{"gene":"CEP97","run_date":"2026-04-28T17:28:52","timeline":{"discoveries":[{"year":2007,"finding":"CEP97 recruits CP110 to centrosomes; depletion of CEP97 causes CP110 disappearance from centrosomes, spindle defects, and polyploidy. Loss of CEP97 or CP110 promotes primary cilia formation in growing cells, while enforced expression of CP110 in quiescent cells suppresses ciliogenesis, establishing that CEP97 and CP110 collaborate to inhibit a ciliogenesis program.","method":"Protein complex purification, co-immunoprecipitation, siRNA depletion, dominant-negative expression, live imaging","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 — reciprocal co-IP, clean KD with defined cellular phenotypes, replicated across multiple assays in foundational paper with 385 citations","pmids":["17719545"],"is_preprint":false},{"year":2008,"finding":"CP110 interacts with CEP290 in a complex separable from other CP110 complexes; this CEP290-CP110 interaction is required for CP110-mediated suppression of primary cilia formation. CEP290 also interacts with Rab8a, and CEP290 depletion disrupts Rab8a localization to centrosomes/cilia.","method":"Co-immunoprecipitation, siRNA depletion, immunofluorescence","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP plus functional KD with defined phenotypes, highly cited","pmids":["18694559"],"is_preprint":false},{"year":2011,"finding":"Kif24, a kinesin-13 subfamily motor protein, specifically interacts with CP110 and CEP97 at the mother centriole, preferentially localizing to mother centrioles. Loss of Kif24 causes CP110 disappearance from mother centrioles in cycling cells and aberrant cilia assembly. Kif24 can bind and depolymerize microtubules in vitro and specifically remodels centriolar microtubules when ectopically expressed.","method":"Co-immunoprecipitation, siRNA depletion, in vitro microtubule depolymerization assay, immunofluorescence","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1-2 — in vitro microtubule assay plus Co-IP plus clean KD with defined phenotype","pmids":["21620453"],"is_preprint":false},{"year":2012,"finding":"CEP104 interacts with CP110 and CEP97 at the centriole and is required for ciliogenesis; CEP104 was identified as a microtubule plus-end tracking protein containing an SxIP motif.","method":"Proteome-wide SxIP motif screen, co-immunoprecipitation, siRNA depletion, fluorescence imaging","journal":"Current biology : CB","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP and KD with phenotype, single study","pmids":["22885064"],"is_preprint":false},{"year":2013,"finding":"MARK4 kinase is required for initiation of axoneme extension; upon MARK4 or ODF2 knockdown, the ciliary program arrests before complete removal of the CP110-CEP97 inhibitory complex from the mother centriole, placing MARK4 upstream of CP110-CEP97 removal in the ciliogenesis pathway.","method":"RNAi screen, siRNA depletion, ultrastructural analysis, immunofluorescence, co-immunoprecipitation","journal":"The Journal of cell biology","confidence":"Medium","confidence_rationale":"Tier 2 — epistasis via KD with defined phenotype and pathway placement, single lab","pmids":["23400999"],"is_preprint":false},{"year":2014,"finding":"TTBK2 phosphorylates CEP97 and CEP164 in vitro. Cep164 binding (not EB1) is essential for centriolar localization of TTBK2 and for CP110/CEP97 removal and ciliogenesis initiation.","method":"In vitro kinase assay, mutagenesis of TTBK2 binding motifs, siRNA rescue experiments, immunofluorescence","journal":"Genes to cells : devoted to molecular & cellular mechanisms","confidence":"High","confidence_rationale":"Tier 1-2 — in vitro phosphorylation assay plus mutagenesis rescue experiment establishing pathway","pmids":["25297623"],"is_preprint":false},{"year":2015,"finding":"In cytotoxic T lymphocytes (CTLs), CP110 and CEP97 remain associated with the mother centriole and neither axoneme nor transition zone ciliary structures form, demonstrating that CP110/CEP97 retention at the mother centriole prevents ciliogenesis during centrosome docking at the immunological synapse.","method":"High-resolution TEM tomography, immunofluorescence, siRNA depletion","journal":"Current biology : CB","confidence":"Medium","confidence_rationale":"Tier 2 — direct ultrastructural localization evidence with functional correlate","pmids":["26670998"],"is_preprint":false},{"year":2016,"finding":"Crystal structure of the CEP104 TOG domain was solved; biophysical characterization defined the direct interaction network between CEP104, CP110, CEP97, EB protein, and tubulin, establishing CEP97 as part of a microtubule-EB-CEP104-tubulin-CP110 network at the centriole.","method":"X-ray crystallography, biophysical binding assays (ITC, SEC), sequence analysis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — crystal structure plus multiple biophysical binding assays","pmids":["27402853"],"is_preprint":false},{"year":2016,"finding":"Asterless (Drosophila ortholog of Cep152) controls centriole length via the centriole protein Cep97; in Asl-free centrioles, Cep97 function in length control is revealed as a duplication-independent role.","method":"Drosophila genetics, immunofluorescence, loss-of-function analysis in specific cell populations","journal":"The Journal of cell biology","confidence":"Medium","confidence_rationale":"Tier 2 — genetic epistasis in Drosophila model organism, defined phenotypic readout","pmids":["27185836"],"is_preprint":false},{"year":2018,"finding":"MPP9 is recruited by KIF24 to the distal end of the mother centriole where it forms a ring-like structure and directly binds CEP97 to recruit the CP110-CEP97 complex. Upon TTBK2-mediated phosphorylation of MPP9 at the onset of ciliogenesis, MPP9 is degraded via the ubiquitin-proteasome system, facilitating removal of CP110 and CEP97 from the mother centriole distal end.","method":"Co-immunoprecipitation, super-resolution microscopy, siRNA depletion, phosphorylation assays, mouse kidney models","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP, super-resolution localization, in vivo mouse validation, mechanistic pathway established","pmids":["30375385"],"is_preprint":false},{"year":2018,"finding":"Truncated SALL1 (produced by TBS-causing mutations) interacts with CP110 and CEP97 as identified by proximity proteomics, leading to more frequent cilia formation in TBS-derived fibroblasts and altered SHH signaling.","method":"Proximity proteomics (BioID), CRISPR/Cas9 cell line generation, immunofluorescence, SHH signaling assays","journal":"American journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 3 — proximity proteomics identification plus functional phenotype, single study","pmids":["29395072"],"is_preprint":false},{"year":2020,"finding":"In Drosophila, Cep97 is essential for formation of full-length centrioles and for ciliogenesis, acting as part of a protective cap at the centriole distal end. The microtubule deacetylase Sirt2 was identified as a Cep97 interactor; both Sirt2 deletion and Atat1 (acetylase) deletion impair centriole integrity, indicating Cep97 cooperates with the microtubule acetylation machinery to maintain centriole stability.","method":"Drosophila genetics (null mutants), co-immunoprecipitation, immunofluorescence, electron microscopy","journal":"Current biology : CB","confidence":"High","confidence_rationale":"Tier 2 — null mutant analysis, co-IP of novel interactor, multiple tissue types examined, orthogonal methods","pmids":["32589908"],"is_preprint":false},{"year":2021,"finding":"Dyrk1a phosphorylates CEP97, which promotes recruitment of Polo-like kinase 1 (Plk1) to multiciliated cells. CEP97 and Dyrk1a coordinate with Plk1 to promote Separase function for centriole disengagement during multiciliogenesis; knockdown of CEP97 or Dyrk1a disrupts cilia formation and centriole disengagement, rescued by Separase overexpression.","method":"Xenopus embryo model, in vitro kinase assay, morpholino knockdown, overexpression rescue, immunofluorescence","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1-2 — in vitro kinase assay plus genetic rescue in vertebrate model organism with defined pathway","pmids":["34787650"],"is_preprint":false},{"year":2021,"finding":"LUBAC generates linear ubiquitin chains specifically on CP110, and a pre-mRNA splicing factor PRPF8 at the distal end of the mother centriole acts as receptor for these linear ubiquitin chains to facilitate CP110 (and consequently CEP97) removal at the initial stage of ciliogenesis.","method":"Co-immunoprecipitation, ubiquitination assay, siRNA depletion, immunofluorescence","journal":"The Journal of cell biology","confidence":"Medium","confidence_rationale":"Tier 2 — biochemical ubiquitination assay plus KD with defined pathway placement, single lab","pmids":["34813648"],"is_preprint":false},{"year":2022,"finding":"ENKD1 competes with CEP97 for binding to CP110; depletion of ENKD1 enhances the CP110-CEP97 interaction and detains CP110 at the mother centriole, inhibiting ciliogenesis. Simultaneous knockdown of ENKD1 and CP110 reverses the ciliogenesis defect, placing ENKD1 as a promoter of CP110 removal by competing with CEP97.","method":"Co-immunoprecipitation, super-resolution microscopy, siRNA/knockout mouse models, genetic epistasis (double knockdown)","journal":"EMBO reports","confidence":"High","confidence_rationale":"Tier 2 — competitive binding assay, super-resolution imaging, in vivo knockout, double-KD epistasis","pmids":["35301795"],"is_preprint":false},{"year":2022,"finding":"The seeding of a phosphorylated HSP27 ring around centrioles during aggresome assembly depends on CP110, CEP97, and CEP290; satellites and the CP110-CEP97-CEP290 complex are required for aggresome growth and for aggregation of mutant huntingtin.","method":"siRNA depletion, high-resolution quantitative imaging, immunofluorescence, proteasome inhibitor treatment","journal":"Nature cell biology","confidence":"Medium","confidence_rationale":"Tier 2 — clean KD with quantitative phenotypic readout, single lab","pmids":["35411088"],"is_preprint":false},{"year":2022,"finding":"WDR8 and Cep135 are required for both ciliary vesicle docking to the mother centriole and for removing the CP110-CEP97 inhibitory complex from the mother centriole distal end, establishing a role for centriolar proximal-end proteins upstream of CP110-CEP97 displacement in ciliogenesis.","method":"siRNA depletion, immunofluorescence, electron microscopy","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 — epistasis via KD with defined ultrastructural phenotype, single lab","pmids":["26675238"],"is_preprint":false},{"year":2022,"finding":"In Drosophila embryos, CP110 and Cep97 form a complex at the distal end of centrioles whose levels oscillate with the cell cycle, entrained by the Cdk-Cyclin oscillator. Changing CP110/Cep97 levels alters Plk4 oscillation and cartwheel growth at the proximal end, revealing unexpected crosstalk between distal-end capping factors and proximal-end cartwheel assembly.","method":"Drosophila embryo live imaging, genetic manipulation (overexpression/depletion), quantitative fluorescence analysis","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 — live imaging with quantitative analysis plus genetic perturbation, single lab","pmids":["35707992"],"is_preprint":false},{"year":2023,"finding":"PCM1 and centriolar satellites facilitate removal of CP110 and CEP97 from the distal mother centriole to initiate ciliogenesis; Pcm1-null RPE1 cells show reduced docking of the mother centriole to the ciliary vesicle and reduced removal of CP110/CEP97.","method":"Mouse knockout, siRNA depletion in human RPE1 cells, immunofluorescence, single-cell transcriptomics","journal":"eLife","confidence":"Medium","confidence_rationale":"Tier 2 — in vivo knockout and cell KD with mechanistic phenotype, single study","pmids":["36790165"],"is_preprint":false},{"year":2023,"finding":"In Drosophila, Cep97 is the central scaffolding unit required to recruit distal tip complex (DTC) components including Cep104 to the distal tip of centrioles; Cep97 and Cep104 cooperate during spermiogenesis to align spermatids and coordinate individualization.","method":"Drosophila proximity-labeling screen, null mutant analysis, immunofluorescence, electron microscopy","journal":"Current biology : CB","confidence":"Medium","confidence_rationale":"Tier 2 — proximity labeling plus null mutant analysis with defined phenotype","pmids":["37729913"],"is_preprint":false},{"year":2023,"finding":"miR-106b-5p in morphine-stimulated astrocyte-derived extracellular vesicles induces primary ciliogenesis by targeting CEP97 mRNA, reducing CEP97 levels; delivery of anti-miR-106b restored CEP97 expression, inhibited ciliogenesis, and prevented morphine tolerance in mice.","method":"miRNA target validation, EV delivery experiments, mouse morphine tolerance model, immunofluorescence, western blot","journal":"Molecular therapy","confidence":"Medium","confidence_rationale":"Tier 2 — miRNA target validation in vitro and in vivo with functional rescue, single lab","pmids":["37012704"],"is_preprint":false},{"year":2024,"finding":"During cerebellar granule cell differentiation, mother centrioles in maturing neurons recruit CEP97 (centriole cap complex) while cilia disassemble and cells permanently lose the ability to re-ciliate, indicating that CEP97 re-capping of docked mother centrioles prevents cilia regrowth in post-mitotic neurons.","method":"Single-cell transcriptomics, immunocytology, confocal imaging of mouse cerebellar tissue","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 — direct subcellular localization in tissue context tied to functional consequence (permanent cilia loss), single study","pmids":["39705308"],"is_preprint":false},{"year":2022,"finding":"CUL3/KCTD10 E3 ubiquitin ligase complex ubiquitinates CEP97, mediating its degradation and thereby influencing primary cilium formation.","method":"Ubiquitination assay, co-immunoprecipitation, siRNA depletion","journal":"BioEssays","confidence":"Low","confidence_rationale":"Tier 3 — review summarizing experimental findings from primary papers without independent replication data presented","pmids":["32484264"],"is_preprint":false},{"year":2025,"finding":"EHD1, through its membrane tubulation function, directly promotes CP110/CEP97 removal from the mother centriole cap during ciliogenesis, linking membrane vesicle dynamics to CP110-CEP97 displacement.","method":"3D electron microscopy (isotropic ultrastructure imaging), siRNA depletion, quantitative analysis","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 — advanced ultrastructural imaging plus functional KD, novel mechanistic finding not yet in peer-reviewed literature","pmids":["40894589"],"is_preprint":true}],"current_model":"CEP97 localizes to the distal end of centrioles where it recruits CP110 to form an inhibitory cap complex that suppresses ciliogenesis in cycling cells; this cap is maintained by MPP9 (which directly binds CEP97), KIF24, and the CUL3/KCTD10 ubiquitin ligase, and is removed at ciliogenesis onset through TTBK2-mediated phosphorylation of MPP9 (triggering its proteasomal degradation), LUBAC-mediated linear ubiquitination of CP110, competition by ENKD1 for CEP97-CP110 binding, and EHD1-driven membrane tubulation, while in Drosophila CEP97 additionally serves as the central scaffolding scaffold of the distal tip complex and cooperates with microtubule acetylation machinery to maintain centriole structural integrity, and in vertebrate multiciliated cells CEP97 is phosphorylated by Dyrk1a to recruit Plk1 and promote Separase-mediated centriole disengagement."},"narrative":{"teleology":[{"year":2007,"claim":"The foundational question of how primary cilia formation is suppressed in proliferating cells was answered by demonstrating that CEP97 recruits CP110 to centrosomes and that their co-depletion triggers ectopic ciliogenesis, establishing the CEP97–CP110 capping model.","evidence":"Protein complex purification, reciprocal co-IP, siRNA depletion, and dominant-negative expression in human cell lines","pmids":["17719545"],"confidence":"High","gaps":["Mechanism by which CEP97 itself is recruited to the centriole distal end was unknown","Whether removal of the cap is an active regulated process or passive consequence of cell-cycle exit was unresolved","No structural information on CEP97 or the CEP97–CP110 interface"]},{"year":2008,"claim":"The CP110 capping complex was shown to be modular: CEP290 forms a distinct subcomplex with CP110 required for cilia suppression and linking the cap to Rab8a vesicle trafficking, expanding the cap's functional reach beyond simple physical obstruction.","evidence":"Co-immunoprecipitation and siRNA depletion with ciliogenesis and Rab8a localization readouts","pmids":["18694559"],"confidence":"High","gaps":["Whether CEP97 and CEP290 bind CP110 simultaneously or mutually exclusively was not resolved","No direct binding assay between CEP97 and CEP290"]},{"year":2011,"claim":"KIF24, a depolymerizing kinesin-13, was identified as a mother-centriole-specific interactor of CP110 and CEP97 whose loss causes CP110 displacement and ectopic ciliogenesis, revealing that active microtubule remodeling maintains the cap.","evidence":"Co-IP, siRNA depletion, in vitro microtubule depolymerization assay in human cells","pmids":["21620453"],"confidence":"High","gaps":["Whether KIF24 directly contacts CEP97 or acts only through CP110 was not distinguished","Mechanism linking microtubule depolymerization to cap retention was unclear"]},{"year":2014,"claim":"TTBK2 was placed as the kinase that triggers ciliogenesis initiation by phosphorylating CEP97 and CEP164, with CEP164-dependent centriolar recruitment of TTBK2 required for CP110/CEP97 removal, establishing the first enzymatic trigger of cap displacement.","evidence":"In vitro kinase assay, TTBK2 binding-motif mutagenesis, siRNA rescue in human cells","pmids":["25297623"],"confidence":"High","gaps":["Direct phosphorylation sites on CEP97 were not mapped","Whether TTBK2 phosphorylation of CEP97 itself is sufficient for cap removal was untested"]},{"year":2016,"claim":"Biophysical characterization of the CEP104–CP110–CEP97 interaction network and crystal structure of the CEP104 TOG domain defined a microtubule-EB-CEP104-tubulin-CP110 bridge, placing CEP97 within a structurally resolved centriole distal-end interaction network.","evidence":"X-ray crystallography, ITC, and SEC binding assays","pmids":["27402853"],"confidence":"High","gaps":["No atomic-resolution structure of CEP97 itself or the CEP97–CP110 interface","Functional consequence of disrupting the CEP97–CEP104 interaction in cells was not tested"]},{"year":2018,"claim":"The recruitment hierarchy was resolved: MPP9 directly binds CEP97 and is required to recruit the CP110–CEP97 cap, while TTBK2-mediated phosphorylation of MPP9 triggers its proteasomal degradation and consequent cap loss, unifying the kinase signal with cap displacement.","evidence":"Reciprocal co-IP, super-resolution microscopy, phosphorylation assays, and mouse kidney validation","pmids":["30375385"],"confidence":"High","gaps":["Whether MPP9 phosphodegron is the sole route for cap removal or acts in parallel with other mechanisms","Structural basis of the MPP9–CEP97 interaction is unknown"]},{"year":2020,"claim":"Drosophila null mutants revealed that Cep97 is essential for full-length centriole formation and ciliogenesis in flies, and identified Sirt2 (a microtubule deacetylase) as a Cep97 interactor, linking the cap to centriole structural integrity via tubulin acetylation.","evidence":"Drosophila null mutant analysis, co-IP, electron microscopy across multiple tissue types","pmids":["32589908"],"confidence":"High","gaps":["Whether tubulin acetylation directly stabilizes CEP97 binding or acts indirectly through centriole architecture","Relevance of Sirt2–CEP97 interaction in vertebrates was untested"]},{"year":2021,"claim":"Two parallel cap-removal mechanisms were identified: LUBAC-mediated linear ubiquitination of CP110 (read by PRPF8) and competitive displacement of CEP97 by ENKD1, revealing that cap disassembly is a multi-pathway convergence rather than a single trigger.","evidence":"Ubiquitination assays, co-IP, super-resolution microscopy, knockout mouse models, double-KD epistasis","pmids":["34813648","35301795"],"confidence":"High","gaps":["How LUBAC and ENKD1 pathways are temporally coordinated during ciliogenesis","Whether ENKD1 competition and TTBK2/MPP9 degradation are independent or redundant"]},{"year":2021,"claim":"In multiciliated cells, CEP97 was shown to have a ciliogenesis-promoting function: Dyrk1a phosphorylates CEP97 to recruit Plk1, which activates Separase-mediated centriole disengagement, revealing a context-dependent reversal of CEP97's canonical cilia-inhibitory role.","evidence":"In vitro kinase assay, morpholino knockdown and Separase rescue in Xenopus multiciliated epithelium","pmids":["34787650"],"confidence":"High","gaps":["Phosphorylation sites on CEP97 targeted by Dyrk1a were not mapped","Whether this pathway operates in mammalian multiciliated cells is untested"]},{"year":2022,"claim":"Cell-cycle-entrained oscillation of CP110/Cep97 levels at the distal end was shown to influence Plk4 dynamics and cartwheel growth at the proximal end in Drosophila, establishing unexpected crosstalk between distal capping and proximal centriole duplication.","evidence":"Live imaging and genetic manipulation in Drosophila embryos with quantitative fluorescence analysis","pmids":["35707992"],"confidence":"Medium","gaps":["Molecular mechanism linking distal-end CP110/Cep97 levels to proximal Plk4 regulation is unknown","Whether this crosstalk occurs in vertebrate cells"]},{"year":2023,"claim":"Drosophila proximity labeling established Cep97 as the central scaffold of the distal tip complex, required for recruiting Cep104 and other DTC components, and showed Cep97–Cep104 cooperation is essential for spermatid alignment during spermiogenesis.","evidence":"Proximity-labeling screen, null mutant analysis, EM in Drosophila testes","pmids":["37729913"],"confidence":"Medium","gaps":["Whether CEP97's scaffolding role in the DTC is conserved in vertebrates","Binding interfaces between Cep97 and DTC components remain unmapped"]},{"year":2024,"claim":"In vivo evidence from mouse cerebellar granule neurons showed that re-recruitment of CEP97 to the mother centriole accompanies permanent cilia loss during neuronal differentiation, extending the capping model to irreversible fate decisions in post-mitotic cells.","evidence":"Single-cell transcriptomics, confocal imaging, and immunocytology of mouse cerebellar tissue","pmids":["39705308"],"confidence":"Medium","gaps":["Signal that triggers CEP97 re-capping in differentiating neurons is unknown","Whether preventing CEP97 re-capping restores ciliogenesis competence in these neurons"]},{"year":null,"claim":"No atomic-resolution structure of CEP97 or the CEP97–CP110 interface exists, and the precise phosphorylation sites on CEP97 targeted by TTBK2 and Dyrk1a have not been mapped; how the multiple parallel cap-removal pathways are coordinated temporally and whether CEP97's scaffolding role in the Drosophila DTC is conserved in vertebrates remain open questions.","evidence":"","pmids":[],"confidence":"High","gaps":["No structure of CEP97 or CEP97–CP110 complex","Phosphosite mapping on CEP97 is incomplete","Temporal coordination of parallel cap-removal pathways is unresolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,9,19]},{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[11,19]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[7,11]}],"localization":[{"term_id":"GO:0005815","term_label":"microtubule organizing center","supporting_discovery_ids":[0,2,6,9,11,17,21]},{"term_id":"GO:0005929","term_label":"cilium","supporting_discovery_ids":[0,11,19]}],"pathway":[{"term_id":"R-HSA-1852241","term_label":"Organelle biogenesis and maintenance","supporting_discovery_ids":[0,9,11,14,17,19]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[0,17]}],"complexes":["CP110–CEP97 capping complex","CP110–CEP97–CEP290 complex","Distal tip complex (Drosophila)"],"partners":["CP110","MPP9","KIF24","CEP104","CEP290","ENKD1","SIRT2","TTBK2"],"other_free_text":[]},"mechanistic_narrative":"CEP97 is a centriole distal-end capping protein that, together with CP110, forms an inhibitory cap complex suppressing inappropriate ciliogenesis in cycling cells. CEP97 recruits CP110 to centrosomes and is itself recruited via direct binding to MPP9, which is positioned by KIF24; removal of this cap at ciliogenesis onset is triggered by TTBK2-mediated phosphorylation and proteasomal degradation of MPP9, LUBAC-dependent linear ubiquitination of CP110, competitive displacement by ENKD1, and satellite-mediated displacement by PCM1 [PMID:17719545, PMID:30375385, PMID:34813648, PMID:35301795, PMID:36790165]. Beyond its ciliogenesis-gating role, CEP97 functions as the central scaffold of the Drosophila distal tip complex required for centriole length control and structural integrity in cooperation with the microtubule acetylation machinery, and in vertebrate multiciliated cells it is phosphorylated by Dyrk1a to recruit Plk1 and promote Separase-mediated centriole disengagement [PMID:32589908, PMID:37729913, PMID:34787650]. CEP97 re-capping of mother centrioles in post-mitotic cerebellar neurons enforces permanent loss of ciliation, and its levels can be regulated post-transcriptionally by miR-106b-5p to modulate ciliogenesis in astrocytes [PMID:39705308, PMID:37012704]."},"prefetch_data":{"uniprot":{"accession":"Q8IW35","full_name":"Centrosomal protein of 97 kDa","aliases":["Leucine-rich repeat and IQ domain-containing protein 2"],"length_aa":865,"mass_kda":97.0,"function":"Acts as a key negative regulator of ciliogenesis in collaboration with CCP110 by capping the mother centriole thereby preventing cilia formation (PubMed:17719545, PubMed:30375385). Required for recruitment of CCP110 to the centrosome (PubMed:17719545)","subcellular_location":"Cytoplasm, cytoskeleton, microtubule organizing center, centrosome; Cytoplasm, cytoskeleton, microtubule organizing center, centrosome, centriole","url":"https://www.uniprot.org/uniprotkb/Q8IW35/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CEP97","classification":"Not Classified","n_dependent_lines":340,"n_total_lines":1208,"dependency_fraction":0.2814569536423841},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CALM1","stoichiometry":0.2},{"gene":"CALM3","stoichiometry":0.2},{"gene":"TUBA1B","stoichiometry":0.2},{"gene":"TUBB4B","stoichiometry":0.2},{"gene":"VPS35","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/CEP97","total_profiled":1310},"omim":[{"mim_id":"621119","title":"ENKURIN DOMAIN-CONTAINING PROTEIN 1; ENKD1","url":"https://www.omim.org/entry/621119"},{"mim_id":"620791","title":"CENTROSOMAL PROTEIN, 76-KD; CEP76","url":"https://www.omim.org/entry/620791"},{"mim_id":"615864","title":"CENTROSOMAL PROTEIN, 97-KD; CEP97","url":"https://www.omim.org/entry/615864"},{"mim_id":"613747","title":"KINESIN FAMILY MEMBER 24; KIF24","url":"https://www.omim.org/entry/613747"},{"mim_id":"609544","title":"CENTRIOLAR COILED-COIL PROTEIN, 110-KD; CCP110","url":"https://www.omim.org/entry/609544"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Centriolar satellite","reliability":"Approved"},{"location":"Centrosome","reliability":"Approved"},{"location":"Cytosol","reliability":"Approved"},{"location":"Basal body","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/CEP97"},"hgnc":{"alias_symbol":["FLJ23047"],"prev_symbol":["LRRIQ2"]},"alphafold":{"accession":"Q8IW35","domains":[{"cath_id":"1.20.5","chopping":"576-636","consensus_level":"medium","plddt":86.3105,"start":576,"end":636}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8IW35","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8IW35-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8IW35-F1-predicted_aligned_error_v6.png","plddt_mean":58.19},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CEP97","jax_strain_url":"https://www.jax.org/strain/search?query=CEP97"},"sequence":{"accession":"Q8IW35","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8IW35.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8IW35/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8IW35"}},"corpus_meta":[{"pmid":"17719545","id":"PMC_17719545","title":"Cep97 and CP110 suppress a 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Loss of CEP97 or CP110 promotes primary cilia formation in growing cells, and enforced CP110 expression in quiescent cells suppresses ciliogenesis, establishing CEP97 and CP110 as collaborative inhibitors of a ciliogenesis program.\",\n      \"method\": \"Biochemical purification of CP110-associated complexes, siRNA knockdown, dominant-negative mutant expression, immunofluorescence\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — foundational study, multiple orthogonal methods (purification, KD, DN mutants), highly cited, replicated across subsequent studies\",\n      \"pmids\": [\"17719545\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Kif24, a kinesin-13 subfamily motor protein, specifically interacts with CP110 and CEP97 at centrosomes, preferentially localizing to mother centrioles. Kif24 can bind and depolymerize microtubules in vitro and specifically remodels centriolar microtubules, regulating cilia assembly. Loss of Kif24 leads to disappearance of CP110 from mother centrioles in cycling cells.\",\n      \"method\": \"Co-immunoprecipitation, in vitro microtubule depolymerization assay, siRNA knockdown, immunofluorescence, overexpression\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — in vitro enzymatic assay plus reciprocal Co-IP and KD with defined cellular phenotypes, highly cited\",\n      \"pmids\": [\"21620453\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"CEP104 interacts with CP110 and CEP97 at the centriole and is required for ciliogenesis, placing CEP104 in the CP110-CEP97 regulatory network at the microtubule plus-end.\",\n      \"method\": \"Proteome-wide SxIP motif screen, Co-immunoprecipitation, siRNA knockdown, live-cell imaging\",\n      \"journal\": \"Current Biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — Co-IP interaction plus functional knockdown, single study\",\n      \"pmids\": [\"22885064\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Upon MARK4 or ODF2 knockdown, the ciliary program arrests before complete removal of the CP110-CEP97 inhibitory complex from the mother centriole, placing MARK4 and ODF2 upstream of CP110-CEP97 removal in ciliogenesis.\",\n      \"method\": \"RNAi screen, siRNA knockdown, immunofluorescence, ultrastructural analysis\",\n      \"journal\": \"Journal of Cell Biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis via KD with defined phenotypic readout, single lab\",\n      \"pmids\": [\"23400999\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"TTBK2 phosphorylates CEP97 in vitro and has the potential to inhibit the interaction between Cep164 and its binding partner Dishevelled-3 in a kinase-activity-dependent manner; TTBK2 binding to Cep164 (not EB1) is essential for CP110/CEP97 removal and ciliogenesis.\",\n      \"method\": \"In vitro kinase assay, mutagenesis of SxIP and proline-rich motifs, siRNA rescue experiments, Co-immunoprecipitation\",\n      \"journal\": \"Genes to Cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 — in vitro kinase assay plus mutagenesis rescue, single lab\",\n      \"pmids\": [\"25297623\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"CEP104's TOG domain binds tubulin; CEP104 interacts biophysically with CP110 and CEP97 at the centriole distal end, as characterized by x-ray crystallography, biophysical binding assays, and sequence analysis.\",\n      \"method\": \"X-ray crystallography (TOG domain structure), biophysical binding assays (ITC/SPR), sequence analysis\",\n      \"journal\": \"Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure plus biophysical characterization of protein-protein interactions with multiple orthogonal methods\",\n      \"pmids\": [\"27402853\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"In Drosophila, Asterless (ortholog of CEP152) controls centriole length via the centriole protein CEP97; Asl-free centrioles show length defects that involve CEP97 function.\",\n      \"method\": \"Genetic analysis in Drosophila tissues with Asl-free centrioles, immunofluorescence, loss-of-function\",\n      \"journal\": \"Journal of Cell Biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis in Drosophila model organism, defined phenotypic readout, single lab\",\n      \"pmids\": [\"27185836\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"MPP9 is recruited by KIF24 to the distal end of the mother centriole where it forms a ring-like structure and directly binds CEP97 to recruit the CP110-CEP97 complex. Phosphorylation of MPP9 by TTBK2 at ciliogenesis onset targets MPP9 for ubiquitin-proteasome degradation, facilitating removal of CP110 and CEP97 from the mother centriole distal end.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown, super-resolution microscopy, in vivo mouse kidney analysis, ubiquitin-proteasome inhibition assays\",\n      \"journal\": \"Nature Communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP showing direct CEP97 binding, super-resolution localization, in vivo validation, multiple orthogonal methods\",\n      \"pmids\": [\"30375385\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"In Drosophila, CEP97 is essential for formation of full-length centrioles in multiple tissues. CEP97 interacts with the microtubule deacetylase Sirt2; deletion of Sirt2 or the acetylase Atat1 also affects centriole size, supporting a model where CEP97 forms a protective cap that acts with the microtubule acetylation machinery to maintain centriole stability required for ciliogenesis. In Drosophila, CEP97 is only transiently removed from basal bodies and its loss strongly impairs ciliogenesis.\",\n      \"method\": \"Drosophila genetic knockouts, Co-immunoprecipitation (CEP97-Sirt2 interaction), immunofluorescence, electron microscopy\",\n      \"journal\": \"Current Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — loss-of-function in Drosophila with multiple tissue phenotypes plus Co-IP identifying Sirt2 as interactor, multiple orthogonal methods\",\n      \"pmids\": [\"32589908\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"CEP97 interacts with Dyrk1a kinase; Dyrk1a phosphorylates CEP97, which promotes recruitment of Polo-like kinase 1 (Plk1) to centrioles to enhance centriole disengagement via Separase during multiciliogenesis in Xenopus MCCs. Knockdown of CEP97 or Dyrk1a disrupts centriole disengagement, rescued by Separase overexpression.\",\n      \"method\": \"Co-immunoprecipitation, in vitro kinase assay, Xenopus embryo knockdown/rescue experiments, immunofluorescence\",\n      \"journal\": \"Journal of Cell Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — in vitro kinase assay plus Co-IP plus genetic rescue in Xenopus vertebrate model, multiple orthogonal methods\",\n      \"pmids\": [\"34787650\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"The LUBAC E3 ligase complex promotes ciliogenesis by generating linear ubiquitin chains on CP110, required for CP110-CEP97 complex removal from the mother centriole at ciliogenesis onset. PRPF8 at the distal end of the mother centriole acts as receptor for linear ubiquitin chains to facilitate CP110 removal.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assays, siRNA knockdown, immunofluorescence\",\n      \"journal\": \"Journal of Cell Biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — biochemical ubiquitination assay plus KD with defined phenotype, single lab but multiple methods\",\n      \"pmids\": [\"34813648\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"CEP97 (with CP110 and CEP290) is required for aggresome assembly at the centrosome; the CP110-CEP97-CEP290 complex seeds a phospho-HSP27 ring around centrioles during aggresome formation, and is required for aggregation of mutant huntingtin.\",\n      \"method\": \"High-resolution quantitative microscopy, siRNA knockdown, immunofluorescence, huntingtin aggregation assay\",\n      \"journal\": \"Nature Cell Biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KD with defined cellular phenotype (aggresome formation) and quantitative imaging, single lab\",\n      \"pmids\": [\"35411088\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"ENKD1 competes with CEP97 for binding to CP110; depletion of ENKD1 enhances the CP110-CEP97 interaction and retains CP110 at the mother centriole. ENKD1 promotes CP110 removal from the mother centriole to initiate ciliogenesis.\",\n      \"method\": \"Co-immunoprecipitation, competitive binding assay, siRNA knockdown, Enkd1 knockout mice, super-resolution microscopy\",\n      \"journal\": \"EMBO Reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — competitive Co-IP demonstrating direct CEP97-CP110 interaction disrupted by ENKD1, in vivo knockout plus KD rescue, multiple orthogonal methods\",\n      \"pmids\": [\"35301795\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"In Drosophila embryos, CP110 and CEP97 form a complex at the distal end of centriole microtubules whose levels oscillate with new centriole MT growth, entrained by the Cdk-Cyclin oscillator. Altering CP110/CEP97 levels changes the Plk4 oscillation and cartwheel growth at the proximal end, revealing crosstalk between distal-end and proximal-end centriole assembly factors.\",\n      \"method\": \"Live imaging in Drosophila embryos, genetic manipulation of CP110/Cep97 levels, fluorescence quantification\",\n      \"journal\": \"Journal of Cell Science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — live imaging with quantitative analysis in Drosophila model, single lab\",\n      \"pmids\": [\"35707992\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"PCM1 and centriolar satellites facilitate the departure of CP110 and CEP97 from the mother centriole distal end to initiate ciliogenesis; Pcm1-null RPE1 cells show reduced removal of CP110 and CEP97 from the distal mother centriole and reduced mother centriole docking to the ciliary vesicle.\",\n      \"method\": \"PCM1 knockout mice, PCM1-null RPE1 cells (CRISPR), immunofluorescence, electron microscopy\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KO model with defined molecular phenotype (CP110/CEP97 retention), in vivo and cell-based validation\",\n      \"pmids\": [\"36790165\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"In Drosophila, Cep97 is the central scaffolding unit of the distal tip complex (DTC) required to recruit DTC components (including Cep104) to the distal tip of centrioles; Cep104 and Cep97 cooperate during spermiogenesis to align spermatids and coordinate individualization.\",\n      \"method\": \"Proximity-labeling screen, genetic null analysis (Cep104 null flies), immunofluorescence, interactome mapping\",\n      \"journal\": \"Current Biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — proximity labeling interactome plus null genetics with defined phenotypes, single lab\",\n      \"pmids\": [\"37729913\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"In maturing cerebellar granule cell neurons, mother centrioles recruit the CEP97 cap complex to prevent cilia regrowth and dysregulated SHH signaling, establishing CEP97 recruitment as a mechanism for permanent cilia loss in differentiated neurons.\",\n      \"method\": \"Single-cell transcriptomics, immunocytology, subcellular localization analysis in mouse tissue and cultured neurons\",\n      \"journal\": \"PNAS\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — direct localization tied to functional consequence (cilia suppression in neurons), correlative but with functional context\",\n      \"pmids\": [\"39705308\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"EHD1, through its membrane tubulation function, directly promotes CP110/CEP97 removal from the mother centriole cap during ciliogenesis, linking membrane trafficking at the distal appendage to CP110-CEP97 complex displacement.\",\n      \"method\": \"3D electron tomography (isotropic ultrastructure imaging), siRNA knockdown, immunofluorescence, quantitative ultrastructural analysis\",\n      \"journal\": \"bioRxiv (preprint)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 — ultrastructural imaging plus KD with defined molecular phenotype, preprint only\",\n      \"pmids\": [\"40894589\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Nuclear CEP97 co-immunoprecipitates with the tetraspanin CD9 in nuclear extracts of breast cancer cells, placing CEP97 in a nuclear protein complex whose disruption leads to polynucleation and multipolar mitoses.\",\n      \"method\": \"Co-immunoprecipitation from nuclear extracts, FRET analysis, immunofluorescence, siRNA knockdown\",\n      \"journal\": \"Molecular Cancer Research\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — single Co-IP in nuclear fraction, FRET excluded direct binding; no direct mechanistic follow-up on CEP97's role\",\n      \"pmids\": [\"25103498\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CEP97 is a conserved centriolar distal-end scaffolding protein that forms a cap complex with CP110 to suppress ciliogenesis in cycling cells; it recruits CP110 to centrosomes and is itself regulated by multiple upstream signals—including MPP9-mediated tethering (displaced via TTBK2 phosphorylation and proteasomal degradation), competition by ENKD1, Dyrk1a-mediated phosphorylation (promoting Plk1 recruitment and Separase-driven centriole disengagement in multiciliated cells), and LUBAC-mediated linear ubiquitylation of CP110—while additionally acting as the central scaffold of the distal tip complex to coordinate centriole length control through the microtubule acetylation machinery (Sirt2/Atat1) and to facilitate aggresome assembly at the centrosome.\"\n}\n```\n\n--- ROUND 2 (R2/R3, augmented corpus) ---\n\n```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2007,\n      \"finding\": \"CEP97 recruits CP110 to centrosomes; depletion of CEP97 causes CP110 disappearance from centrosomes, spindle defects, and polyploidy. Loss of CEP97 or CP110 promotes primary cilia formation in growing cells, while enforced expression of CP110 in quiescent cells suppresses ciliogenesis, establishing that CEP97 and CP110 collaborate to inhibit a ciliogenesis program.\",\n      \"method\": \"Protein complex purification, co-immunoprecipitation, siRNA depletion, dominant-negative expression, live imaging\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal co-IP, clean KD with defined cellular phenotypes, replicated across multiple assays in foundational paper with 385 citations\",\n      \"pmids\": [\"17719545\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"CP110 interacts with CEP290 in a complex separable from other CP110 complexes; this CEP290-CP110 interaction is required for CP110-mediated suppression of primary cilia formation. CEP290 also interacts with Rab8a, and CEP290 depletion disrupts Rab8a localization to centrosomes/cilia.\",\n      \"method\": \"Co-immunoprecipitation, siRNA depletion, immunofluorescence\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP plus functional KD with defined phenotypes, highly cited\",\n      \"pmids\": [\"18694559\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Kif24, a kinesin-13 subfamily motor protein, specifically interacts with CP110 and CEP97 at the mother centriole, preferentially localizing to mother centrioles. Loss of Kif24 causes CP110 disappearance from mother centrioles in cycling cells and aberrant cilia assembly. Kif24 can bind and depolymerize microtubules in vitro and specifically remodels centriolar microtubules when ectopically expressed.\",\n      \"method\": \"Co-immunoprecipitation, siRNA depletion, in vitro microtubule depolymerization assay, immunofluorescence\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro microtubule assay plus Co-IP plus clean KD with defined phenotype\",\n      \"pmids\": [\"21620453\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"CEP104 interacts with CP110 and CEP97 at the centriole and is required for ciliogenesis; CEP104 was identified as a microtubule plus-end tracking protein containing an SxIP motif.\",\n      \"method\": \"Proteome-wide SxIP motif screen, co-immunoprecipitation, siRNA depletion, fluorescence imaging\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP and KD with phenotype, single study\",\n      \"pmids\": [\"22885064\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"MARK4 kinase is required for initiation of axoneme extension; upon MARK4 or ODF2 knockdown, the ciliary program arrests before complete removal of the CP110-CEP97 inhibitory complex from the mother centriole, placing MARK4 upstream of CP110-CEP97 removal in the ciliogenesis pathway.\",\n      \"method\": \"RNAi screen, siRNA depletion, ultrastructural analysis, immunofluorescence, co-immunoprecipitation\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — epistasis via KD with defined phenotype and pathway placement, single lab\",\n      \"pmids\": [\"23400999\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"TTBK2 phosphorylates CEP97 and CEP164 in vitro. Cep164 binding (not EB1) is essential for centriolar localization of TTBK2 and for CP110/CEP97 removal and ciliogenesis initiation.\",\n      \"method\": \"In vitro kinase assay, mutagenesis of TTBK2 binding motifs, siRNA rescue experiments, immunofluorescence\",\n      \"journal\": \"Genes to cells : devoted to molecular & cellular mechanisms\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro phosphorylation assay plus mutagenesis rescue experiment establishing pathway\",\n      \"pmids\": [\"25297623\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"In cytotoxic T lymphocytes (CTLs), CP110 and CEP97 remain associated with the mother centriole and neither axoneme nor transition zone ciliary structures form, demonstrating that CP110/CEP97 retention at the mother centriole prevents ciliogenesis during centrosome docking at the immunological synapse.\",\n      \"method\": \"High-resolution TEM tomography, immunofluorescence, siRNA depletion\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct ultrastructural localization evidence with functional correlate\",\n      \"pmids\": [\"26670998\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Crystal structure of the CEP104 TOG domain was solved; biophysical characterization defined the direct interaction network between CEP104, CP110, CEP97, EB protein, and tubulin, establishing CEP97 as part of a microtubule-EB-CEP104-tubulin-CP110 network at the centriole.\",\n      \"method\": \"X-ray crystallography, biophysical binding assays (ITC, SEC), sequence analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure plus multiple biophysical binding assays\",\n      \"pmids\": [\"27402853\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Asterless (Drosophila ortholog of Cep152) controls centriole length via the centriole protein Cep97; in Asl-free centrioles, Cep97 function in length control is revealed as a duplication-independent role.\",\n      \"method\": \"Drosophila genetics, immunofluorescence, loss-of-function analysis in specific cell populations\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis in Drosophila model organism, defined phenotypic readout\",\n      \"pmids\": [\"27185836\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"MPP9 is recruited by KIF24 to the distal end of the mother centriole where it forms a ring-like structure and directly binds CEP97 to recruit the CP110-CEP97 complex. Upon TTBK2-mediated phosphorylation of MPP9 at the onset of ciliogenesis, MPP9 is degraded via the ubiquitin-proteasome system, facilitating removal of CP110 and CEP97 from the mother centriole distal end.\",\n      \"method\": \"Co-immunoprecipitation, super-resolution microscopy, siRNA depletion, phosphorylation assays, mouse kidney models\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP, super-resolution localization, in vivo mouse validation, mechanistic pathway established\",\n      \"pmids\": [\"30375385\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Truncated SALL1 (produced by TBS-causing mutations) interacts with CP110 and CEP97 as identified by proximity proteomics, leading to more frequent cilia formation in TBS-derived fibroblasts and altered SHH signaling.\",\n      \"method\": \"Proximity proteomics (BioID), CRISPR/Cas9 cell line generation, immunofluorescence, SHH signaling assays\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — proximity proteomics identification plus functional phenotype, single study\",\n      \"pmids\": [\"29395072\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"In Drosophila, Cep97 is essential for formation of full-length centrioles and for ciliogenesis, acting as part of a protective cap at the centriole distal end. The microtubule deacetylase Sirt2 was identified as a Cep97 interactor; both Sirt2 deletion and Atat1 (acetylase) deletion impair centriole integrity, indicating Cep97 cooperates with the microtubule acetylation machinery to maintain centriole stability.\",\n      \"method\": \"Drosophila genetics (null mutants), co-immunoprecipitation, immunofluorescence, electron microscopy\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — null mutant analysis, co-IP of novel interactor, multiple tissue types examined, orthogonal methods\",\n      \"pmids\": [\"32589908\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Dyrk1a phosphorylates CEP97, which promotes recruitment of Polo-like kinase 1 (Plk1) to multiciliated cells. CEP97 and Dyrk1a coordinate with Plk1 to promote Separase function for centriole disengagement during multiciliogenesis; knockdown of CEP97 or Dyrk1a disrupts cilia formation and centriole disengagement, rescued by Separase overexpression.\",\n      \"method\": \"Xenopus embryo model, in vitro kinase assay, morpholino knockdown, overexpression rescue, immunofluorescence\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro kinase assay plus genetic rescue in vertebrate model organism with defined pathway\",\n      \"pmids\": [\"34787650\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"LUBAC generates linear ubiquitin chains specifically on CP110, and a pre-mRNA splicing factor PRPF8 at the distal end of the mother centriole acts as receptor for these linear ubiquitin chains to facilitate CP110 (and consequently CEP97) removal at the initial stage of ciliogenesis.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, siRNA depletion, immunofluorescence\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — biochemical ubiquitination assay plus KD with defined pathway placement, single lab\",\n      \"pmids\": [\"34813648\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"ENKD1 competes with CEP97 for binding to CP110; depletion of ENKD1 enhances the CP110-CEP97 interaction and detains CP110 at the mother centriole, inhibiting ciliogenesis. Simultaneous knockdown of ENKD1 and CP110 reverses the ciliogenesis defect, placing ENKD1 as a promoter of CP110 removal by competing with CEP97.\",\n      \"method\": \"Co-immunoprecipitation, super-resolution microscopy, siRNA/knockout mouse models, genetic epistasis (double knockdown)\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — competitive binding assay, super-resolution imaging, in vivo knockout, double-KD epistasis\",\n      \"pmids\": [\"35301795\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"The seeding of a phosphorylated HSP27 ring around centrioles during aggresome assembly depends on CP110, CEP97, and CEP290; satellites and the CP110-CEP97-CEP290 complex are required for aggresome growth and for aggregation of mutant huntingtin.\",\n      \"method\": \"siRNA depletion, high-resolution quantitative imaging, immunofluorescence, proteasome inhibitor treatment\",\n      \"journal\": \"Nature cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean KD with quantitative phenotypic readout, single lab\",\n      \"pmids\": [\"35411088\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"WDR8 and Cep135 are required for both ciliary vesicle docking to the mother centriole and for removing the CP110-CEP97 inhibitory complex from the mother centriole distal end, establishing a role for centriolar proximal-end proteins upstream of CP110-CEP97 displacement in ciliogenesis.\",\n      \"method\": \"siRNA depletion, immunofluorescence, electron microscopy\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — epistasis via KD with defined ultrastructural phenotype, single lab\",\n      \"pmids\": [\"26675238\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"In Drosophila embryos, CP110 and Cep97 form a complex at the distal end of centrioles whose levels oscillate with the cell cycle, entrained by the Cdk-Cyclin oscillator. Changing CP110/Cep97 levels alters Plk4 oscillation and cartwheel growth at the proximal end, revealing unexpected crosstalk between distal-end capping factors and proximal-end cartwheel assembly.\",\n      \"method\": \"Drosophila embryo live imaging, genetic manipulation (overexpression/depletion), quantitative fluorescence analysis\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — live imaging with quantitative analysis plus genetic perturbation, single lab\",\n      \"pmids\": [\"35707992\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"PCM1 and centriolar satellites facilitate removal of CP110 and CEP97 from the distal mother centriole to initiate ciliogenesis; Pcm1-null RPE1 cells show reduced docking of the mother centriole to the ciliary vesicle and reduced removal of CP110/CEP97.\",\n      \"method\": \"Mouse knockout, siRNA depletion in human RPE1 cells, immunofluorescence, single-cell transcriptomics\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo knockout and cell KD with mechanistic phenotype, single study\",\n      \"pmids\": [\"36790165\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"In Drosophila, Cep97 is the central scaffolding unit required to recruit distal tip complex (DTC) components including Cep104 to the distal tip of centrioles; Cep97 and Cep104 cooperate during spermiogenesis to align spermatids and coordinate individualization.\",\n      \"method\": \"Drosophila proximity-labeling screen, null mutant analysis, immunofluorescence, electron microscopy\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — proximity labeling plus null mutant analysis with defined phenotype\",\n      \"pmids\": [\"37729913\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"miR-106b-5p in morphine-stimulated astrocyte-derived extracellular vesicles induces primary ciliogenesis by targeting CEP97 mRNA, reducing CEP97 levels; delivery of anti-miR-106b restored CEP97 expression, inhibited ciliogenesis, and prevented morphine tolerance in mice.\",\n      \"method\": \"miRNA target validation, EV delivery experiments, mouse morphine tolerance model, immunofluorescence, western blot\",\n      \"journal\": \"Molecular therapy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — miRNA target validation in vitro and in vivo with functional rescue, single lab\",\n      \"pmids\": [\"37012704\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"During cerebellar granule cell differentiation, mother centrioles in maturing neurons recruit CEP97 (centriole cap complex) while cilia disassemble and cells permanently lose the ability to re-ciliate, indicating that CEP97 re-capping of docked mother centrioles prevents cilia regrowth in post-mitotic neurons.\",\n      \"method\": \"Single-cell transcriptomics, immunocytology, confocal imaging of mouse cerebellar tissue\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct subcellular localization in tissue context tied to functional consequence (permanent cilia loss), single study\",\n      \"pmids\": [\"39705308\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"CUL3/KCTD10 E3 ubiquitin ligase complex ubiquitinates CEP97, mediating its degradation and thereby influencing primary cilium formation.\",\n      \"method\": \"Ubiquitination assay, co-immunoprecipitation, siRNA depletion\",\n      \"journal\": \"BioEssays\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — review summarizing experimental findings from primary papers without independent replication data presented\",\n      \"pmids\": [\"32484264\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"EHD1, through its membrane tubulation function, directly promotes CP110/CEP97 removal from the mother centriole cap during ciliogenesis, linking membrane vesicle dynamics to CP110-CEP97 displacement.\",\n      \"method\": \"3D electron microscopy (isotropic ultrastructure imaging), siRNA depletion, quantitative analysis\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — advanced ultrastructural imaging plus functional KD, novel mechanistic finding not yet in peer-reviewed literature\",\n      \"pmids\": [\"40894589\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"CEP97 localizes to the distal end of centrioles where it recruits CP110 to form an inhibitory cap complex that suppresses ciliogenesis in cycling cells; this cap is maintained by MPP9 (which directly binds CEP97), KIF24, and the CUL3/KCTD10 ubiquitin ligase, and is removed at ciliogenesis onset through TTBK2-mediated phosphorylation of MPP9 (triggering its proteasomal degradation), LUBAC-mediated linear ubiquitination of CP110, competition by ENKD1 for CEP97-CP110 binding, and EHD1-driven membrane tubulation, while in Drosophila CEP97 additionally serves as the central scaffolding scaffold of the distal tip complex and cooperates with microtubule acetylation machinery to maintain centriole structural integrity, and in vertebrate multiciliated cells CEP97 is phosphorylated by Dyrk1a to recruit Plk1 and promote Separase-mediated centriole disengagement.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"CEP97 is a conserved centriolar distal-end protein that functions as both a ciliogenesis gatekeeper and a central scaffold for centriole length and stability control. CEP97 recruits CP110 to centrosomes to form an inhibitory cap complex whose removal from the mother centriole is the committed step for cilia assembly; this removal is regulated by multiple upstream pathways including TTBK2-mediated phosphorylation and degradation of the tethering factor MPP9, competitive displacement by ENKD1, LUBAC-dependent linear ubiquitylation of CP110, PCM1/centriolar satellite-mediated transport, and MARK4/ODF2 signaling [PMID:17719545, PMID:30375385, PMID:35301795, PMID:34813648, PMID:36790165, PMID:23400999]. Beyond ciliogenesis suppression, CEP97 scaffolds the distal tip complex to recruit CEP104 and interacts with the microtubule deacetylase Sirt2, coordinating centriole microtubule acetylation and length control required for proper ciliogenesis and spermiogenesis in Drosophila [PMID:32589908, PMID:37729913]. CEP97 also participates in centriole disengagement during multiciliogenesis via Dyrk1a-mediated phosphorylation that recruits Plk1/Separase, and contributes to aggresome assembly at the centrosome together with CP110 and CEP290 [PMID:34787650, PMID:35411088].\",\n  \"teleology\": [\n    {\n      \"year\": 2007,\n      \"claim\": \"Identification of CEP97 as the factor that recruits CP110 to centrosomes and demonstration that the CEP97–CP110 complex suppresses ciliogenesis in cycling cells established the first molecular gatekeeping mechanism for primary cilia formation.\",\n      \"evidence\": \"Biochemical purification of CP110-associated complexes, siRNA knockdown, dominant-negative mutants, and immunofluorescence in human cells\",\n      \"pmids\": [\"17719545\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which CEP97 recruits CP110 was undefined\", \"How the cap complex is removed at ciliogenesis onset was unknown\", \"Whether the cilia-suppressive function is conserved across species was untested\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Discovery that the kinesin-13 motor Kif24 interacts with CP110–CEP97 at the mother centriole and remodels centriolar microtubules revealed the first enzymatic activity linked to the cap complex's regulation of cilia-competent microtubule ends.\",\n      \"evidence\": \"Co-immunoprecipitation, in vitro microtubule depolymerization assay, siRNA knockdown in human cells\",\n      \"pmids\": [\"21620453\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether Kif24 acts on CEP97 directly or only through CP110 was unclear\", \"Structural basis of the Kif24–CP110–CEP97 interaction was unresolved\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"CEP104 was placed in the CP110–CEP97 regulatory network at the centriole distal end and shown to be required for ciliogenesis, expanding the known composition of the distal cap.\",\n      \"evidence\": \"SxIP motif proteome screen, Co-IP, siRNA knockdown, live-cell imaging in human cells\",\n      \"pmids\": [\"22885064\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct binding interface between CEP104 and CEP97 was not mapped\", \"Functional hierarchy among CEP104, CP110, and CEP97 was unresolved\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"MARK4 and ODF2 were positioned upstream of CP110–CEP97 removal, demonstrating that kinase-dependent signaling cascades regulate the dismantling of the cap complex to license ciliogenesis.\",\n      \"evidence\": \"RNAi screen, siRNA knockdown with immunofluorescence and ultrastructural analysis in human cells\",\n      \"pmids\": [\"23400999\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct substrates of MARK4 at the mother centriole were not identified\", \"Whether MARK4 phosphorylates CEP97 directly was untested\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"TTBK2 was shown to phosphorylate CEP97 in vitro, linking a spinocerebellar ataxia-associated kinase directly to the CP110–CEP97 removal step; Cep164 binding, not EB1 binding, of TTBK2 was essential for this process.\",\n      \"evidence\": \"In vitro kinase assay, mutagenesis of SxIP/proline-rich motifs, siRNA rescue in human cells\",\n      \"pmids\": [\"25297623\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Phosphorylation sites on CEP97 were not mapped\", \"Functional consequences of CEP97 phosphorylation in cells were not demonstrated directly\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Crystal structure of CEP104's TOG domain and biophysical characterization of its interaction with CP110/CEP97 provided the first atomic-resolution view of a distal cap component, while Drosophila genetics linked CEP97 to centriole length control downstream of Asterless/CEP152.\",\n      \"evidence\": \"X-ray crystallography, ITC/SPR binding assays; Drosophila Asl-null genetic analysis with immunofluorescence\",\n      \"pmids\": [\"27402853\", \"27185836\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No structure of CEP97 itself or the CEP97–CP110 interface existed\", \"The mechanism by which Asl controls CEP97 levels was unknown\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"MPP9 was identified as the direct binding partner that tethers CEP97 to the mother centriole distal end; TTBK2 phosphorylation of MPP9 triggers its proteasomal degradation, providing the molecular mechanism for TTBK2-dependent CP110–CEP97 removal.\",\n      \"evidence\": \"Reciprocal Co-IP, super-resolution microscopy, ubiquitin-proteasome inhibition assays, in vivo mouse kidney analysis\",\n      \"pmids\": [\"30375385\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether TTBK2 phosphorylation of CEP97 itself has an additional role beyond MPP9 degradation was unclear\", \"The E3 ligase mediating MPP9 ubiquitylation was not identified\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Drosophila knockout studies revealed that CEP97 is essential for full-length centriole formation and that it cooperates with the microtubule acetylation machinery (Sirt2/Atat1) to maintain centriole stability, establishing CEP97 as a structural cap beyond its cilia-suppressive role.\",\n      \"evidence\": \"Drosophila genetic knockouts, Co-IP of CEP97–Sirt2, electron microscopy across multiple tissues\",\n      \"pmids\": [\"32589908\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the CEP97–Sirt2 interaction is conserved in mammals was untested\", \"How acetylation state mechanistically controls centriole length was not resolved\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Two new regulatory inputs to the CEP97–CP110 axis were defined: Dyrk1a phosphorylation of CEP97 promotes Plk1 recruitment and Separase-driven centriole disengagement during multiciliogenesis, while LUBAC-generated linear ubiquitin chains on CP110 promote CP110–CEP97 removal via the receptor PRPF8.\",\n      \"evidence\": \"In vitro kinase assay plus Xenopus embryo knockdown/rescue; ubiquitination assays and siRNA knockdown in human cells\",\n      \"pmids\": [\"34787650\", \"34813648\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Phosphorylation sites on CEP97 mediating Plk1 docking were not mapped\", \"How PRPF8 specifically recognizes linear ubiquitin on CP110 was unexplained\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"ENKD1 was shown to compete with CEP97 for CP110 binding, identifying a competition-based mechanism for cap disassembly; separately, the CP110–CEP97–CEP290 complex was found to seed aggresome formation, broadening CEP97 function beyond centriole/cilia biology.\",\n      \"evidence\": \"Competitive Co-IP, Enkd1 knockout mice, super-resolution microscopy; high-resolution quantitative microscopy of aggresome assembly with huntingtin aggregation assay\",\n      \"pmids\": [\"35301795\", \"35411088\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Binding interface between ENKD1 and CP110 relative to CEP97 was not structurally resolved\", \"Whether aggresome function of CEP97 is relevant in neurodegenerative disease in vivo was untested\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Live imaging in Drosophila embryos showed that CP110–CEP97 levels oscillate with the Cdk-Cyclin cell cycle oscillator and influence Plk4/cartwheel dynamics at the proximal end, revealing cross-talk between centriole distal and proximal assembly programs.\",\n      \"evidence\": \"Live imaging of fluorescently tagged proteins in Drosophila embryos with genetic manipulation of CP110/Cep97 dosage\",\n      \"pmids\": [\"35707992\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct molecular link between distal cap levels and Plk4 regulation was not identified\", \"Whether this oscillatory crosstalk occurs in mammalian centriole duplication was unknown\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"CEP97 was established as the central scaffold of the Drosophila distal tip complex required for recruiting CEP104 and other components, with functional importance for spermatid individualization; in parallel, PCM1/centriolar satellites were shown to facilitate CP110–CEP97 departure from the mother centriole during ciliogenesis.\",\n      \"evidence\": \"Proximity-labeling interactome plus Cep104-null fly genetics; Pcm1 knockout mice and CRISPR-null RPE1 cells with electron microscopy\",\n      \"pmids\": [\"37729913\", \"36790165\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which satellites physically remove the cap complex was unclear\", \"Whether the scaffolding hierarchy (CEP97-central) is conserved in vertebrates was not shown\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"CEP97 cap complex recruitment to the mother centriole was shown to mediate permanent cilia loss in maturing cerebellar granule neurons, linking the ciliogenesis-suppressive function to terminal neuronal differentiation and SHH signaling control.\",\n      \"evidence\": \"Single-cell transcriptomics, immunocytology, and subcellular localization analysis in mouse cerebellar tissue and cultured neurons\",\n      \"pmids\": [\"39705308\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Signal that triggers CEP97 recruitment during neuronal maturation was not identified\", \"Whether forced CEP97 removal restores cilia and SHH responsiveness was not tested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"No high-resolution structure of CEP97 or the CEP97–CP110 interface exists, the precise phosphorylation sites on CEP97 targeted by TTBK2 and Dyrk1a have not been mapped, and the extent to which the scaffolding and length-control functions discovered in Drosophila are conserved in mammals remains untested.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No atomic structure of CEP97 or CEP97–CP110 complex\", \"Phosphosite mapping on CEP97 by TTBK2 and Dyrk1a incomplete\", \"Mammalian conservation of distal tip complex scaffolding hierarchy unconfirmed\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [0, 8, 15]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 7, 15]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005815\", \"supporting_discovery_ids\": [0, 1, 7, 8, 13, 15, 16]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1852241\", \"supporting_discovery_ids\": [0, 8, 13, 15]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [0, 13]}\n    ],\n    \"complexes\": [\n      \"CP110–CEP97 cap complex\",\n      \"CP110–CEP97–CEP290 complex\",\n      \"Distal tip complex (DTC)\"\n    ],\n    \"partners\": [\n      \"CP110\",\n      \"MPP9\",\n      \"CEP104\",\n      \"KIF24\",\n      \"ENKD1\",\n      \"SIRT2\",\n      \"DYRK1A\",\n      \"CEP290\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```\n\n--- ROUND 2 (R2/R3, augmented corpus) ---\n\n```json\n{\n  \"mechanistic_narrative\": \"CEP97 is a centriole distal-end capping protein that, together with CP110, forms an inhibitory cap complex suppressing inappropriate ciliogenesis in cycling cells. CEP97 recruits CP110 to centrosomes and is itself recruited via direct binding to MPP9, which is positioned by KIF24; removal of this cap at ciliogenesis onset is triggered by TTBK2-mediated phosphorylation and proteasomal degradation of MPP9, LUBAC-dependent linear ubiquitination of CP110, competitive displacement by ENKD1, and satellite-mediated displacement by PCM1 [PMID:17719545, PMID:30375385, PMID:34813648, PMID:35301795, PMID:36790165]. Beyond its ciliogenesis-gating role, CEP97 functions as the central scaffold of the Drosophila distal tip complex required for centriole length control and structural integrity in cooperation with the microtubule acetylation machinery, and in vertebrate multiciliated cells it is phosphorylated by Dyrk1a to recruit Plk1 and promote Separase-mediated centriole disengagement [PMID:32589908, PMID:37729913, PMID:34787650]. CEP97 re-capping of mother centrioles in post-mitotic cerebellar neurons enforces permanent loss of ciliation, and its levels can be regulated post-transcriptionally by miR-106b-5p to modulate ciliogenesis in astrocytes [PMID:39705308, PMID:37012704].\",\n  \"teleology\": [\n    {\n      \"year\": 2007,\n      \"claim\": \"The foundational question of how primary cilia formation is suppressed in proliferating cells was answered by demonstrating that CEP97 recruits CP110 to centrosomes and that their co-depletion triggers ectopic ciliogenesis, establishing the CEP97–CP110 capping model.\",\n      \"evidence\": \"Protein complex purification, reciprocal co-IP, siRNA depletion, and dominant-negative expression in human cell lines\",\n      \"pmids\": [\"17719545\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Mechanism by which CEP97 itself is recruited to the centriole distal end was unknown\",\n        \"Whether removal of the cap is an active regulated process or passive consequence of cell-cycle exit was unresolved\",\n        \"No structural information on CEP97 or the CEP97–CP110 interface\"\n      ]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"The CP110 capping complex was shown to be modular: CEP290 forms a distinct subcomplex with CP110 required for cilia suppression and linking the cap to Rab8a vesicle trafficking, expanding the cap's functional reach beyond simple physical obstruction.\",\n      \"evidence\": \"Co-immunoprecipitation and siRNA depletion with ciliogenesis and Rab8a localization readouts\",\n      \"pmids\": [\"18694559\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether CEP97 and CEP290 bind CP110 simultaneously or mutually exclusively was not resolved\",\n        \"No direct binding assay between CEP97 and CEP290\"\n      ]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"KIF24, a depolymerizing kinesin-13, was identified as a mother-centriole-specific interactor of CP110 and CEP97 whose loss causes CP110 displacement and ectopic ciliogenesis, revealing that active microtubule remodeling maintains the cap.\",\n      \"evidence\": \"Co-IP, siRNA depletion, in vitro microtubule depolymerization assay in human cells\",\n      \"pmids\": [\"21620453\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether KIF24 directly contacts CEP97 or acts only through CP110 was not distinguished\",\n        \"Mechanism linking microtubule depolymerization to cap retention was unclear\"\n      ]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"TTBK2 was placed as the kinase that triggers ciliogenesis initiation by phosphorylating CEP97 and CEP164, with CEP164-dependent centriolar recruitment of TTBK2 required for CP110/CEP97 removal, establishing the first enzymatic trigger of cap displacement.\",\n      \"evidence\": \"In vitro kinase assay, TTBK2 binding-motif mutagenesis, siRNA rescue in human cells\",\n      \"pmids\": [\"25297623\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Direct phosphorylation sites on CEP97 were not mapped\",\n        \"Whether TTBK2 phosphorylation of CEP97 itself is sufficient for cap removal was untested\"\n      ]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Biophysical characterization of the CEP104–CP110–CEP97 interaction network and crystal structure of the CEP104 TOG domain defined a microtubule-EB-CEP104-tubulin-CP110 bridge, placing CEP97 within a structurally resolved centriole distal-end interaction network.\",\n      \"evidence\": \"X-ray crystallography, ITC, and SEC binding assays\",\n      \"pmids\": [\"27402853\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"No atomic-resolution structure of CEP97 itself or the CEP97–CP110 interface\",\n        \"Functional consequence of disrupting the CEP97–CEP104 interaction in cells was not tested\"\n      ]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"The recruitment hierarchy was resolved: MPP9 directly binds CEP97 and is required to recruit the CP110–CEP97 cap, while TTBK2-mediated phosphorylation of MPP9 triggers its proteasomal degradation and consequent cap loss, unifying the kinase signal with cap displacement.\",\n      \"evidence\": \"Reciprocal co-IP, super-resolution microscopy, phosphorylation assays, and mouse kidney validation\",\n      \"pmids\": [\"30375385\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether MPP9 phosphodegron is the sole route for cap removal or acts in parallel with other mechanisms\",\n        \"Structural basis of the MPP9–CEP97 interaction is unknown\"\n      ]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Drosophila null mutants revealed that Cep97 is essential for full-length centriole formation and ciliogenesis in flies, and identified Sirt2 (a microtubule deacetylase) as a Cep97 interactor, linking the cap to centriole structural integrity via tubulin acetylation.\",\n      \"evidence\": \"Drosophila null mutant analysis, co-IP, electron microscopy across multiple tissue types\",\n      \"pmids\": [\"32589908\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether tubulin acetylation directly stabilizes CEP97 binding or acts indirectly through centriole architecture\",\n        \"Relevance of Sirt2–CEP97 interaction in vertebrates was untested\"\n      ]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Two parallel cap-removal mechanisms were identified: LUBAC-mediated linear ubiquitination of CP110 (read by PRPF8) and competitive displacement of CEP97 by ENKD1, revealing that cap disassembly is a multi-pathway convergence rather than a single trigger.\",\n      \"evidence\": \"Ubiquitination assays, co-IP, super-resolution microscopy, knockout mouse models, double-KD epistasis\",\n      \"pmids\": [\"34813648\", \"35301795\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"How LUBAC and ENKD1 pathways are temporally coordinated during ciliogenesis\",\n        \"Whether ENKD1 competition and TTBK2/MPP9 degradation are independent or redundant\"\n      ]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"In multiciliated cells, CEP97 was shown to have a ciliogenesis-promoting function: Dyrk1a phosphorylates CEP97 to recruit Plk1, which activates Separase-mediated centriole disengagement, revealing a context-dependent reversal of CEP97's canonical cilia-inhibitory role.\",\n      \"evidence\": \"In vitro kinase assay, morpholino knockdown and Separase rescue in Xenopus multiciliated epithelium\",\n      \"pmids\": [\"34787650\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Phosphorylation sites on CEP97 targeted by Dyrk1a were not mapped\",\n        \"Whether this pathway operates in mammalian multiciliated cells is untested\"\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Cell-cycle-entrained oscillation of CP110/Cep97 levels at the distal end was shown to influence Plk4 dynamics and cartwheel growth at the proximal end in Drosophila, establishing unexpected crosstalk between distal capping and proximal centriole duplication.\",\n      \"evidence\": \"Live imaging and genetic manipulation in Drosophila embryos with quantitative fluorescence analysis\",\n      \"pmids\": [\"35707992\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Molecular mechanism linking distal-end CP110/Cep97 levels to proximal Plk4 regulation is unknown\",\n        \"Whether this crosstalk occurs in vertebrate cells\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Drosophila proximity labeling established Cep97 as the central scaffold of the distal tip complex, required for recruiting Cep104 and other DTC components, and showed Cep97–Cep104 cooperation is essential for spermatid alignment during spermiogenesis.\",\n      \"evidence\": \"Proximity-labeling screen, null mutant analysis, EM in Drosophila testes\",\n      \"pmids\": [\"37729913\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether CEP97's scaffolding role in the DTC is conserved in vertebrates\",\n        \"Binding interfaces between Cep97 and DTC components remain unmapped\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"In vivo evidence from mouse cerebellar granule neurons showed that re-recruitment of CEP97 to the mother centriole accompanies permanent cilia loss during neuronal differentiation, extending the capping model to irreversible fate decisions in post-mitotic cells.\",\n      \"evidence\": \"Single-cell transcriptomics, confocal imaging, and immunocytology of mouse cerebellar tissue\",\n      \"pmids\": [\"39705308\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Signal that triggers CEP97 re-capping in differentiating neurons is unknown\",\n        \"Whether preventing CEP97 re-capping restores ciliogenesis competence in these neurons\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"No atomic-resolution structure of CEP97 or the CEP97–CP110 interface exists, and the precise phosphorylation sites on CEP97 targeted by TTBK2 and Dyrk1a have not been mapped; how the multiple parallel cap-removal pathways are coordinated temporally and whether CEP97's scaffolding role in the Drosophila DTC is conserved in vertebrates remain open questions.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"No structure of CEP97 or CEP97–CP110 complex\",\n        \"Phosphosite mapping on CEP97 is incomplete\",\n        \"Temporal coordination of parallel cap-removal pathways is unresolved\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 9, 19]},\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [11, 19]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [7, 11]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005815\", \"supporting_discovery_ids\": [0, 2, 6, 9, 11, 17, 21]},\n      {\"term_id\": \"GO:0005929\", \"supporting_discovery_ids\": [0, 11, 19]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1852241\", \"supporting_discovery_ids\": [0, 9, 11, 14, 17, 19]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [0, 17]}\n    ],\n    \"complexes\": [\n      \"CP110–CEP97 capping complex\",\n      \"CP110–CEP97–CEP290 complex\",\n      \"Distal tip complex (Drosophila)\"\n    ],\n    \"partners\": [\n      \"CP110\",\n      \"MPP9\",\n      \"KIF24\",\n      \"CEP104\",\n      \"CEP290\",\n      \"ENKD1\",\n      \"SIRT2\",\n      \"TTBK2\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}