{"gene":"BRME1","run_date":"2026-06-09T22:02:45","timeline":{"discoveries":[{"year":2020,"finding":"BRME1 (C19orf57/4930432K21Rik) associates with the ssDNA binding proteins BRCA2 and MEILB2/HSF2BP, forming a complex critical for loading recombinases onto DSB sites. In Brme1 KO spermatocytes, removal of ssDNA binding proteins from DSB sites is delayed and loading of RAD51 and DMC1 onto resected ssDNA is impaired.","method":"Co-immunoprecipitation, knockout mouse model with cytological analysis of DSB repair foci","journal":"Cell Reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP plus KO mouse phenotype with specific cytological readouts, replicated across multiple concurrent independent labs","pmids":["32460033"],"is_preprint":false},{"year":2020,"finding":"BRME1 functions as a stabilizer of MEILB2 by binding to the α-helical N-terminus of MEILB2 and preventing MEILB2 self-association. BRCA2 binds to the C-terminus of MEILB2, resulting in formation of a BRCA2-MEILB2-BRME1 ternary complex. In Brme1-/- mice, the BRCA2-MEILB2 complex is destabilized, leading to defects in DSB repair, homolog synapsis, and crossover formation.","method":"Co-immunoprecipitation, knockout mouse model, structural/biochemical binding domain mapping","journal":"Nature Communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP with domain mapping, KO mouse with multiple orthogonal phenotypic readouts, independent from PMID:32460033","pmids":["32345962"],"is_preprint":false},{"year":2020,"finding":"BRME1 is a strong interactor and stabilizer of HSF2BP (MEILB2), and the BRME1/HSF2BP complex co-immunoprecipitates with BRCA2, RAD51, RPA, and PALB2. A hypomorphic HSF2BP-S167L variant causes strongly decreased staining of both HSF2BP and BRME1 at recombination nodules and reduced RAD51/DMC1 foci, leading to fewer crossovers.","method":"Co-immunoprecipitation, mouse genetics (knock-in and knockout), immunofluorescence cytology","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 / Strong — Co-IP identifying multiple complex members, genetic mouse models with cytological quantification, independently corroborates PMID:32345962 and PMID:32460033","pmids":["32845237"],"is_preprint":false},{"year":2020,"finding":"MEIOK21 (BRME1) is a component of meiotic recombination bridges that dynamically localizes on chromosomes from on-axis foci to 'hanging foci', then to 'bridges', and finally to 'fused foci' between homolog axes. Its chromosome localization depends on DSBs. Knockout decreases HSF2BP and DMC1/RAD51 foci numbers, disrupting DSB repair, synapsis, and crossover recombination, causing male infertility. BRME1 physically interacts with HSF2BP.","method":"Knockout mouse model, immunofluorescence cytology, physical interaction assay (co-immunoprecipitation/pulldown)","journal":"Nucleic Acids Research","confidence":"High","confidence_rationale":"Tier 2 / Strong — KO mouse with detailed cytological analysis, direct interaction demonstrated, independently replicates findings of concurrent papers","pmids":["32463460"],"is_preprint":false},{"year":2020,"finding":"MEILB2-BRME1 is activated/expressed in many human cancers, and somatically expressed MEILB2-BRME1 impairs mitotic homologous recombination, implicating misregulation of this meiotic complex in cancer development.","method":"Ectopic expression in somatic/cancer cell lines, HR functional assay","journal":"Nature Communications","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — functional HR assay in cancer cells, single lab, no independent replication reported","pmids":["32345962"],"is_preprint":false},{"year":2024,"finding":"Crystal structure of the MEILB2-BRME1 2:2 core complex reveals a parallel four-helical assembly with an N-terminal β-cap that binds DNA and a MEILB2 coiled-coil bridging to C-terminal ARM domains. Upon BRCA2 binding, MEILB2-BRME1 2:2 complexes dimerize into a V-shaped 2:4:4 complex with β-caps separated by 25 nm, forming a DNA clamp that can bridge between DNA molecules or homologous chromosomes.","method":"X-ray crystallography, in vitro biochemical assays, in vivo localization studies","journal":"Nature Communications","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure with functional validation (DNA binding, in vivo recruitment), single lab but multiple orthogonal methods","pmids":["39095423"],"is_preprint":false},{"year":2023,"finding":"HSF2BP (MEILB2) forms octameric rings that interlock into a large ring-shaped 24-mer upon binding to BRCA2. Addition of BRME1 leads to dissociation of both ring structures, cancels the disruptive effect of HSF2BP on cancer cell resistance to DNA damage, and prevents BRCA2 degradation during interstrand DNA crosslink repair in Xenopus egg extracts.","method":"Structural biochemistry (electron microscopy of oligomeric rings), Xenopus egg extract assay, cancer cell DNA damage resistance assay","journal":"Science Advances","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution of ring assembly/disassembly with structural imaging, orthogonal Xenopus egg extract assay, single lab","pmids":["37889963"],"is_preprint":false},{"year":2024,"finding":"L3MBTL2 (a PRC1.6 component) silences BRME1 in neuroblastoma cells via H2AK119ub histone modification at the BRME1 transcriptional start site. L3MBTL2 knockout de-represses BRME1 expression, and add-back studies show the L3MBTL2-BRME1 axis is important for neuroblastoma cell proliferation.","method":"Knockout and knockdown of L3MBTL2 in neuroblastoma cells, ChIP for H2AK119ub, transcriptome analysis, add-back experiments","journal":"Genes to Cells","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — ChIP evidence for epigenetic silencing mechanism with functional add-back, single lab, indirect evidence for BRME1's role in proliferation context","pmids":["39189159"],"is_preprint":false},{"year":2026,"finding":"PCBP2 recruits hnRNPU and DDX5 to Brme1 mRNA to regulate its stability and alternative splicing in spermatocytes. PCBP2 germline knockout reduces BRME1 transcript processing, contributing to delayed meiotic prophase.","method":"IP-MS, RNA-Seq, RIP-Seq in Pcbp2 germline knockout mice","journal":"International Journal of Biological Macromolecules","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — multi-omic approach (IP-MS, RIP-Seq) in KO model, single lab, BRME1 is one of several targets identified","pmids":["41655928"],"is_preprint":false}],"current_model":"BRME1 is a meiosis-specific protein that forms a ternary complex with MEILB2 (HSF2BP) and BRCA2: it stabilizes MEILB2 by binding its α-helical N-terminus and preventing self-association, and upon BRCA2 binding the MEILB2-BRME1 heterodimer (crystal structure resolved as a parallel four-helical assembly with a DNA-binding β-cap) dimerizes into a V-shaped DNA clamp that bridges resected DNA ends or homologous chromosomes to facilitate loading of RAD51 and DMC1 at meiotic DSBs; loss of BRME1 destabilizes the BRCA2-MEILB2 complex, impairs recombinase recruitment, and causes DSB repair failure, asynapsis, and male infertility, while ectopic expression of MEILB2-BRME1 in somatic cancer cells disrupts mitotic homologous recombination."},"narrative":{"mechanistic_narrative":"BRME1 (C19orf57/MEIOK21) is a meiosis-specific protein that promotes homologous recombination at meiotic DNA double-strand breaks (DSBs) by organizing a BRCA2-MEILB2(HSF2BP) recombinase-loading complex [PMID:32460033, PMID:32345962]. It binds the α-helical N-terminus of MEILB2 and prevents MEILB2 self-association, thereby stabilizing MEILB2 and the BRCA2-MEILB2 complex; BRCA2 engages the MEILB2 C-terminus to assemble a BRCA2-MEILB2-BRME1 ternary complex [PMID:32345962]. Structurally, MEILB2-BRME1 forms a parallel four-helical 2:2 core carrying an N-terminal β-cap that binds DNA, and upon BRCA2 binding these cores dimerize into a V-shaped 2:4:4 DNA clamp whose two β-caps are separated by ~25 nm, allowing it to bridge between DNA molecules or homologous chromosomes [PMID:39095423]. BRME1 also acts as a regulatory switch on MEILB2 oligomerization: it dissociates the octameric and BRCA2-induced 24-mer rings formed by MEILB2 and protects BRCA2 from degradation during interstrand crosslink repair [PMID:37889963]. On meiotic chromosomes BRME1 localizes in a DSB-dependent manner, progressing through on-axis foci, hanging foci, bridges, and fused foci, and its loss reduces MEILB2, RAD51, and DMC1 foci, impairing DSB repair, synapsis, and crossover formation and causing male infertility [PMID:32845237, PMID:32463460]. Ectopic somatic expression of the MEILB2-BRME1 complex disrupts mitotic homologous recombination, linking misregulation of this meiotic module to cancer [PMID:32345962].","teleology":[{"year":2020,"claim":"Established that BRME1 is a meiotic component of the BRCA2-MEILB2 recombinase-loading machinery, answering whether a then-uncharacterized protein contributes to RAD51/DMC1 loading at meiotic DSBs.","evidence":"Co-IP of BRME1 with BRCA2 and MEILB2 plus knockout mouse cytology of DSB repair foci","pmids":["32460033"],"confidence":"High","gaps":["Did not resolve the structural basis of complex assembly","Mechanism of how recombinase loading is delayed not defined at molecular level"]},{"year":2020,"claim":"Defined BRME1's molecular role as a MEILB2 stabilizer that binds the MEILB2 N-terminus and blocks self-association, building a defined BRCA2-MEILB2-BRME1 ternary complex and explaining why BRME1 loss destabilizes the complex.","evidence":"Co-IP with binding-domain mapping and knockout mouse with synapsis/crossover readouts","pmids":["32345962"],"confidence":"High","gaps":["Atomic structure of the complex not yet determined","Stoichiometry of the ternary complex unresolved"]},{"year":2020,"claim":"Independently confirmed the BRME1-MEILB2 interaction and connected it to a hypomorphic HSF2BP variant, showing the complex co-purifies with BRCA2, RAD51, RPA, and PALB2 and is required for recombination nodule localization.","evidence":"Co-IP of multiple complex members plus knock-in/knockout mouse immunofluorescence cytology","pmids":["32845237"],"confidence":"High","gaps":["Direct versus indirect nature of RPA/PALB2 association not distinguished","Order of recruitment to recombination nodules unclear"]},{"year":2020,"claim":"Characterized BRME1's dynamic, DSB-dependent chromosomal localization through on-axis foci, hanging foci, bridges, and fused foci, framing it as a structural component of meiotic recombination bridges between homolog axes.","evidence":"Knockout mouse with detailed immunofluorescence cytology and physical interaction assays","pmids":["32463460"],"confidence":"High","gaps":["Molecular trigger for the focus-to-bridge transition not defined","How bridges physically tether homologs not shown structurally"]},{"year":2020,"claim":"Tested whether the meiotic complex is pathogenic when misexpressed somatically, showing ectopic MEILB2-BRME1 impairs mitotic homologous recombination and is activated in cancers.","evidence":"Ectopic expression in cancer cell lines with HR functional assay","pmids":["32345962"],"confidence":"Medium","gaps":["Single lab, no independent replication","Mechanism of HR impairment in somatic cells not dissected"]},{"year":2023,"claim":"Revealed that BRME1 acts as a switch over MEILB2 oligomeric state, dissociating MEILB2 octamer and BRCA2-induced 24-mer rings and protecting BRCA2 from degradation during crosslink repair.","evidence":"EM of oligomeric rings, Xenopus egg extract crosslink-repair assay, and cancer-cell DNA-damage resistance assay","pmids":["37889963"],"confidence":"High","gaps":["Physiological relevance of ring assembly in meiosis not established","Single lab"]},{"year":2024,"claim":"Resolved the structural architecture of the complex, showing a parallel four-helical 2:2 MEILB2-BRME1 core with a DNA-binding β-cap that, upon BRCA2 binding, forms a V-shaped 2:4:4 DNA clamp able to bridge DNA molecules or chromosomes.","evidence":"X-ray crystallography with in vitro DNA-binding assays and in vivo recruitment studies","pmids":["39095423"],"confidence":"High","gaps":["DNA bridging not directly visualized on chromosomes","How the clamp interfaces with RAD51/DMC1 loading not resolved"]},{"year":2024,"claim":"Identified epigenetic control of BRME1 expression, showing the PRC1.6 component L3MBTL2 silences BRME1 via H2AK119ub and that this axis supports neuroblastoma proliferation.","evidence":"L3MBTL2 knockout/knockdown in neuroblastoma cells, ChIP for H2AK119ub, transcriptomics, and add-back","pmids":["39189159"],"confidence":"Medium","gaps":["Direct role of BRME1 protein in proliferation is indirect","Single lab; mechanism downstream of BRME1 de-repression unclear"]},{"year":2026,"claim":"Showed post-transcriptional control of Brme1 mRNA, with PCBP2 recruiting hnRNPU and DDX5 to regulate its stability and splicing in spermatocytes.","evidence":"IP-MS, RNA-Seq, RIP-Seq in Pcbp2 germline knockout mice","pmids":["41655928"],"confidence":"Medium","gaps":["BRME1 is one of several PCBP2 targets; specific contribution to phenotype not isolated","Single lab"]},{"year":null,"claim":"How the BRME1-MEILB2-BRCA2 DNA clamp mechanically couples chromosome bridging to RAD51/DMC1 nucleofilament assembly at meiotic DSBs remains undefined.","evidence":"","pmids":[],"confidence":"High","gaps":["No direct visualization of recombinase handoff from the clamp","Regulation distinguishing meiotic from aberrant somatic activity not mechanistically resolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[5]},{"term_id":"GO:0140313","term_label":"molecular sequestering activity","supporting_discovery_ids":[1,6]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[1,6]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,1]}],"localization":[{"term_id":"GO:0000228","term_label":"nuclear chromosome","supporting_discovery_ids":[3]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,3]}],"pathway":[{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[0,1]},{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[1,3]}],"complexes":["BRCA2-MEILB2(HSF2BP)-BRME1 ternary complex"],"partners":["HSF2BP","BRCA2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q0VDD7","full_name":"Break repair meiotic recombinase recruitment factor 1","aliases":["Pre-T/NK cell-associated protein 3B3"],"length_aa":668,"mass_kda":69.6,"function":"Meiotic recombination factor component of recombination bridges involved in meiotic double-strand break repair. Modulates the localization of recombinases DMC1:RAD51 to meiotic double-strand break (DSB) sites through the interaction with and stabilization of the BRCA2:HSF2BP complex during meiotic recombination. Indispensable for the DSB repair, homologous synapsis, and crossover formation that are needed for progression past metaphase I, is essential for spermatogenesis and male fertility","subcellular_location":"Chromosome","url":"https://www.uniprot.org/uniprotkb/Q0VDD7/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/BRME1","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/BRME1","total_profiled":1310},"omim":[{"mim_id":"619276","title":"BREAK REPAIR MEIOTIC RECOMBINASE RECRUITMENT FACTOR 1; BRME1","url":"https://www.omim.org/entry/619276"},{"mim_id":"619245","title":"PREMATURE OVARIAN FAILURE 19; POF19","url":"https://www.omim.org/entry/619245"},{"mim_id":"604554","title":"HEAT-SHOCK TRANSCRIPTION FACTOR 2-BINDING PROTEIN; HSF2BP","url":"https://www.omim.org/entry/604554"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"testis","ntpm":13.5}],"url":"https://www.proteinatlas.org/search/BRME1"},"hgnc":{"alias_symbol":["MGC11271","MEIOK21"],"prev_symbol":["C19orf57"]},"alphafold":{"accession":"Q0VDD7","domains":[],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q0VDD7","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q0VDD7-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q0VDD7-F1-predicted_aligned_error_v6.png","plddt_mean":46.66},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=BRME1","jax_strain_url":"https://www.jax.org/strain/search?query=BRME1"},"sequence":{"accession":"Q0VDD7","fasta_url":"https://rest.uniprot.org/uniprotkb/Q0VDD7.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q0VDD7/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q0VDD7"}},"corpus_meta":[{"pmid":"32460033","id":"PMC_32460033","title":"Meiosis-Specific C19orf57/4930432K21Rik/BRME1 Modulates Localization of RAD51 and DMC1 to DSBs in Mouse Meiotic Recombination.","date":"2020","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/32460033","citation_count":49,"is_preprint":false},{"pmid":"32345962","id":"PMC_32345962","title":"The BRCA2-MEILB2-BRME1 complex governs meiotic recombination and impairs the mitotic BRCA2-RAD51 function in cancer cells.","date":"2020","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/32345962","citation_count":42,"is_preprint":false},{"pmid":"32845237","id":"PMC_32845237","title":"A missense in HSF2BP causing primary ovarian insufficiency affects meiotic recombination by its novel interactor C19ORF57/BRME1.","date":"2020","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/32845237","citation_count":32,"is_preprint":false},{"pmid":"31456134","id":"PMC_31456134","title":"Transcriptome sequencing profiles of cervical cancer tissues and SiHa cells.","date":"2019","source":"Functional & integrative genomics","url":"https://pubmed.ncbi.nlm.nih.gov/31456134","citation_count":31,"is_preprint":false},{"pmid":"32463460","id":"PMC_32463460","title":"MEIOK21: a new component of meiotic recombination bridges required for spermatogenesis.","date":"2020","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/32463460","citation_count":25,"is_preprint":false},{"pmid":"37806621","id":"PMC_37806621","title":"Liver transcriptome profiles of dairy cows with different serum metabotypes.","date":"2023","source":"Journal of dairy science","url":"https://pubmed.ncbi.nlm.nih.gov/37806621","citation_count":9,"is_preprint":false},{"pmid":"34625364","id":"PMC_34625364","title":"BRCA2 in mammalian meiosis.","date":"2021","source":"Trends in cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/34625364","citation_count":6,"is_preprint":false},{"pmid":"36686818","id":"PMC_36686818","title":"Alternative splicing event associated with immunological features in bladder cancer.","date":"2023","source":"Frontiers in oncology","url":"https://pubmed.ncbi.nlm.nih.gov/36686818","citation_count":5,"is_preprint":false},{"pmid":"36857322","id":"PMC_36857322","title":"Therapeutic implications of transcriptomics in head and neck cancer patient-derived xenografts.","date":"2023","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/36857322","citation_count":5,"is_preprint":false},{"pmid":"39189159","id":"PMC_39189159","title":"L3MBTL2 maintains MYCN-amplified neuroblastoma cell proliferation through silencing NRIP3 and BRME1 genes.","date":"2024","source":"Genes to cells : devoted to molecular & cellular mechanisms","url":"https://pubmed.ncbi.nlm.nih.gov/39189159","citation_count":4,"is_preprint":false},{"pmid":"39095423","id":"PMC_39095423","title":"MEILB2-BRME1 forms a V-shaped DNA clamp upon BRCA2-binding in meiotic recombination.","date":"2024","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/39095423","citation_count":3,"is_preprint":false},{"pmid":"37889963","id":"PMC_37889963","title":"BRCA2-HSF2BP oligomeric ring disassembly by BRME1 promotes homologous recombination.","date":"2023","source":"Science advances","url":"https://pubmed.ncbi.nlm.nih.gov/37889963","citation_count":2,"is_preprint":false},{"pmid":"34755660","id":"PMC_34755660","title":"[Peripheral blood EMR3 gene methylation level is correlated with breast cancer in Chinese women].","date":"2021","source":"Nan fang yi ke da xue xue bao = Journal of Southern Medical University","url":"https://pubmed.ncbi.nlm.nih.gov/34755660","citation_count":0,"is_preprint":false},{"pmid":"41655928","id":"PMC_41655928","title":"The Poly(rC) binding protein 2 is required for spermatogenesis by regulating alternative splicing and mRNA stability.","date":"2026","source":"International journal of biological macromolecules","url":"https://pubmed.ncbi.nlm.nih.gov/41655928","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9597,"output_tokens":2488,"usd":0.033056,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9562,"output_tokens":3278,"usd":0.06488,"stage2_stop_reason":"end_turn"},"total_usd":0.097936,"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\": 2020,\n      \"finding\": \"BRME1 (C19orf57/4930432K21Rik) associates with the ssDNA binding proteins BRCA2 and MEILB2/HSF2BP, forming a complex critical for loading recombinases onto DSB sites. In Brme1 KO spermatocytes, removal of ssDNA binding proteins from DSB sites is delayed and loading of RAD51 and DMC1 onto resected ssDNA is impaired.\",\n      \"method\": \"Co-immunoprecipitation, knockout mouse model with cytological analysis of DSB repair foci\",\n      \"journal\": \"Cell Reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP plus KO mouse phenotype with specific cytological readouts, replicated across multiple concurrent independent labs\",\n      \"pmids\": [\"32460033\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"BRME1 functions as a stabilizer of MEILB2 by binding to the α-helical N-terminus of MEILB2 and preventing MEILB2 self-association. BRCA2 binds to the C-terminus of MEILB2, resulting in formation of a BRCA2-MEILB2-BRME1 ternary complex. In Brme1-/- mice, the BRCA2-MEILB2 complex is destabilized, leading to defects in DSB repair, homolog synapsis, and crossover formation.\",\n      \"method\": \"Co-immunoprecipitation, knockout mouse model, structural/biochemical binding domain mapping\",\n      \"journal\": \"Nature Communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP with domain mapping, KO mouse with multiple orthogonal phenotypic readouts, independent from PMID:32460033\",\n      \"pmids\": [\"32345962\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"BRME1 is a strong interactor and stabilizer of HSF2BP (MEILB2), and the BRME1/HSF2BP complex co-immunoprecipitates with BRCA2, RAD51, RPA, and PALB2. A hypomorphic HSF2BP-S167L variant causes strongly decreased staining of both HSF2BP and BRME1 at recombination nodules and reduced RAD51/DMC1 foci, leading to fewer crossovers.\",\n      \"method\": \"Co-immunoprecipitation, mouse genetics (knock-in and knockout), immunofluorescence cytology\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — Co-IP identifying multiple complex members, genetic mouse models with cytological quantification, independently corroborates PMID:32345962 and PMID:32460033\",\n      \"pmids\": [\"32845237\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"MEIOK21 (BRME1) is a component of meiotic recombination bridges that dynamically localizes on chromosomes from on-axis foci to 'hanging foci', then to 'bridges', and finally to 'fused foci' between homolog axes. Its chromosome localization depends on DSBs. Knockout decreases HSF2BP and DMC1/RAD51 foci numbers, disrupting DSB repair, synapsis, and crossover recombination, causing male infertility. BRME1 physically interacts with HSF2BP.\",\n      \"method\": \"Knockout mouse model, immunofluorescence cytology, physical interaction assay (co-immunoprecipitation/pulldown)\",\n      \"journal\": \"Nucleic Acids Research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — KO mouse with detailed cytological analysis, direct interaction demonstrated, independently replicates findings of concurrent papers\",\n      \"pmids\": [\"32463460\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"MEILB2-BRME1 is activated/expressed in many human cancers, and somatically expressed MEILB2-BRME1 impairs mitotic homologous recombination, implicating misregulation of this meiotic complex in cancer development.\",\n      \"method\": \"Ectopic expression in somatic/cancer cell lines, HR functional assay\",\n      \"journal\": \"Nature Communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — functional HR assay in cancer cells, single lab, no independent replication reported\",\n      \"pmids\": [\"32345962\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Crystal structure of the MEILB2-BRME1 2:2 core complex reveals a parallel four-helical assembly with an N-terminal β-cap that binds DNA and a MEILB2 coiled-coil bridging to C-terminal ARM domains. Upon BRCA2 binding, MEILB2-BRME1 2:2 complexes dimerize into a V-shaped 2:4:4 complex with β-caps separated by 25 nm, forming a DNA clamp that can bridge between DNA molecules or homologous chromosomes.\",\n      \"method\": \"X-ray crystallography, in vitro biochemical assays, in vivo localization studies\",\n      \"journal\": \"Nature Communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure with functional validation (DNA binding, in vivo recruitment), single lab but multiple orthogonal methods\",\n      \"pmids\": [\"39095423\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"HSF2BP (MEILB2) forms octameric rings that interlock into a large ring-shaped 24-mer upon binding to BRCA2. Addition of BRME1 leads to dissociation of both ring structures, cancels the disruptive effect of HSF2BP on cancer cell resistance to DNA damage, and prevents BRCA2 degradation during interstrand DNA crosslink repair in Xenopus egg extracts.\",\n      \"method\": \"Structural biochemistry (electron microscopy of oligomeric rings), Xenopus egg extract assay, cancer cell DNA damage resistance assay\",\n      \"journal\": \"Science Advances\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution of ring assembly/disassembly with structural imaging, orthogonal Xenopus egg extract assay, single lab\",\n      \"pmids\": [\"37889963\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"L3MBTL2 (a PRC1.6 component) silences BRME1 in neuroblastoma cells via H2AK119ub histone modification at the BRME1 transcriptional start site. L3MBTL2 knockout de-represses BRME1 expression, and add-back studies show the L3MBTL2-BRME1 axis is important for neuroblastoma cell proliferation.\",\n      \"method\": \"Knockout and knockdown of L3MBTL2 in neuroblastoma cells, ChIP for H2AK119ub, transcriptome analysis, add-back experiments\",\n      \"journal\": \"Genes to Cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — ChIP evidence for epigenetic silencing mechanism with functional add-back, single lab, indirect evidence for BRME1's role in proliferation context\",\n      \"pmids\": [\"39189159\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"PCBP2 recruits hnRNPU and DDX5 to Brme1 mRNA to regulate its stability and alternative splicing in spermatocytes. PCBP2 germline knockout reduces BRME1 transcript processing, contributing to delayed meiotic prophase.\",\n      \"method\": \"IP-MS, RNA-Seq, RIP-Seq in Pcbp2 germline knockout mice\",\n      \"journal\": \"International Journal of Biological Macromolecules\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — multi-omic approach (IP-MS, RIP-Seq) in KO model, single lab, BRME1 is one of several targets identified\",\n      \"pmids\": [\"41655928\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"BRME1 is a meiosis-specific protein that forms a ternary complex with MEILB2 (HSF2BP) and BRCA2: it stabilizes MEILB2 by binding its α-helical N-terminus and preventing self-association, and upon BRCA2 binding the MEILB2-BRME1 heterodimer (crystal structure resolved as a parallel four-helical assembly with a DNA-binding β-cap) dimerizes into a V-shaped DNA clamp that bridges resected DNA ends or homologous chromosomes to facilitate loading of RAD51 and DMC1 at meiotic DSBs; loss of BRME1 destabilizes the BRCA2-MEILB2 complex, impairs recombinase recruitment, and causes DSB repair failure, asynapsis, and male infertility, while ectopic expression of MEILB2-BRME1 in somatic cancer cells disrupts mitotic homologous recombination.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"BRME1 (C19orf57/MEIOK21) is a meiosis-specific protein that promotes homologous recombination at meiotic DNA double-strand breaks (DSBs) by organizing a BRCA2-MEILB2(HSF2BP) recombinase-loading complex [#0, #1]. It binds the α-helical N-terminus of MEILB2 and prevents MEILB2 self-association, thereby stabilizing MEILB2 and the BRCA2-MEILB2 complex; BRCA2 engages the MEILB2 C-terminus to assemble a BRCA2-MEILB2-BRME1 ternary complex [#1]. Structurally, MEILB2-BRME1 forms a parallel four-helical 2:2 core carrying an N-terminal β-cap that binds DNA, and upon BRCA2 binding these cores dimerize into a V-shaped 2:4:4 DNA clamp whose two β-caps are separated by ~25 nm, allowing it to bridge between DNA molecules or homologous chromosomes [#5]. BRME1 also acts as a regulatory switch on MEILB2 oligomerization: it dissociates the octameric and BRCA2-induced 24-mer rings formed by MEILB2 and protects BRCA2 from degradation during interstrand crosslink repair [#6]. On meiotic chromosomes BRME1 localizes in a DSB-dependent manner, progressing through on-axis foci, hanging foci, bridges, and fused foci, and its loss reduces MEILB2, RAD51, and DMC1 foci, impairing DSB repair, synapsis, and crossover formation and causing male infertility [#2, #3]. Ectopic somatic expression of the MEILB2-BRME1 complex disrupts mitotic homologous recombination, linking misregulation of this meiotic module to cancer [#4].\",\n  \"teleology\": [\n    {\n      \"year\": 2020,\n      \"claim\": \"Established that BRME1 is a meiotic component of the BRCA2-MEILB2 recombinase-loading machinery, answering whether a then-uncharacterized protein contributes to RAD51/DMC1 loading at meiotic DSBs.\",\n      \"evidence\": \"Co-IP of BRME1 with BRCA2 and MEILB2 plus knockout mouse cytology of DSB repair foci\",\n      \"pmids\": [\"32460033\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve the structural basis of complex assembly\", \"Mechanism of how recombinase loading is delayed not defined at molecular level\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Defined BRME1's molecular role as a MEILB2 stabilizer that binds the MEILB2 N-terminus and blocks self-association, building a defined BRCA2-MEILB2-BRME1 ternary complex and explaining why BRME1 loss destabilizes the complex.\",\n      \"evidence\": \"Co-IP with binding-domain mapping and knockout mouse with synapsis/crossover readouts\",\n      \"pmids\": [\"32345962\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Atomic structure of the complex not yet determined\", \"Stoichiometry of the ternary complex unresolved\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Independently confirmed the BRME1-MEILB2 interaction and connected it to a hypomorphic HSF2BP variant, showing the complex co-purifies with BRCA2, RAD51, RPA, and PALB2 and is required for recombination nodule localization.\",\n      \"evidence\": \"Co-IP of multiple complex members plus knock-in/knockout mouse immunofluorescence cytology\",\n      \"pmids\": [\"32845237\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct versus indirect nature of RPA/PALB2 association not distinguished\", \"Order of recruitment to recombination nodules unclear\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Characterized BRME1's dynamic, DSB-dependent chromosomal localization through on-axis foci, hanging foci, bridges, and fused foci, framing it as a structural component of meiotic recombination bridges between homolog axes.\",\n      \"evidence\": \"Knockout mouse with detailed immunofluorescence cytology and physical interaction assays\",\n      \"pmids\": [\"32463460\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular trigger for the focus-to-bridge transition not defined\", \"How bridges physically tether homologs not shown structurally\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Tested whether the meiotic complex is pathogenic when misexpressed somatically, showing ectopic MEILB2-BRME1 impairs mitotic homologous recombination and is activated in cancers.\",\n      \"evidence\": \"Ectopic expression in cancer cell lines with HR functional assay\",\n      \"pmids\": [\"32345962\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab, no independent replication\", \"Mechanism of HR impairment in somatic cells not dissected\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Revealed that BRME1 acts as a switch over MEILB2 oligomeric state, dissociating MEILB2 octamer and BRCA2-induced 24-mer rings and protecting BRCA2 from degradation during crosslink repair.\",\n      \"evidence\": \"EM of oligomeric rings, Xenopus egg extract crosslink-repair assay, and cancer-cell DNA-damage resistance assay\",\n      \"pmids\": [\"37889963\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological relevance of ring assembly in meiosis not established\", \"Single lab\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Resolved the structural architecture of the complex, showing a parallel four-helical 2:2 MEILB2-BRME1 core with a DNA-binding β-cap that, upon BRCA2 binding, forms a V-shaped 2:4:4 DNA clamp able to bridge DNA molecules or chromosomes.\",\n      \"evidence\": \"X-ray crystallography with in vitro DNA-binding assays and in vivo recruitment studies\",\n      \"pmids\": [\"39095423\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"DNA bridging not directly visualized on chromosomes\", \"How the clamp interfaces with RAD51/DMC1 loading not resolved\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identified epigenetic control of BRME1 expression, showing the PRC1.6 component L3MBTL2 silences BRME1 via H2AK119ub and that this axis supports neuroblastoma proliferation.\",\n      \"evidence\": \"L3MBTL2 knockout/knockdown in neuroblastoma cells, ChIP for H2AK119ub, transcriptomics, and add-back\",\n      \"pmids\": [\"39189159\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct role of BRME1 protein in proliferation is indirect\", \"Single lab; mechanism downstream of BRME1 de-repression unclear\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Showed post-transcriptional control of Brme1 mRNA, with PCBP2 recruiting hnRNPU and DDX5 to regulate its stability and splicing in spermatocytes.\",\n      \"evidence\": \"IP-MS, RNA-Seq, RIP-Seq in Pcbp2 germline knockout mice\",\n      \"pmids\": [\"41655928\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"BRME1 is one of several PCBP2 targets; specific contribution to phenotype not isolated\", \"Single lab\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the BRME1-MEILB2-BRCA2 DNA clamp mechanically couples chromosome bridging to RAD51/DMC1 nucleofilament assembly at meiotic DSBs remains undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No direct visualization of recombinase handoff from the clamp\", \"Regulation distinguishing meiotic from aberrant somatic activity not mechanistically resolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [5]},\n      {\"term_id\": \"GO:0140313\", \"supporting_discovery_ids\": [1, 6]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [1, 6]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0000228\", \"supporting_discovery_ids\": [3]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [1, 3]}\n    ],\n    \"complexes\": [\"BRCA2-MEILB2(HSF2BP)-BRME1 ternary complex\"],\n    \"partners\": [\"HSF2BP\", \"BRCA2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":6,"faith_pct":83.33333333333333}}