{"gene":"HORMAD2","run_date":"2026-06-10T01:55:22","timeline":{"discoveries":[{"year":2009,"finding":"HORMAD2 preferentially associates with unsynapsed chromosome axes throughout meiotic prophase and is depleted from synapsed axes; TRIP13 AAA-ATPase is required for the reciprocal distribution of HORMADs and SYCP1/SC-component along chromosome axes, indicating TRIP13 promotes HORMAD2 removal from synapsed chromatin.","method":"Immunofluorescence analysis of wild-type and mutant (TRIP13-deficient, DSB-processing mutant) mouse spermatocytes/oocytes; co-localization with SC markers","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct localization experiments with functional consequence in defined genetic mutants, replicated across multiple mutant backgrounds by the same study and corroborated by subsequent independent labs","pmids":["19851446"],"is_preprint":false},{"year":2012,"finding":"HORMAD2 is required for accumulation of the checkpoint kinase ATR along unsynapsed chromosome axes (but not at DNA DSBs or DSB-associated chromatin loops), and this HORMAD2-dependent ATR recruitment constitutes a distinct asynapsis surveillance mechanism; HORMAD2 knockout eliminates asynaptic Spo11−/− oocytes but not DSB-repair-defective Dmc1−/− oocytes, demonstrating that asynapsis surveillance and DSB surveillance are mechanistically distinct.","method":"Hormad2 knockout mouse generation; immunofluorescence for ATR on meiotic chromosomes; genetic epistasis using Spo11−/− and Dmc1−/− double mutants; oocyte counting","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean KO with defined cellular phenotype, genetic epistasis with two double-mutant backgrounds, independently replicated by Kogo et al. 2012 (PMID 23039116)","pmids":["22549958"],"is_preprint":false},{"year":2012,"finding":"HORMAD2 deficiency impairs proper recruitment of ATR activity to unsynapsed chromosomes; in males, loss of HORMAD2 causes partial dissociation of the sex body (ATR- and γH2AX-enriched domain) from elongated sex chromosome axes leading to spermatocyte loss; in females, HORMAD2-dependent pseudo-sex body formation (likely via local ATR concentration) drives elimination of asynaptic Spo11-deficient oocytes.","method":"Hormad2 knockout mouse; immunofluorescence for ATR, γH2AX, SYCP1, SYCP3; Hormad2/Spo11 double-mutant analysis; oocyte counting in a gene-dosage series","journal":"Genes to cells : devoted to molecular & cellular mechanisms","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean KO with sex-specific phenotypic readouts, gene-dosage series, and genetic epistasis; independently consistent with Wojtasz et al. 2012 (PMID 22549958)","pmids":["23039116"],"is_preprint":false},{"year":2012,"finding":"HORMAD2 is post-translationally phosphorylated during meiotic prophase I; phosphorylation of HORMAD2 depends on BRCA1 and SYCP3 for normal levels, and is dramatically reduced in the absence of meiotic recombination initiation; reduced HORMAD2 phosphorylation is associated with impaired targeting of the MSUC (meiotic silencing of unsynapsed chromatin) machinery to unsynapsed chromosomes.","method":"Western blot and immunofluorescence with phospho-specific analysis; genetic requirement tested in Spo11, BRCA1, and SYCP3 mutant spermatocytes","journal":"PLoS genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple mutant backgrounds tested, but single lab and phosphorylation site identity not fully resolved in abstract","pmids":["22346761"],"is_preprint":false},{"year":2014,"finding":"Mammalian HORMAD1 binds a cognate peptide motif found at the C-terminus of HORMAD2, indicating that HORMAD2 is recruited to the chromosome axis via a 'safety-belt' HORMA domain–closure motif interaction conserved from C. elegans to mammals.","method":"Biochemical binding assays (pulldown); structural analysis of C. elegans orthologs; sequence analysis identifying conserved closure motif in HORMAD2 C-terminus","journal":"Developmental cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct biochemical binding demonstrated and structurally rationalized, but mammalian interaction validated biochemically in a single study","pmids":["25446517"],"is_preprint":false},{"year":2017,"finding":"HORMAD1/2 on unsynapsed chromosome axes inhibit repair of spontaneous DSBs by intersister recombination; when a threshold (~10) of late-prophase spontaneous DSBs accumulates on unsynapsed axes bearing HORMAD1/2, the CHK2-dependent DNA damage checkpoint is triggered to eliminate oocytes; Hormad2 deletion rescued fertility of Trip13-mutant females (which cannot remove HORMADs from synapsed chromosomes), establishing that HORMAD2 is epistatic to TRIP13 in this checkpoint pathway.","method":"Genetic epistasis: Hormad2 deletion in Trip13 hypomorphic females; oocyte counting; immunofluorescence for DSB markers; CHK2 pathway analysis","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean genetic rescue (Hormad2 deletion rescues Trip13 mutant fertility), multiple orthogonal readouts, mechanistically places HORMAD2 downstream of TRIP13 and upstream of CHK2-dependent checkpoint","pmids":["28844861"],"is_preprint":false},{"year":2019,"finding":"Using expansion microscopy coupled with 2-color STORM (ExSTORM) at 10–20 nm resolution in mouse spermatocytes, HORMAD2 was shown to be arrayed around the SYCP3/SYCP2 C-terminus filament core of the meiotic chromosome axis, positioned peripherally relative to the compact axial core.","method":"Expansion microscopy + 2-color STORM (ExSTORM) super-resolution imaging of mouse spermatocytes","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct super-resolution structural localization, single lab, no functional mutagenesis","pmids":["31444302"],"is_preprint":false},{"year":2020,"finding":"TRIP13 pathogenic variants reduce TRIP13 protein abundance and cause HORMAD2 to accumulate (fail to be removed) in HeLa cells and patient-derived lymphoblastoid cells, establishing that TRIP13 enzymatic activity is required for HORMAD2 disassembly in a human cellular context.","method":"In vitro cell assays (HeLa overexpression); patient-derived lymphoblastoid cells; western blot for HORMAD2 levels","journal":"American journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional consequence (HORMAD2 accumulation) demonstrated in two cellular systems with patient variants, single lab","pmids":["32473092"],"is_preprint":false},{"year":2022,"finding":"RAD1 (shared subunit of all 9-1-1 complexes) is required for phosphorylation of HORMAD2 as an ATR target during meiosis; testis-specific Rad1 disruption impaired HORMAD2 phosphorylation along with other ATR targets (H2AX, CHK1), placing 9-1-1 complexes upstream of ATR-mediated HORMAD2 modification.","method":"Testis-specific Rad1 knockout mice; immunofluorescence and western blot for phospho-HORMAD2 and other ATR targets on meiotic chromosomes","journal":"eLife","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean conditional KO with direct phosphorylation readout, single lab","pmids":["35133274"],"is_preprint":false},{"year":2022,"finding":"In Prdm9-deficient rat oocytes, non-homologous synapsis (NHS) is accompanied by HORMAD2 levels similar to those on pachytene chromosomes with homologous synapsis; this indicates that NHS bypasses the HORMAD2-based asynapsis signal and allows oocytes to evade meiotic checkpoints, linking HORMAD2 checkpoint evasion to subsequent aneuploidy.","method":"Immunofluorescence for HORMAD2 on rat oocyte chromosome spreads; comparison between homologous-synapsed and non-homologously-synapsed pachytene chromosomes in Prdm9-deficient animals","journal":"Mammalian genome","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct HORMAD2 protein quantification on individual chromosomes, single lab, no functional rescue","pmids":["35596034"],"is_preprint":false},{"year":2023,"finding":"The crystal structure of human HORMAD1 reveals a self-closed conformation via intramolecular HORMA domain–closure motif interaction; structural and biochemical data show that a peptide from HORMAD2 binds HORMAD1 in the same mode as HORMAD1's own closure motif, with both sharing a conserved Ser-Glu-Pro sequence; this HORMAD1–HORMAD2 interaction contributes to HORMAD1-dependent homologous recombination repair in cell-based assays.","method":"X-ray crystallography of human HORMAD1; peptide-binding biochemical assays; cell-based HR repair reporter assays","journal":"Structure (London, England : 1993)","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure plus biochemical binding assays plus functional cell assays in a single study; rigorous multi-method approach","pmids":["37794593"],"is_preprint":false},{"year":2024,"finding":"N-terminal tagging (3×FLAG-HA) of HORMAD2 prevents its timely removal from synapsed chromosome axes by TRIP13; co-immunoprecipitation coupled with mass spectrometry identified HORMAD1 and SYCP2 as HORMAD2-associated proteins in the testis; super-resolution microscopy showed that N-terminally tagged HORMAD2 redistributes to the central region of the synaptonemal complex rather than the lateral elements, without blocking meiosis but reducing sperm count in males.","method":"N-terminal knock-in tagging in mice; co-IP + mass spectrometry; super-resolution microscopy; fertility and sperm count assays","journal":"Reproduction (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — endogenous tagging with multiple orthogonal methods (Co-IP/MS for interactors, super-resolution for localization, in vivo fertility phenotype); single lab","pmids":["38401263"],"is_preprint":false},{"year":2025,"finding":"When HORMAD1 and HORMAD2 are retained on synapsed chromosome axes (in TRIP13-deficient contexts), they recruit BRCA1 and activate the chromosome asynapsis checkpoint, triggering oocyte elimination; mechanistically, HORMAD1 co-immunoprecipitates with BRCA1 via an interface on its HORMA domain near the N-terminus (not through the canonical closure-motif binding mode), while HORMAD2 co-immunoprecipitates with BRCA1 weakly but also contributes to BRCA1 recruitment; N-terminal tagging of HORMAD1/2 retains them on synapsed axes but abolishes BRCA1 recruitment and oocyte elimination, confirming the N-terminal interface is required.","method":"Co-immunoprecipitation; N-terminal-tagged HORMAD knock-in mice; immunofluorescence for BRCA1 on meiotic chromosomes; oocyte counting in multiple genetic backgrounds","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, endogenous tagging rescue experiment, multiple genetic backgrounds, direct functional phenotype; single lab but multiple orthogonal methods","pmids":["40050306"],"is_preprint":false},{"year":2025,"finding":"Using a squash immunohistochemical method for perinatal mouse ovaries, asynapsis-induced oocyte apoptosis (but not DNA damage-induced apoptosis) was shown to be significantly dependent on HORMAD2 in double-mutant analysis, confirming HORMAD2's specific role in the asynapsis surveillance pathway distinct from the DNA damage checkpoint.","method":"Squash immunohistochemistry; double-mutant analysis (Hormad2 × Spo11 and Hormad2 × Dmc1); apoptosis kinetics measurement in perinatal ovaries","journal":"Histochemistry and cell biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis with two double-mutant backgrounds, direct apoptosis readout; consistent with prior work but single recent lab","pmids":["39961811"],"is_preprint":false}],"current_model":"HORMAD2 is a meiosis-specific HORMA-domain protein that localizes to unsynapsed chromosome axes via a safety-belt closure-motif interaction with HORMAD1 (and associated with SYCP2), where it recruits ATR kinase activity (facilitated by 9-1-1 complexes and BRCA1) to establish a distinct asynapsis surveillance checkpoint; upon synapsis, TRIP13 AAA-ATPase engages HORMAD2's N-terminal region to remove it from axes, and failure to remove HORMAD2 aberrantly activates BRCA1-dependent checkpoint signaling to eliminate oocytes, while HORMAD2 phosphorylation by ATM/ATR serves as an axis mark coupled to the MSUC machinery."},"narrative":{"mechanistic_narrative":"HORMAD2 is a meiosis-specific HORMA-domain protein that marks unsynapsed chromosome axes and operates the asynapsis surveillance checkpoint that eliminates oocytes and spermatocytes failing to complete homologous synapsis [PMID:22549958, PMID:23039116]. It preferentially decorates unsynapsed axes throughout meiotic prophase and is removed from axes upon synapsis [PMID:19851446], being recruited to the axis via a conserved 'safety-belt' interaction in which its C-terminal closure motif (sharing a Ser-Glu-Pro sequence) docks into the HORMA domain of HORMAD1 [PMID:25446517, PMID:37794593]; HORMAD1 and SYCP2 are its principal axis-associated partners, positioning it peripherally around the SYCP3/SYCP2 axial core [PMID:31444302, PMID:38401263]. On unsynapsed axes HORMAD2 is required for the local accumulation of ATR kinase activity that builds the surveillance signal, a function genetically separable from the DSB-repair checkpoint [PMID:22549958, PMID:23039116, PMID:39961811]. HORMAD2 is itself phosphorylated during prophase I as an ATR target, dependent on the 9-1-1 subunit RAD1 and on BRCA1/SYCP3, coupling it to the meiotic silencing of unsynapsed chromatin (MSUC) machinery [PMID:22346761, PMID:35133274]. Synapsis-coupled removal of HORMAD2 is driven by the TRIP13 AAA-ATPase acting on its N-terminal region [PMID:19851446, PMID:32473092, PMID:38401263]; when removal fails, retained HORMAD2 (with HORMAD1) aberrantly recruits BRCA1 through an N-terminal HORMA-domain interface and activates the checkpoint to eliminate oocytes, and Hormad2 deletion is epistatic to Trip13, rescuing Trip13-mutant fertility [PMID:28844861, PMID:40050306].","teleology":[{"year":2009,"claim":"Established that HORMAD2 is an unsynapsed-axis marker whose distribution is reciprocal to synaptonemal complex components and is controlled by TRIP13, framing it as a dynamic axis component rather than a static structural protein.","evidence":"Immunofluorescence in wild-type and TRIP13-deficient/DSB-processing-mutant mouse meiocytes with SC co-localization","pmids":["19851446"],"confidence":"High","gaps":["Did not define the molecular basis of axis recruitment","Did not establish a functional consequence of HORMAD2 presence"]},{"year":2012,"claim":"Defined HORMAD2's core function: recruiting ATR activity to unsynapsed axes to drive an asynapsis surveillance checkpoint mechanistically distinct from DSB surveillance, with sex-specific consequences for germ cell elimination.","evidence":"Hormad2 knockout mice; ATR/γH2AX/SYCP immunofluorescence; epistasis with Spo11−/− and Dmc1−/−; gene-dosage oocyte counting","pmids":["22549958","23039116"],"confidence":"High","gaps":["Did not identify how HORMAD2 physically recruits ATR","Did not resolve the downstream effector causing germ cell death"]},{"year":2012,"claim":"Linked HORMAD2 to the MSUC silencing pathway by showing it is phosphorylated in prophase I in a BRCA1/SYCP3- and recombination-initiation-dependent manner.","evidence":"Phospho-specific western blot/IF in Spo11, BRCA1, and SYCP3 mutant spermatocytes","pmids":["22346761"],"confidence":"Medium","gaps":["Phosphorylation site identity not fully resolved","Direct kinase responsible not established in this study","Causal role of the phosphorylation in MSUC not tested by mutagenesis"]},{"year":2014,"claim":"Provided the molecular mechanism of axis recruitment by demonstrating a conserved HORMA domain–closure motif 'safety-belt' interaction between HORMAD1 and HORMAD2's C-terminus.","evidence":"Biochemical pulldowns, sequence analysis, and structural data from C. elegans orthologs","pmids":["25446517"],"confidence":"Medium","gaps":["Mammalian interaction validated biochemically in a single study","No structure of the mammalian complex"]},{"year":2017,"claim":"Placed HORMAD2 in a defined checkpoint hierarchy — downstream of TRIP13 and upstream of CHK2 — by showing Hormad2 deletion rescues Trip13-mutant female fertility and that HORMAD1/2 on unsynapsed axes trigger CHK2-dependent oocyte elimination above a DSB threshold.","evidence":"Genetic epistasis (Hormad2 deletion in Trip13 hypomorph), oocyte counting, DSB-marker IF, CHK2 pathway analysis","pmids":["28844861"],"confidence":"High","gaps":["Did not define the molecular link between retained HORMAD and checkpoint kinase activation","Did not resolve the intersister recombination inhibition mechanism"]},{"year":2019,"claim":"Resolved the nanoscale architecture of HORMAD2 on the axis, showing it is arrayed peripherally around the compact SYCP3/SYCP2 axial core.","evidence":"Expansion microscopy + 2-color STORM (ExSTORM) at 10–20 nm resolution in mouse spermatocytes","pmids":["31444302"],"confidence":"Medium","gaps":["No functional mutagenesis tied to the positioning","Single lab structural observation"]},{"year":2020,"claim":"Extended TRIP13-dependent HORMAD2 disassembly to human cells, showing pathogenic TRIP13 variants reduce TRIP13 abundance and cause HORMAD2 to accumulate.","evidence":"HeLa overexpression and patient-derived lymphoblastoid cells; western blot for HORMAD2","pmids":["32473092"],"confidence":"Medium","gaps":["Cellular context is not meiotic","Direct enzymatic action of TRIP13 on HORMAD2 not reconstituted here"]},{"year":2022,"claim":"Positioned the 9-1-1 complex upstream of HORMAD2 modification by showing RAD1 is required for HORMAD2 phosphorylation as an ATR target during meiosis.","evidence":"Testis-specific Rad1 knockout mice; phospho-HORMAD2 and ATR-target IF/western blot","pmids":["35133274"],"confidence":"Medium","gaps":["Direct biochemical phosphorylation not shown","Phosphosite still undefined","Single lab"]},{"year":2022,"claim":"Connected HORMAD2 checkpoint signaling to aneuploidy risk by showing non-homologous synapsis maintains pachytene-like HORMAD2 levels and thereby evades the asynapsis checkpoint.","evidence":"HORMAD2 IF quantification on Prdm9-deficient rat oocyte chromosome spreads","pmids":["35596034"],"confidence":"Medium","gaps":["Correlative protein quantification without functional rescue","Mechanism of checkpoint evasion not directly tested"]},{"year":2023,"claim":"Provided high-resolution structural confirmation that human HORMAD2 binds HORMAD1's HORMA domain via a shared Ser-Glu-Pro closure motif, and tied this interaction to HR repair function.","evidence":"X-ray crystallography of human HORMAD1, peptide-binding assays, cell-based HR repair reporter","pmids":["37794593"],"confidence":"High","gaps":["HR repair assay performed in non-meiotic cell context","No structure of full-length HORMAD2"]},{"year":2024,"claim":"Identified HORMAD2's in vivo interactors and showed its N-terminus is required for TRIP13-mediated removal, with mislocalization to the SC central region upon N-terminal tagging.","evidence":"N-terminal knock-in tagging in mice; Co-IP/mass spectrometry; super-resolution microscopy; fertility and sperm count","pmids":["38401263"],"confidence":"High","gaps":["Did not map the precise TRIP13 engagement residues","Reduced sperm count mechanism not fully resolved"]},{"year":2025,"claim":"Defined the effector mechanism of the retained-HORMAD checkpoint: HORMAD2 (with HORMAD1) recruits BRCA1 via an N-terminal HORMA-domain interface to trigger oocyte elimination, and confirmed HORMAD2's apoptotic role is specific to asynapsis surveillance.","evidence":"Reciprocal Co-IP; N-terminal-tagged HORMAD knock-in mice; BRCA1 IF; oocyte counting; squash immunohistochemistry with Spo11/Dmc1 double mutants","pmids":["40050306","39961811"],"confidence":"High","gaps":["HORMAD2 contributes to but binds BRCA1 only weakly — relative contribution vs HORMAD1 not quantified","Downstream apoptotic execution steps not detailed"]},{"year":null,"claim":"How HORMAD2 phosphorylation, its peripheral axial positioning, and the N-terminal BRCA1/TRIP13 interface are mechanistically integrated to convert an unsynapsed axis into a committed elimination signal remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["HORMAD2 phosphosite identity and its functional requirement remain undefined","Direct biochemical reconstitution of TRIP13-mediated HORMAD2 removal is lacking","The precise structural interface and quantitative contribution of HORMAD2 to BRCA1 recruitment is unresolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[1,2,12]}],"localization":[{"term_id":"GO:0005694","term_label":"chromosome","supporting_discovery_ids":[0,6,11]},{"term_id":"GO:0000228","term_label":"nuclear chromosome","supporting_discovery_ids":[0,6]}],"pathway":[{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[1,2,5]},{"term_id":"R-HSA-8953897","term_label":"Cellular responses to stimuli","supporting_discovery_ids":[1,2,13]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[5,12,13]}],"complexes":["synaptonemal complex axis / lateral element"],"partners":["HORMAD1","SYCP2","SYCP3","TRIP13","BRCA1","ATR","RAD1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q8N7B1","full_name":"HORMA domain-containing protein 2","aliases":[],"length_aa":307,"mass_kda":35.3,"function":"Essential for synapsis surveillance during meiotic prophase via the recruitment of ATR activity. Plays a key role in the male mid-pachytene checkpoint and the female meiotic prophase checkpoint: required for efficient build-up of ATR activity on unsynapsed chromosome regions, a process believed to form the basis of meiotic silencing of unsynapsed chromatin (MSUC) and meiotic prophase quality control in both sexes. Required for the DNA double-strand break-independent, BRCA1-dependent activation of ATR on the sex chromosomes that is essential for normal sex body formation (By similarity)","subcellular_location":"Nucleus; Chromosome","url":"https://www.uniprot.org/uniprotkb/Q8N7B1/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/HORMAD2","classification":"Not Classified","n_dependent_lines":6,"n_total_lines":1208,"dependency_fraction":0.004966887417218543},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/HORMAD2","total_profiled":1310},"omim":[{"mim_id":"618842","title":"HORMA DOMAIN-CONTAINING PROTEIN 2; HORMAD2","url":"https://www.omim.org/entry/618842"},{"mim_id":"609824","title":"HORMA DOMAIN-CONTAINING PROTEIN 1; HORMAD1","url":"https://www.omim.org/entry/609824"},{"mim_id":"604507","title":"THYROID HORMONE RECEPTOR INTERACTOR 13; TRIP13","url":"https://www.omim.org/entry/604507"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Centrosome","reliability":"Additional"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"testis","ntpm":21.3}],"url":"https://www.proteinatlas.org/search/HORMAD2"},"hgnc":{"alias_symbol":["MGC26710","CT46.2"],"prev_symbol":[]},"alphafold":{"accession":"Q8N7B1","domains":[{"cath_id":"3.30.900.10","chopping":"29-130_150-252_295-299","consensus_level":"high","plddt":85.581,"start":29,"end":299}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8N7B1","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8N7B1-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8N7B1-F1-predicted_aligned_error_v6.png","plddt_mean":72.0},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=HORMAD2","jax_strain_url":"https://www.jax.org/strain/search?query=HORMAD2"},"sequence":{"accession":"Q8N7B1","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8N7B1.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8N7B1/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8N7B1"}},"corpus_meta":[{"pmid":"19851446","id":"PMC_19851446","title":"Mouse HORMAD1 and HORMAD2, two conserved meiotic chromosomal proteins, are depleted from synapsed chromosome axes with the help of TRIP13 AAA-ATPase.","date":"2009","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/19851446","citation_count":333,"is_preprint":false},{"pmid":"22549958","id":"PMC_22549958","title":"Meiotic DNA double-strand breaks and chromosome asynapsis in mice are monitored by distinct HORMAD2-independent and -dependent mechanisms.","date":"2012","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/22549958","citation_count":122,"is_preprint":false},{"pmid":"23072577","id":"PMC_23072577","title":"Pathogenesis of immunoglobulin A nephropathy: recent insight from genetic studies.","date":"2012","source":"Annual review of medicine","url":"https://pubmed.ncbi.nlm.nih.gov/23072577","citation_count":107,"is_preprint":false},{"pmid":"25446517","id":"PMC_25446517","title":"The chromosome axis controls meiotic events through a hierarchical assembly of HORMA domain proteins.","date":"2014","source":"Developmental cell","url":"https://pubmed.ncbi.nlm.nih.gov/25446517","citation_count":105,"is_preprint":false},{"pmid":"32473092","id":"PMC_32473092","title":"Bi-allelic Missense Pathogenic Variants in TRIP13 Cause Female Infertility Characterized by Oocyte Maturation Arrest.","date":"2020","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/32473092","citation_count":102,"is_preprint":false},{"pmid":"28844861","id":"PMC_28844861","title":"The DNA Damage Checkpoint Eliminates Mouse Oocytes with Chromosome Synapsis Failure.","date":"2017","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/28844861","citation_count":101,"is_preprint":false},{"pmid":"31444302","id":"PMC_31444302","title":"Molecular organization of mammalian meiotic chromosome axis revealed by expansion STORM microscopy.","date":"2019","source":"Proceedings of the National Academy of Sciences of the United States of 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chromosome axes throughout meiotic prophase and is depleted from synapsed axes; TRIP13 AAA-ATPase is required for the reciprocal distribution of HORMADs and SYCP1/SC-component along chromosome axes, indicating TRIP13 promotes HORMAD2 removal from synapsed chromatin.\",\n      \"method\": \"Immunofluorescence analysis of wild-type and mutant (TRIP13-deficient, DSB-processing mutant) mouse spermatocytes/oocytes; co-localization with SC markers\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct localization experiments with functional consequence in defined genetic mutants, replicated across multiple mutant backgrounds by the same study and corroborated by subsequent independent labs\",\n      \"pmids\": [\"19851446\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"HORMAD2 is required for accumulation of the checkpoint kinase ATR along unsynapsed chromosome axes (but not at DNA DSBs or DSB-associated chromatin loops), and this HORMAD2-dependent ATR recruitment constitutes a distinct asynapsis surveillance mechanism; HORMAD2 knockout eliminates asynaptic Spo11−/− oocytes but not DSB-repair-defective Dmc1−/− oocytes, demonstrating that asynapsis surveillance and DSB surveillance are mechanistically distinct.\",\n      \"method\": \"Hormad2 knockout mouse generation; immunofluorescence for ATR on meiotic chromosomes; genetic epistasis using Spo11−/− and Dmc1−/− double mutants; oocyte counting\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean KO with defined cellular phenotype, genetic epistasis with two double-mutant backgrounds, independently replicated by Kogo et al. 2012 (PMID 23039116)\",\n      \"pmids\": [\"22549958\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"HORMAD2 deficiency impairs proper recruitment of ATR activity to unsynapsed chromosomes; in males, loss of HORMAD2 causes partial dissociation of the sex body (ATR- and γH2AX-enriched domain) from elongated sex chromosome axes leading to spermatocyte loss; in females, HORMAD2-dependent pseudo-sex body formation (likely via local ATR concentration) drives elimination of asynaptic Spo11-deficient oocytes.\",\n      \"method\": \"Hormad2 knockout mouse; immunofluorescence for ATR, γH2AX, SYCP1, SYCP3; Hormad2/Spo11 double-mutant analysis; oocyte counting in a gene-dosage series\",\n      \"journal\": \"Genes to cells : devoted to molecular & cellular mechanisms\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean KO with sex-specific phenotypic readouts, gene-dosage series, and genetic epistasis; independently consistent with Wojtasz et al. 2012 (PMID 22549958)\",\n      \"pmids\": [\"23039116\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"HORMAD2 is post-translationally phosphorylated during meiotic prophase I; phosphorylation of HORMAD2 depends on BRCA1 and SYCP3 for normal levels, and is dramatically reduced in the absence of meiotic recombination initiation; reduced HORMAD2 phosphorylation is associated with impaired targeting of the MSUC (meiotic silencing of unsynapsed chromatin) machinery to unsynapsed chromosomes.\",\n      \"method\": \"Western blot and immunofluorescence with phospho-specific analysis; genetic requirement tested in Spo11, BRCA1, and SYCP3 mutant spermatocytes\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple mutant backgrounds tested, but single lab and phosphorylation site identity not fully resolved in abstract\",\n      \"pmids\": [\"22346761\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Mammalian HORMAD1 binds a cognate peptide motif found at the C-terminus of HORMAD2, indicating that HORMAD2 is recruited to the chromosome axis via a 'safety-belt' HORMA domain–closure motif interaction conserved from C. elegans to mammals.\",\n      \"method\": \"Biochemical binding assays (pulldown); structural analysis of C. elegans orthologs; sequence analysis identifying conserved closure motif in HORMAD2 C-terminus\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct biochemical binding demonstrated and structurally rationalized, but mammalian interaction validated biochemically in a single study\",\n      \"pmids\": [\"25446517\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"HORMAD1/2 on unsynapsed chromosome axes inhibit repair of spontaneous DSBs by intersister recombination; when a threshold (~10) of late-prophase spontaneous DSBs accumulates on unsynapsed axes bearing HORMAD1/2, the CHK2-dependent DNA damage checkpoint is triggered to eliminate oocytes; Hormad2 deletion rescued fertility of Trip13-mutant females (which cannot remove HORMADs from synapsed chromosomes), establishing that HORMAD2 is epistatic to TRIP13 in this checkpoint pathway.\",\n      \"method\": \"Genetic epistasis: Hormad2 deletion in Trip13 hypomorphic females; oocyte counting; immunofluorescence for DSB markers; CHK2 pathway analysis\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean genetic rescue (Hormad2 deletion rescues Trip13 mutant fertility), multiple orthogonal readouts, mechanistically places HORMAD2 downstream of TRIP13 and upstream of CHK2-dependent checkpoint\",\n      \"pmids\": [\"28844861\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Using expansion microscopy coupled with 2-color STORM (ExSTORM) at 10–20 nm resolution in mouse spermatocytes, HORMAD2 was shown to be arrayed around the SYCP3/SYCP2 C-terminus filament core of the meiotic chromosome axis, positioned peripherally relative to the compact axial core.\",\n      \"method\": \"Expansion microscopy + 2-color STORM (ExSTORM) super-resolution imaging of mouse spermatocytes\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct super-resolution structural localization, single lab, no functional mutagenesis\",\n      \"pmids\": [\"31444302\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"TRIP13 pathogenic variants reduce TRIP13 protein abundance and cause HORMAD2 to accumulate (fail to be removed) in HeLa cells and patient-derived lymphoblastoid cells, establishing that TRIP13 enzymatic activity is required for HORMAD2 disassembly in a human cellular context.\",\n      \"method\": \"In vitro cell assays (HeLa overexpression); patient-derived lymphoblastoid cells; western blot for HORMAD2 levels\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional consequence (HORMAD2 accumulation) demonstrated in two cellular systems with patient variants, single lab\",\n      \"pmids\": [\"32473092\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"RAD1 (shared subunit of all 9-1-1 complexes) is required for phosphorylation of HORMAD2 as an ATR target during meiosis; testis-specific Rad1 disruption impaired HORMAD2 phosphorylation along with other ATR targets (H2AX, CHK1), placing 9-1-1 complexes upstream of ATR-mediated HORMAD2 modification.\",\n      \"method\": \"Testis-specific Rad1 knockout mice; immunofluorescence and western blot for phospho-HORMAD2 and other ATR targets on meiotic chromosomes\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean conditional KO with direct phosphorylation readout, single lab\",\n      \"pmids\": [\"35133274\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"In Prdm9-deficient rat oocytes, non-homologous synapsis (NHS) is accompanied by HORMAD2 levels similar to those on pachytene chromosomes with homologous synapsis; this indicates that NHS bypasses the HORMAD2-based asynapsis signal and allows oocytes to evade meiotic checkpoints, linking HORMAD2 checkpoint evasion to subsequent aneuploidy.\",\n      \"method\": \"Immunofluorescence for HORMAD2 on rat oocyte chromosome spreads; comparison between homologous-synapsed and non-homologously-synapsed pachytene chromosomes in Prdm9-deficient animals\",\n      \"journal\": \"Mammalian genome\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct HORMAD2 protein quantification on individual chromosomes, single lab, no functional rescue\",\n      \"pmids\": [\"35596034\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"The crystal structure of human HORMAD1 reveals a self-closed conformation via intramolecular HORMA domain–closure motif interaction; structural and biochemical data show that a peptide from HORMAD2 binds HORMAD1 in the same mode as HORMAD1's own closure motif, with both sharing a conserved Ser-Glu-Pro sequence; this HORMAD1–HORMAD2 interaction contributes to HORMAD1-dependent homologous recombination repair in cell-based assays.\",\n      \"method\": \"X-ray crystallography of human HORMAD1; peptide-binding biochemical assays; cell-based HR repair reporter assays\",\n      \"journal\": \"Structure (London, England : 1993)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure plus biochemical binding assays plus functional cell assays in a single study; rigorous multi-method approach\",\n      \"pmids\": [\"37794593\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"N-terminal tagging (3×FLAG-HA) of HORMAD2 prevents its timely removal from synapsed chromosome axes by TRIP13; co-immunoprecipitation coupled with mass spectrometry identified HORMAD1 and SYCP2 as HORMAD2-associated proteins in the testis; super-resolution microscopy showed that N-terminally tagged HORMAD2 redistributes to the central region of the synaptonemal complex rather than the lateral elements, without blocking meiosis but reducing sperm count in males.\",\n      \"method\": \"N-terminal knock-in tagging in mice; co-IP + mass spectrometry; super-resolution microscopy; fertility and sperm count assays\",\n      \"journal\": \"Reproduction (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — endogenous tagging with multiple orthogonal methods (Co-IP/MS for interactors, super-resolution for localization, in vivo fertility phenotype); single lab\",\n      \"pmids\": [\"38401263\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"When HORMAD1 and HORMAD2 are retained on synapsed chromosome axes (in TRIP13-deficient contexts), they recruit BRCA1 and activate the chromosome asynapsis checkpoint, triggering oocyte elimination; mechanistically, HORMAD1 co-immunoprecipitates with BRCA1 via an interface on its HORMA domain near the N-terminus (not through the canonical closure-motif binding mode), while HORMAD2 co-immunoprecipitates with BRCA1 weakly but also contributes to BRCA1 recruitment; N-terminal tagging of HORMAD1/2 retains them on synapsed axes but abolishes BRCA1 recruitment and oocyte elimination, confirming the N-terminal interface is required.\",\n      \"method\": \"Co-immunoprecipitation; N-terminal-tagged HORMAD knock-in mice; immunofluorescence for BRCA1 on meiotic chromosomes; oocyte counting in multiple genetic backgrounds\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, endogenous tagging rescue experiment, multiple genetic backgrounds, direct functional phenotype; single lab but multiple orthogonal methods\",\n      \"pmids\": [\"40050306\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Using a squash immunohistochemical method for perinatal mouse ovaries, asynapsis-induced oocyte apoptosis (but not DNA damage-induced apoptosis) was shown to be significantly dependent on HORMAD2 in double-mutant analysis, confirming HORMAD2's specific role in the asynapsis surveillance pathway distinct from the DNA damage checkpoint.\",\n      \"method\": \"Squash immunohistochemistry; double-mutant analysis (Hormad2 × Spo11 and Hormad2 × Dmc1); apoptosis kinetics measurement in perinatal ovaries\",\n      \"journal\": \"Histochemistry and cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis with two double-mutant backgrounds, direct apoptosis readout; consistent with prior work but single recent lab\",\n      \"pmids\": [\"39961811\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"HORMAD2 is a meiosis-specific HORMA-domain protein that localizes to unsynapsed chromosome axes via a safety-belt closure-motif interaction with HORMAD1 (and associated with SYCP2), where it recruits ATR kinase activity (facilitated by 9-1-1 complexes and BRCA1) to establish a distinct asynapsis surveillance checkpoint; upon synapsis, TRIP13 AAA-ATPase engages HORMAD2's N-terminal region to remove it from axes, and failure to remove HORMAD2 aberrantly activates BRCA1-dependent checkpoint signaling to eliminate oocytes, while HORMAD2 phosphorylation by ATM/ATR serves as an axis mark coupled to the MSUC machinery.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"HORMAD2 is a meiosis-specific HORMA-domain protein that marks unsynapsed chromosome axes and operates the asynapsis surveillance checkpoint that eliminates oocytes and spermatocytes failing to complete homologous synapsis [#1, #2]. It preferentially decorates unsynapsed axes throughout meiotic prophase and is removed from axes upon synapsis [#0], being recruited to the axis via a conserved 'safety-belt' interaction in which its C-terminal closure motif (sharing a Ser-Glu-Pro sequence) docks into the HORMA domain of HORMAD1 [#4, #10]; HORMAD1 and SYCP2 are its principal axis-associated partners, positioning it peripherally around the SYCP3/SYCP2 axial core [#6, #11]. On unsynapsed axes HORMAD2 is required for the local accumulation of ATR kinase activity that builds the surveillance signal, a function genetically separable from the DSB-repair checkpoint [#1, #2, #13]. HORMAD2 is itself phosphorylated during prophase I as an ATR target, dependent on the 9-1-1 subunit RAD1 and on BRCA1/SYCP3, coupling it to the meiotic silencing of unsynapsed chromatin (MSUC) machinery [#3, #8]. Synapsis-coupled removal of HORMAD2 is driven by the TRIP13 AAA-ATPase acting on its N-terminal region [#0, #7, #11]; when removal fails, retained HORMAD2 (with HORMAD1) aberrantly recruits BRCA1 through an N-terminal HORMA-domain interface and activates the checkpoint to eliminate oocytes, and Hormad2 deletion is epistatic to Trip13, rescuing Trip13-mutant fertility [#5, #12].\",\n  \"teleology\": [\n    {\n      \"year\": 2009,\n      \"claim\": \"Established that HORMAD2 is an unsynapsed-axis marker whose distribution is reciprocal to synaptonemal complex components and is controlled by TRIP13, framing it as a dynamic axis component rather than a static structural protein.\",\n      \"evidence\": \"Immunofluorescence in wild-type and TRIP13-deficient/DSB-processing-mutant mouse meiocytes with SC co-localization\",\n      \"pmids\": [\"19851446\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define the molecular basis of axis recruitment\", \"Did not establish a functional consequence of HORMAD2 presence\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Defined HORMAD2's core function: recruiting ATR activity to unsynapsed axes to drive an asynapsis surveillance checkpoint mechanistically distinct from DSB surveillance, with sex-specific consequences for germ cell elimination.\",\n      \"evidence\": \"Hormad2 knockout mice; ATR/\\u03b3H2AX/SYCP immunofluorescence; epistasis with Spo11\\u2212/\\u2212 and Dmc1\\u2212/\\u2212; gene-dosage oocyte counting\",\n      \"pmids\": [\"22549958\", \"23039116\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify how HORMAD2 physically recruits ATR\", \"Did not resolve the downstream effector causing germ cell death\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Linked HORMAD2 to the MSUC silencing pathway by showing it is phosphorylated in prophase I in a BRCA1/SYCP3- and recombination-initiation-dependent manner.\",\n      \"evidence\": \"Phospho-specific western blot/IF in Spo11, BRCA1, and SYCP3 mutant spermatocytes\",\n      \"pmids\": [\"22346761\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Phosphorylation site identity not fully resolved\", \"Direct kinase responsible not established in this study\", \"Causal role of the phosphorylation in MSUC not tested by mutagenesis\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Provided the molecular mechanism of axis recruitment by demonstrating a conserved HORMA domain\\u2013closure motif 'safety-belt' interaction between HORMAD1 and HORMAD2's C-terminus.\",\n      \"evidence\": \"Biochemical pulldowns, sequence analysis, and structural data from C. elegans orthologs\",\n      \"pmids\": [\"25446517\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mammalian interaction validated biochemically in a single study\", \"No structure of the mammalian complex\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Placed HORMAD2 in a defined checkpoint hierarchy \\u2014 downstream of TRIP13 and upstream of CHK2 \\u2014 by showing Hormad2 deletion rescues Trip13-mutant female fertility and that HORMAD1/2 on unsynapsed axes trigger CHK2-dependent oocyte elimination above a DSB threshold.\",\n      \"evidence\": \"Genetic epistasis (Hormad2 deletion in Trip13 hypomorph), oocyte counting, DSB-marker IF, CHK2 pathway analysis\",\n      \"pmids\": [\"28844861\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define the molecular link between retained HORMAD and checkpoint kinase activation\", \"Did not resolve the intersister recombination inhibition mechanism\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Resolved the nanoscale architecture of HORMAD2 on the axis, showing it is arrayed peripherally around the compact SYCP3/SYCP2 axial core.\",\n      \"evidence\": \"Expansion microscopy + 2-color STORM (ExSTORM) at 10\\u201320 nm resolution in mouse spermatocytes\",\n      \"pmids\": [\"31444302\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No functional mutagenesis tied to the positioning\", \"Single lab structural observation\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Extended TRIP13-dependent HORMAD2 disassembly to human cells, showing pathogenic TRIP13 variants reduce TRIP13 abundance and cause HORMAD2 to accumulate.\",\n      \"evidence\": \"HeLa overexpression and patient-derived lymphoblastoid cells; western blot for HORMAD2\",\n      \"pmids\": [\"32473092\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Cellular context is not meiotic\", \"Direct enzymatic action of TRIP13 on HORMAD2 not reconstituted here\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Positioned the 9-1-1 complex upstream of HORMAD2 modification by showing RAD1 is required for HORMAD2 phosphorylation as an ATR target during meiosis.\",\n      \"evidence\": \"Testis-specific Rad1 knockout mice; phospho-HORMAD2 and ATR-target IF/western blot\",\n      \"pmids\": [\"35133274\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct biochemical phosphorylation not shown\", \"Phosphosite still undefined\", \"Single lab\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Connected HORMAD2 checkpoint signaling to aneuploidy risk by showing non-homologous synapsis maintains pachytene-like HORMAD2 levels and thereby evades the asynapsis checkpoint.\",\n      \"evidence\": \"HORMAD2 IF quantification on Prdm9-deficient rat oocyte chromosome spreads\",\n      \"pmids\": [\"35596034\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Correlative protein quantification without functional rescue\", \"Mechanism of checkpoint evasion not directly tested\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Provided high-resolution structural confirmation that human HORMAD2 binds HORMAD1's HORMA domain via a shared Ser-Glu-Pro closure motif, and tied this interaction to HR repair function.\",\n      \"evidence\": \"X-ray crystallography of human HORMAD1, peptide-binding assays, cell-based HR repair reporter\",\n      \"pmids\": [\"37794593\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"HR repair assay performed in non-meiotic cell context\", \"No structure of full-length HORMAD2\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identified HORMAD2's in vivo interactors and showed its N-terminus is required for TRIP13-mediated removal, with mislocalization to the SC central region upon N-terminal tagging.\",\n      \"evidence\": \"N-terminal knock-in tagging in mice; Co-IP/mass spectrometry; super-resolution microscopy; fertility and sperm count\",\n      \"pmids\": [\"38401263\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not map the precise TRIP13 engagement residues\", \"Reduced sperm count mechanism not fully resolved\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Defined the effector mechanism of the retained-HORMAD checkpoint: HORMAD2 (with HORMAD1) recruits BRCA1 via an N-terminal HORMA-domain interface to trigger oocyte elimination, and confirmed HORMAD2's apoptotic role is specific to asynapsis surveillance.\",\n      \"evidence\": \"Reciprocal Co-IP; N-terminal-tagged HORMAD knock-in mice; BRCA1 IF; oocyte counting; squash immunohistochemistry with Spo11/Dmc1 double mutants\",\n      \"pmids\": [\"40050306\", \"39961811\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"HORMAD2 contributes to but binds BRCA1 only weakly \\u2014 relative contribution vs HORMAD1 not quantified\", \"Downstream apoptotic execution steps not detailed\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How HORMAD2 phosphorylation, its peripheral axial positioning, and the N-terminal BRCA1/TRIP13 interface are mechanistically integrated to convert an unsynapsed axis into a committed elimination signal remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"HORMAD2 phosphosite identity and its functional requirement remain undefined\", \"Direct biochemical reconstitution of TRIP13-mediated HORMAD2 removal is lacking\", \"The precise structural interface and quantitative contribution of HORMAD2 to BRCA1 recruitment is unresolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [1, 2, 12]},\n      {\"term_id\": \"GO:0005515\", \"supporting_discovery_ids\": [4, 10, 11]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005694\", \"supporting_discovery_ids\": [0, 6, 11]},\n      {\"term_id\": \"GO:0000228\", \"supporting_discovery_ids\": [0, 6]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [1, 2, 5]},\n      {\"term_id\": \"R-HSA-8953897\", \"supporting_discovery_ids\": [1, 2, 13]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [5, 12, 13]}\n    ],\n    \"complexes\": [\"synaptonemal complex axis / lateral element\"],\n    \"partners\": [\"HORMAD1\", \"SYCP2\", \"SYCP3\", \"TRIP13\", \"BRCA1\", \"ATR\", \"RAD1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":4,"faith_total":5,"faith_pct":80.0}}