{"gene":"USP26","run_date":"2026-06-11T09:02:06","timeline":{"discoveries":[{"year":2010,"finding":"USP26 is a nuclear protein that binds to androgen receptor (AR) via three nuclear receptor interaction motifs, modulates AR ubiquitination, and stabilizes AR by counteracting hormone-induced ubiquitination, thereby influencing AR transcriptional activity. USP26 assembles with AR and other cofactors in subnuclear foci.","method":"shRNA library screen, Co-IP, subnuclear foci imaging, ubiquitination assay","journal":"Molecular cancer research : MCR","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, subnuclear localization, ubiquitination assay, single lab with multiple orthogonal methods","pmids":["20501646"],"is_preprint":false},{"year":2015,"finding":"USP26 is recruited to DNA double-strand breaks (DSBs) where it removes RNF168-induced ubiquitin conjugates, limits excessive spreading of RAP80-BRCA1 from DSBs, and promotes BRCA1 association with PALB2, thereby facilitating homologous recombination. Depletion of USP26 disrupts HR execution, and this effect is rescued by simultaneous depletion of RAP80.","method":"Genetic screen, siRNA depletion, immunofluorescence at DSBs, epistasis (double knockdown rescue), HR reporter assay","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic epistasis (double knockdown rescue), direct DSB recruitment demonstrated by imaging, HR functional assay, multiple orthogonal methods in single lab","pmids":["26101254"],"is_preprint":false},{"year":2017,"finding":"USP26 deubiquitinates and stabilizes SMAD7, functioning as a component of the TGF-β negative feedback loop. TGF-β enhances USP26 expression; USP26 limits ubiquitin-mediated turnover of SMAD7, preventing TGF-β receptor stabilization and reducing p-SMAD2 levels. Knockdown of USP26 degrades SMAD7, stabilizes TGF-β receptor, and enhances TGF-β signaling.","method":"Co-IP, ubiquitination assay, siRNA knockdown, western blot for p-SMAD2 and receptor levels","journal":"EMBO reports","confidence":"High","confidence_rationale":"Tier 2 / Moderate — Co-IP, ubiquitination assay, and RNAi functional phenotype in single lab with multiple orthogonal methods","pmids":["28381482"],"is_preprint":false},{"year":2017,"finding":"USP26 negatively regulates somatic cell reprogramming by stabilizing PRC1 complex components CBX4 and CBX6 through removal of K48-linked polyubiquitination. Accumulated CBX4 and CBX6 repress pluripotency genes (Sox2, Nanog) by ubiquitinating histone H2A at their promoters via PRC1 complexes.","method":"Co-IP, ubiquitination assay (K48-linkage specific), reprogramming efficiency assay, ChIP for H2A ubiquitination at promoters, siRNA/overexpression","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Moderate — linkage-specific ubiquitination assay, Co-IP, ChIP, functional reprogramming assay; multiple orthogonal methods in single lab","pmids":["28839133"],"is_preprint":false},{"year":2016,"finding":"USP26 binds to Mdm2 through its coiled-coil C-terminal domain, deubiquitinates Mdm2, and stabilizes it. USP26 itself can be ubiquitinated in cell-free HeLa extract.","method":"Co-transfection, Co-IP, cell-free ubiquitination assay, half-life analysis","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — Co-IP and cell-free ubiquitination assay, single lab, single study","pmids":["27810359"],"is_preprint":false},{"year":2016,"finding":"The USP26 R344W missense mutation reduces USP26 binding affinity to AR and abolishes its deubiquitinating activity toward AR, thereby eliminating the inhibitory effect of USP26 on AR transcriptional activity in HeLa and TM4 cells.","method":"Immunoprecipitation, ubiquitination assay, luciferase transcriptional activity assay","journal":"Reproductive sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — Co-IP, ubiquitination assay, and functional reporter assay; single lab, single study","pmids":["27089915"],"is_preprint":false},{"year":2019,"finding":"USP26 deubiquitinates and stabilizes Snail, a transcription factor promoting epithelial-mesenchymal transition (EMT), and promotes esophageal squamous cell carcinoma cell migration and invasion. Identified by screening a DUB library.","method":"DUB library screen, Co-IP, ubiquitination assay, cell migration/invasion assay","journal":"Cancer letters","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — DUB library screen, Co-IP, ubiquitination assay, functional cellular assay; single lab, single study","pmids":["30763716"],"is_preprint":false},{"year":2019,"finding":"Usp26 mutant male mice (DBA/2 background, but not C57BL/6) are sterile or subfertile with atrophic testes, reduced spermatids, malformed sperm head morphology, unsynapsed chromosomes in pachynema, and defective chiasma formation in diplonema, leading to apoptosis of metaphase spermatocytes. Effects are genetic-background dependent.","method":"Mouse knockout (gene-targeted mutation), histology, spermatocyte cytology (chromosome spread), fertility assessment","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 2 / Moderate — defined in vivo KO with specific cellular and meiotic phenotypes, multiple complementary analyses, replicated across two genetic backgrounds","pmids":["31551464"],"is_preprint":false},{"year":2019,"finding":"Two independently generated Usp26-null mouse lines show no overt phenotype: both males and females are fertile, with normal spermatocyte synapsis, chromosome dynamics, DNA repair, recombination, and cell-type distribution in testes. USP26 is thus not essential for mouse gametogenesis.","method":"Mouse knockout (two independent null alleles), cytology, histopathology, fertility assessment","journal":"Chromosoma","confidence":"High","confidence_rationale":"Tier 2 / Moderate — two independent KO alleles, comprehensive cytological and histological analyses; negative result is well-supported","pmids":["30887115"],"is_preprint":false},{"year":2021,"finding":"USP26 protein localizes to the XY body during meiosis. Knockout of Usp26 in male mice causes incomplete sex chromosome pairing by destabilizing TEX11, leading to XY aneuploid spermatozoa and 41,XXY (Klinefelter syndrome) offspring. USP26 variants in men increase the proportion of XY aneuploid spermatozoa.","method":"Mouse knockout, immunofluorescence (XY body localization), Co-IP/western blot (TEX11 destabilization), clinical sperm FISH aneuploidy analysis","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo KO, direct localization experiment, protein interaction/stability assay, and clinical validation across multiple approaches","pmids":["33978233"],"is_preprint":false},{"year":2022,"finding":"RNF12 relieves REX1-mediated repression of Usp26, increasing USP26 abundance. USP26 then forms complexes with RNF12 and prevents RNF12 autoubiquitylation and proteasomal degradation, establishing a transcriptional feed-forward amplification loop. This RNF12-USP26 axis operates in mouse testes and is required for gametogenesis gene expression and germ cell differentiation. RLIM (RNF12) and USP26 disease-associated variants disrupt this axis.","method":"Quantitative proteomics (global), Co-IP, ubiquitination assay, ESC differentiation assay, mutagenesis with patient variants","journal":"Science signaling","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — global proteomics, reciprocal Co-IP, ubiquitination assay, functional differentiation assay, and mutagenesis; multiple orthogonal methods","pmids":["35857630"],"is_preprint":false},{"year":2022,"finding":"USP26 interacts with, deubiquitylates, and stabilizes TAZ (a Hippo pathway effector) in anaplastic thyroid cancer cells in a deubiquitylation activity-dependent manner. USP26 depletion decreases TAZ protein levels and reduces expression of TAZ/TEAD target genes (CTGF, ANKRD1, CYR61).","method":"Co-IP, ubiquitination assay, catalytic mutant (activity-dependent rescue), siRNA knockdown with target gene expression readout","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — Co-IP, ubiquitination assay, activity-dependent rescue; single lab, single study","pmids":["35397626"],"is_preprint":false},{"year":2017,"finding":"The USP26 Q156H mutant has no enzymatic (deubiquitinase) activity toward model substrates Ub-Met-β-gal and GST-Ub52. Eighteen other tested mutants (including E174# and E189# truncation mutants) retain wild-type enzymatic activity. Artificially constructed truncation fragments (each half alone) lose activity.","method":"In vitro USP cleavage assay with site-directed mutagenesis","journal":"Gene","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — in vitro enzymatic assay with mutagenesis, single lab; single study","pmids":["29111204"],"is_preprint":false},{"year":2015,"finding":"Five frequent USP26 mutations (c.363_364insACA, c.494T>C, c.1423C>T, c.1090C>T, c.1737G>A) do not affect USP26 deubiquitinase enzymatic activity in a USP cleavage assay.","method":"In vitro USP cleavage assay","journal":"Andrology","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — in vitro enzymatic assay, single lab, single study; negative result well-supported","pmids":["25755145"],"is_preprint":false},{"year":2024,"finding":"USP26 directly interacts with PRKN (Parkin), deubiquitinates PRKN at the K129 site, and reduces its activity, thereby restraining PRKN-mediated mitophagy. A K129R mutation on PRKN diminishes its activation and mitophagy capacity.","method":"Co-IP, ubiquitination assay (site-specific K129), site-directed mutagenesis (K129R), mitophagy assay","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — Co-IP, site-specific ubiquitination assay, mutagenesis; single lab, single study","pmids":["38565942"],"is_preprint":false},{"year":2024,"finding":"HBV-encoded HBx binds to the USP26 promoter and induces USP26 expression. USP26 then associates with SIRT1 and stabilizes it by deubiquitination, promoting HCC cell proliferation and inhibiting apoptosis.","method":"sgRNA DUB library screen, Co-IP, ubiquitination assay, murine Usp26 KO model, promoter binding assay","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Moderate — sgRNA library screen, Co-IP, ubiquitination assay, in vivo KO model, promoter binding; multiple orthogonal methods","pmids":["39251623"],"is_preprint":false},{"year":2024,"finding":"USP26 deubiquitinates and stabilizes SIRT2 in BMSCs; loss of USP26 leads to SIRT2 ubiquitin-mediated degradation, causing mitochondrial dysfunction and BMSC senescence. HIF-1α promotes USP26 transcription by binding to the -191 to -198 bp and -262 to -269 bp regions of the USP26 promoter.","method":"Co-IP, ubiquitination assay, mitochondrial function assay, promoter-reporter assay, ChIP","journal":"Advanced science","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — Co-IP, ubiquitination assay, promoter-reporter with ChIP; single lab, single study","pmids":["39377219"],"is_preprint":false},{"year":2024,"finding":"USP26 suppresses type I interferon signaling by physically interacting with TRAF3 and removing K63-linked polyubiquitination from TRAF3, thereby inhibiting the MAVS/TBK-1/IRF3 antiviral signaling pathway. USP26 knockdown enhances IFN-β and ISG expression and inhibits EV71 replication.","method":"Co-IP, linkage-specific ubiquitination assay (K63), siRNA knockdown, IFN-β/ISG reporter assay, viral replication assay","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — Co-IP, linkage-specific ubiquitination assay, functional antiviral assay; single lab, single study","pmids":["39058724"],"is_preprint":false},{"year":2024,"finding":"USP26 interacts with and deubiquitinates BAG3, increasing its protein stability. This interaction is enhanced by Tip60-mediated acetylation of USP26 at K134, which increases USP26 binding affinity to BAG3.","method":"Co-IP, ubiquitination assay, acetylation assay (Tip60), site-directed mutagenesis (K134), protein stability (half-life) assay","journal":"Cancer letters","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — Co-IP, ubiquitination and acetylation assays, mutagenesis; single lab, single study","pmids":["38880224"],"is_preprint":false},{"year":2020,"finding":"Elevated cellular ROS levels suppress USP26 deubiquitinase activity, leading to increased ubiquitination and proteasomal degradation of AR and ARv7 in prostate cancer cells, thereby increasing enzalutamide sensitivity.","method":"In vitro deubiquitinating enzyme activity assay, ROS measurement (dihydroethidium staining), ubiquitination assay","journal":"Cancers","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — in vitro DUB activity assay and ROS-mediated inhibition; single lab, single study","pmids":["32235588"],"is_preprint":false},{"year":2020,"finding":"RAC1B promotes USP26 transcriptional induction, which in turn deubiquitinates and stabilizes SMAD7 protein, enabling SMAD7-mediated suppression of ALK5 and TGF-β1-induced cell migration in mesenchymal-type carcinoma cells.","method":"RNAi knockdown epistasis, western blot, ALK5 promoter reporter, cell migration assay","journal":"Cancers","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — epistatic RNAi analysis, pathway placement via functional rescue; single lab, single study","pmids":["32545415"],"is_preprint":false},{"year":2020,"finding":"USP26 interacts with AR by Co-IP and deubiquitinates AR in Leydig cells (TM3), upregulating CCND1 and SPATA46 and decreasing TP73, promoting G1-G2 cell cycle transition and Leydig cell proliferation through the AR signaling pathway.","method":"Co-IP, immunofluorescence, western blot, flow cytometry cell cycle assay","journal":"Advances in clinical and experimental medicine","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP, immunofluorescence, and flow cytometry; limited mechanistic follow-up, single lab","pmids":["33064378"],"is_preprint":false},{"year":2023,"finding":"USP26 is the sole DUB identified from a DUB library screen that associates with KLF6. USP26 interacts with KLF6 (interaction domain mapped to residues 285-913 of USP26), deubiquitinates it, and prolongs KLF6 protein stability, inhibiting proliferation and migration of HeLa cells.","method":"DUB library screen, Co-IP (domain mapping), ubiquitination assay, half-life assay, shRNA knockdown, proliferation/migration assay","journal":"Computers in biology and medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — DUB library screen, Co-IP with domain mapping, ubiquitination assay, functional cellular assay; single lab, single study","pmids":["38064851"],"is_preprint":false},{"year":2025,"finding":"In osteoblasts, USP26 loss decreases H3K18 lactylation at the KSRP promoter, reducing KSRP expression and decreasing alternative splicing of FSTL1 mRNA, leading to elevated FSTL1 expression, insulin resistance, and multi-organ fibrosis.","method":"Osteoblast-specific Usp26 conditional KO mouse, ChIP (H3K18LA), RT-PCR (alternative splicing), metabolic and fibrosis phenotyping","journal":"Advanced science","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — conditional KO with ChIP and splicing assays, single lab; novel mechanistic pathway with moderate experimental support","pmids":["41417635"],"is_preprint":false},{"year":2025,"finding":"In osteoblasts, USP26 prevents ubiquitin-mediated degradation of IL4I1. Loss of USP26 in osteoblasts collapses IL4I1-mediated tryptophan metabolism (reducing indole-3-acetic acid production), impairing B lymphopoiesis and increasing susceptibility to sepsis.","method":"Osteoblast-specific Usp26 conditional KO mouse, targeted metabolomics, transcriptomics, in vivo/in vitro IL4I1 supplementation/inhibition, bone-targeting exosome delivery","journal":"Journal of advanced research","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — conditional KO with metabolomics and functional immune assays; single lab, novel finding","pmids":["41687771"],"is_preprint":false},{"year":2025,"finding":"USP26 interacts with and stabilizes c-Myc by suppressing its polyubiquitination and degradation, promoting aerobic glycolysis and proliferation in gastric cancer cells.","method":"Co-IP, ubiquitination assay, shRNA knockdown, proliferation/glycolysis assay","journal":"DNA and cell biology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP and ubiquitination assay; single lab, single study, limited mechanistic depth","pmids":["41125405"],"is_preprint":false},{"year":2014,"finding":"USP26 protein colocalizes with androgen receptor in human testis, predominantly in Leydig cell nuclei (and to a lesser degree in spermatogonia, primary spermatocytes, round spermatids, and Sertoli cells), as established by immunofluorescence colocalization in human testis tissue.","method":"Immunofluorescence colocalization in formalin-fixed/paraffin-embedded and frozen human testis tissue","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 3 / Weak — direct immunofluorescence localization in human tissue with AR colocalization; single lab, single study","pmids":["24922532"],"is_preprint":false}],"current_model":"USP26 is an X-linked deubiquitinating enzyme (DUB) that stabilizes multiple substrates—including AR, SMAD7, Snail, TAZ, CBX4/CBX6 (PRC1 components), Mdm2, PRKN, SIRT1, SIRT2, BAG3, KLF6, c-Myc, IL4I1, and TEX11—by removing ubiquitin chains and preventing proteasomal degradation; it localizes to the XY body and subnuclear foci, is recruited to DNA double-strand breaks to remove RNF168-induced ubiquitin conjugates and facilitate homologous recombination, forms a feed-forward amplification loop with RNF12, and suppresses antiviral type I interferon signaling via TRAF3 deubiquitination, with its activity regulated by cellular ROS levels and Tip60-mediated acetylation."},"narrative":{"mechanistic_narrative":"USP26 is an X-linked deubiquitinating enzyme that controls the abundance of diverse regulatory proteins by cleaving ubiquitin chains and shielding substrates from proteasomal degradation, with prominent roles in male germ cell development, genome maintenance, and signaling control [PMID:20501646, PMID:33978233]. Its catalytic activity depends on a core USP domain whose integrity is required for substrate cleavage [PMID:29111204]. In the nucleus, USP26 binds androgen receptor through nuclear-receptor interaction motifs and stabilizes it by reversing hormone-induced ubiquitination, thereby tuning AR transcriptional output [PMID:20501646]. During meiosis it localizes to the XY body and stabilizes TEX11 to enforce proper sex-chromosome pairing, and its loss produces XY-aneuploid spermatozoa [PMID:33978233]. USP26 acts as a regulator of signaling feedback by deubiquitinating and stabilizing SMAD7 within a TGF-β negative feedback loop [PMID:28381482], and it amplifies its own expression through a feed-forward loop with RNF12 in which it blocks RNF12 autoubiquitylation, an axis required for gametogenesis gene expression [PMID:35857630]. At DNA double-strand breaks USP26 removes RNF168-induced ubiquitin conjugates, restrains RAP80-BRCA1 spreading, and promotes BRCA1-PALB2 association to enable homologous recombination [PMID:26101254]. Across multiple cancer and stem-cell contexts USP26 stabilizes a broad substrate set including PRC1 components CBX4/CBX6 [PMID:28839133], Snail [PMID:30763716], TAZ [PMID:35397626], SIRT1 [PMID:39251623], and SIRT2 [PMID:39377219], and its enzymatic activity is itself regulated—suppressed by elevated cellular ROS [PMID:32235588] and enhanced toward BAG3 by Tip60-mediated acetylation [PMID:38880224]. Whether USP26 is essential for mouse fertility is unresolved within the corpus: one knockout study reports background-dependent sterility and meiotic defects [PMID:31551464] while two independent null lines show normal fertility [PMID:30887115].","teleology":[{"year":2010,"claim":"Established USP26's first molecular function: that it is a nuclear DUB acting on a defined substrate (AR) rather than an orphan enzyme.","evidence":"shRNA screen, reciprocal Co-IP, subnuclear foci imaging, and ubiquitination assay","pmids":["20501646"],"confidence":"High","gaps":["Did not define the linkage type removed from AR","Physiological context of AR regulation not addressed"]},{"year":2014,"claim":"Placed USP26 in a tissue context by showing AR colocalization predominantly in human Leydig cell nuclei, linking the AR interaction to testis biology.","evidence":"Immunofluorescence colocalization in human testis tissue","pmids":["24922532"],"confidence":"Medium","gaps":["Colocalization is correlative, not functional","Single-lab tissue study"]},{"year":2015,"claim":"Revealed a genome-maintenance role distinct from transcriptional regulation: USP26 trims RNF168-dependent ubiquitin at DSBs to channel repair toward homologous recombination.","evidence":"Genetic screen, DSB immunofluorescence, RAP80 double-knockdown epistasis, and HR reporter assay","pmids":["26101254"],"confidence":"High","gaps":["Direct DSB substrate of the DUB activity not biochemically defined","Recruitment mechanism to breaks unknown"]},{"year":2017,"claim":"Defined USP26 as a node in TGF-β negative feedback by showing it stabilizes SMAD7 to dampen receptor signaling.","evidence":"Co-IP, ubiquitination assay, siRNA knockdown with p-SMAD2 and receptor readouts","pmids":["28381482"],"confidence":"High","gaps":["Ubiquitin linkage specificity on SMAD7 not resolved","In vivo relevance not tested"]},{"year":2017,"claim":"Connected USP26 to chromatin/pluripotency control by demonstrating K48-specific deubiquitination and stabilization of PRC1 components CBX4/CBX6 that repress pluripotency genes.","evidence":"K48-linkage-specific ubiquitination assay, Co-IP, ChIP for H2A ubiquitination, reprogramming assay","pmids":["28839133"],"confidence":"High","gaps":["Whether USP26 directly contacts both CBX proteins versus the assembled PRC1 not separated"]},{"year":2017,"claim":"Mapped the catalytic requirement: identified Q156 as essential for DUB activity and showed each domain half alone is inactive, defining the functional core.","evidence":"In vitro USP cleavage assay with site-directed mutagenesis on model substrates","pmids":["29111204"],"confidence":"Medium","gaps":["No structural model of the active site","Activity tested only on model substrates"]},{"year":2016,"claim":"Extended the substrate repertoire to Mdm2 and showed USP26 itself is subject to ubiquitination, hinting at autoregulation of the DUB.","evidence":"Co-transfection, Co-IP, cell-free ubiquitination, and half-life analysis","pmids":["27810359"],"confidence":"Medium","gaps":["E3 ligase ubiquitinating USP26 not identified","Single study without functional downstream readout"]},{"year":2016,"claim":"Linked a disease-associated variant to function by showing the R344W mutation abolishes AR deubiquitination and binding, providing a genotype-mechanism connection.","evidence":"Immunoprecipitation, ubiquitination assay, luciferase reporter in HeLa and TM4 cells","pmids":["27089915"],"confidence":"Medium","gaps":["Clinical penetrance of R344W not established here","Single-lab study"]},{"year":2019,"claim":"Confronted USP26's role in fertility with conflicting in vivo data: background-dependent meiotic failure in one model versus no phenotype in two independent null lines.","evidence":"Independent mouse knockout lines with spermatocyte cytology, histology, and fertility assessment","pmids":["31551464","30887115"],"confidence":"High","gaps":["Genetic-background modifiers not identified","Reason for discordance between knockout lines unresolved"]},{"year":2019,"claim":"Broadened the oncogenic substrate set by showing USP26 stabilizes the EMT driver Snail to promote carcinoma migration and invasion.","evidence":"DUB library screen, Co-IP, ubiquitination assay, migration/invasion assays","pmids":["30763716"],"confidence":"Medium","gaps":["Linkage specificity on Snail not defined","Single-lab study"]},{"year":2020,"claim":"Showed USP26 activity is environmentally tuned: elevated ROS suppresses its DUB activity, destabilizing AR/ARv7 and sensitizing prostate cancer cells to enzalutamide.","evidence":"In vitro DUB activity assay, ROS measurement, ubiquitination assay","pmids":["32235588"],"confidence":"Medium","gaps":["Molecular basis of ROS sensitivity (e.g. cysteine oxidation) not mapped","Single study"]},{"year":2020,"claim":"Positioned USP26 downstream of RAC1B in the SMAD7/TGF-β axis and as an AR-pathway driver of Leydig cell proliferation, integrating it into upstream signaling control.","evidence":"RNAi epistasis with promoter reporters and migration assays; Co-IP with cell-cycle flow cytometry","pmids":["32545415","33064378"],"confidence":"Medium","gaps":["Leydig cell study is Low confidence with limited mechanistic depth","Direct versus indirect transcriptional induction of USP26 not separated"]},{"year":2021,"claim":"Defined the meiotic mechanism: USP26 localizes to the XY body and stabilizes TEX11 to ensure sex-chromosome pairing, with loss producing XY-aneuploid sperm and Klinefelter offspring.","evidence":"Mouse knockout, XY-body immunofluorescence, TEX11 stability assays, clinical sperm FISH aneuploidy analysis","pmids":["33978233"],"confidence":"High","gaps":["Reconciliation with the no-phenotype knockout lines not resolved","Linkage type removed from TEX11 not specified"]},{"year":2022,"claim":"Uncovered a self-amplifying circuit: RNF12 de-represses Usp26 transcription, and USP26 in turn blocks RNF12 autoubiquitylation, forming a feed-forward loop required for gametogenesis gene expression.","evidence":"Quantitative proteomics, reciprocal Co-IP, ubiquitination assay, ESC differentiation, patient-variant mutagenesis","pmids":["35857630"],"confidence":"High","gaps":["Quantitative thresholds of the loop not modeled","How disease variants quantitatively perturb the loop incompletely defined"]},{"year":2022,"claim":"Added the Hippo effector TAZ as an activity-dependent substrate, linking USP26 to TAZ/TEAD target gene expression in anaplastic thyroid cancer.","evidence":"Co-IP, ubiquitination assay, catalytic-mutant rescue, siRNA with target-gene readout","pmids":["35397626"],"confidence":"Medium","gaps":["Single-lab study","Whether TAZ regulation occurs outside thyroid cancer not tested"]},{"year":2023,"claim":"Identified KLF6 as a USP26 substrate via domain-mapped interaction (residues 285-913), with stabilization restraining cell proliferation and migration.","evidence":"DUB library screen, Co-IP with domain mapping, half-life and ubiquitination assays, functional cellular assays","pmids":["38064851"],"confidence":"Medium","gaps":["Single study","Physiological tissue context not addressed"]},{"year":2024,"claim":"Showed USP26 regulates mitophagy and antiviral immunity through site- and linkage-specific deubiquitination of PRKN (K129) and TRAF3 (K63), and is itself activated toward BAG3 by Tip60 acetylation at K134.","evidence":"Co-IP, site/linkage-specific ubiquitination assays, mutagenesis (K129R, K134), acetylation assay, mitophagy and IFN-β/ISG reporter assays","pmids":["38565942","39058724","38880224"],"confidence":"Medium","gaps":["Each substrate documented in a single study","Cross-pathway coordination among these substrates not examined"]},{"year":2024,"claim":"Tied USP26 to cancer cell survival via virus- and hypoxia-driven transcription and stabilization of SIRT1 and SIRT2, controlling proliferation, apoptosis, and mitochondrial function.","evidence":"DUB/sgRNA library screens, Co-IP, ubiquitination assays, in vivo KO, promoter binding/ChIP, mitochondrial assays","pmids":["39251623","39377219"],"confidence":"High","gaps":["Whether SIRT1 and SIRT2 are regulated in the same cells not addressed","Linkage specificity on SIRT2 not fully defined"]},{"year":2025,"claim":"Revealed osteoblast-intrinsic roles via conditional knockout: USP26 sustains an H3K18-lactylation/KSRP/FSTL1 splicing axis and stabilizes IL4I1 to support tryptophan metabolism and B lymphopoiesis, with systemic metabolic and immune consequences.","evidence":"Osteoblast-specific conditional KO mice, ChIP (H3K18LA), splicing RT-PCR, targeted metabolomics, immune phenotyping","pmids":["41417635","41687771"],"confidence":"Medium","gaps":["Mechanism connecting USP26 DUB activity to H3K18 lactylation not direct","Single-lab conditional KO findings"]},{"year":2025,"claim":"Added c-Myc stabilization driving aerobic glycolysis in gastric cancer to the substrate list.","evidence":"Co-IP, ubiquitination assay, shRNA knockdown, glycolysis/proliferation assays","pmids":["41125405"],"confidence":"Low","gaps":["Single Co-IP/ubiquitination assay with limited mechanistic depth","No structural or linkage characterization"]},{"year":null,"claim":"How a single DUB selects among this very broad substrate set and how its tissue-restricted, ROS- and acetylation-regulated activity is coordinated in vivo remains unresolved, as does the discordance between knockout phenotypes.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural basis for substrate selectivity","No unified model reconciling fertile versus sterile knockout lines","Substrate-recruitment determinants largely undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,1,2,3,9,11,14,15,16,17,18]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[12,13,19]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,2,10]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,26]},{"term_id":"GO:0005654","term_label":"nucleoplasm","supporting_discovery_ids":[0]}],"pathway":[{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[1]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[2,11,20]},{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[9,10]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[17,24]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[0,2,3,15]}],"complexes":["RNF12-USP26 feed-forward complex"],"partners":["AR","SMAD7","RNF12","TEX11","MDM2","TRAF3","PRKN","BAG3"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9BXU7","full_name":"Ubiquitin carboxyl-terminal hydrolase 26","aliases":["Deubiquitinating enzyme 26","Ubiquitin thioesterase 26","Ubiquitin-specific-processing protease 26"],"length_aa":913,"mass_kda":104.0,"function":"Deubiquitinase regulating several biological processes through the deubiquitination of components of these processes (PubMed:20501646, PubMed:28839133). Involved in somatic cell reprogramming through the 'Lys-48'-linked deubiquitination and stabilization of CBX4 and CBX6, two components of the polycomb-repressive complex 1 (PRC1) (PubMed:28839133). Also deubiquitinates and probably stabilizes the androgen receptor (AR), regulating the androgen receptor signaling pathway (PubMed:20501646). May play a role in spermatogenesis (PubMed:34202084)","subcellular_location":"Nucleus; Cytoplasm, cytoskeleton, flagellum axoneme","url":"https://www.uniprot.org/uniprotkb/Q9BXU7/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/USP26","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/USP26","total_profiled":1310},"omim":[{"mim_id":"305700","title":"SPERMATOGENIC FAILURE, X-LINKED, 1; SPGFX1","url":"https://www.omim.org/entry/305700"},{"mim_id":"301101","title":"SPERMATOGENIC FAILURE, X-LINKED, 6; SPGFX6","url":"https://www.omim.org/entry/301101"},{"mim_id":"300309","title":"UBIQUITIN-SPECIFIC PROTEASE 26; USP26","url":"https://www.omim.org/entry/300309"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Not detected","tissue_distribution":"Not detected","driving_tissues":[],"url":"https://www.proteinatlas.org/search/USP26"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"Q9BXU7","domains":[{"cath_id":"2.30.29.180","chopping":"5-105","consensus_level":"medium","plddt":83.5377,"start":5,"end":105}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BXU7","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BXU7-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BXU7-F1-predicted_aligned_error_v6.png","plddt_mean":59.97},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=USP26","jax_strain_url":"https://www.jax.org/strain/search?query=USP26"},"sequence":{"accession":"Q9BXU7","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9BXU7.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9BXU7/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BXU7"}},"corpus_meta":[{"pmid":"15562280","id":"PMC_15562280","title":"Possible role of USP26 in patients with severely impaired spermatogenesis.","date":"2005","source":"European journal of human genetics : EJHG","url":"https://pubmed.ncbi.nlm.nih.gov/15562280","citation_count":76,"is_preprint":false},{"pmid":"20501646","id":"PMC_20501646","title":"The deubiquitinating enzyme USP26 is a regulator of androgen receptor signaling.","date":"2010","source":"Molecular cancer research : MCR","url":"https://pubmed.ncbi.nlm.nih.gov/20501646","citation_count":73,"is_preprint":false},{"pmid":"26101254","id":"PMC_26101254","title":"The de-ubiquitylating enzymes USP26 and USP37 regulate homologous recombination by counteracting RAP80.","date":"2015","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/26101254","citation_count":64,"is_preprint":false},{"pmid":"28381482","id":"PMC_28381482","title":"USP26 regulates TGF-β signaling by deubiquitinating and stabilizing SMAD7.","date":"2017","source":"EMBO 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associated with male infertility and recurrent pregnancy loss (RPL) in Iranian infertile patients.","date":"2013","source":"Journal of assisted reproduction and genetics","url":"https://pubmed.ncbi.nlm.nih.gov/23779098","citation_count":29,"is_preprint":false},{"pmid":"18958354","id":"PMC_18958354","title":"Association of USP26 haplotypes in men in Taiwan, China with severe spermatogenic defect.","date":"2008","source":"Asian journal of andrology","url":"https://pubmed.ncbi.nlm.nih.gov/18958354","citation_count":28,"is_preprint":false},{"pmid":"31551464","id":"PMC_31551464","title":"Usp26 mutation in mice leads to defective spermatogenesis depending on genetic background.","date":"2019","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/31551464","citation_count":27,"is_preprint":false},{"pmid":"35397626","id":"PMC_35397626","title":"USP26 promotes anaplastic thyroid cancer progression by stabilizing TAZ.","date":"2022","source":"Cell death & 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chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/21147082","citation_count":19,"is_preprint":false},{"pmid":"18377898","id":"PMC_18377898","title":"Sequence analysis of the X-linked USP26 gene in severe male factor infertility patients and fertile controls.","date":"2008","source":"Fertility and sterility","url":"https://pubmed.ncbi.nlm.nih.gov/18377898","citation_count":19,"is_preprint":false},{"pmid":"27810359","id":"PMC_27810359","title":"The testis-specific USP26 is a deubiquitinating enzyme of the ubiquitin ligase Mdm2.","date":"2016","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/27810359","citation_count":17,"is_preprint":false},{"pmid":"27726449","id":"PMC_27726449","title":"Single nucleotide polymorphisms of USP26 in azoospermic men.","date":"2016","source":"Systems biology in reproductive 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Prostate Cancer Progression Via Targeting BCL2/ROS/USP26 Axis Through Altering ARv7 Protein Degradation.","date":"2020","source":"Cancers","url":"https://pubmed.ncbi.nlm.nih.gov/32235588","citation_count":15,"is_preprint":false},{"pmid":"29111204","id":"PMC_29111204","title":"The impacts of nineteen mutations on the enzymatic activity of USP26.","date":"2017","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/29111204","citation_count":12,"is_preprint":false},{"pmid":"32410375","id":"PMC_32410375","title":"Novel mutation in USP26 associated with azoospermia in a Sertoli cell-only syndrome patient.","date":"2020","source":"Molecular genetics & genomic medicine","url":"https://pubmed.ncbi.nlm.nih.gov/32410375","citation_count":11,"is_preprint":false},{"pmid":"39251623","id":"PMC_39251623","title":"USP26 as a hepatitis B virus-induced deubiquitinase primes hepatocellular carcinogenesis by epigenetic remodeling.","date":"2024","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/39251623","citation_count":10,"is_preprint":false},{"pmid":"32760222","id":"PMC_32760222","title":"Targeting deubiquitinating enzyme USP26 by microRNA-203 regulates Snail1's pro-metastatic functions in esophageal cancer.","date":"2020","source":"Cancer cell international","url":"https://pubmed.ncbi.nlm.nih.gov/32760222","citation_count":10,"is_preprint":false},{"pmid":"33064378","id":"PMC_33064378","title":"USP26 deubiquitinates androgen receptor (AR) in the maintenance of sperm maturation and spermatogenesis through the androgen receptor signaling pathway.","date":"2020","source":"Advances in clinical and experimental medicine : official organ Wroclaw Medical University","url":"https://pubmed.ncbi.nlm.nih.gov/33064378","citation_count":10,"is_preprint":false},{"pmid":"38880224","id":"PMC_38880224","title":"Acetylation-dependent deubiquitinase USP26 stabilizes BAG3 to promote breast cancer progression.","date":"2024","source":"Cancer letters","url":"https://pubmed.ncbi.nlm.nih.gov/38880224","citation_count":8,"is_preprint":false},{"pmid":"32545415","id":"PMC_32545415","title":"RAC1B Induces SMAD7 via USP26 to Suppress TGFβ1-Dependent Cell Migration in Mesenchymal-Subtype Carcinoma Cells.","date":"2020","source":"Cancers","url":"https://pubmed.ncbi.nlm.nih.gov/32545415","citation_count":8,"is_preprint":false},{"pmid":"35857630","id":"PMC_35857630","title":"An RNF12-USP26 amplification loop drives germ cell specification and is disrupted by disease-associated mutations.","date":"2022","source":"Science signaling","url":"https://pubmed.ncbi.nlm.nih.gov/35857630","citation_count":7,"is_preprint":false},{"pmid":"38064851","id":"PMC_38064851","title":"Machine learning-based classification of deubiquitinase USP26 and its cell proliferation inhibition through stabilizing KLF6 in cervical cancer.","date":"2023","source":"Computers in biology and 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lymphopoiesis by endogenous tryptophan metabolites.","date":"2026","source":"Journal of advanced research","url":"https://pubmed.ncbi.nlm.nih.gov/41687771","citation_count":1,"is_preprint":false},{"pmid":"41423141","id":"PMC_41423141","title":"A novel candidate missense variant in the catalytic domain of USP26 associated with asthenoteratozoospermia.","date":"2025","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/41423141","citation_count":1,"is_preprint":false},{"pmid":"41125405","id":"PMC_41125405","title":"USP26 Promotes Cell Proliferation of Gastric Cancer by Stabilizing c-Myc.","date":"2025","source":"DNA and cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/41125405","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.09.11.675685","title":"Active maintenance of meiosis-specific chromosome structures in  <i>C. elegans</i>  by the deubiquitinase DUO-1","date":"2025-09-12","source":"bioRxiv","url":"https://doi.org/10.1101/2025.09.11.675685","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":23923,"output_tokens":6239,"usd":0.082677,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":14875,"output_tokens":5618,"usd":0.107412,"stage2_stop_reason":"end_turn"},"total_usd":0.190089,"stage1_batch_id":"msgbatch_01UT1AahFPCAyn2uVweS7A9z","stage2_batch_id":"msgbatch_01HuKWtKNT4Pqj1bc8eEP5RV","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2010,\n      \"finding\": \"USP26 is a nuclear protein that binds to androgen receptor (AR) via three nuclear receptor interaction motifs, modulates AR ubiquitination, and stabilizes AR by counteracting hormone-induced ubiquitination, thereby influencing AR transcriptional activity. USP26 assembles with AR and other cofactors in subnuclear foci.\",\n      \"method\": \"shRNA library screen, Co-IP, subnuclear foci imaging, ubiquitination assay\",\n      \"journal\": \"Molecular cancer research : MCR\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, subnuclear localization, ubiquitination assay, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"20501646\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"USP26 is recruited to DNA double-strand breaks (DSBs) where it removes RNF168-induced ubiquitin conjugates, limits excessive spreading of RAP80-BRCA1 from DSBs, and promotes BRCA1 association with PALB2, thereby facilitating homologous recombination. Depletion of USP26 disrupts HR execution, and this effect is rescued by simultaneous depletion of RAP80.\",\n      \"method\": \"Genetic screen, siRNA depletion, immunofluorescence at DSBs, epistasis (double knockdown rescue), HR reporter assay\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis (double knockdown rescue), direct DSB recruitment demonstrated by imaging, HR functional assay, multiple orthogonal methods in single lab\",\n      \"pmids\": [\"26101254\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"USP26 deubiquitinates and stabilizes SMAD7, functioning as a component of the TGF-β negative feedback loop. TGF-β enhances USP26 expression; USP26 limits ubiquitin-mediated turnover of SMAD7, preventing TGF-β receptor stabilization and reducing p-SMAD2 levels. Knockdown of USP26 degrades SMAD7, stabilizes TGF-β receptor, and enhances TGF-β signaling.\",\n      \"method\": \"Co-IP, ubiquitination assay, siRNA knockdown, western blot for p-SMAD2 and receptor levels\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, ubiquitination assay, and RNAi functional phenotype in single lab with multiple orthogonal methods\",\n      \"pmids\": [\"28381482\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"USP26 negatively regulates somatic cell reprogramming by stabilizing PRC1 complex components CBX4 and CBX6 through removal of K48-linked polyubiquitination. Accumulated CBX4 and CBX6 repress pluripotency genes (Sox2, Nanog) by ubiquitinating histone H2A at their promoters via PRC1 complexes.\",\n      \"method\": \"Co-IP, ubiquitination assay (K48-linkage specific), reprogramming efficiency assay, ChIP for H2A ubiquitination at promoters, siRNA/overexpression\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — linkage-specific ubiquitination assay, Co-IP, ChIP, functional reprogramming assay; multiple orthogonal methods in single lab\",\n      \"pmids\": [\"28839133\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"USP26 binds to Mdm2 through its coiled-coil C-terminal domain, deubiquitinates Mdm2, and stabilizes it. USP26 itself can be ubiquitinated in cell-free HeLa extract.\",\n      \"method\": \"Co-transfection, Co-IP, cell-free ubiquitination assay, half-life analysis\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — Co-IP and cell-free ubiquitination assay, single lab, single study\",\n      \"pmids\": [\"27810359\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"The USP26 R344W missense mutation reduces USP26 binding affinity to AR and abolishes its deubiquitinating activity toward AR, thereby eliminating the inhibitory effect of USP26 on AR transcriptional activity in HeLa and TM4 cells.\",\n      \"method\": \"Immunoprecipitation, ubiquitination assay, luciferase transcriptional activity assay\",\n      \"journal\": \"Reproductive sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — Co-IP, ubiquitination assay, and functional reporter assay; single lab, single study\",\n      \"pmids\": [\"27089915\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"USP26 deubiquitinates and stabilizes Snail, a transcription factor promoting epithelial-mesenchymal transition (EMT), and promotes esophageal squamous cell carcinoma cell migration and invasion. Identified by screening a DUB library.\",\n      \"method\": \"DUB library screen, Co-IP, ubiquitination assay, cell migration/invasion assay\",\n      \"journal\": \"Cancer letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — DUB library screen, Co-IP, ubiquitination assay, functional cellular assay; single lab, single study\",\n      \"pmids\": [\"30763716\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Usp26 mutant male mice (DBA/2 background, but not C57BL/6) are sterile or subfertile with atrophic testes, reduced spermatids, malformed sperm head morphology, unsynapsed chromosomes in pachynema, and defective chiasma formation in diplonema, leading to apoptosis of metaphase spermatocytes. Effects are genetic-background dependent.\",\n      \"method\": \"Mouse knockout (gene-targeted mutation), histology, spermatocyte cytology (chromosome spread), fertility assessment\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — defined in vivo KO with specific cellular and meiotic phenotypes, multiple complementary analyses, replicated across two genetic backgrounds\",\n      \"pmids\": [\"31551464\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Two independently generated Usp26-null mouse lines show no overt phenotype: both males and females are fertile, with normal spermatocyte synapsis, chromosome dynamics, DNA repair, recombination, and cell-type distribution in testes. USP26 is thus not essential for mouse gametogenesis.\",\n      \"method\": \"Mouse knockout (two independent null alleles), cytology, histopathology, fertility assessment\",\n      \"journal\": \"Chromosoma\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two independent KO alleles, comprehensive cytological and histological analyses; negative result is well-supported\",\n      \"pmids\": [\"30887115\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"USP26 protein localizes to the XY body during meiosis. Knockout of Usp26 in male mice causes incomplete sex chromosome pairing by destabilizing TEX11, leading to XY aneuploid spermatozoa and 41,XXY (Klinefelter syndrome) offspring. USP26 variants in men increase the proportion of XY aneuploid spermatozoa.\",\n      \"method\": \"Mouse knockout, immunofluorescence (XY body localization), Co-IP/western blot (TEX11 destabilization), clinical sperm FISH aneuploidy analysis\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo KO, direct localization experiment, protein interaction/stability assay, and clinical validation across multiple approaches\",\n      \"pmids\": [\"33978233\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"RNF12 relieves REX1-mediated repression of Usp26, increasing USP26 abundance. USP26 then forms complexes with RNF12 and prevents RNF12 autoubiquitylation and proteasomal degradation, establishing a transcriptional feed-forward amplification loop. This RNF12-USP26 axis operates in mouse testes and is required for gametogenesis gene expression and germ cell differentiation. RLIM (RNF12) and USP26 disease-associated variants disrupt this axis.\",\n      \"method\": \"Quantitative proteomics (global), Co-IP, ubiquitination assay, ESC differentiation assay, mutagenesis with patient variants\",\n      \"journal\": \"Science signaling\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — global proteomics, reciprocal Co-IP, ubiquitination assay, functional differentiation assay, and mutagenesis; multiple orthogonal methods\",\n      \"pmids\": [\"35857630\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"USP26 interacts with, deubiquitylates, and stabilizes TAZ (a Hippo pathway effector) in anaplastic thyroid cancer cells in a deubiquitylation activity-dependent manner. USP26 depletion decreases TAZ protein levels and reduces expression of TAZ/TEAD target genes (CTGF, ANKRD1, CYR61).\",\n      \"method\": \"Co-IP, ubiquitination assay, catalytic mutant (activity-dependent rescue), siRNA knockdown with target gene expression readout\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — Co-IP, ubiquitination assay, activity-dependent rescue; single lab, single study\",\n      \"pmids\": [\"35397626\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"The USP26 Q156H mutant has no enzymatic (deubiquitinase) activity toward model substrates Ub-Met-β-gal and GST-Ub52. Eighteen other tested mutants (including E174# and E189# truncation mutants) retain wild-type enzymatic activity. Artificially constructed truncation fragments (each half alone) lose activity.\",\n      \"method\": \"In vitro USP cleavage assay with site-directed mutagenesis\",\n      \"journal\": \"Gene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — in vitro enzymatic assay with mutagenesis, single lab; single study\",\n      \"pmids\": [\"29111204\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Five frequent USP26 mutations (c.363_364insACA, c.494T>C, c.1423C>T, c.1090C>T, c.1737G>A) do not affect USP26 deubiquitinase enzymatic activity in a USP cleavage assay.\",\n      \"method\": \"In vitro USP cleavage assay\",\n      \"journal\": \"Andrology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — in vitro enzymatic assay, single lab, single study; negative result well-supported\",\n      \"pmids\": [\"25755145\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"USP26 directly interacts with PRKN (Parkin), deubiquitinates PRKN at the K129 site, and reduces its activity, thereby restraining PRKN-mediated mitophagy. A K129R mutation on PRKN diminishes its activation and mitophagy capacity.\",\n      \"method\": \"Co-IP, ubiquitination assay (site-specific K129), site-directed mutagenesis (K129R), mitophagy assay\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — Co-IP, site-specific ubiquitination assay, mutagenesis; single lab, single study\",\n      \"pmids\": [\"38565942\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"HBV-encoded HBx binds to the USP26 promoter and induces USP26 expression. USP26 then associates with SIRT1 and stabilizes it by deubiquitination, promoting HCC cell proliferation and inhibiting apoptosis.\",\n      \"method\": \"sgRNA DUB library screen, Co-IP, ubiquitination assay, murine Usp26 KO model, promoter binding assay\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — sgRNA library screen, Co-IP, ubiquitination assay, in vivo KO model, promoter binding; multiple orthogonal methods\",\n      \"pmids\": [\"39251623\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"USP26 deubiquitinates and stabilizes SIRT2 in BMSCs; loss of USP26 leads to SIRT2 ubiquitin-mediated degradation, causing mitochondrial dysfunction and BMSC senescence. HIF-1α promotes USP26 transcription by binding to the -191 to -198 bp and -262 to -269 bp regions of the USP26 promoter.\",\n      \"method\": \"Co-IP, ubiquitination assay, mitochondrial function assay, promoter-reporter assay, ChIP\",\n      \"journal\": \"Advanced science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — Co-IP, ubiquitination assay, promoter-reporter with ChIP; single lab, single study\",\n      \"pmids\": [\"39377219\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"USP26 suppresses type I interferon signaling by physically interacting with TRAF3 and removing K63-linked polyubiquitination from TRAF3, thereby inhibiting the MAVS/TBK-1/IRF3 antiviral signaling pathway. USP26 knockdown enhances IFN-β and ISG expression and inhibits EV71 replication.\",\n      \"method\": \"Co-IP, linkage-specific ubiquitination assay (K63), siRNA knockdown, IFN-β/ISG reporter assay, viral replication assay\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — Co-IP, linkage-specific ubiquitination assay, functional antiviral assay; single lab, single study\",\n      \"pmids\": [\"39058724\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"USP26 interacts with and deubiquitinates BAG3, increasing its protein stability. This interaction is enhanced by Tip60-mediated acetylation of USP26 at K134, which increases USP26 binding affinity to BAG3.\",\n      \"method\": \"Co-IP, ubiquitination assay, acetylation assay (Tip60), site-directed mutagenesis (K134), protein stability (half-life) assay\",\n      \"journal\": \"Cancer letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — Co-IP, ubiquitination and acetylation assays, mutagenesis; single lab, single study\",\n      \"pmids\": [\"38880224\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Elevated cellular ROS levels suppress USP26 deubiquitinase activity, leading to increased ubiquitination and proteasomal degradation of AR and ARv7 in prostate cancer cells, thereby increasing enzalutamide sensitivity.\",\n      \"method\": \"In vitro deubiquitinating enzyme activity assay, ROS measurement (dihydroethidium staining), ubiquitination assay\",\n      \"journal\": \"Cancers\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — in vitro DUB activity assay and ROS-mediated inhibition; single lab, single study\",\n      \"pmids\": [\"32235588\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"RAC1B promotes USP26 transcriptional induction, which in turn deubiquitinates and stabilizes SMAD7 protein, enabling SMAD7-mediated suppression of ALK5 and TGF-β1-induced cell migration in mesenchymal-type carcinoma cells.\",\n      \"method\": \"RNAi knockdown epistasis, western blot, ALK5 promoter reporter, cell migration assay\",\n      \"journal\": \"Cancers\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — epistatic RNAi analysis, pathway placement via functional rescue; single lab, single study\",\n      \"pmids\": [\"32545415\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"USP26 interacts with AR by Co-IP and deubiquitinates AR in Leydig cells (TM3), upregulating CCND1 and SPATA46 and decreasing TP73, promoting G1-G2 cell cycle transition and Leydig cell proliferation through the AR signaling pathway.\",\n      \"method\": \"Co-IP, immunofluorescence, western blot, flow cytometry cell cycle assay\",\n      \"journal\": \"Advances in clinical and experimental medicine\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP, immunofluorescence, and flow cytometry; limited mechanistic follow-up, single lab\",\n      \"pmids\": [\"33064378\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"USP26 is the sole DUB identified from a DUB library screen that associates with KLF6. USP26 interacts with KLF6 (interaction domain mapped to residues 285-913 of USP26), deubiquitinates it, and prolongs KLF6 protein stability, inhibiting proliferation and migration of HeLa cells.\",\n      \"method\": \"DUB library screen, Co-IP (domain mapping), ubiquitination assay, half-life assay, shRNA knockdown, proliferation/migration assay\",\n      \"journal\": \"Computers in biology and medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — DUB library screen, Co-IP with domain mapping, ubiquitination assay, functional cellular assay; single lab, single study\",\n      \"pmids\": [\"38064851\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In osteoblasts, USP26 loss decreases H3K18 lactylation at the KSRP promoter, reducing KSRP expression and decreasing alternative splicing of FSTL1 mRNA, leading to elevated FSTL1 expression, insulin resistance, and multi-organ fibrosis.\",\n      \"method\": \"Osteoblast-specific Usp26 conditional KO mouse, ChIP (H3K18LA), RT-PCR (alternative splicing), metabolic and fibrosis phenotyping\",\n      \"journal\": \"Advanced science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — conditional KO with ChIP and splicing assays, single lab; novel mechanistic pathway with moderate experimental support\",\n      \"pmids\": [\"41417635\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In osteoblasts, USP26 prevents ubiquitin-mediated degradation of IL4I1. Loss of USP26 in osteoblasts collapses IL4I1-mediated tryptophan metabolism (reducing indole-3-acetic acid production), impairing B lymphopoiesis and increasing susceptibility to sepsis.\",\n      \"method\": \"Osteoblast-specific Usp26 conditional KO mouse, targeted metabolomics, transcriptomics, in vivo/in vitro IL4I1 supplementation/inhibition, bone-targeting exosome delivery\",\n      \"journal\": \"Journal of advanced research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — conditional KO with metabolomics and functional immune assays; single lab, novel finding\",\n      \"pmids\": [\"41687771\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"USP26 interacts with and stabilizes c-Myc by suppressing its polyubiquitination and degradation, promoting aerobic glycolysis and proliferation in gastric cancer cells.\",\n      \"method\": \"Co-IP, ubiquitination assay, shRNA knockdown, proliferation/glycolysis assay\",\n      \"journal\": \"DNA and cell biology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP and ubiquitination assay; single lab, single study, limited mechanistic depth\",\n      \"pmids\": [\"41125405\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"USP26 protein colocalizes with androgen receptor in human testis, predominantly in Leydig cell nuclei (and to a lesser degree in spermatogonia, primary spermatocytes, round spermatids, and Sertoli cells), as established by immunofluorescence colocalization in human testis tissue.\",\n      \"method\": \"Immunofluorescence colocalization in formalin-fixed/paraffin-embedded and frozen human testis tissue\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Weak — direct immunofluorescence localization in human tissue with AR colocalization; single lab, single study\",\n      \"pmids\": [\"24922532\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"USP26 is an X-linked deubiquitinating enzyme (DUB) that stabilizes multiple substrates—including AR, SMAD7, Snail, TAZ, CBX4/CBX6 (PRC1 components), Mdm2, PRKN, SIRT1, SIRT2, BAG3, KLF6, c-Myc, IL4I1, and TEX11—by removing ubiquitin chains and preventing proteasomal degradation; it localizes to the XY body and subnuclear foci, is recruited to DNA double-strand breaks to remove RNF168-induced ubiquitin conjugates and facilitate homologous recombination, forms a feed-forward amplification loop with RNF12, and suppresses antiviral type I interferon signaling via TRAF3 deubiquitination, with its activity regulated by cellular ROS levels and Tip60-mediated acetylation.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"USP26 is an X-linked deubiquitinating enzyme that controls the abundance of diverse regulatory proteins by cleaving ubiquitin chains and shielding substrates from proteasomal degradation, with prominent roles in male germ cell development, genome maintenance, and signaling control [#0, #9]. Its catalytic activity depends on a core USP domain whose integrity is required for substrate cleavage [#12]. In the nucleus, USP26 binds androgen receptor through nuclear-receptor interaction motifs and stabilizes it by reversing hormone-induced ubiquitination, thereby tuning AR transcriptional output [#0]. During meiosis it localizes to the XY body and stabilizes TEX11 to enforce proper sex-chromosome pairing, and its loss produces XY-aneuploid spermatozoa [#9]. USP26 acts as a regulator of signaling feedback by deubiquitinating and stabilizing SMAD7 within a TGF-\\u03b2 negative feedback loop [#2], and it amplifies its own expression through a feed-forward loop with RNF12 in which it blocks RNF12 autoubiquitylation, an axis required for gametogenesis gene expression [#10]. At DNA double-strand breaks USP26 removes RNF168-induced ubiquitin conjugates, restrains RAP80-BRCA1 spreading, and promotes BRCA1-PALB2 association to enable homologous recombination [#1]. Across multiple cancer and stem-cell contexts USP26 stabilizes a broad substrate set including PRC1 components CBX4/CBX6 [#3], Snail [#6], TAZ [#11], SIRT1 [#15], and SIRT2 [#16], and its enzymatic activity is itself regulated\\u2014suppressed by elevated cellular ROS [#19] and enhanced toward BAG3 by Tip60-mediated acetylation [#18]. Whether USP26 is essential for mouse fertility is unresolved within the corpus: one knockout study reports background-dependent sterility and meiotic defects [#7] while two independent null lines show normal fertility [#8].\",\n  \"teleology\": [\n    {\n      \"year\": 2010,\n      \"claim\": \"Established USP26's first molecular function: that it is a nuclear DUB acting on a defined substrate (AR) rather than an orphan enzyme.\",\n      \"evidence\": \"shRNA screen, reciprocal Co-IP, subnuclear foci imaging, and ubiquitination assay\",\n      \"pmids\": [\"20501646\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define the linkage type removed from AR\", \"Physiological context of AR regulation not addressed\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Placed USP26 in a tissue context by showing AR colocalization predominantly in human Leydig cell nuclei, linking the AR interaction to testis biology.\",\n      \"evidence\": \"Immunofluorescence colocalization in human testis tissue\",\n      \"pmids\": [\"24922532\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Colocalization is correlative, not functional\", \"Single-lab tissue study\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Revealed a genome-maintenance role distinct from transcriptional regulation: USP26 trims RNF168-dependent ubiquitin at DSBs to channel repair toward homologous recombination.\",\n      \"evidence\": \"Genetic screen, DSB immunofluorescence, RAP80 double-knockdown epistasis, and HR reporter assay\",\n      \"pmids\": [\"26101254\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct DSB substrate of the DUB activity not biochemically defined\", \"Recruitment mechanism to breaks unknown\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Defined USP26 as a node in TGF-\\u03b2 negative feedback by showing it stabilizes SMAD7 to dampen receptor signaling.\",\n      \"evidence\": \"Co-IP, ubiquitination assay, siRNA knockdown with p-SMAD2 and receptor readouts\",\n      \"pmids\": [\"28381482\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Ubiquitin linkage specificity on SMAD7 not resolved\", \"In vivo relevance not tested\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Connected USP26 to chromatin/pluripotency control by demonstrating K48-specific deubiquitination and stabilization of PRC1 components CBX4/CBX6 that repress pluripotency genes.\",\n      \"evidence\": \"K48-linkage-specific ubiquitination assay, Co-IP, ChIP for H2A ubiquitination, reprogramming assay\",\n      \"pmids\": [\"28839133\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether USP26 directly contacts both CBX proteins versus the assembled PRC1 not separated\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Mapped the catalytic requirement: identified Q156 as essential for DUB activity and showed each domain half alone is inactive, defining the functional core.\",\n      \"evidence\": \"In vitro USP cleavage assay with site-directed mutagenesis on model substrates\",\n      \"pmids\": [\"29111204\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of the active site\", \"Activity tested only on model substrates\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Extended the substrate repertoire to Mdm2 and showed USP26 itself is subject to ubiquitination, hinting at autoregulation of the DUB.\",\n      \"evidence\": \"Co-transfection, Co-IP, cell-free ubiquitination, and half-life analysis\",\n      \"pmids\": [\"27810359\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"E3 ligase ubiquitinating USP26 not identified\", \"Single study without functional downstream readout\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Linked a disease-associated variant to function by showing the R344W mutation abolishes AR deubiquitination and binding, providing a genotype-mechanism connection.\",\n      \"evidence\": \"Immunoprecipitation, ubiquitination assay, luciferase reporter in HeLa and TM4 cells\",\n      \"pmids\": [\"27089915\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Clinical penetrance of R344W not established here\", \"Single-lab study\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Confronted USP26's role in fertility with conflicting in vivo data: background-dependent meiotic failure in one model versus no phenotype in two independent null lines.\",\n      \"evidence\": \"Independent mouse knockout lines with spermatocyte cytology, histology, and fertility assessment\",\n      \"pmids\": [\"31551464\", \"30887115\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Genetic-background modifiers not identified\", \"Reason for discordance between knockout lines unresolved\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Broadened the oncogenic substrate set by showing USP26 stabilizes the EMT driver Snail to promote carcinoma migration and invasion.\",\n      \"evidence\": \"DUB library screen, Co-IP, ubiquitination assay, migration/invasion assays\",\n      \"pmids\": [\"30763716\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Linkage specificity on Snail not defined\", \"Single-lab study\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Showed USP26 activity is environmentally tuned: elevated ROS suppresses its DUB activity, destabilizing AR/ARv7 and sensitizing prostate cancer cells to enzalutamide.\",\n      \"evidence\": \"In vitro DUB activity assay, ROS measurement, ubiquitination assay\",\n      \"pmids\": [\"32235588\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular basis of ROS sensitivity (e.g. cysteine oxidation) not mapped\", \"Single study\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Positioned USP26 downstream of RAC1B in the SMAD7/TGF-\\u03b2 axis and as an AR-pathway driver of Leydig cell proliferation, integrating it into upstream signaling control.\",\n      \"evidence\": \"RNAi epistasis with promoter reporters and migration assays; Co-IP with cell-cycle flow cytometry\",\n      \"pmids\": [\"32545415\", \"33064378\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Leydig cell study is Low confidence with limited mechanistic depth\", \"Direct versus indirect transcriptional induction of USP26 not separated\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Defined the meiotic mechanism: USP26 localizes to the XY body and stabilizes TEX11 to ensure sex-chromosome pairing, with loss producing XY-aneuploid sperm and Klinefelter offspring.\",\n      \"evidence\": \"Mouse knockout, XY-body immunofluorescence, TEX11 stability assays, clinical sperm FISH aneuploidy analysis\",\n      \"pmids\": [\"33978233\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Reconciliation with the no-phenotype knockout lines not resolved\", \"Linkage type removed from TEX11 not specified\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Uncovered a self-amplifying circuit: RNF12 de-represses Usp26 transcription, and USP26 in turn blocks RNF12 autoubiquitylation, forming a feed-forward loop required for gametogenesis gene expression.\",\n      \"evidence\": \"Quantitative proteomics, reciprocal Co-IP, ubiquitination assay, ESC differentiation, patient-variant mutagenesis\",\n      \"pmids\": [\"35857630\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Quantitative thresholds of the loop not modeled\", \"How disease variants quantitatively perturb the loop incompletely defined\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Added the Hippo effector TAZ as an activity-dependent substrate, linking USP26 to TAZ/TEAD target gene expression in anaplastic thyroid cancer.\",\n      \"evidence\": \"Co-IP, ubiquitination assay, catalytic-mutant rescue, siRNA with target-gene readout\",\n      \"pmids\": [\"35397626\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab study\", \"Whether TAZ regulation occurs outside thyroid cancer not tested\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identified KLF6 as a USP26 substrate via domain-mapped interaction (residues 285-913), with stabilization restraining cell proliferation and migration.\",\n      \"evidence\": \"DUB library screen, Co-IP with domain mapping, half-life and ubiquitination assays, functional cellular assays\",\n      \"pmids\": [\"38064851\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single study\", \"Physiological tissue context not addressed\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Showed USP26 regulates mitophagy and antiviral immunity through site- and linkage-specific deubiquitination of PRKN (K129) and TRAF3 (K63), and is itself activated toward BAG3 by Tip60 acetylation at K134.\",\n      \"evidence\": \"Co-IP, site/linkage-specific ubiquitination assays, mutagenesis (K129R, K134), acetylation assay, mitophagy and IFN-\\u03b2/ISG reporter assays\",\n      \"pmids\": [\"38565942\", \"39058724\", \"38880224\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Each substrate documented in a single study\", \"Cross-pathway coordination among these substrates not examined\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Tied USP26 to cancer cell survival via virus- and hypoxia-driven transcription and stabilization of SIRT1 and SIRT2, controlling proliferation, apoptosis, and mitochondrial function.\",\n      \"evidence\": \"DUB/sgRNA library screens, Co-IP, ubiquitination assays, in vivo KO, promoter binding/ChIP, mitochondrial assays\",\n      \"pmids\": [\"39251623\", \"39377219\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether SIRT1 and SIRT2 are regulated in the same cells not addressed\", \"Linkage specificity on SIRT2 not fully defined\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Revealed osteoblast-intrinsic roles via conditional knockout: USP26 sustains an H3K18-lactylation/KSRP/FSTL1 splicing axis and stabilizes IL4I1 to support tryptophan metabolism and B lymphopoiesis, with systemic metabolic and immune consequences.\",\n      \"evidence\": \"Osteoblast-specific conditional KO mice, ChIP (H3K18LA), splicing RT-PCR, targeted metabolomics, immune phenotyping\",\n      \"pmids\": [\"41417635\", \"41687771\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism connecting USP26 DUB activity to H3K18 lactylation not direct\", \"Single-lab conditional KO findings\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Added c-Myc stabilization driving aerobic glycolysis in gastric cancer to the substrate list.\",\n      \"evidence\": \"Co-IP, ubiquitination assay, shRNA knockdown, glycolysis/proliferation assays\",\n      \"pmids\": [\"41125405\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single Co-IP/ubiquitination assay with limited mechanistic depth\", \"No structural or linkage characterization\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How a single DUB selects among this very broad substrate set and how its tissue-restricted, ROS- and acetylation-regulated activity is coordinated in vivo remains unresolved, as does the discordance between knockout phenotypes.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural basis for substrate selectivity\", \"No unified model reconciling fertile versus sterile knockout lines\", \"Substrate-recruitment determinants largely undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 1, 2, 3, 9, 11, 14, 15, 16, 17, 18]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [12, 13, 19]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 2, 10]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 26]},\n      {\"term_id\": \"GO:0005654\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [2, 11, 20]},\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [9, 10]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [17, 24]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [0, 2, 3, 15]}\n    ],\n    \"complexes\": [\"RNF12-USP26 feed-forward complex\"],\n    \"partners\": [\"AR\", \"SMAD7\", \"RNF12\", \"TEX11\", \"MDM2\", \"TRAF3\", \"PRKN\", \"BAG3\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"tie","faith_supported":8,"faith_total":8,"faith_pct":100.0}}