{"gene":"RNF212B","run_date":"2026-06-10T06:43:37","timeline":{"discoveries":[{"year":2024,"finding":"RNF212B is a RING-E3 ligase with ubiquitin activity that is essential for crossover designation and maturation during male and female meiosis in mice. RNF212B colocalizes and physically interacts with RNF212, forming foci along chromosomes from zygonema onward in a synapsis-dependent and DSB-independent manner. These foci consolidate into larger foci at maturing crossover sites, colocalizing with HEI10, CNTD1, and MLH1 by late pachynema.","method":"Co-immunoprecipitation, immunofluorescence/colocalization, mouse knockout, active-site mutagenesis (catalytically inactive RNF212B), SUMOylome analysis of testes, pull-down assay with SUMO- and Ubiquitin-tagged HeLa cells","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — multiple orthogonal methods including KO mice, catalytic mutant, pull-down, SUMOylome, and colocalization; single lab but rigorous and comprehensive","pmids":["38865271"],"is_preprint":false},{"year":2024,"finding":"RNF212B foci formation depends genetically on Rnf212 but not on Msh4, Hei10, or Cntd1. The unloading of RNF212B at the end of pachynema is dependent on Hei10 and Cntd1. Double mutants for Rnf212b and Rnf212 exhibit an identical phenotype to Rnf212b single mutants, while double heterozygotes show a dosage-dependent reduction in crossover number, indicating functional interplay between paralogs.","method":"Genetic epistasis analysis using single and double mutant mice (Rnf212b KO, Rnf212 KO, Msh4 KO, Hei10 KO, Cntd1 KO combinations); immunofluorescence","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis with multiple double-mutant combinations, replicated across sexes in a single rigorous study","pmids":["38865271"],"is_preprint":false},{"year":2024,"finding":"Loss of RNF212B reduces localization of pro-crossover factors MSH4, TEX11, RPA, and MZIP2, and eliminates late crossover intermediates (MLH1 foci), resulting in mostly univalent chromosomes at diakinesis due to loss of the majority of crossovers.","method":"Mouse knockout (Rnf212b null), immunofluorescence for pro-CO factors, diakinesis chromosome spreads","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean KO with multiple downstream marker readouts, comprehensive phenotypic characterization","pmids":["38865271"],"is_preprint":false},{"year":2025,"finding":"RNF212B, RNF212, and HEI10 show divergent spatiotemporal localization dynamics along synapsed chromosomes, with profound differences between spermatocytes and oocytes. Contrasting mutant phenotypes and genetic requirements establish that RNF212B plays distinct but interdependent functions from RNF212 and HEI10 in regulating meiotic recombination and coordinating meiotic prophase-I events by integrating signals from DNA breaks, homolog synapsis, the cell-cycle, and incipient crossover sites.","method":"Live and fixed immunofluorescence localization dynamics, mouse mutant phenotype comparison, genetic epistasis","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — systematic localization and genetic analysis of all three paralogs across multiple mutant backgrounds in two independent studies","pmids":["39761402"],"is_preprint":false},{"year":2025,"finding":"HEIP1 promotes the recruitment of RNF212B (along with HEI10, RNF212, and MutSγ) to maturing crossover sites. RNF212B recruitment is thus dependent on HEIP1 function during meiotic prophase I.","method":"Mouse Heip1 knockout with immunofluorescence for RNF212B localization; direct interaction of HEIP1 with HEI10 shown by co-immunoprecipitation","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — RNF212B recruitment failure shown in Heip1 KO by IF, but direct HEIP1-RNF212B interaction not demonstrated; single lab","pmids":["41118211","40909735"],"is_preprint":false},{"year":2023,"finding":"A homozygous nonsense mutation in RNF212B causes severe male infertility with high aneuploidy rates in sperm and IVF embryos. RNF212B shows meiosis-specific expression by scRNA-seq. Inactivation of Drosophila RNF212B orthologs significantly reduces male fertility, indicating a conserved role in spermatogenesis beyond meiotic recombination (since male Drosophila lack recombination).","method":"Exome sequencing, scRNA-seq, FISH aneuploidy analysis of sperm and embryos, Drosophila ortholog RNAi/knockout male fertility assay","journal":"HGG advances","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — human loss-of-function variant with functional Drosophila ortholog validation, multiple methods, single lab","pmids":["37124137"],"is_preprint":false}],"current_model":"RNF212B is a meiosis-specific RING-domain E3 ubiquitin ligase that, together with its paralog RNF212 and HEI10, is essential for crossover designation and maturation: it loads onto synapsed chromosomes in a synapsis-dependent, DSB-independent manner downstream of RNF212, concentrates at maturing crossover sites together with HEI10/CNTD1/MLH1, promotes retention of pro-crossover factors (MSH4, TEX11, RPA, MZIP2), and is recruited by the master regulator HEIP1; loss of RNF212B abolishes most crossovers, causes aneuploidy, and results in infertility in both mice and humans."},"narrative":{"mechanistic_narrative":"RNF212B is a meiosis-specific RING-domain E3 ubiquitin ligase essential for crossover designation and maturation during both male and female meiosis [PMID:38865271]. It loads onto synapsed chromosomes from zygonema onward in a synapsis-dependent, DSB-independent manner, where it colocalizes and physically interacts with its paralog RNF212, and its foci then consolidate at maturing crossover sites together with HEI10, CNTD1, and MLH1 by late pachynema [PMID:38865271]. Chromosomal loading of RNF212B depends genetically on Rnf212 but not on Msh4, Hei10, or Cntd1, while its removal at the end of pachynema requires Hei10 and Cntd1, placing RNF212B downstream of RNF212 yet under HEI10/CNTD1-dependent turnover [PMID:38865271]; recruitment to crossover sites further requires HEIP1 [PMID:41118211, PMID:40909735]. Functionally, RNF212B promotes retention of pro-crossover factors MSH4, TEX11, RPA, and MZIP2, and its loss eliminates late crossover intermediates (MLH1 foci), producing largely univalent chromosomes at diakinesis [PMID:38865271]. RNF212B, RNF212, and HEI10 display divergent, sex-specific localization dynamics, indicating distinct but interdependent roles in integrating DNA-break, synapsis, and cell-cycle signals at incipient crossover sites [PMID:39761402]. A homozygous nonsense mutation in RNF212B causes severe human male infertility with high sperm and embryo aneuploidy, and disruption of Drosophila orthologs reduces male fertility, establishing a conserved meiosis-specific requirement [PMID:37124137].","teleology":[{"year":2023,"claim":"Established RNF212B as a meiosis-specific factor whose loss causes human infertility, defining its physiological importance before its molecular mechanism was known.","evidence":"Exome sequencing of an infertile male, scRNA-seq expression, FISH aneuploidy analysis, and Drosophila ortholog fertility assays","pmids":["37124137"],"confidence":"Medium","gaps":["Single human family with one loss-of-function variant","Molecular activity of the protein not addressed","Conserved Drosophila role shown despite absence of male recombination, leaving the mechanistic basis unresolved"]},{"year":2024,"claim":"Defined RNF212B as a catalytically active RING-E3 ligase that interacts with RNF212 and marks maturing crossover sites, answering what the protein is and where it acts.","evidence":"Co-IP, immunofluorescence colocalization, knockout and catalytic-mutant mice, SUMOylome and pull-down assays","pmids":["38865271"],"confidence":"High","gaps":["Physiological ubiquitination substrates at crossover sites not identified","Relationship between catalytic activity and SUMOylome changes not mechanistically resolved","Single lab"]},{"year":2024,"claim":"Ordered RNF212B within the crossover pathway by showing its loading depends on RNF212 and its unloading on HEI10/CNTD1, and that it sustains pro-crossover factor retention.","evidence":"Genetic epistasis across single and double mutant mice with immunofluorescence for MSH4, TEX11, RPA, MZIP2, and MLH1","pmids":["38865271"],"confidence":"High","gaps":["Direct molecular basis of RNF212-dependent loading unknown","How RNF212B promotes retention of pro-CO factors mechanistically unclear"]},{"year":2025,"claim":"Resolved that RNF212B, RNF212, and HEI10 have distinct, sex-specific dynamics, establishing non-redundant yet interdependent roles in coordinating prophase-I events.","evidence":"Live and fixed immunofluorescence dynamics and mutant phenotype comparison across paralogs in spermatocytes and oocytes","pmids":["39761402"],"confidence":"High","gaps":["Molecular drivers of the divergent spatiotemporal dynamics not identified","Basis of male-versus-female differences unexplained"]},{"year":2025,"claim":"Identified HEIP1 as an upstream determinant of RNF212B recruitment to maturing crossover sites.","evidence":"Heip1 knockout mice with immunofluorescence for RNF212B localization; HEIP1-HEI10 interaction by co-IP","pmids":["41118211","40909735"],"confidence":"Medium","gaps":["Direct HEIP1-RNF212B physical interaction not demonstrated","Recruitment shown by IF in a single lab without biochemical reconstitution"]},{"year":null,"claim":"The physiological ubiquitination substrates of RNF212B and how its E3 activity mechanistically drives crossover maturation remain undefined.","evidence":"","pmids":[],"confidence":"High","gaps":["No substrate identified for the RING-E3 activity","No structural model of RNF212B or its complexes","Mechanism linking ubiquitination to pro-CO factor retention unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0]}],"localization":[{"term_id":"GO:0000228","term_label":"nuclear chromosome","supporting_discovery_ids":[0,1]}],"pathway":[{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[0,2,5]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[3]}],"complexes":[],"partners":["RNF212","HEI10","CNTD1","MLH1","HEIP1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"A8MTL3","full_name":"E3 ubiquitin-protein ligase RNF212B","aliases":["RING finger protein 212B"],"length_aa":300,"mass_kda":33.6,"function":"Ubiquitin E3 ligase that acts as a crucial factor for crossing-over (CO) formation during meiosis. Essential for normal prophase I progression and for ensuring appropriate CO designation in meiosis. Recruits key components of the cross-over machinery either directly ou indirectly, leading to the activation of the MutL-gamma complex. The function of RNF212B in CO designation is dependent on its catalytic activity","subcellular_location":"Chromosome","url":"https://www.uniprot.org/uniprotkb/A8MTL3/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/RNF212B","classification":"Not Classified","n_dependent_lines":59,"n_total_lines":1208,"dependency_fraction":0.048841059602649006},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/RNF212B","total_profiled":1310},"omim":[{"mim_id":"621020","title":"RING FINGER PROTEIN 212B; RNF212B","url":"https://www.omim.org/entry/621020"},{"mim_id":"612041","title":"RING FINGER PROTEIN 212; RNF212","url":"https://www.omim.org/entry/612041"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Golgi apparatus","reliability":"Approved"},{"location":"Nucleoplasm","reliability":"Additional"},{"location":"Nucleoli","reliability":"Additional"},{"location":"Nucleoli fibrillar center","reliability":"Additional"}],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"kidney","ntpm":24.2}],"url":"https://www.proteinatlas.org/search/RNF212B"},"hgnc":{"alias_symbol":[],"prev_symbol":["C14orf164"]},"alphafold":{"accession":"A8MTL3","domains":[{"cath_id":"3.30.40","chopping":"2-62","consensus_level":"medium","plddt":87.667,"start":2,"end":62},{"cath_id":"1.20.5","chopping":"63-139","consensus_level":"medium","plddt":95.414,"start":63,"end":139}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/A8MTL3","model_url":"https://alphafold.ebi.ac.uk/files/AF-A8MTL3-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-A8MTL3-F1-predicted_aligned_error_v6.png","plddt_mean":66.31},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=RNF212B","jax_strain_url":"https://www.jax.org/strain/search?query=RNF212B"},"sequence":{"accession":"A8MTL3","fasta_url":"https://rest.uniprot.org/uniprotkb/A8MTL3.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/A8MTL3/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/A8MTL3"}},"corpus_meta":[{"pmid":"27029733","id":"PMC_27029733","title":"Conserved Genetic Architecture Underlying Individual Recombination Rate Variation in a Wild Population of Soay Sheep (Ovis aries).","date":"2016","source":"Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/27029733","citation_count":126,"is_preprint":false},{"pmid":"29764960","id":"PMC_29764960","title":"A Genomic Region Containing REC8 and RNF212B Is Associated with Individual Recombination Rate Variation in a Wild Population of Red Deer (Cervus elaphus).","date":"2018","source":"G3 (Bethesda, Md.)","url":"https://pubmed.ncbi.nlm.nih.gov/29764960","citation_count":37,"is_preprint":false},{"pmid":"38865271","id":"PMC_38865271","title":"RNF212B E3 ligase is essential for crossover designation and maturation during male and female meiosis in the mouse.","date":"2024","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/38865271","citation_count":18,"is_preprint":false},{"pmid":"39761402","id":"PMC_39761402","title":"Distinct and interdependent functions of three RING proteins regulate recombination during mammalian meiosis.","date":"2025","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/39761402","citation_count":12,"is_preprint":false},{"pmid":"37124137","id":"PMC_37124137","title":"A pathogenic variant in the uncharacterized RNF212B gene results in severe aneuploidy male infertility and repeated IVF failure.","date":"2023","source":"HGG advances","url":"https://pubmed.ncbi.nlm.nih.gov/37124137","citation_count":8,"is_preprint":false},{"pmid":"40426007","id":"PMC_40426007","title":"Genomic and chromosomal architectures underlying fertility maintenance in the testes of intergeneric homoploid hybrids.","date":"2025","source":"Science China. Life sciences","url":"https://pubmed.ncbi.nlm.nih.gov/40426007","citation_count":1,"is_preprint":false},{"pmid":"40259604","id":"PMC_40259604","title":"A variant in RNF212B may contribute to female infertility and recurrent pregnancy loss.","date":"2025","source":"HGG advances","url":"https://pubmed.ncbi.nlm.nih.gov/40259604","citation_count":0,"is_preprint":false},{"pmid":"41118211","id":"PMC_41118211","title":"HEIP1 orchestrates pro-crossover protein activity during mammalian meiosis.","date":"2025","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/41118211","citation_count":0,"is_preprint":false},{"pmid":"40909735","id":"PMC_40909735","title":"HEIP1 orchestrates pro-crossover protein activity during mammalian meiosis.","date":"2025","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/40909735","citation_count":0,"is_preprint":false},{"pmid":"40515540","id":"PMC_40515540","title":"An Increase in Male Recombination Rate With Age in Dairy Cattle Is Heritable and Polygenic.","date":"2025","source":"Journal of animal breeding and genetics = Zeitschrift fur Tierzuchtung und Zuchtungsbiologie","url":"https://pubmed.ncbi.nlm.nih.gov/40515540","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.05.15.654186","title":"Genome landscape and genetic architecture of recombination in domestic goats (  <i>Capra Hircus</i>  )","date":"2025-05-15","source":"bioRxiv","url":"https://doi.org/10.1101/2025.05.15.654186","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7464,"output_tokens":1833,"usd":0.024944,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8616,"output_tokens":2190,"usd":0.048915,"stage2_stop_reason":"end_turn"},"total_usd":0.073859,"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\": 2024,\n      \"finding\": \"RNF212B is a RING-E3 ligase with ubiquitin activity that is essential for crossover designation and maturation during male and female meiosis in mice. RNF212B colocalizes and physically interacts with RNF212, forming foci along chromosomes from zygonema onward in a synapsis-dependent and DSB-independent manner. These foci consolidate into larger foci at maturing crossover sites, colocalizing with HEI10, CNTD1, and MLH1 by late pachynema.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence/colocalization, mouse knockout, active-site mutagenesis (catalytically inactive RNF212B), SUMOylome analysis of testes, pull-down assay with SUMO- and Ubiquitin-tagged HeLa cells\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — multiple orthogonal methods including KO mice, catalytic mutant, pull-down, SUMOylome, and colocalization; single lab but rigorous and comprehensive\",\n      \"pmids\": [\"38865271\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"RNF212B foci formation depends genetically on Rnf212 but not on Msh4, Hei10, or Cntd1. The unloading of RNF212B at the end of pachynema is dependent on Hei10 and Cntd1. Double mutants for Rnf212b and Rnf212 exhibit an identical phenotype to Rnf212b single mutants, while double heterozygotes show a dosage-dependent reduction in crossover number, indicating functional interplay between paralogs.\",\n      \"method\": \"Genetic epistasis analysis using single and double mutant mice (Rnf212b KO, Rnf212 KO, Msh4 KO, Hei10 KO, Cntd1 KO combinations); immunofluorescence\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis with multiple double-mutant combinations, replicated across sexes in a single rigorous study\",\n      \"pmids\": [\"38865271\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Loss of RNF212B reduces localization of pro-crossover factors MSH4, TEX11, RPA, and MZIP2, and eliminates late crossover intermediates (MLH1 foci), resulting in mostly univalent chromosomes at diakinesis due to loss of the majority of crossovers.\",\n      \"method\": \"Mouse knockout (Rnf212b null), immunofluorescence for pro-CO factors, diakinesis chromosome spreads\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean KO with multiple downstream marker readouts, comprehensive phenotypic characterization\",\n      \"pmids\": [\"38865271\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"RNF212B, RNF212, and HEI10 show divergent spatiotemporal localization dynamics along synapsed chromosomes, with profound differences between spermatocytes and oocytes. Contrasting mutant phenotypes and genetic requirements establish that RNF212B plays distinct but interdependent functions from RNF212 and HEI10 in regulating meiotic recombination and coordinating meiotic prophase-I events by integrating signals from DNA breaks, homolog synapsis, the cell-cycle, and incipient crossover sites.\",\n      \"method\": \"Live and fixed immunofluorescence localization dynamics, mouse mutant phenotype comparison, genetic epistasis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — systematic localization and genetic analysis of all three paralogs across multiple mutant backgrounds in two independent studies\",\n      \"pmids\": [\"39761402\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"HEIP1 promotes the recruitment of RNF212B (along with HEI10, RNF212, and MutSγ) to maturing crossover sites. RNF212B recruitment is thus dependent on HEIP1 function during meiotic prophase I.\",\n      \"method\": \"Mouse Heip1 knockout with immunofluorescence for RNF212B localization; direct interaction of HEIP1 with HEI10 shown by co-immunoprecipitation\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — RNF212B recruitment failure shown in Heip1 KO by IF, but direct HEIP1-RNF212B interaction not demonstrated; single lab\",\n      \"pmids\": [\"41118211\", \"40909735\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"A homozygous nonsense mutation in RNF212B causes severe male infertility with high aneuploidy rates in sperm and IVF embryos. RNF212B shows meiosis-specific expression by scRNA-seq. Inactivation of Drosophila RNF212B orthologs significantly reduces male fertility, indicating a conserved role in spermatogenesis beyond meiotic recombination (since male Drosophila lack recombination).\",\n      \"method\": \"Exome sequencing, scRNA-seq, FISH aneuploidy analysis of sperm and embryos, Drosophila ortholog RNAi/knockout male fertility assay\",\n      \"journal\": \"HGG advances\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — human loss-of-function variant with functional Drosophila ortholog validation, multiple methods, single lab\",\n      \"pmids\": [\"37124137\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"RNF212B is a meiosis-specific RING-domain E3 ubiquitin ligase that, together with its paralog RNF212 and HEI10, is essential for crossover designation and maturation: it loads onto synapsed chromosomes in a synapsis-dependent, DSB-independent manner downstream of RNF212, concentrates at maturing crossover sites together with HEI10/CNTD1/MLH1, promotes retention of pro-crossover factors (MSH4, TEX11, RPA, MZIP2), and is recruited by the master regulator HEIP1; loss of RNF212B abolishes most crossovers, causes aneuploidy, and results in infertility in both mice and humans.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"RNF212B is a meiosis-specific RING-domain E3 ubiquitin ligase essential for crossover designation and maturation during both male and female meiosis [#0]. It loads onto synapsed chromosomes from zygonema onward in a synapsis-dependent, DSB-independent manner, where it colocalizes and physically interacts with its paralog RNF212, and its foci then consolidate at maturing crossover sites together with HEI10, CNTD1, and MLH1 by late pachynema [#0]. Chromosomal loading of RNF212B depends genetically on Rnf212 but not on Msh4, Hei10, or Cntd1, while its removal at the end of pachynema requires Hei10 and Cntd1, placing RNF212B downstream of RNF212 yet under HEI10/CNTD1-dependent turnover [#1]; recruitment to crossover sites further requires HEIP1 [#4]. Functionally, RNF212B promotes retention of pro-crossover factors MSH4, TEX11, RPA, and MZIP2, and its loss eliminates late crossover intermediates (MLH1 foci), producing largely univalent chromosomes at diakinesis [#2]. RNF212B, RNF212, and HEI10 display divergent, sex-specific localization dynamics, indicating distinct but interdependent roles in integrating DNA-break, synapsis, and cell-cycle signals at incipient crossover sites [#3]. A homozygous nonsense mutation in RNF212B causes severe human male infertility with high sperm and embryo aneuploidy, and disruption of Drosophila orthologs reduces male fertility, establishing a conserved meiosis-specific requirement [#5].\",\n  \"teleology\": [\n    {\n      \"year\": 2023,\n      \"claim\": \"Established RNF212B as a meiosis-specific factor whose loss causes human infertility, defining its physiological importance before its molecular mechanism was known.\",\n      \"evidence\": \"Exome sequencing of an infertile male, scRNA-seq expression, FISH aneuploidy analysis, and Drosophila ortholog fertility assays\",\n      \"pmids\": [\"37124137\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single human family with one loss-of-function variant\", \"Molecular activity of the protein not addressed\", \"Conserved Drosophila role shown despite absence of male recombination, leaving the mechanistic basis unresolved\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Defined RNF212B as a catalytically active RING-E3 ligase that interacts with RNF212 and marks maturing crossover sites, answering what the protein is and where it acts.\",\n      \"evidence\": \"Co-IP, immunofluorescence colocalization, knockout and catalytic-mutant mice, SUMOylome and pull-down assays\",\n      \"pmids\": [\"38865271\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological ubiquitination substrates at crossover sites not identified\", \"Relationship between catalytic activity and SUMOylome changes not mechanistically resolved\", \"Single lab\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Ordered RNF212B within the crossover pathway by showing its loading depends on RNF212 and its unloading on HEI10/CNTD1, and that it sustains pro-crossover factor retention.\",\n      \"evidence\": \"Genetic epistasis across single and double mutant mice with immunofluorescence for MSH4, TEX11, RPA, MZIP2, and MLH1\",\n      \"pmids\": [\"38865271\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct molecular basis of RNF212-dependent loading unknown\", \"How RNF212B promotes retention of pro-CO factors mechanistically unclear\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Resolved that RNF212B, RNF212, and HEI10 have distinct, sex-specific dynamics, establishing non-redundant yet interdependent roles in coordinating prophase-I events.\",\n      \"evidence\": \"Live and fixed immunofluorescence dynamics and mutant phenotype comparison across paralogs in spermatocytes and oocytes\",\n      \"pmids\": [\"39761402\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular drivers of the divergent spatiotemporal dynamics not identified\", \"Basis of male-versus-female differences unexplained\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identified HEIP1 as an upstream determinant of RNF212B recruitment to maturing crossover sites.\",\n      \"evidence\": \"Heip1 knockout mice with immunofluorescence for RNF212B localization; HEIP1-HEI10 interaction by co-IP\",\n      \"pmids\": [\"41118211\", \"40909735\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct HEIP1-RNF212B physical interaction not demonstrated\", \"Recruitment shown by IF in a single lab without biochemical reconstitution\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The physiological ubiquitination substrates of RNF212B and how its E3 activity mechanistically drives crossover maturation remain undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No substrate identified for the RING-E3 activity\", \"No structural model of RNF212B or its complexes\", \"Mechanism linking ubiquitination to pro-CO factor retention unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0000228\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [0, 2, 5]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"RNF212\", \"HEI10\", \"CNTD1\", \"MLH1\", \"HEIP1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":6,"faith_pct":83.33333333333333}}