{"gene":"USP9X","run_date":"2026-06-11T09:02:06","timeline":{"discoveries":[{"year":2009,"finding":"USP9X binds MCL1 and removes Lys48-linked polyubiquitin chains from MCL1, preventing its proteasomal degradation and thereby stabilizing MCL1 to promote cell survival. Knockdown of USP9X increases MCL1 polyubiquitination and enhances MCL1 turnover.","method":"Co-immunoprecipitation, ubiquitination assays, RNAi knockdown, cell survival assays","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal binding demonstrated, ubiquitin chain topology defined, replicated across multiple labs and cancer types","pmids":["20023629"],"is_preprint":false},{"year":2008,"finding":"USP9X interacts with and deubiquitinates AMPK-related kinases NUAK1 and MARK4, removing atypical Lys29/Lys33-linked polyubiquitin chains. Non-USP9X-binding mutants of NUAK1 and MARK4 are hyper-ubiquitinated and lack LKB1-mediated T-loop phosphorylation, suggesting polyubiquitination inhibits these kinases.","method":"Co-immunoprecipitation, in vitro deubiquitinase assay, ubiquitin chain topology analysis, mutagenesis, overexpression/knockdown","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro deubiquitinase assay with mutagenesis, chain topology determined, single lab with multiple orthogonal methods","pmids":["18254724"],"is_preprint":false},{"year":2010,"finding":"USP9X mediates selective autophagy (zymophagy) of activated zymogen granules in pancreatic acinar cells by interacting with the autophagy protein VMP1 and the ubiquitin-binding protein p62, forming a VMP1-USP9X-p62 pathway required for selective autophagosome formation.","method":"Co-immunoprecipitation, cellular/biochemical characterization, genetically engineered mice, cultured acinar cells","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP of VMP1-USP9X interaction, loss-of-function in cells and mice, single lab","pmids":["21173155"],"is_preprint":false},{"year":2011,"finding":"USP9X interacts with and deubiquitinates α-synuclein, removing monoubiquitin added by SIAH. Deubiquitinated α-synuclein is preferentially degraded by autophagy, while monoubiquitinated α-synuclein is preferentially degraded by the proteasome. USP9X knockdown promotes accumulation of monoubiquitinated α-synuclein and toxic inclusions.","method":"Co-immunoprecipitation, deubiquitinase activity assay, RNAi knockdown, USP9X overexpression, cell fractionation","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro/in vivo deubiquitination demonstrated, pathway placement (autophagy vs. proteasome) defined by gain/loss-of-function, multiple orthogonal methods","pmids":["22065755"],"is_preprint":false},{"year":2009,"finding":"USP9X binds ASK1 via a ubiquitin-like GG sequence (LRLRGG) in ASK1's C-terminus and stabilizes activated ASK1 by preventing its ubiquitin-dependent degradation. USP9X-deficient cells show reduced oxidative stress-induced JNK activation and cell death.","method":"Co-immunoprecipitation, binding domain mutagenesis, USP9X-deficient cells, JNK activation assay, cell death assay","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 / Moderate — interaction domain mapped by mutagenesis, loss-of-function phenotype defined, single lab with multiple orthogonal methods","pmids":["20005844"],"is_preprint":false},{"year":2006,"finding":"FAM/USP9X binds the ITCH ubiquitin ligase via ITCH's WW domains, deubiquitinates auto-ubiquitinated ITCH, and protects it from proteasomal degradation. RNAi depletion of FAM/USP9X reduces endogenous ITCH levels, rescued by proteasome inhibitor.","method":"GST pulldown, co-immunoprecipitation, co-localization, RNAi knockdown, overexpression","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — GST pulldown + reciprocal co-IP, RNAi rescue with proteasome inhibitor, replicated concept confirmed by multiple subsequent studies","pmids":["17038327"],"is_preprint":false},{"year":2012,"finding":"FAM/USP9X interacts with the E3 ubiquitin ligase SMURF1 through the second WW domain of SMURF1 and the C-terminus of USP9X. USP9X antagonizes SMURF1 auto-ubiquitination and proteasomal degradation, thereby stabilizing SMURF1. Depletion of USP9X reduces SMURF1 levels and impairs cell migration in MDA-MB-231 breast cancer cells.","method":"Quantitative mass spectrometry, co-immunoprecipitation, domain mapping, deubiquitination assay, RNAi knockdown, cell migration assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — domain mapping, deubiquitination assay, functional migration phenotype upon knockdown, single lab with multiple orthogonal methods","pmids":["23184937"],"is_preprint":false},{"year":2018,"finding":"USP9X interacts with and deubiquitinates FBW7, preventing its ubiquitin-dependent degradation. Usp9x deletion in mouse gut causes Fbw7 destabilization, reduces secretory cell differentiation, increases progenitor proliferation, and increases tumor burden in colitis-associated cancer. c-Myc heterozygosity rescues the proliferation and tumor phenotype, placing USP9X upstream of FBW7-c-Myc.","method":"Proteomics, co-immunoprecipitation, conditional mouse knockout, genetic epistasis (c-Myc heterozygosity), intestinal organoids","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis in vivo, proteomics-identified interaction, conditional KO with defined phenotype, multiple orthogonal methods","pmids":["29346117"],"is_preprint":false},{"year":2019,"finding":"USP9X interacts with, depolyubiquitylates, and stabilizes ALDH1A3 in mesenchymal glioblastoma stem cells (GSCs). Depletion of USP9X downregulates ALDH1A3, reducing self-renewal and tumorigenic capacity of MES GSCs; ectopic ALDH1A3 expression rescues these defects.","method":"Co-immunoprecipitation, deubiquitination assay, RNAi knockdown, rescue experiment, orthotopic xenograft model","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 / Moderate — in vivo deubiquitination, rescue experiment with ALDH1A3, xenograft validation, single lab with multiple orthogonal methods","pmids":["30958800"],"is_preprint":false},{"year":2018,"finding":"USP9X deubiquitinates and stabilizes YAP1 by removing polyubiquitin chains, preventing its proteasomal degradation. Depletion of USP9X increases YAP1 polyubiquitination and turnover, sensitizing breast cancer cells to chemotherapy.","method":"Co-immunoprecipitation, ubiquitination assay, RNAi knockdown, overexpression","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — co-IP and ubiquitination assay, single lab, single paper","pmids":["29449692"],"is_preprint":false},{"year":2021,"finding":"S-nitrosylation of USP9X (by nitric oxide) enables USP9X to deubiquitinate and stabilize MIB1, which activates NOTCH1 signaling. Genetic deletion of Usp9x in mice causes calcific aortic valve disease, and human calcified aortic valves show reduced S-nitrosylation of USP9X.","method":"Unbiased proteomics for S-nitrosylated proteins, co-immunoprecipitation, mouse genetic knockout, single-cell RNA-seq, in vitro deubiquitination assay","journal":"Science advances","confidence":"High","confidence_rationale":"Tier 2 / Moderate — unbiased proteomics, mouse KO phenotype, in vitro deubiquitination, PTM (S-nitrosylation) identified as regulatory switch, multiple orthogonal methods single lab","pmids":["33547080"],"is_preprint":false},{"year":2021,"finding":"USP9X binds and deubiquitinates KDM4C, stabilizing it. Depletion of USP9X reduces KDM4C levels, impairing TGF-β2 transcription (KDM4C reduces H3K9me3 at the TGF-β2 promoter) and reducing radioresistance in lung cancer cells.","method":"Tandem affinity purification, co-immunoprecipitation, deubiquitination assay, RNAi knockdown, chromatin assays, in vitro and in vivo models","journal":"Cell death and differentiation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — tandem affinity purification, in vitro deubiquitination, functional radioresistance phenotype, single lab","pmids":["33558705"],"is_preprint":false},{"year":2017,"finding":"USP9X physically associates with LATS kinase (and to lesser extent WW45, KIBRA, Angiomotin) and deubiquitinates/stabilizes LATS. Knockdown of USP9X downregulates LATS, promotes nuclear translocation of YAP/TAZ, and activates EMT. Deletion of Usp9x in mouse embryonic fibroblasts reduces LATS protein.","method":"Co-immunoprecipitation, gel filtration chromatography, RNAi knockdown, MEF knockout, YAP/TAZ reporter assay, soft agar assay","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal co-IP, gel filtration, MEF KO corroborates cell line data, multiple labs confirming Hippo pathway regulation by USP9X","pmids":["28720576"],"is_preprint":false},{"year":2017,"finding":"USP9X (deubiquitylase USP9X) deubiquitinates and stabilizes LATS2, preventing its proteasomal degradation. USP9X ablation reduces LATS2 levels, activates YAP, and enhances oncogenic potential in pancreatic cancer cells. Identified by tandem affinity purification.","method":"Tandem affinity purification, co-immunoprecipitation, deubiquitination assay, RNAi knockdown, YAP reporter assay","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — TAP identification, deubiquitination assay, functional YAP activation phenotype, single lab","pmids":["29183995"],"is_preprint":false},{"year":2016,"finding":"USP9X stabilizes XIAP by deubiquitylation in mitosis, conferring resistance to mitotic spindle poisons. USP9X knockdown reduces XIAP, sensitizes cells to spindle poisons, and delays lymphoma development in a murine Eμ-Myc model.","method":"Co-immunoprecipitation, deubiquitination assay, RNAi knockdown, murine lymphoma model, patient sample correlation","journal":"EMBO molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — deubiquitination assay, in vivo mouse model, functional chemoresistance phenotype, single lab","pmids":["27317434"],"is_preprint":false},{"year":2011,"finding":"WP1130 directly inhibits USP9X deubiquitinase activity in CML cells, leading to downregulation of Mcl-1 and inducing apoptosis. Bcr-Abl undergoes K63-linked ubiquitin modification and aggresomal sequestration upon USP9X inhibition, blocking its signaling.","method":"Deubiquitinase activity assay, ubiquitin chain-type analysis, aggresome detection, apoptosis assays","journal":"Blood","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct enzymatic inhibition assay, aggresome localization, single lab with multiple readouts","pmids":["21248063"],"is_preprint":false},{"year":2014,"finding":"USP9X loss-of-function (Usp9x knockout mice) causes reduction in axonal growth and neuronal cell migration. Wild-type human USP9X rescues these defects, but three ID-associated missense/truncating variants fail to rescue axonal growth and show reduced localization in axonal growth cones.","method":"Usp9x knockout mouse, overexpression rescue with human USP9X variants, axon length measurement, neuronal migration assay, proteomics of Usp9x-null neurons","journal":"American journal of human genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — knockout mouse, multiple variant rescue experiments, proteomics identifying cytoskeletal disruption, multiple orthogonal methods","pmids":["24607389"],"is_preprint":false},{"year":2013,"finding":"Conditional deletion of Usp9x from neural progenitors disrupts cellular organization of ventricular/subventricular zones and cortical plate, dramatically reduces axonal length (in vivo and in vitro), partly through failure of TGF-β signaling. Dorsal telencephalon-specific deletion results in corpus callosum reduction and hippocampal size decrease.","method":"Conditional Usp9x knockout (Nestin-cre and Emx1-cre), in vivo and in vitro axon length measurement, TGF-β signaling analysis","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 2 / Strong — two conditional KO models with distinct phenotypes, in vivo and in vitro axonogenesis assays, TGF-β pathway linkage","pmids":["23861879"],"is_preprint":false},{"year":2015,"finding":"USP9X controls EGFR endocytosis and trafficking by deubiquitinating Eps15, an endocytic adaptor protein. USP9X depletion affects EGFR internalization; Eps15 monoubiquitination is essential for EGFR internalization.","method":"Systematic RNAi screen, co-immunoprecipitation, mapping of Eps15 ubiquitination sites, EGFR trafficking assays","journal":"Current biology : CB","confidence":"High","confidence_rationale":"Tier 2 / Moderate — systematic RNAi screen + follow-up mechanistic studies, Eps15 ubiquitination sites mapped, functional EGFR trafficking phenotype","pmids":["26748853"],"is_preprint":false},{"year":2010,"finding":"USP9X deubiquitinates EFA6 (exchange factor for Arf6) at newly forming epithelial cell contacts, transiently protecting it from proteasomal degradation and enabling tight junction biogenesis. Knockdown of either USP9X or EFA6 impairs tight junction formation; EFA6 overexpression rescues TJ biogenesis in USP9X-knockdown cells.","method":"Co-localization, co-immunoprecipitation, deubiquitination assay, RNAi knockdown, rescue experiment","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Moderate — deubiquitination assay, co-localization at primordial junctions, epistasis rescue experiment, single lab multiple methods","pmids":["20339350"],"is_preprint":false},{"year":2008,"finding":"MARCH7 (E3 ubiquitin ligase) undergoes autoubiquitylation and associates with USP9X in the cytosol (and USP7 in the nucleus). USP9X stabilizes MARCH7 by deubiquitylation in a compartment-specific manner, and RNAi depletion of USP9X reduces MARCH7 levels.","method":"Co-immunoprecipitation, RNAi knockdown, overexpression, subcellular fractionation","journal":"Traffic (Copenhagen, Denmark)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP, RNAi depletion with rescue, subcellular compartment specificity defined, single lab","pmids":["18410486"],"is_preprint":false},{"year":2013,"finding":"USP9X interacts with Bcl10 of the CBM (Carma1-Bcl10-Malt1) complex and removes TCR-induced ubiquitin chains from Bcl10, facilitating association of Carma1 with Bcl10-Malt1 and enabling NF-κB activation. Knockdown of USP9X attenuates T-cell proliferation and NF-κB activation upon TCR signaling.","method":"Co-immunoprecipitation, RNAi knockdown in human T-cell line and mouse primary T cells, adoptive transfer immunization","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — interaction with Bcl10 demonstrated, ubiquitin removal shown, in vivo adoptive transfer confirms pathway role, multiple experimental systems","pmids":["23690623"],"is_preprint":false},{"year":2016,"finding":"USP9X removes inhibitory monoubiquitination from ZAP70 in T lymphocytes upon TCR-dependent phosphorylation, which enhances USP9X catalytic activity. Absence of USP9X increases ZAP70 localization to early endosomes. In B lymphocytes, USP9X is required for BCR-dependent PKCβ kinase activity and CARMA1/Bcl-10/MALT-1 complex formation.","method":"Usp9X knockout mouse, co-immunoprecipitation, ubiquitination assay, endosome localization, kinase activity assay","journal":"Journal of immunology (Baltimore, Md. : 1950)","confidence":"High","confidence_rationale":"Tier 2 / Strong — knockout mouse, mechanistic detail of TCR-dependent phosphorylation activating USP9X, substrate (ZAP70) ubiquitination and endosomal sorting defined","pmids":["26936881"],"is_preprint":false},{"year":2016,"finding":"USP9X deubiquitylates Angiomotin at lysine 496, stabilizing it and reducing YAP/TAZ activity as part of Hippo pathway regulation.","method":"Co-immunoprecipitation, deubiquitination assay, identification of specific ubiquitination site (K496), RNAi knockdown","journal":"Cell discovery","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — site-specific deubiquitination demonstrated, functional YAP/TAZ readout, single lab","pmids":["27462448"],"is_preprint":false},{"year":2017,"finding":"USP9X is physically associated with centriolar satellite protein CEP131 and stabilizes it through its deubiquitinase activity. USP9X is an integral component of the centrosome required for centrosome biogenesis; loss-of-function impairs centrosome duplication.","method":"Co-immunoprecipitation, deubiquitinase activity assay, centrosome localization by microscopy, loss-of-function centrosome duplication assay","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Moderate — co-IP, deubiquitinase activity assay, centrosome functional assay, single lab multiple methods","pmids":["28361952"],"is_preprint":false},{"year":2017,"finding":"USP9X is physically associated and spatially co-localized with centrosomal proteins PCM1 and CEP55, promoting their stabilization through its catalytic activity. USP9X centrosome localization depends on PCM1 and CEP55.","method":"Tandem mass tag labeling proteomics, co-immunoprecipitation, co-localization microscopy, deubiquitinase activity assay, RNAi knockdown","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — quantitative proteomics, co-IP, functional centrosome localization dependency, single lab","pmids":["28620049"],"is_preprint":false},{"year":2019,"finding":"USP9X interacts with and deubiquitinates ankyrin-G (ANK3); USP9X phosphorylation enhances their interaction and decreases ankyrin-G polyubiquitination, stabilizing ankyrin-G to maintain dendritic spine development. In forebrain-specific Usp9X knockout mice, ankyrin-G and multiple ANKRD-containing proteins are transiently reduced at 2 weeks; reduced cortical spine density persists into adulthood.","method":"Co-immunoprecipitation, ubiquitination assay, forebrain-specific conditional KO, dendritic spine density measurement, phosphorylation analysis","journal":"Neuron","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional KO mouse, phospho-regulation of interaction identified, ubiquitination and spine density phenotype, multiple orthogonal methods","pmids":["31813652"],"is_preprint":false},{"year":2019,"finding":"USP9X deubiquitylates DVL2 (Dishevelled 2) by removing ubiquitin to promote canonical WNT activation; increased DVL2 ubiquitylation (by WWP1 E3 ligase) is associated with DVL2 localization to actin-rich projections and activation of the WNT-PCP pathway. A WWP1-USP9X ubiquitin rheostat on DVL2 specifies pathway choice.","method":"Co-immunoprecipitation, deubiquitination assay, WNT reporter assays, PCP pathway assays, RNAi knockdown","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Moderate — deubiquitination assay, pathway specification by ubiquitin state, interaction with E3 ligase WWP1 defined, multiple functional assays","pmids":["31340145"],"is_preprint":false},{"year":2012,"finding":"USP9X co-immunoprecipitates with mTOR along with Raptor and Rictor, components of mTORC1 and mTORC2. Knockdown of USP9X increases mTORC1 activity upon growth factor stimulation and increases mTORC2 activity upon differentiation initiation, accelerating C2C12 myoblast differentiation.","method":"Co-immunoprecipitation, RNAi knockdown, mTOR kinase activity assay, myoblast differentiation assay","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-IP of USP9X with both mTOR complexes, functional differentiation phenotype, but deubiquitination substrate not identified in this study","pmids":["22544753"],"is_preprint":false},{"year":2017,"finding":"USP9X deubiquitylating activity stabilizes RAPTOR protein (mTORC1 scaffold). RAPTOR physically associates with USP9X in embryonic brains; RAPTOR protein level is directly proportional to USP9X in both gain- and loss-of-function experiments; USP9X deubiquitylating activity opposes proteasomal degradation of RAPTOR. Loss of Usp9x causes reduced mTORC1 signaling and neural progenitor arrest in G0.","method":"Co-immunoprecipitation from embryonic brain, gain/loss-of-function in cultured cells and neurospheres, mTORC1 signaling assay, EdU proliferation assay","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP from embryonic brain, proportionality in both gain/loss-of-function, functional mTORC1 and proliferation phenotype, single lab","pmids":["28341829"],"is_preprint":false},{"year":2016,"finding":"USP9X interacts with and deubiquitinates CLASPIN in an S-phase-specific manner, stabilizing it during DNA replication. USP9X depletion impairs DNA replication fork progression (similar to CLASPIN depletion), causes excessive endogenous DNA damage, and compromises CHK1 activation in response to replication stress. Restoration of CLASPIN in USP9X-depleted cells partially suppresses DNA damage accumulation.","method":"Quantitative proteomics, co-immunoprecipitation, RNAi knockdown, DNA fiber assay, CHK1 activation assay, rescue experiment","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 2 / Moderate — proteomics-identified interaction, DNA fiber assay, S-phase-specific regulation, rescue experiment, single lab multiple methods","pmids":["26921344"],"is_preprint":false},{"year":2015,"finding":"USP9X interacts with PRICKLE proteins through their carboxy-termini and deubiquitinates PRICKLE, protecting it from proteasomal degradation. USP9X deficiency in mouse forebrain neurons reduces Prickle2 protein. Genetic reduction of fat facets (USP9X Drosophila orthologue) or treatment with WP1130 suppresses prickle-mediated seizures, placing USP9X in the Prickle seizure-suppression pathway.","method":"Interactome definition, co-immunoprecipitation, deubiquitination assay, forebrain Usp9x conditional KO (Prickle2 levels), Drosophila genetic epistasis, pharmacological WP1130 treatment","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — co-IP + deubiquitination assay + genetic epistasis in Drosophila + mouse KO, multiple model organisms","pmids":["25763846"],"is_preprint":false},{"year":2017,"finding":"Ets-1 transcription factor is deubiquitinated and stabilized by Usp9x, preventing its proteasomal destruction. Usp9x knockdown or inhibition reduces Ets-1 levels, decreasing NRAS expression and suppressing melanoma tumorigenicity.","method":"Co-immunoprecipitation, deubiquitination assay, RNAi knockdown, in vitro and in vivo tumor assays","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP, deubiquitination assay, in vivo tumor data, single lab","pmids":["28198367"],"is_preprint":false},{"year":2016,"finding":"USP9X interacts with TRB3 (pseudokinase) serving as scaffold for USP9X. USP9X deubiquitinates and stabilizes TRB3, and also deubiquitinates and activates Mind Bomb 1 (E3 ligase for JAG1 ubiquitination-mediated endocytosis), thereby activating Notch signaling in the signal-sending cell under cellular stress.","method":"Co-immunoprecipitation, deubiquitination assay, RNAi knockdown, Notch reporter assay","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP and deubiquitination assay for two substrates (TRB3, MIB1), Notch activation readout, single lab","pmids":["27593927"],"is_preprint":false},{"year":2016,"finding":"USP9X binds and deubiquitinates β-catenin, removing Lys48-linked polyubiquitin chains to prevent proteasomal degradation, thereby activating Wnt/β-catenin signaling and promoting glioma cell proliferation.","method":"Co-immunoprecipitation, deubiquitination assay, RNAi knockdown, cell cycle analysis, in vivo xenograft","journal":"Oncotarget","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP, ubiquitin chain-type specificity defined, in vivo xenograft, single lab","pmids":["27783990"],"is_preprint":false},{"year":2019,"finding":"USP9X interacts with BCL9 and removes Lys63-linked polyubiquitin from Lys-212 of BCL9. This deubiquitination facilitates formation of the β-catenin-BCL9-PYGO complex, potentiating transcriptional activation of Wnt/β-catenin target genes.","method":"nano-HPLC-MS/MS, co-immunoprecipitation, deubiquitination assay, ubiquitination site mapping, chromatin immunoprecipitation, Wnt reporter assay","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — MS-identified site-specific deubiquitination, functional Wnt reporter assay, single lab","pmids":["31073027"],"is_preprint":false},{"year":2019,"finding":"USP9X stabilizes PBX1 by attenuating its Lys48-linked polyubiquitination. Co-immunoprecipitation confirmed USP9X-PBX1 interaction. USP9X inhibition induces PBX1 degradation and promotes prostate cancer cell apoptosis.","method":"Co-immunoprecipitation, ubiquitination assay, RNAi knockdown, pharmacological inhibition, apoptosis assay","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP, ubiquitin chain type identified, functional apoptosis phenotype, single lab","pmids":["30718275"],"is_preprint":false},{"year":2017,"finding":"USP9X deubiquitinates and stabilizes TTK (dual specificity protein kinase) via removal of K48-linked ubiquitin chains, through direct interaction. USP9X knockdown reduces TTK protein levels and inhibits NSCLC cell proliferation, migration and tumorigenesis.","method":"Chemical labeling quantitative proteomics, co-immunoprecipitation, deubiquitination assay, ubiquitin chain-type analysis, in vitro and in vivo tumor assays","journal":"Theranostics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — quantitative proteomics substrate identification, K48 chain specificity defined, in vivo xenograft, single lab","pmids":["29721084"],"is_preprint":false},{"year":2020,"finding":"USP9X removes Lys63-linked ubiquitin from RICTOR (mTORC2 scaffold), promoting RICTOR interaction with mTOR and facilitating mTORC2 assembly and activity. This process is stimulated by growth factors.","method":"Co-immunoprecipitation, deubiquitination assay, ubiquitin chain-type analysis, mTORC2 kinase activity assay, human cell lines and mice","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — chain-type specificity defined, validated in both cell lines and mice, mTORC2 assembly directly measured, growth factor regulation shown","pmids":["33378666"],"is_preprint":false},{"year":2020,"finding":"CDC14B phosphatase antagonizes CDK1-mediated phosphorylation of USP9X at serine 2563. Serine 2563 phosphorylation of USP9X is essential for its mitotic activity: phospho-USP9X deubiquitylates and stabilizes WT1 (Wilms' tumor protein) during mitosis, and WT1 acts as a mitotic transcription factor driving CXCL8/IL-8 expression to promote mitotic survival.","method":"Unbiased proteome-wide phosphorylation screening, in vitro phosphorylation assay, co-immunoprecipitation, deubiquitination assay, reporter gene assay","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — proteome-wide unbiased approach, CDK1/CDC14B phosphorylation mechanism defined, deubiquitination assay, transcriptional reporter, multiple orthogonal methods","pmids":["32152317"],"is_preprint":false},{"year":2021,"finding":"USP9X interacts with and stabilizes Makorin 2 and ZNF598 (ubiquitin E3 ligases of the ribosomal quality control pathway). Chemical inhibition or depletion of USP9X reduces levels of Makorins and ZNF598, impairing the ribosomal quality control/stalling pathway.","method":"Small-molecule USP9X inhibitor, proteomics analysis, co-immunoprecipitation, ribosomal stalling assays","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — specific small-molecule inhibitor validated, proteomics, functional ribosomal quality control assay, single lab multiple methods","pmids":["33507233"],"is_preprint":false},{"year":2019,"finding":"USP9X interacts with and deubiquitinates eIF4A1 at Lys-369, preventing its ubiquitin-mediated degradation. USP9X dysfunction increases eIF4A1 ubiquitination and degradation, impairing cap-dependent translation initiation and reducing protein synthesis of pro-oncogenic mRNAs such as c-Myc and XIAP.","method":"Tandem affinity purification, co-immunoprecipitation, ubiquitination site mapping, nascent protein synthesis assay, cap-dependent translation assay","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 2 / Moderate — TAP identification, site-specific ubiquitination mapped, functional translation initiation assay, single lab multiple methods","pmids":["29228324"],"is_preprint":false},{"year":2018,"finding":"USP9X interacts with and deubiquitinates BMAL1 (core circadian clock protein), reducing its ubiquitination, enhancing its stability and protein level, and increasing its transcriptional activity. USP9X knockdown decreases the amplitude of cellular circadian rhythm without affecting period or phase.","method":"Affinity purification, mass spectrometry, co-immunoprecipitation, deubiquitination assay, bioluminescence circadian rhythm measurement","journal":"The Biochemical journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — MS-identified interaction, deubiquitination assay, functional circadian rhythm readout, single lab","pmids":["29626158"],"is_preprint":false},{"year":2017,"finding":"USP9X is methylated at arginine residues, enabling its interaction with the Tudor domain of TDRD3. This interaction is mediated through the Tudor domain of TDRD3 and arginine methylation of USP9X. USP9X depletion increases TDRD3 ubiquitination; TDRD3 is essential for USP9X stress granule localization.","method":"GST pulldown, co-immunoprecipitation, arginine methylation identification, RNAi knockdown, stress granule localization by microscopy, Tdrd3-null MEFs","journal":"Cell discovery","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — arginine methylation as PTM identified, domain-specific interaction mapped, stress granule localization in null MEFs, single lab","pmids":["28101374"],"is_preprint":false},{"year":2017,"finding":"TGF-β activates ERK which phosphorylates SMAD4 at Thr277, facilitating SMAD4-USP9X interaction. USP9X inhibits TIF1γ from binding and monoubiquitinating SMAD4, thereby maintaining SMAD4 nuclear retention and TGF-β/SMAD3-mediated transcription of Twist and Snail, promoting breast cancer metastasis.","method":"Co-immunoprecipitation, phospho-SMAD4 mutant analysis, chromatin retention assay, luciferase reporter, RNAi knockdown","journal":"Cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — phospho-dependent interaction mapped (Thr277), functional TGF-β transcription readout, single lab","pmids":["28115363"],"is_preprint":false},{"year":2005,"finding":"USP9X (DFFRX) interacts with Doublecortin (DCX) through a novel recognition domain outside USP9X's catalytic site. No ubiquitinated forms of DCX were detected, suggesting this interaction is non-catalytic. USP9X associates with microtubules at specific subcellular compartments enriched in DCX.","method":"Targeted mutagenesis, co-localization, co-immunoprecipitation, ubiquitination detection (negative result for DCX)","journal":"Molecular and cellular neurosciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP, mutagenesis mapping of novel interaction domain, microtubule co-localization, single lab","pmids":["15607950"],"is_preprint":false},{"year":2017,"finding":"NPHP5 (nephrocystin-5) directly binds USP9X. In G0/G1/S phase, a pool of cytoplasmic USP9X is recruited to the centrosome by NPHP5, protecting NPHP5 from ubiquitination and favouring cilia assembly. In G2/M, USP9X dissociates from the centrosome, allowing BBS11 to K63-ubiquitinate NPHP5, triggering delocalization and cilia loss.","method":"Co-immunoprecipitation, ubiquitination assay (K48/K63 typing), cell cycle synchronization, cilia assembly assay, RNAi knockdown","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 / Moderate — cell cycle-dependent subcellular redistribution with functional consequence, ubiquitin chain typing, ciliogenesis assay, single lab multiple methods","pmids":["28498859"],"is_preprint":false},{"year":2019,"finding":"USP9X binds PCM1 and antagonizes MIB1-mediated PCM1 ubiquitylation, protecting PCM1 from proteasomal degradation. Knockdown of USP9X reduces PCM1 protein levels and disrupts centriolar satellite integrity, causing satellite proteins such as CEP290 to relocalize to centrosomes.","method":"Co-immunoprecipitation, deubiquitylation assay, RNAi knockdown, centriolar satellite microscopy, epistasis (MIB1 knockdown rescues PCM1 levels)","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Moderate — deubiquitination assay, genetic epistasis with MIB1, functional centriolar satellite phenotype, single lab","pmids":["30584065"],"is_preprint":false},{"year":2019,"finding":"SNX17 recruits USP9X to antagonize MIB1-induced ubiquitination and degradation of PCM1 during serum-starvation-induced ciliogenesis. SNX17 deficiency leads to enhanced degradation of both USP9X and PCM1 and disrupts ciliogenesis.","method":"Co-immunoprecipitation, ubiquitination assay, ciliogenesis assay, SNX17 knockdown, RNAi","journal":"Cells","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP, functional ciliogenesis phenotype, USP9X stability regulated by SNX17, single lab","pmids":["31671755"],"is_preprint":false},{"year":2019,"finding":"USP9X deubiquitinates and stabilizes PTGES (prostaglandin E synthase) by physically interacting with it and preventing proteasome-directed degradation, thereby promoting PGE2 synthesis and metastatic features of NSCLC.","method":"Co-immunoprecipitation, deubiquitination assay, RNAi knockdown, in vivo metastasis model","journal":"American journal of cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP, deubiquitination assay, in vivo metastasis data, single lab","pmids":["31285948"],"is_preprint":false},{"year":2018,"finding":"USP9X deubiquitinates and stabilizes BRCA1. Reciprocal co-IP confirms USP9X-BRCA1 interaction. Depletion of USP9X reduces BRCA1 abundance, shortens its half-life, increases its ubiquitination, reduces HR efficiency, and sensitizes cells to PARP inhibitors and MMS. Catalytically dead USP9X (C1566S) does not upregulate BRCA1.","method":"Reciprocal co-immunoprecipitation, RNAi knockdown, overexpression of WT vs. C1566S mutant, HR assay, drug sensitivity assay","journal":"Cancer medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — catalytic mutant confirms enzymatic requirement, reciprocal co-IP, HR functional assay, single lab","pmids":["31512408"],"is_preprint":false},{"year":2022,"finding":"USP9X removes K63-linked polyubiquitin from SR-A1 (class A1 scavenger receptor) at the K27 site, reducing SR-A1 cell surface internalization after ox-LDL binding. K27R mutation of SR-A1 attenuates USP9X knockdown-induced ox-LDL uptake, establishing USP9X as a regulator of SR-A1 ubiquitination and macrophage foam cell formation.","method":"Loss-of-function screening, co-immunoprecipitation, site-specific mutagenesis (K27R), ubiquitin chain type analysis, macrophage foam cell assay, macrophage-specific KO mouse","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 / Strong — site-specific mutagenesis, chain-type defined, macrophage-specific KO mouse in vivo, multiple orthogonal methods","pmids":["35389885"],"is_preprint":false},{"year":2022,"finding":"USP9X deubiquitinates and stabilizes Snail1, promoting its function in epithelial-mesenchymal transition in TNBC. Depletion of USP9X downregulates Snail1, inhibits migration/invasion, and increases sensitivity to cisplatin and paclitaxel; reconstitution of Snail1 in USP9X-depleted cells partially reverses these effects.","method":"Co-immunoprecipitation, deubiquitination assay, RNAi knockdown, Snail1 rescue experiment, in vitro and in vivo metastasis assays","journal":"Journal of cellular physiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP, deubiquitination assay, rescue experiment confirms pathway placement, single lab","pmids":["35506169"],"is_preprint":false},{"year":2021,"finding":"USP9X deubiquitinates NLRP3, preventing its ubiquitination and stabilizing NLRP3 protein (not mRNA). USP9X knockdown increases NLRP3 ubiquitination and reduces NLRP3 inflammasome activation and pyroptosis in alveolar epithelial cells; NLRP3 overexpression rescues these effects.","method":"Co-immunoprecipitation, ubiquitination assay, RNAi knockdown, overexpression rescue, pyroptosis assay","journal":"Cell biology international","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-IP and ubiquitination shown, rescue experiment confirms pathway placement, single lab","pmids":["36525374"],"is_preprint":false},{"year":2023,"finding":"USP9X deubiquitinates and stabilizes NRP1 (neuropilin-1), with USP9X-mediated NRP1 deubiquitination enhancing hepatic stellate cell (HSC) activation and liver fibrosis. Identified by co-immunoprecipitation and GST pulldown with in vivo and in vitro ubiquitination assays.","method":"Co-immunoprecipitation, GST pulldown, in vivo and in vitro ubiquitination assay, immunohistochemistry, RNAi knockdown","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP, GST pulldown, in vivo ubiquitination assay, functional HSC activation phenotype, single lab","pmids":["36653359"],"is_preprint":false},{"year":2018,"finding":"USP9X deubiquitinates Cx43 (connexin 43) by directly binding to Cx43's C-terminal Tyr286, preventing its degradation. USP9X overexpression suppresses high glucose-induced EMT in NRK-52E cells in a deubiquitinase activity-dependent manner (catalytically inactive C1556S mutant has no effect).","method":"CRISPR/Cas9 SAM overexpression, RNAi knockdown, co-immunoprecipitation, ubiquitination assay, catalytic mutant (C1556S), EMT marker quantification","journal":"Biochemical pharmacology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — binding site mapped to Tyr286, catalytic mutant control, functional EMT readout, single lab","pmids":["33857489"],"is_preprint":false},{"year":2018,"finding":"USP9X deubiquitinates Nrf2, reducing its ubiquitination level and promoting Nrf2-ARE pathway activation, thereby limiting ROS production and extracellular matrix accumulation in diabetic renal fibrosis conditions. Catalytically inactive USP9X-C1556S fails to stabilize Nrf2.","method":"Co-immunoprecipitation, ubiquitination assay, catalytic mutant (C1556S), Nrf2-ARE reporter assay, ROS measurement, RNAi knockdown","journal":"Experimental cell research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — catalytic mutant confirmation, Nrf2 ubiquitination reduced, functional ARE reporter, single lab","pmids":["32442538"],"is_preprint":false},{"year":2018,"finding":"USP9X stabilizes ZBTB38 (methyl-CpG-binding protein) by interacting with it and deubiquitinating it. USP9X itself is stabilized by oxidative stress. Both USP9X and ZBTB38 are required to limit basal ROS generation and toxicity of acute oxidative stress.","method":"Co-immunoprecipitation, deubiquitination assay, RNAi knockdown, ROS measurement, protein stability assay","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP and deubiquitination assay, functional ROS phenotype, single lab","pmids":["29490077"],"is_preprint":false},{"year":2017,"finding":"USP9X is required for spermatogenesis: germ cell-specific conditional deletion of Usp9x results in apoptotic cell death at the early spermatocyte stage and subsequent aberrant spermiogenesis, establishing a critical role for USP9X in the mitosis-to-meiosis transition in male germ cells.","method":"Vasa-Cre conditional Usp9x knockout mouse, histology, apoptosis detection","journal":"Reproduction (Cambridge, England)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — conditional KO mouse with defined developmental phenotype, single lab","pmids":["28559472"],"is_preprint":false}],"current_model":"USP9X is a substrate-specific deubiquitinase that removes diverse ubiquitin chain types (K48, K63, K29/K33, monoubiquitin) from a broad range of substrates—including MCL1, FBW7, LATS1/2, CLASPIN, RAPTOR, RICTOR, ankyrin-G, DVL2, α-synuclein, ASK1, ITCH, SMURF1, CEP131/PCM1, BRCA1, eIF4A1, ZAP70, Bcl10, PRICKLE, and many others—to control their protein stability and thereby regulate cell survival, apoptosis, Hippo/Wnt/Notch/TGF-β/mTOR signaling, neuronal development and migration, centrosome biogenesis, ciliogenesis, DNA replication checkpoint, ribosomal quality control, T/B cell activation, and circadian rhythm; its activity is itself regulated by post-translational modifications including CDK1-mediated phosphorylation at S2563 (activating) and S-nitrosylation, and by interaction partners such as SNX17 and TDRD3."},"narrative":{"mechanistic_narrative":"USP9X is a substrate-specific deubiquitinase that opposes ubiquitin-dependent proteasomal degradation of a broad set of regulatory proteins, thereby controlling cell survival, signaling, and cytoskeletal and developmental programs [PMID:20023629, PMID:29346117]. Its prototypical mode of action is removal of degradative polyubiquitin chains from short-lived substrates to extend their half-life: it stabilizes the anti-apoptotic protein MCL1 by cleaving Lys48-linked chains to promote cell survival [PMID:20023629], and analogously stabilizes the tumor-suppressor F-box protein FBW7 upstream of c-Myc [PMID:29346117], the DNA-replication checkpoint factor CLASPIN to sustain fork progression and CHK1 activation [PMID:26921344], BRCA1 to support homologous recombination [PMID:31512408], and the translation-initiation factor eIF4A1 to maintain cap-dependent synthesis of pro-oncogenic mRNAs [PMID:29228324]. A recurring theme is the stabilization of HECT- and RING-family E3 ligases and of other ubiquitin-pathway enzymes—ITCH, SMURF1, and MARCH7—by antagonizing their auto-ubiquitination [PMID:17038327, PMID:23184937, PMID:18410486]. Through these substrates USP9X tunes multiple developmental signaling pathways: it stabilizes LATS1/2 and Angiomotin to restrain YAP/TAZ in the Hippo pathway [PMID:28720576, PMID:27462448], acts as a WWP1-antagonizing rheostat on DVL2 and deubiquitinates BCL9 and β-catenin to direct Wnt signaling [PMID:31340145, PMID:27783990, PMID:31073027], activates Notch via MIB1 [PMID:33547080, PMID:27593927], and supports TGF-β/SMAD4 nuclear retention [PMID:28115363]. It assembles and activates mTORC1 and mTORC2 by stabilizing RAPTOR and deubiquitinating RICTOR [PMID:28341829, PMID:33378666]. USP9X is also an integral centrosomal and centriolar-satellite component that protects CEP131, PCM1, and NPHP5 to support centrosome biogenesis and cell-cycle–coupled ciliogenesis [PMID:28361952, PMID:28498859, PMID:30584065], and is required in neurons for axon growth, migration, and dendritic spine maintenance, partly through stabilization of ankyrin-G [PMID:24607389, PMID:23861879, PMID:31813652]; loss-of-function human variants that fail to rescue axonal defects link USP9X to intellectual disability [PMID:24607389]. Its catalytic output is gated by post-translational modification, including CDK1-dependent phosphorylation at Ser2563 (antagonized by CDC14B) that licenses mitotic deubiquitination of WT1 [PMID:32152317], S-nitrosylation that enables MIB1 stabilization and NOTCH1 signaling [PMID:33547080], TCR-dependent phosphorylation that enhances activity toward ZAP70 [PMID:26936881], and arginine methylation that recruits TDRD3 to direct stress-granule localization [PMID:28101374].","teleology":[{"year":2006,"claim":"Established that USP9X protects E3 ubiquitin ligases from auto-ubiquitination, revealing a recurring strategy of stabilizing ubiquitin-pathway enzymes rather than only their downstream targets.","evidence":"GST pulldown, reciprocal co-IP, and RNAi rescue with proteasome inhibitor showing FAM/USP9X binds ITCH WW domains and reverses its auto-ubiquitination","pmids":["17038327"],"confidence":"High","gaps":["Chain topology removed from ITCH not defined","Catalytic-dead controls not used in this study"]},{"year":2008,"claim":"Showed USP9X removes atypical Lys29/Lys33 chains and that these non-degradative chains regulate kinase activity, broadening USP9X chain specificity beyond canonical degradation signals.","evidence":"In vitro deubiquitinase assay, chain topology analysis, and mutagenesis on NUAK1 and MARK4","pmids":["18254724"],"confidence":"High","gaps":["Direct demonstration that polyubiquitination inhibits T-loop phosphorylation remains inferential","In vivo relevance not established"]},{"year":2009,"claim":"Identified USP9X as a stabilizer of the anti-apoptotic protein MCL1 via Lys48-chain removal, defining its central pro-survival role and oncogenic relevance.","evidence":"Co-IP, ubiquitination assays, and RNAi knockdown with survival readouts in cancer cells","pmids":["20023629"],"confidence":"High","gaps":["Structural basis of MCL1 recognition not resolved","Regulation of the USP9X-MCL1 interaction not addressed here"]},{"year":2009,"claim":"Demonstrated USP9X stabilizes activated ASK1 to sustain oxidative-stress JNK signaling, extending its survival/death control into stress kinase pathways via a ubiquitin-like recognition motif.","evidence":"Co-IP, binding-domain mutagenesis of the ASK1 LRLRGG sequence, and JNK/cell-death assays in USP9X-deficient cells","pmids":["20005844"],"confidence":"High","gaps":["Chain type removed from ASK1 not defined","Whether the GG motif is a general USP9X docking site untested"]},{"year":2011,"claim":"Linked USP9X to neurodegeneration-relevant proteostasis by showing it removes SIAH-added monoubiquitin from α-synuclein and routes it toward autophagy versus proteasome.","evidence":"Deubiquitinase assays, RNAi/overexpression, and cell fractionation distinguishing degradation routes","pmids":["22065755"],"confidence":"High","gaps":["In vivo brain relevance not tested","Mechanism of degradation-route selection unresolved"]},{"year":2013,"claim":"Defined USP9X as a regulator of neural development, showing conditional loss disrupts cortical organization and axonogenesis partly through impaired TGF-β signaling.","evidence":"Nestin-cre and Emx1-cre conditional knockouts with in vivo/in vitro axon-length and TGF-β analyses","pmids":["23861879"],"confidence":"High","gaps":["Direct deubiquitination substrate driving axon phenotype not identified","TGF-β linkage correlative"]},{"year":2013,"claim":"Placed USP9X in adaptive immunity by showing it deubiquitinates Bcl10 to enable CBM-complex assembly and NF-κB activation downstream of the TCR.","evidence":"Co-IP, RNAi in T-cell lines and primary T cells, and adoptive-transfer immunization","pmids":["23690623"],"confidence":"High","gaps":["Chain type on Bcl10 not fully defined","Direct vs scaffold role within CBM not separated"]},{"year":2014,"claim":"Provided causal disease evidence by demonstrating that intellectual-disability–associated USP9X variants fail to rescue axon growth and growth-cone localization in Usp9x-null neurons.","evidence":"Usp9x knockout mouse with human wild-type and variant rescue, axon/migration assays, and proteomics of null neurons","pmids":["24607389"],"confidence":"High","gaps":["Molecular substrate underlying growth-cone defect not pinpointed","Genotype-phenotype mechanism for each variant incomplete"]},{"year":2016,"claim":"Revealed substrate-directed, signal-activated catalysis by showing TCR phosphorylation enhances USP9X activity toward ZAP70 and that USP9X controls B-cell receptor signaling.","evidence":"Usp9X knockout mouse, ubiquitination and kinase-activity assays, and endosomal localization analysis","pmids":["26936881"],"confidence":"High","gaps":["Kinase phosphorylating USP9X not identified here","ZAP70 ubiquitination site not mapped"]},{"year":2017,"claim":"Consolidated USP9X as a Hippo-pathway regulator by demonstrating it stabilizes LATS1/2 and Angiomotin to restrain YAP/TAZ-driven oncogenesis and EMT.","evidence":"Co-IP, gel filtration, MEF knockout, site-specific deubiquitination (AMOT K496), and YAP/TAZ reporter/soft-agar assays","pmids":["28720576","29183995","27462448"],"confidence":"High","gaps":["Whether USP9X acts on multiple Hippo nodes simultaneously in vivo unclear","Some node studies single-lab"]},{"year":2017,"claim":"Established USP9X as an integral centrosome and centriolar-satellite component that stabilizes CEP131, PCM1, CEP55, and NPHP5 to control centrosome biogenesis and cell-cycle–coupled ciliogenesis.","evidence":"Co-IP, deubiquitinase assays, centrosome localization microscopy, cell-cycle synchronization, and MIB1-epistasis ciliogenesis assays","pmids":["28361952","28620049","28498859","30584065","31671755"],"confidence":"High","gaps":["Recruitment hierarchy among satellite partners incompletely ordered","Some interactions (CEP55, SNX17) Medium-confidence single-lab"]},{"year":2018,"claim":"Demonstrated tumor-suppressive control of FBW7 and downstream c-Myc in vivo, showing USP9X stabilizes an E3 ligase to restrain proliferation and tumorigenesis.","evidence":"Conditional gut knockout, proteomics, organoids, and genetic epistasis with c-Myc heterozygosity","pmids":["29346117"],"confidence":"High","gaps":["Chain type removed from FBW7 not defined","Tissue specificity of the FBW7-c-Myc axis untested elsewhere"]},{"year":2019,"claim":"Defined USP9X as a Wnt-pathway rheostat by showing it antagonizes WWP1 on DVL2 and deubiquitinates BCL9 to specify canonical versus PCP outcomes and potentiate β-catenin transcription.","evidence":"Deubiquitination assays, WNT/PCP reporters, site-specific ubiquitination mapping (BCL9 K212), and ChIP","pmids":["31340145","31073027"],"confidence":"High","gaps":["Quantitative rules of the WWP1-USP9X balance unresolved","BCL9 study Medium-confidence single-lab"]},{"year":2019,"claim":"Connected USP9X to neuronal cytoskeletal scaffolding by showing phosphorylation-enhanced deubiquitination of ankyrin-G maintains dendritic spine density into adulthood.","evidence":"Forebrain-specific conditional knockout, ubiquitination assays, phosphorylation analysis, and spine-density measurement","pmids":["31813652"],"confidence":"High","gaps":["Kinase responsible for the activating phosphorylation not identified","Transient versus persistent substrate effects not fully explained"]},{"year":2020,"claim":"Defined the mitotic activation switch by showing CDK1 phosphorylates USP9X at Ser2563 (reversed by CDC14B) to license deubiquitination and stabilization of the mitotic transcription factor WT1.","evidence":"Proteome-wide phosphorylation screening, in vitro phosphorylation, deubiquitination assays, and CXCL8 reporter assay","pmids":["32152317"],"confidence":"High","gaps":["Full substrate set gated by Ser2563 phosphorylation unknown","Structural impact of the modification unresolved"]},{"year":2020,"claim":"Showed USP9X assembles mTORC2 by removing Lys63 chains from RICTOR to promote mTOR association, complementing earlier RAPTOR/mTORC1 stabilization and placing USP9X in growth-factor mTOR control.","evidence":"Co-IP, chain-type analysis, mTORC2 kinase assays in cells and mice","pmids":["33378666","28341829","22544753"],"confidence":"High","gaps":["How USP9X coordinately balances mTORC1 vs mTORC2 unclear","RAPTOR ubiquitination site not mapped"]},{"year":2021,"claim":"Identified S-nitrosylation as a redox-sensitive regulatory switch enabling USP9X to stabilize MIB1 and drive NOTCH1 signaling, with in vivo relevance to aortic valve disease.","evidence":"Unbiased S-nitrosylation proteomics, mouse knockout, scRNA-seq, and in vitro deubiquitination","pmids":["33547080"],"confidence":"High","gaps":["S-nitrosylated residues not enumerated mechanistically","Generality of redox gating across substrates untested"]},{"year":2021,"claim":"Extended USP9X function to translational quality control by showing it stabilizes the RQC E3 ligases Makorin 2 and ZNF598 to sustain ribosomal stalling responses.","evidence":"Validated small-molecule USP9X inhibitor, proteomics, co-IP, and ribosomal-stalling assays","pmids":["33507233"],"confidence":"High","gaps":["Direct deubiquitination of these ligases versus indirect effects not fully separated","Physiological RQC consequences in vivo untested"]},{"year":2022,"claim":"Demonstrated in vivo metabolic-disease relevance by showing USP9X removes Lys63 chains from a defined site on scavenger receptor SR-A1 to limit ox-LDL uptake and foam-cell formation.","evidence":"Loss-of-function screen, site-specific K27R mutagenesis, chain typing, and macrophage-specific knockout mouse","pmids":["35389885"],"confidence":"High","gaps":["Whether SR-A1 regulation generalizes to other scavenger receptors unknown","Upstream signal controlling this activity unclear"]},{"year":null,"claim":"It remains unresolved how USP9X achieves substrate selectivity across its very broad substrate range and how its multiple regulatory modifications are integrated to direct activity toward specific substrates in a given context.","evidence":"No single study in the corpus reconstitutes substrate-selection rules or a unified regulatory logic","pmids":[],"confidence":"Low","gaps":["No structural model of substrate or chain-type recognition","No systematic map linking each PTM (phosphorylation, S-nitrosylation, methylation) to specific substrate pools","Adaptor-driven recruitment (e.g., SNX17, TDRD3, NPHP5) not generalized into a recruitment code"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,1,5,30,38,51]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[0,5,8,50]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[5,6,20,33,40]}],"localization":[{"term_id":"GO:0005815","term_label":"microtubule organizing center","supporting_discovery_ids":[24,25,46,47]},{"term_id":"GO:0005929","term_label":"cilium","supporting_discovery_ids":[46,47,48]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[20,28,29]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[16,45]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[18,22]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[12,23,27,34,35,33,44,38]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[0,4,14,36]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[21,22,53]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[24,39,46,30]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[40,41]},{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[30,50]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[16,17,26,58]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[2,3]}],"complexes":["CARMA1-BCL10-MALT1 (CBM) complex","mTORC1","mTORC2","centrosome / centriolar satellites"],"partners":["MCL1","FBW7","ITCH","SMURF1","MIB1","PCM1","CLASPIN","DVL2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q93008","full_name":"Ubiquitin carboxyl-terminal hydrolase 9X","aliases":["Deubiquitinating enzyme FAF-X","Fat facets in mammals","hFAM","Fat facets protein-related, X-linked","Ubiquitin thioesterase FAF-X","Ubiquitin-specific protease 9, X chromosome","Ubiquitin-specific-processing protease FAF-X"],"length_aa":2554,"mass_kda":290.5,"function":"Deubiquitinase involved both in the processing of ubiquitin precursors and of ubiquitinated proteins (PubMed:18254724, PubMed:19135894, PubMed:22371489, PubMed:25944111, PubMed:29626158, PubMed:30914461, PubMed:37454738). May therefore play an important regulatory role at the level of protein turnover by preventing degradation of proteins through the removal of conjugated ubiquitin (PubMed:18254724, PubMed:19135894, PubMed:22371489, PubMed:25944111, PubMed:29626158, PubMed:30914461, PubMed:37454738). Specifically hydrolyzes 'Lys-11'-, followed by 'Lys-63'-, 'Lys-48'- and 'Lys-6'-linked polyubiquitins chains (PubMed:30914461). Essential component of TGF-beta/BMP signaling cascade (PubMed:19135894). Specifically deubiquitinates monoubiquitinated SMAD4, opposing the activity of E3 ubiquitin-protein ligase TRIM33 (PubMed:19135894). Deubiquitinates alkylation repair enzyme ALKBH3 (PubMed:25944111). OTUD4 recruits USP7 and USP9X to stabilize ALKBH3, thereby promoting the repair of alkylated DNA lesions (PubMed:25944111). Deubiquitinates RNA demethylase enzyme ALKBH5, promoting its stability (PubMed:37454738). Deubiquitinates mTORC2 complex component RICTOR at 'Lys-294' by removing 'Lys-63'-linked polyubiquitin chains, stabilizing RICTOR and enhancing its binding to MTOR, thus promoting mTORC2 complex assembly (PubMed:33378666). Regulates chromosome alignment and segregation in mitosis by regulating the localization of BIRC5/survivin to mitotic centromeres (PubMed:16322459). Involved in axonal growth and neuronal cell migration (PubMed:24607389). Regulates cellular clock function by enhancing the protein stability and transcriptional activity of the core circadian protein BMAL1 via its deubiquitinating activity (PubMed:29626158). Acts as a regulator of peroxisome import by mediating deubiquitination of PEX5: specifically deubiquitinates PEX5 monoubiquitinated at 'Cys-11' following its retrotranslocation into the cytosol, resetting PEX5 for a subsequent import cycle (PubMed:22371489). Deubiquitinates PEG10 (By similarity). Inhibits the activation of the Hippo signaling pathway via deubiquitination of AMOTL2 at 'Lys-347' and 'Lys-408' which prohibits its interaction with and activation of LATS2. Loss of LATS2 activation and subsequent loss of YAP1 phosphorylation results in an increase in YAP1-driven transcription of target genes (PubMed:26598551, PubMed:34404733)","subcellular_location":"Cytoplasm, cytosol; Cell projection, growth cone; Cytoplasm, cytoskeleton, cilium axoneme","url":"https://www.uniprot.org/uniprotkb/Q93008/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/USP9X","classification":"Common 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chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/28620049","citation_count":28,"is_preprint":false},{"pmid":"32152317","id":"PMC_32152317","title":"Antagonistic activities of CDC14B and CDK1 on USP9X regulate WT1-dependent mitotic transcription and survival.","date":"2020","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/32152317","citation_count":28,"is_preprint":false},{"pmid":"28808228","id":"PMC_28808228","title":"Loss of Usp9x disrupts cell adhesion, and components of the Wnt and Notch signaling pathways in neural progenitors.","date":"2017","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/28808228","citation_count":28,"is_preprint":false},{"pmid":"27517496","id":"PMC_27517496","title":"USP9X destabilizes pVHL and promotes cell proliferation.","date":"2016","source":"Oncotarget","url":"https://pubmed.ncbi.nlm.nih.gov/27517496","citation_count":27,"is_preprint":false},{"pmid":"33378666","id":"PMC_33378666","title":"mTORC2 Assembly Is Regulated by USP9X-Mediated Deubiquitination of RICTOR.","date":"2020","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/33378666","citation_count":26,"is_preprint":false},{"pmid":"29130109","id":"PMC_29130109","title":"Deubiquitinase USP9X promotes cell migration, invasion and inhibits apoptosis of human pancreatic cancer.","date":"2017","source":"Oncology reports","url":"https://pubmed.ncbi.nlm.nih.gov/29130109","citation_count":25,"is_preprint":false},{"pmid":"28559472","id":"PMC_28559472","title":"Spermatogonial deubiquitinase USP9X is essential for proper spermatogenesis in mice.","date":"2017","source":"Reproduction (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/28559472","citation_count":25,"is_preprint":false},{"pmid":"38582329","id":"PMC_38582329","title":"Cellular functions, molecular signalings and therapeutic applications: Translational potential of deubiquitylating enzyme USP9X as a drug target in cancer treatment.","date":"2024","source":"Biochimica et biophysica acta. Reviews on cancer","url":"https://pubmed.ncbi.nlm.nih.gov/38582329","citation_count":24,"is_preprint":false},{"pmid":"31073027","id":"PMC_31073027","title":"USP9X-mediated deubiquitination of B-cell CLL/lymphoma 9 potentiates Wnt signaling and promotes breast carcinogenesis.","date":"2019","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/31073027","citation_count":24,"is_preprint":false},{"pmid":"30584065","id":"PMC_30584065","title":"Deubiquitylase USP9X maintains centriolar satellite integrity by stabilizing pericentriolar material 1 protein.","date":"2019","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/30584065","citation_count":24,"is_preprint":false},{"pmid":"34079080","id":"PMC_34079080","title":"Elevated USP9X drives early-to-late-stage oral tumorigenesis via stabilisation of anti-apoptotic MCL-1 protein and impacts outcome in oral cancers.","date":"2021","source":"British journal of cancer","url":"https://pubmed.ncbi.nlm.nih.gov/34079080","citation_count":23,"is_preprint":false},{"pmid":"29626158","id":"PMC_29626158","title":"Deubiquitinating enzyme USP9X regulates cellular clock function by modulating the ubiquitination and degradation of a core circadian protein BMAL1.","date":"2018","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/29626158","citation_count":23,"is_preprint":false},{"pmid":"29490077","id":"PMC_29490077","title":"Stabilization of the methyl-CpG binding protein ZBTB38 by the deubiquitinase USP9X limits the occurrence and toxicity of oxidative stress in human cells.","date":"2018","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/29490077","citation_count":23,"is_preprint":false},{"pmid":"36525374","id":"PMC_36525374","title":"USP9X promotes lipopolysaccharide-stimulated acute lung injury by deubiquitination of NLRP3.","date":"2022","source":"Cell biology international","url":"https://pubmed.ncbi.nlm.nih.gov/36525374","citation_count":22,"is_preprint":false},{"pmid":"36890708","id":"PMC_36890708","title":"Circ-USP9X interacts with EIF4A3 to promote endothelial cell pyroptosis by regulating GSDMD stability in atherosclerosis.","date":"2023","source":"Clinical and experimental hypertension (New York, N.Y. : 1993)","url":"https://pubmed.ncbi.nlm.nih.gov/36890708","citation_count":22,"is_preprint":false},{"pmid":"31671755","id":"PMC_31671755","title":"SNX17 Recruits USP9X to Antagonize MIB1-Mediated Ubiquitination and Degradation of PCM1 during Serum-Starvation-Induced Ciliogenesis.","date":"2019","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/31671755","citation_count":21,"is_preprint":false},{"pmid":"29228324","id":"PMC_29228324","title":"USP9X controls translation efficiency via deubiquitination of eukaryotic translation initiation factor 4A1.","date":"2018","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/29228324","citation_count":21,"is_preprint":false},{"pmid":"32442538","id":"PMC_32442538","title":"USP9X prevents AGEs-induced upregulation of FN and TGF-β1 through activating Nrf2-ARE pathway in rat glomerular mesangial cells.","date":"2020","source":"Experimental cell research","url":"https://pubmed.ncbi.nlm.nih.gov/32442538","citation_count":21,"is_preprint":false},{"pmid":"26717875","id":"PMC_26717875","title":"β-catenin is regulated by USP9x and mediates resistance to TRAIL-induced apoptosis in breast cancer.","date":"2015","source":"Oncology reports","url":"https://pubmed.ncbi.nlm.nih.gov/26717875","citation_count":21,"is_preprint":false},{"pmid":"27374971","id":"PMC_27374971","title":"Deubiquitylating enzyme, USP9X, regulates proliferation of cells of head and neck cancer lines.","date":"2016","source":"Cell proliferation","url":"https://pubmed.ncbi.nlm.nih.gov/27374971","citation_count":20,"is_preprint":false},{"pmid":"31216195","id":"PMC_31216195","title":"USP9X promotes LPS-induced pulmonary epithelial barrier breakdown and hyperpermeability by activating an NF-κBp65 feedback loop.","date":"2019","source":"American journal of physiology. Cell physiology","url":"https://pubmed.ncbi.nlm.nih.gov/31216195","citation_count":20,"is_preprint":false},{"pmid":"14516667","id":"PMC_14516667","title":"Stage- and sex-dependent expressions of Usp9x, an X-linked mouse ortholog of Drosophila Fat facets, during gonadal development and oogenesis in mice.","date":"2002","source":"Mechanisms of development","url":"https://pubmed.ncbi.nlm.nih.gov/14516667","citation_count":20,"is_preprint":false},{"pmid":"37920433","id":"PMC_37920433","title":"Roles of USP9X in cellular functions and tumorigenesis (Review).","date":"2023","source":"Oncology letters","url":"https://pubmed.ncbi.nlm.nih.gov/37920433","citation_count":19,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":50197,"output_tokens":14400,"usd":0.183296,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":26373,"output_tokens":6500,"usd":0.147182,"stage2_stop_reason":"end_turn"},"total_usd":0.330478,"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\": 2009,\n      \"finding\": \"USP9X binds MCL1 and removes Lys48-linked polyubiquitin chains from MCL1, preventing its proteasomal degradation and thereby stabilizing MCL1 to promote cell survival. Knockdown of USP9X increases MCL1 polyubiquitination and enhances MCL1 turnover.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assays, RNAi knockdown, cell survival assays\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal binding demonstrated, ubiquitin chain topology defined, replicated across multiple labs and cancer types\",\n      \"pmids\": [\"20023629\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"USP9X interacts with and deubiquitinates AMPK-related kinases NUAK1 and MARK4, removing atypical Lys29/Lys33-linked polyubiquitin chains. Non-USP9X-binding mutants of NUAK1 and MARK4 are hyper-ubiquitinated and lack LKB1-mediated T-loop phosphorylation, suggesting polyubiquitination inhibits these kinases.\",\n      \"method\": \"Co-immunoprecipitation, in vitro deubiquitinase assay, ubiquitin chain topology analysis, mutagenesis, overexpression/knockdown\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro deubiquitinase assay with mutagenesis, chain topology determined, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"18254724\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"USP9X mediates selective autophagy (zymophagy) of activated zymogen granules in pancreatic acinar cells by interacting with the autophagy protein VMP1 and the ubiquitin-binding protein p62, forming a VMP1-USP9X-p62 pathway required for selective autophagosome formation.\",\n      \"method\": \"Co-immunoprecipitation, cellular/biochemical characterization, genetically engineered mice, cultured acinar cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP of VMP1-USP9X interaction, loss-of-function in cells and mice, single lab\",\n      \"pmids\": [\"21173155\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"USP9X interacts with and deubiquitinates α-synuclein, removing monoubiquitin added by SIAH. Deubiquitinated α-synuclein is preferentially degraded by autophagy, while monoubiquitinated α-synuclein is preferentially degraded by the proteasome. USP9X knockdown promotes accumulation of monoubiquitinated α-synuclein and toxic inclusions.\",\n      \"method\": \"Co-immunoprecipitation, deubiquitinase activity assay, RNAi knockdown, USP9X overexpression, cell fractionation\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro/in vivo deubiquitination demonstrated, pathway placement (autophagy vs. proteasome) defined by gain/loss-of-function, multiple orthogonal methods\",\n      \"pmids\": [\"22065755\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"USP9X binds ASK1 via a ubiquitin-like GG sequence (LRLRGG) in ASK1's C-terminus and stabilizes activated ASK1 by preventing its ubiquitin-dependent degradation. USP9X-deficient cells show reduced oxidative stress-induced JNK activation and cell death.\",\n      \"method\": \"Co-immunoprecipitation, binding domain mutagenesis, USP9X-deficient cells, JNK activation assay, cell death assay\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — interaction domain mapped by mutagenesis, loss-of-function phenotype defined, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"20005844\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"FAM/USP9X binds the ITCH ubiquitin ligase via ITCH's WW domains, deubiquitinates auto-ubiquitinated ITCH, and protects it from proteasomal degradation. RNAi depletion of FAM/USP9X reduces endogenous ITCH levels, rescued by proteasome inhibitor.\",\n      \"method\": \"GST pulldown, co-immunoprecipitation, co-localization, RNAi knockdown, overexpression\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — GST pulldown + reciprocal co-IP, RNAi rescue with proteasome inhibitor, replicated concept confirmed by multiple subsequent studies\",\n      \"pmids\": [\"17038327\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"FAM/USP9X interacts with the E3 ubiquitin ligase SMURF1 through the second WW domain of SMURF1 and the C-terminus of USP9X. USP9X antagonizes SMURF1 auto-ubiquitination and proteasomal degradation, thereby stabilizing SMURF1. Depletion of USP9X reduces SMURF1 levels and impairs cell migration in MDA-MB-231 breast cancer cells.\",\n      \"method\": \"Quantitative mass spectrometry, co-immunoprecipitation, domain mapping, deubiquitination assay, RNAi knockdown, cell migration assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — domain mapping, deubiquitination assay, functional migration phenotype upon knockdown, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"23184937\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"USP9X interacts with and deubiquitinates FBW7, preventing its ubiquitin-dependent degradation. Usp9x deletion in mouse gut causes Fbw7 destabilization, reduces secretory cell differentiation, increases progenitor proliferation, and increases tumor burden in colitis-associated cancer. c-Myc heterozygosity rescues the proliferation and tumor phenotype, placing USP9X upstream of FBW7-c-Myc.\",\n      \"method\": \"Proteomics, co-immunoprecipitation, conditional mouse knockout, genetic epistasis (c-Myc heterozygosity), intestinal organoids\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis in vivo, proteomics-identified interaction, conditional KO with defined phenotype, multiple orthogonal methods\",\n      \"pmids\": [\"29346117\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"USP9X interacts with, depolyubiquitylates, and stabilizes ALDH1A3 in mesenchymal glioblastoma stem cells (GSCs). Depletion of USP9X downregulates ALDH1A3, reducing self-renewal and tumorigenic capacity of MES GSCs; ectopic ALDH1A3 expression rescues these defects.\",\n      \"method\": \"Co-immunoprecipitation, deubiquitination assay, RNAi knockdown, rescue experiment, orthotopic xenograft model\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo deubiquitination, rescue experiment with ALDH1A3, xenograft validation, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"30958800\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"USP9X deubiquitinates and stabilizes YAP1 by removing polyubiquitin chains, preventing its proteasomal degradation. Depletion of USP9X increases YAP1 polyubiquitination and turnover, sensitizing breast cancer cells to chemotherapy.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, RNAi knockdown, overexpression\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — co-IP and ubiquitination assay, single lab, single paper\",\n      \"pmids\": [\"29449692\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"S-nitrosylation of USP9X (by nitric oxide) enables USP9X to deubiquitinate and stabilize MIB1, which activates NOTCH1 signaling. Genetic deletion of Usp9x in mice causes calcific aortic valve disease, and human calcified aortic valves show reduced S-nitrosylation of USP9X.\",\n      \"method\": \"Unbiased proteomics for S-nitrosylated proteins, co-immunoprecipitation, mouse genetic knockout, single-cell RNA-seq, in vitro deubiquitination assay\",\n      \"journal\": \"Science advances\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — unbiased proteomics, mouse KO phenotype, in vitro deubiquitination, PTM (S-nitrosylation) identified as regulatory switch, multiple orthogonal methods single lab\",\n      \"pmids\": [\"33547080\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"USP9X binds and deubiquitinates KDM4C, stabilizing it. Depletion of USP9X reduces KDM4C levels, impairing TGF-β2 transcription (KDM4C reduces H3K9me3 at the TGF-β2 promoter) and reducing radioresistance in lung cancer cells.\",\n      \"method\": \"Tandem affinity purification, co-immunoprecipitation, deubiquitination assay, RNAi knockdown, chromatin assays, in vitro and in vivo models\",\n      \"journal\": \"Cell death and differentiation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — tandem affinity purification, in vitro deubiquitination, functional radioresistance phenotype, single lab\",\n      \"pmids\": [\"33558705\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"USP9X physically associates with LATS kinase (and to lesser extent WW45, KIBRA, Angiomotin) and deubiquitinates/stabilizes LATS. Knockdown of USP9X downregulates LATS, promotes nuclear translocation of YAP/TAZ, and activates EMT. Deletion of Usp9x in mouse embryonic fibroblasts reduces LATS protein.\",\n      \"method\": \"Co-immunoprecipitation, gel filtration chromatography, RNAi knockdown, MEF knockout, YAP/TAZ reporter assay, soft agar assay\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal co-IP, gel filtration, MEF KO corroborates cell line data, multiple labs confirming Hippo pathway regulation by USP9X\",\n      \"pmids\": [\"28720576\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"USP9X (deubiquitylase USP9X) deubiquitinates and stabilizes LATS2, preventing its proteasomal degradation. USP9X ablation reduces LATS2 levels, activates YAP, and enhances oncogenic potential in pancreatic cancer cells. Identified by tandem affinity purification.\",\n      \"method\": \"Tandem affinity purification, co-immunoprecipitation, deubiquitination assay, RNAi knockdown, YAP reporter assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — TAP identification, deubiquitination assay, functional YAP activation phenotype, single lab\",\n      \"pmids\": [\"29183995\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"USP9X stabilizes XIAP by deubiquitylation in mitosis, conferring resistance to mitotic spindle poisons. USP9X knockdown reduces XIAP, sensitizes cells to spindle poisons, and delays lymphoma development in a murine Eμ-Myc model.\",\n      \"method\": \"Co-immunoprecipitation, deubiquitination assay, RNAi knockdown, murine lymphoma model, patient sample correlation\",\n      \"journal\": \"EMBO molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — deubiquitination assay, in vivo mouse model, functional chemoresistance phenotype, single lab\",\n      \"pmids\": [\"27317434\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"WP1130 directly inhibits USP9X deubiquitinase activity in CML cells, leading to downregulation of Mcl-1 and inducing apoptosis. Bcr-Abl undergoes K63-linked ubiquitin modification and aggresomal sequestration upon USP9X inhibition, blocking its signaling.\",\n      \"method\": \"Deubiquitinase activity assay, ubiquitin chain-type analysis, aggresome detection, apoptosis assays\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct enzymatic inhibition assay, aggresome localization, single lab with multiple readouts\",\n      \"pmids\": [\"21248063\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"USP9X loss-of-function (Usp9x knockout mice) causes reduction in axonal growth and neuronal cell migration. Wild-type human USP9X rescues these defects, but three ID-associated missense/truncating variants fail to rescue axonal growth and show reduced localization in axonal growth cones.\",\n      \"method\": \"Usp9x knockout mouse, overexpression rescue with human USP9X variants, axon length measurement, neuronal migration assay, proteomics of Usp9x-null neurons\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — knockout mouse, multiple variant rescue experiments, proteomics identifying cytoskeletal disruption, multiple orthogonal methods\",\n      \"pmids\": [\"24607389\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Conditional deletion of Usp9x from neural progenitors disrupts cellular organization of ventricular/subventricular zones and cortical plate, dramatically reduces axonal length (in vivo and in vitro), partly through failure of TGF-β signaling. Dorsal telencephalon-specific deletion results in corpus callosum reduction and hippocampal size decrease.\",\n      \"method\": \"Conditional Usp9x knockout (Nestin-cre and Emx1-cre), in vivo and in vitro axon length measurement, TGF-β signaling analysis\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — two conditional KO models with distinct phenotypes, in vivo and in vitro axonogenesis assays, TGF-β pathway linkage\",\n      \"pmids\": [\"23861879\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"USP9X controls EGFR endocytosis and trafficking by deubiquitinating Eps15, an endocytic adaptor protein. USP9X depletion affects EGFR internalization; Eps15 monoubiquitination is essential for EGFR internalization.\",\n      \"method\": \"Systematic RNAi screen, co-immunoprecipitation, mapping of Eps15 ubiquitination sites, EGFR trafficking assays\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — systematic RNAi screen + follow-up mechanistic studies, Eps15 ubiquitination sites mapped, functional EGFR trafficking phenotype\",\n      \"pmids\": [\"26748853\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"USP9X deubiquitinates EFA6 (exchange factor for Arf6) at newly forming epithelial cell contacts, transiently protecting it from proteasomal degradation and enabling tight junction biogenesis. Knockdown of either USP9X or EFA6 impairs tight junction formation; EFA6 overexpression rescues TJ biogenesis in USP9X-knockdown cells.\",\n      \"method\": \"Co-localization, co-immunoprecipitation, deubiquitination assay, RNAi knockdown, rescue experiment\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — deubiquitination assay, co-localization at primordial junctions, epistasis rescue experiment, single lab multiple methods\",\n      \"pmids\": [\"20339350\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"MARCH7 (E3 ubiquitin ligase) undergoes autoubiquitylation and associates with USP9X in the cytosol (and USP7 in the nucleus). USP9X stabilizes MARCH7 by deubiquitylation in a compartment-specific manner, and RNAi depletion of USP9X reduces MARCH7 levels.\",\n      \"method\": \"Co-immunoprecipitation, RNAi knockdown, overexpression, subcellular fractionation\",\n      \"journal\": \"Traffic (Copenhagen, Denmark)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, RNAi depletion with rescue, subcellular compartment specificity defined, single lab\",\n      \"pmids\": [\"18410486\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"USP9X interacts with Bcl10 of the CBM (Carma1-Bcl10-Malt1) complex and removes TCR-induced ubiquitin chains from Bcl10, facilitating association of Carma1 with Bcl10-Malt1 and enabling NF-κB activation. Knockdown of USP9X attenuates T-cell proliferation and NF-κB activation upon TCR signaling.\",\n      \"method\": \"Co-immunoprecipitation, RNAi knockdown in human T-cell line and mouse primary T cells, adoptive transfer immunization\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — interaction with Bcl10 demonstrated, ubiquitin removal shown, in vivo adoptive transfer confirms pathway role, multiple experimental systems\",\n      \"pmids\": [\"23690623\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"USP9X removes inhibitory monoubiquitination from ZAP70 in T lymphocytes upon TCR-dependent phosphorylation, which enhances USP9X catalytic activity. Absence of USP9X increases ZAP70 localization to early endosomes. In B lymphocytes, USP9X is required for BCR-dependent PKCβ kinase activity and CARMA1/Bcl-10/MALT-1 complex formation.\",\n      \"method\": \"Usp9X knockout mouse, co-immunoprecipitation, ubiquitination assay, endosome localization, kinase activity assay\",\n      \"journal\": \"Journal of immunology (Baltimore, Md. : 1950)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — knockout mouse, mechanistic detail of TCR-dependent phosphorylation activating USP9X, substrate (ZAP70) ubiquitination and endosomal sorting defined\",\n      \"pmids\": [\"26936881\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"USP9X deubiquitylates Angiomotin at lysine 496, stabilizing it and reducing YAP/TAZ activity as part of Hippo pathway regulation.\",\n      \"method\": \"Co-immunoprecipitation, deubiquitination assay, identification of specific ubiquitination site (K496), RNAi knockdown\",\n      \"journal\": \"Cell discovery\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — site-specific deubiquitination demonstrated, functional YAP/TAZ readout, single lab\",\n      \"pmids\": [\"27462448\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"USP9X is physically associated with centriolar satellite protein CEP131 and stabilizes it through its deubiquitinase activity. USP9X is an integral component of the centrosome required for centrosome biogenesis; loss-of-function impairs centrosome duplication.\",\n      \"method\": \"Co-immunoprecipitation, deubiquitinase activity assay, centrosome localization by microscopy, loss-of-function centrosome duplication assay\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, deubiquitinase activity assay, centrosome functional assay, single lab multiple methods\",\n      \"pmids\": [\"28361952\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"USP9X is physically associated and spatially co-localized with centrosomal proteins PCM1 and CEP55, promoting their stabilization through its catalytic activity. USP9X centrosome localization depends on PCM1 and CEP55.\",\n      \"method\": \"Tandem mass tag labeling proteomics, co-immunoprecipitation, co-localization microscopy, deubiquitinase activity assay, RNAi knockdown\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — quantitative proteomics, co-IP, functional centrosome localization dependency, single lab\",\n      \"pmids\": [\"28620049\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"USP9X interacts with and deubiquitinates ankyrin-G (ANK3); USP9X phosphorylation enhances their interaction and decreases ankyrin-G polyubiquitination, stabilizing ankyrin-G to maintain dendritic spine development. In forebrain-specific Usp9X knockout mice, ankyrin-G and multiple ANKRD-containing proteins are transiently reduced at 2 weeks; reduced cortical spine density persists into adulthood.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, forebrain-specific conditional KO, dendritic spine density measurement, phosphorylation analysis\",\n      \"journal\": \"Neuron\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional KO mouse, phospho-regulation of interaction identified, ubiquitination and spine density phenotype, multiple orthogonal methods\",\n      \"pmids\": [\"31813652\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"USP9X deubiquitylates DVL2 (Dishevelled 2) by removing ubiquitin to promote canonical WNT activation; increased DVL2 ubiquitylation (by WWP1 E3 ligase) is associated with DVL2 localization to actin-rich projections and activation of the WNT-PCP pathway. A WWP1-USP9X ubiquitin rheostat on DVL2 specifies pathway choice.\",\n      \"method\": \"Co-immunoprecipitation, deubiquitination assay, WNT reporter assays, PCP pathway assays, RNAi knockdown\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — deubiquitination assay, pathway specification by ubiquitin state, interaction with E3 ligase WWP1 defined, multiple functional assays\",\n      \"pmids\": [\"31340145\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"USP9X co-immunoprecipitates with mTOR along with Raptor and Rictor, components of mTORC1 and mTORC2. Knockdown of USP9X increases mTORC1 activity upon growth factor stimulation and increases mTORC2 activity upon differentiation initiation, accelerating C2C12 myoblast differentiation.\",\n      \"method\": \"Co-immunoprecipitation, RNAi knockdown, mTOR kinase activity assay, myoblast differentiation assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-IP of USP9X with both mTOR complexes, functional differentiation phenotype, but deubiquitination substrate not identified in this study\",\n      \"pmids\": [\"22544753\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"USP9X deubiquitylating activity stabilizes RAPTOR protein (mTORC1 scaffold). RAPTOR physically associates with USP9X in embryonic brains; RAPTOR protein level is directly proportional to USP9X in both gain- and loss-of-function experiments; USP9X deubiquitylating activity opposes proteasomal degradation of RAPTOR. Loss of Usp9x causes reduced mTORC1 signaling and neural progenitor arrest in G0.\",\n      \"method\": \"Co-immunoprecipitation from embryonic brain, gain/loss-of-function in cultured cells and neurospheres, mTORC1 signaling assay, EdU proliferation assay\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP from embryonic brain, proportionality in both gain/loss-of-function, functional mTORC1 and proliferation phenotype, single lab\",\n      \"pmids\": [\"28341829\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"USP9X interacts with and deubiquitinates CLASPIN in an S-phase-specific manner, stabilizing it during DNA replication. USP9X depletion impairs DNA replication fork progression (similar to CLASPIN depletion), causes excessive endogenous DNA damage, and compromises CHK1 activation in response to replication stress. Restoration of CLASPIN in USP9X-depleted cells partially suppresses DNA damage accumulation.\",\n      \"method\": \"Quantitative proteomics, co-immunoprecipitation, RNAi knockdown, DNA fiber assay, CHK1 activation assay, rescue experiment\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — proteomics-identified interaction, DNA fiber assay, S-phase-specific regulation, rescue experiment, single lab multiple methods\",\n      \"pmids\": [\"26921344\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"USP9X interacts with PRICKLE proteins through their carboxy-termini and deubiquitinates PRICKLE, protecting it from proteasomal degradation. USP9X deficiency in mouse forebrain neurons reduces Prickle2 protein. Genetic reduction of fat facets (USP9X Drosophila orthologue) or treatment with WP1130 suppresses prickle-mediated seizures, placing USP9X in the Prickle seizure-suppression pathway.\",\n      \"method\": \"Interactome definition, co-immunoprecipitation, deubiquitination assay, forebrain Usp9x conditional KO (Prickle2 levels), Drosophila genetic epistasis, pharmacological WP1130 treatment\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — co-IP + deubiquitination assay + genetic epistasis in Drosophila + mouse KO, multiple model organisms\",\n      \"pmids\": [\"25763846\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Ets-1 transcription factor is deubiquitinated and stabilized by Usp9x, preventing its proteasomal destruction. Usp9x knockdown or inhibition reduces Ets-1 levels, decreasing NRAS expression and suppressing melanoma tumorigenicity.\",\n      \"method\": \"Co-immunoprecipitation, deubiquitination assay, RNAi knockdown, in vitro and in vivo tumor assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, deubiquitination assay, in vivo tumor data, single lab\",\n      \"pmids\": [\"28198367\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"USP9X interacts with TRB3 (pseudokinase) serving as scaffold for USP9X. USP9X deubiquitinates and stabilizes TRB3, and also deubiquitinates and activates Mind Bomb 1 (E3 ligase for JAG1 ubiquitination-mediated endocytosis), thereby activating Notch signaling in the signal-sending cell under cellular stress.\",\n      \"method\": \"Co-immunoprecipitation, deubiquitination assay, RNAi knockdown, Notch reporter assay\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP and deubiquitination assay for two substrates (TRB3, MIB1), Notch activation readout, single lab\",\n      \"pmids\": [\"27593927\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"USP9X binds and deubiquitinates β-catenin, removing Lys48-linked polyubiquitin chains to prevent proteasomal degradation, thereby activating Wnt/β-catenin signaling and promoting glioma cell proliferation.\",\n      \"method\": \"Co-immunoprecipitation, deubiquitination assay, RNAi knockdown, cell cycle analysis, in vivo xenograft\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, ubiquitin chain-type specificity defined, in vivo xenograft, single lab\",\n      \"pmids\": [\"27783990\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"USP9X interacts with BCL9 and removes Lys63-linked polyubiquitin from Lys-212 of BCL9. This deubiquitination facilitates formation of the β-catenin-BCL9-PYGO complex, potentiating transcriptional activation of Wnt/β-catenin target genes.\",\n      \"method\": \"nano-HPLC-MS/MS, co-immunoprecipitation, deubiquitination assay, ubiquitination site mapping, chromatin immunoprecipitation, Wnt reporter assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — MS-identified site-specific deubiquitination, functional Wnt reporter assay, single lab\",\n      \"pmids\": [\"31073027\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"USP9X stabilizes PBX1 by attenuating its Lys48-linked polyubiquitination. Co-immunoprecipitation confirmed USP9X-PBX1 interaction. USP9X inhibition induces PBX1 degradation and promotes prostate cancer cell apoptosis.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, RNAi knockdown, pharmacological inhibition, apoptosis assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, ubiquitin chain type identified, functional apoptosis phenotype, single lab\",\n      \"pmids\": [\"30718275\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"USP9X deubiquitinates and stabilizes TTK (dual specificity protein kinase) via removal of K48-linked ubiquitin chains, through direct interaction. USP9X knockdown reduces TTK protein levels and inhibits NSCLC cell proliferation, migration and tumorigenesis.\",\n      \"method\": \"Chemical labeling quantitative proteomics, co-immunoprecipitation, deubiquitination assay, ubiquitin chain-type analysis, in vitro and in vivo tumor assays\",\n      \"journal\": \"Theranostics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — quantitative proteomics substrate identification, K48 chain specificity defined, in vivo xenograft, single lab\",\n      \"pmids\": [\"29721084\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"USP9X removes Lys63-linked ubiquitin from RICTOR (mTORC2 scaffold), promoting RICTOR interaction with mTOR and facilitating mTORC2 assembly and activity. This process is stimulated by growth factors.\",\n      \"method\": \"Co-immunoprecipitation, deubiquitination assay, ubiquitin chain-type analysis, mTORC2 kinase activity assay, human cell lines and mice\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — chain-type specificity defined, validated in both cell lines and mice, mTORC2 assembly directly measured, growth factor regulation shown\",\n      \"pmids\": [\"33378666\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"CDC14B phosphatase antagonizes CDK1-mediated phosphorylation of USP9X at serine 2563. Serine 2563 phosphorylation of USP9X is essential for its mitotic activity: phospho-USP9X deubiquitylates and stabilizes WT1 (Wilms' tumor protein) during mitosis, and WT1 acts as a mitotic transcription factor driving CXCL8/IL-8 expression to promote mitotic survival.\",\n      \"method\": \"Unbiased proteome-wide phosphorylation screening, in vitro phosphorylation assay, co-immunoprecipitation, deubiquitination assay, reporter gene assay\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — proteome-wide unbiased approach, CDK1/CDC14B phosphorylation mechanism defined, deubiquitination assay, transcriptional reporter, multiple orthogonal methods\",\n      \"pmids\": [\"32152317\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"USP9X interacts with and stabilizes Makorin 2 and ZNF598 (ubiquitin E3 ligases of the ribosomal quality control pathway). Chemical inhibition or depletion of USP9X reduces levels of Makorins and ZNF598, impairing the ribosomal quality control/stalling pathway.\",\n      \"method\": \"Small-molecule USP9X inhibitor, proteomics analysis, co-immunoprecipitation, ribosomal stalling assays\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — specific small-molecule inhibitor validated, proteomics, functional ribosomal quality control assay, single lab multiple methods\",\n      \"pmids\": [\"33507233\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"USP9X interacts with and deubiquitinates eIF4A1 at Lys-369, preventing its ubiquitin-mediated degradation. USP9X dysfunction increases eIF4A1 ubiquitination and degradation, impairing cap-dependent translation initiation and reducing protein synthesis of pro-oncogenic mRNAs such as c-Myc and XIAP.\",\n      \"method\": \"Tandem affinity purification, co-immunoprecipitation, ubiquitination site mapping, nascent protein synthesis assay, cap-dependent translation assay\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — TAP identification, site-specific ubiquitination mapped, functional translation initiation assay, single lab multiple methods\",\n      \"pmids\": [\"29228324\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"USP9X interacts with and deubiquitinates BMAL1 (core circadian clock protein), reducing its ubiquitination, enhancing its stability and protein level, and increasing its transcriptional activity. USP9X knockdown decreases the amplitude of cellular circadian rhythm without affecting period or phase.\",\n      \"method\": \"Affinity purification, mass spectrometry, co-immunoprecipitation, deubiquitination assay, bioluminescence circadian rhythm measurement\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — MS-identified interaction, deubiquitination assay, functional circadian rhythm readout, single lab\",\n      \"pmids\": [\"29626158\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"USP9X is methylated at arginine residues, enabling its interaction with the Tudor domain of TDRD3. This interaction is mediated through the Tudor domain of TDRD3 and arginine methylation of USP9X. USP9X depletion increases TDRD3 ubiquitination; TDRD3 is essential for USP9X stress granule localization.\",\n      \"method\": \"GST pulldown, co-immunoprecipitation, arginine methylation identification, RNAi knockdown, stress granule localization by microscopy, Tdrd3-null MEFs\",\n      \"journal\": \"Cell discovery\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — arginine methylation as PTM identified, domain-specific interaction mapped, stress granule localization in null MEFs, single lab\",\n      \"pmids\": [\"28101374\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"TGF-β activates ERK which phosphorylates SMAD4 at Thr277, facilitating SMAD4-USP9X interaction. USP9X inhibits TIF1γ from binding and monoubiquitinating SMAD4, thereby maintaining SMAD4 nuclear retention and TGF-β/SMAD3-mediated transcription of Twist and Snail, promoting breast cancer metastasis.\",\n      \"method\": \"Co-immunoprecipitation, phospho-SMAD4 mutant analysis, chromatin retention assay, luciferase reporter, RNAi knockdown\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — phospho-dependent interaction mapped (Thr277), functional TGF-β transcription readout, single lab\",\n      \"pmids\": [\"28115363\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"USP9X (DFFRX) interacts with Doublecortin (DCX) through a novel recognition domain outside USP9X's catalytic site. No ubiquitinated forms of DCX were detected, suggesting this interaction is non-catalytic. USP9X associates with microtubules at specific subcellular compartments enriched in DCX.\",\n      \"method\": \"Targeted mutagenesis, co-localization, co-immunoprecipitation, ubiquitination detection (negative result for DCX)\",\n      \"journal\": \"Molecular and cellular neurosciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, mutagenesis mapping of novel interaction domain, microtubule co-localization, single lab\",\n      \"pmids\": [\"15607950\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"NPHP5 (nephrocystin-5) directly binds USP9X. In G0/G1/S phase, a pool of cytoplasmic USP9X is recruited to the centrosome by NPHP5, protecting NPHP5 from ubiquitination and favouring cilia assembly. In G2/M, USP9X dissociates from the centrosome, allowing BBS11 to K63-ubiquitinate NPHP5, triggering delocalization and cilia loss.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay (K48/K63 typing), cell cycle synchronization, cilia assembly assay, RNAi knockdown\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — cell cycle-dependent subcellular redistribution with functional consequence, ubiquitin chain typing, ciliogenesis assay, single lab multiple methods\",\n      \"pmids\": [\"28498859\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"USP9X binds PCM1 and antagonizes MIB1-mediated PCM1 ubiquitylation, protecting PCM1 from proteasomal degradation. Knockdown of USP9X reduces PCM1 protein levels and disrupts centriolar satellite integrity, causing satellite proteins such as CEP290 to relocalize to centrosomes.\",\n      \"method\": \"Co-immunoprecipitation, deubiquitylation assay, RNAi knockdown, centriolar satellite microscopy, epistasis (MIB1 knockdown rescues PCM1 levels)\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — deubiquitination assay, genetic epistasis with MIB1, functional centriolar satellite phenotype, single lab\",\n      \"pmids\": [\"30584065\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"SNX17 recruits USP9X to antagonize MIB1-induced ubiquitination and degradation of PCM1 during serum-starvation-induced ciliogenesis. SNX17 deficiency leads to enhanced degradation of both USP9X and PCM1 and disrupts ciliogenesis.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, ciliogenesis assay, SNX17 knockdown, RNAi\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, functional ciliogenesis phenotype, USP9X stability regulated by SNX17, single lab\",\n      \"pmids\": [\"31671755\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"USP9X deubiquitinates and stabilizes PTGES (prostaglandin E synthase) by physically interacting with it and preventing proteasome-directed degradation, thereby promoting PGE2 synthesis and metastatic features of NSCLC.\",\n      \"method\": \"Co-immunoprecipitation, deubiquitination assay, RNAi knockdown, in vivo metastasis model\",\n      \"journal\": \"American journal of cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, deubiquitination assay, in vivo metastasis data, single lab\",\n      \"pmids\": [\"31285948\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"USP9X deubiquitinates and stabilizes BRCA1. Reciprocal co-IP confirms USP9X-BRCA1 interaction. Depletion of USP9X reduces BRCA1 abundance, shortens its half-life, increases its ubiquitination, reduces HR efficiency, and sensitizes cells to PARP inhibitors and MMS. Catalytically dead USP9X (C1566S) does not upregulate BRCA1.\",\n      \"method\": \"Reciprocal co-immunoprecipitation, RNAi knockdown, overexpression of WT vs. C1566S mutant, HR assay, drug sensitivity assay\",\n      \"journal\": \"Cancer medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — catalytic mutant confirms enzymatic requirement, reciprocal co-IP, HR functional assay, single lab\",\n      \"pmids\": [\"31512408\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"USP9X removes K63-linked polyubiquitin from SR-A1 (class A1 scavenger receptor) at the K27 site, reducing SR-A1 cell surface internalization after ox-LDL binding. K27R mutation of SR-A1 attenuates USP9X knockdown-induced ox-LDL uptake, establishing USP9X as a regulator of SR-A1 ubiquitination and macrophage foam cell formation.\",\n      \"method\": \"Loss-of-function screening, co-immunoprecipitation, site-specific mutagenesis (K27R), ubiquitin chain type analysis, macrophage foam cell assay, macrophage-specific KO mouse\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — site-specific mutagenesis, chain-type defined, macrophage-specific KO mouse in vivo, multiple orthogonal methods\",\n      \"pmids\": [\"35389885\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"USP9X deubiquitinates and stabilizes Snail1, promoting its function in epithelial-mesenchymal transition in TNBC. Depletion of USP9X downregulates Snail1, inhibits migration/invasion, and increases sensitivity to cisplatin and paclitaxel; reconstitution of Snail1 in USP9X-depleted cells partially reverses these effects.\",\n      \"method\": \"Co-immunoprecipitation, deubiquitination assay, RNAi knockdown, Snail1 rescue experiment, in vitro and in vivo metastasis assays\",\n      \"journal\": \"Journal of cellular physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, deubiquitination assay, rescue experiment confirms pathway placement, single lab\",\n      \"pmids\": [\"35506169\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"USP9X deubiquitinates NLRP3, preventing its ubiquitination and stabilizing NLRP3 protein (not mRNA). USP9X knockdown increases NLRP3 ubiquitination and reduces NLRP3 inflammasome activation and pyroptosis in alveolar epithelial cells; NLRP3 overexpression rescues these effects.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, RNAi knockdown, overexpression rescue, pyroptosis assay\",\n      \"journal\": \"Cell biology international\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-IP and ubiquitination shown, rescue experiment confirms pathway placement, single lab\",\n      \"pmids\": [\"36525374\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"USP9X deubiquitinates and stabilizes NRP1 (neuropilin-1), with USP9X-mediated NRP1 deubiquitination enhancing hepatic stellate cell (HSC) activation and liver fibrosis. Identified by co-immunoprecipitation and GST pulldown with in vivo and in vitro ubiquitination assays.\",\n      \"method\": \"Co-immunoprecipitation, GST pulldown, in vivo and in vitro ubiquitination assay, immunohistochemistry, RNAi knockdown\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, GST pulldown, in vivo ubiquitination assay, functional HSC activation phenotype, single lab\",\n      \"pmids\": [\"36653359\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"USP9X deubiquitinates Cx43 (connexin 43) by directly binding to Cx43's C-terminal Tyr286, preventing its degradation. USP9X overexpression suppresses high glucose-induced EMT in NRK-52E cells in a deubiquitinase activity-dependent manner (catalytically inactive C1556S mutant has no effect).\",\n      \"method\": \"CRISPR/Cas9 SAM overexpression, RNAi knockdown, co-immunoprecipitation, ubiquitination assay, catalytic mutant (C1556S), EMT marker quantification\",\n      \"journal\": \"Biochemical pharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — binding site mapped to Tyr286, catalytic mutant control, functional EMT readout, single lab\",\n      \"pmids\": [\"33857489\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"USP9X deubiquitinates Nrf2, reducing its ubiquitination level and promoting Nrf2-ARE pathway activation, thereby limiting ROS production and extracellular matrix accumulation in diabetic renal fibrosis conditions. Catalytically inactive USP9X-C1556S fails to stabilize Nrf2.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, catalytic mutant (C1556S), Nrf2-ARE reporter assay, ROS measurement, RNAi knockdown\",\n      \"journal\": \"Experimental cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — catalytic mutant confirmation, Nrf2 ubiquitination reduced, functional ARE reporter, single lab\",\n      \"pmids\": [\"32442538\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"USP9X stabilizes ZBTB38 (methyl-CpG-binding protein) by interacting with it and deubiquitinating it. USP9X itself is stabilized by oxidative stress. Both USP9X and ZBTB38 are required to limit basal ROS generation and toxicity of acute oxidative stress.\",\n      \"method\": \"Co-immunoprecipitation, deubiquitination assay, RNAi knockdown, ROS measurement, protein stability assay\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP and deubiquitination assay, functional ROS phenotype, single lab\",\n      \"pmids\": [\"29490077\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"USP9X is required for spermatogenesis: germ cell-specific conditional deletion of Usp9x results in apoptotic cell death at the early spermatocyte stage and subsequent aberrant spermiogenesis, establishing a critical role for USP9X in the mitosis-to-meiosis transition in male germ cells.\",\n      \"method\": \"Vasa-Cre conditional Usp9x knockout mouse, histology, apoptosis detection\",\n      \"journal\": \"Reproduction (Cambridge, England)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional KO mouse with defined developmental phenotype, single lab\",\n      \"pmids\": [\"28559472\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"USP9X is a substrate-specific deubiquitinase that removes diverse ubiquitin chain types (K48, K63, K29/K33, monoubiquitin) from a broad range of substrates—including MCL1, FBW7, LATS1/2, CLASPIN, RAPTOR, RICTOR, ankyrin-G, DVL2, α-synuclein, ASK1, ITCH, SMURF1, CEP131/PCM1, BRCA1, eIF4A1, ZAP70, Bcl10, PRICKLE, and many others—to control their protein stability and thereby regulate cell survival, apoptosis, Hippo/Wnt/Notch/TGF-β/mTOR signaling, neuronal development and migration, centrosome biogenesis, ciliogenesis, DNA replication checkpoint, ribosomal quality control, T/B cell activation, and circadian rhythm; its activity is itself regulated by post-translational modifications including CDK1-mediated phosphorylation at S2563 (activating) and S-nitrosylation, and by interaction partners such as SNX17 and TDRD3.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"USP9X is a substrate-specific deubiquitinase that opposes ubiquitin-dependent proteasomal degradation of a broad set of regulatory proteins, thereby controlling cell survival, signaling, and cytoskeletal and developmental programs [#0, #7]. Its prototypical mode of action is removal of degradative polyubiquitin chains from short-lived substrates to extend their half-life: it stabilizes the anti-apoptotic protein MCL1 by cleaving Lys48-linked chains to promote cell survival [#0], and analogously stabilizes the tumor-suppressor F-box protein FBW7 upstream of c-Myc [#7], the DNA-replication checkpoint factor CLASPIN to sustain fork progression and CHK1 activation [#30], BRCA1 to support homologous recombination [#50], and the translation-initiation factor eIF4A1 to maintain cap-dependent synthesis of pro-oncogenic mRNAs [#41]. A recurring theme is the stabilization of HECT- and RING-family E3 ligases and of other ubiquitin-pathway enzymes\\u2014ITCH, SMURF1, and MARCH7\\u2014by antagonizing their auto-ubiquitination [#5, #6, #20]. Through these substrates USP9X tunes multiple developmental signaling pathways: it stabilizes LATS1/2 and Angiomotin to restrain YAP/TAZ in the Hippo pathway [#12, #23], acts as a WWP1-antagonizing rheostat on DVL2 and deubiquitinates BCL9 and \\u03b2-catenin to direct Wnt signaling [#27, #34, #35], activates Notch via MIB1 [#10, #33], and supports TGF-\\u03b2/SMAD4 nuclear retention [#44]. It assembles and activates mTORC1 and mTORC2 by stabilizing RAPTOR and deubiquitinating RICTOR [#29, #38]. USP9X is also an integral centrosomal and centriolar-satellite component that protects CEP131, PCM1, and NPHP5 to support centrosome biogenesis and cell-cycle\\u2013coupled ciliogenesis [#24, #46, #47], and is required in neurons for axon growth, migration, and dendritic spine maintenance, partly through stabilization of ankyrin-G [#16, #17, #26]; loss-of-function human variants that fail to rescue axonal defects link USP9X to intellectual disability [#16]. Its catalytic output is gated by post-translational modification, including CDK1-dependent phosphorylation at Ser2563 (antagonized by CDC14B) that licenses mitotic deubiquitination of WT1 [#39], S-nitrosylation that enables MIB1 stabilization and NOTCH1 signaling [#10], TCR-dependent phosphorylation that enhances activity toward ZAP70 [#22], and arginine methylation that recruits TDRD3 to direct stress-granule localization [#43].\",\n  \"teleology\": [\n    {\n      \"year\": 2006,\n      \"claim\": \"Established that USP9X protects E3 ubiquitin ligases from auto-ubiquitination, revealing a recurring strategy of stabilizing ubiquitin-pathway enzymes rather than only their downstream targets.\",\n      \"evidence\": \"GST pulldown, reciprocal co-IP, and RNAi rescue with proteasome inhibitor showing FAM/USP9X binds ITCH WW domains and reverses its auto-ubiquitination\",\n      \"pmids\": [\"17038327\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Chain topology removed from ITCH not defined\", \"Catalytic-dead controls not used in this study\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Showed USP9X removes atypical Lys29/Lys33 chains and that these non-degradative chains regulate kinase activity, broadening USP9X chain specificity beyond canonical degradation signals.\",\n      \"evidence\": \"In vitro deubiquitinase assay, chain topology analysis, and mutagenesis on NUAK1 and MARK4\",\n      \"pmids\": [\"18254724\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct demonstration that polyubiquitination inhibits T-loop phosphorylation remains inferential\", \"In vivo relevance not established\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Identified USP9X as a stabilizer of the anti-apoptotic protein MCL1 via Lys48-chain removal, defining its central pro-survival role and oncogenic relevance.\",\n      \"evidence\": \"Co-IP, ubiquitination assays, and RNAi knockdown with survival readouts in cancer cells\",\n      \"pmids\": [\"20023629\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of MCL1 recognition not resolved\", \"Regulation of the USP9X-MCL1 interaction not addressed here\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Demonstrated USP9X stabilizes activated ASK1 to sustain oxidative-stress JNK signaling, extending its survival/death control into stress kinase pathways via a ubiquitin-like recognition motif.\",\n      \"evidence\": \"Co-IP, binding-domain mutagenesis of the ASK1 LRLRGG sequence, and JNK/cell-death assays in USP9X-deficient cells\",\n      \"pmids\": [\"20005844\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Chain type removed from ASK1 not defined\", \"Whether the GG motif is a general USP9X docking site untested\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Linked USP9X to neurodegeneration-relevant proteostasis by showing it removes SIAH-added monoubiquitin from \\u03b1-synuclein and routes it toward autophagy versus proteasome.\",\n      \"evidence\": \"Deubiquitinase assays, RNAi/overexpression, and cell fractionation distinguishing degradation routes\",\n      \"pmids\": [\"22065755\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo brain relevance not tested\", \"Mechanism of degradation-route selection unresolved\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Defined USP9X as a regulator of neural development, showing conditional loss disrupts cortical organization and axonogenesis partly through impaired TGF-\\u03b2 signaling.\",\n      \"evidence\": \"Nestin-cre and Emx1-cre conditional knockouts with in vivo/in vitro axon-length and TGF-\\u03b2 analyses\",\n      \"pmids\": [\"23861879\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct deubiquitination substrate driving axon phenotype not identified\", \"TGF-\\u03b2 linkage correlative\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Placed USP9X in adaptive immunity by showing it deubiquitinates Bcl10 to enable CBM-complex assembly and NF-\\u03baB activation downstream of the TCR.\",\n      \"evidence\": \"Co-IP, RNAi in T-cell lines and primary T cells, and adoptive-transfer immunization\",\n      \"pmids\": [\"23690623\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Chain type on Bcl10 not fully defined\", \"Direct vs scaffold role within CBM not separated\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Provided causal disease evidence by demonstrating that intellectual-disability\\u2013associated USP9X variants fail to rescue axon growth and growth-cone localization in Usp9x-null neurons.\",\n      \"evidence\": \"Usp9x knockout mouse with human wild-type and variant rescue, axon/migration assays, and proteomics of null neurons\",\n      \"pmids\": [\"24607389\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular substrate underlying growth-cone defect not pinpointed\", \"Genotype-phenotype mechanism for each variant incomplete\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Revealed substrate-directed, signal-activated catalysis by showing TCR phosphorylation enhances USP9X activity toward ZAP70 and that USP9X controls B-cell receptor signaling.\",\n      \"evidence\": \"Usp9X knockout mouse, ubiquitination and kinase-activity assays, and endosomal localization analysis\",\n      \"pmids\": [\"26936881\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Kinase phosphorylating USP9X not identified here\", \"ZAP70 ubiquitination site not mapped\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Consolidated USP9X as a Hippo-pathway regulator by demonstrating it stabilizes LATS1/2 and Angiomotin to restrain YAP/TAZ-driven oncogenesis and EMT.\",\n      \"evidence\": \"Co-IP, gel filtration, MEF knockout, site-specific deubiquitination (AMOT K496), and YAP/TAZ reporter/soft-agar assays\",\n      \"pmids\": [\"28720576\", \"29183995\", \"27462448\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether USP9X acts on multiple Hippo nodes simultaneously in vivo unclear\", \"Some node studies single-lab\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Established USP9X as an integral centrosome and centriolar-satellite component that stabilizes CEP131, PCM1, CEP55, and NPHP5 to control centrosome biogenesis and cell-cycle\\u2013coupled ciliogenesis.\",\n      \"evidence\": \"Co-IP, deubiquitinase assays, centrosome localization microscopy, cell-cycle synchronization, and MIB1-epistasis ciliogenesis assays\",\n      \"pmids\": [\"28361952\", \"28620049\", \"28498859\", \"30584065\", \"31671755\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Recruitment hierarchy among satellite partners incompletely ordered\", \"Some interactions (CEP55, SNX17) Medium-confidence single-lab\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Demonstrated tumor-suppressive control of FBW7 and downstream c-Myc in vivo, showing USP9X stabilizes an E3 ligase to restrain proliferation and tumorigenesis.\",\n      \"evidence\": \"Conditional gut knockout, proteomics, organoids, and genetic epistasis with c-Myc heterozygosity\",\n      \"pmids\": [\"29346117\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Chain type removed from FBW7 not defined\", \"Tissue specificity of the FBW7-c-Myc axis untested elsewhere\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Defined USP9X as a Wnt-pathway rheostat by showing it antagonizes WWP1 on DVL2 and deubiquitinates BCL9 to specify canonical versus PCP outcomes and potentiate \\u03b2-catenin transcription.\",\n      \"evidence\": \"Deubiquitination assays, WNT/PCP reporters, site-specific ubiquitination mapping (BCL9 K212), and ChIP\",\n      \"pmids\": [\"31340145\", \"31073027\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Quantitative rules of the WWP1-USP9X balance unresolved\", \"BCL9 study Medium-confidence single-lab\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Connected USP9X to neuronal cytoskeletal scaffolding by showing phosphorylation-enhanced deubiquitination of ankyrin-G maintains dendritic spine density into adulthood.\",\n      \"evidence\": \"Forebrain-specific conditional knockout, ubiquitination assays, phosphorylation analysis, and spine-density measurement\",\n      \"pmids\": [\"31813652\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Kinase responsible for the activating phosphorylation not identified\", \"Transient versus persistent substrate effects not fully explained\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Defined the mitotic activation switch by showing CDK1 phosphorylates USP9X at Ser2563 (reversed by CDC14B) to license deubiquitination and stabilization of the mitotic transcription factor WT1.\",\n      \"evidence\": \"Proteome-wide phosphorylation screening, in vitro phosphorylation, deubiquitination assays, and CXCL8 reporter assay\",\n      \"pmids\": [\"32152317\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full substrate set gated by Ser2563 phosphorylation unknown\", \"Structural impact of the modification unresolved\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Showed USP9X assembles mTORC2 by removing Lys63 chains from RICTOR to promote mTOR association, complementing earlier RAPTOR/mTORC1 stabilization and placing USP9X in growth-factor mTOR control.\",\n      \"evidence\": \"Co-IP, chain-type analysis, mTORC2 kinase assays in cells and mice\",\n      \"pmids\": [\"33378666\", \"28341829\", \"22544753\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How USP9X coordinately balances mTORC1 vs mTORC2 unclear\", \"RAPTOR ubiquitination site not mapped\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identified S-nitrosylation as a redox-sensitive regulatory switch enabling USP9X to stabilize MIB1 and drive NOTCH1 signaling, with in vivo relevance to aortic valve disease.\",\n      \"evidence\": \"Unbiased S-nitrosylation proteomics, mouse knockout, scRNA-seq, and in vitro deubiquitination\",\n      \"pmids\": [\"33547080\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"S-nitrosylated residues not enumerated mechanistically\", \"Generality of redox gating across substrates untested\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Extended USP9X function to translational quality control by showing it stabilizes the RQC E3 ligases Makorin 2 and ZNF598 to sustain ribosomal stalling responses.\",\n      \"evidence\": \"Validated small-molecule USP9X inhibitor, proteomics, co-IP, and ribosomal-stalling assays\",\n      \"pmids\": [\"33507233\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct deubiquitination of these ligases versus indirect effects not fully separated\", \"Physiological RQC consequences in vivo untested\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Demonstrated in vivo metabolic-disease relevance by showing USP9X removes Lys63 chains from a defined site on scavenger receptor SR-A1 to limit ox-LDL uptake and foam-cell formation.\",\n      \"evidence\": \"Loss-of-function screen, site-specific K27R mutagenesis, chain typing, and macrophage-specific knockout mouse\",\n      \"pmids\": [\"35389885\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether SR-A1 regulation generalizes to other scavenger receptors unknown\", \"Upstream signal controlling this activity unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved how USP9X achieves substrate selectivity across its very broad substrate range and how its multiple regulatory modifications are integrated to direct activity toward specific substrates in a given context.\",\n      \"evidence\": \"No single study in the corpus reconstitutes substrate-selection rules or a unified regulatory logic\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structural model of substrate or chain-type recognition\", \"No systematic map linking each PTM (phosphorylation, S-nitrosylation, methylation) to specific substrate pools\", \"Adaptor-driven recruitment (e.g., SNX17, TDRD3, NPHP5) not generalized into a recruitment code\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 1, 5, 30, 38, 51]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [0, 5, 8, 50]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [5, 6, 20, 33, 40]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005815\", \"supporting_discovery_ids\": [24, 25, 46, 47]},\n      {\"term_id\": \"GO:0005929\", \"supporting_discovery_ids\": [46, 47, 48]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [20, 28, 29]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [16, 45]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [18, 22]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [12, 23, 27, 34, 35, 33, 44, 38]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [0, 4, 14, 36]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [21, 22, 53]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [24, 39, 46, 30]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [40, 41]},\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [30, 50]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [16, 17, 26, 58]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [2, 3]}\n    ],\n    \"complexes\": [\n      \"CARMA1-BCL10-MALT1 (CBM) complex\",\n      \"mTORC1\",\n      \"mTORC2\",\n      \"centrosome / centriolar satellites\"\n    ],\n    \"partners\": [\n      \"MCL1\",\n      \"FBW7\",\n      \"ITCH\",\n      \"SMURF1\",\n      \"MIB1\",\n      \"PCM1\",\n      \"CLASPIN\",\n      \"DVL2\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}