{"gene":"ABTB1","run_date":"2026-06-09T22:02:37","timeline":{"discoveries":[{"year":2001,"finding":"BPOZ (ABTB1) overexpression suppresses cancer cell growth and inhibits cell cycle progression at the G1/S transition, while antisense oligonucleotides against BPOZ accelerate cell growth, placing BPOZ downstream of PTEN as a mediator of its growth-suppressive signaling pathway.","method":"Colony-formation assays, stable overexpression, flow cytometry, antisense oligonucleotide knockdown","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal functional assays (stable OE, KD, flow cytometry) in single lab establishing cell-cycle role and pathway placement","pmids":["11494141"],"is_preprint":false},{"year":2008,"finding":"BPOZ-2 (ABTB1) directly binds eEF1A1 via its ankyrin repeats and both BTB/POZ domains (interacting with Domains I and III of eEF1A1), acts as a CUL3 E3 ubiquitin ligase adaptor to promote eEF1A1 ubiquitylation and proteasomal degradation, inhibits GTP binding to eEF1A1, and prevents translation in vitro.","method":"Yeast two-hybrid screen, GST pull-down, co-immunoprecipitation, in vitro ubiquitylation assay, in vitro translation assay (rabbit reticulocyte), co-localization imaging","journal":"Genes to cells : devoted to molecular & cellular mechanisms","confidence":"High","confidence_rationale":"Tier 1 / Strong — multiple orthogonal methods including in vitro reconstitution (translation assay, ubiquitylation assay), domain-mapping, pull-down and co-IP, all in one study","pmids":["18459963"],"is_preprint":false},{"year":2009,"finding":"TdIF1 binds directly to BPOZ-2 (ABTB1) and recruits it from the cytoplasm into the nucleus, where BPOZ-2 promotes TdT ubiquitylation; BPOZ-2 alone localizes mainly to the cytoplasm but co-localizes with TdIF1 in the nucleus upon co-expression.","method":"Yeast two-hybrid, GST pull-down, co-immunoprecipitation, fluorescence co-localization (EGFP/DsRed), ubiquitylation assay in 293T cells","journal":"Genes to cells : devoted to molecular & cellular mechanisms","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — reciprocal Co-IP + pull-down + localization shift + functional ubiquitylation assay, multiple orthogonal methods in one study","pmids":["19930467"],"is_preprint":false},{"year":2016,"finding":"BPOZ-2 (ABTB1) physically associates with PINK1, and lentiviral overexpression of BPOZ-2 in A53T transgenic mice stimulates PINK1-dependent autophagic clearance of alpha-synuclein, reducing its burden in dopaminergic neurons; lentiviral shRNA knockdown of BPOZ-2 increases monomeric and polymeric alpha-synuclein accumulation.","method":"Lentiviral gene delivery and shRNA knockdown in A53T transgenic mice, protein-protein interaction (co-immunoprecipitation), immunohistochemistry","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo loss- and gain-of-function with protein interaction data, single lab","pmids":["26916519"],"is_preprint":false},{"year":2023,"finding":"BPOZ-2 (ABTB1) interacts with NLRP3 and mediates its degradation by recruiting CUL3 E3 ubiquitin ligase; BPOZ-2 knockout mice show increased IL-1β and greater susceptibility to LPS-induced septic shock and ALI; SARS-CoV-2 nucleocapsid (N) protein reduces BPOZ-2 expression to promote NLRP3 inflammasome activation.","method":"BPOZ-2 knockout mouse model, co-immunoprecipitation, ELISA, immunoblot, BMDM functional assays, BPOZ-2 reintroduction rescue experiment","journal":"Frontiers in cellular and infection microbiology","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, KO mouse model, rescue experiment, multiple orthogonal functional readouts in single study","pmids":["36936774"],"is_preprint":false},{"year":2023,"finding":"ABTB1 interacts with TRIM4 (via immunoprecipitation and mass spectrometry) and promotes TRIM4 degradation through the proteasome system, thereby blocking TRIM4-mediated ubiquitylation and degradation of influenza A virus NP protein and facilitating nuclear import of the vRNP complex; ABTB1 does not interact directly with NP.","method":"Co-immunoprecipitation, mass spectrometry, proteasome inhibitor treatment, IAV replication assays, nuclear import assays","journal":"Emerging microbes & infections","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP/MS interaction data plus functional virology assays, single lab","pmids":["37823597"],"is_preprint":false},{"year":2026,"finding":"ABTB1 interacts with CDK1 via its 1–214 amino acid region and promotes CDK1 destabilization through K27-linked ubiquitination, acting as a tumor suppressor; TRIM4 counteracts this by promoting ABTB1 degradation via K6, K27, K29, and K33-linked ubiquitination targeting the 53–500 aa region of TRIM4, defining a TRIM4–ABTB1–CDK1 axis that controls G2/M phase transition in glioblastoma.","method":"Co-immunoprecipitation, ubiquitination assay, protein turnover assay, molecular cloning/domain mapping, flow cytometry, xenograft tumor model","journal":"International journal of biological macromolecules","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal biochemical methods (Co-IP, ubiquitination assay, domain mapping) plus in vivo xenograft, single lab","pmids":["42034143"],"is_preprint":false},{"year":2026,"finding":"TTLL12 competes with BPOZ-2 (ABTB1) for binding to eEF1A1, thereby suppressing BPOZ-2/CUL3-mediated ubiquitin-proteasome degradation of eEF1A1 and promoting hepatocellular carcinoma cell proliferation.","method":"Co-immunoprecipitation, ubiquitination assay, knockdown/overexpression functional assays, in vivo tumor model","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — competitive binding and ubiquitination assays with functional readout, single lab","pmids":["42014684"],"is_preprint":false},{"year":2024,"finding":"BPOZ-2 (ABTB1) deficiency in mice increases IL-1β induction and aggravates DSS-induced colitis and DEN-induced acute liver injury, consistent with its role as a negative regulator of inflammatory responses through CUL3-mediated protein degradation.","method":"BPOZ-2 knockout mouse model, DSS and DEN chemical injury models, ELISA for IL-1β, histopathology","journal":"Toxicology letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO with defined inflammatory phenotype in two independent in vivo models, single lab","pmids":["38866194"],"is_preprint":false}],"current_model":"ABTB1 (BPOZ-2) is a CUL3 E3 ubiquitin ligase adaptor protein that uses its ankyrin repeats and BTB/POZ domains to recruit substrates—including eEF1A1, NLRP3, CDK1, and TdT—for ubiquitin-proteasome-mediated degradation, thereby suppressing translation, inhibiting cell cycle progression at G1/S and G2/M, negatively regulating NLRP3 inflammasome activation, and promoting autophagic clearance of alpha-synuclein via PINK1; its subcellular localization is predominantly cytoplasmic but can be shifted to the nucleus by binding partners such as TdIF1, and its activity is counteracted by TRIM4 (which ubiquitinates and degrades ABTB1) and TTLL12 (which competes with ABTB1 for eEF1A1 binding)."},"narrative":{"mechanistic_narrative":"ABTB1 (BPOZ-2) is a substrate-recognition adaptor for CUL3-based E3 ubiquitin ligase complexes that directs target proteins for ubiquitin-proteasome degradation, coupling this activity to control of translation, cell-cycle progression, and inflammatory signaling [PMID:18459963, PMID:36936774]. Acting downstream of PTEN, ABTB1 restrains cell growth and arrests the cell cycle at the G1/S transition [PMID:11494141]; through its ankyrin repeats and tandem BTB/POZ domains it directly binds the translation elongation factor eEF1A1, blocks its GTP loading, and promotes its CUL3-dependent ubiquitylation and degradation, thereby suppressing translation [PMID:18459963]. The same adaptor function targets CDK1 for K27-linked ubiquitination to gate the G2/M transition as a tumor suppressor in glioblastoma [PMID:42034143], and degrades NLRP3 to limit IL-1β production and inflammasome-driven pathology in vivo [PMID:36936774, PMID:38866194]. ABTB1 is predominantly cytoplasmic but is recruited to the nucleus by TdIF1, where it promotes ubiquitylation of TdT [PMID:19930467]. Its activity is set by opposing regulators: TRIM4 ubiquitinates and degrades ABTB1 (while ABTB1 reciprocally promotes TRIM4 degradation) [PMID:37823597, PMID:42034143], and TTLL12 competes for eEF1A1 binding to spare the substrate from degradation [PMID:42014684]. ABTB1 also associates with PINK1 to drive autophagic clearance of alpha-synuclein in dopaminergic neurons [PMID:26916519].","teleology":[{"year":2001,"claim":"Established ABTB1 as a growth-suppressive effector by placing it in the cell-cycle control circuitry downstream of PTEN, answering whether the gene actively restrains proliferation.","evidence":"Colony-formation assays, stable overexpression, antisense knockdown and flow cytometry in cancer cells","pmids":["11494141"],"confidence":"Medium","gaps":["No molecular mechanism for the G1/S arrest identified at this stage","Direct biochemical link to PTEN signaling not resolved"]},{"year":2008,"claim":"Defined the core biochemical identity of ABTB1 as a CUL3 E3 ligase adaptor and identified eEF1A1 as a direct substrate, explaining a molecular route to translational suppression.","evidence":"Yeast two-hybrid, GST pull-down, co-IP, domain mapping, in vitro ubiquitylation and in vitro translation assays","pmids":["18459963"],"confidence":"High","gaps":["Whether eEF1A1 degradation accounts for the cell-cycle phenotype not tested","Physiological contexts of translation suppression not defined"]},{"year":2009,"claim":"Showed that ABTB1 localization and substrate choice are controlled by binding partners, with TdIF1 driving nuclear recruitment and TdT ubiquitylation.","evidence":"Yeast two-hybrid, pull-down, reciprocal co-IP, fluorescence co-localization and ubiquitylation assay in 293T cells","pmids":["19930467"],"confidence":"High","gaps":["Functional consequence of nuclear TdT ubiquitylation in vivo unknown","Signals governing cytoplasmic-versus-nuclear partitioning not defined"]},{"year":2016,"claim":"Extended ABTB1 function to neuronal proteostasis by linking it to PINK1-dependent autophagic clearance of alpha-synuclein.","evidence":"Lentiviral overexpression and shRNA knockdown in A53T transgenic mice, co-IP, immunohistochemistry","pmids":["26916519"],"confidence":"Medium","gaps":["Whether ABTB1 acts as a CUL3 adaptor in this autophagy context unclear","Direct substrate in the PINK1 pathway not identified"]},{"year":2023,"claim":"Identified NLRP3 as a degradation substrate, establishing ABTB1 as a negative regulator of inflammasome activation with disease relevance in sepsis and viral infection.","evidence":"Knockout mouse model, reciprocal co-IP, ELISA, immunoblot, BMDM assays and rescue experiment; SARS-CoV-2 N protein modulation","pmids":["36936774"],"confidence":"High","gaps":["Ubiquitin linkage type on NLRP3 not characterized","Mechanism by which SARS-CoV-2 N protein lowers ABTB1 expression not resolved"]},{"year":2023,"claim":"Revealed a regulatory interplay with TRIM4, showing ABTB1 promotes TRIM4 degradation and thereby influences influenza A virus replication.","evidence":"Co-IP, mass spectrometry, proteasome inhibition, IAV replication and nuclear import assays","pmids":["37823597"],"confidence":"Medium","gaps":["Whether ABTB1 uses CUL3 to degrade TRIM4 not established","ABTB1 does not bind NP directly, leaving the chain of causation indirect"]},{"year":2024,"claim":"Confirmed ABTB1 as a broad anti-inflammatory factor in vivo by showing its deficiency aggravates colitis and acute liver injury via elevated IL-1β.","evidence":"Knockout mouse model with DSS and DEN injury models, IL-1β ELISA, histopathology","pmids":["38866194"],"confidence":"Medium","gaps":["Tissue-specific substrates driving each phenotype not dissected","Relative contribution of NLRP3 versus other targets not quantified"]},{"year":2026,"claim":"Defined a TRIM4–ABTB1–CDK1 axis controlling G2/M, with ABTB1 degrading CDK1 via K27-linked chains and TRIM4 counteracting by degrading ABTB1, providing a mechanistic basis for tumor suppression in glioblastoma.","evidence":"Co-IP, ubiquitination assays, protein turnover, domain mapping, flow cytometry and xenograft model","pmids":["42034143"],"confidence":"Medium","gaps":["Whether CDK1 degradation explains the earlier G1/S phenotype not reconciled","Generality of the axis beyond glioblastoma untested"]},{"year":2026,"claim":"Showed that substrate availability is tuned competitively, as TTLL12 displaces ABTB1 from eEF1A1 to block its degradation and drive hepatocellular carcinoma proliferation.","evidence":"Co-IP, ubiquitination assay, knockdown/overexpression functional assays and in vivo tumor model","pmids":["42014684"],"confidence":"Medium","gaps":["Structural basis of the competitive binding not resolved","Whether other substrates are similarly protected by competing partners unknown"]},{"year":null,"claim":"How ABTB1 substrate selection, ubiquitin-linkage specificity, and cytoplasmic/nuclear partitioning are coordinated across its diverse roles in translation, cell cycle, inflammation, and autophagy remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of the ABTB1–CUL3 substrate complex","Determinants of which substrate is engaged in a given cell type not defined","Unifying logic linking the multiple substrate-specific axes not established"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[1,4,6]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[1,2,4]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,4,7]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[1,2]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[2]}],"pathway":[{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[1,4,6]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[0,6]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[4,8]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[3]}],"complexes":["CUL3 E3 ubiquitin ligase complex"],"partners":["CUL3","EEF1A1","TDIF1","PINK1","NLRP3","TRIM4","CDK1","TTLL12"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q969K4","full_name":"Ankyrin repeat and BTB/POZ domain-containing protein 1","aliases":["Elongation factor 1A-binding protein"],"length_aa":478,"mass_kda":54.0,"function":"May act as a mediator of the PTEN growth-suppressive signaling pathway. May play a role in developmental processes","subcellular_location":"Cytoplasm","url":"https://www.uniprot.org/uniprotkb/Q969K4/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ABTB1","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/ABTB1","total_profiled":1310},"omim":[{"mim_id":"608308","title":"ANKYRIN REPEAT- AND BTB DOMAIN-CONTAINING PROTEIN 1; ABTB1","url":"https://www.omim.org/entry/608308"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Cytosol","reliability":"Supported"},{"location":"Nucleoli","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/ABTB1"},"hgnc":{"alias_symbol":["BPOZ","EF1ABP","Btb3","BTBD21","BPOZ-2"],"prev_symbol":[]},"alphafold":{"accession":"Q969K4","domains":[{"cath_id":"1.25.40.20","chopping":"2-97","consensus_level":"high","plddt":81.9554,"start":2,"end":97},{"cath_id":"3.30.710.10","chopping":"101-229","consensus_level":"high","plddt":91.3942,"start":101,"end":229},{"cath_id":"3.30.710.10","chopping":"237-373","consensus_level":"high","plddt":85.2091,"start":237,"end":373},{"cath_id":"-","chopping":"379-475","consensus_level":"high","plddt":90.1705,"start":379,"end":475}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q969K4","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q969K4-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q969K4-F1-predicted_aligned_error_v6.png","plddt_mean":86.5},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ABTB1","jax_strain_url":"https://www.jax.org/strain/search?query=ABTB1"},"sequence":{"accession":"Q969K4","fasta_url":"https://rest.uniprot.org/uniprotkb/Q969K4.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q969K4/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q969K4"}},"corpus_meta":[{"pmid":"11494141","id":"PMC_11494141","title":"Growth-suppressive effects of BPOZ and EGR2, two genes involved in the PTEN signaling pathway.","date":"2001","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/11494141","citation_count":313,"is_preprint":false},{"pmid":"31065369","id":"PMC_31065369","title":"MiR-4319 suppresses colorectal cancer progression by targeting ABTB1.","date":"2019","source":"United European gastroenterology journal","url":"https://pubmed.ncbi.nlm.nih.gov/31065369","citation_count":48,"is_preprint":false},{"pmid":"18459963","id":"PMC_18459963","title":"BPOZ-2 directly binds to eEF1A1 to promote eEF1A1 ubiquitylation and degradation and prevent translation.","date":"2008","source":"Genes to cells : devoted to molecular & cellular mechanisms","url":"https://pubmed.ncbi.nlm.nih.gov/18459963","citation_count":18,"is_preprint":false},{"pmid":"37823597","id":"PMC_37823597","title":"ABTB1 facilitates the replication of influenza A virus by counteracting TRIM4-mediated degradation of viral NP protein.","date":"2023","source":"Emerging microbes & infections","url":"https://pubmed.ncbi.nlm.nih.gov/37823597","citation_count":12,"is_preprint":false},{"pmid":"26916519","id":"PMC_26916519","title":"BPOZ-2 Gene Delivery Ameliorates Alpha-Synucleinopathy in A53T Transgenic Mouse Model of Parkinson's Disease.","date":"2016","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/26916519","citation_count":8,"is_preprint":false},{"pmid":"36936774","id":"PMC_36936774","title":"BPOZ-2 is a negative regulator of the NLPR3 inflammasome contributing to SARS-CoV-2-induced hyperinflammation.","date":"2023","source":"Frontiers in cellular and infection microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/36936774","citation_count":7,"is_preprint":false},{"pmid":"35111848","id":"PMC_35111848","title":"Mechanism of Gegen Qinlian Decoction Regulating ABTB1 Expression in Colorectal Cancer Metastasis Based on PI3K/AKT/FOXO1 Pathway.","date":"2022","source":"BioMed research international","url":"https://pubmed.ncbi.nlm.nih.gov/35111848","citation_count":7,"is_preprint":false},{"pmid":"19930467","id":"PMC_19930467","title":"TdT interacting factor 1 enhances TdT ubiquitylation through recruitment of BPOZ-2 into nucleus from cytoplasm.","date":"2009","source":"Genes to cells : devoted to molecular & cellular mechanisms","url":"https://pubmed.ncbi.nlm.nih.gov/19930467","citation_count":5,"is_preprint":false},{"pmid":"30129726","id":"PMC_30129726","title":"[In Vitro Effects of Aminoalcohol-carbazole Compound BTB3 against Echinococcus granulosus].","date":"2016","source":"Zhongguo ji sheng chong xue yu ji sheng chong bing za zhi = Chinese journal of parasitology & parasitic diseases","url":"https://pubmed.ncbi.nlm.nih.gov/30129726","citation_count":1,"is_preprint":false},{"pmid":"38866194","id":"PMC_38866194","title":"BPOZ-2-deficient mice exhibit aggravated inflammation-associated tissue damage after acute dextran sodium sulfate or diethylnitrosamine exposure.","date":"2024","source":"Toxicology letters","url":"https://pubmed.ncbi.nlm.nih.gov/38866194","citation_count":0,"is_preprint":false},{"pmid":"42014684","id":"PMC_42014684","title":"TTLL12 counteracts BPOZ-2 to stabilize eEF1A1 and promote hepatocarcinogenesis.","date":"2026","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/42014684","citation_count":0,"is_preprint":false},{"pmid":"38550062","id":"PMC_38550062","title":"Retracted: Mechanism of Gegen Qinlian Decoction Regulating ABTB1 Expression in Colorectal Cancer Metastasis Based on PI3K/AKT/FOXO1 Pathway.","date":"2024","source":"BioMed research international","url":"https://pubmed.ncbi.nlm.nih.gov/38550062","citation_count":0,"is_preprint":false},{"pmid":"42034143","id":"PMC_42034143","title":"The E3 ubiquitin ligase TRIM4 promotes the proliferation of glioblastoma by inhibiting ABTB1-mediated CDK1 ubiquitination.","date":"2026","source":"International journal of biological macromolecules","url":"https://pubmed.ncbi.nlm.nih.gov/42034143","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":8523,"output_tokens":2506,"usd":0.03158,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9613,"output_tokens":3347,"usd":0.06587,"stage2_stop_reason":"end_turn"},"total_usd":0.09745,"stage1_batch_id":"msgbatch_0179Z2pxRYBsXi2xADneafRw","stage2_batch_id":"msgbatch_01LaY9ZaVdgjWArcZo9eqQE5","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2001,\n      \"finding\": \"BPOZ (ABTB1) overexpression suppresses cancer cell growth and inhibits cell cycle progression at the G1/S transition, while antisense oligonucleotides against BPOZ accelerate cell growth, placing BPOZ downstream of PTEN as a mediator of its growth-suppressive signaling pathway.\",\n      \"method\": \"Colony-formation assays, stable overexpression, flow cytometry, antisense oligonucleotide knockdown\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal functional assays (stable OE, KD, flow cytometry) in single lab establishing cell-cycle role and pathway placement\",\n      \"pmids\": [\"11494141\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"BPOZ-2 (ABTB1) directly binds eEF1A1 via its ankyrin repeats and both BTB/POZ domains (interacting with Domains I and III of eEF1A1), acts as a CUL3 E3 ubiquitin ligase adaptor to promote eEF1A1 ubiquitylation and proteasomal degradation, inhibits GTP binding to eEF1A1, and prevents translation in vitro.\",\n      \"method\": \"Yeast two-hybrid screen, GST pull-down, co-immunoprecipitation, in vitro ubiquitylation assay, in vitro translation assay (rabbit reticulocyte), co-localization imaging\",\n      \"journal\": \"Genes to cells : devoted to molecular & cellular mechanisms\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — multiple orthogonal methods including in vitro reconstitution (translation assay, ubiquitylation assay), domain-mapping, pull-down and co-IP, all in one study\",\n      \"pmids\": [\"18459963\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"TdIF1 binds directly to BPOZ-2 (ABTB1) and recruits it from the cytoplasm into the nucleus, where BPOZ-2 promotes TdT ubiquitylation; BPOZ-2 alone localizes mainly to the cytoplasm but co-localizes with TdIF1 in the nucleus upon co-expression.\",\n      \"method\": \"Yeast two-hybrid, GST pull-down, co-immunoprecipitation, fluorescence co-localization (EGFP/DsRed), ubiquitylation assay in 293T cells\",\n      \"journal\": \"Genes to cells : devoted to molecular & cellular mechanisms\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — reciprocal Co-IP + pull-down + localization shift + functional ubiquitylation assay, multiple orthogonal methods in one study\",\n      \"pmids\": [\"19930467\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"BPOZ-2 (ABTB1) physically associates with PINK1, and lentiviral overexpression of BPOZ-2 in A53T transgenic mice stimulates PINK1-dependent autophagic clearance of alpha-synuclein, reducing its burden in dopaminergic neurons; lentiviral shRNA knockdown of BPOZ-2 increases monomeric and polymeric alpha-synuclein accumulation.\",\n      \"method\": \"Lentiviral gene delivery and shRNA knockdown in A53T transgenic mice, protein-protein interaction (co-immunoprecipitation), immunohistochemistry\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo loss- and gain-of-function with protein interaction data, single lab\",\n      \"pmids\": [\"26916519\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"BPOZ-2 (ABTB1) interacts with NLRP3 and mediates its degradation by recruiting CUL3 E3 ubiquitin ligase; BPOZ-2 knockout mice show increased IL-1β and greater susceptibility to LPS-induced septic shock and ALI; SARS-CoV-2 nucleocapsid (N) protein reduces BPOZ-2 expression to promote NLRP3 inflammasome activation.\",\n      \"method\": \"BPOZ-2 knockout mouse model, co-immunoprecipitation, ELISA, immunoblot, BMDM functional assays, BPOZ-2 reintroduction rescue experiment\",\n      \"journal\": \"Frontiers in cellular and infection microbiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, KO mouse model, rescue experiment, multiple orthogonal functional readouts in single study\",\n      \"pmids\": [\"36936774\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"ABTB1 interacts with TRIM4 (via immunoprecipitation and mass spectrometry) and promotes TRIM4 degradation through the proteasome system, thereby blocking TRIM4-mediated ubiquitylation and degradation of influenza A virus NP protein and facilitating nuclear import of the vRNP complex; ABTB1 does not interact directly with NP.\",\n      \"method\": \"Co-immunoprecipitation, mass spectrometry, proteasome inhibitor treatment, IAV replication assays, nuclear import assays\",\n      \"journal\": \"Emerging microbes & infections\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP/MS interaction data plus functional virology assays, single lab\",\n      \"pmids\": [\"37823597\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"ABTB1 interacts with CDK1 via its 1–214 amino acid region and promotes CDK1 destabilization through K27-linked ubiquitination, acting as a tumor suppressor; TRIM4 counteracts this by promoting ABTB1 degradation via K6, K27, K29, and K33-linked ubiquitination targeting the 53–500 aa region of TRIM4, defining a TRIM4–ABTB1–CDK1 axis that controls G2/M phase transition in glioblastoma.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, protein turnover assay, molecular cloning/domain mapping, flow cytometry, xenograft tumor model\",\n      \"journal\": \"International journal of biological macromolecules\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal biochemical methods (Co-IP, ubiquitination assay, domain mapping) plus in vivo xenograft, single lab\",\n      \"pmids\": [\"42034143\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"TTLL12 competes with BPOZ-2 (ABTB1) for binding to eEF1A1, thereby suppressing BPOZ-2/CUL3-mediated ubiquitin-proteasome degradation of eEF1A1 and promoting hepatocellular carcinoma cell proliferation.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, knockdown/overexpression functional assays, in vivo tumor model\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — competitive binding and ubiquitination assays with functional readout, single lab\",\n      \"pmids\": [\"42014684\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"BPOZ-2 (ABTB1) deficiency in mice increases IL-1β induction and aggravates DSS-induced colitis and DEN-induced acute liver injury, consistent with its role as a negative regulator of inflammatory responses through CUL3-mediated protein degradation.\",\n      \"method\": \"BPOZ-2 knockout mouse model, DSS and DEN chemical injury models, ELISA for IL-1β, histopathology\",\n      \"journal\": \"Toxicology letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with defined inflammatory phenotype in two independent in vivo models, single lab\",\n      \"pmids\": [\"38866194\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ABTB1 (BPOZ-2) is a CUL3 E3 ubiquitin ligase adaptor protein that uses its ankyrin repeats and BTB/POZ domains to recruit substrates—including eEF1A1, NLRP3, CDK1, and TdT—for ubiquitin-proteasome-mediated degradation, thereby suppressing translation, inhibiting cell cycle progression at G1/S and G2/M, negatively regulating NLRP3 inflammasome activation, and promoting autophagic clearance of alpha-synuclein via PINK1; its subcellular localization is predominantly cytoplasmic but can be shifted to the nucleus by binding partners such as TdIF1, and its activity is counteracted by TRIM4 (which ubiquitinates and degrades ABTB1) and TTLL12 (which competes with ABTB1 for eEF1A1 binding).\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ABTB1 (BPOZ-2) is a substrate-recognition adaptor for CUL3-based E3 ubiquitin ligase complexes that directs target proteins for ubiquitin-proteasome degradation, coupling this activity to control of translation, cell-cycle progression, and inflammatory signaling [#1, #4]. Acting downstream of PTEN, ABTB1 restrains cell growth and arrests the cell cycle at the G1/S transition [#0]; through its ankyrin repeats and tandem BTB/POZ domains it directly binds the translation elongation factor eEF1A1, blocks its GTP loading, and promotes its CUL3-dependent ubiquitylation and degradation, thereby suppressing translation [#1]. The same adaptor function targets CDK1 for K27-linked ubiquitination to gate the G2/M transition as a tumor suppressor in glioblastoma [#6], and degrades NLRP3 to limit IL-1\\u03b2 production and inflammasome-driven pathology in vivo [#4, #8]. ABTB1 is predominantly cytoplasmic but is recruited to the nucleus by TdIF1, where it promotes ubiquitylation of TdT [#2]. Its activity is set by opposing regulators: TRIM4 ubiquitinates and degrades ABTB1 (while ABTB1 reciprocally promotes TRIM4 degradation) [#5, #6], and TTLL12 competes for eEF1A1 binding to spare the substrate from degradation [#7]. ABTB1 also associates with PINK1 to drive autophagic clearance of alpha-synuclein in dopaminergic neurons [#3].\",\n  \"teleology\": [\n    {\n      \"year\": 2001,\n      \"claim\": \"Established ABTB1 as a growth-suppressive effector by placing it in the cell-cycle control circuitry downstream of PTEN, answering whether the gene actively restrains proliferation.\",\n      \"evidence\": \"Colony-formation assays, stable overexpression, antisense knockdown and flow cytometry in cancer cells\",\n      \"pmids\": [\"11494141\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No molecular mechanism for the G1/S arrest identified at this stage\", \"Direct biochemical link to PTEN signaling not resolved\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Defined the core biochemical identity of ABTB1 as a CUL3 E3 ligase adaptor and identified eEF1A1 as a direct substrate, explaining a molecular route to translational suppression.\",\n      \"evidence\": \"Yeast two-hybrid, GST pull-down, co-IP, domain mapping, in vitro ubiquitylation and in vitro translation assays\",\n      \"pmids\": [\"18459963\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether eEF1A1 degradation accounts for the cell-cycle phenotype not tested\", \"Physiological contexts of translation suppression not defined\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Showed that ABTB1 localization and substrate choice are controlled by binding partners, with TdIF1 driving nuclear recruitment and TdT ubiquitylation.\",\n      \"evidence\": \"Yeast two-hybrid, pull-down, reciprocal co-IP, fluorescence co-localization and ubiquitylation assay in 293T cells\",\n      \"pmids\": [\"19930467\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of nuclear TdT ubiquitylation in vivo unknown\", \"Signals governing cytoplasmic-versus-nuclear partitioning not defined\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Extended ABTB1 function to neuronal proteostasis by linking it to PINK1-dependent autophagic clearance of alpha-synuclein.\",\n      \"evidence\": \"Lentiviral overexpression and shRNA knockdown in A53T transgenic mice, co-IP, immunohistochemistry\",\n      \"pmids\": [\"26916519\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether ABTB1 acts as a CUL3 adaptor in this autophagy context unclear\", \"Direct substrate in the PINK1 pathway not identified\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identified NLRP3 as a degradation substrate, establishing ABTB1 as a negative regulator of inflammasome activation with disease relevance in sepsis and viral infection.\",\n      \"evidence\": \"Knockout mouse model, reciprocal co-IP, ELISA, immunoblot, BMDM assays and rescue experiment; SARS-CoV-2 N protein modulation\",\n      \"pmids\": [\"36936774\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Ubiquitin linkage type on NLRP3 not characterized\", \"Mechanism by which SARS-CoV-2 N protein lowers ABTB1 expression not resolved\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Revealed a regulatory interplay with TRIM4, showing ABTB1 promotes TRIM4 degradation and thereby influences influenza A virus replication.\",\n      \"evidence\": \"Co-IP, mass spectrometry, proteasome inhibition, IAV replication and nuclear import assays\",\n      \"pmids\": [\"37823597\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether ABTB1 uses CUL3 to degrade TRIM4 not established\", \"ABTB1 does not bind NP directly, leaving the chain of causation indirect\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Confirmed ABTB1 as a broad anti-inflammatory factor in vivo by showing its deficiency aggravates colitis and acute liver injury via elevated IL-1\\u03b2.\",\n      \"evidence\": \"Knockout mouse model with DSS and DEN injury models, IL-1\\u03b2 ELISA, histopathology\",\n      \"pmids\": [\"38866194\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Tissue-specific substrates driving each phenotype not dissected\", \"Relative contribution of NLRP3 versus other targets not quantified\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Defined a TRIM4\\u2013ABTB1\\u2013CDK1 axis controlling G2/M, with ABTB1 degrading CDK1 via K27-linked chains and TRIM4 counteracting by degrading ABTB1, providing a mechanistic basis for tumor suppression in glioblastoma.\",\n      \"evidence\": \"Co-IP, ubiquitination assays, protein turnover, domain mapping, flow cytometry and xenograft model\",\n      \"pmids\": [\"42034143\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether CDK1 degradation explains the earlier G1/S phenotype not reconciled\", \"Generality of the axis beyond glioblastoma untested\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Showed that substrate availability is tuned competitively, as TTLL12 displaces ABTB1 from eEF1A1 to block its degradation and drive hepatocellular carcinoma proliferation.\",\n      \"evidence\": \"Co-IP, ubiquitination assay, knockdown/overexpression functional assays and in vivo tumor model\",\n      \"pmids\": [\"42014684\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural basis of the competitive binding not resolved\", \"Whether other substrates are similarly protected by competing partners unknown\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How ABTB1 substrate selection, ubiquitin-linkage specificity, and cytoplasmic/nuclear partitioning are coordinated across its diverse roles in translation, cell cycle, inflammation, and autophagy remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of the ABTB1\\u2013CUL3 substrate complex\", \"Determinants of which substrate is engaged in a given cell type not defined\", \"Unifying logic linking the multiple substrate-specific axes not established\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [1, 4, 6]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [1, 2, 4]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 4, 7]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [1, 2]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [1, 4, 6]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [0, 6]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [4, 8]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"complexes\": [\"CUL3 E3 ubiquitin ligase complex\"],\n    \"partners\": [\"CUL3\", \"eEF1A1\", \"TdIF1\", \"PINK1\", \"NLRP3\", \"TRIM4\", \"CDK1\", \"TTLL12\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}