{"gene":"IRF2BP1","run_date":"2026-06-10T01:55:23","timeline":{"discoveries":[{"year":2003,"finding":"IRF2BP1 was identified as a novel transcriptional co-repressor that interacts specifically with the C-terminal repression domain of IRF-2. IRF2BP1 is a nuclear protein containing an N-terminal zinc finger and a C-terminal RING finger domain (C3HC4 subclass), and it can inhibit both enhancer-activated and basal transcription in a manner independent of histone deacetylation. An alternatively spliced IRF-2 isoform lacking Val177/178 cannot bind IRF2BP1, indicating the relative conformation of the DNA-binding domain and C-terminal region of IRF-2 is required for co-repressor recruitment.","method":"Co-immunoprecipitation/protein interaction assays, transcription reporter assays, nuclear localization imaging, HDAC inhibitor experiments","journal":"Nucleic Acids Research","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal binding assays, functional transcription repression assays with mechanistic dissection, foundational paper replicated by subsequent work","pmids":["12799427"],"is_preprint":false},{"year":2008,"finding":"IRF2BP1 was isolated as a JDP2-binding protein and shown to act as a ubiquitin E3 ligase for JDP2, enhancing JDP2 polyubiquitination via its RING-finger domain. IRF2BP1 also represses ATF2-mediated transcriptional activation from a CRE-containing promoter.","method":"Epitope-tagging co-immunoprecipitation to identify JDP2 interaction; in vitro/cell-based ubiquitination assay; transcription reporter assay","journal":"FEBS Letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ubiquitination assay plus transcription reporter, single lab, two orthogonal methods","pmids":["18671972"],"is_preprint":false},{"year":2011,"finding":"IRF2BP1 is a component of the DIF-1 (IRF-2BP2) transcriptional repressor complex in breast cancer cells, contributing to complex stability and transcriptional repression of FASTKD2. The interaction between DIF-1, IRF2BP1, and EAP1 occurs through their conserved C4 zinc finger domains. The DIF-1 complex binds to the FASTKD2 promoter, and repression of FASTKD2 by this complex controls apoptosis in breast cancer cells.","method":"Co-immunoprecipitation to identify complex components, chromatin immunoprecipitation (ChIP) at the FASTKD2 promoter, microarray gene expression, RNAi knockdown with apoptosis readout, domain mapping via zinc finger mutants","journal":"Molecular and Cellular Biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, ChIP, functional knockdown with defined phenotype, domain mapping, multiple orthogonal methods in one study","pmids":["21444724"],"is_preprint":false},{"year":2021,"finding":"IRF2BP1 undergoes transient deSUMOylation upon EGF stimulation, and this SUMOylation cycle acts as a molecular switch controlling immediate early gene transcription. IRF2BP1 functions as a transcriptional repressor on the DUSP1 (MKP-1) promoter; transient deSUMOylation of IRF2BP1 permits DUSP1 transcription, while timely reSUMOylation restricts it. Comparison of wild-type versus SUMOylation-deficient IRF2BP1 confirmed that SUMOylation state controls appropriate expression of immediate early genes including DUSP1 and ATF3 in EGFR signaling.","method":"Quantitative SUMO proteomics (mass spectrometry) comparing endogenous SUMO proteomes before/after EGF stimulation; SUMOylation-deficient IRF2BP1 mutant analysis; gene expression assays for immediate early genes","journal":"EMBO Reports","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — quantitative proteomics, site-specific mutagenesis (SUMOylation-deficient mutant), functional gene expression readout, single lab with multiple orthogonal methods","pmids":["33480129"],"is_preprint":false},{"year":2024,"finding":"Cdk5 suppresses MHC-I expression on breast cancer brain metastasis cells through the Irf2bp1-Stat1-importin α-Nlrc5 pathway. IRF2BP1 functions downstream of Cdk5 and upstream of Stat1/importin α/Nlrc5 to mediate MHC-I downregulation, enabling immune evasion.","method":"Single-cell RNA sequencing, genetic/pharmacological Cdk5 inhibition, functional MHC-I expression and antigen-presentation assays, pathway epistasis analysis in mouse BrM models","journal":"Nature Cell Biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis in vivo with defined pathway order, functional MHC-I readout, single study but multiple orthogonal approaches","pmids":["39304713"],"is_preprint":false},{"year":2024,"finding":"IRF2BP1 was identified as a novel fusion partner of RARA in a variant acute promyelocytic leukemia (APL). The IRF2BP1::RARA fusion gene produces a transcript involving IRF2BP1 exon 1 and RARA exon 3, linked by a 9-bp fragment from RARA intron 2, and the patient presented with classical APL clinical features.","method":"Molecular characterization of fusion gene breakpoints and transcript by sequencing","journal":"American Journal of Hematology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single case report with molecular characterization of fusion transcript, no functional mechanistic follow-up of the fusion protein","pmids":["38410879"],"is_preprint":false}],"current_model":"IRF2BP1 is a nuclear transcriptional co-repressor containing an N-terminal zinc finger and a C-terminal RING finger domain that was originally identified as binding the C-terminal repression domain of IRF-2 to inhibit transcription independently of histone deacetylation; it also forms a multi-protein repressor complex with IRF-2BP2 and EAP1 (via C4 zinc finger interactions) to repress target genes such as FASTKD2, acts as a RING-finger E3 ubiquitin ligase for JDP2 to suppress ATF2-dependent transcription, undergoes transient deSUMOylation downstream of EGFR signaling to permit immediate-early gene (DUSP1, ATF3) transcription, and operates downstream of Cdk5 in the Irf2bp1-Stat1-importin α-Nlrc5 pathway to suppress MHC-I expression."},"narrative":{"mechanistic_narrative":"IRF2BP1 is a nuclear transcriptional co-repressor that controls gene expression through both direct repressor-complex assembly and RING-dependent enzymatic activity [PMID:12799427, PMID:21444724]. It was originally defined by its specific interaction with the C-terminal repression domain of IRF-2, repressing both enhancer-activated and basal transcription independently of histone deacetylation, with conformational requirements in IRF-2 governing co-repressor recruitment [PMID:12799427]. IRF2BP1 stabilizes and operates within the DIF-1 (IRF-2BP2) repressor complex together with IRF-2BP2 and EAP1 through conserved C4 zinc finger interactions, binding the FASTKD2 promoter to repress its transcription and thereby control apoptosis [PMID:21444724]. Beyond scaffolding, its C-terminal RING finger confers E3 ubiquitin ligase activity toward JDP2, promoting JDP2 polyubiquitination and repressing ATF2-mediated transcription from CRE-containing promoters [PMID:18671972]. Its repressive output is dynamically regulated: a transient deSUMOylation cycle downstream of EGF stimulation acts as a switch that relieves IRF2BP1 repression of the DUSP1 promoter to permit timely immediate-early gene transcription (DUSP1, ATF3) [PMID:33480129]. IRF2BP1 also functions downstream of Cdk5 in an Irf2bp1-Stat1-importin α-Nlrc5 pathway that suppresses MHC-I expression in breast cancer brain metastasis, enabling immune evasion [PMID:39304713]. It has additionally been identified as a RARA fusion partner in a variant acute promyelocytic leukemia [PMID:38410879].","teleology":[{"year":2003,"claim":"Established IRF2BP1 as a bona fide transcriptional co-repressor by defining its interaction with IRF-2 and its HDAC-independent repression mechanism, answering how IRF-2's repression domain executes transcriptional silencing.","evidence":"Co-immunoprecipitation, transcription reporter assays, nuclear localization imaging, and HDAC inhibitor experiments in cells","pmids":["12799427"],"confidence":"High","gaps":["The molecular mechanism of HDAC-independent repression is undefined","No structural basis for the IRF-2 conformational requirement","Genome-wide target repertoire not mapped"]},{"year":2008,"claim":"Revealed that the C-terminal RING finger is catalytically functional, showing IRF2BP1 acts as an E3 ubiquitin ligase for JDP2 and represses ATF2-dependent transcription, expanding its role beyond passive scaffolding to enzymatic regulation.","evidence":"Co-immunoprecipitation, in vitro/cell-based ubiquitination assay, and transcription reporter assay","pmids":["18671972"],"confidence":"Medium","gaps":["Single lab without independent replication","Fate of ubiquitinated JDP2 (degradation vs. signaling) not resolved","Other RING substrates not identified"]},{"year":2011,"claim":"Defined IRF2BP1 as a structural and functional member of the DIF-1/IRF-2BP2/EAP1 repressor complex assembled via C4 zinc finger interactions, linking it to FASTKD2 repression and apoptosis control in breast cancer.","evidence":"Reciprocal Co-IP, ChIP at the FASTKD2 promoter, microarray, RNAi knockdown with apoptosis readout, and zinc finger domain mapping","pmids":["21444724"],"confidence":"High","gaps":["Whether IRF2BP1 contributes catalytic vs. scaffolding function within the complex is unclear","Full set of complex target genes not enumerated","Recruitment to specific promoters not mechanistically dissected"]},{"year":2021,"claim":"Showed that IRF2BP1 repressive activity is dynamically controlled by a SUMOylation cycle downstream of EGFR, identifying transient deSUMOylation as the switch permitting immediate-early gene transcription.","evidence":"Quantitative SUMO proteomics before/after EGF stimulation, SUMOylation-deficient mutant analysis, and immediate-early gene expression assays","pmids":["33480129"],"confidence":"High","gaps":["The SUMO E3/protease enzymes acting on IRF2BP1 are not identified","How SUMO state mechanistically alters repressor function is unknown","Generality beyond DUSP1/ATF3 not established"]},{"year":2024,"claim":"Placed IRF2BP1 within a defined Cdk5-Irf2bp1-Stat1-importin α-Nlrc5 epistatic pathway that suppresses MHC-I, connecting its repressor function to immune evasion in brain metastasis.","evidence":"Single-cell RNA-seq, genetic/pharmacological Cdk5 inhibition, MHC-I/antigen-presentation assays, and pathway epistasis in mouse brain metastasis models","pmids":["39304713"],"confidence":"Medium","gaps":["Direct molecular target of IRF2BP1 in this pathway not defined","Whether RING ligase activity is required is untested","Single study without independent replication"]},{"year":2024,"claim":"Identified IRF2BP1 as a RARA fusion partner in variant APL, raising the possibility of an oncogenic fusion role, though the fusion protein's function was not characterized.","evidence":"Molecular characterization of fusion breakpoints and transcript by sequencing in a single APL case","pmids":["38410879"],"confidence":"Low","gaps":["Single case report with no functional characterization of the fusion protein","Transforming activity untested","Contribution of IRF2BP1 portion to leukemogenesis unknown"]},{"year":null,"claim":"How IRF2BP1's distinct activities — scaffolding within the DIF-1 complex, RING E3 ligase function, and SUMO-gated repression — are integrated and selectively deployed at different target genes remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model linking zinc finger, RING, and SUMO sites","Genome-wide direct target map absent","Relationship between catalytic and scaffolding roles undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[0,2,3]},{"term_id":"GO:0016874","term_label":"ligase activity","supporting_discovery_ids":[1]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[1]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0]}],"pathway":[{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[0,2,3]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[3,4]}],"complexes":["DIF-1 (IRF-2BP2) repressor complex"],"partners":["IRF2","IRF2BP2","EAP1","JDP2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q8IU81","full_name":"Interferon regulatory factor 2-binding protein 1","aliases":["Probable E3 ubiquitin-protein ligase IRF2BP1","Probable RING-type E3 ubiquitin transferase IRF2BP1"],"length_aa":584,"mass_kda":61.7,"function":"Acts as a transcriptional corepressor in a IRF2-dependent manner; this repression is not mediated by histone deacetylase activities. May act as an E3 ligase towards JDP2, enhancing its polyubiquitination. Represses ATF2-dependent transcriptional activation","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/Q8IU81/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/IRF2BP1","classification":"Not Classified","n_dependent_lines":26,"n_total_lines":1208,"dependency_fraction":0.02152317880794702},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/IRF2BP1","total_profiled":1310},"omim":[{"mim_id":"615332","title":"INTERFERON REGULATORY FACTOR 2-BINDING PROTEIN 2; IRF2BP2","url":"https://www.omim.org/entry/615332"},{"mim_id":"615331","title":"INTERFERON REGULATORY FACTOR 2-BINDING PROTEIN 1; IRF2BP1","url":"https://www.omim.org/entry/615331"},{"mim_id":"608657","title":"JUN DIMERIZATION PROTEIN 2; JDP2","url":"https://www.omim.org/entry/608657"},{"mim_id":"123811","title":"ACTIVATING TRANSCRIPTION FACTOR 2; ATF2","url":"https://www.omim.org/entry/123811"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/IRF2BP1"},"hgnc":{"alias_symbol":["DKFZP434M154","IRF-2BP1"],"prev_symbol":[]},"alphafold":{"accession":"Q8IU81","domains":[{"cath_id":"-","chopping":"218-348","consensus_level":"high","plddt":87.6892,"start":218,"end":348},{"cath_id":"1.10.10.1580","chopping":"514-573","consensus_level":"high","plddt":89.4485,"start":514,"end":573},{"cath_id":"3.30.40","chopping":"9-58","consensus_level":"high","plddt":94.0404,"start":9,"end":58}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8IU81","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8IU81-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8IU81-F1-predicted_aligned_error_v6.png","plddt_mean":64.44},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=IRF2BP1","jax_strain_url":"https://www.jax.org/strain/search?query=IRF2BP1"},"sequence":{"accession":"Q8IU81","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8IU81.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8IU81/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8IU81"}},"corpus_meta":[{"pmid":"12799427","id":"PMC_12799427","title":"Identification of novel co-repressor molecules for Interferon Regulatory Factor-2.","date":"2003","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/12799427","citation_count":112,"is_preprint":false},{"pmid":"21444724","id":"PMC_21444724","title":"A novel transcription complex that selectively modulates apoptosis of breast cancer cells through regulation of FASTKD2.","date":"2011","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/21444724","citation_count":59,"is_preprint":false},{"pmid":"31022319","id":"PMC_31022319","title":"IRF2BP2: A new player in the regulation of cell homeostasis.","date":"2019","source":"Journal of leukocyte biology","url":"https://pubmed.ncbi.nlm.nih.gov/31022319","citation_count":47,"is_preprint":false},{"pmid":"39304713","id":"PMC_39304713","title":"Astrocyte-induced Cdk5 expedites breast cancer brain metastasis by suppressing MHC-I expression to evade immune recognition.","date":"2024","source":"Nature cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/39304713","citation_count":40,"is_preprint":false},{"pmid":"38091987","id":"PMC_38091987","title":"Systematic analysis of variants escaping nonsense-mediated decay uncovers candidate Mendelian diseases.","date":"2023","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/38091987","citation_count":30,"is_preprint":false},{"pmid":"33996817","id":"PMC_33996817","title":"The Transcriptional Co-factor IRF2BP2: A New Player in Tumor Development and Microenvironment.","date":"2021","source":"Frontiers in cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/33996817","citation_count":26,"is_preprint":false},{"pmid":"24771638","id":"PMC_24771638","title":"Quantitative proteome profiling of lymph node-positive vs. -negative colorectal carcinomas pinpoints MX1 as a marker for lymph node metastasis.","date":"2014","source":"International journal of cancer","url":"https://pubmed.ncbi.nlm.nih.gov/24771638","citation_count":26,"is_preprint":false},{"pmid":"18671972","id":"PMC_18671972","title":"IRF2-binding protein-1 is a JDP2 ubiquitin ligase and an inhibitor of ATF2-dependent transcription.","date":"2008","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/18671972","citation_count":20,"is_preprint":false},{"pmid":"33480129","id":"PMC_33480129","title":"Transient deSUMOylation of IRF2BP proteins controls early transcription in EGFR signaling.","date":"2021","source":"EMBO reports","url":"https://pubmed.ncbi.nlm.nih.gov/33480129","citation_count":19,"is_preprint":false},{"pmid":"30329049","id":"PMC_30329049","title":"Identification of New Potential Therapies for Colitis Amelioration Using an Appendicitis-Appendectomy Model.","date":"2019","source":"Inflammatory bowel diseases","url":"https://pubmed.ncbi.nlm.nih.gov/30329049","citation_count":12,"is_preprint":false},{"pmid":"25243802","id":"PMC_25243802","title":"Modulation of interferon activity-associated soluble molecules by appendicitis and appendectomy limits colitis-identification of novel anti-colitic targets.","date":"2014","source":"Journal of interferon & cytokine research : the official journal of the International Society for Interferon and Cytokine Research","url":"https://pubmed.ncbi.nlm.nih.gov/25243802","citation_count":10,"is_preprint":false},{"pmid":"37867141","id":"PMC_37867141","title":"Genetic susceptibility to post-endoscopic retrograde cholangiopancreatography pancreatitis identified in propensity score-matched analysis.","date":"2023","source":"The Korean journal of internal medicine","url":"https://pubmed.ncbi.nlm.nih.gov/37867141","citation_count":7,"is_preprint":false},{"pmid":"37501076","id":"PMC_37501076","title":"Diagnostic yield and novel candidate genes for neurodevelopmental disorders by exome sequencing in an unselected cohort with microcephaly.","date":"2023","source":"BMC genomics","url":"https://pubmed.ncbi.nlm.nih.gov/37501076","citation_count":7,"is_preprint":false},{"pmid":"38410879","id":"PMC_38410879","title":"Report of IRF2BP1 as a novel partner of RARA in variant acute promyelocytic leukemia.","date":"2024","source":"American journal of hematology","url":"https://pubmed.ncbi.nlm.nih.gov/38410879","citation_count":2,"is_preprint":false},{"pmid":"36775182","id":"PMC_36775182","title":"An IRF2BP member (CgIRF2BP) involved in negative regulation of CgIFNLP expression in oyster Crassostrea gigas.","date":"2023","source":"Fish & shellfish immunology","url":"https://pubmed.ncbi.nlm.nih.gov/36775182","citation_count":1,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9265,"output_tokens":1907,"usd":0.0282,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8809,"output_tokens":2702,"usd":0.055797,"stage2_stop_reason":"end_turn"},"total_usd":0.083997,"stage1_batch_id":"msgbatch_01DUPACZi7AAWwuZiUjseQF4","stage2_batch_id":"msgbatch_018yt7chE3f48PEFtDwtj6AE","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2003,\n      \"finding\": \"IRF2BP1 was identified as a novel transcriptional co-repressor that interacts specifically with the C-terminal repression domain of IRF-2. IRF2BP1 is a nuclear protein containing an N-terminal zinc finger and a C-terminal RING finger domain (C3HC4 subclass), and it can inhibit both enhancer-activated and basal transcription in a manner independent of histone deacetylation. An alternatively spliced IRF-2 isoform lacking Val177/178 cannot bind IRF2BP1, indicating the relative conformation of the DNA-binding domain and C-terminal region of IRF-2 is required for co-repressor recruitment.\",\n      \"method\": \"Co-immunoprecipitation/protein interaction assays, transcription reporter assays, nuclear localization imaging, HDAC inhibitor experiments\",\n      \"journal\": \"Nucleic Acids Research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal binding assays, functional transcription repression assays with mechanistic dissection, foundational paper replicated by subsequent work\",\n      \"pmids\": [\"12799427\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"IRF2BP1 was isolated as a JDP2-binding protein and shown to act as a ubiquitin E3 ligase for JDP2, enhancing JDP2 polyubiquitination via its RING-finger domain. IRF2BP1 also represses ATF2-mediated transcriptional activation from a CRE-containing promoter.\",\n      \"method\": \"Epitope-tagging co-immunoprecipitation to identify JDP2 interaction; in vitro/cell-based ubiquitination assay; transcription reporter assay\",\n      \"journal\": \"FEBS Letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ubiquitination assay plus transcription reporter, single lab, two orthogonal methods\",\n      \"pmids\": [\"18671972\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"IRF2BP1 is a component of the DIF-1 (IRF-2BP2) transcriptional repressor complex in breast cancer cells, contributing to complex stability and transcriptional repression of FASTKD2. The interaction between DIF-1, IRF2BP1, and EAP1 occurs through their conserved C4 zinc finger domains. The DIF-1 complex binds to the FASTKD2 promoter, and repression of FASTKD2 by this complex controls apoptosis in breast cancer cells.\",\n      \"method\": \"Co-immunoprecipitation to identify complex components, chromatin immunoprecipitation (ChIP) at the FASTKD2 promoter, microarray gene expression, RNAi knockdown with apoptosis readout, domain mapping via zinc finger mutants\",\n      \"journal\": \"Molecular and Cellular Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, ChIP, functional knockdown with defined phenotype, domain mapping, multiple orthogonal methods in one study\",\n      \"pmids\": [\"21444724\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"IRF2BP1 undergoes transient deSUMOylation upon EGF stimulation, and this SUMOylation cycle acts as a molecular switch controlling immediate early gene transcription. IRF2BP1 functions as a transcriptional repressor on the DUSP1 (MKP-1) promoter; transient deSUMOylation of IRF2BP1 permits DUSP1 transcription, while timely reSUMOylation restricts it. Comparison of wild-type versus SUMOylation-deficient IRF2BP1 confirmed that SUMOylation state controls appropriate expression of immediate early genes including DUSP1 and ATF3 in EGFR signaling.\",\n      \"method\": \"Quantitative SUMO proteomics (mass spectrometry) comparing endogenous SUMO proteomes before/after EGF stimulation; SUMOylation-deficient IRF2BP1 mutant analysis; gene expression assays for immediate early genes\",\n      \"journal\": \"EMBO Reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — quantitative proteomics, site-specific mutagenesis (SUMOylation-deficient mutant), functional gene expression readout, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"33480129\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Cdk5 suppresses MHC-I expression on breast cancer brain metastasis cells through the Irf2bp1-Stat1-importin α-Nlrc5 pathway. IRF2BP1 functions downstream of Cdk5 and upstream of Stat1/importin α/Nlrc5 to mediate MHC-I downregulation, enabling immune evasion.\",\n      \"method\": \"Single-cell RNA sequencing, genetic/pharmacological Cdk5 inhibition, functional MHC-I expression and antigen-presentation assays, pathway epistasis analysis in mouse BrM models\",\n      \"journal\": \"Nature Cell Biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis in vivo with defined pathway order, functional MHC-I readout, single study but multiple orthogonal approaches\",\n      \"pmids\": [\"39304713\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"IRF2BP1 was identified as a novel fusion partner of RARA in a variant acute promyelocytic leukemia (APL). The IRF2BP1::RARA fusion gene produces a transcript involving IRF2BP1 exon 1 and RARA exon 3, linked by a 9-bp fragment from RARA intron 2, and the patient presented with classical APL clinical features.\",\n      \"method\": \"Molecular characterization of fusion gene breakpoints and transcript by sequencing\",\n      \"journal\": \"American Journal of Hematology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single case report with molecular characterization of fusion transcript, no functional mechanistic follow-up of the fusion protein\",\n      \"pmids\": [\"38410879\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"IRF2BP1 is a nuclear transcriptional co-repressor containing an N-terminal zinc finger and a C-terminal RING finger domain that was originally identified as binding the C-terminal repression domain of IRF-2 to inhibit transcription independently of histone deacetylation; it also forms a multi-protein repressor complex with IRF-2BP2 and EAP1 (via C4 zinc finger interactions) to repress target genes such as FASTKD2, acts as a RING-finger E3 ubiquitin ligase for JDP2 to suppress ATF2-dependent transcription, undergoes transient deSUMOylation downstream of EGFR signaling to permit immediate-early gene (DUSP1, ATF3) transcription, and operates downstream of Cdk5 in the Irf2bp1-Stat1-importin α-Nlrc5 pathway to suppress MHC-I expression.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"IRF2BP1 is a nuclear transcriptional co-repressor that controls gene expression through both direct repressor-complex assembly and RING-dependent enzymatic activity [#0, #2]. It was originally defined by its specific interaction with the C-terminal repression domain of IRF-2, repressing both enhancer-activated and basal transcription independently of histone deacetylation, with conformational requirements in IRF-2 governing co-repressor recruitment [#0]. IRF2BP1 stabilizes and operates within the DIF-1 (IRF-2BP2) repressor complex together with IRF-2BP2 and EAP1 through conserved C4 zinc finger interactions, binding the FASTKD2 promoter to repress its transcription and thereby control apoptosis [#2]. Beyond scaffolding, its C-terminal RING finger confers E3 ubiquitin ligase activity toward JDP2, promoting JDP2 polyubiquitination and repressing ATF2-mediated transcription from CRE-containing promoters [#1]. Its repressive output is dynamically regulated: a transient deSUMOylation cycle downstream of EGF stimulation acts as a switch that relieves IRF2BP1 repression of the DUSP1 promoter to permit timely immediate-early gene transcription (DUSP1, ATF3) [#3]. IRF2BP1 also functions downstream of Cdk5 in an Irf2bp1-Stat1-importin α-Nlrc5 pathway that suppresses MHC-I expression in breast cancer brain metastasis, enabling immune evasion [#4]. It has additionally been identified as a RARA fusion partner in a variant acute promyelocytic leukemia [#5].\",\n  \"teleology\": [\n    {\n      \"year\": 2003,\n      \"claim\": \"Established IRF2BP1 as a bona fide transcriptional co-repressor by defining its interaction with IRF-2 and its HDAC-independent repression mechanism, answering how IRF-2's repression domain executes transcriptional silencing.\",\n      \"evidence\": \"Co-immunoprecipitation, transcription reporter assays, nuclear localization imaging, and HDAC inhibitor experiments in cells\",\n      \"pmids\": [\"12799427\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The molecular mechanism of HDAC-independent repression is undefined\", \"No structural basis for the IRF-2 conformational requirement\", \"Genome-wide target repertoire not mapped\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Revealed that the C-terminal RING finger is catalytically functional, showing IRF2BP1 acts as an E3 ubiquitin ligase for JDP2 and represses ATF2-dependent transcription, expanding its role beyond passive scaffolding to enzymatic regulation.\",\n      \"evidence\": \"Co-immunoprecipitation, in vitro/cell-based ubiquitination assay, and transcription reporter assay\",\n      \"pmids\": [\"18671972\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab without independent replication\", \"Fate of ubiquitinated JDP2 (degradation vs. signaling) not resolved\", \"Other RING substrates not identified\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Defined IRF2BP1 as a structural and functional member of the DIF-1/IRF-2BP2/EAP1 repressor complex assembled via C4 zinc finger interactions, linking it to FASTKD2 repression and apoptosis control in breast cancer.\",\n      \"evidence\": \"Reciprocal Co-IP, ChIP at the FASTKD2 promoter, microarray, RNAi knockdown with apoptosis readout, and zinc finger domain mapping\",\n      \"pmids\": [\"21444724\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether IRF2BP1 contributes catalytic vs. scaffolding function within the complex is unclear\", \"Full set of complex target genes not enumerated\", \"Recruitment to specific promoters not mechanistically dissected\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Showed that IRF2BP1 repressive activity is dynamically controlled by a SUMOylation cycle downstream of EGFR, identifying transient deSUMOylation as the switch permitting immediate-early gene transcription.\",\n      \"evidence\": \"Quantitative SUMO proteomics before/after EGF stimulation, SUMOylation-deficient mutant analysis, and immediate-early gene expression assays\",\n      \"pmids\": [\"33480129\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The SUMO E3/protease enzymes acting on IRF2BP1 are not identified\", \"How SUMO state mechanistically alters repressor function is unknown\", \"Generality beyond DUSP1/ATF3 not established\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Placed IRF2BP1 within a defined Cdk5-Irf2bp1-Stat1-importin α-Nlrc5 epistatic pathway that suppresses MHC-I, connecting its repressor function to immune evasion in brain metastasis.\",\n      \"evidence\": \"Single-cell RNA-seq, genetic/pharmacological Cdk5 inhibition, MHC-I/antigen-presentation assays, and pathway epistasis in mouse brain metastasis models\",\n      \"pmids\": [\"39304713\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct molecular target of IRF2BP1 in this pathway not defined\", \"Whether RING ligase activity is required is untested\", \"Single study without independent replication\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identified IRF2BP1 as a RARA fusion partner in variant APL, raising the possibility of an oncogenic fusion role, though the fusion protein's function was not characterized.\",\n      \"evidence\": \"Molecular characterization of fusion breakpoints and transcript by sequencing in a single APL case\",\n      \"pmids\": [\"38410879\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single case report with no functional characterization of the fusion protein\", \"Transforming activity untested\", \"Contribution of IRF2BP1 portion to leukemogenesis unknown\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How IRF2BP1's distinct activities — scaffolding within the DIF-1 complex, RING E3 ligase function, and SUMO-gated repression — are integrated and selectively deployed at different target genes remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model linking zinc finger, RING, and SUMO sites\", \"Genome-wide direct target map absent\", \"Relationship between catalytic and scaffolding roles undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [0, 2, 3]},\n      {\"term_id\": \"GO:0016874\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0, 2, 3]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [3, 4]}\n    ],\n    \"complexes\": [\"DIF-1 (IRF-2BP2) repressor complex\"],\n    \"partners\": [\"IRF2\", \"IRF2BP2\", \"EAP1\", \"JDP2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":7,"faith_pct":85.71428571428571}}