{"gene":"PMFBP1","run_date":"2026-06-10T06:43:35","timeline":{"discoveries":[{"year":2018,"finding":"PMFBP1 cooperates with SUN5 and SPATA6 at the sperm head-tail junction; disruption of Pmfbp1 in male mice causes infertility due to acephalic spermatozoa and loss of this cooperative interaction, establishing PMFBP1 as a structural scaffold linking the sperm head to the tail.","method":"Pmfbp1 knockout mice (loss-of-function), co-immunoprecipitation/interaction studies with SUN5 and SPATA6, whole-exome sequencing in human patients","journal":"American journal of human genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — KO mouse phenotype with defined cellular consequence, protein interaction studies, replicated in human patients; independent replication by second paper (PMID:30298696)","pmids":["30032984"],"is_preprint":false},{"year":2018,"finding":"PMFBP1 localizes to the head-flagella junction region of sperm, and its absence (in patients with biallelic truncating mutations) is associated with acephalic spermatozoa; Pmfbp1 KO mice recapitulate the phenotype. Label-free quantitative proteomics of KO testicular sperm showed enrichment of differentially expressed proteins in Golgi vesicle transport, suggesting PMFBP1 affects Golgi-related processes during head-neck junction formation.","method":"Immunofluorescence staining for localization, Pmfbp1 knockout mouse generation, label-free quantitative proteomics of testicular sperm","journal":"Clinical genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct localization by immunofluorescence with functional consequence (KO phenotype), proteomics, replicates findings from PMID:30032984","pmids":["30298696"],"is_preprint":false},{"year":2023,"finding":"PMFBP1 interacts with HDAC3 and CCT3 (chaperonin-containing TCP1 subunit 3); loss of Pmfbp1 in mice reduces HDAC3 expression, which in turn downregulates RNF151 and RNF133, defining a PMFBP1–CCT3–HDAC3–RNF151/RNF133 molecular axis during spermatogenesis.","method":"Immunoprecipitation combined with mass spectrometry (IP-MS), co-immunoprecipitation, immunoblotting, immunohistochemistry, RT-qPCR, proteomics and transcriptomics of Pmfbp1-/- mouse testis","journal":"Journal of assisted reproduction and genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — IP-MS plus co-IP plus KO mouse phenotype in a single lab; multiple orthogonal methods but not independently replicated","pmids":["37423931"],"is_preprint":false},{"year":2021,"finding":"A homozygous missense mutation in PMFBP1 (c.301A>C, p.T101P) causes reduced PMFBP1 protein expression in sperm, confirmed by Western blotting of patient sperm and in vitro expression of the mutant construct, demonstrating that missense mutations can destabilize PMFBP1 protein.","method":"Western blotting of patient sperm, immunofluorescence, in vitro expression of mutant PMFBP1 construct","journal":"Journal of assisted reproduction and genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Western blot of patient sperm plus in vitro mutant expression, single lab, two orthogonal methods","pmids":["33484382"],"is_preprint":false},{"year":2022,"finding":"Truncating mutations in PMFBP1 reduce expression of outer dense fiber proteins ODF1 and ODF2, indicating PMFBP1 regulates ODF1/ODF2 expression as part of sperm tail structural assembly.","method":"Western blotting of sperm from patient with compound heterozygous PMFBP1 mutations","journal":"Molecular genetics & genomic medicine","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, single method (Western blot), no orthogonal validation","pmids":["35860846"],"is_preprint":false},{"year":2024,"finding":"CEP250 physically interacts with SUN5 and PMFBP1 at the sperm neck region; a loss-of-function mutation in CEP250 reduces this interaction, placing CEP250 in the same head-neck junction complex as PMFBP1.","method":"Co-immunoprecipitation, immunofluorescence, CRISPR-Cas9 knock-in mice","journal":"Andrology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP showing interaction between CEP250 and PMFBP1/SUN5, supported by in vivo mouse model; single lab","pmids":["39726222"],"is_preprint":false},{"year":2025,"finding":"A nonsense mutation in PMFBP1 (c.2641C>T, p.Arg881Ter) produces a truncated protein with significantly altered stability (assessed by cycloheximide chase and MG132 proteasome inhibitor assays), causing absence of PMFBP1 in sperm and acephalic spermatozoa syndrome.","method":"Western blot, cycloheximide chase assay, MG132 proteasome inhibitor assay, Sanger sequencing, transmission electron microscopy","journal":"Biomedicines","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — protein stability mechanistically dissected with CHX/MG132 assays, single lab, multiple orthogonal methods","pmids":["41462896"],"is_preprint":false},{"year":2024,"finding":"A homozygous splice site mutation (c.2089-1G>T) in PMFBP1 causes deletion of 4 bp from exon 15, abolishing PMFBP1 protein expression in sperm, confirmed by in vitro splicing model, RT-PCR and Sanger sequencing.","method":"Western blotting, immunofluorescence, in vitro splice-site mutation model, RT-PCR, Sanger sequencing","journal":"Basic and clinical andrology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro splicing model with RT-PCR validation plus patient sperm Western blot; single lab, two orthogonal methods","pmids":["39668357"],"is_preprint":false},{"year":2025,"finding":"Loss of CCDC188 protein in patients is accompanied by co-depletion of SUN5 and PMFBP1 in sperm, suggesting CCDC188 functions in the same structural complex at the sperm head-neck junction as PMFBP1.","method":"Western blotting and immunofluorescence of patient sperm","journal":"Journal of assisted reproduction and genetics","confidence":"Low","confidence_rationale":"Tier 3 / Weak — co-depletion observed in patient sperm by Western blot/IF; no direct interaction assay performed for PMFBP1 specifically; single lab, single method","pmids":["41004021"],"is_preprint":false}],"current_model":"PMFBP1 is a testis-specific scaffold protein that localizes to the sperm head-neck junction, where it cooperates with SUN5, SPATA6, and CEP250 to physically connect the sperm head to the tail; loss-of-function mutations cause acephalic spermatozoa syndrome in both humans and mice, and mechanistically PMFBP1 interacts with the chaperone CCT3 to maintain HDAC3 expression, which in turn regulates downstream spermatogenic factors RNF151 and RNF133, while its absence also reduces expression of the structural proteins ODF1 and ODF2."},"narrative":{"mechanistic_narrative":"PMFBP1 is a testis-specific scaffold protein of the sperm head-neck junction that physically couples the sperm head to the flagellum, and its loss causes acephalic spermatozoa syndrome in both humans and mice [PMID:30032984, PMID:30298696]. At this junction it cooperates with SUN5 and SPATA6, and integrates into a multiprotein head-neck complex that also includes CEP250, whose own interaction with PMFBP1/SUN5 is lost upon CEP250 disruption [PMID:30032984, PMID:39726222]. Beyond its structural role, PMFBP1 acts in a regulatory axis during spermatogenesis: it associates with the chaperonin subunit CCT3 and with HDAC3, and its loss reduces HDAC3 expression with downstream downregulation of the E3 ligase factors RNF151 and RNF133 [PMID:37423931]. Disease-causing alleles — missense, nonsense, splice-site, and truncating mutations — converge mechanistically on destabilization or loss of PMFBP1 protein in sperm [PMID:33484382, PMID:41462896, PMID:39668357], establishing PMFBP1 as a causative gene for acephalic spermatozoa syndrome.","teleology":[{"year":2018,"claim":"Established PMFBP1 as a structural scaffold at the sperm head-tail junction by showing it cooperates with SUN5 and SPATA6 and that its loss produces acephalic spermatozoa, defining a molecular basis for head-tail decapitation.","evidence":"Pmfbp1 knockout mice, co-IP with SUN5/SPATA6, and whole-exome sequencing of human patients, with independent immunofluorescence localization and KO replication plus proteomics","pmids":["30032984","30298696"],"confidence":"High","gaps":["Direct binding interfaces/stoichiometry of the SUN5-SPATA6-PMFBP1 assembly not resolved","Mechanism connecting PMFBP1 loss to Golgi vesicle transport changes unclear"]},{"year":2023,"claim":"Extended PMFBP1 from a purely structural protein to a node in a gene-regulatory axis by identifying CCT3 and HDAC3 as interactors and linking PMFBP1 loss to reduced HDAC3 and downstream RNF151/RNF133.","evidence":"IP-MS, co-IP, immunoblotting, RT-qPCR, and proteomics/transcriptomics of Pmfbp1-/- mouse testis (single lab)","pmids":["37423931"],"confidence":"Medium","gaps":["Not independently replicated","Direct vs indirect nature of the PMFBP1-HDAC3 functional link unresolved","How a junction scaffold modulates HDAC3 levels mechanistically unknown"]},{"year":2024,"claim":"Placed CEP250 in the same head-neck junction complex as PMFBP1, broadening the membership of the structural assembly.","evidence":"Reciprocal co-IP, immunofluorescence, and CRISPR-Cas9 knock-in mice (single lab)","pmids":["39726222"],"confidence":"Medium","gaps":["Whether CEP250 binds PMFBP1 directly or via SUN5 not established","Spatial architecture of the full complex unknown"]},{"year":2025,"claim":"Defined how disease alleles act mechanistically, showing missense, nonsense, splice-site, and truncating mutations destabilize or abolish PMFBP1 protein in sperm.","evidence":"Western blot of patient sperm, in vitro mutant expression, cycloheximide chase, MG132 proteasome assays, and in vitro splicing models across multiple patient studies","pmids":["33484382","41462896","39668357"],"confidence":"Medium","gaps":["Each allele characterized in a single lab","Genotype-phenotype correlation across mutation classes not systematized"]},{"year":2025,"claim":"Implicated additional partners (ODF1/ODF2, CCDC188) by co-depletion, hinting at broader structural dependencies but without direct interaction proof for PMFBP1.","evidence":"Western blotting and immunofluorescence of patient sperm","pmids":["35860846","41004021"],"confidence":"Low","gaps":["No direct PMFBP1 interaction assay performed for CCDC188 or ODF1/ODF2","Single method (Western/IF), no orthogonal validation","Cause vs consequence of expression changes unclear"]},{"year":null,"claim":"The structural architecture and biochemical mechanism by which PMFBP1 simultaneously scaffolds the head-neck junction and influences HDAC3-dependent gene regulation remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of the PMFBP1-containing junction complex","Direct binding partners vs co-dependent proteins not fully distinguished","Mechanism coupling structural scaffolding to transcriptional/regulatory output unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[0,1]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,5]}],"localization":[],"pathway":[{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[0,1]}],"complexes":["sperm head-neck junction complex"],"partners":["SUN5","SPATA6","CEP250","CCT3","HDAC3"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q8TBY8","full_name":"Polyamine-modulated factor 1-binding protein 1","aliases":[],"length_aa":1007,"mass_kda":117.5,"function":"Required for normal spermatogenesis (PubMed:1770140, PubMed:30032984, PubMed:30298696). It functions as a scaffold protein that attaches the sperm head-tail connecting piece to the nuclear envelope, thus maintaining sperm head and tail integrity (PubMed:30032984). May also be involved in the general organization of cellular cytoskeleton (By similarity)","subcellular_location":"Cell projection, cilium, flagellum","url":"https://www.uniprot.org/uniprotkb/Q8TBY8/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/PMFBP1","classification":"Not Classified","n_dependent_lines":3,"n_total_lines":1208,"dependency_fraction":0.0024834437086092716},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/PMFBP1","total_profiled":1310},"omim":[{"mim_id":"618112","title":"SPERMATOGENIC FAILURE 31; SPGF31","url":"https://www.omim.org/entry/618112"},{"mim_id":"618085","title":"POLYAMINE-MODULATED FACTOR 1-BINDING PROTEIN 1; PMFBP1","url":"https://www.omim.org/entry/618085"},{"mim_id":"258150","title":"SPERMATOGENIC FAILURE 1; SPGF1","url":"https://www.omim.org/entry/258150"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Uncertain","locations":[{"location":"Nucleoplasm","reliability":"Uncertain"},{"location":"Connecting piece","reliability":"Uncertain"},{"location":"Cell Junctions","reliability":"Additional"},{"location":"Acrosome","reliability":"Additional"},{"location":"Flagellar centriole","reliability":"Additional"},{"location":"Mid piece","reliability":"Additional"},{"location":"Principal piece","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"epididymis","ntpm":12.7},{"tissue":"testis","ntpm":20.0}],"url":"https://www.proteinatlas.org/search/PMFBP1"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"Q8TBY8","domains":[],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TBY8","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TBY8-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TBY8-F1-predicted_aligned_error_v6.png","plddt_mean":77.38},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PMFBP1","jax_strain_url":"https://www.jax.org/strain/search?query=PMFBP1"},"sequence":{"accession":"Q8TBY8","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8TBY8.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8TBY8/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TBY8"}},"corpus_meta":[{"pmid":"30032984","id":"PMC_30032984","title":"Mutations in PMFBP1 Cause Acephalic Spermatozoa Syndrome.","date":"2018","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/30032984","citation_count":97,"is_preprint":false},{"pmid":"22170508","id":"PMC_22170508","title":"Increased recycling of polyamines is associated with global DNA hypomethylation in rheumatoid arthritis synovial fibroblasts.","date":"2011","source":"Arthritis and rheumatism","url":"https://pubmed.ncbi.nlm.nih.gov/22170508","citation_count":94,"is_preprint":false},{"pmid":"30298696","id":"PMC_30298696","title":"Biallelic mutations in PMFBP1 cause acephalic spermatozoa.","date":"2018","source":"Clinical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/30298696","citation_count":45,"is_preprint":false},{"pmid":"35546142","id":"PMC_35546142","title":"Meta-analysis of sub-Saharan African studies provides insights into genetic architecture of lipid traits.","date":"2022","source":"Nature 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1987)","url":"https://pubmed.ncbi.nlm.nih.gov/38061432","citation_count":26,"is_preprint":false},{"pmid":"35312700","id":"PMC_35312700","title":"BmPMFBP1 regulates the development of eupyrene sperm in the silkworm, Bombyx mori.","date":"2022","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/35312700","citation_count":24,"is_preprint":false},{"pmid":"39417902","id":"PMC_39417902","title":"Genetic etiological spectrum of sperm morphological abnormalities.","date":"2024","source":"Journal of assisted reproduction and genetics","url":"https://pubmed.ncbi.nlm.nih.gov/39417902","citation_count":17,"is_preprint":false},{"pmid":"33452591","id":"PMC_33452591","title":"Genetic basis of acephalic spermatozoa syndrome, and intracytoplasmic sperm injection outcomes in infertile men: a systematic scoping review.","date":"2021","source":"Journal of assisted reproduction and genetics","url":"https://pubmed.ncbi.nlm.nih.gov/33452591","citation_count":15,"is_preprint":false},{"pmid":"33484382","id":"PMC_33484382","title":"A novel homozygous missense mutation of PMFBP1 causes acephalic spermatozoa syndrome.","date":"2021","source":"Journal of assisted reproduction and genetics","url":"https://pubmed.ncbi.nlm.nih.gov/33484382","citation_count":14,"is_preprint":false},{"pmid":"35860846","id":"PMC_35860846","title":"Novel mutations of PMFBP1 in a man with acephalic spermatozoa defects.","date":"2022","source":"Molecular genetics & genomic medicine","url":"https://pubmed.ncbi.nlm.nih.gov/35860846","citation_count":9,"is_preprint":false},{"pmid":"36579083","id":"PMC_36579083","title":"Compound heterozygous mutations in PMFBP1 cause acephalic spermatozoa syndrome: A case report.","date":"2022","source":"World journal of clinical cases","url":"https://pubmed.ncbi.nlm.nih.gov/36579083","citation_count":6,"is_preprint":false},{"pmid":"37760635","id":"PMC_37760635","title":"Identification of Potentially Novel Molecular Targets of Endometrial Cancer Using a Non-Biased Proteomic Approach.","date":"2023","source":"Cancers","url":"https://pubmed.ncbi.nlm.nih.gov/37760635","citation_count":5,"is_preprint":false},{"pmid":"37423931","id":"PMC_37423931","title":"Loss of PMFBP1 Disturbs Mouse Spermatogenesis by Downregulating HDAC3 Expression.","date":"2023","source":"Journal of assisted reproduction and genetics","url":"https://pubmed.ncbi.nlm.nih.gov/37423931","citation_count":4,"is_preprint":false},{"pmid":"32127052","id":"PMC_32127052","title":"Prevention of multiple system atrophy using human bone marrow-derived mesenchymal stem cells by reducing polyamine and cholesterol-induced neural damages.","date":"2020","source":"Stem cell research & therapy","url":"https://pubmed.ncbi.nlm.nih.gov/32127052","citation_count":4,"is_preprint":false},{"pmid":"39726222","id":"PMC_39726222","title":"A homozygous loss-of-function mutation in CEP250 is associated with acephalic spermatozoa syndrome in humans.","date":"2024","source":"Andrology","url":"https://pubmed.ncbi.nlm.nih.gov/39726222","citation_count":3,"is_preprint":false},{"pmid":"32233213","id":"PMC_32233213","title":"[Advances in the molecular genetic studies of acephalic spermatozoa syndrome].","date":"2019","source":"Zhonghua nan ke xue = National journal of andrology","url":"https://pubmed.ncbi.nlm.nih.gov/32233213","citation_count":3,"is_preprint":false},{"pmid":"39668357","id":"PMC_39668357","title":"Pathogenesis of acephalic spermatozoa syndrome caused by PMFBP1 mutation.","date":"2024","source":"Basic and clinical andrology","url":"https://pubmed.ncbi.nlm.nih.gov/39668357","citation_count":1,"is_preprint":false},{"pmid":"41004021","id":"PMC_41004021","title":"Novel CCDC188 variants cause acephalic spermatozoa syndrome with poor intracytoplasmic sperm injection outcome.","date":"2025","source":"Journal of assisted reproduction and genetics","url":"https://pubmed.ncbi.nlm.nih.gov/41004021","citation_count":1,"is_preprint":false},{"pmid":"35599408","id":"PMC_35599408","title":"[Gender differences of genetic etiology in the incidence of major depressive disorder among Han freshmen].","date":"2022","source":"Zhonghua yi xue za zhi","url":"https://pubmed.ncbi.nlm.nih.gov/35599408","citation_count":1,"is_preprint":false},{"pmid":"41462896","id":"PMC_41462896","title":"A Novel Homozygous Mutation in PMFBP1 Associated with Acephalic Spermatozoa Defects.","date":"2025","source":"Biomedicines","url":"https://pubmed.ncbi.nlm.nih.gov/41462896","citation_count":0,"is_preprint":false},{"pmid":"38818563","id":"PMC_38818563","title":"[Clinical characteristics and genetic analysis of a patient with Acephalic spermatozoa syndrome due to variant of PMFBP1 gene].","date":"2024","source":"Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/38818563","citation_count":0,"is_preprint":false},{"pmid":"41483127","id":"PMC_41483127","title":"Genetic diversity of infertile males in India.","date":"2026","source":"Journal of assisted reproduction and genetics","url":"https://pubmed.ncbi.nlm.nih.gov/41483127","citation_count":0,"is_preprint":false},{"pmid":"40376536","id":"PMC_40376536","title":"Establishment and clinical significance of genetic factor screening method for patients with nonobstructive azoospermia based on whole exon sequencing technology.","date":"2025","source":"Translational andrology and urology","url":"https://pubmed.ncbi.nlm.nih.gov/40376536","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":15180,"output_tokens":2261,"usd":0.039727,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9236,"output_tokens":2093,"usd":0.049252,"stage2_stop_reason":"end_turn"},"total_usd":0.088979,"stage1_batch_id":"msgbatch_01CNoDbkChHEkgrJnL7BwtGJ","stage2_batch_id":"msgbatch_016Y4x9E9Wg5VQDANj9quSQD","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2018,\n      \"finding\": \"PMFBP1 cooperates with SUN5 and SPATA6 at the sperm head-tail junction; disruption of Pmfbp1 in male mice causes infertility due to acephalic spermatozoa and loss of this cooperative interaction, establishing PMFBP1 as a structural scaffold linking the sperm head to the tail.\",\n      \"method\": \"Pmfbp1 knockout mice (loss-of-function), co-immunoprecipitation/interaction studies with SUN5 and SPATA6, whole-exome sequencing in human patients\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — KO mouse phenotype with defined cellular consequence, protein interaction studies, replicated in human patients; independent replication by second paper (PMID:30298696)\",\n      \"pmids\": [\"30032984\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"PMFBP1 localizes to the head-flagella junction region of sperm, and its absence (in patients with biallelic truncating mutations) is associated with acephalic spermatozoa; Pmfbp1 KO mice recapitulate the phenotype. Label-free quantitative proteomics of KO testicular sperm showed enrichment of differentially expressed proteins in Golgi vesicle transport, suggesting PMFBP1 affects Golgi-related processes during head-neck junction formation.\",\n      \"method\": \"Immunofluorescence staining for localization, Pmfbp1 knockout mouse generation, label-free quantitative proteomics of testicular sperm\",\n      \"journal\": \"Clinical genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct localization by immunofluorescence with functional consequence (KO phenotype), proteomics, replicates findings from PMID:30032984\",\n      \"pmids\": [\"30298696\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"PMFBP1 interacts with HDAC3 and CCT3 (chaperonin-containing TCP1 subunit 3); loss of Pmfbp1 in mice reduces HDAC3 expression, which in turn downregulates RNF151 and RNF133, defining a PMFBP1–CCT3–HDAC3–RNF151/RNF133 molecular axis during spermatogenesis.\",\n      \"method\": \"Immunoprecipitation combined with mass spectrometry (IP-MS), co-immunoprecipitation, immunoblotting, immunohistochemistry, RT-qPCR, proteomics and transcriptomics of Pmfbp1-/- mouse testis\",\n      \"journal\": \"Journal of assisted reproduction and genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — IP-MS plus co-IP plus KO mouse phenotype in a single lab; multiple orthogonal methods but not independently replicated\",\n      \"pmids\": [\"37423931\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"A homozygous missense mutation in PMFBP1 (c.301A>C, p.T101P) causes reduced PMFBP1 protein expression in sperm, confirmed by Western blotting of patient sperm and in vitro expression of the mutant construct, demonstrating that missense mutations can destabilize PMFBP1 protein.\",\n      \"method\": \"Western blotting of patient sperm, immunofluorescence, in vitro expression of mutant PMFBP1 construct\",\n      \"journal\": \"Journal of assisted reproduction and genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Western blot of patient sperm plus in vitro mutant expression, single lab, two orthogonal methods\",\n      \"pmids\": [\"33484382\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Truncating mutations in PMFBP1 reduce expression of outer dense fiber proteins ODF1 and ODF2, indicating PMFBP1 regulates ODF1/ODF2 expression as part of sperm tail structural assembly.\",\n      \"method\": \"Western blotting of sperm from patient with compound heterozygous PMFBP1 mutations\",\n      \"journal\": \"Molecular genetics & genomic medicine\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, single method (Western blot), no orthogonal validation\",\n      \"pmids\": [\"35860846\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"CEP250 physically interacts with SUN5 and PMFBP1 at the sperm neck region; a loss-of-function mutation in CEP250 reduces this interaction, placing CEP250 in the same head-neck junction complex as PMFBP1.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence, CRISPR-Cas9 knock-in mice\",\n      \"journal\": \"Andrology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP showing interaction between CEP250 and PMFBP1/SUN5, supported by in vivo mouse model; single lab\",\n      \"pmids\": [\"39726222\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"A nonsense mutation in PMFBP1 (c.2641C>T, p.Arg881Ter) produces a truncated protein with significantly altered stability (assessed by cycloheximide chase and MG132 proteasome inhibitor assays), causing absence of PMFBP1 in sperm and acephalic spermatozoa syndrome.\",\n      \"method\": \"Western blot, cycloheximide chase assay, MG132 proteasome inhibitor assay, Sanger sequencing, transmission electron microscopy\",\n      \"journal\": \"Biomedicines\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — protein stability mechanistically dissected with CHX/MG132 assays, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"41462896\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"A homozygous splice site mutation (c.2089-1G>T) in PMFBP1 causes deletion of 4 bp from exon 15, abolishing PMFBP1 protein expression in sperm, confirmed by in vitro splicing model, RT-PCR and Sanger sequencing.\",\n      \"method\": \"Western blotting, immunofluorescence, in vitro splice-site mutation model, RT-PCR, Sanger sequencing\",\n      \"journal\": \"Basic and clinical andrology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro splicing model with RT-PCR validation plus patient sperm Western blot; single lab, two orthogonal methods\",\n      \"pmids\": [\"39668357\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Loss of CCDC188 protein in patients is accompanied by co-depletion of SUN5 and PMFBP1 in sperm, suggesting CCDC188 functions in the same structural complex at the sperm head-neck junction as PMFBP1.\",\n      \"method\": \"Western blotting and immunofluorescence of patient sperm\",\n      \"journal\": \"Journal of assisted reproduction and genetics\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — co-depletion observed in patient sperm by Western blot/IF; no direct interaction assay performed for PMFBP1 specifically; single lab, single method\",\n      \"pmids\": [\"41004021\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PMFBP1 is a testis-specific scaffold protein that localizes to the sperm head-neck junction, where it cooperates with SUN5, SPATA6, and CEP250 to physically connect the sperm head to the tail; loss-of-function mutations cause acephalic spermatozoa syndrome in both humans and mice, and mechanistically PMFBP1 interacts with the chaperone CCT3 to maintain HDAC3 expression, which in turn regulates downstream spermatogenic factors RNF151 and RNF133, while its absence also reduces expression of the structural proteins ODF1 and ODF2.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PMFBP1 is a testis-specific scaffold protein of the sperm head-neck junction that physically couples the sperm head to the flagellum, and its loss causes acephalic spermatozoa syndrome in both humans and mice [#0, #1]. At this junction it cooperates with SUN5 and SPATA6, and integrates into a multiprotein head-neck complex that also includes CEP250, whose own interaction with PMFBP1/SUN5 is lost upon CEP250 disruption [#0, #5]. Beyond its structural role, PMFBP1 acts in a regulatory axis during spermatogenesis: it associates with the chaperonin subunit CCT3 and with HDAC3, and its loss reduces HDAC3 expression with downstream downregulation of the E3 ligase factors RNF151 and RNF133 [#2]. Disease-causing alleles — missense, nonsense, splice-site, and truncating mutations — converge mechanistically on destabilization or loss of PMFBP1 protein in sperm [#3, #6, #7], establishing PMFBP1 as a causative gene for acephalic spermatozoa syndrome.\",\n  \"teleology\": [\n    {\n      \"year\": 2018,\n      \"claim\": \"Established PMFBP1 as a structural scaffold at the sperm head-tail junction by showing it cooperates with SUN5 and SPATA6 and that its loss produces acephalic spermatozoa, defining a molecular basis for head-tail decapitation.\",\n      \"evidence\": \"Pmfbp1 knockout mice, co-IP with SUN5/SPATA6, and whole-exome sequencing of human patients, with independent immunofluorescence localization and KO replication plus proteomics\",\n      \"pmids\": [\"30032984\", \"30298696\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct binding interfaces/stoichiometry of the SUN5-SPATA6-PMFBP1 assembly not resolved\", \"Mechanism connecting PMFBP1 loss to Golgi vesicle transport changes unclear\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Extended PMFBP1 from a purely structural protein to a node in a gene-regulatory axis by identifying CCT3 and HDAC3 as interactors and linking PMFBP1 loss to reduced HDAC3 and downstream RNF151/RNF133.\",\n      \"evidence\": \"IP-MS, co-IP, immunoblotting, RT-qPCR, and proteomics/transcriptomics of Pmfbp1-/- mouse testis (single lab)\",\n      \"pmids\": [\"37423931\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Not independently replicated\", \"Direct vs indirect nature of the PMFBP1-HDAC3 functional link unresolved\", \"How a junction scaffold modulates HDAC3 levels mechanistically unknown\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Placed CEP250 in the same head-neck junction complex as PMFBP1, broadening the membership of the structural assembly.\",\n      \"evidence\": \"Reciprocal co-IP, immunofluorescence, and CRISPR-Cas9 knock-in mice (single lab)\",\n      \"pmids\": [\"39726222\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether CEP250 binds PMFBP1 directly or via SUN5 not established\", \"Spatial architecture of the full complex unknown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Defined how disease alleles act mechanistically, showing missense, nonsense, splice-site, and truncating mutations destabilize or abolish PMFBP1 protein in sperm.\",\n      \"evidence\": \"Western blot of patient sperm, in vitro mutant expression, cycloheximide chase, MG132 proteasome assays, and in vitro splicing models across multiple patient studies\",\n      \"pmids\": [\"33484382\", \"41462896\", \"39668357\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Each allele characterized in a single lab\", \"Genotype-phenotype correlation across mutation classes not systematized\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Implicated additional partners (ODF1/ODF2, CCDC188) by co-depletion, hinting at broader structural dependencies but without direct interaction proof for PMFBP1.\",\n      \"evidence\": \"Western blotting and immunofluorescence of patient sperm\",\n      \"pmids\": [\"35860846\", \"41004021\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No direct PMFBP1 interaction assay performed for CCDC188 or ODF1/ODF2\", \"Single method (Western/IF), no orthogonal validation\", \"Cause vs consequence of expression changes unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The structural architecture and biochemical mechanism by which PMFBP1 simultaneously scaffolds the head-neck junction and influences HDAC3-dependent gene regulation remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of the PMFBP1-containing junction complex\", \"Direct binding partners vs co-dependent proteins not fully distinguished\", \"Mechanism coupling structural scaffolding to transcriptional/regulatory output unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 5]}\n    ],\n    \"localization\": [],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"complexes\": [\"sperm head-neck junction complex\"],\n    \"partners\": [\"SUN5\", \"SPATA6\", \"CEP250\", \"CCT3\", \"HDAC3\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":4,"faith_total":4,"faith_pct":100.0}}