{"gene":"USP51","run_date":"2026-06-11T09:02:06","timeline":{"discoveries":[{"year":2016,"finding":"USP51 directly binds H2A-H2B and deubiquitylates histone H2A at K13 and K15 (H2AK13,15ub) in vitro. In cells, USP51 is recruited to chromatin after DNA damage and regulates dynamic assembly/disassembly of 53BP1 and BRCA1 foci. USP51 overexpression suppresses 53BP1 and BRCA1 but not RNF168 foci, placing USP51 downstream of RNF168 in the DNA damage response pathway.","method":"In vitro deubiquitylation assay, direct binding assay (H2A-H2B pulldown), chromatin fractionation, epistasis via foci analysis (RNF168/53BP1/BRCA1), USP51 depletion/overexpression","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — in vitro biochemical reconstitution of DUB activity, direct binding assay, genetic epistasis by foci analysis, replicated across multiple orthogonal methods in one rigorous study","pmids":["27083998"],"is_preprint":false},{"year":2018,"finding":"USP51 deubiquitylates H2AK13Ub, H2AK15Ub, and H2AK119Ub in vitro on reconstituted nucleosomes without site selectivity (in contrast to in vivo observations). USP51 can also deubiquitylate H2BK120Ub but not H2BK34Ub in vitro. Molecular dynamics simulations suggest steric hindrance of the isopeptide bond affects USP51 catalytic activity on certain sites.","method":"Total chemical protein synthesis of ubiquitylated histones, nucleosome reconstitution, in vitro deubiquitylation assay, molecular dynamics simulation","journal":"Chembiochem","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with chemically defined substrates and mutagenesis-equivalent site-specific probes, single lab but multiple orthogonal biochemical methods","pmids":["30192049"],"is_preprint":false},{"year":2017,"finding":"USP51 binds, deubiquitinates, and stabilizes the transcription factor ZEB1, identified by screening a human deubiquitinase library. Depletion of USP51 in mesenchymal-like breast cancer cells leads to downregulation of ZEB1 protein, upregulation of E-cadherin, downregulation of mesenchymal markers, and inhibition of cell invasion.","method":"Deubiquitinase library screen, co-immunoprecipitation, ubiquitination assay, USP51 depletion/overexpression, cell invasion assay","journal":"American journal of cancer research","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — Co-IP and deubiquitination assay confirmed in cells, multiple functional readouts, single lab","pmids":["29119051"],"is_preprint":false},{"year":2020,"finding":"CDK4/6 phosphorylates and activates USP51, which is necessary for USP51 to deubiquitinate and stabilize ZEB1, thereby promoting breast cancer metastasis. This establishes a CDK4/6-USP51-ZEB1 signaling axis.","method":"In vitro phosphorylation assay, co-immunoprecipitation, ubiquitination assay, USP51 depletion/overexpression, in vivo tumor metastasis models, tissue correlation analysis","journal":"Signal transduction and targeted therapy","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — biochemical phosphorylation and deubiquitination assays combined with in vivo functional data, single lab","pmids":["32296027"],"is_preprint":false},{"year":2023,"finding":"USP51 directly binds Elongin C (ELOC) and forms a functional complex with the VHL E3 ligase (USP51/VHL/CUL2/ELOB/ELOC/RBX1). Within this complex, USP51 deubiquitinates HIF1A and stabilizes it, activating hypoxia-induced gene transcription. SUMOylation of ELOC at K32 inhibits its binding to USP51; SENP1-mediated deSUMOylation of ELOC promotes USP51-ELOC binding and facilitates HIF1A stabilization.","method":"Co-immunoprecipitation, ubiquitination/deubiquitination assay, SUMOylation assay, SENP1 manipulation, USP51 depletion/overexpression, functional readouts (proliferation, migration, stemness)","journal":"Cell death and differentiation","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — multiple Co-IP and biochemical assays in single lab, multiple orthogonal methods but no in vitro reconstitution","pmids":["37816999"],"is_preprint":false},{"year":2023,"finding":"USP51 deubiquitinates and stabilizes PD-L1 protein in NSCLC cells. PD-L1, stabilized by USP51, directly binds ITGB1 at the cell membrane and activates NF-κB signaling to promote chemoresistance.","method":"Co-immunoprecipitation, pulldown assay, protein deubiquitination assay, Ub-AMC-based DUB activity assay, cellular thermal shift assay, surface plasmon resonance (SPR), USP51 depletion/overexpression","journal":"Cancer communications","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — biochemical DUB activity and SPR confirm USP51-PD-L1 interaction and deubiquitination, single lab with multiple orthogonal methods","pmids":["37386737"],"is_preprint":false},{"year":2019,"finding":"USP51 directly binds FAT4 (confirmed by co-immunoprecipitation). USP51 stabilizes FAT4 protein; ablation of USP51 decreases FAT4 protein levels while overexpression increases them. USP51-FAT4 interaction is required for FAT4's tumor-suppressive function via the Hippo pathway in endometrial cancer cells.","method":"Co-immunoprecipitation, USP51 shRNA knockdown/overexpression, FAT4 protein level measurement, Hippo pathway activity assay (LATS1/2 phosphorylation, YAP localization)","journal":"American journal of translational research","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — Co-IP confirmed direct binding, functional rescue experiments, single lab","pmids":["31217854"],"is_preprint":false},{"year":2023,"finding":"USP51 deubiquitinates TWIST1, attenuating its polyubiquitination and stabilizing the TWIST1 protein, thereby maintaining cancer stem cell properties in NSCLC cells. Re-expression of TWIST1 rescued the inhibitory effects of USP51 knockdown on cell stemness.","method":"Cycloheximide chase assay, polyubiquitination assay, USP51 overexpression/knockdown, TWIST1 rescue experiment, colony/sphere formation assays, in vivo xenograft","journal":"Journal of translational medicine","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — ubiquitination assay and protein stability assay with functional rescue, single lab","pmids":["37422632"],"is_preprint":false},{"year":2024,"finding":"USP51 deubiquitinates GPX4, stabilizing it and protecting it from proteasomal degradation. Reduction of USP51 by berbamine leads to increased ubiquitination and degradation of GPX4, triggering ferroptosis in esophageal squamous cell carcinoma cells. USP51 overexpression rescues GPX4 from BBM-induced downregulation.","method":"Ubiquitination/deubiquitination assay, USP51 overexpression rescue experiment, cell death assay (ferroptosis markers: Fe, ROS, MDA), in vivo xenograft","journal":"Biomedicine & pharmacotherapy","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — biochemical ubiquitination assay with functional rescue, single lab","pmids":["39151312"],"is_preprint":false},{"year":2019,"finding":"AMPK activation by hispidulin upregulates USP51 expression, which in turn stabilizes the pro-apoptotic protein Bim at the post-translational level, sensitizing cancer cells to TRAIL-induced apoptosis. Depletion of Bim blocks this effect.","method":"USP51 expression analysis, siRNA depletion of Bim and USP51, AMPK activation, apoptosis assay, in vivo xenograft","journal":"Cancers","confidence":"Low","confidence_rationale":"Tier 3 / Weak — indirect evidence linking AMPK-USP51-Bim without direct biochemical demonstration of USP51-Bim deubiquitination, single lab","pmids":["31817696"],"is_preprint":false},{"year":2022,"finding":"CDK4/6 phosphorylates and activates USP51 in lung adenocarcinoma, leading to deubiquitination and stabilization of ZEB1, thereby promoting tumor metastasis. p-USP51 and ZEB1 levels are positively correlated in human lung adenocarcinoma samples.","method":"Phosphorylation assay, co-immunoprecipitation, ubiquitination assay, USP51 depletion/overexpression, in vitro invasion assays, clinical tissue correlation","journal":"Cancer gene therapy","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — replicates CDK4/6-USP51-ZEB1 mechanism in a distinct cancer model with biochemical and functional validation, single lab","pmids":["35058607"],"is_preprint":false},{"year":2025,"finding":"USP51 deubiquitinates and stabilizes GRP78. This stabilization increases GRP78 cell-surface localization, which enhances ABCB1 efflux pump activity and reduces doxorubicin accumulation in triple-negative breast cancer cells, conferring chemoresistance.","method":"Co-immunoprecipitation, ubiquitination/deubiquitination assay, USP51 overexpression, cell surface GRP78 localization assay, doxorubicin accumulation assay, in vivo xenograft","journal":"Acta pharmaceutica Sinica B","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — biochemical deubiquitination and functional localization assays, single lab with multiple orthogonal methods","pmids":["40487653"],"is_preprint":false},{"year":2025,"finding":"USP51 directly interacts with NEK8, reduces its ubiquitination level, and stabilizes NEK8 protein. NEK8 stabilization by USP51 promotes colorectal cancer cell proliferation and invasion through activation of the WNT/β-catenin pathway.","method":"Co-immunoprecipitation, co-immunofluorescence, ubiquitination assay, functional rescue experiments, USP51/NEK8 knockdown, WNT/β-catenin pathway readout (β-catenin protein levels), subcutaneous tumor formation","journal":"Pathology, research and practice","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — Co-IP, co-IF, ubiquitination assay, and functional rescue experiments, single lab","pmids":["41475333"],"is_preprint":false},{"year":2025,"finding":"CDK4/6 kinase activity and USP51 cooperate to enhance ZEB1 protein stability via deubiquitination, promoting cell migration in a mesenchymal breast cancer model. Suppression of USP51 or CDK4/6 attenuates ZEB1 stability and cell migration.","method":"Ubiquitin-proteasome pathway analysis, CDK4/6 and USP51 inhibition/knockdown, ZEB1 protein stability assay, cell migration assay","journal":"Scientific reports","confidence":"Low","confidence_rationale":"Tier 3 / Weak — replicates CDK4/6-USP51-ZEB1 axis but uses less rigorous biochemical methods; single lab, limited new mechanistic detail beyond prior studies","pmids":["40877392"],"is_preprint":false}],"current_model":"USP51 is a deubiquitinase (DUB) that removes ubiquitin from multiple substrates including histone H2A at K13/K15 (acting downstream of RNF168 in the DNA damage response), ZEB1 (activated by CDK4/6-mediated phosphorylation of USP51 to promote EMT and metastasis), HIF1A (within a VHL/CUL2 complex, regulated by SENP1-mediated deSUMOylation of ELOC), PD-L1, GPX4, GRP78, TWIST1, FAT4, NEK8, and Bim, thereby controlling protein stability and a broad set of cancer-related cellular processes including DNA repair, EMT, stemness, and chemoresistance."},"narrative":{"mechanistic_narrative":"USP51 is a deubiquitinase that controls protein stability across DNA repair, transcription, and a broad spectrum of cancer-associated processes by removing ubiquitin from chromatin and multiple non-histone substrates [PMID:27083998, PMID:29119051]. In the DNA damage response, USP51 directly binds the H2A-H2B dimer and deubiquitylates histone H2A at K13/K15, acting downstream of RNF168 to regulate the dynamic assembly and disassembly of 53BP1 and BRCA1 foci [PMID:27083998]; biochemically it processes H2AK13ub, H2AK15ub, H2AK119ub, and H2BK120ub on reconstituted nucleosomes, with site discrimination governed by steric accessibility of the isopeptide bond [PMID:30192049]. Beyond chromatin, USP51 functions as a stabilizing DUB for an array of substrates: it deubiquitinates and stabilizes the EMT transcription factor ZEB1, an activity that requires CDK4/6-mediated phosphorylation of USP51 and drives breast and lung cancer metastasis through a CDK4/6-USP51-ZEB1 axis [PMID:29119051, PMID:32296027, PMID:35058607]. USP51 also assembles into the VHL/CUL2/ELOB/ELOC/RBX1 complex via direct binding to Elongin C, where it deubiquitinates and stabilizes HIF1A to activate hypoxia-induced transcription, a step gated by SENP1-mediated deSUMOylation of ELOC [PMID:37816999]. Through stabilization of additional substrates—PD-L1, TWIST1, GPX4, GRP78, FAT4, and NEK8—USP51 promotes chemoresistance, cancer stemness, ferroptosis resistance, and Hippo and WNT/β-catenin pathway modulation [PMID:37386737, PMID:31217854, PMID:37422632, PMID:39151312, PMID:40487653, PMID:41475333].","teleology":[{"year":2016,"claim":"Established USP51 as a chromatin-acting deubiquitinase that targets histone H2A and modulates DNA damage signaling, defining its first molecular function and pathway position.","evidence":"In vitro deubiquitylation and H2A-H2B binding assays with chromatin fractionation and 53BP1/BRCA1/RNF168 foci epistasis after DNA damage","pmids":["27083998"],"confidence":"High","gaps":["Site selectivity for H2AK13/K15 in cells not explained biochemically","Recruitment mechanism to damaged chromatin unresolved"]},{"year":2018,"claim":"Defined the intrinsic substrate range of USP51 on defined nucleosomal substrates, showing the in vivo site selectivity is not an intrinsic enzymatic property but is set by structural accessibility.","evidence":"Total chemical synthesis of ubiquitylated histones, nucleosome reconstitution, in vitro DUB assays, and molecular dynamics simulation","pmids":["30192049"],"confidence":"High","gaps":["What confers in-cell site selectivity (cofactors, recruitment) remains unknown","No structural model of the USP51-nucleosome complex"]},{"year":2017,"claim":"Extended USP51 function beyond chromatin by identifying ZEB1 as a stabilized substrate, linking the DUB to EMT control in breast cancer.","evidence":"Deubiquitinase library screen, Co-IP, ubiquitination assays, and cell invasion assays in mesenchymal breast cancer cells","pmids":["29119051"],"confidence":"Medium","gaps":["Direct deubiquitination not reconstituted in vitro","Ubiquitin chain type on ZEB1 not defined"]},{"year":2020,"claim":"Showed that USP51 activity toward ZEB1 is switched on by CDK4/6 phosphorylation, establishing an upstream regulatory kinase axis driving metastasis.","evidence":"In vitro phosphorylation, Co-IP, ubiquitination assays, in vivo metastasis models, and tissue correlation","pmids":["32296027"],"confidence":"Medium","gaps":["Phosphosite(s) on USP51 not mapped to catalytic mechanism","Single lab"]},{"year":2022,"claim":"Replicated the CDK4/6-USP51-ZEB1 axis in lung adenocarcinoma, generalizing the mechanism across cancer types.","evidence":"Phosphorylation and ubiquitination assays, Co-IP, invasion assays, and clinical tissue correlation","pmids":["35058607"],"confidence":"Medium","gaps":["Mechanistic detail beyond prior breast cancer work limited","Single lab"]},{"year":2019,"claim":"Placed USP51 within a tumor-suppressive context by stabilizing FAT4 to modulate Hippo signaling, indicating context-dependent functional outputs.","evidence":"Co-IP, USP51 knockdown/overexpression, FAT4 protein measurement, and Hippo pathway readouts in endometrial cancer cells","pmids":["31217854"],"confidence":"Medium","gaps":["Direct deubiquitination of FAT4 not biochemically demonstrated","Reconciliation with oncogenic roles elsewhere not addressed"]},{"year":2019,"claim":"Linked AMPK signaling to USP51-dependent stabilization of pro-apoptotic Bim, implicating USP51 in apoptosis sensitization.","evidence":"siRNA depletion of USP51 and Bim, AMPK activation, apoptosis assays, and xenograft","pmids":["31817696"],"confidence":"Low","gaps":["No direct biochemical demonstration of USP51-Bim deubiquitination","Causal link is indirect"]},{"year":2023,"claim":"Defined USP51 as a functional subunit of the VHL/CUL2 complex that deubiquitinates HIF1A, with its incorporation controlled by SENP1-driven deSUMOylation of ELOC.","evidence":"Co-IP, ubiquitination/deubiquitination and SUMOylation assays, SENP1 manipulation, and functional readouts","pmids":["37816999"],"confidence":"Medium","gaps":["No in vitro reconstitution of the USP51-VHL complex","Stoichiometry within the CUL2 ligase unresolved"]},{"year":2023,"claim":"Identified PD-L1 as a USP51 substrate, connecting the DUB to immune-checkpoint protein stability and NF-κB-driven chemoresistance.","evidence":"Co-IP, pulldown, Ub-AMC DUB activity assay, cellular thermal shift, and SPR in NSCLC cells","pmids":["37386737"],"confidence":"Medium","gaps":["In vivo relevance of PD-L1-ITGB1 axis incompletely defined","Single lab"]},{"year":2023,"claim":"Showed USP51 stabilizes TWIST1 to maintain cancer stem cell properties, expanding its role in stemness control.","evidence":"Cycloheximide chase, polyubiquitination assays, TWIST1 rescue, sphere formation, and xenograft in NSCLC","pmids":["37422632"],"confidence":"Medium","gaps":["Direct in vitro deubiquitination not shown","Ubiquitin linkage type unspecified"]},{"year":2024,"claim":"Connected USP51 to ferroptosis regulation by stabilizing GPX4, defining a redox-survival function exploitable by berbamine.","evidence":"Ubiquitination/deubiquitination and rescue assays, ferroptosis markers, and xenograft in esophageal squamous cell carcinoma","pmids":["39151312"],"confidence":"Medium","gaps":["Whether USP51 directly binds GPX4 not fully established","Single lab"]},{"year":2025,"claim":"Demonstrated USP51 stabilization of GRP78 promotes cell-surface GRP78 and ABCB1-mediated drug efflux, providing a mechanism for chemoresistance.","evidence":"Co-IP, ubiquitination/deubiquitination assays, surface GRP78 localization, doxorubicin accumulation, and xenograft in TNBC","pmids":["40487653"],"confidence":"Medium","gaps":["Mechanism coupling GRP78 deubiquitination to surface trafficking unclear","Single lab"]},{"year":2025,"claim":"Added NEK8 as a USP51 substrate driving WNT/β-catenin-dependent colorectal cancer proliferation, broadening the oncogenic substrate set.","evidence":"Co-IP, co-IF, ubiquitination assays, functional rescue, and subcutaneous tumor formation","pmids":["41475333"],"confidence":"Medium","gaps":["Direct in vitro deubiquitination not reconstituted","Single lab"]},{"year":null,"claim":"How USP51 substrate selection and site specificity are governed in cells across such a broad substrate repertoire, and how its phosphorylation and complex incorporation are coordinated, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of USP51 bound to any substrate","No unifying determinant of in-cell substrate/site selectivity","Reconciliation of tumor-suppressive (FAT4, Bim) versus oncogenic substrate roles unaddressed"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,1,2,4,5,7,8,11,12]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[0,1,5]},{"term_id":"GO:0042393","term_label":"histone binding","supporting_discovery_ids":[0,1]}],"localization":[{"term_id":"GO:0005694","term_label":"chromosome","supporting_discovery_ids":[0]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,12]}],"pathway":[{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[0]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[2,4,5,7,8,11,12]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[4,6,12]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[3,5,10,11]}],"complexes":["VHL/CUL2/ELOB/ELOC/RBX1 ubiquitin ligase complex"],"partners":["ZEB1","HIF1A","ELOC","PD-L1","FAT4","TWIST1","GPX4","NEK8"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q70EK9","full_name":"Ubiquitin carboxyl-terminal hydrolase 51","aliases":["Deubiquitinating enzyme 51","Ubiquitin thioesterase 51","Ubiquitin-specific-processing protease 51"],"length_aa":711,"mass_kda":79.8,"function":"Specifically deubiquitinates 'Lys-14' (H2AK13Ub) and 'Lys-16'(H2AK15Ub) of histone H2A regulating the DNA damage response at double-strand breaks (DSBs) (PubMed:27083998, PubMed:33022275). USP51 is recruited to chromatin after DNA damage and regulates the dynamic assembly/disassembly of TP53BP1 and BRCA1. Functions in DNA double-strand break repair also by mediating the deubiquitination and subsequent stabilization of DGCR8, leading to the recruitment of DGCR8 binding partners to double strand breaks such as RNF168 or MDC1 (PubMed:34188037). In addition, promotes the deubiquitination and stabilization of the transcriptional repressor ZEB1 (PubMed:29119051)","subcellular_location":"Chromosome","url":"https://www.uniprot.org/uniprotkb/Q70EK9/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/USP51","classification":"Not Classified","n_dependent_lines":3,"n_total_lines":1208,"dependency_fraction":0.0024834437086092716},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/USP51","total_profiled":1310},"omim":[],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Cytosol","reliability":"Approved"},{"location":"Nucleoli fibrillar center","reliability":"Additional"}],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"epididymis","ntpm":46.7}],"url":"https://www.proteinatlas.org/search/USP51"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"Q70EK9","domains":[{"cath_id":"3.30.40.10","chopping":"202-312","consensus_level":"high","plddt":87.6555,"start":202,"end":312},{"cath_id":"-","chopping":"372-466","consensus_level":"high","plddt":92.0314,"start":372,"end":466},{"cath_id":"3.90.70.10","chopping":"490-520_546-709","consensus_level":"medium","plddt":88.6126,"start":490,"end":709}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q70EK9","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q70EK9-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q70EK9-F1-predicted_aligned_error_v6.png","plddt_mean":68.44},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=USP51","jax_strain_url":"https://www.jax.org/strain/search?query=USP51"},"sequence":{"accession":"Q70EK9","fasta_url":"https://rest.uniprot.org/uniprotkb/Q70EK9.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q70EK9/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q70EK9"}},"corpus_meta":[{"pmid":"27083998","id":"PMC_27083998","title":"USP51 deubiquitylates H2AK13,15ub and regulates DNA damage response.","date":"2016","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/27083998","citation_count":80,"is_preprint":false},{"pmid":"29119051","id":"PMC_29119051","title":"USP51 promotes deubiquitination and stabilization of ZEB1.","date":"2017","source":"American journal of cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/29119051","citation_count":70,"is_preprint":false},{"pmid":"32296027","id":"PMC_32296027","title":"CDK4/6 inhibition blocks cancer metastasis through a USP51-ZEB1-dependent deubiquitination mechanism.","date":"2020","source":"Signal transduction and targeted therapy","url":"https://pubmed.ncbi.nlm.nih.gov/32296027","citation_count":69,"is_preprint":false},{"pmid":"37816999","id":"PMC_37816999","title":"USP51 facilitates colorectal cancer stemness and chemoresistance by forming a positive feed-forward loop with HIF1A.","date":"2023","source":"Cell death and differentiation","url":"https://pubmed.ncbi.nlm.nih.gov/37816999","citation_count":41,"is_preprint":false},{"pmid":"37386737","id":"PMC_37386737","title":"USP51/PD-L1/ITGB1-deployed juxtacrine interaction plays a cell-intrinsic role in promoting chemoresistant phenotypes in non-small cell lung cancer.","date":"2023","source":"Cancer communications (London, England)","url":"https://pubmed.ncbi.nlm.nih.gov/37386737","citation_count":37,"is_preprint":false},{"pmid":"30192049","id":"PMC_30192049","title":"Examination of the Deubiquitylation Site Selectivity of USP51 by Using Chemically Synthesized Ubiquitylated Histones.","date":"2018","source":"Chembiochem : a European journal of chemical biology","url":"https://pubmed.ncbi.nlm.nih.gov/30192049","citation_count":31,"is_preprint":false},{"pmid":"36603607","id":"PMC_36603607","title":"USP51/ZEB1/ACTA2 axis promotes mesenchymal phenotype in gastric cancer and is associated with low cohesion characteristics.","date":"2023","source":"Pharmacological research","url":"https://pubmed.ncbi.nlm.nih.gov/36603607","citation_count":26,"is_preprint":false},{"pmid":"31217854","id":"PMC_31217854","title":"FAT4-USP51 complex regulates the proliferation and invasion of endometrial cancer via Hippo pathway.","date":"2019","source":"American journal of translational research","url":"https://pubmed.ncbi.nlm.nih.gov/31217854","citation_count":20,"is_preprint":false},{"pmid":"37422632","id":"PMC_37422632","title":"USP51 promotes non-small cell lung carcinoma cell stemness by deubiquitinating TWIST1.","date":"2023","source":"Journal of translational medicine","url":"https://pubmed.ncbi.nlm.nih.gov/37422632","citation_count":16,"is_preprint":false},{"pmid":"39151312","id":"PMC_39151312","title":"Berbamine promotes ferroptosis of esophageal squamous cell carcinoma by facilitating USP51-mediated GPX4 ubiquitination and degradation.","date":"2024","source":"Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie","url":"https://pubmed.ncbi.nlm.nih.gov/39151312","citation_count":16,"is_preprint":false},{"pmid":"31817696","id":"PMC_31817696","title":"Hispidulin Enhances TRAIL-Mediated Apoptosis via CaMKK/AMPK/USP51 Axis-Mediated Bim Stabilization.","date":"2019","source":"Cancers","url":"https://pubmed.ncbi.nlm.nih.gov/31817696","citation_count":16,"is_preprint":false},{"pmid":"35058607","id":"PMC_35058607","title":"CDK4/6-USP51 axis regulates lung adenocarcinoma metastasis through ZEB1.","date":"2022","source":"Cancer gene therapy","url":"https://pubmed.ncbi.nlm.nih.gov/35058607","citation_count":15,"is_preprint":false},{"pmid":"35856403","id":"PMC_35856403","title":"The role of USP51 in attenuating chemosensitivity of lung cancer cells to cisplatin by regulating DNA damage response.","date":"2022","source":"Biotechnology and applied biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/35856403","citation_count":14,"is_preprint":false},{"pmid":"40487653","id":"PMC_40487653","title":"USP51/GRP78/ABCB1 axis confers chemoresistance through decreasing doxorubicin accumulation in triple-negative breast cancer cells.","date":"2025","source":"Acta pharmaceutica Sinica. B","url":"https://pubmed.ncbi.nlm.nih.gov/40487653","citation_count":4,"is_preprint":false},{"pmid":"40877392","id":"PMC_40877392","title":"Regulation of divergent epithelial-to-mesenchymal transition responses via the CDK4/6-USP51 pathway through ZEB1 protein stabilization.","date":"2025","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/40877392","citation_count":2,"is_preprint":false},{"pmid":"41475333","id":"PMC_41475333","title":"NEK8 stabilization via USP51-mediated deubiquitination promotes colorectal cancer progression.","date":"2025","source":"Pathology, research and practice","url":"https://pubmed.ncbi.nlm.nih.gov/41475333","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10247,"output_tokens":3779,"usd":0.043713,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":11346,"output_tokens":4130,"usd":0.07999,"stage2_stop_reason":"end_turn"},"total_usd":0.123703,"stage1_batch_id":"msgbatch_01UT1AahFPCAyn2uVweS7A9z","stage2_batch_id":"msgbatch_01HuKWtKNT4Pqj1bc8eEP5RV","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2016,\n      \"finding\": \"USP51 directly binds H2A-H2B and deubiquitylates histone H2A at K13 and K15 (H2AK13,15ub) in vitro. In cells, USP51 is recruited to chromatin after DNA damage and regulates dynamic assembly/disassembly of 53BP1 and BRCA1 foci. USP51 overexpression suppresses 53BP1 and BRCA1 but not RNF168 foci, placing USP51 downstream of RNF168 in the DNA damage response pathway.\",\n      \"method\": \"In vitro deubiquitylation assay, direct binding assay (H2A-H2B pulldown), chromatin fractionation, epistasis via foci analysis (RNF168/53BP1/BRCA1), USP51 depletion/overexpression\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — in vitro biochemical reconstitution of DUB activity, direct binding assay, genetic epistasis by foci analysis, replicated across multiple orthogonal methods in one rigorous study\",\n      \"pmids\": [\"27083998\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"USP51 deubiquitylates H2AK13Ub, H2AK15Ub, and H2AK119Ub in vitro on reconstituted nucleosomes without site selectivity (in contrast to in vivo observations). USP51 can also deubiquitylate H2BK120Ub but not H2BK34Ub in vitro. Molecular dynamics simulations suggest steric hindrance of the isopeptide bond affects USP51 catalytic activity on certain sites.\",\n      \"method\": \"Total chemical protein synthesis of ubiquitylated histones, nucleosome reconstitution, in vitro deubiquitylation assay, molecular dynamics simulation\",\n      \"journal\": \"Chembiochem\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with chemically defined substrates and mutagenesis-equivalent site-specific probes, single lab but multiple orthogonal biochemical methods\",\n      \"pmids\": [\"30192049\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"USP51 binds, deubiquitinates, and stabilizes the transcription factor ZEB1, identified by screening a human deubiquitinase library. Depletion of USP51 in mesenchymal-like breast cancer cells leads to downregulation of ZEB1 protein, upregulation of E-cadherin, downregulation of mesenchymal markers, and inhibition of cell invasion.\",\n      \"method\": \"Deubiquitinase library screen, co-immunoprecipitation, ubiquitination assay, USP51 depletion/overexpression, cell invasion assay\",\n      \"journal\": \"American journal of cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — Co-IP and deubiquitination assay confirmed in cells, multiple functional readouts, single lab\",\n      \"pmids\": [\"29119051\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"CDK4/6 phosphorylates and activates USP51, which is necessary for USP51 to deubiquitinate and stabilize ZEB1, thereby promoting breast cancer metastasis. This establishes a CDK4/6-USP51-ZEB1 signaling axis.\",\n      \"method\": \"In vitro phosphorylation assay, co-immunoprecipitation, ubiquitination assay, USP51 depletion/overexpression, in vivo tumor metastasis models, tissue correlation analysis\",\n      \"journal\": \"Signal transduction and targeted therapy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — biochemical phosphorylation and deubiquitination assays combined with in vivo functional data, single lab\",\n      \"pmids\": [\"32296027\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"USP51 directly binds Elongin C (ELOC) and forms a functional complex with the VHL E3 ligase (USP51/VHL/CUL2/ELOB/ELOC/RBX1). Within this complex, USP51 deubiquitinates HIF1A and stabilizes it, activating hypoxia-induced gene transcription. SUMOylation of ELOC at K32 inhibits its binding to USP51; SENP1-mediated deSUMOylation of ELOC promotes USP51-ELOC binding and facilitates HIF1A stabilization.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination/deubiquitination assay, SUMOylation assay, SENP1 manipulation, USP51 depletion/overexpression, functional readouts (proliferation, migration, stemness)\",\n      \"journal\": \"Cell death and differentiation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — multiple Co-IP and biochemical assays in single lab, multiple orthogonal methods but no in vitro reconstitution\",\n      \"pmids\": [\"37816999\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"USP51 deubiquitinates and stabilizes PD-L1 protein in NSCLC cells. PD-L1, stabilized by USP51, directly binds ITGB1 at the cell membrane and activates NF-κB signaling to promote chemoresistance.\",\n      \"method\": \"Co-immunoprecipitation, pulldown assay, protein deubiquitination assay, Ub-AMC-based DUB activity assay, cellular thermal shift assay, surface plasmon resonance (SPR), USP51 depletion/overexpression\",\n      \"journal\": \"Cancer communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — biochemical DUB activity and SPR confirm USP51-PD-L1 interaction and deubiquitination, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"37386737\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"USP51 directly binds FAT4 (confirmed by co-immunoprecipitation). USP51 stabilizes FAT4 protein; ablation of USP51 decreases FAT4 protein levels while overexpression increases them. USP51-FAT4 interaction is required for FAT4's tumor-suppressive function via the Hippo pathway in endometrial cancer cells.\",\n      \"method\": \"Co-immunoprecipitation, USP51 shRNA knockdown/overexpression, FAT4 protein level measurement, Hippo pathway activity assay (LATS1/2 phosphorylation, YAP localization)\",\n      \"journal\": \"American journal of translational research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — Co-IP confirmed direct binding, functional rescue experiments, single lab\",\n      \"pmids\": [\"31217854\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"USP51 deubiquitinates TWIST1, attenuating its polyubiquitination and stabilizing the TWIST1 protein, thereby maintaining cancer stem cell properties in NSCLC cells. Re-expression of TWIST1 rescued the inhibitory effects of USP51 knockdown on cell stemness.\",\n      \"method\": \"Cycloheximide chase assay, polyubiquitination assay, USP51 overexpression/knockdown, TWIST1 rescue experiment, colony/sphere formation assays, in vivo xenograft\",\n      \"journal\": \"Journal of translational medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — ubiquitination assay and protein stability assay with functional rescue, single lab\",\n      \"pmids\": [\"37422632\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"USP51 deubiquitinates GPX4, stabilizing it and protecting it from proteasomal degradation. Reduction of USP51 by berbamine leads to increased ubiquitination and degradation of GPX4, triggering ferroptosis in esophageal squamous cell carcinoma cells. USP51 overexpression rescues GPX4 from BBM-induced downregulation.\",\n      \"method\": \"Ubiquitination/deubiquitination assay, USP51 overexpression rescue experiment, cell death assay (ferroptosis markers: Fe, ROS, MDA), in vivo xenograft\",\n      \"journal\": \"Biomedicine & pharmacotherapy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — biochemical ubiquitination assay with functional rescue, single lab\",\n      \"pmids\": [\"39151312\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"AMPK activation by hispidulin upregulates USP51 expression, which in turn stabilizes the pro-apoptotic protein Bim at the post-translational level, sensitizing cancer cells to TRAIL-induced apoptosis. Depletion of Bim blocks this effect.\",\n      \"method\": \"USP51 expression analysis, siRNA depletion of Bim and USP51, AMPK activation, apoptosis assay, in vivo xenograft\",\n      \"journal\": \"Cancers\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — indirect evidence linking AMPK-USP51-Bim without direct biochemical demonstration of USP51-Bim deubiquitination, single lab\",\n      \"pmids\": [\"31817696\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"CDK4/6 phosphorylates and activates USP51 in lung adenocarcinoma, leading to deubiquitination and stabilization of ZEB1, thereby promoting tumor metastasis. p-USP51 and ZEB1 levels are positively correlated in human lung adenocarcinoma samples.\",\n      \"method\": \"Phosphorylation assay, co-immunoprecipitation, ubiquitination assay, USP51 depletion/overexpression, in vitro invasion assays, clinical tissue correlation\",\n      \"journal\": \"Cancer gene therapy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — replicates CDK4/6-USP51-ZEB1 mechanism in a distinct cancer model with biochemical and functional validation, single lab\",\n      \"pmids\": [\"35058607\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"USP51 deubiquitinates and stabilizes GRP78. This stabilization increases GRP78 cell-surface localization, which enhances ABCB1 efflux pump activity and reduces doxorubicin accumulation in triple-negative breast cancer cells, conferring chemoresistance.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination/deubiquitination assay, USP51 overexpression, cell surface GRP78 localization assay, doxorubicin accumulation assay, in vivo xenograft\",\n      \"journal\": \"Acta pharmaceutica Sinica B\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — biochemical deubiquitination and functional localization assays, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"40487653\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"USP51 directly interacts with NEK8, reduces its ubiquitination level, and stabilizes NEK8 protein. NEK8 stabilization by USP51 promotes colorectal cancer cell proliferation and invasion through activation of the WNT/β-catenin pathway.\",\n      \"method\": \"Co-immunoprecipitation, co-immunofluorescence, ubiquitination assay, functional rescue experiments, USP51/NEK8 knockdown, WNT/β-catenin pathway readout (β-catenin protein levels), subcutaneous tumor formation\",\n      \"journal\": \"Pathology, research and practice\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — Co-IP, co-IF, ubiquitination assay, and functional rescue experiments, single lab\",\n      \"pmids\": [\"41475333\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"CDK4/6 kinase activity and USP51 cooperate to enhance ZEB1 protein stability via deubiquitination, promoting cell migration in a mesenchymal breast cancer model. Suppression of USP51 or CDK4/6 attenuates ZEB1 stability and cell migration.\",\n      \"method\": \"Ubiquitin-proteasome pathway analysis, CDK4/6 and USP51 inhibition/knockdown, ZEB1 protein stability assay, cell migration assay\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — replicates CDK4/6-USP51-ZEB1 axis but uses less rigorous biochemical methods; single lab, limited new mechanistic detail beyond prior studies\",\n      \"pmids\": [\"40877392\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"USP51 is a deubiquitinase (DUB) that removes ubiquitin from multiple substrates including histone H2A at K13/K15 (acting downstream of RNF168 in the DNA damage response), ZEB1 (activated by CDK4/6-mediated phosphorylation of USP51 to promote EMT and metastasis), HIF1A (within a VHL/CUL2 complex, regulated by SENP1-mediated deSUMOylation of ELOC), PD-L1, GPX4, GRP78, TWIST1, FAT4, NEK8, and Bim, thereby controlling protein stability and a broad set of cancer-related cellular processes including DNA repair, EMT, stemness, and chemoresistance.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"USP51 is a deubiquitinase that controls protein stability across DNA repair, transcription, and a broad spectrum of cancer-associated processes by removing ubiquitin from chromatin and multiple non-histone substrates [#0, #2]. In the DNA damage response, USP51 directly binds the H2A-H2B dimer and deubiquitylates histone H2A at K13/K15, acting downstream of RNF168 to regulate the dynamic assembly and disassembly of 53BP1 and BRCA1 foci [#0]; biochemically it processes H2AK13ub, H2AK15ub, H2AK119ub, and H2BK120ub on reconstituted nucleosomes, with site discrimination governed by steric accessibility of the isopeptide bond [#1]. Beyond chromatin, USP51 functions as a stabilizing DUB for an array of substrates: it deubiquitinates and stabilizes the EMT transcription factor ZEB1, an activity that requires CDK4/6-mediated phosphorylation of USP51 and drives breast and lung cancer metastasis through a CDK4/6-USP51-ZEB1 axis [#2, #3, #10]. USP51 also assembles into the VHL/CUL2/ELOB/ELOC/RBX1 complex via direct binding to Elongin C, where it deubiquitinates and stabilizes HIF1A to activate hypoxia-induced transcription, a step gated by SENP1-mediated deSUMOylation of ELOC [#4]. Through stabilization of additional substrates—PD-L1, TWIST1, GPX4, GRP78, FAT4, and NEK8—USP51 promotes chemoresistance, cancer stemness, ferroptosis resistance, and Hippo and WNT/\\u03b2-catenin pathway modulation [#5, #6, #7, #8, #11, #12].\",\n  \"teleology\": [\n    {\n      \"year\": 2016,\n      \"claim\": \"Established USP51 as a chromatin-acting deubiquitinase that targets histone H2A and modulates DNA damage signaling, defining its first molecular function and pathway position.\",\n      \"evidence\": \"In vitro deubiquitylation and H2A-H2B binding assays with chromatin fractionation and 53BP1/BRCA1/RNF168 foci epistasis after DNA damage\",\n      \"pmids\": [\"27083998\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Site selectivity for H2AK13/K15 in cells not explained biochemically\", \"Recruitment mechanism to damaged chromatin unresolved\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Defined the intrinsic substrate range of USP51 on defined nucleosomal substrates, showing the in vivo site selectivity is not an intrinsic enzymatic property but is set by structural accessibility.\",\n      \"evidence\": \"Total chemical synthesis of ubiquitylated histones, nucleosome reconstitution, in vitro DUB assays, and molecular dynamics simulation\",\n      \"pmids\": [\"30192049\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"What confers in-cell site selectivity (cofactors, recruitment) remains unknown\", \"No structural model of the USP51-nucleosome complex\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Extended USP51 function beyond chromatin by identifying ZEB1 as a stabilized substrate, linking the DUB to EMT control in breast cancer.\",\n      \"evidence\": \"Deubiquitinase library screen, Co-IP, ubiquitination assays, and cell invasion assays in mesenchymal breast cancer cells\",\n      \"pmids\": [\"29119051\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct deubiquitination not reconstituted in vitro\", \"Ubiquitin chain type on ZEB1 not defined\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Showed that USP51 activity toward ZEB1 is switched on by CDK4/6 phosphorylation, establishing an upstream regulatory kinase axis driving metastasis.\",\n      \"evidence\": \"In vitro phosphorylation, Co-IP, ubiquitination assays, in vivo metastasis models, and tissue correlation\",\n      \"pmids\": [\"32296027\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Phosphosite(s) on USP51 not mapped to catalytic mechanism\", \"Single lab\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Replicated the CDK4/6-USP51-ZEB1 axis in lung adenocarcinoma, generalizing the mechanism across cancer types.\",\n      \"evidence\": \"Phosphorylation and ubiquitination assays, Co-IP, invasion assays, and clinical tissue correlation\",\n      \"pmids\": [\"35058607\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanistic detail beyond prior breast cancer work limited\", \"Single lab\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Placed USP51 within a tumor-suppressive context by stabilizing FAT4 to modulate Hippo signaling, indicating context-dependent functional outputs.\",\n      \"evidence\": \"Co-IP, USP51 knockdown/overexpression, FAT4 protein measurement, and Hippo pathway readouts in endometrial cancer cells\",\n      \"pmids\": [\"31217854\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct deubiquitination of FAT4 not biochemically demonstrated\", \"Reconciliation with oncogenic roles elsewhere not addressed\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Linked AMPK signaling to USP51-dependent stabilization of pro-apoptotic Bim, implicating USP51 in apoptosis sensitization.\",\n      \"evidence\": \"siRNA depletion of USP51 and Bim, AMPK activation, apoptosis assays, and xenograft\",\n      \"pmids\": [\"31817696\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No direct biochemical demonstration of USP51-Bim deubiquitination\", \"Causal link is indirect\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Defined USP51 as a functional subunit of the VHL/CUL2 complex that deubiquitinates HIF1A, with its incorporation controlled by SENP1-driven deSUMOylation of ELOC.\",\n      \"evidence\": \"Co-IP, ubiquitination/deubiquitination and SUMOylation assays, SENP1 manipulation, and functional readouts\",\n      \"pmids\": [\"37816999\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No in vitro reconstitution of the USP51-VHL complex\", \"Stoichiometry within the CUL2 ligase unresolved\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identified PD-L1 as a USP51 substrate, connecting the DUB to immune-checkpoint protein stability and NF-\\u03baB-driven chemoresistance.\",\n      \"evidence\": \"Co-IP, pulldown, Ub-AMC DUB activity assay, cellular thermal shift, and SPR in NSCLC cells\",\n      \"pmids\": [\"37386737\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vivo relevance of PD-L1-ITGB1 axis incompletely defined\", \"Single lab\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Showed USP51 stabilizes TWIST1 to maintain cancer stem cell properties, expanding its role in stemness control.\",\n      \"evidence\": \"Cycloheximide chase, polyubiquitination assays, TWIST1 rescue, sphere formation, and xenograft in NSCLC\",\n      \"pmids\": [\"37422632\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct in vitro deubiquitination not shown\", \"Ubiquitin linkage type unspecified\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Connected USP51 to ferroptosis regulation by stabilizing GPX4, defining a redox-survival function exploitable by berbamine.\",\n      \"evidence\": \"Ubiquitination/deubiquitination and rescue assays, ferroptosis markers, and xenograft in esophageal squamous cell carcinoma\",\n      \"pmids\": [\"39151312\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether USP51 directly binds GPX4 not fully established\", \"Single lab\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Demonstrated USP51 stabilization of GRP78 promotes cell-surface GRP78 and ABCB1-mediated drug efflux, providing a mechanism for chemoresistance.\",\n      \"evidence\": \"Co-IP, ubiquitination/deubiquitination assays, surface GRP78 localization, doxorubicin accumulation, and xenograft in TNBC\",\n      \"pmids\": [\"40487653\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism coupling GRP78 deubiquitination to surface trafficking unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Added NEK8 as a USP51 substrate driving WNT/\\u03b2-catenin-dependent colorectal cancer proliferation, broadening the oncogenic substrate set.\",\n      \"evidence\": \"Co-IP, co-IF, ubiquitination assays, functional rescue, and subcutaneous tumor formation\",\n      \"pmids\": [\"41475333\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct in vitro deubiquitination not reconstituted\", \"Single lab\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How USP51 substrate selection and site specificity are governed in cells across such a broad substrate repertoire, and how its phosphorylation and complex incorporation are coordinated, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of USP51 bound to any substrate\", \"No unifying determinant of in-cell substrate/site selectivity\", \"Reconciliation of tumor-suppressive (FAT4, Bim) versus oncogenic substrate roles unaddressed\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 1, 2, 4, 5, 7, 8, 11, 12]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [0, 1, 5]},\n      {\"term_id\": \"GO:0042393\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005694\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 12]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [2, 4, 5, 7, 8, 11, 12]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [4, 6, 12]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [3, 5, 10, 11]}\n    ],\n    \"complexes\": [\"VHL/CUL2/ELOB/ELOC/RBX1 ubiquitin ligase complex\"],\n    \"partners\": [\"ZEB1\", \"HIF1A\", \"ELOC\", \"PD-L1\", \"FAT4\", \"TWIST1\", \"GPX4\", \"NEK8\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}