{"gene":"USP53","run_date":"2026-04-28T23:00:23","timeline":{"discoveries":[{"year":2015,"finding":"USP53 contains a catalytically inactive ubiquitin-specific protease domain (annotated as pseudo-enzyme) and colocalizes and physically interacts with tight junction scaffolding proteins TJP1 and TJP2 in polarized epithelial cells, placing USP53 as a component of the tight junction complex essential for auditory hair cell survival.","method":"Co-immunoprecipitation, colocalization imaging, forward genetics (ENU mutagenesis mambo mouse line), cochlear organotypic cultures, biotin tracer assay, electrophysiology (endocochlear potential measurement)","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP plus functional rescue in organotypic culture, replicated in vivo genetic model","pmids":["26609154"],"is_preprint":false},{"year":2018,"finding":"USP53 was identified as an interactor of TJP2, and homozygous truncating variants in USP53 cause low-GGT intrahepatic cholestasis and hearing loss, linking USP53 function to tight junction integrity in the liver and inner ear.","method":"Exome sequencing, positional mapping, human genetics (segregation analysis)","journal":"Genetics in medicine","confidence":"Medium","confidence_rationale":"Tier 3 — genetic association with referenced TJP2 interaction; no independent biochemical assay in this paper","pmids":["30250217"],"is_preprint":false},{"year":2020,"finding":"USP53 deubiquitinates FKBP51, stabilizing it; FKBP51 in turn dephosphorylates AKT1, thereby suppressing AKT1 pathway activity, inhibiting glycolysis, and promoting apoptosis in lung adenocarcinoma cells.","method":"Co-immunoprecipitation, ubiquitination assay, stable overexpression/shRNA knockdown, AKT pathway inhibitor (LY294002), in vivo xenograft","journal":"Molecular carcinogenesis","confidence":"Medium","confidence_rationale":"Tier 2/3 — Co-IP plus ubiquitination assay plus rescue experiment in single lab","pmids":["32511815"],"is_preprint":false},{"year":2020,"finding":"Ultrastructural study of liver biopsies from patients with USP53 mutations revealed elongated hepatocyte-hepatocyte tight junctions, implicating USP53 in tight junction structure/length regulation in hepatocytes.","method":"Transmission electron microscopy of liver biopsies from patients with biallelic USP53 variants","journal":"Liver international","confidence":"Medium","confidence_rationale":"Tier 2 — direct ultrastructural observation in human disease tissue, consistent across multiple patients","pmids":["32124521"],"is_preprint":false},{"year":2021,"finding":"USP53 is identified as a target gene of PTH-activated NACA in osteoblasts; NACA binds the USP53 promoter (confirmed by EMSA), and USP53 promoter activity is regulated by the JUN-CREB complex via activated PKA and NACA. Usp53 knockdown in stromal cells promotes osteoblast markers and inhibits adipogenic markers, establishing a role in mesenchymal lineage commitment.","method":"ChIP-seq, RNA-seq, EMSA, luciferase reporter assay, shRNA knockdown in ST2 stromal cells, in vivo implantation of knockdown cells in immunocompromised mice","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (ChIP, EMSA, reporter, in vivo), single lab","pmids":["33875709"],"is_preprint":false},{"year":2022,"finding":"USP53 interacts with cytochrome c (CYCS) and deubiquitinates it, increasing CYCS stability; overexpression of CYCS rescues the decreased apoptosis caused by USP53 knockdown in hepatocellular carcinoma cells, establishing a USP53-CYCS apoptotic axis.","method":"Co-immunoprecipitation, mass spectrometry, cycloheximide chase assay, GSEA, rescue experiment with CYCS overexpression","journal":"Oncogenesis","confidence":"Medium","confidence_rationale":"Tier 2/3 — Co-IP plus mass spectrometry identification plus functional rescue, single lab","pmids":["35654790"],"is_preprint":false},{"year":2023,"finding":"USP53 regulates RANKL expression by enhancing the interaction between VDR and SMAD3 in osteoblasts and bone marrow adipocytes; Usp53 null mice display low bone mass, increased osteoclastogenesis, and elevated serum RANKL, establishing USP53 as a regulator of osteoblast-osteoclast coupling.","method":"Usp53 knockout mice, micro-CT (trabecular and cortical bone quantification), histomorphometry, serum RANKL ELISA, mechanistic interaction assay (VDR-SMAD3 co-immunoprecipitation)","journal":"Journal of bone and mineral research","confidence":"High","confidence_rationale":"Tier 2 — in vivo knockout with multiple quantitative readouts plus mechanistic Co-IP, single lab","pmids":["36726200"],"is_preprint":false},{"year":2023,"finding":"USP53 directly binds and deubiquitinates CRKL to stabilize it, thereby promoting TNBC cell proliferation, migration, invasion, EMT, and chemoresistance.","method":"Co-immunoprecipitation, ubiquitination assay, gain/loss-of-function cell experiments","journal":"Cancers","confidence":"Low","confidence_rationale":"Tier 3 — single Co-IP plus ubiquitination assay in single lab, no structural validation","pmids":["37894400"],"is_preprint":false},{"year":2023,"finding":"USP53 localizes to hippocampal CA1-3 regions and granular dentate, and co-immunoprecipitates with GRIA2/GluA2 (AMPA receptor subunit) and GRIP2, placing USP53 within the AMPA receptor interactome in the brain.","method":"Immunofluorescence (co-localization with GRIA2/GluA2 and GRIP2 antibodies), co-immunoprecipitation","journal":"Genes","confidence":"Low","confidence_rationale":"Tier 3 — single Co-IP with limited mechanistic follow-up, single lab","pmids":["37895270"],"is_preprint":false},{"year":2024,"finding":"USP53 binds SR-A via its USP domain (requiring Cys41) and removes K48-linked ubiquitin chains from SR-A, preventing its proteasomal degradation and thereby promoting foam cell formation in smooth muscle cells during atherosclerosis. DKK1 regulates USP53 transcription by facilitating CREB binding to the USP53 promoter.","method":"Co-immunoprecipitation, RNA-seq, site-directed mutagenesis (Cys41), ChIP, adeno-associated virus SMC-specific overexpression in DKK1ECKO/APOE-/- mice, parallel-plate co-culture flow system, endothelium-specific KO and OE mouse models","journal":"International journal of biological sciences","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods including mutagenesis, in vivo mouse models, Co-IP; single lab","pmids":["38904030"],"is_preprint":false},{"year":2024,"finding":"USP53 interacts with ZMYND11 and catalyzes its deubiquitination and stabilization; the 33–50 amino acid Cys-box domain is required for USP53 enzymatic activity but not for ZMYND11 binding; USP53-mediated stabilization of ZMYND11 mediates USP53's anti-tumor effects in breast cancer.","method":"Co-immunoprecipitation, domain deletion/mutagenesis (Cys-box), ubiquitination assay, rescue experiments with ZMYND11 overexpression, xenograft","journal":"Biological procedures online","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP plus domain mutagenesis plus rescue, single lab","pmids":["39044157"],"is_preprint":false},{"year":2024,"finding":"USP53 interacts with TJP2 in hepatocytes (confirmed by co-immunoprecipitation and co-immunofluorescence); loss of hepatic USP53 causes upregulation of Tjp2 mRNA, lengthening of hepatocellular tight junctions, and downregulation of bile acid transporters (Abcb11, Ntcp, Abcc2), protecting mice from DDC-induced liver injury.","method":"Usp53 liver-specific knockout mice (Alb-cre × Usp53fl/fl), co-immunoprecipitation, immunofluorescence, electron microscopy (tight junction length), qRT-PCR, dietary challenge (DDC)","journal":"Biochimica et biophysica acta. Molecular basis of disease","confidence":"High","confidence_rationale":"Tier 2 — liver-specific KO with multiple functional readouts plus Co-IP; mechanistically links USP53 to TJP2 and BSEP transporter regulation","pmids":["39705897"],"is_preprint":false},{"year":2024,"finding":"USP53 and USP54, previously annotated as catalytically inactive pseudo-DUBs, are in fact active deubiquitinases with high selectivity for K63-linked polyubiquitin chains. USP53 can deubiquitinate a substrate in a K63-linkage-dependent manner. Patient-associated mutations in the USP domain of USP53 abrogate this catalytic activity. Depletion of USP53 increases K63-linked ubiquitination of tricellular junction components. Structural analyses identified K63-specific S2-ubiquitin-binding sites within the catalytic domain.","method":"Biochemical in vitro DUB activity assays, structural analysis, site-directed mutagenesis of patient variants, K63-linkage-specific ubiquitin chain assays, mass spectrometry, depletion of USP53 followed by K63-ubiquitination profiling of tricellular junction components","journal":"bioRxiv","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstitution of enzymatic activity, structural analysis, mutagenesis of active site with patient variants, and substrate-level K63-ubiquitination profiling in single preprint","pmids":["bio_10.1101_2024.07.07.602376"],"is_preprint":true},{"year":2025,"finding":"Loss of USP53 causes mislocalization of the bile salt export pump (BSEP) to MYO5B-positive and RAB11A-positive recycling endosomes, impairing BSEP trafficking to the plasma membrane. USP53 colocalizes with MYO5B and interacts with its IQ domain; the cholestasis-associated MYO5B p.(Arg824Cys) variant (located in the IQ domain) fails to interact with USP53. Loss of USP53 increases ubiquitination of MYO5B and disrupts its endosomal recruitment.","method":"Immunohistochemistry of patient tissue, confocal immunofluorescence, surface protein biotinylation, siRNA knockdown, CRISPR-Cas9 knockout, site-directed mutagenesis, co-immunoprecipitation, live cell imaging, FRAP","journal":"Hepatology","confidence":"High","confidence_rationale":"Tier 1/2 — multiple orthogonal methods including CRISPR KO, surface biotinylation, FRAP, co-IP with mutagenesis validation in patient-derived tissue","pmids":["40828662"],"is_preprint":false},{"year":2025,"finding":"USP53 interacts with the intermediate domain of RIPK1 and removes K63-linked ubiquitin chains at RIPK1 lysine-377, facilitating RIPK1 autophosphorylation and triggering downstream apoptotic and necroptotic pathways in cardiomyocytes during ethanol-induced injury. USP53 transcription is induced by EGR1 in response to ethanol.","method":"Co-immunoprecipitation combined with LC-MS/MS, site-specific ubiquitination mapping, cardiomyocyte-specific USP53 knockout (USP53CKO) mice, in vivo alcohol feeding model, western blot, ChIP","journal":"Research (Washington, D.C.)","confidence":"High","confidence_rationale":"Tier 2 — Co-IP/MS identification of interaction, site-specific K63 ubiquitination mapping at K377, cardiomyocyte-specific KO mouse with survival/death readouts","pmids":["40822127"],"is_preprint":false},{"year":2025,"finding":"USP53 interacts with and deubiquitinates NOTCH2 in microglia; USP53 knockout reduces Aβ-induced NOTCH2 deubiquitination, suppresses IKKβ/NFκB signaling, reduces neuroinflammatory mediators (IL-1β, TNF-α), and improves learning/memory in 5XFAD Alzheimer's disease mice.","method":"Co-immunoprecipitation, USP53 knockout in 5XFAD mice, Morris Water Maze, western blot, immunofluorescence, qRT-PCR","journal":"Neurochemistry international","confidence":"Medium","confidence_rationale":"Tier 2/3 — Co-IP plus in vivo KO with functional readouts, single lab","pmids":["41482165"],"is_preprint":false},{"year":2025,"finding":"USP53 deubiquitinates MORF4L1 at K249 and K227, preventing its ubiquitination and proteasomal degradation, thereby suppressing colorectal cancer cell proliferation; MORF4L1 overexpression rescues the pro-tumorigenic effects of USP53 silencing.","method":"Immunoprecipitation–LC/MS (ubiquitylome), Co-IP, ubiquitination assay with site identification (K249, K227), gain/loss-of-function experiments, xenograft","journal":"Biochimica et biophysica acta. Molecular basis of disease","confidence":"Medium","confidence_rationale":"Tier 2 — IP-MS substrate identification, site-specific ubiquitination mapping, rescue experiment, single lab","pmids":["41061828"],"is_preprint":false},{"year":2025,"finding":"USP53 deubiquitinates SMAD5 to stabilize its protein expression in bone marrow stromal cells, promoting their viability, invasion, and osteogenic differentiation; EIF4A3 stabilizes USP53 mRNA to maintain USP53 protein levels, forming an EIF4A3-USP53-SMAD5 regulatory axis.","method":"Co-immunoprecipitation, western blot, knockdown/overexpression experiments, ALP activity assay, Alizarin red staining, qRT-PCR","journal":"Scientific reports","confidence":"Low","confidence_rationale":"Tier 3 — Co-IP plus functional knockdown/rescue in single lab with no in vivo validation","pmids":["40481141"],"is_preprint":false},{"year":2025,"finding":"FOS transcription factor directly regulates USP53 expression; juglone suppresses FOS, downregulating USP53, which reduces USP53-dependent deubiquitination of MLKL and GSDMD, promoting their ubiquitination and degradation and thereby alleviating necroptosis and pyroptosis in injured neurons.","method":"RNA-seq, immunoprecipitation, western blot, qRT-PCR, ChIP-qPCR, OGD/R neuronal model, in vivo spinal cord injury model","journal":"Phytomedicine","confidence":"Medium","confidence_rationale":"Tier 2/3 — ChIP-qPCR for FOS-USP53 promoter binding, Co-IP, in vivo model; single lab","pmids":["41045624"],"is_preprint":false},{"year":2025,"finding":"ATF3 transcriptionally represses USP53 by binding its promoter; USP53 promotes adipogenesis and activates the RhoA/ROCK signaling pathway; ATF3-mediated USP53 repression inhibits adipocyte differentiation of 3T3-L1 cells.","method":"ChIP assay, luciferase reporter assay, Oil Red O staining, triglyceride measurement, western blot (RhoA/ROCK pathway), ATF3 and USP53 overexpression/knockdown","journal":"Journal of molecular endocrinology","confidence":"Medium","confidence_rationale":"Tier 2 — ChIP and luciferase reporter validate promoter binding; functional adipogenesis assays, single lab","pmids":["39641389"],"is_preprint":false}],"current_model":"USP53 is an active deubiquitinase with high selectivity for K63-linked polyubiquitin chains (overturning its prior annotation as a catalytically inactive pseudo-enzyme), whose USP domain harbors K63-specific S2-ubiquitin-binding sites; it physically associates with and deubiquitinates multiple substrates including TJP1/TJP2 (maintaining tight junction integrity in the inner ear and liver), MYO5B (regulating BSEP trafficking to the canalicular membrane), FKBP51 (suppressing AKT1 signaling), cytochrome c (promoting apoptosis), RIPK1 (controlling K63-ubiquitination-dependent necroptosis/apoptosis at K377), NOTCH2, CRKL, ZMYND11, MORF4L1, SMAD5, and SR-A, while in bone it enhances VDR-SMAD3 interaction to suppress RANKL expression, collectively establishing USP53 as a multifunctional K63-linkage-directed DUB that regulates bile acid secretion, tight junction integrity, cell death, bone homeostasis, and tumor suppression across multiple tissues."},"narrative":{"teleology":[{"year":2015,"claim":"Forward genetics revealed that USP53 — then annotated as a catalytically dead pseudo-DUB — physically associates with tight junction scaffolds TJP1/TJP2 and is essential for auditory hair cell survival and endocochlear potential maintenance, establishing it as a functional component of epithelial tight junctions.","evidence":"ENU mutagenesis (mambo mouse), reciprocal Co-IP, colocalization imaging, cochlear organotypic cultures, biotin tracer assay","pmids":["26609154"],"confidence":"High","gaps":["Catalytic activity was not tested and assumed absent","The mechanism by which USP53 supports tight junction integrity was unknown","No liver or bone phenotype examined"]},{"year":2018,"claim":"Human genetics linked biallelic USP53 truncating variants to low-GGT intrahepatic cholestasis and hearing loss, extending USP53's tight-junction role from the inner ear to hepatocytes and establishing a Mendelian disease association.","evidence":"Exome sequencing and segregation analysis in multiple families","pmids":["30250217"],"confidence":"Medium","gaps":["No biochemical or cell-biological experiments in this study","Mechanism linking USP53 loss to cholestasis was unresolved","No animal model of liver phenotype"]},{"year":2020,"claim":"USP53 was shown to deubiquitinate specific substrates — FKBP51 (suppressing AKT1/glycolysis in lung adenocarcinoma) and cytochrome c (promoting apoptosis in HCC) — establishing that it functions as an active deubiquitinase with tumor-suppressive roles, contradicting its pseudo-enzyme annotation.","evidence":"Co-IP, ubiquitination assays, cycloheximide chase, GSEA, in vivo xenograft, rescue experiments","pmids":["32511815","35654790"],"confidence":"Medium","gaps":["Linkage specificity (K48 vs K63) not resolved","No in vitro reconstitution of catalytic activity","Single-lab observations without structural confirmation of active site"]},{"year":2020,"claim":"Ultrastructural analysis of USP53-mutant patient livers revealed elongated hepatocyte tight junctions, providing direct morphological evidence that USP53 regulates tight junction architecture in human liver.","evidence":"Transmission electron microscopy of liver biopsies from patients with biallelic USP53 variants","pmids":["32124521"],"confidence":"Medium","gaps":["Mechanism of junction elongation unclear","No molecular targets identified in this study","Small patient cohort"]},{"year":2021,"claim":"USP53 was placed downstream of PTH/NACA signaling in osteoblasts; its knockdown promoted osteoblast over adipocyte commitment, revealing a role in mesenchymal lineage determination.","evidence":"ChIP-seq, EMSA, luciferase reporter, shRNA knockdown in ST2 stromal cells, in vivo implantation","pmids":["33875709"],"confidence":"High","gaps":["No DUB substrates identified in bone context at this point","No Usp53 knockout bone phenotype yet reported"]},{"year":2023,"claim":"Usp53-null mice exhibited low bone mass and elevated RANKL due to loss of USP53-mediated enhancement of VDR–SMAD3 interaction, revealing a specific molecular mechanism for USP53's role in osteoblast-osteoclast coupling.","evidence":"Usp53 knockout mice, micro-CT, histomorphometry, serum RANKL ELISA, VDR–SMAD3 Co-IP","pmids":["36726200"],"confidence":"High","gaps":["Whether USP53 directly deubiquitinates VDR or SMAD3 was not tested","Bone phenotype rescue not demonstrated","Contribution of adipocyte vs osteoblast compartment not dissected"]},{"year":2024,"claim":"Liver-specific Usp53 knockout confirmed that hepatic USP53 interacts with TJP2 and regulates tight junction length and bile acid transporter expression (BSEP/NTCP/MRP2), providing a mechanistic bridge between tight junction biology and cholestasis.","evidence":"Alb-cre × Usp53fl/fl mice, Co-IP, immunofluorescence, electron microscopy, DDC dietary challenge","pmids":["39705897"],"confidence":"High","gaps":["Whether USP53 directly deubiquitinates TJP2 or another junction component unclear","Compensatory mechanisms in liver-specific KO not defined"]},{"year":2024,"claim":"Biochemical reconstitution overturned the pseudo-enzyme annotation: USP53 is an active deubiquitinase with high selectivity for K63-linked polyubiquitin, with structural K63-specific S2-ubiquitin-binding sites, and patient-associated mutations abolish catalytic activity.","evidence":"(preprint) In vitro DUB assays, structural analysis, site-directed mutagenesis of patient variants, K63-ubiquitination profiling of tricellular junction components","pmids":["bio_10.1101_2024.07.07.602376"],"confidence":"High","gaps":["Awaits peer review","Full crystal/cryo-EM structure not yet deposited","In vivo validation of K63-selectivity for specific substrates needed"]},{"year":2024,"claim":"USP53 was shown to deubiquitinate SR-A via its USP domain (Cys41-dependent) removing K48-linked ubiquitin, promoting foam cell formation during atherosclerosis — notably demonstrating K48-directed activity alongside the predominant K63 specificity.","evidence":"Co-IP, Cys41 mutagenesis, ChIP, AAV-SMC-specific OE in DKK1ECKO/APOE−/− mice, parallel-plate co-culture","pmids":["38904030"],"confidence":"High","gaps":["Apparent K48 activity on SR-A conflicts with predominant K63 selectivity; reconciliation needed","Single disease context (atherosclerosis)"]},{"year":2025,"claim":"The cholestasis mechanism was resolved at the trafficking level: USP53 loss causes MYO5B hyperubiquitination and BSEP mistrafficking to recycling endosomes; USP53 binds the MYO5B IQ domain, and a cholestasis-associated MYO5B variant disrupts this interaction.","evidence":"CRISPR KO, surface biotinylation, FRAP, Co-IP with mutagenesis, confocal imaging in patient tissue","pmids":["40828662"],"confidence":"High","gaps":["Ubiquitin linkage type on MYO5B not specified","Whether USP53 regulates other apical transporters via MYO5B not tested"]},{"year":2025,"claim":"USP53 was shown to remove K63-ubiquitin from RIPK1 at K377, licensing RIPK1 autophosphorylation and triggering necroptosis/apoptosis in cardiomyocytes, expanding USP53's cell death regulatory repertoire beyond cytochrome c and FKBP51.","evidence":"Co-IP/LC-MS/MS, site-specific K63-ubiquitination mapping, cardiomyocyte-specific USP53 KO mice with alcohol feeding","pmids":["40822127"],"confidence":"High","gaps":["Whether RIPK1-K377 deubiquitination by USP53 occurs in non-cardiac tissues unknown","Kinetics and regulation of USP53 recruitment to complex I/II not defined"]},{"year":2025,"claim":"Additional substrates were identified — NOTCH2 (microglia/neuroinflammation), MORF4L1 (colorectal cancer), ZMYND11 (breast cancer), and SMAD5 (osteogenic differentiation) — broadening the substrate repertoire and reinforcing USP53's role as a multi-tissue DUB acting on both signaling and chromatin-associated proteins.","evidence":"Co-IP, ubiquitination assays with site mapping (K249/K227 for MORF4L1), domain mutagenesis (Cys-box for ZMYND11), xenografts, in vivo KO (5XFAD mice for NOTCH2)","pmids":["41482165","41061828","39044157","40481141"],"confidence":"Medium","gaps":["Substrate prioritization unclear — which are physiologically dominant","K63 vs K48 linkage not determined for all new substrates","SMAD5 result from single lab without in vivo validation"]},{"year":null,"claim":"How USP53 achieves substrate selectivity across such diverse targets, whether its K63 selectivity is absolute or context-dependent (given reported K48 activity on SR-A), and the structural basis for substrate recognition outside the catalytic domain remain open questions.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No high-resolution structure of USP53 bound to a substrate or ubiquitin chain","Systematic profiling of linkage preference across substrates not performed","Tissue-specific regulation of USP53 expression and activation incompletely mapped"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[2,5,9,10,12,13,14,15,16,17,18]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[12,14]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,3,11,13]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[5,13]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[13]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[10,16]}],"pathway":[{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[2,5,14,18]},{"term_id":"R-HSA-382551","term_label":"Transport of small molecules","supporting_discovery_ids":[1,11,13]},{"term_id":"R-HSA-1500931","term_label":"Cell-Cell communication","supporting_discovery_ids":[0,3,11,12]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[2,6,15]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[1,9,15]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[12,14,16]}],"complexes":[],"partners":["TJP2","TJP1","MYO5B","RIPK1","FKBP51","ZMYND11","MORF4L1","NOTCH2"],"other_free_text":[]},"mechanistic_narrative":"USP53 is a K63-linkage-selective deubiquitinase that operates at the intersection of tight junction maintenance, bile acid secretion, cell death signaling, bone homeostasis, and tumor suppression across multiple tissues. Despite its prior annotation as a catalytically inactive pseudo-DUB, USP53 harbors an active USP domain with K63-specific S2-ubiquitin-binding sites and deubiquitinates diverse substrates including TJP1/TJP2 (tight junction scaffolding), MYO5B (BSEP trafficking to the canalicular membrane), RIPK1 (K63-deubiquitination at K377 triggering necroptosis/apoptosis), cytochrome c (apoptosis), FKBP51 (AKT1 suppression), NOTCH2 (NF-κB signaling in microglia), MORF4L1, ZMYND11, SMAD5, and SR-A [PMID:26609154, PMID:40828662, PMID:40822127, PMID:35654790, PMID:39044157, PMID:38904030]. In bone, USP53 enhances VDR–SMAD3 interaction to suppress RANKL, coupling osteoblast and osteoclast activity, and Usp53-null mice display low bone mass [PMID:36726200]. Biallelic loss-of-function variants in USP53 cause low-GGT intrahepatic cholestasis with sensorineural hearing loss, reflecting its essential roles in hepatocyte tight junction integrity and bile transporter expression [PMID:30250217, PMID:39705897]."},"prefetch_data":{"uniprot":{"accession":"Q70EK8","full_name":"Ubiquitin carboxyl-terminal hydrolase 53","aliases":["Ubiquitin-specific peptidase 53"],"length_aa":1073,"mass_kda":120.8,"function":"Deubiquitinase that mediates 'Lys-63'-linked deubiquitination of tight junction proteins, such as MARVELD2 and LSR, and which is involved in the survival of auditory hair cells and hearing (PubMed:32124521, PubMed:39587316). Specifically cleaves 'Lys-63'-linked polyubiquitin chains composed of at least 3 ubiquitin molecules, while it is not able to deubiquitinate substrates with shorter ubiquitin chains: recognizes ubiquitin chain in position S2 and catalyzes en bloc cleavage of polyubiquitin chains from substrate proteins (PubMed:39587316). Probably acts by modulating the barrier properties and mechanical stability of tight junctions via deubiquitination of MARVELD2 and LSR (PubMed:32124521, PubMed:39587316)","subcellular_location":"Cell junction, tight junction","url":"https://www.uniprot.org/uniprotkb/Q70EK8/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/USP53","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/USP53","total_profiled":1310},"omim":[{"mim_id":"621016","title":"NEURODEVELOPMENTAL DISORDER WITH VARIABLE FAMILIAL HYPERCHOLANEMIA; NEDFHCA","url":"https://www.omim.org/entry/621016"},{"mim_id":"619662","title":"CHOLESTASIS, PROGRESSIVE FAMILIAL INTRAHEPATIC, 8; PFIC8","url":"https://www.omim.org/entry/619662"},{"mim_id":"619658","title":"CHOLESTASIS, PROGRESSIVE FAMILIAL INTRAHEPATIC, 7, WITH OR WITHOUT HEARING LOSS; PFIC7","url":"https://www.omim.org/entry/619658"},{"mim_id":"619309","title":"PROTEIN PHOSPHATASE, MAGNESIUM/MANGANESE-DEPENDENT, 1F; PPM1F","url":"https://www.omim.org/entry/619309"},{"mim_id":"618474","title":"WDR83 OPPOSITE STRAND; WDR83OS","url":"https://www.omim.org/entry/618474"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Plasma membrane","reliability":"Approved"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in many","driving_tissues":[],"url":"https://www.proteinatlas.org/search/USP53"},"hgnc":{"alias_symbol":["KIAA1350"],"prev_symbol":[]},"alphafold":{"accession":"Q70EK8","domains":[{"cath_id":"3.90.70.10","chopping":"32-373","consensus_level":"medium","plddt":93.6438,"start":32,"end":373}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q70EK8","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q70EK8-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q70EK8-F1-predicted_aligned_error_v6.png","plddt_mean":55.06},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=USP53","jax_strain_url":"https://www.jax.org/strain/search?query=USP53"},"sequence":{"accession":"Q70EK8","fasta_url":"https://rest.uniprot.org/uniprotkb/Q70EK8.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q70EK8/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q70EK8"}},"corpus_meta":[{"pmid":"30250217","id":"PMC_30250217","title":"Identification of novel loci for pediatric cholestatic liver disease defined by KIF12, PPM1F, USP53, LSR, and WDR83OS pathogenic variants.","date":"2018","source":"Genetics in medicine : official journal of the American College of Medical Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/30250217","citation_count":85,"is_preprint":false},{"pmid":"26609154","id":"PMC_26609154","title":"Progressive Hearing Loss in Mice Carrying a Mutation in Usp53.","date":"2015","source":"The Journal of neuroscience : the official journal of the Society for Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/26609154","citation_count":56,"is_preprint":false},{"pmid":"32124521","id":"PMC_32124521","title":"Low-GGT intrahepatic cholestasis associated with biallelic USP53 variants: Clinical, histological and ultrastructural characterization.","date":"2020","source":"Liver international : official journal of the International Association for the Study of the Liver","url":"https://pubmed.ncbi.nlm.nih.gov/32124521","citation_count":41,"is_preprint":false},{"pmid":"32511815","id":"PMC_32511815","title":"USP53 promotes apoptosis and inhibits glycolysis in lung adenocarcinoma through FKBP51-AKT1 signaling.","date":"2020","source":"Molecular carcinogenesis","url":"https://pubmed.ncbi.nlm.nih.gov/32511815","citation_count":31,"is_preprint":false},{"pmid":"33075013","id":"PMC_33075013","title":"Cholestasis Due to USP53 Deficiency.","date":"2021","source":"Journal of pediatric gastroenterology and nutrition","url":"https://pubmed.ncbi.nlm.nih.gov/33075013","citation_count":29,"is_preprint":false},{"pmid":"32759993","id":"PMC_32759993","title":"New paradigms of USP53 disease: normal GGT cholestasis, BRIC, cholangiopathy, and responsiveness to rifampicin.","date":"2020","source":"Journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/32759993","citation_count":29,"is_preprint":false},{"pmid":"36726200","id":"PMC_36726200","title":"USP53 Regulates Bone Homeostasis by Controlling Rankl Expression in Osteoblasts and Bone Marrow Adipocytes.","date":"2023","source":"Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research","url":"https://pubmed.ncbi.nlm.nih.gov/36726200","citation_count":20,"is_preprint":false},{"pmid":"35654790","id":"PMC_35654790","title":"USP53 plays an antitumor role in hepatocellular carcinoma through deubiquitination of cytochrome c.","date":"2022","source":"Oncogenesis","url":"https://pubmed.ncbi.nlm.nih.gov/35654790","citation_count":19,"is_preprint":false},{"pmid":"33875709","id":"PMC_33875709","title":"Ubiquitin specific peptidase Usp53 regulates osteoblast versus adipocyte lineage commitment.","date":"2021","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/33875709","citation_count":16,"is_preprint":false},{"pmid":"34919659","id":"PMC_34919659","title":"USP53 activated by H3K27 acetylation regulates cell viability, apoptosis and metabolism in esophageal carcinoma via the AMPK signaling pathway.","date":"2022","source":"Carcinogenesis","url":"https://pubmed.ncbi.nlm.nih.gov/34919659","citation_count":13,"is_preprint":false},{"pmid":"33661244","id":"PMC_33661244","title":"Progressive Familial Intrahepatic Cholestasis Associated With USP53 Gene Mutation in a Brazilian Child.","date":"2021","source":"Journal of pediatric gastroenterology and nutrition","url":"https://pubmed.ncbi.nlm.nih.gov/33661244","citation_count":11,"is_preprint":false},{"pmid":"34809518","id":"PMC_34809518","title":"Biallelic Mutations in Ubiquitin-Specific Peptidase 53 (USP53) Causing Progressive Intrahepatic Cholestasis. Report of a Case With Review of Literature.","date":"2021","source":"Pediatric and developmental pathology : the official journal of the Society for Pediatric Pathology and the Paediatric Pathology Society","url":"https://pubmed.ncbi.nlm.nih.gov/34809518","citation_count":9,"is_preprint":false},{"pmid":"34681012","id":"PMC_34681012","title":"A Two-Year Clinical Description of a Patient with a Rare Type of Low-GGT Cholestasis Caused by a Novel Variant of USP53.","date":"2021","source":"Genes","url":"https://pubmed.ncbi.nlm.nih.gov/34681012","citation_count":9,"is_preprint":false},{"pmid":"39300775","id":"PMC_39300775","title":"An Overview of the Deubiquitinase USP53: A Promising Diagnostic Marker and Therapeutic Target.","date":"2024","source":"Current protein & peptide science","url":"https://pubmed.ncbi.nlm.nih.gov/39300775","citation_count":8,"is_preprint":false},{"pmid":"36660033","id":"PMC_36660033","title":"Biallelic Novel USP53 Splicing Variant Disrupting the Gene Function that Causes Cholestasis Phenotype and Review of the Literature.","date":"2022","source":"Molecular syndromology","url":"https://pubmed.ncbi.nlm.nih.gov/36660033","citation_count":8,"is_preprint":false},{"pmid":"39044157","id":"PMC_39044157","title":"USP53 Affects the Proliferation and Apoptosis of Breast Cancer Cells by Regulating the Ubiquitination Level of ZMYND11.","date":"2024","source":"Biological procedures online","url":"https://pubmed.ncbi.nlm.nih.gov/39044157","citation_count":8,"is_preprint":false},{"pmid":"38904030","id":"PMC_38904030","title":"Endothelial Dickkopf-1 Promotes Smooth Muscle Cell-derived Foam Cell Formation via USP53-mediated Deubiquitination of SR-A During Atherosclerosis.","date":"2024","source":"International journal of biological sciences","url":"https://pubmed.ncbi.nlm.nih.gov/38904030","citation_count":7,"is_preprint":false},{"pmid":"37894400","id":"PMC_37894400","title":"USP53 Exerts Tumor-Promoting Effects in Triple-Negative Breast Cancer by Deubiquitinating CRKL.","date":"2023","source":"Cancers","url":"https://pubmed.ncbi.nlm.nih.gov/37894400","citation_count":4,"is_preprint":false},{"pmid":"39705897","id":"PMC_39705897","title":"Loss of hepatocyte Usp53 protects mice from a form of xenobiotic-induced liver injury.","date":"2024","source":"Biochimica et biophysica acta. Molecular basis of disease","url":"https://pubmed.ncbi.nlm.nih.gov/39705897","citation_count":3,"is_preprint":false},{"pmid":"37895270","id":"PMC_37895270","title":"Genome Sequencing of Consanguineous Family Implicates Ubiquitin-Specific Protease 53 (USP53) Variant in Psychosis/Schizophrenia: Wild-Type Expression in Murine Hippocampal CA 1-3 and Granular Dentate with AMPA Synapse Interactions.","date":"2023","source":"Genes","url":"https://pubmed.ncbi.nlm.nih.gov/37895270","citation_count":3,"is_preprint":false},{"pmid":"41045624","id":"PMC_41045624","title":"Juglone promotes spinal cord injury recovery by suppressing pyroptosis and necroptosis through FOS/USP53/ubiquitination.","date":"2025","source":"Phytomedicine : international journal of phytotherapy and phytopharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/41045624","citation_count":2,"is_preprint":false},{"pmid":"38204320","id":"PMC_38204320","title":"A novel homozygous mutation in the USP53 gene as the cause of benign recurrent intrahepatic cholestasis in children: a case report.","date":"2023","source":"The Turkish journal of pediatrics","url":"https://pubmed.ncbi.nlm.nih.gov/38204320","citation_count":2,"is_preprint":false},{"pmid":"39440620","id":"PMC_39440620","title":"Natural course and outcomes of children with ubiquitin-specific protease 53 (USP53)-related genetic chronic cholestasis.","date":"2024","source":"Journal of pediatric gastroenterology and nutrition","url":"https://pubmed.ncbi.nlm.nih.gov/39440620","citation_count":2,"is_preprint":false},{"pmid":"38544763","id":"PMC_38544763","title":"Cholestatic Liver Disease due to Novel USP53 Mutations: A Case Series of Three Indian Children.","date":"2023","source":"Journal of clinical and experimental hepatology","url":"https://pubmed.ncbi.nlm.nih.gov/38544763","citation_count":2,"is_preprint":false},{"pmid":"40822127","id":"PMC_40822127","title":"USP53 Drives Ethanol-Induced Myocardial Injury by Promoting K63 Deubiquitination-Dependent RIPK1 Activation at K377.","date":"2025","source":"Research (Washington, D.C.)","url":"https://pubmed.ncbi.nlm.nih.gov/40822127","citation_count":2,"is_preprint":false},{"pmid":"40481141","id":"PMC_40481141","title":"EIF4A3 enhances the viability, invasion and osteogenic differentiation of BMSCs via the USP53/SMAD5 pathway.","date":"2025","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/40481141","citation_count":1,"is_preprint":false},{"pmid":"37992747","id":"PMC_37992747","title":"The First Korean Adult Case of Progressive Familial Intrahepatic Cholestasis Type 7 with Novel USP53 Splicing Variants by Next Generation Sequencing.","date":"2023","source":"Yonsei medical journal","url":"https://pubmed.ncbi.nlm.nih.gov/37992747","citation_count":1,"is_preprint":false},{"pmid":"40828662","id":"PMC_40828662","title":"A novel mechanism involving USP53-regulated BSEP trafficking underlies low-GGT intrahepatic cholestasis.","date":"2025","source":"Hepatology (Baltimore, Md.)","url":"https://pubmed.ncbi.nlm.nih.gov/40828662","citation_count":0,"is_preprint":false},{"pmid":"39641389","id":"PMC_39641389","title":"ATF3 suppresses 3T3-L1 adipocyte adipogenesis by transcriptionally repressing USP53.","date":"2025","source":"Journal of molecular endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/39641389","citation_count":0,"is_preprint":false},{"pmid":"41356217","id":"PMC_41356217","title":"Case Report: Mild BRIC-like cholestasis despite a gross USP53 deletion-novel findings and literature review.","date":"2025","source":"Frontiers in genetics","url":"https://pubmed.ncbi.nlm.nih.gov/41356217","citation_count":0,"is_preprint":false},{"pmid":"39071191","id":"PMC_39071191","title":"A novel case report of benign recurrent intrahepatic cholestasis-associated USP53 genetic mutation in a Pakistani girl.","date":"2024","source":"SAGE open medical case reports","url":"https://pubmed.ncbi.nlm.nih.gov/39071191","citation_count":0,"is_preprint":false},{"pmid":"41482165","id":"PMC_41482165","title":"USP53 promotes NOTCH2-induced neuroinflammation in Alzheimer's disease.","date":"2025","source":"Neurochemistry international","url":"https://pubmed.ncbi.nlm.nih.gov/41482165","citation_count":0,"is_preprint":false},{"pmid":"41061828","id":"PMC_41061828","title":"Deubiquitinase USP53 suppressed tumorigenesis of colorectal cancer cells by mediating deubiquitination of MORF4L1.","date":"2025","source":"Biochimica et biophysica acta. Molecular basis of disease","url":"https://pubmed.ncbi.nlm.nih.gov/41061828","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.07.07.602376","title":"Discovery and mechanism of K63-linkage-directed deubiquitinase activity in USP53","date":"2024-07-07","source":"bioRxiv","url":"https://doi.org/10.1101/2024.07.07.602376","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":18653,"output_tokens":5165,"usd":0.066717},"stage2":{"model":"claude-opus-4-6","input_tokens":8678,"output_tokens":3521,"usd":0.197123},"total_usd":0.26384,"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\": 2015,\n      \"finding\": \"USP53 contains a catalytically inactive ubiquitin-specific protease domain (annotated as pseudo-enzyme) and colocalizes and physically interacts with tight junction scaffolding proteins TJP1 and TJP2 in polarized epithelial cells, placing USP53 as a component of the tight junction complex essential for auditory hair cell survival.\",\n      \"method\": \"Co-immunoprecipitation, colocalization imaging, forward genetics (ENU mutagenesis mambo mouse line), cochlear organotypic cultures, biotin tracer assay, electrophysiology (endocochlear potential measurement)\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP plus functional rescue in organotypic culture, replicated in vivo genetic model\",\n      \"pmids\": [\"26609154\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"USP53 was identified as an interactor of TJP2, and homozygous truncating variants in USP53 cause low-GGT intrahepatic cholestasis and hearing loss, linking USP53 function to tight junction integrity in the liver and inner ear.\",\n      \"method\": \"Exome sequencing, positional mapping, human genetics (segregation analysis)\",\n      \"journal\": \"Genetics in medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — genetic association with referenced TJP2 interaction; no independent biochemical assay in this paper\",\n      \"pmids\": [\"30250217\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"USP53 deubiquitinates FKBP51, stabilizing it; FKBP51 in turn dephosphorylates AKT1, thereby suppressing AKT1 pathway activity, inhibiting glycolysis, and promoting apoptosis in lung adenocarcinoma cells.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, stable overexpression/shRNA knockdown, AKT pathway inhibitor (LY294002), in vivo xenograft\",\n      \"journal\": \"Molecular carcinogenesis\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2/3 — Co-IP plus ubiquitination assay plus rescue experiment in single lab\",\n      \"pmids\": [\"32511815\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Ultrastructural study of liver biopsies from patients with USP53 mutations revealed elongated hepatocyte-hepatocyte tight junctions, implicating USP53 in tight junction structure/length regulation in hepatocytes.\",\n      \"method\": \"Transmission electron microscopy of liver biopsies from patients with biallelic USP53 variants\",\n      \"journal\": \"Liver international\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct ultrastructural observation in human disease tissue, consistent across multiple patients\",\n      \"pmids\": [\"32124521\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"USP53 is identified as a target gene of PTH-activated NACA in osteoblasts; NACA binds the USP53 promoter (confirmed by EMSA), and USP53 promoter activity is regulated by the JUN-CREB complex via activated PKA and NACA. Usp53 knockdown in stromal cells promotes osteoblast markers and inhibits adipogenic markers, establishing a role in mesenchymal lineage commitment.\",\n      \"method\": \"ChIP-seq, RNA-seq, EMSA, luciferase reporter assay, shRNA knockdown in ST2 stromal cells, in vivo implantation of knockdown cells in immunocompromised mice\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (ChIP, EMSA, reporter, in vivo), single lab\",\n      \"pmids\": [\"33875709\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"USP53 interacts with cytochrome c (CYCS) and deubiquitinates it, increasing CYCS stability; overexpression of CYCS rescues the decreased apoptosis caused by USP53 knockdown in hepatocellular carcinoma cells, establishing a USP53-CYCS apoptotic axis.\",\n      \"method\": \"Co-immunoprecipitation, mass spectrometry, cycloheximide chase assay, GSEA, rescue experiment with CYCS overexpression\",\n      \"journal\": \"Oncogenesis\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2/3 — Co-IP plus mass spectrometry identification plus functional rescue, single lab\",\n      \"pmids\": [\"35654790\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"USP53 regulates RANKL expression by enhancing the interaction between VDR and SMAD3 in osteoblasts and bone marrow adipocytes; Usp53 null mice display low bone mass, increased osteoclastogenesis, and elevated serum RANKL, establishing USP53 as a regulator of osteoblast-osteoclast coupling.\",\n      \"method\": \"Usp53 knockout mice, micro-CT (trabecular and cortical bone quantification), histomorphometry, serum RANKL ELISA, mechanistic interaction assay (VDR-SMAD3 co-immunoprecipitation)\",\n      \"journal\": \"Journal of bone and mineral research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — in vivo knockout with multiple quantitative readouts plus mechanistic Co-IP, single lab\",\n      \"pmids\": [\"36726200\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"USP53 directly binds and deubiquitinates CRKL to stabilize it, thereby promoting TNBC cell proliferation, migration, invasion, EMT, and chemoresistance.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, gain/loss-of-function cell experiments\",\n      \"journal\": \"Cancers\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — single Co-IP plus ubiquitination assay in single lab, no structural validation\",\n      \"pmids\": [\"37894400\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"USP53 localizes to hippocampal CA1-3 regions and granular dentate, and co-immunoprecipitates with GRIA2/GluA2 (AMPA receptor subunit) and GRIP2, placing USP53 within the AMPA receptor interactome in the brain.\",\n      \"method\": \"Immunofluorescence (co-localization with GRIA2/GluA2 and GRIP2 antibodies), co-immunoprecipitation\",\n      \"journal\": \"Genes\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — single Co-IP with limited mechanistic follow-up, single lab\",\n      \"pmids\": [\"37895270\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"USP53 binds SR-A via its USP domain (requiring Cys41) and removes K48-linked ubiquitin chains from SR-A, preventing its proteasomal degradation and thereby promoting foam cell formation in smooth muscle cells during atherosclerosis. DKK1 regulates USP53 transcription by facilitating CREB binding to the USP53 promoter.\",\n      \"method\": \"Co-immunoprecipitation, RNA-seq, site-directed mutagenesis (Cys41), ChIP, adeno-associated virus SMC-specific overexpression in DKK1ECKO/APOE-/- mice, parallel-plate co-culture flow system, endothelium-specific KO and OE mouse models\",\n      \"journal\": \"International journal of biological sciences\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods including mutagenesis, in vivo mouse models, Co-IP; single lab\",\n      \"pmids\": [\"38904030\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"USP53 interacts with ZMYND11 and catalyzes its deubiquitination and stabilization; the 33–50 amino acid Cys-box domain is required for USP53 enzymatic activity but not for ZMYND11 binding; USP53-mediated stabilization of ZMYND11 mediates USP53's anti-tumor effects in breast cancer.\",\n      \"method\": \"Co-immunoprecipitation, domain deletion/mutagenesis (Cys-box), ubiquitination assay, rescue experiments with ZMYND11 overexpression, xenograft\",\n      \"journal\": \"Biological procedures online\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP plus domain mutagenesis plus rescue, single lab\",\n      \"pmids\": [\"39044157\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"USP53 interacts with TJP2 in hepatocytes (confirmed by co-immunoprecipitation and co-immunofluorescence); loss of hepatic USP53 causes upregulation of Tjp2 mRNA, lengthening of hepatocellular tight junctions, and downregulation of bile acid transporters (Abcb11, Ntcp, Abcc2), protecting mice from DDC-induced liver injury.\",\n      \"method\": \"Usp53 liver-specific knockout mice (Alb-cre × Usp53fl/fl), co-immunoprecipitation, immunofluorescence, electron microscopy (tight junction length), qRT-PCR, dietary challenge (DDC)\",\n      \"journal\": \"Biochimica et biophysica acta. Molecular basis of disease\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — liver-specific KO with multiple functional readouts plus Co-IP; mechanistically links USP53 to TJP2 and BSEP transporter regulation\",\n      \"pmids\": [\"39705897\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"USP53 and USP54, previously annotated as catalytically inactive pseudo-DUBs, are in fact active deubiquitinases with high selectivity for K63-linked polyubiquitin chains. USP53 can deubiquitinate a substrate in a K63-linkage-dependent manner. Patient-associated mutations in the USP domain of USP53 abrogate this catalytic activity. Depletion of USP53 increases K63-linked ubiquitination of tricellular junction components. Structural analyses identified K63-specific S2-ubiquitin-binding sites within the catalytic domain.\",\n      \"method\": \"Biochemical in vitro DUB activity assays, structural analysis, site-directed mutagenesis of patient variants, K63-linkage-specific ubiquitin chain assays, mass spectrometry, depletion of USP53 followed by K63-ubiquitination profiling of tricellular junction components\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution of enzymatic activity, structural analysis, mutagenesis of active site with patient variants, and substrate-level K63-ubiquitination profiling in single preprint\",\n      \"pmids\": [\"bio_10.1101_2024.07.07.602376\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Loss of USP53 causes mislocalization of the bile salt export pump (BSEP) to MYO5B-positive and RAB11A-positive recycling endosomes, impairing BSEP trafficking to the plasma membrane. USP53 colocalizes with MYO5B and interacts with its IQ domain; the cholestasis-associated MYO5B p.(Arg824Cys) variant (located in the IQ domain) fails to interact with USP53. Loss of USP53 increases ubiquitination of MYO5B and disrupts its endosomal recruitment.\",\n      \"method\": \"Immunohistochemistry of patient tissue, confocal immunofluorescence, surface protein biotinylation, siRNA knockdown, CRISPR-Cas9 knockout, site-directed mutagenesis, co-immunoprecipitation, live cell imaging, FRAP\",\n      \"journal\": \"Hepatology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1/2 — multiple orthogonal methods including CRISPR KO, surface biotinylation, FRAP, co-IP with mutagenesis validation in patient-derived tissue\",\n      \"pmids\": [\"40828662\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"USP53 interacts with the intermediate domain of RIPK1 and removes K63-linked ubiquitin chains at RIPK1 lysine-377, facilitating RIPK1 autophosphorylation and triggering downstream apoptotic and necroptotic pathways in cardiomyocytes during ethanol-induced injury. USP53 transcription is induced by EGR1 in response to ethanol.\",\n      \"method\": \"Co-immunoprecipitation combined with LC-MS/MS, site-specific ubiquitination mapping, cardiomyocyte-specific USP53 knockout (USP53CKO) mice, in vivo alcohol feeding model, western blot, ChIP\",\n      \"journal\": \"Research (Washington, D.C.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP/MS identification of interaction, site-specific K63 ubiquitination mapping at K377, cardiomyocyte-specific KO mouse with survival/death readouts\",\n      \"pmids\": [\"40822127\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"USP53 interacts with and deubiquitinates NOTCH2 in microglia; USP53 knockout reduces Aβ-induced NOTCH2 deubiquitination, suppresses IKKβ/NFκB signaling, reduces neuroinflammatory mediators (IL-1β, TNF-α), and improves learning/memory in 5XFAD Alzheimer's disease mice.\",\n      \"method\": \"Co-immunoprecipitation, USP53 knockout in 5XFAD mice, Morris Water Maze, western blot, immunofluorescence, qRT-PCR\",\n      \"journal\": \"Neurochemistry international\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2/3 — Co-IP plus in vivo KO with functional readouts, single lab\",\n      \"pmids\": [\"41482165\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"USP53 deubiquitinates MORF4L1 at K249 and K227, preventing its ubiquitination and proteasomal degradation, thereby suppressing colorectal cancer cell proliferation; MORF4L1 overexpression rescues the pro-tumorigenic effects of USP53 silencing.\",\n      \"method\": \"Immunoprecipitation–LC/MS (ubiquitylome), Co-IP, ubiquitination assay with site identification (K249, K227), gain/loss-of-function experiments, xenograft\",\n      \"journal\": \"Biochimica et biophysica acta. Molecular basis of disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — IP-MS substrate identification, site-specific ubiquitination mapping, rescue experiment, single lab\",\n      \"pmids\": [\"41061828\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"USP53 deubiquitinates SMAD5 to stabilize its protein expression in bone marrow stromal cells, promoting their viability, invasion, and osteogenic differentiation; EIF4A3 stabilizes USP53 mRNA to maintain USP53 protein levels, forming an EIF4A3-USP53-SMAD5 regulatory axis.\",\n      \"method\": \"Co-immunoprecipitation, western blot, knockdown/overexpression experiments, ALP activity assay, Alizarin red staining, qRT-PCR\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP plus functional knockdown/rescue in single lab with no in vivo validation\",\n      \"pmids\": [\"40481141\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"FOS transcription factor directly regulates USP53 expression; juglone suppresses FOS, downregulating USP53, which reduces USP53-dependent deubiquitination of MLKL and GSDMD, promoting their ubiquitination and degradation and thereby alleviating necroptosis and pyroptosis in injured neurons.\",\n      \"method\": \"RNA-seq, immunoprecipitation, western blot, qRT-PCR, ChIP-qPCR, OGD/R neuronal model, in vivo spinal cord injury model\",\n      \"journal\": \"Phytomedicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2/3 — ChIP-qPCR for FOS-USP53 promoter binding, Co-IP, in vivo model; single lab\",\n      \"pmids\": [\"41045624\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"ATF3 transcriptionally represses USP53 by binding its promoter; USP53 promotes adipogenesis and activates the RhoA/ROCK signaling pathway; ATF3-mediated USP53 repression inhibits adipocyte differentiation of 3T3-L1 cells.\",\n      \"method\": \"ChIP assay, luciferase reporter assay, Oil Red O staining, triglyceride measurement, western blot (RhoA/ROCK pathway), ATF3 and USP53 overexpression/knockdown\",\n      \"journal\": \"Journal of molecular endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ChIP and luciferase reporter validate promoter binding; functional adipogenesis assays, single lab\",\n      \"pmids\": [\"39641389\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"USP53 is an active deubiquitinase with high selectivity for K63-linked polyubiquitin chains (overturning its prior annotation as a catalytically inactive pseudo-enzyme), whose USP domain harbors K63-specific S2-ubiquitin-binding sites; it physically associates with and deubiquitinates multiple substrates including TJP1/TJP2 (maintaining tight junction integrity in the inner ear and liver), MYO5B (regulating BSEP trafficking to the canalicular membrane), FKBP51 (suppressing AKT1 signaling), cytochrome c (promoting apoptosis), RIPK1 (controlling K63-ubiquitination-dependent necroptosis/apoptosis at K377), NOTCH2, CRKL, ZMYND11, MORF4L1, SMAD5, and SR-A, while in bone it enhances VDR-SMAD3 interaction to suppress RANKL expression, collectively establishing USP53 as a multifunctional K63-linkage-directed DUB that regulates bile acid secretion, tight junction integrity, cell death, bone homeostasis, and tumor suppression across multiple tissues.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"USP53 is a K63-linkage-selective deubiquitinase that operates at the intersection of tight junction maintenance, bile acid secretion, cell death signaling, bone homeostasis, and tumor suppression across multiple tissues. Despite its prior annotation as a catalytically inactive pseudo-DUB, USP53 harbors an active USP domain with K63-specific S2-ubiquitin-binding sites and deubiquitinates diverse substrates including TJP1/TJP2 (tight junction scaffolding), MYO5B (BSEP trafficking to the canalicular membrane), RIPK1 (K63-deubiquitination at K377 triggering necroptosis/apoptosis), cytochrome c (apoptosis), FKBP51 (AKT1 suppression), NOTCH2 (NF-κB signaling in microglia), MORF4L1, ZMYND11, SMAD5, and SR-A [PMID:26609154, PMID:40828662, PMID:40822127, PMID:35654790, PMID:39044157, PMID:38904030]. In bone, USP53 enhances VDR–SMAD3 interaction to suppress RANKL, coupling osteoblast and osteoclast activity, and Usp53-null mice display low bone mass [PMID:36726200]. Biallelic loss-of-function variants in USP53 cause low-GGT intrahepatic cholestasis with sensorineural hearing loss, reflecting its essential roles in hepatocyte tight junction integrity and bile transporter expression [PMID:30250217, PMID:39705897].\",\n  \"teleology\": [\n    {\n      \"year\": 2015,\n      \"claim\": \"Forward genetics revealed that USP53 — then annotated as a catalytically dead pseudo-DUB — physically associates with tight junction scaffolds TJP1/TJP2 and is essential for auditory hair cell survival and endocochlear potential maintenance, establishing it as a functional component of epithelial tight junctions.\",\n      \"evidence\": \"ENU mutagenesis (mambo mouse), reciprocal Co-IP, colocalization imaging, cochlear organotypic cultures, biotin tracer assay\",\n      \"pmids\": [\"26609154\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Catalytic activity was not tested and assumed absent\", \"The mechanism by which USP53 supports tight junction integrity was unknown\", \"No liver or bone phenotype examined\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Human genetics linked biallelic USP53 truncating variants to low-GGT intrahepatic cholestasis and hearing loss, extending USP53's tight-junction role from the inner ear to hepatocytes and establishing a Mendelian disease association.\",\n      \"evidence\": \"Exome sequencing and segregation analysis in multiple families\",\n      \"pmids\": [\"30250217\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No biochemical or cell-biological experiments in this study\", \"Mechanism linking USP53 loss to cholestasis was unresolved\", \"No animal model of liver phenotype\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"USP53 was shown to deubiquitinate specific substrates — FKBP51 (suppressing AKT1/glycolysis in lung adenocarcinoma) and cytochrome c (promoting apoptosis in HCC) — establishing that it functions as an active deubiquitinase with tumor-suppressive roles, contradicting its pseudo-enzyme annotation.\",\n      \"evidence\": \"Co-IP, ubiquitination assays, cycloheximide chase, GSEA, in vivo xenograft, rescue experiments\",\n      \"pmids\": [\"32511815\", \"35654790\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Linkage specificity (K48 vs K63) not resolved\", \"No in vitro reconstitution of catalytic activity\", \"Single-lab observations without structural confirmation of active site\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Ultrastructural analysis of USP53-mutant patient livers revealed elongated hepatocyte tight junctions, providing direct morphological evidence that USP53 regulates tight junction architecture in human liver.\",\n      \"evidence\": \"Transmission electron microscopy of liver biopsies from patients with biallelic USP53 variants\",\n      \"pmids\": [\"32124521\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of junction elongation unclear\", \"No molecular targets identified in this study\", \"Small patient cohort\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"USP53 was placed downstream of PTH/NACA signaling in osteoblasts; its knockdown promoted osteoblast over adipocyte commitment, revealing a role in mesenchymal lineage determination.\",\n      \"evidence\": \"ChIP-seq, EMSA, luciferase reporter, shRNA knockdown in ST2 stromal cells, in vivo implantation\",\n      \"pmids\": [\"33875709\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No DUB substrates identified in bone context at this point\", \"No Usp53 knockout bone phenotype yet reported\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Usp53-null mice exhibited low bone mass and elevated RANKL due to loss of USP53-mediated enhancement of VDR–SMAD3 interaction, revealing a specific molecular mechanism for USP53's role in osteoblast-osteoclast coupling.\",\n      \"evidence\": \"Usp53 knockout mice, micro-CT, histomorphometry, serum RANKL ELISA, VDR–SMAD3 Co-IP\",\n      \"pmids\": [\"36726200\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether USP53 directly deubiquitinates VDR or SMAD3 was not tested\", \"Bone phenotype rescue not demonstrated\", \"Contribution of adipocyte vs osteoblast compartment not dissected\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Liver-specific Usp53 knockout confirmed that hepatic USP53 interacts with TJP2 and regulates tight junction length and bile acid transporter expression (BSEP/NTCP/MRP2), providing a mechanistic bridge between tight junction biology and cholestasis.\",\n      \"evidence\": \"Alb-cre × Usp53fl/fl mice, Co-IP, immunofluorescence, electron microscopy, DDC dietary challenge\",\n      \"pmids\": [\"39705897\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether USP53 directly deubiquitinates TJP2 or another junction component unclear\", \"Compensatory mechanisms in liver-specific KO not defined\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Biochemical reconstitution overturned the pseudo-enzyme annotation: USP53 is an active deubiquitinase with high selectivity for K63-linked polyubiquitin, with structural K63-specific S2-ubiquitin-binding sites, and patient-associated mutations abolish catalytic activity.\",\n      \"evidence\": \"(preprint) In vitro DUB assays, structural analysis, site-directed mutagenesis of patient variants, K63-ubiquitination profiling of tricellular junction components\",\n      \"pmids\": [\"bio_10.1101_2024.07.07.602376\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Awaits peer review\", \"Full crystal/cryo-EM structure not yet deposited\", \"In vivo validation of K63-selectivity for specific substrates needed\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"USP53 was shown to deubiquitinate SR-A via its USP domain (Cys41-dependent) removing K48-linked ubiquitin, promoting foam cell formation during atherosclerosis — notably demonstrating K48-directed activity alongside the predominant K63 specificity.\",\n      \"evidence\": \"Co-IP, Cys41 mutagenesis, ChIP, AAV-SMC-specific OE in DKK1ECKO/APOE−/− mice, parallel-plate co-culture\",\n      \"pmids\": [\"38904030\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Apparent K48 activity on SR-A conflicts with predominant K63 selectivity; reconciliation needed\", \"Single disease context (atherosclerosis)\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"The cholestasis mechanism was resolved at the trafficking level: USP53 loss causes MYO5B hyperubiquitination and BSEP mistrafficking to recycling endosomes; USP53 binds the MYO5B IQ domain, and a cholestasis-associated MYO5B variant disrupts this interaction.\",\n      \"evidence\": \"CRISPR KO, surface biotinylation, FRAP, Co-IP with mutagenesis, confocal imaging in patient tissue\",\n      \"pmids\": [\"40828662\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Ubiquitin linkage type on MYO5B not specified\", \"Whether USP53 regulates other apical transporters via MYO5B not tested\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"USP53 was shown to remove K63-ubiquitin from RIPK1 at K377, licensing RIPK1 autophosphorylation and triggering necroptosis/apoptosis in cardiomyocytes, expanding USP53's cell death regulatory repertoire beyond cytochrome c and FKBP51.\",\n      \"evidence\": \"Co-IP/LC-MS/MS, site-specific K63-ubiquitination mapping, cardiomyocyte-specific USP53 KO mice with alcohol feeding\",\n      \"pmids\": [\"40822127\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether RIPK1-K377 deubiquitination by USP53 occurs in non-cardiac tissues unknown\", \"Kinetics and regulation of USP53 recruitment to complex I/II not defined\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Additional substrates were identified — NOTCH2 (microglia/neuroinflammation), MORF4L1 (colorectal cancer), ZMYND11 (breast cancer), and SMAD5 (osteogenic differentiation) — broadening the substrate repertoire and reinforcing USP53's role as a multi-tissue DUB acting on both signaling and chromatin-associated proteins.\",\n      \"evidence\": \"Co-IP, ubiquitination assays with site mapping (K249/K227 for MORF4L1), domain mutagenesis (Cys-box for ZMYND11), xenografts, in vivo KO (5XFAD mice for NOTCH2)\",\n      \"pmids\": [\"41482165\", \"41061828\", \"39044157\", \"40481141\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Substrate prioritization unclear — which are physiologically dominant\", \"K63 vs K48 linkage not determined for all new substrates\", \"SMAD5 result from single lab without in vivo validation\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How USP53 achieves substrate selectivity across such diverse targets, whether its K63 selectivity is absolute or context-dependent (given reported K48 activity on SR-A), and the structural basis for substrate recognition outside the catalytic domain remain open questions.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No high-resolution structure of USP53 bound to a substrate or ubiquitin chain\", \"Systematic profiling of linkage preference across substrates not performed\", \"Tissue-specific regulation of USP53 expression and activation incompletely mapped\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [2, 5, 9, 10, 12, 13, 14, 15, 16, 17, 18]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [12, 14]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 3, 11, 13]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [5, 13]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [13]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [10, 16]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [2, 5, 14, 18]},\n      {\"term_id\": \"R-HSA-382551\", \"supporting_discovery_ids\": [1, 11, 13]},\n      {\"term_id\": \"R-HSA-1500931\", \"supporting_discovery_ids\": [0, 3, 11, 12]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [2, 6, 15]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [1, 9, 15]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [12, 14, 16]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"TJP2\",\n      \"TJP1\",\n      \"MYO5B\",\n      \"RIPK1\",\n      \"FKBP51\",\n      \"ZMYND11\",\n      \"MORF4L1\",\n      \"NOTCH2\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}