{"gene":"CFAP300","run_date":"2026-06-09T22:57:18","timeline":{"discoveries":[{"year":2018,"finding":"C11orf70/CFAP300 is required for the assembly of both outer (ODA) and inner (IDA) dynein arms in ciliary axonemes; RNAi knockdown in Paramecium caused combined loss of ciliary IDA+ODA with reduced cilia beating and swim velocity. Tagged C11orf70 localizes mainly in the cytoplasm with a small amount in the ciliary compartment, and its transport within cilia is IFT-dependent (shown by IFT139/TTC21B and FLA10 depletion). During ciliogenesis, C11orf70 accumulates at ciliary tips in a distribution similar to IFT-B protein IFT46.","method":"RNAi knockdown in Paramecium; tagged protein localization in Paramecium and Chlamydomonas; IFT component depletion experiments (IFT139/TTC21B and FLA10); transmission electron microscopy","journal":"American journal of human genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (RNAi functional assay, tagged localization, IFT depletion epistasis) in two model organisms, replicated functionally across labs","pmids":["29727692"],"is_preprint":false},{"year":2018,"finding":"Loss-of-function mutations in C11orf70/CFAP300 cause loss of axonemal ODAs and IDAs in respiratory cilia and sperm flagella, leading to immotility; CFAP300 expression is upregulated during ciliogenesis similarly to other dynein arm assembly factors. CFAP300 was shown to interact with cytoplasmic ODA/IDA assembly factor DNAAF2 by co-immunoprecipitation, supporting a role as a dynein preassembly factor.","method":"Transmission electron microscopy; immunofluorescence microscopy; expression analysis during ciliogenesis; co-immunoprecipitation with DNAAF2","journal":"American journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal interaction shown by Co-IP with DNAAF2, supported by TEM structural data and expression analysis, single lab","pmids":["29727693"],"is_preprint":false},{"year":2019,"finding":"Immunofluorescence analysis of respiratory epithelial cells from patients with CFAP300 mutations revealed absence or aberrant localization of ODA marker DNAH5 and IDA marker DNALI1, with disparate localization patterns suggesting differential trafficking mechanisms for preassembled outer versus inner dynein arms to the axoneme. Gene silencing in Schmidtea mediterranea confirmed conserved role of CFAP300 in ciliary function.","method":"Immunofluorescence microscopy of patient respiratory epithelial cells; transmission electron microscopy; RNAi gene silencing in Schmidtea mediterranea (flatworm)","journal":"American journal of respiratory cell and molecular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — patient-derived cell immunofluorescence with two dynein markers plus ortholog knockdown in model organism, single lab","pmids":["30916986"],"is_preprint":false},{"year":2021,"finding":"In dynein preassembly mutant males with CFAP300/C11orf70 mutations, sperm flagella show complete loss of ODAs (and IDAs), while some respiratory cilia from the same individuals can retain ODAs in the proximal ciliary compartment, demonstrating a tissue-specific difference. Mutant sperm also show a significant reduction in flagellar length. Systematic immunofluorescence comparison of dynein arm composition between sperm flagella and respiratory cilia established that only one ODA type exists in sperm versus two ODA types in respiratory cilia.","method":"High-speed video microscopy; transmission electron microscopy; immunofluorescence microscopy comparing sperm flagella and respiratory cilia; flagellar length analysis","journal":"PLoS genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple imaging modalities on patient-derived cells from multiple DNAAF mutant individuals including CFAP300, single study","pmids":["33635866"],"is_preprint":false},{"year":2022,"finding":"Super-resolution microscopy of normal human airway epithelial cells demonstrated that CFAP300 is transported along cilia, supporting a role not only in cytoplasmic dynein preassembly but also in dynein complex transport into the axoneme. Patients homozygous for the c.198_200delinsCC loss-of-function mutation lack CFAP300 protein and show complete absence of dynein arms and immotile cilia.","method":"Super-resolution microscopy for intraciliary CFAP300 localization; immunofluorescence; transmission electron microscopy of patient cilia","journal":"Frontiers in genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct super-resolution localization experiment in normal human airway cells plus patient loss-of-function confirmation, single lab","pmids":["36246608"],"is_preprint":false},{"year":2025,"finding":"A homozygous CFAP300 loss-of-function variant (c.304delC) in a human patient caused not only dynein arm deficiency in sperm but also acrosomal malformation, revealing a role in acrosome formation. TMT-based quantitative proteomics of patient sperm showed reduced levels of key spermatogenesis proteins (SPEF2, SLC25A31, AKAP3) and mitochondrial ATP synthesis factors (SLC25A31, CATSPER3), along with abnormal increases in autophagy-related proteins and signaling mediator phosphorylation.","method":"Transmission electron microscopy; immunofluorescence; TMT-based quantitative proteomics of patient versus control sperm; histological analysis","journal":"Asian journal of andrology","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — quantitative proteomics with TEM structural validation in patient material, single lab, single patient","pmids":["40898687"],"is_preprint":false},{"year":2025,"finding":"In CFAP300 mutant zebrafish (cfap300 knockout), cfap300 was found to be expressed in multiple ciliated organs starting in Kupffer's vesicle. Mechanistically, loss of cfap300 increases hnf1ba expression, which drives cdh17 transcription and impairs Corpuscle of Stannius (CS) precursor transdifferentiation; knockdown of hnf1ba or knockout of cdh17 in cfap300 mutants restores CS gland formation, establishing a Cfap300-Hnf1ba-Cdh17 pathway in epithelial-to-endocrine transdifferentiation.","method":"TALEN-based knockout zebrafish; whole-mount in situ hybridization; RT-qPCR; digital PCR; genetic epistasis (hnf1ba knockdown and cdh17 knockout rescue)","journal":"Cell communication and signaling : CCS","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis with two-step rescue in zebrafish knockout, multiple methods, single lab","pmids":["42067934"],"is_preprint":false},{"year":2025,"finding":"In patient-derived respiratory epithelial cells cultured at air-liquid interface (ALI), CFAP300 loss-of-function variant c.198_200delinsCC (p.Phe67ProfsTer10) leads to complete absence of functional CFAP300 protein, total loss of outer and inner dynein arms, and immotile cilia with no ciliary beating; immunostaining confirmed absence of CFAP300 in patient-derived cilia.","method":"Air-liquid interface cell culture; high-speed video microscopy; transmission electron microscopy; immunofluorescence staining","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multimodal approach in patient-derived ALI cultures with functional readout, single lab","pmids":["40806783"],"is_preprint":false}],"current_model":"CFAP300 (C11orf70/DNAAF17) is a cytoplasmic dynein arm preassembly factor that localizes predominantly in the cytoplasm and is transported into cilia via an IFT-dependent mechanism; it physically interacts with DNAAF2, is required for the assembly and/or trafficking of both outer and inner dynein arms into axonemes of respiratory cilia and sperm flagella, and its loss causes combined ODA+IDA deficiency with immotile cilia and male infertility, while in zebrafish it additionally regulates a Cfap300-Hnf1ba-Cdh17 pathway controlling epithelial-to-endocrine transdifferentiation in the pronephros."},"narrative":{"mechanistic_narrative":"CFAP300 (C11orf70/DNAAF17) is a cytoplasmic dynein arm preassembly factor required for the assembly of both outer (ODA) and inner (IDA) dynein arms in motile ciliary and flagellar axonemes [PMID:29727692, PMID:29727693]. It localizes predominantly to the cytoplasm with a smaller pool transported into the ciliary compartment by an IFT-dependent mechanism, accumulating at ciliary tips in a distribution resembling the IFT-B protein IFT46 [PMID:29727692], and it is also detected moving along the length of cilia, consistent with a role in both cytoplasmic preassembly and trafficking of dynein complexes into the axoneme [PMID:36246608]. Mechanistically it acts as a dynein preassembly factor through physical interaction with the assembly factor DNAAF2 [PMID:29727693]. Loss-of-function mutations abolish CFAP300 protein and cause combined ODA+IDA deficiency with immotile cilia and absent ciliary beating in patient respiratory epithelium, and complete dynein arm loss with shortened, immotile sperm flagella, identifying it as a cause of primary ciliary dyskinesia and male infertility [PMID:36246608, PMID:40806783, PMID:33635866]; in sperm, loss additionally produces acrosomal malformation and altered abundance of spermatogenesis and mitochondrial ATP-synthesis proteins [PMID:40898687]. Beyond its conserved axonemal role, in zebrafish Cfap300 operates in a Cfap300-Hnf1ba-Cdh17 pathway governing epithelial-to-endocrine transdifferentiation in the pronephros [PMID:42067934].","teleology":[{"year":2018,"claim":"Established the core molecular function of CFAP300 as a cytoplasmic factor required for assembly of both dynein arm types, distinguishing it from axonemal structural components.","evidence":"RNAi knockdown, tagged localization, and IFT-component depletion epistasis in Paramecium and Chlamydomonas with TEM","pmids":["29727692"],"confidence":"High","gaps":["Molecular step in the preassembly chain not resolved","Direct substrate or dynein subunit binding not biochemically defined"]},{"year":2018,"claim":"Connected CFAP300 to the known DNAAF preassembly machinery and to human disease by demonstrating a physical interaction with DNAAF2 and disease-causing loss-of-function alleles.","evidence":"Co-immunoprecipitation with DNAAF2, TEM, immunofluorescence, and ciliogenesis expression analysis in patient material","pmids":["29727693"],"confidence":"Medium","gaps":["Single lab; interaction interface and stoichiometry with DNAAF2 unknown","Whether interaction is direct or bridged by other DNAAFs not established"]},{"year":2019,"claim":"Showed that outer versus inner dynein arm trafficking to the axoneme may follow distinct routes, refining how preassembled complexes reach their destination.","evidence":"Immunofluorescence of DNAH5 (ODA) and DNALI1 (IDA) in patient respiratory cells plus ortholog silencing in Schmidtea mediterranea","pmids":["30916986"],"confidence":"Medium","gaps":["Mechanism producing disparate ODA/IDA localization not defined","Single lab"]},{"year":2021,"claim":"Revealed tissue-specific consequences of CFAP300 loss, with complete dynein loss in sperm but partial proximal ODA retention in some respiratory cilia, linked to differing dynein arm composition between tissues.","evidence":"High-speed video microscopy, TEM, and comparative immunofluorescence of sperm flagella versus respiratory cilia with flagellar length analysis","pmids":["33635866"],"confidence":"Medium","gaps":["Basis for tissue-specific differential requirement unresolved","Single study"]},{"year":2022,"claim":"Provided direct evidence that CFAP300 is transported within cilia, extending its role from cytoplasmic preassembly to intraciliary dynein delivery.","evidence":"Super-resolution microscopy in normal human airway epithelial cells plus patient loss-of-function confirmation by IF and TEM","pmids":["36246608"],"confidence":"Medium","gaps":["Cargo carried during transport not directly identified","Single lab"]},{"year":2025,"claim":"Extended CFAP300's role in spermatogenesis beyond flagellar dynein to acrosome formation and altered abundance of spermatogenesis and mitochondrial proteins.","evidence":"TEM, immunofluorescence, histology, and TMT quantitative proteomics of patient versus control sperm","pmids":["40898687"],"confidence":"Medium","gaps":["Single patient; causal link between CFAP300 loss and acrosome defect not mechanistically dissected","Whether proteomic changes are direct or secondary to immotility is unknown"]},{"year":2025,"claim":"Uncovered a cilia-associated developmental signaling role in which Cfap300 loss derepresses hnf1ba to drive cdh17 and block endocrine transdifferentiation.","evidence":"TALEN zebrafish knockout with in situ hybridization, RT-qPCR/digital PCR, and two-step genetic epistasis rescue","pmids":["42067934"],"confidence":"Medium","gaps":["Mechanism linking ciliary CFAP300 function to hnf1ba regulation unknown","Conservation of this pathway in mammals not tested","Single lab"]},{"year":2025,"claim":"Confirmed in a physiological airway model that a recurrent loss-of-function allele abolishes CFAP300 protein, eliminates both dynein arms, and arrests ciliary beating.","evidence":"Air-liquid interface patient cultures with high-speed video microscopy, TEM, and immunofluorescence","pmids":["40806783"],"confidence":"Medium","gaps":["Does not add new molecular mechanism beyond confirming null phenotype","Single lab"]},{"year":null,"claim":"How CFAP300 mechanistically loads dynein complexes onto IFT for axonemal delivery, and whether its developmental signaling role reflects cilia-dependent or independent functions, remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structure of CFAP300 or its DNAAF2 complex","Dynein cargo handed off during intraciliary transport not identified","Mammalian relevance of the Hnf1ba-Cdh17 pathway untested"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,1]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,1]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[0]},{"term_id":"GO:0005929","term_label":"cilium","supporting_discovery_ids":[0,4]}],"pathway":[{"term_id":"R-HSA-1852241","term_label":"Organelle biogenesis and maintenance","supporting_discovery_ids":[0]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[6]}],"complexes":[],"partners":["DNAAF2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9BRQ4","full_name":"Cilia- and flagella-associated protein 300","aliases":[],"length_aa":267,"mass_kda":30.9,"function":"Cilium- and flagellum-specific protein that plays a role in axonemal structure organization and motility. May play a role in outer and inner dynein arm assembly","subcellular_location":"Cytoplasm; Cytoplasm, cytoskeleton, cilium axoneme","url":"https://www.uniprot.org/uniprotkb/Q9BRQ4/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CFAP300","classification":"Not Classified","n_dependent_lines":9,"n_total_lines":1208,"dependency_fraction":0.0074503311258278145},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/CFAP300","total_profiled":1310},"omim":[{"mim_id":"618063","title":"CILIARY DYSKINESIA, PRIMARY, 38; CILD38","url":"https://www.omim.org/entry/618063"},{"mim_id":"618058","title":"CILIA- AND FLAGELLA-ASSOCIATED PROTEIN 300; CFAP300","url":"https://www.omim.org/entry/618058"},{"mim_id":"244400","title":"CILIARY DYSKINESIA, PRIMARY, 1; CILD1","url":"https://www.omim.org/entry/244400"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Primary cilium","reliability":"Approved"},{"location":"Centrosome","reliability":"Approved"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"choroid plexus","ntpm":23.0},{"tissue":"fallopian tube","ntpm":27.4},{"tissue":"testis","ntpm":28.2}],"url":"https://www.proteinatlas.org/search/CFAP300"},"hgnc":{"alias_symbol":["MGC13040","FBB5","DNAAF17"],"prev_symbol":["C11orf70"]},"alphafold":{"accession":"Q9BRQ4","domains":[{"cath_id":"3.40.1000,3.40.1000","chopping":"15-101_205-260","consensus_level":"medium","plddt":95.5038,"start":15,"end":260},{"cath_id":"-","chopping":"109-189","consensus_level":"medium","plddt":96.1841,"start":109,"end":189}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BRQ4","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BRQ4-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BRQ4-F1-predicted_aligned_error_v6.png","plddt_mean":93.69},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CFAP300","jax_strain_url":"https://www.jax.org/strain/search?query=CFAP300"},"sequence":{"accession":"Q9BRQ4","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9BRQ4.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9BRQ4/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BRQ4"}},"corpus_meta":[{"pmid":"33635866","id":"PMC_33635866","title":"Defects in the cytoplasmic assembly of axonemal dynein arms cause morphological abnormalities and dysmotility in sperm cells leading to male infertility.","date":"2021","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/33635866","citation_count":67,"is_preprint":false},{"pmid":"29727692","id":"PMC_29727692","title":"C11orf70 Mutations Disrupting the Intraflagellar Transport-Dependent Assembly of Multiple Axonemal Dyneins Cause Primary Ciliary Dyskinesia.","date":"2018","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/29727692","citation_count":56,"is_preprint":false},{"pmid":"29727693","id":"PMC_29727693","title":"Mutations in C11orf70 Cause Primary Ciliary Dyskinesia with Randomization of Left/Right Body Asymmetry Due to Defects of Outer and Inner Dynein Arms.","date":"2018","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/29727693","citation_count":53,"is_preprint":false},{"pmid":"34215651","id":"PMC_34215651","title":"Whole-exome sequencing reveals a monogenic cause in 56% of individuals with laterality disorders and associated congenital heart defects.","date":"2021","source":"Journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/34215651","citation_count":25,"is_preprint":false},{"pmid":"30916986","id":"PMC_30916986","title":"CFAP300: Mutations in Slavic Patients with Primary Ciliary Dyskinesia and a Role in Ciliary Dynein Arms Trafficking.","date":"2019","source":"American journal of respiratory cell and molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/30916986","citation_count":23,"is_preprint":false},{"pmid":"36246608","id":"PMC_36246608","title":"CFAP300 mutation causing primary ciliary dyskinesia in Finland.","date":"2022","source":"Frontiers in genetics","url":"https://pubmed.ncbi.nlm.nih.gov/36246608","citation_count":9,"is_preprint":false},{"pmid":"19041365","id":"PMC_19041365","title":"TPD52, a candidate gene from genomic studies, is overexpressed in testicular germ cell tumours.","date":"2008","source":"Molecular and cellular endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/19041365","citation_count":9,"is_preprint":false},{"pmid":"39004944","id":"PMC_39004944","title":"Genetics of 67 patients of suspected primary ciliary dyskinesia from India.","date":"2024","source":"Clinical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/39004944","citation_count":7,"is_preprint":false},{"pmid":"39180133","id":"PMC_39180133","title":"Characterization of pathogenic genetic variants in Russian patients with primary ciliary dyskinesia using gene panel sequencing and transcript analysis.","date":"2024","source":"Orphanet journal of rare diseases","url":"https://pubmed.ncbi.nlm.nih.gov/39180133","citation_count":5,"is_preprint":false},{"pmid":"39254424","id":"PMC_39254424","title":"A novel homozygous mutation of CFAP300 identified in a Chinese patient with primary ciliary dyskinesia and infertility.","date":"2024","source":"Asian journal of andrology","url":"https://pubmed.ncbi.nlm.nih.gov/39254424","citation_count":4,"is_preprint":false},{"pmid":"40898687","id":"PMC_40898687","title":"CFAP300 loss-of-function variant causes primary ciliary dyskinesia and male infertility via disrupting sperm flagellar assembly and acrosome formation.","date":"2025","source":"Asian journal of andrology","url":"https://pubmed.ncbi.nlm.nih.gov/40898687","citation_count":2,"is_preprint":false},{"pmid":"40806783","id":"PMC_40806783","title":"CFAP300 Loss-of-Function Mutations with Primary Ciliary Dyskinesia: Evidence from Ex Vivo and ALI Cultures.","date":"2025","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/40806783","citation_count":2,"is_preprint":false},{"pmid":"42067934","id":"PMC_42067934","title":"Cfap300 regulates the transdifferentiation of Corpuscle of Stannius cells in zebrafish.","date":"2026","source":"Cell communication and signaling : CCS","url":"https://pubmed.ncbi.nlm.nih.gov/42067934","citation_count":0,"is_preprint":false},{"pmid":"41373829","id":"PMC_41373829","title":"Heterogeneity of Primary Ciliary Dyskinesia Gene Variants: A Genetic Database Analysis in Russia.","date":"2025","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/41373829","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9578,"output_tokens":2408,"usd":0.032427,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9566,"output_tokens":2853,"usd":0.059577,"stage2_stop_reason":"end_turn"},"total_usd":0.092004,"stage1_batch_id":"msgbatch_01ACAxJQabDsht39JXeWG22d","stage2_batch_id":"msgbatch_01QEU22A9U5sbPTgsMzTmvSf","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2018,\n      \"finding\": \"C11orf70/CFAP300 is required for the assembly of both outer (ODA) and inner (IDA) dynein arms in ciliary axonemes; RNAi knockdown in Paramecium caused combined loss of ciliary IDA+ODA with reduced cilia beating and swim velocity. Tagged C11orf70 localizes mainly in the cytoplasm with a small amount in the ciliary compartment, and its transport within cilia is IFT-dependent (shown by IFT139/TTC21B and FLA10 depletion). During ciliogenesis, C11orf70 accumulates at ciliary tips in a distribution similar to IFT-B protein IFT46.\",\n      \"method\": \"RNAi knockdown in Paramecium; tagged protein localization in Paramecium and Chlamydomonas; IFT component depletion experiments (IFT139/TTC21B and FLA10); transmission electron microscopy\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (RNAi functional assay, tagged localization, IFT depletion epistasis) in two model organisms, replicated functionally across labs\",\n      \"pmids\": [\"29727692\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Loss-of-function mutations in C11orf70/CFAP300 cause loss of axonemal ODAs and IDAs in respiratory cilia and sperm flagella, leading to immotility; CFAP300 expression is upregulated during ciliogenesis similarly to other dynein arm assembly factors. CFAP300 was shown to interact with cytoplasmic ODA/IDA assembly factor DNAAF2 by co-immunoprecipitation, supporting a role as a dynein preassembly factor.\",\n      \"method\": \"Transmission electron microscopy; immunofluorescence microscopy; expression analysis during ciliogenesis; co-immunoprecipitation with DNAAF2\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal interaction shown by Co-IP with DNAAF2, supported by TEM structural data and expression analysis, single lab\",\n      \"pmids\": [\"29727693\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Immunofluorescence analysis of respiratory epithelial cells from patients with CFAP300 mutations revealed absence or aberrant localization of ODA marker DNAH5 and IDA marker DNALI1, with disparate localization patterns suggesting differential trafficking mechanisms for preassembled outer versus inner dynein arms to the axoneme. Gene silencing in Schmidtea mediterranea confirmed conserved role of CFAP300 in ciliary function.\",\n      \"method\": \"Immunofluorescence microscopy of patient respiratory epithelial cells; transmission electron microscopy; RNAi gene silencing in Schmidtea mediterranea (flatworm)\",\n      \"journal\": \"American journal of respiratory cell and molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — patient-derived cell immunofluorescence with two dynein markers plus ortholog knockdown in model organism, single lab\",\n      \"pmids\": [\"30916986\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"In dynein preassembly mutant males with CFAP300/C11orf70 mutations, sperm flagella show complete loss of ODAs (and IDAs), while some respiratory cilia from the same individuals can retain ODAs in the proximal ciliary compartment, demonstrating a tissue-specific difference. Mutant sperm also show a significant reduction in flagellar length. Systematic immunofluorescence comparison of dynein arm composition between sperm flagella and respiratory cilia established that only one ODA type exists in sperm versus two ODA types in respiratory cilia.\",\n      \"method\": \"High-speed video microscopy; transmission electron microscopy; immunofluorescence microscopy comparing sperm flagella and respiratory cilia; flagellar length analysis\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple imaging modalities on patient-derived cells from multiple DNAAF mutant individuals including CFAP300, single study\",\n      \"pmids\": [\"33635866\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Super-resolution microscopy of normal human airway epithelial cells demonstrated that CFAP300 is transported along cilia, supporting a role not only in cytoplasmic dynein preassembly but also in dynein complex transport into the axoneme. Patients homozygous for the c.198_200delinsCC loss-of-function mutation lack CFAP300 protein and show complete absence of dynein arms and immotile cilia.\",\n      \"method\": \"Super-resolution microscopy for intraciliary CFAP300 localization; immunofluorescence; transmission electron microscopy of patient cilia\",\n      \"journal\": \"Frontiers in genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct super-resolution localization experiment in normal human airway cells plus patient loss-of-function confirmation, single lab\",\n      \"pmids\": [\"36246608\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"A homozygous CFAP300 loss-of-function variant (c.304delC) in a human patient caused not only dynein arm deficiency in sperm but also acrosomal malformation, revealing a role in acrosome formation. TMT-based quantitative proteomics of patient sperm showed reduced levels of key spermatogenesis proteins (SPEF2, SLC25A31, AKAP3) and mitochondrial ATP synthesis factors (SLC25A31, CATSPER3), along with abnormal increases in autophagy-related proteins and signaling mediator phosphorylation.\",\n      \"method\": \"Transmission electron microscopy; immunofluorescence; TMT-based quantitative proteomics of patient versus control sperm; histological analysis\",\n      \"journal\": \"Asian journal of andrology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — quantitative proteomics with TEM structural validation in patient material, single lab, single patient\",\n      \"pmids\": [\"40898687\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In CFAP300 mutant zebrafish (cfap300 knockout), cfap300 was found to be expressed in multiple ciliated organs starting in Kupffer's vesicle. Mechanistically, loss of cfap300 increases hnf1ba expression, which drives cdh17 transcription and impairs Corpuscle of Stannius (CS) precursor transdifferentiation; knockdown of hnf1ba or knockout of cdh17 in cfap300 mutants restores CS gland formation, establishing a Cfap300-Hnf1ba-Cdh17 pathway in epithelial-to-endocrine transdifferentiation.\",\n      \"method\": \"TALEN-based knockout zebrafish; whole-mount in situ hybridization; RT-qPCR; digital PCR; genetic epistasis (hnf1ba knockdown and cdh17 knockout rescue)\",\n      \"journal\": \"Cell communication and signaling : CCS\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis with two-step rescue in zebrafish knockout, multiple methods, single lab\",\n      \"pmids\": [\"42067934\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In patient-derived respiratory epithelial cells cultured at air-liquid interface (ALI), CFAP300 loss-of-function variant c.198_200delinsCC (p.Phe67ProfsTer10) leads to complete absence of functional CFAP300 protein, total loss of outer and inner dynein arms, and immotile cilia with no ciliary beating; immunostaining confirmed absence of CFAP300 in patient-derived cilia.\",\n      \"method\": \"Air-liquid interface cell culture; high-speed video microscopy; transmission electron microscopy; immunofluorescence staining\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multimodal approach in patient-derived ALI cultures with functional readout, single lab\",\n      \"pmids\": [\"40806783\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CFAP300 (C11orf70/DNAAF17) is a cytoplasmic dynein arm preassembly factor that localizes predominantly in the cytoplasm and is transported into cilia via an IFT-dependent mechanism; it physically interacts with DNAAF2, is required for the assembly and/or trafficking of both outer and inner dynein arms into axonemes of respiratory cilia and sperm flagella, and its loss causes combined ODA+IDA deficiency with immotile cilia and male infertility, while in zebrafish it additionally regulates a Cfap300-Hnf1ba-Cdh17 pathway controlling epithelial-to-endocrine transdifferentiation in the pronephros.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CFAP300 (C11orf70/DNAAF17) is a cytoplasmic dynein arm preassembly factor required for the assembly of both outer (ODA) and inner (IDA) dynein arms in motile ciliary and flagellar axonemes [#0, #1]. It localizes predominantly to the cytoplasm with a smaller pool transported into the ciliary compartment by an IFT-dependent mechanism, accumulating at ciliary tips in a distribution resembling the IFT-B protein IFT46 [#0], and it is also detected moving along the length of cilia, consistent with a role in both cytoplasmic preassembly and trafficking of dynein complexes into the axoneme [#4]. Mechanistically it acts as a dynein preassembly factor through physical interaction with the assembly factor DNAAF2 [#1]. Loss-of-function mutations abolish CFAP300 protein and cause combined ODA+IDA deficiency with immotile cilia and absent ciliary beating in patient respiratory epithelium, and complete dynein arm loss with shortened, immotile sperm flagella, identifying it as a cause of primary ciliary dyskinesia and male infertility [#4, #7, #3]; in sperm, loss additionally produces acrosomal malformation and altered abundance of spermatogenesis and mitochondrial ATP-synthesis proteins [#5]. Beyond its conserved axonemal role, in zebrafish Cfap300 operates in a Cfap300-Hnf1ba-Cdh17 pathway governing epithelial-to-endocrine transdifferentiation in the pronephros [#6].\",\n  \"teleology\": [\n    {\n      \"year\": 2018,\n      \"claim\": \"Established the core molecular function of CFAP300 as a cytoplasmic factor required for assembly of both dynein arm types, distinguishing it from axonemal structural components.\",\n      \"evidence\": \"RNAi knockdown, tagged localization, and IFT-component depletion epistasis in Paramecium and Chlamydomonas with TEM\",\n      \"pmids\": [\"29727692\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Molecular step in the preassembly chain not resolved\",\n        \"Direct substrate or dynein subunit binding not biochemically defined\"\n      ]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Connected CFAP300 to the known DNAAF preassembly machinery and to human disease by demonstrating a physical interaction with DNAAF2 and disease-causing loss-of-function alleles.\",\n      \"evidence\": \"Co-immunoprecipitation with DNAAF2, TEM, immunofluorescence, and ciliogenesis expression analysis in patient material\",\n      \"pmids\": [\"29727693\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Single lab; interaction interface and stoichiometry with DNAAF2 unknown\",\n        \"Whether interaction is direct or bridged by other DNAAFs not established\"\n      ]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Showed that outer versus inner dynein arm trafficking to the axoneme may follow distinct routes, refining how preassembled complexes reach their destination.\",\n      \"evidence\": \"Immunofluorescence of DNAH5 (ODA) and DNALI1 (IDA) in patient respiratory cells plus ortholog silencing in Schmidtea mediterranea\",\n      \"pmids\": [\"30916986\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanism producing disparate ODA/IDA localization not defined\",\n        \"Single lab\"\n      ]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Revealed tissue-specific consequences of CFAP300 loss, with complete dynein loss in sperm but partial proximal ODA retention in some respiratory cilia, linked to differing dynein arm composition between tissues.\",\n      \"evidence\": \"High-speed video microscopy, TEM, and comparative immunofluorescence of sperm flagella versus respiratory cilia with flagellar length analysis\",\n      \"pmids\": [\"33635866\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Basis for tissue-specific differential requirement unresolved\",\n        \"Single study\"\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Provided direct evidence that CFAP300 is transported within cilia, extending its role from cytoplasmic preassembly to intraciliary dynein delivery.\",\n      \"evidence\": \"Super-resolution microscopy in normal human airway epithelial cells plus patient loss-of-function confirmation by IF and TEM\",\n      \"pmids\": [\"36246608\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Cargo carried during transport not directly identified\",\n        \"Single lab\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Extended CFAP300's role in spermatogenesis beyond flagellar dynein to acrosome formation and altered abundance of spermatogenesis and mitochondrial proteins.\",\n      \"evidence\": \"TEM, immunofluorescence, histology, and TMT quantitative proteomics of patient versus control sperm\",\n      \"pmids\": [\"40898687\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Single patient; causal link between CFAP300 loss and acrosome defect not mechanistically dissected\",\n        \"Whether proteomic changes are direct or secondary to immotility is unknown\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Uncovered a cilia-associated developmental signaling role in which Cfap300 loss derepresses hnf1ba to drive cdh17 and block endocrine transdifferentiation.\",\n      \"evidence\": \"TALEN zebrafish knockout with in situ hybridization, RT-qPCR/digital PCR, and two-step genetic epistasis rescue\",\n      \"pmids\": [\"42067934\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanism linking ciliary CFAP300 function to hnf1ba regulation unknown\",\n        \"Conservation of this pathway in mammals not tested\",\n        \"Single lab\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Confirmed in a physiological airway model that a recurrent loss-of-function allele abolishes CFAP300 protein, eliminates both dynein arms, and arrests ciliary beating.\",\n      \"evidence\": \"Air-liquid interface patient cultures with high-speed video microscopy, TEM, and immunofluorescence\",\n      \"pmids\": [\"40806783\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Does not add new molecular mechanism beyond confirming null phenotype\",\n        \"Single lab\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How CFAP300 mechanistically loads dynein complexes onto IFT for axonemal delivery, and whether its developmental signaling role reflects cilia-dependent or independent functions, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No structure of CFAP300 or its DNAAF2 complex\",\n        \"Dynein cargo handed off during intraciliary transport not identified\",\n        \"Mammalian relevance of the Hnf1ba-Cdh17 pathway untested\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0005929\", \"supporting_discovery_ids\": [0, 4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1852241\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"DNAAF2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}