{"gene":"NUDT21","run_date":"2026-06-10T05:19:52","timeline":{"discoveries":[{"year":2010,"finding":"Crystal structures of human CFIm25 homodimer in complex with UGUAAA and UUGUAU RNA sequences revealed that CFIm25 is the first Nudix protein to bind RNA in a sequence-specific manner. The UGUA sequence contributes binding specificity through an intramolecular G:A Watson-Crick/sugar-edge base interaction. Mutational data suggested a mechanism for simultaneous recognition of two UGUA elements. CFIm25 has no detectable hydrolase activity despite its Nudix fold. The signaling molecule Ap4A (diadenosine tetraphosphate) and RNA bind CFIm25 in a mutually exclusive manner, suggesting small-molecule regulation of mRNA 3' processing.","method":"Crystal structure determination, mutational analysis, in vitro binding assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structures with functional mutational validation, multiple orthogonal methods in one rigorous study","pmids":["20479262"],"is_preprint":false},{"year":2014,"finding":"CFIm25 (NUDT21) acts as a broad repressor of proximal poly(A) site usage. CFIm25 knockdown causes 3' UTR shortening of at least 1,450 genes (11% of expressed mRNAs), increases cell proliferation, and upregulates oncogenes including cyclin D1. Downregulation of CFIm25 in glioblastoma cells enhances tumorigenic properties and increases tumor size; overexpression reduces these properties and inhibits tumor growth.","method":"RNA-seq with regression model for APA analysis, CFIm25 siRNA knockdown, glioblastoma xenograft tumor assays","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — genome-wide APA analysis, multiple cancer cell lines, in vivo xenograft models, replicated across multiple approaches","pmids":["24814343"],"is_preprint":false},{"year":2015,"finding":"NUDT21 regulates MeCP2 protein quantity via alternative polyadenylation. Elevated NUDT21 increases usage of the distal polyadenylation site in the MECP2 3' UTR, resulting in enrichment of inefficiently translated long mRNA isoforms and reduced MeCP2 protein. siRNA-mediated knockdown of NUDT21 in duplication patient lymphoblasts restores MeCP2 to normal levels.","method":"Patient-derived lymphoblastoid cell analysis, MECP2 mRNA and protein abundance measurement, siRNA knockdown","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 / Strong — patient-derived cells, multiple CNV cases, functional rescue experiment with siRNA normalization","pmids":["26312503"],"is_preprint":false},{"year":2016,"finding":"CFIm25 depletion causes a shift to proximal poly(A) site usage within the KGA isoform of glutaminase (GLS) 3' UTR and alters splicing to exclude the GAC 3' UTR. The apoptosis induced by downregulation of the GAC isoform can be alleviated through concurrent reduction in CFIm25 expression, linking CFIm25 to glutamine metabolism in cancer cells.","method":"CFIm25 siRNA depletion, RT-PCR for isoform analysis, apoptosis assays, concurrent knockdown rescue experiments","journal":"RNA (New York, N.Y.)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional rescue epistasis, multiple knockdown approaches, single lab","pmids":["27095025"],"is_preprint":false},{"year":2017,"finding":"Nudt21 directs differential polyadenylation of over 1,500 transcripts during cellular reprogramming to pluripotency, with the resulting protein-level changes strongly enriched for chromatin regulators. Suppression of these chromatin regulator proteins neutralizes the effect of Nudt21 during reprogramming, establishing a direct link between alternative polyadenylation and chromatin signaling in cell fate control.","method":"Transcription-factor-induced reprogramming screen, RNA-seq, proteomic analysis, epistasis via chromatin regulator knockdown","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — functional screening assay, genome-wide APA profiling, proteomic validation, epistasis experiments across multiple cell fate transitions","pmids":["29249356"],"is_preprint":false},{"year":2017,"finding":"NUDT21 co-localizes with AGO2 in P/GW bodies in normal liver cells, and this co-localization is diminished in cancer cells. NUDT21 elongates the 3' UTR of mRNAs and enhances the efficiency of miRNA-mediated gene silencing by increasing AGO2-mRNA binding efficiency.","method":"Co-immunoprecipitation, immunofluorescence co-localization, AGO2-mRNA binding assays, NUDT21 knockdown/overexpression","journal":"Cancer letters","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-localization and co-IP with functional follow-up, single lab, two orthogonal methods","pmids":["28964783"],"is_preprint":false},{"year":2018,"finding":"NUDT21 knockdown in K562 cells inhibits proliferation and promotes apoptosis through the MAPK/ERK pathway, involving modulation of PTEN and downstream ERK1/2 signaling.","method":"Lentiviral NUDT21 knockdown in K562 cells, RNA microarray, intracellular signaling array, western blotting, flow cytometry","journal":"Cancer management and research","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, signaling array without direct mechanistic validation of the NUDT21-PTEN-ERK connection","pmids":["30349365"],"is_preprint":false},{"year":2018,"finding":"NUDT21 knockdown increases proximal polyadenylation site usage in the 3' UTRs of PSMB2 and CXXC5, resulting in marked increases in their protein expression, which promote HCC cell proliferation and invasion.","method":"Global APA site profiling, NUDT21 knockdown/overexpression, western blotting for PSMB2 and CXXC5, functional rescue knockdown of PSMB2 and CXXC5","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — global APA profiling plus specific target validation, functional epistasis via individual target knockdown, single lab","pmids":["29780166"],"is_preprint":false},{"year":2018,"finding":"CFIm25 inhibits HCC cell migration and invasion by blocking the p38 and JNK/c-Jun signaling pathways, and disrupts epithelial-mesenchymal transition by increasing E-cadherin. CFIm25 knockdown increases transcriptional activity of AP-1.","method":"CFIm25 knockdown/overexpression, in vitro invasion and migration assays, in vivo metastasis models, western blotting for EMT markers and MAPK pathway components, AP-1 reporter assay","journal":"Oncotarget","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo and in vitro functional studies, pathway analysis by western blot and reporter assay, single lab","pmids":["29545935"],"is_preprint":false},{"year":2019,"finding":"NUDT21 promotes circRNA cyclization by recognizing UGUA sequences, and NUDT21 knockdown disrupts circRNA-miRNA-mRNA ceRNA pathways in hepatocellular carcinoma. Overexpression of downregulated circRNAs assists NUDT21-mediated tumor suppression.","method":"NUDT21 knockdown/overexpression, circRNA expression profiling, UGUA motif mutagenesis, ceRNA pathway analysis, functional rescue with circRNA overexpression","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional rescue epistasis, motif mutagenesis, single lab with multiple approaches","pmids":["31570791"],"is_preprint":false},{"year":2019,"finding":"NUDT21 modulates the expression of ANXA2 and LIMK2 via alternative polyadenylation in bladder cancer, and these genes act in the Wnt/β-catenin and NF-κB signaling pathways.","method":"Global APA site profiling, NUDT21 knockdown/overexpression, TOP/FOP flash reporter assay (Wnt/β-catenin), western blotting","journal":"Theranostics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — global APA profiling with specific target validation and pathway reporter assay, single lab","pmids":["31695759"],"is_preprint":false},{"year":2020,"finding":"CFIm25 depletion promotes 3' UTR shortening of TGFβ-regulated fibrotic genes and enhances their protein expression in normal dermal fibroblasts. Fibroblast-specific CFIm25 deletion in mice exaggerates bleomycin-induced skin fibrosis, and CFIm25 restoration attenuates this fibrosis.","method":"CFIm25 knockdown in fibroblasts, APA profiling, fibroblast-specific conditional knockout mice, bleomycin-induced fibrosis model","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional knockout mouse model, APA profiling, in vivo rescue, and cell-level mechanistic validation across multiple approaches","pmids":["31757866"],"is_preprint":false},{"year":2020,"finding":"Nudt21+/- mice with 30% reduced CFIm25 protein show learning deficits, cortical hyperexcitability, and misregulated APA in hippocampi. Partial NUDT21 inhibition (30% CFIm25 reduction) in human stem cell-derived neurons induces APA and protein level misregulation in hundreds of genes, several of which cause intellectual disability when mutated.","method":"Nudt21+/- mouse model, behavioral testing (learning), electrophysiology (cortical hyperexcitability), APA profiling in hippocampi, human stem cell-derived neuron experiments","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo mouse model, human stem cell-derived neurons, APA genome-wide profiling, multiple phenotypic readouts","pmids":["32319885"],"is_preprint":false},{"year":2020,"finding":"NUDT21 co-localizes with EZH2 in human trophoblast cells and binds to EZH2 mRNA. NUDT21 elongates 3' UTRs, exposing additional miRNA binding sites (including miR138 and miR363), thereby enhancing miRNA-mediated silencing of EZH2.","method":"RNA immunoprecipitation (RIP), immunofluorescence co-localization, NUDT21 loss-of-function assays, 3' UTR length analysis","journal":"Journal of cellular and molecular medicine","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, RIP without strong mechanistic follow-up, binding to mRNA rather than protein","pmids":["30883033"],"is_preprint":false},{"year":2020,"finding":"NUDT21 physically associates with IPS-1 (mitochondrial antiviral adaptor) and mediates IPS-1 localization to stress granules in response to poly(I:C) transfection. A fraction of NUDT21 localizes to mitochondria in resting cells and moves to stress granules upon viral dsRNA stimulation. NUDT21 is required for efficient type I IFN induction in response to viral infection.","method":"Co-immunoprecipitation, immunofluorescence/subcellular fractionation, poly(I:C) stimulation, NUDT21 knockdown in HeLa and RAW264.7 cells, IFN induction assays","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP, localization experiments, functional knockdown with IFN readout, single lab with multiple orthogonal methods","pmids":["33219146"],"is_preprint":false},{"year":2020,"finding":"HIF-1α-mediated downregulation of NUDT21 alters expression patterns of the two GLS1 isoforms GAC and KGA in SCLC under hypoxia, linking hypoxic tumor environments to aberrant glutamine metabolism.","method":"NUDT21 shRNA transduction, hypoxia treatment, HIF-1α inhibition, isoform expression analysis by RT-PCR/western blot","journal":"Biochemical and biophysical research communications","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, indirect mechanism (HIF-1α → NUDT21 → GLS1 isoforms), no direct reconstitution of HIF-1α/NUDT21 interaction","pmids":["32228887"],"is_preprint":false},{"year":2020,"finding":"NUDT21 directly interacted with CPSF6 as detected by mass spectrometry and western blotting, and negatively regulated CPSF6 expression in breast cancer cells. Knockdown of CPSF6 reversed NUDT21 expression-induced cancer cell migration and invasion.","method":"Mass spectrometry, western blotting, co-immunoprecipitation, CPSF6 knockdown rescue experiments","journal":"Cancer management and research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mass spectrometry plus western blot for interaction, functional epistasis via CPSF6 knockdown rescue, single lab","pmids":["32431549"],"is_preprint":false},{"year":2021,"finding":"NUDT21 gene editing in human embryonic stem cells impairs differentiation potential and increases proliferation, but unexpectedly did not significantly affect cellular mRNA 3' processing efficiency or APA profile. Instead, CFIm25 perturbation affects RNA polymerase II occupancy at the body of transcribed genes and promotes expression of transcripts associated with proliferation/differentiation including rex1.","method":"CRISPR/Cas9 editing of CFIm25 in hESCs, RNA-seq APA profiling, Pol II ChIP-seq, proliferation and differentiation assays","journal":"RNA biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — CRISPR-based editing, Pol II ChIP-seq, APA profiling with negative APA result, single lab with multiple methods","pmids":["35491945"],"is_preprint":false},{"year":2022,"finding":"FXR1 interacts with CFIm25 (NUDT21) and CFIm68, forming a novel 3' processing machinery for sequence-specific poly(A) site recognition. This FXR1-CFIm25/CFIm68 complex affects 3' processing of TRAF1 mRNA, leading to its nuclear stabilization.","method":"Co-immunoprecipitation, mass spectrometry, 3' end processing assays, TRAF1 mRNA stability analysis","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP, mass spectrometry identification, functional mRNA processing readout, single lab","pmids":["35194031"],"is_preprint":false},{"year":2023,"finding":"Poly(A)-binding protein nuclear 1 (PABPN1) aggregates sequester CFIm25 in an mRNA-dependent manner, impairing CFIm25 function in alternative polyadenylation. Ala expansion drives PABPN1 aggregation from nuclear speckles, and poly(A) nucleotide is essential for early-stage condensation.","method":"Biochemical phase transition assays, molecular cell biology, immunofluorescence, APA profiling in PABPN1 aggregate conditions","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — biochemical reconstitution of aggregation, functional APA readout upon sequestration, single lab with multiple methods","pmids":["37422193"],"is_preprint":false},{"year":2023,"finding":"LINC00921 lncRNA controls NUDT21 protein stability by facilitating binding of NUDT21 with the E3 ubiquitin ligase TRIP12, leading to NUDT21 destabilization and subsequent 3' UTR shortening of MED23 mRNA via APA.","method":"Co-immunoprecipitation, ubiquitination assays, APA profiling, NUDT21 stability assays with TRIP12 knockdown/overexpression","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP evidence for NUDT21-TRIP12 interaction, functional APA readout, stability assays, single lab","pmids":["37999979"],"is_preprint":false},{"year":2023,"finding":"NUDT21 loss (induced by DNMT3B-mediated promoter methylation) causes 3' UTR shortening of MORC2 mRNA, stabilizing MORC2 and enhancing its oncogenic activity in kidney renal clear cell carcinoma. MORC2 subsequently recruits DNMT3A to hypermethylate the DAPK1 promoter, silencing this tumor suppressor.","method":"APA profiling, NUDT21 promoter methylation analysis, MORC2 3'UTR reporter assay, DNMT3A ChIP, DAPK1 promoter methylation assay","journal":"JCI insight","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — APA profiling, epigenetic mechanistic follow-up via ChIP, antisense oligonucleotide rescue in vivo, single lab","pmids":["37737260"],"is_preprint":false},{"year":2023,"finding":"NUDT21 knockdown in glioma cells causes 3' UTR shortening of LAMC1, removing miR-124/506 binding sites and relieving miRNA repression, resulting in increased LAMC1 protein and enhanced glioma cell migration. Co-depletion of LAMC1 with NUDT21 abolishes the NUDT21-knockdown-induced migration phenotype.","method":"PAC-seq APA profiling, qRT-PCR, western blotting for LAMC1, miRNA binding site analysis, co-depletion epistasis experiment, cell migration assays","journal":"Journal of neuro-oncology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genome-wide APA profiling, specific target validation, epistasis by co-depletion, single lab","pmids":["37389756"],"is_preprint":false},{"year":2023,"finding":"HIV-1 nuclear entry triggers translocation of CPSF6 from paraspeckles into nuclear speckles, forming biomolecular condensates. CPSF5 (NUDT21), but not CPSF7, co-localizes with CPSF6 in these condensates. Formation of CPSF6/CPSF5 condensates does not require HIV-1 integration or reverse transcription, but is required for productive wild-type HIV-1 infection (not for capsid mutants N74D/A77V that do not form condensates).","method":"Immunofluorescence, osmotic stress/1,6-hexanediol condensate disruption assays, HIV-1 infection with capsid mutants, fluorescence microscopy in T cells and primary macrophages","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple condensate disruption methods, capsid mutant controls, primary cell validation, single lab","pmids":["37414787"],"is_preprint":false},{"year":2024,"finding":"TRIM65 E3 ligase interacts with NUDT21 (identified by yeast-hybrid screen) and induces K48-linked polyubiquitination of NUDT21 at lysine 56, leading to proteasomal degradation. NUDT21 degradation inhibits TGF-β1-mediated SMAD and ERK1/2 signaling and alters 3'UTR-APA of pro-fibrotic genes (Col1a1, Fn-1, Tgfbr1, Wnt5a, Fzd2).","method":"Yeast-hybrid screen, co-immunoprecipitation, ubiquitination assay with K48-linkage specificity, proteasome inhibitor treatment, APA profiling, AAV9-mediated NUDT21 knockdown in vivo","journal":"Cell death and differentiation","confidence":"High","confidence_rationale":"Tier 1 / Strong — ubiquitination site mapped (K56), linkage specificity determined (K48), yeast-hybrid + co-IP for interaction, in vivo AAV model, multiple orthogonal methods","pmids":["38951701"],"is_preprint":false},{"year":2024,"finding":"PRMT7-mediated mono-methylation of NUDT21 (at K23) induces a shift in 3'UTR usage, reducing oncogenicity in prostate cancer. Un-methylated NUDT21 promotes cancer growth and cuproptosis insensitivity by suppressing docosahexaenoic acid (DHA) biosynthesis. HDAC2 serves as the eraser of NUDT21 K23 mono-methylation.","method":"Mono-methylation monoclonal antibody generation, conditional knockin transgenic mouse model, transcriptomic and metabolomic analyses, loss-of-function and gain-of-function assays, drug-resistant cell lines","journal":"Drug resistance updates","confidence":"High","confidence_rationale":"Tier 1 / Strong — specific methylation site mapped, writer (PRMT7) and eraser (HDAC2) identified, transgenic mouse model, multiple orthogonal approaches including metabolomics","pmids":["39208673"],"is_preprint":false},{"year":2025,"finding":"L-lactate-induced lactylation of NUDT21 at K23 (catalyzed by AARS1 as the 'writer' and removed by HDAC2 as the 'eraser') enhances NUDT21 interaction with CPSF6, facilitating CFIm complex formation and inducing 3'UTR lengthening of FDX1. This extended FDX1 3'UTR attenuates FDX1 protein output, conferring resistance to cuproptosis in esophageal squamous cell carcinoma.","method":"Lactylation site mapping (K23), co-immunoprecipitation for NUDT21-CPSF6 interaction, APA profiling, FDX1 3'UTR reporter assay, AARS1 and HDAC2 functional validation, in vivo tumor models","journal":"Cell discovery","confidence":"High","confidence_rationale":"Tier 1 / Strong — PTM site mapped, writer/eraser identified, protein interaction consequence demonstrated, in vivo functional validation, multiple orthogonal methods","pmids":["40425546"],"is_preprint":false},{"year":2025,"finding":"IGF2BP3 interacts with NUDT21 (recognizing m6A-modified site in intron 32 of SPTBN1), recruiting NUDT21 to promote usage of the SPTBN1 proximal polyadenylation site and increasing generation of short SPTBN1 transcripts in ovarian cancer cells.","method":"Co-immunoprecipitation, m6A site mapping, APA site profiling, SPTBN1 isoform functional assays","journal":"Communications biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP for interaction, m6A modification site mapped, APA functional consequence demonstrated, single lab","pmids":["40301554"],"is_preprint":false},{"year":2025,"finding":"N-acetyltransferase 10 (NAT10) catalyzes ac4C modification at nucleotide 3311 of MVC viral RNA, which promotes specific binding of CPSF5 (NUDT21) to the target region. NP1 recruits CPSF5 to MVC RNAs in an ac4C-dependent manner, and this CPSF5 binding is required for precise alternative viral RNA processing without altering RNA stability.","method":"acRIP-seq, RedaC:T-seq for ac4C site mapping, in vitro binding assays, NP1/CPSF5 co-IP, viral RNA processing assays with ac4C mutants","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — in vitro binding assays with modification site mapped, co-IP, functional RNA processing readout, single lab","pmids":["40167508"],"is_preprint":false},{"year":2025,"finding":"PCBP1 suppresses CFIm25 (NUDT21) translation in monocytes by binding to its long 3'UTR. During monocyte-to-macrophage differentiation, alternative polyadenylation generates a shorter CFIm25 3'UTR lacking PCBP1 binding sites, releasing translational suppression and increasing CFIm25 protein. PCBP1 knockdown increases CFIm25 protein and induces macrophage differentiation markers without stimulation.","method":"RNA immunoprecipitation (PCBP1-long 3'UTR), ribosome association analysis, APA analysis during differentiation, PCBP1 knockdown experiments","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — RIP confirmation, ribosome association, functional PCBP1 knockdown, mechanistic link between APA and translation, single lab","pmids":["41830116"],"is_preprint":false},{"year":2025,"finding":"CFIm25 (NUDT21) promotes macrophage differentiation by inducing APA-mediated 3'UTR shortening of TAB2 and TBL1XR1 mRNAs (positive NF-κB regulators), increasing their protein levels and activating NF-κB signaling. CFIm25 overexpression elevates NF-κB-p65 phosphorylation and increases expression of NF-κB targets. Knockdown of TAB2 and TBL1XR1 in CFIm25-overexpressing cells attenuates these effects.","method":"CFIm25 overexpression/knockdown in monocytic cell lines, 3' end-focused sequencing (APA), western blotting, NF-κB chemical inhibition, TAB2/TBL1XR1 knockdown epistasis","journal":"Cell communication and signaling","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — APA profiling, epistasis via target knockdown, multiple functional readouts, single lab","pmids":["40022203"],"is_preprint":false},{"year":2025,"finding":"CFIm25 promotes proximal polyadenylation of AKT2 mRNA, generating shorter transcripts with enhanced stability and translational efficiency that increase Akt2 protein levels and support M1 macrophage polarization via NF-κB signaling. Blocking the proximal AKT2 poly(A) site with an antisense oligonucleotide reduces Akt2 expression and M1 traits.","method":"CFIm25 overexpression/knockdown, APA site analysis of AKT2, ASO blocking of proximal poly(A) site, Akt2 protein and mRNA stability analysis, nitric oxide/CD80/cytokine assays for macrophage polarization","journal":"iScience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — specific poly(A) site manipulation via ASO, protein level consequences demonstrated, functional polarization readouts, single lab","pmids":["42111214"],"is_preprint":false},{"year":2026,"finding":"NUDT21 promotes distal poly(A) site usage of UBE2D3 oncogenic transcripts in T-ALL, generating long 3'UTR isoforms with enhanced mRNA stability and increased protein expression. NUDT21 also localizes to transcriptionally active promoters and interacts with lineage-specific transcription factors MYB, RUNX1, and GATA3 to facilitate MYC transcription. Pharmacological targeting with ouabain octahydrate degrades NUDT21 protein and suppresses UBE2D3 and MYC.","method":"Multi-omics analysis, APA profiling, ChIP/chromatin localization, co-IP with transcription factors, pharmacological NUDT21 degradation, T-ALL functional assays","journal":"Advanced science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multi-omics, co-IP for TF interactions, chromatin localization, pharmacological validation, single lab","pmids":["41926643"],"is_preprint":false},{"year":2026,"finding":"Moderate Nudt21 suppression causes maturation arrest of stem cells due to 3'UTR-shortening of differentiation-associated mRNAs that escape miRNA regulation and perturb ceRNA networks. Complete Nudt21 suppression additionally shortens 3'UTRs of mRNAs encoding nuclear pore complex subunits, leading to complex destabilization, proteotoxic stress, DNA damage, and cell cycle arrest. Deletion of alternative 3'UTRs of individual nucleoporins recapitulates defects of Nudt21 loss, and co-translational assembly of dozens of protein complexes is impaired in Nudt21-deficient cells.","method":"Graded Nudt21 knockdown, APA profiling, nuclear pore complex stability assays, proteotoxic stress markers, individual nucleoporin 3'UTR deletion by CRISPR, ribosome profiling/co-translational assembly analysis","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct CRISPR deletion of individual 3'UTRs recapitulating Nudt21 phenotype, co-translational assembly assays, multiple graded knockdown conditions, multiple orthogonal methods","pmids":["41580420"],"is_preprint":false},{"year":2024,"finding":"NUDT21 promotes usage of the proximal polyadenylation site on MZT1 mRNA by binding to the UGUA element located upstream of the proximal PAS in pancreatic cancer cells.","method":"APA profiling, UGUA element analysis, NUDT21 binding site mapping, functional studies with proximal PAS usage","journal":"iScience","confidence":"Low","confidence_rationale":"Tier 3 / Weak — binding inferred from APA profiling and UGUA motif analysis without direct protein-RNA interaction assay, single lab","pmids":["38303721"],"is_preprint":false},{"year":2024,"finding":"NUDT21 mediates APA of LOXL2 3'UTR, thereby modulating LOXL2 expression and ECM protein cross-linking in silica-induced pulmonary fibrosis.","method":"NUDT21 modulation, APA analysis of LOXL2 3'UTR, siRNA-loaded liposomes for in vivo LOXL2 knockdown","journal":"Ecotoxicology and environmental safety","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, indirect evidence for NUDT21-LOXL2 APA without reconstitution","pmids":["39700768"],"is_preprint":false},{"year":2025,"finding":"Mycobacterium tuberculosis disrupts the interaction between NUDT21 and CPSF6, impairing NUDT21's ability to bind UGUA motifs in the FTH1 3'UTR. This shifts polyadenylation toward longer FTH1 isoforms with enhanced protein synthesis, facilitating bacterial survival. Silencing NUDT21 reduces macrophage bactericidal activity against Mtb.","method":"Co-immunoprecipitation (NUDT21-CPSF6 interaction), APA profiling of FTH1, NUDT21 knockdown, intracellular Mtb survival assays","journal":"Frontiers in cellular and infection microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP for disrupted NUDT21-CPSF6 interaction, APA profiling, functional infection assay, single lab","pmids":["40384984"],"is_preprint":false},{"year":2025,"finding":"miR-23a, miR-222, and miR-323a directly regulate NUDT21 mRNA levels in mantle cell lymphoma cells. The NUDT21 pre-mRNA undergoes alternative polyadenylation within the same terminal exon generating three different sized mRNAs with different 3'UTR lengths, each using a different canonical polyadenylation signal (AAUAAA). The different 3'UTR lengths affect NUDT21's own evasion of miRNA regulation.","method":"miRNA mimic and inhibitor experiments, 3'UTR luciferase reporter assays, mRNA stability measurements, APA isoform characterization","journal":"FASEB journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — miRNA mimic/inhibitor with functional readout, APA isoform characterization, luciferase reporter validation, single lab","pmids":["39812508"],"is_preprint":false}],"current_model":"NUDT21 (CFIm25/CPSF5) is the 25 kDa subunit of the Cleavage Factor Im (CFIm) complex that acts as a master regulator of alternative polyadenylation (APA): it binds UGUA motifs on pre-mRNAs via its Nudix fold (without hydrolase activity) to stimulate distal poly(A) site usage, thereby lengthening 3'UTRs and allowing miRNA-mediated gene silencing; its depletion globally shifts polyadenylation to proximal sites, shortening 3'UTRs and upregulating proliferative and oncogenic transcripts. NUDT21's activity and stability are controlled by post-translational modifications including K48-linked ubiquitination by TRIM65 (degradation), PRMT7-mediated mono-methylation at K23 (reduces oncogenicity), and AARS1-catalyzed lactylation at K23 (enhances CPSF6 interaction and complex assembly). Beyond canonical 3' processing, NUDT21 also links mitochondrial antiviral signaling (IPS-1) to stress granules, participates in HIV-1-induced nuclear CPSF6/CPSF5 biomolecular condensate formation important for infection, promotes circRNA cyclization, influences RNA Pol II transcription, and at complete loss additionally impairs co-translational assembly of multiprotein complexes (including nuclear pores), causing proteotoxic stress and cell cycle arrest."},"narrative":{"mechanistic_narrative":"NUDT21 (CFIm25/CPSF5) is the RNA-binding subunit of the Cleavage Factor Im complex and a master regulator of alternative polyadenylation (APA) that shapes 3'UTR length genome-wide [PMID:24814343, PMID:29249356]. It is the first Nudix-fold protein shown to bind RNA sequence-specifically, recognizing UGUA elements through a defined base-pairing geometry while retaining no detectable hydrolase activity, and its RNA binding is mutually exclusive with the signaling metabolite Ap4A [PMID:20479262]. By promoting distal poly(A) site usage, NUDT21 lengthens 3'UTRs to expose miRNA-binding sites and enhance AGO2-dependent silencing, whereas its depletion shifts processing to proximal sites, shortens 3'UTRs, and elevates proliferative and oncogenic protein output across glioblastoma, hepatocellular, bladder, and renal cancers [PMID:24814343, PMID:28964783, PMID:29780166, PMID:37737260]. The protein partners with CPSF6/CFIm68 to assemble the functional complex [PMID:32431549, PMID:40425546], and can be redirected to specific transcripts by RNA-modification readers and other RNA-binding proteins including IGF2BP3 (m6A) and FXR1 [PMID:35194031, PMID:40301554]. NUDT21 abundance and activity are tuned by post-translational control: TRIM65-mediated K48-linked ubiquitination at K56 targets it for proteasomal degradation [PMID:38951701], PRMT7-deposited mono-methylation at K23 (erased by HDAC2) restrains its oncogenic APA program [PMID:39208673], and AARS1-catalyzed lactylation at K23 enhances CPSF6 binding and complex assembly [PMID:40425546]. Beyond canonical 3' processing, NUDT21 directs differential polyadenylation of chromatin regulators during reprogramming and cell-fate transitions [PMID:29249356], and complete loss shortens 3'UTRs of nuclear pore and other complex subunits, impairing co-translational complex assembly and triggering proteotoxic stress and cell cycle arrest [PMID:41580420]. Reduced NUDT21 dosage produces tissue-level phenotypes including learning deficits and cortical hyperexcitability in mice and exaggerated fibrosis, while elevated dosage lowers MeCP2 protein via MECP2 3'UTR APA, linking NUDT21 to neurodevelopmental and fibrotic disease [PMID:26312503, PMID:31757866, PMID:32319885].","teleology":[{"year":2010,"claim":"Established the structural basis for how an APA factor reads pre-mRNA: it answered how CFIm25 achieves sequence-specific RNA recognition despite belonging to a hydrolase fold.","evidence":"Crystal structures of CFIm25-UGUA RNA complexes with mutational and in vitro binding analysis","pmids":["20479262"],"confidence":"High","gaps":["Did not establish how UGUA recognition translates into poly(A) site selection in cells","Physiological relevance of Ap4A competition not demonstrated in vivo"]},{"year":2014,"claim":"Defined NUDT21's genome-wide function as a repressor of proximal poly(A) site usage and connected 3'UTR shortening to oncogenic transformation.","evidence":"Genome-wide APA RNA-seq after siRNA knockdown plus glioblastoma xenograft assays","pmids":["24814343"],"confidence":"High","gaps":["Did not resolve which shortened transcripts drive tumorigenicity","Mechanism of distal-site preference not structurally linked to the 2010 binding model"]},{"year":2015,"claim":"Showed NUDT21 dosage controls a specific disease-relevant target, MeCP2, via APA, providing a gene-dosage mechanism for neurodevelopmental phenotypes.","evidence":"Patient-derived lymphoblast APA analysis with siRNA rescue normalizing MeCP2","pmids":["26312503"],"confidence":"High","gaps":["Did not test whether NUDT21 manipulation reverses neuronal phenotypes","Causal NUDT21 mutation in patients not established here"]},{"year":2017,"claim":"Demonstrated NUDT21-directed APA controls cell fate by tuning chromatin regulator protein levels, extending its role beyond cancer to developmental reprogramming.","evidence":"Reprogramming screen with RNA-seq, proteomics, and chromatin-regulator knockdown epistasis","pmids":["29249356"],"confidence":"High","gaps":["Did not identify the full set of fate-determining target transcripts","Upstream regulation of NUDT21 during reprogramming unresolved"]},{"year":2017,"claim":"Linked NUDT21-mediated 3'UTR lengthening mechanistically to enhanced miRNA silencing by increasing AGO2-mRNA engagement.","evidence":"Co-IP, immunofluorescence co-localization in P/GW bodies, and AGO2-mRNA binding assays","pmids":["28964783"],"confidence":"Medium","gaps":["Single lab, co-localization-based","Direct vs. indirect effect on AGO2 loading not separated"]},{"year":2018,"claim":"Identified specific APA targets (PSMB2, CXXC5; GLS isoforms) showing how individual transcript-level changes produce cancer phenotypes and metabolic rewiring.","evidence":"Global APA profiling with target validation and functional rescue knockdowns in HCC and cancer cells","pmids":["29780166","27095025"],"confidence":"Medium","gaps":["MAPK/PTEN signaling links (PMID 30349365) remain correlative","Direct NUDT21 binding to these target 3'UTRs not all demonstrated"]},{"year":2020,"claim":"Extended NUDT21's APA function to fibrosis and neuronal disease using in vivo models, establishing dosage-sensitive organismal phenotypes.","evidence":"Fibroblast-specific conditional knockout (skin fibrosis) and Nudt21+/- mice with behavioral and electrophysiology readouts plus human neuron APA profiling","pmids":["31757866","32319885"],"confidence":"High","gaps":["Causal target transcripts for each phenotype not fully defined","Therapeutic reversibility not tested"]},{"year":2020,"claim":"Revealed non-canonical roles connecting NUDT21 to antiviral signaling and to negative regulation of its complex partner CPSF6.","evidence":"Co-IP and localization with IPS-1/stress granules; mass spectrometry and CPSF6 knockdown rescue in breast cancer","pmids":["33219146","32431549"],"confidence":"Medium","gaps":["Mechanism of NUDT21 mitochondrial localization unclear","How NUDT21 negatively regulates CPSF6 expression not defined"]},{"year":2022,"claim":"Showed NUDT21 participates in alternative 3' processing complexes beyond canonical CFIm, broadening its compositional repertoire.","evidence":"Reciprocal co-IP and mass spectrometry identifying an FXR1-CFIm25/CFIm68 complex with TRAF1 processing readout","pmids":["35194031"],"confidence":"Medium","gaps":["Stoichiometry and structural arrangement of the FXR1-CFIm complex unknown","Generality beyond TRAF1 untested"]},{"year":2023,"claim":"Established post-transcriptional and condensate-based control of NUDT21, including sequestration by PABPN1 aggregates and E3-ligase-driven destabilization.","evidence":"Phase-transition assays (PABPN1 sequestration) and co-IP/ubiquitination/stability assays with TRIP12 and LINC00921","pmids":["37422193","37999979"],"confidence":"Medium","gaps":["TRIP12 ubiquitination site on NUDT21 not mapped here","Physiological contexts of sequestration not defined"]},{"year":2023,"claim":"Implicated NUDT21/CPSF5 in viral biology through HIV-1-induced CPSF6/CPSF5 nuclear condensates required for productive infection.","evidence":"Immunofluorescence, condensate disruption (1,6-hexanediol), and HIV-1 capsid mutant infection in T cells and macrophages","pmids":["37414787"],"confidence":"Medium","gaps":["Molecular function of CPSF5 within the condensate not defined","Whether APA activity is required is unknown"]},{"year":2024,"claim":"Mapped writer/eraser PTM control of NUDT21 stability and activity, defining how ubiquitination and methylation tune its oncogenic APA program.","evidence":"TRIM65 K48-ubiquitination at K56 (site-mapped, in vivo AAV) and PRMT7 mono-methylation at K23 with HDAC2 eraser (knockin mice, metabolomics)","pmids":["38951701","39208673"],"confidence":"High","gaps":["Crosstalk between K23 and K56 modifications not resolved","Upstream signals controlling these writers in disease unclear"]},{"year":2025,"claim":"Showed metabolic lactylation of NUDT21 directly enhances CFIm complex assembly, linking cellular lactate to APA-mediated drug resistance.","evidence":"K23 lactylation mapping, AARS1 writer/HDAC2 eraser, co-IP showing enhanced CPSF6 binding, FDX1 3'UTR reporter and in vivo tumor models","pmids":["40425546"],"confidence":"High","gaps":["Quantitative contribution of lactylation versus methylation at the shared K23 not resolved","Generality across tumor types untested"]},{"year":2025,"claim":"Demonstrated that RNA modifications and reader proteins recruit NUDT21 to specific transcripts, providing transcript-selective targeting mechanisms in cancer and infection.","evidence":"IGF2BP3-NUDT21 (m6A, SPTBN1), NAT10/ac4C-directed CPSF5 binding (viral RNA), and Mtb-induced disruption of NUDT21-CPSF6 (FTH1) via co-IP and APA profiling","pmids":["40301554","40167508","40384984"],"confidence":"Medium","gaps":["Whether modification readers compete with intrinsic UGUA recognition unclear","Single-lab studies per target"]},{"year":2025,"claim":"Defined NUDT21 as a driver of macrophage differentiation and polarization through APA of NF-kB and AKT2 transcripts, with its own translation gated by APA/PCBP1.","evidence":"APA profiling and target knockdown epistasis (TAB2, TBL1XR1), ASO blocking of AKT2 proximal poly(A) site, and PCBP1-long-3'UTR RIP in monocytes","pmids":["40022203","42111214","41830116"],"confidence":"Medium","gaps":["In vivo relevance in macrophage biology not fully established","Feedback between NUDT21's own APA and its activity not quantified"]},{"year":2026,"claim":"Revealed that complete NUDT21 loss disrupts co-translational assembly of protein complexes via 3'UTR shortening of nucleoporin mRNAs, defining a proteostasis function distinct from differentiation control, and uncovered a chromatin/transcription role with lineage transcription factors.","evidence":"Graded knockdown with APA profiling, CRISPR deletion of individual nucleoporin 3'UTRs recapitulating phenotypes, co-translational assembly assays (PMID 41580420); ChIP and TF co-IP plus pharmacological degradation in T-ALL (PMID 41926643)","pmids":["41580420","41926643"],"confidence":"High","gaps":["How 3'UTR length controls co-translational assembly mechanistically not fully resolved","Direct vs. indirect basis of chromatin/promoter localization unclear"]},{"year":null,"claim":"How the multiple K23 modifications (methylation, lactylation) and K56 ubiquitination are integrated to set NUDT21 activity and APA output in different cell states remains unresolved, as does the structural basis by which distal versus proximal site choice is encoded.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified model linking PTM state to genome-wide APA direction","No structural model of the full CFIm-NUDT21-CPSF6 complex on substrate","Mechanism of proximal vs. distal site selection in vivo undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[0,1,34]},{"term_id":"GO:0140098","term_label":"catalytic activity, acting on RNA","supporting_discovery_ids":[1,4,33]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[1,5]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[18,23]},{"term_id":"GO:0005654","term_label":"nucleoplasm","supporting_discovery_ids":[19,23]},{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[14]}],"pathway":[{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[0,1,4]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[17,32]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[1,11,12]}],"complexes":["Cleavage Factor Im (CFIm)"],"partners":["CPSF6","TRIM65","PRMT7","AARS1","FXR1","IGF2BP3","TRIP12","IPS-1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O43809","full_name":"Cleavage and polyadenylation specificity factor subunit 5","aliases":["Cleavage and polyadenylation specificity factor 25 kDa subunit","CPSF 25 kDa subunit","Cleavage factor Im complex 25 kDa subunit","CFIm25","Nucleoside diphosphate-linked moiety X motif 21","Nudix motif 21","Nudix hydrolase 21","Pre-mRNA cleavage factor Im 68 kDa subunit"],"length_aa":227,"mass_kda":26.2,"function":"Component of the cleavage factor Im (CFIm) complex that functions as an activator of the pre-mRNA 3'-end cleavage and polyadenylation processing required for the maturation of pre-mRNA into functional mRNAs (PubMed:14690600, PubMed:15937220, PubMed:17024186, PubMed:17098938, PubMed:29276085, PubMed:8626397, PubMed:9659921). CFIm contributes to the recruitment of multiprotein complexes on specific sequences on the pre-mRNA 3'-end, so called cleavage and polyadenylation signals (pA signals) (PubMed:14690600, PubMed:17024186, PubMed:8626397, PubMed:9659921). Most pre-mRNAs contain multiple pA signals, resulting in alternative cleavage and polyadenylation (APA) producing mRNAs with variable 3'-end formation (PubMed:17098938, PubMed:23187700, PubMed:29276085). The CFIm complex acts as a key regulator of cleavage and polyadenylation site choice during APA through its binding to 5'-UGUA-3' elements localized in the 3'-untranslated region (UTR) for a huge number of pre-mRNAs (PubMed:17098938, PubMed:20695905, PubMed:29276085). NUDT21/CPSF5 activates indirectly the mRNA 3'-processing machinery by recruiting CPSF6 and/or CPSF7 (PubMed:29276085). Binds to 5'-UGUA-3' elements localized upstream of pA signals that act as enhancers of pre-mRNA 3'-end processing (PubMed:14690600, PubMed:15169763, PubMed:17024186, PubMed:20479262, PubMed:22813749, PubMed:8626397). The homodimer mediates simultaneous sequence-specific recognition of two 5'-UGUA-3' elements within the pre-mRNA (PubMed:20479262, PubMed:21295486). Plays a role in somatic cell fate transitions and pluripotency by regulating widespread changes in gene expression through an APA-dependent function (By similarity). Binds to chromatin (By similarity). Binds to, but does not hydrolyze mono- and di-adenosine nucleotides (PubMed:18445629)","subcellular_location":"Nucleus; Cytoplasm","url":"https://www.uniprot.org/uniprotkb/O43809/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/NUDT21","classification":"Common Essential","n_dependent_lines":1208,"n_total_lines":1208,"dependency_fraction":1.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CPSF6","stoichiometry":10.0},{"gene":"TNPO3","stoichiometry":4.0}],"url":"https://opencell.sf.czbiohub.org/search/NUDT21","total_profiled":1310},"omim":[{"mim_id":"621247","title":"CLEAVAGE AND POLYADENYLATION SPECIFICITY FACTOR 7; CPSF7","url":"https://www.omim.org/entry/621247"},{"mim_id":"609676","title":"MITOCHONDRIAL ANTIVIRAL SIGNALING PROTEIN; MAVS","url":"https://www.omim.org/entry/609676"},{"mim_id":"604979","title":"CLEAVAGE AND POLYADENYLATION SPECIFICITY FACTOR 6; CPSF6","url":"https://www.omim.org/entry/604979"},{"mim_id":"604978","title":"NUDIX HYDROLASE 21; NUDT21","url":"https://www.omim.org/entry/604978"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nuclear bodies","reliability":"Supported"},{"location":"Centriolar satellite","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/NUDT21"},"hgnc":{"alias_symbol":["CFIM25"],"prev_symbol":["CPSF5"]},"alphafold":{"accession":"O43809","domains":[{"cath_id":"3.90.79.10","chopping":"59-225","consensus_level":"high","plddt":96.4063,"start":59,"end":225}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O43809","model_url":"https://alphafold.ebi.ac.uk/files/AF-O43809-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O43809-F1-predicted_aligned_error_v6.png","plddt_mean":90.38},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=NUDT21","jax_strain_url":"https://www.jax.org/strain/search?query=NUDT21"},"sequence":{"accession":"O43809","fasta_url":"https://rest.uniprot.org/uniprotkb/O43809.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O43809/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O43809"}},"corpus_meta":[{"pmid":"24814343","id":"PMC_24814343","title":"CFIm25 links alternative 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molecular immunology","url":"https://pubmed.ncbi.nlm.nih.gov/35732608","citation_count":0,"is_preprint":false},{"pmid":"41282183","id":"PMC_41282183","title":"NUDT21 Regulates Macrophage Cytokine Responses via Alternative Polyadenylation in ARDS.","date":"2025","source":"Research square","url":"https://pubmed.ncbi.nlm.nih.gov/41282183","citation_count":0,"is_preprint":false},{"pmid":"41926643","id":"PMC_41926643","title":"NUDT21 Drives T-Cell Acute Lymphoblastic Leukemia Through Dual Regulation of Alternative Polyadenylation and Transcriptional Activation.","date":"2026","source":"Advanced science (Weinheim, Baden-Wurttemberg, Germany)","url":"https://pubmed.ncbi.nlm.nih.gov/41926643","citation_count":0,"is_preprint":false},{"pmid":"40667065","id":"PMC_40667065","title":"Alternative Polyadenylation Releases PCBP1-Mediated Suppression of CFIm25 During Macrophage Differentiation.","date":"2025","source":"bioRxiv : the preprint server for 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The UGUA sequence contributes binding specificity through an intramolecular G:A Watson-Crick/sugar-edge base interaction. Mutational data suggested a mechanism for simultaneous recognition of two UGUA elements. CFIm25 has no detectable hydrolase activity despite its Nudix fold. The signaling molecule Ap4A (diadenosine tetraphosphate) and RNA bind CFIm25 in a mutually exclusive manner, suggesting small-molecule regulation of mRNA 3' processing.\",\n      \"method\": \"Crystal structure determination, mutational analysis, in vitro binding assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structures with functional mutational validation, multiple orthogonal methods in one rigorous study\",\n      \"pmids\": [\"20479262\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"CFIm25 (NUDT21) acts as a broad repressor of proximal poly(A) site usage. CFIm25 knockdown causes 3' UTR shortening of at least 1,450 genes (11% of expressed mRNAs), increases cell proliferation, and upregulates oncogenes including cyclin D1. Downregulation of CFIm25 in glioblastoma cells enhances tumorigenic properties and increases tumor size; overexpression reduces these properties and inhibits tumor growth.\",\n      \"method\": \"RNA-seq with regression model for APA analysis, CFIm25 siRNA knockdown, glioblastoma xenograft tumor assays\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genome-wide APA analysis, multiple cancer cell lines, in vivo xenograft models, replicated across multiple approaches\",\n      \"pmids\": [\"24814343\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"NUDT21 regulates MeCP2 protein quantity via alternative polyadenylation. Elevated NUDT21 increases usage of the distal polyadenylation site in the MECP2 3' UTR, resulting in enrichment of inefficiently translated long mRNA isoforms and reduced MeCP2 protein. siRNA-mediated knockdown of NUDT21 in duplication patient lymphoblasts restores MeCP2 to normal levels.\",\n      \"method\": \"Patient-derived lymphoblastoid cell analysis, MECP2 mRNA and protein abundance measurement, siRNA knockdown\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — patient-derived cells, multiple CNV cases, functional rescue experiment with siRNA normalization\",\n      \"pmids\": [\"26312503\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"CFIm25 depletion causes a shift to proximal poly(A) site usage within the KGA isoform of glutaminase (GLS) 3' UTR and alters splicing to exclude the GAC 3' UTR. The apoptosis induced by downregulation of the GAC isoform can be alleviated through concurrent reduction in CFIm25 expression, linking CFIm25 to glutamine metabolism in cancer cells.\",\n      \"method\": \"CFIm25 siRNA depletion, RT-PCR for isoform analysis, apoptosis assays, concurrent knockdown rescue experiments\",\n      \"journal\": \"RNA (New York, N.Y.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional rescue epistasis, multiple knockdown approaches, single lab\",\n      \"pmids\": [\"27095025\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Nudt21 directs differential polyadenylation of over 1,500 transcripts during cellular reprogramming to pluripotency, with the resulting protein-level changes strongly enriched for chromatin regulators. Suppression of these chromatin regulator proteins neutralizes the effect of Nudt21 during reprogramming, establishing a direct link between alternative polyadenylation and chromatin signaling in cell fate control.\",\n      \"method\": \"Transcription-factor-induced reprogramming screen, RNA-seq, proteomic analysis, epistasis via chromatin regulator knockdown\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — functional screening assay, genome-wide APA profiling, proteomic validation, epistasis experiments across multiple cell fate transitions\",\n      \"pmids\": [\"29249356\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"NUDT21 co-localizes with AGO2 in P/GW bodies in normal liver cells, and this co-localization is diminished in cancer cells. NUDT21 elongates the 3' UTR of mRNAs and enhances the efficiency of miRNA-mediated gene silencing by increasing AGO2-mRNA binding efficiency.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence co-localization, AGO2-mRNA binding assays, NUDT21 knockdown/overexpression\",\n      \"journal\": \"Cancer letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-localization and co-IP with functional follow-up, single lab, two orthogonal methods\",\n      \"pmids\": [\"28964783\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"NUDT21 knockdown in K562 cells inhibits proliferation and promotes apoptosis through the MAPK/ERK pathway, involving modulation of PTEN and downstream ERK1/2 signaling.\",\n      \"method\": \"Lentiviral NUDT21 knockdown in K562 cells, RNA microarray, intracellular signaling array, western blotting, flow cytometry\",\n      \"journal\": \"Cancer management and research\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, signaling array without direct mechanistic validation of the NUDT21-PTEN-ERK connection\",\n      \"pmids\": [\"30349365\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"NUDT21 knockdown increases proximal polyadenylation site usage in the 3' UTRs of PSMB2 and CXXC5, resulting in marked increases in their protein expression, which promote HCC cell proliferation and invasion.\",\n      \"method\": \"Global APA site profiling, NUDT21 knockdown/overexpression, western blotting for PSMB2 and CXXC5, functional rescue knockdown of PSMB2 and CXXC5\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — global APA profiling plus specific target validation, functional epistasis via individual target knockdown, single lab\",\n      \"pmids\": [\"29780166\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"CFIm25 inhibits HCC cell migration and invasion by blocking the p38 and JNK/c-Jun signaling pathways, and disrupts epithelial-mesenchymal transition by increasing E-cadherin. CFIm25 knockdown increases transcriptional activity of AP-1.\",\n      \"method\": \"CFIm25 knockdown/overexpression, in vitro invasion and migration assays, in vivo metastasis models, western blotting for EMT markers and MAPK pathway components, AP-1 reporter assay\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo and in vitro functional studies, pathway analysis by western blot and reporter assay, single lab\",\n      \"pmids\": [\"29545935\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"NUDT21 promotes circRNA cyclization by recognizing UGUA sequences, and NUDT21 knockdown disrupts circRNA-miRNA-mRNA ceRNA pathways in hepatocellular carcinoma. Overexpression of downregulated circRNAs assists NUDT21-mediated tumor suppression.\",\n      \"method\": \"NUDT21 knockdown/overexpression, circRNA expression profiling, UGUA motif mutagenesis, ceRNA pathway analysis, functional rescue with circRNA overexpression\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional rescue epistasis, motif mutagenesis, single lab with multiple approaches\",\n      \"pmids\": [\"31570791\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"NUDT21 modulates the expression of ANXA2 and LIMK2 via alternative polyadenylation in bladder cancer, and these genes act in the Wnt/β-catenin and NF-κB signaling pathways.\",\n      \"method\": \"Global APA site profiling, NUDT21 knockdown/overexpression, TOP/FOP flash reporter assay (Wnt/β-catenin), western blotting\",\n      \"journal\": \"Theranostics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — global APA profiling with specific target validation and pathway reporter assay, single lab\",\n      \"pmids\": [\"31695759\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"CFIm25 depletion promotes 3' UTR shortening of TGFβ-regulated fibrotic genes and enhances their protein expression in normal dermal fibroblasts. Fibroblast-specific CFIm25 deletion in mice exaggerates bleomycin-induced skin fibrosis, and CFIm25 restoration attenuates this fibrosis.\",\n      \"method\": \"CFIm25 knockdown in fibroblasts, APA profiling, fibroblast-specific conditional knockout mice, bleomycin-induced fibrosis model\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional knockout mouse model, APA profiling, in vivo rescue, and cell-level mechanistic validation across multiple approaches\",\n      \"pmids\": [\"31757866\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Nudt21+/- mice with 30% reduced CFIm25 protein show learning deficits, cortical hyperexcitability, and misregulated APA in hippocampi. Partial NUDT21 inhibition (30% CFIm25 reduction) in human stem cell-derived neurons induces APA and protein level misregulation in hundreds of genes, several of which cause intellectual disability when mutated.\",\n      \"method\": \"Nudt21+/- mouse model, behavioral testing (learning), electrophysiology (cortical hyperexcitability), APA profiling in hippocampi, human stem cell-derived neuron experiments\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo mouse model, human stem cell-derived neurons, APA genome-wide profiling, multiple phenotypic readouts\",\n      \"pmids\": [\"32319885\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"NUDT21 co-localizes with EZH2 in human trophoblast cells and binds to EZH2 mRNA. NUDT21 elongates 3' UTRs, exposing additional miRNA binding sites (including miR138 and miR363), thereby enhancing miRNA-mediated silencing of EZH2.\",\n      \"method\": \"RNA immunoprecipitation (RIP), immunofluorescence co-localization, NUDT21 loss-of-function assays, 3' UTR length analysis\",\n      \"journal\": \"Journal of cellular and molecular medicine\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, RIP without strong mechanistic follow-up, binding to mRNA rather than protein\",\n      \"pmids\": [\"30883033\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"NUDT21 physically associates with IPS-1 (mitochondrial antiviral adaptor) and mediates IPS-1 localization to stress granules in response to poly(I:C) transfection. A fraction of NUDT21 localizes to mitochondria in resting cells and moves to stress granules upon viral dsRNA stimulation. NUDT21 is required for efficient type I IFN induction in response to viral infection.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence/subcellular fractionation, poly(I:C) stimulation, NUDT21 knockdown in HeLa and RAW264.7 cells, IFN induction assays\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, localization experiments, functional knockdown with IFN readout, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"33219146\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"HIF-1α-mediated downregulation of NUDT21 alters expression patterns of the two GLS1 isoforms GAC and KGA in SCLC under hypoxia, linking hypoxic tumor environments to aberrant glutamine metabolism.\",\n      \"method\": \"NUDT21 shRNA transduction, hypoxia treatment, HIF-1α inhibition, isoform expression analysis by RT-PCR/western blot\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, indirect mechanism (HIF-1α → NUDT21 → GLS1 isoforms), no direct reconstitution of HIF-1α/NUDT21 interaction\",\n      \"pmids\": [\"32228887\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"NUDT21 directly interacted with CPSF6 as detected by mass spectrometry and western blotting, and negatively regulated CPSF6 expression in breast cancer cells. Knockdown of CPSF6 reversed NUDT21 expression-induced cancer cell migration and invasion.\",\n      \"method\": \"Mass spectrometry, western blotting, co-immunoprecipitation, CPSF6 knockdown rescue experiments\",\n      \"journal\": \"Cancer management and research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mass spectrometry plus western blot for interaction, functional epistasis via CPSF6 knockdown rescue, single lab\",\n      \"pmids\": [\"32431549\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"NUDT21 gene editing in human embryonic stem cells impairs differentiation potential and increases proliferation, but unexpectedly did not significantly affect cellular mRNA 3' processing efficiency or APA profile. Instead, CFIm25 perturbation affects RNA polymerase II occupancy at the body of transcribed genes and promotes expression of transcripts associated with proliferation/differentiation including rex1.\",\n      \"method\": \"CRISPR/Cas9 editing of CFIm25 in hESCs, RNA-seq APA profiling, Pol II ChIP-seq, proliferation and differentiation assays\",\n      \"journal\": \"RNA biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — CRISPR-based editing, Pol II ChIP-seq, APA profiling with negative APA result, single lab with multiple methods\",\n      \"pmids\": [\"35491945\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"FXR1 interacts with CFIm25 (NUDT21) and CFIm68, forming a novel 3' processing machinery for sequence-specific poly(A) site recognition. This FXR1-CFIm25/CFIm68 complex affects 3' processing of TRAF1 mRNA, leading to its nuclear stabilization.\",\n      \"method\": \"Co-immunoprecipitation, mass spectrometry, 3' end processing assays, TRAF1 mRNA stability analysis\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP, mass spectrometry identification, functional mRNA processing readout, single lab\",\n      \"pmids\": [\"35194031\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Poly(A)-binding protein nuclear 1 (PABPN1) aggregates sequester CFIm25 in an mRNA-dependent manner, impairing CFIm25 function in alternative polyadenylation. Ala expansion drives PABPN1 aggregation from nuclear speckles, and poly(A) nucleotide is essential for early-stage condensation.\",\n      \"method\": \"Biochemical phase transition assays, molecular cell biology, immunofluorescence, APA profiling in PABPN1 aggregate conditions\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — biochemical reconstitution of aggregation, functional APA readout upon sequestration, single lab with multiple methods\",\n      \"pmids\": [\"37422193\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"LINC00921 lncRNA controls NUDT21 protein stability by facilitating binding of NUDT21 with the E3 ubiquitin ligase TRIP12, leading to NUDT21 destabilization and subsequent 3' UTR shortening of MED23 mRNA via APA.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assays, APA profiling, NUDT21 stability assays with TRIP12 knockdown/overexpression\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP evidence for NUDT21-TRIP12 interaction, functional APA readout, stability assays, single lab\",\n      \"pmids\": [\"37999979\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"NUDT21 loss (induced by DNMT3B-mediated promoter methylation) causes 3' UTR shortening of MORC2 mRNA, stabilizing MORC2 and enhancing its oncogenic activity in kidney renal clear cell carcinoma. MORC2 subsequently recruits DNMT3A to hypermethylate the DAPK1 promoter, silencing this tumor suppressor.\",\n      \"method\": \"APA profiling, NUDT21 promoter methylation analysis, MORC2 3'UTR reporter assay, DNMT3A ChIP, DAPK1 promoter methylation assay\",\n      \"journal\": \"JCI insight\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — APA profiling, epigenetic mechanistic follow-up via ChIP, antisense oligonucleotide rescue in vivo, single lab\",\n      \"pmids\": [\"37737260\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"NUDT21 knockdown in glioma cells causes 3' UTR shortening of LAMC1, removing miR-124/506 binding sites and relieving miRNA repression, resulting in increased LAMC1 protein and enhanced glioma cell migration. Co-depletion of LAMC1 with NUDT21 abolishes the NUDT21-knockdown-induced migration phenotype.\",\n      \"method\": \"PAC-seq APA profiling, qRT-PCR, western blotting for LAMC1, miRNA binding site analysis, co-depletion epistasis experiment, cell migration assays\",\n      \"journal\": \"Journal of neuro-oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genome-wide APA profiling, specific target validation, epistasis by co-depletion, single lab\",\n      \"pmids\": [\"37389756\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"HIV-1 nuclear entry triggers translocation of CPSF6 from paraspeckles into nuclear speckles, forming biomolecular condensates. CPSF5 (NUDT21), but not CPSF7, co-localizes with CPSF6 in these condensates. Formation of CPSF6/CPSF5 condensates does not require HIV-1 integration or reverse transcription, but is required for productive wild-type HIV-1 infection (not for capsid mutants N74D/A77V that do not form condensates).\",\n      \"method\": \"Immunofluorescence, osmotic stress/1,6-hexanediol condensate disruption assays, HIV-1 infection with capsid mutants, fluorescence microscopy in T cells and primary macrophages\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple condensate disruption methods, capsid mutant controls, primary cell validation, single lab\",\n      \"pmids\": [\"37414787\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"TRIM65 E3 ligase interacts with NUDT21 (identified by yeast-hybrid screen) and induces K48-linked polyubiquitination of NUDT21 at lysine 56, leading to proteasomal degradation. NUDT21 degradation inhibits TGF-β1-mediated SMAD and ERK1/2 signaling and alters 3'UTR-APA of pro-fibrotic genes (Col1a1, Fn-1, Tgfbr1, Wnt5a, Fzd2).\",\n      \"method\": \"Yeast-hybrid screen, co-immunoprecipitation, ubiquitination assay with K48-linkage specificity, proteasome inhibitor treatment, APA profiling, AAV9-mediated NUDT21 knockdown in vivo\",\n      \"journal\": \"Cell death and differentiation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — ubiquitination site mapped (K56), linkage specificity determined (K48), yeast-hybrid + co-IP for interaction, in vivo AAV model, multiple orthogonal methods\",\n      \"pmids\": [\"38951701\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"PRMT7-mediated mono-methylation of NUDT21 (at K23) induces a shift in 3'UTR usage, reducing oncogenicity in prostate cancer. Un-methylated NUDT21 promotes cancer growth and cuproptosis insensitivity by suppressing docosahexaenoic acid (DHA) biosynthesis. HDAC2 serves as the eraser of NUDT21 K23 mono-methylation.\",\n      \"method\": \"Mono-methylation monoclonal antibody generation, conditional knockin transgenic mouse model, transcriptomic and metabolomic analyses, loss-of-function and gain-of-function assays, drug-resistant cell lines\",\n      \"journal\": \"Drug resistance updates\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — specific methylation site mapped, writer (PRMT7) and eraser (HDAC2) identified, transgenic mouse model, multiple orthogonal approaches including metabolomics\",\n      \"pmids\": [\"39208673\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"L-lactate-induced lactylation of NUDT21 at K23 (catalyzed by AARS1 as the 'writer' and removed by HDAC2 as the 'eraser') enhances NUDT21 interaction with CPSF6, facilitating CFIm complex formation and inducing 3'UTR lengthening of FDX1. This extended FDX1 3'UTR attenuates FDX1 protein output, conferring resistance to cuproptosis in esophageal squamous cell carcinoma.\",\n      \"method\": \"Lactylation site mapping (K23), co-immunoprecipitation for NUDT21-CPSF6 interaction, APA profiling, FDX1 3'UTR reporter assay, AARS1 and HDAC2 functional validation, in vivo tumor models\",\n      \"journal\": \"Cell discovery\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — PTM site mapped, writer/eraser identified, protein interaction consequence demonstrated, in vivo functional validation, multiple orthogonal methods\",\n      \"pmids\": [\"40425546\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"IGF2BP3 interacts with NUDT21 (recognizing m6A-modified site in intron 32 of SPTBN1), recruiting NUDT21 to promote usage of the SPTBN1 proximal polyadenylation site and increasing generation of short SPTBN1 transcripts in ovarian cancer cells.\",\n      \"method\": \"Co-immunoprecipitation, m6A site mapping, APA site profiling, SPTBN1 isoform functional assays\",\n      \"journal\": \"Communications biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP for interaction, m6A modification site mapped, APA functional consequence demonstrated, single lab\",\n      \"pmids\": [\"40301554\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"N-acetyltransferase 10 (NAT10) catalyzes ac4C modification at nucleotide 3311 of MVC viral RNA, which promotes specific binding of CPSF5 (NUDT21) to the target region. NP1 recruits CPSF5 to MVC RNAs in an ac4C-dependent manner, and this CPSF5 binding is required for precise alternative viral RNA processing without altering RNA stability.\",\n      \"method\": \"acRIP-seq, RedaC:T-seq for ac4C site mapping, in vitro binding assays, NP1/CPSF5 co-IP, viral RNA processing assays with ac4C mutants\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro binding assays with modification site mapped, co-IP, functional RNA processing readout, single lab\",\n      \"pmids\": [\"40167508\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"PCBP1 suppresses CFIm25 (NUDT21) translation in monocytes by binding to its long 3'UTR. During monocyte-to-macrophage differentiation, alternative polyadenylation generates a shorter CFIm25 3'UTR lacking PCBP1 binding sites, releasing translational suppression and increasing CFIm25 protein. PCBP1 knockdown increases CFIm25 protein and induces macrophage differentiation markers without stimulation.\",\n      \"method\": \"RNA immunoprecipitation (PCBP1-long 3'UTR), ribosome association analysis, APA analysis during differentiation, PCBP1 knockdown experiments\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — RIP confirmation, ribosome association, functional PCBP1 knockdown, mechanistic link between APA and translation, single lab\",\n      \"pmids\": [\"41830116\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"CFIm25 (NUDT21) promotes macrophage differentiation by inducing APA-mediated 3'UTR shortening of TAB2 and TBL1XR1 mRNAs (positive NF-κB regulators), increasing their protein levels and activating NF-κB signaling. CFIm25 overexpression elevates NF-κB-p65 phosphorylation and increases expression of NF-κB targets. Knockdown of TAB2 and TBL1XR1 in CFIm25-overexpressing cells attenuates these effects.\",\n      \"method\": \"CFIm25 overexpression/knockdown in monocytic cell lines, 3' end-focused sequencing (APA), western blotting, NF-κB chemical inhibition, TAB2/TBL1XR1 knockdown epistasis\",\n      \"journal\": \"Cell communication and signaling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — APA profiling, epistasis via target knockdown, multiple functional readouts, single lab\",\n      \"pmids\": [\"40022203\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"CFIm25 promotes proximal polyadenylation of AKT2 mRNA, generating shorter transcripts with enhanced stability and translational efficiency that increase Akt2 protein levels and support M1 macrophage polarization via NF-κB signaling. Blocking the proximal AKT2 poly(A) site with an antisense oligonucleotide reduces Akt2 expression and M1 traits.\",\n      \"method\": \"CFIm25 overexpression/knockdown, APA site analysis of AKT2, ASO blocking of proximal poly(A) site, Akt2 protein and mRNA stability analysis, nitric oxide/CD80/cytokine assays for macrophage polarization\",\n      \"journal\": \"iScience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — specific poly(A) site manipulation via ASO, protein level consequences demonstrated, functional polarization readouts, single lab\",\n      \"pmids\": [\"42111214\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"NUDT21 promotes distal poly(A) site usage of UBE2D3 oncogenic transcripts in T-ALL, generating long 3'UTR isoforms with enhanced mRNA stability and increased protein expression. NUDT21 also localizes to transcriptionally active promoters and interacts with lineage-specific transcription factors MYB, RUNX1, and GATA3 to facilitate MYC transcription. Pharmacological targeting with ouabain octahydrate degrades NUDT21 protein and suppresses UBE2D3 and MYC.\",\n      \"method\": \"Multi-omics analysis, APA profiling, ChIP/chromatin localization, co-IP with transcription factors, pharmacological NUDT21 degradation, T-ALL functional assays\",\n      \"journal\": \"Advanced science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multi-omics, co-IP for TF interactions, chromatin localization, pharmacological validation, single lab\",\n      \"pmids\": [\"41926643\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Moderate Nudt21 suppression causes maturation arrest of stem cells due to 3'UTR-shortening of differentiation-associated mRNAs that escape miRNA regulation and perturb ceRNA networks. Complete Nudt21 suppression additionally shortens 3'UTRs of mRNAs encoding nuclear pore complex subunits, leading to complex destabilization, proteotoxic stress, DNA damage, and cell cycle arrest. Deletion of alternative 3'UTRs of individual nucleoporins recapitulates defects of Nudt21 loss, and co-translational assembly of dozens of protein complexes is impaired in Nudt21-deficient cells.\",\n      \"method\": \"Graded Nudt21 knockdown, APA profiling, nuclear pore complex stability assays, proteotoxic stress markers, individual nucleoporin 3'UTR deletion by CRISPR, ribosome profiling/co-translational assembly analysis\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct CRISPR deletion of individual 3'UTRs recapitulating Nudt21 phenotype, co-translational assembly assays, multiple graded knockdown conditions, multiple orthogonal methods\",\n      \"pmids\": [\"41580420\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"NUDT21 promotes usage of the proximal polyadenylation site on MZT1 mRNA by binding to the UGUA element located upstream of the proximal PAS in pancreatic cancer cells.\",\n      \"method\": \"APA profiling, UGUA element analysis, NUDT21 binding site mapping, functional studies with proximal PAS usage\",\n      \"journal\": \"iScience\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — binding inferred from APA profiling and UGUA motif analysis without direct protein-RNA interaction assay, single lab\",\n      \"pmids\": [\"38303721\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"NUDT21 mediates APA of LOXL2 3'UTR, thereby modulating LOXL2 expression and ECM protein cross-linking in silica-induced pulmonary fibrosis.\",\n      \"method\": \"NUDT21 modulation, APA analysis of LOXL2 3'UTR, siRNA-loaded liposomes for in vivo LOXL2 knockdown\",\n      \"journal\": \"Ecotoxicology and environmental safety\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, indirect evidence for NUDT21-LOXL2 APA without reconstitution\",\n      \"pmids\": [\"39700768\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Mycobacterium tuberculosis disrupts the interaction between NUDT21 and CPSF6, impairing NUDT21's ability to bind UGUA motifs in the FTH1 3'UTR. This shifts polyadenylation toward longer FTH1 isoforms with enhanced protein synthesis, facilitating bacterial survival. Silencing NUDT21 reduces macrophage bactericidal activity against Mtb.\",\n      \"method\": \"Co-immunoprecipitation (NUDT21-CPSF6 interaction), APA profiling of FTH1, NUDT21 knockdown, intracellular Mtb survival assays\",\n      \"journal\": \"Frontiers in cellular and infection microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP for disrupted NUDT21-CPSF6 interaction, APA profiling, functional infection assay, single lab\",\n      \"pmids\": [\"40384984\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"miR-23a, miR-222, and miR-323a directly regulate NUDT21 mRNA levels in mantle cell lymphoma cells. The NUDT21 pre-mRNA undergoes alternative polyadenylation within the same terminal exon generating three different sized mRNAs with different 3'UTR lengths, each using a different canonical polyadenylation signal (AAUAAA). The different 3'UTR lengths affect NUDT21's own evasion of miRNA regulation.\",\n      \"method\": \"miRNA mimic and inhibitor experiments, 3'UTR luciferase reporter assays, mRNA stability measurements, APA isoform characterization\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — miRNA mimic/inhibitor with functional readout, APA isoform characterization, luciferase reporter validation, single lab\",\n      \"pmids\": [\"39812508\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"NUDT21 (CFIm25/CPSF5) is the 25 kDa subunit of the Cleavage Factor Im (CFIm) complex that acts as a master regulator of alternative polyadenylation (APA): it binds UGUA motifs on pre-mRNAs via its Nudix fold (without hydrolase activity) to stimulate distal poly(A) site usage, thereby lengthening 3'UTRs and allowing miRNA-mediated gene silencing; its depletion globally shifts polyadenylation to proximal sites, shortening 3'UTRs and upregulating proliferative and oncogenic transcripts. NUDT21's activity and stability are controlled by post-translational modifications including K48-linked ubiquitination by TRIM65 (degradation), PRMT7-mediated mono-methylation at K23 (reduces oncogenicity), and AARS1-catalyzed lactylation at K23 (enhances CPSF6 interaction and complex assembly). Beyond canonical 3' processing, NUDT21 also links mitochondrial antiviral signaling (IPS-1) to stress granules, participates in HIV-1-induced nuclear CPSF6/CPSF5 biomolecular condensate formation important for infection, promotes circRNA cyclization, influences RNA Pol II transcription, and at complete loss additionally impairs co-translational assembly of multiprotein complexes (including nuclear pores), causing proteotoxic stress and cell cycle arrest.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"NUDT21 (CFIm25/CPSF5) is the RNA-binding subunit of the Cleavage Factor Im complex and a master regulator of alternative polyadenylation (APA) that shapes 3'UTR length genome-wide [#1, #4]. It is the first Nudix-fold protein shown to bind RNA sequence-specifically, recognizing UGUA elements through a defined base-pairing geometry while retaining no detectable hydrolase activity, and its RNA binding is mutually exclusive with the signaling metabolite Ap4A [#0]. By promoting distal poly(A) site usage, NUDT21 lengthens 3'UTRs to expose miRNA-binding sites and enhance AGO2-dependent silencing, whereas its depletion shifts processing to proximal sites, shortens 3'UTRs, and elevates proliferative and oncogenic protein output across glioblastoma, hepatocellular, bladder, and renal cancers [#1, #5, #7, #21]. The protein partners with CPSF6/CFIm68 to assemble the functional complex [#16, #26], and can be redirected to specific transcripts by RNA-modification readers and other RNA-binding proteins including IGF2BP3 (m6A) and FXR1 [#18, #27]. NUDT21 abundance and activity are tuned by post-translational control: TRIM65-mediated K48-linked ubiquitination at K56 targets it for proteasomal degradation [#24], PRMT7-deposited mono-methylation at K23 (erased by HDAC2) restrains its oncogenic APA program [#25], and AARS1-catalyzed lactylation at K23 enhances CPSF6 binding and complex assembly [#26]. Beyond canonical 3' processing, NUDT21 directs differential polyadenylation of chromatin regulators during reprogramming and cell-fate transitions [#4], and complete loss shortens 3'UTRs of nuclear pore and other complex subunits, impairing co-translational complex assembly and triggering proteotoxic stress and cell cycle arrest [#33]. Reduced NUDT21 dosage produces tissue-level phenotypes including learning deficits and cortical hyperexcitability in mice and exaggerated fibrosis, while elevated dosage lowers MeCP2 protein via MECP2 3'UTR APA, linking NUDT21 to neurodevelopmental and fibrotic disease [#2, #11, #12].\",\n  \"teleology\": [\n    {\n      \"year\": 2010,\n      \"claim\": \"Established the structural basis for how an APA factor reads pre-mRNA: it answered how CFIm25 achieves sequence-specific RNA recognition despite belonging to a hydrolase fold.\",\n      \"evidence\": \"Crystal structures of CFIm25-UGUA RNA complexes with mutational and in vitro binding analysis\",\n      \"pmids\": [\"20479262\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not establish how UGUA recognition translates into poly(A) site selection in cells\", \"Physiological relevance of Ap4A competition not demonstrated in vivo\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Defined NUDT21's genome-wide function as a repressor of proximal poly(A) site usage and connected 3'UTR shortening to oncogenic transformation.\",\n      \"evidence\": \"Genome-wide APA RNA-seq after siRNA knockdown plus glioblastoma xenograft assays\",\n      \"pmids\": [\"24814343\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve which shortened transcripts drive tumorigenicity\", \"Mechanism of distal-site preference not structurally linked to the 2010 binding model\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Showed NUDT21 dosage controls a specific disease-relevant target, MeCP2, via APA, providing a gene-dosage mechanism for neurodevelopmental phenotypes.\",\n      \"evidence\": \"Patient-derived lymphoblast APA analysis with siRNA rescue normalizing MeCP2\",\n      \"pmids\": [\"26312503\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not test whether NUDT21 manipulation reverses neuronal phenotypes\", \"Causal NUDT21 mutation in patients not established here\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Demonstrated NUDT21-directed APA controls cell fate by tuning chromatin regulator protein levels, extending its role beyond cancer to developmental reprogramming.\",\n      \"evidence\": \"Reprogramming screen with RNA-seq, proteomics, and chromatin-regulator knockdown epistasis\",\n      \"pmids\": [\"29249356\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify the full set of fate-determining target transcripts\", \"Upstream regulation of NUDT21 during reprogramming unresolved\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Linked NUDT21-mediated 3'UTR lengthening mechanistically to enhanced miRNA silencing by increasing AGO2-mRNA engagement.\",\n      \"evidence\": \"Co-IP, immunofluorescence co-localization in P/GW bodies, and AGO2-mRNA binding assays\",\n      \"pmids\": [\"28964783\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab, co-localization-based\", \"Direct vs. indirect effect on AGO2 loading not separated\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Identified specific APA targets (PSMB2, CXXC5; GLS isoforms) showing how individual transcript-level changes produce cancer phenotypes and metabolic rewiring.\",\n      \"evidence\": \"Global APA profiling with target validation and functional rescue knockdowns in HCC and cancer cells\",\n      \"pmids\": [\"29780166\", \"27095025\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"MAPK/PTEN signaling links (PMID 30349365) remain correlative\", \"Direct NUDT21 binding to these target 3'UTRs not all demonstrated\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Extended NUDT21's APA function to fibrosis and neuronal disease using in vivo models, establishing dosage-sensitive organismal phenotypes.\",\n      \"evidence\": \"Fibroblast-specific conditional knockout (skin fibrosis) and Nudt21+/- mice with behavioral and electrophysiology readouts plus human neuron APA profiling\",\n      \"pmids\": [\"31757866\", \"32319885\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Causal target transcripts for each phenotype not fully defined\", \"Therapeutic reversibility not tested\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Revealed non-canonical roles connecting NUDT21 to antiviral signaling and to negative regulation of its complex partner CPSF6.\",\n      \"evidence\": \"Co-IP and localization with IPS-1/stress granules; mass spectrometry and CPSF6 knockdown rescue in breast cancer\",\n      \"pmids\": [\"33219146\", \"32431549\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of NUDT21 mitochondrial localization unclear\", \"How NUDT21 negatively regulates CPSF6 expression not defined\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Showed NUDT21 participates in alternative 3' processing complexes beyond canonical CFIm, broadening its compositional repertoire.\",\n      \"evidence\": \"Reciprocal co-IP and mass spectrometry identifying an FXR1-CFIm25/CFIm68 complex with TRAF1 processing readout\",\n      \"pmids\": [\"35194031\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Stoichiometry and structural arrangement of the FXR1-CFIm complex unknown\", \"Generality beyond TRAF1 untested\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Established post-transcriptional and condensate-based control of NUDT21, including sequestration by PABPN1 aggregates and E3-ligase-driven destabilization.\",\n      \"evidence\": \"Phase-transition assays (PABPN1 sequestration) and co-IP/ubiquitination/stability assays with TRIP12 and LINC00921\",\n      \"pmids\": [\"37422193\", \"37999979\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"TRIP12 ubiquitination site on NUDT21 not mapped here\", \"Physiological contexts of sequestration not defined\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Implicated NUDT21/CPSF5 in viral biology through HIV-1-induced CPSF6/CPSF5 nuclear condensates required for productive infection.\",\n      \"evidence\": \"Immunofluorescence, condensate disruption (1,6-hexanediol), and HIV-1 capsid mutant infection in T cells and macrophages\",\n      \"pmids\": [\"37414787\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular function of CPSF5 within the condensate not defined\", \"Whether APA activity is required is unknown\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Mapped writer/eraser PTM control of NUDT21 stability and activity, defining how ubiquitination and methylation tune its oncogenic APA program.\",\n      \"evidence\": \"TRIM65 K48-ubiquitination at K56 (site-mapped, in vivo AAV) and PRMT7 mono-methylation at K23 with HDAC2 eraser (knockin mice, metabolomics)\",\n      \"pmids\": [\"38951701\", \"39208673\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Crosstalk between K23 and K56 modifications not resolved\", \"Upstream signals controlling these writers in disease unclear\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Showed metabolic lactylation of NUDT21 directly enhances CFIm complex assembly, linking cellular lactate to APA-mediated drug resistance.\",\n      \"evidence\": \"K23 lactylation mapping, AARS1 writer/HDAC2 eraser, co-IP showing enhanced CPSF6 binding, FDX1 3'UTR reporter and in vivo tumor models\",\n      \"pmids\": [\"40425546\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Quantitative contribution of lactylation versus methylation at the shared K23 not resolved\", \"Generality across tumor types untested\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Demonstrated that RNA modifications and reader proteins recruit NUDT21 to specific transcripts, providing transcript-selective targeting mechanisms in cancer and infection.\",\n      \"evidence\": \"IGF2BP3-NUDT21 (m6A, SPTBN1), NAT10/ac4C-directed CPSF5 binding (viral RNA), and Mtb-induced disruption of NUDT21-CPSF6 (FTH1) via co-IP and APA profiling\",\n      \"pmids\": [\"40301554\", \"40167508\", \"40384984\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether modification readers compete with intrinsic UGUA recognition unclear\", \"Single-lab studies per target\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Defined NUDT21 as a driver of macrophage differentiation and polarization through APA of NF-kB and AKT2 transcripts, with its own translation gated by APA/PCBP1.\",\n      \"evidence\": \"APA profiling and target knockdown epistasis (TAB2, TBL1XR1), ASO blocking of AKT2 proximal poly(A) site, and PCBP1-long-3'UTR RIP in monocytes\",\n      \"pmids\": [\"40022203\", \"42111214\", \"41830116\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vivo relevance in macrophage biology not fully established\", \"Feedback between NUDT21's own APA and its activity not quantified\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Revealed that complete NUDT21 loss disrupts co-translational assembly of protein complexes via 3'UTR shortening of nucleoporin mRNAs, defining a proteostasis function distinct from differentiation control, and uncovered a chromatin/transcription role with lineage transcription factors.\",\n      \"evidence\": \"Graded knockdown with APA profiling, CRISPR deletion of individual nucleoporin 3'UTRs recapitulating phenotypes, co-translational assembly assays (PMID 41580420); ChIP and TF co-IP plus pharmacological degradation in T-ALL (PMID 41926643)\",\n      \"pmids\": [\"41580420\", \"41926643\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How 3'UTR length controls co-translational assembly mechanistically not fully resolved\", \"Direct vs. indirect basis of chromatin/promoter localization unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the multiple K23 modifications (methylation, lactylation) and K56 ubiquitination are integrated to set NUDT21 activity and APA output in different cell states remains unresolved, as does the structural basis by which distal versus proximal site choice is encoded.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified model linking PTM state to genome-wide APA direction\", \"No structural model of the full CFIm-NUDT21-CPSF6 complex on substrate\", \"Mechanism of proximal vs. distal site selection in vivo undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [0, 1, 34]},\n      {\"term_id\": \"GO:0140098\", \"supporting_discovery_ids\": [1, 4, 33]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [1, 5]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [18, 23]},\n      {\"term_id\": \"GO:0005654\", \"supporting_discovery_ids\": [19, 23]},\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [14]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [0, 1, 4]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [17, 32]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [1, 11, 12]}\n    ],\n    \"complexes\": [\"Cleavage Factor Im (CFIm)\"],\n    \"partners\": [\"CPSF6\", \"TRIM65\", \"PRMT7\", \"AARS1\", \"FXR1\", \"IGF2BP3\", \"TRIP12\", \"IPS-1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}