{"gene":"ZC3HC1","run_date":"2026-04-28T23:00:24","timeline":{"discoveries":[{"year":2003,"finding":"NIPA (ZC3HC1) was identified as a novel downstream target of NPM-ALK via yeast two-hybrid screen. NIPA contains a classical nuclear translocation signal in its C terminus directing nuclear localization, interacts with NPM-ALK and other ALK fusions in a tyrosine kinase-dependent manner, and is phosphorylated on tyrosine and serine residues (major site: Ser-354) in NPM-ALK-expressing cells. Overexpression of NIPA protected Ba/F3 cells from apoptosis induced by IL-3 withdrawal; mutations of the nuclear translocation signal or Ser-354 impaired this antiapoptotic function.","method":"Yeast two-hybrid screen, co-immunoprecipitation, site-directed mutagenesis, overexpression/dominant-negative in Ba/F3 cells","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP, mutagenesis, and functional rescue, multiple orthogonal methods","pmids":["12748172"],"is_preprint":false},{"year":2005,"finding":"NIPA (ZC3HC1) is an F-box-containing protein that forms an SCF-type E3 ubiquitin ligase (SCF(NIPA)) that targets nuclear cyclin B1 for ubiquitination and degradation in interphase, thereby controlling mitotic entry. Cell-cycle-dependent phosphorylation of NIPA restricts its ubiquitination activity to interphase. RNAi-mediated inactivation of NIPA causes nuclear accumulation of cyclin B1 in interphase, activation of cyclin B1-Cdk1 kinase activity, and premature mitotic entry.","method":"RNAi knockdown, co-immunoprecipitation (SCF complex assembly), ubiquitination assay, cell cycle analysis","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1-2 — E3 ligase activity demonstrated, substrate identified, RNAi phenotype with specific molecular readout, highly cited foundational paper","pmids":["16009132"],"is_preprint":false},{"year":2007,"finding":"Cyclin B1/Cdk1 phosphorylates NIPA at Ser-395 in mitosis. Two additional phosphorylation sites (Ser-359 and Ser-395) beyond the previously described Ser-354 were identified within the cyclin B1-binding region of NIPA. Mutation of both Ser-359 and Ser-395 impaired inactivation of the SCF(NIPA) complex, resulting in reduced mitotic cyclin B1 levels. This defines a positive-feedback mechanism whereby cyclin B1/Cdk1 amplifies NIPA phosphorylation to contribute to regulation of its own abundance in early mitosis.","method":"In vitro kinase assay, site-directed mutagenesis, cyclin B1 binding domain mapping, cell cycle synchronization and immunoblotting","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — in vitro kinase assay plus mutagenesis with defined functional consequence","pmids":["17389604"],"is_preprint":false},{"year":2011,"finding":"Phosphorylated NIPA is degraded in late mitosis in an APC/C(Cdh1)-dependent manner. Binding of the unphosphorylated form of NIPA to Skp1 interferes with binding to the APC/C adaptor protein Cdh1, thereby protecting unphosphorylated NIPA from APC/C-mediated degradation in interphase. This defines a novel mode of regulating APC/C-mediated ubiquitination via competition between SCF and APC/C substrate adaptors.","method":"Co-immunoprecipitation, cell cycle synchronization, siRNA knockdown of Cdh1, immunoblotting","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP, Cdh1 knockdown confirmation, mechanistically distinct finding with orthogonal validations","pmids":["22205987"],"is_preprint":false},{"year":2012,"finding":"ERK2 (but not ERK1) is the kinase responsible for the critical initial phosphorylation of NIPA at Ser-354 and Ser-359 at G2/M, inactivating the SCF(NIPA) complex. In vitro kinase assays showed both ERK1 and ERK2 can phosphorylate NIPA, but shRNA-mediated stable knockdown combined with cell cycle synchronization showed only ERK2 mediates NIPA inactivation in cells. ERK2 knockdown leads to a delay at G2/M transition, phenocopying phospho-deficient NIPA mutants.","method":"In vitro kinase assay, shRNA stable knockdown, cell cycle synchronization, pharmacologic inhibition of ERK1/2, phospho-deficient NIPA mutants","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — in vitro kinase assay plus genetic (shRNA) validation with matched phenotype, multiple orthogonal approaches","pmids":["22955283"],"is_preprint":false},{"year":2016,"finding":"The CAD-associated coding polymorphism rs11556924 in ZC3HC1 (Arg363His) results in lower regulatory phosphorylation of NIPA at the risk variant (Arg363), giving higher SCF(NIPA) activity, which causes decreased cyclin B1 stability in the nucleus, slowing nuclear cyclin B1 accumulation and extending mitosis. The protective His363 variant shows increased phosphorylation at Ser354, higher protein expression, and greater nuclear mobility.","method":"Genome editing (CRISPR), cell cycle analysis, immunoblotting, FRAP (nuclear mobility), phospho-specific immunoblotting","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — genome-editing approach, multiple orthogonal methods linking variant to molecular mechanism and cell cycle phenotype","pmids":["27226629"],"is_preprint":false},{"year":2017,"finding":"The protective His363 NIPA variant (rs11556924) exhibits increased phosphorylation at Ser354 and higher protein expression compared with the risk Arg363 variant. Neither SKP1 nor CCNB1 binding is affected by the polymorphism. NIPA His363 exhibits greater nuclear mobility by FRAP. NIPA suppression reduces proliferation in HeLa cells, and the protective variant reduces cell proliferation relative to the risk variant.","method":"Allele-specific expression analysis, immunoblotting with phospho-specific antibodies, co-immunoprecipitation (SKP1, CCNB1 binding), FRAP, siRNA knockdown, proliferation assays","journal":"Circulation. Cardiovascular genetics","confidence":"Medium","confidence_rationale":"Tier 2 — multiple methods from single lab, confirms and extends mechanistic findings from prior study","pmids":["28115489"],"is_preprint":false},{"year":2019,"finding":"NPM-ALK expression causes constitutive phosphorylation of NIPA on multiple serine/threonine residues. Mass spectrometry proteomics identified nine significantly upregulated sites; five key residues (Ser-338, Ser-344, Ser-370, Ser-381, Thr-387) were confirmed by phospho-deficient mutagenesis. ALK-induced phosphorylation influences NIPA-NPM-ALK interaction and localization but does not alter SCF(NIPA) complex formation. Silencing these five residues increased NIPA-NPM-ALK binding and slightly reduced cell proliferation.","method":"Mass spectrometry-based phosphoproteomics, site-directed mutagenesis of phospho-deficient mutants, co-immunoprecipitation, immunofluorescence localization, proliferation assays","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 1-2 — MS identification confirmed by mutagenesis, single lab with multiple orthogonal methods","pmids":["31434245"],"is_preprint":false},{"year":2020,"finding":"NIPA (ZC3HC1) binds FANCD2 and regulates its nuclear abundance, placing NIPA as a component of the Fanconi anemia (FA)/BRCA DNA repair pathway. Knockout of Nipa in mice caused accumulation of DNA damage in hematopoietic stem cells, premature aging phenotype, and upon replication stress, complete bone marrow failure and death with 100% penetrance.","method":"Co-immunoprecipitation (NIPA-FANCD2), Nipa knockout mouse model, immunofluorescence (DNA damage foci), HSC functional assays, replication stress induction","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 — Co-IP identifies binding partner, KO mouse with defined molecular and cellular phenotypes, strong evidence from multiple approaches","pmids":["32338640"],"is_preprint":false},{"year":2021,"finding":"ZC3HC1 is an inherent structural component of the nuclear basket (NB), present at nuclear envelopes of both proliferating and terminally differentiated vertebrate cells. ZC3HC1 is required for enabling approximately half the total amount of TPR to be NB-appended; loss of ZC3HC1 reduces the NB-associated TPR pool without ablating TPR entirely from the NPC.","method":"Immunofluorescence microscopy, subcellular fractionation, siRNA knockdown, antibody-based localization in multiple vertebrate cell types","journal":"Cells","confidence":"High","confidence_rationale":"Tier 2 — direct localization with functional consequence (TPR NB-association), replicated across multiple cell types in one thorough study","pmids":["34440706"],"is_preprint":false},{"year":2022,"finding":"ZC3HC1 functions as a second structural scaffold element of the nuclear basket, distinct from TPR. In vivo and in vitro experiments showed ZC3HC1 enables stepwise recruitment of TPR subpopulations to the NB and their linkage to already NPC-anchored TPR polypeptides. Rapid degron-mediated elimination of ZC3HC1 causes prompt detachment of ZC3HC1-appended TPR polypeptides from the NB and their release into the nucleoplasm. ZC3HC1 can link TPR polypeptides to each other even at sites remote from the NB.","method":"In vitro reconstitution, auxin-inducible degron (AID) for rapid protein elimination, live-cell imaging, immunofluorescence, nuclear basket fractionation","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstitution plus AID-based in vivo validation, mechanistic clarity on structural role","pmids":["35609216"],"is_preprint":false},{"year":2022,"finding":"NIPA is required for effective NPM-ALK-driven lymphomagenesis. Nipa deletion in primary mouse embryonic fibroblasts reduced transformation ability and colony formation upon NPM-ALK expression. Downregulating NIPA in NPM-ALK+ cell lines decreased proliferation. In vivo mouse transplantation models showed Nipa deletion inhibited NPM-ALK-induced tumorigenesis, prolonged survival, and reduced stem-cell-like features of lymphomas.","method":"Nipa gene knockout (conditional, Lck-Cre), in vivo transplantation mouse models, colony formation assays, siRNA knockdown, ALK inhibitor combination studies","journal":"Frontiers in oncology","confidence":"Medium","confidence_rationale":"Tier 2 — genetic KO in vivo with clear phenotype, but pathway mechanism not fully resolved beyond prior findings","pmids":["35646639"],"is_preprint":false},{"year":2023,"finding":"ZC3HC1 (and its yeast homologue Pml39p/ScPml39p) contains a nuclear basket-interaction domain (NuBaID) comprising two similarly built modules, both essential for binding NB-resident TPR. This bimodular NuBaID is evolutionarily conserved across humans, Dictyostelium discoideum, and Saccharomyces cerevisiae. Pml39p enables linkage between subpopulations of Mlp1p (yeast TPR homologue) via the same bimodular domain.","method":"Domain deletion and mutagenesis, in vitro binding assays, yeast genetics, immunofluorescence localization, phylogenetic/structural analysis","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 1 — domain mapping with mutagenesis and in vitro binding, validated across multiple organisms","pmids":["36857168"],"is_preprint":false},{"year":2025,"finding":"HROB suppresses lung adenocarcinoma progression by interacting with ZC3HC1 and reducing its phosphorylation at Ser354. This de-phosphorylation facilitates K27-linked ubiquitination of CCNB1 (cyclin B1) by the SCF(NIPA) complex, promoting cyclin B1 proteasomal degradation, impairing the G2-to-M phase transition, and suppressing cell proliferation and tumor growth.","method":"Co-immunoprecipitation (HROB-ZC3HC1 interaction), phospho-specific immunoblotting, ubiquitination assay (K27-linked), cell cycle analysis, in vivo tumor models","journal":"Cancer science","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP identifies new binding partner with mechanistic consequence, ubiquitination assay defines linkage type, single lab","pmids":["40654113"],"is_preprint":false},{"year":2025,"finding":"In human fibroblasts, ZC3HC1 localization to nuclear pores is TPR-dependent, but TPR remains localized to pores when ZC3HC1 is depleted, indicating the ZC3HC1-TPR dependence is asymmetric. Knockdown of ZC3HC1 does not compromise senescence-associated heterochromatin foci (SAHF) or the senescence-associated secretory phenotype (SASP), which depend on TPR. TPR and ZC3HC1 knockdowns have largely distinct transcriptional consequences.","method":"siRNA-mediated knockdown, immunofluorescence, RNA sequencing","journal":"Wellcome open research","confidence":"Medium","confidence_rationale":"Tier 2 — siRNA with immunofluorescence and transcriptomics, functionally distinguishes ZC3HC1 from TPR, single lab","pmids":["40443800"],"is_preprint":false},{"year":2026,"finding":"ZC3HC1 (NIPA) acts as a dosage-sensitive modulator of vascular smooth muscle cell (SMC) phenotype. Partial ZC3HC1 knockdown increases SMC migration and proliferation and causes cyclin B1 (CCNB1) accumulation with reduced contractile marker expression. Complete Zc3hc1 knockout in mice results in reduced SMC proliferation, lower CCNB1 levels, and exaggerated neointima formation after arterial injury. Immunofluorescence revealed colocalization of NIPA and CCNB1 at the cleavage furrow during mitotic exit.","method":"siRNA knockdown (human SMCs), Zc3hc1 knockout mice, arterial injury model (in vivo neointima formation), immunofluorescence microscopy, transcriptomic profiling","journal":"Arteriosclerosis, thrombosis, and vascular biology","confidence":"Medium","confidence_rationale":"Tier 2 — KO mouse with in vivo vascular phenotype, siRNA recapitulation, immunofluorescence localization with functional context, single lab","pmids":["41815085"],"is_preprint":false}],"current_model":"ZC3HC1/NIPA is an F-box protein that forms an SCF-type E3 ubiquitin ligase (SCF(NIPA)) targeting nuclear cyclin B1 for ubiquitination and degradation in interphase to restrain mitotic entry; its activity is precisely timed by sequential phosphorylation — first by ERK2 at Ser-354/359, then by cyclin B1/Cdk1 at Ser-395 at G2/M — which inactivates the complex to allow cyclin B1 accumulation; unphosphorylated NIPA is protected from APC/C(Cdh1)-mediated degradation by its association with Skp1, while phosphorylated NIPA is degraded in late mitosis; additionally, ZC3HC1 is an inherent structural scaffold of the nuclear pore complex nuclear basket where it recruits and interlinks TPR polypeptides via an evolutionarily conserved bimodular nuclear basket-interaction domain (NuBaID), and it also participates in the Fanconi anemia DNA repair pathway by binding and regulating the nuclear abundance of FANCD2."},"narrative":{"teleology":[{"year":2003,"claim":"The initial molecular identity and nuclear localization of ZC3HC1/NIPA were established when it was recovered as a tyrosine-kinase-dependent interactor of NPM-ALK, revealing a nuclear protein whose Ser-354 phosphorylation is functionally significant for cell survival.","evidence":"Yeast two-hybrid screen, co-immunoprecipitation, mutagenesis, and IL-3 withdrawal apoptosis assay in Ba/F3 cells","pmids":["12748172"],"confidence":"High","gaps":["Endogenous function apart from NPM-ALK context was unknown","The kinase(s) responsible for Ser-354 phosphorylation under physiological conditions had not been identified","No link to cell cycle regulation yet established"]},{"year":2005,"claim":"The core cell-cycle function of ZC3HC1 was defined: NIPA is an F-box protein assembling an SCF(NIPA) E3 ubiquitin ligase that targets nuclear cyclin B1 for degradation during interphase, and its loss causes premature mitotic entry—establishing ZC3HC1 as a gatekeeper of G2/M transition.","evidence":"RNAi knockdown, SCF complex co-immunoprecipitation, ubiquitination assay, cell cycle analysis","pmids":["16009132"],"confidence":"High","gaps":["The upstream kinases regulating NIPA phosphorylation-dependent inactivation at G2/M were unidentified","The ubiquitin chain linkage type on cyclin B1 was not determined","Mechanism of NIPA's own turnover was unknown"]},{"year":2007,"claim":"A positive-feedback loop was revealed in which cyclin B1/Cdk1 itself phosphorylates NIPA at Ser-395 during mitosis, inactivating the SCF(NIPA) complex to amplify cyclin B1 accumulation and commit cells to mitosis.","evidence":"In vitro kinase assay with recombinant cyclin B1/Cdk1, site-directed mutagenesis, cell cycle synchronization","pmids":["17389604"],"confidence":"High","gaps":["The kinase for the initial priming phosphorylation at Ser-354/359 remained unresolved","Whether this feedback is essential in vivo was untested"]},{"year":2011,"claim":"The turnover mechanism of NIPA itself was clarified: phosphorylated NIPA is degraded by APC/C(Cdh1) in late mitosis, while unphosphorylated NIPA is protected because Skp1 binding occludes Cdh1 recognition—establishing a competition model between SCF and APC/C for NIPA regulation.","evidence":"Co-immunoprecipitation, Cdh1 siRNA knockdown, cell cycle synchronization and immunoblotting","pmids":["22205987"],"confidence":"High","gaps":["The degron motif recognized by Cdh1 on phospho-NIPA was not mapped","Whether other APC/C co-activators contribute was not tested"]},{"year":2012,"claim":"ERK2 was identified as the kinase that performs the critical initial phosphorylation of NIPA at Ser-354/359 at G2/M, completing the two-step kinase cascade (ERK2 → cyclin B1/Cdk1) that inactivates SCF(NIPA) and permits mitotic entry.","evidence":"In vitro kinase assay, shRNA knockdown of ERK1 vs ERK2, cell cycle synchronization, pharmacologic ERK inhibition","pmids":["22955283"],"confidence":"High","gaps":["Why ERK2 but not ERK1 is the relevant kinase in cells was mechanistically unexplained","How growth factor signaling couples ERK2 activation to the G2/M clock through NIPA was not resolved"]},{"year":2016,"claim":"The coronary artery disease-associated coding variant rs11556924 (Arg363His) was mechanistically linked to differential SCF(NIPA) activity: the risk Arg363 allele has lower phosphorylation, higher ligase activity, reduced nuclear cyclin B1, and prolonged mitosis, connecting a common human disease-associated polymorphism to the SCF(NIPA)–cyclin B1 axis.","evidence":"CRISPR genome editing, FRAP, phospho-specific immunoblotting, cell cycle analysis","pmids":["27226629","28115489"],"confidence":"High","gaps":["How altered cell cycle kinetics translate to coronary artery disease pathology was not established","In vivo vascular consequences of the variant were not modeled"]},{"year":2020,"claim":"An entirely separate function was uncovered: NIPA binds FANCD2 and regulates its nuclear abundance, placing ZC3HC1 in the Fanconi anemia/BRCA DNA repair pathway; Nipa knockout mice showed hematopoietic stem cell DNA damage accumulation and lethal bone marrow failure upon replication stress.","evidence":"Co-immunoprecipitation (NIPA-FANCD2), Nipa knockout mouse, DNA damage foci quantification, hematopoietic stem cell assays","pmids":["32338640"],"confidence":"High","gaps":["Whether FANCD2 regulation occurs through SCF(NIPA)-mediated ubiquitination or a non-catalytic mechanism was not determined","The relationship between the nuclear basket and DNA repair functions is unclear"]},{"year":2021,"claim":"ZC3HC1 was identified as an inherent structural component of the nuclear pore complex nuclear basket, present in both proliferating and terminally differentiated cells, and required for approximately half the total TPR to associate with the NB—revealing a second major biological role distinct from its SCF ligase function.","evidence":"Immunofluorescence, subcellular fractionation, siRNA knockdown across multiple vertebrate cell types","pmids":["34440706"],"confidence":"High","gaps":["The domains responsible for TPR interaction were not yet mapped","Whether ZC3HC1's basket and ligase roles are coordinated or independent was unknown"]},{"year":2022,"claim":"In vitro reconstitution and auxin-inducible degron approaches demonstrated that ZC3HC1 acts as a bona fide second scaffold of the nuclear basket, stepwise recruiting and interlinking TPR polypeptides; rapid ZC3HC1 elimination causes immediate detachment of its TPR cargo from the NB.","evidence":"In vitro reconstitution, auxin-inducible degron (AID), live-cell imaging, nuclear basket fractionation","pmids":["35609216"],"confidence":"High","gaps":["The stoichiometry of ZC3HC1 per NPC was not determined","Structural basis for ZC3HC1-TPR interaction at atomic resolution was lacking"]},{"year":2023,"claim":"The molecular basis of ZC3HC1's nuclear basket scaffolding was resolved: it contains a bimodular NuBaID (nuclear basket-interaction domain) conserved from yeast (Pml39p) to humans, with both modules essential for TPR binding, establishing deep evolutionary conservation of this structural function.","evidence":"Domain deletion/mutagenesis, in vitro binding assays, yeast genetics, cross-species phylogenetic analysis","pmids":["36857168"],"confidence":"High","gaps":["High-resolution structure of the NuBaID–TPR interface is unavailable","Whether the NuBaID is required for SCF(NIPA) assembly or only for basket scaffolding was not tested"]},{"year":2025,"claim":"Functional differentiation between ZC3HC1 and TPR at the nuclear basket was established: ZC3HC1 localization depends on TPR but not vice versa, and their knockdowns produce largely distinct transcriptomic consequences; additionally, HROB was identified as a binding partner that suppresses ZC3HC1 Ser-354 phosphorylation, promoting K27-linked ubiquitination and degradation of cyclin B1 to restrain lung adenocarcinoma.","evidence":"siRNA knockdown with RNA-seq in human fibroblasts; co-immunoprecipitation, K27-linkage-specific ubiquitination assay, in vivo tumor models","pmids":["40443800","40654113"],"confidence":"Medium","gaps":["K27-linked ubiquitination of cyclin B1 by SCF(NIPA) requires confirmation of linkage specificity by independent methods","Whether HROB-mediated regulation of NIPA is relevant beyond lung adenocarcinoma is unknown","Functional consequences of the distinct ZC3HC1 vs TPR transcriptomes are not characterized"]},{"year":2026,"claim":"ZC3HC1 was shown to be a dosage-sensitive modulator of vascular smooth muscle cell phenotype: partial knockdown increases SMC proliferation and cyclin B1 accumulation while complete knockout paradoxically reduces proliferation and CCNB1, with Zc3hc1-null mice showing exaggerated neointima formation after arterial injury.","evidence":"siRNA knockdown in human SMCs, Zc3hc1 knockout mice, wire-injury arterial model, transcriptomic profiling","pmids":["41815085"],"confidence":"Medium","gaps":["The basis for opposite proliferative phenotypes at partial vs. complete loss is mechanistically unexplained","Whether the vascular phenotype is cyclin B1-dependent or reflects other NIPA functions (e.g., DNA repair, nuclear basket) is not resolved","Relevance to human coronary artery disease beyond the rs11556924 variant association is not established"]},{"year":null,"claim":"Key open questions include whether the SCF ligase and nuclear basket scaffold functions of ZC3HC1 are mechanistically independent or coordinated, what determines the switch between these roles, and how ZC3HC1's FANCD2-regulatory function relates to its other activities.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model of full-length ZC3HC1 or the SCF(NIPA) complex exists","Whether the NuBaID and F-box domains are functionally separable in vivo has not been tested","The mechanism by which ZC3HC1 regulates FANCD2 nuclear abundance remains undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[1,2,3,4]},{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[9,10,12]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[1,10]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,1,9,10]},{"term_id":"GO:0005635","term_label":"nuclear envelope","supporting_discovery_ids":[9,10,12]},{"term_id":"GO:0005654","term_label":"nucleoplasm","supporting_discovery_ids":[10,14]}],"pathway":[{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[1,2,4,5]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[1,3,13]},{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[8]},{"term_id":"R-HSA-1852241","term_label":"Organelle biogenesis and maintenance","supporting_discovery_ids":[9,10,12]}],"complexes":["SCF(NIPA)","Nuclear basket"],"partners":["SKP1","CCNB1","TPR","FANCD2","CDH1","MAPK1","HROB","NPM-ALK"],"other_free_text":[]},"mechanistic_narrative":"ZC3HC1 (NIPA) is a multifunctional nuclear protein that operates both as an F-box component of the SCF(NIPA) E3 ubiquitin ligase controlling mitotic entry and as a structural scaffold of the nuclear pore complex nuclear basket. As an SCF subunit, ZC3HC1 targets nuclear cyclin B1 for ubiquitin-mediated degradation during interphase; this activity is terminated at G2/M by sequential phosphorylation—first by ERK2 at Ser-354/359 and then by cyclin B1/Cdk1 at Ser-395—which inactivates the ligase and allows cyclin B1 accumulation for mitotic onset, while phosphorylated NIPA itself is degraded in late mitosis by APC/C(Cdh1) [PMID:16009132, PMID:22955283, PMID:17389604, PMID:22205987]. Independently, ZC3HC1 serves as a second scaffold element of the nuclear basket, recruiting and interlinking approximately half the NPC-associated TPR polypeptides via an evolutionarily conserved bimodular nuclear basket-interaction domain (NuBaID) [PMID:34440706, PMID:35609216, PMID:36857168]. ZC3HC1 also participates in the Fanconi anemia/BRCA DNA repair pathway by binding FANCD2 and regulating its nuclear abundance; Nipa knockout mice accumulate DNA damage in hematopoietic stem cells and develop bone marrow failure upon replication stress [PMID:32338640]."},"prefetch_data":{"uniprot":{"accession":"Q86WB0","full_name":"Zinc finger C3HC-type protein 1","aliases":["Nuclear-interacting partner of ALK","hNIPA","Nuclear-interacting partner of anaplastic lymphoma kinase"],"length_aa":502,"mass_kda":55.3,"function":"Required for proper positioning of a substantial amount of TPR at the nuclear basket (NB) through interaction with TPR","subcellular_location":"Nucleus; Nucleus envelope","url":"https://www.uniprot.org/uniprotkb/Q86WB0/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ZC3HC1","classification":"Not Classified","n_dependent_lines":81,"n_total_lines":1208,"dependency_fraction":0.06705298013245033},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/ZC3HC1","total_profiled":1310},"omim":[{"mim_id":"619746","title":"ZINC FINGER C3HC-TYPE DOMAIN-CONTAINING PROTEIN 1; ZC3HC1","url":"https://www.omim.org/entry/619746"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Nuclear membrane","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/ZC3HC1"},"hgnc":{"alias_symbol":["NIPA"],"prev_symbol":[]},"alphafold":{"accession":"Q86WB0","domains":[{"cath_id":"1.10.1170","chopping":"76-168","consensus_level":"high","plddt":94.6397,"start":76,"end":168},{"cath_id":"-","chopping":"174-289_418-437_456-502","consensus_level":"medium","plddt":82.8754,"start":174,"end":502}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q86WB0","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q86WB0-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q86WB0-F1-predicted_aligned_error_v6.png","plddt_mean":68.31},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ZC3HC1","jax_strain_url":"https://www.jax.org/strain/search?query=ZC3HC1"},"sequence":{"accession":"Q86WB0","fasta_url":"https://rest.uniprot.org/uniprotkb/Q86WB0.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q86WB0/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q86WB0"}},"corpus_meta":[{"pmid":"16009132","id":"PMC_16009132","title":"NIPA defines an SCF-type mammalian E3 ligase that regulates mitotic entry.","date":"2005","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/16009132","citation_count":70,"is_preprint":false},{"pmid":"28751642","id":"PMC_28751642","title":"Anti-obesity and anti-inflammatory effects of synthetic acetic acid vinegar and Nipa vinegar on high-fat-diet-induced obese mice.","date":"2017","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/28751642","citation_count":51,"is_preprint":false},{"pmid":"12748172","id":"PMC_12748172","title":"Identification and characterization of a nuclear interacting partner of anaplastic lymphoma kinase (NIPA).","date":"2003","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12748172","citation_count":45,"is_preprint":false},{"pmid":"17389604","id":"PMC_17389604","title":"Multisite phosphorylation of nuclear interaction partner of ALK (NIPA) at G2/M involves cyclin B1/Cdk1.","date":"2007","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/17389604","citation_count":25,"is_preprint":false},{"pmid":"24286297","id":"PMC_24286297","title":"The ZC3HC1 rs11556924 polymorphism is associated with increased carotid intima-media thickness in patients with rheumatoid arthritis.","date":"2013","source":"Arthritis research & therapy","url":"https://pubmed.ncbi.nlm.nih.gov/24286297","citation_count":22,"is_preprint":false},{"pmid":"22205987","id":"PMC_22205987","title":"APC/C(Cdh1)-mediated degradation of the F-box protein NIPA is regulated by its association with Skp1.","date":"2011","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/22205987","citation_count":19,"is_preprint":false},{"pmid":"34440706","id":"PMC_34440706","title":"ZC3HC1 Is a Novel Inherent Component of the Nuclear Basket, Resident in a State of Reciprocal Dependence with TPR.","date":"2021","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/34440706","citation_count":17,"is_preprint":false},{"pmid":"27226629","id":"PMC_27226629","title":"The Coronary Artery Disease-associated Coding Variant in Zinc Finger C3HC-type Containing 1 (ZC3HC1) Affects Cell Cycle Regulation.","date":"2016","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/27226629","citation_count":15,"is_preprint":false},{"pmid":"18038432","id":"PMC_18038432","title":"Smart and cationic poly(NIPA)/PEI block copolymers as non-viral vectors: in vitro and in vivo transfection studies.","date":"2007","source":"Journal of tissue engineering and regenerative medicine","url":"https://pubmed.ncbi.nlm.nih.gov/18038432","citation_count":14,"is_preprint":false},{"pmid":"29464350","id":"PMC_29464350","title":"NIPA-like domain containing 1 is a novel tumor-promoting factor in oral squamous cell carcinoma.","date":"2018","source":"Journal of cancer research and 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NIPA contains a classical nuclear translocation signal in its C terminus directing nuclear localization, interacts with NPM-ALK and other ALK fusions in a tyrosine kinase-dependent manner, and is phosphorylated on tyrosine and serine residues (major site: Ser-354) in NPM-ALK-expressing cells. Overexpression of NIPA protected Ba/F3 cells from apoptosis induced by IL-3 withdrawal; mutations of the nuclear translocation signal or Ser-354 impaired this antiapoptotic function.\",\n      \"method\": \"Yeast two-hybrid screen, co-immunoprecipitation, site-directed mutagenesis, overexpression/dominant-negative in Ba/F3 cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP, mutagenesis, and functional rescue, multiple orthogonal methods\",\n      \"pmids\": [\"12748172\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"NIPA (ZC3HC1) is an F-box-containing protein that forms an SCF-type E3 ubiquitin ligase (SCF(NIPA)) that targets nuclear cyclin B1 for ubiquitination and degradation in interphase, thereby controlling mitotic entry. Cell-cycle-dependent phosphorylation of NIPA restricts its ubiquitination activity to interphase. RNAi-mediated inactivation of NIPA causes nuclear accumulation of cyclin B1 in interphase, activation of cyclin B1-Cdk1 kinase activity, and premature mitotic entry.\",\n      \"method\": \"RNAi knockdown, co-immunoprecipitation (SCF complex assembly), ubiquitination assay, cell cycle analysis\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — E3 ligase activity demonstrated, substrate identified, RNAi phenotype with specific molecular readout, highly cited foundational paper\",\n      \"pmids\": [\"16009132\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Cyclin B1/Cdk1 phosphorylates NIPA at Ser-395 in mitosis. Two additional phosphorylation sites (Ser-359 and Ser-395) beyond the previously described Ser-354 were identified within the cyclin B1-binding region of NIPA. Mutation of both Ser-359 and Ser-395 impaired inactivation of the SCF(NIPA) complex, resulting in reduced mitotic cyclin B1 levels. This defines a positive-feedback mechanism whereby cyclin B1/Cdk1 amplifies NIPA phosphorylation to contribute to regulation of its own abundance in early mitosis.\",\n      \"method\": \"In vitro kinase assay, site-directed mutagenesis, cyclin B1 binding domain mapping, cell cycle synchronization and immunoblotting\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro kinase assay plus mutagenesis with defined functional consequence\",\n      \"pmids\": [\"17389604\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Phosphorylated NIPA is degraded in late mitosis in an APC/C(Cdh1)-dependent manner. Binding of the unphosphorylated form of NIPA to Skp1 interferes with binding to the APC/C adaptor protein Cdh1, thereby protecting unphosphorylated NIPA from APC/C-mediated degradation in interphase. This defines a novel mode of regulating APC/C-mediated ubiquitination via competition between SCF and APC/C substrate adaptors.\",\n      \"method\": \"Co-immunoprecipitation, cell cycle synchronization, siRNA knockdown of Cdh1, immunoblotting\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP, Cdh1 knockdown confirmation, mechanistically distinct finding with orthogonal validations\",\n      \"pmids\": [\"22205987\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"ERK2 (but not ERK1) is the kinase responsible for the critical initial phosphorylation of NIPA at Ser-354 and Ser-359 at G2/M, inactivating the SCF(NIPA) complex. In vitro kinase assays showed both ERK1 and ERK2 can phosphorylate NIPA, but shRNA-mediated stable knockdown combined with cell cycle synchronization showed only ERK2 mediates NIPA inactivation in cells. ERK2 knockdown leads to a delay at G2/M transition, phenocopying phospho-deficient NIPA mutants.\",\n      \"method\": \"In vitro kinase assay, shRNA stable knockdown, cell cycle synchronization, pharmacologic inhibition of ERK1/2, phospho-deficient NIPA mutants\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro kinase assay plus genetic (shRNA) validation with matched phenotype, multiple orthogonal approaches\",\n      \"pmids\": [\"22955283\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"The CAD-associated coding polymorphism rs11556924 in ZC3HC1 (Arg363His) results in lower regulatory phosphorylation of NIPA at the risk variant (Arg363), giving higher SCF(NIPA) activity, which causes decreased cyclin B1 stability in the nucleus, slowing nuclear cyclin B1 accumulation and extending mitosis. The protective His363 variant shows increased phosphorylation at Ser354, higher protein expression, and greater nuclear mobility.\",\n      \"method\": \"Genome editing (CRISPR), cell cycle analysis, immunoblotting, FRAP (nuclear mobility), phospho-specific immunoblotting\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genome-editing approach, multiple orthogonal methods linking variant to molecular mechanism and cell cycle phenotype\",\n      \"pmids\": [\"27226629\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"The protective His363 NIPA variant (rs11556924) exhibits increased phosphorylation at Ser354 and higher protein expression compared with the risk Arg363 variant. Neither SKP1 nor CCNB1 binding is affected by the polymorphism. NIPA His363 exhibits greater nuclear mobility by FRAP. NIPA suppression reduces proliferation in HeLa cells, and the protective variant reduces cell proliferation relative to the risk variant.\",\n      \"method\": \"Allele-specific expression analysis, immunoblotting with phospho-specific antibodies, co-immunoprecipitation (SKP1, CCNB1 binding), FRAP, siRNA knockdown, proliferation assays\",\n      \"journal\": \"Circulation. Cardiovascular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple methods from single lab, confirms and extends mechanistic findings from prior study\",\n      \"pmids\": [\"28115489\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"NPM-ALK expression causes constitutive phosphorylation of NIPA on multiple serine/threonine residues. Mass spectrometry proteomics identified nine significantly upregulated sites; five key residues (Ser-338, Ser-344, Ser-370, Ser-381, Thr-387) were confirmed by phospho-deficient mutagenesis. ALK-induced phosphorylation influences NIPA-NPM-ALK interaction and localization but does not alter SCF(NIPA) complex formation. Silencing these five residues increased NIPA-NPM-ALK binding and slightly reduced cell proliferation.\",\n      \"method\": \"Mass spectrometry-based phosphoproteomics, site-directed mutagenesis of phospho-deficient mutants, co-immunoprecipitation, immunofluorescence localization, proliferation assays\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 — MS identification confirmed by mutagenesis, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"31434245\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"NIPA (ZC3HC1) binds FANCD2 and regulates its nuclear abundance, placing NIPA as a component of the Fanconi anemia (FA)/BRCA DNA repair pathway. Knockout of Nipa in mice caused accumulation of DNA damage in hematopoietic stem cells, premature aging phenotype, and upon replication stress, complete bone marrow failure and death with 100% penetrance.\",\n      \"method\": \"Co-immunoprecipitation (NIPA-FANCD2), Nipa knockout mouse model, immunofluorescence (DNA damage foci), HSC functional assays, replication stress induction\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP identifies binding partner, KO mouse with defined molecular and cellular phenotypes, strong evidence from multiple approaches\",\n      \"pmids\": [\"32338640\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"ZC3HC1 is an inherent structural component of the nuclear basket (NB), present at nuclear envelopes of both proliferating and terminally differentiated vertebrate cells. ZC3HC1 is required for enabling approximately half the total amount of TPR to be NB-appended; loss of ZC3HC1 reduces the NB-associated TPR pool without ablating TPR entirely from the NPC.\",\n      \"method\": \"Immunofluorescence microscopy, subcellular fractionation, siRNA knockdown, antibody-based localization in multiple vertebrate cell types\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct localization with functional consequence (TPR NB-association), replicated across multiple cell types in one thorough study\",\n      \"pmids\": [\"34440706\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"ZC3HC1 functions as a second structural scaffold element of the nuclear basket, distinct from TPR. In vivo and in vitro experiments showed ZC3HC1 enables stepwise recruitment of TPR subpopulations to the NB and their linkage to already NPC-anchored TPR polypeptides. Rapid degron-mediated elimination of ZC3HC1 causes prompt detachment of ZC3HC1-appended TPR polypeptides from the NB and their release into the nucleoplasm. ZC3HC1 can link TPR polypeptides to each other even at sites remote from the NB.\",\n      \"method\": \"In vitro reconstitution, auxin-inducible degron (AID) for rapid protein elimination, live-cell imaging, immunofluorescence, nuclear basket fractionation\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution plus AID-based in vivo validation, mechanistic clarity on structural role\",\n      \"pmids\": [\"35609216\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"NIPA is required for effective NPM-ALK-driven lymphomagenesis. Nipa deletion in primary mouse embryonic fibroblasts reduced transformation ability and colony formation upon NPM-ALK expression. Downregulating NIPA in NPM-ALK+ cell lines decreased proliferation. In vivo mouse transplantation models showed Nipa deletion inhibited NPM-ALK-induced tumorigenesis, prolonged survival, and reduced stem-cell-like features of lymphomas.\",\n      \"method\": \"Nipa gene knockout (conditional, Lck-Cre), in vivo transplantation mouse models, colony formation assays, siRNA knockdown, ALK inhibitor combination studies\",\n      \"journal\": \"Frontiers in oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO in vivo with clear phenotype, but pathway mechanism not fully resolved beyond prior findings\",\n      \"pmids\": [\"35646639\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"ZC3HC1 (and its yeast homologue Pml39p/ScPml39p) contains a nuclear basket-interaction domain (NuBaID) comprising two similarly built modules, both essential for binding NB-resident TPR. This bimodular NuBaID is evolutionarily conserved across humans, Dictyostelium discoideum, and Saccharomyces cerevisiae. Pml39p enables linkage between subpopulations of Mlp1p (yeast TPR homologue) via the same bimodular domain.\",\n      \"method\": \"Domain deletion and mutagenesis, in vitro binding assays, yeast genetics, immunofluorescence localization, phylogenetic/structural analysis\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — domain mapping with mutagenesis and in vitro binding, validated across multiple organisms\",\n      \"pmids\": [\"36857168\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"HROB suppresses lung adenocarcinoma progression by interacting with ZC3HC1 and reducing its phosphorylation at Ser354. This de-phosphorylation facilitates K27-linked ubiquitination of CCNB1 (cyclin B1) by the SCF(NIPA) complex, promoting cyclin B1 proteasomal degradation, impairing the G2-to-M phase transition, and suppressing cell proliferation and tumor growth.\",\n      \"method\": \"Co-immunoprecipitation (HROB-ZC3HC1 interaction), phospho-specific immunoblotting, ubiquitination assay (K27-linked), cell cycle analysis, in vivo tumor models\",\n      \"journal\": \"Cancer science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP identifies new binding partner with mechanistic consequence, ubiquitination assay defines linkage type, single lab\",\n      \"pmids\": [\"40654113\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In human fibroblasts, ZC3HC1 localization to nuclear pores is TPR-dependent, but TPR remains localized to pores when ZC3HC1 is depleted, indicating the ZC3HC1-TPR dependence is asymmetric. Knockdown of ZC3HC1 does not compromise senescence-associated heterochromatin foci (SAHF) or the senescence-associated secretory phenotype (SASP), which depend on TPR. TPR and ZC3HC1 knockdowns have largely distinct transcriptional consequences.\",\n      \"method\": \"siRNA-mediated knockdown, immunofluorescence, RNA sequencing\",\n      \"journal\": \"Wellcome open research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — siRNA with immunofluorescence and transcriptomics, functionally distinguishes ZC3HC1 from TPR, single lab\",\n      \"pmids\": [\"40443800\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"ZC3HC1 (NIPA) acts as a dosage-sensitive modulator of vascular smooth muscle cell (SMC) phenotype. Partial ZC3HC1 knockdown increases SMC migration and proliferation and causes cyclin B1 (CCNB1) accumulation with reduced contractile marker expression. Complete Zc3hc1 knockout in mice results in reduced SMC proliferation, lower CCNB1 levels, and exaggerated neointima formation after arterial injury. Immunofluorescence revealed colocalization of NIPA and CCNB1 at the cleavage furrow during mitotic exit.\",\n      \"method\": \"siRNA knockdown (human SMCs), Zc3hc1 knockout mice, arterial injury model (in vivo neointima formation), immunofluorescence microscopy, transcriptomic profiling\",\n      \"journal\": \"Arteriosclerosis, thrombosis, and vascular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KO mouse with in vivo vascular phenotype, siRNA recapitulation, immunofluorescence localization with functional context, single lab\",\n      \"pmids\": [\"41815085\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ZC3HC1/NIPA is an F-box protein that forms an SCF-type E3 ubiquitin ligase (SCF(NIPA)) targeting nuclear cyclin B1 for ubiquitination and degradation in interphase to restrain mitotic entry; its activity is precisely timed by sequential phosphorylation — first by ERK2 at Ser-354/359, then by cyclin B1/Cdk1 at Ser-395 at G2/M — which inactivates the complex to allow cyclin B1 accumulation; unphosphorylated NIPA is protected from APC/C(Cdh1)-mediated degradation by its association with Skp1, while phosphorylated NIPA is degraded in late mitosis; additionally, ZC3HC1 is an inherent structural scaffold of the nuclear pore complex nuclear basket where it recruits and interlinks TPR polypeptides via an evolutionarily conserved bimodular nuclear basket-interaction domain (NuBaID), and it also participates in the Fanconi anemia DNA repair pathway by binding and regulating the nuclear abundance of FANCD2.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"ZC3HC1 (NIPA) is a multifunctional nuclear protein that operates both as an F-box component of the SCF(NIPA) E3 ubiquitin ligase controlling mitotic entry and as a structural scaffold of the nuclear pore complex nuclear basket. As an SCF subunit, ZC3HC1 targets nuclear cyclin B1 for ubiquitin-mediated degradation during interphase; this activity is terminated at G2/M by sequential phosphorylation—first by ERK2 at Ser-354/359 and then by cyclin B1/Cdk1 at Ser-395—which inactivates the ligase and allows cyclin B1 accumulation for mitotic onset, while phosphorylated NIPA itself is degraded in late mitosis by APC/C(Cdh1) [PMID:16009132, PMID:22955283, PMID:17389604, PMID:22205987]. Independently, ZC3HC1 serves as a second scaffold element of the nuclear basket, recruiting and interlinking approximately half the NPC-associated TPR polypeptides via an evolutionarily conserved bimodular nuclear basket-interaction domain (NuBaID) [PMID:34440706, PMID:35609216, PMID:36857168]. ZC3HC1 also participates in the Fanconi anemia/BRCA DNA repair pathway by binding FANCD2 and regulating its nuclear abundance; Nipa knockout mice accumulate DNA damage in hematopoietic stem cells and develop bone marrow failure upon replication stress [PMID:32338640].\",\n  \"teleology\": [\n    {\n      \"year\": 2003,\n      \"claim\": \"The initial molecular identity and nuclear localization of ZC3HC1/NIPA were established when it was recovered as a tyrosine-kinase-dependent interactor of NPM-ALK, revealing a nuclear protein whose Ser-354 phosphorylation is functionally significant for cell survival.\",\n      \"evidence\": \"Yeast two-hybrid screen, co-immunoprecipitation, mutagenesis, and IL-3 withdrawal apoptosis assay in Ba/F3 cells\",\n      \"pmids\": [\"12748172\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Endogenous function apart from NPM-ALK context was unknown\",\n        \"The kinase(s) responsible for Ser-354 phosphorylation under physiological conditions had not been identified\",\n        \"No link to cell cycle regulation yet established\"\n      ]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"The core cell-cycle function of ZC3HC1 was defined: NIPA is an F-box protein assembling an SCF(NIPA) E3 ubiquitin ligase that targets nuclear cyclin B1 for degradation during interphase, and its loss causes premature mitotic entry—establishing ZC3HC1 as a gatekeeper of G2/M transition.\",\n      \"evidence\": \"RNAi knockdown, SCF complex co-immunoprecipitation, ubiquitination assay, cell cycle analysis\",\n      \"pmids\": [\"16009132\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"The upstream kinases regulating NIPA phosphorylation-dependent inactivation at G2/M were unidentified\",\n        \"The ubiquitin chain linkage type on cyclin B1 was not determined\",\n        \"Mechanism of NIPA's own turnover was unknown\"\n      ]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"A positive-feedback loop was revealed in which cyclin B1/Cdk1 itself phosphorylates NIPA at Ser-395 during mitosis, inactivating the SCF(NIPA) complex to amplify cyclin B1 accumulation and commit cells to mitosis.\",\n      \"evidence\": \"In vitro kinase assay with recombinant cyclin B1/Cdk1, site-directed mutagenesis, cell cycle synchronization\",\n      \"pmids\": [\"17389604\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"The kinase for the initial priming phosphorylation at Ser-354/359 remained unresolved\",\n        \"Whether this feedback is essential in vivo was untested\"\n      ]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"The turnover mechanism of NIPA itself was clarified: phosphorylated NIPA is degraded by APC/C(Cdh1) in late mitosis, while unphosphorylated NIPA is protected because Skp1 binding occludes Cdh1 recognition—establishing a competition model between SCF and APC/C for NIPA regulation.\",\n      \"evidence\": \"Co-immunoprecipitation, Cdh1 siRNA knockdown, cell cycle synchronization and immunoblotting\",\n      \"pmids\": [\"22205987\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"The degron motif recognized by Cdh1 on phospho-NIPA was not mapped\",\n        \"Whether other APC/C co-activators contribute was not tested\"\n      ]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"ERK2 was identified as the kinase that performs the critical initial phosphorylation of NIPA at Ser-354/359 at G2/M, completing the two-step kinase cascade (ERK2 → cyclin B1/Cdk1) that inactivates SCF(NIPA) and permits mitotic entry.\",\n      \"evidence\": \"In vitro kinase assay, shRNA knockdown of ERK1 vs ERK2, cell cycle synchronization, pharmacologic ERK inhibition\",\n      \"pmids\": [\"22955283\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Why ERK2 but not ERK1 is the relevant kinase in cells was mechanistically unexplained\",\n        \"How growth factor signaling couples ERK2 activation to the G2/M clock through NIPA was not resolved\"\n      ]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"The coronary artery disease-associated coding variant rs11556924 (Arg363His) was mechanistically linked to differential SCF(NIPA) activity: the risk Arg363 allele has lower phosphorylation, higher ligase activity, reduced nuclear cyclin B1, and prolonged mitosis, connecting a common human disease-associated polymorphism to the SCF(NIPA)–cyclin B1 axis.\",\n      \"evidence\": \"CRISPR genome editing, FRAP, phospho-specific immunoblotting, cell cycle analysis\",\n      \"pmids\": [\"27226629\", \"28115489\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"How altered cell cycle kinetics translate to coronary artery disease pathology was not established\",\n        \"In vivo vascular consequences of the variant were not modeled\"\n      ]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"An entirely separate function was uncovered: NIPA binds FANCD2 and regulates its nuclear abundance, placing ZC3HC1 in the Fanconi anemia/BRCA DNA repair pathway; Nipa knockout mice showed hematopoietic stem cell DNA damage accumulation and lethal bone marrow failure upon replication stress.\",\n      \"evidence\": \"Co-immunoprecipitation (NIPA-FANCD2), Nipa knockout mouse, DNA damage foci quantification, hematopoietic stem cell assays\",\n      \"pmids\": [\"32338640\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether FANCD2 regulation occurs through SCF(NIPA)-mediated ubiquitination or a non-catalytic mechanism was not determined\",\n        \"The relationship between the nuclear basket and DNA repair functions is unclear\"\n      ]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"ZC3HC1 was identified as an inherent structural component of the nuclear pore complex nuclear basket, present in both proliferating and terminally differentiated cells, and required for approximately half the total TPR to associate with the NB—revealing a second major biological role distinct from its SCF ligase function.\",\n      \"evidence\": \"Immunofluorescence, subcellular fractionation, siRNA knockdown across multiple vertebrate cell types\",\n      \"pmids\": [\"34440706\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"The domains responsible for TPR interaction were not yet mapped\",\n        \"Whether ZC3HC1's basket and ligase roles are coordinated or independent was unknown\"\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"In vitro reconstitution and auxin-inducible degron approaches demonstrated that ZC3HC1 acts as a bona fide second scaffold of the nuclear basket, stepwise recruiting and interlinking TPR polypeptides; rapid ZC3HC1 elimination causes immediate detachment of its TPR cargo from the NB.\",\n      \"evidence\": \"In vitro reconstitution, auxin-inducible degron (AID), live-cell imaging, nuclear basket fractionation\",\n      \"pmids\": [\"35609216\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"The stoichiometry of ZC3HC1 per NPC was not determined\",\n        \"Structural basis for ZC3HC1-TPR interaction at atomic resolution was lacking\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"The molecular basis of ZC3HC1's nuclear basket scaffolding was resolved: it contains a bimodular NuBaID (nuclear basket-interaction domain) conserved from yeast (Pml39p) to humans, with both modules essential for TPR binding, establishing deep evolutionary conservation of this structural function.\",\n      \"evidence\": \"Domain deletion/mutagenesis, in vitro binding assays, yeast genetics, cross-species phylogenetic analysis\",\n      \"pmids\": [\"36857168\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"High-resolution structure of the NuBaID–TPR interface is unavailable\",\n        \"Whether the NuBaID is required for SCF(NIPA) assembly or only for basket scaffolding was not tested\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Functional differentiation between ZC3HC1 and TPR at the nuclear basket was established: ZC3HC1 localization depends on TPR but not vice versa, and their knockdowns produce largely distinct transcriptomic consequences; additionally, HROB was identified as a binding partner that suppresses ZC3HC1 Ser-354 phosphorylation, promoting K27-linked ubiquitination and degradation of cyclin B1 to restrain lung adenocarcinoma.\",\n      \"evidence\": \"siRNA knockdown with RNA-seq in human fibroblasts; co-immunoprecipitation, K27-linkage-specific ubiquitination assay, in vivo tumor models\",\n      \"pmids\": [\"40443800\", \"40654113\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"K27-linked ubiquitination of cyclin B1 by SCF(NIPA) requires confirmation of linkage specificity by independent methods\",\n        \"Whether HROB-mediated regulation of NIPA is relevant beyond lung adenocarcinoma is unknown\",\n        \"Functional consequences of the distinct ZC3HC1 vs TPR transcriptomes are not characterized\"\n      ]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"ZC3HC1 was shown to be a dosage-sensitive modulator of vascular smooth muscle cell phenotype: partial knockdown increases SMC proliferation and cyclin B1 accumulation while complete knockout paradoxically reduces proliferation and CCNB1, with Zc3hc1-null mice showing exaggerated neointima formation after arterial injury.\",\n      \"evidence\": \"siRNA knockdown in human SMCs, Zc3hc1 knockout mice, wire-injury arterial model, transcriptomic profiling\",\n      \"pmids\": [\"41815085\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"The basis for opposite proliferative phenotypes at partial vs. complete loss is mechanistically unexplained\",\n        \"Whether the vascular phenotype is cyclin B1-dependent or reflects other NIPA functions (e.g., DNA repair, nuclear basket) is not resolved\",\n        \"Relevance to human coronary artery disease beyond the rs11556924 variant association is not established\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key open questions include whether the SCF ligase and nuclear basket scaffold functions of ZC3HC1 are mechanistically independent or coordinated, what determines the switch between these roles, and how ZC3HC1's FANCD2-regulatory function relates to its other activities.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No structural model of full-length ZC3HC1 or the SCF(NIPA) complex exists\",\n        \"Whether the NuBaID and F-box domains are functionally separable in vivo has not been tested\",\n        \"The mechanism by which ZC3HC1 regulates FANCD2 nuclear abundance remains undefined\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [1, 2, 3, 4]},\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [9, 10, 12]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [1, 10]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 1, 9, 10]},\n      {\"term_id\": \"GO:0005635\", \"supporting_discovery_ids\": [9, 10, 12]},\n      {\"term_id\": \"GO:0005654\", \"supporting_discovery_ids\": [10, 14]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [1, 2, 4, 5]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [1, 3, 13]},\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [8]},\n      {\"term_id\": \"R-HSA-1852241\", \"supporting_discovery_ids\": [9, 10, 12]}\n    ],\n    \"complexes\": [\n      \"SCF(NIPA)\",\n      \"Nuclear basket\"\n    ],\n    \"partners\": [\n      \"SKP1\",\n      \"CCNB1\",\n      \"TPR\",\n      \"FANCD2\",\n      \"CDH1\",\n      \"MAPK1\",\n      \"HROB\",\n      \"NPM-ALK\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}