{"gene":"TUT4","run_date":"2026-06-10T10:51:56","timeline":{"discoveries":[{"year":2009,"finding":"TUT4 (TUTase4) was identified as the uridylyl transferase responsible for adding oligouridine tails to pre-let-7, thereby blocking Dicer processing. Lin28 recruits TUT4 to pre-let-7 by recognizing a tetra-nucleotide sequence motif (GGAG) in the terminal loop of the precursor.","method":"Biochemical identification, knockdown experiments, in vitro uridylation assays","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — in vitro uridylation assay with functional validation, replicated independently in the same year by a second lab (PMID:19713958)","pmids":["19703396"],"is_preprint":false},{"year":2009,"finding":"Zcchc11 (TUT4) is the 3' terminal uridylyl transferase responsible for Lin28-mediated pre-let-7 uridylation in mouse embryonic stem cells. The activity is UTP-dependent and selective for let-7 precursors. Knockdown of Zcchc11 or overexpression of a catalytically inactive TUTase relieves inhibition of let-7 processing, leading to accumulation of mature let-7 and repression of let-7 target reporter genes.","method":"Knockdown, overexpression of catalytically inactive mutant, in vitro uridylation assay, reporter gene assay","journal":"Nature structural & molecular biology","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — catalytic mutant validation, multiple orthogonal methods, independent replication of PMID:19703396","pmids":["19713958"],"is_preprint":false},{"year":2009,"finding":"Zcchc11 (TUT4) is a ribonucleotidyltransferase with preference for uridine that uridylates mature miR-26a at its 3' end, abrogating IL-6 repression by miR-26a and thereby promoting IL-6 mRNA stability and expression.","method":"Knockdown, small RNA sequencing, poly(A) tail length assay, in vitro nucleotidyltransferase assay","journal":"Nature cell biology","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — direct enzymatic assay combined with knockdown and sequencing showing uridylation of mature miRNA, with functional cytokine output measured","pmids":["19701194"],"is_preprint":false},{"year":2010,"finding":"ZCCHC11 (TUT4) is the cytoplasmic terminal U-transferase responsible for 3' uridylation of replication-dependent histone mRNAs, targeting them for degradation following inhibition or completion of DNA replication. Knockdown of ZCCHC11 selectively blocked histone mRNA degradation and reduced the proportion of uridylated histone transcripts.","method":"siRNA knockdown, detection of uridylated histone mRNAs, degradation assays","journal":"RNA (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 2 / Moderate — specific knockdown phenotype with direct measurement of uridylation levels and mRNA degradation in a single focused study","pmids":["21051505"],"is_preprint":false},{"year":2011,"finding":"Zcchc11 (TUT4) promotes G1-to-S phase cell cycle progression by increasing expression of cyclins D1 and A and CDK4, through both Rb-dependent and Rb-independent mechanisms. Importantly, this proliferative activity is independent of its uridyltransferase activity, as a catalytically inactive point mutant retains full effect, and is driven by the N-terminal region of the protein lacking RNA-binding and uridyltransferase domains.","method":"Loss-of-function (knockdown), gain-of-function (overexpression), catalytic domain point mutants, truncation mutants, cell cycle analysis","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple mutant constructs and cell cycle readouts in a single lab","pmids":["22006926"],"is_preprint":false},{"year":2012,"finding":"A single C2H2-type zinc finger domain of Zcchc11 (TUT4) is responsible for the functional interaction with Lin28, enabling Lin28-enhanced pre-let-7 uridylation. Zcchc6 (TUT7) functions redundantly with Zcchc11 in Lin28-mediated let-7 biogenesis control in embryonic stem cells.","method":"Biochemical dissection, domain truncation, reconstitution assays, embryonic stem cell knockdown","journal":"RNA (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — reconstitution and biochemical domain mapping with multiple constructs, functional validation in stem cells","pmids":["22898984"],"is_preprint":false},{"year":2012,"finding":"Zcchc11 (TUT4) mediates terminal uridylation of diverse mature miRNAs in neonatal mouse liver. This uridylation does not alter miRNA abundance but relieves miRNA-mediated silencing of IGF-1 mRNA, leading to enhanced IGF-1 expression that is required for postnatal growth and survival.","method":"Zcchc11-knockout mice, deep small RNA sequencing, reporter assays, measurement of IGF-1 mRNA and protein","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout model with deep sequencing, in vivo phenotype, and in vitro mechanistic validation across multiple methods","pmids":["23209448"],"is_preprint":false},{"year":2014,"finding":"TUT4 (Zcchc11) and TUT7 (Zcchc6) selectively 3' mono-uridylate a specific subset of mature miRNAs involved in cell differentiation and Hox gene control. A bipartite sequence motif in the miRNA is necessary and sufficient to confer Zcchc6/11-catalyzed uridylation. Loss of uridylation leads to concomitant gain of 3' mono-adenylation on the same miRNAs.","method":"In vitro uridylation assay, cell knockdown, small RNA sequencing, zebrafish TUTase inhibition with developmental phenotype readout","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — in vitro biochemical definition of substrate motif, confirmed by cell-based depletion and in vivo model","pmids":["25223788"],"is_preprint":false},{"year":2014,"finding":"Trim25, an E3 ubiquitin ligase, acts as an RNA-specific cofactor for Lin28a/TUT4-mediated uridylation. Trim25 binds the conserved terminal loop (CTL) of pre-let-7 and activates TUT4, allowing more efficient Lin28a-mediated uridylation; this provides additional substrate specificity beyond Lin28a alone.","method":"RNA pulldown coupled with quantitative mass spectrometry, co-immunoprecipitation, in vitro uridylation assay","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal pulldown and in vitro assay in single lab, two orthogonal methods","pmids":["25457611"],"is_preprint":false},{"year":2015,"finding":"Small molecule inhibitors of Zcchc11 (TUT4) TUTase activity were identified via a high-throughput biochemical screen. The study established that Zcchc11 TUTase activity is pharmacologically targetable and that uridylated pre-let-7 is targeted for decay by the downstream exonuclease Dis3l2.","method":"High-throughput enzymatic screen (~15,000 compounds), biochemical TUTase activity assay","journal":"RNA biology","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — direct biochemical assay validated with multiple inhibitors, single lab","pmids":["26114892"],"is_preprint":false},{"year":2006,"finding":"ZCCHC11 (TUT4) interacts with TIFA (TRAF-interacting protein with FHA domain) and functions as a negative regulator of TLR-mediated NF-κB activation. ZCCHC11 is mostly nuclear but translocates to the cytoplasm in response to LPS and binds TIFA. The N-terminal region containing the C2H2-type zinc finger motif is sufficient for NF-κB suppression.","method":"GST-TIFA affinity purification, mass spectrometry, siRNA knockdown, overexpression, subcellular localization by fractionation","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — affinity purification with MS identification, siRNA knockdown, and LPS-induced translocation observed; single lab","pmids":["16643855"],"is_preprint":false},{"year":2017,"finding":"TUT4 and TUT7 utilize two multidomain functional modules during the switch from monoU to oligoU addition: a catalytic module (CM) essential for both activities, and a Lin28-interacting module (LIM) indispensable for oligoU. A crystal structure of TUT7 CM trapped in the monoU state revealed a duplex-RNA-binding pocket that orients group II pre-let-7 hairpins for monoU addition. The switch to oligoU requires the ZK domain of Lin28 to drive stable ternary complex formation, and ZK2 of TUT4(7) aids oligoU addition by engaging the growing oligoU tail through uracil-specific interactions.","method":"Crystal structure of TUT7 catalytic module, domain mutants, biochemical reconstitution, in vitro uridylation assays","journal":"Nature structural & molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure combined with domain mutagenesis and reconstitution, multiple orthogonal methods in one rigorous study","pmids":["28671666"],"is_preprint":false},{"year":2018,"finding":"TUT4 and TUT7 uridylate LINE-1 mRNA 3' ends to restrict retrotransposition. TUT4 is enriched in cytoplasmic foci and destabilizes LINE-1 mRNAs, while TUT7 adds uridines in the cytoplasm to inhibit initiation of reverse transcription after mRNA reimport to the nucleus. TUT4/7 cooperate with the helicase/RNPase MOV10 to counteract the RNA chaperone activity of L1-ORF1p.","method":"TUT4/TUT7 knockdown, retrotransposition reporter assays, subcellular fractionation/localization, co-immunoprecipitation with MOV10","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple human cellular models and mouse testes, differential localization with functional consequence, MOV10 interaction, mechanistically differentiated roles for TUT4 vs TUT7","pmids":["30122351"],"is_preprint":false},{"year":2021,"finding":"TUT4(7) ZnF2 contains two distinct RNA-binding surfaces used for interactions with different RNA nucleobases in different target miRNAs, encoding diversity in TUT4(7) selectivity. Unlike other CCHC zinc fingers, ZnF2 acts independently of ZnF3. ZnF1 has lost intrinsic RNA-binding capability.","method":"NMR with functional validation, RNA-binding assays, mutagenesis of ZnF domains","journal":"RNA biology","confidence":"Medium","confidence_rationale":"Tier 1–2 / Moderate — NMR-based structural characterization with RNA-binding assays; single lab","pmids":["34719327"],"is_preprint":false},{"year":2022,"finding":"Kinetic characterization of TUT4 (Zcchc11) revealed a steady-state ordered mechanism where UTP adds before RNA. The enzyme uridylates substrates as small as dinucleotides, preferentially uridylates RNA lacking base-pairing near the 3' terminus, and shows nucleotide selectivity (UTP > CTP > ATP >> GTP) manifested in Km,XTP rather than kcat.","method":"In vitro kinetic assays, substrate titrations, nucleoside triphosphate specificity assays","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — rigorous in vitro kinetic characterization with multiple substrates and nucleotide analogs; single lab","pmids":["35797480"],"is_preprint":false},{"year":2022,"finding":"TUT4 is the predominant TUTase for uridylating most mature miRNAs, while TUT7 is largely dispensable for bulk miRNA uridylation. Loss of uridylation leads to replacement by adenylated isomiRs. TUT4/7-mediated uridylation also indirectly controls oncogenic signaling via the let-7a/AKT phosphorylation axis.","method":"CRISPR knockout of TENT2, TUT4, TUT7 individually and in combination, deep sequencing, Northern blot, in vitro assays","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — isogenic knockout cell lines with rescue, deep sequencing and Northern blot as orthogonal methods, in vitro validation","pmids":["36071058"],"is_preprint":false},{"year":2023,"finding":"TUT4 and TUT7 uridylate subgenomic RNAs of the mouse hepatitis virus (MHV coronavirus), particularly transcripts with poly(A) tails shorter than ~22 nucleotides. Depletion of TUT4/7 increases MHV replication capacity, indicating that TUT4/7-mediated uridylation marks viral subgenomic RNAs for decay and delays viral replication.","method":"Splint-ligation poly(A) tail length assay, TUT4/7 siRNA knockdown, viral replication measurement","journal":"Communications biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct measurement of viral RNA uridylation with functional knockdown phenotype; single lab, single model system","pmids":["37085578"],"is_preprint":false},{"year":2024,"finding":"In FOCAD-deleted cancer cells, TUT7 (and the downstream exonuclease DIS3L2) function as a salvage mechanism to degrade aberrant RNA. TUT4 knockout does not impair proliferation in FOCAD-deleted cells, whereas TUT7 or DIS3L2 knockout does. FOCAD deficiency post-transcriptionally disrupts SKI complex stability, creating TUT7 dependency. Selective TUT4/7 small molecule inhibitors substantially reduce uridylation and show antiproliferative activity in vitro and in vivo specifically in FOCAD-deleted cancer.","method":"CRISPR knockout, FOCAD re-expression rescue, pharmacological TUT4/7 inhibitors, in vitro and in vivo proliferation assays","journal":"Molecular cancer therapeutics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic and pharmacological evidence in multiple cancer cell lines and in vivo, but mechanistic pathway placement is partially inferred; single lab","pmids":["39235218"],"is_preprint":false},{"year":2026,"finding":"Cryo-EM structure of human TUT4 complexed with Lin28A and oligo-uridylated pre-let-7 at the elongation stage revealed that: (1) the Lin28-interacting module (LIM) anchors pre-let-7 via Lin28A interactions with the terminal stem-loop; (2) the catalytic module (CM) associates with LIM through protein-protein interactions; (3) the duplex stem region of pre-let-7 is surrounded by CM and LIM, with the upper portion unwinding to position the 3' end in the CM catalytic site; (4) during processive oligo-uridylation, the CM finger domain clamps the double-stranded region, further stabilizing the complex.","method":"Cryo-EM structure determination, biochemical analysis of TUT4–Lin28A–pre-let-7 ternary complex","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 / Strong — high-resolution cryo-EM structure with biochemical validation of mechanism, multiple structural states characterized","pmids":["41521656"],"is_preprint":false},{"year":2025,"finding":"In the ZAP-mediated RNA decay pathway, the 5' cleavage fragment generated by KHNYN endonuclease undergoes TUT4/TUT7-mediated 3' uridylation followed by degradation by DIS3L2. ZAP and TRIM25 interact with TUT7, DIS3L2, and XRN1 in an RNase-resistant manner, and viral infection promotes these interactions to drive viral RNA decay.","method":"Co-immunoprecipitation, RNase-resistant interaction assays, viral RNA decay measurement","journal":"bioRxiv","confidence":"Low","confidence_rationale":"Tier 3 / Weak — preprint, single lab, co-IP without in vitro reconstitution specific to TUT4","pmids":[],"is_preprint":true}],"current_model":"TUT4 (Zcchc11/ZCCHC11/TENT3A) is a cytoplasmic non-canonical poly(U) polymerase that catalyzes 3' uridylation of diverse RNA substrates—including pre-let-7 and other pre-miRNAs (in a Lin28-dependent manner that blocks Dicer processing and triggers DIS3L2-mediated decay), mature miRNAs (modulating their silencing activity), replication-dependent histone mRNAs (targeting them for decay), and LINE-1 retrotransposon mRNAs (restricting retrotransposition)—acting through a structurally characterized two-module mechanism (catalytic module plus Lin28-interacting module) and additionally functioning as a negative regulator of TLR/NF-κB signaling and a promoter of cell cycle G1/S transition through an enzymatic-activity-independent N-terminal domain."},"narrative":{"mechanistic_narrative":"TUT4 (Zcchc11/ZCCHC11/TENT3A) is a cytoplasmic non-canonical terminal uridylyl transferase that adds 3' uridine tails to a broad range of RNA substrates to control their fate and silencing activity [PMID:19703396, PMID:19701194, PMID:35797480]. Its best-characterized role is in let-7 microRNA biogenesis: TUT4 is recruited by Lin28 to a GGAG motif in the terminal loop of pre-let-7 and oligo-uridylates the precursor, blocking Dicer processing and marking the transcript for decay by the exonuclease DIS3L2 [PMID:19703396, PMID:19713958, PMID:26114892]. Beyond pre-let-7, TUT4 uridylates a defined subset of mature miRNAs through a bipartite sequence motif, an event that does not change miRNA abundance but relieves miRNA-mediated silencing of targets such as IL-6 and IGF-1 mRNAs, linking TUT4 to cytokine output and postnatal growth [PMID:19701194, PMID:23209448, PMID:25223788]; it is the predominant TUTase for bulk mature-miRNA uridylation, with loss of uridylation replaced by adenylated isomiRs [PMID:36071058]. TUT4 also uridylates replication-dependent histone mRNAs to target them for degradation after DNA replication [PMID:21051505], and restricts LINE-1 retrotransposition and viral RNAs by uridylating their 3' ends to promote decay [PMID:30122351, PMID:37085578]. Mechanistically, TUT4 operates through two modules — a catalytic module (CM) and a Lin28-interacting module (LIM) — that switch the enzyme from mono-U to processive oligo-U addition; structural work defined how Lin28 drives ternary complex formation, how the CM finger clamps the duplex stem of pre-let-7 during elongation, and how the enzyme follows an ordered kinetic mechanism with UTP binding before RNA and strong selectivity for UTP [PMID:28671666, PMID:35797480, PMID:41521656]. Distinct from its enzymatic functions, TUT4 acts through an N-terminal C2H2 zinc-finger region as a negative regulator of TLR/NF-κB signaling via TIFA and as a uridyltransferase-independent promoter of G1/S cell cycle progression [PMID:22006926, PMID:16643855].","teleology":[{"year":2009,"claim":"Established TUT4 as the enzyme that executes Lin28-directed pre-let-7 uridylation, answering how Lin28 blocks let-7 maturation at the molecular level.","evidence":"Biochemical identification, knockdown, catalytically inactive mutant, and in vitro uridylation assays in mouse ES cells, replicated by two labs","pmids":["19703396","19713958"],"confidence":"High","gaps":["Did not resolve the fate of uridylated pre-let-7 (decay enzyme unknown at this stage)","Did not define domain requirements for Lin28 interaction"]},{"year":2009,"claim":"Extended TUT4 activity to mature miRNAs, showing uridylation of miR-26a as a mechanism to control cytokine output.","evidence":"Knockdown, small RNA sequencing, and in vitro nucleotidyltransferase assay with IL-6 readout","pmids":["19701194"],"confidence":"High","gaps":["Did not define the sequence determinants distinguishing uridylated mature miRNAs","Mechanism by which uridylation alters silencing not resolved"]},{"year":2010,"claim":"Identified histone mRNAs as a non-miRNA substrate class, showing uridylation couples to mRNA decay after DNA replication.","evidence":"siRNA knockdown with direct detection of uridylated histone transcripts and degradation assays","pmids":["21051505"],"confidence":"High","gaps":["Downstream decay machinery for uridylated histone mRNAs not identified","Trigger linking replication status to uridylation not defined"]},{"year":2011,"claim":"Revealed a catalysis-independent function: an N-terminal region of TUT4 promotes G1/S progression independent of uridyltransferase activity.","evidence":"Knockdown, overexpression, catalytic point and truncation mutants, cell cycle analysis","pmids":["22006926"],"confidence":"Medium","gaps":["Direct molecular partners of the N-terminal region in cell cycle control not identified","Single-lab finding without orthogonal mechanistic validation"]},{"year":2012,"claim":"Mapped the Lin28 interaction to a single C2H2 zinc finger and showed TUT7 acts redundantly, clarifying the determinants of let-7 control.","evidence":"Domain truncation, reconstitution assays, and ES cell knockdown","pmids":["22898984"],"confidence":"High","gaps":["Did not provide atomic structure of the zinc finger-Lin28 interface","Relative contributions of TUT4 vs TUT7 in other tissues unresolved"]},{"year":2012,"claim":"Demonstrated in vivo physiological relevance: mature-miRNA uridylation relieves silencing of IGF-1 to support postnatal growth.","evidence":"Zcchc11-knockout mice with deep small RNA sequencing, reporter assays, and IGF-1 measurements","pmids":["23209448"],"confidence":"High","gaps":["Molecular mechanism by which uridylation reduces silencing capacity not fully resolved","Full set of physiologically relevant miRNA targets undefined"]},{"year":2014,"claim":"Defined substrate specificity for mature-miRNA uridylation through a bipartite RNA motif and identified TRIM25 as an RNA-specific cofactor enhancing pre-let-7 uridylation.","evidence":"In vitro uridylation with motif mapping, zebrafish developmental readout; RNA pulldown/MS and co-IP for TRIM25","pmids":["25223788","25457611"],"confidence":"High","gaps":["Structural basis of TRIM25 activation of TUT4 not resolved","Generality of TRIM25 cofactor role across substrates unknown"]},{"year":2017,"claim":"Provided the structural and mechanistic basis for the mono-U to oligo-U switch, defining the catalytic and Lin28-interacting modules.","evidence":"Crystal structure of TUT7 catalytic module in monoU state, domain mutants, and in vitro reconstitution","pmids":["28671666"],"confidence":"High","gaps":["Full ternary complex during processive elongation not captured at this stage","Conformational dynamics of the switch inferred rather than directly observed"]},{"year":2018,"claim":"Established TUT4 as a host restriction factor for LINE-1 retrotransposition, with divergent cytoplasmic roles for TUT4 vs TUT7 and cooperation with MOV10.","evidence":"Knockdown, retrotransposition reporter assays, subcellular localization, and co-IP with MOV10 in human cells and mouse testes","pmids":["30122351"],"confidence":"High","gaps":["Precise determinants directing TUT4 to LINE-1 mRNA not defined","Mechanistic interplay between uridylation and MOV10 RNPase activity incomplete"]},{"year":2022,"claim":"Refined the enzymatic and selectivity logic: kinetic ordered mechanism and zinc-finger surfaces underlying substrate diversity, plus establishment of TUT4 as the dominant bulk-miRNA uridylase.","evidence":"In vitro kinetics and nucleotide specificity assays; NMR of ZnF2 RNA-binding surfaces; CRISPR knockouts of TENT2/TUT4/TUT7 with deep sequencing","pmids":["35797480","34719327","36071058"],"confidence":"High","gaps":["How distinct ZnF2 surfaces are deployed on specific targets in cells not directly observed","Cellular consequences of let-7a/AKT axis modulation only partially characterized"]},{"year":2023,"claim":"Extended TUT4 antiviral surveillance to coronavirus subgenomic RNAs with short poly(A) tails, marking them for decay.","evidence":"Splint-ligation poly(A) length assay, siRNA knockdown, and viral replication measurement for MHV","pmids":["37085578"],"confidence":"Medium","gaps":["Single virus model; generality across coronaviruses untested","Decay enzyme acting on uridylated viral RNA not directly identified in this study"]},{"year":2024,"claim":"Distinguished TUT4 from TUT7 in a synthetic-lethal cancer context, establishing TUT4/7 uridylation as a pharmacologically targetable RNA salvage pathway.","evidence":"CRISPR knockout, FOCAD re-expression rescue, and selective TUT4/7 inhibitors in vitro and in vivo","pmids":["39235218"],"confidence":"Medium","gaps":["Why TUT7 but not TUT4 is required in FOCAD-deleted cells mechanistically unclear","Single-lab pathway placement partially inferred"]},{"year":2026,"claim":"Captured the elongation-stage ternary complex, resolving how Lin28 anchoring and CM-LIM cooperation enable processive oligo-uridylation of pre-let-7.","evidence":"Cryo-EM of human TUT4-Lin28A-pre-let-7 with biochemical validation","pmids":["41521656"],"confidence":"High","gaps":["Structural basis for substrate selection beyond pre-let-7 not addressed","Dynamics of repeated UTP incorporation cycles inferred from static states"]},{"year":null,"claim":"How TUT4's catalysis-independent N-terminal functions (cell cycle, NF-κB regulation) integrate mechanistically with its RNA uridylation activity remains unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural or interaction map linking the N-terminal zinc-finger region to cell cycle effectors","Whether enzymatic and non-enzymatic activities operate in the same cellular contexts is unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140098","term_label":"catalytic activity, acting on RNA","supporting_discovery_ids":[0,1,2,3,14]},{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,1,2,14]},{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[7,13,14]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[3,12]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[10]}],"pathway":[{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[0,2,3,7,15]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[4]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[2,10,12,16]}],"complexes":[],"partners":["LIN28A","TUT7","TRIM25","TIFA","MOV10","DIS3L2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q5TAX3","full_name":"Terminal uridylyltransferase 4","aliases":["Zinc finger CCHC domain-containing protein 11"],"length_aa":1644,"mass_kda":185.2,"function":"Uridylyltransferase that mediates the terminal uridylation of mRNAs with short (less than 25 nucleotides) poly(A) tails, hence facilitating global mRNA decay (PubMed:25480299, PubMed:31036859). Essential for both oocyte maturation and fertility. Through 3' terminal uridylation of mRNA, sculpts, with TUT7, the maternal transcriptome by eliminating transcripts during oocyte growth (By similarity). Involved in microRNA (miRNA)-induced gene silencing through uridylation of deadenylated miRNA targets. Also functions as an integral regulator of microRNA biogenesis using 3 different uridylation mechanisms (PubMed:25979828). Acts as a suppressor of miRNA biogenesis by mediating the terminal uridylation of some miRNA precursors, including that of let-7 (pre-let-7), miR107, miR-143 and miR-200c. Uridylated miRNAs are not processed by Dicer and undergo degradation. Degradation of pre-let-7 contributes to the maintenance of embryonic stem (ES) cell pluripotency (By similarity). Also catalyzes the 3' uridylation of miR-26A, a miRNA that targets IL6 transcript. This abrogates the silencing of IL6 transcript, hence promoting cytokine expression (PubMed:19703396). In the absence of LIN28A, TUT7 and TUT4 monouridylate group II pre-miRNAs, which includes most of pre-let7 members, that shapes an optimal 3' end overhang for efficient processing (PubMed:25979828). Adds oligo-U tails to truncated pre-miRNAS with a 5' overhang which may promote rapid degradation of non-functional pre-miRNA species (PubMed:25979828). May also suppress Toll-like receptor-induced NF-kappa-B activation via binding to T2BP (PubMed:16643855). Does not play a role in replication-dependent histone mRNA degradation (PubMed:18172165). Due to functional redundancy between TUT4 and TUT7, the identification of the specific role of each of these proteins is difficult (By similarity) (PubMed:16643855, PubMed:18172165, PubMed:19703396, PubMed:25480299, PubMed:25979828). TUT4 and TUT7 restrict retrotransposition of long interspersed element-1 (LINE-1) in cooperation with MOV10 counteracting the RNA chaperonne activity of L1RE1. TUT7 uridylates LINE-1 mRNAs in the cytoplasm which inhibits initiation of reverse transcription once in the nucleus, whereas uridylation by TUT4 destabilizes mRNAs in cytoplasmic ribonucleoprotein granules (PubMed:30122351)","subcellular_location":"Nucleus; Cytoplasm; Cytoplasm, Cytoplasmic ribonucleoprotein granule","url":"https://www.uniprot.org/uniprotkb/Q5TAX3/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/TUT4","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"FKBP5","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/TUT4","total_profiled":1310},"omim":[{"mim_id":"613692","title":"TERMINAL URIDYLYL TRANSFERASE 4; TUT4","url":"https://www.omim.org/entry/613692"},{"mim_id":"613467","title":"ZINC FINGER CCHC DOMAIN-CONTAINING PROTEIN 6; ZCCHC6","url":"https://www.omim.org/entry/613467"},{"mim_id":"611043","title":"LIN28 HOMOLOG A; LIN28A","url":"https://www.omim.org/entry/611043"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Cytosol","reliability":"Supported"},{"location":"Nucleoli","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/TUT4"},"hgnc":{"alias_symbol":["KIAA0191","PAPD3","TENT3A"],"prev_symbol":["ZCCHC11"]},"alphafold":{"accession":"Q5TAX3","domains":[{"cath_id":"-","chopping":"285-344","consensus_level":"medium","plddt":88.4272,"start":285,"end":344},{"cath_id":"1.10.1410.10","chopping":"350-572_612-709","consensus_level":"medium","plddt":92.7077,"start":350,"end":709},{"cath_id":"1.10.1410.10","chopping":"933-1026_1075-1308","consensus_level":"medium","plddt":91.4699,"start":933,"end":1308}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q5TAX3","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q5TAX3-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q5TAX3-F1-predicted_aligned_error_v6.png","plddt_mean":62.88},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=TUT4","jax_strain_url":"https://www.jax.org/strain/search?query=TUT4"},"sequence":{"accession":"Q5TAX3","fasta_url":"https://rest.uniprot.org/uniprotkb/Q5TAX3.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q5TAX3/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q5TAX3"}},"corpus_meta":[{"pmid":"19703396","id":"PMC_19703396","title":"TUT4 in concert with Lin28 suppresses microRNA biogenesis through pre-microRNA uridylation.","date":"2009","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/19703396","citation_count":669,"is_preprint":false},{"pmid":"19713958","id":"PMC_19713958","title":"Lin28 recruits the TUTase Zcchc11 to inhibit let-7 maturation in mouse embryonic stem cells.","date":"2009","source":"Nature structural & molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/19713958","citation_count":423,"is_preprint":false},{"pmid":"19701194","id":"PMC_19701194","title":"Zcchc11-dependent uridylation of microRNA directs cytokine expression.","date":"2009","source":"Nature cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/19701194","citation_count":248,"is_preprint":false},{"pmid":"22898984","id":"PMC_22898984","title":"Lin28-mediated control of let-7 microRNA expression by alternative TUTases Zcchc11 (TUT4) and Zcchc6 (TUT7).","date":"2012","source":"RNA (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/22898984","citation_count":176,"is_preprint":false},{"pmid":"24056962","id":"PMC_24056962","title":"miR-26a enhances miRNA biogenesis by targeting Lin28B and Zcchc11 to suppress tumor growth and metastasis.","date":"2013","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/24056962","citation_count":100,"is_preprint":false},{"pmid":"21051505","id":"PMC_21051505","title":"The human cytoplasmic RNA terminal U-transferase ZCCHC11 targets histone mRNAs for degradation.","date":"2010","source":"RNA (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/21051505","citation_count":86,"is_preprint":false},{"pmid":"25223788","id":"PMC_25223788","title":"Selective microRNA uridylation by Zcchc6 (TUT7) and Zcchc11 (TUT4).","date":"2014","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/25223788","citation_count":85,"is_preprint":false},{"pmid":"30122351","id":"PMC_30122351","title":"Uridylation by TUT4/7 Restricts Retrotransposition of Human LINE-1s.","date":"2018","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/30122351","citation_count":74,"is_preprint":false},{"pmid":"25457611","id":"PMC_25457611","title":"Trim25 Is an RNA-Specific Activator of Lin28a/TuT4-Mediated Uridylation.","date":"2014","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/25457611","citation_count":71,"is_preprint":false},{"pmid":"23209448","id":"PMC_23209448","title":"Zcchc11 uridylates mature miRNAs to enhance neonatal IGF-1 expression, growth, and survival.","date":"2012","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/23209448","citation_count":46,"is_preprint":false},{"pmid":"28671666","id":"PMC_28671666","title":"Multi-domain utilization by TUT4 and TUT7 in control of let-7 biogenesis.","date":"2017","source":"Nature structural & molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/28671666","citation_count":45,"is_preprint":false},{"pmid":"36071058","id":"PMC_36071058","title":"TENT2, TUT4, and TUT7 selectively regulate miRNA sequence and abundance.","date":"2022","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/36071058","citation_count":44,"is_preprint":false},{"pmid":"26114892","id":"PMC_26114892","title":"Identification of small molecule inhibitors of Zcchc11 TUTase activity.","date":"2015","source":"RNA biology","url":"https://pubmed.ncbi.nlm.nih.gov/26114892","citation_count":43,"is_preprint":false},{"pmid":"16643855","id":"PMC_16643855","title":"A novel Zinc finger protein, ZCCHC11, interacts with TIFA and modulates TLR signaling.","date":"2006","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/16643855","citation_count":41,"is_preprint":false},{"pmid":"22006926","id":"PMC_22006926","title":"Terminal uridyltransferase enzyme Zcchc11 promotes cell proliferation independent of its uridyltransferase activity.","date":"2011","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/22006926","citation_count":16,"is_preprint":false},{"pmid":"21453498","id":"PMC_21453498","title":"E2F1 and KIAA0191 expression predicts breast cancer patient survival.","date":"2011","source":"BMC research notes","url":"https://pubmed.ncbi.nlm.nih.gov/21453498","citation_count":14,"is_preprint":false},{"pmid":"37085578","id":"PMC_37085578","title":"TUT4/7-mediated uridylation of a coronavirus subgenomic RNAs delays viral replication.","date":"2023","source":"Communications biology","url":"https://pubmed.ncbi.nlm.nih.gov/37085578","citation_count":13,"is_preprint":false},{"pmid":"34949722","id":"PMC_34949722","title":"RNA uridyl transferases TUT4/7 differentially regulate miRNA variants depending on the cancer cell type.","date":"2021","source":"RNA (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/34949722","citation_count":12,"is_preprint":false},{"pmid":"36497000","id":"PMC_36497000","title":"Terminal Uridylyltransferases TUT4/7 Regulate microRNA and mRNA Homeostasis.","date":"2022","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/36497000","citation_count":8,"is_preprint":false},{"pmid":"39235218","id":"PMC_39235218","title":"Targeting the Synthetic Lethal Relationship between FOCAD and TUT7 Represents a Potential Therapeutic Opportunity for TUT4/7 Small-Molecule Inhibitors in Cancer.","date":"2024","source":"Molecular cancer therapeutics","url":"https://pubmed.ncbi.nlm.nih.gov/39235218","citation_count":5,"is_preprint":false},{"pmid":"36324561","id":"PMC_36324561","title":"Differentially Expressed mRNAs and Potential Mechanisms of Radiation-Induced TUT4-/- Esophageal Cell Injury.","date":"2022","source":"Dose-response : a publication of International Hormesis Society","url":"https://pubmed.ncbi.nlm.nih.gov/36324561","citation_count":3,"is_preprint":false},{"pmid":"35797480","id":"PMC_35797480","title":"Kinetic and Mechanistic Studies of the Terminal Uridylyltransferase, Zcchc11 (TUT4).","date":"2022","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/35797480","citation_count":2,"is_preprint":false},{"pmid":"34719327","id":"PMC_34719327","title":"The distinct RNA-interaction modes of a small ZnF domain underlay TUT4(7) diverse action in miRNA regulation.","date":"2021","source":"RNA biology","url":"https://pubmed.ncbi.nlm.nih.gov/34719327","citation_count":1,"is_preprint":false},{"pmid":"40933885","id":"PMC_40933885","title":"Potential protective regulatory effects on radiation-induced esophageal injury in TUT4-/- mice.","date":"2025","source":"Frontiers in oncology","url":"https://pubmed.ncbi.nlm.nih.gov/40933885","citation_count":0,"is_preprint":false},{"pmid":"41521656","id":"PMC_41521656","title":"Mechanistic insights into Lin28-dependent oligo-uridylylation of pre-let-7 by TUT4.","date":"2026","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/41521656","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.05.12.650695","title":"HENMT1 restricts endogenous retrovirus activity by methylation of 3’-tRNA fragments","date":"2025-05-12","source":"bioRxiv","url":"https://doi.org/10.1101/2025.05.12.650695","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.04.28.650959","title":"The long isoform of ZAP coordinates multiple enzymes to mediate complete decay of target transcripts","date":"2025-05-01","source":"bioRxiv","url":"https://doi.org/10.1101/2025.04.28.650959","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":14298,"output_tokens":5185,"usd":0.060334,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":13461,"output_tokens":4258,"usd":0.086877,"stage2_stop_reason":"end_turn"},"total_usd":0.147211,"stage1_batch_id":"msgbatch_017qqVz33Ga63SCDwzb35XPb","stage2_batch_id":"msgbatch_01Scr2Ei9x4HJMiRGxwrmvLK","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2009,\n      \"finding\": \"TUT4 (TUTase4) was identified as the uridylyl transferase responsible for adding oligouridine tails to pre-let-7, thereby blocking Dicer processing. Lin28 recruits TUT4 to pre-let-7 by recognizing a tetra-nucleotide sequence motif (GGAG) in the terminal loop of the precursor.\",\n      \"method\": \"Biochemical identification, knockdown experiments, in vitro uridylation assays\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — in vitro uridylation assay with functional validation, replicated independently in the same year by a second lab (PMID:19713958)\",\n      \"pmids\": [\"19703396\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Zcchc11 (TUT4) is the 3' terminal uridylyl transferase responsible for Lin28-mediated pre-let-7 uridylation in mouse embryonic stem cells. The activity is UTP-dependent and selective for let-7 precursors. Knockdown of Zcchc11 or overexpression of a catalytically inactive TUTase relieves inhibition of let-7 processing, leading to accumulation of mature let-7 and repression of let-7 target reporter genes.\",\n      \"method\": \"Knockdown, overexpression of catalytically inactive mutant, in vitro uridylation assay, reporter gene assay\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — catalytic mutant validation, multiple orthogonal methods, independent replication of PMID:19703396\",\n      \"pmids\": [\"19713958\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Zcchc11 (TUT4) is a ribonucleotidyltransferase with preference for uridine that uridylates mature miR-26a at its 3' end, abrogating IL-6 repression by miR-26a and thereby promoting IL-6 mRNA stability and expression.\",\n      \"method\": \"Knockdown, small RNA sequencing, poly(A) tail length assay, in vitro nucleotidyltransferase assay\",\n      \"journal\": \"Nature cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — direct enzymatic assay combined with knockdown and sequencing showing uridylation of mature miRNA, with functional cytokine output measured\",\n      \"pmids\": [\"19701194\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"ZCCHC11 (TUT4) is the cytoplasmic terminal U-transferase responsible for 3' uridylation of replication-dependent histone mRNAs, targeting them for degradation following inhibition or completion of DNA replication. Knockdown of ZCCHC11 selectively blocked histone mRNA degradation and reduced the proportion of uridylated histone transcripts.\",\n      \"method\": \"siRNA knockdown, detection of uridylated histone mRNAs, degradation assays\",\n      \"journal\": \"RNA (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — specific knockdown phenotype with direct measurement of uridylation levels and mRNA degradation in a single focused study\",\n      \"pmids\": [\"21051505\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Zcchc11 (TUT4) promotes G1-to-S phase cell cycle progression by increasing expression of cyclins D1 and A and CDK4, through both Rb-dependent and Rb-independent mechanisms. Importantly, this proliferative activity is independent of its uridyltransferase activity, as a catalytically inactive point mutant retains full effect, and is driven by the N-terminal region of the protein lacking RNA-binding and uridyltransferase domains.\",\n      \"method\": \"Loss-of-function (knockdown), gain-of-function (overexpression), catalytic domain point mutants, truncation mutants, cell cycle analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple mutant constructs and cell cycle readouts in a single lab\",\n      \"pmids\": [\"22006926\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"A single C2H2-type zinc finger domain of Zcchc11 (TUT4) is responsible for the functional interaction with Lin28, enabling Lin28-enhanced pre-let-7 uridylation. Zcchc6 (TUT7) functions redundantly with Zcchc11 in Lin28-mediated let-7 biogenesis control in embryonic stem cells.\",\n      \"method\": \"Biochemical dissection, domain truncation, reconstitution assays, embryonic stem cell knockdown\",\n      \"journal\": \"RNA (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — reconstitution and biochemical domain mapping with multiple constructs, functional validation in stem cells\",\n      \"pmids\": [\"22898984\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Zcchc11 (TUT4) mediates terminal uridylation of diverse mature miRNAs in neonatal mouse liver. This uridylation does not alter miRNA abundance but relieves miRNA-mediated silencing of IGF-1 mRNA, leading to enhanced IGF-1 expression that is required for postnatal growth and survival.\",\n      \"method\": \"Zcchc11-knockout mice, deep small RNA sequencing, reporter assays, measurement of IGF-1 mRNA and protein\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout model with deep sequencing, in vivo phenotype, and in vitro mechanistic validation across multiple methods\",\n      \"pmids\": [\"23209448\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"TUT4 (Zcchc11) and TUT7 (Zcchc6) selectively 3' mono-uridylate a specific subset of mature miRNAs involved in cell differentiation and Hox gene control. A bipartite sequence motif in the miRNA is necessary and sufficient to confer Zcchc6/11-catalyzed uridylation. Loss of uridylation leads to concomitant gain of 3' mono-adenylation on the same miRNAs.\",\n      \"method\": \"In vitro uridylation assay, cell knockdown, small RNA sequencing, zebrafish TUTase inhibition with developmental phenotype readout\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — in vitro biochemical definition of substrate motif, confirmed by cell-based depletion and in vivo model\",\n      \"pmids\": [\"25223788\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Trim25, an E3 ubiquitin ligase, acts as an RNA-specific cofactor for Lin28a/TUT4-mediated uridylation. Trim25 binds the conserved terminal loop (CTL) of pre-let-7 and activates TUT4, allowing more efficient Lin28a-mediated uridylation; this provides additional substrate specificity beyond Lin28a alone.\",\n      \"method\": \"RNA pulldown coupled with quantitative mass spectrometry, co-immunoprecipitation, in vitro uridylation assay\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal pulldown and in vitro assay in single lab, two orthogonal methods\",\n      \"pmids\": [\"25457611\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Small molecule inhibitors of Zcchc11 (TUT4) TUTase activity were identified via a high-throughput biochemical screen. The study established that Zcchc11 TUTase activity is pharmacologically targetable and that uridylated pre-let-7 is targeted for decay by the downstream exonuclease Dis3l2.\",\n      \"method\": \"High-throughput enzymatic screen (~15,000 compounds), biochemical TUTase activity assay\",\n      \"journal\": \"RNA biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct biochemical assay validated with multiple inhibitors, single lab\",\n      \"pmids\": [\"26114892\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"ZCCHC11 (TUT4) interacts with TIFA (TRAF-interacting protein with FHA domain) and functions as a negative regulator of TLR-mediated NF-κB activation. ZCCHC11 is mostly nuclear but translocates to the cytoplasm in response to LPS and binds TIFA. The N-terminal region containing the C2H2-type zinc finger motif is sufficient for NF-κB suppression.\",\n      \"method\": \"GST-TIFA affinity purification, mass spectrometry, siRNA knockdown, overexpression, subcellular localization by fractionation\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — affinity purification with MS identification, siRNA knockdown, and LPS-induced translocation observed; single lab\",\n      \"pmids\": [\"16643855\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"TUT4 and TUT7 utilize two multidomain functional modules during the switch from monoU to oligoU addition: a catalytic module (CM) essential for both activities, and a Lin28-interacting module (LIM) indispensable for oligoU. A crystal structure of TUT7 CM trapped in the monoU state revealed a duplex-RNA-binding pocket that orients group II pre-let-7 hairpins for monoU addition. The switch to oligoU requires the ZK domain of Lin28 to drive stable ternary complex formation, and ZK2 of TUT4(7) aids oligoU addition by engaging the growing oligoU tail through uracil-specific interactions.\",\n      \"method\": \"Crystal structure of TUT7 catalytic module, domain mutants, biochemical reconstitution, in vitro uridylation assays\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure combined with domain mutagenesis and reconstitution, multiple orthogonal methods in one rigorous study\",\n      \"pmids\": [\"28671666\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"TUT4 and TUT7 uridylate LINE-1 mRNA 3' ends to restrict retrotransposition. TUT4 is enriched in cytoplasmic foci and destabilizes LINE-1 mRNAs, while TUT7 adds uridines in the cytoplasm to inhibit initiation of reverse transcription after mRNA reimport to the nucleus. TUT4/7 cooperate with the helicase/RNPase MOV10 to counteract the RNA chaperone activity of L1-ORF1p.\",\n      \"method\": \"TUT4/TUT7 knockdown, retrotransposition reporter assays, subcellular fractionation/localization, co-immunoprecipitation with MOV10\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple human cellular models and mouse testes, differential localization with functional consequence, MOV10 interaction, mechanistically differentiated roles for TUT4 vs TUT7\",\n      \"pmids\": [\"30122351\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"TUT4(7) ZnF2 contains two distinct RNA-binding surfaces used for interactions with different RNA nucleobases in different target miRNAs, encoding diversity in TUT4(7) selectivity. Unlike other CCHC zinc fingers, ZnF2 acts independently of ZnF3. ZnF1 has lost intrinsic RNA-binding capability.\",\n      \"method\": \"NMR with functional validation, RNA-binding assays, mutagenesis of ZnF domains\",\n      \"journal\": \"RNA biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — NMR-based structural characterization with RNA-binding assays; single lab\",\n      \"pmids\": [\"34719327\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Kinetic characterization of TUT4 (Zcchc11) revealed a steady-state ordered mechanism where UTP adds before RNA. The enzyme uridylates substrates as small as dinucleotides, preferentially uridylates RNA lacking base-pairing near the 3' terminus, and shows nucleotide selectivity (UTP > CTP > ATP >> GTP) manifested in Km,XTP rather than kcat.\",\n      \"method\": \"In vitro kinetic assays, substrate titrations, nucleoside triphosphate specificity assays\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — rigorous in vitro kinetic characterization with multiple substrates and nucleotide analogs; single lab\",\n      \"pmids\": [\"35797480\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"TUT4 is the predominant TUTase for uridylating most mature miRNAs, while TUT7 is largely dispensable for bulk miRNA uridylation. Loss of uridylation leads to replacement by adenylated isomiRs. TUT4/7-mediated uridylation also indirectly controls oncogenic signaling via the let-7a/AKT phosphorylation axis.\",\n      \"method\": \"CRISPR knockout of TENT2, TUT4, TUT7 individually and in combination, deep sequencing, Northern blot, in vitro assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — isogenic knockout cell lines with rescue, deep sequencing and Northern blot as orthogonal methods, in vitro validation\",\n      \"pmids\": [\"36071058\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"TUT4 and TUT7 uridylate subgenomic RNAs of the mouse hepatitis virus (MHV coronavirus), particularly transcripts with poly(A) tails shorter than ~22 nucleotides. Depletion of TUT4/7 increases MHV replication capacity, indicating that TUT4/7-mediated uridylation marks viral subgenomic RNAs for decay and delays viral replication.\",\n      \"method\": \"Splint-ligation poly(A) tail length assay, TUT4/7 siRNA knockdown, viral replication measurement\",\n      \"journal\": \"Communications biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct measurement of viral RNA uridylation with functional knockdown phenotype; single lab, single model system\",\n      \"pmids\": [\"37085578\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"In FOCAD-deleted cancer cells, TUT7 (and the downstream exonuclease DIS3L2) function as a salvage mechanism to degrade aberrant RNA. TUT4 knockout does not impair proliferation in FOCAD-deleted cells, whereas TUT7 or DIS3L2 knockout does. FOCAD deficiency post-transcriptionally disrupts SKI complex stability, creating TUT7 dependency. Selective TUT4/7 small molecule inhibitors substantially reduce uridylation and show antiproliferative activity in vitro and in vivo specifically in FOCAD-deleted cancer.\",\n      \"method\": \"CRISPR knockout, FOCAD re-expression rescue, pharmacological TUT4/7 inhibitors, in vitro and in vivo proliferation assays\",\n      \"journal\": \"Molecular cancer therapeutics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic and pharmacological evidence in multiple cancer cell lines and in vivo, but mechanistic pathway placement is partially inferred; single lab\",\n      \"pmids\": [\"39235218\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Cryo-EM structure of human TUT4 complexed with Lin28A and oligo-uridylated pre-let-7 at the elongation stage revealed that: (1) the Lin28-interacting module (LIM) anchors pre-let-7 via Lin28A interactions with the terminal stem-loop; (2) the catalytic module (CM) associates with LIM through protein-protein interactions; (3) the duplex stem region of pre-let-7 is surrounded by CM and LIM, with the upper portion unwinding to position the 3' end in the CM catalytic site; (4) during processive oligo-uridylation, the CM finger domain clamps the double-stranded region, further stabilizing the complex.\",\n      \"method\": \"Cryo-EM structure determination, biochemical analysis of TUT4–Lin28A–pre-let-7 ternary complex\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — high-resolution cryo-EM structure with biochemical validation of mechanism, multiple structural states characterized\",\n      \"pmids\": [\"41521656\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In the ZAP-mediated RNA decay pathway, the 5' cleavage fragment generated by KHNYN endonuclease undergoes TUT4/TUT7-mediated 3' uridylation followed by degradation by DIS3L2. ZAP and TRIM25 interact with TUT7, DIS3L2, and XRN1 in an RNase-resistant manner, and viral infection promotes these interactions to drive viral RNA decay.\",\n      \"method\": \"Co-immunoprecipitation, RNase-resistant interaction assays, viral RNA decay measurement\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — preprint, single lab, co-IP without in vitro reconstitution specific to TUT4\",\n      \"pmids\": [],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"TUT4 (Zcchc11/ZCCHC11/TENT3A) is a cytoplasmic non-canonical poly(U) polymerase that catalyzes 3' uridylation of diverse RNA substrates—including pre-let-7 and other pre-miRNAs (in a Lin28-dependent manner that blocks Dicer processing and triggers DIS3L2-mediated decay), mature miRNAs (modulating their silencing activity), replication-dependent histone mRNAs (targeting them for decay), and LINE-1 retrotransposon mRNAs (restricting retrotransposition)—acting through a structurally characterized two-module mechanism (catalytic module plus Lin28-interacting module) and additionally functioning as a negative regulator of TLR/NF-κB signaling and a promoter of cell cycle G1/S transition through an enzymatic-activity-independent N-terminal domain.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"TUT4 (Zcchc11/ZCCHC11/TENT3A) is a cytoplasmic non-canonical terminal uridylyl transferase that adds 3' uridine tails to a broad range of RNA substrates to control their fate and silencing activity [#0, #2, #14]. Its best-characterized role is in let-7 microRNA biogenesis: TUT4 is recruited by Lin28 to a GGAG motif in the terminal loop of pre-let-7 and oligo-uridylates the precursor, blocking Dicer processing and marking the transcript for decay by the exonuclease DIS3L2 [#0, #1, #9]. Beyond pre-let-7, TUT4 uridylates a defined subset of mature miRNAs through a bipartite sequence motif, an event that does not change miRNA abundance but relieves miRNA-mediated silencing of targets such as IL-6 and IGF-1 mRNAs, linking TUT4 to cytokine output and postnatal growth [#2, #6, #7]; it is the predominant TUTase for bulk mature-miRNA uridylation, with loss of uridylation replaced by adenylated isomiRs [#15]. TUT4 also uridylates replication-dependent histone mRNAs to target them for degradation after DNA replication [#3], and restricts LINE-1 retrotransposition and viral RNAs by uridylating their 3' ends to promote decay [#12, #16]. Mechanistically, TUT4 operates through two modules — a catalytic module (CM) and a Lin28-interacting module (LIM) — that switch the enzyme from mono-U to processive oligo-U addition; structural work defined how Lin28 drives ternary complex formation, how the CM finger clamps the duplex stem of pre-let-7 during elongation, and how the enzyme follows an ordered kinetic mechanism with UTP binding before RNA and strong selectivity for UTP [#11, #14, #18]. Distinct from its enzymatic functions, TUT4 acts through an N-terminal C2H2 zinc-finger region as a negative regulator of TLR/NF-\\u03baB signaling via TIFA and as a uridyltransferase-independent promoter of G1/S cell cycle progression [#4, #10].\",\n  \"teleology\": [\n    {\n      \"year\": 2009,\n      \"claim\": \"Established TUT4 as the enzyme that executes Lin28-directed pre-let-7 uridylation, answering how Lin28 blocks let-7 maturation at the molecular level.\",\n      \"evidence\": \"Biochemical identification, knockdown, catalytically inactive mutant, and in vitro uridylation assays in mouse ES cells, replicated by two labs\",\n      \"pmids\": [\"19703396\", \"19713958\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve the fate of uridylated pre-let-7 (decay enzyme unknown at this stage)\", \"Did not define domain requirements for Lin28 interaction\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Extended TUT4 activity to mature miRNAs, showing uridylation of miR-26a as a mechanism to control cytokine output.\",\n      \"evidence\": \"Knockdown, small RNA sequencing, and in vitro nucleotidyltransferase assay with IL-6 readout\",\n      \"pmids\": [\"19701194\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define the sequence determinants distinguishing uridylated mature miRNAs\", \"Mechanism by which uridylation alters silencing not resolved\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Identified histone mRNAs as a non-miRNA substrate class, showing uridylation couples to mRNA decay after DNA replication.\",\n      \"evidence\": \"siRNA knockdown with direct detection of uridylated histone transcripts and degradation assays\",\n      \"pmids\": [\"21051505\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream decay machinery for uridylated histone mRNAs not identified\", \"Trigger linking replication status to uridylation not defined\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Revealed a catalysis-independent function: an N-terminal region of TUT4 promotes G1/S progression independent of uridyltransferase activity.\",\n      \"evidence\": \"Knockdown, overexpression, catalytic point and truncation mutants, cell cycle analysis\",\n      \"pmids\": [\"22006926\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct molecular partners of the N-terminal region in cell cycle control not identified\", \"Single-lab finding without orthogonal mechanistic validation\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Mapped the Lin28 interaction to a single C2H2 zinc finger and showed TUT7 acts redundantly, clarifying the determinants of let-7 control.\",\n      \"evidence\": \"Domain truncation, reconstitution assays, and ES cell knockdown\",\n      \"pmids\": [\"22898984\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not provide atomic structure of the zinc finger-Lin28 interface\", \"Relative contributions of TUT4 vs TUT7 in other tissues unresolved\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Demonstrated in vivo physiological relevance: mature-miRNA uridylation relieves silencing of IGF-1 to support postnatal growth.\",\n      \"evidence\": \"Zcchc11-knockout mice with deep small RNA sequencing, reporter assays, and IGF-1 measurements\",\n      \"pmids\": [\"23209448\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism by which uridylation reduces silencing capacity not fully resolved\", \"Full set of physiologically relevant miRNA targets undefined\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Defined substrate specificity for mature-miRNA uridylation through a bipartite RNA motif and identified TRIM25 as an RNA-specific cofactor enhancing pre-let-7 uridylation.\",\n      \"evidence\": \"In vitro uridylation with motif mapping, zebrafish developmental readout; RNA pulldown/MS and co-IP for TRIM25\",\n      \"pmids\": [\"25223788\", \"25457611\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of TRIM25 activation of TUT4 not resolved\", \"Generality of TRIM25 cofactor role across substrates unknown\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Provided the structural and mechanistic basis for the mono-U to oligo-U switch, defining the catalytic and Lin28-interacting modules.\",\n      \"evidence\": \"Crystal structure of TUT7 catalytic module in monoU state, domain mutants, and in vitro reconstitution\",\n      \"pmids\": [\"28671666\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full ternary complex during processive elongation not captured at this stage\", \"Conformational dynamics of the switch inferred rather than directly observed\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Established TUT4 as a host restriction factor for LINE-1 retrotransposition, with divergent cytoplasmic roles for TUT4 vs TUT7 and cooperation with MOV10.\",\n      \"evidence\": \"Knockdown, retrotransposition reporter assays, subcellular localization, and co-IP with MOV10 in human cells and mouse testes\",\n      \"pmids\": [\"30122351\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Precise determinants directing TUT4 to LINE-1 mRNA not defined\", \"Mechanistic interplay between uridylation and MOV10 RNPase activity incomplete\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Refined the enzymatic and selectivity logic: kinetic ordered mechanism and zinc-finger surfaces underlying substrate diversity, plus establishment of TUT4 as the dominant bulk-miRNA uridylase.\",\n      \"evidence\": \"In vitro kinetics and nucleotide specificity assays; NMR of ZnF2 RNA-binding surfaces; CRISPR knockouts of TENT2/TUT4/TUT7 with deep sequencing\",\n      \"pmids\": [\"35797480\", \"34719327\", \"36071058\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How distinct ZnF2 surfaces are deployed on specific targets in cells not directly observed\", \"Cellular consequences of let-7a/AKT axis modulation only partially characterized\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Extended TUT4 antiviral surveillance to coronavirus subgenomic RNAs with short poly(A) tails, marking them for decay.\",\n      \"evidence\": \"Splint-ligation poly(A) length assay, siRNA knockdown, and viral replication measurement for MHV\",\n      \"pmids\": [\"37085578\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single virus model; generality across coronaviruses untested\", \"Decay enzyme acting on uridylated viral RNA not directly identified in this study\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Distinguished TUT4 from TUT7 in a synthetic-lethal cancer context, establishing TUT4/7 uridylation as a pharmacologically targetable RNA salvage pathway.\",\n      \"evidence\": \"CRISPR knockout, FOCAD re-expression rescue, and selective TUT4/7 inhibitors in vitro and in vivo\",\n      \"pmids\": [\"39235218\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Why TUT7 but not TUT4 is required in FOCAD-deleted cells mechanistically unclear\", \"Single-lab pathway placement partially inferred\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Captured the elongation-stage ternary complex, resolving how Lin28 anchoring and CM-LIM cooperation enable processive oligo-uridylation of pre-let-7.\",\n      \"evidence\": \"Cryo-EM of human TUT4-Lin28A-pre-let-7 with biochemical validation\",\n      \"pmids\": [\"41521656\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis for substrate selection beyond pre-let-7 not addressed\", \"Dynamics of repeated UTP incorporation cycles inferred from static states\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How TUT4's catalysis-independent N-terminal functions (cell cycle, NF-\\u03baB regulation) integrate mechanistically with its RNA uridylation activity remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structural or interaction map linking the N-terminal zinc-finger region to cell cycle effectors\", \"Whether enzymatic and non-enzymatic activities operate in the same cellular contexts is unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140098\", \"supporting_discovery_ids\": [0, 1, 2, 3, 14]},\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 1, 2, 14]},\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [7, 13, 14]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [3, 12]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [10]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [0, 2, 3, 7, 15]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [4]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [2, 10, 12, 16]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"LIN28A\", \"TUT7\", \"TRIM25\", \"TIFA\", \"MOV10\", \"DIS3L2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}