{"gene":"RMI2","run_date":"2026-06-10T06:43:37","timeline":{"discoveries":[{"year":2008,"finding":"BLAP18/RMI2 contains a putative OB-fold domain and is an essential component of the BTB (BLM-Topo IIIα-RMI1) complex; the majority of RMI2 exists in complex with Topo IIIα and RMI1, and depletion of RMI2 destabilizes the BTB complex, abolishes chromatin targeting of BLM, prevents BLM focus assembly upon hydroxyurea treatment, and reduces the double Holliday junction (dHJ) dissolution capability of the complex.","method":"Co-immunoprecipitation, siRNA depletion, chromatin fractionation, immunofluorescence, in vitro dHJ dissolution assay","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — multiple orthogonal methods (Co-IP, in vitro reconstituted dHJ assay, chromatin fractionation, cellular imaging) in a single focused study establishing RMI2 mechanism","pmids":["18923083"],"is_preprint":false},{"year":2013,"finding":"The Topo IIIα-RMI1-RMI2 complex is required for processivity of BLM-mediated 5′ DNA end resection; RMI1-RMI2 potentiates stimulation of BLM DNA unwinding by Topo IIIα in a reconstituted system with purified human proteins.","method":"In vitro reconstitution with purified human proteins, DNA unwinding/resection assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — biochemical reconstitution with purified proteins demonstrating direct stimulatory role, single lab","pmids":["25200081"],"is_preprint":false},{"year":2013,"finding":"MPS1 kinase phosphorylates RMI2 at serine 112 upon spindle assembly checkpoint (SAC) activation during mitosis; the S112A mutant of RMI2 fails to maintain mitotic arrest, causes redistribution defects between nucleoplasm and nuclear matrix, and results in genomic instability (micronuclei, multiple nuclei, aberrant chromosome segregation), while phosphorylation at S112 is independent of BLM and not required for BTR complex stability or BLM focus formation under replication stress.","method":"Phospho-specific analysis, site-directed mutagenesis (S112A), coimmunoprecipitation, immunofluorescence, cellular phenotype assays","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, mutagenesis, and cellular phenotype in single lab with multiple orthogonal approaches","pmids":["24108125"],"is_preprint":false},{"year":2016,"finding":"Loss of RMI2 in human cells (patient-derived and CRISPR knockout) results in elevated sister chromatid exchange, anaphase DNA bridges, and micronuclei, and reduces localization of BLM to ultrafine DNA bridges and FANCD2 at foci linking bridges, indicating that RMI2 is required for full BLM complex function at replication intermediates.","method":"RMI2 knockout cells (patient-derived homozygous deletion and independently generated KO), sister chromatid exchange assay, immunofluorescence","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — two independent RMI2-null cellular models with consistent phenotypes and direct localization experiments","pmids":["27977684"],"is_preprint":false},{"year":2022,"finding":"The Topo IIIα-RMI1-RMI2 (TRR) complex forms an open ssDNA gate of 8.5 ± 3.8 nm; dsDNA binding to the open gate increases its size by ~16%, and BLM alters the mechanical flexibility of the gate, revealing plasticity of the TRR-ssDNA gate mechanism.","method":"Single-molecule optical tweezers, fluorescence microscopy","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Moderate — single-molecule biophysical reconstitution with direct visualization, rigorous quantitative measurements","pmids":["35102151"],"is_preprint":false},{"year":2022,"finding":"The Topo IIIα-RMI1-RMI2 (TRR) complex orients BLM helicase for efficient D-loop disruption; presence of TRR markedly shifts BLM activity from D-loop stabilization toward efficient D-loop disruption, providing a mechanism for HR pathway quality control.","method":"Single-molecule FRET, biochemical D-loop disruption assays with purified proteins","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with purified proteins and single-molecule assays in one focused study","pmids":["35115525"],"is_preprint":false},{"year":2025,"finding":"RAD54L2, a SNF2-family protein, physically interacts with BLM and is revealed by a BLM-TOP3A-RMI1-RMI2 (BTRR) proximity proteome map; RAD54L2 requires an intact ATPase domain to promote non-crossover recombination and is important for BLM recruitment to chromatin.","method":"BioID proximity proteomics of the BTRR complex, co-immunoprecipitation, sister chromatid exchange assays, ATPase domain mutant","journal":"EMBO reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — proximity proteomics plus reciprocal Co-IP and functional mutant in single lab; finding primarily describes RAD54L2 but establishes new BTRR interaction","pmids":["39870965"],"is_preprint":false},{"year":2026,"finding":"The Topo IIIα-RMI1-RMI2 (TRR) complex relaxes highly negatively supercoiled DNA in a processive manner using a single-molecule approach; TRR remains stably bound to DNA after torsional stress is released, providing a mechanistic basis for TRR's role in ultrafine anaphase bridge (UFB) resolution.","method":"Single-molecule optical tweezers combined with fluorescence imaging, real-time supercoiling density measurement","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Moderate — rigorous single-molecule biophysical reconstitution with real-time mechanistic readout, single lab","pmids":["41576078"],"is_preprint":false},{"year":2021,"finding":"In C. elegans, the RMI2 functional homolog RMIF-2 shows dynamic localization to meiotic recombination foci in a manner mutually dependent on other BTR complex proteins (HIM-6/BLM, TOP-3, RMH-1), and is required for crossover distribution and suppression of heterologous recombination during meiosis.","method":"C. elegans genetics, immunofluorescence localization, rmif-2 and rmh-1 mutant phenotype comparison","journal":"PLoS genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ortholog functional study in C. elegans with genetic epistasis and direct localization experiments; relevant as functional homolog with consistent BTR complex architecture","pmids":["34252074"],"is_preprint":false},{"year":2023,"finding":"The β-catenin/TCF complex binds to a TCF binding site at −333/−326 of the RMI2 promoter, driving RMI2 transcription as a Wnt/β-catenin target gene in hepatic cell lines.","method":"Chromatin immunoprecipitation (ChIP) assay, luciferase reporter assay with promoter deletions","journal":"BMC cancer","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP and reporter assay in single lab establishing promoter binding; two orthogonal methods but focused on transcriptional regulation rather than RMI2 protein mechanism","pmids":["37875822"],"is_preprint":false}],"current_model":"RMI2 (BLAP18) is an OB-fold-containing scaffold subunit of the conserved BLM-Topo IIIα-RMI1-RMI2 (BTRR/BTR) dissolvasome complex that stabilizes the complex, targets BLM to chromatin and DNA damage foci, stimulates processivity of BLM-driven 5′ end resection, potentiates double Holliday junction dissolution to enforce non-crossover recombination, and modulates the mechanical gate size of the Topo IIIα-RMI1-RMI2 (TRR) topoisomerase for processive negative supercoil relaxation; additionally, MPS1 kinase phosphorylates RMI2 at S112 during mitotic spindle assembly checkpoint activation, redirecting the complex to the nuclear matrix to maintain mitotic arrest and prevent chromosomal instability."},"narrative":{"mechanistic_narrative":"RMI2 (BLAP18) is an OB-fold-containing scaffold subunit of the conserved BLM-Topoisomerase IIIα-RMI1-RMI2 (BTRR/dissolvasome) complex that governs the resolution of recombination and replication intermediates to enforce genome stability [PMID:18923083]. The majority of cellular RMI2 exists in complex with Topo IIIα and RMI1, and its depletion destabilizes the complex, abolishes chromatin targeting of BLM, prevents BLM focus assembly under replication stress, and reduces double Holliday junction dissolution [PMID:18923083]. Within the reconstituted complex RMI2 acts together with RMI1 to potentiate Topo IIIα-driven stimulation of BLM, conferring processivity on BLM-mediated 5′ DNA end resection [PMID:25200081], and the Topo IIIα-RMI1-RMI2 (TRR) subcomplex orients BLM to favor D-loop disruption over stabilization, providing quality control over the homologous recombination pathway toward non-crossover outcomes [PMID:35115525]. Single-molecule analyses show TRR forms an open ssDNA gate whose mechanical size is modulated by dsDNA binding and by BLM, and that TRR processively relaxes highly negatively supercoiled DNA while remaining stably bound, supplying a mechanistic basis for resolving ultrafine anaphase bridges [PMID:35102151, PMID:41576078]. Consistent with these biochemical roles, loss of RMI2 in human cells elevates sister chromatid exchange and produces anaphase DNA bridges and micronuclei, with impaired BLM and FANCD2 localization to ultrafine bridges [PMID:27977684]. Separately from its dissolvasome function, MPS1 kinase phosphorylates RMI2 at serine 112 upon spindle assembly checkpoint activation, redirecting the complex between nucleoplasm and nuclear matrix to maintain mitotic arrest and prevent chromosomal instability, independent of BLM and of complex stability [PMID:24108125].","teleology":[{"year":2008,"claim":"Established RMI2 as an essential structural subunit of the BLM dissolvasome, answering whether the newly identified OB-fold protein had a defined role in the complex.","evidence":"Co-IP, siRNA depletion, chromatin fractionation, and in vitro dHJ dissolution assay in human cells","pmids":["18923083"],"confidence":"High","gaps":["Did not resolve which contacts within the complex RMI2 mediates","Quantitative contribution of RMI2 to dissolution versus chromatin targeting not separated"]},{"year":2013,"claim":"Defined a biochemical role for RMI2 beyond complex integrity, showing it potentiates BLM unwinding and resection processivity rather than merely scaffolding.","evidence":"In vitro reconstitution with purified human proteins and DNA unwinding/resection assays","pmids":["25200081"],"confidence":"High","gaps":["Single lab","Did not isolate RMI2-specific contribution from RMI1 within the RMI1-RMI2 pair"]},{"year":2013,"claim":"Uncovered a mitosis-specific, dissolvasome-independent function for RMI2 as an MPS1 phosphorylation substrate maintaining the spindle assembly checkpoint.","evidence":"Phospho-specific analysis, S112A mutagenesis, reciprocal Co-IP, and cellular phenotype assays","pmids":["24108125"],"confidence":"Medium","gaps":["Mechanism of nucleoplasm/nuclear-matrix redistribution unresolved","Direct MPS1-RMI2 kinase-substrate relationship in vitro not fully reconstituted"]},{"year":2016,"claim":"Confirmed the physiological requirement for RMI2 in genome maintenance using human null models, linking biochemistry to cellular phenotypes at replication intermediates.","evidence":"Patient-derived and CRISPR RMI2-knockout cells, sister chromatid exchange assays, immunofluorescence","pmids":["27977684"],"confidence":"High","gaps":["Whether RMI2 loss phenotypes are fully accounted for by BLM mislocalization not established","No structural basis for ultrafine-bridge localization defect"]},{"year":2021,"claim":"Extended RMI2 function to meiosis via its ortholog, showing conserved BTR-complex interdependence and roles in crossover control.","evidence":"C. elegans rmif-2 genetics, immunofluorescence, and mutant epistasis with HIM-6/BLM, TOP-3, RMH-1","pmids":["34252074"],"confidence":"Medium","gaps":["Ortholog-based; human meiotic role not directly tested","Molecular basis of mutual localization dependence not defined"]},{"year":2022,"claim":"Provided a mechanistic basis for how the complex enforces non-crossover recombination by reorienting BLM activity and defining the topoisomerase gate.","evidence":"Single-molecule FRET, optical tweezers, and D-loop disruption assays with purified TRR and BLM","pmids":["35115525","35102151"],"confidence":"High","gaps":["RMI2-specific contribution to gate plasticity versus Topo IIIα/RMI1 not isolated","Structural model of the gate in its active state not resolved"]},{"year":2025,"claim":"Expanded the dissolvasome interaction network, identifying RAD54L2 as a BTRR-proximal factor aiding BLM recruitment and non-crossover recombination.","evidence":"BioID proximity proteomics of BTRR, Co-IP, SCE assays, and ATPase-dead RAD54L2 mutant","pmids":["39870965"],"confidence":"Medium","gaps":["Finding centers on RAD54L2; direct RMI2-RAD54L2 contact not shown","Whether RAD54L2 acts through RMI2 specifically is unknown"]},{"year":2026,"claim":"Demonstrated processive supercoil relaxation and stable DNA retention by TRR, linking the topoisomerase mechanism to ultrafine anaphase bridge resolution.","evidence":"Single-molecule optical tweezers with fluorescence imaging and real-time supercoiling measurement","pmids":["41576078"],"confidence":"High","gaps":["RMI2-specific role in processivity not dissected from the complex","In-cell relevance to UFB resolution inferred, not directly observed"]},{"year":null,"claim":"How RMI2's two roles — dissolvasome scaffolding and MPS1-dependent checkpoint maintenance — are coordinated, and the structural basis of its specific contacts within the complex, remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structure isolating RMI2 interfaces within BTRR","Coupling between mitotic phosphorylation and dissolvasome function undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[4,7]},{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[0]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,1]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,2]},{"term_id":"GO:0005694","term_label":"chromosome","supporting_discovery_ids":[0,3]},{"term_id":"GO:0005654","term_label":"nucleoplasm","supporting_discovery_ids":[2]}],"pathway":[{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[0,1,5]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[2,3,7]}],"complexes":["BLM-Topo IIIα-RMI1-RMI2 dissolvasome (BTRR/BTR)"],"partners":["BLM","TOP3A","RMI1","RAD54L2","MPS1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q96E14","full_name":"RecQ-mediated genome instability protein 2","aliases":["BLM-associated protein of 18 kDa","BLAP18"],"length_aa":147,"mass_kda":15.9,"function":"Essential component of the RMI complex, a complex that plays an important role in the processing of homologous recombination intermediates. It is required to regulate sister chromatid segregation and to limit DNA crossover. Essential for the stability, localization, and function of BLM, TOP3A, and complexes containing BLM. In the RMI complex, it is required to target BLM to chromatin and stress-induced nuclear foci and mitotic phosphorylation of BLM","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/Q96E14/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/RMI2","classification":"Not Classified","n_dependent_lines":175,"n_total_lines":1208,"dependency_fraction":0.14486754966887416},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"BLM","stoichiometry":10.0}],"url":"https://opencell.sf.czbiohub.org/search/RMI2","total_profiled":1310},"omim":[{"mim_id":"612426","title":"RECQ-MEDIATED GENOME INSTABILITY 2; RMI2","url":"https://www.omim.org/entry/612426"},{"mim_id":"610404","title":"RECQ-MEDIATED GENOME INSTABILITY 1; RMI1","url":"https://www.omim.org/entry/610404"},{"mim_id":"601243","title":"TOPOISOMERASE, DNA, III, ALPHA; TOP3A","url":"https://www.omim.org/entry/601243"},{"mim_id":"210900","title":"BLOOM SYNDROME; BLM","url":"https://www.omim.org/entry/210900"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nuclear speckles","reliability":"Supported"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"lymphoid tissue","ntpm":34.3}],"url":"https://www.proteinatlas.org/search/RMI2"},"hgnc":{"alias_symbol":["MGC24665","BLAP18"],"prev_symbol":["C16orf75"]},"alphafold":{"accession":"Q96E14","domains":[{"cath_id":"2.40.50.140","chopping":"22-144","consensus_level":"high","plddt":94.9434,"start":22,"end":144}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96E14","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q96E14-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q96E14-F1-predicted_aligned_error_v6.png","plddt_mean":88.62},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=RMI2","jax_strain_url":"https://www.jax.org/strain/search?query=RMI2"},"sequence":{"accession":"Q96E14","fasta_url":"https://rest.uniprot.org/uniprotkb/Q96E14.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q96E14/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96E14"}},"corpus_meta":[{"pmid":"18923083","id":"PMC_18923083","title":"BLAP18/RMI2, a novel OB-fold-containing protein, is an essential component of the Bloom helicase-double Holliday junction dissolvasome.","date":"2008","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/18923083","citation_count":180,"is_preprint":false},{"pmid":"25200081","id":"PMC_25200081","title":"Multifaceted role of the Topo IIIα-RMI1-RMI2 complex and DNA2 in the BLM-dependent pathway of DNA break end resection.","date":"2014","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/25200081","citation_count":65,"is_preprint":false},{"pmid":"27977684","id":"PMC_27977684","title":"Loss of RMI2 Increases Genome Instability and Causes a Bloom-Like Syndrome.","date":"2016","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/27977684","citation_count":46,"is_preprint":false},{"pmid":"23543748","id":"PMC_23543748","title":"Role of replication protein A in double holliday junction dissolution mediated by the BLM-Topo IIIα-RMI1-RMI2 protein complex.","date":"2013","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/23543748","citation_count":38,"is_preprint":false},{"pmid":"35102151","id":"PMC_35102151","title":"Duplex DNA and BLM regulate gate opening by the human TopoIIIα-RMI1-RMI2 complex.","date":"2022","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/35102151","citation_count":16,"is_preprint":false},{"pmid":"35115525","id":"PMC_35115525","title":"The toposiomerase IIIalpha-RMI1-RMI2 complex orients human Bloom's syndrome helicase for efficient disruption of D-loops.","date":"2022","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/35115525","citation_count":12,"is_preprint":false},{"pmid":"24108125","id":"PMC_24108125","title":"Monopolar spindle 1 (MPS1) protein-dependent phosphorylation of RecQ-mediated genome instability protein 2 (RMI2) at serine 112 is essential for BLM-Topo III α-RMI1-RMI2 (BTR) protein complex function upon spindle assembly checkpoint (SAC) activation during mitosis.","date":"2013","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/24108125","citation_count":10,"is_preprint":false},{"pmid":"37875822","id":"PMC_37875822","title":"A combined bioinformatics and experimental approach identifies RMI2 as a Wnt/β-catenin signaling target gene related to hepatocellular carcinoma.","date":"2023","source":"BMC cancer","url":"https://pubmed.ncbi.nlm.nih.gov/37875822","citation_count":7,"is_preprint":false},{"pmid":"34252074","id":"PMC_34252074","title":"Caenorhabditis elegans RMI2 functional homolog-2 (RMIF-2) and RMI1 (RMH-1) have both overlapping and distinct meiotic functions within the BTR complex.","date":"2021","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/34252074","citation_count":7,"is_preprint":false},{"pmid":"39870965","id":"PMC_39870965","title":"The BLM-TOP3A-RMI1-RMI2 proximity map reveals that RAD54L2 suppresses sister chromatid exchanges.","date":"2025","source":"EMBO reports","url":"https://pubmed.ncbi.nlm.nih.gov/39870965","citation_count":2,"is_preprint":false},{"pmid":"34634948","id":"PMC_34634948","title":"The Clinical Significance of RMI2 in Hepatocellular Carcinoma.","date":"2021","source":"Technology in cancer research & treatment","url":"https://pubmed.ncbi.nlm.nih.gov/34634948","citation_count":2,"is_preprint":false},{"pmid":"41576078","id":"PMC_41576078","title":"Mechanistic basis for relaxation of DNA supercoils by human topoisomerase IIIα-RMI1-RMI2.","date":"2026","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/41576078","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.06.16.660032","title":"Comparative Transcriptomics Reveals Inflammatory and Epigenetic Programs that Actively Orchestrate Pineal Brain Sand Calcification","date":"2025-06-20","source":"bioRxiv","url":"https://doi.org/10.1101/2025.06.16.660032","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.04.17.649287","title":"BTRR complex deficiency is a driver for genomic instability in Bloom syndrome","date":"2025-04-22","source":"bioRxiv","url":"https://doi.org/10.1101/2025.04.17.649287","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9159,"output_tokens":2579,"usd":0.033081,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9756,"output_tokens":3057,"usd":0.062603,"stage2_stop_reason":"end_turn"},"total_usd":0.095684,"stage1_batch_id":"msgbatch_01CNoDbkChHEkgrJnL7BwtGJ","stage2_batch_id":"msgbatch_016Y4x9E9Wg5VQDANj9quSQD","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2008,\n      \"finding\": \"BLAP18/RMI2 contains a putative OB-fold domain and is an essential component of the BTB (BLM-Topo IIIα-RMI1) complex; the majority of RMI2 exists in complex with Topo IIIα and RMI1, and depletion of RMI2 destabilizes the BTB complex, abolishes chromatin targeting of BLM, prevents BLM focus assembly upon hydroxyurea treatment, and reduces the double Holliday junction (dHJ) dissolution capability of the complex.\",\n      \"method\": \"Co-immunoprecipitation, siRNA depletion, chromatin fractionation, immunofluorescence, in vitro dHJ dissolution assay\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — multiple orthogonal methods (Co-IP, in vitro reconstituted dHJ assay, chromatin fractionation, cellular imaging) in a single focused study establishing RMI2 mechanism\",\n      \"pmids\": [\"18923083\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"The Topo IIIα-RMI1-RMI2 complex is required for processivity of BLM-mediated 5′ DNA end resection; RMI1-RMI2 potentiates stimulation of BLM DNA unwinding by Topo IIIα in a reconstituted system with purified human proteins.\",\n      \"method\": \"In vitro reconstitution with purified human proteins, DNA unwinding/resection assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — biochemical reconstitution with purified proteins demonstrating direct stimulatory role, single lab\",\n      \"pmids\": [\"25200081\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"MPS1 kinase phosphorylates RMI2 at serine 112 upon spindle assembly checkpoint (SAC) activation during mitosis; the S112A mutant of RMI2 fails to maintain mitotic arrest, causes redistribution defects between nucleoplasm and nuclear matrix, and results in genomic instability (micronuclei, multiple nuclei, aberrant chromosome segregation), while phosphorylation at S112 is independent of BLM and not required for BTR complex stability or BLM focus formation under replication stress.\",\n      \"method\": \"Phospho-specific analysis, site-directed mutagenesis (S112A), coimmunoprecipitation, immunofluorescence, cellular phenotype assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, mutagenesis, and cellular phenotype in single lab with multiple orthogonal approaches\",\n      \"pmids\": [\"24108125\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Loss of RMI2 in human cells (patient-derived and CRISPR knockout) results in elevated sister chromatid exchange, anaphase DNA bridges, and micronuclei, and reduces localization of BLM to ultrafine DNA bridges and FANCD2 at foci linking bridges, indicating that RMI2 is required for full BLM complex function at replication intermediates.\",\n      \"method\": \"RMI2 knockout cells (patient-derived homozygous deletion and independently generated KO), sister chromatid exchange assay, immunofluorescence\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — two independent RMI2-null cellular models with consistent phenotypes and direct localization experiments\",\n      \"pmids\": [\"27977684\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"The Topo IIIα-RMI1-RMI2 (TRR) complex forms an open ssDNA gate of 8.5 ± 3.8 nm; dsDNA binding to the open gate increases its size by ~16%, and BLM alters the mechanical flexibility of the gate, revealing plasticity of the TRR-ssDNA gate mechanism.\",\n      \"method\": \"Single-molecule optical tweezers, fluorescence microscopy\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — single-molecule biophysical reconstitution with direct visualization, rigorous quantitative measurements\",\n      \"pmids\": [\"35102151\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"The Topo IIIα-RMI1-RMI2 (TRR) complex orients BLM helicase for efficient D-loop disruption; presence of TRR markedly shifts BLM activity from D-loop stabilization toward efficient D-loop disruption, providing a mechanism for HR pathway quality control.\",\n      \"method\": \"Single-molecule FRET, biochemical D-loop disruption assays with purified proteins\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with purified proteins and single-molecule assays in one focused study\",\n      \"pmids\": [\"35115525\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"RAD54L2, a SNF2-family protein, physically interacts with BLM and is revealed by a BLM-TOP3A-RMI1-RMI2 (BTRR) proximity proteome map; RAD54L2 requires an intact ATPase domain to promote non-crossover recombination and is important for BLM recruitment to chromatin.\",\n      \"method\": \"BioID proximity proteomics of the BTRR complex, co-immunoprecipitation, sister chromatid exchange assays, ATPase domain mutant\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — proximity proteomics plus reciprocal Co-IP and functional mutant in single lab; finding primarily describes RAD54L2 but establishes new BTRR interaction\",\n      \"pmids\": [\"39870965\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"The Topo IIIα-RMI1-RMI2 (TRR) complex relaxes highly negatively supercoiled DNA in a processive manner using a single-molecule approach; TRR remains stably bound to DNA after torsional stress is released, providing a mechanistic basis for TRR's role in ultrafine anaphase bridge (UFB) resolution.\",\n      \"method\": \"Single-molecule optical tweezers combined with fluorescence imaging, real-time supercoiling density measurement\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — rigorous single-molecule biophysical reconstitution with real-time mechanistic readout, single lab\",\n      \"pmids\": [\"41576078\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"In C. elegans, the RMI2 functional homolog RMIF-2 shows dynamic localization to meiotic recombination foci in a manner mutually dependent on other BTR complex proteins (HIM-6/BLM, TOP-3, RMH-1), and is required for crossover distribution and suppression of heterologous recombination during meiosis.\",\n      \"method\": \"C. elegans genetics, immunofluorescence localization, rmif-2 and rmh-1 mutant phenotype comparison\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ortholog functional study in C. elegans with genetic epistasis and direct localization experiments; relevant as functional homolog with consistent BTR complex architecture\",\n      \"pmids\": [\"34252074\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"The β-catenin/TCF complex binds to a TCF binding site at −333/−326 of the RMI2 promoter, driving RMI2 transcription as a Wnt/β-catenin target gene in hepatic cell lines.\",\n      \"method\": \"Chromatin immunoprecipitation (ChIP) assay, luciferase reporter assay with promoter deletions\",\n      \"journal\": \"BMC cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP and reporter assay in single lab establishing promoter binding; two orthogonal methods but focused on transcriptional regulation rather than RMI2 protein mechanism\",\n      \"pmids\": [\"37875822\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"RMI2 (BLAP18) is an OB-fold-containing scaffold subunit of the conserved BLM-Topo IIIα-RMI1-RMI2 (BTRR/BTR) dissolvasome complex that stabilizes the complex, targets BLM to chromatin and DNA damage foci, stimulates processivity of BLM-driven 5′ end resection, potentiates double Holliday junction dissolution to enforce non-crossover recombination, and modulates the mechanical gate size of the Topo IIIα-RMI1-RMI2 (TRR) topoisomerase for processive negative supercoil relaxation; additionally, MPS1 kinase phosphorylates RMI2 at S112 during mitotic spindle assembly checkpoint activation, redirecting the complex to the nuclear matrix to maintain mitotic arrest and prevent chromosomal instability.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"RMI2 (BLAP18) is an OB-fold-containing scaffold subunit of the conserved BLM-Topoisomerase IIIα-RMI1-RMI2 (BTRR/dissolvasome) complex that governs the resolution of recombination and replication intermediates to enforce genome stability [#0]. The majority of cellular RMI2 exists in complex with Topo IIIα and RMI1, and its depletion destabilizes the complex, abolishes chromatin targeting of BLM, prevents BLM focus assembly under replication stress, and reduces double Holliday junction dissolution [#0]. Within the reconstituted complex RMI2 acts together with RMI1 to potentiate Topo IIIα-driven stimulation of BLM, conferring processivity on BLM-mediated 5′ DNA end resection [#1], and the Topo IIIα-RMI1-RMI2 (TRR) subcomplex orients BLM to favor D-loop disruption over stabilization, providing quality control over the homologous recombination pathway toward non-crossover outcomes [#5]. Single-molecule analyses show TRR forms an open ssDNA gate whose mechanical size is modulated by dsDNA binding and by BLM, and that TRR processively relaxes highly negatively supercoiled DNA while remaining stably bound, supplying a mechanistic basis for resolving ultrafine anaphase bridges [#4, #7]. Consistent with these biochemical roles, loss of RMI2 in human cells elevates sister chromatid exchange and produces anaphase DNA bridges and micronuclei, with impaired BLM and FANCD2 localization to ultrafine bridges [#3]. Separately from its dissolvasome function, MPS1 kinase phosphorylates RMI2 at serine 112 upon spindle assembly checkpoint activation, redirecting the complex between nucleoplasm and nuclear matrix to maintain mitotic arrest and prevent chromosomal instability, independent of BLM and of complex stability [#2].\",\n  \"teleology\": [\n    {\n      \"year\": 2008,\n      \"claim\": \"Established RMI2 as an essential structural subunit of the BLM dissolvasome, answering whether the newly identified OB-fold protein had a defined role in the complex.\",\n      \"evidence\": \"Co-IP, siRNA depletion, chromatin fractionation, and in vitro dHJ dissolution assay in human cells\",\n      \"pmids\": [\"18923083\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve which contacts within the complex RMI2 mediates\", \"Quantitative contribution of RMI2 to dissolution versus chromatin targeting not separated\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Defined a biochemical role for RMI2 beyond complex integrity, showing it potentiates BLM unwinding and resection processivity rather than merely scaffolding.\",\n      \"evidence\": \"In vitro reconstitution with purified human proteins and DNA unwinding/resection assays\",\n      \"pmids\": [\"25200081\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Single lab\", \"Did not isolate RMI2-specific contribution from RMI1 within the RMI1-RMI2 pair\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Uncovered a mitosis-specific, dissolvasome-independent function for RMI2 as an MPS1 phosphorylation substrate maintaining the spindle assembly checkpoint.\",\n      \"evidence\": \"Phospho-specific analysis, S112A mutagenesis, reciprocal Co-IP, and cellular phenotype assays\",\n      \"pmids\": [\"24108125\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of nucleoplasm/nuclear-matrix redistribution unresolved\", \"Direct MPS1-RMI2 kinase-substrate relationship in vitro not fully reconstituted\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Confirmed the physiological requirement for RMI2 in genome maintenance using human null models, linking biochemistry to cellular phenotypes at replication intermediates.\",\n      \"evidence\": \"Patient-derived and CRISPR RMI2-knockout cells, sister chromatid exchange assays, immunofluorescence\",\n      \"pmids\": [\"27977684\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether RMI2 loss phenotypes are fully accounted for by BLM mislocalization not established\", \"No structural basis for ultrafine-bridge localization defect\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Extended RMI2 function to meiosis via its ortholog, showing conserved BTR-complex interdependence and roles in crossover control.\",\n      \"evidence\": \"C. elegans rmif-2 genetics, immunofluorescence, and mutant epistasis with HIM-6/BLM, TOP-3, RMH-1\",\n      \"pmids\": [\"34252074\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Ortholog-based; human meiotic role not directly tested\", \"Molecular basis of mutual localization dependence not defined\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Provided a mechanistic basis for how the complex enforces non-crossover recombination by reorienting BLM activity and defining the topoisomerase gate.\",\n      \"evidence\": \"Single-molecule FRET, optical tweezers, and D-loop disruption assays with purified TRR and BLM\",\n      \"pmids\": [\"35115525\", \"35102151\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"RMI2-specific contribution to gate plasticity versus Topo IIIα/RMI1 not isolated\", \"Structural model of the gate in its active state not resolved\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Expanded the dissolvasome interaction network, identifying RAD54L2 as a BTRR-proximal factor aiding BLM recruitment and non-crossover recombination.\",\n      \"evidence\": \"BioID proximity proteomics of BTRR, Co-IP, SCE assays, and ATPase-dead RAD54L2 mutant\",\n      \"pmids\": [\"39870965\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Finding centers on RAD54L2; direct RMI2-RAD54L2 contact not shown\", \"Whether RAD54L2 acts through RMI2 specifically is unknown\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Demonstrated processive supercoil relaxation and stable DNA retention by TRR, linking the topoisomerase mechanism to ultrafine anaphase bridge resolution.\",\n      \"evidence\": \"Single-molecule optical tweezers with fluorescence imaging and real-time supercoiling measurement\",\n      \"pmids\": [\"41576078\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"RMI2-specific role in processivity not dissected from the complex\", \"In-cell relevance to UFB resolution inferred, not directly observed\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How RMI2's two roles — dissolvasome scaffolding and MPS1-dependent checkpoint maintenance — are coordinated, and the structural basis of its specific contacts within the complex, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structure isolating RMI2 interfaces within BTRR\", \"Coupling between mitotic phosphorylation and dissolvasome function undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [4, 7]},\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 2]},\n      {\"term_id\": \"GO:0005694\", \"supporting_discovery_ids\": [0, 3]},\n      {\"term_id\": \"GO:0005654\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [0, 1, 5]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [2, 3, 7]}\n    ],\n    \"complexes\": [\"BLM-Topo IIIα-RMI1-RMI2 dissolvasome (BTRR/BTR)\"],\n    \"partners\": [\"BLM\", \"TOP3A\", \"RMI1\", \"RAD54L2\", \"MPS1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}