{"gene":"CENPA","run_date":"2026-04-28T17:28:52","timeline":{"discoveries":[{"year":2006,"finding":"CENP-A nucleosomes directly recruit a proximal CENP-A nucleosome associated complex (NAC) comprising CENP-M, CENP-N, CENP-T, CENP-U(50), CENP-C, and CENP-H; assembly of this NAC is dependent on CENP-M, CENP-N, and CENP-T; seven additional CENP-A nucleosome distal (CAD) components (CENP-K, -L, -O, -P, -Q, -R, -S) assemble on the NAC; disruption of the complex causes chromosome alignment and segregation errors.","method":"Affinity purification/mass spectrometry, Co-immunoprecipitation, siRNA knockdown with mitotic phenotype readout","journal":"Nature cell biology","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP/MS with functional KD validation, foundational study replicated across labs","pmids":["16622419"],"is_preprint":false},{"year":2000,"finding":"CENP-A (Cenpa) is essential for kinetochore targeting of CENP-C; Cenpa null mouse embryos fail beyond E6.5 and display micronuclei, nuclear bridging, chromatin fragmentation, and dispersal of Cenpb and Cenpc from centromeres, establishing CENP-A as an upstream organizer of centromeric chromatin.","method":"Gene targeting (knockout mouse), immunofluorescence of null embryos","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — clean genetic KO with defined molecular phenotype (loss of CENP-C centromere targeting), replicated in vivo","pmids":["10655499"],"is_preprint":false},{"year":2011,"finding":"Crystal structure of HJURP bound to a CENP-A–H4 heterodimer shows that HJURP's C-terminal β-sheet domain caps the DNA-binding surface of the CENP-A–H4 heterodimer, preventing spontaneous DNA association; a novel surface in CENP-A distinguishes it from H3 for HJURP recognition.","method":"X-ray crystallography, in vitro binding assays, mutagenesis","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 1 — crystal structure with mutagenesis identifying CENP-A-specific HJURP binding determinants","pmids":["21478274"],"is_preprint":false},{"year":2011,"finding":"CENP-C recruits the Mis18 complex protein M18BP1 to centromeres through direct binding via conserved domains in CENP-C; depletion of CENP-C prevents M18BP1 targeting to metaphase centromeres and inhibits CENP-A chromatin assembly.","method":"Protein depletion (siRNA), in vitro direct binding assay (pulldown), immunofluorescence","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 — direct binding assay + loss-of-function with specific CENP-A assembly phenotype","pmids":["21911481"],"is_preprint":false},{"year":2014,"finding":"Polo-like kinase 1 (Plk1) is required to initiate CENP-A deposition by promoting localization of the Mis18 complex to centromeres; CDK activity inhibits Mis18 complex assembly; these two signals form a two-step licensing mechanism controlling cell-cycle-restricted CENP-A deposition.","method":"Chemical inhibition and kinase-dead mutants of Plk1/CDK, immunofluorescence, CENP-A deposition assays in human cells","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal functional perturbations with defined molecular and cellular phenotypes","pmids":["25036634"],"is_preprint":false},{"year":2014,"finding":"CENP-A is phosphorylated at Ser68 by Cdk1 during early mitosis; this phosphorylation eliminates CENP-A binding to HJURP, preventing premature centromeric loading; dephosphorylation by PP1α at mitotic exit permits HJURP-mediated deposition at centromeres.","method":"In vitro kinase assay, phospho-specific antibodies, co-immunoprecipitation, CENP-A loading assays in human cells","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 1-2 — in vitro kinase assay combined with mutant CENP-A functional studies and Co-IP","pmids":["25556658"],"is_preprint":false},{"year":2012,"finding":"CENP-A nucleosomes cycle between octameric and tetrameric forms across the human cell cycle: they exist as tetramers after replication and convert to octamers before replication; these structural transitions are accompanied by reversible chaperone binding and chromatin fiber folding changes and modifications within CENP-A and H4.","method":"Native chromatin fractionation, cell-cycle synchronization, mass spectrometry, electron microscopy, FRAP","journal":"Cell","confidence":"Medium","confidence_rationale":"Tier 2 — multiple biophysical/biochemical methods from single lab; structural conclusions remain debated","pmids":["22817894"],"is_preprint":false},{"year":2009,"finding":"CENP-A is rapidly recruited to DNA double-strand breaks along with CENP-N, CENP-T, and CENP-U; the centromere-targeting domain (CATD) of CENP-A is both necessary and sufficient for DSB recruitment; CENP-A accumulation at breaks is enhanced by active NHEJ but is independent of DNA-PKcs, Ligase IV, and H2AX.","method":"Multiphoton laser-induced DSBs, I-SceI endonuclease-induced breaks, CENP-A domain mutants, immunofluorescence in human and mouse cells","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 — domain mapping with loss-of-function and gain-of-function in live cells, but functional significance at DSBs remains uncertain","pmids":["19717431"],"is_preprint":false},{"year":2001,"finding":"CENP-A is phosphorylated at a serine residue (analogous to H3 Ser10) during mitosis, occurring after pericentric H3 phosphorylation; phosphorylation begins in prophase, peaks in prometaphase, and is lost by telophase, defining CENP-A phosphorylation as a distinct kinetochore-specific mitotic event.","method":"Phospho-specific peptide antibodies, ELISA, western blot, immunofluorescence across cell cycle stages","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 — antibody characterization with quantitative immunofluorescence across cell cycle; functional role of this modification not fully established in this paper","pmids":["11171370"],"is_preprint":false},{"year":2014,"finding":"Overexpressed CENP-A mislocalizes to non-centromeric chromatin through a heterotypic tetramer containing CenH3-H4 with H3.3-H4, deposited by the H3.3 chaperone DAXX rather than the dedicated chaperone HJURP; ectopic CENP-A occludes CTCF binding and both effects depend on DAXX.","method":"Native ChIP-seq, co-immunoprecipitation, siRNA depletion of chaperones in human cells","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP plus ChIP-seq plus loss-of-function establishing DAXX as chaperone for ectopic CENP-A","pmids":["24530302"],"is_preprint":false},{"year":2018,"finding":"HJURP transiently associates with centromeres during S phase and binds to pre-existing CENP-A; HJURP co-purifies with the MCM2-7 helicase complex and simultaneously binds CENP-A with MCM2, establishing HJURP as an S-phase retention factor required for inheritance of centromeric CENP-A nucleosomes through DNA replication.","method":"BioID proximity labeling, co-immunoprecipitation, siRNA depletion, in vitro binding assays","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 2 — BioID plus direct binding assay plus KD with defined inheritance phenotype; multiple orthogonal methods","pmids":["30293838"],"is_preprint":false},{"year":2017,"finding":"CENP-A undergoes α-amino trimethylation by the enzyme NRMT in vivo; loss of this modification reduces CENP-T and CENP-I levels at the centromere and causes lagging chromosomes and spindle pole defects.","method":"Mass spectrometry identification of modification, in vivo functional assays with CENP-A N-terminal mutants, immunofluorescence","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 — modification identified by MS, functional phenotype established by mutant expression, single lab","pmids":["28266506"],"is_preprint":false},{"year":2022,"finding":"Cryo-EM structures of the human inner kinetochore CCAN complex bound to a CENP-A nucleosome show CCAN makes edge-on contacts with CENP-A nucleosomes; linker DNA threading through the CENP-LN channel and partial wrapping by CENP-TWSX provide topological entrapment of DNA as a mechanism to withstand spindle forces.","method":"Cryo-electron microscopy structure determination of reconstituted CCAN–CENP-A nucleosome complex","journal":"Science (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 1 — near-atomic cryo-EM structure of reconstituted complex with mechanistic interpretation","pmids":["35420891"],"is_preprint":false},{"year":2011,"finding":"The CCAN has two distinct roles: (1) recruiting CENP-A to establish the kinetochore (via HJURP, CENP-C, CENP-I, or CENP-C C-terminus) and (2) serving as a structural core to directly recruit kinetochore proteins (Ndc80/CPC) independently of CENP-A (via CENP-T or CENP-C N-terminus).","method":"Chromosome engineering with conditional centromere removal, ectopic targeting of individual CCAN proteins, immunofluorescence in DT40 cells","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 — genetic epistasis via chromosome engineering plus ectopic targeting system; functional dissection by multiple constructs","pmids":["23277427"],"is_preprint":false},{"year":2010,"finding":"Forced reduction of CENP-A triggers premature cellular senescence in human primary fibroblasts in a p53-dependent manner; in p53-deficient cells, CENP-A depletion instead causes aberrant mitosis with chromosome missegregation, revealing a p53-dependent safeguard against centromere defects.","method":"shRNA knockdown of CENP-A in human fibroblasts, β-galactosidase senescence assay, chromosome segregation analysis","journal":"Molecular and cellular biology","confidence":"Medium","confidence_rationale":"Tier 2 — clean KD with defined cellular and molecular phenotype in isogenic p53+/- backgrounds","pmids":["20160010"],"is_preprint":false},{"year":2002,"finding":"PARP-2 co-immunoprecipitates with CENP-A and CENP-B at mammalian centromeres in a cell-cycle-dependent manner (enriched prometaphase/metaphase, absent by telophase); PARP-2 centromere binding is sequence-independent and occurs only at active centromeres.","method":"Co-immunoprecipitation, immunofluorescence on pseudodicentric and neocentromere-containing chromosomes","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 3 — single Co-IP identifying interaction; cell-cycle localization established but mechanistic consequence limited","pmids":["12217960"],"is_preprint":false},{"year":2015,"finding":"CENP-B forms a stable complex with the CENP-A nucleosome specifically when the CENP-B box sequence is located at the proximal edge of the nucleosome; the CENP-B DNA-binding domain interacts directly with the CENP-A–H4 complex (but not H3.1–H4); CENP-B binding near CENP-A nucleosomes stabilizes CENP-A on alphoid DNA in human cells.","method":"In vitro reconstitution, pulldown assays, in vivo CENP-A stability assay","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstitution with position-specific binding assays and in vivo functional validation","pmids":["25916850"],"is_preprint":false},{"year":2019,"finding":"CENP-C binding to the CENP-A nucleosome causes two key conformational changes: further exacerbation of loose DNA wrapping via destabilization of the H2A C-terminal tail, and rigidification of the H4 N-terminal tail in a conformation favoring H4K20 monomethylation; CENP-C binds exclusively to CENP-A nucleosomes via an extended hydrophobic interface involving CENP-A V532/V533.","method":"Cryo-EM, in vitro binding assays (EMSA, MST), mutagenesis","journal":"EMBO reports","confidence":"High","confidence_rationale":"Tier 1 — structural and biophysical methods with mutagenesis identifying specific binding contacts","pmids":["31475439"],"is_preprint":false},{"year":2019,"finding":"Cryo-EM structure of native-like human CENP-A nucleosome on α-satellite DNA at 2.6 Å resolution reveals the atomic architecture of the CENP-A octameric nucleosome; scFv binds the H2A-H2B acidic patch without perturbing nucleosome structure.","method":"Cryo-EM structure determination with scFv stabilization","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 — near-atomic resolution cryo-EM structure of native-sequence CENP-A nucleosome","pmids":["31127102"],"is_preprint":false},{"year":2016,"finding":"The flexible DNA ends of CENP-A nucleosomes (conferred by the short αN helix) prevent histone H1 binding; substituting the CENP-A αN helix with the H3 αN helix rigidifies DNA ends, enables H1 binding, causes delocalization of kinetochore proteins, and produces mitotic and cytokinesis defects in vivo.","method":"Cryo-EM, biochemical H1 binding assays, in vivo H3-CENP-A chimera expression with kinetochore localization and mitotic phenotype readout","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1-2 — cryo-EM structure combined with biochemical and in vivo functional analysis of domain swap mutants","pmids":["27499292"],"is_preprint":false},{"year":2017,"finding":"Two HJURP repeats bind concomitantly to the 4:2:2 Mis18α:Mis18β:M18BP1 complex without dissociating it; Mis18α N-terminal tails blockade two identical HJURP-repeat binding sites near the Mis18αβ C-terminal helices; mutation of these sites separates Mis18 from HJURP centromere recruitment.","method":"Photo-cross-linking, in vitro binding assays, point mutagenesis, immunofluorescence","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1-2 — photo-cross-linking to identify binding interface plus mutagenesis confirming functional relevance","pmids":["31492860"],"is_preprint":false},{"year":2017,"finding":"CDK1 phosphorylation at two conserved sites in M18BP1's N-terminal 140 residues destabilizes its binding to the Mis18α:Mis18β hexamer (4:2 stoichiometry), limiting Mis18 complex formation and centromere recruitment of HJURP/CENP-A loading to G1 phase.","method":"Biochemical reconstitution, viral 2A co-expression system, phosphomutant analysis, centromere localization assays","journal":"eLife","confidence":"High","confidence_rationale":"Tier 1 — biochemical reconstitution of complex stoichiometry with CDK1 phosphomutant functional validation","pmids":["28059702"],"is_preprint":false},{"year":2018,"finding":"Aurora A phosphorylates CENP-A at serine 7 at inner centromeres; non-phosphorylatable CENP-A S7A weakens sister chromatid cohesion only under spindle tension, and Aurora A is recruited to centromeres in a Bub1-dependent manner; this modification protects bioriented chromosomes against cohesion fatigue.","method":"Phospho-specific antibody, non-phosphorylatable CENP-A mutant expression, Aurora A inhibition/depletion, cohesion fatigue assay","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 — phosphomutant with tension-specific phenotype and kinase recruitment pathway established; single lab","pmids":["29760389"],"is_preprint":false},{"year":2016,"finding":"KAT7/HBO1 acetyltransferase interacts with the CENP-A assembly factor M18BP1; KAT7 knockout reduces centromeric CENP-A assembly; tethering KAT7 to ectopic alphoid DNA removes H3K9me3 and stimulates CENP-A assembly by antagonizing Suv39h1-mediated heterochromatin invasion.","method":"Co-immunoprecipitation, KO cell line, tethering assay, chromatin immunoprecipitation","journal":"Developmental cell","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP plus KO with CENP-A assembly phenotype plus tethering assay; single lab","pmids":["27270040"],"is_preprint":false},{"year":2016,"finding":"CENP-A K124 is acetylated by p300 at G1/S and switches to monomethylation during early and mid-S phase; acetylation of K124 diminishes CENP-C binding and promotes DNA sliding of nucleosomes; K124 mutation alters CENP-C levels and centromeric replication timing.","method":"Mass spectrometry, computational modeling, in vivo K124 acetyl/unacetylatable mutant expression, immunofluorescence","journal":"Epigenetics & chromatin","confidence":"Medium","confidence_rationale":"Tier 2-3 — MS identification with in vivo mutant phenotypes; computational modeling supports but does not fully validate mechanism","pmids":["28396698"],"is_preprint":false},{"year":2016,"finding":"CENP-A ubiquitylation (K124, by CUL4A-RBX1-COPS8) is inherited through cell divisions; pre-existing ubiquitylated CENP-A is necessary for recruitment of newly synthesized CENP-A; inheritance of ubiquitylation requires CENP-A dimerization, as shown by dimerization mutants.","method":"In vivo and in vitro dimerization mutant analysis, cell cycle tracking of ubiquitylated CENP-A, immunofluorescence","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 — in vitro and in vivo dimerization mutant evidence linking ubiquitylation inheritance to dimerization; single lab","pmids":["27052173"],"is_preprint":false},{"year":2020,"finding":"Spt6 (histone chaperone and transcription elongation factor) directly binds to dCENP-A and prevents loss of old CENP-A nucleosomes during centromeric transcription in both Drosophila and human cells; phosphomimetic dCENP-A residues reduce Spt6 association and CENP-A retention at centromeres.","method":"Direct binding assay (Spt6–dCENP-A), phosphomutant CENP-A expression, immunofluorescence in Drosophila and human cells","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 — direct binding assay plus in vivo phosphomutant analysis in two organisms; single lab","pmids":["32522980"],"is_preprint":false},{"year":2024,"finding":"CENP-A acts as an m6A reader of centromeric RNA (cenRNA): m6A-modified cenRNA stabilizes centromeric localization of CENP-A during S phase; mutations at CENP-A Leu61 and Arg63 abolish this interaction, leading to loss of centromere-bound CENP-A during S phase, compromised centromere integrity, and abnormal chromosome segregation.","method":"m6A-seq, CENP-A point mutagenesis, ChIP, chromosome segregation assays in cancer cells","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 — m6A mapping combined with CENP-A mutagenesis identifying specific residues mediating RNA reading with defined functional phenotype","pmids":["39305902"],"is_preprint":false},{"year":2019,"finding":"Centromeric tri-nucleosome cryo-EM structures show that H3-CENP-A-H3 tri-nucleosomes adopt an untwisted architecture with outward-facing linker DNA between nucleosomes, distinct from canonical H3-H3-H3 tri-nucleosomes; this configuration may expose the CENP-A nucleosome in condensed chromatin for centromeric protein access.","method":"Cryo-EM structure of reconstituted tri-nucleosomes containing central CENP-A nucleosome","journal":"Structure (London, England : 1993)","confidence":"High","confidence_rationale":"Tier 1 — cryo-EM structure of reconstituted CENP-A-containing chromatin fiber unit","pmids":["31711756"],"is_preprint":false},{"year":2015,"finding":"Both the N-terminal tail (small portion) and the centromere-targeting domain (CATD) of CENP-A are required for initial recruitment of CENP-C and CENP-T during centromere establishment; these requirements differ from those for maintaining centromere identity.","method":"LacI-LacO tethering of H3-CENP-A chimeras, immunofluorescence readout of CENP-C and CENP-T recruitment","journal":"The Journal of cell biology","confidence":"Medium","confidence_rationale":"Tier 2 — domain-swap gain-of-function assay with specific centromere protein recruitment readout; single lab","pmids":["25713413"],"is_preprint":false},{"year":2013,"finding":"Natively assembled human CENP-A nucleosomes are octameric throughout the cell cycle, containing CENP-A dimers along with H2B and H4; CENP-A associated with HJURP can exist as monomer or dimer, indicating possible assembly intermediates.","method":"TIRF-coupled photobleaching copy-number counting of single nucleosomes from cultured cells","journal":"Current biology : CB","confidence":"Medium","confidence_rationale":"Tier 2 — single-molecule stoichiometry on native particles; single lab, contrasts with other structural reports","pmids":["23623556"],"is_preprint":false},{"year":2015,"finding":"CRL4(RBBP7) E3 ubiquitin ligase complex (CUL4-DDB1-RBBP7) is required for centromeric loading of CENP-A during G1 but does not influence CENP-A maintenance or pre-nucleosomal CENP-A levels; RBBP7 also binds and stabilizes soluble CENP-A.","method":"siRNA depletion of CRL4 components, quantitative imaging of CENP-A loading, co-immunoprecipitation","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 — biochemical and imaging evidence for E3 ligase role in CENP-A loading; single lab","pmids":["25795299"],"is_preprint":false}],"current_model":"CENP-A, the centromere-specific histone H3 variant, forms octameric nucleosomes whose unique structural features (short αN helix, flexible DNA ends, CATD loop) epigenetically mark centromeres; its cell-cycle-restricted deposition in late mitosis/G1 is controlled by Plk1-mediated Mis18 complex recruitment (counterbalanced by CDK-mediated inhibition), HJURP chaperone delivery (blocked by Cdk1 phosphorylation of CENP-A Ser68 until mitotic exit), and post-translational modifications including α-amino trimethylation by NRMT, Aurora A phosphorylation at Ser7, and ubiquitylation at K124; established CENP-A nucleosomes directly scaffold the CCAN (via CENP-C, CENP-T, CENP-N, and other subunits) to nucleate kinetochore assembly, while HJURP also functions during S phase together with MCM2 to ensure faithful inheritance of CENP-A through DNA replication, and Spt6 retains old CENP-A during centromeric transcription."},"narrative":{"teleology":[{"year":2000,"claim":"Establishing that CENP-A is the upstream organizer of centromeric chromatin answered whether centromere identity depends on a single histone variant: Cenpa-null mouse embryos lose CENP-B and CENP-C from centromeres and die early in development, proving CENP-A is essential and epistatic to other centromere proteins.","evidence":"Gene-targeted knockout mouse with immunofluorescence of null embryos","pmids":["10655499"],"confidence":"High","gaps":["Downstream mechanism by which CENP-A loss disperses CENP-C was not resolved","Whether CENP-A is sufficient (not just necessary) for centromere identity was untested"]},{"year":2001,"claim":"Identifying mitosis-specific phosphorylation of CENP-A revealed that this histone variant undergoes cell-cycle-regulated modification analogous to H3 Ser10 phosphorylation, suggesting kinetochore-specific signaling layers.","evidence":"Phospho-specific antibodies with cell-cycle immunofluorescence in human cells","pmids":["11171370"],"confidence":"Medium","gaps":["The kinase responsible was not identified in this study","Functional consequence of this phosphorylation event was not demonstrated"]},{"year":2006,"claim":"Defining the CENP-A nucleosome-associated complex (NAC/CAD) answered how centromeric chromatin nucleates kinetochore assembly: CENP-A nucleosomes directly recruit a proximal complex of CENP-C, CENP-N, CENP-T, CENP-H, CENP-M, and CENP-U, upon which distal components assemble, and disruption causes chromosome segregation errors.","evidence":"Affinity purification/mass spectrometry, reciprocal Co-IP, siRNA knockdown with mitotic phenotype readout","pmids":["16622419"],"confidence":"High","gaps":["Structural basis of NAC-CENP-A nucleosome contacts was unknown","How individual NAC subunits recognize CENP-A versus H3 nucleosomes was not resolved"]},{"year":2011,"claim":"Structural and functional dissection of HJURP-mediated CENP-A deposition answered how CENP-A is distinguished from canonical H3 for centromere targeting: the HJURP crystal structure revealed a β-sheet domain capping the CENP-A–H4 DNA-binding surface via CENP-A-specific contacts, while CENP-C was shown to recruit the Mis18/M18BP1 licensing complex to prime deposition, and CCAN components were separated into centromere-establishing versus kinetochore-recruiting roles.","evidence":"X-ray crystallography of HJURP–CENP-A–H4 complex; direct binding assays and siRNA depletion for CENP-C–M18BP1 interaction; chromosome engineering with ectopic targeting in DT40 cells","pmids":["21478274","21911481","23277427"],"confidence":"High","gaps":["How HJURP is released after deposition was not resolved","Structure of the complete Mis18–HJURP–CENP-A loading intermediate was lacking"]},{"year":2014,"claim":"Elucidating the cell-cycle licensing mechanism answered why CENP-A deposition is restricted to late mitosis/G1: Plk1 promotes Mis18 complex centromere recruitment while CDK opposes it, and separately Cdk1 phosphorylates CENP-A Ser68 to block HJURP binding until PP1α-mediated dephosphorylation at mitotic exit, creating a two-tiered temporal gate.","evidence":"Chemical inhibition and kinase-dead mutants of Plk1/CDK with CENP-A deposition assays; in vitro kinase assays with phospho-specific antibodies and Co-IP","pmids":["25036634","25556658"],"confidence":"High","gaps":["How Plk1 is recruited to centromeres for Mis18 licensing was not fully defined","Whether additional phosphatases contribute to CENP-A Ser68 dephosphorylation was untested"]},{"year":2015,"claim":"Determining how CENP-B and domain requirements stabilize CENP-A and recruit CCAN during centromere establishment answered what features of CENP-A nucleosomes control initial versus maintenance centromere identity: CENP-B directly binds CENP-A–H4 and stabilizes CENP-A on alphoid DNA, while both the N-terminal tail and the CATD are required for initial CENP-C/CENP-T recruitment.","evidence":"In vitro reconstitution and pulldown assays for CENP-B; LacI-LacO tethering of H3-CENP-A chimeras with immunofluorescence","pmids":["25916850","25713413"],"confidence":"High","gaps":["Structural basis of CENP-B–CENP-A–H4 interaction at atomic resolution was missing","Whether CENP-B stabilization is required at neocentromeres (which lack CENP-B boxes) was unresolved"]},{"year":2016,"claim":"Characterizing the flexible DNA-end architecture and post-translational modification landscape of CENP-A nucleosomes answered how centromeric chromatin is structurally distinguished from bulk chromatin: the short αN helix prevents H1 binding and is essential for kinetochore protein localization; K124 ubiquitylation by CUL4A is inherited through divisions and required for new CENP-A recruitment; and KAT7 acetylation antagonizes heterochromatin to facilitate CENP-A assembly.","evidence":"Cryo-EM and biochemical H1-binding assays with αN domain swaps; in vivo ubiquitylation tracking with dimerization mutants; KAT7 KO and tethering assays with ChIP","pmids":["27499292","27052173","27270040"],"confidence":"High","gaps":["Whether αN-dependent H1 exclusion operates in all cell types was not tested","The deubiquitylase counterbalancing K124 ubiquitylation was not identified"]},{"year":2017,"claim":"Reconstituting the Mis18–HJURP interaction and defining CDK1 control of M18BP1 answered how the loading machinery is biochemically assembled and cell-cycle-gated: two HJURP repeats bind the 4:2:2 Mis18α:Mis18β:M18BP1 hexamer via sites gated by Mis18α N-terminal tails, and CDK1 phosphorylation of M18BP1 destabilizes its binding to the Mis18αβ core, restricting complex formation to G1.","evidence":"Photo-cross-linking and mutagenesis of Mis18–HJURP interface; biochemical reconstitution of Mis18 complex with CDK1 phosphomutant analysis","pmids":["31492860","28059702"],"confidence":"High","gaps":["How dephosphorylation of M18BP1 is temporally coordinated with Plk1 activity was not addressed","Whether the two HJURP repeats deposit two CENP-A–H4 dimers simultaneously was not resolved"]},{"year":2018,"claim":"Discovering HJURP's S-phase function with MCM2 answered how parental CENP-A nucleosomes survive replication fork passage: HJURP transiently associates with centromeres during S phase, co-purifies with the MCM2-7 helicase, and simultaneously binds CENP-A and MCM2, functioning as an inheritance factor rather than solely a deposition chaperone.","evidence":"BioID proximity labeling, Co-IP, siRNA depletion, and in vitro binding assays","pmids":["30293838"],"confidence":"High","gaps":["Whether HJURP recycles CENP-A to the same or sister centromere after fork passage was unknown","Structural basis of the ternary HJURP–CENP-A–MCM2 complex was not determined"]},{"year":2019,"claim":"High-resolution cryo-EM structures of the CENP-A nucleosome and CENP-C-bound CENP-A nucleosome answered how centromeric nucleosomes are conformationally reshaped by CCAN binding: CENP-C binding destabilizes the H2A C-terminal tail to further loosen DNA wrapping and rigidifies the H4 N-terminal tail in a conformation favoring H4K20me1, while tri-nucleosome structures showed CENP-A creates an untwisted fiber exposing it to centromere proteins.","evidence":"Cryo-EM at 2.6 Å of CENP-A nucleosome on α-satellite DNA; cryo-EM of CENP-C–CENP-A nucleosome complex with mutagenesis; cryo-EM of reconstituted H3-CENP-A-H3 tri-nucleosomes","pmids":["31127102","31475439","31711756"],"confidence":"High","gaps":["How CENP-C-induced H4K20me1 is read downstream was not established","Whether the tri-nucleosome architecture is maintained in native centromeric chromatin fibers was not verified"]},{"year":2020,"claim":"Identifying Spt6 as a CENP-A retention factor during centromeric transcription answered how active transcription through centromeres avoids evicting CENP-A: Spt6 directly binds CENP-A and prevents its loss during transcription, with phosphomimetic CENP-A mutations reducing Spt6 association and centromeric CENP-A retention.","evidence":"Direct binding assay between Spt6 and dCENP-A/CENP-A, phosphomutant analysis in Drosophila and human cells","pmids":["32522980"],"confidence":"Medium","gaps":["The kinase phosphorylating CENP-A to regulate Spt6 binding was not identified in human cells","Whether Spt6-mediated retention is coupled to HJURP-mediated recycling was unknown"]},{"year":2022,"claim":"The cryo-EM structure of the complete CCAN bound to a CENP-A nucleosome answered how the inner kinetochore withstands spindle forces: CCAN makes edge-on contacts with the CENP-A nucleosome, linker DNA threads through the CENP-LN channel, and CENP-TWSX partially wraps DNA, topologically entrapping the centromeric fiber.","evidence":"Cryo-EM of reconstituted full CCAN–CENP-A nucleosome complex","pmids":["35420891"],"confidence":"High","gaps":["How dynamic remodeling of CCAN–nucleosome contacts occurs during the tension cycle was not addressed","Whether the topological entrapment model applies equally at neocentromeres was untested"]},{"year":2024,"claim":"Discovering CENP-A as an m6A reader of centromeric RNA answered how centromeric transcripts contribute to CENP-A maintenance: m6A-modified cenRNA stabilizes CENP-A at centromeres during S phase via Leu61 and Arg63, and disruption of this interaction causes CENP-A loss and chromosome missegregation.","evidence":"m6A-seq, CENP-A point mutagenesis at L61/R63, ChIP, and chromosome segregation assays in cancer cells","pmids":["39305902"],"confidence":"High","gaps":["The RNA methyltransferase responsible for centromeric m6A deposition was not identified","Whether m6A reading cooperates with HJURP-MCM2-mediated S-phase retention was not tested","Structural basis of CENP-A–m6A-RNA interaction was not determined"]},{"year":null,"claim":"Major open questions remain regarding how CENP-A inheritance is coordinated across replication, transcription, and post-translational modification pathways, and whether the distinct structural and regulatory mechanisms cooperate or act redundantly to maintain centromere identity through successive cell divisions.","evidence":"","pmids":[],"confidence":"High","gaps":["No integrated structural model of the HJURP–MCM2–CENP-A–Spt6 handoff during replication-coupled retention","Whether m6A-RNA reading and K124 ubiquitylation act in the same or parallel S-phase retention pathways is unknown","How CENP-A deposition/maintenance is regulated in meiosis remains poorly characterized"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0042393","term_label":"histone binding","supporting_discovery_ids":[16,17,19,28]},{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[27]},{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[0,1,12]}],"localization":[{"term_id":"GO:0005694","term_label":"chromosome","supporting_discovery_ids":[0,1,12,18,28]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[1,14]}],"pathway":[{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[4,5,21,22]},{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[6,18,19,28]},{"term_id":"R-HSA-69306","term_label":"DNA Replication","supporting_discovery_ids":[10,27]}],"complexes":["CENP-A nucleosome","CCAN (constitutive centromere-associated network)"],"partners":["HJURP","CENPC","CENPN","CENPT","CENPB","MCM2","SUPT6H","DAXX"],"other_free_text":[]},"mechanistic_narrative":"CENP-A is the centromere-specific histone H3 variant that epigenetically defines active centromeres and serves as the foundational scaffold for kinetochore assembly. CENP-A forms octameric nucleosomes with distinctive structural features — a short αN helix that generates flexible DNA ends excluding linker histone H1, and a CATD loop that confers specificity for the dedicated chaperone HJURP — which together create an exposed chromatin platform recognized by the constitutive centromere-associated network (CCAN) including CENP-C, CENP-N, CENP-T, and additional subunits that topologically entrap DNA to resist spindle forces [PMID:16622419, PMID:35420891, PMID:27499292]. Cell-cycle-restricted deposition of new CENP-A in late mitosis/G1 is enforced by a two-step licensing mechanism in which Plk1 promotes Mis18 complex centromere recruitment (counterbalanced by CDK-mediated inhibition of M18BP1 binding to Mis18α/β) and Cdk1 phosphorylation of CENP-A Ser68 blocks HJURP binding until mitotic exit [PMID:25036634, PMID:28059702, PMID:25556658]. Faithful inheritance of centromeric CENP-A through DNA replication requires HJURP acting with the MCM2-7 helicase during S phase, while post-translational modifications including α-amino trimethylation by NRMT, Aurora A phosphorylation at Ser7, CUL4A-mediated K124 ubiquitylation, and interaction with m6A-modified centromeric RNA further regulate centromere maintenance and chromosome segregation fidelity [PMID:30293838, PMID:28266506, PMID:29760389, PMID:27052173, PMID:39305902]."},"prefetch_data":{"uniprot":{"accession":"P49450","full_name":"Histone H3-like centromeric protein A","aliases":["Centromere autoantigen A","Centromere protein A","CENP-A"],"length_aa":140,"mass_kda":16.0,"function":"Histone H3-like nucleosomal protein that is specifically found in centromeric nucleosomes (PubMed:11756469, PubMed:14667408, PubMed:15282608, PubMed:15475964, PubMed:15702419, PubMed:17651496, PubMed:19114591, PubMed:20739937, PubMed:27499292, PubMed:7962047, PubMed:9024683). Replaces conventional H3 in the nucleosome core of centromeric chromatin that serves as an assembly site for the inner kinetochore (PubMed:18072184). The presence of CENPA subtly modifies the nucleosome structure and the way DNA is wrapped around the nucleosome and gives rise to protruding DNA ends that are less well-ordered and rigid compared to nucleosomes containing histone H3 (PubMed:26878239, PubMed:27499292). May serve as an epigenetic mark that propagates centromere identity through replication and cell division (PubMed:15282608, PubMed:15475964, PubMed:20739937, PubMed:21478274, PubMed:26878239). Required for recruitment and assembly of kinetochore proteins, and as a consequence required for progress through mitosis, chromosome segregation and cytokinesis (PubMed:11756469, PubMed:14667408, PubMed:18072184, PubMed:23818633, PubMed:25556658, PubMed:27499292)","subcellular_location":"Nucleus; Chromosome, centromere","url":"https://www.uniprot.org/uniprotkb/P49450/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/CENPA","classification":"Common Essential","n_dependent_lines":1134,"n_total_lines":1208,"dependency_fraction":0.9387417218543046},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000115163","cell_line_id":"CID000925","localizations":[{"compartment":"nuclear_punctae","grade":3},{"compartment":"nucleolus_gc","grade":1}],"interactors":[{"gene":"HJURP","stoichiometry":0.2},{"gene":"ARGLU1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID000925","total_profiled":1310},"omim":[{"mim_id":"618139","title":"MIS18-BINDING PROTEIN 1; MIS18BP1","url":"https://www.omim.org/entry/618139"},{"mim_id":"618137","title":"MIS18 KINETOCHORE PROTEIN A: MIS18A","url":"https://www.omim.org/entry/618137"},{"mim_id":"616401","title":"SPINDLE APPARATUS COILED-COIL PROTEIN 1; SPDL1","url":"https://www.omim.org/entry/616401"},{"mim_id":"612667","title":"HOLLIDAY JUNCTION RECOGNITION PROTEIN; HJURP","url":"https://www.omim.org/entry/612667"},{"mim_id":"611511","title":"MLF1-INTERACTING PROTEIN; MLF1IP","url":"https://www.omim.org/entry/611511"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"lymphoid tissue","ntpm":12.4}],"url":"https://www.proteinatlas.org/search/CENPA"},"hgnc":{"alias_symbol":["CENP-A","CenH3"],"prev_symbol":[]},"alphafold":{"accession":"P49450","domains":[{"cath_id":"1.10.20.10","chopping":"44-134","consensus_level":"medium","plddt":95.0744,"start":44,"end":134}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P49450","model_url":"https://alphafold.ebi.ac.uk/files/AF-P49450-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P49450-F1-predicted_aligned_error_v6.png","plddt_mean":81.5},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CENPA","jax_strain_url":"https://www.jax.org/strain/search?query=CENPA"},"sequence":{"accession":"P49450","fasta_url":"https://rest.uniprot.org/uniprotkb/P49450.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P49450/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P49450"}},"corpus_meta":[{"pmid":"16622419","id":"PMC_16622419","title":"The human CENP-A centromeric 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\"Affinity purification/mass spectrometry, Co-immunoprecipitation, siRNA knockdown with mitotic phenotype readout\",\n      \"journal\": \"Nature cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP/MS with functional KD validation, foundational study replicated across labs\",\n      \"pmids\": [\"16622419\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"CENP-A (Cenpa) is essential for kinetochore targeting of CENP-C; Cenpa null mouse embryos fail beyond E6.5 and display micronuclei, nuclear bridging, chromatin fragmentation, and dispersal of Cenpb and Cenpc from centromeres, establishing CENP-A as an upstream organizer of centromeric chromatin.\",\n      \"method\": \"Gene targeting (knockout mouse), immunofluorescence of null embryos\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean genetic KO with defined molecular phenotype (loss of CENP-C centromere targeting), replicated in vivo\",\n      \"pmids\": [\"10655499\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Crystal structure of HJURP bound to a CENP-A–H4 heterodimer shows that HJURP's C-terminal β-sheet domain caps the DNA-binding surface of the CENP-A–H4 heterodimer, preventing spontaneous DNA association; a novel surface in CENP-A distinguishes it from H3 for HJURP recognition.\",\n      \"method\": \"X-ray crystallography, in vitro binding assays, mutagenesis\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure with mutagenesis identifying CENP-A-specific HJURP binding determinants\",\n      \"pmids\": [\"21478274\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"CENP-C recruits the Mis18 complex protein M18BP1 to centromeres through direct binding via conserved domains in CENP-C; depletion of CENP-C prevents M18BP1 targeting to metaphase centromeres and inhibits CENP-A chromatin assembly.\",\n      \"method\": \"Protein depletion (siRNA), in vitro direct binding assay (pulldown), immunofluorescence\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct binding assay + loss-of-function with specific CENP-A assembly phenotype\",\n      \"pmids\": [\"21911481\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Polo-like kinase 1 (Plk1) is required to initiate CENP-A deposition by promoting localization of the Mis18 complex to centromeres; CDK activity inhibits Mis18 complex assembly; these two signals form a two-step licensing mechanism controlling cell-cycle-restricted CENP-A deposition.\",\n      \"method\": \"Chemical inhibition and kinase-dead mutants of Plk1/CDK, immunofluorescence, CENP-A deposition assays in human cells\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal functional perturbations with defined molecular and cellular phenotypes\",\n      \"pmids\": [\"25036634\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"CENP-A is phosphorylated at Ser68 by Cdk1 during early mitosis; this phosphorylation eliminates CENP-A binding to HJURP, preventing premature centromeric loading; dephosphorylation by PP1α at mitotic exit permits HJURP-mediated deposition at centromeres.\",\n      \"method\": \"In vitro kinase assay, phospho-specific antibodies, co-immunoprecipitation, CENP-A loading assays in human cells\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro kinase assay combined with mutant CENP-A functional studies and Co-IP\",\n      \"pmids\": [\"25556658\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"CENP-A nucleosomes cycle between octameric and tetrameric forms across the human cell cycle: they exist as tetramers after replication and convert to octamers before replication; these structural transitions are accompanied by reversible chaperone binding and chromatin fiber folding changes and modifications within CENP-A and H4.\",\n      \"method\": \"Native chromatin fractionation, cell-cycle synchronization, mass spectrometry, electron microscopy, FRAP\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple biophysical/biochemical methods from single lab; structural conclusions remain debated\",\n      \"pmids\": [\"22817894\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"CENP-A is rapidly recruited to DNA double-strand breaks along with CENP-N, CENP-T, and CENP-U; the centromere-targeting domain (CATD) of CENP-A is both necessary and sufficient for DSB recruitment; CENP-A accumulation at breaks is enhanced by active NHEJ but is independent of DNA-PKcs, Ligase IV, and H2AX.\",\n      \"method\": \"Multiphoton laser-induced DSBs, I-SceI endonuclease-induced breaks, CENP-A domain mutants, immunofluorescence in human and mouse cells\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — domain mapping with loss-of-function and gain-of-function in live cells, but functional significance at DSBs remains uncertain\",\n      \"pmids\": [\"19717431\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"CENP-A is phosphorylated at a serine residue (analogous to H3 Ser10) during mitosis, occurring after pericentric H3 phosphorylation; phosphorylation begins in prophase, peaks in prometaphase, and is lost by telophase, defining CENP-A phosphorylation as a distinct kinetochore-specific mitotic event.\",\n      \"method\": \"Phospho-specific peptide antibodies, ELISA, western blot, immunofluorescence across cell cycle stages\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — antibody characterization with quantitative immunofluorescence across cell cycle; functional role of this modification not fully established in this paper\",\n      \"pmids\": [\"11171370\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Overexpressed CENP-A mislocalizes to non-centromeric chromatin through a heterotypic tetramer containing CenH3-H4 with H3.3-H4, deposited by the H3.3 chaperone DAXX rather than the dedicated chaperone HJURP; ectopic CENP-A occludes CTCF binding and both effects depend on DAXX.\",\n      \"method\": \"Native ChIP-seq, co-immunoprecipitation, siRNA depletion of chaperones in human cells\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP plus ChIP-seq plus loss-of-function establishing DAXX as chaperone for ectopic CENP-A\",\n      \"pmids\": [\"24530302\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"HJURP transiently associates with centromeres during S phase and binds to pre-existing CENP-A; HJURP co-purifies with the MCM2-7 helicase complex and simultaneously binds CENP-A with MCM2, establishing HJURP as an S-phase retention factor required for inheritance of centromeric CENP-A nucleosomes through DNA replication.\",\n      \"method\": \"BioID proximity labeling, co-immunoprecipitation, siRNA depletion, in vitro binding assays\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — BioID plus direct binding assay plus KD with defined inheritance phenotype; multiple orthogonal methods\",\n      \"pmids\": [\"30293838\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"CENP-A undergoes α-amino trimethylation by the enzyme NRMT in vivo; loss of this modification reduces CENP-T and CENP-I levels at the centromere and causes lagging chromosomes and spindle pole defects.\",\n      \"method\": \"Mass spectrometry identification of modification, in vivo functional assays with CENP-A N-terminal mutants, immunofluorescence\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — modification identified by MS, functional phenotype established by mutant expression, single lab\",\n      \"pmids\": [\"28266506\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Cryo-EM structures of the human inner kinetochore CCAN complex bound to a CENP-A nucleosome show CCAN makes edge-on contacts with CENP-A nucleosomes; linker DNA threading through the CENP-LN channel and partial wrapping by CENP-TWSX provide topological entrapment of DNA as a mechanism to withstand spindle forces.\",\n      \"method\": \"Cryo-electron microscopy structure determination of reconstituted CCAN–CENP-A nucleosome complex\",\n      \"journal\": \"Science (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — near-atomic cryo-EM structure of reconstituted complex with mechanistic interpretation\",\n      \"pmids\": [\"35420891\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"The CCAN has two distinct roles: (1) recruiting CENP-A to establish the kinetochore (via HJURP, CENP-C, CENP-I, or CENP-C C-terminus) and (2) serving as a structural core to directly recruit kinetochore proteins (Ndc80/CPC) independently of CENP-A (via CENP-T or CENP-C N-terminus).\",\n      \"method\": \"Chromosome engineering with conditional centromere removal, ectopic targeting of individual CCAN proteins, immunofluorescence in DT40 cells\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis via chromosome engineering plus ectopic targeting system; functional dissection by multiple constructs\",\n      \"pmids\": [\"23277427\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Forced reduction of CENP-A triggers premature cellular senescence in human primary fibroblasts in a p53-dependent manner; in p53-deficient cells, CENP-A depletion instead causes aberrant mitosis with chromosome missegregation, revealing a p53-dependent safeguard against centromere defects.\",\n      \"method\": \"shRNA knockdown of CENP-A in human fibroblasts, β-galactosidase senescence assay, chromosome segregation analysis\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean KD with defined cellular and molecular phenotype in isogenic p53+/- backgrounds\",\n      \"pmids\": [\"20160010\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"PARP-2 co-immunoprecipitates with CENP-A and CENP-B at mammalian centromeres in a cell-cycle-dependent manner (enriched prometaphase/metaphase, absent by telophase); PARP-2 centromere binding is sequence-independent and occurs only at active centromeres.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence on pseudodicentric and neocentromere-containing chromosomes\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single Co-IP identifying interaction; cell-cycle localization established but mechanistic consequence limited\",\n      \"pmids\": [\"12217960\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"CENP-B forms a stable complex with the CENP-A nucleosome specifically when the CENP-B box sequence is located at the proximal edge of the nucleosome; the CENP-B DNA-binding domain interacts directly with the CENP-A–H4 complex (but not H3.1–H4); CENP-B binding near CENP-A nucleosomes stabilizes CENP-A on alphoid DNA in human cells.\",\n      \"method\": \"In vitro reconstitution, pulldown assays, in vivo CENP-A stability assay\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution with position-specific binding assays and in vivo functional validation\",\n      \"pmids\": [\"25916850\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"CENP-C binding to the CENP-A nucleosome causes two key conformational changes: further exacerbation of loose DNA wrapping via destabilization of the H2A C-terminal tail, and rigidification of the H4 N-terminal tail in a conformation favoring H4K20 monomethylation; CENP-C binds exclusively to CENP-A nucleosomes via an extended hydrophobic interface involving CENP-A V532/V533.\",\n      \"method\": \"Cryo-EM, in vitro binding assays (EMSA, MST), mutagenesis\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — structural and biophysical methods with mutagenesis identifying specific binding contacts\",\n      \"pmids\": [\"31475439\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Cryo-EM structure of native-like human CENP-A nucleosome on α-satellite DNA at 2.6 Å resolution reveals the atomic architecture of the CENP-A octameric nucleosome; scFv binds the H2A-H2B acidic patch without perturbing nucleosome structure.\",\n      \"method\": \"Cryo-EM structure determination with scFv stabilization\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — near-atomic resolution cryo-EM structure of native-sequence CENP-A nucleosome\",\n      \"pmids\": [\"31127102\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"The flexible DNA ends of CENP-A nucleosomes (conferred by the short αN helix) prevent histone H1 binding; substituting the CENP-A αN helix with the H3 αN helix rigidifies DNA ends, enables H1 binding, causes delocalization of kinetochore proteins, and produces mitotic and cytokinesis defects in vivo.\",\n      \"method\": \"Cryo-EM, biochemical H1 binding assays, in vivo H3-CENP-A chimera expression with kinetochore localization and mitotic phenotype readout\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — cryo-EM structure combined with biochemical and in vivo functional analysis of domain swap mutants\",\n      \"pmids\": [\"27499292\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Two HJURP repeats bind concomitantly to the 4:2:2 Mis18α:Mis18β:M18BP1 complex without dissociating it; Mis18α N-terminal tails blockade two identical HJURP-repeat binding sites near the Mis18αβ C-terminal helices; mutation of these sites separates Mis18 from HJURP centromere recruitment.\",\n      \"method\": \"Photo-cross-linking, in vitro binding assays, point mutagenesis, immunofluorescence\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — photo-cross-linking to identify binding interface plus mutagenesis confirming functional relevance\",\n      \"pmids\": [\"31492860\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"CDK1 phosphorylation at two conserved sites in M18BP1's N-terminal 140 residues destabilizes its binding to the Mis18α:Mis18β hexamer (4:2 stoichiometry), limiting Mis18 complex formation and centromere recruitment of HJURP/CENP-A loading to G1 phase.\",\n      \"method\": \"Biochemical reconstitution, viral 2A co-expression system, phosphomutant analysis, centromere localization assays\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — biochemical reconstitution of complex stoichiometry with CDK1 phosphomutant functional validation\",\n      \"pmids\": [\"28059702\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Aurora A phosphorylates CENP-A at serine 7 at inner centromeres; non-phosphorylatable CENP-A S7A weakens sister chromatid cohesion only under spindle tension, and Aurora A is recruited to centromeres in a Bub1-dependent manner; this modification protects bioriented chromosomes against cohesion fatigue.\",\n      \"method\": \"Phospho-specific antibody, non-phosphorylatable CENP-A mutant expression, Aurora A inhibition/depletion, cohesion fatigue assay\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — phosphomutant with tension-specific phenotype and kinase recruitment pathway established; single lab\",\n      \"pmids\": [\"29760389\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"KAT7/HBO1 acetyltransferase interacts with the CENP-A assembly factor M18BP1; KAT7 knockout reduces centromeric CENP-A assembly; tethering KAT7 to ectopic alphoid DNA removes H3K9me3 and stimulates CENP-A assembly by antagonizing Suv39h1-mediated heterochromatin invasion.\",\n      \"method\": \"Co-immunoprecipitation, KO cell line, tethering assay, chromatin immunoprecipitation\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP plus KO with CENP-A assembly phenotype plus tethering assay; single lab\",\n      \"pmids\": [\"27270040\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"CENP-A K124 is acetylated by p300 at G1/S and switches to monomethylation during early and mid-S phase; acetylation of K124 diminishes CENP-C binding and promotes DNA sliding of nucleosomes; K124 mutation alters CENP-C levels and centromeric replication timing.\",\n      \"method\": \"Mass spectrometry, computational modeling, in vivo K124 acetyl/unacetylatable mutant expression, immunofluorescence\",\n      \"journal\": \"Epigenetics & chromatin\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — MS identification with in vivo mutant phenotypes; computational modeling supports but does not fully validate mechanism\",\n      \"pmids\": [\"28396698\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"CENP-A ubiquitylation (K124, by CUL4A-RBX1-COPS8) is inherited through cell divisions; pre-existing ubiquitylated CENP-A is necessary for recruitment of newly synthesized CENP-A; inheritance of ubiquitylation requires CENP-A dimerization, as shown by dimerization mutants.\",\n      \"method\": \"In vivo and in vitro dimerization mutant analysis, cell cycle tracking of ubiquitylated CENP-A, immunofluorescence\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vitro and in vivo dimerization mutant evidence linking ubiquitylation inheritance to dimerization; single lab\",\n      \"pmids\": [\"27052173\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Spt6 (histone chaperone and transcription elongation factor) directly binds to dCENP-A and prevents loss of old CENP-A nucleosomes during centromeric transcription in both Drosophila and human cells; phosphomimetic dCENP-A residues reduce Spt6 association and CENP-A retention at centromeres.\",\n      \"method\": \"Direct binding assay (Spt6–dCENP-A), phosphomutant CENP-A expression, immunofluorescence in Drosophila and human cells\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct binding assay plus in vivo phosphomutant analysis in two organisms; single lab\",\n      \"pmids\": [\"32522980\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"CENP-A acts as an m6A reader of centromeric RNA (cenRNA): m6A-modified cenRNA stabilizes centromeric localization of CENP-A during S phase; mutations at CENP-A Leu61 and Arg63 abolish this interaction, leading to loss of centromere-bound CENP-A during S phase, compromised centromere integrity, and abnormal chromosome segregation.\",\n      \"method\": \"m6A-seq, CENP-A point mutagenesis, ChIP, chromosome segregation assays in cancer cells\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — m6A mapping combined with CENP-A mutagenesis identifying specific residues mediating RNA reading with defined functional phenotype\",\n      \"pmids\": [\"39305902\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Centromeric tri-nucleosome cryo-EM structures show that H3-CENP-A-H3 tri-nucleosomes adopt an untwisted architecture with outward-facing linker DNA between nucleosomes, distinct from canonical H3-H3-H3 tri-nucleosomes; this configuration may expose the CENP-A nucleosome in condensed chromatin for centromeric protein access.\",\n      \"method\": \"Cryo-EM structure of reconstituted tri-nucleosomes containing central CENP-A nucleosome\",\n      \"journal\": \"Structure (London, England : 1993)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — cryo-EM structure of reconstituted CENP-A-containing chromatin fiber unit\",\n      \"pmids\": [\"31711756\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Both the N-terminal tail (small portion) and the centromere-targeting domain (CATD) of CENP-A are required for initial recruitment of CENP-C and CENP-T during centromere establishment; these requirements differ from those for maintaining centromere identity.\",\n      \"method\": \"LacI-LacO tethering of H3-CENP-A chimeras, immunofluorescence readout of CENP-C and CENP-T recruitment\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — domain-swap gain-of-function assay with specific centromere protein recruitment readout; single lab\",\n      \"pmids\": [\"25713413\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Natively assembled human CENP-A nucleosomes are octameric throughout the cell cycle, containing CENP-A dimers along with H2B and H4; CENP-A associated with HJURP can exist as monomer or dimer, indicating possible assembly intermediates.\",\n      \"method\": \"TIRF-coupled photobleaching copy-number counting of single nucleosomes from cultured cells\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — single-molecule stoichiometry on native particles; single lab, contrasts with other structural reports\",\n      \"pmids\": [\"23623556\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"CRL4(RBBP7) E3 ubiquitin ligase complex (CUL4-DDB1-RBBP7) is required for centromeric loading of CENP-A during G1 but does not influence CENP-A maintenance or pre-nucleosomal CENP-A levels; RBBP7 also binds and stabilizes soluble CENP-A.\",\n      \"method\": \"siRNA depletion of CRL4 components, quantitative imaging of CENP-A loading, co-immunoprecipitation\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — biochemical and imaging evidence for E3 ligase role in CENP-A loading; single lab\",\n      \"pmids\": [\"25795299\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CENP-A, the centromere-specific histone H3 variant, forms octameric nucleosomes whose unique structural features (short αN helix, flexible DNA ends, CATD loop) epigenetically mark centromeres; its cell-cycle-restricted deposition in late mitosis/G1 is controlled by Plk1-mediated Mis18 complex recruitment (counterbalanced by CDK-mediated inhibition), HJURP chaperone delivery (blocked by Cdk1 phosphorylation of CENP-A Ser68 until mitotic exit), and post-translational modifications including α-amino trimethylation by NRMT, Aurora A phosphorylation at Ser7, and ubiquitylation at K124; established CENP-A nucleosomes directly scaffold the CCAN (via CENP-C, CENP-T, CENP-N, and other subunits) to nucleate kinetochore assembly, while HJURP also functions during S phase together with MCM2 to ensure faithful inheritance of CENP-A through DNA replication, and Spt6 retains old CENP-A during centromeric transcription.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"CENP-A is the centromere-specific histone H3 variant that epigenetically defines active centromeres and serves as the foundational scaffold for kinetochore assembly. CENP-A forms octameric nucleosomes with distinctive structural features — a short αN helix that generates flexible DNA ends excluding linker histone H1, and a CATD loop that confers specificity for the dedicated chaperone HJURP — which together create an exposed chromatin platform recognized by the constitutive centromere-associated network (CCAN) including CENP-C, CENP-N, CENP-T, and additional subunits that topologically entrap DNA to resist spindle forces [PMID:16622419, PMID:35420891, PMID:27499292]. Cell-cycle-restricted deposition of new CENP-A in late mitosis/G1 is enforced by a two-step licensing mechanism in which Plk1 promotes Mis18 complex centromere recruitment (counterbalanced by CDK-mediated inhibition of M18BP1 binding to Mis18α/β) and Cdk1 phosphorylation of CENP-A Ser68 blocks HJURP binding until mitotic exit [PMID:25036634, PMID:28059702, PMID:25556658]. Faithful inheritance of centromeric CENP-A through DNA replication requires HJURP acting with the MCM2-7 helicase during S phase, while post-translational modifications including α-amino trimethylation by NRMT, Aurora A phosphorylation at Ser7, CUL4A-mediated K124 ubiquitylation, and interaction with m6A-modified centromeric RNA further regulate centromere maintenance and chromosome segregation fidelity [PMID:30293838, PMID:28266506, PMID:29760389, PMID:27052173, PMID:39305902].\",\n  \"teleology\": [\n    {\n      \"year\": 2000,\n      \"claim\": \"Establishing that CENP-A is the upstream organizer of centromeric chromatin answered whether centromere identity depends on a single histone variant: Cenpa-null mouse embryos lose CENP-B and CENP-C from centromeres and die early in development, proving CENP-A is essential and epistatic to other centromere proteins.\",\n      \"evidence\": \"Gene-targeted knockout mouse with immunofluorescence of null embryos\",\n      \"pmids\": [\"10655499\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream mechanism by which CENP-A loss disperses CENP-C was not resolved\", \"Whether CENP-A is sufficient (not just necessary) for centromere identity was untested\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Identifying mitosis-specific phosphorylation of CENP-A revealed that this histone variant undergoes cell-cycle-regulated modification analogous to H3 Ser10 phosphorylation, suggesting kinetochore-specific signaling layers.\",\n      \"evidence\": \"Phospho-specific antibodies with cell-cycle immunofluorescence in human cells\",\n      \"pmids\": [\"11171370\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"The kinase responsible was not identified in this study\", \"Functional consequence of this phosphorylation event was not demonstrated\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Defining the CENP-A nucleosome-associated complex (NAC/CAD) answered how centromeric chromatin nucleates kinetochore assembly: CENP-A nucleosomes directly recruit a proximal complex of CENP-C, CENP-N, CENP-T, CENP-H, CENP-M, and CENP-U, upon which distal components assemble, and disruption causes chromosome segregation errors.\",\n      \"evidence\": \"Affinity purification/mass spectrometry, reciprocal Co-IP, siRNA knockdown with mitotic phenotype readout\",\n      \"pmids\": [\"16622419\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of NAC-CENP-A nucleosome contacts was unknown\", \"How individual NAC subunits recognize CENP-A versus H3 nucleosomes was not resolved\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Structural and functional dissection of HJURP-mediated CENP-A deposition answered how CENP-A is distinguished from canonical H3 for centromere targeting: the HJURP crystal structure revealed a β-sheet domain capping the CENP-A–H4 DNA-binding surface via CENP-A-specific contacts, while CENP-C was shown to recruit the Mis18/M18BP1 licensing complex to prime deposition, and CCAN components were separated into centromere-establishing versus kinetochore-recruiting roles.\",\n      \"evidence\": \"X-ray crystallography of HJURP–CENP-A–H4 complex; direct binding assays and siRNA depletion for CENP-C–M18BP1 interaction; chromosome engineering with ectopic targeting in DT40 cells\",\n      \"pmids\": [\"21478274\", \"21911481\", \"23277427\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How HJURP is released after deposition was not resolved\", \"Structure of the complete Mis18–HJURP–CENP-A loading intermediate was lacking\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Elucidating the cell-cycle licensing mechanism answered why CENP-A deposition is restricted to late mitosis/G1: Plk1 promotes Mis18 complex centromere recruitment while CDK opposes it, and separately Cdk1 phosphorylates CENP-A Ser68 to block HJURP binding until PP1α-mediated dephosphorylation at mitotic exit, creating a two-tiered temporal gate.\",\n      \"evidence\": \"Chemical inhibition and kinase-dead mutants of Plk1/CDK with CENP-A deposition assays; in vitro kinase assays with phospho-specific antibodies and Co-IP\",\n      \"pmids\": [\"25036634\", \"25556658\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How Plk1 is recruited to centromeres for Mis18 licensing was not fully defined\", \"Whether additional phosphatases contribute to CENP-A Ser68 dephosphorylation was untested\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Determining how CENP-B and domain requirements stabilize CENP-A and recruit CCAN during centromere establishment answered what features of CENP-A nucleosomes control initial versus maintenance centromere identity: CENP-B directly binds CENP-A–H4 and stabilizes CENP-A on alphoid DNA, while both the N-terminal tail and the CATD are required for initial CENP-C/CENP-T recruitment.\",\n      \"evidence\": \"In vitro reconstitution and pulldown assays for CENP-B; LacI-LacO tethering of H3-CENP-A chimeras with immunofluorescence\",\n      \"pmids\": [\"25916850\", \"25713413\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of CENP-B–CENP-A–H4 interaction at atomic resolution was missing\", \"Whether CENP-B stabilization is required at neocentromeres (which lack CENP-B boxes) was unresolved\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Characterizing the flexible DNA-end architecture and post-translational modification landscape of CENP-A nucleosomes answered how centromeric chromatin is structurally distinguished from bulk chromatin: the short αN helix prevents H1 binding and is essential for kinetochore protein localization; K124 ubiquitylation by CUL4A is inherited through divisions and required for new CENP-A recruitment; and KAT7 acetylation antagonizes heterochromatin to facilitate CENP-A assembly.\",\n      \"evidence\": \"Cryo-EM and biochemical H1-binding assays with αN domain swaps; in vivo ubiquitylation tracking with dimerization mutants; KAT7 KO and tethering assays with ChIP\",\n      \"pmids\": [\"27499292\", \"27052173\", \"27270040\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether αN-dependent H1 exclusion operates in all cell types was not tested\", \"The deubiquitylase counterbalancing K124 ubiquitylation was not identified\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Reconstituting the Mis18–HJURP interaction and defining CDK1 control of M18BP1 answered how the loading machinery is biochemically assembled and cell-cycle-gated: two HJURP repeats bind the 4:2:2 Mis18α:Mis18β:M18BP1 hexamer via sites gated by Mis18α N-terminal tails, and CDK1 phosphorylation of M18BP1 destabilizes its binding to the Mis18αβ core, restricting complex formation to G1.\",\n      \"evidence\": \"Photo-cross-linking and mutagenesis of Mis18–HJURP interface; biochemical reconstitution of Mis18 complex with CDK1 phosphomutant analysis\",\n      \"pmids\": [\"31492860\", \"28059702\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How dephosphorylation of M18BP1 is temporally coordinated with Plk1 activity was not addressed\", \"Whether the two HJURP repeats deposit two CENP-A–H4 dimers simultaneously was not resolved\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Discovering HJURP's S-phase function with MCM2 answered how parental CENP-A nucleosomes survive replication fork passage: HJURP transiently associates with centromeres during S phase, co-purifies with the MCM2-7 helicase, and simultaneously binds CENP-A and MCM2, functioning as an inheritance factor rather than solely a deposition chaperone.\",\n      \"evidence\": \"BioID proximity labeling, Co-IP, siRNA depletion, and in vitro binding assays\",\n      \"pmids\": [\"30293838\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether HJURP recycles CENP-A to the same or sister centromere after fork passage was unknown\", \"Structural basis of the ternary HJURP–CENP-A–MCM2 complex was not determined\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"High-resolution cryo-EM structures of the CENP-A nucleosome and CENP-C-bound CENP-A nucleosome answered how centromeric nucleosomes are conformationally reshaped by CCAN binding: CENP-C binding destabilizes the H2A C-terminal tail to further loosen DNA wrapping and rigidifies the H4 N-terminal tail in a conformation favoring H4K20me1, while tri-nucleosome structures showed CENP-A creates an untwisted fiber exposing it to centromere proteins.\",\n      \"evidence\": \"Cryo-EM at 2.6 Å of CENP-A nucleosome on α-satellite DNA; cryo-EM of CENP-C–CENP-A nucleosome complex with mutagenesis; cryo-EM of reconstituted H3-CENP-A-H3 tri-nucleosomes\",\n      \"pmids\": [\"31127102\", \"31475439\", \"31711756\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How CENP-C-induced H4K20me1 is read downstream was not established\", \"Whether the tri-nucleosome architecture is maintained in native centromeric chromatin fibers was not verified\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Identifying Spt6 as a CENP-A retention factor during centromeric transcription answered how active transcription through centromeres avoids evicting CENP-A: Spt6 directly binds CENP-A and prevents its loss during transcription, with phosphomimetic CENP-A mutations reducing Spt6 association and centromeric CENP-A retention.\",\n      \"evidence\": \"Direct binding assay between Spt6 and dCENP-A/CENP-A, phosphomutant analysis in Drosophila and human cells\",\n      \"pmids\": [\"32522980\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"The kinase phosphorylating CENP-A to regulate Spt6 binding was not identified in human cells\", \"Whether Spt6-mediated retention is coupled to HJURP-mediated recycling was unknown\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"The cryo-EM structure of the complete CCAN bound to a CENP-A nucleosome answered how the inner kinetochore withstands spindle forces: CCAN makes edge-on contacts with the CENP-A nucleosome, linker DNA threads through the CENP-LN channel, and CENP-TWSX partially wraps DNA, topologically entrapping the centromeric fiber.\",\n      \"evidence\": \"Cryo-EM of reconstituted full CCAN–CENP-A nucleosome complex\",\n      \"pmids\": [\"35420891\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How dynamic remodeling of CCAN–nucleosome contacts occurs during the tension cycle was not addressed\", \"Whether the topological entrapment model applies equally at neocentromeres was untested\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Discovering CENP-A as an m6A reader of centromeric RNA answered how centromeric transcripts contribute to CENP-A maintenance: m6A-modified cenRNA stabilizes CENP-A at centromeres during S phase via Leu61 and Arg63, and disruption of this interaction causes CENP-A loss and chromosome missegregation.\",\n      \"evidence\": \"m6A-seq, CENP-A point mutagenesis at L61/R63, ChIP, and chromosome segregation assays in cancer cells\",\n      \"pmids\": [\"39305902\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The RNA methyltransferase responsible for centromeric m6A deposition was not identified\", \"Whether m6A reading cooperates with HJURP-MCM2-mediated S-phase retention was not tested\", \"Structural basis of CENP-A–m6A-RNA interaction was not determined\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Major open questions remain regarding how CENP-A inheritance is coordinated across replication, transcription, and post-translational modification pathways, and whether the distinct structural and regulatory mechanisms cooperate or act redundantly to maintain centromere identity through successive cell divisions.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No integrated structural model of the HJURP–MCM2–CENP-A–Spt6 handoff during replication-coupled retention\", \"Whether m6A-RNA reading and K124 ubiquitylation act in the same or parallel S-phase retention pathways is unknown\", \"How CENP-A deposition/maintenance is regulated in meiosis remains poorly characterized\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0042393\", \"supporting_discovery_ids\": [16, 17, 19, 28]},\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [27]},\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [0, 1, 12]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005694\", \"supporting_discovery_ids\": [0, 1, 12, 18, 28]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [1, 14]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [4, 5, 21, 22]},\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [6, 18, 19, 28]},\n      {\"term_id\": \"R-HSA-69306\", \"supporting_discovery_ids\": [10, 27]}\n    ],\n    \"complexes\": [\n      \"CENP-A nucleosome\",\n      \"CCAN (constitutive centromere-associated network)\"\n    ],\n    \"partners\": [\n      \"HJURP\",\n      \"CENPC\",\n      \"CENPN\",\n      \"CENPT\",\n      \"CENPB\",\n      \"MCM2\",\n      \"SUPT6H\",\n      \"DAXX\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}