{"gene":"SEPTIN14","run_date":"2026-06-10T07:46:30","timeline":{"discoveries":[{"year":2010,"finding":"SEPT14's C-terminal coiled-coil region interacts with SEPT4, and this interaction is required for cortical neuronal migration; C-terminal deletion mutant of SEPT14 failed to rescue migration defects caused by SEPT14 knockdown. Both SEPT14 and SEPT4 are required for leading process formation in migrating cortical neurons.","method":"In utero electroporation knockdown, rescue experiments with wild-type and C-terminal deletion mutant cDNA, biochemical co-immunoprecipitation","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal biochemical interaction mapping combined with in vivo loss-of-function and domain-deletion rescue, multiple orthogonal methods in one study","pmids":["20181826"],"is_preprint":false},{"year":2007,"finding":"SEPT14 interacts with SEPT9 via yeast two-hybrid and co-immunoprecipitation; the two proteins co-localize when co-expressed in cell lines. SEPT14 was also co-immunoprecipitated from rat testes using SEPT9 antibodies. Yeast two-hybrid analysis further suggested SEPT14 interactions with nine additional septins.","method":"Yeast two-hybrid, co-immunoprecipitation from cell lines and rat testes, co-localization in cell lines","journal":"Mammalian genome : official journal of the International Mammalian Genome Society","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — reciprocal co-IP in two systems (cell lines and native tissue) plus yeast two-hybrid, single lab","pmids":["17922164"],"is_preprint":false},{"year":2019,"finding":"Two missense mutations in SEPT14 (p.Ala123Thr and p.Ile333Thr) impair its polymerization ability in vitro and are associated with severely malformed sperm heads, abnormal chromatin packaging, and high DNA fragmentation in sperm from affected men.","method":"In vitro polymerization assay of mutant vs. wild-type SEPT14, transmission electron microscopy, Toluidine blue staining, comet assay","journal":"Journal of clinical medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro polymerization assay with specific mutations plus multiple structural/functional readouts, single lab","pmids":["31450874"],"is_preprint":false},{"year":2020,"finding":"SEPT14 localizes to the manchette structure in sperm heads and interacts with ACTN4 (an actin-binding protein) in a male germ cell line. SEPT14 co-localizes with ACTN4 in the perinuclear and manchette regions of early elongating spermatids. Mutated SEPT14 (p.Ala123Thr and p.Ile333Thr) disrupts ACTN4 localization, causing mislocalized and fragmented ACTN4 signals and sperm head defects.","method":"Co-immunoprecipitation, nano-LC-MS/MS proteomics, immunostaining, cell model with mutant SEPT14","journal":"Biomedicines","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP validated by mass spectrometry and immunolocalization, with functional consequence shown via mutant SEPT14, single lab","pmids":["33228246"],"is_preprint":false},{"year":2025,"finding":"SEPT14 is expressed at the acroplaxome, manchette, neck, and annulus during spermiogenesis. In the sperm head, SEPT14 interacts and co-localizes with microtubules and actin during manchette formation. In the annulus, SEPT14 interacts with SEPT9, SEPT7, and SEPT2 to form septin filaments; the GTP-binding domain (GBD) of SEPT14 interacts with the GBD of SEPT2, and the C-terminus of SEPT14 interacts with the GBD of SEPT7. Sept14 knockout male mice are subfertile with irregular acrosomes, DNA damage, disorganized mitochondria, displaced annuli, reduced sperm motility, and impaired capacitation.","method":"Sept14 knockout mice generation, immunofluorescence localization, co-immunoprecipitation domain-mapping experiments, sperm functional assays","journal":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — knockout mouse model with defined phenotypes, domain-specific co-IP mapping of multiple septin interactions, multiple orthogonal methods in one study","pmids":["39982757"],"is_preprint":false},{"year":2020,"finding":"SEPT14 protein localizes to the head-to-tail region of normal sperm, with highest concentration at the acrosome front and neck region, as determined by immunocytochemistry.","method":"Immunocytochemistry on human sperm","journal":"Reproductive biology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single localization method (immunocytochemistry), no functional consequence directly linked, single lab","pmids":["32249155"],"is_preprint":false}],"current_model":"SEPT14 is a GTP-binding septin that forms heteromeric complexes with SEPT2, SEPT4, SEPT7, and SEPT9 through defined domain interactions (GBD-GBD and C-terminus-GBD contacts), localizes to the manchette, acroplaxome, neck, and annulus during spermiogenesis, and functions in sperm morphogenesis and cortical neuronal migration by coordinating actin/microtubule-based structures; loss of function or polymerization-disrupting mutations cause sperm head defects (via ACTN4 mislocalization), DNA damage, and impaired sperm motility, while its interaction with SEPT4 via its C-terminal coiled-coil domain is required for neuronal leading process formation and cortical migration."},"narrative":{"mechanistic_narrative":"SEPTIN14 is a GTP-binding septin that assembles into heteromeric septin filaments and organizes actin- and microtubule-based cytoskeletal structures required for sperm morphogenesis and cortical neuronal migration [PMID:39982757, PMID:20181826]. During spermiogenesis it localizes to the acroplaxome, manchette, neck, and annulus, where it interacts and co-localizes with microtubules and actin during manchette formation and assembles into annular septin filaments through defined domain contacts—its GTP-binding domain (GBD) binds the GBD of SEPT2 and its C-terminus binds the GBD of SEPT7 [PMID:39982757]. SEPT14 also associates with SEPT9 and additional septins, consistent with incorporation into broader heteromeric septin complexes [PMID:17922164]. In sperm-head morphogenesis SEPT14 binds the actin-binding protein ACTN4 and recruits it to the perinuclear and manchette regions; polymerization-disrupting missense mutations (p.Ala123Thr and p.Ile333Thr) impair filament assembly, mislocalize and fragment ACTN4, and produce malformed sperm heads with abnormal chromatin packaging and DNA fragmentation [PMID:31450874, PMID:33228246]. Loss of SEPT14 in mice causes subfertility with irregular acrosomes, DNA damage, disorganized mitochondria, displaced annuli, and impaired motility and capacitation [PMID:39982757]. In a parallel role, SEPT14 uses its C-terminal coiled-coil region to bind SEPT4, an interaction required for leading-process formation and cortical migration of neurons [PMID:20181826].","teleology":[{"year":2007,"claim":"Establishing SEPT14 as a bona fide septin required showing it physically associates with known septins; this defined it as a member of heteromeric septin assemblies rather than an isolated protein.","evidence":"Yeast two-hybrid plus reciprocal co-immunoprecipitation in cell lines and rat testes, with co-localization","pmids":["17922164"],"confidence":"Medium","gaps":["Stoichiometry and architecture of the SEPT14-containing complex not resolved","Functional consequence of the SEPT9 interaction not tested","Y2H hits with nine additional septins not validated biochemically"]},{"year":2010,"claim":"It was unknown whether SEPT14 had a role outside the testis; mapping a SEPT4-binding C-terminal coiled-coil and showing its requirement in vivo established a function in cortical neuronal migration.","evidence":"In utero electroporation knockdown with wild-type and C-terminal deletion rescue, plus co-immunoprecipitation","pmids":["20181826"],"confidence":"High","gaps":["Molecular mechanism linking SEPT14-SEPT4 to leading-process cytoskeleton not defined","Whether SEPT14 acts in the same complex with other neuronal septins not addressed"]},{"year":2019,"claim":"Linking SEPT14 to human male infertility required disease alleles; two missense mutations that impair polymerization were tied to severe sperm-head and chromatin defects, establishing polymerization as functionally critical.","evidence":"In vitro polymerization assays of mutant vs wild-type protein, with TEM, Toluidine blue, and comet assay on patient sperm","pmids":["31450874"],"confidence":"Medium","gaps":["Causality in humans is associative, not genetically proven by rescue","How impaired polymerization mechanistically produces chromatin/DNA defects not shown"]},{"year":2020,"claim":"The downstream effector through which SEPT14 shapes the sperm head was unknown; identifying ACTN4 as a partner mislocalized by polymerization-defective SEPT14 connected SEPT14 filaments to actin organization at the manchette.","evidence":"Co-immunoprecipitation with nano-LC-MS/MS, immunostaining, and mutant SEPT14 cell model; complemented by immunocytochemical mapping of SEPT14 to the sperm head-to-tail region","pmids":["33228246","32249155"],"confidence":"Medium","gaps":["Direct vs indirect SEPT14-ACTN4 binding not distinguished","Localization study alone provides no functional readout"]},{"year":2025,"claim":"A definitive loss-of-function model and domain-level interaction map were missing; knockout mice with multi-compartment defects plus GBD/C-terminus mapping established SEPT14 as an architectural organizer of septin filaments across spermiogenesis structures.","evidence":"Sept14 knockout mice with sperm functional assays, immunofluorescence, and domain-specific co-IP mapping of SEPT2/SEPT7/SEPT9 interactions","pmids":["39982757"],"confidence":"High","gaps":["Structural basis of GBD-GBD and C-terminus-GBD contacts not solved","How the same protein coordinates manchette microtubules and annulus filaments not mechanistically separated"]},{"year":null,"claim":"How SEPT14 GTP binding/hydrolysis regulates filament assembly and effector recruitment, and whether its neuronal and germ-cell roles share a common mechanism, remain open.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structure of SEPT14 or its complexes","GTPase cycle not directly characterized","Unified model across spermiogenesis and cortical migration absent"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[3]},{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[2,4]}],"localization":[{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[4]},{"term_id":"GO:0005815","term_label":"microtubule organizing center","supporting_discovery_ids":[4]}],"pathway":[{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[4]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[0]}],"complexes":["heteromeric septin filament"],"partners":["SEPT4","SEPT9","SEPT7","SEPT2","ACTN4"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q6ZU15","full_name":"Septin-14","aliases":[],"length_aa":432,"mass_kda":50.0,"function":"Filament-forming cytoskeletal GTPase (Probable). Involved in the migration of cortical neurons and the formation of neuron leading processes during embryonic development (By similarity). Plays a role in sperm head formation during spermiogenesis, potentially via facilitating localization of ACTN4 to cell filaments (PubMed:33228246)","subcellular_location":"Cytoplasm; Cytoplasm, cytoskeleton; Cell projection, axon; Cell projection, dendrite; Perikaryon; Cytoplasm, perinuclear region; Cytoplasmic vesicle, secretory vesicle, acrosome","url":"https://www.uniprot.org/uniprotkb/Q6ZU15/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SEPTIN14","classification":"Not Classified","n_dependent_lines":88,"n_total_lines":1090,"dependency_fraction":0.08073394495412844},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/SEPTIN14","total_profiled":1310},"omim":[],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"testis","ntpm":21.2}],"url":"https://www.proteinatlas.org/search/SEPTIN14"},"hgnc":{"alias_symbol":["FLJ44060","Septin-14"],"prev_symbol":["SEPT14"]},"alphafold":{"accession":"Q6ZU15","domains":[{"cath_id":"3.40.50.300","chopping":"44-317","consensus_level":"high","plddt":87.7912,"start":44,"end":317},{"cath_id":"1.20.5","chopping":"329-410","consensus_level":"medium","plddt":85.947,"start":329,"end":410}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q6ZU15","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q6ZU15-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q6ZU15-F1-predicted_aligned_error_v6.png","plddt_mean":81.62},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SEPTIN14","jax_strain_url":"https://www.jax.org/strain/search?query=SEPTIN14"},"sequence":{"accession":"Q6ZU15","fasta_url":"https://rest.uniprot.org/uniprotkb/Q6ZU15.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q6ZU15/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q6ZU15"}},"corpus_meta":[{"pmid":"20181826","id":"PMC_20181826","title":"Septin 14 is involved in cortical neuronal migration via interaction with Septin 4.","date":"2010","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/20181826","citation_count":62,"is_preprint":false},{"pmid":"17922164","id":"PMC_17922164","title":"Characterization of a SEPT9 interacting protein, SEPT14, a novel testis-specific septin.","date":"2007","source":"Mammalian genome : official journal of the International Mammalian Genome Society","url":"https://pubmed.ncbi.nlm.nih.gov/17922164","citation_count":44,"is_preprint":false},{"pmid":"31502214","id":"PMC_31502214","title":"Concurrent Identification of Novel EGFR-SEPT14 Fusion and ETV6-RET Fusion in Secretory Carcinoma of the Salivary Gland.","date":"2019","source":"Head and neck pathology","url":"https://pubmed.ncbi.nlm.nih.gov/31502214","citation_count":30,"is_preprint":false},{"pmid":"31450874","id":"PMC_31450874","title":"SEPT14 Mutations and Teratozoospermia: Genetic Effects on Sperm Head Morphology and DNA Integrity.","date":"2019","source":"Journal of clinical medicine","url":"https://pubmed.ncbi.nlm.nih.gov/31450874","citation_count":22,"is_preprint":false},{"pmid":"32162810","id":"PMC_32162810","title":"A Rare EGFR-SEPT14 Fusion in a Patient with Colorectal Adenocarcinoma Responding to Erlotinib.","date":"2019","source":"The oncologist","url":"https://pubmed.ncbi.nlm.nih.gov/32162810","citation_count":16,"is_preprint":false},{"pmid":"32249155","id":"PMC_32249155","title":"Expression and localization of Septin 14 gene and protein in infertile men testis.","date":"2020","source":"Reproductive biology","url":"https://pubmed.ncbi.nlm.nih.gov/32249155","citation_count":12,"is_preprint":false},{"pmid":"33228246","id":"PMC_33228246","title":"ACTN4 Mediates SEPT14 Mutation-Induced Sperm Head Defects.","date":"2020","source":"Biomedicines","url":"https://pubmed.ncbi.nlm.nih.gov/33228246","citation_count":11,"is_preprint":false},{"pmid":"27115672","id":"PMC_27115672","title":"SEPT14 Is Associated with a Reduced Risk for Parkinson's Disease and Expressed in Human Brain.","date":"2016","source":"Journal of molecular neuroscience : MN","url":"https://pubmed.ncbi.nlm.nih.gov/27115672","citation_count":11,"is_preprint":false},{"pmid":"24799881","id":"PMC_24799881","title":"Comparative expression analysis of Septin 14 in testes of infertile men with normal spermatogenesis and spermatogenic failure.","date":"2014","source":"Iranian journal of reproductive medicine","url":"https://pubmed.ncbi.nlm.nih.gov/24799881","citation_count":10,"is_preprint":false},{"pmid":"35571367","id":"PMC_35571367","title":"Effects of Septin-14 Gene Deletion on Adult Cognitive/Emotional Behavior.","date":"2022","source":"Frontiers in molecular neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/35571367","citation_count":6,"is_preprint":false},{"pmid":"39982757","id":"PMC_39982757","title":"SEPT14 complexes maintain sperm morphogenesis and function.","date":"2025","source":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/39982757","citation_count":4,"is_preprint":false},{"pmid":"33969073","id":"PMC_33969073","title":"Detection of EGFR-SEPT14 fusion in cell-free DNA of a patient with advanced gastric cancer: A case report.","date":"2021","source":"World journal of clinical cases","url":"https://pubmed.ncbi.nlm.nih.gov/33969073","citation_count":4,"is_preprint":false},{"pmid":"34486539","id":"PMC_34486539","title":"Complete remission in leptomeningeal metastasis of NSCLC with rare EGFR-SEPT14 fusion treated with osimertinib combined with intrathecal chemotherapy with pemetrexed.","date":"2022","source":"Anti-cancer drugs","url":"https://pubmed.ncbi.nlm.nih.gov/34486539","citation_count":4,"is_preprint":false},{"pmid":"33791027","id":"PMC_33791027","title":"Septin14, a gene specifically expressed in the testis and seminal vesicle of the Banna mini-pig inbred line (BMI).","date":"2021","source":"Animal reproduction","url":"https://pubmed.ncbi.nlm.nih.gov/33791027","citation_count":2,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.10.02.24314823","title":"Unravelling the Impact of Tumor Location on Patient Survival in Glioblastoma: A Genomics and Radiomics Approach","date":"2024-10-04","source":"bioRxiv","url":"https://doi.org/10.1101/2024.10.02.24314823","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9504,"output_tokens":1673,"usd":0.026804,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8480,"output_tokens":2431,"usd":0.051588,"stage2_stop_reason":"end_turn"},"total_usd":0.078392,"stage1_batch_id":"msgbatch_013LWZZT6MWaqB9qyTSeQBmU","stage2_batch_id":"msgbatch_0194ZzQaTGNpruoNJBbEMbt3","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2010,\n      \"finding\": \"SEPT14's C-terminal coiled-coil region interacts with SEPT4, and this interaction is required for cortical neuronal migration; C-terminal deletion mutant of SEPT14 failed to rescue migration defects caused by SEPT14 knockdown. Both SEPT14 and SEPT4 are required for leading process formation in migrating cortical neurons.\",\n      \"method\": \"In utero electroporation knockdown, rescue experiments with wild-type and C-terminal deletion mutant cDNA, biochemical co-immunoprecipitation\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal biochemical interaction mapping combined with in vivo loss-of-function and domain-deletion rescue, multiple orthogonal methods in one study\",\n      \"pmids\": [\"20181826\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"SEPT14 interacts with SEPT9 via yeast two-hybrid and co-immunoprecipitation; the two proteins co-localize when co-expressed in cell lines. SEPT14 was also co-immunoprecipitated from rat testes using SEPT9 antibodies. Yeast two-hybrid analysis further suggested SEPT14 interactions with nine additional septins.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation from cell lines and rat testes, co-localization in cell lines\",\n      \"journal\": \"Mammalian genome : official journal of the International Mammalian Genome Society\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — reciprocal co-IP in two systems (cell lines and native tissue) plus yeast two-hybrid, single lab\",\n      \"pmids\": [\"17922164\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Two missense mutations in SEPT14 (p.Ala123Thr and p.Ile333Thr) impair its polymerization ability in vitro and are associated with severely malformed sperm heads, abnormal chromatin packaging, and high DNA fragmentation in sperm from affected men.\",\n      \"method\": \"In vitro polymerization assay of mutant vs. wild-type SEPT14, transmission electron microscopy, Toluidine blue staining, comet assay\",\n      \"journal\": \"Journal of clinical medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro polymerization assay with specific mutations plus multiple structural/functional readouts, single lab\",\n      \"pmids\": [\"31450874\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"SEPT14 localizes to the manchette structure in sperm heads and interacts with ACTN4 (an actin-binding protein) in a male germ cell line. SEPT14 co-localizes with ACTN4 in the perinuclear and manchette regions of early elongating spermatids. Mutated SEPT14 (p.Ala123Thr and p.Ile333Thr) disrupts ACTN4 localization, causing mislocalized and fragmented ACTN4 signals and sperm head defects.\",\n      \"method\": \"Co-immunoprecipitation, nano-LC-MS/MS proteomics, immunostaining, cell model with mutant SEPT14\",\n      \"journal\": \"Biomedicines\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP validated by mass spectrometry and immunolocalization, with functional consequence shown via mutant SEPT14, single lab\",\n      \"pmids\": [\"33228246\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"SEPT14 is expressed at the acroplaxome, manchette, neck, and annulus during spermiogenesis. In the sperm head, SEPT14 interacts and co-localizes with microtubules and actin during manchette formation. In the annulus, SEPT14 interacts with SEPT9, SEPT7, and SEPT2 to form septin filaments; the GTP-binding domain (GBD) of SEPT14 interacts with the GBD of SEPT2, and the C-terminus of SEPT14 interacts with the GBD of SEPT7. Sept14 knockout male mice are subfertile with irregular acrosomes, DNA damage, disorganized mitochondria, displaced annuli, reduced sperm motility, and impaired capacitation.\",\n      \"method\": \"Sept14 knockout mice generation, immunofluorescence localization, co-immunoprecipitation domain-mapping experiments, sperm functional assays\",\n      \"journal\": \"FASEB journal : official publication of the Federation of American Societies for Experimental Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — knockout mouse model with defined phenotypes, domain-specific co-IP mapping of multiple septin interactions, multiple orthogonal methods in one study\",\n      \"pmids\": [\"39982757\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"SEPT14 protein localizes to the head-to-tail region of normal sperm, with highest concentration at the acrosome front and neck region, as determined by immunocytochemistry.\",\n      \"method\": \"Immunocytochemistry on human sperm\",\n      \"journal\": \"Reproductive biology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single localization method (immunocytochemistry), no functional consequence directly linked, single lab\",\n      \"pmids\": [\"32249155\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SEPT14 is a GTP-binding septin that forms heteromeric complexes with SEPT2, SEPT4, SEPT7, and SEPT9 through defined domain interactions (GBD-GBD and C-terminus-GBD contacts), localizes to the manchette, acroplaxome, neck, and annulus during spermiogenesis, and functions in sperm morphogenesis and cortical neuronal migration by coordinating actin/microtubule-based structures; loss of function or polymerization-disrupting mutations cause sperm head defects (via ACTN4 mislocalization), DNA damage, and impaired sperm motility, while its interaction with SEPT4 via its C-terminal coiled-coil domain is required for neuronal leading process formation and cortical migration.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"SEPTIN14 is a GTP-binding septin that assembles into heteromeric septin filaments and organizes actin- and microtubule-based cytoskeletal structures required for sperm morphogenesis and cortical neuronal migration [#4, #0]. During spermiogenesis it localizes to the acroplaxome, manchette, neck, and annulus, where it interacts and co-localizes with microtubules and actin during manchette formation and assembles into annular septin filaments through defined domain contacts—its GTP-binding domain (GBD) binds the GBD of SEPT2 and its C-terminus binds the GBD of SEPT7 [#4]. SEPT14 also associates with SEPT9 and additional septins, consistent with incorporation into broader heteromeric septin complexes [#1]. In sperm-head morphogenesis SEPT14 binds the actin-binding protein ACTN4 and recruits it to the perinuclear and manchette regions; polymerization-disrupting missense mutations (p.Ala123Thr and p.Ile333Thr) impair filament assembly, mislocalize and fragment ACTN4, and produce malformed sperm heads with abnormal chromatin packaging and DNA fragmentation [#2, #3]. Loss of SEPT14 in mice causes subfertility with irregular acrosomes, DNA damage, disorganized mitochondria, displaced annuli, and impaired motility and capacitation [#4]. In a parallel role, SEPT14 uses its C-terminal coiled-coil region to bind SEPT4, an interaction required for leading-process formation and cortical migration of neurons [#0].\",\n  \"teleology\": [\n    {\n      \"year\": 2007,\n      \"claim\": \"Establishing SEPT14 as a bona fide septin required showing it physically associates with known septins; this defined it as a member of heteromeric septin assemblies rather than an isolated protein.\",\n      \"evidence\": \"Yeast two-hybrid plus reciprocal co-immunoprecipitation in cell lines and rat testes, with co-localization\",\n      \"pmids\": [\"17922164\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Stoichiometry and architecture of the SEPT14-containing complex not resolved\",\n        \"Functional consequence of the SEPT9 interaction not tested\",\n        \"Y2H hits with nine additional septins not validated biochemically\"\n      ]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"It was unknown whether SEPT14 had a role outside the testis; mapping a SEPT4-binding C-terminal coiled-coil and showing its requirement in vivo established a function in cortical neuronal migration.\",\n      \"evidence\": \"In utero electroporation knockdown with wild-type and C-terminal deletion rescue, plus co-immunoprecipitation\",\n      \"pmids\": [\"20181826\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Molecular mechanism linking SEPT14-SEPT4 to leading-process cytoskeleton not defined\",\n        \"Whether SEPT14 acts in the same complex with other neuronal septins not addressed\"\n      ]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Linking SEPT14 to human male infertility required disease alleles; two missense mutations that impair polymerization were tied to severe sperm-head and chromatin defects, establishing polymerization as functionally critical.\",\n      \"evidence\": \"In vitro polymerization assays of mutant vs wild-type protein, with TEM, Toluidine blue, and comet assay on patient sperm\",\n      \"pmids\": [\"31450874\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Causality in humans is associative, not genetically proven by rescue\",\n        \"How impaired polymerization mechanistically produces chromatin/DNA defects not shown\"\n      ]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"The downstream effector through which SEPT14 shapes the sperm head was unknown; identifying ACTN4 as a partner mislocalized by polymerization-defective SEPT14 connected SEPT14 filaments to actin organization at the manchette.\",\n      \"evidence\": \"Co-immunoprecipitation with nano-LC-MS/MS, immunostaining, and mutant SEPT14 cell model; complemented by immunocytochemical mapping of SEPT14 to the sperm head-to-tail region\",\n      \"pmids\": [\"33228246\", \"32249155\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Direct vs indirect SEPT14-ACTN4 binding not distinguished\",\n        \"Localization study alone provides no functional readout\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"A definitive loss-of-function model and domain-level interaction map were missing; knockout mice with multi-compartment defects plus GBD/C-terminus mapping established SEPT14 as an architectural organizer of septin filaments across spermiogenesis structures.\",\n      \"evidence\": \"Sept14 knockout mice with sperm functional assays, immunofluorescence, and domain-specific co-IP mapping of SEPT2/SEPT7/SEPT9 interactions\",\n      \"pmids\": [\"39982757\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Structural basis of GBD-GBD and C-terminus-GBD contacts not solved\",\n        \"How the same protein coordinates manchette microtubules and annulus filaments not mechanistically separated\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How SEPT14 GTP binding/hydrolysis regulates filament assembly and effector recruitment, and whether its neuronal and germ-cell roles share a common mechanism, remain open.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No structure of SEPT14 or its complexes\",\n        \"GTPase cycle not directly characterized\",\n        \"Unified model across spermiogenesis and cortical migration absent\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005525\", \"supporting_discovery_ids\": [4]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [3]},\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [2, 4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [4]},\n      {\"term_id\": \"GO:0005815\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [4]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"complexes\": [\"heteromeric septin filament\"],\n    \"partners\": [\"SEPT4\", \"SEPT9\", \"SEPT7\", \"SEPT2\", \"ACTN4\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}