{"gene":"HORMAD2","run_date":"2026-04-28T18:06:53","timeline":{"discoveries":[{"year":2009,"finding":"Mouse 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-components along chromosome axes, establishing that SC formation (directly or indirectly) promotes HORMAD depletion from synapsed axes.","method":"Immunofluorescence analysis of wild-type and mutant (TRIP13-deficient, DSB-defective, SC-defective) mouse spermatocytes and oocytes; genetic epistasis with multiple mutants","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal genetic backgrounds, replicated across multiple mutants, highly cited foundational paper","pmids":["19851446"],"is_preprint":false},{"year":2012,"finding":"HORMAD2 is required for the accumulation of the checkpoint kinase ATR along unsynapsed chromosome axes (but not at DSBs or DSB-associated chromatin loops), and this HORMAD2-dependent ATR recruitment constitutes a distinct asynapsis surveillance mechanism that eliminates asynaptic oocytes (Spo11−/− but not Dmc1−/− oocytes).","method":"Hormad2 knockout mouse generation; immunofluorescence for ATR on meiotic chromosomes; analysis of Spo11−/−, Dmc1−/−, and double-mutant oocyte survival","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 2 — clean KO with defined cellular phenotype, epistasis with Spo11 and Dmc1, two independent labs (Wojtasz et al. and Kogo et al.) reporting consistent results","pmids":["22549958"],"is_preprint":false},{"year":2012,"finding":"HORMAD2 deficiency impairs proper recruitment of ATR activity to unsynapsed chromosomes in male mice, causing characteristic sex body malformation (ATR/γH2AX-enriched domain dissociated from elongated sex chromosome axes) and spermatocyte loss; in females, HORMAD2-dependent pseudo-sex body formation (local ATR concentration) drives elimination of Spo11-deficient asynaptic oocytes.","method":"Hormad2 knockout mouse; immunofluorescence for ATR, γH2AX, sex body markers; Hormad2/Spo11 double-mutant analysis with oocyte counting","journal":"Genes to cells","confidence":"High","confidence_rationale":"Tier 2 — independent KO mouse study corroborating Wojtasz et al. 2012, multiple phenotypic readouts and epistasis","pmids":["23039116"],"is_preprint":false},{"year":2012,"finding":"HORMAD2 (along with HORMAD1) becomes phosphorylated during meiotic prophase I; BRCA1 and SYCP3 are required for normal phosphorylation levels of HORMAD1 and HORMAD2 (but not SMC3), and reduced HORMAD1/2 phosphorylation is associated with impaired targeting of the meiotic silencing of unsynapsed chromatin (MSUC) machinery.","method":"Immunofluorescence with phospho-specific antibodies; analysis of Brca1, Sycp3, and recombination-initiation mutant mice","journal":"PLoS genetics","confidence":"Medium","confidence_rationale":"Tier 2 — genetic requirement established in multiple mutant backgrounds, single lab study","pmids":["22346761"],"is_preprint":false},{"year":2014,"finding":"Mammalian HORMAD1 binds a peptide motif found at the C-terminus of HORMAD2, indicating that intermolecular HORMA domain–closure motif interactions (analogous to the Mad2 'safety belt') are a conserved feature of meiotic chromosome structure, and this interaction is relevant for HORMAD2 recruitment to chromosome axes.","method":"Biochemical pulldown and structural analysis of C. elegans HORMA proteins with validation of conserved HORMAD1–HORMAD2 C-terminal peptide interaction in mammals","journal":"Developmental cell","confidence":"Medium","confidence_rationale":"Tier 1 — structural and biochemical data, but mammalian HORMAD1–HORMAD2 interaction confirmed as extrapolation from C. elegans work","pmids":["25446517"],"is_preprint":false},{"year":2017,"finding":"HORMAD1/2 on unsynapsed chromosome axes inhibit repair of spontaneous DSBs via intersister recombination; CHK2-dependent DNA damage checkpoint culls oocytes that accumulate ~10 spontaneous DSBs in late prophase I. Hormad2 deletion rescued fertility of Trip13 mutant oocytes (which retain HORMADs on synapsed chromosomes), establishing that HORMAD2 promotes intersister repair inhibition and DSB-dependent oocyte elimination downstream of asynapsis.","method":"Hormad2 deletion in Trip13 mutant mice; genetic epistasis; analysis of oocyte survival and DSB markers","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 — clean epistasis experiment with defined phenotypic rescue, directly establishes pathway position","pmids":["28844861"],"is_preprint":false},{"year":2019,"finding":"By expansion STORM super-resolution microscopy of mouse spermatocytes, HORMAD2 is localized to the periphery of the chromosome axis core (which is formed by SYCP3 filaments), arrayed around the SYCP3/SYCP2 C-terminal core together with cohesin complexes and the N-terminus of SYCP2.","method":"Expansion microscopy coupled with 2-color STORM (ExSTORM) imaging at 10–20 nm resolution in mouse spermatocytes","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 — direct structural/localization determination by super-resolution microscopy with orthogonal validation","pmids":["31444302"],"is_preprint":false},{"year":2020,"finding":"Pathogenic missense variants in TRIP13 reduce its protein abundance and cause accumulation of HORMAD2 (its downstream molecule) in HeLa cells and proband-derived lymphoblastoid cells, confirming that TRIP13 AAA-ATPase activity is required for HORMAD2 turnover/removal in human cells.","method":"In vitro expression of TRIP13 variants in HeLa cells; immunoblotting for HORMAD2 levels; analysis of patient-derived lymphoblastoid cells","journal":"American journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 2 — cell-based assay with patient-derived material confirming TRIP13–HORMAD2 relationship, 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) on meiotic chromosomes; testis-specific Rad1 disruption caused severe synapsis defects and impaired ATR signaling including HORMAD2 phosphorylation, unlike disruption of only the canonical HUS1 or RAD9A subunits.","method":"Testis-specific Rad1 knockout mice; immunofluorescence for phospho-HORMAD2 and other ATR targets on meiotic chromosome spreads; comparison with Hus1 and Rad9a knockouts","journal":"eLife","confidence":"Medium","confidence_rationale":"Tier 2 — clean conditional KO with defined molecular phenotype, single lab","pmids":["35133274"],"is_preprint":false},{"year":2023,"finding":"The HORMA domain of HORMAD1 binds a peptide motif from HORMAD2 (sharing a conserved Ser-Glu-Pro sequence with HORMAD1's own closure motif and MCM9), in a self-closed intra-molecular interaction mode; structural comparison and cell-based assays show this HORMA–closure motif interaction contributes to DNA mismatch repair and HR repair.","method":"Crystal structure of human HORMAD1; biochemical binding assays with HORMAD2-derived peptides; mutagenesis; cell-based HR and MMR reporter assays","journal":"Structure","confidence":"High","confidence_rationale":"Tier 1 — crystal structure combined with biochemical binding assays and cell-based functional validation with mutagenesis","pmids":["37794593"],"is_preprint":false},{"year":2024,"finding":"The N-terminal region of HORMAD2 is critical for its timely removal from synapsed meiotic chromosome axes by TRIP13; N-terminal 3×FLAG-HA tagging causes HORMAD2 to persist ectopically on synapsed regions in pachynema and localizes to the central region of the synaptonemal complex rather than lateral elements, while HORMAD1 remains on lateral elements. Co-immunoprecipitation with mass spectrometry identified HORMAD1 and SYCP2 as HORMAD2-associated proteins in testis.","method":"N-terminal tagging knockin mouse; co-immunoprecipitation coupled with mass spectrometry; super-resolution microscopy; sperm count analysis","journal":"Reproduction","confidence":"High","confidence_rationale":"Tier 1 — knockin mouse with precise molecular perturbation, super-resolution microscopy, and proteomics-based binding partner identification","pmids":["38401263"],"is_preprint":false},{"year":2025,"finding":"When HORMAD1 and HORMAD2 are retained on synapsed chromosome axes (by TRIP13 depletion), they recruit BRCA1 and activate the chromosome asynapsis checkpoint triggering oocyte elimination. HORMAD1 co-immunoprecipitates with BRCA1 via an interface on its HORMA domain near the N-terminus (not through the canonical closure motif-binding mode); HORMAD2 co-immunoprecipitates weakly with BRCA1 but also contributes to its recruitment. N-terminal tagging of HORMAD1 or HORMAD2 retains them on synapsed axes without triggering oocyte elimination due to defective BRCA1 recruitment.","method":"Co-immunoprecipitation; TRIP13-depletion mouse model; N-terminal tagging knockin mice; oocyte elimination assays; mutagenesis of HORMAD1 interaction interface","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1–2 — multiple orthogonal methods (Co-IP, genetic mouse models, mutagenesis, functional oocyte elimination assay) in a single study","pmids":["40050306"],"is_preprint":false},{"year":2025,"finding":"Asynapsis-induced oocyte apoptosis (in Spo11-deficient mice) but not DNA damage-induced apoptosis (in Dmc1-deficient mice) is significantly dependent on HORMAD2, confirming a specific role for HORMAD2 in the asynapsis surveillance pathway distinct from the DNA damage checkpoint.","method":"Double-mutant analysis (Hormad2/Spo11 and Hormad2/Dmc1) with immunohistochemical apoptosis assay on perinatal mouse ovaries using squash method","journal":"Histochemistry and cell biology","confidence":"Medium","confidence_rationale":"Tier 2 — clean epistasis with two different checkpoint mutants, single lab, corroborates prior findings","pmids":["39961811"],"is_preprint":false}],"current_model":"HORMAD2 is a meiosis-specific HORMA domain protein that localizes to unsynapsed chromosome axes by engaging HORMAD1 via a conserved closure motif–HORMA domain interaction (analogous to Mad2's safety belt), where it recruits ATR kinase activity and BRCA1 to activate an asynapsis surveillance checkpoint that eliminates oocytes with unsynapsed chromosomes; upon synapsis, the TRIP13 AAA-ATPase engages HORMAD2's N-terminal region to displace it from chromosome axes, and failure of this removal results in aberrant BRCA1 recruitment and unintended oocyte elimination, establishing TRIP13-dependent HORMAD2 removal as essential for female fertility."},"narrative":{"teleology":[{"year":2009,"claim":"Establishing that HORMAD2 preferentially marks unsynapsed chromosome axes and that TRIP13 is required for its depletion upon synapsis answered the foundational question of where HORMAD2 acts and how its distribution is regulated.","evidence":"Immunofluorescence in wild-type and multiple mutant mouse spermatocytes/oocytes (TRIP13-deficient, DSB-defective, SC-defective)","pmids":["19851446"],"confidence":"High","gaps":["Mechanism by which TRIP13 removes HORMAD2 was unknown","Whether HORMAD2 has a functional role beyond a marker of unsynapsed axes was unresolved","Direct physical interaction between TRIP13 and HORMAD2 not demonstrated"]},{"year":2012,"claim":"Two independent knockout studies demonstrated that HORMAD2 is specifically required for ATR recruitment to unsynapsed axes (not DSB sites) and for asynapsis-specific oocyte elimination, separating the asynapsis surveillance pathway from the DNA damage checkpoint.","evidence":"Hormad2 knockout mice; epistasis with Spo11−/− and Dmc1−/− backgrounds; immunofluorescence for ATR, γH2AX, sex body markers; oocyte counting","pmids":["22549958","23039116"],"confidence":"High","gaps":["Molecular mechanism by which HORMAD2 recruits ATR was unclear","Whether HORMAD2 acts directly or through HORMAD1 in checkpoint activation was unresolved","Role of HORMAD2 phosphorylation in ATR signaling not established"]},{"year":2012,"claim":"The finding that BRCA1 and SYCP3 are required for normal HORMAD1/2 phosphorylation connected HORMAD2 modification to the meiotic silencing of unsynapsed chromatin (MSUC) machinery, revealing upstream regulators of HORMAD2 phosphorylation.","evidence":"Phospho-specific immunofluorescence in Brca1, Sycp3, and recombination-initiation mutant mice","pmids":["22346761"],"confidence":"Medium","gaps":["Identity of the kinase directly phosphorylating HORMAD2 was not determined","Functional consequences of reduced HORMAD2 phosphorylation on checkpoint activation not tested directly","Relationship between MSUC and asynapsis checkpoint was unclear"]},{"year":2014,"claim":"Biochemical and structural analysis revealed that HORMAD1 binds a C-terminal closure motif on HORMAD2 in a safety-belt mechanism conserved from worms to mammals, explaining the molecular basis of HORMAD2 recruitment to chromosome axes via HORMAD1.","evidence":"Biochemical pulldown and structural analysis of C. elegans HORMA proteins with validation of the conserved HORMAD1–HORMAD2 peptide interaction in mammals","pmids":["25446517"],"confidence":"Medium","gaps":["Mammalian interaction was inferred partly from C. elegans structural data","Whether disrupting this interaction in vivo affects HORMAD2 axis localization was untested","Stoichiometry and dynamics of the HORMAD1–HORMAD2 complex on axes were unknown"]},{"year":2017,"claim":"Epistasis experiments showed that HORMAD2 deletion rescues fertility of Trip13-mutant oocytes and that persistent HORMAD1/2 on synapsed axes inhibits intersister DSB repair, positioning HORMAD2 as a functional effector—not merely a marker—of the asynapsis checkpoint and recombination control.","evidence":"Hormad2 deletion in Trip13 mutant mice; oocyte survival analysis; DSB marker quantification","pmids":["28844861"],"confidence":"High","gaps":["Mechanism by which HORMAD2 inhibits intersister recombination was not defined","Whether HORMAD2 acts through ATR or through a distinct effector for recombination control was unresolved"]},{"year":2019,"claim":"Super-resolution imaging placed HORMAD2 at the periphery of the meiotic chromosome axis core, resolving its nanoscale position relative to SYCP3/SYCP2 and cohesins.","evidence":"Expansion STORM (ExSTORM) super-resolution microscopy at 10–20 nm resolution in mouse spermatocytes","pmids":["31444302"],"confidence":"High","gaps":["How peripheral localization relates to HORMAD2 function in ATR recruitment was not addressed","Whether HORMAD2 contacts the central element of the SC prior to removal was unknown"]},{"year":2020,"claim":"Pathogenic TRIP13 variants cause HORMAD2 accumulation in human cells, confirming that the TRIP13–HORMAD2 regulatory axis is conserved beyond mouse and operates in somatic cells.","evidence":"Expression of TRIP13 variants in HeLa cells; immunoblotting for HORMAD2 in patient-derived lymphoblastoid cells","pmids":["32473092"],"confidence":"Medium","gaps":["Functional consequence of HORMAD2 accumulation in somatic cells not characterized","Whether TRIP13 directly contacts HORMAD2 or acts via HORMAD1 was still unclear"]},{"year":2022,"claim":"RAD1 (9-1-1 complex subunit) was shown to be required for HORMAD2 phosphorylation as an ATR target, identifying the upstream DNA damage sensor complex that channels ATR activity toward HORMAD2.","evidence":"Testis-specific Rad1 conditional knockout mice; immunofluorescence for phospho-HORMAD2 on meiotic chromosome spreads","pmids":["35133274"],"confidence":"Medium","gaps":["Whether 9-1-1 recruits ATR to HORMAD2 directly or through an intermediate was not resolved","Specific phosphorylation sites on HORMAD2 were not mapped"]},{"year":2023,"claim":"Crystal structure of human HORMAD1 bound to a HORMAD2-derived closure motif peptide (sharing a conserved Ser-Glu-Pro sequence) defined the atomic interface and linked the HORMAD1–HORMAD2 interaction to homologous recombination and mismatch repair functions.","evidence":"X-ray crystallography of human HORMAD1; biochemical binding assays with HORMAD2 peptides; mutagenesis; cell-based HR and MMR reporter assays","pmids":["37794593"],"confidence":"High","gaps":["In vivo meiotic consequence of disrupting the specific binding interface was not tested","Whether HORMAD2 plays a direct role in somatic HR/MMR or acts only through HORMAD1 was unclear"]},{"year":2024,"claim":"Knockin mouse studies demonstrated that the N-terminal region of HORMAD2 is critical for TRIP13-mediated removal from synapsed axes: N-terminal tagging caused ectopic HORMAD2 persistence on synapsed regions and relocalization to the SC central region, and identified HORMAD1 and SYCP2 as HORMAD2-associated proteins by co-IP/MS.","evidence":"N-terminal 3×FLAG-HA tagging knockin mouse; co-immunoprecipitation with mass spectrometry; super-resolution microscopy; sperm count analysis","pmids":["38401263"],"confidence":"High","gaps":["Whether TRIP13 directly engages the HORMAD2 N-terminus or acts through an adaptor (e.g., p31comet) was not resolved","How ectopic HORMAD2 relocates to the central region of the SC was mechanistically unclear"]},{"year":2025,"claim":"Retained HORMAD1/2 on synapsed axes (via TRIP13 depletion) recruit BRCA1 to trigger the asynapsis checkpoint and oocyte elimination; HORMAD1 binds BRCA1 via a HORMA domain interface near its N-terminus, while HORMAD2 contributes to BRCA1 recruitment. N-terminal tagging of either HORMAD blocks BRCA1 recruitment and oocyte elimination, explaining why tagged HORMAD2 persistence is not toxic.","evidence":"Co-immunoprecipitation; TRIP13-depletion and N-terminal tagging knockin mice; oocyte elimination assays; HORMAD1 mutagenesis","pmids":["40050306"],"confidence":"High","gaps":["Direct versus indirect contribution of HORMAD2 to BRCA1 recruitment not fully separated from HORMAD1","Structural basis of the HORMAD1–BRCA1 interface not determined","Whether HORMAD2 contacts additional checkpoint effectors beyond BRCA1 and ATR is unknown"]},{"year":2025,"claim":"Double-mutant analysis confirmed that HORMAD2 is specifically required for asynapsis-induced (Spo11-dependent) but not DNA damage-induced (Dmc1-dependent) oocyte apoptosis, reinforcing the pathway specificity first observed in 2012.","evidence":"Hormad2/Spo11 and Hormad2/Dmc1 double-mutant mice; immunohistochemical apoptosis assay on perinatal ovaries","pmids":["39961811"],"confidence":"Medium","gaps":["Molecular distinction between asynapsis and DNA damage checkpoint signaling downstream of HORMAD2 not fully elucidated"]},{"year":null,"claim":"Key open questions include: whether TRIP13 directly engages the HORMAD2 N-terminus or acts through an adaptor such as p31comet; the identity and functional significance of specific HORMAD2 phosphorylation sites; and whether HORMAD2 has checkpoint effector functions independent of HORMAD1.","evidence":"","pmids":[],"confidence":"Low","gaps":["Direct TRIP13–HORMAD2 physical interaction and structural basis not demonstrated","Specific phosphorylation sites on HORMAD2 and their individual contributions to ATR signaling not mapped","Whether HORMAD2 has HORMAD1-independent roles in meiotic surveillance or recombination control remains untested"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[4,9,10]}],"localization":[{"term_id":"GO:0005694","term_label":"chromosome","supporting_discovery_ids":[0,1,2,6,10]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,1,6]}],"pathway":[{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[0,1,5,10]},{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[5,9]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[1,2,11,12]}],"complexes":[],"partners":["HORMAD1","TRIP13","ATR","BRCA1","SYCP2","RAD1"],"other_free_text":[]},"mechanistic_narrative":"HORMAD2 is a meiosis-specific HORMA domain protein that functions as a sensor of chromosome asynapsis, recruiting ATR kinase activity and BRCA1 to unsynapsed chromosome axes to activate a surveillance checkpoint that eliminates defective oocytes. HORMAD2 preferentially associates with unsynapsed axes throughout meiotic prophase, where it is positioned at the periphery of the SYCP3/SYCP2 axis core, and engages HORMAD1 through a conserved C-terminal closure motif–HORMA domain interaction analogous to the Mad2 safety-belt mechanism [PMID:25446517, PMID:37794593, PMID:31444302]. HORMAD2-dependent ATR accumulation on unsynapsed axes drives asynapsis-specific oocyte elimination (distinct from the DNA damage checkpoint), while HORMAD2 also inhibits intersister recombination repair of spontaneous DSBs, linking persistent asynapsis to CHK2-dependent oocyte culling [PMID:22549958, PMID:23039116, PMID:28844861, PMID:39961811]. Upon synapsis, the TRIP13 AAA-ATPase engages the N-terminal region of HORMAD2 to strip it from chromosome axes; failure of this removal—caused by TRIP13 loss or N-terminal perturbation—results in ectopic BRCA1 recruitment and unintended oocyte elimination, establishing TRIP13-dependent HORMAD2 removal as essential for female fertility [PMID:19851446, PMID:38401263, PMID:40050306]."},"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":327,"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":121,"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":103,"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":99,"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":97,"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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TRIP13 AAA-ATPase is required for the reciprocal distribution of HORMADs and SYCP1/SC-components along chromosome axes, establishing that SC formation (directly or indirectly) promotes HORMAD depletion from synapsed axes.\",\n      \"method\": \"Immunofluorescence analysis of wild-type and mutant (TRIP13-deficient, DSB-defective, SC-defective) mouse spermatocytes and oocytes; genetic epistasis with multiple mutants\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal genetic backgrounds, replicated across multiple mutants, highly cited foundational paper\",\n      \"pmids\": [\"19851446\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"HORMAD2 is required for the accumulation of the checkpoint kinase ATR along unsynapsed chromosome axes (but not at DSBs or DSB-associated chromatin loops), and this HORMAD2-dependent ATR recruitment constitutes a distinct asynapsis surveillance mechanism that eliminates asynaptic oocytes (Spo11−/− but not Dmc1−/− oocytes).\",\n      \"method\": \"Hormad2 knockout mouse generation; immunofluorescence for ATR on meiotic chromosomes; analysis of Spo11−/−, Dmc1−/−, and double-mutant oocyte survival\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with defined cellular phenotype, epistasis with Spo11 and Dmc1, two independent labs (Wojtasz et al. and Kogo et al.) reporting consistent results\",\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 male mice, causing characteristic sex body malformation (ATR/γH2AX-enriched domain dissociated from elongated sex chromosome axes) and spermatocyte loss; in females, HORMAD2-dependent pseudo-sex body formation (local ATR concentration) drives elimination of Spo11-deficient asynaptic oocytes.\",\n      \"method\": \"Hormad2 knockout mouse; immunofluorescence for ATR, γH2AX, sex body markers; Hormad2/Spo11 double-mutant analysis with oocyte counting\",\n      \"journal\": \"Genes to cells\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — independent KO mouse study corroborating Wojtasz et al. 2012, multiple phenotypic readouts and epistasis\",\n      \"pmids\": [\"23039116\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"HORMAD2 (along with HORMAD1) becomes phosphorylated during meiotic prophase I; BRCA1 and SYCP3 are required for normal phosphorylation levels of HORMAD1 and HORMAD2 (but not SMC3), and reduced HORMAD1/2 phosphorylation is associated with impaired targeting of the meiotic silencing of unsynapsed chromatin (MSUC) machinery.\",\n      \"method\": \"Immunofluorescence with phospho-specific antibodies; analysis of Brca1, Sycp3, and recombination-initiation mutant mice\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic requirement established in multiple mutant backgrounds, single lab study\",\n      \"pmids\": [\"22346761\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Mammalian HORMAD1 binds a peptide motif found at the C-terminus of HORMAD2, indicating that intermolecular HORMA domain–closure motif interactions (analogous to the Mad2 'safety belt') are a conserved feature of meiotic chromosome structure, and this interaction is relevant for HORMAD2 recruitment to chromosome axes.\",\n      \"method\": \"Biochemical pulldown and structural analysis of C. elegans HORMA proteins with validation of conserved HORMAD1–HORMAD2 C-terminal peptide interaction in mammals\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — structural and biochemical data, but mammalian HORMAD1–HORMAD2 interaction confirmed as extrapolation from C. elegans work\",\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 via intersister recombination; CHK2-dependent DNA damage checkpoint culls oocytes that accumulate ~10 spontaneous DSBs in late prophase I. Hormad2 deletion rescued fertility of Trip13 mutant oocytes (which retain HORMADs on synapsed chromosomes), establishing that HORMAD2 promotes intersister repair inhibition and DSB-dependent oocyte elimination downstream of asynapsis.\",\n      \"method\": \"Hormad2 deletion in Trip13 mutant mice; genetic epistasis; analysis of oocyte survival and DSB markers\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean epistasis experiment with defined phenotypic rescue, directly establishes pathway position\",\n      \"pmids\": [\"28844861\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"By expansion STORM super-resolution microscopy of mouse spermatocytes, HORMAD2 is localized to the periphery of the chromosome axis core (which is formed by SYCP3 filaments), arrayed around the SYCP3/SYCP2 C-terminal core together with cohesin complexes and the N-terminus of SYCP2.\",\n      \"method\": \"Expansion microscopy coupled with 2-color STORM (ExSTORM) imaging at 10–20 nm resolution in mouse spermatocytes\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — direct structural/localization determination by super-resolution microscopy with orthogonal validation\",\n      \"pmids\": [\"31444302\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Pathogenic missense variants in TRIP13 reduce its protein abundance and cause accumulation of HORMAD2 (its downstream molecule) in HeLa cells and proband-derived lymphoblastoid cells, confirming that TRIP13 AAA-ATPase activity is required for HORMAD2 turnover/removal in human cells.\",\n      \"method\": \"In vitro expression of TRIP13 variants in HeLa cells; immunoblotting for HORMAD2 levels; analysis of patient-derived lymphoblastoid cells\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — cell-based assay with patient-derived material confirming TRIP13–HORMAD2 relationship, 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) on meiotic chromosomes; testis-specific Rad1 disruption caused severe synapsis defects and impaired ATR signaling including HORMAD2 phosphorylation, unlike disruption of only the canonical HUS1 or RAD9A subunits.\",\n      \"method\": \"Testis-specific Rad1 knockout mice; immunofluorescence for phospho-HORMAD2 and other ATR targets on meiotic chromosome spreads; comparison with Hus1 and Rad9a knockouts\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean conditional KO with defined molecular phenotype, single lab\",\n      \"pmids\": [\"35133274\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"The HORMA domain of HORMAD1 binds a peptide motif from HORMAD2 (sharing a conserved Ser-Glu-Pro sequence with HORMAD1's own closure motif and MCM9), in a self-closed intra-molecular interaction mode; structural comparison and cell-based assays show this HORMA–closure motif interaction contributes to DNA mismatch repair and HR repair.\",\n      \"method\": \"Crystal structure of human HORMAD1; biochemical binding assays with HORMAD2-derived peptides; mutagenesis; cell-based HR and MMR reporter assays\",\n      \"journal\": \"Structure\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure combined with biochemical binding assays and cell-based functional validation with mutagenesis\",\n      \"pmids\": [\"37794593\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"The N-terminal region of HORMAD2 is critical for its timely removal from synapsed meiotic chromosome axes by TRIP13; N-terminal 3×FLAG-HA tagging causes HORMAD2 to persist ectopically on synapsed regions in pachynema and localizes to the central region of the synaptonemal complex rather than lateral elements, while HORMAD1 remains on lateral elements. Co-immunoprecipitation with mass spectrometry identified HORMAD1 and SYCP2 as HORMAD2-associated proteins in testis.\",\n      \"method\": \"N-terminal tagging knockin mouse; co-immunoprecipitation coupled with mass spectrometry; super-resolution microscopy; sperm count analysis\",\n      \"journal\": \"Reproduction\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — knockin mouse with precise molecular perturbation, super-resolution microscopy, and proteomics-based binding partner identification\",\n      \"pmids\": [\"38401263\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"When HORMAD1 and HORMAD2 are retained on synapsed chromosome axes (by TRIP13 depletion), they recruit BRCA1 and activate the chromosome asynapsis checkpoint triggering oocyte elimination. HORMAD1 co-immunoprecipitates with BRCA1 via an interface on its HORMA domain near the N-terminus (not through the canonical closure motif-binding mode); HORMAD2 co-immunoprecipitates weakly with BRCA1 but also contributes to its recruitment. N-terminal tagging of HORMAD1 or HORMAD2 retains them on synapsed axes without triggering oocyte elimination due to defective BRCA1 recruitment.\",\n      \"method\": \"Co-immunoprecipitation; TRIP13-depletion mouse model; N-terminal tagging knockin mice; oocyte elimination assays; mutagenesis of HORMAD1 interaction interface\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — multiple orthogonal methods (Co-IP, genetic mouse models, mutagenesis, functional oocyte elimination assay) in a single study\",\n      \"pmids\": [\"40050306\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Asynapsis-induced oocyte apoptosis (in Spo11-deficient mice) but not DNA damage-induced apoptosis (in Dmc1-deficient mice) is significantly dependent on HORMAD2, confirming a specific role for HORMAD2 in the asynapsis surveillance pathway distinct from the DNA damage checkpoint.\",\n      \"method\": \"Double-mutant analysis (Hormad2/Spo11 and Hormad2/Dmc1) with immunohistochemical apoptosis assay on perinatal mouse ovaries using squash method\",\n      \"journal\": \"Histochemistry and cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean epistasis with two different checkpoint mutants, single lab, corroborates prior findings\",\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 by engaging HORMAD1 via a conserved closure motif–HORMA domain interaction (analogous to Mad2's safety belt), where it recruits ATR kinase activity and BRCA1 to activate an asynapsis surveillance checkpoint that eliminates oocytes with unsynapsed chromosomes; upon synapsis, the TRIP13 AAA-ATPase engages HORMAD2's N-terminal region to displace it from chromosome axes, and failure of this removal results in aberrant BRCA1 recruitment and unintended oocyte elimination, establishing TRIP13-dependent HORMAD2 removal as essential for female fertility.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"HORMAD2 is a meiosis-specific HORMA domain protein that functions as a sensor of chromosome asynapsis, recruiting ATR kinase activity and BRCA1 to unsynapsed chromosome axes to activate a surveillance checkpoint that eliminates defective oocytes. HORMAD2 preferentially associates with unsynapsed axes throughout meiotic prophase, where it is positioned at the periphery of the SYCP3/SYCP2 axis core, and engages HORMAD1 through a conserved C-terminal closure motif–HORMA domain interaction analogous to the Mad2 safety-belt mechanism [PMID:25446517, PMID:37794593, PMID:31444302]. HORMAD2-dependent ATR accumulation on unsynapsed axes drives asynapsis-specific oocyte elimination (distinct from the DNA damage checkpoint), while HORMAD2 also inhibits intersister recombination repair of spontaneous DSBs, linking persistent asynapsis to CHK2-dependent oocyte culling [PMID:22549958, PMID:23039116, PMID:28844861, PMID:39961811]. Upon synapsis, the TRIP13 AAA-ATPase engages the N-terminal region of HORMAD2 to strip it from chromosome axes; failure of this removal—caused by TRIP13 loss or N-terminal perturbation—results in ectopic BRCA1 recruitment and unintended oocyte elimination, establishing TRIP13-dependent HORMAD2 removal as essential for female fertility [PMID:19851446, PMID:38401263, PMID:40050306].\",\n  \"teleology\": [\n    {\n      \"year\": 2009,\n      \"claim\": \"Establishing that HORMAD2 preferentially marks unsynapsed chromosome axes and that TRIP13 is required for its depletion upon synapsis answered the foundational question of where HORMAD2 acts and how its distribution is regulated.\",\n      \"evidence\": \"Immunofluorescence in wild-type and multiple mutant mouse spermatocytes/oocytes (TRIP13-deficient, DSB-defective, SC-defective)\",\n      \"pmids\": [\"19851446\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which TRIP13 removes HORMAD2 was unknown\", \"Whether HORMAD2 has a functional role beyond a marker of unsynapsed axes was unresolved\", \"Direct physical interaction between TRIP13 and HORMAD2 not demonstrated\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Two independent knockout studies demonstrated that HORMAD2 is specifically required for ATR recruitment to unsynapsed axes (not DSB sites) and for asynapsis-specific oocyte elimination, separating the asynapsis surveillance pathway from the DNA damage checkpoint.\",\n      \"evidence\": \"Hormad2 knockout mice; epistasis with Spo11−/− and Dmc1−/− backgrounds; immunofluorescence for ATR, γH2AX, sex body markers; oocyte counting\",\n      \"pmids\": [\"22549958\", \"23039116\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism by which HORMAD2 recruits ATR was unclear\", \"Whether HORMAD2 acts directly or through HORMAD1 in checkpoint activation was unresolved\", \"Role of HORMAD2 phosphorylation in ATR signaling not established\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"The finding that BRCA1 and SYCP3 are required for normal HORMAD1/2 phosphorylation connected HORMAD2 modification to the meiotic silencing of unsynapsed chromatin (MSUC) machinery, revealing upstream regulators of HORMAD2 phosphorylation.\",\n      \"evidence\": \"Phospho-specific immunofluorescence in Brca1, Sycp3, and recombination-initiation mutant mice\",\n      \"pmids\": [\"22346761\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Identity of the kinase directly phosphorylating HORMAD2 was not determined\", \"Functional consequences of reduced HORMAD2 phosphorylation on checkpoint activation not tested directly\", \"Relationship between MSUC and asynapsis checkpoint was unclear\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Biochemical and structural analysis revealed that HORMAD1 binds a C-terminal closure motif on HORMAD2 in a safety-belt mechanism conserved from worms to mammals, explaining the molecular basis of HORMAD2 recruitment to chromosome axes via HORMAD1.\",\n      \"evidence\": \"Biochemical pulldown and structural analysis of C. elegans HORMA proteins with validation of the conserved HORMAD1–HORMAD2 peptide interaction in mammals\",\n      \"pmids\": [\"25446517\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mammalian interaction was inferred partly from C. elegans structural data\", \"Whether disrupting this interaction in vivo affects HORMAD2 axis localization was untested\", \"Stoichiometry and dynamics of the HORMAD1–HORMAD2 complex on axes were unknown\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Epistasis experiments showed that HORMAD2 deletion rescues fertility of Trip13-mutant oocytes and that persistent HORMAD1/2 on synapsed axes inhibits intersister DSB repair, positioning HORMAD2 as a functional effector—not merely a marker—of the asynapsis checkpoint and recombination control.\",\n      \"evidence\": \"Hormad2 deletion in Trip13 mutant mice; oocyte survival analysis; DSB marker quantification\",\n      \"pmids\": [\"28844861\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which HORMAD2 inhibits intersister recombination was not defined\", \"Whether HORMAD2 acts through ATR or through a distinct effector for recombination control was unresolved\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Super-resolution imaging placed HORMAD2 at the periphery of the meiotic chromosome axis core, resolving its nanoscale position relative to SYCP3/SYCP2 and cohesins.\",\n      \"evidence\": \"Expansion STORM (ExSTORM) super-resolution microscopy at 10–20 nm resolution in mouse spermatocytes\",\n      \"pmids\": [\"31444302\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How peripheral localization relates to HORMAD2 function in ATR recruitment was not addressed\", \"Whether HORMAD2 contacts the central element of the SC prior to removal was unknown\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Pathogenic TRIP13 variants cause HORMAD2 accumulation in human cells, confirming that the TRIP13–HORMAD2 regulatory axis is conserved beyond mouse and operates in somatic cells.\",\n      \"evidence\": \"Expression of TRIP13 variants in HeLa cells; immunoblotting for HORMAD2 in patient-derived lymphoblastoid cells\",\n      \"pmids\": [\"32473092\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of HORMAD2 accumulation in somatic cells not characterized\", \"Whether TRIP13 directly contacts HORMAD2 or acts via HORMAD1 was still unclear\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"RAD1 (9-1-1 complex subunit) was shown to be required for HORMAD2 phosphorylation as an ATR target, identifying the upstream DNA damage sensor complex that channels ATR activity toward HORMAD2.\",\n      \"evidence\": \"Testis-specific Rad1 conditional knockout mice; immunofluorescence for phospho-HORMAD2 on meiotic chromosome spreads\",\n      \"pmids\": [\"35133274\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether 9-1-1 recruits ATR to HORMAD2 directly or through an intermediate was not resolved\", \"Specific phosphorylation sites on HORMAD2 were not mapped\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Crystal structure of human HORMAD1 bound to a HORMAD2-derived closure motif peptide (sharing a conserved Ser-Glu-Pro sequence) defined the atomic interface and linked the HORMAD1–HORMAD2 interaction to homologous recombination and mismatch repair functions.\",\n      \"evidence\": \"X-ray crystallography of human HORMAD1; biochemical binding assays with HORMAD2 peptides; mutagenesis; cell-based HR and MMR reporter assays\",\n      \"pmids\": [\"37794593\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo meiotic consequence of disrupting the specific binding interface was not tested\", \"Whether HORMAD2 plays a direct role in somatic HR/MMR or acts only through HORMAD1 was unclear\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Knockin mouse studies demonstrated that the N-terminal region of HORMAD2 is critical for TRIP13-mediated removal from synapsed axes: N-terminal tagging caused ectopic HORMAD2 persistence on synapsed regions and relocalization to the SC central region, and identified HORMAD1 and SYCP2 as HORMAD2-associated proteins by co-IP/MS.\",\n      \"evidence\": \"N-terminal 3×FLAG-HA tagging knockin mouse; co-immunoprecipitation with mass spectrometry; super-resolution microscopy; sperm count analysis\",\n      \"pmids\": [\"38401263\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether TRIP13 directly engages the HORMAD2 N-terminus or acts through an adaptor (e.g., p31comet) was not resolved\", \"How ectopic HORMAD2 relocates to the central region of the SC was mechanistically unclear\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Retained HORMAD1/2 on synapsed axes (via TRIP13 depletion) recruit BRCA1 to trigger the asynapsis checkpoint and oocyte elimination; HORMAD1 binds BRCA1 via a HORMA domain interface near its N-terminus, while HORMAD2 contributes to BRCA1 recruitment. N-terminal tagging of either HORMAD blocks BRCA1 recruitment and oocyte elimination, explaining why tagged HORMAD2 persistence is not toxic.\",\n      \"evidence\": \"Co-immunoprecipitation; TRIP13-depletion and N-terminal tagging knockin mice; oocyte elimination assays; HORMAD1 mutagenesis\",\n      \"pmids\": [\"40050306\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct versus indirect contribution of HORMAD2 to BRCA1 recruitment not fully separated from HORMAD1\", \"Structural basis of the HORMAD1–BRCA1 interface not determined\", \"Whether HORMAD2 contacts additional checkpoint effectors beyond BRCA1 and ATR is unknown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Double-mutant analysis confirmed that HORMAD2 is specifically required for asynapsis-induced (Spo11-dependent) but not DNA damage-induced (Dmc1-dependent) oocyte apoptosis, reinforcing the pathway specificity first observed in 2012.\",\n      \"evidence\": \"Hormad2/Spo11 and Hormad2/Dmc1 double-mutant mice; immunohistochemical apoptosis assay on perinatal ovaries\",\n      \"pmids\": [\"39961811\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular distinction between asynapsis and DNA damage checkpoint signaling downstream of HORMAD2 not fully elucidated\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key open questions include: whether TRIP13 directly engages the HORMAD2 N-terminus or acts through an adaptor such as p31comet; the identity and functional significance of specific HORMAD2 phosphorylation sites; and whether HORMAD2 has checkpoint effector functions independent of HORMAD1.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Direct TRIP13–HORMAD2 physical interaction and structural basis not demonstrated\", \"Specific phosphorylation sites on HORMAD2 and their individual contributions to ATR signaling not mapped\", \"Whether HORMAD2 has HORMAD1-independent roles in meiotic surveillance or recombination control remains untested\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\n        \"term_id\": \"GO:0060090\",\n        \"supporting_discovery_ids\": [4, 9, 10]\n      }\n    ],\n    \"localization\": [\n      {\n        \"term_id\": \"GO:0005694\",\n        \"supporting_discovery_ids\": [0, 1, 2, 6, 10]\n      },\n      {\n        \"term_id\": \"GO:0005634\",\n        \"supporting_discovery_ids\": [0, 1, 6]\n      }\n    ],\n    \"pathway\": [\n      {\n        \"term_id\": \"R-HSA-1640170\",\n        \"supporting_discovery_ids\": [0, 1, 5, 10]\n      },\n      {\n        \"term_id\": \"R-HSA-73894\",\n        \"supporting_discovery_ids\": [5, 9]\n      },\n      {\n        \"term_id\": \"R-HSA-5357801\",\n        \"supporting_discovery_ids\": [1, 2, 11, 12]\n      }\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"HORMAD1\",\n      \"TRIP13\",\n      \"ATR\",\n      \"BRCA1\",\n      \"SYCP2\",\n      \"RAD1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}