{"gene":"IQUB","run_date":"2026-04-28T18:06:54","timeline":{"discoveries":[{"year":2011,"finding":"siRNA knockdown of IQUB in mammalian cell lines results in elongated cilia, establishing IQUB as a regulator of cilia length without affecting ciliation per se; knockdown also affected Hedgehog signaling readouts, placing IQUB in the ciliary signaling pathway.","method":"siRNA knockdown + high-content immunofluorescence microscopy (cilia length, Gli3 transport, Gli-luciferase Hh assay) in three cell lines","journal":"Molecular biology of the cell","confidence":"Medium","confidence_rationale":"Tier 2 — validated siRNA knockdown with multiple phenotypic readouts in three cell lines, single study","pmids":["21289087"],"is_preprint":false},{"year":2018,"finding":"IQUB overexpression promotes breast cancer cell proliferation and migration by activating Akt, which phosphorylates GSK3β, thereby activating the Wnt/β-catenin signaling pathway; IQUB knockdown causes G1 arrest and reduced migration, and co-treatment with Akt activator LiCl or proteasome inhibitor MG-132 confirmed the pathway order.","method":"Overexpression and siRNA knockdown in MCF-7/MDA-MB-231 cells + cell cycle analysis + migration assay + pharmacological epistasis (LiCl, MG-132) + Western blot for pathway components","journal":"Cancer medicine","confidence":"Medium","confidence_rationale":"Tier 2 — loss- and gain-of-function with pharmacological epistasis in two cell lines, single lab","pmids":["29968965"],"is_preprint":false},{"year":2022,"finding":"IQUB is required for assembly of radial spoke 1 (RS1) in mouse sperm flagella but is dispensable for RS1 in tracheal cilia; Iqub knockout mice lack entire RS1 in sperm, display sperm motility defects, and are male-infertile, identifying IQUB as an essential RS1 component in mammalian flagella and defining the RS1 protein composition.","method":"Iqub knockout mouse model + cryo-electron tomography/transmission electron microscopy of sperm ultrastructure + proteomics of RS1 composition","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 1-2 — genetic knockout with ultrastructural EM validation and proteomic identification of RS1 components; replicated by independent groups","pmids":["36417862"],"is_preprint":false},{"year":2023,"finding":"IQUB interacts with RSPH3, CEP295NL/DDC8, GSTM1, and ODF1 (yeast two-hybrid); in sperm lacking IQUB (knockout/knockin mouse), radial spoke assembly is defective and p-ERK1/2 activity is dysregulated via RSPH3; mechanistically, IQUB recruits calmodulin in low-Ca²⁺ environments to facilitate normal radial spoke assembly by inhibiting the RSPH3/p-ERK1/2 complex (a non-typical AKAP).","method":"Yeast two-hybrid protein interaction screen + Iqub KO and KI mouse models + co-immunoprecipitation + Western blot for p-ERK1/2 + scanning and transmission electron microscopy of sperm ultrastructure","journal":"Human reproduction","confidence":"Medium","confidence_rationale":"Tier 2 — genetic models with co-IP and functional pathway analysis, single lab; calmodulin recruitment is mechanistic inference without direct structural validation","pmids":["36355624"],"is_preprint":false},{"year":2023,"finding":"IQUB protein is localized to the acrosome and flagellum of mature spermatocytes and is expressed across multiple stages of spermatogenic cells in mouse testis, as determined by immunofluorescence with a validated polyclonal antibody.","method":"Immunofluorescence histochemistry and Western blot of mouse testis sections using recombinant-protein-generated polyclonal antibody","journal":"Xi bao yu fen zi mian yi xue za zhi","confidence":"Medium","confidence_rationale":"Tier 3 — direct localization by immunofluorescence with validated antibody, single study","pmids":["37732581"],"is_preprint":false},{"year":2024,"finding":"IQUB deficiency (caused by ARL3 compound heterozygous mutation-driven downregulation) results in over-elongated cilia, and re-expression of IQUB rescues the elongated cilia phenotype in ARL3T31A/C118F patient-derived fibroblasts, establishing IQUB as a downstream effector of ARL3 that limits cilia length.","method":"Patient-derived immortalized fibroblasts + RNA-seq + proteomics + IQUB rescue experiment + cilia length measurement by microscopy","journal":"FASEB journal","confidence":"Medium","confidence_rationale":"Tier 2 — rescue experiment with direct phenotypic readout in patient-derived cells, single study","pmids":["38457249"],"is_preprint":false},{"year":2025,"finding":"IQUB forms part of the stalk of RS1 in human and mouse sperm flagella; IQUB deficiency (homozygous frameshift mutation) causes selective RS1 loss (not RS2 or RS3) and secondary downregulation of inner dynein arms DNAH7 and DNAH12; proteomic analysis identified twelve RS1 components including RSPH3, RSPH6A, RSPH9, DYDC1, NME5, DNAJB13, PPIL6, AK8, ROPN1L, RSPH14, DYNLL1, and IQUB itself.","method":"Whole-exome sequencing of patient + Iqub−/− mouse model + protein mass spectrometry + Western blot + electron microscopy + structural modeling of RS1","journal":"Cell communication and signaling","confidence":"High","confidence_rationale":"Tier 1-2 — genetic patient mutation confirmed in mouse KO, proteomic RS1 composition defined, EM ultrastructural validation; replicates and extends prior RS1 findings","pmids":["39849482"],"is_preprint":false}],"current_model":"IQUB is a structural component of the stalk of radial spoke 1 (RS1) in mammalian sperm flagella, required for RS1 assembly and normal sperm motility; it interacts with RSPH3, calmodulin, and other RS1 proteins to modulate the RSPH3/p-ERK1/2 signaling axis, and in cilia it limits cilia length downstream of ARL3, while in cancer cells it activates the Akt/GSK3β/β-catenin pathway to promote proliferation and migration."},"narrative":{"teleology":[{"year":2011,"claim":"Whether IQUB had any ciliary function was unknown; siRNA knockdown established that IQUB limits cilia length and participates in Hedgehog signaling, identifying it as a ciliary regulatory factor.","evidence":"siRNA knockdown with cilia length quantification and Gli-luciferase Hedgehog assay in three mammalian cell lines","pmids":["21289087"],"confidence":"Medium","gaps":["Mechanism by which IQUB controls cilia length was not defined","Whether IQUB acts in motile cilia/flagella was untested","Upstream regulators of IQUB expression unknown"]},{"year":2018,"claim":"Whether IQUB influenced proliferative signaling outside the cilium was unknown; overexpression and knockdown showed IQUB activates the Akt/GSK3β/β-catenin pathway to promote breast cancer cell proliferation and migration.","evidence":"Gain- and loss-of-function with pharmacological epistasis (LiCl, MG-132) in MCF-7 and MDA-MB-231 breast cancer cells","pmids":["29968965"],"confidence":"Medium","gaps":["Relevance to non-cancer physiology unclear","No in vivo tumor model validation","Mechanism linking IQUB's IQ domains to Akt activation not identified"]},{"year":2022,"claim":"The role of IQUB in motile flagella was unknown; Iqub knockout mice revealed that IQUB is essential for assembly of the entire radial spoke 1 in sperm flagella, causing male infertility, while being dispensable for RS1 in tracheal cilia.","evidence":"Iqub knockout mouse with cryo-electron tomography, transmission EM, and proteomics of sperm RS1","pmids":["36417862"],"confidence":"High","gaps":["Precise position of IQUB within RS1 architecture was not resolved","Why tracheal cilia RS1 is independent of IQUB was unexplained","Downstream signaling consequences of RS1 loss not addressed"]},{"year":2023,"claim":"How IQUB contributes to RS1 assembly at the molecular level was unclear; interaction mapping and signaling analysis showed IQUB binds RSPH3 and calmodulin, and recruits calmodulin under low-Ca²⁺ conditions to inhibit the RSPH3/p-ERK1/2 complex, linking radial spoke assembly to an AKAP-like signaling module.","evidence":"Yeast two-hybrid screen, co-immunoprecipitation, Iqub KO/KI mouse models, Western blot for p-ERK1/2","pmids":["36355624"],"confidence":"Medium","gaps":["Calmodulin recruitment mechanism lacks direct structural validation","Whether p-ERK1/2 dysregulation is a cause or consequence of RS1 disassembly is ambiguous","In vitro reconstitution of the IQUB–calmodulin–RSPH3 complex not performed"]},{"year":2024,"claim":"Whether IQUB's cilia-length role was connected to known ciliopathy pathways was unknown; IQUB was identified as a downstream effector of ARL3, with rescue of elongated cilia in ARL3-mutant patient fibroblasts confirming IQUB as the functional mediator.","evidence":"Patient-derived immortalized fibroblasts with ARL3 compound heterozygous mutations, RNA-seq, proteomics, IQUB re-expression rescue","pmids":["38457249"],"confidence":"Medium","gaps":["Mechanism by which ARL3 regulates IQUB expression or stability not defined","Whether this pathway operates in motile cilia/flagella is untested","Single patient genotype limits generalizability"]},{"year":2025,"claim":"The precise structural position of IQUB in RS1 and its loss-of-function consequences in humans were undefined; a human frameshift mutation combined with mouse KO showed IQUB forms part of the RS1 stalk, and its loss selectively eliminates RS1 with secondary loss of inner dynein arms DNAH7 and DNAH12.","evidence":"Whole-exome sequencing of infertile patient, Iqub−/− mouse, mass spectrometry, EM, structural modeling","pmids":["39849482"],"confidence":"High","gaps":["Atomic-resolution structure of the RS1 stalk with IQUB is lacking","How RS1 loss causes secondary inner dynein arm downregulation is mechanistically unresolved","Whether IQUB mutations contribute to female subfertility is unknown"]},{"year":null,"claim":"How IQUB's dual roles in primary cilia length regulation (via ARL3) and motile flagella RS1 assembly are coordinated, and the structural basis of IQUB-calmodulin interaction within the RS1 stalk, remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No atomic structure of IQUB or IQUB-containing RS1 complex","Tissue-specific regulation of IQUB's cilia-length vs. RS1-assembly functions not understood","Relationship between IQ-domain calmodulin binding and RS1 structural integrity undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[2,6]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,3]}],"localization":[{"term_id":"GO:0005929","term_label":"cilium","supporting_discovery_ids":[0,2,4,5,6]}],"pathway":[{"term_id":"R-HSA-1852241","term_label":"Organelle biogenesis and maintenance","supporting_discovery_ids":[0,2,5,6]},{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[2,6]}],"complexes":["Radial spoke 1 (RS1)"],"partners":["RSPH3","DNAJB13","NME5","ODF1","GSTM1","CEP295NL","DYNLL1","RSPH6A"],"other_free_text":[]},"mechanistic_narrative":"IQUB is a structural component of the stalk of radial spoke 1 (RS1) in mammalian sperm flagella, essential for RS1 assembly, normal sperm motility, and male fertility [PMID:36417862, PMID:39849482]. Within the RS1 complex, IQUB interacts with RSPH3 and recruits calmodulin under low-Ca²⁺ conditions to modulate the RSPH3/p-ERK1/2 signaling axis, and its deficiency causes selective RS1 loss with secondary downregulation of inner dynein arms DNAH7 and DNAH12 [PMID:36355624, PMID:39849482]. IQUB also functions as a downstream effector of ARL3 in limiting primary cilia length; its depletion leads to cilia over-elongation, and re-expression rescues this phenotype [PMID:21289087, PMID:38457249]. Homozygous loss-of-function IQUB mutations cause asthenoteratozoospermia and male infertility in humans [PMID:39849482]."},"prefetch_data":{"uniprot":{"accession":"Q8NA54","full_name":"IQ motif and ubiquitin-like domain-containing protein","aliases":[],"length_aa":791,"mass_kda":92.6,"function":"Adapter protein that anchors the radial spoke 1 (RS1) complex to the A microtubule of outer doublet microtubules in axonemes (PubMed:36355624). The triple radial spokes (RS1, RS2 and RS3) are required to modulate beating of the sperm flagellum (PubMed:36355624). May play a role in inhibiting signaling via MAPK1/ERK2 and MAPK3/ERK1 (PubMed:36355624). Additionally, may play a role in the functioning of cilia (By similarity). Not required for the functioning of tracheal or ependymal cilia (By similarity)","subcellular_location":"Cytoplasm, cytoskeleton, flagellum axoneme; Cell projection, cilium","url":"https://www.uniprot.org/uniprotkb/Q8NA54/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/IQUB","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/IQUB","total_profiled":1310},"omim":[{"mim_id":"620557","title":"IQ MOTIF- AND UBIQUITIN DOMAIN-CONTAINING PROTEIN; IQUB","url":"https://www.omim.org/entry/620557"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nuclear speckles","reliability":"Approved"},{"location":"Mid piece","reliability":"Approved"},{"location":"Principal piece","reliability":"Approved"},{"location":"End piece","reliability":"Approved"},{"location":"Nucleoplasm","reliability":"Additional"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"testis","ntpm":31.3}],"url":"https://www.proteinatlas.org/search/IQUB"},"hgnc":{"alias_symbol":["FLJ35834"],"prev_symbol":[]},"alphafold":{"accession":"Q8NA54","domains":[{"cath_id":"3.10.20.90","chopping":"128-203","consensus_level":"high","plddt":85.8339,"start":128,"end":203},{"cath_id":"-","chopping":"640-773","consensus_level":"high","plddt":82.6294,"start":640,"end":773},{"cath_id":"1.10.287","chopping":"399-469","consensus_level":"medium","plddt":91.9873,"start":399,"end":469},{"cath_id":"1.20.120","chopping":"483-585","consensus_level":"medium","plddt":90.4597,"start":483,"end":585}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8NA54","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8NA54-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8NA54-F1-predicted_aligned_error_v6.png","plddt_mean":75.31},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=IQUB","jax_strain_url":"https://www.jax.org/strain/search?query=IQUB"},"sequence":{"accession":"Q8NA54","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8NA54.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8NA54/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8NA54"}},"corpus_meta":[{"pmid":"26330360","id":"PMC_26330360","title":"Whole genome and transcriptome sequencing of matched primary and peritoneal metastatic gastric carcinoma.","date":"2015","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/26330360","citation_count":81,"is_preprint":false},{"pmid":"21289087","id":"PMC_21289087","title":"Functional characterization of putative cilia genes by high-content analysis.","date":"2011","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/21289087","citation_count":77,"is_preprint":false},{"pmid":"24348429","id":"PMC_24348429","title":"Rare Genomic Variants Link Bipolar Disorder with Anxiety Disorders to CREB-Regulated Intracellular Signaling Pathways.","date":"2013","source":"Frontiers in psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/24348429","citation_count":33,"is_preprint":false},{"pmid":"36417862","id":"PMC_36417862","title":"Differential requirements of IQUB for the assembly of radial spoke 1 and the motility of mouse cilia and flagella.","date":"2022","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/36417862","citation_count":25,"is_preprint":false},{"pmid":"29968965","id":"PMC_29968965","title":"Upregulated IQUB promotes cell proliferation and migration via activating Akt/GSK3β/β-catenin signaling pathway in breast cancer.","date":"2018","source":"Cancer medicine","url":"https://pubmed.ncbi.nlm.nih.gov/29968965","citation_count":20,"is_preprint":false},{"pmid":"36339449","id":"PMC_36339449","title":"Combining bioinformatics, network pharmacology and artificial intelligence to predict the mechanism of celastrol in the treatment of type 2 diabetes.","date":"2022","source":"Frontiers in endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/36339449","citation_count":18,"is_preprint":false},{"pmid":"36355624","id":"PMC_36355624","title":"IQUB deficiency causes male infertility by affecting the activity of p-ERK1/2/RSPH3.","date":"2023","source":"Human reproduction (Oxford, England)","url":"https://pubmed.ncbi.nlm.nih.gov/36355624","citation_count":8,"is_preprint":false},{"pmid":"39849482","id":"PMC_39849482","title":"IQUB mutation induces radial spoke 1 deficiency causing asthenozoospermia with normal sperm morphology in humans and mice.","date":"2025","source":"Cell communication and signaling : CCS","url":"https://pubmed.ncbi.nlm.nih.gov/39849482","citation_count":5,"is_preprint":false},{"pmid":"38457249","id":"PMC_38457249","title":"Mechanisms underlying morphological and functional changes of cilia in fibroblasts derived from patients bearing ARL3T31A and ARL3T31A/C118F mutations.","date":"2024","source":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/38457249","citation_count":5,"is_preprint":false},{"pmid":"37277920","id":"PMC_37277920","title":"Transcriptome-wide profile of 1α,25 dihydroxyvitamin D3 in HTR-8/SVneo cells.","date":"2023","source":"The journal of obstetrics and gynaecology research","url":"https://pubmed.ncbi.nlm.nih.gov/37277920","citation_count":1,"is_preprint":false},{"pmid":"37732581","id":"PMC_37732581","title":"[Preparation and application of rabbit polyclonal antibody against mouse IQ and ubiquitin-like domain-containing protein (IQUB)].","date":"2023","source":"Xi bao yu fen zi mian yi xue za zhi = Chinese journal of cellular and molecular immunology","url":"https://pubmed.ncbi.nlm.nih.gov/37732581","citation_count":0,"is_preprint":false},{"pmid":"41602861","id":"PMC_41602861","title":"IQ motif family genes in male infertility: pathogenesis, mechanisms, and clinical perspectives.","date":"2026","source":"Frontiers in reproductive health","url":"https://pubmed.ncbi.nlm.nih.gov/41602861","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":8448,"output_tokens":1898,"usd":0.026907},"stage2":{"model":"claude-opus-4-6","input_tokens":5178,"output_tokens":2040,"usd":0.115335},"total_usd":0.142242,"stage1_batch_id":"msgbatch_01DzrsgVgYngY1hvM3DU1yF2","stage2_batch_id":"msgbatch_01KA9b7iRzKFdhoBUT7vCvSe","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2011,\n      \"finding\": \"siRNA knockdown of IQUB in mammalian cell lines results in elongated cilia, establishing IQUB as a regulator of cilia length without affecting ciliation per se; knockdown also affected Hedgehog signaling readouts, placing IQUB in the ciliary signaling pathway.\",\n      \"method\": \"siRNA knockdown + high-content immunofluorescence microscopy (cilia length, Gli3 transport, Gli-luciferase Hh assay) in three cell lines\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — validated siRNA knockdown with multiple phenotypic readouts in three cell lines, single study\",\n      \"pmids\": [\"21289087\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"IQUB overexpression promotes breast cancer cell proliferation and migration by activating Akt, which phosphorylates GSK3β, thereby activating the Wnt/β-catenin signaling pathway; IQUB knockdown causes G1 arrest and reduced migration, and co-treatment with Akt activator LiCl or proteasome inhibitor MG-132 confirmed the pathway order.\",\n      \"method\": \"Overexpression and siRNA knockdown in MCF-7/MDA-MB-231 cells + cell cycle analysis + migration assay + pharmacological epistasis (LiCl, MG-132) + Western blot for pathway components\",\n      \"journal\": \"Cancer medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — loss- and gain-of-function with pharmacological epistasis in two cell lines, single lab\",\n      \"pmids\": [\"29968965\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"IQUB is required for assembly of radial spoke 1 (RS1) in mouse sperm flagella but is dispensable for RS1 in tracheal cilia; Iqub knockout mice lack entire RS1 in sperm, display sperm motility defects, and are male-infertile, identifying IQUB as an essential RS1 component in mammalian flagella and defining the RS1 protein composition.\",\n      \"method\": \"Iqub knockout mouse model + cryo-electron tomography/transmission electron microscopy of sperm ultrastructure + proteomics of RS1 composition\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — genetic knockout with ultrastructural EM validation and proteomic identification of RS1 components; replicated by independent groups\",\n      \"pmids\": [\"36417862\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"IQUB interacts with RSPH3, CEP295NL/DDC8, GSTM1, and ODF1 (yeast two-hybrid); in sperm lacking IQUB (knockout/knockin mouse), radial spoke assembly is defective and p-ERK1/2 activity is dysregulated via RSPH3; mechanistically, IQUB recruits calmodulin in low-Ca²⁺ environments to facilitate normal radial spoke assembly by inhibiting the RSPH3/p-ERK1/2 complex (a non-typical AKAP).\",\n      \"method\": \"Yeast two-hybrid protein interaction screen + Iqub KO and KI mouse models + co-immunoprecipitation + Western blot for p-ERK1/2 + scanning and transmission electron microscopy of sperm ultrastructure\",\n      \"journal\": \"Human reproduction\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic models with co-IP and functional pathway analysis, single lab; calmodulin recruitment is mechanistic inference without direct structural validation\",\n      \"pmids\": [\"36355624\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"IQUB protein is localized to the acrosome and flagellum of mature spermatocytes and is expressed across multiple stages of spermatogenic cells in mouse testis, as determined by immunofluorescence with a validated polyclonal antibody.\",\n      \"method\": \"Immunofluorescence histochemistry and Western blot of mouse testis sections using recombinant-protein-generated polyclonal antibody\",\n      \"journal\": \"Xi bao yu fen zi mian yi xue za zhi\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — direct localization by immunofluorescence with validated antibody, single study\",\n      \"pmids\": [\"37732581\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"IQUB deficiency (caused by ARL3 compound heterozygous mutation-driven downregulation) results in over-elongated cilia, and re-expression of IQUB rescues the elongated cilia phenotype in ARL3T31A/C118F patient-derived fibroblasts, establishing IQUB as a downstream effector of ARL3 that limits cilia length.\",\n      \"method\": \"Patient-derived immortalized fibroblasts + RNA-seq + proteomics + IQUB rescue experiment + cilia length measurement by microscopy\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — rescue experiment with direct phenotypic readout in patient-derived cells, single study\",\n      \"pmids\": [\"38457249\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"IQUB forms part of the stalk of RS1 in human and mouse sperm flagella; IQUB deficiency (homozygous frameshift mutation) causes selective RS1 loss (not RS2 or RS3) and secondary downregulation of inner dynein arms DNAH7 and DNAH12; proteomic analysis identified twelve RS1 components including RSPH3, RSPH6A, RSPH9, DYDC1, NME5, DNAJB13, PPIL6, AK8, ROPN1L, RSPH14, DYNLL1, and IQUB itself.\",\n      \"method\": \"Whole-exome sequencing of patient + Iqub−/− mouse model + protein mass spectrometry + Western blot + electron microscopy + structural modeling of RS1\",\n      \"journal\": \"Cell communication and signaling\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — genetic patient mutation confirmed in mouse KO, proteomic RS1 composition defined, EM ultrastructural validation; replicates and extends prior RS1 findings\",\n      \"pmids\": [\"39849482\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"IQUB is a structural component of the stalk of radial spoke 1 (RS1) in mammalian sperm flagella, required for RS1 assembly and normal sperm motility; it interacts with RSPH3, calmodulin, and other RS1 proteins to modulate the RSPH3/p-ERK1/2 signaling axis, and in cilia it limits cilia length downstream of ARL3, while in cancer cells it activates the Akt/GSK3β/β-catenin pathway to promote proliferation and migration.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"IQUB is a structural component of the stalk of radial spoke 1 (RS1) in mammalian sperm flagella, essential for RS1 assembly, normal sperm motility, and male fertility [PMID:36417862, PMID:39849482]. Within the RS1 complex, IQUB interacts with RSPH3 and recruits calmodulin under low-Ca²⁺ conditions to modulate the RSPH3/p-ERK1/2 signaling axis, and its deficiency causes selective RS1 loss with secondary downregulation of inner dynein arms DNAH7 and DNAH12 [PMID:36355624, PMID:39849482]. IQUB also functions as a downstream effector of ARL3 in limiting primary cilia length; its depletion leads to cilia over-elongation, and re-expression rescues this phenotype [PMID:21289087, PMID:38457249]. Homozygous loss-of-function IQUB mutations cause asthenoteratozoospermia and male infertility in humans [PMID:39849482].\",\n  \"teleology\": [\n    {\n      \"year\": 2011,\n      \"claim\": \"Whether IQUB had any ciliary function was unknown; siRNA knockdown established that IQUB limits cilia length and participates in Hedgehog signaling, identifying it as a ciliary regulatory factor.\",\n      \"evidence\": \"siRNA knockdown with cilia length quantification and Gli-luciferase Hedgehog assay in three mammalian cell lines\",\n      \"pmids\": [\"21289087\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which IQUB controls cilia length was not defined\", \"Whether IQUB acts in motile cilia/flagella was untested\", \"Upstream regulators of IQUB expression unknown\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Whether IQUB influenced proliferative signaling outside the cilium was unknown; overexpression and knockdown showed IQUB activates the Akt/GSK3β/β-catenin pathway to promote breast cancer cell proliferation and migration.\",\n      \"evidence\": \"Gain- and loss-of-function with pharmacological epistasis (LiCl, MG-132) in MCF-7 and MDA-MB-231 breast cancer cells\",\n      \"pmids\": [\"29968965\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Relevance to non-cancer physiology unclear\", \"No in vivo tumor model validation\", \"Mechanism linking IQUB's IQ domains to Akt activation not identified\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"The role of IQUB in motile flagella was unknown; Iqub knockout mice revealed that IQUB is essential for assembly of the entire radial spoke 1 in sperm flagella, causing male infertility, while being dispensable for RS1 in tracheal cilia.\",\n      \"evidence\": \"Iqub knockout mouse with cryo-electron tomography, transmission EM, and proteomics of sperm RS1\",\n      \"pmids\": [\"36417862\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Precise position of IQUB within RS1 architecture was not resolved\", \"Why tracheal cilia RS1 is independent of IQUB was unexplained\", \"Downstream signaling consequences of RS1 loss not addressed\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"How IQUB contributes to RS1 assembly at the molecular level was unclear; interaction mapping and signaling analysis showed IQUB binds RSPH3 and calmodulin, and recruits calmodulin under low-Ca²⁺ conditions to inhibit the RSPH3/p-ERK1/2 complex, linking radial spoke assembly to an AKAP-like signaling module.\",\n      \"evidence\": \"Yeast two-hybrid screen, co-immunoprecipitation, Iqub KO/KI mouse models, Western blot for p-ERK1/2\",\n      \"pmids\": [\"36355624\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Calmodulin recruitment mechanism lacks direct structural validation\", \"Whether p-ERK1/2 dysregulation is a cause or consequence of RS1 disassembly is ambiguous\", \"In vitro reconstitution of the IQUB–calmodulin–RSPH3 complex not performed\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Whether IQUB's cilia-length role was connected to known ciliopathy pathways was unknown; IQUB was identified as a downstream effector of ARL3, with rescue of elongated cilia in ARL3-mutant patient fibroblasts confirming IQUB as the functional mediator.\",\n      \"evidence\": \"Patient-derived immortalized fibroblasts with ARL3 compound heterozygous mutations, RNA-seq, proteomics, IQUB re-expression rescue\",\n      \"pmids\": [\"38457249\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which ARL3 regulates IQUB expression or stability not defined\", \"Whether this pathway operates in motile cilia/flagella is untested\", \"Single patient genotype limits generalizability\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"The precise structural position of IQUB in RS1 and its loss-of-function consequences in humans were undefined; a human frameshift mutation combined with mouse KO showed IQUB forms part of the RS1 stalk, and its loss selectively eliminates RS1 with secondary loss of inner dynein arms DNAH7 and DNAH12.\",\n      \"evidence\": \"Whole-exome sequencing of infertile patient, Iqub−/− mouse, mass spectrometry, EM, structural modeling\",\n      \"pmids\": [\"39849482\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Atomic-resolution structure of the RS1 stalk with IQUB is lacking\", \"How RS1 loss causes secondary inner dynein arm downregulation is mechanistically unresolved\", \"Whether IQUB mutations contribute to female subfertility is unknown\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How IQUB's dual roles in primary cilia length regulation (via ARL3) and motile flagella RS1 assembly are coordinated, and the structural basis of IQUB-calmodulin interaction within the RS1 stalk, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No atomic structure of IQUB or IQUB-containing RS1 complex\", \"Tissue-specific regulation of IQUB's cilia-length vs. RS1-assembly functions not understood\", \"Relationship between IQ-domain calmodulin binding and RS1 structural integrity undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [2, 6]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005929\", \"supporting_discovery_ids\": [0, 2, 4, 5, 6]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0005929\", \"supporting_discovery_ids\": []},\n      {\"term_id\": \"R-HSA-1852241\", \"supporting_discovery_ids\": [0, 2, 5, 6]},\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [2, 6]}\n    ],\n    \"complexes\": [\"Radial spoke 1 (RS1)\"],\n    \"partners\": [\"RSPH3\", \"DNAJB13\", \"NME5\", \"ODF1\", \"GSTM1\", \"CEP295NL\", \"DYNLL1\", \"RSPH6A\"],\n    \"other_free_text\": []\n  }\n}\n```"}