{"gene":"ZFC3H1","run_date":"2026-06-11T09:02:06","timeline":{"discoveries":[{"year":2016,"finding":"ZFC3H1 is a central component of the poly(A) tail exosome targeting (PAXT) connection, acting as a link between the RNA helicase hMTR4 and the nuclear poly(A)-binding protein PABPN1 to facilitate nuclear exosome degradation of polyadenylated transcripts. ZFC3H1/PABPN1 and ZCCHC8/RBM7 contact hMTR4 in a mutually exclusive manner, establishing that NEXT and PAXT are distinct, competing hMTR4-adaptor complexes targeting transcripts of different maturation status.","method":"Protein co-immunoprecipitation, depletion/knockdown with RNA-seq readout, identification of mutual exclusivity by interaction assays","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP establishing mutually exclusive interactions, combined with KD phenotypes; independently replicated by subsequent studies","pmids":["27871484"],"is_preprint":false},{"year":2017,"finding":"ZFC3H1 forms a distinct complex with MTR4 (separate from NEXT) that is required for nuclear surveillance of prematurely terminated RNAs (ptRNAs) and upstream antisense RNAs (uaRNAs). Knockdown of either Mtr4 or ZFC3H1 causes these lncRNAs to accumulate in the cytoplasm and associate with active ribosomes, leading to global repression of translation, establishing a role for the Mtr4/ZFC3H1 complex in preventing cytoplasmic transport and translational disruption.","method":"Complex purification/isolation, siRNA knockdown, cellular fractionation, polysome profiling, RNA immunoprecipitation","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 2 / Moderate — complex isolation plus KD with multiple orthogonal readouts (fractionation, polysome profiling), single lab","pmids":["28733371"],"is_preprint":false},{"year":2018,"finding":"ZFC3H1 is required for the formation of distinct nuclear foci containing polyadenylated RNA when exosome function is abolished. In the absence of ZFC3H1, selected polyadenylated RNAs (coding and non-coding) are exported to the cytoplasm via the mRNA export factor AlyREF, establishing ZFC3H1 as a central nuclear pA+ RNA retention factor that counteracts nuclear export activity.","method":"Co-localization imaging (RNA FISH + immunofluorescence), siRNA knockdown, cellular fractionation, AlyREF epistasis experiments","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Moderate — KD with specific phenotypic readout plus epistasis with AlyREF; multiple orthogonal methods (imaging, fractionation, genetic epistasis)","pmids":["29768216"],"is_preprint":false},{"year":2018,"finding":"ZFC3H1 physically associates with the HIV-1 TAR region and represses HIV-1 transcriptional output and RNAPII recruitment to the LTR. Knockdown of ZFC3H1 increases HIV-1 expression and reactivates HIV-1 from latently infected PBMCs.","method":"ChIP (chromatin immunoprecipitation), siRNA knockdown, reporter assays, flow cytometry of GFP-positive J-Lat cells, ex vivo PBMC infection","journal":"PLoS pathogens","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP plus functional KD readout in multiple cell systems; single lab","pmids":["29554134"],"is_preprint":false},{"year":2019,"finding":"NRDE2 inhibits ZFC3H1 interaction with MTR4 by binding MTR4 via a conserved MTR4-interacting domain (MID), locking MTR4 in a closed conformation and thereby blocking exosome recruitment. Structural and biochemical data confirm that NRDE2 competes with ZFC3H1 for binding to key residues on MTR4.","method":"Structural analysis, biochemical interaction assays, mutagenesis of MTR4-interacting domain, Co-IP","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 1 / Moderate — structural and biochemical data with mutagenesis; negative regulatory interaction with ZFC3H1 mechanistically defined","pmids":["30842217"],"is_preprint":false},{"year":2019,"finding":"Knockout of ZFC3H1 in mouse embryonic stem cells impairs differentiation and leads to de-repression of PRC2-controlled developmental genes, paralleled by decreased PRC2 binding to chromatin, reduced H3K27 methylation, and compromised PRC2 complex stability due to elevated nonspecific RNA bound to PRC2 components.","method":"CRISPR/Cas9 knockout, ChIP-seq for H3K27me3 and PRC2, RNA-seq, RNA immunoprecipitation","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Moderate — KO with multiple orthogonal readouts (ChIP-seq, RNA-IP, differentiation assay) in a single lab","pmids":["31722198"],"is_preprint":false},{"year":2019,"finding":"Celastramycin binds ZFC3H1 as a direct binding partner (pulled down by celastramycin), and ZFC3H1 mediates celastramycin's effects on HIF-1α and NF-κB protein levels, reactive oxygen species, and mitochondrial metabolism in pulmonary artery smooth muscle cells.","method":"Affinity pull-down with celastramycin, siRNA knockdown, western blotting, functional cellular assays","journal":"Circulation research","confidence":"Medium","confidence_rationale":"Tier 3 / Weak — single pull-down assay identifying binding; functional link inferred from KD, single lab","pmids":["31195886"],"is_preprint":false},{"year":2020,"finding":"ZFC3H1 functions as the core dimer partner of MTR4 in the PAXT connection, and three additional proteins—ZC3H3, RBM26, and RBM27—are required for PAXT function. ZC3H3 interacts directly with the MTR4-ZFC3H1 dimer, and loss of any newly identified component results in accumulation of PAXT substrates.","method":"Proteomics of nuclear pA+-RNA bound proteins, Co-IP of MTR4-ZFC3H1 complexes, siRNA knockdown with RNA-seq readout","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 2 / Moderate — proteomic identification plus direct interaction assays and functional KD phenotypes; multiple orthogonal methods, single lab","pmids":["31950173"],"is_preprint":false},{"year":2021,"finding":"Upon exosome inactivation, ZFC3H1 forms nuclear condensates that prevent polyadenylated RNA trafficking to nuclear speckles, thereby blocking export competence. Systematic domain mapping revealed that ZFC3H1 uses distinct domains for condensation and for RNA degradation; condensation activity is required for nuclear RNA retention but not for RNA degradation.","method":"Live-cell imaging, domain deletion/mutation analysis, RNA FISH, siRNA knockdown, fluorescence microscopy of nuclear speckles","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — domain mapping with mutants and imaging; functional dissection of condensation vs. degradation, single lab","pmids":["34530450"],"is_preprint":false},{"year":2022,"finding":"ZFC3H1 is required for the nuclear retention and degradation of intronic polyadenylated (IPA) transcripts that contain intact 5' splice site (5'SS) motifs. ZFC3H1 sequesters mRNAs with 5'SS motifs into nuclear speckles to prevent their nuclear export, functioning in the same pathway as U1-70K (a component of the U1 snRNP).","method":"High-throughput sequencing of cellular fractions, reporter mRNA assays, siRNA knockdown, nuclear speckle disruption experiments, epistasis between ZFC3H1 and U1-70K","journal":"RNA (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 2 / Moderate — fractionation-seq plus reporter assays plus genetic epistasis; multiple orthogonal methods in single lab","pmids":["35351812"],"is_preprint":false},{"year":2023,"finding":"Mutational analysis of ZFC3H1 uncovered a direct ARS2-ZFC3H1 interaction via acidic-rich short linear motifs that compete with ZC3H18 for a common ARS2 epitope. This reveals a separate PAXT branch targeting short adenylated RNAs and explains how ZC3H18 simultaneously promotes NEXT while antagonizing PAXT activity.","method":"Site-directed mutagenesis, Co-IP, competitive binding assays, RNA-seq after KD/KO","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mutagenesis plus binding competition plus functional readout; single lab","pmids":["37889751"],"is_preprint":false},{"year":2023,"finding":"ZFC3H1 is required for PAXT recruitment to transcription start sites (TSSs) of hundreds of genes; loss of ZFC3H1 abolishes recruitment of all PAXT subunits including PAPγ to TSSs and concomitantly increases the abundance of PROMPTs at those sites. ZFC3H1, MTR4, and PAPγ are all implicated in polyadenylation of PROMPTs.","method":"ChIP-seq / genome-wide binding mapping of ZFC3H1, RBM27, and PAPγ; ZFC3H1 KO with RNA-seq; proteomics","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genome-wide ChIP-seq plus KO RNA-seq plus proteomics; multiple orthogonal methods, single lab","pmids":["37875486"],"is_preprint":false},{"year":2024,"finding":"ZFC3H1 is co-transcriptionally loaded onto the first exon/intron of RNA precursors in a 'closed' conformation that blocks exosome recruitment. Upon RNA processing, short RNAs with fewer exons recruit transient PAXT components ZC3H3 and RBM26/27 to the 3' end, triggering ZFC3H1 'opening' and subsequent exosomal degradation, whereas longer RNAs with more exons are directed to nuclear export. This establishes a decoupled loading-and-activation mechanism for ZFC3H1 that pre-configures RNA fate.","method":"iCLIP/eCLIP mapping, domain mutant analysis, Co-IP, RNA-seq fractionation, nascent RNA analysis","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (iCLIP, domain mutants, fractionation) in a focused mechanistic study; single lab","pmids":["39461342"],"is_preprint":false},{"year":2024,"finding":"YTHDC1 and YTHDC2 (YTH-domain m6A reader proteins) interact with ZFC3H1 and U1-70K, and are required for nuclear retention of mRNAs with intact 5'SS motifs. Disruption of m6A deposition inhibits nuclear retention of these transcripts and their accumulation in YTHDC1-enriched foci adjacent to nuclear speckles.","method":"Co-IP (ZFC3H1 with YTHDC1/2), siRNA knockdown, reporter mRNA assays, RNA FISH, m6A inhibition experiments","journal":"Life science alliance","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — Co-IP plus functional KD with reporter readout; single lab, single study","pmids":["39626965"],"is_preprint":false},{"year":2014,"finding":"ZFC3H1 (also known as CCDC131/CSRC2) was identified as a direct binding protein of Celastramycin A by affinity pull-down screening. Knockdown of ZFC3H1 reduced TNFα-induced IL-8 expression, and reporter assays showed ZFC3H1 participates in transcriptional activation of IL-8. UV-irradiation experiments suggested ZFC3H1 may indirectly interact with ERCC1 in an activated DNA repair complex.","method":"Celastramycin A affinity pull-down screen, siRNA knockdown, IL-8 reporter assay, Co-IP suggestion","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 3 / Weak — affinity pull-down plus reporter assay; single lab, single study","pmids":["25268596"],"is_preprint":false},{"year":2022,"finding":"ZFC3H1 participates in human telomerase RNA (hTR) biogenesis via pathways related to the polyadenylated RNA degradation mechanism, as determined by knockdown experiments examining hTR isoforms and localization.","method":"siRNA knockdown, RT-PCR analysis of hTR isoforms, cellular fractionation","journal":"Biomedicines","confidence":"Low","confidence_rationale":"Tier 3 / Weak — KD with RNA readout only; single lab, limited mechanistic detail in abstract","pmids":["35740297"],"is_preprint":false},{"year":2024,"finding":"ZFC3H1 protein competes with lncRNA MSL3P1 for binding to CUL3 mRNA; MSL3P1 prevents ZFC3H1-mediated degradation and cytoplasmic export blockade of CUL3 mRNA by competitive binding, demonstrating ZFC3H1's role in targeting specific mRNAs for exosomal degradation and nuclear retention.","method":"RNA immunoprecipitation, siRNA knockdown of ZFC3H1, RNA pull-down competition assays, cellular fractionation","journal":"Molecular cancer research : MCR","confidence":"Low","confidence_rationale":"Tier 3 / Weak — competitive pull-down and KD; single lab, partial mechanistic follow-up only","pmids":["38718076"],"is_preprint":false}],"current_model":"ZFC3H1 is a core component of the poly(A) exosome targeting (PAXT) connection that, together with MTR4, forms the central dimer of a nuclear RNA surveillance complex; it is co-transcriptionally loaded onto pre-RNAs in a closed conformation that blocks exosome recruitment, and is activated by recruitment of transient components ZC3H3 and RBM26/27 to the 3' ends of short adenylated RNAs, thereby triggering exosomal degradation, while for longer RNAs ZFC3H1 allows switching to nuclear export—and when degradation is impaired, ZFC3H1 forms nuclear condensates that retain polyadenylated RNAs away from speckles and the export machinery."},"narrative":{"mechanistic_narrative":"ZFC3H1 is a central scaffold of the poly(A) tail exosome targeting (PAXT) connection, a nuclear RNA surveillance system that routes polyadenylated transcripts toward exosomal degradation [PMID:27871484]. It forms a core dimer with the RNA helicase MTR4 and bridges MTR4 to the nuclear poly(A)-binding protein PABPN1; this PAXT engagement of MTR4 is mutually exclusive with the NEXT adaptor module (ZCCHC8/RBM7), so that NEXT and PAXT compete for MTR4 to target transcripts of differing maturation status [PMID:27871484]. The MTR4-ZFC3H1 dimer additionally recruits transient subunits ZC3H3, RBM26 and RBM27, and loss of any component stabilizes PAXT substrates [PMID:31950173]. Mechanistically, ZFC3H1 is loaded co-transcriptionally onto the first exon/intron of RNA precursors in a 'closed' conformation that blocks exosome recruitment; short, few-exon RNAs recruit ZC3H3 and RBM26/27 to the 3' end to trigger ZFC3H1 'opening' and degradation, whereas longer transcripts are diverted to nuclear export, establishing a decoupled loading-and-activation switch that pre-configures RNA fate [PMID:39461342]. The MTR4-ZFC3H1 interaction is negatively regulated by NRDE2, which binds MTR4 via a conserved MTR4-interacting domain and competes with ZFC3H1 for key MTR4 residues to lock the helicase closed [PMID:30842217], and a distinct PAXT branch targeting short adenylated RNAs is engaged through a direct ARS2-ZFC3H1 interaction that competes with ZC3H18 [PMID:37889751]. Beyond degradation, ZFC3H1 acts as a nuclear retention factor: when exosome function is lost it forms nuclear condensates that retain polyadenylated RNAs away from nuclear speckles and the AlyREF export machinery, with condensation and degradation served by separable domains [PMID:29768216, PMID:34530450]. It enforces nuclear retention of intronic polyadenylated transcripts bearing intact 5' splice site motifs in the same pathway as U1-70K, sequestering them into nuclear speckles [PMID:35351812], and engages the m6A readers YTHDC1/YTHDC2 to retain 5'SS-containing mRNAs [PMID:39626965]. PAXT is recruited by ZFC3H1 to transcription start sites genome-wide, where its loss abolishes recruitment of PAP-gamma and other subunits and increases PROMPT abundance [PMID:37875486]. Through this surveillance activity ZFC3H1 also supports embryonic stem cell differentiation, preventing nonspecific RNA from compromising PRC2 stability and chromatin occupancy [PMID:31722198], and restrains aberrant cytoplasmic accumulation and translation of unprocessed lncRNAs [PMID:28733371].","teleology":[{"year":2016,"claim":"Established ZFC3H1 as the adaptor defining a distinct MTR4-dependent surveillance pathway, answering how polyadenylated transcripts are selectively delivered to the nuclear exosome.","evidence":"Reciprocal Co-IP and depletion with RNA-seq in human cells, defining PAXT versus NEXT mutual exclusivity on MTR4","pmids":["27871484"],"confidence":"High","gaps":["Did not resolve the structural basis of the MTR4-ZFC3H1 contact","Substrate selectivity rules between NEXT and PAXT not defined"]},{"year":2017,"claim":"Showed the MTR4/ZFC3H1 complex prevents cytoplasmic escape of prematurely terminated and antisense RNAs, linking failed nuclear surveillance to translational disruption.","evidence":"Complex purification, siRNA knockdown, fractionation, polysome profiling and RIP in human cells","pmids":["28733371"],"confidence":"High","gaps":["Mechanism distinguishing retention from degradation not separated","Did not define how transcripts escape to the cytoplasm"]},{"year":2018,"claim":"Defined ZFC3H1 as a nuclear pA+ RNA retention factor that counteracts AlyREF-mediated export, separating retention from degradation as a function.","evidence":"RNA-FISH/IF co-localization, knockdown, fractionation and AlyREF epistasis in human cells","pmids":["29768216"],"confidence":"High","gaps":["Physical basis of foci formation not yet determined","Selectivity of which transcripts are retained unresolved"]},{"year":2019,"claim":"Resolved a negative regulatory switch: NRDE2 competes with ZFC3H1 for MTR4 to lock the helicase closed and block exosome recruitment.","evidence":"Structural and biochemical interaction assays with MTR4-interacting-domain mutagenesis and Co-IP","pmids":["30842217"],"confidence":"High","gaps":["Cellular conditions governing NRDE2-versus-ZFC3H1 occupancy of MTR4 not defined"]},{"year":2019,"claim":"Connected ZFC3H1 surveillance to developmental gene control, showing its loss destabilizes PRC2 via nonspecific RNA and impairs ES cell differentiation.","evidence":"CRISPR knockout in mouse ES cells with H3K27me3/PRC2 ChIP-seq, RNA-seq and RNA-IP","pmids":["31722198"],"confidence":"High","gaps":["Direct versus indirect effect on PRC2 not fully separated","Which RNAs accumulate on PRC2 not identified"]},{"year":2020,"claim":"Expanded the PAXT subunit roster, identifying ZC3H3/RBM26/RBM27 as components recruited to the MTR4-ZFC3H1 dimer required for substrate turnover.","evidence":"Nuclear pA+-RNA proteomics, Co-IP of MTR4-ZFC3H1, and knockdown RNA-seq in human cells","pmids":["31950173"],"confidence":"High","gaps":["Stoichiometry and assembly order of transient subunits unresolved","Whether subunits are constitutive or substrate-induced not settled at the time"]},{"year":2021,"claim":"Dissected ZFC3H1 into separable domains for condensation versus degradation, showing condensate formation drives nuclear RNA retention independent of degradation.","evidence":"Live-cell imaging, domain deletion/mutation, RNA-FISH and speckle microscopy under exosome inactivation","pmids":["34530450"],"confidence":"Medium","gaps":["Biophysical determinants of condensation not characterized","Single lab; physiological trigger for condensation in vivo unclear"]},{"year":2022,"claim":"Showed ZFC3H1 enforces nuclear retention of intronic polyadenylated transcripts with intact 5'SS motifs, placing it in a U1-70K-coupled surveillance pathway.","evidence":"Fractionation-seq, reporter mRNA assays, speckle disruption and ZFC3H1/U1-70K epistasis","pmids":["35351812"],"confidence":"High","gaps":["Direct ZFC3H1-U1 snRNP contact not demonstrated","How 5'SS recognition feeds into retention not molecularly defined"]},{"year":2023,"claim":"Defined an ARS2-ZFC3H1 interaction branch for short adenylated RNAs, explaining how ZC3H18 partitions activity between NEXT and PAXT.","evidence":"Mutagenesis of acidic short linear motifs, competitive binding assays and KD/KO RNA-seq","pmids":["37889751"],"confidence":"Medium","gaps":["Structural detail of the ARS2 epitope contact not resolved","In vivo balance of ZC3H18 versus ZFC3H1 for ARS2 not quantified"]},{"year":2023,"claim":"Mapped ZFC3H1-dependent PAXT recruitment to transcription start sites genome-wide, linking PAXT to PROMPT polyadenylation and turnover.","evidence":"ChIP-seq of ZFC3H1/RBM27/PAP-gamma, ZFC3H1 KO RNA-seq and proteomics","pmids":["37875486"],"confidence":"High","gaps":["How ZFC3H1 is targeted to specific TSSs unresolved","Role of PAP-gamma polyadenylation step mechanistically incomplete"]},{"year":2024,"claim":"Resolved a decoupled loading-and-activation model: co-transcriptional loading in a closed state followed by 3'-end-triggered opening that pre-configures degradation versus export.","evidence":"iCLIP/eCLIP, domain mutants, Co-IP, fractionation and nascent RNA analysis","pmids":["39461342"],"confidence":"High","gaps":["Exact conformational change accompanying opening not structurally defined","Counting mechanism for exon number not elucidated"]},{"year":2024,"claim":"Connected ZFC3H1 retention to m6A reading, showing YTHDC1/2 partner with ZFC3H1 and U1-70K to retain 5'SS-containing mRNAs.","evidence":"Co-IP, knockdown, reporter assays, RNA-FISH and m6A inhibition in human cells","pmids":["39626965"],"confidence":"Medium","gaps":["Direct versus indirect ZFC3H1-YTHDC1/2 contact not separated","Single study; physiological scope of m6A-dependent retention unclear"]},{"year":null,"claim":"How ZFC3H1 substrate-specificity, condensation, and chromatin-proximal recruitment are integrated into a single regulatory logic that decides RNA fate remains unresolved.","evidence":"No single study reconciles co-transcriptional loading, conformational switching, condensate retention, and TSS recruitment into one structural/biochemical model","pmids":[],"confidence":"Low","gaps":["No high-resolution structure of the assembled PAXT-ZFC3H1 complex","Determinants distinguishing degraded versus exported transcripts only partially defined","Reported roles in HIV-1 latency, PRC2/differentiation, and disease-associated mRNAs not unified mechanistically"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[5,9,16]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,7]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[4,10]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,2,8]},{"term_id":"GO:0005654","term_label":"nucleoplasm","supporting_discovery_ids":[2,8,9]}],"pathway":[{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[0,1,7,12]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[2,9,13]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[11]}],"complexes":["PAXT connection"],"partners":["MTR4","PABPN1","ZC3H3","RBM26","RBM27","NRDE2","ARS2","YTHDC1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O60293","full_name":"Zinc finger C3H1 domain-containing protein","aliases":["Coiled-coil domain-containing protein 131","Proline/serine-rich coiled-coil protein 2"],"length_aa":1989,"mass_kda":226.4,"function":"Subunit of the trimeric poly(A) tail exosome targeting (PAXT) complex, a complex that directs a subset of long and polyadenylated poly(A) RNAs for exosomal degradation. The RNA exosome is fundamental for the degradation of RNA in eukaryotic nuclei. Substrate targeting is facilitated by its cofactor MTREX, which links to RNA-binding protein adapters","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/O60293/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/ZFC3H1","classification":"Common Essential","n_dependent_lines":822,"n_total_lines":1208,"dependency_fraction":0.6804635761589404},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CPSF6","stoichiometry":0.2},{"gene":"DDX39B","stoichiometry":0.2},{"gene":"RTCB","stoichiometry":0.2},{"gene":"SNRPA","stoichiometry":0.2},{"gene":"SSRP1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/ZFC3H1","total_profiled":1310},"omim":[{"mim_id":"620956","title":"ZINC FINGER C3H1 DOMAIN-CONTAINING PROTEIN; ZFC3H1","url":"https://www.omim.org/entry/620956"},{"mim_id":"620082","title":"RNA-BINDING MOTIF PROTEIN 27; RBM27","url":"https://www.omim.org/entry/620082"},{"mim_id":"620081","title":"RNA-BINDING MOTIF PROTEIN 26; RBM26","url":"https://www.omim.org/entry/620081"},{"mim_id":"618640","title":"ZINC FINGER CCCH DOMAIN-CONTAINING PROTEIN 3; ZC3H3","url":"https://www.omim.org/entry/618640"},{"mim_id":"616865","title":"POLY(A) POLYMERASE, GAMMA; PAPOLG","url":"https://www.omim.org/entry/616865"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Intermediate filaments","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/ZFC3H1"},"hgnc":{"alias_symbol":["MGC23401","KIAA0546","CSRC2"],"prev_symbol":["PSRC2","CCDC131"]},"alphafold":{"accession":"O60293","domains":[{"cath_id":"1.10.287,1.10.287","chopping":"820-928","consensus_level":"medium","plddt":82.0594,"start":820,"end":928},{"cath_id":"-","chopping":"1152-1273","consensus_level":"medium","plddt":80.232,"start":1152,"end":1273},{"cath_id":"1.25.40.10","chopping":"1345-1446","consensus_level":"medium","plddt":81.4595,"start":1345,"end":1446}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O60293","model_url":"https://alphafold.ebi.ac.uk/files/AF-O60293-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O60293-F1-predicted_aligned_error_v6.png","plddt_mean":58.0},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ZFC3H1","jax_strain_url":"https://www.jax.org/strain/search?query=ZFC3H1"},"sequence":{"accession":"O60293","fasta_url":"https://rest.uniprot.org/uniprotkb/O60293.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O60293/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O60293"}},"corpus_meta":[{"pmid":"27871484","id":"PMC_27871484","title":"Identification of a Nuclear Exosome Decay Pathway for Processed Transcripts.","date":"2016","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/27871484","citation_count":230,"is_preprint":false},{"pmid":"28733371","id":"PMC_28733371","title":"An Mtr4/ZFC3H1 complex facilitates turnover of unstable nuclear RNAs to prevent their cytoplasmic transport and global translational repression.","date":"2017","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/28733371","citation_count":113,"is_preprint":false},{"pmid":"29768216","id":"PMC_29768216","title":"The RNA Exosome Adaptor ZFC3H1 Functionally Competes with Nuclear Export Activity to Retain Target Transcripts.","date":"2018","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/29768216","citation_count":75,"is_preprint":false},{"pmid":"10543724","id":"PMC_10543724","title":"cSrc is a major cytosolic tyrosine kinase in vascular tissue.","date":"1999","source":"Canadian journal of physiology and 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ZFC3H1/PABPN1 and ZCCHC8/RBM7 contact hMTR4 in a mutually exclusive manner, establishing that NEXT and PAXT are distinct, competing hMTR4-adaptor complexes targeting transcripts of different maturation status.\",\n      \"method\": \"Protein co-immunoprecipitation, depletion/knockdown with RNA-seq readout, identification of mutual exclusivity by interaction assays\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP establishing mutually exclusive interactions, combined with KD phenotypes; independently replicated by subsequent studies\",\n      \"pmids\": [\"27871484\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"ZFC3H1 forms a distinct complex with MTR4 (separate from NEXT) that is required for nuclear surveillance of prematurely terminated RNAs (ptRNAs) and upstream antisense RNAs (uaRNAs). Knockdown of either Mtr4 or ZFC3H1 causes these lncRNAs to accumulate in the cytoplasm and associate with active ribosomes, leading to global repression of translation, establishing a role for the Mtr4/ZFC3H1 complex in preventing cytoplasmic transport and translational disruption.\",\n      \"method\": \"Complex purification/isolation, siRNA knockdown, cellular fractionation, polysome profiling, RNA immunoprecipitation\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — complex isolation plus KD with multiple orthogonal readouts (fractionation, polysome profiling), single lab\",\n      \"pmids\": [\"28733371\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"ZFC3H1 is required for the formation of distinct nuclear foci containing polyadenylated RNA when exosome function is abolished. In the absence of ZFC3H1, selected polyadenylated RNAs (coding and non-coding) are exported to the cytoplasm via the mRNA export factor AlyREF, establishing ZFC3H1 as a central nuclear pA+ RNA retention factor that counteracts nuclear export activity.\",\n      \"method\": \"Co-localization imaging (RNA FISH + immunofluorescence), siRNA knockdown, cellular fractionation, AlyREF epistasis experiments\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KD with specific phenotypic readout plus epistasis with AlyREF; multiple orthogonal methods (imaging, fractionation, genetic epistasis)\",\n      \"pmids\": [\"29768216\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"ZFC3H1 physically associates with the HIV-1 TAR region and represses HIV-1 transcriptional output and RNAPII recruitment to the LTR. Knockdown of ZFC3H1 increases HIV-1 expression and reactivates HIV-1 from latently infected PBMCs.\",\n      \"method\": \"ChIP (chromatin immunoprecipitation), siRNA knockdown, reporter assays, flow cytometry of GFP-positive J-Lat cells, ex vivo PBMC infection\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP plus functional KD readout in multiple cell systems; single lab\",\n      \"pmids\": [\"29554134\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"NRDE2 inhibits ZFC3H1 interaction with MTR4 by binding MTR4 via a conserved MTR4-interacting domain (MID), locking MTR4 in a closed conformation and thereby blocking exosome recruitment. Structural and biochemical data confirm that NRDE2 competes with ZFC3H1 for binding to key residues on MTR4.\",\n      \"method\": \"Structural analysis, biochemical interaction assays, mutagenesis of MTR4-interacting domain, Co-IP\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — structural and biochemical data with mutagenesis; negative regulatory interaction with ZFC3H1 mechanistically defined\",\n      \"pmids\": [\"30842217\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Knockout of ZFC3H1 in mouse embryonic stem cells impairs differentiation and leads to de-repression of PRC2-controlled developmental genes, paralleled by decreased PRC2 binding to chromatin, reduced H3K27 methylation, and compromised PRC2 complex stability due to elevated nonspecific RNA bound to PRC2 components.\",\n      \"method\": \"CRISPR/Cas9 knockout, ChIP-seq for H3K27me3 and PRC2, RNA-seq, RNA immunoprecipitation\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO with multiple orthogonal readouts (ChIP-seq, RNA-IP, differentiation assay) in a single lab\",\n      \"pmids\": [\"31722198\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Celastramycin binds ZFC3H1 as a direct binding partner (pulled down by celastramycin), and ZFC3H1 mediates celastramycin's effects on HIF-1α and NF-κB protein levels, reactive oxygen species, and mitochondrial metabolism in pulmonary artery smooth muscle cells.\",\n      \"method\": \"Affinity pull-down with celastramycin, siRNA knockdown, western blotting, functional cellular assays\",\n      \"journal\": \"Circulation research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single pull-down assay identifying binding; functional link inferred from KD, single lab\",\n      \"pmids\": [\"31195886\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"ZFC3H1 functions as the core dimer partner of MTR4 in the PAXT connection, and three additional proteins—ZC3H3, RBM26, and RBM27—are required for PAXT function. ZC3H3 interacts directly with the MTR4-ZFC3H1 dimer, and loss of any newly identified component results in accumulation of PAXT substrates.\",\n      \"method\": \"Proteomics of nuclear pA+-RNA bound proteins, Co-IP of MTR4-ZFC3H1 complexes, siRNA knockdown with RNA-seq readout\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — proteomic identification plus direct interaction assays and functional KD phenotypes; multiple orthogonal methods, single lab\",\n      \"pmids\": [\"31950173\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Upon exosome inactivation, ZFC3H1 forms nuclear condensates that prevent polyadenylated RNA trafficking to nuclear speckles, thereby blocking export competence. Systematic domain mapping revealed that ZFC3H1 uses distinct domains for condensation and for RNA degradation; condensation activity is required for nuclear RNA retention but not for RNA degradation.\",\n      \"method\": \"Live-cell imaging, domain deletion/mutation analysis, RNA FISH, siRNA knockdown, fluorescence microscopy of nuclear speckles\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — domain mapping with mutants and imaging; functional dissection of condensation vs. degradation, single lab\",\n      \"pmids\": [\"34530450\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"ZFC3H1 is required for the nuclear retention and degradation of intronic polyadenylated (IPA) transcripts that contain intact 5' splice site (5'SS) motifs. ZFC3H1 sequesters mRNAs with 5'SS motifs into nuclear speckles to prevent their nuclear export, functioning in the same pathway as U1-70K (a component of the U1 snRNP).\",\n      \"method\": \"High-throughput sequencing of cellular fractions, reporter mRNA assays, siRNA knockdown, nuclear speckle disruption experiments, epistasis between ZFC3H1 and U1-70K\",\n      \"journal\": \"RNA (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — fractionation-seq plus reporter assays plus genetic epistasis; multiple orthogonal methods in single lab\",\n      \"pmids\": [\"35351812\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Mutational analysis of ZFC3H1 uncovered a direct ARS2-ZFC3H1 interaction via acidic-rich short linear motifs that compete with ZC3H18 for a common ARS2 epitope. This reveals a separate PAXT branch targeting short adenylated RNAs and explains how ZC3H18 simultaneously promotes NEXT while antagonizing PAXT activity.\",\n      \"method\": \"Site-directed mutagenesis, Co-IP, competitive binding assays, RNA-seq after KD/KO\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mutagenesis plus binding competition plus functional readout; single lab\",\n      \"pmids\": [\"37889751\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"ZFC3H1 is required for PAXT recruitment to transcription start sites (TSSs) of hundreds of genes; loss of ZFC3H1 abolishes recruitment of all PAXT subunits including PAPγ to TSSs and concomitantly increases the abundance of PROMPTs at those sites. ZFC3H1, MTR4, and PAPγ are all implicated in polyadenylation of PROMPTs.\",\n      \"method\": \"ChIP-seq / genome-wide binding mapping of ZFC3H1, RBM27, and PAPγ; ZFC3H1 KO with RNA-seq; proteomics\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genome-wide ChIP-seq plus KO RNA-seq plus proteomics; multiple orthogonal methods, single lab\",\n      \"pmids\": [\"37875486\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"ZFC3H1 is co-transcriptionally loaded onto the first exon/intron of RNA precursors in a 'closed' conformation that blocks exosome recruitment. Upon RNA processing, short RNAs with fewer exons recruit transient PAXT components ZC3H3 and RBM26/27 to the 3' end, triggering ZFC3H1 'opening' and subsequent exosomal degradation, whereas longer RNAs with more exons are directed to nuclear export. This establishes a decoupled loading-and-activation mechanism for ZFC3H1 that pre-configures RNA fate.\",\n      \"method\": \"iCLIP/eCLIP mapping, domain mutant analysis, Co-IP, RNA-seq fractionation, nascent RNA analysis\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (iCLIP, domain mutants, fractionation) in a focused mechanistic study; single lab\",\n      \"pmids\": [\"39461342\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"YTHDC1 and YTHDC2 (YTH-domain m6A reader proteins) interact with ZFC3H1 and U1-70K, and are required for nuclear retention of mRNAs with intact 5'SS motifs. Disruption of m6A deposition inhibits nuclear retention of these transcripts and their accumulation in YTHDC1-enriched foci adjacent to nuclear speckles.\",\n      \"method\": \"Co-IP (ZFC3H1 with YTHDC1/2), siRNA knockdown, reporter mRNA assays, RNA FISH, m6A inhibition experiments\",\n      \"journal\": \"Life science alliance\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — Co-IP plus functional KD with reporter readout; single lab, single study\",\n      \"pmids\": [\"39626965\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"ZFC3H1 (also known as CCDC131/CSRC2) was identified as a direct binding protein of Celastramycin A by affinity pull-down screening. Knockdown of ZFC3H1 reduced TNFα-induced IL-8 expression, and reporter assays showed ZFC3H1 participates in transcriptional activation of IL-8. UV-irradiation experiments suggested ZFC3H1 may indirectly interact with ERCC1 in an activated DNA repair complex.\",\n      \"method\": \"Celastramycin A affinity pull-down screen, siRNA knockdown, IL-8 reporter assay, Co-IP suggestion\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Weak — affinity pull-down plus reporter assay; single lab, single study\",\n      \"pmids\": [\"25268596\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"ZFC3H1 participates in human telomerase RNA (hTR) biogenesis via pathways related to the polyadenylated RNA degradation mechanism, as determined by knockdown experiments examining hTR isoforms and localization.\",\n      \"method\": \"siRNA knockdown, RT-PCR analysis of hTR isoforms, cellular fractionation\",\n      \"journal\": \"Biomedicines\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — KD with RNA readout only; single lab, limited mechanistic detail in abstract\",\n      \"pmids\": [\"35740297\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"ZFC3H1 protein competes with lncRNA MSL3P1 for binding to CUL3 mRNA; MSL3P1 prevents ZFC3H1-mediated degradation and cytoplasmic export blockade of CUL3 mRNA by competitive binding, demonstrating ZFC3H1's role in targeting specific mRNAs for exosomal degradation and nuclear retention.\",\n      \"method\": \"RNA immunoprecipitation, siRNA knockdown of ZFC3H1, RNA pull-down competition assays, cellular fractionation\",\n      \"journal\": \"Molecular cancer research : MCR\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — competitive pull-down and KD; single lab, partial mechanistic follow-up only\",\n      \"pmids\": [\"38718076\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ZFC3H1 is a core component of the poly(A) exosome targeting (PAXT) connection that, together with MTR4, forms the central dimer of a nuclear RNA surveillance complex; it is co-transcriptionally loaded onto pre-RNAs in a closed conformation that blocks exosome recruitment, and is activated by recruitment of transient components ZC3H3 and RBM26/27 to the 3' ends of short adenylated RNAs, thereby triggering exosomal degradation, while for longer RNAs ZFC3H1 allows switching to nuclear export—and when degradation is impaired, ZFC3H1 forms nuclear condensates that retain polyadenylated RNAs away from speckles and the export machinery.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ZFC3H1 is a central scaffold of the poly(A) tail exosome targeting (PAXT) connection, a nuclear RNA surveillance system that routes polyadenylated transcripts toward exosomal degradation [#0]. It forms a core dimer with the RNA helicase MTR4 and bridges MTR4 to the nuclear poly(A)-binding protein PABPN1; this PAXT engagement of MTR4 is mutually exclusive with the NEXT adaptor module (ZCCHC8/RBM7), so that NEXT and PAXT compete for MTR4 to target transcripts of differing maturation status [#0]. The MTR4-ZFC3H1 dimer additionally recruits transient subunits ZC3H3, RBM26 and RBM27, and loss of any component stabilizes PAXT substrates [#7]. Mechanistically, ZFC3H1 is loaded co-transcriptionally onto the first exon/intron of RNA precursors in a 'closed' conformation that blocks exosome recruitment; short, few-exon RNAs recruit ZC3H3 and RBM26/27 to the 3' end to trigger ZFC3H1 'opening' and degradation, whereas longer transcripts are diverted to nuclear export, establishing a decoupled loading-and-activation switch that pre-configures RNA fate [#12]. The MTR4-ZFC3H1 interaction is negatively regulated by NRDE2, which binds MTR4 via a conserved MTR4-interacting domain and competes with ZFC3H1 for key MTR4 residues to lock the helicase closed [#4], and a distinct PAXT branch targeting short adenylated RNAs is engaged through a direct ARS2-ZFC3H1 interaction that competes with ZC3H18 [#10]. Beyond degradation, ZFC3H1 acts as a nuclear retention factor: when exosome function is lost it forms nuclear condensates that retain polyadenylated RNAs away from nuclear speckles and the AlyREF export machinery, with condensation and degradation served by separable domains [#2, #8]. It enforces nuclear retention of intronic polyadenylated transcripts bearing intact 5' splice site motifs in the same pathway as U1-70K, sequestering them into nuclear speckles [#9], and engages the m6A readers YTHDC1/YTHDC2 to retain 5'SS-containing mRNAs [#13]. PAXT is recruited by ZFC3H1 to transcription start sites genome-wide, where its loss abolishes recruitment of PAP-gamma and other subunits and increases PROMPT abundance [#11]. Through this surveillance activity ZFC3H1 also supports embryonic stem cell differentiation, preventing nonspecific RNA from compromising PRC2 stability and chromatin occupancy [#5], and restrains aberrant cytoplasmic accumulation and translation of unprocessed lncRNAs [#1].\",\n  \"teleology\": [\n    {\n      \"year\": 2016,\n      \"claim\": \"Established ZFC3H1 as the adaptor defining a distinct MTR4-dependent surveillance pathway, answering how polyadenylated transcripts are selectively delivered to the nuclear exosome.\",\n      \"evidence\": \"Reciprocal Co-IP and depletion with RNA-seq in human cells, defining PAXT versus NEXT mutual exclusivity on MTR4\",\n      \"pmids\": [\"27871484\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve the structural basis of the MTR4-ZFC3H1 contact\", \"Substrate selectivity rules between NEXT and PAXT not defined\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Showed the MTR4/ZFC3H1 complex prevents cytoplasmic escape of prematurely terminated and antisense RNAs, linking failed nuclear surveillance to translational disruption.\",\n      \"evidence\": \"Complex purification, siRNA knockdown, fractionation, polysome profiling and RIP in human cells\",\n      \"pmids\": [\"28733371\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism distinguishing retention from degradation not separated\", \"Did not define how transcripts escape to the cytoplasm\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Defined ZFC3H1 as a nuclear pA+ RNA retention factor that counteracts AlyREF-mediated export, separating retention from degradation as a function.\",\n      \"evidence\": \"RNA-FISH/IF co-localization, knockdown, fractionation and AlyREF epistasis in human cells\",\n      \"pmids\": [\"29768216\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physical basis of foci formation not yet determined\", \"Selectivity of which transcripts are retained unresolved\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Resolved a negative regulatory switch: NRDE2 competes with ZFC3H1 for MTR4 to lock the helicase closed and block exosome recruitment.\",\n      \"evidence\": \"Structural and biochemical interaction assays with MTR4-interacting-domain mutagenesis and Co-IP\",\n      \"pmids\": [\"30842217\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cellular conditions governing NRDE2-versus-ZFC3H1 occupancy of MTR4 not defined\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Connected ZFC3H1 surveillance to developmental gene control, showing its loss destabilizes PRC2 via nonspecific RNA and impairs ES cell differentiation.\",\n      \"evidence\": \"CRISPR knockout in mouse ES cells with H3K27me3/PRC2 ChIP-seq, RNA-seq and RNA-IP\",\n      \"pmids\": [\"31722198\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct versus indirect effect on PRC2 not fully separated\", \"Which RNAs accumulate on PRC2 not identified\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Expanded the PAXT subunit roster, identifying ZC3H3/RBM26/RBM27 as components recruited to the MTR4-ZFC3H1 dimer required for substrate turnover.\",\n      \"evidence\": \"Nuclear pA+-RNA proteomics, Co-IP of MTR4-ZFC3H1, and knockdown RNA-seq in human cells\",\n      \"pmids\": [\"31950173\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry and assembly order of transient subunits unresolved\", \"Whether subunits are constitutive or substrate-induced not settled at the time\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Dissected ZFC3H1 into separable domains for condensation versus degradation, showing condensate formation drives nuclear RNA retention independent of degradation.\",\n      \"evidence\": \"Live-cell imaging, domain deletion/mutation, RNA-FISH and speckle microscopy under exosome inactivation\",\n      \"pmids\": [\"34530450\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Biophysical determinants of condensation not characterized\", \"Single lab; physiological trigger for condensation in vivo unclear\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Showed ZFC3H1 enforces nuclear retention of intronic polyadenylated transcripts with intact 5'SS motifs, placing it in a U1-70K-coupled surveillance pathway.\",\n      \"evidence\": \"Fractionation-seq, reporter mRNA assays, speckle disruption and ZFC3H1/U1-70K epistasis\",\n      \"pmids\": [\"35351812\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct ZFC3H1-U1 snRNP contact not demonstrated\", \"How 5'SS recognition feeds into retention not molecularly defined\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Defined an ARS2-ZFC3H1 interaction branch for short adenylated RNAs, explaining how ZC3H18 partitions activity between NEXT and PAXT.\",\n      \"evidence\": \"Mutagenesis of acidic short linear motifs, competitive binding assays and KD/KO RNA-seq\",\n      \"pmids\": [\"37889751\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural detail of the ARS2 epitope contact not resolved\", \"In vivo balance of ZC3H18 versus ZFC3H1 for ARS2 not quantified\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Mapped ZFC3H1-dependent PAXT recruitment to transcription start sites genome-wide, linking PAXT to PROMPT polyadenylation and turnover.\",\n      \"evidence\": \"ChIP-seq of ZFC3H1/RBM27/PAP-gamma, ZFC3H1 KO RNA-seq and proteomics\",\n      \"pmids\": [\"37875486\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How ZFC3H1 is targeted to specific TSSs unresolved\", \"Role of PAP-gamma polyadenylation step mechanistically incomplete\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Resolved a decoupled loading-and-activation model: co-transcriptional loading in a closed state followed by 3'-end-triggered opening that pre-configures degradation versus export.\",\n      \"evidence\": \"iCLIP/eCLIP, domain mutants, Co-IP, fractionation and nascent RNA analysis\",\n      \"pmids\": [\"39461342\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Exact conformational change accompanying opening not structurally defined\", \"Counting mechanism for exon number not elucidated\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Connected ZFC3H1 retention to m6A reading, showing YTHDC1/2 partner with ZFC3H1 and U1-70K to retain 5'SS-containing mRNAs.\",\n      \"evidence\": \"Co-IP, knockdown, reporter assays, RNA-FISH and m6A inhibition in human cells\",\n      \"pmids\": [\"39626965\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct versus indirect ZFC3H1-YTHDC1/2 contact not separated\", \"Single study; physiological scope of m6A-dependent retention unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How ZFC3H1 substrate-specificity, condensation, and chromatin-proximal recruitment are integrated into a single regulatory logic that decides RNA fate remains unresolved.\",\n      \"evidence\": \"No single study reconciles co-transcriptional loading, conformational switching, condensate retention, and TSS recruitment into one structural/biochemical model\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No high-resolution structure of the assembled PAXT-ZFC3H1 complex\", \"Determinants distinguishing degraded versus exported transcripts only partially defined\", \"Reported roles in HIV-1 latency, PRC2/differentiation, and disease-associated mRNAs not unified mechanistically\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [5, 9, 16]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 7]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [4, 10]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 2, 8]},\n      {\"term_id\": \"GO:0005654\", \"supporting_discovery_ids\": [2, 8, 9]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [0, 1, 7, 12]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [2, 9, 13]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [11]}\n    ],\n    \"complexes\": [\n      \"PAXT connection\"\n    ],\n    \"partners\": [\n      \"MTR4\",\n      \"PABPN1\",\n      \"ZC3H3\",\n      \"RBM26\",\n      \"RBM27\",\n      \"NRDE2\",\n      \"ARS2\",\n      \"YTHDC1\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"tie","faith_supported":7,"faith_total":9,"faith_pct":77.77777777777777}}