{"gene":"JOSD2","run_date":"2026-04-28T18:06:54","timeline":{"discoveries":[{"year":2020,"finding":"JOSD2 directly deubiquitinates and stabilizes a glycolytic enzyme complex including Aldolase A, Phosphofructokinase-1, and Phosphoglycerate dehydrogenase, enhancing their activities and the glycolytic rate; a catalytically inactive JOSD2 mutant fails to do so, demonstrating the requirement for deubiquitinase activity.","method":"In vitro and in vivo deubiquitination assays, catalytically inactive mutant analysis, glycolytic rate measurement, Co-IP","journal":"Cell death and differentiation","confidence":"High","confidence_rationale":"Tier 1-2 — multiple orthogonal methods including in vitro assay, mutagenesis, and functional metabolic readouts in a single study","pmids":["33082514"],"is_preprint":false},{"year":2021,"finding":"JOSD2 deubiquitinates YAP and TAZ, cleaving their polyubiquitin chains in a deubiquitinase activity-dependent manner to prevent proteasomal degradation, thereby sustaining YAP/TAZ protein levels in cholangiocarcinoma cells.","method":"Deubiquitination assay, proteasome inhibitor rescue, JOSD2 knockdown with YAP/TAZ protein level measurement, in vitro and in vivo proliferation assays","journal":"Acta pharmaceutica Sinica. B","confidence":"High","confidence_rationale":"Tier 1-2 — deubiquitinase activity-dependent mechanism established with catalytic mutant and proteasomal degradation rescue","pmids":["35024322"],"is_preprint":false},{"year":2022,"finding":"JOSD2 interacts with PKM2 and inhibits its nuclear localization by reducing K433 acetylation of PKM2, without affecting PKM2 protein stability.","method":"Mass spectrometry, co-immunoprecipitation, co-immunofluorescence, nuclear/cytoplasmic fractionation, acetylation assays","journal":"Experimental hematology & oncology","confidence":"Medium","confidence_rationale":"Tier 2 — reciprocal Co-IP and MS identification with functional nuclear localization readout, single lab","pmids":["35836282"],"is_preprint":false},{"year":2022,"finding":"JOSD2 binds to and deubiquitinates CTNNB1 (β-catenin), reducing its ubiquitination level and preventing its degradation, thereby augmenting Wnt signaling in hepatocellular carcinoma cells.","method":"Co-immunoprecipitation, ubiquitination assay, rescue experiments with CTNNB1 manipulation","journal":"Cell biology international","confidence":"Medium","confidence_rationale":"Tier 2-3 — Co-IP and ubiquitination assay with functional rescue, single lab","pmids":["35568970"],"is_preprint":false},{"year":2023,"finding":"JOSD2 deubiquitinates and stabilizes SERCA2a (sarco/endoplasmic reticulum calcium ATPase 2a) in cardiomyocytes; JOSD2 deficiency impairs calcium handling and promotes cardiac hypertrophy, while cardiac-specific JOSD2 overexpression via AAV9 prevents angiotensin II-induced hypertrophy.","method":"Proteome-wide quantitative analysis, Co-IP, deubiquitination assay, Josd2 knockout mice, AAV9-mediated overexpression, calcium imaging","journal":"Nature cardiovascular research","confidence":"High","confidence_rationale":"Tier 1-2 — in vivo genetic KO and AAV-mediated OE with defined calcium handling phenotype, proteomics substrate identification, multiple orthogonal methods","pmids":["39195964"],"is_preprint":false},{"year":2024,"finding":"JOSD2 restricts the kinase activity of LKB1 by removing K6-linked polyubiquitination from LKB1, an action vital for maintaining the integrity of the LKB1-STRAD-MO25 complex in NSCLC.","method":"Co-IP, ubiquitination linkage-specific assay (K6-linked), LKB1 kinase activity assay, JOSD2 knockdown and pharmacological inhibition in cell/PDX models","journal":"Signal transduction and targeted therapy","confidence":"High","confidence_rationale":"Tier 1-2 — specific ubiquitin linkage identified, kinase activity assay used as functional readout, validated in vitro and in vivo","pmids":["38177135"],"is_preprint":false},{"year":2024,"finding":"JOSD2 interacts with CaMKIIδ and directly hydrolyzes K63-linked polyubiquitin chains on CaMKIIδ, increasing its phosphorylation and thereby causing calcium mishandling, hypertrophy, and fibrosis in cardiomyocytes; these effects are reversible by the CaMKIIδ inhibitor KN-93.","method":"Mass spectrometry, Co-IP, K63-specific deubiquitination assay, CaMKIIδ phosphorylation measurement, JOSD2 KO and OE in vivo, KN-93 rescue","journal":"Cellular and molecular life sciences : CMLS","confidence":"High","confidence_rationale":"Tier 1-2 — specific ubiquitin linkage established, pharmacological rescue confirms pathway placement, multiple orthogonal methods","pmids":["38195959"],"is_preprint":false},{"year":2024,"finding":"JOSD2 deubiquitinates IMPDH2 by preferentially cleaving K63-linked polyubiquitin chains at the K134 site of IMPDH2, suppressing IMPDH2 activity and preventing NF-κB activation and inflammation in macrophages.","method":"Co-IP, K63-linkage-specific ubiquitination assay, site-directed mutagenesis (K134), IMPDH2 activity assay, NF-κB reporter assay, myeloid-specific JOSD2 KO mice, bone marrow transplantation","journal":"Acta pharmaceutica Sinica. B","confidence":"High","confidence_rationale":"Tier 1-2 — specific ubiquitin linkage and lysine site identified by mutagenesis, enzyme activity assay, in vivo myeloid-specific KO with functional phenotype","pmids":["40177575"],"is_preprint":false},{"year":2023,"finding":"JOSD2 promotes DNA damage repair in NSCLC cells; DNA damaging agents increase nuclear localization of JOSD2, and JOSD2 depletion sensitizes NSCLC cells to DNA damaging agents.","method":"Immunofluorescence (nuclear localization), Western blotting (DDR pathway proteins), SRB cytotoxicity assay upon JOSD2 knockdown with DNA damaging drugs","journal":"Journal of Zhejiang University. Medical sciences","confidence":"Low","confidence_rationale":"Tier 3 — localization and sensitization shown but no direct substrate or molecular mechanism of DDR regulation identified","pmids":["37899394"],"is_preprint":false},{"year":2025,"finding":"JOSD2 directly interacts with and stabilizes KRAS mutant proteins by reverting their proteolytic ubiquitination; reciprocally, KRAS mutants inhibit the catalytic activity of CHIP (an E3 ubiquitin ligase for JOSD2), forming a positive feedback circuit that accelerates KRAS-mutant CRC growth.","method":"DUB siRNA library screen, Co-IP, ubiquitination assay, CHIP E3 ligase activity assay, JOSD2 KD and pharmacological inhibition in PDC/PDX/PDO models","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1-2 — bidirectional regulatory circuit established with E3 ligase activity assay and validated in multiple patient-derived models","pmids":["40240366"],"is_preprint":false},{"year":2025,"finding":"JOSD2 specifically binds to the MH1 domain of SMAD7 and removes K48-linked ubiquitin chains from SMAD7 at lysine 220, sustaining SMAD7 stability and thereby inhibiting TGFβ-SMAD signaling in vascular smooth muscle cells.","method":"LC-MS/MS, Co-IP, K48-linkage-specific ubiquitination assay, site-directed mutagenesis (K220), SMAD7 stability assay, RNA-seq, VSMC-specific JOSD2 OE in mice","journal":"Acta pharmacologica Sinica","confidence":"High","confidence_rationale":"Tier 1-2 — specific ubiquitin linkage and lysine site identified by mutagenesis, in vivo validation with cell-type-specific OE","pmids":["39833306"],"is_preprint":false},{"year":2025,"finding":"JOSD2 removes K63-linked ubiquitination from SIRT7 via its active site C24, promoting P62-mediated autophagic degradation of SIRT7, which prevents P65 phosphorylation and nuclear translocation, thereby reducing inflammatory responses in renal tubular epithelial cells during acute kidney injury.","method":"Mass spectrometry, Co-IP, K63-linkage-specific ubiquitination assay, active-site mutagenesis (C24), P62/autophagy pathway analysis, renal tubular-specific JOSD2 OE in mice, cisplatin and IRI AKI models","journal":"Acta pharmacologica Sinica","confidence":"High","confidence_rationale":"Tier 1-2 — active site mutagenesis, specific ubiquitin linkage, autophagy mechanism, and in vivo validation with cell-type-specific OE","pmids":["40217118"],"is_preprint":false},{"year":2025,"finding":"JOSD2 interacts with and stabilizes SMAD4 by removing polyubiquitin chains, thereby activating TGF-β signaling and promoting breast cancer metastasis.","method":"Co-IP, ubiquitination assay, JOSD2 RNAi, in vitro migration/invasion assays, in vivo metastasis model","journal":"Biochemical pharmacology","confidence":"Medium","confidence_rationale":"Tier 2-3 — Co-IP and ubiquitination assay with in vivo validation, single lab, ubiquitin linkage type not specified","pmids":["39793716"],"is_preprint":false},{"year":2025,"finding":"JOSD2 suppresses cGAS enzymatic activity by removing K27-linked ubiquitination from cGAS, thereby inhibiting cGAS-STING signaling and promoting M2 macrophage polarization and immune evasion in colorectal cancer.","method":"Co-IP, K27-linkage-specific ubiquitination assay, cGAS enzymatic activity assay, JOSD2 catalytic inhibitor (HY041004), macrophage polarization assay, in vivo CRC model","journal":"Oncoimmunology","confidence":"High","confidence_rationale":"Tier 1-2 — specific ubiquitin linkage identified, enzyme activity assay for cGAS, pharmacological inhibition with in vivo validation","pmids":["41351298"],"is_preprint":false},{"year":2025,"finding":"JOSD2 deubiquitinates the K63-linked ubiquitin chain of AKT via its active site H125 and enhances P62-mediated autophagic degradation of AKT in renal tubular epithelial cells, reducing AKT levels and thereby reducing renal EMT and fibrosis.","method":"Mass spectrometry, Co-IP, K63-linkage-specific ubiquitination assay, active-site mutagenesis (H125), autophagy assay, JOSD2 KO mice, single-cell RNA-seq, TEC-specific JOSD2 OE","journal":"Cellular signalling","confidence":"High","confidence_rationale":"Tier 1-2 — active site mutagenesis, specific ubiquitin linkage, autophagy mechanism established, cell-type-specific in vivo validation","pmids":["41412561"],"is_preprint":false},{"year":2025,"finding":"A small-molecule covalent inhibitor of JOSD2 (compound 31) was designed with a cyanamide warhead that selectively engages the catalytic cysteine residue of JOSD2, confirming the catalytic cysteine as the active site and demonstrating that JOSD2 inhibition induces downregulation of KRAS protein in CRC cells.","method":"Covalent binding assay, structure-activity relationship, KRAS protein level measurement after inhibitor treatment","journal":"Bioorganic chemistry","confidence":"Medium","confidence_rationale":"Tier 1-2 — covalent active-site engagement confirmed, but mechanistic depth limited to single functional readout","pmids":["41092805"],"is_preprint":false}],"current_model":"JOSD2 is a Josephin domain-containing deubiquitinase whose catalytic cysteine (C24) removes ubiquitin chains of specific linkages (K6, K27, K48, K63) from diverse substrate proteins including glycolytic enzymes (Aldolase A, PFK1, PHGDH), YAP/TAZ, SERCA2a, CaMKIIδ, LKB1, KRAS mutants, CTNNB1, SMAD4, SMAD7, IMPDH2, SIRT7, AKT, and cGAS, thereby either stabilizing substrates against proteasomal degradation or routing them to autophagic degradation (via P62), with consequences for glycolysis, calcium handling, Wnt/TGFβ/cGAS-STING signaling, and inflammation across multiple cancer and non-cancer contexts."},"narrative":{"teleology":[{"year":2020,"claim":"The initial enzymatic function of JOSD2 was established: it directly deubiquitinates glycolytic enzymes (Aldolase A, PFK1, PHGDH), stabilizing them and enhancing glycolysis—demonstrating that JOSD2 is an active deubiquitinase with metabolic substrates.","evidence":"In vitro deubiquitination assays, catalytically inactive mutant, glycolytic rate measurement, Co-IP in cancer cell lines","pmids":["33082514"],"confidence":"High","gaps":["Ubiquitin linkage specificity on glycolytic substrates not determined","No structural basis for substrate recognition","Whether metabolic effects are relevant in non-cancer cells unknown"]},{"year":2021,"claim":"JOSD2's substrate repertoire was extended to signaling effectors: it deubiquitinates YAP and TAZ to prevent their proteasomal degradation, establishing JOSD2 as a stabilizer of Hippo pathway transcriptional co-activators.","evidence":"Deubiquitination assay with catalytic mutant, proteasome inhibitor rescue, cholangiocarcinoma cell proliferation assays","pmids":["35024322"],"confidence":"High","gaps":["Ubiquitin linkage type on YAP/TAZ not specified","E3 ligase counterpart not identified","In vivo validation lacking"]},{"year":2022,"claim":"Beyond deubiquitination-mediated stabilization, JOSD2 was found to regulate PKM2 nuclear localization by reducing its acetylation, and to stabilize β-catenin by deubiquitination—expanding its mechanisms to include non-degradative regulation and Wnt signaling.","evidence":"Mass spectrometry, Co-IP, nuclear/cytoplasmic fractionation, acetylation assays for PKM2; Co-IP and ubiquitination assays for CTNNB1 in HCC cells","pmids":["35836282","35568970"],"confidence":"Medium","gaps":["Mechanism by which JOSD2 affects PKM2 acetylation is indirect and unexplained","Ubiquitin linkage type on β-catenin not specified","Both findings from single laboratories"]},{"year":2023,"claim":"JOSD2 was shown to stabilize SERCA2a in cardiomyocytes and its deficiency causes impaired calcium handling and cardiac hypertrophy, establishing a non-cancer physiological role for JOSD2 in the heart with in vivo genetic evidence.","evidence":"Proteome-wide analysis, Co-IP, deubiquitination assay, Josd2 KO mice, AAV9-mediated cardiac overexpression, calcium imaging","pmids":["39195964"],"confidence":"High","gaps":["Ubiquitin linkage type on SERCA2a not specified","Whether JOSD2 cardiac effects are solely SERCA2a-dependent or involve additional substrates not resolved"]},{"year":2024,"claim":"Ubiquitin linkage specificity of JOSD2 was resolved for multiple substrates: K6-linked chains on LKB1 (restricting its kinase activity), K63-linked chains on CaMKIIδ (altering phosphorylation and calcium handling), and K63-linked chains on IMPDH2 (suppressing enzymatic activity and NF-κB), revealing that JOSD2 cleaves distinct chain types to modulate enzyme activity rather than solely protein stability.","evidence":"Linkage-specific ubiquitination assays, kinase/enzyme activity assays, active-site and site-directed mutagenesis, in vivo KO mice (myeloid-specific for IMPDH2), pharmacological rescue (KN-93 for CaMKIIδ)","pmids":["38177135","38195959","40177575"],"confidence":"High","gaps":["How JOSD2 achieves selectivity for different linkage types on different substrates is structurally unexplained","Whether K63-chain removal from CaMKIIδ promotes autophagy or only alters signaling not tested","No crystal structure of JOSD2-substrate complex available"]},{"year":2025,"claim":"A dual-outcome model was established: JOSD2 removal of K63-linked ubiquitin from SIRT7 and AKT promotes their P62-mediated autophagic degradation, while removal of K48-linked ubiquitin from SMAD7 and KRAS mutants blocks proteasomal degradation—demonstrating that chain-type specificity dictates whether JOSD2 stabilizes or destabilizes a substrate.","evidence":"Active-site mutagenesis (C24, H125), K63- and K48-linkage-specific assays, P62/autophagy pathway analysis, renal tubular- and VSMC-specific OE in mice, PDC/PDX/PDO for KRAS, site-directed mutagenesis (K220 on SMAD7)","pmids":["40217118","41412561","39833306","40240366"],"confidence":"High","gaps":["Determinants of whether K63-deubiquitination leads to autophagic degradation versus non-degradative signaling change are unknown","Whether JOSD2 acts processively or distributively on chains not tested","Relative contribution of each substrate to in vivo phenotypes not deconvoluted"]},{"year":2025,"claim":"JOSD2 was shown to remove K27-linked ubiquitin from cGAS, suppressing cGAS-STING innate immune signaling and enabling tumor immune evasion, extending the linkage repertoire to K27 and connecting JOSD2 to innate immunity.","evidence":"K27-linkage-specific ubiquitination assay, cGAS enzymatic activity assay, JOSD2 catalytic inhibitor (HY041004), macrophage polarization assay, in vivo CRC model","pmids":["41351298"],"confidence":"High","gaps":["Whether JOSD2 regulation of cGAS is relevant outside of tumor microenvironment not examined","Structural basis for K27-linkage recognition unknown"]},{"year":2025,"claim":"A covalent small-molecule inhibitor targeting the JOSD2 catalytic cysteine was developed, pharmacologically validating the active site and demonstrating that JOSD2 inhibition can downregulate KRAS protein in cancer cells.","evidence":"Cyanamide-warhead covalent binding assay, structure-activity relationship, KRAS protein measurement in CRC cells","pmids":["41092805"],"confidence":"Medium","gaps":["Selectivity over other Josephin-domain DUBs not comprehensively profiled","In vivo pharmacokinetics and efficacy not reported","Whether inhibitor blocks all JOSD2 substrate deubiquitination equally not tested"]},{"year":null,"claim":"Key unresolved questions include how JOSD2 achieves specificity for different ubiquitin linkage types (K6, K27, K48, K63) and different substrates, what structural features govern whether deubiquitination leads to substrate stabilization versus autophagic degradation, and whether a unifying physiological role integrates JOSD2's diverse substrate repertoire.","evidence":"","pmids":[],"confidence":"High","gaps":["No crystal or cryo-EM structure of JOSD2 alone or in complex with any substrate","No systematic substrate profiling (e.g., ubiquitin-SILAC) performed","Relative physiological importance of individual substrates in vivo not ranked"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[0,1,3,4,5,6,7,9,10,11,13,14]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,1,3,4,5,6,7,9,10,11,13,14]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[0,2]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[8]}],"pathway":[{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[0,1,3,4,5,6,7,9,10,11,13,14]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[0,7]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[1,3,5,10,12,13]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[7,13]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[11,14]}],"complexes":[],"partners":["ALDOA","PFKL","SERCA2A","LKB1","KRAS","SMAD7","IMPDH2","CGAS"],"other_free_text":[]},"mechanistic_narrative":"JOSD2 is a Josephin-domain deubiquitinase that cleaves polyubiquitin chains of multiple linkage types (K6, K27, K48, K63) from a broad range of substrate proteins, thereby controlling their stability or activity in metabolic, signaling, and inflammatory pathways. Its catalytic cysteine (C24) and histidine (H125) residues are essential for hydrolysis of ubiquitin chains; removal of K48-linked chains stabilizes substrates such as Aldolase A, PFK1, YAP/TAZ, SERCA2a, SMAD7, KRAS mutants, and β-catenin against proteasomal degradation, whereas removal of K63-linked chains from SIRT7 and AKT routes them to P62-mediated autophagic degradation [PMID:33082514, PMID:35024322, PMID:39195964, PMID:39833306, PMID:40240366, PMID:40217118, PMID:41412561]. JOSD2 also modulates enzyme activity non-degradatively: it removes K6-linked ubiquitin from LKB1 to restrict its kinase function, K63-linked ubiquitin from CaMKIIδ to alter its phosphorylation, K63-linked ubiquitin from IMPDH2 to suppress its enzymatic activity and NF-κB signaling, and K27-linked ubiquitin from cGAS to inhibit cGAS-STING innate immune signaling [PMID:38177135, PMID:38195959, PMID:40177575, PMID:41351298]. Through these diverse substrates, JOSD2 exerts context-dependent roles in glycolysis, cardiac calcium handling and hypertrophy, Wnt and TGF-β signaling, inflammation, renal fibrosis, and tumor immune evasion."},"prefetch_data":{"uniprot":{"accession":"Q8TAC2","full_name":"Josephin-2","aliases":["Josephin domain-containing protein 2"],"length_aa":188,"mass_kda":20.8,"function":"Cleaves 'Lys-63'-linked poly-ubiquitin chains, and with lesser efficiency 'Lys-48'-linked poly-ubiquitin chains (in vitro). May act as a deubiquitinating enzyme","subcellular_location":"Cytoplasm, cytosol","url":"https://www.uniprot.org/uniprotkb/Q8TAC2/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/JOSD2","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/JOSD2","total_profiled":1310},"omim":[{"mim_id":"615324","title":"JOSEPHIN DOMAIN-CONTAINING PROTEIN 2; JOSD2","url":"https://www.omim.org/entry/615324"},{"mim_id":"615323","title":"JOSEPHIN DOMAIN-CONTAINING PROTEIN 1; JOSD1","url":"https://www.omim.org/entry/615323"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/JOSD2"},"hgnc":{"alias_symbol":["SBBI54"],"prev_symbol":[]},"alphafold":{"accession":"Q8TAC2","domains":[{"cath_id":"3.90.70.40","chopping":"22-180","consensus_level":"medium","plddt":92.309,"start":22,"end":180}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TAC2","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TAC2-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TAC2-F1-predicted_aligned_error_v6.png","plddt_mean":89.94},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=JOSD2","jax_strain_url":"https://www.jax.org/strain/search?query=JOSD2"},"sequence":{"accession":"Q8TAC2","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8TAC2.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8TAC2/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TAC2"}},"corpus_meta":[{"pmid":"35024322","id":"PMC_35024322","title":"Deubiquitinase JOSD2 stabilizes YAP/TAZ to promote cholangiocarcinoma progression.","date":"2021","source":"Acta pharmaceutica Sinica. B","url":"https://pubmed.ncbi.nlm.nih.gov/35024322","citation_count":38,"is_preprint":false},{"pmid":"33082514","id":"PMC_33082514","title":"The deubiquitinase JOSD2 is a positive regulator of glucose metabolism.","date":"2020","source":"Cell death and differentiation","url":"https://pubmed.ncbi.nlm.nih.gov/33082514","citation_count":35,"is_preprint":false},{"pmid":"39195964","id":"PMC_39195964","title":"Deubiquitinase JOSD2 improves calcium handling and attenuates cardiac hypertrophy and dysfunction by stabilizing SERCA2a in cardiomyocytes.","date":"2023","source":"Nature cardiovascular research","url":"https://pubmed.ncbi.nlm.nih.gov/39195964","citation_count":22,"is_preprint":false},{"pmid":"35836282","id":"PMC_35836282","title":"JOSD2 regulates PKM2 nuclear translocation and reduces acute myeloid leukemia progression.","date":"2022","source":"Experimental hematology & oncology","url":"https://pubmed.ncbi.nlm.nih.gov/35836282","citation_count":19,"is_preprint":false},{"pmid":"38177135","id":"PMC_38177135","title":"Josephin domain containing 2 (JOSD2) promotes lung cancer by inhibiting LKB1 (Liver kinase B1) activity.","date":"2024","source":"Signal transduction and targeted therapy","url":"https://pubmed.ncbi.nlm.nih.gov/38177135","citation_count":17,"is_preprint":false},{"pmid":"35568970","id":"PMC_35568970","title":"Deubiquitinating enzyme JOSD2 promotes hepatocellular carcinoma progression through interacting with and inhibiting CTNNB1 degradation.","date":"2022","source":"Cell biology international","url":"https://pubmed.ncbi.nlm.nih.gov/35568970","citation_count":12,"is_preprint":false},{"pmid":"38195959","id":"PMC_38195959","title":"JOSD2 mediates isoprenaline-induced heart failure by deubiquitinating CaMKIIδ in cardiomyocytes.","date":"2024","source":"Cellular and molecular life sciences : CMLS","url":"https://pubmed.ncbi.nlm.nih.gov/38195959","citation_count":10,"is_preprint":false},{"pmid":"40240366","id":"PMC_40240366","title":"Josephin Domain Containing 2 (JOSD2) inhibition as Pan-KRAS-mutation-targeting strategy for colorectal cancer.","date":"2025","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/40240366","citation_count":6,"is_preprint":false},{"pmid":"38463028","id":"PMC_38463028","title":"Role of deubiquitinase JOSD2 in the pathogenesis of esophageal squamous cell carcinoma.","date":"2024","source":"World journal of gastroenterology","url":"https://pubmed.ncbi.nlm.nih.gov/38463028","citation_count":4,"is_preprint":false},{"pmid":"40177575","id":"PMC_40177575","title":"Deubiquitinase JOSD2 alleviates colitis by inhibiting inflammation via deubiquitination of IMPDH2 in macrophages.","date":"2024","source":"Acta pharmaceutica Sinica. B","url":"https://pubmed.ncbi.nlm.nih.gov/40177575","citation_count":4,"is_preprint":false},{"pmid":"40217118","id":"PMC_40217118","title":"JOSD2 alleviates acute kidney injury through deubiquitinating SIRT7 and negativity regulating SIRT7-NF-κB inflammatory pathway in renal tubular epithelial cells.","date":"2025","source":"Acta pharmacologica Sinica","url":"https://pubmed.ncbi.nlm.nih.gov/40217118","citation_count":3,"is_preprint":false},{"pmid":"39833306","id":"PMC_39833306","title":"JOSD2 inhibits angiotensin II-induced vascular remodeling by deubiquitinating and stabilizing SMAD7.","date":"2025","source":"Acta pharmacologica Sinica","url":"https://pubmed.ncbi.nlm.nih.gov/39833306","citation_count":2,"is_preprint":false},{"pmid":"37899394","id":"PMC_37899394","title":"Deubiquitinating enzyme JOSD2 affects susceptibility of non-small cell lung carcinoma cells to anti-cancer drugs through DNA damage repair.","date":"2023","source":"Zhejiang da xue xue bao. Yi xue ban = Journal of Zhejiang University. Medical sciences","url":"https://pubmed.ncbi.nlm.nih.gov/37899394","citation_count":2,"is_preprint":false},{"pmid":"39793716","id":"PMC_39793716","title":"JOSD2 promotes breast cancer metastasis by deubiquitinating and stabilizing SMAD4.","date":"2025","source":"Biochemical pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/39793716","citation_count":1,"is_preprint":false},{"pmid":"41351298","id":"PMC_41351298","title":"Deubiquitinating enzyme JOSD2 modulates cGAS to facilitate immune evasion in colorectal cancer.","date":"2025","source":"Oncoimmunology","url":"https://pubmed.ncbi.nlm.nih.gov/41351298","citation_count":1,"is_preprint":false},{"pmid":"41092805","id":"PMC_41092805","title":"Rational DESIGN and Structure-activity relationship study of novel JOSD2 inhibitor against colorectal cancer.","date":"2025","source":"Bioorganic chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/41092805","citation_count":0,"is_preprint":false},{"pmid":"41412561","id":"PMC_41412561","title":"JOSD2 alleviates hypertensive renal disease through deubiquitinating AKT in renal tubular epithelial cells.","date":"2025","source":"Cellular signalling","url":"https://pubmed.ncbi.nlm.nih.gov/41412561","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9960,"output_tokens":3945,"usd":0.044527},"stage2":{"model":"claude-opus-4-6","input_tokens":7394,"output_tokens":3020,"usd":0.168705},"total_usd":0.213232,"stage1_batch_id":"msgbatch_01DzrsgVgYngY1hvM3DU1yF2","stage2_batch_id":"msgbatch_01KA9b7iRzKFdhoBUT7vCvSe","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2020,\n      \"finding\": \"JOSD2 directly deubiquitinates and stabilizes a glycolytic enzyme complex including Aldolase A, Phosphofructokinase-1, and Phosphoglycerate dehydrogenase, enhancing their activities and the glycolytic rate; a catalytically inactive JOSD2 mutant fails to do so, demonstrating the requirement for deubiquitinase activity.\",\n      \"method\": \"In vitro and in vivo deubiquitination assays, catalytically inactive mutant analysis, glycolytic rate measurement, Co-IP\",\n      \"journal\": \"Cell death and differentiation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple orthogonal methods including in vitro assay, mutagenesis, and functional metabolic readouts in a single study\",\n      \"pmids\": [\"33082514\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"JOSD2 deubiquitinates YAP and TAZ, cleaving their polyubiquitin chains in a deubiquitinase activity-dependent manner to prevent proteasomal degradation, thereby sustaining YAP/TAZ protein levels in cholangiocarcinoma cells.\",\n      \"method\": \"Deubiquitination assay, proteasome inhibitor rescue, JOSD2 knockdown with YAP/TAZ protein level measurement, in vitro and in vivo proliferation assays\",\n      \"journal\": \"Acta pharmaceutica Sinica. B\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — deubiquitinase activity-dependent mechanism established with catalytic mutant and proteasomal degradation rescue\",\n      \"pmids\": [\"35024322\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"JOSD2 interacts with PKM2 and inhibits its nuclear localization by reducing K433 acetylation of PKM2, without affecting PKM2 protein stability.\",\n      \"method\": \"Mass spectrometry, co-immunoprecipitation, co-immunofluorescence, nuclear/cytoplasmic fractionation, acetylation assays\",\n      \"journal\": \"Experimental hematology & oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP and MS identification with functional nuclear localization readout, single lab\",\n      \"pmids\": [\"35836282\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"JOSD2 binds to and deubiquitinates CTNNB1 (β-catenin), reducing its ubiquitination level and preventing its degradation, thereby augmenting Wnt signaling in hepatocellular carcinoma cells.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, rescue experiments with CTNNB1 manipulation\",\n      \"journal\": \"Cell biology international\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — Co-IP and ubiquitination assay with functional rescue, single lab\",\n      \"pmids\": [\"35568970\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"JOSD2 deubiquitinates and stabilizes SERCA2a (sarco/endoplasmic reticulum calcium ATPase 2a) in cardiomyocytes; JOSD2 deficiency impairs calcium handling and promotes cardiac hypertrophy, while cardiac-specific JOSD2 overexpression via AAV9 prevents angiotensin II-induced hypertrophy.\",\n      \"method\": \"Proteome-wide quantitative analysis, Co-IP, deubiquitination assay, Josd2 knockout mice, AAV9-mediated overexpression, calcium imaging\",\n      \"journal\": \"Nature cardiovascular research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vivo genetic KO and AAV-mediated OE with defined calcium handling phenotype, proteomics substrate identification, multiple orthogonal methods\",\n      \"pmids\": [\"39195964\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"JOSD2 restricts the kinase activity of LKB1 by removing K6-linked polyubiquitination from LKB1, an action vital for maintaining the integrity of the LKB1-STRAD-MO25 complex in NSCLC.\",\n      \"method\": \"Co-IP, ubiquitination linkage-specific assay (K6-linked), LKB1 kinase activity assay, JOSD2 knockdown and pharmacological inhibition in cell/PDX models\",\n      \"journal\": \"Signal transduction and targeted therapy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — specific ubiquitin linkage identified, kinase activity assay used as functional readout, validated in vitro and in vivo\",\n      \"pmids\": [\"38177135\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"JOSD2 interacts with CaMKIIδ and directly hydrolyzes K63-linked polyubiquitin chains on CaMKIIδ, increasing its phosphorylation and thereby causing calcium mishandling, hypertrophy, and fibrosis in cardiomyocytes; these effects are reversible by the CaMKIIδ inhibitor KN-93.\",\n      \"method\": \"Mass spectrometry, Co-IP, K63-specific deubiquitination assay, CaMKIIδ phosphorylation measurement, JOSD2 KO and OE in vivo, KN-93 rescue\",\n      \"journal\": \"Cellular and molecular life sciences : CMLS\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — specific ubiquitin linkage established, pharmacological rescue confirms pathway placement, multiple orthogonal methods\",\n      \"pmids\": [\"38195959\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"JOSD2 deubiquitinates IMPDH2 by preferentially cleaving K63-linked polyubiquitin chains at the K134 site of IMPDH2, suppressing IMPDH2 activity and preventing NF-κB activation and inflammation in macrophages.\",\n      \"method\": \"Co-IP, K63-linkage-specific ubiquitination assay, site-directed mutagenesis (K134), IMPDH2 activity assay, NF-κB reporter assay, myeloid-specific JOSD2 KO mice, bone marrow transplantation\",\n      \"journal\": \"Acta pharmaceutica Sinica. B\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — specific ubiquitin linkage and lysine site identified by mutagenesis, enzyme activity assay, in vivo myeloid-specific KO with functional phenotype\",\n      \"pmids\": [\"40177575\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"JOSD2 promotes DNA damage repair in NSCLC cells; DNA damaging agents increase nuclear localization of JOSD2, and JOSD2 depletion sensitizes NSCLC cells to DNA damaging agents.\",\n      \"method\": \"Immunofluorescence (nuclear localization), Western blotting (DDR pathway proteins), SRB cytotoxicity assay upon JOSD2 knockdown with DNA damaging drugs\",\n      \"journal\": \"Journal of Zhejiang University. Medical sciences\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — localization and sensitization shown but no direct substrate or molecular mechanism of DDR regulation identified\",\n      \"pmids\": [\"37899394\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"JOSD2 directly interacts with and stabilizes KRAS mutant proteins by reverting their proteolytic ubiquitination; reciprocally, KRAS mutants inhibit the catalytic activity of CHIP (an E3 ubiquitin ligase for JOSD2), forming a positive feedback circuit that accelerates KRAS-mutant CRC growth.\",\n      \"method\": \"DUB siRNA library screen, Co-IP, ubiquitination assay, CHIP E3 ligase activity assay, JOSD2 KD and pharmacological inhibition in PDC/PDX/PDO models\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — bidirectional regulatory circuit established with E3 ligase activity assay and validated in multiple patient-derived models\",\n      \"pmids\": [\"40240366\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"JOSD2 specifically binds to the MH1 domain of SMAD7 and removes K48-linked ubiquitin chains from SMAD7 at lysine 220, sustaining SMAD7 stability and thereby inhibiting TGFβ-SMAD signaling in vascular smooth muscle cells.\",\n      \"method\": \"LC-MS/MS, Co-IP, K48-linkage-specific ubiquitination assay, site-directed mutagenesis (K220), SMAD7 stability assay, RNA-seq, VSMC-specific JOSD2 OE in mice\",\n      \"journal\": \"Acta pharmacologica Sinica\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — specific ubiquitin linkage and lysine site identified by mutagenesis, in vivo validation with cell-type-specific OE\",\n      \"pmids\": [\"39833306\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"JOSD2 removes K63-linked ubiquitination from SIRT7 via its active site C24, promoting P62-mediated autophagic degradation of SIRT7, which prevents P65 phosphorylation and nuclear translocation, thereby reducing inflammatory responses in renal tubular epithelial cells during acute kidney injury.\",\n      \"method\": \"Mass spectrometry, Co-IP, K63-linkage-specific ubiquitination assay, active-site mutagenesis (C24), P62/autophagy pathway analysis, renal tubular-specific JOSD2 OE in mice, cisplatin and IRI AKI models\",\n      \"journal\": \"Acta pharmacologica Sinica\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — active site mutagenesis, specific ubiquitin linkage, autophagy mechanism, and in vivo validation with cell-type-specific OE\",\n      \"pmids\": [\"40217118\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"JOSD2 interacts with and stabilizes SMAD4 by removing polyubiquitin chains, thereby activating TGF-β signaling and promoting breast cancer metastasis.\",\n      \"method\": \"Co-IP, ubiquitination assay, JOSD2 RNAi, in vitro migration/invasion assays, in vivo metastasis model\",\n      \"journal\": \"Biochemical pharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — Co-IP and ubiquitination assay with in vivo validation, single lab, ubiquitin linkage type not specified\",\n      \"pmids\": [\"39793716\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"JOSD2 suppresses cGAS enzymatic activity by removing K27-linked ubiquitination from cGAS, thereby inhibiting cGAS-STING signaling and promoting M2 macrophage polarization and immune evasion in colorectal cancer.\",\n      \"method\": \"Co-IP, K27-linkage-specific ubiquitination assay, cGAS enzymatic activity assay, JOSD2 catalytic inhibitor (HY041004), macrophage polarization assay, in vivo CRC model\",\n      \"journal\": \"Oncoimmunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — specific ubiquitin linkage identified, enzyme activity assay for cGAS, pharmacological inhibition with in vivo validation\",\n      \"pmids\": [\"41351298\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"JOSD2 deubiquitinates the K63-linked ubiquitin chain of AKT via its active site H125 and enhances P62-mediated autophagic degradation of AKT in renal tubular epithelial cells, reducing AKT levels and thereby reducing renal EMT and fibrosis.\",\n      \"method\": \"Mass spectrometry, Co-IP, K63-linkage-specific ubiquitination assay, active-site mutagenesis (H125), autophagy assay, JOSD2 KO mice, single-cell RNA-seq, TEC-specific JOSD2 OE\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — active site mutagenesis, specific ubiquitin linkage, autophagy mechanism established, cell-type-specific in vivo validation\",\n      \"pmids\": [\"41412561\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"A small-molecule covalent inhibitor of JOSD2 (compound 31) was designed with a cyanamide warhead that selectively engages the catalytic cysteine residue of JOSD2, confirming the catalytic cysteine as the active site and demonstrating that JOSD2 inhibition induces downregulation of KRAS protein in CRC cells.\",\n      \"method\": \"Covalent binding assay, structure-activity relationship, KRAS protein level measurement after inhibitor treatment\",\n      \"journal\": \"Bioorganic chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 — covalent active-site engagement confirmed, but mechanistic depth limited to single functional readout\",\n      \"pmids\": [\"41092805\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"JOSD2 is a Josephin domain-containing deubiquitinase whose catalytic cysteine (C24) removes ubiquitin chains of specific linkages (K6, K27, K48, K63) from diverse substrate proteins including glycolytic enzymes (Aldolase A, PFK1, PHGDH), YAP/TAZ, SERCA2a, CaMKIIδ, LKB1, KRAS mutants, CTNNB1, SMAD4, SMAD7, IMPDH2, SIRT7, AKT, and cGAS, thereby either stabilizing substrates against proteasomal degradation or routing them to autophagic degradation (via P62), with consequences for glycolysis, calcium handling, Wnt/TGFβ/cGAS-STING signaling, and inflammation across multiple cancer and non-cancer contexts.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"JOSD2 is a Josephin-domain deubiquitinase that cleaves polyubiquitin chains of multiple linkage types (K6, K27, K48, K63) from a broad range of substrate proteins, thereby controlling their stability or activity in metabolic, signaling, and inflammatory pathways. Its catalytic cysteine (C24) and histidine (H125) residues are essential for hydrolysis of ubiquitin chains; removal of K48-linked chains stabilizes substrates such as Aldolase A, PFK1, YAP/TAZ, SERCA2a, SMAD7, KRAS mutants, and β-catenin against proteasomal degradation, whereas removal of K63-linked chains from SIRT7 and AKT routes them to P62-mediated autophagic degradation [PMID:33082514, PMID:35024322, PMID:39195964, PMID:39833306, PMID:40240366, PMID:40217118, PMID:41412561]. JOSD2 also modulates enzyme activity non-degradatively: it removes K6-linked ubiquitin from LKB1 to restrict its kinase function, K63-linked ubiquitin from CaMKIIδ to alter its phosphorylation, K63-linked ubiquitin from IMPDH2 to suppress its enzymatic activity and NF-κB signaling, and K27-linked ubiquitin from cGAS to inhibit cGAS-STING innate immune signaling [PMID:38177135, PMID:38195959, PMID:40177575, PMID:41351298]. Through these diverse substrates, JOSD2 exerts context-dependent roles in glycolysis, cardiac calcium handling and hypertrophy, Wnt and TGF-β signaling, inflammation, renal fibrosis, and tumor immune evasion.\",\n  \"teleology\": [\n    {\n      \"year\": 2020,\n      \"claim\": \"The initial enzymatic function of JOSD2 was established: it directly deubiquitinates glycolytic enzymes (Aldolase A, PFK1, PHGDH), stabilizing them and enhancing glycolysis—demonstrating that JOSD2 is an active deubiquitinase with metabolic substrates.\",\n      \"evidence\": \"In vitro deubiquitination assays, catalytically inactive mutant, glycolytic rate measurement, Co-IP in cancer cell lines\",\n      \"pmids\": [\"33082514\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Ubiquitin linkage specificity on glycolytic substrates not determined\", \"No structural basis for substrate recognition\", \"Whether metabolic effects are relevant in non-cancer cells unknown\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"JOSD2's substrate repertoire was extended to signaling effectors: it deubiquitinates YAP and TAZ to prevent their proteasomal degradation, establishing JOSD2 as a stabilizer of Hippo pathway transcriptional co-activators.\",\n      \"evidence\": \"Deubiquitination assay with catalytic mutant, proteasome inhibitor rescue, cholangiocarcinoma cell proliferation assays\",\n      \"pmids\": [\"35024322\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Ubiquitin linkage type on YAP/TAZ not specified\", \"E3 ligase counterpart not identified\", \"In vivo validation lacking\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Beyond deubiquitination-mediated stabilization, JOSD2 was found to regulate PKM2 nuclear localization by reducing its acetylation, and to stabilize β-catenin by deubiquitination—expanding its mechanisms to include non-degradative regulation and Wnt signaling.\",\n      \"evidence\": \"Mass spectrometry, Co-IP, nuclear/cytoplasmic fractionation, acetylation assays for PKM2; Co-IP and ubiquitination assays for CTNNB1 in HCC cells\",\n      \"pmids\": [\"35836282\", \"35568970\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which JOSD2 affects PKM2 acetylation is indirect and unexplained\", \"Ubiquitin linkage type on β-catenin not specified\", \"Both findings from single laboratories\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"JOSD2 was shown to stabilize SERCA2a in cardiomyocytes and its deficiency causes impaired calcium handling and cardiac hypertrophy, establishing a non-cancer physiological role for JOSD2 in the heart with in vivo genetic evidence.\",\n      \"evidence\": \"Proteome-wide analysis, Co-IP, deubiquitination assay, Josd2 KO mice, AAV9-mediated cardiac overexpression, calcium imaging\",\n      \"pmids\": [\"39195964\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Ubiquitin linkage type on SERCA2a not specified\", \"Whether JOSD2 cardiac effects are solely SERCA2a-dependent or involve additional substrates not resolved\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Ubiquitin linkage specificity of JOSD2 was resolved for multiple substrates: K6-linked chains on LKB1 (restricting its kinase activity), K63-linked chains on CaMKIIδ (altering phosphorylation and calcium handling), and K63-linked chains on IMPDH2 (suppressing enzymatic activity and NF-κB), revealing that JOSD2 cleaves distinct chain types to modulate enzyme activity rather than solely protein stability.\",\n      \"evidence\": \"Linkage-specific ubiquitination assays, kinase/enzyme activity assays, active-site and site-directed mutagenesis, in vivo KO mice (myeloid-specific for IMPDH2), pharmacological rescue (KN-93 for CaMKIIδ)\",\n      \"pmids\": [\"38177135\", \"38195959\", \"40177575\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How JOSD2 achieves selectivity for different linkage types on different substrates is structurally unexplained\", \"Whether K63-chain removal from CaMKIIδ promotes autophagy or only alters signaling not tested\", \"No crystal structure of JOSD2-substrate complex available\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"A dual-outcome model was established: JOSD2 removal of K63-linked ubiquitin from SIRT7 and AKT promotes their P62-mediated autophagic degradation, while removal of K48-linked ubiquitin from SMAD7 and KRAS mutants blocks proteasomal degradation—demonstrating that chain-type specificity dictates whether JOSD2 stabilizes or destabilizes a substrate.\",\n      \"evidence\": \"Active-site mutagenesis (C24, H125), K63- and K48-linkage-specific assays, P62/autophagy pathway analysis, renal tubular- and VSMC-specific OE in mice, PDC/PDX/PDO for KRAS, site-directed mutagenesis (K220 on SMAD7)\",\n      \"pmids\": [\"40217118\", \"41412561\", \"39833306\", \"40240366\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Determinants of whether K63-deubiquitination leads to autophagic degradation versus non-degradative signaling change are unknown\", \"Whether JOSD2 acts processively or distributively on chains not tested\", \"Relative contribution of each substrate to in vivo phenotypes not deconvoluted\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"JOSD2 was shown to remove K27-linked ubiquitin from cGAS, suppressing cGAS-STING innate immune signaling and enabling tumor immune evasion, extending the linkage repertoire to K27 and connecting JOSD2 to innate immunity.\",\n      \"evidence\": \"K27-linkage-specific ubiquitination assay, cGAS enzymatic activity assay, JOSD2 catalytic inhibitor (HY041004), macrophage polarization assay, in vivo CRC model\",\n      \"pmids\": [\"41351298\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether JOSD2 regulation of cGAS is relevant outside of tumor microenvironment not examined\", \"Structural basis for K27-linkage recognition unknown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"A covalent small-molecule inhibitor targeting the JOSD2 catalytic cysteine was developed, pharmacologically validating the active site and demonstrating that JOSD2 inhibition can downregulate KRAS protein in cancer cells.\",\n      \"evidence\": \"Cyanamide-warhead covalent binding assay, structure-activity relationship, KRAS protein measurement in CRC cells\",\n      \"pmids\": [\"41092805\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Selectivity over other Josephin-domain DUBs not comprehensively profiled\", \"In vivo pharmacokinetics and efficacy not reported\", \"Whether inhibitor blocks all JOSD2 substrate deubiquitination equally not tested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include how JOSD2 achieves specificity for different ubiquitin linkage types (K6, K27, K48, K63) and different substrates, what structural features govern whether deubiquitination leads to substrate stabilization versus autophagic degradation, and whether a unifying physiological role integrates JOSD2's diverse substrate repertoire.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No crystal or cryo-EM structure of JOSD2 alone or in complex with any substrate\", \"No systematic substrate profiling (e.g., ubiquitin-SILAC) performed\", \"Relative physiological importance of individual substrates in vivo not ranked\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [0, 1, 3, 4, 5, 6, 7, 9, 10, 11, 13, 14]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 1, 3, 4, 5, 6, 7, 9, 10, 11, 13, 14]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [0, 2]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [8]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [0, 1, 3, 4, 5, 6, 7, 9, 10, 11, 13, 14]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [0, 7]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 3, 5, 10, 12, 13]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [7, 13]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [11, 14]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"ALDOA\",\n      \"PFKL\",\n      \"SERCA2a\",\n      \"LKB1\",\n      \"KRAS\",\n      \"SMAD7\",\n      \"IMPDH2\",\n      \"CGAS\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}