{"gene":"CEP68","run_date":"2026-06-09T22:57:18","timeline":{"discoveries":[{"year":2007,"finding":"CEP68 localizes to fibres emanating from the proximal ends of centrioles during interphase and dissociates from centrosomes during mitosis. Knockdown of CEP68 causes centrosome splitting, establishing a required role in centrosome cohesion. CEP68 and rootletin depend on each other and on C-Nap1 for centriole association, and CEP68 is readily recruited to ectopic rootletin fibres, indicating it cooperates with rootletin and C-Nap1 in maintaining the intercentrosomal linker.","method":"siRNA knockdown, immunofluorescence localization, overexpression/ectopic fibre recruitment assays","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (KD with specific phenotype, localization, epistatic dependency experiments), foundational paper replicated by subsequent work","pmids":["18042621"],"is_preprint":false},{"year":2014,"finding":"CEP68 is degraded in prometaphase via the SCF(βTrCP) ubiquitin ligase. PLK1 phosphorylates CEP68 on Ser332, creating a phosphodegron recognized by βTrCP. CEP68 forms a complex with Cep215 (Cdk5Rap2) and pericentrin (PCNT); its degradation allows removal of Cep215 from the peripheral PCM, which is required to prevent aberrant centriole separation following disengagement.","method":"Mass spectrometry (interactome), co-immunoprecipitation, in vitro ubiquitylation assay, phosphorylation site mutagenesis, siRNA knockdown with centrosome phenotype readout","journal":"Nature cell biology","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — in vitro ubiquitylation, phospho-site mutagenesis, reciprocal Co-IP/MS, loss-of-function phenotype, multiple orthogonal methods in a single rigorous study","pmids":["25503564"],"is_preprint":false},{"year":2014,"finding":"Centlein (CNTLN) directly interacts with both C-Nap1 and CEP68, acting as a molecular bridge between them at the proximal ends of centrioles. Depletion of centlein impairs recruitment of CEP68 to centrosomes and causes centrosome splitting. Both centlein and CEP68 are phosphorylation substrates of Nek2A.","method":"Co-immunoprecipitation, yeast two-hybrid, siRNA knockdown, immunofluorescence, in vitro kinase assay","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct interaction confirmed by yeast two-hybrid and Co-IP, Nek2A kinase assay, KD with defined centrosome phenotype; replicated across multiple methods","pmids":["24554434"],"is_preprint":false},{"year":2018,"finding":"STED super-resolution microscopy revealed that the centrosome linker is organized as a periodic rootletin/CEP68 network. C-Nap1 forms a ring at each centriole that anchors rootletin rings and rootletin/CEP68 fibres. Rootletin binds CEP68 via its C-terminal spectrin repeat-containing region in 75-nm intervals. CEP68 modulates the branching of rootletin filaments off centrioles and regulates the thickness of rootletin fibres.","method":"STED nanoscopy, structured illumination microscopy, siRNA knockdown, domain-mapping co-immunoprecipitation","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — direct super-resolution structural imaging combined with domain-mapping Co-IP and KD phenotype, multiple orthogonal approaches","pmids":["29463719"],"is_preprint":false},{"year":2015,"finding":"The C-terminal 300–400 amino acids of CEP68 are necessary for its localization to interphase centrosomes, while the C-terminal 400–500 aa region regulates its dissociation from centrosomes at mitotic onset. Nek2 phosphorylates CEP68 in vivo and this phosphorylation promotes CEP68 degradation in mitosis. The SCF(βTrCP) complex targets CEP68 for proteasomal destruction at mitosis.","method":"Truncation/deletion constructs with live-cell localization, in vivo phosphorylation assay, co-immunoprecipitation with βTrCP","journal":"European journal of cell biology","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — in vivo phosphorylation and Co-IP with βTrCP, deletion mapping; single lab, consistent with Pagan et al. 2014 but less rigorous methodology described","pmids":["25704143"],"is_preprint":false},{"year":2017,"finding":"Rootletin prevents CEP68 from VHL-mediated proteasomal degradation. In the absence of rootletin, the VHL E3 ligase complex ubiquitinates CEP68 both in vitro and in vivo, leading to its proteasomal degradation and centrosome splitting. Co-silencing of rootletin and VHL, or expression of a stable CEP68 mutant that lacks VHL-β-domain binding or polyubiquitylation sites, rescues centrosome splitting caused by rootletin depletion.","method":"In vitro ubiquitylation assay, co-immunoprecipitation, siRNA double knockdown (epistasis), stable CEP68 mutant rescue experiments","journal":"Biochimica et biophysica acta. Molecular cell research","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — in vitro ubiquitylation reconstitution, mutagenesis rescue, epistatic double-KD, multiple orthogonal approaches in single study","pmids":["28089774"],"is_preprint":false},{"year":2017,"finding":"MCM7 directly binds CEP68 in vitro and forms a complex with CEP68 and VHL in vivo. MCM7 overexpression facilitates the CEP68–VHL interaction, enhancing CEP68 ubiquitination and proteasomal degradation, resulting in centrosome splitting. Depletion of MCM7 weakens the CEP68–VHL interaction.","method":"In vitro pull-down, co-immunoprecipitation, overexpression and knockdown with centrosome splitting readout, ubiquitination assay","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — in vitro binding and in vivo Co-IP, functional OE/KD phenotype; single lab, moderate methodology detail","pmids":["28578000"],"is_preprint":false},{"year":2007,"finding":"CEP68 (KIAA0582) is a novel tyrosine-phosphorylation target of EGF receptor signaling in human cancer cells. EGF-induced tyrosine phosphorylation of CEP68 is inhibited by Iressa (gefitinib, an EGFR inhibitor), indicating EGFR kinase activity is required for this modification.","method":"cICAT-based LC-MS/MS phosphoproteomics, immunoprecipitation/immunoblot validation with EGFR inhibitor treatment","journal":"Proteomics","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — validated by IP/immunoblot with inhibitor, but single lab and limited mechanistic follow-up on CEP68 specifically","pmids":["17570516"],"is_preprint":false}],"current_model":"CEP68 is an intercentrosomal linker protein that localizes to periodic rootletin/CEP68 fibres anchored at C-Nap1 rings on the proximal centriole ends; it is recruited to centrioles via a C-terminal localization domain and bridges rootletin and C-Nap1 (through centlein) to maintain centrosome cohesion during interphase. At mitotic onset, PLK1 phosphorylates CEP68 on Ser332, triggering SCF(βTrCP)-mediated ubiquitination and proteasomal degradation, which releases Cep215 from the peripheral PCM and allows centrosome separation; during interphase, rootletin protects CEP68 from VHL-mediated ubiquitination and degradation, while MCM7 can compete by enhancing the CEP68–VHL interaction. CEP68 is also a tyrosine-phosphorylation substrate of EGFR signaling, though the functional consequence of this modification remains undefined."},"narrative":{"mechanistic_narrative":"CEP68 is an intercentrosomal linker protein that maintains centrosome cohesion during interphase by cooperating with rootletin and C-Nap1 in the fibrous tether that joins the two centrioles [PMID:18042621]. It localizes to fibres emanating from the proximal centriole ends and dissociates from centrosomes at mitosis; its depletion causes premature centrosome splitting, and its centriolar association is mutually dependent on rootletin and C-Nap1 [PMID:18042621]. Super-resolution imaging places CEP68 within a periodic rootletin/CEP68 network anchored at C-Nap1 rings, where CEP68 binds the C-terminal spectrin-repeat region of rootletin and modulates the branching and thickness of rootletin filaments [PMID:29463719]; centlein bridges CEP68 to C-Nap1 and is required for CEP68 recruitment to centrosomes [PMID:24554434]. A C-terminal region of CEP68 governs its interphase centriolar localization and its mitotic dissociation [PMID:25704143]. Linker disassembly at mitotic onset is driven by regulated proteolysis: PLK1 phosphorylates CEP68 on Ser332 to create a phosphodegron recognized by SCF(βTrCP), and degradation of the CEP68–Cep215–pericentrin complex permits removal of Cep215 from the peripheral PCM to license centriole separation [PMID:25503564, PMID:25704143]. During interphase, rootletin shields CEP68 from VHL-mediated ubiquitination and degradation, and MCM7 antagonizes this protection by enhancing the CEP68–VHL interaction [PMID:28089774, PMID:28578000]. CEP68 is additionally a tyrosine-phosphorylation substrate of EGFR signaling, with the functional consequence of this modification uncharacterized in the available corpus [PMID:17570516].","teleology":[{"year":2007,"claim":"Established CEP68 as a required component of the interphase intercentrosomal linker, defining its core cellular role in centrosome cohesion.","evidence":"siRNA knockdown with centrosome-splitting readout, immunofluorescence localization, and ectopic rootletin fibre recruitment in human cells","pmids":["18042621"],"confidence":"High","gaps":["Did not resolve the direct binding interface between CEP68 and rootletin/C-Nap1","Molecular structure and stoichiometry of the linker not defined"]},{"year":2007,"claim":"Identified CEP68 as a tyrosine-phosphorylation target downstream of EGFR, linking it to growth-factor signaling.","evidence":"cICAT LC-MS/MS phosphoproteomics with IP/immunoblot validation under EGFR inhibitor (gefitinib) treatment in cancer cells","pmids":["17570516"],"confidence":"Medium","gaps":["Functional consequence of EGFR-driven tyrosine phosphorylation on CEP68 not determined","Phosphosite(s) and responsible kinase relationship to centrosome function unestablished"]},{"year":2014,"claim":"Defined the mitotic destruction pathway that dismantles the linker, showing how phosphorylation-triggered proteolysis licenses centrosome separation.","evidence":"Interactome MS, reciprocal Co-IP, in vitro ubiquitylation, Ser332 phospho-site mutagenesis, and siRNA with centrosome phenotype","pmids":["25503564"],"confidence":"High","gaps":["Did not address how PLK1 access to CEP68 is temporally controlled","Relationship between Cep215 release and PCM expansion mechanistically incomplete"]},{"year":2014,"claim":"Identified centlein as the molecular bridge connecting CEP68 to C-Nap1, explaining how CEP68 is recruited to the proximal centriole.","evidence":"Yeast two-hybrid, Co-IP, siRNA knockdown with splitting phenotype, and in vitro Nek2A kinase assay","pmids":["24554434"],"confidence":"High","gaps":["Functional consequence of Nek2A phosphorylation of CEP68/centlein not resolved","Spatial arrangement of the centlein bridge within the fibre not defined"]},{"year":2015,"claim":"Mapped the CEP68 regions controlling interphase centriolar localization versus mitotic dissociation and implicated Nek2 phosphorylation in its mitotic degradation.","evidence":"Truncation/deletion localization constructs, in vivo phosphorylation assay, and Co-IP with βTrCP","pmids":["25704143"],"confidence":"Medium","gaps":["Precise localization determinants within the C-terminus not defined at residue level","Interplay of Nek2 and PLK1 phosphorylation in degradation not reconciled"]},{"year":2017,"claim":"Revealed an interphase stabilization mechanism in which rootletin protects CEP68 from VHL-mediated degradation, coupling linker integrity to CEP68 abundance.","evidence":"In vitro ubiquitylation, Co-IP, double siRNA epistasis, and stable CEP68 mutant rescue of splitting","pmids":["28089774"],"confidence":"High","gaps":["How rootletin physically occludes VHL from CEP68 not structurally defined","Whether this pathway operates outside rootletin-deficient conditions unclear"]},{"year":2017,"claim":"Identified MCM7 as an enhancer of CEP68–VHL engagement, providing a counterweight to rootletin-based protection.","evidence":"In vitro pull-down, in vivo Co-IP, overexpression/knockdown with splitting readout, and ubiquitination assay","pmids":["28578000"],"confidence":"Medium","gaps":["Physiological trigger for MCM7-driven CEP68 degradation not established","Single-lab finding without reciprocal in vivo validation across systems"]},{"year":null,"claim":"How EGFR-driven tyrosine phosphorylation of CEP68 intersects with its centrosome-linker and degradation functions remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No functional readout connecting EGFR signaling to centrosome cohesion via CEP68","Tyrosine phosphosite identity and downstream effect unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[0,3]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[0,3]}],"localization":[{"term_id":"GO:0005815","term_label":"microtubule organizing center","supporting_discovery_ids":[0,3]},{"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":[0,1]},{"term_id":"R-HSA-1852241","term_label":"Organelle biogenesis and maintenance","supporting_discovery_ids":[0,3]}],"complexes":["centrosome linker (rootletin/CEP68 fibre)","CEP68-Cep215-pericentrin complex"],"partners":["CROCC","CEP250","CNTLN","CDK5RAP2","PCNT","VHL","MCM7","BTRC"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9NQ79","full_name":"Cartilage acidic protein 1","aliases":["68 kDa chondrocyte-expressed protein","CEP-68","ASPIC"],"length_aa":661,"mass_kda":71.4,"function":"","subcellular_location":"Secreted, extracellular space, extracellular matrix","url":"https://www.uniprot.org/uniprotkb/Q9NQ79/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CEP68","classification":"Not Classified","n_dependent_lines":80,"n_total_lines":1208,"dependency_fraction":0.06622516556291391},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/CEP68","total_profiled":1310},"omim":[{"mim_id":"621147","title":"COILED-COIL DOMAIN-CONTAINING PROTEIN 102B; CCDC102B","url":"https://www.omim.org/entry/621147"},{"mim_id":"616889","title":"CENTROSOMAL PROTEIN, 68-KD; CEP68","url":"https://www.omim.org/entry/616889"},{"mim_id":"615776","title":"CILIARY ROOTLET COILED-COIL PROTEIN; CROCC","url":"https://www.omim.org/entry/615776"},{"mim_id":"611870","title":"CENTLEIN; CNTLN","url":"https://www.omim.org/entry/611870"},{"mim_id":"609689","title":"CENTROSOMAL PROTEIN, 250-KD; CEP250","url":"https://www.omim.org/entry/609689"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Centriolar satellite","reliability":"Approved"},{"location":"Cell Junctions","reliability":"Additional"},{"location":"Basal body","reliability":"Additional"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/CEP68"},"hgnc":{"alias_symbol":[],"prev_symbol":["KIAA0582"]},"alphafold":{"accession":"Q9NQ79","domains":[{"cath_id":"2.130.10.130","chopping":"46-451","consensus_level":"medium","plddt":94.9409,"start":46,"end":451},{"cath_id":"-","chopping":"562-594","consensus_level":"medium","plddt":90.3539,"start":562,"end":594}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NQ79","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NQ79-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NQ79-F1-predicted_aligned_error_v6.png","plddt_mean":85.69},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CEP68","jax_strain_url":"https://www.jax.org/strain/search?query=CEP68"},"sequence":{"accession":"Q9NQ79","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9NQ79.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9NQ79/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NQ79"}},"corpus_meta":[{"pmid":"18042621","id":"PMC_18042621","title":"Cep68 and Cep215 (Cdk5rap2) are required for centrosome cohesion.","date":"2007","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/18042621","citation_count":176,"is_preprint":false},{"pmid":"25503564","id":"PMC_25503564","title":"Degradation of Cep68 and PCNT cleavage mediate Cep215 removal from the PCM to allow centriole separation, disengagement and licensing.","date":"2014","source":"Nature cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/25503564","citation_count":70,"is_preprint":false},{"pmid":"21072201","id":"PMC_21072201","title":"Genome-wide and follow-up studies identify CEP68 gene variants associated with risk of aspirin-intolerant asthma.","date":"2010","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/21072201","citation_count":62,"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":"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":"17570516","id":"PMC_17570516","title":"Phosphoproteomics identified Endofin, DCBLD2, and KIAA0582 as novel tyrosine phosphorylation targets of EGF signaling and Iressa in human cancer cells.","date":"2007","source":"Proteomics","url":"https://pubmed.ncbi.nlm.nih.gov/17570516","citation_count":44,"is_preprint":false},{"pmid":"11139377","id":"PMC_11139377","title":"Chondrocyte expressed protein-68 (CEP-68), a novel human marker gene for cultured chondrocytes.","date":"2001","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/11139377","citation_count":38,"is_preprint":false},{"pmid":"25704143","id":"PMC_25704143","title":"Cep68 can be regulated by Nek2 and SCF complex.","date":"2015","source":"European journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/25704143","citation_count":21,"is_preprint":false},{"pmid":"24618698","id":"PMC_24618698","title":"Variants of CEP68 gene are associated with acute urticaria/angioedema induced by multiple non-steroidal anti-inflammatory drugs.","date":"2014","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/24618698","citation_count":19,"is_preprint":false},{"pmid":"28089774","id":"PMC_28089774","title":"Rootletin prevents Cep68 from VHL-mediated proteasomal degradation to maintain centrosome cohesion.","date":"2017","source":"Biochimica et biophysica acta. Molecular cell research","url":"https://pubmed.ncbi.nlm.nih.gov/28089774","citation_count":13,"is_preprint":false},{"pmid":"30093714","id":"PMC_30093714","title":"Polymorphisms in CEP68 gene associated with risk of immediate selective reactions to non-steroidal anti-inflammatory drugs.","date":"2018","source":"The pharmacogenomics journal","url":"https://pubmed.ncbi.nlm.nih.gov/30093714","citation_count":9,"is_preprint":false},{"pmid":"28578000","id":"PMC_28578000","title":"Centrosomal MCM7 strengthens the Cep68-VHL interaction and excessive MCM7 leads to centrosome splitting resulting from increase in Cep68 ubiquitination and proteasomal degradation.","date":"2017","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/28578000","citation_count":7,"is_preprint":false},{"pmid":"41683918","id":"PMC_41683918","title":"Atrial Fibrillation and Primary Cilia-Associated Genes: The Role of CEP68.","date":"2026","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/41683918","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":8283,"output_tokens":2433,"usd":0.030672,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9541,"output_tokens":2852,"usd":0.059502,"stage2_stop_reason":"end_turn"},"total_usd":0.090174,"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\": 2007,\n      \"finding\": \"CEP68 localizes to fibres emanating from the proximal ends of centrioles during interphase and dissociates from centrosomes during mitosis. Knockdown of CEP68 causes centrosome splitting, establishing a required role in centrosome cohesion. CEP68 and rootletin depend on each other and on C-Nap1 for centriole association, and CEP68 is readily recruited to ectopic rootletin fibres, indicating it cooperates with rootletin and C-Nap1 in maintaining the intercentrosomal linker.\",\n      \"method\": \"siRNA knockdown, immunofluorescence localization, overexpression/ectopic fibre recruitment assays\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (KD with specific phenotype, localization, epistatic dependency experiments), foundational paper replicated by subsequent work\",\n      \"pmids\": [\"18042621\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"CEP68 is degraded in prometaphase via the SCF(βTrCP) ubiquitin ligase. PLK1 phosphorylates CEP68 on Ser332, creating a phosphodegron recognized by βTrCP. CEP68 forms a complex with Cep215 (Cdk5Rap2) and pericentrin (PCNT); its degradation allows removal of Cep215 from the peripheral PCM, which is required to prevent aberrant centriole separation following disengagement.\",\n      \"method\": \"Mass spectrometry (interactome), co-immunoprecipitation, in vitro ubiquitylation assay, phosphorylation site mutagenesis, siRNA knockdown with centrosome phenotype readout\",\n      \"journal\": \"Nature cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — in vitro ubiquitylation, phospho-site mutagenesis, reciprocal Co-IP/MS, loss-of-function phenotype, multiple orthogonal methods in a single rigorous study\",\n      \"pmids\": [\"25503564\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Centlein (CNTLN) directly interacts with both C-Nap1 and CEP68, acting as a molecular bridge between them at the proximal ends of centrioles. Depletion of centlein impairs recruitment of CEP68 to centrosomes and causes centrosome splitting. Both centlein and CEP68 are phosphorylation substrates of Nek2A.\",\n      \"method\": \"Co-immunoprecipitation, yeast two-hybrid, siRNA knockdown, immunofluorescence, in vitro kinase assay\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct interaction confirmed by yeast two-hybrid and Co-IP, Nek2A kinase assay, KD with defined centrosome phenotype; replicated across multiple methods\",\n      \"pmids\": [\"24554434\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"STED super-resolution microscopy revealed that the centrosome linker is organized as a periodic rootletin/CEP68 network. C-Nap1 forms a ring at each centriole that anchors rootletin rings and rootletin/CEP68 fibres. Rootletin binds CEP68 via its C-terminal spectrin repeat-containing region in 75-nm intervals. CEP68 modulates the branching of rootletin filaments off centrioles and regulates the thickness of rootletin fibres.\",\n      \"method\": \"STED nanoscopy, structured illumination microscopy, siRNA knockdown, domain-mapping co-immunoprecipitation\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — direct super-resolution structural imaging combined with domain-mapping Co-IP and KD phenotype, multiple orthogonal approaches\",\n      \"pmids\": [\"29463719\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"The C-terminal 300–400 amino acids of CEP68 are necessary for its localization to interphase centrosomes, while the C-terminal 400–500 aa region regulates its dissociation from centrosomes at mitotic onset. Nek2 phosphorylates CEP68 in vivo and this phosphorylation promotes CEP68 degradation in mitosis. The SCF(βTrCP) complex targets CEP68 for proteasomal destruction at mitosis.\",\n      \"method\": \"Truncation/deletion constructs with live-cell localization, in vivo phosphorylation assay, co-immunoprecipitation with βTrCP\",\n      \"journal\": \"European journal of cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — in vivo phosphorylation and Co-IP with βTrCP, deletion mapping; single lab, consistent with Pagan et al. 2014 but less rigorous methodology described\",\n      \"pmids\": [\"25704143\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Rootletin prevents CEP68 from VHL-mediated proteasomal degradation. In the absence of rootletin, the VHL E3 ligase complex ubiquitinates CEP68 both in vitro and in vivo, leading to its proteasomal degradation and centrosome splitting. Co-silencing of rootletin and VHL, or expression of a stable CEP68 mutant that lacks VHL-β-domain binding or polyubiquitylation sites, rescues centrosome splitting caused by rootletin depletion.\",\n      \"method\": \"In vitro ubiquitylation assay, co-immunoprecipitation, siRNA double knockdown (epistasis), stable CEP68 mutant rescue experiments\",\n      \"journal\": \"Biochimica et biophysica acta. Molecular cell research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — in vitro ubiquitylation reconstitution, mutagenesis rescue, epistatic double-KD, multiple orthogonal approaches in single study\",\n      \"pmids\": [\"28089774\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"MCM7 directly binds CEP68 in vitro and forms a complex with CEP68 and VHL in vivo. MCM7 overexpression facilitates the CEP68–VHL interaction, enhancing CEP68 ubiquitination and proteasomal degradation, resulting in centrosome splitting. Depletion of MCM7 weakens the CEP68–VHL interaction.\",\n      \"method\": \"In vitro pull-down, co-immunoprecipitation, overexpression and knockdown with centrosome splitting readout, ubiquitination assay\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — in vitro binding and in vivo Co-IP, functional OE/KD phenotype; single lab, moderate methodology detail\",\n      \"pmids\": [\"28578000\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"CEP68 (KIAA0582) is a novel tyrosine-phosphorylation target of EGF receptor signaling in human cancer cells. EGF-induced tyrosine phosphorylation of CEP68 is inhibited by Iressa (gefitinib, an EGFR inhibitor), indicating EGFR kinase activity is required for this modification.\",\n      \"method\": \"cICAT-based LC-MS/MS phosphoproteomics, immunoprecipitation/immunoblot validation with EGFR inhibitor treatment\",\n      \"journal\": \"Proteomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — validated by IP/immunoblot with inhibitor, but single lab and limited mechanistic follow-up on CEP68 specifically\",\n      \"pmids\": [\"17570516\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CEP68 is an intercentrosomal linker protein that localizes to periodic rootletin/CEP68 fibres anchored at C-Nap1 rings on the proximal centriole ends; it is recruited to centrioles via a C-terminal localization domain and bridges rootletin and C-Nap1 (through centlein) to maintain centrosome cohesion during interphase. At mitotic onset, PLK1 phosphorylates CEP68 on Ser332, triggering SCF(βTrCP)-mediated ubiquitination and proteasomal degradation, which releases Cep215 from the peripheral PCM and allows centrosome separation; during interphase, rootletin protects CEP68 from VHL-mediated ubiquitination and degradation, while MCM7 can compete by enhancing the CEP68–VHL interaction. CEP68 is also a tyrosine-phosphorylation substrate of EGFR signaling, though the functional consequence of this modification remains undefined.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CEP68 is an intercentrosomal linker protein that maintains centrosome cohesion during interphase by cooperating with rootletin and C-Nap1 in the fibrous tether that joins the two centrioles [#0]. It localizes to fibres emanating from the proximal centriole ends and dissociates from centrosomes at mitosis; its depletion causes premature centrosome splitting, and its centriolar association is mutually dependent on rootletin and C-Nap1 [#0]. Super-resolution imaging places CEP68 within a periodic rootletin/CEP68 network anchored at C-Nap1 rings, where CEP68 binds the C-terminal spectrin-repeat region of rootletin and modulates the branching and thickness of rootletin filaments [#3]; centlein bridges CEP68 to C-Nap1 and is required for CEP68 recruitment to centrosomes [#2]. A C-terminal region of CEP68 governs its interphase centriolar localization and its mitotic dissociation [#4]. Linker disassembly at mitotic onset is driven by regulated proteolysis: PLK1 phosphorylates CEP68 on Ser332 to create a phosphodegron recognized by SCF(\\u03b2TrCP), and degradation of the CEP68\\u2013Cep215\\u2013pericentrin complex permits removal of Cep215 from the peripheral PCM to license centriole separation [#1, #4]. During interphase, rootletin shields CEP68 from VHL-mediated ubiquitination and degradation, and MCM7 antagonizes this protection by enhancing the CEP68\\u2013VHL interaction [#5, #6]. CEP68 is additionally a tyrosine-phosphorylation substrate of EGFR signaling, with the functional consequence of this modification uncharacterized in the available corpus [#7].\",\n  \"teleology\": [\n    {\n      \"year\": 2007,\n      \"claim\": \"Established CEP68 as a required component of the interphase intercentrosomal linker, defining its core cellular role in centrosome cohesion.\",\n      \"evidence\": \"siRNA knockdown with centrosome-splitting readout, immunofluorescence localization, and ectopic rootletin fibre recruitment in human cells\",\n      \"pmids\": [\"18042621\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Did not resolve the direct binding interface between CEP68 and rootletin/C-Nap1\",\n        \"Molecular structure and stoichiometry of the linker not defined\"\n      ]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Identified CEP68 as a tyrosine-phosphorylation target downstream of EGFR, linking it to growth-factor signaling.\",\n      \"evidence\": \"cICAT LC-MS/MS phosphoproteomics with IP/immunoblot validation under EGFR inhibitor (gefitinib) treatment in cancer cells\",\n      \"pmids\": [\"17570516\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Functional consequence of EGFR-driven tyrosine phosphorylation on CEP68 not determined\",\n        \"Phosphosite(s) and responsible kinase relationship to centrosome function unestablished\"\n      ]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Defined the mitotic destruction pathway that dismantles the linker, showing how phosphorylation-triggered proteolysis licenses centrosome separation.\",\n      \"evidence\": \"Interactome MS, reciprocal Co-IP, in vitro ubiquitylation, Ser332 phospho-site mutagenesis, and siRNA with centrosome phenotype\",\n      \"pmids\": [\"25503564\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Did not address how PLK1 access to CEP68 is temporally controlled\",\n        \"Relationship between Cep215 release and PCM expansion mechanistically incomplete\"\n      ]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Identified centlein as the molecular bridge connecting CEP68 to C-Nap1, explaining how CEP68 is recruited to the proximal centriole.\",\n      \"evidence\": \"Yeast two-hybrid, Co-IP, siRNA knockdown with splitting phenotype, and in vitro Nek2A kinase assay\",\n      \"pmids\": [\"24554434\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Functional consequence of Nek2A phosphorylation of CEP68/centlein not resolved\",\n        \"Spatial arrangement of the centlein bridge within the fibre not defined\"\n      ]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Mapped the CEP68 regions controlling interphase centriolar localization versus mitotic dissociation and implicated Nek2 phosphorylation in its mitotic degradation.\",\n      \"evidence\": \"Truncation/deletion localization constructs, in vivo phosphorylation assay, and Co-IP with \\u03b2TrCP\",\n      \"pmids\": [\"25704143\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Precise localization determinants within the C-terminus not defined at residue level\",\n        \"Interplay of Nek2 and PLK1 phosphorylation in degradation not reconciled\"\n      ]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Revealed an interphase stabilization mechanism in which rootletin protects CEP68 from VHL-mediated degradation, coupling linker integrity to CEP68 abundance.\",\n      \"evidence\": \"In vitro ubiquitylation, Co-IP, double siRNA epistasis, and stable CEP68 mutant rescue of splitting\",\n      \"pmids\": [\"28089774\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"How rootletin physically occludes VHL from CEP68 not structurally defined\",\n        \"Whether this pathway operates outside rootletin-deficient conditions unclear\"\n      ]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Identified MCM7 as an enhancer of CEP68\\u2013VHL engagement, providing a counterweight to rootletin-based protection.\",\n      \"evidence\": \"In vitro pull-down, in vivo Co-IP, overexpression/knockdown with splitting readout, and ubiquitination assay\",\n      \"pmids\": [\"28578000\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Physiological trigger for MCM7-driven CEP68 degradation not established\",\n        \"Single-lab finding without reciprocal in vivo validation across systems\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How EGFR-driven tyrosine phosphorylation of CEP68 intersects with its centrosome-linker and degradation functions remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No functional readout connecting EGFR signaling to centrosome cohesion via CEP68\",\n        \"Tyrosine phosphosite identity and downstream effect unknown\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [0, 3]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [0, 3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005815\", \"supporting_discovery_ids\": [0, 3]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [0, 3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"R-HSA-1852241\", \"supporting_discovery_ids\": [0, 3]}\n    ],\n    \"complexes\": [\n      \"centrosome linker (rootletin/CEP68 fibre)\",\n      \"CEP68-Cep215-pericentrin complex\"\n    ],\n    \"partners\": [\n      \"CROCC\",\n      \"CEP250\",\n      \"CNTLN\",\n      \"CDK5RAP2\",\n      \"PCNT\",\n      \"VHL\",\n      \"MCM7\",\n      \"BTRC\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"faith_supported":6,"faith_total":6,"faith_pct":100.0}}