{"gene":"UBTF","run_date":"2026-06-10T10:51:56","timeline":{"discoveries":[{"year":1988,"finding":"UBF1 (purified to homogeneity) binds both the UCE and core elements of the human rDNA promoter and activates RNA pol I transcription through direct protein-protein interactions with SL1; cooperative UBF1-SL1 interaction forms a new protein-DNA complex at the promoter that is required for transcriptional activation.","method":"In vitro transcription reconstitution, DNase I footprinting, protein purification","journal":"Science","confidence":"High","confidence_rationale":"Tier 1 / Strong — purified factor, reconstituted in vitro transcription, DNase I footprinting, widely replicated","pmids":["3413483"],"is_preprint":false},{"year":1991,"finding":"Two forms of UBF (UBF1 and UBF2) exist, arising from alternative splicing that deletes 37 amino acids from HMG box 2 of UBF2; both forms are expressed in vertebrate cells.","method":"cDNA cloning, polymerase chain reaction, probe protection assay, SDS-PAGE","journal":"PNAS","confidence":"High","confidence_rationale":"Tier 1 / Strong — molecular cloning with direct sequencing, confirmed by multiple methods across labs","pmids":["2014238"],"is_preprint":false},{"year":1991,"finding":"Human NOR-90 autoantigen is identical to hUBF; anti-NOR-90 antibodies immunoprecipitate both forms of hUBF, and UBF remains bound to NOR during mitosis even when rRNA synthesis is minimal.","method":"cDNA cloning/immunoprecipitation, immunofluorescence","journal":"Journal of Experimental Medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — cDNA identity established by cloning and immunoprecipitation, replicated across multiple studies","pmids":["1940801"],"is_preprint":false},{"year":1992,"finding":"UBF stimulates rDNA transcription by relieving inhibition from a negative-acting factor in the polymerase fraction that competes for TIF-IB binding; UBF also counteracts histone H1-mediated repression of pol I transcription, acting as an antirepressor.","method":"Reconstituted in vitro transcription with partially purified factors, template commitment experiments","journal":"PNAS","confidence":"High","confidence_rationale":"Tier 1 / Strong — reconstituted transcription system with defined purified components","pmids":["1502143"],"is_preprint":false},{"year":1992,"finding":"UBF1 and UBF2 are phosphorylated on serine residues in vivo; serum deprivation reduces UBF phosphorylation ~80% without changing UBF protein levels; dephosphorylated UBF has reduced ability to rescue Pol I transcription in vitro; serum deprivation causes redistribution of UBF from nucleolus.","method":"In vivo 32P labeling, phosphoamino acid analysis, Western blotting, in vitro transcription, immunofluorescence","journal":"Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — multiple orthogonal methods, functional consequence demonstrated in vitro, replicated across labs","pmids":["1730600"],"is_preprint":false},{"year":1992,"finding":"UBF1 and UBF2 form homodimers and heterodimers; the N-terminal 102 amino acids are important for both DNA binding and dimerization; the HMG box 2 region (present in UBF1 but partially deleted in UBF2) contributes to dimerization and DNA binding differences between isoforms.","method":"Glutaraldehyde cross-linking, overlay assays, Southwestern blotting with recombinant forms","journal":"Nucleic Acids Research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple biochemical methods in single lab","pmids":["1561086"],"is_preprint":false},{"year":1993,"finding":"UBF relieves repression of rDNA transcription by the Ku antigen (a 75/90 kDa heterodimer); anti-Ku antibodies precipitate the repressor activity; Ku binds the rDNA promoter specifically as shown by EMSA and DNase footprinting.","method":"Protein purification, UV-crosslinking, EMSA, DNase footprinting, antibody precipitation of repressor activity","journal":"Nucleic Acids Research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional repressor purified and identified, multiple biochemical approaches in single lab","pmids":["8502546"],"is_preprint":false},{"year":1993,"finding":"UBF is associated with both transcriptionally active and inactive rRNA genes throughout the cell cycle; in interphase it localizes exclusively to the nucleolus in necklace-like structures; it remains at chromosomal NOR during mitosis.","method":"Immunofluorescence, electron microscopy, actinomycin D treatment, nutritional starvation experiments","journal":"Chromosoma","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization by EM and immunofluorescence under multiple conditions","pmids":["8306821"],"is_preprint":false},{"year":1994,"finding":"UBF HMG boxes interact with the minor groove of DNA; UBF is sequence-tolerant (no consensus binding sequence required); UBF can bind RNA (tRNA) as well as DNA; UBF binds synthetic cruciform DNA.","method":"Methylation interference assays, selection for optimal binding sequences, minor-groove drug competition, cruciform DNA binding assays","journal":"Nucleic Acids Research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple binding assays in single lab","pmids":["8041627"],"is_preprint":false},{"year":1994,"finding":"UBF physically associates with RNA Pol I through its HMG boxes; UBF interacts specifically with a single Pol I-specific subunit (62 kDa in mouse); this interaction is conserved with yeast Pol I (binding the 34.5 kDa subunit).","method":"Immunoprecipitation, glycerol gradient sedimentation, affinity chromatography, protein blotting, mutational analysis","journal":"EMBO Journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal biochemical methods, conserved interaction validated across species","pmids":["8306961"],"is_preprint":false},{"year":1994,"finding":"UBF1 and UBF2 differ functionally: UBF1 is a potent transcriptional activator and antirepressor, while UBF2's activity is at least 10-fold lower; the intact HMG box 2 (present only in UBF1) determines sequence-specific binding to rDNA control elements and is responsible for the functional difference; both isoforms bind four-way junction DNA.","method":"In vitro transcription, four-way junction DNA binding, deletion/mutagenesis analysis, in vivo transcription assays","journal":"EMBO Journal","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with mutagenesis, in vivo validation, replicated","pmids":["8313887"],"is_preprint":false},{"year":1995,"finding":"Rb protein directly inhibits UBF activity in vitro; Rb interacts with UBF as shown by affinity chromatography and immunoprecipitation; Rb accumulates in nucleoli of differentiated cells concomitant with rDNA transcription inhibition; Rb repression requires a functional Rb pocket domain.","method":"In vitro transcription, affinity chromatography, immunoprecipitation, in vivo Rb localization studies","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — in vitro transcription assay plus direct protein interaction assays, published in Nature, later replicated","pmids":["7877691"],"is_preprint":false},{"year":1995,"finding":"UBF must be phosphorylated at multiple sites (including casein kinase II sites in the C-terminal domain) to stimulate transcription; unphosphorylated recombinant UBF is transcriptionally inactive; CKII-mediated phosphorylation contributes to but is not sufficient for activation; additional growth-dependent kinases phosphorylate UBF at distinct sites.","method":"In vitro transcription with recombinant E. coli-expressed UBF, site-directed mutagenesis, tryptic phosphopeptide mapping","journal":"Nucleic Acids Research","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with mutagenesis in single lab","pmids":["7651819"],"is_preprint":false},{"year":1995,"finding":"HMG box 4 of UBF is the principal determinant of species specificity in Pol I transcription; adding human HMG box 4 to Xenopus UBF converts it to function in human Pol I transcription, and deleting HMG box 4 from hUBF converts it to function in Xenopus transcription.","method":"Hybrid UBF molecules, in vitro transcription, deletion/addition mutagenesis","journal":"Nucleic Acids Research","confidence":"High","confidence_rationale":"Tier 1 / Moderate — structure-function reconstitution with reciprocal gain- and loss-of-function mutants","pmids":["8524646"],"is_preprint":false},{"year":1996,"finding":"PAF53 (RNA pol I-associated factor) interacts with UBF in vitro as shown by Far-Western blotting and GST pulldown; PAF53 is required for accurate initiation from the rRNA promoter; PAF53 is proposed to mediate interaction between Pol I and UBF in initiation complex formation.","method":"Far-Western blotting, GST pulldown, anti-PAF53 antibody transcription inhibition assay","journal":"EMBO Journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — two orthogonal binding assays plus functional transcription inhibition, single lab","pmids":["8641287"],"is_preprint":false},{"year":1996,"finding":"Overexpression of UBF1 alone is sufficient to increase rDNA transcription 3-5 fold in neonatal cardiomyocytes, establishing UBF as a rate-limiting activator of Pol I transcription in cardiac cells.","method":"Cotransfection of UBF1 expression vector with rDNA reporter construct, Western blot confirmation of expression","journal":"PNAS","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — gain-of-function with reporter assay plus Western blot in primary cells","pmids":["8710943"],"is_preprint":false},{"year":1999,"finding":"UBF is phosphorylated by G1-specific cdk4/cyclin D1 and cdk2/cyclin E complexes at Ser484; mutation of Ser484 impairs rDNA transcription in vivo and in vitro; UBF activity increases during G1 progression concomitant with onset of Pol I transcription.","method":"Tryptic phosphopeptide mapping, site-directed mutagenesis, in vitro kinase assays, in vivo and in vitro transcription","journal":"EMBO Journal","confidence":"High","confidence_rationale":"Tier 1 / Strong — site-directed mutagenesis of phosphorylation site, in vitro kinase assay, both in vivo and in vitro functional validation","pmids":["10202152"],"is_preprint":false},{"year":1999,"finding":"UBF is inactivated during mitosis by phosphorylation and reactivated by dephosphorylation during G1 (with different kinetics from TIF-IB/SL1); repression of Pol I transcription in mitosis and early G1 can be reproduced with M- or G1-phase extracts or with purified TIF-IB and UBF isolated in the presence of phosphatase inhibitors.","method":"Synchronized cell extracts, purified factor transcription assays, phosphatase inhibitor experiments","journal":"PNAS","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional assays with synchronized extracts and purified factors, single lab","pmids":["10339547"],"is_preprint":false},{"year":1999,"finding":"The carboxy-terminal activation domain of UBF directly contacts the TBP-TAFI complex SL1; phosphorylation of UBF is required for this interaction—dephosphorylation abolishes UBF-SL1 interaction and this can be rescued by nuclear extracts from growing cells.","method":"Protein-protein interaction assays with UBF deletion mutants, alkaline phosphatase treatment, DNase I footprinting, in vitro transcription","journal":"Molecular and Cellular Biology","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — deletion mapping, phosphatase experiments, footprinting, in vitro transcription, independently replicated","pmids":["10082553"],"is_preprint":false},{"year":1999,"finding":"SV40 large T antigen-associated kinase phosphorylates the carboxy-terminal activation domain of UBF, promoting formation of a stable UBF-SL1 complex and stimulating Pol I transcription; this rescues the transcriptional defect of dephosphorylated UBF.","method":"Cell labeling, in vitro kinase assay, in vitro transcription reconstitution","journal":"Molecular and Cellular Biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — kinase assay plus reconstituted transcription, single lab","pmids":["10082545"],"is_preprint":false},{"year":2000,"finding":"Rb directly interacts with UBF and blocks UBF-SL1 interaction (using the 48 kDa SL1 subunit as marker), without inhibiting UBF DNA binding; p130 (but not p107) also forms a complex with UBF and represses rDNA transcription.","method":"DNase footprinting, band-shift assays, co-immunoprecipitation, in vitro transcription","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — multiple assays defining mechanism, multiple pocket proteins tested, extends prior Nature paper","pmids":["11042686"],"is_preprint":false},{"year":2000,"finding":"CBP acetyltransferase is recruited to and acetylates UBF both in vitro and in vivo; CBP activates Pol I transcription through its acetyltransferase domain; acetylation of UBF facilitates transcription derepression; Rb-HDAC and CBP competitively recruit to UBF, creating an acetylation-deacetylation switch that regulates Pol I transcription.","method":"In vitro acetylation assay, in vivo co-immunoprecipitation, in vitro transcription with acetylated/deacetylated UBF, in vivo transcription assays","journal":"Molecular Cell","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — in vitro and in vivo acetylation, functional rescue, mechanistic switch established with multiple methods","pmids":["11106745"],"is_preprint":false},{"year":2001,"finding":"UBF two monomers induce hemi-enhancesomes bending DNA ~175°; a UBF dimer creates a full enhancesome with two precisely phased hemi-enhancesomes; HMG boxes 1 and 2 of UBF lie head-to-head along the DNA; insertion/deletion mutations in the linker between the dimerization domain and HMG box 1 prevent DNA looping.","method":"Insertion/deletion mutagenesis, electron microscopy, DNA bending analysis","journal":"Nucleic Acids Research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — structural and mutational analysis, single lab","pmids":["11470882"],"is_preprint":false},{"year":2001,"finding":"ERK1/2 phosphorylates UBF at amino acids 117 and 201 within HMG boxes 1 and 2, preventing their interaction with DNA; this phosphorylation is required for EGF-induced activation of ribosomal transcription; mutation of ERK sites inhibits transcription activation and abolishes the transcriptional response to ERK.","method":"In vitro ERK kinase assay, site-directed mutagenesis, endogenous transcription run-on, ERK1/2 inhibition/activation experiments","journal":"Molecular Cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct phosphorylation site identified, mutagenesis abolishes response, functional consequence in endogenous transcription","pmids":["11741541"],"is_preprint":false},{"year":2001,"finding":"Phosphorylation of UBF at Ser388 by cdk2/cyclin E and cdk2/cyclin A is required for interaction between UBF and RNA polymerase I; conversion of Ser388 to glycine abolishes UBF activity; substitution with aspartate (phospho-mimic) enhances transactivating function.","method":"Site-directed mutagenesis, protein-protein interaction assays, in vivo and in vitro transcription","journal":"PNAS","confidence":"High","confidence_rationale":"Tier 1 / Moderate — phosphosite mutagenesis with gain- and loss-of-function, functional assays, extends prior EMBO paper","pmids":["11698641"],"is_preprint":false},{"year":2002,"finding":"UBF binding in vivo extends across the entire intergenic spacer and transcribed region of rDNA repeats (not restricted to regulatory sequences), consistent with a structural role at active NORs; this was demonstrated in Xenopus, human, and mouse rDNA.","method":"Chromatin immunoprecipitation (ChIP) from nucleolar chromatin fraction","journal":"Molecular and Cellular Biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct ChIP from enriched nucleolar chromatin, multiple species validated","pmids":["11756560"],"is_preprint":false},{"year":2002,"finding":"TAF1 binds UBF directly (confirmed by co-immunoprecipitation and protein-protein interaction assays); TAF1 colocalizes with UBF in the nucleolus; TAF1 stimulates Pol I transcription in a dosage-dependent manner.","method":"Yeast two-hybrid, co-immunoprecipitation, confocal microscopy, cell fractionation, cotransfection, in vitro transcription","journal":"Current Biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple interaction and functional assays, single lab","pmids":["12498690"],"is_preprint":false},{"year":2003,"finding":"mTOR regulates rDNA transcription via S6K1-mediated phosphorylation of the C-terminal activation domain of UBF; rapamycin causes rapid dephosphorylation of UBF and reduces its ability to associate with SL-1; constitutively active, rapamycin-insensitive S6K1 rescues rapamycin repression; purified phosphorylated UBF (but not hypophosphorylated UBF) rescues rapamycin-mediated repression.","method":"Rapamycin treatment, dominant-negative/constitutively active S6K1 expression, UBF phosphorylation analysis, SL-1 association assays, in vitro transcription rescue","journal":"Molecular and Cellular Biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple genetic and biochemical approaches including direct rescue with purified phosphorylated vs. dephosphorylated UBF","pmids":["14612424"],"is_preprint":false},{"year":2003,"finding":"UBF2 associates with LEF-1 (confirmed by co-immunoprecipitation) and potentiates transcriptional activation by LEF-1/β-catenin from Pol II promoters; both UBF1 and UBF2 can activate RNA pol II-regulated promoters; UBF RNAi reduces β-catenin-LEF/TCF-responsive transcription.","method":"Functional screen, co-immunoprecipitation, co-transfection reporter assays, siRNA knockdown","journal":"Molecular and Cellular Biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP plus reporter assays plus siRNA, single lab","pmids":["12748295"],"is_preprint":false},{"year":2004,"finding":"Large arrays of UBF-binding sequences integrated at ectopic chromosomal sites recruit UBF and form pseudo-NORs that sequester the entire Pol I transcription machinery through protein-protein interactions with UBF, independent of transcription, nucleoli, and underlying DNA sequence.","method":"Chromosomal integration of heterologous UBF-binding arrays, immunofluorescence, ChIP, metaphase chromosome analysis","journal":"Genes & Development","confidence":"High","confidence_rationale":"Tier 2 / Strong — gain-of-function chromosomal insertion experiment with multiple readouts, mechanistically definitive","pmids":["15598984"],"is_preprint":false},{"year":2004,"finding":"c-MYC activates and MAD1 represses rDNA transcription; MAD1 represses rDNA transcription by directly interacting with the UBF promoter; UBF is required for c-MYC-induced rDNA transcription (shown by siRNA).","method":"Nuclear run-on assays, ChIP of MAD1 at UBF promoter, UBF siRNA knockdown, luciferase reporter assays","journal":"EMBO Journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple assays including siRNA epistasis and ChIP, single lab","pmids":["15282543"],"is_preprint":false},{"year":2006,"finding":"ERK phosphorylation of UBF HMG boxes 1 and 2 decreases their affinity for linear rDNA but not for pre-bent DNA; ERK-site mutations prevent DNA looping characteristic of the enhancesome (confirmed by electron spectroscopic imaging); ERK phosphorylation cooperatively unfolds the enhancesome.","method":"Electron spectroscopic imaging, DNA bending/binding assays with ERK site mutants","journal":"Biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — structural imaging plus mutant analysis, single lab","pmids":["16533045"],"is_preprint":false},{"year":2006,"finding":"EGF and serum stimulation of rRNA synthesis does not increase Pol I engagement (initiation), but directly increases transcription elongation rates; ERK phosphorylation of UBF HMG boxes regulates elongation by remodeling ribosomal gene chromatin.","method":"Pol I engagement assay, transcription elongation rate measurement, ERK inhibition, ChIP","journal":"Molecular Cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct measurement of elongation rates and Pol I engagement, ERK phosphorylation mechanistically linked, multiple approaches","pmids":["16507361"],"is_preprint":false},{"year":2006,"finding":"UBF activates Pol I transcription by stimulating promoter escape (the transition between initiation and elongation), not by facilitating recruitment or stabilization of the pre-initiation complex.","method":"Reconstituted in vitro transcription assays with defined components, PIC formation and stabilization assays","journal":"EMBO Journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — reconstituted transcription system, negative result for PIC recruitment model rigorously tested","pmids":["16858408"],"is_preprint":false},{"year":2006,"finding":"CK2 co-immunoprecipitates with the Pol I complex and is associated with the rRNA gene promoter; CK2 phosphorylates specific serines in the C-terminus of UBF, counteracting inhibition by HMG boxes 5 and 6, thereby stabilizing UBF-SL1 interaction and promoting multiple rounds of Pol I transcription re-initiation.","method":"Co-immunoprecipitation, ChIP, in vitro kinase assay, immobilized-template transcription assay","journal":"Nucleic Acids Research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP, co-IP, kinase assay, and functional transcription assay, single lab","pmids":["16971462"],"is_preprint":false},{"year":2006,"finding":"UBF acetylation is cell cycle-dependent (acetylated in S-phase, not in G1); HDAC1 overexpression hypoacetylates UBF and reduces its interaction with PAF53/Pol I; acetylation of UBF augments its interaction with Pol I and is required for Pol I association with rDNA and pre-rRNA synthesis.","method":"Inducible HDAC1 overexpression, co-immunoprecipitation, pulldown assay, ChIP","journal":"Nucleic Acids Research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — cell-cycle synchronization, acetylation-function correlation, multiple assays, single lab","pmids":["16582105"],"is_preprint":false},{"year":2007,"finding":"Pseudo-NORs (artificial UBF-chromatin arrays) sequester t-UTPs and factors linking transcription with pre-rRNA modification (Nopp140 and Treacle) independent of transcription, underlying DNA sequence, and nucleolar location; recruitment is mediated by UBF-based chromatin structure.","method":"Pseudo-NOR cell lines, immunofluorescence, ChIP","journal":"Genes & Development","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ectopic integration experiment with clear functional localization readout, single lab","pmids":["17699751"],"is_preprint":false},{"year":2008,"finding":"UBF levels determine the number of active rRNA gene copies in mammals; UBF depletion causes stable, methylation-independent rDNA silencing by promoting histone H1-induced inactive chromatin assembly; silencing is abrogated by mutation of the ERK site in HMG box 1; remaining active genes increase their transcription rate to compensate; the active rDNA pool decreases during differentiation correlating with reduced UBF expression.","method":"Conditional UBF depletion/overexpression, ChIP for histone H1 and methylation marks, chromatin remodeling assays, site-directed mutagenesis of ERK site","journal":"Journal of Cell Biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional knockdown with multiple chromatin and transcription readouts, mutagenesis, published in JCB","pmids":["19103806"],"is_preprint":false},{"year":2008,"finding":"UBF2, lacking 37 amino acids from HMG box 2, cannot bind bent DNA and hence cannot induce chromatin folding; UBF2 is less effective than UBF1 at arresting RNAPI elongation but more responsive to ERK phosphorylation, suggesting it tunes the growth factor response of ribosomal RNA genes.","method":"DNA bending/binding assays, transcription elongation assays, ERK phosphorylation experiments","journal":"Nucleic Acids Research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional differentiation of splice variants, single lab","pmids":["18676449"],"is_preprint":false},{"year":2009,"finding":"Treacle recruits Pol I to the nucleolus independently of UBF; the treacle C-terminus is involved in UBF recruitment; knockdown of treacle disperses Pol I and UBF from the nucleolus, but treacle-Pol I interaction and treacle-rDNA promoter interaction are not disrupted by UBF depletion.","method":"siRNA knockdown, co-immunoprecipitation, ChIP","journal":"Biochemical and Biophysical Research Communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — epistasis by knockdown with clear functional hierarchy established","pmids":["19527688"],"is_preprint":false},{"year":2010,"finding":"hALP (a histone acetyltransferase t-UTP) binds UBF in vivo (by co-immunoprecipitation) and in vitro (GST pulldown), acetylates UBF in a HAT-dependent manner, and promotes nuclear translocation of PAF53 and association of UBF with PAF53, thereby activating Pol I transcription.","method":"Co-immunoprecipitation, GST pulldown, in vivo acetylation assays, PAF53 localization studies","journal":"Journal of Biological Chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro and in vivo interaction and acetylation demonstrated, functional consequence shown, single lab","pmids":["21177859"],"is_preprint":false},{"year":2010,"finding":"Depletion of UBF decreases chromatin binding affinity of B23/nucleophosmin at rDNA, leading to increased histone density at r-chromatin; UBF and RNA binding activity of B23 jointly mediate site-specific targeting of B23 to rDNA chromatin.","method":"UBF siRNA knockdown, histone density measurement at r-chromatin, B23 chromatin binding assays","journal":"Molecular and Cellular Biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — knockdown with chromatin-level readout, single lab","pmids":["20713446"],"is_preprint":false},{"year":2013,"finding":"ESET (H3K9 methyltransferase) interacts with UBF and trimethylates UBF at Lys232/254; UBF trimethylation causes nucleolar chromatin condensation and decreased rDNA transcription; UBF K232/254A and K232/254R mutations restore rDNA transcription; ESET-ΔSET mutant and ESET knockdown reduce UBF trimethylation and restore transcription.","method":"Co-immunoprecipitation, in vitro methylation assay, ChIP, mutagenesis, atomic force microscopy, shRNA knockdown","journal":"Nucleic Acids Research","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — direct methylation assay, site-directed mutagenesis, knockdown with rescue, structural imaging","pmids":["24234436"],"is_preprint":false},{"year":2013,"finding":"PIP2 (phosphatidylinositol 4,5-bisphosphate) associates with UBF and Pol I subunits in a transcription-independent manner throughout the cell cycle; PIP2-UBF colocalization persists during mitosis and after transcription inhibition, suggesting a structural role as anchor for the Pol I pre-initiation complex.","method":"Immunoprecipitation, immunofluorescence colocalization, transcription inhibition (actinomycin D, DRB), mitotic arrest","journal":"Nucleus","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-IP and co-localization under multiple conditions, single lab","pmids":["24513678"],"is_preprint":false},{"year":2014,"finding":"UBTF1 and UBTF2 bind highly expressed Pol II-transcribed genes genome-wide (in addition to rDNA); UBTF1/2 is required for recruiting Pol II to histone gene clusters and for their optimal expression; UBTF depletion causes increased accessibility of histone promoters to MNase and DNA damage/genomic instability independent of Pol I transcription; UBTF2 (not active in Pol I transcription) is sufficient to regulate histone gene expression.","method":"ChIP-seq, expression array, siRNA depletion, MNase accessibility assay, DNA damage markers","journal":"Genome Research","confidence":"High","confidence_rationale":"Tier 2 / Strong — genome-wide ChIP-seq plus functional siRNA depletion with multiple orthogonal readouts, multiple cell systems","pmids":["25452314"],"is_preprint":false},{"year":2015,"finding":"Cisplatin rapidly displaces UBF from ribosomal RNA genes and strongly inhibits ribosomal RNA synthesis; conditional gene deletion of UBF arrests cell proliferation and induces rapid, fully penetrant apoptosis specifically in oncogenically transformed cells in a p53-independent manner.","method":"Conditional gene deletion (Cre/lox), cisplatin treatment with UBF ChIP, apoptosis assays in multiple transformed cell lines, p53-null cells","journal":"Oncotarget","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional KO with multiple cell lines including p53-null, mechanistically specific phenotype","pmids":["26317157"],"is_preprint":false},{"year":2016,"finding":"Disruption of the UBF gene causes disassembly of somatic nucleoli with rRNA gene transcription factors accumulating in dense NPB-like foci; UBF deletion causes rRNA genes to collapse onto centromere-proximal sites; embryonic NPBs and surrounding heterochromatin are disrupted in UBF-null mouse embryos; UBF-null embryos arrest before completing the fourth cleavage division.","method":"Conditional gene disruption in mice, fluorescence microscopy, FISH, immunofluorescence","journal":"Gene","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with precise cellular phenotypes, multiple readouts in both somatic and embryonic cells","pmids":["27614293"],"is_preprint":false},{"year":2017,"finding":"Conditional inactivation of UBF (UBTF) shows that preinitiation complex formation at rDNA is driven by UBF independently of transcription; RPI termination and release corresponds with the TTF1 binding site; the Enhancer Boundary Complex (CTCF and Cohesin) flanks each functional rRNA gene and is maintained even after gene inactivation and re-establishment of repressive chromatin.","method":"Conditional UBF inactivation, conditional Rrn3 inactivation, ChIP-seq","journal":"PLoS Genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional inactivation of two key factors with high-resolution ChIP-seq, multiple mechanistic conclusions","pmids":["28715449"],"is_preprint":false},{"year":2017,"finding":"A heterozygous de novo gain-of-function variant p.Glu210Lys in UBF causes markedly increased UBF binding to the rDNA promoter and 5'-external transcribed spacer, increased 18S rRNA expression, and enlarged nucleoli reduced in number, leading to childhood-onset neurodegeneration.","method":"Chromatin immunoprecipitation, rRNA expression analysis, immunofluorescence of nucleoli in patient fibroblasts","journal":"American Journal of Human Genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP and rRNA analysis in patient cells, single lab, functional validation in patient-derived cells","pmids":["28777933"],"is_preprint":false},{"year":2018,"finding":"The UBTF p.Glu210Lys mutation results in increased pre-rRNA and 18S rRNA expression, nucleolar abnormalities, markedly increased DNA breaks, and defective cell-cycle progression in patient fibroblasts; expression of mutant UBTF1 in Drosophila neurons is lethal; Ubtf+/- mice show only mild motor and behavioral dysfunction.","method":"Patient fibroblast analysis (RT-PCR, rRNA expression, DNA damage markers), Drosophila transgenic expression, mouse heterozygous KO","journal":"Human Molecular Genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple model organisms and patient cells, single lab","pmids":["29300972"],"is_preprint":false},{"year":2019,"finding":"The intracellular domain (ICD) of β-dystroglycan localizes to the nucleolus where it interacts with UBF and B23; overexpression of β-DG ICD mislocalizes UBF, decreases UBF levels, and suppresses rRNA expression; ICD cleavage is induced by nucleolar stressors.","method":"Co-immunoprecipitation, immunofluorescence, rDNA promoter ChIP, rRNA expression analysis, siRNA knockdown","journal":"Cell Death & Disease","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-IP and functional expression/depletion experiments, single lab","pmids":["30814495"],"is_preprint":false},{"year":2020,"finding":"PKCι directly phosphorylates UBF1 at Ser-412, generating a phosphopeptide-binding epitope that recruits the BRCT domain of ECT2; this UBF1-ECT2 interaction on rDNA promoters is required for elevated rRNA synthesis and transformed growth of NSCLC cells.","method":"ECT2 mutagenesis, in vitro kinase assay with MS-based phosphosite identification, lentiviral shRNA knockdown and reconstitution, rRNA synthesis measurement","journal":"Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — direct phosphorylation site identified by MS, mutagenesis of both kinase target and binding domain, knockdown/reconstitution functional validation","pmids":["32350115"],"is_preprint":false},{"year":2022,"finding":"UBTF-TD (exon 13 tandem duplication) maintains genomic occupancy at rDNA loci while also occupying HOXA/HOXB clusters and MEIS1; UBTF-TD co-occupies these loci with KMT2A and menin; UBTF-TD is a gain-of-function alteration causing mislocalization to new genomic targets; stemness, proliferation, and transcriptional signature depend on sustained UBTF-TD chromatin localization.","method":"ChIP-seq of UBTF-TD in cord blood CD34+ cells and patient-derived xenografts, protein degradation system, menin inhibitor treatment","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 / Strong — ChIP-seq plus functional protein degradation experiments plus in vitro and in vivo drug response, multiple models","pmids":["37890156"],"is_preprint":false},{"year":2022,"finding":"Cooperation between SL1 (specifically its TAF1B subunit) and UBTF1 splice variant (not UBTF2) generates the specificity required for rDNA promoter recognition; conditional TAF1B deletion causes striking depletion of UBF at rDNA promoters but not elsewhere; only UBTF1 (not UBTF2) is present with SL1 at promoters.","method":"Conditional TAF1B deletion, ChIP-seq of UBTF1 and SL1, UBTF-E210K knock-in cells","journal":"PLoS Genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional knockout plus genome-wide ChIP-seq, clear epistasis between TAF1B and UBTF1 at promoters","pmids":["35139074"],"is_preprint":false}],"current_model":"UBTF (UBF) is an architectural HMG-box transcription factor that forms homodimers/heterodimers, binds extensively across the entire rDNA repeat to create a nucleosome-free enhancesome structure, and activates RNA Pol I transcription primarily at the promoter escape step and by regulating elongation through ERK-dependent chromatin remodeling; its activity is tightly controlled by phosphorylation (by CK2, CDK4/cyclin D1, CDK2/cyclin E/A, ERK, S6K1, and PKCι at distinct sites) and acetylation (by CBP, opposed by HDAC1/Rb), with UBF1 splice variant acting cooperatively with SL1/TAF1B for promoter recognition, while UBF also functions at highly expressed Pol II genes (via UBTF2) to maintain genome stability, and gain-of-function mutations (E210K) or tandem duplications in leukemia cause aberrant chromatin occupancy and disease."},"narrative":{"mechanistic_narrative":"UBTF (UBF) is an architectural HMG-box DNA-binding protein that activates RNA Polymerase I transcription of ribosomal RNA genes and organizes the chromatin of nucleolar organizer regions [PMID:3413483, PMID:11756560]. Purified UBF binds both the UCE and core elements of the rDNA promoter and cooperatively recruits the SL1/TBP-TAFI complex through its C-terminal activation domain, forming a protein-DNA complex required for transcriptional activation [PMID:3413483, PMID:10082553]. Rather than facilitating pre-initiation complex recruitment, UBF stimulates the transition from initiation to elongation at the promoter-escape step [PMID:16858408] and relieves repression by negative-acting factors including histone H1 and Ku [PMID:1502143, PMID:8502546]. Its HMG boxes contact the DNA minor groove with little sequence specificity [PMID:8041627], allowing UBF dimers to bend DNA ~175° and assemble phased hemi-enhancesome loops into a higher-order enhancesome structure [PMID:11470882]. UBF binding extends across the entire rDNA repeat, and UBF levels set the number of transcriptionally active rRNA gene copies by antagonizing H1-mediated silent chromatin assembly [PMID:11756560, PMID:19103806]. UBF also physically associates with Pol I and its accessory factor PAF53 to integrate the polymerase into the transcription apparatus [PMID:8306961, PMID:8641287]. UBF activity is governed by extensive post-translational control: stimulatory phosphorylation by CK2, CDK4/cyclin D1 and CDK2/cyclin E/A (Ser484, Ser388), S6K1 downstream of mTOR, and PKCι (Ser412), versus ERK phosphorylation within HMG boxes 1 and 2 that unfolds the enhancesome to regulate elongation [PMID:10202152, PMID:11698641, PMID:14612424, PMID:32350115, PMID:11741541, PMID:16507361]; and by an acetylation–deacetylation switch in which CBP and HDAC1/Rb compete, alongside repressive ESET-mediated trimethylation and Rb/p130 binding that blocks UBF-SL1 contact [PMID:11106745, PMID:24234436, PMID:11042686]. Two splice isoforms, UBF1 and UBF2, differ in HMG box 2: UBF1 is the potent Pol I activator that, with the SL1 TAF1B subunit, confers rDNA promoter specificity, while UBF2 cannot bend DNA but binds and regulates highly expressed Pol II genes such as histone clusters to maintain genome stability [PMID:8313887, PMID:35139074, PMID:25452314, PMID:18676449]. UBF deletion disassembles nucleoli and arrests early embryogenesis, and its loss triggers p53-independent apoptosis selectively in transformed cells [PMID:27614293, PMID:26317157]. Gain-of-function alterations—the de novo p.Glu210Lys variant causing childhood-onset neurodegeneration and exon-13 tandem duplications in leukemia—produce aberrant chromatin occupancy and disease [PMID:28777933, PMID:37890156].","teleology":[{"year":1988,"claim":"Established UBF as a sequence-specific activator of Pol I transcription that works through cooperative recruitment of the SL1 promoter-selectivity factor, defining the founding model of rDNA activation.","evidence":"In vitro transcription reconstitution and DNase I footprinting with purified UBF1","pmids":["3413483"],"confidence":"High","gaps":["Did not resolve which step of the transcription cycle UBF stimulates","Mechanism of cooperative complex formation with SL1 not defined structurally"]},{"year":1991,"claim":"Resolved that UBF exists as two alternatively spliced isoforms differing in HMG box 2, raising the question of whether the isoforms are functionally distinct.","evidence":"cDNA cloning, PCR, and probe protection in vertebrate cells","pmids":["2014238"],"confidence":"High","gaps":["Functional difference between UBF1 and UBF2 not yet tested","Did not address isoform-specific binding or activity"]},{"year":1991,"claim":"Identified UBF as the NOR-90 autoantigen that stays bound to nucleolar organizer regions through mitosis, implying a constitutive structural role beyond active transcription.","evidence":"cDNA cloning, immunoprecipitation, and mitotic immunofluorescence","pmids":["1940801"],"confidence":"High","gaps":["Functional consequence of mitotic NOR retention unclear","Did not distinguish active from inactive gene binding"]},{"year":1992,"claim":"Showed UBF acts as an antirepressor relieving inhibition by histone H1 and competing negative factors, and that its activity depends on serine phosphorylation regulated by growth signals.","evidence":"Reconstituted in vitro transcription, in vivo 32P labeling, and serum-deprivation experiments","pmids":["1502143","1730600"],"confidence":"High","gaps":["Specific kinases and phosphosites not identified","Mechanism of H1 antagonism at chromatin level not defined"]},{"year":1992,"claim":"Defined the structural basis of UBF self-association and DNA binding, localizing dimerization to the N-terminus and isoform differences to HMG box 2.","evidence":"Glutaraldehyde cross-linking, overlay, and Southwestern assays with recombinant proteins","pmids":["1561086"],"confidence":"Medium","gaps":["Single-lab biochemistry without structural confirmation","Functional consequence of heterodimerization not established"]},{"year":1994,"claim":"Characterized UBF DNA-binding mode as minor-groove, sequence-tolerant, and structure-selective (cruciform/bent DNA), and showed UBF1 is a far stronger activator than UBF2 with HMG box 4 dictating species specificity.","evidence":"Methylation interference, four-way junction and cruciform binding, hybrid-UBF in vitro transcription","pmids":["8041627","8313887","8524646"],"confidence":"High","gaps":["How structure-selective binding translates to in vivo enhancesome geometry unresolved","Basis of UBF2 functional weakness mechanistically incomplete"]},{"year":1994,"claim":"Demonstrated that UBF physically engages Pol I through its HMG boxes via a conserved polymerase-specific subunit, and that PAF53 bridges this interaction during initiation.","evidence":"Immunoprecipitation, glycerol gradient, affinity chromatography, and Far-Western/GST pulldown","pmids":["8306961","8641287"],"confidence":"High","gaps":["Stoichiometry of the UBF-Pol I-PAF53 assembly not defined","How this contact promotes a specific transcription step not yet addressed"]},{"year":1995,"claim":"Identified Rb as a direct UBF repressor and established that multisite phosphorylation, including CK2 sites, is required to render UBF transcriptionally active, linking growth and tumor-suppressor signaling to rDNA output.","evidence":"In vitro transcription with recombinant UBF, phosphopeptide mapping, Rb affinity chromatography and co-IP","pmids":["7877691","7651819"],"confidence":"High","gaps":["Precise step Rb blocks not yet defined","Individual growth-dependent kinase identities pending"]},{"year":1999,"claim":"Mapped cell-cycle control of UBF to CDK4/cyclin D1 and CDK2/cyclin E phosphorylation of Ser484, and to mitotic inactivation/G1 reactivation, coupling Pol I output to cell-cycle progression.","evidence":"Phosphopeptide mapping, Ser484 mutagenesis, in vitro kinase and synchronized-extract transcription assays","pmids":["10202152","10339547"],"confidence":"High","gaps":["Mitotic kinase responsible not pinpointed","Relationship between Ser484 and the UBF-SL1 contact not yet integrated"]},{"year":1999,"claim":"Showed the UBF C-terminal activation domain directly contacts SL1 in a phosphorylation-dependent manner, providing the molecular basis for how growth signals gate enhancesome-SL1 coupling.","evidence":"Deletion mapping, phosphatase treatment, footprinting, and in vitro transcription including an SV40 large T-associated kinase","pmids":["10082553","10082545"],"confidence":"High","gaps":["Physiological kinase generating this modification not fully resolved","Contact interface on SL1 not structurally defined"]},{"year":2000,"claim":"Defined opposing post-translational switches: Rb/p130 block UBF-SL1 contact without affecting DNA binding, while CBP acetylation derepresses transcription, establishing an acetylation–deacetylation regulatory hub.","evidence":"Co-IP, band-shift, in vitro and in vivo acetylation, and reconstituted transcription","pmids":["11042686","11106745"],"confidence":"High","gaps":["UBF acetylation sites not mapped","How acetylation status feeds into the SL1 contact vs Pol I contact not separated"]},{"year":2001,"claim":"Resolved the enhancesome architecture (paired hemi-enhancesomes bending DNA ~175°) and showed ERK phosphorylation within HMG boxes 1/2 disrupts DNA contact, while CDK2-mediated Ser388 phosphorylation enables UBF-Pol I interaction.","evidence":"Insertion/deletion mutagenesis, electron microscopy, ERK and CDK2 site mutagenesis, transcription run-on","pmids":["11470882","11741541","11698641"],"confidence":"High","gaps":["How antagonistic phosphorylation events are temporally coordinated unclear","ERK-induced unfolding not yet linked to a specific transcription step"]},{"year":2002,"claim":"Demonstrated by ChIP that UBF coats the entire rDNA repeat rather than only regulatory sequences, cementing a structural role at active NORs, and identified TAF1 as a direct UBF partner.","evidence":"ChIP from nucleolar chromatin across species, yeast two-hybrid, co-IP, and in vitro transcription","pmids":["11756560","12498690"],"confidence":"High","gaps":["Functional consequence of genome-wide rDNA coverage not directly tested here","TAF1-UBF interplay with SL1 not integrated"]},{"year":2003,"claim":"Placed UBF downstream of mTOR signaling, showing S6K1 phosphorylates the UBF activation domain to maintain SL1 association, providing the nutrient-sensing link to ribosome biogenesis.","evidence":"Rapamycin treatment, S6K1 mutants, and rescue with purified phosphorylated vs hypophosphorylated UBF","pmids":["14612424"],"confidence":"High","gaps":["Exact S6K1 target residues not pinpointed","Crosstalk with CK2/ERK phosphorylation not resolved"]},{"year":2003,"claim":"Revealed an unexpected Pol II role: UBF2 partners with LEF-1/β-catenin to potentiate Pol II promoter activity, broadening UBF function beyond rDNA.","evidence":"Functional screen, co-IP, reporter assays, and siRNA knockdown","pmids":["12748295"],"confidence":"Medium","gaps":["Genome-wide Pol II targets not yet defined","Mechanism of UBF2 action at Pol II promoters unclear"]},{"year":2004,"claim":"Showed UBF chromatin arrays alone are sufficient to nucleate pseudo-NORs that sequester the entire Pol I machinery independent of transcription, establishing UBF as the primary determinant of NOR identity.","evidence":"Ectopic chromosomal integration of UBF-binding arrays with immunofluorescence and ChIP; also c-MYC/MAD1 epistasis at the UBF gene","pmids":["15598984","15282543"],"confidence":"High","gaps":["Minimal protein interactions needed for sequestration not dissected","Relationship between pseudo-NOR and functional rRNA synthesis not addressed"]},{"year":2006,"claim":"Reframed UBF as an elongation/promoter-escape regulator rather than a PIC-recruitment factor, with ERK phosphorylation remodeling rDNA chromatin to control elongation rate.","evidence":"Reconstituted transcription with PIC stabilization assays, Pol I engagement and elongation-rate measurements, electron spectroscopic imaging of enhancesome unfolding","pmids":["16858408","16507361","16533045","16971462","16582105"],"confidence":"High","gaps":["How promoter-escape stimulation reconciles with genome-wide rDNA coating not fully resolved","Acetylation/CK2 inputs to escape vs reinitiation not separated"]},{"year":2008,"claim":"Established UBF as the dosage-dependent determinant of active rRNA gene copy number, with depletion driving H1-induced, methylation-independent silencing reversible by ERK-site mutation; defined UBF1 vs UBF2 contributions to chromatin folding and ERK responsiveness.","evidence":"Conditional UBF depletion/overexpression with H1 and methylation ChIP, ERK-site mutagenesis, and isoform DNA-bending/elongation assays","pmids":["19103806","18676449"],"confidence":"High","gaps":["How UBF level is read out into a binary active/silent gene state not mechanistically resolved","Compensatory transcription-rate increase mechanism unclear"]},{"year":2010,"claim":"Connected UBF to nucleolar factor recruitment, showing it directs B23/nucleophosmin to rDNA chromatin and is acetylated by the t-UTP hALP to promote PAF53/Pol I association.","evidence":"siRNA knockdown with chromatin readouts, co-IP, GST pulldown, and acetylation assays","pmids":["20713446","21177859"],"confidence":"Medium","gaps":["Single-lab studies without structural detail","Hierarchy of recruitment events not fully ordered"]},{"year":2013,"claim":"Identified repressive UBF modifications, ESET-mediated trimethylation at Lys232/254 condensing nucleolar chromatin, and a transcription-independent PIP2-UBF structural association.","evidence":"In vitro methylation, lysine mutagenesis with rescue, atomic force microscopy, shRNA knockdown, and PIP2 co-IP/colocalization","pmids":["24234436","24513678"],"confidence":"High","gaps":["PIP2-UBF functional role remains correlative","How methylation and acetylation switches are coordinated unclear"]},{"year":2014,"claim":"Demonstrated a genome-stability function: UBTF (especially UBTF2) binds and maintains accessible chromatin at highly expressed Pol II genes such as histone clusters, with depletion causing genomic instability independent of Pol I.","evidence":"ChIP-seq, expression arrays, siRNA depletion, MNase accessibility, and DNA-damage markers","pmids":["25452314"],"confidence":"High","gaps":["How UBTF2 selects Pol II target genes not defined","Mechanistic link from chromatin accessibility to genome stability incomplete"]},{"year":2015,"claim":"Showed UBF is essential for proliferation and is a selective vulnerability of transformed cells, where its deletion or cisplatin-induced displacement triggers p53-independent apoptosis.","evidence":"Conditional Cre/lox deletion across transformed cell lines including p53-null, cisplatin treatment with UBF ChIP, and apoptosis assays","pmids":["26317157"],"confidence":"High","gaps":["Apoptotic effector pathway downstream of UBF loss not defined","Basis of transformed-cell selectivity unclear"]},{"year":2016,"claim":"Established UBF as required for nucleolar assembly and early embryogenesis, with its loss disassembling nucleoli, collapsing rRNA genes to centromere-proximal sites, and arresting embryos at the fourth cleavage.","evidence":"Conditional gene disruption in mice with FISH and immunofluorescence","pmids":["27614293"],"confidence":"High","gaps":["Sequence of events from UBF loss to nucleolar disassembly not fully ordered","Whether arrest reflects transcriptional or structural failure not separated"]},{"year":2017,"claim":"Defined the architecture of the functional rRNA gene unit, showing UBF drives PIC formation independently of transcription and that CTCF/cohesin Enhancer Boundary Complexes persist across gene activity states.","evidence":"Conditional UBF and Rrn3 inactivation with high-resolution ChIP-seq","pmids":["28715449"],"confidence":"High","gaps":["Interplay between UBF occupancy and boundary complex maintenance not mechanistically resolved","How transcription-independent PIC formation is regulated unclear"]},{"year":2017,"claim":"Linked UBF directly to human disease, identifying a de novo gain-of-function p.Glu210Lys variant causing increased rDNA occupancy, elevated rRNA, nucleolar changes, and childhood-onset neurodegeneration.","evidence":"ChIP, rRNA expression, and nucleolar immunofluorescence in patient fibroblasts, with cross-organism modeling","pmids":["28777933","29300972"],"confidence":"Medium","gaps":["Mechanism connecting hyperactive UBF to neuronal vulnerability unresolved","Discrepancy between severe Drosophila lethality and mild mouse phenotype unexplained"]},{"year":2019,"claim":"Identified β-dystroglycan ICD as a nucleolar UBF regulator coupling nucleolar stress to UBF mislocalization and suppressed rRNA synthesis.","evidence":"Co-IP, immunofluorescence, rDNA ChIP, and rRNA expression with siRNA knockdown","pmids":["30814495"],"confidence":"Medium","gaps":["Single-lab study; physiological relevance of the interaction untested in vivo","Stress-signaling input to ICD cleavage not fully defined"]},{"year":2020,"claim":"Defined an oncogenic phosphorylation event, PKCι phosphorylation of UBF1 Ser412 that creates a docking site for the ECT2 BRCT domain to drive rRNA synthesis and transformed growth in lung cancer.","evidence":"MS-based phosphosite mapping, ECT2 and kinase mutagenesis, and shRNA knockdown/reconstitution with rRNA measurement","pmids":["32350115"],"confidence":"High","gaps":["How the UBF1-ECT2 complex mechanistically elevates rRNA synthesis not detailed","Generality beyond NSCLC not established"]},{"year":2022,"claim":"Resolved how isoform-SL1 cooperation generates rDNA promoter specificity and how leukemogenic tandem duplications redirect UBTF to ectopic oncogenic loci.","evidence":"Conditional TAF1B deletion with UBTF1/SL1 ChIP-seq, and UBTF-TD ChIP-seq with protein degradation and menin-inhibitor treatment in leukemia models","pmids":["35139074","37890156"],"confidence":"High","gaps":["How TD acquires affinity for HOXA/HOXB/MEIS1 loci not structurally defined","Whether ectopic occupancy reflects altered DNA-binding or partner recruitment unclear"]},{"year":null,"claim":"How the many antagonistic UBF modifications (CK2, CDK, ERK, S6K1, PKCι phosphorylation; CBP acetylation; ESET methylation) are integrated in real time to set enhancesome state, promoter escape, and active gene number remains unresolved, as does the structural basis by which gain-of-function variants reprogram genomic occupancy.","evidence":"","pmids":[],"confidence":"High","gaps":["No integrated model coordinating the multiple PTM switches","No high-resolution structure of the UBF enhancesome on rDNA","Mechanism by which E210K and exon-13 duplication alter target selection unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[0,8,10,22,25]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[0,3,10,33,44]},{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[8]},{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[22,25,29,37]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,9,18]}],"localization":[{"term_id":"GO:0005730","term_label":"nucleolus","supporting_discovery_ids":[2,7,25,46]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[4,28,44]},{"term_id":"GO:0005694","term_label":"chromosome","supporting_discovery_ids":[2,7,29,46]}],"pathway":[{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[0,3,25,33,44]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[16,17,24,35]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[23,27,32,51]},{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[37,42,44]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[48,49,52]},{"term_id":"R-HSA-1852241","term_label":"Organelle biogenesis and maintenance","supporting_discovery_ids":[29,46]}],"complexes":["rDNA enhancesome","nucleolar organizer region (NOR)"],"partners":["SL1/TAF1B","RNA POL I","PAF53","RB1","CBP","ECT2","B23/NPM1","LEF1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P17480","full_name":"Nucleolar transcription factor 1","aliases":["Autoantigen NOR-90","Upstream-binding factor 1","UBF-1"],"length_aa":764,"mass_kda":89.4,"function":"Recognizes the ribosomal RNA gene promoter and activates transcription mediated by RNA polymerase I (Pol I) through cooperative interactions with the transcription factor SL1/TIF-IB complex. It binds specifically to the upstream control element and can activate Pol I promoter escape","subcellular_location":"Nucleus, nucleolus","url":"https://www.uniprot.org/uniprotkb/P17480/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/UBTF","classification":"Common Essential","n_dependent_lines":1206,"n_total_lines":1208,"dependency_fraction":0.9983443708609272},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000108312","cell_line_id":"CID000846","localizations":[{"compartment":"nucleolus_fc_dfc","grade":3},{"compartment":"nucleoplasm","grade":3},{"compartment":"nuclear_punctae","grade":1}],"interactors":[{"gene":"RAC3","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID000846","total_profiled":1310},"omim":[{"mim_id":"619043","title":"INOSITOL-PENTAKISPHOSPHATE 2-KINASE; IPPK","url":"https://www.omim.org/entry/619043"},{"mim_id":"617672","title":"NEURODEGENERATION, CHILDHOOD-ONSET, WITH BRAIN ATROPHY; CONDBA","url":"https://www.omim.org/entry/617672"},{"mim_id":"616936","title":"CHROMODOMAIN HELICASE DNA-BINDING PROTEIN 9; CHD9","url":"https://www.omim.org/entry/616936"},{"mim_id":"616642","title":"CHROMOSOME 6 OPEN READING FRAME 89; C6ORF89","url":"https://www.omim.org/entry/616642"},{"mim_id":"614405","title":"DEAH-BOX HELICASE 33; DHX33","url":"https://www.omim.org/entry/614405"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Enhanced","locations":[{"location":"Nucleoli fibrillar center","reliability":"Enhanced"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/UBTF"},"hgnc":{"alias_symbol":["UBF","NOR-90","UBF1","UBF2"],"prev_symbol":[]},"alphafold":{"accession":"P17480","domains":[{"cath_id":"1.10.30.10","chopping":"117-185","consensus_level":"medium","plddt":89.6261,"start":117,"end":185},{"cath_id":"-","chopping":"201-283","consensus_level":"high","plddt":88.7612,"start":201,"end":283},{"cath_id":"1.10.30.10","chopping":"300-384","consensus_level":"high","plddt":88.5499,"start":300,"end":384},{"cath_id":"1.10.30.10","chopping":"412-468","consensus_level":"high","plddt":87.093,"start":412,"end":468},{"cath_id":"1.10.30.10","chopping":"487-548","consensus_level":"high","plddt":93.1648,"start":487,"end":548},{"cath_id":"1.10.30.10","chopping":"573-653","consensus_level":"high","plddt":90.9784,"start":573,"end":653},{"cath_id":"1.10.225","chopping":"23-97","consensus_level":"medium","plddt":90.4581,"start":23,"end":97}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P17480","model_url":"https://alphafold.ebi.ac.uk/files/AF-P17480-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P17480-F1-predicted_aligned_error_v6.png","plddt_mean":77.25},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=UBTF","jax_strain_url":"https://www.jax.org/strain/search?query=UBTF"},"sequence":{"accession":"P17480","fasta_url":"https://rest.uniprot.org/uniprotkb/P17480.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P17480/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P17480"}},"corpus_meta":[{"pmid":"14612424","id":"PMC_14612424","title":"mTOR-dependent regulation of ribosomal gene transcription requires S6K1 and is mediated by phosphorylation of the carboxy-terminal activation domain of the nucleolar transcription factor UBF.","date":"2003","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/14612424","citation_count":366,"is_preprint":false},{"pmid":"3413483","id":"PMC_3413483","title":"Functional cooperativity between transcription factors UBF1 and SL1 mediates human ribosomal RNA synthesis.","date":"1988","source":"Science (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/3413483","citation_count":324,"is_preprint":false},{"pmid":"7877691","id":"PMC_7877691","title":"Activity of RNA polymerase I transcription factor UBF blocked by Rb gene product.","date":"1995","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/7877691","citation_count":307,"is_preprint":false},{"pmid":"11741541","id":"PMC_11741541","title":"An immediate response of ribosomal transcription to growth factor stimulation in mammals is mediated by ERK phosphorylation of UBF.","date":"2001","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/11741541","citation_count":202,"is_preprint":false},{"pmid":"11756560","id":"PMC_11756560","title":"UBF binding in vivo is not restricted to regulatory sequences within the vertebrate ribosomal DNA repeat.","date":"2002","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/11756560","citation_count":187,"is_preprint":false},{"pmid":"16507361","id":"PMC_16507361","title":"Growth factor signaling regulates elongation of RNA polymerase I transcription in mammals via UBF phosphorylation and r-chromatin remodeling.","date":"2006","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/16507361","citation_count":173,"is_preprint":false},{"pmid":"19103806","id":"PMC_19103806","title":"UBF levels determine the number of active ribosomal RNA genes in mammals.","date":"2008","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/19103806","citation_count":171,"is_preprint":false},{"pmid":"1940801","id":"PMC_1940801","title":"Human autoantibody to RNA polymerase I transcription factor hUBF. Molecular identity of nucleolus organizer region autoantigen NOR-90 and ribosomal RNA transcription upstream binding factor.","date":"1991","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/1940801","citation_count":153,"is_preprint":false},{"pmid":"15282543","id":"PMC_15282543","title":"MAD1 and c-MYC regulate UBF and rDNA transcription during granulocyte differentiation.","date":"2004","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/15282543","citation_count":152,"is_preprint":false},{"pmid":"10202152","id":"PMC_10202152","title":"Phosphorylation by G1-specific cdk-cyclin complexes activates the nucleolar transcription factor UBF.","date":"1999","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/10202152","citation_count":152,"is_preprint":false},{"pmid":"15598984","id":"PMC_15598984","title":"UBF-binding site arrays form pseudo-NORs and sequester the RNA polymerase I transcription machinery.","date":"2004","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/15598984","citation_count":145,"is_preprint":false},{"pmid":"10339547","id":"PMC_10339547","title":"Cell cycle-dependent regulation of RNA polymerase I transcription: the nucleolar transcription factor UBF is inactive in mitosis and early G1.","date":"1999","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/10339547","citation_count":143,"is_preprint":false},{"pmid":"17699751","id":"PMC_17699751","title":"Recruitment of factors linking transcription and processing of pre-rRNA to NOR chromatin is UBF-dependent and occurs independent of transcription in human cells.","date":"2007","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/17699751","citation_count":130,"is_preprint":false},{"pmid":"8609157","id":"PMC_8609157","title":"In vivo evidence that TATA-binding protein/SL1 colocalizes with UBF and RNA polymerase I when rRNA synthesis is either active or inactive.","date":"1996","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/8609157","citation_count":129,"is_preprint":false},{"pmid":"2014238","id":"PMC_2014238","title":"Identification of two forms of the RNA polymerase I transcription factor UBF.","date":"1991","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/2014238","citation_count":121,"is_preprint":false},{"pmid":"11106745","id":"PMC_11106745","title":"Competitive recruitment of CBP and Rb-HDAC regulates UBF acetylation and ribosomal transcription.","date":"2000","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/11106745","citation_count":114,"is_preprint":false},{"pmid":"1730600","id":"PMC_1730600","title":"Differential phosphorylation and localization of the transcription factor UBF in vivo in response to serum deprivation. In vitro dephosphorylation of UBF reduces its transactivation properties.","date":"1992","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/1730600","citation_count":111,"is_preprint":false},{"pmid":"11042686","id":"PMC_11042686","title":"Rb and p130 regulate RNA polymerase I transcription: Rb disrupts the interaction between UBF and SL-1.","date":"2000","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/11042686","citation_count":110,"is_preprint":false},{"pmid":"19717978","id":"PMC_19717978","title":"The role of UBF in regulating the structure and dynamics of transcriptionally active rDNA chromatin.","date":"2009","source":"Epigenetics","url":"https://pubmed.ncbi.nlm.nih.gov/19717978","citation_count":106,"is_preprint":false},{"pmid":"11698641","id":"PMC_11698641","title":"Phosphorylation of UBF at serine 388 is required for interaction with RNA polymerase I and activation of rDNA transcription.","date":"2001","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/11698641","citation_count":106,"is_preprint":false},{"pmid":"8306821","id":"PMC_8306821","title":"The RNA polymerase I-specific transcription initiation factor UBF is associated with transcriptionally active and inactive ribosomal genes.","date":"1993","source":"Chromosoma","url":"https://pubmed.ncbi.nlm.nih.gov/8306821","citation_count":101,"is_preprint":false},{"pmid":"7651819","id":"PMC_7651819","title":"Activation of mammalian ribosomal gene transcription requires phosphorylation of the nucleolar transcription factor UBF.","date":"1995","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/7651819","citation_count":100,"is_preprint":false},{"pmid":"16858408","id":"PMC_16858408","title":"UBF activates RNA polymerase I transcription by stimulating promoter escape.","date":"2006","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/16858408","citation_count":93,"is_preprint":false},{"pmid":"8041627","id":"PMC_8041627","title":"The RNA polymerase I transcription factor UBF is a sequence-tolerant HMG-box protein that can recognize structured nucleic acids.","date":"1994","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/8041627","citation_count":91,"is_preprint":false},{"pmid":"1502143","id":"PMC_1502143","title":"Dual role of the nucleolar transcription factor UBF: trans-activator and antirepressor.","date":"1992","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/1502143","citation_count":91,"is_preprint":false},{"pmid":"35176137","id":"PMC_35176137","title":"Integrated Genomic Analysis Identifies UBTF Tandem Duplications as a Recurrent Lesion in Pediatric Acute Myeloid Leukemia.","date":"2022","source":"Blood cancer discovery","url":"https://pubmed.ncbi.nlm.nih.gov/35176137","citation_count":88,"is_preprint":false},{"pmid":"8641287","id":"PMC_8641287","title":"RNA polymerase I associated factor 53 binds to the nucleolar transcription factor UBF and functions in specific rDNA transcription.","date":"1996","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/8641287","citation_count":87,"is_preprint":false},{"pmid":"8313887","id":"PMC_8313887","title":"Functional differences between the two splice variants of the nucleolar transcription factor UBF: the second HMG box determines specificity of DNA binding and transcriptional activity.","date":"1994","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/8313887","citation_count":85,"is_preprint":false},{"pmid":"3309055","id":"PMC_3309055","title":"Anti-NOR 90. A new autoantibody in scleroderma that recognizes a 90-kDa component of the nucleolus-organizing region of chromatin.","date":"1987","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/3309055","citation_count":85,"is_preprint":false},{"pmid":"10082553","id":"PMC_10082553","title":"Recruitment of TATA-binding protein-TAFI complex SL1 to the human ribosomal DNA promoter is mediated by the carboxy-terminal activation domain of upstream binding factor (UBF) and is regulated by UBF phosphorylation.","date":"1999","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/10082553","citation_count":79,"is_preprint":false},{"pmid":"11470882","id":"PMC_11470882","title":"DNA looping in the RNA polymerase I enhancesome is the result of non-cooperative in-phase bending by two UBF molecules.","date":"2001","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/11470882","citation_count":78,"is_preprint":false},{"pmid":"8502546","id":"PMC_8502546","title":"The nucleolar transcription activator UBF relieves Ku antigen-mediated repression of mouse ribosomal gene transcription.","date":"1993","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/8502546","citation_count":76,"is_preprint":false},{"pmid":"9410881","id":"PMC_9410881","title":"When rDNA transcription is arrested during mitosis, UBF is still associated with non-condensed rDNA.","date":"1997","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/9410881","citation_count":75,"is_preprint":false},{"pmid":"1561086","id":"PMC_1561086","title":"Analysis of the phosphorylation, DNA-binding and dimerization properties of the RNA polymerase I transcription factors UBF1 and UBF2.","date":"1992","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/1561086","citation_count":74,"is_preprint":false},{"pmid":"1891354","id":"PMC_1891354","title":"Cloning and structural analysis of cDNA and the gene for mouse transcription factor UBF.","date":"1991","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/1891354","citation_count":73,"is_preprint":false},{"pmid":"10329630","id":"PMC_10329630","title":"The interferon-inducible nucleolar p204 protein binds the ribosomal RNA-specific UBF1 transcription factor and inhibits ribosomal RNA transcription.","date":"1999","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/10329630","citation_count":69,"is_preprint":false},{"pmid":"16924243","id":"PMC_16924243","title":"Human tumor suppressor p14ARF negatively regulates rRNA transcription and inhibits UBF1 transcription factor phosphorylation.","date":"2006","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/16924243","citation_count":69,"is_preprint":false},{"pmid":"28715449","id":"PMC_28715449","title":"A unique enhancer boundary complex on the mouse ribosomal RNA genes persists after loss of Rrn3 or UBF and the inactivation of RNA polymerase I transcription.","date":"2017","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/28715449","citation_count":65,"is_preprint":false},{"pmid":"8306961","id":"PMC_8306961","title":"The HMG box-containing nucleolar transcription factor UBF interacts with a specific subunit of RNA polymerase I.","date":"1994","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/8306961","citation_count":64,"is_preprint":false},{"pmid":"8710943","id":"PMC_8710943","title":"Overexpression of the transcription factor UBF1 is sufficient to increase ribosomal DNA transcription in neonatal cardiomyocytes: implications for cardiac hypertrophy.","date":"1996","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/8710943","citation_count":63,"is_preprint":false},{"pmid":"21177859","id":"PMC_21177859","title":"hALP, a novel transcriptional U three protein (t-UTP), activates RNA polymerase I transcription by binding and acetylating the upstream binding factor (UBF).","date":"2010","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/21177859","citation_count":57,"is_preprint":false},{"pmid":"11511532","id":"PMC_11511532","title":"Increased expression of UBF is a critical determinant for rRNA synthesis and hypertrophic growth of cardiac myocytes.","date":"2001","source":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/11511532","citation_count":54,"is_preprint":false},{"pmid":"25452314","id":"PMC_25452314","title":"A novel role for the Pol I transcription factor UBTF in maintaining genome stability through the regulation of highly transcribed Pol II genes.","date":"2014","source":"Genome research","url":"https://pubmed.ncbi.nlm.nih.gov/25452314","citation_count":50,"is_preprint":false},{"pmid":"37890156","id":"PMC_37890156","title":"Acute myeloid leukemias with UBTF tandem duplications are sensitive to menin inhibitors.","date":"2024","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/37890156","citation_count":48,"is_preprint":false},{"pmid":"19527688","id":"PMC_19527688","title":"Treacle recruits RNA polymerase I complex to the nucleolus that is independent of UBF.","date":"2009","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/19527688","citation_count":46,"is_preprint":false},{"pmid":"16533045","id":"PMC_16533045","title":"ERK modulates DNA bending and enhancesome structure by phosphorylating HMG1-boxes 1 and 2 of the RNA polymerase I transcription factor UBF.","date":"2006","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16533045","citation_count":45,"is_preprint":false},{"pmid":"24513678","id":"PMC_24513678","title":"UBF complexes with phosphatidylinositol 4,5-bisphosphate in nucleolar organizer regions regardless of ongoing RNA polymerase I activity.","date":"2013","source":"Nucleus (Austin, Tex.)","url":"https://pubmed.ncbi.nlm.nih.gov/24513678","citation_count":44,"is_preprint":false},{"pmid":"35192684","id":"PMC_35192684","title":"Enhancer retargeting of CDX2 and UBTF::ATXN7L3 define a subtype of high-risk B-progenitor acute lymphoblastic leukemia.","date":"2022","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/35192684","citation_count":43,"is_preprint":false},{"pmid":"16971462","id":"PMC_16971462","title":"CK2-mediated stimulation of Pol I transcription by stabilization of UBF-SL1 interaction.","date":"2006","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/16971462","citation_count":43,"is_preprint":false},{"pmid":"18676449","id":"PMC_18676449","title":"The splice variants of UBF differentially regulate RNA polymerase I transcription elongation in response to ERK phosphorylation.","date":"2008","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/18676449","citation_count":42,"is_preprint":false},{"pmid":"28777933","id":"PMC_28777933","title":"Heterozygous De Novo UBTF Gain-of-Function Variant Is Associated with Neurodegeneration in Childhood.","date":"2017","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/28777933","citation_count":42,"is_preprint":false},{"pmid":"8019125","id":"PMC_8019125","title":"Transcription from the rat 45S ribosomal DNA promoter does not require the factor UBF.","date":"1993","source":"Gene expression","url":"https://pubmed.ncbi.nlm.nih.gov/8019125","citation_count":39,"is_preprint":false},{"pmid":"16582105","id":"PMC_16582105","title":"Acetylation of UBF changes during the cell cycle and regulates the interaction of UBF with RNA polymerase I.","date":"2006","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/16582105","citation_count":39,"is_preprint":false},{"pmid":"29300972","id":"PMC_29300972","title":"A recurrent de novo missense mutation in UBTF causes developmental neuroregression.","date":"2018","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/29300972","citation_count":32,"is_preprint":false},{"pmid":"12498690","id":"PMC_12498690","title":"The cell cycle regulatory factor TAF1 stimulates ribosomal DNA transcription by binding to the activator UBF.","date":"2002","source":"Current biology : CB","url":"https://pubmed.ncbi.nlm.nih.gov/12498690","citation_count":32,"is_preprint":false},{"pmid":"8072492","id":"PMC_8072492","title":"Immunocytochemical characterization of human NOR-90 (upstream binding factor) and associated antigens reactive with autoimmune sera. Two MR forms of NOR-90/hUBF autoantigens.","date":"1994","source":"Molecular biology reports","url":"https://pubmed.ncbi.nlm.nih.gov/8072492","citation_count":31,"is_preprint":false},{"pmid":"26317157","id":"PMC_26317157","title":"Depletion of the cisplatin targeted HMGB-box factor UBF selectively induces p53-independent apoptotic death in transformed cells.","date":"2015","source":"Oncotarget","url":"https://pubmed.ncbi.nlm.nih.gov/26317157","citation_count":29,"is_preprint":false},{"pmid":"37085611","id":"PMC_37085611","title":"UBTF tandem duplications define a distinct subtype of adult de novo acute myeloid leukemia.","date":"2023","source":"Leukemia","url":"https://pubmed.ncbi.nlm.nih.gov/37085611","citation_count":28,"is_preprint":false},{"pmid":"9927757","id":"PMC_9927757","title":"Cellular regulation of ribosomal DNA transcription:both rat and Xenopus UBF1 stimulate rDNA transcription in 3T3 fibroblasts.","date":"1999","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/9927757","citation_count":28,"is_preprint":false},{"pmid":"7876178","id":"PMC_7876178","title":"The RNA polymerase I transcription factor UBF is the product of a primary response gene.","date":"1995","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/7876178","citation_count":28,"is_preprint":false},{"pmid":"10082545","id":"PMC_10082545","title":"A kinase activity associated with simian virus 40 large T antigen phosphorylates upstream binding factor (UBF) and promotes formation of a stable initiation complex between UBF and SL1.","date":"1999","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/10082545","citation_count":28,"is_preprint":false},{"pmid":"35316324","id":"PMC_35316324","title":"Concurrent CDX2 cis-deregulation and UBTF::ATXN7L3 fusion define a novel high-risk subtype of B-cell ALL.","date":"2022","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/35316324","citation_count":27,"is_preprint":false},{"pmid":"20713446","id":"PMC_20713446","title":"Regulation of nucleolar chromatin by B23/nucleophosmin jointly depends upon its RNA binding activity and transcription factor UBF.","date":"2010","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/20713446","citation_count":27,"is_preprint":false},{"pmid":"8702439","id":"PMC_8702439","title":"Detection of autoantibodies to nucleolar transcription factor NOR 90/hUBF in sera of patients with rheumatic diseases, by recombinant autoantigen-based assays.","date":"1996","source":"Arthritis and rheumatism","url":"https://pubmed.ncbi.nlm.nih.gov/8702439","citation_count":27,"is_preprint":false},{"pmid":"17587596","id":"PMC_17587596","title":"The giant fibrillar center: a nucleolar structure enriched in upstream binding factor (UBF) that appears in transcriptionally more active sensory ganglia neurons.","date":"2007","source":"Journal of structural biology","url":"https://pubmed.ncbi.nlm.nih.gov/17587596","citation_count":27,"is_preprint":false},{"pmid":"7699685","id":"PMC_7699685","title":"Clinical relevance and HLA association of autoantibodies against the nucleolus organizer region (NOR-90).","date":"1995","source":"The Journal of rheumatology","url":"https://pubmed.ncbi.nlm.nih.gov/7699685","citation_count":26,"is_preprint":false},{"pmid":"12748295","id":"PMC_12748295","title":"A functional screen in human cells identifies UBF2 as an RNA polymerase II transcription factor that enhances the beta-catenin signaling pathway.","date":"2003","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/12748295","citation_count":24,"is_preprint":false},{"pmid":"1487488","id":"PMC_1487488","title":"Characterization and immunolocalization of RNA polymerase I transcription factor UBF with anti-NOR serum in protozoa, higher plant and vertebrate cells.","date":"1992","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/1487488","citation_count":23,"is_preprint":false},{"pmid":"30517966","id":"PMC_30517966","title":"UBTF Mutation Causes Complex Phenotype of Neurodegeneration and Severe Epilepsy in Childhood.","date":"2018","source":"Neuropediatrics","url":"https://pubmed.ncbi.nlm.nih.gov/30517966","citation_count":22,"is_preprint":false},{"pmid":"9029158","id":"PMC_9029158","title":"The Xenopus RNA polymerase I transcription factor, UBF, has a role in transcriptional enhancement distinct from that at the promoter.","date":"1997","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/9029158","citation_count":22,"is_preprint":false},{"pmid":"34663332","id":"PMC_34663332","title":"UBTF facilitates melanoma progression via modulating MEK1/2-ERK1/2 signalling pathways by promoting GIT1 transcription.","date":"2021","source":"Cancer cell international","url":"https://pubmed.ncbi.nlm.nih.gov/34663332","citation_count":20,"is_preprint":false},{"pmid":"9378756","id":"PMC_9378756","title":"Association of the nucleolar transcription factor UBF with the transcriptionally inactive rRNA genes of pronuclei and early Xenopus embryos.","date":"1997","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/9378756","citation_count":20,"is_preprint":false},{"pmid":"8524646","id":"PMC_8524646","title":"HMG box 4 is the principal determinant of species specificity in the RNA polymerase I transcription factor UBF.","date":"1995","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/8524646","citation_count":20,"is_preprint":false},{"pmid":"8679707","id":"PMC_8679707","title":"Intracellular distribution of HMG1, HMG2 and UBF change following treatment with cisplatin.","date":"1996","source":"Biochimica et biophysica acta","url":"https://pubmed.ncbi.nlm.nih.gov/8679707","citation_count":19,"is_preprint":false},{"pmid":"36323371","id":"PMC_36323371","title":"Long-term performance, microbial evolution and spatial microstructural characteristics of anammox granules in an upflow blanket filter (UBF) treating high-strength nitrogen wastewater.","date":"2022","source":"Bioresource technology","url":"https://pubmed.ncbi.nlm.nih.gov/36323371","citation_count":19,"is_preprint":false},{"pmid":"35139074","id":"PMC_35139074","title":"Ribosomal DNA promoter recognition is determined in vivo by cooperation between UBTF1 and SL1 and is compromised in the UBTF-E210K neuroregression syndrome.","date":"2022","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/35139074","citation_count":18,"is_preprint":false},{"pmid":"24234436","id":"PMC_24234436","title":"ESET methylates UBF at K232/254 and regulates nucleolar heterochromatin plasticity and rDNA transcription.","date":"2013","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/24234436","citation_count":18,"is_preprint":false},{"pmid":"27588501","id":"PMC_27588501","title":"MXD1 localizes in the nucleolus, binds UBF and impairs rRNA synthesis.","date":"2016","source":"Oncotarget","url":"https://pubmed.ncbi.nlm.nih.gov/27588501","citation_count":18,"is_preprint":false},{"pmid":"37236968","id":"PMC_37236968","title":"UBTF tandem duplications are rare but recurrent alterations in adult AML and associated with younger age, myelodysplasia, and inferior outcome.","date":"2023","source":"Blood cancer journal","url":"https://pubmed.ncbi.nlm.nih.gov/37236968","citation_count":17,"is_preprint":false},{"pmid":"25587355","id":"PMC_25587355","title":"HP1β-dependent recruitment of UBF1 to irradiated chromatin occurs simultaneously with CPDs.","date":"2014","source":"Epigenetics & chromatin","url":"https://pubmed.ncbi.nlm.nih.gov/25587355","citation_count":17,"is_preprint":false},{"pmid":"8628680","id":"PMC_8628680","title":"Structure of recombinant rat UBF by electron image analysis and homology modelling.","date":"1996","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/8628680","citation_count":17,"is_preprint":false},{"pmid":"7567455","id":"PMC_7567455","title":"A DNA binding factor (UBF) interacts with a positive regulatory element in the promoters of genes expressed during meiosis and vegetative growth in yeast.","date":"1995","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/7567455","citation_count":15,"is_preprint":false},{"pmid":"36106513","id":"PMC_36106513","title":"A novel, likely pathogenic variant in UBTF-related neurodegeneration with brain atrophy is associated with a severe divergent neurodevelopmental phenotype.","date":"2022","source":"Molecular genetics & genomic medicine","url":"https://pubmed.ncbi.nlm.nih.gov/36106513","citation_count":14,"is_preprint":false},{"pmid":"25890091","id":"PMC_25890091","title":"The HBx oncoprotein of hepatitis B virus potentiates cell transformation by inducing c-Myc-dependent expression of the RNA polymerase I transcription factor UBF.","date":"2015","source":"Virology journal","url":"https://pubmed.ncbi.nlm.nih.gov/25890091","citation_count":14,"is_preprint":false},{"pmid":"7783073","id":"PMC_7783073","title":"Autoantibodies to the nucleolar organizer antigen NOR-90 in children with systemic rheumatic diseases.","date":"1995","source":"The Journal of rheumatology","url":"https://pubmed.ncbi.nlm.nih.gov/7783073","citation_count":14,"is_preprint":false},{"pmid":"32350115","id":"PMC_32350115","title":"Protein kinase Cι promotes UBF1-ECT2 binding on ribosomal DNA to drive rRNA synthesis and transformed growth of non-small-cell lung cancer cells.","date":"2020","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/32350115","citation_count":12,"is_preprint":false},{"pmid":"26984997","id":"PMC_26984997","title":"Three-Dimensional Distribution of UBF and Nopp140 in Relationship to Ribosomal DNA Transcription During Mouse Preimplantation Development.","date":"2016","source":"Biology of reproduction","url":"https://pubmed.ncbi.nlm.nih.gov/26984997","citation_count":12,"is_preprint":false},{"pmid":"27614293","id":"PMC_27614293","title":"Disruption of the UBF gene induces aberrant somatic nucleolar bodies and disrupts embryo nucleolar precursor bodies.","date":"2016","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/27614293","citation_count":12,"is_preprint":false},{"pmid":"11036095","id":"PMC_11036095","title":"Immunohistochemical detection of ribosomal transcription factor UBF and AgNOR staining identify apoptotic events in neoplastic cells of Hodgkin's disease and in other lymphoid cells.","date":"2000","source":"The journal of histochemistry and cytochemistry : official journal of the Histochemistry Society","url":"https://pubmed.ncbi.nlm.nih.gov/11036095","citation_count":12,"is_preprint":false},{"pmid":"12885411","id":"PMC_12885411","title":"Cardiac hypertrophy in vivo is associated with increased expression of the ribosomal gene transcription factor UBF.","date":"2003","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/12885411","citation_count":12,"is_preprint":false},{"pmid":"38426285","id":"PMC_38426285","title":"UBTF tandem duplications in pediatric myelodysplastic syndrome and acute myeloid leukemia: implications for clinical screening and diagnosis.","date":"2024","source":"Haematologica","url":"https://pubmed.ncbi.nlm.nih.gov/38426285","citation_count":11,"is_preprint":false},{"pmid":"35973608","id":"PMC_35973608","title":"Behavioral and molecular effects of Ubtf knockout and knockdown in mice.","date":"2022","source":"Brain research","url":"https://pubmed.ncbi.nlm.nih.gov/35973608","citation_count":11,"is_preprint":false},{"pmid":"8751374","id":"PMC_8751374","title":"The RNA polymerase I transcription factor UBF and rDNA are located at the same major sites in both interphase and mitotic pig embryonic kidney (PK) cells.","date":"1996","source":"Cytogenetics and cell genetics","url":"https://pubmed.ncbi.nlm.nih.gov/8751374","citation_count":11,"is_preprint":false},{"pmid":"1579451","id":"PMC_1579451","title":"Analysis of the rat ribosomal DNA promoter: characterization of linker-scanning mutants and of the binding of UBF.","date":"1992","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/1579451","citation_count":10,"is_preprint":false},{"pmid":"9126496","id":"PMC_9126496","title":"Molecular cloning of the RNA polymerase I transcription factor hUBF/NOR-90 (UBTF) gene and localization to 17q21.3 by fluorescence in situ hybridization and radiation hybrid mapping.","date":"1997","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/9126496","citation_count":10,"is_preprint":false},{"pmid":"26484160","id":"PMC_26484160","title":"Genome wide mapping of UBF binding-sites in mouse and human cell lines.","date":"2015","source":"Genomics data","url":"https://pubmed.ncbi.nlm.nih.gov/26484160","citation_count":9,"is_preprint":false},{"pmid":"26208041","id":"PMC_26208041","title":"Localized movement and morphology of UBF1-positive nucleolar regions are changed by γ-irradiation in G2 phase of the cell cycle.","date":"2015","source":"Nucleus (Austin, Tex.)","url":"https://pubmed.ncbi.nlm.nih.gov/26208041","citation_count":9,"is_preprint":false},{"pmid":"30814495","id":"PMC_30814495","title":"The intracellular domain of β-dystroglycan mediates the nucleolar stress response by suppressing UBF transcriptional activity.","date":"2019","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/30814495","citation_count":9,"is_preprint":false},{"pmid":"19738441","id":"PMC_19738441","title":"IRS-2, but not IRS-1, can sustain proliferation and rescue UBF stabilization in InR or InR defective signaling of 32D myeloid cells.","date":"2009","source":"Cell cycle (Georgetown, Tex.)","url":"https://pubmed.ncbi.nlm.nih.gov/19738441","citation_count":9,"is_preprint":false},{"pmid":"8918262","id":"PMC_8918262","title":"Cloning and sequencing of the genes encoding the hamster ribosomal transcription factors UBF1 and UBF2.","date":"1996","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/8918262","citation_count":8,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":46355,"output_tokens":11750,"usd":0.157658,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":22854,"output_tokens":8488,"usd":0.163235,"stage2_stop_reason":"end_turn"},"total_usd":0.320893,"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\": 1988,\n      \"finding\": \"UBF1 (purified to homogeneity) binds both the UCE and core elements of the human rDNA promoter and activates RNA pol I transcription through direct protein-protein interactions with SL1; cooperative UBF1-SL1 interaction forms a new protein-DNA complex at the promoter that is required for transcriptional activation.\",\n      \"method\": \"In vitro transcription reconstitution, DNase I footprinting, protein purification\",\n      \"journal\": \"Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — purified factor, reconstituted in vitro transcription, DNase I footprinting, widely replicated\",\n      \"pmids\": [\"3413483\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1991,\n      \"finding\": \"Two forms of UBF (UBF1 and UBF2) exist, arising from alternative splicing that deletes 37 amino acids from HMG box 2 of UBF2; both forms are expressed in vertebrate cells.\",\n      \"method\": \"cDNA cloning, polymerase chain reaction, probe protection assay, SDS-PAGE\",\n      \"journal\": \"PNAS\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — molecular cloning with direct sequencing, confirmed by multiple methods across labs\",\n      \"pmids\": [\"2014238\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1991,\n      \"finding\": \"Human NOR-90 autoantigen is identical to hUBF; anti-NOR-90 antibodies immunoprecipitate both forms of hUBF, and UBF remains bound to NOR during mitosis even when rRNA synthesis is minimal.\",\n      \"method\": \"cDNA cloning/immunoprecipitation, immunofluorescence\",\n      \"journal\": \"Journal of Experimental Medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — cDNA identity established by cloning and immunoprecipitation, replicated across multiple studies\",\n      \"pmids\": [\"1940801\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1992,\n      \"finding\": \"UBF stimulates rDNA transcription by relieving inhibition from a negative-acting factor in the polymerase fraction that competes for TIF-IB binding; UBF also counteracts histone H1-mediated repression of pol I transcription, acting as an antirepressor.\",\n      \"method\": \"Reconstituted in vitro transcription with partially purified factors, template commitment experiments\",\n      \"journal\": \"PNAS\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — reconstituted transcription system with defined purified components\",\n      \"pmids\": [\"1502143\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1992,\n      \"finding\": \"UBF1 and UBF2 are phosphorylated on serine residues in vivo; serum deprivation reduces UBF phosphorylation ~80% without changing UBF protein levels; dephosphorylated UBF has reduced ability to rescue Pol I transcription in vitro; serum deprivation causes redistribution of UBF from nucleolus.\",\n      \"method\": \"In vivo 32P labeling, phosphoamino acid analysis, Western blotting, in vitro transcription, immunofluorescence\",\n      \"journal\": \"Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — multiple orthogonal methods, functional consequence demonstrated in vitro, replicated across labs\",\n      \"pmids\": [\"1730600\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1992,\n      \"finding\": \"UBF1 and UBF2 form homodimers and heterodimers; the N-terminal 102 amino acids are important for both DNA binding and dimerization; the HMG box 2 region (present in UBF1 but partially deleted in UBF2) contributes to dimerization and DNA binding differences between isoforms.\",\n      \"method\": \"Glutaraldehyde cross-linking, overlay assays, Southwestern blotting with recombinant forms\",\n      \"journal\": \"Nucleic Acids Research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple biochemical methods in single lab\",\n      \"pmids\": [\"1561086\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1993,\n      \"finding\": \"UBF relieves repression of rDNA transcription by the Ku antigen (a 75/90 kDa heterodimer); anti-Ku antibodies precipitate the repressor activity; Ku binds the rDNA promoter specifically as shown by EMSA and DNase footprinting.\",\n      \"method\": \"Protein purification, UV-crosslinking, EMSA, DNase footprinting, antibody precipitation of repressor activity\",\n      \"journal\": \"Nucleic Acids Research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional repressor purified and identified, multiple biochemical approaches in single lab\",\n      \"pmids\": [\"8502546\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1993,\n      \"finding\": \"UBF is associated with both transcriptionally active and inactive rRNA genes throughout the cell cycle; in interphase it localizes exclusively to the nucleolus in necklace-like structures; it remains at chromosomal NOR during mitosis.\",\n      \"method\": \"Immunofluorescence, electron microscopy, actinomycin D treatment, nutritional starvation experiments\",\n      \"journal\": \"Chromosoma\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization by EM and immunofluorescence under multiple conditions\",\n      \"pmids\": [\"8306821\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"UBF HMG boxes interact with the minor groove of DNA; UBF is sequence-tolerant (no consensus binding sequence required); UBF can bind RNA (tRNA) as well as DNA; UBF binds synthetic cruciform DNA.\",\n      \"method\": \"Methylation interference assays, selection for optimal binding sequences, minor-groove drug competition, cruciform DNA binding assays\",\n      \"journal\": \"Nucleic Acids Research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple binding assays in single lab\",\n      \"pmids\": [\"8041627\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"UBF physically associates with RNA Pol I through its HMG boxes; UBF interacts specifically with a single Pol I-specific subunit (62 kDa in mouse); this interaction is conserved with yeast Pol I (binding the 34.5 kDa subunit).\",\n      \"method\": \"Immunoprecipitation, glycerol gradient sedimentation, affinity chromatography, protein blotting, mutational analysis\",\n      \"journal\": \"EMBO Journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal biochemical methods, conserved interaction validated across species\",\n      \"pmids\": [\"8306961\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"UBF1 and UBF2 differ functionally: UBF1 is a potent transcriptional activator and antirepressor, while UBF2's activity is at least 10-fold lower; the intact HMG box 2 (present only in UBF1) determines sequence-specific binding to rDNA control elements and is responsible for the functional difference; both isoforms bind four-way junction DNA.\",\n      \"method\": \"In vitro transcription, four-way junction DNA binding, deletion/mutagenesis analysis, in vivo transcription assays\",\n      \"journal\": \"EMBO Journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with mutagenesis, in vivo validation, replicated\",\n      \"pmids\": [\"8313887\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"Rb protein directly inhibits UBF activity in vitro; Rb interacts with UBF as shown by affinity chromatography and immunoprecipitation; Rb accumulates in nucleoli of differentiated cells concomitant with rDNA transcription inhibition; Rb repression requires a functional Rb pocket domain.\",\n      \"method\": \"In vitro transcription, affinity chromatography, immunoprecipitation, in vivo Rb localization studies\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — in vitro transcription assay plus direct protein interaction assays, published in Nature, later replicated\",\n      \"pmids\": [\"7877691\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"UBF must be phosphorylated at multiple sites (including casein kinase II sites in the C-terminal domain) to stimulate transcription; unphosphorylated recombinant UBF is transcriptionally inactive; CKII-mediated phosphorylation contributes to but is not sufficient for activation; additional growth-dependent kinases phosphorylate UBF at distinct sites.\",\n      \"method\": \"In vitro transcription with recombinant E. coli-expressed UBF, site-directed mutagenesis, tryptic phosphopeptide mapping\",\n      \"journal\": \"Nucleic Acids Research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with mutagenesis in single lab\",\n      \"pmids\": [\"7651819\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"HMG box 4 of UBF is the principal determinant of species specificity in Pol I transcription; adding human HMG box 4 to Xenopus UBF converts it to function in human Pol I transcription, and deleting HMG box 4 from hUBF converts it to function in Xenopus transcription.\",\n      \"method\": \"Hybrid UBF molecules, in vitro transcription, deletion/addition mutagenesis\",\n      \"journal\": \"Nucleic Acids Research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — structure-function reconstitution with reciprocal gain- and loss-of-function mutants\",\n      \"pmids\": [\"8524646\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"PAF53 (RNA pol I-associated factor) interacts with UBF in vitro as shown by Far-Western blotting and GST pulldown; PAF53 is required for accurate initiation from the rRNA promoter; PAF53 is proposed to mediate interaction between Pol I and UBF in initiation complex formation.\",\n      \"method\": \"Far-Western blotting, GST pulldown, anti-PAF53 antibody transcription inhibition assay\",\n      \"journal\": \"EMBO Journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two orthogonal binding assays plus functional transcription inhibition, single lab\",\n      \"pmids\": [\"8641287\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"Overexpression of UBF1 alone is sufficient to increase rDNA transcription 3-5 fold in neonatal cardiomyocytes, establishing UBF as a rate-limiting activator of Pol I transcription in cardiac cells.\",\n      \"method\": \"Cotransfection of UBF1 expression vector with rDNA reporter construct, Western blot confirmation of expression\",\n      \"journal\": \"PNAS\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — gain-of-function with reporter assay plus Western blot in primary cells\",\n      \"pmids\": [\"8710943\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"UBF is phosphorylated by G1-specific cdk4/cyclin D1 and cdk2/cyclin E complexes at Ser484; mutation of Ser484 impairs rDNA transcription in vivo and in vitro; UBF activity increases during G1 progression concomitant with onset of Pol I transcription.\",\n      \"method\": \"Tryptic phosphopeptide mapping, site-directed mutagenesis, in vitro kinase assays, in vivo and in vitro transcription\",\n      \"journal\": \"EMBO Journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — site-directed mutagenesis of phosphorylation site, in vitro kinase assay, both in vivo and in vitro functional validation\",\n      \"pmids\": [\"10202152\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"UBF is inactivated during mitosis by phosphorylation and reactivated by dephosphorylation during G1 (with different kinetics from TIF-IB/SL1); repression of Pol I transcription in mitosis and early G1 can be reproduced with M- or G1-phase extracts or with purified TIF-IB and UBF isolated in the presence of phosphatase inhibitors.\",\n      \"method\": \"Synchronized cell extracts, purified factor transcription assays, phosphatase inhibitor experiments\",\n      \"journal\": \"PNAS\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional assays with synchronized extracts and purified factors, single lab\",\n      \"pmids\": [\"10339547\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"The carboxy-terminal activation domain of UBF directly contacts the TBP-TAFI complex SL1; phosphorylation of UBF is required for this interaction—dephosphorylation abolishes UBF-SL1 interaction and this can be rescued by nuclear extracts from growing cells.\",\n      \"method\": \"Protein-protein interaction assays with UBF deletion mutants, alkaline phosphatase treatment, DNase I footprinting, in vitro transcription\",\n      \"journal\": \"Molecular and Cellular Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — deletion mapping, phosphatase experiments, footprinting, in vitro transcription, independently replicated\",\n      \"pmids\": [\"10082553\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"SV40 large T antigen-associated kinase phosphorylates the carboxy-terminal activation domain of UBF, promoting formation of a stable UBF-SL1 complex and stimulating Pol I transcription; this rescues the transcriptional defect of dephosphorylated UBF.\",\n      \"method\": \"Cell labeling, in vitro kinase assay, in vitro transcription reconstitution\",\n      \"journal\": \"Molecular and Cellular Biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — kinase assay plus reconstituted transcription, single lab\",\n      \"pmids\": [\"10082545\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Rb directly interacts with UBF and blocks UBF-SL1 interaction (using the 48 kDa SL1 subunit as marker), without inhibiting UBF DNA binding; p130 (but not p107) also forms a complex with UBF and represses rDNA transcription.\",\n      \"method\": \"DNase footprinting, band-shift assays, co-immunoprecipitation, in vitro transcription\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — multiple assays defining mechanism, multiple pocket proteins tested, extends prior Nature paper\",\n      \"pmids\": [\"11042686\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"CBP acetyltransferase is recruited to and acetylates UBF both in vitro and in vivo; CBP activates Pol I transcription through its acetyltransferase domain; acetylation of UBF facilitates transcription derepression; Rb-HDAC and CBP competitively recruit to UBF, creating an acetylation-deacetylation switch that regulates Pol I transcription.\",\n      \"method\": \"In vitro acetylation assay, in vivo co-immunoprecipitation, in vitro transcription with acetylated/deacetylated UBF, in vivo transcription assays\",\n      \"journal\": \"Molecular Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — in vitro and in vivo acetylation, functional rescue, mechanistic switch established with multiple methods\",\n      \"pmids\": [\"11106745\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"UBF two monomers induce hemi-enhancesomes bending DNA ~175°; a UBF dimer creates a full enhancesome with two precisely phased hemi-enhancesomes; HMG boxes 1 and 2 of UBF lie head-to-head along the DNA; insertion/deletion mutations in the linker between the dimerization domain and HMG box 1 prevent DNA looping.\",\n      \"method\": \"Insertion/deletion mutagenesis, electron microscopy, DNA bending analysis\",\n      \"journal\": \"Nucleic Acids Research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — structural and mutational analysis, single lab\",\n      \"pmids\": [\"11470882\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"ERK1/2 phosphorylates UBF at amino acids 117 and 201 within HMG boxes 1 and 2, preventing their interaction with DNA; this phosphorylation is required for EGF-induced activation of ribosomal transcription; mutation of ERK sites inhibits transcription activation and abolishes the transcriptional response to ERK.\",\n      \"method\": \"In vitro ERK kinase assay, site-directed mutagenesis, endogenous transcription run-on, ERK1/2 inhibition/activation experiments\",\n      \"journal\": \"Molecular Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct phosphorylation site identified, mutagenesis abolishes response, functional consequence in endogenous transcription\",\n      \"pmids\": [\"11741541\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Phosphorylation of UBF at Ser388 by cdk2/cyclin E and cdk2/cyclin A is required for interaction between UBF and RNA polymerase I; conversion of Ser388 to glycine abolishes UBF activity; substitution with aspartate (phospho-mimic) enhances transactivating function.\",\n      \"method\": \"Site-directed mutagenesis, protein-protein interaction assays, in vivo and in vitro transcription\",\n      \"journal\": \"PNAS\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — phosphosite mutagenesis with gain- and loss-of-function, functional assays, extends prior EMBO paper\",\n      \"pmids\": [\"11698641\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"UBF binding in vivo extends across the entire intergenic spacer and transcribed region of rDNA repeats (not restricted to regulatory sequences), consistent with a structural role at active NORs; this was demonstrated in Xenopus, human, and mouse rDNA.\",\n      \"method\": \"Chromatin immunoprecipitation (ChIP) from nucleolar chromatin fraction\",\n      \"journal\": \"Molecular and Cellular Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct ChIP from enriched nucleolar chromatin, multiple species validated\",\n      \"pmids\": [\"11756560\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"TAF1 binds UBF directly (confirmed by co-immunoprecipitation and protein-protein interaction assays); TAF1 colocalizes with UBF in the nucleolus; TAF1 stimulates Pol I transcription in a dosage-dependent manner.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation, confocal microscopy, cell fractionation, cotransfection, in vitro transcription\",\n      \"journal\": \"Current Biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple interaction and functional assays, single lab\",\n      \"pmids\": [\"12498690\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"mTOR regulates rDNA transcription via S6K1-mediated phosphorylation of the C-terminal activation domain of UBF; rapamycin causes rapid dephosphorylation of UBF and reduces its ability to associate with SL-1; constitutively active, rapamycin-insensitive S6K1 rescues rapamycin repression; purified phosphorylated UBF (but not hypophosphorylated UBF) rescues rapamycin-mediated repression.\",\n      \"method\": \"Rapamycin treatment, dominant-negative/constitutively active S6K1 expression, UBF phosphorylation analysis, SL-1 association assays, in vitro transcription rescue\",\n      \"journal\": \"Molecular and Cellular Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple genetic and biochemical approaches including direct rescue with purified phosphorylated vs. dephosphorylated UBF\",\n      \"pmids\": [\"14612424\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"UBF2 associates with LEF-1 (confirmed by co-immunoprecipitation) and potentiates transcriptional activation by LEF-1/β-catenin from Pol II promoters; both UBF1 and UBF2 can activate RNA pol II-regulated promoters; UBF RNAi reduces β-catenin-LEF/TCF-responsive transcription.\",\n      \"method\": \"Functional screen, co-immunoprecipitation, co-transfection reporter assays, siRNA knockdown\",\n      \"journal\": \"Molecular and Cellular Biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP plus reporter assays plus siRNA, single lab\",\n      \"pmids\": [\"12748295\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Large arrays of UBF-binding sequences integrated at ectopic chromosomal sites recruit UBF and form pseudo-NORs that sequester the entire Pol I transcription machinery through protein-protein interactions with UBF, independent of transcription, nucleoli, and underlying DNA sequence.\",\n      \"method\": \"Chromosomal integration of heterologous UBF-binding arrays, immunofluorescence, ChIP, metaphase chromosome analysis\",\n      \"journal\": \"Genes & Development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — gain-of-function chromosomal insertion experiment with multiple readouts, mechanistically definitive\",\n      \"pmids\": [\"15598984\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"c-MYC activates and MAD1 represses rDNA transcription; MAD1 represses rDNA transcription by directly interacting with the UBF promoter; UBF is required for c-MYC-induced rDNA transcription (shown by siRNA).\",\n      \"method\": \"Nuclear run-on assays, ChIP of MAD1 at UBF promoter, UBF siRNA knockdown, luciferase reporter assays\",\n      \"journal\": \"EMBO Journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple assays including siRNA epistasis and ChIP, single lab\",\n      \"pmids\": [\"15282543\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"ERK phosphorylation of UBF HMG boxes 1 and 2 decreases their affinity for linear rDNA but not for pre-bent DNA; ERK-site mutations prevent DNA looping characteristic of the enhancesome (confirmed by electron spectroscopic imaging); ERK phosphorylation cooperatively unfolds the enhancesome.\",\n      \"method\": \"Electron spectroscopic imaging, DNA bending/binding assays with ERK site mutants\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — structural imaging plus mutant analysis, single lab\",\n      \"pmids\": [\"16533045\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"EGF and serum stimulation of rRNA synthesis does not increase Pol I engagement (initiation), but directly increases transcription elongation rates; ERK phosphorylation of UBF HMG boxes regulates elongation by remodeling ribosomal gene chromatin.\",\n      \"method\": \"Pol I engagement assay, transcription elongation rate measurement, ERK inhibition, ChIP\",\n      \"journal\": \"Molecular Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct measurement of elongation rates and Pol I engagement, ERK phosphorylation mechanistically linked, multiple approaches\",\n      \"pmids\": [\"16507361\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"UBF activates Pol I transcription by stimulating promoter escape (the transition between initiation and elongation), not by facilitating recruitment or stabilization of the pre-initiation complex.\",\n      \"method\": \"Reconstituted in vitro transcription assays with defined components, PIC formation and stabilization assays\",\n      \"journal\": \"EMBO Journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — reconstituted transcription system, negative result for PIC recruitment model rigorously tested\",\n      \"pmids\": [\"16858408\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"CK2 co-immunoprecipitates with the Pol I complex and is associated with the rRNA gene promoter; CK2 phosphorylates specific serines in the C-terminus of UBF, counteracting inhibition by HMG boxes 5 and 6, thereby stabilizing UBF-SL1 interaction and promoting multiple rounds of Pol I transcription re-initiation.\",\n      \"method\": \"Co-immunoprecipitation, ChIP, in vitro kinase assay, immobilized-template transcription assay\",\n      \"journal\": \"Nucleic Acids Research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP, co-IP, kinase assay, and functional transcription assay, single lab\",\n      \"pmids\": [\"16971462\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"UBF acetylation is cell cycle-dependent (acetylated in S-phase, not in G1); HDAC1 overexpression hypoacetylates UBF and reduces its interaction with PAF53/Pol I; acetylation of UBF augments its interaction with Pol I and is required for Pol I association with rDNA and pre-rRNA synthesis.\",\n      \"method\": \"Inducible HDAC1 overexpression, co-immunoprecipitation, pulldown assay, ChIP\",\n      \"journal\": \"Nucleic Acids Research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — cell-cycle synchronization, acetylation-function correlation, multiple assays, single lab\",\n      \"pmids\": [\"16582105\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Pseudo-NORs (artificial UBF-chromatin arrays) sequester t-UTPs and factors linking transcription with pre-rRNA modification (Nopp140 and Treacle) independent of transcription, underlying DNA sequence, and nucleolar location; recruitment is mediated by UBF-based chromatin structure.\",\n      \"method\": \"Pseudo-NOR cell lines, immunofluorescence, ChIP\",\n      \"journal\": \"Genes & Development\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ectopic integration experiment with clear functional localization readout, single lab\",\n      \"pmids\": [\"17699751\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"UBF levels determine the number of active rRNA gene copies in mammals; UBF depletion causes stable, methylation-independent rDNA silencing by promoting histone H1-induced inactive chromatin assembly; silencing is abrogated by mutation of the ERK site in HMG box 1; remaining active genes increase their transcription rate to compensate; the active rDNA pool decreases during differentiation correlating with reduced UBF expression.\",\n      \"method\": \"Conditional UBF depletion/overexpression, ChIP for histone H1 and methylation marks, chromatin remodeling assays, site-directed mutagenesis of ERK site\",\n      \"journal\": \"Journal of Cell Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional knockdown with multiple chromatin and transcription readouts, mutagenesis, published in JCB\",\n      \"pmids\": [\"19103806\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"UBF2, lacking 37 amino acids from HMG box 2, cannot bind bent DNA and hence cannot induce chromatin folding; UBF2 is less effective than UBF1 at arresting RNAPI elongation but more responsive to ERK phosphorylation, suggesting it tunes the growth factor response of ribosomal RNA genes.\",\n      \"method\": \"DNA bending/binding assays, transcription elongation assays, ERK phosphorylation experiments\",\n      \"journal\": \"Nucleic Acids Research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional differentiation of splice variants, single lab\",\n      \"pmids\": [\"18676449\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Treacle recruits Pol I to the nucleolus independently of UBF; the treacle C-terminus is involved in UBF recruitment; knockdown of treacle disperses Pol I and UBF from the nucleolus, but treacle-Pol I interaction and treacle-rDNA promoter interaction are not disrupted by UBF depletion.\",\n      \"method\": \"siRNA knockdown, co-immunoprecipitation, ChIP\",\n      \"journal\": \"Biochemical and Biophysical Research Communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — epistasis by knockdown with clear functional hierarchy established\",\n      \"pmids\": [\"19527688\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"hALP (a histone acetyltransferase t-UTP) binds UBF in vivo (by co-immunoprecipitation) and in vitro (GST pulldown), acetylates UBF in a HAT-dependent manner, and promotes nuclear translocation of PAF53 and association of UBF with PAF53, thereby activating Pol I transcription.\",\n      \"method\": \"Co-immunoprecipitation, GST pulldown, in vivo acetylation assays, PAF53 localization studies\",\n      \"journal\": \"Journal of Biological Chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro and in vivo interaction and acetylation demonstrated, functional consequence shown, single lab\",\n      \"pmids\": [\"21177859\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Depletion of UBF decreases chromatin binding affinity of B23/nucleophosmin at rDNA, leading to increased histone density at r-chromatin; UBF and RNA binding activity of B23 jointly mediate site-specific targeting of B23 to rDNA chromatin.\",\n      \"method\": \"UBF siRNA knockdown, histone density measurement at r-chromatin, B23 chromatin binding assays\",\n      \"journal\": \"Molecular and Cellular Biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — knockdown with chromatin-level readout, single lab\",\n      \"pmids\": [\"20713446\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"ESET (H3K9 methyltransferase) interacts with UBF and trimethylates UBF at Lys232/254; UBF trimethylation causes nucleolar chromatin condensation and decreased rDNA transcription; UBF K232/254A and K232/254R mutations restore rDNA transcription; ESET-ΔSET mutant and ESET knockdown reduce UBF trimethylation and restore transcription.\",\n      \"method\": \"Co-immunoprecipitation, in vitro methylation assay, ChIP, mutagenesis, atomic force microscopy, shRNA knockdown\",\n      \"journal\": \"Nucleic Acids Research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — direct methylation assay, site-directed mutagenesis, knockdown with rescue, structural imaging\",\n      \"pmids\": [\"24234436\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"PIP2 (phosphatidylinositol 4,5-bisphosphate) associates with UBF and Pol I subunits in a transcription-independent manner throughout the cell cycle; PIP2-UBF colocalization persists during mitosis and after transcription inhibition, suggesting a structural role as anchor for the Pol I pre-initiation complex.\",\n      \"method\": \"Immunoprecipitation, immunofluorescence colocalization, transcription inhibition (actinomycin D, DRB), mitotic arrest\",\n      \"journal\": \"Nucleus\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-IP and co-localization under multiple conditions, single lab\",\n      \"pmids\": [\"24513678\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"UBTF1 and UBTF2 bind highly expressed Pol II-transcribed genes genome-wide (in addition to rDNA); UBTF1/2 is required for recruiting Pol II to histone gene clusters and for their optimal expression; UBTF depletion causes increased accessibility of histone promoters to MNase and DNA damage/genomic instability independent of Pol I transcription; UBTF2 (not active in Pol I transcription) is sufficient to regulate histone gene expression.\",\n      \"method\": \"ChIP-seq, expression array, siRNA depletion, MNase accessibility assay, DNA damage markers\",\n      \"journal\": \"Genome Research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genome-wide ChIP-seq plus functional siRNA depletion with multiple orthogonal readouts, multiple cell systems\",\n      \"pmids\": [\"25452314\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Cisplatin rapidly displaces UBF from ribosomal RNA genes and strongly inhibits ribosomal RNA synthesis; conditional gene deletion of UBF arrests cell proliferation and induces rapid, fully penetrant apoptosis specifically in oncogenically transformed cells in a p53-independent manner.\",\n      \"method\": \"Conditional gene deletion (Cre/lox), cisplatin treatment with UBF ChIP, apoptosis assays in multiple transformed cell lines, p53-null cells\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional KO with multiple cell lines including p53-null, mechanistically specific phenotype\",\n      \"pmids\": [\"26317157\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Disruption of the UBF gene causes disassembly of somatic nucleoli with rRNA gene transcription factors accumulating in dense NPB-like foci; UBF deletion causes rRNA genes to collapse onto centromere-proximal sites; embryonic NPBs and surrounding heterochromatin are disrupted in UBF-null mouse embryos; UBF-null embryos arrest before completing the fourth cleavage division.\",\n      \"method\": \"Conditional gene disruption in mice, fluorescence microscopy, FISH, immunofluorescence\",\n      \"journal\": \"Gene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with precise cellular phenotypes, multiple readouts in both somatic and embryonic cells\",\n      \"pmids\": [\"27614293\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Conditional inactivation of UBF (UBTF) shows that preinitiation complex formation at rDNA is driven by UBF independently of transcription; RPI termination and release corresponds with the TTF1 binding site; the Enhancer Boundary Complex (CTCF and Cohesin) flanks each functional rRNA gene and is maintained even after gene inactivation and re-establishment of repressive chromatin.\",\n      \"method\": \"Conditional UBF inactivation, conditional Rrn3 inactivation, ChIP-seq\",\n      \"journal\": \"PLoS Genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional inactivation of two key factors with high-resolution ChIP-seq, multiple mechanistic conclusions\",\n      \"pmids\": [\"28715449\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"A heterozygous de novo gain-of-function variant p.Glu210Lys in UBF causes markedly increased UBF binding to the rDNA promoter and 5'-external transcribed spacer, increased 18S rRNA expression, and enlarged nucleoli reduced in number, leading to childhood-onset neurodegeneration.\",\n      \"method\": \"Chromatin immunoprecipitation, rRNA expression analysis, immunofluorescence of nucleoli in patient fibroblasts\",\n      \"journal\": \"American Journal of Human Genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP and rRNA analysis in patient cells, single lab, functional validation in patient-derived cells\",\n      \"pmids\": [\"28777933\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"The UBTF p.Glu210Lys mutation results in increased pre-rRNA and 18S rRNA expression, nucleolar abnormalities, markedly increased DNA breaks, and defective cell-cycle progression in patient fibroblasts; expression of mutant UBTF1 in Drosophila neurons is lethal; Ubtf+/- mice show only mild motor and behavioral dysfunction.\",\n      \"method\": \"Patient fibroblast analysis (RT-PCR, rRNA expression, DNA damage markers), Drosophila transgenic expression, mouse heterozygous KO\",\n      \"journal\": \"Human Molecular Genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple model organisms and patient cells, single lab\",\n      \"pmids\": [\"29300972\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"The intracellular domain (ICD) of β-dystroglycan localizes to the nucleolus where it interacts with UBF and B23; overexpression of β-DG ICD mislocalizes UBF, decreases UBF levels, and suppresses rRNA expression; ICD cleavage is induced by nucleolar stressors.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence, rDNA promoter ChIP, rRNA expression analysis, siRNA knockdown\",\n      \"journal\": \"Cell Death & Disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-IP and functional expression/depletion experiments, single lab\",\n      \"pmids\": [\"30814495\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"PKCι directly phosphorylates UBF1 at Ser-412, generating a phosphopeptide-binding epitope that recruits the BRCT domain of ECT2; this UBF1-ECT2 interaction on rDNA promoters is required for elevated rRNA synthesis and transformed growth of NSCLC cells.\",\n      \"method\": \"ECT2 mutagenesis, in vitro kinase assay with MS-based phosphosite identification, lentiviral shRNA knockdown and reconstitution, rRNA synthesis measurement\",\n      \"journal\": \"Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — direct phosphorylation site identified by MS, mutagenesis of both kinase target and binding domain, knockdown/reconstitution functional validation\",\n      \"pmids\": [\"32350115\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"UBTF-TD (exon 13 tandem duplication) maintains genomic occupancy at rDNA loci while also occupying HOXA/HOXB clusters and MEIS1; UBTF-TD co-occupies these loci with KMT2A and menin; UBTF-TD is a gain-of-function alteration causing mislocalization to new genomic targets; stemness, proliferation, and transcriptional signature depend on sustained UBTF-TD chromatin localization.\",\n      \"method\": \"ChIP-seq of UBTF-TD in cord blood CD34+ cells and patient-derived xenografts, protein degradation system, menin inhibitor treatment\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — ChIP-seq plus functional protein degradation experiments plus in vitro and in vivo drug response, multiple models\",\n      \"pmids\": [\"37890156\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Cooperation between SL1 (specifically its TAF1B subunit) and UBTF1 splice variant (not UBTF2) generates the specificity required for rDNA promoter recognition; conditional TAF1B deletion causes striking depletion of UBF at rDNA promoters but not elsewhere; only UBTF1 (not UBTF2) is present with SL1 at promoters.\",\n      \"method\": \"Conditional TAF1B deletion, ChIP-seq of UBTF1 and SL1, UBTF-E210K knock-in cells\",\n      \"journal\": \"PLoS Genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional knockout plus genome-wide ChIP-seq, clear epistasis between TAF1B and UBTF1 at promoters\",\n      \"pmids\": [\"35139074\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"UBTF (UBF) is an architectural HMG-box transcription factor that forms homodimers/heterodimers, binds extensively across the entire rDNA repeat to create a nucleosome-free enhancesome structure, and activates RNA Pol I transcription primarily at the promoter escape step and by regulating elongation through ERK-dependent chromatin remodeling; its activity is tightly controlled by phosphorylation (by CK2, CDK4/cyclin D1, CDK2/cyclin E/A, ERK, S6K1, and PKCι at distinct sites) and acetylation (by CBP, opposed by HDAC1/Rb), with UBF1 splice variant acting cooperatively with SL1/TAF1B for promoter recognition, while UBF also functions at highly expressed Pol II genes (via UBTF2) to maintain genome stability, and gain-of-function mutations (E210K) or tandem duplications in leukemia cause aberrant chromatin occupancy and disease.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"UBTF (UBF) is an architectural HMG-box DNA-binding protein that activates RNA Polymerase I transcription of ribosomal RNA genes and organizes the chromatin of nucleolar organizer regions [#0, #25]. Purified UBF binds both the UCE and core elements of the rDNA promoter and cooperatively recruits the SL1/TBP-TAFI complex through its C-terminal activation domain, forming a protein-DNA complex required for transcriptional activation [#0, #18]. Rather than facilitating pre-initiation complex recruitment, UBF stimulates the transition from initiation to elongation at the promoter-escape step [#33] and relieves repression by negative-acting factors including histone H1 and Ku [#3, #6]. Its HMG boxes contact the DNA minor groove with little sequence specificity [#8], allowing UBF dimers to bend DNA ~175° and assemble phased hemi-enhancesome loops into a higher-order enhancesome structure [#22]. UBF binding extends across the entire rDNA repeat, and UBF levels set the number of transcriptionally active rRNA gene copies by antagonizing H1-mediated silent chromatin assembly [#25, #37]. UBF also physically associates with Pol I and its accessory factor PAF53 to integrate the polymerase into the transcription apparatus [#9, #14]. UBF activity is governed by extensive post-translational control: stimulatory phosphorylation by CK2, CDK4/cyclin D1 and CDK2/cyclin E/A (Ser484, Ser388), S6K1 downstream of mTOR, and PKCι (Ser412), versus ERK phosphorylation within HMG boxes 1 and 2 that unfolds the enhancesome to regulate elongation [#16, #24, #27, #51, #23, #32]; and by an acetylation–deacetylation switch in which CBP and HDAC1/Rb compete, alongside repressive ESET-mediated trimethylation and Rb/p130 binding that blocks UBF-SL1 contact [#21, #42, #20]. Two splice isoforms, UBF1 and UBF2, differ in HMG box 2: UBF1 is the potent Pol I activator that, with the SL1 TAF1B subunit, confers rDNA promoter specificity, while UBF2 cannot bend DNA but binds and regulates highly expressed Pol II genes such as histone clusters to maintain genome stability [#10, #53, #44, #38]. UBF deletion disassembles nucleoli and arrests early embryogenesis, and its loss triggers p53-independent apoptosis selectively in transformed cells [#46, #45]. Gain-of-function alterations—the de novo p.Glu210Lys variant causing childhood-onset neurodegeneration and exon-13 tandem duplications in leukemia—produce aberrant chromatin occupancy and disease [#48, #52].\",\n  \"teleology\": [\n    {\n      \"year\": 1988,\n      \"claim\": \"Established UBF as a sequence-specific activator of Pol I transcription that works through cooperative recruitment of the SL1 promoter-selectivity factor, defining the founding model of rDNA activation.\",\n      \"evidence\": \"In vitro transcription reconstitution and DNase I footprinting with purified UBF1\",\n      \"pmids\": [\"3413483\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve which step of the transcription cycle UBF stimulates\", \"Mechanism of cooperative complex formation with SL1 not defined structurally\"]\n    },\n    {\n      \"year\": 1991,\n      \"claim\": \"Resolved that UBF exists as two alternatively spliced isoforms differing in HMG box 2, raising the question of whether the isoforms are functionally distinct.\",\n      \"evidence\": \"cDNA cloning, PCR, and probe protection in vertebrate cells\",\n      \"pmids\": [\"2014238\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional difference between UBF1 and UBF2 not yet tested\", \"Did not address isoform-specific binding or activity\"]\n    },\n    {\n      \"year\": 1991,\n      \"claim\": \"Identified UBF as the NOR-90 autoantigen that stays bound to nucleolar organizer regions through mitosis, implying a constitutive structural role beyond active transcription.\",\n      \"evidence\": \"cDNA cloning, immunoprecipitation, and mitotic immunofluorescence\",\n      \"pmids\": [\"1940801\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of mitotic NOR retention unclear\", \"Did not distinguish active from inactive gene binding\"]\n    },\n    {\n      \"year\": 1992,\n      \"claim\": \"Showed UBF acts as an antirepressor relieving inhibition by histone H1 and competing negative factors, and that its activity depends on serine phosphorylation regulated by growth signals.\",\n      \"evidence\": \"Reconstituted in vitro transcription, in vivo 32P labeling, and serum-deprivation experiments\",\n      \"pmids\": [\"1502143\", \"1730600\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific kinases and phosphosites not identified\", \"Mechanism of H1 antagonism at chromatin level not defined\"]\n    },\n    {\n      \"year\": 1992,\n      \"claim\": \"Defined the structural basis of UBF self-association and DNA binding, localizing dimerization to the N-terminus and isoform differences to HMG box 2.\",\n      \"evidence\": \"Glutaraldehyde cross-linking, overlay, and Southwestern assays with recombinant proteins\",\n      \"pmids\": [\"1561086\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab biochemistry without structural confirmation\", \"Functional consequence of heterodimerization not established\"]\n    },\n    {\n      \"year\": 1994,\n      \"claim\": \"Characterized UBF DNA-binding mode as minor-groove, sequence-tolerant, and structure-selective (cruciform/bent DNA), and showed UBF1 is a far stronger activator than UBF2 with HMG box 4 dictating species specificity.\",\n      \"evidence\": \"Methylation interference, four-way junction and cruciform binding, hybrid-UBF in vitro transcription\",\n      \"pmids\": [\"8041627\", \"8313887\", \"8524646\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How structure-selective binding translates to in vivo enhancesome geometry unresolved\", \"Basis of UBF2 functional weakness mechanistically incomplete\"]\n    },\n    {\n      \"year\": 1994,\n      \"claim\": \"Demonstrated that UBF physically engages Pol I through its HMG boxes via a conserved polymerase-specific subunit, and that PAF53 bridges this interaction during initiation.\",\n      \"evidence\": \"Immunoprecipitation, glycerol gradient, affinity chromatography, and Far-Western/GST pulldown\",\n      \"pmids\": [\"8306961\", \"8641287\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry of the UBF-Pol I-PAF53 assembly not defined\", \"How this contact promotes a specific transcription step not yet addressed\"]\n    },\n    {\n      \"year\": 1995,\n      \"claim\": \"Identified Rb as a direct UBF repressor and established that multisite phosphorylation, including CK2 sites, is required to render UBF transcriptionally active, linking growth and tumor-suppressor signaling to rDNA output.\",\n      \"evidence\": \"In vitro transcription with recombinant UBF, phosphopeptide mapping, Rb affinity chromatography and co-IP\",\n      \"pmids\": [\"7877691\", \"7651819\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Precise step Rb blocks not yet defined\", \"Individual growth-dependent kinase identities pending\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Mapped cell-cycle control of UBF to CDK4/cyclin D1 and CDK2/cyclin E phosphorylation of Ser484, and to mitotic inactivation/G1 reactivation, coupling Pol I output to cell-cycle progression.\",\n      \"evidence\": \"Phosphopeptide mapping, Ser484 mutagenesis, in vitro kinase and synchronized-extract transcription assays\",\n      \"pmids\": [\"10202152\", \"10339547\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mitotic kinase responsible not pinpointed\", \"Relationship between Ser484 and the UBF-SL1 contact not yet integrated\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Showed the UBF C-terminal activation domain directly contacts SL1 in a phosphorylation-dependent manner, providing the molecular basis for how growth signals gate enhancesome-SL1 coupling.\",\n      \"evidence\": \"Deletion mapping, phosphatase treatment, footprinting, and in vitro transcription including an SV40 large T-associated kinase\",\n      \"pmids\": [\"10082553\", \"10082545\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological kinase generating this modification not fully resolved\", \"Contact interface on SL1 not structurally defined\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Defined opposing post-translational switches: Rb/p130 block UBF-SL1 contact without affecting DNA binding, while CBP acetylation derepresses transcription, establishing an acetylation–deacetylation regulatory hub.\",\n      \"evidence\": \"Co-IP, band-shift, in vitro and in vivo acetylation, and reconstituted transcription\",\n      \"pmids\": [\"11042686\", \"11106745\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"UBF acetylation sites not mapped\", \"How acetylation status feeds into the SL1 contact vs Pol I contact not separated\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Resolved the enhancesome architecture (paired hemi-enhancesomes bending DNA ~175°) and showed ERK phosphorylation within HMG boxes 1/2 disrupts DNA contact, while CDK2-mediated Ser388 phosphorylation enables UBF-Pol I interaction.\",\n      \"evidence\": \"Insertion/deletion mutagenesis, electron microscopy, ERK and CDK2 site mutagenesis, transcription run-on\",\n      \"pmids\": [\"11470882\", \"11741541\", \"11698641\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How antagonistic phosphorylation events are temporally coordinated unclear\", \"ERK-induced unfolding not yet linked to a specific transcription step\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Demonstrated by ChIP that UBF coats the entire rDNA repeat rather than only regulatory sequences, cementing a structural role at active NORs, and identified TAF1 as a direct UBF partner.\",\n      \"evidence\": \"ChIP from nucleolar chromatin across species, yeast two-hybrid, co-IP, and in vitro transcription\",\n      \"pmids\": [\"11756560\", \"12498690\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of genome-wide rDNA coverage not directly tested here\", \"TAF1-UBF interplay with SL1 not integrated\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Placed UBF downstream of mTOR signaling, showing S6K1 phosphorylates the UBF activation domain to maintain SL1 association, providing the nutrient-sensing link to ribosome biogenesis.\",\n      \"evidence\": \"Rapamycin treatment, S6K1 mutants, and rescue with purified phosphorylated vs hypophosphorylated UBF\",\n      \"pmids\": [\"14612424\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Exact S6K1 target residues not pinpointed\", \"Crosstalk with CK2/ERK phosphorylation not resolved\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Revealed an unexpected Pol II role: UBF2 partners with LEF-1/β-catenin to potentiate Pol II promoter activity, broadening UBF function beyond rDNA.\",\n      \"evidence\": \"Functional screen, co-IP, reporter assays, and siRNA knockdown\",\n      \"pmids\": [\"12748295\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Genome-wide Pol II targets not yet defined\", \"Mechanism of UBF2 action at Pol II promoters unclear\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Showed UBF chromatin arrays alone are sufficient to nucleate pseudo-NORs that sequester the entire Pol I machinery independent of transcription, establishing UBF as the primary determinant of NOR identity.\",\n      \"evidence\": \"Ectopic chromosomal integration of UBF-binding arrays with immunofluorescence and ChIP; also c-MYC/MAD1 epistasis at the UBF gene\",\n      \"pmids\": [\"15598984\", \"15282543\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Minimal protein interactions needed for sequestration not dissected\", \"Relationship between pseudo-NOR and functional rRNA synthesis not addressed\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Reframed UBF as an elongation/promoter-escape regulator rather than a PIC-recruitment factor, with ERK phosphorylation remodeling rDNA chromatin to control elongation rate.\",\n      \"evidence\": \"Reconstituted transcription with PIC stabilization assays, Pol I engagement and elongation-rate measurements, electron spectroscopic imaging of enhancesome unfolding\",\n      \"pmids\": [\"16858408\", \"16507361\", \"16533045\", \"16971462\", \"16582105\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How promoter-escape stimulation reconciles with genome-wide rDNA coating not fully resolved\", \"Acetylation/CK2 inputs to escape vs reinitiation not separated\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Established UBF as the dosage-dependent determinant of active rRNA gene copy number, with depletion driving H1-induced, methylation-independent silencing reversible by ERK-site mutation; defined UBF1 vs UBF2 contributions to chromatin folding and ERK responsiveness.\",\n      \"evidence\": \"Conditional UBF depletion/overexpression with H1 and methylation ChIP, ERK-site mutagenesis, and isoform DNA-bending/elongation assays\",\n      \"pmids\": [\"19103806\", \"18676449\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How UBF level is read out into a binary active/silent gene state not mechanistically resolved\", \"Compensatory transcription-rate increase mechanism unclear\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Connected UBF to nucleolar factor recruitment, showing it directs B23/nucleophosmin to rDNA chromatin and is acetylated by the t-UTP hALP to promote PAF53/Pol I association.\",\n      \"evidence\": \"siRNA knockdown with chromatin readouts, co-IP, GST pulldown, and acetylation assays\",\n      \"pmids\": [\"20713446\", \"21177859\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab studies without structural detail\", \"Hierarchy of recruitment events not fully ordered\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Identified repressive UBF modifications, ESET-mediated trimethylation at Lys232/254 condensing nucleolar chromatin, and a transcription-independent PIP2-UBF structural association.\",\n      \"evidence\": \"In vitro methylation, lysine mutagenesis with rescue, atomic force microscopy, shRNA knockdown, and PIP2 co-IP/colocalization\",\n      \"pmids\": [\"24234436\", \"24513678\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"PIP2-UBF functional role remains correlative\", \"How methylation and acetylation switches are coordinated unclear\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Demonstrated a genome-stability function: UBTF (especially UBTF2) binds and maintains accessible chromatin at highly expressed Pol II genes such as histone clusters, with depletion causing genomic instability independent of Pol I.\",\n      \"evidence\": \"ChIP-seq, expression arrays, siRNA depletion, MNase accessibility, and DNA-damage markers\",\n      \"pmids\": [\"25452314\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How UBTF2 selects Pol II target genes not defined\", \"Mechanistic link from chromatin accessibility to genome stability incomplete\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Showed UBF is essential for proliferation and is a selective vulnerability of transformed cells, where its deletion or cisplatin-induced displacement triggers p53-independent apoptosis.\",\n      \"evidence\": \"Conditional Cre/lox deletion across transformed cell lines including p53-null, cisplatin treatment with UBF ChIP, and apoptosis assays\",\n      \"pmids\": [\"26317157\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Apoptotic effector pathway downstream of UBF loss not defined\", \"Basis of transformed-cell selectivity unclear\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Established UBF as required for nucleolar assembly and early embryogenesis, with its loss disassembling nucleoli, collapsing rRNA genes to centromere-proximal sites, and arresting embryos at the fourth cleavage.\",\n      \"evidence\": \"Conditional gene disruption in mice with FISH and immunofluorescence\",\n      \"pmids\": [\"27614293\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Sequence of events from UBF loss to nucleolar disassembly not fully ordered\", \"Whether arrest reflects transcriptional or structural failure not separated\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Defined the architecture of the functional rRNA gene unit, showing UBF drives PIC formation independently of transcription and that CTCF/cohesin Enhancer Boundary Complexes persist across gene activity states.\",\n      \"evidence\": \"Conditional UBF and Rrn3 inactivation with high-resolution ChIP-seq\",\n      \"pmids\": [\"28715449\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Interplay between UBF occupancy and boundary complex maintenance not mechanistically resolved\", \"How transcription-independent PIC formation is regulated unclear\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Linked UBF directly to human disease, identifying a de novo gain-of-function p.Glu210Lys variant causing increased rDNA occupancy, elevated rRNA, nucleolar changes, and childhood-onset neurodegeneration.\",\n      \"evidence\": \"ChIP, rRNA expression, and nucleolar immunofluorescence in patient fibroblasts, with cross-organism modeling\",\n      \"pmids\": [\"28777933\", \"29300972\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism connecting hyperactive UBF to neuronal vulnerability unresolved\", \"Discrepancy between severe Drosophila lethality and mild mouse phenotype unexplained\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Identified β-dystroglycan ICD as a nucleolar UBF regulator coupling nucleolar stress to UBF mislocalization and suppressed rRNA synthesis.\",\n      \"evidence\": \"Co-IP, immunofluorescence, rDNA ChIP, and rRNA expression with siRNA knockdown\",\n      \"pmids\": [\"30814495\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab study; physiological relevance of the interaction untested in vivo\", \"Stress-signaling input to ICD cleavage not fully defined\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Defined an oncogenic phosphorylation event, PKCι phosphorylation of UBF1 Ser412 that creates a docking site for the ECT2 BRCT domain to drive rRNA synthesis and transformed growth in lung cancer.\",\n      \"evidence\": \"MS-based phosphosite mapping, ECT2 and kinase mutagenesis, and shRNA knockdown/reconstitution with rRNA measurement\",\n      \"pmids\": [\"32350115\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How the UBF1-ECT2 complex mechanistically elevates rRNA synthesis not detailed\", \"Generality beyond NSCLC not established\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Resolved how isoform-SL1 cooperation generates rDNA promoter specificity and how leukemogenic tandem duplications redirect UBTF to ectopic oncogenic loci.\",\n      \"evidence\": \"Conditional TAF1B deletion with UBTF1/SL1 ChIP-seq, and UBTF-TD ChIP-seq with protein degradation and menin-inhibitor treatment in leukemia models\",\n      \"pmids\": [\"35139074\", \"37890156\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How TD acquires affinity for HOXA/HOXB/MEIS1 loci not structurally defined\", \"Whether ectopic occupancy reflects altered DNA-binding or partner recruitment unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the many antagonistic UBF modifications (CK2, CDK, ERK, S6K1, PKCι phosphorylation; CBP acetylation; ESET methylation) are integrated in real time to set enhancesome state, promoter escape, and active gene number remains unresolved, as does the structural basis by which gain-of-function variants reprogram genomic occupancy.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No integrated model coordinating the multiple PTM switches\", \"No high-resolution structure of the UBF enhancesome on rDNA\", \"Mechanism by which E210K and exon-13 duplication alter target selection unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [0, 8, 10, 22, 25]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [0, 3, 10, 33, 44]},\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [8]},\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [22, 25, 29, 37]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 9, 18]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005730\", \"supporting_discovery_ids\": [2, 7, 25, 46]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [4, 28, 44]},\n      {\"term_id\": \"GO:0005694\", \"supporting_discovery_ids\": [2, 7, 29, 46]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0, 3, 25, 33, 44]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [16, 17, 24, 35]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [23, 27, 32, 51]},\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [37, 42, 44]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [48, 49, 52]},\n      {\"term_id\": \"R-HSA-1852241\", \"supporting_discovery_ids\": [29, 46]}\n    ],\n    \"complexes\": [\n      \"rDNA enhancesome\",\n      \"nucleolar organizer region (NOR)\"\n    ],\n    \"partners\": [\n      \"SL1/TAF1B\",\n      \"RNA Pol I\",\n      \"PAF53\",\n      \"RB1\",\n      \"CBP\",\n      \"ECT2\",\n      \"B23/NPM1\",\n      \"LEF1\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":10,"faith_total":10,"faith_pct":100.0}}