in rapidly progressive Alzheimer's disease. Molecular neurodegeneration 21 33618749
2015 Cep68 can be regulated by Nek2 and SCF complex. European journal of cell biology 21 25704143
2014 Variants of CEP68 gene are associated with acute urticaria/angioedema induced by multiple non-steroidal anti-inflammatory drugs. PloS one 19 24618698
2017 Rootletin prevents Cep68 from VHL-mediated proteasomal degradation to maintain centrosome cohesion. Biochimica et biophysica acta. Molecular cell research 13 28089774
2018 Polymorphisms in CEP68 gene associated with risk of immediate selective reactions to non-steroidal anti-inflammatory drugs. The pharmacogenomics journal 9 30093714
2017 Centrosomal MCM7 strengthens the Cep68-VHL interaction and excessive MCM7 leads to centrosome splitting resulting from increase in Cep68 ubiquitination and proteasomal degradation. Biochemical and biophysical research communications 7 28578000
2026 Atrial Fibrillation and Primary Cilia-Associated Genes: The Role of CEP68. International journal of molecular sciences 0 41683918