Affinage

CEP76

Centrosomal protein of 76 kDa · UniProt Q8TAP6

Length
659 aa
Mass
74.4 kDa
Annotated
2026-04-28
11 papers in source corpus 8 papers cited in narrative 8 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

CEP76 is a centriolar and transition zone protein that maintains centrosome number fidelity and regulates ciliary gating and assembly. It suppresses centriole re-amplification during S phase through cyclin A/CDK2-dependent phosphorylation at S83, which inhibits PLK1 activation at centrosomes; this suppressive capacity is relieved in G2 by acetylation at K279, creating a cell-cycle-dependent regulatory switch (PMID:19460342, PMID:27065328). During mitosis, CEP76 restrains cytoplasmic PLK1 activity, and its loss causes ectopic PLK1 hyperphosphorylation, defective spindle orientation, and mitotic delay (PMID:32878946). CEP76 also functions as a transition zone component essential for selective protein entry into cilia and flagella, intraflagellar transport, and cilium length control; genetic loss causes ciliopathy phenotypes in zebrafish and male infertility in mice due to defective sperm flagellum assembly (PMID:38570187, PMID:41105778).

Mechanistic history

Synthesis pass · year-by-year structured walk · 5 steps
  1. 2009 High

    The discovery that CEP76 specifically suppresses centriole re-duplication while leaving normal duplication unaffected established a previously unrecognized checkpoint-like mechanism at centrosomes and identified CP110 as a physical partner.

    Evidence Co-IP of CEP76–CP110, RNAi depletion and overexpression with centriole counting by immunofluorescence in human cells

    PMID:19460342

    Open questions at the time
    • Upstream signals controlling CEP76 were unknown
    • Mechanism by which CEP76 specifically blocks amplification but not duplication was unclear
    • Whether CEP76 functions beyond the centriole was not addressed
  2. 2016 High

    Identification of cyclin A/CDK2 phosphorylation at S83 and opposing G2-phase acetylation at K279 revealed the molecular switch by which CEP76 activity is temporally restricted to S phase and linked centriole amplification suppression to PLK1 inhibition.

    Evidence In vitro kinase assay, phospho- and acetyl-site mutagenesis, Co-IP with CDK2, cancer variant (S83C) characterization, centriole counting

    PMID:27065328

    Open questions at the time
    • The acetyltransferase and deacetylase acting on K279 were not identified
    • How phospho-CEP76 mechanistically inhibits PLK1 activation was unresolved
    • Whether S83C or analogous mutations drive centrosome amplification in tumors in vivo was not tested
  3. 2020 High

    Demonstrating that CEP76 physically binds PLK1 and suppresses its cytoplasmic hyperactivation during mitosis extended CEP76's function beyond interphase centriole control to mitotic spindle orientation.

    Evidence Co-IP of CEP76–PLK1, RNAi screen, immunofluorescence of PLK1 aggregates and spindle angle, rescue by PLK1 kinase inhibitor

    PMID:32878946

    Open questions at the time
    • Whether PLK1 inhibition by CEP76 is direct (e.g., allosteric) or indirect was not resolved
    • The relationship between mitotic PLK1 suppression and the S83-phosphorylation pathway was not addressed
    • Relevance to non-transformed primary cells and in vivo tissues was untested
  4. 2024 High

    Genetic knockout in mice revealed that CEP76 is a transition zone protein required for selective import of motility factors (DNAH2, AKAP4) into the flagellar compartment, establishing it as essential for sperm tail assembly and male fertility.

    Evidence Cep76-knockout mouse, immunofluorescence, Western blot, sperm motility analysis

    PMID:38570187

    Open questions at the time
    • Whether CEP76 directly gates protein entry or acts indirectly through transition zone structure was unclear
    • Ciliary roles in somatic tissues were not examined in this model
    • Whether the centriole amplification suppression and transition zone gating functions are mechanistically linked was unknown
  5. 2025 High

    Proteomics and multi-organism studies unified CEP76's centrosomal and ciliary roles by showing it is required for transition zone architecture, IFT88-mediated anterograde transport, and cilium length, with human patient fibroblasts and zebrafish mutants displaying ciliopathy phenotypes.

    Evidence Proteomics (CEP76 interactome identifying CP110, CEP97, ALMS1, LUZP1), RPE1 RNAi, patient fibroblasts, zebrafish cep76 mutants, complementation assays

    PMID:41105778

    Open questions at the time
    • The direct biochemical activity of CEP76 at the transition zone (structural scaffold vs. enzymatic) remains unresolved
    • Whether ALMS1 and LUZP1 interactions are direct or within larger complexes was not determined
    • The clinical spectrum of human CEP76 mutations is only beginning to be defined

Open questions

Synthesis pass · forward-looking unresolved questions
  • Whether CEP76 possesses catalytic peptidase activity (predicted computationally) and how such activity would relate to its centriole amplification and transition zone functions remains the central unresolved mechanistic question.
  • No experimental demonstration of CEP76 peptidase activity exists
  • The relationship between centrosome number control and ciliary gating functions has not been mechanistically connected
  • In vivo consequences of CEP76 loss in non-reproductive somatic tissues in mammals are incompletely characterized

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0098772 molecular function regulator activity 3
Localization
GO:0005815 microtubule organizing center 3 GO:0005929 cilium 2
Pathway
R-HSA-1640170 Cell Cycle 3 R-HSA-1852241 Organelle biogenesis and maintenance 2
Partners
ALMS1CEP97CP110LUZP1PLK1

Evidence

Reading pass · 8 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2009 CEP76 is a centriolar protein that interacts with CP110 and specifically restrains centriole re-duplication (amplification) but not normal centriole duplication; depletion of CEP76 drives accumulation of centriolar intermediates, while enforced expression inhibits centriole amplification without affecting normal duplication. Co-immunoprecipitation (CEP76–CP110 interaction), RNAi depletion, overexpression, immunofluorescence microscopy of centriole number Developmental Cell High 19460342
2016 CEP76 is phosphorylated by cyclin A/CDK2 at serine 83 during S phase; this phosphorylation is required to suppress centriole amplification by inhibiting PLK1 activation and preventing premature centriole disengagement. A cancer-associated mutation S83C abrogates this function. Additionally, CEP76 is acetylated at K279 in G2 phase, which dampens its ability to inhibit amplification and blocks S83 phosphorylation, creating a temporal regulatory switch. In vitro kinase assay, phospho-site mutagenesis, acetylation assays, Co-IP (CEP76–CDK2), cancer patient variant characterization, immunofluorescence centriole counting Oncogene High 27065328
2020 CEP76 physically interacts with PLK1 and suppresses aberrant activation of cytoplasmic PLK1 during mitosis; depletion of CEP76 causes ectopic aggregation of hyperphosphorylated PLK1 in the cytoplasm, defective spindle orientation, and mitotic delay, phenotypes rescued by PLK1 kinase inhibition. Co-immunoprecipitation (CEP76–PLK1), targeted RNAi screen, immunofluorescence (PLK1 aggregates, spindle orientation), PLK1 kinase inhibitor rescue Journal of Cell Science High 32878946
2024 CEP76 functions as a male germ cell transition zone protein required for selective entry of motility proteins (DNAH2, AKAP4) into the ciliary/flagellar compartment; loss of CEP76 results in shorter, immotile sperm tails with deficits in fibrous sheath, outer dense fibres, and annulus positioning. Genetic mouse knockout (Cep76 mutation), immunofluorescence, Western blot, sperm motility analysis, protein localization by immunostaining Life Science Alliance High 38570187
2025 CEP76 is required for cilium formation and length, proper transition zone architecture, and IFT88-mediated anterograde intraflagellar transport; proteomics identified CEP76 interactors including CP110, CEP97, ALMS1, and LUZP1; patient-derived fibroblasts and CEP76-depleted RPE1 cells display these ciliary deficits, and zebrafish cep76 mutants recapitulate ciliopathy phenotypes. Proteomics (CEP76 interactome), RNAi depletion in RPE1 cells, patient fibroblast analysis, zebrafish cep76 mutants, in vitro complementation assays, immunofluorescence (IFT88, transition zone markers, cilia length) Science Advances High 41105778
2012 Computational analysis identified a transglutaminase-like (TGL) peptidase domain and a C2 domain in CEP76; the TGL domain was predicted to be catalytically active (potentially acting as a peptidase to remove tubulin modifications or cleave ciliary proteins), and the C2 domain was predicted to mediate membrane localization, suggesting CEP76 participates in a cilia-specific peptide modification system. Computational sequence analysis, domain prediction, homology modeling Cell Cycle Low 22983010
2023 Structure-based classification confirmed that CEP76 retains a catalytically active papain-like cysteine peptidase domain, suggesting a potential enzymatic function in centriole duplication regulation. Transitive remote homology searches and 3D structural modeling Journal of Biological Chemistry Low 37164157
2020 Bioinformatic analysis of TCGA data identified CEP76 loss-of-function as a candidate cause of centrosome amplification in human cancer; in cellulo validation placed CEP76 alongside other centrosome amplification suppressors. TCGA genomic/transcriptomic analysis (bioinformatics), in cellulo candidate validation Scientific Reports Low 32681070

Source papers

Stage 0 corpus · 11 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2017 Antisense oligonucleotide therapy for spinocerebellar ataxia type 2. Nature 248 28405024
2009 Cep76, a centrosomal protein that specifically restrains centriole reduplication. Developmental cell 54 19460342
2012 Novel transglutaminase-like peptidase and C2 domains elucidate the structure, biogenesis and evolution of the ciliary compartment. Cell cycle (Georgetown, Tex.) 42 22983010
2023 Identification and classification of papain-like cysteine proteinases. The Journal of biological chemistry 27 37164157
2007 A syndromic form of autosomal recessive congenital microcephaly (Jawad syndrome) maps to chromosome 18p11.22-q11.2. Human genetics 20 18071751
2016 Opposing post-translational modifications regulate Cep76 function to suppress centriole amplification. Oncogene 15 27065328
2024 Evaluating the association between placenta DNA methylation and cognitive functions in the offspring. Translational psychiatry 13 39304652
2020 Analysis of the "centrosome-ome" identifies MCPH1 deletion as a cause of centrosome amplification in human cancer. Scientific reports 13 32681070
2020 The centriole protein CEP76 negatively regulates PLK1 activity in the cytoplasm for proper mitotic progression. Journal of cell science 8 32878946
2024 Genetic mutation of Cep76 results in male infertility due to abnormal sperm tail composition. Life science alliance 7 38570187
2025 CEP76 impairment at the centrosome-cilium interface contributes to a spectrum of ciliopathies. Science advances 1 41105778