{"gene":"IRF2BP1","run_date":"2026-04-28T18:06:54","timeline":{"discoveries":[{"year":2003,"finding":"IRF2BP1 was identified as a nuclear transcriptional co-repressor that interacts specifically with the C-terminal repression domain of IRF-2. IRF2BP1 can inhibit both enhancer-activated and basal transcription in a manner independent of histone deacetylation. IRF2BP1 contains an N-terminal zinc finger and a C-terminal RING finger domain (C3HC4 subclass), defining a new family of co-repressor proteins.","method":"Co-immunoprecipitation, nuclear localization assays, transcriptional reporter assays, deletion/mutant analysis of IRF-2 binding","journal":"Nucleic Acids Research","confidence":"High","confidence_rationale":"Tier 2 — reciprocal interaction mapping with functional transcriptional assays, highly cited foundational paper","pmids":["12799427"],"is_preprint":false},{"year":2003,"finding":"An alternatively spliced form of IRF-2 lacking valines 177 and 178 (IRF-2[S]) cannot bind IRF2BP1 and cannot mediate repression despite retaining the same C-terminal repression domain, indicating that the relative conformation of the DNA binding domain and C-terminal region of IRF-2 is crucial for co-repressor recruitment.","method":"Binding assays with IRF-2 splice variants and transcriptional reporter assays","journal":"Nucleic Acids Research","confidence":"High","confidence_rationale":"Tier 2 — direct binding and functional assay with defined mutants, highly cited","pmids":["12799427"],"is_preprint":false},{"year":2008,"finding":"IRF2BP1 was identified as a JDP2-binding protein and functions as a ubiquitin E3 ligase for JDP2 through its RING-finger domain, promoting polyubiquitination of JDP2. IRF2BP1 also represses ATF2-mediated transcriptional activation from a CRE-containing promoter.","method":"Epitope-tagging co-purification, in vitro/in vivo ubiquitination assay, transcriptional reporter assay","journal":"FEBS Letters","confidence":"Medium","confidence_rationale":"Tier 1-2 — ubiquitination assay with RING domain implication, single lab","pmids":["18671972"],"is_preprint":false},{"year":2011,"finding":"IRF2BP1 forms a complex with DIF-1 (IRF-2BP2) and EAP1, where the interaction occurs through the conserved C4 zinc fingers of these proteins. This complex contributes to complex stability and transcriptional repression of FASTKD2 in breast cancer cells, as confirmed by chromatin immunoprecipitation.","method":"Co-immunoprecipitation, ChIP, conditional knockdown, microarray analysis","journal":"Molecular and Cellular Biology","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP with domain mapping, ChIP confirmation, functional KD readout, moderately cited","pmids":["21444724"],"is_preprint":false},{"year":2021,"finding":"IRF2BP1 undergoes transient deSUMOylation in response to EGF stimulation, identified by quantitative SUMO proteomics. SUMOylation-deficient IRF2BP1 affects appropriate expression of immediate early genes including DUSP1 and ATF3. IRF2BP1 acts as a repressor on the DUSP1 promoter, and its transient deSUMOylation permits DUSP1 transcription, while timely reSUMOylation restricts it.","method":"Quantitative mass spectrometry SUMO proteomics, comparison of wild-type vs. SUMOylation-deficient IRF2BP1 mutants, transcriptional reporter assays","journal":"EMBO Reports","confidence":"High","confidence_rationale":"Tier 1-2 — quantitative proteomics plus mutant functional analysis with multiple orthogonal methods in a single study","pmids":["33480129"],"is_preprint":false},{"year":2024,"finding":"Cdk5 suppresses MHC-I expression in breast cancer brain metastases through a pathway involving Irf2bp1: mechanistically, Cdk5 acts upstream of Irf2bp1, which in turn suppresses Stat1, thereby reducing importin α and Nlrc5 activity and impairing the antigen-presentation pathway.","method":"Genetic/pharmacological Cdk5 inhibition, single-cell RNA sequencing, functional immune evasion assays in mouse models","journal":"Nature Cell Biology","confidence":"Medium","confidence_rationale":"Tier 2 — genetic and pharmacological epistasis in vivo with scRNA-seq validation, single study","pmids":["39304713"],"is_preprint":false},{"year":2024,"finding":"IRF2BP1 was identified as a fusion partner of RARA in a variant acute promyelocytic leukemia (APL), producing an IRF2BP1::RARA fusion transcript involving IRF2BP1 exon 1 and RARA exon 3. The patient exhibited classic APL clinical features, suggesting the IRF2BP1 N-terminal region can replace the typical PML domain in driving APL pathogenesis.","method":"Molecular cytogenetics, RT-PCR, fusion transcript sequencing","journal":"American Journal of Hematology","confidence":"Low","confidence_rationale":"Tier 3 — single case report with fusion transcript identification, no in vitro functional validation of 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; it binds the C-terminal repression domain of IRF-2 to repress transcription independently of histone deacetylation, forms a multi-protein complex with IRF2BP2 and EAP1 via C4 zinc fingers to repress target genes such as FASTKD2, acts as a RING-domain E3 ubiquitin ligase for JDP2 to inhibit ATF2-dependent transcription, undergoes signal-regulated SUMO modification that controls its repressive activity at immediate-early gene promoters (e.g., DUSP1) during EGFR signaling, and participates in the Cdk5–Irf2bp1–Stat1–Nlrc5 pathway to suppress MHC-I-mediated antigen presentation."},"narrative":{"teleology":[{"year":2003,"claim":"Identifying IRF2BP1 as a co-repressor that binds the IRF-2 repression domain established the gene's core function as a transcriptional silencer acting independently of HDAC activity, answering how IRF-2 mediates repression through recruited cofactors.","evidence":"Co-immunoprecipitation, nuclear localization, and transcriptional reporter assays with IRF-2 deletion/splice mutants in mammalian cells","pmids":["12799427"],"confidence":"High","gaps":["Endogenous genomic targets of IRF2BP1 repression were not identified","Mechanism by which repression occurs without HDAC involvement was not resolved","Whether the RING finger domain has catalytic activity was untested"]},{"year":2008,"claim":"Demonstrating that the RING domain functions as an E3 ubiquitin ligase for JDP2, and that IRF2BP1 represses ATF2/CRE-driven transcription, expanded the gene's mechanism beyond simple co-repressor binding to include enzymatic substrate ubiquitination.","evidence":"In vitro and in vivo ubiquitination assays with RING-domain constructs and transcriptional reporter assays","pmids":["18671972"],"confidence":"Medium","gaps":["Whether JDP2 ubiquitination leads to its degradation or non-proteolytic signaling was not resolved","No in vivo demonstration that E3 ligase activity is required for co-repressor function","Single laboratory finding without independent replication"]},{"year":2011,"claim":"Showing that IRF2BP1 assembles with IRF2BP2 and EAP1 via C4 zinc fingers into a co-repressor complex that occupies the FASTKD2 promoter revealed that IRF2BP1 functions within a multi-subunit repressive complex rather than solely as an IRF-2 adaptor.","evidence":"Reciprocal co-immunoprecipitation, domain mapping, ChIP, knockdown, and microarray in breast cancer cell lines","pmids":["21444724"],"confidence":"High","gaps":["Genome-wide target repertoire of the ternary complex was not defined","Structural basis of the C4 zinc-finger-mediated trimerization is unknown","Functional contribution of individual subunits to repression was not fully dissected"]},{"year":2021,"claim":"Quantitative SUMO proteomics revealed that IRF2BP1 repressor activity is dynamically regulated by signal-dependent SUMO cycling during EGFR signaling, establishing how extracellular cues temporally control immediate-early gene derepression (e.g., DUSP1) and re-silencing.","evidence":"Quantitative mass spectrometry SUMO proteomics, SUMOylation-deficient IRF2BP1 mutants, and transcriptional reporter assays","pmids":["33480129"],"confidence":"High","gaps":["The SUMO E3 ligase and SENP isopeptidase responsible for IRF2BP1 cycling were not identified","Whether SUMO modification alters IRF2BP1 chromatin occupancy or complex assembly was not determined","Generality of SUMO-dependent regulation beyond EGF-stimulated cells is unknown"]},{"year":2024,"claim":"Placing IRF2BP1 in the Cdk5–Irf2bp1–Stat1–Nlrc5 axis that suppresses MHC-I-mediated antigen presentation connected its repressive activity to immune evasion in brain-metastatic breast cancer.","evidence":"Genetic and pharmacological Cdk5 inhibition, single-cell RNA sequencing, and functional immune evasion assays in mouse models","pmids":["39304713"],"confidence":"Medium","gaps":["Direct biochemical mechanism by which Cdk5 regulates IRF2BP1 (phosphorylation, stabilization) is unknown","Whether IRF2BP1 directly binds the Stat1 promoter or acts indirectly was not resolved","Findings are from mouse models; human validation is pending"]},{"year":null,"claim":"Key unresolved questions include the structural basis of IRF2BP1's interactions, the identity of the SUMO/deSUMO machinery controlling its activity, and whether its E3 ligase and co-repressor functions are separable in physiological settings.","evidence":"","pmids":[],"confidence":"High","gaps":["No structural model of IRF2BP1 or its complexes exists","Full genome-wide target landscape across cell types has not been mapped","Separation-of-function between RING-dependent ubiquitin ligase activity and co-repressor recruitment has not been tested in vivo"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[0,1,3,4]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[2]},{"term_id":"GO:0016874","term_label":"ligase activity","supporting_discovery_ids":[2]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,3,4]}],"pathway":[{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[0,3,4]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[2]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[4,5]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[5]}],"complexes":["IRF2BP1–IRF2BP2–EAP1 co-repressor complex"],"partners":["IRF2","IRF2BP2","EAP1","JDP2","CDK5"],"other_free_text":[]},"mechanistic_narrative":"IRF2BP1 is a nuclear transcriptional co-repressor that couples signal-regulated post-translational modifications to chromatin-level gene control. It binds the C-terminal repression domain of IRF-2 through a conformation-sensitive interface and represses both enhancer-activated and basal transcription independently of histone deacetylation, using an N-terminal zinc finger and a C-terminal RING finger (C3HC4) domain [PMID:12799427]. The RING domain confers E3 ubiquitin ligase activity toward JDP2, thereby inhibiting ATF2-dependent transcription from CRE-containing promoters [PMID:18671972], while a conserved C4 zinc finger mediates assembly with IRF2BP2 and EAP1 into a co-repressor complex that occupies and silences targets such as FASTKD2 [PMID:21444724]. IRF2BP1 repressive activity is dynamically tuned by SUMO cycling during EGFR signaling—transient deSUMOylation derepresses immediate-early genes including DUSP1, and timely reSUMOylation restores silencing [PMID:33480129]—and in breast cancer brain metastases it operates downstream of Cdk5 to suppress Stat1-dependent MHC-I antigen presentation [PMID:39304713]."},"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":46,"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":33,"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":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":"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":25,"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":6,"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":5,"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":8493,"output_tokens":1816,"usd":0.02636},"stage2":{"model":"claude-opus-4-6","input_tokens":5084,"output_tokens":2042,"usd":0.114705},"total_usd":0.141065,"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\": 2003,\n      \"finding\": \"IRF2BP1 was identified as a nuclear transcriptional co-repressor that interacts specifically with the C-terminal repression domain of IRF-2. IRF2BP1 can inhibit both enhancer-activated and basal transcription in a manner independent of histone deacetylation. IRF2BP1 contains an N-terminal zinc finger and a C-terminal RING finger domain (C3HC4 subclass), defining a new family of co-repressor proteins.\",\n      \"method\": \"Co-immunoprecipitation, nuclear localization assays, transcriptional reporter assays, deletion/mutant analysis of IRF-2 binding\",\n      \"journal\": \"Nucleic Acids Research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal interaction mapping with functional transcriptional assays, highly cited foundational paper\",\n      \"pmids\": [\"12799427\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"An alternatively spliced form of IRF-2 lacking valines 177 and 178 (IRF-2[S]) cannot bind IRF2BP1 and cannot mediate repression despite retaining the same C-terminal repression domain, indicating that the relative conformation of the DNA binding domain and C-terminal region of IRF-2 is crucial for co-repressor recruitment.\",\n      \"method\": \"Binding assays with IRF-2 splice variants and transcriptional reporter assays\",\n      \"journal\": \"Nucleic Acids Research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct binding and functional assay with defined mutants, highly cited\",\n      \"pmids\": [\"12799427\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"IRF2BP1 was identified as a JDP2-binding protein and functions as a ubiquitin E3 ligase for JDP2 through its RING-finger domain, promoting polyubiquitination of JDP2. IRF2BP1 also represses ATF2-mediated transcriptional activation from a CRE-containing promoter.\",\n      \"method\": \"Epitope-tagging co-purification, in vitro/in vivo ubiquitination assay, transcriptional reporter assay\",\n      \"journal\": \"FEBS Letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 — ubiquitination assay with RING domain implication, single lab\",\n      \"pmids\": [\"18671972\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"IRF2BP1 forms a complex with DIF-1 (IRF-2BP2) and EAP1, where the interaction occurs through the conserved C4 zinc fingers of these proteins. This complex contributes to complex stability and transcriptional repression of FASTKD2 in breast cancer cells, as confirmed by chromatin immunoprecipitation.\",\n      \"method\": \"Co-immunoprecipitation, ChIP, conditional knockdown, microarray analysis\",\n      \"journal\": \"Molecular and Cellular Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP with domain mapping, ChIP confirmation, functional KD readout, moderately cited\",\n      \"pmids\": [\"21444724\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"IRF2BP1 undergoes transient deSUMOylation in response to EGF stimulation, identified by quantitative SUMO proteomics. SUMOylation-deficient IRF2BP1 affects appropriate expression of immediate early genes including DUSP1 and ATF3. IRF2BP1 acts as a repressor on the DUSP1 promoter, and its transient deSUMOylation permits DUSP1 transcription, while timely reSUMOylation restricts it.\",\n      \"method\": \"Quantitative mass spectrometry SUMO proteomics, comparison of wild-type vs. SUMOylation-deficient IRF2BP1 mutants, transcriptional reporter assays\",\n      \"journal\": \"EMBO Reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — quantitative proteomics plus mutant functional analysis with multiple orthogonal methods in a single study\",\n      \"pmids\": [\"33480129\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Cdk5 suppresses MHC-I expression in breast cancer brain metastases through a pathway involving Irf2bp1: mechanistically, Cdk5 acts upstream of Irf2bp1, which in turn suppresses Stat1, thereby reducing importin α and Nlrc5 activity and impairing the antigen-presentation pathway.\",\n      \"method\": \"Genetic/pharmacological Cdk5 inhibition, single-cell RNA sequencing, functional immune evasion assays in mouse models\",\n      \"journal\": \"Nature Cell Biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic and pharmacological epistasis in vivo with scRNA-seq validation, single study\",\n      \"pmids\": [\"39304713\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"IRF2BP1 was identified as a fusion partner of RARA in a variant acute promyelocytic leukemia (APL), producing an IRF2BP1::RARA fusion transcript involving IRF2BP1 exon 1 and RARA exon 3. The patient exhibited classic APL clinical features, suggesting the IRF2BP1 N-terminal region can replace the typical PML domain in driving APL pathogenesis.\",\n      \"method\": \"Molecular cytogenetics, RT-PCR, fusion transcript sequencing\",\n      \"journal\": \"American Journal of Hematology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — single case report with fusion transcript identification, no in vitro functional validation of 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; it binds the C-terminal repression domain of IRF-2 to repress transcription independently of histone deacetylation, forms a multi-protein complex with IRF2BP2 and EAP1 via C4 zinc fingers to repress target genes such as FASTKD2, acts as a RING-domain E3 ubiquitin ligase for JDP2 to inhibit ATF2-dependent transcription, undergoes signal-regulated SUMO modification that controls its repressive activity at immediate-early gene promoters (e.g., DUSP1) during EGFR signaling, and participates in the Cdk5–Irf2bp1–Stat1–Nlrc5 pathway to suppress MHC-I-mediated antigen presentation.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"IRF2BP1 is a nuclear transcriptional co-repressor that couples signal-regulated post-translational modifications to chromatin-level gene control. It binds the C-terminal repression domain of IRF-2 through a conformation-sensitive interface and represses both enhancer-activated and basal transcription independently of histone deacetylation, using an N-terminal zinc finger and a C-terminal RING finger (C3HC4) domain [PMID:12799427]. The RING domain confers E3 ubiquitin ligase activity toward JDP2, thereby inhibiting ATF2-dependent transcription from CRE-containing promoters [PMID:18671972], while a conserved C4 zinc finger mediates assembly with IRF2BP2 and EAP1 into a co-repressor complex that occupies and silences targets such as FASTKD2 [PMID:21444724]. IRF2BP1 repressive activity is dynamically tuned by SUMO cycling during EGFR signaling—transient deSUMOylation derepresses immediate-early genes including DUSP1, and timely reSUMOylation restores silencing [PMID:33480129]—and in breast cancer brain metastases it operates downstream of Cdk5 to suppress Stat1-dependent MHC-I antigen presentation [PMID:39304713].\",\n  \"teleology\": [\n    {\n      \"year\": 2003,\n      \"claim\": \"Identifying IRF2BP1 as a co-repressor that binds the IRF-2 repression domain established the gene's core function as a transcriptional silencer acting independently of HDAC activity, answering how IRF-2 mediates repression through recruited cofactors.\",\n      \"evidence\": \"Co-immunoprecipitation, nuclear localization, and transcriptional reporter assays with IRF-2 deletion/splice mutants in mammalian cells\",\n      \"pmids\": [\"12799427\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Endogenous genomic targets of IRF2BP1 repression were not identified\",\n        \"Mechanism by which repression occurs without HDAC involvement was not resolved\",\n        \"Whether the RING finger domain has catalytic activity was untested\"\n      ]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Demonstrating that the RING domain functions as an E3 ubiquitin ligase for JDP2, and that IRF2BP1 represses ATF2/CRE-driven transcription, expanded the gene's mechanism beyond simple co-repressor binding to include enzymatic substrate ubiquitination.\",\n      \"evidence\": \"In vitro and in vivo ubiquitination assays with RING-domain constructs and transcriptional reporter assays\",\n      \"pmids\": [\"18671972\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether JDP2 ubiquitination leads to its degradation or non-proteolytic signaling was not resolved\",\n        \"No in vivo demonstration that E3 ligase activity is required for co-repressor function\",\n        \"Single laboratory finding without independent replication\"\n      ]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Showing that IRF2BP1 assembles with IRF2BP2 and EAP1 via C4 zinc fingers into a co-repressor complex that occupies the FASTKD2 promoter revealed that IRF2BP1 functions within a multi-subunit repressive complex rather than solely as an IRF-2 adaptor.\",\n      \"evidence\": \"Reciprocal co-immunoprecipitation, domain mapping, ChIP, knockdown, and microarray in breast cancer cell lines\",\n      \"pmids\": [\"21444724\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Genome-wide target repertoire of the ternary complex was not defined\",\n        \"Structural basis of the C4 zinc-finger-mediated trimerization is unknown\",\n        \"Functional contribution of individual subunits to repression was not fully dissected\"\n      ]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Quantitative SUMO proteomics revealed that IRF2BP1 repressor activity is dynamically regulated by signal-dependent SUMO cycling during EGFR signaling, establishing how extracellular cues temporally control immediate-early gene derepression (e.g., DUSP1) and re-silencing.\",\n      \"evidence\": \"Quantitative mass spectrometry SUMO proteomics, SUMOylation-deficient IRF2BP1 mutants, and transcriptional reporter assays\",\n      \"pmids\": [\"33480129\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"The SUMO E3 ligase and SENP isopeptidase responsible for IRF2BP1 cycling were not identified\",\n        \"Whether SUMO modification alters IRF2BP1 chromatin occupancy or complex assembly was not determined\",\n        \"Generality of SUMO-dependent regulation beyond EGF-stimulated cells is unknown\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Placing IRF2BP1 in the Cdk5–Irf2bp1–Stat1–Nlrc5 axis that suppresses MHC-I-mediated antigen presentation connected its repressive activity to immune evasion in brain-metastatic breast cancer.\",\n      \"evidence\": \"Genetic and pharmacological Cdk5 inhibition, single-cell RNA sequencing, and functional immune evasion assays in mouse models\",\n      \"pmids\": [\"39304713\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Direct biochemical mechanism by which Cdk5 regulates IRF2BP1 (phosphorylation, stabilization) is unknown\",\n        \"Whether IRF2BP1 directly binds the Stat1 promoter or acts indirectly was not resolved\",\n        \"Findings are from mouse models; human validation is pending\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the structural basis of IRF2BP1's interactions, the identity of the SUMO/deSUMO machinery controlling its activity, and whether its E3 ligase and co-repressor functions are separable in physiological settings.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"No structural model of IRF2BP1 or its complexes exists\",\n        \"Full genome-wide target landscape across cell types has not been mapped\",\n        \"Separation-of-function between RING-dependent ubiquitin ligase activity and co-repressor recruitment has not been tested in vivo\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [0, 1, 3, 4]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [2]},\n      {\"term_id\": \"GO:0016874\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 3, 4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0, 3, 4]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [2]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [4, 5]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"complexes\": [\n      \"IRF2BP1–IRF2BP2–EAP1 co-repressor complex\"\n    ],\n    \"partners\": [\n      \"IRF2\",\n      \"IRF2BP2\",\n      \"EAP1\",\n      \"JDP2\",\n      \"CDK5\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}