{"gene":"SYCE3","run_date":"2026-06-10T10:51:54","timeline":{"discoveries":[{"year":2011,"finding":"SYCE3 is a central element (CE) protein of the murine synaptonemal complex (SC) that is required downstream of transverse filament protein SYCP1 but upstream of other CE-specific proteins (SYCE1, SYCE2, TEX12). Loss of SYCE3 in knockout mice blocks synapsis initiation, prevents chromosome loading of other CE proteins, and severely impairs meiotic recombination progression (complete absence of MLH1 foci), causing meiotic arrest and infertility in both sexes.","method":"Syce3 knockout mouse generation, immunofluorescence localization, epistasis analysis by comparing loading of CE proteins in Syce3-null vs. wild-type spermatocytes","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with defined cellular phenotype, epistasis established by examining multiple CE protein loading in null background, replicated across sexes","pmids":["21637789"],"is_preprint":false},{"year":2014,"finding":"Immunoelectron microscopy in mouse spermatocytes showed that the N-terminal region of SYCP1 and SYCE3 co-localize to form a joint bilayered central structure within the SC central region, while SYCE1 and SYCE2 localize between the two layers. Disruption of SYCE2 and TEX12 abolishes central alignment of the SYCP1 N-terminus, indicating all four CE proteins interdependently stabilize the bilayered transverse-filament–central-element junction.","method":"Immunoelectron microscopy with immuno-gold particles, protein interaction data in mouse spermatocytes","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — immunoelectron microscopy with spatial resolution plus protein interaction data; multiple CE proteins examined with genetic disruption controls","pmids":["27103161"],"is_preprint":false},{"year":2014,"finding":"Crystal structure of mouse SYCE3 shows it forms a dimer and higher-order oligomers. The SYCE3 N-helix directly interacts with the SYCE1 C-helix, suggesting helical packing mediates intra- or inter-association of CE protein components.","method":"X-ray crystallography of mouse SYCE3; biochemical interaction assay demonstrating SYCE3 N-helix / SYCE1 C-helix interaction","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure plus direct interaction assay identifying specific interacting helices, single lab","pmids":["25394919"],"is_preprint":false},{"year":2019,"finding":"Solution biophysical analysis (multi-angle light scattering and SAXS) of human SYCE3 revealed it adopts a dimeric four-helical bundle structure that serves as the building block for concentration-dependent self-assembly into discrete higher-order oligomers (up to dodecamers). Self-assembly proceeds through staggered lateral interactions between self-assembly surfaces of dimers and end-on interactions likely involving intermolecular domain swapping.","method":"Multi-angle light scattering (MALS), small-angle X-ray scattering (SAXS)","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — two orthogonal biophysical methods (MALS + SAXS) in a single rigorous study establishing structural and self-assembly mechanism","pmids":["31023827"],"is_preprint":false},{"year":2019,"finding":"During SC disassembly in chicken oocytes, SYCP1 and SYCE3 remain associated with lateral elements at the beginning of chromosomal axis separation and disappear as lateral element separation widens, with no subsequent association at crossover sites. Post-translational modifications of central region components are implicated in initial phases of SC disassembly.","method":"Immunolocalization of SC proteins combined with super-resolution microscopy in chicken oocytes at prophase I","journal":"Chromosoma","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — direct localization experiment with functional implication, single lab, single model organism (avian)","pmids":["30793238"],"is_preprint":false},{"year":2019,"finding":"SCRE (synaptonemal complex reinforcing element) physically interacts with SYCE3 and SYCP1, and its loss destabilizes SCs, indicating SYCE3 is part of a structural network that includes SCRE for reinforcing SC integrity during meiosis prophase I.","method":"Co-immunoprecipitation identifying SCRE–SYCE3 and SCRE–SYCP1 interactions; Scre knockout mouse phenotypic analysis","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP establishing physical interaction plus KO phenotype, single lab","pmids":["30949703"],"is_preprint":false},{"year":2023,"finding":"SYCE3 actively remodels the SYCP1 lattice during synapsis rather than merely stabilizing it. SYCP1 tetramers undergo conformational change into 2:1 SYCP1–SYCE3 heterotrimers upon SYCE3 binding, removing SYCP1 assembly interfaces and disrupting the original SYCP1 lattice. SYCE3 then establishes a new lattice through its own self-assembly, mimicking the disrupted interface to tether SYCP1 dimers together. SYCE3 additionally interacts with CE complexes SYCE1–SIX6OS1 and SYCE2–TEX12, providing a mechanism for their recruitment.","method":"Biochemical reconstitution (in vitro binding and complex assembly assays), separation-of-function mutagenesis in mice, structural analysis","journal":"Nature structural & molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — biochemical reconstitution combined with in vivo separation-of-function mutagenesis in mice and structural characterization, multiple orthogonal methods in a single rigorous study","pmids":["36635604"],"is_preprint":false},{"year":2022,"finding":"Overexpression or knockdown of Syce3 (and Syce1) in mouse Sertoli and Leydig cells activates or suppresses steroidogenic genes Star and Hsd3b, upregulating testosterone synthesis. Syce1 and Syce3 overexpression synergistically promoted each other's protein abundance.","method":"Transfection of recombinant Syce1/Syce3 constructs and siRNA knockdown in Sertoli and Leydig cells; measurement of steroidogenic gene expression and hormone output","journal":"The Journal of steroid biochemistry and molecular biology","confidence":"Medium","confidence_rationale":"Tier 3 / Weak — overexpression and knockdown in cell lines with defined gene expression readouts, single lab, no in vivo validation","pmids":["35697131"],"is_preprint":false}],"current_model":"SYCE3 is a central element protein of the synaptonemal complex that forms dimeric four-helical bundles capable of hierarchical self-assembly; it acts downstream of SYCP1 to actively remodel the SYCP1 tetrameric lattice into a 2:1 SYCP1–SYCE3 heterotrimer-based lattice, removing the original SYCP1 assembly interfaces while establishing a new SYCE3-based lattice that recruits the CE complexes SYCE1–SIX6OS1 and SYCE2–TEX12, and interacts with SYCE1 (via N-helix/C-helix contacts) and SCRE to achieve structural maturation of the SC and enable meiotic recombination and fertility."},"narrative":{"mechanistic_narrative":"SYCE3 is a central element protein of the meiotic synaptonemal complex (SC) that is essential for chromosome synapsis, meiotic recombination, and fertility in both sexes [PMID:21637789]. It acts downstream of the transverse filament protein SYCP1 but upstream of the other central element proteins, and its loss blocks synapsis initiation, prevents chromosome loading of SYCE1, SYCE2, and TEX12, and abolishes meiotic recombination (loss of MLH1 foci), causing meiotic arrest [PMID:21637789]. Structurally, SYCE3 adopts a dimeric four-helical bundle that serves as the building block for concentration-dependent hierarchical self-assembly into higher-order oligomers through staggered lateral and end-on interactions [PMID:31023827]. Rather than passively stabilizing SYCP1, SYCE3 actively remodels the SC lattice: it converts SYCP1 tetramers into 2:1 SYCP1–SYCE3 heterotrimers, removing the original SYCP1 assembly interfaces, and then uses its own self-assembly to build a new lattice that tethers SYCP1 dimers while recruiting the SYCE1–SIX6OS1 and SYCE2–TEX12 complexes [PMID:36635604]. SYCE3 directly contacts SYCE1 through an N-helix/C-helix interaction [PMID:25394919] and engages the SC-reinforcing element SCRE to maintain SC integrity [PMID:30949703], positioning SYCE3 at the core of the central element protein network at the transverse-filament–central-element junction [PMID:27103161].","teleology":[{"year":2011,"claim":"Established SYCE3 as an essential central element protein whose genetic position lies downstream of SYCP1 and upstream of all other CE proteins, defining its role as a gatekeeper for synapsis and recombination.","evidence":"Syce3 knockout mice with immunofluorescence and epistasis analysis of CE protein loading in spermatocytes","pmids":["21637789"],"confidence":"High","gaps":["Does not define the biochemical mechanism by which SYCE3 enables loading of downstream CE proteins","Molecular nature of the SYCP1–SYCE3 functional dependency unresolved"]},{"year":2014,"claim":"Localized SYCE3 to the bilayered central region together with the SYCP1 N-terminus and showed the four CE proteins interdependently stabilize the transverse-filament–central-element junction, building a spatial architecture for the SC.","evidence":"Immunoelectron microscopy with immuno-gold labeling and genetic disruption controls in mouse spermatocytes","pmids":["27103161"],"confidence":"High","gaps":["Static ultrastructural snapshot does not reveal assembly dynamics","Direct binding interfaces between SYCE3 and SYCP1 not defined here"]},{"year":2014,"claim":"Provided the first atomic view of SYCE3, showing it dimerizes and oligomerizes and contacts SYCE1 via a defined N-helix/C-helix interaction, identifying helical packing as the basis for CE protein association.","evidence":"X-ray crystallography of mouse SYCE3 plus biochemical SYCE3–SYCE1 interaction assay","pmids":["25394919"],"confidence":"High","gaps":["Crystallographic oligomers may not reflect physiological assembly state","Functional consequence of the SYCE3–SYCE1 contact not tested in vivo"]},{"year":2019,"claim":"Defined SYCE3's solution architecture as a dimeric four-helical bundle that self-assembles in a concentration-dependent, hierarchical manner, supplying the structural building block for SC lattice formation.","evidence":"Multi-angle light scattering and small-angle X-ray scattering of human SYCE3","pmids":["31023827"],"confidence":"High","gaps":["Self-assembly characterized for isolated SYCE3 without SYCP1 or other CE partners","Domain-swapping model of end-on interactions inferred rather than directly visualized"]},{"year":2019,"claim":"Embedded SYCE3 in a structural network with the SC-reinforcing element SCRE, showing physical interaction and a requirement for SC stability beyond initial assembly.","evidence":"Co-immunoprecipitation of SCRE–SYCE3 and SCRE–SYCP1 plus Scre knockout phenotyping in mice","pmids":["30949703"],"confidence":"Medium","gaps":["Co-IP does not establish a direct binary SYCE3–SCRE contact","Structural basis of reinforcement not defined"]},{"year":2019,"claim":"Tracked SYCE3 behavior during SC disassembly, showing it remains with lateral elements at axis separation and disappears as separation widens, implicating post-translational regulation in central region turnover.","evidence":"Immunolocalization and super-resolution microscopy in chicken oocytes at prophase I","pmids":["30793238"],"confidence":"Medium","gaps":["Single avian model, not confirmed in mammals","Specific post-translational modifications driving disassembly not identified"]},{"year":2022,"claim":"Reported a non-canonical role for SYCE3 in steroidogenesis, where its manipulation in somatic gonadal cells modulates steroidogenic gene expression and testosterone output and synergizes with SYCE1.","evidence":"Overexpression and siRNA knockdown of Syce3 in Sertoli and Leydig cell lines with steroidogenic gene and hormone readouts","pmids":["35697131"],"confidence":"Medium","gaps":["Cell-line overexpression/knockdown without in vivo validation","Mechanism linking a meiotic CE protein to steroidogenesis unexplained","Physiological relevance in somatic cells uncertain"]},{"year":2023,"claim":"Resolved how SYCE3 functions mechanistically, showing it actively remodels the SYCP1 lattice into 2:1 SYCP1–SYCE3 heterotrimers and builds a new SYCE3-based lattice that recruits downstream CE complexes, reframing SYCE3 from a stabilizer to an active architect of the SC.","evidence":"Biochemical reconstitution, separation-of-function mutagenesis in mice, and structural analysis","pmids":["36635604"],"confidence":"High","gaps":["Atomic structure of the full SYCE3-based lattice not resolved","Temporal coordination of remodeling with recombination machinery unclear"]},{"year":null,"claim":"How SYCE3-driven lattice remodeling is temporally coordinated with recombination and disassembly, and the structural basis of its recruitment of SYCE1–SIX6OS1 and SYCE2–TEX12, remain open.","evidence":"","pmids":[],"confidence":"High","gaps":["No high-resolution structure of the mature SYCE3–SYCP1–CE lattice","Regulation of disassembly by post-translational modification uncharacterized","Recruitment interfaces for downstream CE complexes not structurally defined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[0,3,6]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[2,5,6]}],"localization":[{"term_id":"GO:0005694","term_label":"chromosome","supporting_discovery_ids":[0,1,4]}],"pathway":[{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[0]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[0]}],"complexes":["synaptonemal complex central element"],"partners":["SYCP1","SYCE1","SYCE2","TEX12","SIX6OS1","SCRE"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"A1L190","full_name":"Synaptonemal complex central element protein 3","aliases":["Testis highly expressed gene 2 protein","THEG-2"],"length_aa":88,"mass_kda":10.6,"function":"Major component of the transverse central element of synaptonemal complexes (SCS), formed between homologous chromosomes during meiotic prophase (PubMed:36635604). Required for the assembly of the central element of the synaptonemal complex during meiosis, via remodeling of SYCP1 lattice structures and promoting recruitment of SYCE2-TEX12 and SYCE1-SIX60S1 complexes (PubMed:36635604). Required for chromosome loading of the central element-specific SCS proteins, and for initiating synapsis between homologous chromosomes (By similarity). Chromosome loading appears to require SYCP1 (By similarity). Required for fertility and normal testis development (By similarity)","subcellular_location":"Nucleus; Chromosome","url":"https://www.uniprot.org/uniprotkb/A1L190/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SYCE3","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/SYCE3","total_profiled":1310},"omim":[{"mim_id":"618968","title":"CHROMOSOME 1 OPEN READING FRAME 146; C1ORF146","url":"https://www.omim.org/entry/618968"},{"mim_id":"617307","title":"CHROMOSOME 14 OPEN READING FRAME 39; C14ORF39","url":"https://www.omim.org/entry/617307"},{"mim_id":"615775","title":"SYNAPTONEMAL COMPLEX CENTRAL ELEMENT PROTEIN 3; SYCE3","url":"https://www.omim.org/entry/615775"},{"mim_id":"611486","title":"SYNAPTONEMAL COMPLEX CENTRAL ELEMENT PROTEIN 1; SYCE1","url":"https://www.omim.org/entry/611486"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Nucleoli","reliability":"Approved"},{"location":"Golgi apparatus","reliability":"Approved"}],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"testis","ntpm":133.4}],"url":"https://www.proteinatlas.org/search/SYCE3"},"hgnc":{"alias_symbol":[],"prev_symbol":["C22orf41"]},"alphafold":{"accession":"A1L190","domains":[{"cath_id":"1.20.5","chopping":"2-52","consensus_level":"medium","plddt":91.9002,"start":2,"end":52},{"cath_id":"1.20.5","chopping":"54-88","consensus_level":"medium","plddt":94.0571,"start":54,"end":88}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/A1L190","model_url":"https://alphafold.ebi.ac.uk/files/AF-A1L190-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-A1L190-F1-predicted_aligned_error_v6.png","plddt_mean":93.56},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SYCE3","jax_strain_url":"https://www.jax.org/strain/search?query=SYCE3"},"sequence":{"accession":"A1L190","fasta_url":"https://rest.uniprot.org/uniprotkb/A1L190.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/A1L190/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/A1L190"}},"corpus_meta":[{"pmid":"21637789","id":"PMC_21637789","title":"A novel mouse synaptonemal complex protein is essential for loading of central element proteins, recombination, and fertility.","date":"2011","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/21637789","citation_count":158,"is_preprint":false},{"pmid":"28149327","id":"PMC_28149327","title":"In utero exposure to maternal smoking is associated with DNA methylation alterations and reduced neuronal content in the developing fetal brain.","date":"2017","source":"Epigenetics & chromatin","url":"https://pubmed.ncbi.nlm.nih.gov/28149327","citation_count":67,"is_preprint":false},{"pmid":"30607510","id":"PMC_30607510","title":"Molecular structure of human synaptonemal complex protein SYCE1.","date":"2019","source":"Chromosoma","url":"https://pubmed.ncbi.nlm.nih.gov/30607510","citation_count":37,"is_preprint":false},{"pmid":"27103161","id":"PMC_27103161","title":"The central element of the synaptonemal complex in mice is organized as a bilayered junction structure.","date":"2016","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/27103161","citation_count":35,"is_preprint":false},{"pmid":"31023827","id":"PMC_31023827","title":"A molecular model for self-assembly of the synaptonemal complex protein SYCE3.","date":"2019","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/31023827","citation_count":29,"is_preprint":false},{"pmid":"25394919","id":"PMC_25394919","title":"Structural insight into the central element assembly of the synaptonemal complex.","date":"2014","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/25394919","citation_count":24,"is_preprint":false},{"pmid":"36635604","id":"PMC_36635604","title":"Structural maturation of SYCP1-mediated meiotic chromosome synapsis by SYCE3.","date":"2023","source":"Nature structural & molecular 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genomics","url":"https://pubmed.ncbi.nlm.nih.gov/39885385","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10431,"output_tokens":2168,"usd":0.031906,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9212,"output_tokens":3019,"usd":0.060768,"stage2_stop_reason":"end_turn"},"total_usd":0.092674,"stage1_batch_id":"msgbatch_017qqVz33Ga63SCDwzb35XPb","stage2_batch_id":"msgbatch_01Scr2Ei9x4HJMiRGxwrmvLK","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2011,\n      \"finding\": \"SYCE3 is a central element (CE) protein of the murine synaptonemal complex (SC) that is required downstream of transverse filament protein SYCP1 but upstream of other CE-specific proteins (SYCE1, SYCE2, TEX12). Loss of SYCE3 in knockout mice blocks synapsis initiation, prevents chromosome loading of other CE proteins, and severely impairs meiotic recombination progression (complete absence of MLH1 foci), causing meiotic arrest and infertility in both sexes.\",\n      \"method\": \"Syce3 knockout mouse generation, immunofluorescence localization, epistasis analysis by comparing loading of CE proteins in Syce3-null vs. wild-type spermatocytes\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with defined cellular phenotype, epistasis established by examining multiple CE protein loading in null background, replicated across sexes\",\n      \"pmids\": [\"21637789\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Immunoelectron microscopy in mouse spermatocytes showed that the N-terminal region of SYCP1 and SYCE3 co-localize to form a joint bilayered central structure within the SC central region, while SYCE1 and SYCE2 localize between the two layers. Disruption of SYCE2 and TEX12 abolishes central alignment of the SYCP1 N-terminus, indicating all four CE proteins interdependently stabilize the bilayered transverse-filament–central-element junction.\",\n      \"method\": \"Immunoelectron microscopy with immuno-gold particles, protein interaction data in mouse spermatocytes\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — immunoelectron microscopy with spatial resolution plus protein interaction data; multiple CE proteins examined with genetic disruption controls\",\n      \"pmids\": [\"27103161\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Crystal structure of mouse SYCE3 shows it forms a dimer and higher-order oligomers. The SYCE3 N-helix directly interacts with the SYCE1 C-helix, suggesting helical packing mediates intra- or inter-association of CE protein components.\",\n      \"method\": \"X-ray crystallography of mouse SYCE3; biochemical interaction assay demonstrating SYCE3 N-helix / SYCE1 C-helix interaction\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure plus direct interaction assay identifying specific interacting helices, single lab\",\n      \"pmids\": [\"25394919\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Solution biophysical analysis (multi-angle light scattering and SAXS) of human SYCE3 revealed it adopts a dimeric four-helical bundle structure that serves as the building block for concentration-dependent self-assembly into discrete higher-order oligomers (up to dodecamers). Self-assembly proceeds through staggered lateral interactions between self-assembly surfaces of dimers and end-on interactions likely involving intermolecular domain swapping.\",\n      \"method\": \"Multi-angle light scattering (MALS), small-angle X-ray scattering (SAXS)\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — two orthogonal biophysical methods (MALS + SAXS) in a single rigorous study establishing structural and self-assembly mechanism\",\n      \"pmids\": [\"31023827\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"During SC disassembly in chicken oocytes, SYCP1 and SYCE3 remain associated with lateral elements at the beginning of chromosomal axis separation and disappear as lateral element separation widens, with no subsequent association at crossover sites. Post-translational modifications of central region components are implicated in initial phases of SC disassembly.\",\n      \"method\": \"Immunolocalization of SC proteins combined with super-resolution microscopy in chicken oocytes at prophase I\",\n      \"journal\": \"Chromosoma\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — direct localization experiment with functional implication, single lab, single model organism (avian)\",\n      \"pmids\": [\"30793238\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"SCRE (synaptonemal complex reinforcing element) physically interacts with SYCE3 and SYCP1, and its loss destabilizes SCs, indicating SYCE3 is part of a structural network that includes SCRE for reinforcing SC integrity during meiosis prophase I.\",\n      \"method\": \"Co-immunoprecipitation identifying SCRE–SYCE3 and SCRE–SYCP1 interactions; Scre knockout mouse phenotypic analysis\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP establishing physical interaction plus KO phenotype, single lab\",\n      \"pmids\": [\"30949703\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"SYCE3 actively remodels the SYCP1 lattice during synapsis rather than merely stabilizing it. SYCP1 tetramers undergo conformational change into 2:1 SYCP1–SYCE3 heterotrimers upon SYCE3 binding, removing SYCP1 assembly interfaces and disrupting the original SYCP1 lattice. SYCE3 then establishes a new lattice through its own self-assembly, mimicking the disrupted interface to tether SYCP1 dimers together. SYCE3 additionally interacts with CE complexes SYCE1–SIX6OS1 and SYCE2–TEX12, providing a mechanism for their recruitment.\",\n      \"method\": \"Biochemical reconstitution (in vitro binding and complex assembly assays), separation-of-function mutagenesis in mice, structural analysis\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — biochemical reconstitution combined with in vivo separation-of-function mutagenesis in mice and structural characterization, multiple orthogonal methods in a single rigorous study\",\n      \"pmids\": [\"36635604\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Overexpression or knockdown of Syce3 (and Syce1) in mouse Sertoli and Leydig cells activates or suppresses steroidogenic genes Star and Hsd3b, upregulating testosterone synthesis. Syce1 and Syce3 overexpression synergistically promoted each other's protein abundance.\",\n      \"method\": \"Transfection of recombinant Syce1/Syce3 constructs and siRNA knockdown in Sertoli and Leydig cells; measurement of steroidogenic gene expression and hormone output\",\n      \"journal\": \"The Journal of steroid biochemistry and molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Weak — overexpression and knockdown in cell lines with defined gene expression readouts, single lab, no in vivo validation\",\n      \"pmids\": [\"35697131\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SYCE3 is a central element protein of the synaptonemal complex that forms dimeric four-helical bundles capable of hierarchical self-assembly; it acts downstream of SYCP1 to actively remodel the SYCP1 tetrameric lattice into a 2:1 SYCP1–SYCE3 heterotrimer-based lattice, removing the original SYCP1 assembly interfaces while establishing a new SYCE3-based lattice that recruits the CE complexes SYCE1–SIX6OS1 and SYCE2–TEX12, and interacts with SYCE1 (via N-helix/C-helix contacts) and SCRE to achieve structural maturation of the SC and enable meiotic recombination and fertility.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"SYCE3 is a central element protein of the meiotic synaptonemal complex (SC) that is essential for chromosome synapsis, meiotic recombination, and fertility in both sexes [#0]. It acts downstream of the transverse filament protein SYCP1 but upstream of the other central element proteins, and its loss blocks synapsis initiation, prevents chromosome loading of SYCE1, SYCE2, and TEX12, and abolishes meiotic recombination (loss of MLH1 foci), causing meiotic arrest [#0]. Structurally, SYCE3 adopts a dimeric four-helical bundle that serves as the building block for concentration-dependent hierarchical self-assembly into higher-order oligomers through staggered lateral and end-on interactions [#3]. Rather than passively stabilizing SYCP1, SYCE3 actively remodels the SC lattice: it converts SYCP1 tetramers into 2:1 SYCP1\\u2013SYCE3 heterotrimers, removing the original SYCP1 assembly interfaces, and then uses its own self-assembly to build a new lattice that tethers SYCP1 dimers while recruiting the SYCE1\\u2013SIX6OS1 and SYCE2\\u2013TEX12 complexes [#6]. SYCE3 directly contacts SYCE1 through an N-helix/C-helix interaction [#2] and engages the SC-reinforcing element SCRE to maintain SC integrity [#5], positioning SYCE3 at the core of the central element protein network at the transverse-filament\\u2013central-element junction [#1].\",\n  \"teleology\": [\n    {\n      \"year\": 2011,\n      \"claim\": \"Established SYCE3 as an essential central element protein whose genetic position lies downstream of SYCP1 and upstream of all other CE proteins, defining its role as a gatekeeper for synapsis and recombination.\",\n      \"evidence\": \"Syce3 knockout mice with immunofluorescence and epistasis analysis of CE protein loading in spermatocytes\",\n      \"pmids\": [\"21637789\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not define the biochemical mechanism by which SYCE3 enables loading of downstream CE proteins\", \"Molecular nature of the SYCP1\\u2013SYCE3 functional dependency unresolved\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Localized SYCE3 to the bilayered central region together with the SYCP1 N-terminus and showed the four CE proteins interdependently stabilize the transverse-filament\\u2013central-element junction, building a spatial architecture for the SC.\",\n      \"evidence\": \"Immunoelectron microscopy with immuno-gold labeling and genetic disruption controls in mouse spermatocytes\",\n      \"pmids\": [\"27103161\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Static ultrastructural snapshot does not reveal assembly dynamics\", \"Direct binding interfaces between SYCE3 and SYCP1 not defined here\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Provided the first atomic view of SYCE3, showing it dimerizes and oligomerizes and contacts SYCE1 via a defined N-helix/C-helix interaction, identifying helical packing as the basis for CE protein association.\",\n      \"evidence\": \"X-ray crystallography of mouse SYCE3 plus biochemical SYCE3\\u2013SYCE1 interaction assay\",\n      \"pmids\": [\"25394919\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Crystallographic oligomers may not reflect physiological assembly state\", \"Functional consequence of the SYCE3\\u2013SYCE1 contact not tested in vivo\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Defined SYCE3's solution architecture as a dimeric four-helical bundle that self-assembles in a concentration-dependent, hierarchical manner, supplying the structural building block for SC lattice formation.\",\n      \"evidence\": \"Multi-angle light scattering and small-angle X-ray scattering of human SYCE3\",\n      \"pmids\": [\"31023827\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Self-assembly characterized for isolated SYCE3 without SYCP1 or other CE partners\", \"Domain-swapping model of end-on interactions inferred rather than directly visualized\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Embedded SYCE3 in a structural network with the SC-reinforcing element SCRE, showing physical interaction and a requirement for SC stability beyond initial assembly.\",\n      \"evidence\": \"Co-immunoprecipitation of SCRE\\u2013SYCE3 and SCRE\\u2013SYCP1 plus Scre knockout phenotyping in mice\",\n      \"pmids\": [\"30949703\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Co-IP does not establish a direct binary SYCE3\\u2013SCRE contact\", \"Structural basis of reinforcement not defined\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Tracked SYCE3 behavior during SC disassembly, showing it remains with lateral elements at axis separation and disappears as separation widens, implicating post-translational regulation in central region turnover.\",\n      \"evidence\": \"Immunolocalization and super-resolution microscopy in chicken oocytes at prophase I\",\n      \"pmids\": [\"30793238\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single avian model, not confirmed in mammals\", \"Specific post-translational modifications driving disassembly not identified\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Reported a non-canonical role for SYCE3 in steroidogenesis, where its manipulation in somatic gonadal cells modulates steroidogenic gene expression and testosterone output and synergizes with SYCE1.\",\n      \"evidence\": \"Overexpression and siRNA knockdown of Syce3 in Sertoli and Leydig cell lines with steroidogenic gene and hormone readouts\",\n      \"pmids\": [\"35697131\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Cell-line overexpression/knockdown without in vivo validation\", \"Mechanism linking a meiotic CE protein to steroidogenesis unexplained\", \"Physiological relevance in somatic cells uncertain\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Resolved how SYCE3 functions mechanistically, showing it actively remodels the SYCP1 lattice into 2:1 SYCP1\\u2013SYCE3 heterotrimers and builds a new SYCE3-based lattice that recruits downstream CE complexes, reframing SYCE3 from a stabilizer to an active architect of the SC.\",\n      \"evidence\": \"Biochemical reconstitution, separation-of-function mutagenesis in mice, and structural analysis\",\n      \"pmids\": [\"36635604\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Atomic structure of the full SYCE3-based lattice not resolved\", \"Temporal coordination of remodeling with recombination machinery unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How SYCE3-driven lattice remodeling is temporally coordinated with recombination and disassembly, and the structural basis of its recruitment of SYCE1\\u2013SIX6OS1 and SYCE2\\u2013TEX12, remain open.\",\n      \"evidence\": null,\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No high-resolution structure of the mature SYCE3\\u2013SYCP1\\u2013CE lattice\", \"Regulation of disassembly by post-translational modification uncharacterized\", \"Recruitment interfaces for downstream CE complexes not structurally defined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [0, 3, 6]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [2, 5, 6]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005694\", \"supporting_discovery_ids\": [0, 1, 4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"complexes\": [\"synaptonemal complex central element\"],\n    \"partners\": [\"SYCP1\", \"SYCE1\", \"SYCE2\", \"TEX12\", \"SIX6OS1\", \"SCRE\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}