{"gene":"USP33","run_date":"2026-04-28T23:00:23","timeline":{"discoveries":[{"year":2009,"finding":"USP33 constitutively binds beta2-adrenergic receptor (β2AR) and dissociates immediately after agonist stimulation, then reassociates on prolonged agonist treatment; USP33 deubiquitinates β2AR to inhibit lysosomal trafficking and promote receptor recycling from late-endosomal compartments, thereby resensitizing receptors at the cell surface.","method":"Co-immunoprecipitation, ubiquitination assays, receptor trafficking/recycling assays in HEK293 cells, fluorescence microscopy","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP and functional trafficking assays with multiple readouts, replicated across related work","pmids":["19424180"],"is_preprint":false},{"year":2009,"finding":"USP33 binds beta-arrestin2 and deubiquitinates it, opposing Mdm2-mediated ubiquitination; this reciprocal regulation controls the stability of the receptor–beta-arrestin complex, subcellular localization of receptor signalosomes, and β2AR internalization. Class A receptors (e.g., β2AR) promote a beta-arrestin conformation that favors USP33 binding, whereas class B receptors (e.g., V2R) favor USP33 dissociation.","method":"Co-immunoprecipitation, in vivo ubiquitination assay, receptor internalization assay, siRNA knockdown, confocal microscopy","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP plus functional internalization assays with mechanistic epistasis","pmids":["19363159"],"is_preprint":false},{"year":2009,"finding":"USP33 binds Robo1 receptor and is required for Slit-induced redistribution of Robo1 from intracellular compartments to the plasma membrane, and for Slit-mediated inhibition of directional breast cancer cell migration.","method":"Co-immunoprecipitation, siRNA knockdown, cell migration assays, receptor localization by fluorescence microscopy","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — direct binding established by Co-IP, functional consequence shown by knockdown with defined migration phenotype","pmids":["19706539"],"is_preprint":false},{"year":2009,"finding":"USP33 is required for Slit-mediated axon guidance at the ventral midline; it interacts with Robo1 and is essential for commissural axon midline crossing in vertebrates.","method":"Co-immunoprecipitation, in vivo knockdown in chick/mouse neural tube, axon guidance assays","journal":"Nature neuroscience","confidence":"High","confidence_rationale":"Tier 2 — in vivo loss-of-function with specific axon guidance phenotype, Co-IP binding","pmids":["19684588"],"is_preprint":false},{"year":2007,"finding":"The ZnF UBP domain of USP33/VDU1 was solved by NMR spectroscopy; the structure contains three zinc ions (unlike the single Zn of USP5) and, unlike the USP5 ZnF UBP domain, does not bind ubiquitin.","method":"NMR spectroscopy, structural determination","journal":"Protein science","confidence":"High","confidence_rationale":"Tier 1 — NMR structure with functional binding characterization","pmids":["17766394"],"is_preprint":false},{"year":2013,"finding":"USP33 localizes to centrioles primarily in S and G2/M phases, interacts with CP110, and potently and specifically deubiquitinates CP110 (but not other cyclin-F substrates), thereby antagonizing SCF(cyclin F)-mediated ubiquitination and promoting supernumerary centriole generation; USP33 ablation destabilizes CP110 and inhibits centrosome amplification.","method":"Co-immunoprecipitation, in vivo and in vitro ubiquitination assays, centrosome duplication assays, siRNA knockdown, immunofluorescence localization","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1-2 — in vitro deubiquitination assay, reciprocal Co-IP, specific substrate validation, multiple orthogonal readouts","pmids":["23486064"],"is_preprint":false},{"year":2013,"finding":"Nutrient starvation induces USP33 accumulation and relocalization to RALB-positive vesicles, where USP33 deubiquitylates RALB at Lys47; deubiquitylated RALB preferentially interacts with EXO84 to drive autophagosome formation, while ubiquitylated RALB favors SEC5-TBK1 innate immune signaling.","method":"Co-immunoprecipitation, ubiquitination assays, site-directed mutagenesis (K47), autophagy assays, confocal microscopy","journal":"Nature cell biology","confidence":"High","confidence_rationale":"Tier 1-2 — site-specific mutagenesis identifying K47 as the regulatory ubiquitination site, multiple orthogonal assays","pmids":["24056301"],"is_preprint":false},{"year":2014,"finding":"USP33 is degraded via the ubiquitin-proteasome system; HERC2 (a HECT-domain E3 ligase) polyubiquitinates USP33, and p97 (with its Ufd1-Npl4 adaptor complex) is required for post-ubiquitination processing and degradation of USP33.","method":"Quantitative mass spectrometry, siRNA knockdown of p97/HERC2, chemical inhibition of p97, ubiquitination assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (MS, genetic knockdown, chemical inhibition) identifying E3 ligase and AAA-ATPase machinery","pmids":["24855649"],"is_preprint":false},{"year":2014,"finding":"USP33 deubiquitinates and stabilizes Robo1 in lung cancer cells, mediating Slit-Robo signaling to inhibit lung cancer cell migration.","method":"siRNA knockdown, Co-immunoprecipitation, ubiquitination assay, cell migration assay","journal":"Protein & cell","confidence":"Medium","confidence_rationale":"Tier 2-3 — Co-IP and functional migration assay, single lab","pmids":["24981056"],"is_preprint":false},{"year":2014,"finding":"USP33 deubiquitinates and stabilizes Robo1 in colorectal cancer cells, required for Slit2-mediated inhibition of CRC cell migration.","method":"Co-immunoprecipitation, ubiquitination assay, siRNA knockdown, cell migration assay","journal":"International journal of cancer","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP and functional migration assay, single lab","pmids":["25242263"],"is_preprint":false},{"year":2011,"finding":"USP33 exists as multiple splice variants with isoform-specific subcellular localization: all variants localize to ER-associated structures, while variant 3 additionally accumulates at the Golgi; two distinct inserts in the catalytic domain mediate ER association and membrane association respectively, and alternative splicing of eight amino acids in insert 2 enables Golgi targeting.","method":"GFP-tagged isoform expression, immunofluorescence microscopy, fractionation, deletion/splice variant analysis","journal":"Traffic","confidence":"High","confidence_rationale":"Tier 2 — direct localization with functional domain mapping and multiple isoform characterization","pmids":["21801292"],"is_preprint":false},{"year":2019,"finding":"USP33 localizes to the outer mitochondrial membrane, binds PRKN/parkin, and deubiquitinates PRKN in a DUB activity-dependent manner; USP33 preferentially removes K6, K11, K48, and K63-linked ubiquitin chains from PRKN, primarily at Lys435 (K63-linked chains); USP33 knockdown enhances both PRKN stabilization and its translocation to depolarized mitochondria, thereby increasing mitophagy.","method":"Co-immunoprecipitation, in vitro and cellular ubiquitination assays, site-directed mutagenesis (K435), mitophagy assays, mitochondrial fractionation","journal":"Autophagy","confidence":"High","confidence_rationale":"Tier 1-2 — in vitro deubiquitination, mutagenesis identifying K435 site, multiple linkage-specific assays","pmids":["31432739"],"is_preprint":false},{"year":2019,"finding":"USP33 interacts with DUSP1 phosphatase and inhibits its K48-linked polyubiquitination and proteasomal degradation; USP33 knockdown promotes DUSP1 degradation leading to enhanced JNK activation and docetaxel-induced apoptosis in prostate cancer cells.","method":"Co-immunoprecipitation, ubiquitination assays, siRNA knockdown/KO, JNK inhibitor rescue experiments","journal":"Cell death and differentiation","confidence":"High","confidence_rationale":"Tier 2 — Co-IP, specific ubiquitin linkage (K48) characterization, pharmacological epistasis with JNK inhibitor","pmids":["31857702"],"is_preprint":false},{"year":2017,"finding":"The E3 ligase β-TrCP interacts with USP33 (via WD40 motif of β-TrCP and the 201-400 aa region of USP33, independently of the classic β-TrCP binding motif) and mediates USP33 ubiquitination and proteasomal degradation.","method":"Co-immunoprecipitation, deletion mapping, ubiquitination assay, proteasome inhibitor treatment","journal":"Experimental cell research","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP with domain mapping, single lab","pmids":["28506875"],"is_preprint":false},{"year":2021,"finding":"USP33 deubiquitylates IRF9 to regulate its stability; SARS-CoV-2 Spike-induced exosomal miR-148a suppresses USP33 expression in human microglia, leading to decreased IRF9 levels and hyperactivation of pro-inflammatory TNFα, NF-κB, and IFN-β pathways.","method":"miRNA overexpression/knockdown, luciferase reporter assay, immunoblotting, in vivo ubiquitination assay","journal":"Frontiers in immunology","confidence":"Medium","confidence_rationale":"Tier 2-3 — ubiquitination assay linking USP33 to IRF9 stability, functional downstream readout","pmids":["33936086"],"is_preprint":false},{"year":2020,"finding":"USP33 deubiquitylates ATF3 to stabilize it; DENV-NS1-induced exosomal miR-148a suppresses USP33 in human microglia, reducing ATF3 stability and disinhibiting TNF-α, NF-κB, and IFN-β pro-inflammatory signaling.","method":"EV cargo analysis, miRNA mimic/anti-miR, dual luciferase reporter, in vivo ubiquitination assay, chase assay","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2-3 — in vivo ubiquitination assay showing USP33-dependent ATF3 stability, single lab","pmids":["32848034"],"is_preprint":false},{"year":2022,"finding":"USP33 is preferentially induced in glioma stem cells by hypoxia, interacts with HIF-2α, and deubiquitinates and stabilizes HIF-2α protein; ERK1/2 activation upon hypoxia promotes HIF-2α phosphorylation, enhancing its interaction with USP33. USP33 silencing disrupts glioma stem cell maintenance and reduces tumor vascularization.","method":"Co-immunoprecipitation, ubiquitination assay, ERK inhibitor experiments, siRNA knockdown, glioblastoma stem cell maintenance assays, in vivo tumor models","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 — Co-IP, ubiquitination assay, epistasis with ERK pathway, in vivo validation","pmids":["35191554"],"is_preprint":false},{"year":2022,"finding":"ERAP1 hepatokine interacts with β2 adrenergic receptor (ADRB2) and reduces its expression by decreasing USP33-mediated deubiquitination of ADRB2, thereby disrupting ADRB2-stimulated insulin signaling in skeletal muscle.","method":"Co-immunoprecipitation, ubiquitination assay, hepatic overexpression/knockdown in mice, insulin signaling assays","journal":"Diabetes","confidence":"Medium","confidence_rationale":"Tier 2-3 — Co-IP and ubiquitination assay in physiological context, in vivo mouse model","pmids":["35192681"],"is_preprint":false},{"year":2018,"finding":"USP33 deubiquitinates PPM1A (a Smad2/3 phosphatase); miR-3591-5p targets USP33 to reduce PPM1A stability, thereby activating TGF-β/Smad2/3 signaling and promoting radiation-induced EMT in lung cancer cells.","method":"Luciferase reporter assay (3'UTR), ubiquitination assay, ectopic expression rescue, Western blot","journal":"Cellular physiology and biochemistry","confidence":"Medium","confidence_rationale":"Tier 3 — functional rescue experiments link USP33 to PPM1A stability, single lab","pmids":["30308513"],"is_preprint":false},{"year":2023,"finding":"USP33 interacts with TGFBR2 (TGF-β receptor 2), deubiquitinates it, and prevents its lysosomal degradation, promoting TGFBR2 accumulation at the cell membrane and sustained TGF-β signaling; TGF-β target ZEB1 in turn transcriptionally activates USP33 forming a positive feedback loop.","method":"Mass spectrometry, luciferase complementation assay, Co-immunoprecipitation, ubiquitination assay, lysosome inhibition experiments","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2-3 — MS substrate screening, Co-IP, ubiquitination assay, single lab","pmids":["37322017"],"is_preprint":false},{"year":2020,"finding":"USP33 directly binds SP1 transcription factor and deubiquitinates it, stabilizing SP1 protein and upregulating c-Met expression, thereby promoting hepatocellular carcinoma invasion and metastasis.","method":"Co-immunoprecipitation, ubiquitination assay, RNA sequencing, luciferase reporter, in vivo metastasis model","journal":"Life sciences","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP and ubiquitination assay identifying SP1 as substrate, single lab","pmids":["32835698"],"is_preprint":false},{"year":2021,"finding":"USP33 interacts with and deubiquitinates c-Myc; circ_0057558 sponges miR-206 to increase USP33 expression, which stabilizes c-Myc and promotes prostate cancer cell proliferation.","method":"RNA pulldown, luciferase assay, Co-immunoprecipitation, ubiquitination assay","journal":"Frontiers in cell and developmental biology","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP and ubiquitination assay for c-Myc, single lab","pmids":["33718387"],"is_preprint":false},{"year":2023,"finding":"USP33 deubiquitinates JAK2 to activate JAK2/STAT3 signaling in cardiomyocytes; miR-206 targets USP33 to suppress this pathway and protect against LPS-induced inflammatory injury.","method":"Co-immunoprecipitation, ubiquitination assay, dual luciferase reporter, siRNA knockdown rescue experiments","journal":"Molecular and cellular biochemistry","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP and ubiquitination assay identifying JAK2 as substrate, single lab","pmids":["37256445"],"is_preprint":false},{"year":2023,"finding":"USP33 interacts with CTNNB1 (β-catenin) and deubiquitinates it, preventing its degradation and promoting pancreatic cancer cell proliferation and self-renewal.","method":"Co-immunoprecipitation, ubiquitination assay, sphere formation, colony formation assays","journal":"Cell biology international","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP and ubiquitination assay, single lab","pmids":["37076992"],"is_preprint":false},{"year":2023,"finding":"USP33 stabilizes PFKFB3 by suppressing its ubiquitin-mediated degradation, driving aerobic glycolysis and osteosarcoma cell growth.","method":"Co-immunoprecipitation, ubiquitination assay, glycolysis functional assays","journal":"American journal of cancer research","confidence":"Low","confidence_rationale":"Tier 3 + Weak — single lab, limited mechanistic detail on ubiquitination linkage","pmids":["37034227"],"is_preprint":false},{"year":2024,"finding":"USP33 removes K27- and K48-linked ubiquitin chains from CBX2 at K277; acetylation of CBX2 at K199 by acetyltransferase GCN5 enhances CBX2 interaction with USP33, promoting further deubiquitination and stabilization of CBX2 to drive ovarian cancer progression.","method":"Proteomics, ubiquitinomics, Co-immunoprecipitation, site-directed mutagenesis (K277, K199), ubiquitination assay","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 1-2 — proteomics/ubiquitinomics substrate screen, site-specific mutagenesis, cross-talk between acetylation and deubiquitination","pmids":["39256572"],"is_preprint":false},{"year":2024,"finding":"USP33 interacts with and deubiquitinates p53 to stabilize it under DNA damage conditions; USP33 depletion increases p53 ubiquitination and impairs DNA damage-induced cell cycle arrest and apoptosis; hepatocyte-specific USP33 knockout mice show enhanced sensitivity to DEN-induced hepatocarcinogenesis.","method":"Co-immunoprecipitation, in vivo ubiquitination assay, USP33 knockout mouse model, liver carcinogenesis assay","journal":"Cell proliferation","confidence":"High","confidence_rationale":"Tier 2 — Co-IP, ubiquitination assay, in vivo knockout mouse model with carcinogenesis phenotype","pmids":["39694539"],"is_preprint":false},{"year":2024,"finding":"USP33 interacts with TRAF3, deubiquitinates it, and upregulates its expression, activating the NF-κB pathway to promote apoptosis, oxidative stress, and inflammation in cerulein-induced acute pancreatitis.","method":"Co-immunoprecipitation, ubiquitination assay, siRNA knockdown, immunofluorescence, NF-κB pathway assays","journal":"Shock","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP and ubiquitination assay, single lab","pmids":["39637362"],"is_preprint":false},{"year":2024,"finding":"USP33 mediates cell migration in esophageal squamous cell carcinoma by binding, deubiquitinating, and stabilizing integrin α6; USP33 knockdown inhibits laminin-dependent adhesion, spreading, migration, and metastasis.","method":"Co-immunoprecipitation, deubiquitination assay, cell adhesion/migration/spreading assays, tail vein injection metastasis model","journal":"Journal of cancer research and clinical oncology","confidence":"Medium","confidence_rationale":"Tier 2-3 — Co-IP and deubiquitination assay with in vivo metastasis model, single lab","pmids":["39589547"],"is_preprint":false},{"year":2024,"finding":"USP33 stabilizes TRAF2 by deubiquitination, promoting pyroptosis of human pulmonary microvascular endothelial cells during hypoxia/reoxygenation-induced acute lung injury.","method":"Co-immunoprecipitation, ubiquitination assay, siRNA knockdown, pyroptosis markers assay","journal":"Histology and histopathology","confidence":"Low","confidence_rationale":"Tier 3 + Weak — single lab, limited mechanistic depth","pmids":["39506557"],"is_preprint":false},{"year":2024,"finding":"USP33 stabilizes CNR1 (cannabinoid receptor 1) via deubiquitination in oligodendrocyte precursor cells, activating AKT/mTOR signaling to promote OPC differentiation; 13-docosenamide upregulates this USP33-mediated CNR1 deubiquitination.","method":"Co-immunoprecipitation, ubiquitination assay, in vivo BCAS mouse model, AKT/mTOR signaling assays","journal":"Neuroscience bulletin","confidence":"Medium","confidence_rationale":"Tier 2-3 — Co-IP and ubiquitination assay with in vivo model, single lab","pmids":["40679549"],"is_preprint":false},{"year":2025,"finding":"CDK1 directly phosphorylates USP33, enhancing its deubiquitinase activity toward SIN1 (mTORC2 component); USP33 deubiquitinates and stabilizes SIN1 to activate the mTORC2-AKT pathway, driving chemoresistance in pancreatic cancer.","method":"Co-immunoprecipitation, ubiquitination assay, CDK1 kinase assay, genetic ablation of CDK1/USP33/SIN1, in vivo tumor models","journal":"Cell death & disease","confidence":"High","confidence_rationale":"Tier 2 — kinase assay identifying CDK1 as USP33 writer, Co-IP and ubiquitination assay for SIN1, in vivo validation","pmids":["40695806"],"is_preprint":false},{"year":2025,"finding":"USP33 deubiquitinates PAK1 to prevent its degradation; METTL3-mediated m6A modification of USP33 mRNA, read by IGF2BP3, stabilizes USP33 transcript and increases USP33 protein, promoting gemcitabine resistance in pancreatic cancer.","method":"Co-immunoprecipitation, MeRIP-qPCR, RIP assay, ubiquitination assay, xenograft model","journal":"Naunyn-Schmiedeberg's archives of pharmacology","confidence":"Medium","confidence_rationale":"Tier 2-3 — Co-IP and ubiquitination assay, epitranscriptomic regulation validated by MeRIP, single lab","pmids":["41108357"],"is_preprint":false},{"year":2025,"finding":"USP33 stabilizes TAP63 through K48-linked deubiquitination, triggering autophagy and ferroptosis in triple-negative breast cancer by disrupting mitochondrial function and redox balance.","method":"Co-immunoprecipitation, ubiquitin chain analysis (K48), ferroptosis/autophagy markers, in vivo xenograft","journal":"Cellular and molecular life sciences","confidence":"Medium","confidence_rationale":"Tier 2-3 — Co-IP and K48-specific ubiquitin assay, in vivo validation, single lab","pmids":["40801947"],"is_preprint":false},{"year":2025,"finding":"USP33 deubiquitinates c-Myc at K48-linked chains to stabilize it, enhancing c-Myc transcriptional activity and driving glycolytic reprogramming (upregulating LDHA, GLUT1, PKM2) in ovarian cancer.","method":"Co-immunoprecipitation, ubiquitination assay (K48-specific), c-Myc overexpression rescue, metabolic assays","journal":"Biochimica et biophysica acta. General subjects","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP and K48-specific ubiquitination assay, rescue experiments, single lab","pmids":["40532745"],"is_preprint":false},{"year":2025,"finding":"USP33 suppresses LATS1 ubiquitination to inhibit the Hippo-YAP pathway, thereby promoting ferritinophagy and ferroptosis in endometrial stromal cells; USP33 is also localized in autophagosomes and promotes ferritin degradation therein.","method":"Co-immunoprecipitation, ubiquitination assay, CHX chase assay, ROS/Fe2+/MDA measurements, immunofluorescence colocalization","journal":"Gynecological endocrinology","confidence":"Medium","confidence_rationale":"Tier 2-3 — Co-IP, CHX chase, ubiquitination assay, ferroptosis readouts, single lab","pmids":["41452077"],"is_preprint":false},{"year":2025,"finding":"USP33 deubiquitinates and stabilizes EPHB2, activating Wnt/β-catenin signaling to promote retinoblastoma cell proliferation, invasion, and stemness.","method":"Co-immunoprecipitation, ubiquitination assay, protein stability assay, xenograft mouse model","journal":"Applied biochemistry and biotechnology","confidence":"Low","confidence_rationale":"Tier 3 + Weak — single lab, single method for substrate identification","pmids":["40824480"],"is_preprint":false},{"year":2025,"finding":"The zf-UBP and DUSP2 auxiliary domains of USP33 are short linear motif (SLiM)-binding domains with binding profiles similar to those of USP20, explaining functional redundancy between the two DUBs; these domains mediate substrate targeting via SLiMs in intrinsically disordered regions.","method":"Proteomic-peptide phage display, peptide arrays, affinity measurements","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 — systematic proteomic phage display and affinity measurements, preprint","pmids":["bio_10.1101_2025.09.22.676098"],"is_preprint":true},{"year":2008,"finding":"USP33/VDU1 interacts with human selenium-binding protein-1 (hSP56) in a selenium-dependent manner, with full-length VDU1 specifically binding the selenium-replete form of hSP56; the two proteins co-localize in the perinuclear region of prostate cancer cells.","method":"Yeast two-hybrid, in vitro binding assay, co-localization by immunofluorescence","journal":"Biochemical and biophysical research communications","confidence":"Low","confidence_rationale":"Tier 3 + Weak — yeast two-hybrid confirmed by in vitro binding, no functional DUB mechanism established","pmids":["19118533"],"is_preprint":false},{"year":2024,"finding":"USP33 deubiquitinates HIF1A (HIF-1α) to stabilize it in hypoxia-exposed human retinal vascular endothelial cells; the RNA-binding protein ELAVL1 stabilizes USP33 mRNA to maintain USP33 protein levels and sustain HIF1A stability.","method":"Immunoprecipitation, ubiquitination assay, RNA immunoprecipitation (RIP), actinomycin D stability assay","journal":"International ophthalmology","confidence":"Medium","confidence_rationale":"Tier 2-3 — Co-IP/ubiquitination assay and RIP linking mRNA stability to protein function, single lab","pmids":["39320536"],"is_preprint":false}],"current_model":"USP33 is a cysteine deubiquitinase with isoform-specific subcellular localization (ER, late endosomes, Golgi, centrioles, outer mitochondrial membrane) whose substrate specificity is determined partly by SLiM-binding auxiliary domains (zf-UBP and DUSP2); it deubiquitinates a broad range of substrates—including β2-adrenergic receptor, beta-arrestin2, Robo1, CP110, RALB (K47), Parkin (K435), HIF-2α, p53, DUSP1, JAK2, SP1, TGFBR2, SIN1, c-Myc, CBX2, integrin α6, PAK1, TRAF2/3, LATS1, ATF3, IRF9, and CNR1—to regulate their stability, localization, and downstream signaling; USP33 activity is itself regulated by CDK1-mediated phosphorylation (activating), and by ubiquitin-mediated proteasomal degradation driven by HERC2/p97 and β-TrCP."},"narrative":{"teleology":[{"year":2007,"claim":"Solving the ZnF UBP domain structure revealed that, unlike USP5, USP33 coordinates three zinc ions and does not bind free ubiquitin through this domain, raising the question of how its auxiliary domains contribute to substrate selection.","evidence":"NMR spectroscopy of recombinant ZnF UBP domain","pmids":["17766394"],"confidence":"High","gaps":["No substrate or functional role assigned to the ZnF UBP domain at this stage","Role of the three-zinc architecture unknown"]},{"year":2009,"claim":"Three contemporaneous studies established USP33 as a deubiquitinase controlling receptor trafficking: it deubiquitinates β2AR to promote receptor recycling from endosomes, deubiquitinates β-arrestin2 to modulate receptor–arrestin complex stability, and deubiquitinates/redistributes Robo1 to mediate Slit-dependent axon guidance and cancer cell migration inhibition.","evidence":"Co-IP, ubiquitination assays, receptor recycling/internalization assays in HEK293 cells; in vivo axon guidance assays in chick/mouse neural tube; migration assays in breast cancer cells","pmids":["19424180","19363159","19706539","19684588"],"confidence":"High","gaps":["Structural basis for USP33 recognition of these diverse receptors unknown","Whether USP33 and USP20 are redundant for these substrates not resolved"]},{"year":2011,"claim":"Isoform mapping showed that alternative splicing generates USP33 variants with distinct subcellular localizations — all isoforms associate with ER, while one isoform additionally targets the Golgi — explaining how a single DUB can access substrates in different compartments.","evidence":"GFP-tagged isoform expression with immunofluorescence and deletion analysis in cultured cells","pmids":["21801292"],"confidence":"High","gaps":["Which isoform acts on which substrate in vivo not determined","Regulation of isoform-specific splicing unknown"]},{"year":2013,"claim":"Two discoveries expanded USP33 function beyond receptor biology: it deubiquitinates CP110 at centrioles to control centrosome duplication, and it deubiquitinates RALB at K47 on starvation-induced vesicles to switch RALB from innate-immune to autophagy signaling.","evidence":"In vitro DUB assay for CP110, site-directed mutagenesis (K47) for RALB, centrosome duplication and autophagy assays","pmids":["23486064","24056301"],"confidence":"High","gaps":["How USP33 is recruited to centrioles specifically in S/G2-M not resolved","Signal that triggers USP33 accumulation on RALB-positive vesicles during starvation not identified"]},{"year":2014,"claim":"The turnover of USP33 itself was shown to be controlled by HERC2-mediated polyubiquitination followed by p97/Ufd1-Npl4-dependent extraction and proteasomal degradation, establishing that USP33 abundance is tightly regulated at the post-translational level.","evidence":"Quantitative mass spectrometry, siRNA knockdown and chemical inhibition of p97, ubiquitination assays","pmids":["24855649"],"confidence":"High","gaps":["Signal triggering HERC2-mediated USP33 degradation unknown","Whether HERC2 regulation is constitutive or stimulus-dependent not addressed"]},{"year":2017,"claim":"β-TrCP was identified as a second E3 ligase targeting USP33 for proteasomal degradation through an atypical interaction independent of the classical β-TrCP degron, indicating dual E3-mediated control of USP33 levels.","evidence":"Co-IP, domain mapping, ubiquitination assay with proteasome inhibitor","pmids":["28506875"],"confidence":"Medium","gaps":["No phospho-degron identified; atypical binding mode not structurally resolved","Relative contributions of HERC2 vs. β-TrCP under different conditions unknown"]},{"year":2019,"claim":"USP33 was shown to localize to the outer mitochondrial membrane and to deubiquitinate Parkin at K435 (removing K6/K11/K48/K63 chains), thereby attenuating Parkin activation and suppressing mitophagy — extending USP33 function to mitochondrial quality control.","evidence":"In vitro and cellular DUB assays, K435 mutagenesis, mitophagy assays, mitochondrial fractionation","pmids":["31432739"],"confidence":"High","gaps":["How USP33 OMM targeting is coordinated with mitochondrial depolarization not defined","Interplay with other Parkin-targeting DUBs (USP8, USP15, USP30) not addressed"]},{"year":2019,"claim":"USP33 was found to deubiquitinate DUSP1, preventing its K48-linked degradation and thereby suppressing JNK-mediated apoptosis in prostate cancer, revealing a role in stress-kinase signaling.","evidence":"Co-IP, K48-linkage-specific ubiquitination assay, JNK inhibitor epistasis in prostate cancer cells","pmids":["31857702"],"confidence":"High","gaps":["Whether USP33-DUSP1 interaction is direct or scaffolded unknown","Broader relevance to other MAPK phosphatases not tested"]},{"year":2022,"claim":"Under hypoxia, ERK1/2 phosphorylates HIF-2α to enhance its binding to USP33, which deubiquitinates and stabilizes HIF-2α, driving glioma stem cell maintenance — demonstrating that signal-dependent substrate phosphorylation can regulate USP33 substrate engagement.","evidence":"Co-IP, ubiquitination assay, ERK inhibitor experiments, glioblastoma stem cell assays, in vivo tumor models","pmids":["35191554"],"confidence":"High","gaps":["Phosphorylation site on HIF-2α mediating USP33 interaction not mapped","Whether USP33 similarly regulates HIF-1α stability under analogous conditions was only addressed separately (PMID:39320536)"]},{"year":2024,"claim":"Site-specific ubiquitinomics identified CBX2 K277 as a direct USP33 target where K27- and K48-linked chains are removed; GCN5-mediated acetylation of CBX2 at K199 enhances CBX2–USP33 interaction, establishing acetylation-deubiquitination crosstalk in substrate regulation.","evidence":"Proteomics, ubiquitinomics, site-directed mutagenesis (K277, K199), Co-IP","pmids":["39256572"],"confidence":"High","gaps":["Structural basis for how K199 acetylation promotes USP33 binding not resolved","Whether this crosstalk operates for other USP33 substrates unknown"]},{"year":2024,"claim":"USP33 was shown to deubiquitinate p53 under DNA-damage conditions, and hepatocyte-specific USP33 knockout mice exhibited enhanced DEN-induced hepatocarcinogenesis, providing the first in vivo genetic evidence that USP33 functions as a tumor suppressor through p53 stabilization.","evidence":"Co-IP, ubiquitination assay, conditional knockout mouse model with chemical carcinogenesis","pmids":["39694539"],"confidence":"High","gaps":["Whether USP33 competes with Mdm2 for p53 deubiquitination not established","Tissue-specific vs. general tumor-suppressive role of USP33 undefined"]},{"year":2025,"claim":"CDK1 was identified as a direct kinase activating USP33 via phosphorylation, with USP33 in turn deubiquitinating SIN1 to activate mTORC2–AKT signaling and drive pancreatic cancer chemoresistance, closing the loop on how cell-cycle kinase signaling modulates USP33 catalytic output.","evidence":"CDK1 kinase assay, Co-IP, ubiquitination assay, genetic ablation of CDK1/USP33/SIN1, in vivo tumor models","pmids":["40695806"],"confidence":"High","gaps":["Phosphorylation sites on USP33 not mapped","Whether CDK1-USP33 regulation extends to other G2/M substrates (e.g. CP110) not tested"]},{"year":2025,"claim":"Proteomic peptide phage display showed that the zf-UBP and DUSP2 domains of USP33 function as SLiM-binding modules with binding profiles overlapping USP20, providing a structural rationale for broad substrate recognition and functional redundancy between these paralogous DUBs.","evidence":"Proteomic-peptide phage display, peptide arrays, affinity measurements (preprint)","pmids":["bio_10.1101_2025.09.22.676098"],"confidence":"Medium","gaps":["Preprint; awaits peer review","Which specific SLiMs in individual substrates are recognized not mapped","In vivo validation of SLiM-dependent substrate recruitment not performed"]},{"year":null,"claim":"Key open questions include: the full catalytic-domain structure of USP33, the phosphorylation sites through which CDK1 activates it, the degree of functional redundancy with USP20 in vivo, how isoform-specific splicing is regulated to direct compartment-specific substrate access, and whether USP33 has genuine substrate selectivity rules or acts broadly on accessible ubiquitinated proteins in its vicinity.","evidence":"","pmids":[],"confidence":"High","gaps":["No full-length catalytic domain crystal/cryo-EM structure","CDK1 phosphorylation sites on USP33 unmapped","No genetic study comparing USP33/USP20 double knockout","Substrate specificity rules beyond SLiM-binding domains not defined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,1,5,6,11,12,16,25,26,31]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[0,5,6,11,25,26]}],"localization":[{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[10]},{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[10]},{"term_id":"GO:0005815","term_label":"microtubule organizing center","supporting_discovery_ids":[5]},{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[11]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[0]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[6]}],"pathway":[{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[6,11]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[5]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,1,2,3,16,19,22,23,31]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[0,5,7,13,25,26]},{"term_id":"R-HSA-1852241","term_label":"Organelle biogenesis and maintenance","supporting_discovery_ids":[5,11]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[3]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[14,15,27]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[26,33]}],"complexes":[],"partners":["ADRB2","ARRB2","ROBO1","CP110","RALB","PRKN","EPAS1","TP53"],"other_free_text":[]},"mechanistic_narrative":"USP33 is a cysteine deubiquitinase that stabilizes a broad array of substrates by removing K48-, K27-, K63-, K6-, and K11-linked ubiquitin chains, thereby controlling receptor trafficking, centrosome homeostasis, autophagy, mitophagy, and multiple signaling cascades. It deubiquitinates membrane receptors (β2AR, Robo1, TGFBR2, CNR1, integrin α6) to promote their recycling or surface retention and prevent lysosomal degradation, and it deubiquitinates signaling effectors (RALB at K47, CP110, Parkin at K435, HIF-2α, p53, c-Myc, β-catenin, SIN1, LATS1) to regulate their stability and pathway output [PMID:19424180, PMID:23486064, PMID:24056301, PMID:31432739, PMID:35191554, PMID:39694539, PMID:37322017, PMID:40695806]. Substrate recruitment is mediated in part by SLiM-binding zf-UBP and DUSP2 auxiliary domains, and its catalytic activity is enhanced by CDK1-mediated phosphorylation [PMID:bio_10.1101_2025.09.22.676098, PMID:40695806]. USP33 itself is targeted for proteasomal destruction by the E3 ligases HERC2 (via p97/Ufd1-Npl4) and β-TrCP, and its mRNA is stabilized by METTL3-mediated m6A modification read by IGF2BP3 and by the RNA-binding protein ELAVL1, establishing multilayered control of USP33 abundance [PMID:24855649, PMID:28506875, PMID:41108357, PMID:39320536]."},"prefetch_data":{"uniprot":{"accession":"Q8TEY7","full_name":"Ubiquitin carboxyl-terminal hydrolase 33","aliases":["Deubiquitinating enzyme 33","Ubiquitin thioesterase 33","Ubiquitin-specific-processing protease 33","VHL-interacting deubiquitinating enzyme 1","hVDU1"],"length_aa":942,"mass_kda":106.7,"function":"Deubiquitinating enzyme involved in various processes such as centrosome duplication, cellular migration and beta-2 adrenergic receptor/ADRB2 recycling. Involved in regulation of centrosome duplication by mediating deubiquitination of CCP110 in S and G2/M phase, leading to stabilize CCP110 during the period which centrioles duplicate and elongate. Involved in cell migration via its interaction with intracellular domain of ROBO1, leading to regulate the Slit signaling. Plays a role in commissural axon guidance cross the ventral midline of the neural tube in a Slit-dependent manner, possibly by mediating the deubiquitination of ROBO1. Acts as a regulator of G-protein coupled receptor (GPCR) signaling by mediating the deubiquitination of beta-arrestins (ARRB1 and ARRB2) and beta-2 adrenergic receptor (ADRB2). Plays a central role in ADRB2 recycling and resensitization after prolonged agonist stimulation by constitutively binding ADRB2, mediating deubiquitination of ADRB2 and inhibiting lysosomal trafficking of ADRB2. Upon dissociation, it is probably transferred to the translocated beta-arrestins, leading to beta-arrestins deubiquitination and disengagement from ADRB2. This suggests the existence of a dynamic exchange between the ADRB2 and beta-arrestins. Deubiquitinates DIO2, thereby regulating thyroid hormone regulation. Mediates deubiquitination of both 'Lys-48'- and 'Lys-63'-linked polyubiquitin chains","subcellular_location":"Golgi apparatus","url":"https://www.uniprot.org/uniprotkb/Q8TEY7/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/USP33","classification":"Not Classified","n_dependent_lines":9,"n_total_lines":1208,"dependency_fraction":0.0074503311258278145},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/USP33","total_profiled":1310},"omim":[{"mim_id":"615146","title":"UBIQUITIN-SPECIFIC PROTEASE 33; USP33","url":"https://www.omim.org/entry/615146"},{"mim_id":"615143","title":"UBIQUITIN-SPECIFIC PROTEASE 20; USP20","url":"https://www.omim.org/entry/615143"},{"mim_id":"609544","title":"CENTRIOLAR COILED-COIL PROTEIN, 110-KD; CCP110","url":"https://www.omim.org/entry/609544"},{"mim_id":"602430","title":"ROUNDABOUT GUIDANCE RECEPTOR 1; ROBO1","url":"https://www.omim.org/entry/602430"},{"mim_id":"601413","title":"DEIODINASE, IODOTHYRONINE, TYPE II; DIO2","url":"https://www.omim.org/entry/601413"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Golgi apparatus","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/USP33"},"hgnc":{"alias_symbol":["KIAA1097","VDU1"],"prev_symbol":[]},"alphafold":{"accession":"Q8TEY7","domains":[{"cath_id":"3.30.40.10","chopping":"41-125","consensus_level":"medium","plddt":83.5605,"start":41,"end":125},{"cath_id":"3.90.70.10","chopping":"473-514_567-715","consensus_level":"high","plddt":93.6752,"start":473,"end":715},{"cath_id":"3.30.2230.10","chopping":"815-918","consensus_level":"high","plddt":89.324,"start":815,"end":918}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TEY7","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TEY7-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TEY7-F1-predicted_aligned_error_v6.png","plddt_mean":70.06},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=USP33","jax_strain_url":"https://www.jax.org/strain/search?query=USP33"},"sequence":{"accession":"Q8TEY7","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8TEY7.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8TEY7/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TEY7"}},"corpus_meta":[{"pmid":"19424180","id":"PMC_19424180","title":"The 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patterns of WSB-1 and USP-33 underlie cell-specific posttranslational control of type 2 deiodinase in the rat brain.","date":"2007","source":"Endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/17628004","citation_count":31,"is_preprint":false},{"pmid":"24855649","id":"PMC_24855649","title":"Degradation of the deubiquitinating enzyme USP33 is mediated by p97 and the ubiquitin ligase HERC2.","date":"2014","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/24855649","citation_count":29,"is_preprint":false},{"pmid":"37322017","id":"PMC_37322017","title":"USP33 promotes pancreatic cancer malignant phenotype through the regulation of TGFBR2/TGFβ signaling pathway.","date":"2023","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/37322017","citation_count":27,"is_preprint":false},{"pmid":"32835698","id":"PMC_32835698","title":"USP33 regulates c-Met expression by deubiquitinating SP1 to facilitate metastasis in hepatocellular 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pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/38703975","citation_count":4,"is_preprint":false},{"pmid":"39694539","id":"PMC_39694539","title":"USP33 Regulates DNA Damage Response and Carcinogenesis Through Deubiquitylating and Stabilising p53.","date":"2024","source":"Cell proliferation","url":"https://pubmed.ncbi.nlm.nih.gov/39694539","citation_count":2,"is_preprint":false},{"pmid":"30187867","id":"PMC_30187867","title":"[USP33 suppresses lung adenocarcinoma lung cell invasion and metastasis by down-regulating SLIT2/ROBO1 signaling pathway].","date":"2018","source":"Nan fang yi ke da xue xue bao = Journal of Southern Medical University","url":"https://pubmed.ncbi.nlm.nih.gov/30187867","citation_count":2,"is_preprint":false},{"pmid":"40801947","id":"PMC_40801947","title":"Synergistic inhibition of TNBC by USP33 and TAP63 through autophagy and ferroptosis activation.","date":"2025","source":"Cellular and molecular life sciences : CMLS","url":"https://pubmed.ncbi.nlm.nih.gov/40801947","citation_count":1,"is_preprint":false},{"pmid":"40532745","id":"PMC_40532745","title":"USP33-mediated stabilization of c-Myc drives glycolytic reprogramming and promotes ovarian cancer progression.","date":"2025","source":"Biochimica et biophysica acta. General subjects","url":"https://pubmed.ncbi.nlm.nih.gov/40532745","citation_count":1,"is_preprint":false},{"pmid":"40679549","id":"PMC_40679549","title":"13-Docosenamide Enhances Oligodendrocyte Precursor Cell Differentiation via USP33-Mediated Deubiquitination of CNR1 in Chronic Cerebral Hypoperfusion.","date":"2025","source":"Neuroscience bulletin","url":"https://pubmed.ncbi.nlm.nih.gov/40679549","citation_count":1,"is_preprint":false},{"pmid":"39637362","id":"PMC_39637362","title":"USP33 PROMOTES CERULEIN-INDUCED APOPTOTIC, OXIDATIVE, AND INFLAMMATORY INJURIES IN ACUTE PANCREATITIS BY DEUBIQUITINATING TRAF3.","date":"2024","source":"Shock (Augusta, Ga.)","url":"https://pubmed.ncbi.nlm.nih.gov/39637362","citation_count":1,"is_preprint":false},{"pmid":"39320536","id":"PMC_39320536","title":"RNA binding protein ELAVL1-mediated USP33 stabilizes HIF1A to promote pathological proliferation, migration and angiogenesis of RECs.","date":"2024","source":"International ophthalmology","url":"https://pubmed.ncbi.nlm.nih.gov/39320536","citation_count":1,"is_preprint":false},{"pmid":"40695806","id":"PMC_40695806","title":"Phosphorylation of USP33 by CDK1 stabilizes the mTORC2 component SIN1.","date":"2025","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/40695806","citation_count":0,"is_preprint":false},{"pmid":"41452077","id":"PMC_41452077","title":"Involvement of USP33 in ferritinophagy and ferroptosis in endometriosis through the Hippo-YAP pathway.","date":"2025","source":"Gynecological endocrinology : the official journal of the International Society of Gynecological Endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/41452077","citation_count":0,"is_preprint":false},{"pmid":"40824480","id":"PMC_40824480","title":"USP33 Facilitates Retinoblastoma Growth by Deubiquitinating and Stabilizing EPHB2 Protein.","date":"2025","source":"Applied biochemistry and biotechnology","url":"https://pubmed.ncbi.nlm.nih.gov/40824480","citation_count":0,"is_preprint":false},{"pmid":"39506557","id":"PMC_39506557","title":"USP33 promotes pulmonary microvascular endothelial cell pyroptosis by stabilizing TRAF2 through deubiquitination.","date":"2024","source":"Histology and histopathology","url":"https://pubmed.ncbi.nlm.nih.gov/39506557","citation_count":0,"is_preprint":false},{"pmid":"39589547","id":"PMC_39589547","title":"USP33 is an integrin α6 deubiquitinase and promotes esophageal squamous cell carcinoma cell migration and metastasis.","date":"2024","source":"Journal of cancer research and clinical oncology","url":"https://pubmed.ncbi.nlm.nih.gov/39589547","citation_count":0,"is_preprint":false},{"pmid":"41661462","id":"PMC_41661462","title":"The role of deubiquitinase USP33 in colorectal cancer tumorigenesis and its potential as a therapeutic target predictor.","date":"2026","source":"Discover oncology","url":"https://pubmed.ncbi.nlm.nih.gov/41661462","citation_count":0,"is_preprint":false},{"pmid":"41108357","id":"PMC_41108357","title":"METTL3/IGF2BP3 axis promotes gemcitabine resistance of pancreatic cancer cells through regulating USP33-mediated PAK1 deubiquitination and degradation.","date":"2025","source":"Naunyn-Schmiedeberg's archives of pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/41108357","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.09.22.676098","title":"Systematic Discovery of Motif-based Interactions of the Auxiliary Domains of USP Family Deubiquitinases","date":"2025-09-22","source":"bioRxiv","url":"https://doi.org/10.1101/2025.09.22.676098","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":26013,"output_tokens":8689,"usd":0.104187},"stage2":{"model":"claude-opus-4-6","input_tokens":12663,"output_tokens":3916,"usd":0.241822},"total_usd":0.346009,"stage1_batch_id":"msgbatch_01BparvgRZ9S2LMidvaoo86K","stage2_batch_id":"msgbatch_01NkBfv9SVZWthhS7j6mU6G3","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2009,\n      \"finding\": \"USP33 constitutively binds beta2-adrenergic receptor (β2AR) and dissociates immediately after agonist stimulation, then reassociates on prolonged agonist treatment; USP33 deubiquitinates β2AR to inhibit lysosomal trafficking and promote receptor recycling from late-endosomal compartments, thereby resensitizing receptors at the cell surface.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assays, receptor trafficking/recycling assays in HEK293 cells, fluorescence microscopy\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP and functional trafficking assays with multiple readouts, replicated across related work\",\n      \"pmids\": [\"19424180\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"USP33 binds beta-arrestin2 and deubiquitinates it, opposing Mdm2-mediated ubiquitination; this reciprocal regulation controls the stability of the receptor–beta-arrestin complex, subcellular localization of receptor signalosomes, and β2AR internalization. Class A receptors (e.g., β2AR) promote a beta-arrestin conformation that favors USP33 binding, whereas class B receptors (e.g., V2R) favor USP33 dissociation.\",\n      \"method\": \"Co-immunoprecipitation, in vivo ubiquitination assay, receptor internalization assay, siRNA knockdown, confocal microscopy\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP plus functional internalization assays with mechanistic epistasis\",\n      \"pmids\": [\"19363159\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"USP33 binds Robo1 receptor and is required for Slit-induced redistribution of Robo1 from intracellular compartments to the plasma membrane, and for Slit-mediated inhibition of directional breast cancer cell migration.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown, cell migration assays, receptor localization by fluorescence microscopy\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct binding established by Co-IP, functional consequence shown by knockdown with defined migration phenotype\",\n      \"pmids\": [\"19706539\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"USP33 is required for Slit-mediated axon guidance at the ventral midline; it interacts with Robo1 and is essential for commissural axon midline crossing in vertebrates.\",\n      \"method\": \"Co-immunoprecipitation, in vivo knockdown in chick/mouse neural tube, axon guidance assays\",\n      \"journal\": \"Nature neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — in vivo loss-of-function with specific axon guidance phenotype, Co-IP binding\",\n      \"pmids\": [\"19684588\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"The ZnF UBP domain of USP33/VDU1 was solved by NMR spectroscopy; the structure contains three zinc ions (unlike the single Zn of USP5) and, unlike the USP5 ZnF UBP domain, does not bind ubiquitin.\",\n      \"method\": \"NMR spectroscopy, structural determination\",\n      \"journal\": \"Protein science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — NMR structure with functional binding characterization\",\n      \"pmids\": [\"17766394\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"USP33 localizes to centrioles primarily in S and G2/M phases, interacts with CP110, and potently and specifically deubiquitinates CP110 (but not other cyclin-F substrates), thereby antagonizing SCF(cyclin F)-mediated ubiquitination and promoting supernumerary centriole generation; USP33 ablation destabilizes CP110 and inhibits centrosome amplification.\",\n      \"method\": \"Co-immunoprecipitation, in vivo and in vitro ubiquitination assays, centrosome duplication assays, siRNA knockdown, immunofluorescence localization\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro deubiquitination assay, reciprocal Co-IP, specific substrate validation, multiple orthogonal readouts\",\n      \"pmids\": [\"23486064\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Nutrient starvation induces USP33 accumulation and relocalization to RALB-positive vesicles, where USP33 deubiquitylates RALB at Lys47; deubiquitylated RALB preferentially interacts with EXO84 to drive autophagosome formation, while ubiquitylated RALB favors SEC5-TBK1 innate immune signaling.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assays, site-directed mutagenesis (K47), autophagy assays, confocal microscopy\",\n      \"journal\": \"Nature cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — site-specific mutagenesis identifying K47 as the regulatory ubiquitination site, multiple orthogonal assays\",\n      \"pmids\": [\"24056301\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"USP33 is degraded via the ubiquitin-proteasome system; HERC2 (a HECT-domain E3 ligase) polyubiquitinates USP33, and p97 (with its Ufd1-Npl4 adaptor complex) is required for post-ubiquitination processing and degradation of USP33.\",\n      \"method\": \"Quantitative mass spectrometry, siRNA knockdown of p97/HERC2, chemical inhibition of p97, ubiquitination assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (MS, genetic knockdown, chemical inhibition) identifying E3 ligase and AAA-ATPase machinery\",\n      \"pmids\": [\"24855649\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"USP33 deubiquitinates and stabilizes Robo1 in lung cancer cells, mediating Slit-Robo signaling to inhibit lung cancer cell migration.\",\n      \"method\": \"siRNA knockdown, Co-immunoprecipitation, ubiquitination assay, cell migration assay\",\n      \"journal\": \"Protein & cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — Co-IP and functional migration assay, single lab\",\n      \"pmids\": [\"24981056\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"USP33 deubiquitinates and stabilizes Robo1 in colorectal cancer cells, required for Slit2-mediated inhibition of CRC cell migration.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, siRNA knockdown, cell migration assay\",\n      \"journal\": \"International journal of cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP and functional migration assay, single lab\",\n      \"pmids\": [\"25242263\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"USP33 exists as multiple splice variants with isoform-specific subcellular localization: all variants localize to ER-associated structures, while variant 3 additionally accumulates at the Golgi; two distinct inserts in the catalytic domain mediate ER association and membrane association respectively, and alternative splicing of eight amino acids in insert 2 enables Golgi targeting.\",\n      \"method\": \"GFP-tagged isoform expression, immunofluorescence microscopy, fractionation, deletion/splice variant analysis\",\n      \"journal\": \"Traffic\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct localization with functional domain mapping and multiple isoform characterization\",\n      \"pmids\": [\"21801292\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"USP33 localizes to the outer mitochondrial membrane, binds PRKN/parkin, and deubiquitinates PRKN in a DUB activity-dependent manner; USP33 preferentially removes K6, K11, K48, and K63-linked ubiquitin chains from PRKN, primarily at Lys435 (K63-linked chains); USP33 knockdown enhances both PRKN stabilization and its translocation to depolarized mitochondria, thereby increasing mitophagy.\",\n      \"method\": \"Co-immunoprecipitation, in vitro and cellular ubiquitination assays, site-directed mutagenesis (K435), mitophagy assays, mitochondrial fractionation\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro deubiquitination, mutagenesis identifying K435 site, multiple linkage-specific assays\",\n      \"pmids\": [\"31432739\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"USP33 interacts with DUSP1 phosphatase and inhibits its K48-linked polyubiquitination and proteasomal degradation; USP33 knockdown promotes DUSP1 degradation leading to enhanced JNK activation and docetaxel-induced apoptosis in prostate cancer cells.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assays, siRNA knockdown/KO, JNK inhibitor rescue experiments\",\n      \"journal\": \"Cell death and differentiation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP, specific ubiquitin linkage (K48) characterization, pharmacological epistasis with JNK inhibitor\",\n      \"pmids\": [\"31857702\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"The E3 ligase β-TrCP interacts with USP33 (via WD40 motif of β-TrCP and the 201-400 aa region of USP33, independently of the classic β-TrCP binding motif) and mediates USP33 ubiquitination and proteasomal degradation.\",\n      \"method\": \"Co-immunoprecipitation, deletion mapping, ubiquitination assay, proteasome inhibitor treatment\",\n      \"journal\": \"Experimental cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP with domain mapping, single lab\",\n      \"pmids\": [\"28506875\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"USP33 deubiquitylates IRF9 to regulate its stability; SARS-CoV-2 Spike-induced exosomal miR-148a suppresses USP33 expression in human microglia, leading to decreased IRF9 levels and hyperactivation of pro-inflammatory TNFα, NF-κB, and IFN-β pathways.\",\n      \"method\": \"miRNA overexpression/knockdown, luciferase reporter assay, immunoblotting, in vivo ubiquitination assay\",\n      \"journal\": \"Frontiers in immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — ubiquitination assay linking USP33 to IRF9 stability, functional downstream readout\",\n      \"pmids\": [\"33936086\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"USP33 deubiquitylates ATF3 to stabilize it; DENV-NS1-induced exosomal miR-148a suppresses USP33 in human microglia, reducing ATF3 stability and disinhibiting TNF-α, NF-κB, and IFN-β pro-inflammatory signaling.\",\n      \"method\": \"EV cargo analysis, miRNA mimic/anti-miR, dual luciferase reporter, in vivo ubiquitination assay, chase assay\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — in vivo ubiquitination assay showing USP33-dependent ATF3 stability, single lab\",\n      \"pmids\": [\"32848034\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"USP33 is preferentially induced in glioma stem cells by hypoxia, interacts with HIF-2α, and deubiquitinates and stabilizes HIF-2α protein; ERK1/2 activation upon hypoxia promotes HIF-2α phosphorylation, enhancing its interaction with USP33. USP33 silencing disrupts glioma stem cell maintenance and reduces tumor vascularization.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, ERK inhibitor experiments, siRNA knockdown, glioblastoma stem cell maintenance assays, in vivo tumor models\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP, ubiquitination assay, epistasis with ERK pathway, in vivo validation\",\n      \"pmids\": [\"35191554\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"ERAP1 hepatokine interacts with β2 adrenergic receptor (ADRB2) and reduces its expression by decreasing USP33-mediated deubiquitination of ADRB2, thereby disrupting ADRB2-stimulated insulin signaling in skeletal muscle.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, hepatic overexpression/knockdown in mice, insulin signaling assays\",\n      \"journal\": \"Diabetes\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — Co-IP and ubiquitination assay in physiological context, in vivo mouse model\",\n      \"pmids\": [\"35192681\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"USP33 deubiquitinates PPM1A (a Smad2/3 phosphatase); miR-3591-5p targets USP33 to reduce PPM1A stability, thereby activating TGF-β/Smad2/3 signaling and promoting radiation-induced EMT in lung cancer cells.\",\n      \"method\": \"Luciferase reporter assay (3'UTR), ubiquitination assay, ectopic expression rescue, Western blot\",\n      \"journal\": \"Cellular physiology and biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — functional rescue experiments link USP33 to PPM1A stability, single lab\",\n      \"pmids\": [\"30308513\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"USP33 interacts with TGFBR2 (TGF-β receptor 2), deubiquitinates it, and prevents its lysosomal degradation, promoting TGFBR2 accumulation at the cell membrane and sustained TGF-β signaling; TGF-β target ZEB1 in turn transcriptionally activates USP33 forming a positive feedback loop.\",\n      \"method\": \"Mass spectrometry, luciferase complementation assay, Co-immunoprecipitation, ubiquitination assay, lysosome inhibition experiments\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — MS substrate screening, Co-IP, ubiquitination assay, single lab\",\n      \"pmids\": [\"37322017\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"USP33 directly binds SP1 transcription factor and deubiquitinates it, stabilizing SP1 protein and upregulating c-Met expression, thereby promoting hepatocellular carcinoma invasion and metastasis.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, RNA sequencing, luciferase reporter, in vivo metastasis model\",\n      \"journal\": \"Life sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP and ubiquitination assay identifying SP1 as substrate, single lab\",\n      \"pmids\": [\"32835698\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"USP33 interacts with and deubiquitinates c-Myc; circ_0057558 sponges miR-206 to increase USP33 expression, which stabilizes c-Myc and promotes prostate cancer cell proliferation.\",\n      \"method\": \"RNA pulldown, luciferase assay, Co-immunoprecipitation, ubiquitination assay\",\n      \"journal\": \"Frontiers in cell and developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP and ubiquitination assay for c-Myc, single lab\",\n      \"pmids\": [\"33718387\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"USP33 deubiquitinates JAK2 to activate JAK2/STAT3 signaling in cardiomyocytes; miR-206 targets USP33 to suppress this pathway and protect against LPS-induced inflammatory injury.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, dual luciferase reporter, siRNA knockdown rescue experiments\",\n      \"journal\": \"Molecular and cellular biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP and ubiquitination assay identifying JAK2 as substrate, single lab\",\n      \"pmids\": [\"37256445\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"USP33 interacts with CTNNB1 (β-catenin) and deubiquitinates it, preventing its degradation and promoting pancreatic cancer cell proliferation and self-renewal.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, sphere formation, colony formation assays\",\n      \"journal\": \"Cell biology international\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP and ubiquitination assay, single lab\",\n      \"pmids\": [\"37076992\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"USP33 stabilizes PFKFB3 by suppressing its ubiquitin-mediated degradation, driving aerobic glycolysis and osteosarcoma cell growth.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, glycolysis functional assays\",\n      \"journal\": \"American journal of cancer research\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 + Weak — single lab, limited mechanistic detail on ubiquitination linkage\",\n      \"pmids\": [\"37034227\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"USP33 removes K27- and K48-linked ubiquitin chains from CBX2 at K277; acetylation of CBX2 at K199 by acetyltransferase GCN5 enhances CBX2 interaction with USP33, promoting further deubiquitination and stabilization of CBX2 to drive ovarian cancer progression.\",\n      \"method\": \"Proteomics, ubiquitinomics, Co-immunoprecipitation, site-directed mutagenesis (K277, K199), ubiquitination assay\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — proteomics/ubiquitinomics substrate screen, site-specific mutagenesis, cross-talk between acetylation and deubiquitination\",\n      \"pmids\": [\"39256572\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"USP33 interacts with and deubiquitinates p53 to stabilize it under DNA damage conditions; USP33 depletion increases p53 ubiquitination and impairs DNA damage-induced cell cycle arrest and apoptosis; hepatocyte-specific USP33 knockout mice show enhanced sensitivity to DEN-induced hepatocarcinogenesis.\",\n      \"method\": \"Co-immunoprecipitation, in vivo ubiquitination assay, USP33 knockout mouse model, liver carcinogenesis assay\",\n      \"journal\": \"Cell proliferation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP, ubiquitination assay, in vivo knockout mouse model with carcinogenesis phenotype\",\n      \"pmids\": [\"39694539\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"USP33 interacts with TRAF3, deubiquitinates it, and upregulates its expression, activating the NF-κB pathway to promote apoptosis, oxidative stress, and inflammation in cerulein-induced acute pancreatitis.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, siRNA knockdown, immunofluorescence, NF-κB pathway assays\",\n      \"journal\": \"Shock\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP and ubiquitination assay, single lab\",\n      \"pmids\": [\"39637362\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"USP33 mediates cell migration in esophageal squamous cell carcinoma by binding, deubiquitinating, and stabilizing integrin α6; USP33 knockdown inhibits laminin-dependent adhesion, spreading, migration, and metastasis.\",\n      \"method\": \"Co-immunoprecipitation, deubiquitination assay, cell adhesion/migration/spreading assays, tail vein injection metastasis model\",\n      \"journal\": \"Journal of cancer research and clinical oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — Co-IP and deubiquitination assay with in vivo metastasis model, single lab\",\n      \"pmids\": [\"39589547\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"USP33 stabilizes TRAF2 by deubiquitination, promoting pyroptosis of human pulmonary microvascular endothelial cells during hypoxia/reoxygenation-induced acute lung injury.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, siRNA knockdown, pyroptosis markers assay\",\n      \"journal\": \"Histology and histopathology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 + Weak — single lab, limited mechanistic depth\",\n      \"pmids\": [\"39506557\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"USP33 stabilizes CNR1 (cannabinoid receptor 1) via deubiquitination in oligodendrocyte precursor cells, activating AKT/mTOR signaling to promote OPC differentiation; 13-docosenamide upregulates this USP33-mediated CNR1 deubiquitination.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, in vivo BCAS mouse model, AKT/mTOR signaling assays\",\n      \"journal\": \"Neuroscience bulletin\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — Co-IP and ubiquitination assay with in vivo model, single lab\",\n      \"pmids\": [\"40679549\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"CDK1 directly phosphorylates USP33, enhancing its deubiquitinase activity toward SIN1 (mTORC2 component); USP33 deubiquitinates and stabilizes SIN1 to activate the mTORC2-AKT pathway, driving chemoresistance in pancreatic cancer.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, CDK1 kinase assay, genetic ablation of CDK1/USP33/SIN1, in vivo tumor models\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — kinase assay identifying CDK1 as USP33 writer, Co-IP and ubiquitination assay for SIN1, in vivo validation\",\n      \"pmids\": [\"40695806\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"USP33 deubiquitinates PAK1 to prevent its degradation; METTL3-mediated m6A modification of USP33 mRNA, read by IGF2BP3, stabilizes USP33 transcript and increases USP33 protein, promoting gemcitabine resistance in pancreatic cancer.\",\n      \"method\": \"Co-immunoprecipitation, MeRIP-qPCR, RIP assay, ubiquitination assay, xenograft model\",\n      \"journal\": \"Naunyn-Schmiedeberg's archives of pharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — Co-IP and ubiquitination assay, epitranscriptomic regulation validated by MeRIP, single lab\",\n      \"pmids\": [\"41108357\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"USP33 stabilizes TAP63 through K48-linked deubiquitination, triggering autophagy and ferroptosis in triple-negative breast cancer by disrupting mitochondrial function and redox balance.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitin chain analysis (K48), ferroptosis/autophagy markers, in vivo xenograft\",\n      \"journal\": \"Cellular and molecular life sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — Co-IP and K48-specific ubiquitin assay, in vivo validation, single lab\",\n      \"pmids\": [\"40801947\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"USP33 deubiquitinates c-Myc at K48-linked chains to stabilize it, enhancing c-Myc transcriptional activity and driving glycolytic reprogramming (upregulating LDHA, GLUT1, PKM2) in ovarian cancer.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay (K48-specific), c-Myc overexpression rescue, metabolic assays\",\n      \"journal\": \"Biochimica et biophysica acta. General subjects\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP and K48-specific ubiquitination assay, rescue experiments, single lab\",\n      \"pmids\": [\"40532745\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"USP33 suppresses LATS1 ubiquitination to inhibit the Hippo-YAP pathway, thereby promoting ferritinophagy and ferroptosis in endometrial stromal cells; USP33 is also localized in autophagosomes and promotes ferritin degradation therein.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, CHX chase assay, ROS/Fe2+/MDA measurements, immunofluorescence colocalization\",\n      \"journal\": \"Gynecological endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — Co-IP, CHX chase, ubiquitination assay, ferroptosis readouts, single lab\",\n      \"pmids\": [\"41452077\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"USP33 deubiquitinates and stabilizes EPHB2, activating Wnt/β-catenin signaling to promote retinoblastoma cell proliferation, invasion, and stemness.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, protein stability assay, xenograft mouse model\",\n      \"journal\": \"Applied biochemistry and biotechnology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 + Weak — single lab, single method for substrate identification\",\n      \"pmids\": [\"40824480\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"The zf-UBP and DUSP2 auxiliary domains of USP33 are short linear motif (SLiM)-binding domains with binding profiles similar to those of USP20, explaining functional redundancy between the two DUBs; these domains mediate substrate targeting via SLiMs in intrinsically disordered regions.\",\n      \"method\": \"Proteomic-peptide phage display, peptide arrays, affinity measurements\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — systematic proteomic phage display and affinity measurements, preprint\",\n      \"pmids\": [\"bio_10.1101_2025.09.22.676098\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"USP33/VDU1 interacts with human selenium-binding protein-1 (hSP56) in a selenium-dependent manner, with full-length VDU1 specifically binding the selenium-replete form of hSP56; the two proteins co-localize in the perinuclear region of prostate cancer cells.\",\n      \"method\": \"Yeast two-hybrid, in vitro binding assay, co-localization by immunofluorescence\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 + Weak — yeast two-hybrid confirmed by in vitro binding, no functional DUB mechanism established\",\n      \"pmids\": [\"19118533\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"USP33 deubiquitinates HIF1A (HIF-1α) to stabilize it in hypoxia-exposed human retinal vascular endothelial cells; the RNA-binding protein ELAVL1 stabilizes USP33 mRNA to maintain USP33 protein levels and sustain HIF1A stability.\",\n      \"method\": \"Immunoprecipitation, ubiquitination assay, RNA immunoprecipitation (RIP), actinomycin D stability assay\",\n      \"journal\": \"International ophthalmology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — Co-IP/ubiquitination assay and RIP linking mRNA stability to protein function, single lab\",\n      \"pmids\": [\"39320536\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"USP33 is a cysteine deubiquitinase with isoform-specific subcellular localization (ER, late endosomes, Golgi, centrioles, outer mitochondrial membrane) whose substrate specificity is determined partly by SLiM-binding auxiliary domains (zf-UBP and DUSP2); it deubiquitinates a broad range of substrates—including β2-adrenergic receptor, beta-arrestin2, Robo1, CP110, RALB (K47), Parkin (K435), HIF-2α, p53, DUSP1, JAK2, SP1, TGFBR2, SIN1, c-Myc, CBX2, integrin α6, PAK1, TRAF2/3, LATS1, ATF3, IRF9, and CNR1—to regulate their stability, localization, and downstream signaling; USP33 activity is itself regulated by CDK1-mediated phosphorylation (activating), and by ubiquitin-mediated proteasomal degradation driven by HERC2/p97 and β-TrCP.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"USP33 is a cysteine deubiquitinase that stabilizes a broad array of substrates by removing K48-, K27-, K63-, K6-, and K11-linked ubiquitin chains, thereby controlling receptor trafficking, centrosome homeostasis, autophagy, mitophagy, and multiple signaling cascades. It deubiquitinates membrane receptors (β2AR, Robo1, TGFBR2, CNR1, integrin α6) to promote their recycling or surface retention and prevent lysosomal degradation, and it deubiquitinates signaling effectors (RALB at K47, CP110, Parkin at K435, HIF-2α, p53, c-Myc, β-catenin, SIN1, LATS1) to regulate their stability and pathway output [PMID:19424180, PMID:23486064, PMID:24056301, PMID:31432739, PMID:35191554, PMID:39694539, PMID:37322017, PMID:40695806]. Substrate recruitment is mediated in part by SLiM-binding zf-UBP and DUSP2 auxiliary domains, and its catalytic activity is enhanced by CDK1-mediated phosphorylation [PMID:bio_10.1101_2025.09.22.676098, PMID:40695806]. USP33 itself is targeted for proteasomal destruction by the E3 ligases HERC2 (via p97/Ufd1-Npl4) and β-TrCP, and its mRNA is stabilized by METTL3-mediated m6A modification read by IGF2BP3 and by the RNA-binding protein ELAVL1, establishing multilayered control of USP33 abundance [PMID:24855649, PMID:28506875, PMID:41108357, PMID:39320536].\",\n  \"teleology\": [\n    {\n      \"year\": 2007,\n      \"claim\": \"Solving the ZnF UBP domain structure revealed that, unlike USP5, USP33 coordinates three zinc ions and does not bind free ubiquitin through this domain, raising the question of how its auxiliary domains contribute to substrate selection.\",\n      \"evidence\": \"NMR spectroscopy of recombinant ZnF UBP domain\",\n      \"pmids\": [\"17766394\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No substrate or functional role assigned to the ZnF UBP domain at this stage\", \"Role of the three-zinc architecture unknown\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Three contemporaneous studies established USP33 as a deubiquitinase controlling receptor trafficking: it deubiquitinates β2AR to promote receptor recycling from endosomes, deubiquitinates β-arrestin2 to modulate receptor–arrestin complex stability, and deubiquitinates/redistributes Robo1 to mediate Slit-dependent axon guidance and cancer cell migration inhibition.\",\n      \"evidence\": \"Co-IP, ubiquitination assays, receptor recycling/internalization assays in HEK293 cells; in vivo axon guidance assays in chick/mouse neural tube; migration assays in breast cancer cells\",\n      \"pmids\": [\"19424180\", \"19363159\", \"19706539\", \"19684588\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis for USP33 recognition of these diverse receptors unknown\", \"Whether USP33 and USP20 are redundant for these substrates not resolved\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Isoform mapping showed that alternative splicing generates USP33 variants with distinct subcellular localizations — all isoforms associate with ER, while one isoform additionally targets the Golgi — explaining how a single DUB can access substrates in different compartments.\",\n      \"evidence\": \"GFP-tagged isoform expression with immunofluorescence and deletion analysis in cultured cells\",\n      \"pmids\": [\"21801292\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which isoform acts on which substrate in vivo not determined\", \"Regulation of isoform-specific splicing unknown\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Two discoveries expanded USP33 function beyond receptor biology: it deubiquitinates CP110 at centrioles to control centrosome duplication, and it deubiquitinates RALB at K47 on starvation-induced vesicles to switch RALB from innate-immune to autophagy signaling.\",\n      \"evidence\": \"In vitro DUB assay for CP110, site-directed mutagenesis (K47) for RALB, centrosome duplication and autophagy assays\",\n      \"pmids\": [\"23486064\", \"24056301\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How USP33 is recruited to centrioles specifically in S/G2-M not resolved\", \"Signal that triggers USP33 accumulation on RALB-positive vesicles during starvation not identified\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"The turnover of USP33 itself was shown to be controlled by HERC2-mediated polyubiquitination followed by p97/Ufd1-Npl4-dependent extraction and proteasomal degradation, establishing that USP33 abundance is tightly regulated at the post-translational level.\",\n      \"evidence\": \"Quantitative mass spectrometry, siRNA knockdown and chemical inhibition of p97, ubiquitination assays\",\n      \"pmids\": [\"24855649\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Signal triggering HERC2-mediated USP33 degradation unknown\", \"Whether HERC2 regulation is constitutive or stimulus-dependent not addressed\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"β-TrCP was identified as a second E3 ligase targeting USP33 for proteasomal degradation through an atypical interaction independent of the classical β-TrCP degron, indicating dual E3-mediated control of USP33 levels.\",\n      \"evidence\": \"Co-IP, domain mapping, ubiquitination assay with proteasome inhibitor\",\n      \"pmids\": [\"28506875\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No phospho-degron identified; atypical binding mode not structurally resolved\", \"Relative contributions of HERC2 vs. β-TrCP under different conditions unknown\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"USP33 was shown to localize to the outer mitochondrial membrane and to deubiquitinate Parkin at K435 (removing K6/K11/K48/K63 chains), thereby attenuating Parkin activation and suppressing mitophagy — extending USP33 function to mitochondrial quality control.\",\n      \"evidence\": \"In vitro and cellular DUB assays, K435 mutagenesis, mitophagy assays, mitochondrial fractionation\",\n      \"pmids\": [\"31432739\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How USP33 OMM targeting is coordinated with mitochondrial depolarization not defined\", \"Interplay with other Parkin-targeting DUBs (USP8, USP15, USP30) not addressed\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"USP33 was found to deubiquitinate DUSP1, preventing its K48-linked degradation and thereby suppressing JNK-mediated apoptosis in prostate cancer, revealing a role in stress-kinase signaling.\",\n      \"evidence\": \"Co-IP, K48-linkage-specific ubiquitination assay, JNK inhibitor epistasis in prostate cancer cells\",\n      \"pmids\": [\"31857702\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether USP33-DUSP1 interaction is direct or scaffolded unknown\", \"Broader relevance to other MAPK phosphatases not tested\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Under hypoxia, ERK1/2 phosphorylates HIF-2α to enhance its binding to USP33, which deubiquitinates and stabilizes HIF-2α, driving glioma stem cell maintenance — demonstrating that signal-dependent substrate phosphorylation can regulate USP33 substrate engagement.\",\n      \"evidence\": \"Co-IP, ubiquitination assay, ERK inhibitor experiments, glioblastoma stem cell assays, in vivo tumor models\",\n      \"pmids\": [\"35191554\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Phosphorylation site on HIF-2α mediating USP33 interaction not mapped\", \"Whether USP33 similarly regulates HIF-1α stability under analogous conditions was only addressed separately (PMID:39320536)\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Site-specific ubiquitinomics identified CBX2 K277 as a direct USP33 target where K27- and K48-linked chains are removed; GCN5-mediated acetylation of CBX2 at K199 enhances CBX2–USP33 interaction, establishing acetylation-deubiquitination crosstalk in substrate regulation.\",\n      \"evidence\": \"Proteomics, ubiquitinomics, site-directed mutagenesis (K277, K199), Co-IP\",\n      \"pmids\": [\"39256572\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis for how K199 acetylation promotes USP33 binding not resolved\", \"Whether this crosstalk operates for other USP33 substrates unknown\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"USP33 was shown to deubiquitinate p53 under DNA-damage conditions, and hepatocyte-specific USP33 knockout mice exhibited enhanced DEN-induced hepatocarcinogenesis, providing the first in vivo genetic evidence that USP33 functions as a tumor suppressor through p53 stabilization.\",\n      \"evidence\": \"Co-IP, ubiquitination assay, conditional knockout mouse model with chemical carcinogenesis\",\n      \"pmids\": [\"39694539\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether USP33 competes with Mdm2 for p53 deubiquitination not established\", \"Tissue-specific vs. general tumor-suppressive role of USP33 undefined\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"CDK1 was identified as a direct kinase activating USP33 via phosphorylation, with USP33 in turn deubiquitinating SIN1 to activate mTORC2–AKT signaling and drive pancreatic cancer chemoresistance, closing the loop on how cell-cycle kinase signaling modulates USP33 catalytic output.\",\n      \"evidence\": \"CDK1 kinase assay, Co-IP, ubiquitination assay, genetic ablation of CDK1/USP33/SIN1, in vivo tumor models\",\n      \"pmids\": [\"40695806\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Phosphorylation sites on USP33 not mapped\", \"Whether CDK1-USP33 regulation extends to other G2/M substrates (e.g. CP110) not tested\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Proteomic peptide phage display showed that the zf-UBP and DUSP2 domains of USP33 function as SLiM-binding modules with binding profiles overlapping USP20, providing a structural rationale for broad substrate recognition and functional redundancy between these paralogous DUBs.\",\n      \"evidence\": \"Proteomic-peptide phage display, peptide arrays, affinity measurements (preprint)\",\n      \"pmids\": [\"bio_10.1101_2025.09.22.676098\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Preprint; awaits peer review\", \"Which specific SLiMs in individual substrates are recognized not mapped\", \"In vivo validation of SLiM-dependent substrate recruitment not performed\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key open questions include: the full catalytic-domain structure of USP33, the phosphorylation sites through which CDK1 activates it, the degree of functional redundancy with USP20 in vivo, how isoform-specific splicing is regulated to direct compartment-specific substrate access, and whether USP33 has genuine substrate selectivity rules or acts broadly on accessible ubiquitinated proteins in its vicinity.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No full-length catalytic domain crystal/cryo-EM structure\", \"CDK1 phosphorylation sites on USP33 unmapped\", \"No genetic study comparing USP33/USP20 double knockout\", \"Substrate specificity rules beyond SLiM-binding domains not defined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 1, 5, 6, 11, 12, 16, 25, 26, 31]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [0, 5, 6, 11, 25, 26]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [10]},\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [10]},\n      {\"term_id\": \"GO:0005815\", \"supporting_discovery_ids\": [5]},\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [11]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [6, 11]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [5]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 1, 2, 3, 16, 19, 22, 23, 31]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [0, 5, 7, 13, 25, 26]},\n      {\"term_id\": \"R-HSA-1852241\", \"supporting_discovery_ids\": [5, 11]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [3]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [14, 15, 27]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [26, 33]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"ADRB2\",\n      \"ARRB2\",\n      \"ROBO1\",\n      \"CP110\",\n      \"RALB\",\n      \"PRKN\",\n      \"EPAS1\",\n      \"TP53\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}