{"gene":"HOOK1","run_date":"2026-06-10T01:55:22","timeline":{"discoveries":[{"year":2002,"finding":"Hook1 is responsible for linking the microtubular manchette and flagellum to cellular structures in spermatids; deletion of exons 10 and 11 creates a non-functional protein causing ectopic positioning of microtubular structures and the azh phenotype (abnormal sperm head shape and tail defects)","method":"Genetic mapping, cDNA isolation, genomic structure analysis, immunohistochemistry in azh mutant mice","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — loss-of-function mutation identified and validated with immunohistochemistry, replicated across multiple analyses in a well-characterized mouse model","pmids":["12075009"],"is_preprint":false},{"year":2004,"finding":"Hook1 physically interacts with endocytic Rab7, Rab9, and Rab11, placing it at the intersection of microtubule cytoskeleton and endocytic membrane trafficking; overexpression of CLN3 induces aggregation of Hook1, potentially by mediating its dissociation from microtubules; weak direct interaction between Hook1 and the cytoplasmic segments of CLN3 was demonstrated","method":"Co-immunoprecipitation, in vitro binding assay","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-IP for Rab interactions and in vitro binding for CLN3, single lab with two orthogonal methods","pmids":["15471887"],"is_preprint":false},{"year":2005,"finding":"Hook1 interacts with Ankyrin G (an adaptor protein bridging the spectrin-actin cytoskeleton and peripheral membrane targeting), and the two proteins co-localize; Hook1 also localizes to additional regions devoid of Ankyrin G, suggesting multiple binding partners","method":"Co-immunoprecipitation, co-localization immunofluorescence","journal":"Biochemical and biophysical research communications","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP and co-localization, single lab, no functional consequence established for this specific interaction","pmids":["15823567"],"is_preprint":false},{"year":2013,"finding":"Hook1 acts as a microtubule- and cargo-tethering protein that recognizes the cytoplasmic tail of CD147 and sorts CD147 and CD98 into Rab22a-dependent tubules for recycling back to the plasma membrane; depletion of Hook1 redirects CD44, CD98, and CD147 toward EEA1 compartments, impairs CD98 recycling to the PM, and inhibits cell spreading; MHC class I trafficking (normally routed to EEA1 compartments) is not affected by Hook1 depletion","method":"siRNA depletion, trafficking/recycling assays, fluorescence microscopy, cell spreading assay","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple CIE cargo proteins tested, loss-of-function with defined phenotypic readouts, specific cargo-tail recognition established, negative control (MHC-I) included","pmids":["23589492"],"is_preprint":false},{"year":2013,"finding":"Hook1, microtubules, and Rab22a work in coordination as an endosomal sorting machinery to route clathrin-independent endocytosis (CIE) cargo (CD44, CD98, CD147) into recycling endosomal tubules and back to the plasma membrane","method":"Review/commentary elaborating on experimental findings from PMID:23589492","journal":"Bioarchitecture","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mechanistic model supported by the primary research paper; this review provides additional context but relies on same experimental data","pmids":["24284901"],"is_preprint":false},{"year":2014,"finding":"Hook1 directly interacts with both the protein-tyrosine phosphatase domain and N-terminal SH2 domain of SHP2; Hook1 functions as an endogenous negative regulator of SHP2 phosphatase activity; down-regulation of Hook1 increases SHP2 activity and promotes TGFβ1-induced EMT, while overexpression of Hook1 inhibits EMT","method":"Yeast two-hybrid (bait: SHP2 PTP domain), co-immunoprecipitation, siRNA knockdown, overexpression, phosphatase activity assay","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct interaction confirmed by co-IP, functional consequence shown by knockdown/overexpression with activity assay, single lab with two orthogonal methods","pmids":["25331952"],"is_preprint":false},{"year":2017,"finding":"Ccdc181 directly interacts with Hook1 in haploid male germ cells; both proteins localize to the microtubular manchette of elongating spermatids; the interacting regions were mapped using yeast two-hybrid assays","method":"Yeast two-hybrid screen with testicular library, FRET analysis, immunofluorescence localization","journal":"European journal of cell biology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — interaction validated by FRET in addition to yeast two-hybrid, co-localization shown, single lab","pmids":["28283191"],"is_preprint":false},{"year":2018,"finding":"Hypoxia enhances the interaction between CD147 and Hook1; interference with this interaction (via Rab22a knockdown) suppresses hypoxia-induced Aβ accumulation in exosomes, indicating that the CD147-Hook1 interaction is required for hypoxia-driven exosomal Aβ trafficking","method":"Co-immunoprecipitation in SH-SY5Y cells and in vivo in hypoxia-exposed mice, siRNA knockdown of Rab22a, ELISA for Aβ in exosomes","journal":"American journal of translational research","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-IP in cells and in vivo, functional rescue by Rab22a knockdown, single lab with two orthogonal approaches","pmids":["29423001"],"is_preprint":false},{"year":2022,"finding":"γ-Taxilin negatively regulates Hook1-mediated endosomal sorting: it binds to the C-terminal region of Hook1 and inhibits Hook1's interaction with its cargo CD98, thereby blocking CD98-positive tubular formation and recycling; depletion of Hook1, Rab10, or Rab22a attenuates the effect of γ-taxilin depletion on tubular formation","method":"Co-immunoprecipitation (interaction mapping), siRNA depletion of γ-taxilin/Hook1/Rab10/Rab22a, fluorescence microscopy of tubular formation, CD98 recycling assay, cell spreading assay","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — binding domain mapped by co-IP, epistasis established via multiple depletions, functional consequence in cargo recycling and cell spreading confirmed","pmids":["34897470"],"is_preprint":false},{"year":2023,"finding":"HOOK1 inhibits RCC tumor growth and metastasis via canonical TGF-β/ALK5/p-Smad3 and non-canonical TGF-β/MEK/ERK/c-Myc pathways; HOOK1 promotes degradation of TNFSF13B through the ubiquitin-proteasome pathway to inhibit angiogenesis; HOOK1 transcription is regulated by E2F3 in a VHL-dependent manner","method":"siRNA knockdown, overexpression, Western blot for pathway components, ubiquitin-proteasome inhibitor assays, ChIP or transcription factor binding assays (implied)","journal":"Advanced science","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — multiple pathway components assessed by knockdown/overexpression in single lab; proteasome pathway functional link established biochemically","pmids":["37085921"],"is_preprint":false},{"year":2024,"finding":"Loss of HOOK1 (by CRISPR/Cas9) in ovarian cancer cells increases endoplasmic reticulum stress via the unfolded protein response, leading to cell death specifically in the cancer stem cell population; HOOK1 thus maintains protein homeostasis and stemness properties; proteomic analysis revealed altered protein networks upon HOOK1 depletion","method":"CRISPR/Cas9 knockout, proteomic mass spectrometry, Western blot, flow cytometry, immunofluorescence, in vivo tumor formation assay","journal":"Journal of experimental & clinical cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — CRISPR KO with proteomic analysis and multiple orthogonal readouts in single lab","pmids":["38807192"],"is_preprint":false}],"current_model":"HOOK1 is a microtubule- and cargo-tethering protein that links the microtubular manchette/flagellum to cellular structures in spermatids (loss causing abnormal sperm morphology), acts as an endosomal cargo adaptor that recognizes cytoplasmic tails of clathrin-independent endocytosis (CIE) cargo proteins (CD44, CD98, CD147) and—together with Rab22a and microtubules—sorts them into recycling tubules for return to the plasma membrane; this activity is negatively regulated by γ-taxilin binding to Hook1's C-terminus; Hook1 also interacts with Rab7, Rab9, Rab11, Ankyrin G, and CLN3, functions as an endogenous inhibitor of SHP2 phosphatase activity, promotes TNFSF13B degradation via the ubiquitin-proteasome pathway, and maintains protein homeostasis to support cancer cell stemness."},"narrative":{"mechanistic_narrative":"HOOK1 is a microtubule- and cargo-tethering protein that couples the microtubule cytoskeleton to membrane structures, functioning in both spermatid morphogenesis and endosomal cargo sorting [PMID:12075009, PMID:23589492]. In spermatids it links the microtubular manchette and flagellum to cellular structures, and a loss-of-function allele deleting exons 10–11 produces ectopic microtubular positioning and the azh phenotype of abnormal sperm head and tail morphology [PMID:12075009]. As an endosomal adaptor, HOOK1 recognizes the cytoplasmic tails of clathrin-independent endocytosis (CIE) cargo such as CD147 and, in coordination with Rab22a and microtubules, sorts CD44, CD98, and CD147 into recycling tubules that return them to the plasma membrane, with HOOK1 depletion misrouting these cargoes to EEA1 compartments and impairing cell spreading [PMID:23589492]. This sorting activity is negatively regulated by γ-taxilin, which binds the HOOK1 C-terminus and blocks its interaction with CD98 cargo to suppress tubular recycling [PMID:34897470]. Beyond trafficking, HOOK1 directly binds the SH2 and phosphatase domains of SHP2 and acts as an endogenous inhibitor of SHP2 activity, thereby restraining TGFβ1-induced EMT [PMID:25331952], and in renal cell carcinoma it suppresses tumor growth and metastasis through TGF-β signaling axes while promoting ubiquitin-proteasome-mediated degradation of TNFSF13B [PMID:37085921]. In ovarian cancer stem cells, HOOK1 maintains protein homeostasis, and its loss elevates ER stress through the unfolded protein response to selectively kill the stem cell population [PMID:38807192].","teleology":[{"year":2002,"claim":"Established HOOK1's foundational role in tethering microtubular structures, answering whether the azh sperm phenotype reflects a defect in linking the manchette and flagellum to the cell.","evidence":"Genetic mapping and immunohistochemistry of a loss-of-function deletion allele in azh mutant mice","pmids":["12075009"],"confidence":"High","gaps":["Molecular partners mediating manchette tethering not identified","Does not address non-germline functions"]},{"year":2004,"claim":"Placed HOOK1 at the intersection of microtubules and endocytic trafficking by showing physical interaction with endosomal Rab GTPases and CLN3.","evidence":"Co-immunoprecipitation of Rab7/Rab9/Rab11 and in vitro binding to CLN3 cytoplasmic segments","pmids":["15471887"],"confidence":"Medium","gaps":["CLN3 interaction was weak","Functional consequence of Rab binding not established","Single lab"]},{"year":2005,"claim":"Linked HOOK1 to the spectrin-actin cytoskeleton via Ankyrin G, hinting at multiple membrane-targeting partners.","evidence":"Co-immunoprecipitation and co-localization immunofluorescence","pmids":["15823567"],"confidence":"Low","gaps":["Single Co-IP and co-localization with no reciprocal validation","No functional consequence established","HOOK1 localizes to regions devoid of Ankyrin G, implying unidentified partners"]},{"year":2013,"claim":"Defined HOOK1 as a CIE cargo adaptor, answering how clathrin-independent cargo is selected for recycling rather than degradation.","evidence":"siRNA depletion, cargo trafficking/recycling assays and cell spreading assay with MHC-I negative control","pmids":["23589492","24284901"],"confidence":"High","gaps":["Structural basis of cytoplasmic tail recognition not resolved","How HOOK1 couples cargo to Rab22a tubules mechanistically unknown"]},{"year":2014,"claim":"Revealed a signaling function distinct from trafficking by identifying HOOK1 as a direct endogenous inhibitor of SHP2 phosphatase and thereby a brake on EMT.","evidence":"Yeast two-hybrid, co-IP, knockdown/overexpression with phosphatase activity assay","pmids":["25331952"],"confidence":"Medium","gaps":["Structural mechanism of SHP2 inhibition unresolved","Single lab","Relationship between trafficking and signaling roles unclear"]},{"year":2017,"claim":"Identified Ccdc181 as a germ-cell partner localizing with HOOK1 at the manchette, extending the spermatid tethering model molecularly.","evidence":"Yeast two-hybrid screen with testicular library, FRET, and immunofluorescence","pmids":["28283191"],"confidence":"Medium","gaps":["Functional consequence of the interaction in spermatids not tested","Single lab"]},{"year":2018,"claim":"Showed the CD147-HOOK1 interaction is co-opted under hypoxia to drive exosomal Aβ trafficking, connecting cargo adaptor function to disease-relevant secretion.","evidence":"Co-IP in SH-SY5Y cells and hypoxic mice, Rab22a knockdown rescue, exosome Aβ ELISA","pmids":["29423001"],"confidence":"Medium","gaps":["Mechanism linking HOOK1 sorting to exosome loading not detailed","Single lab"]},{"year":2022,"claim":"Identified γ-taxilin as a negative regulator that gates HOOK1 cargo binding, answering how the recycling pathway is switched off.","evidence":"Co-IP interaction mapping, epistatic siRNA depletions of γ-taxilin/Hook1/Rab10/Rab22a, recycling and cell spreading assays","pmids":["34897470"],"confidence":"High","gaps":["Signals controlling γ-taxilin binding unknown","Structural basis of C-terminal regulation not resolved"]},{"year":2023,"claim":"Established HOOK1 as a tumor suppressor in RCC acting through TGF-β pathways and ubiquitin-proteasome degradation of TNFSF13B, and placed it under E2F3/VHL transcriptional control.","evidence":"Knockdown/overexpression, Western blot, proteasome inhibitor assays, transcription factor binding assays","pmids":["37085921"],"confidence":"Medium","gaps":["Direct vs indirect role in TNFSF13B ubiquitination not resolved","Single lab"]},{"year":2024,"claim":"Connected HOOK1 to proteostasis in cancer stem cells, showing its loss triggers ER stress/UPR-driven death selectively in the stem population.","evidence":"CRISPR/Cas9 knockout, proteomic mass spectrometry, flow cytometry, in vivo tumor assays","pmids":["38807192"],"confidence":"Medium","gaps":["Mechanism linking HOOK1 trafficking to proteostasis unclear","Single lab"]},{"year":null,"claim":"How HOOK1's microtubule-tethering, cargo-adaptor, signaling-inhibitor, and proteostasis roles are mechanistically unified within a single protein remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model linking cargo, Rab, and microtubule binding","Whether SHP2 inhibition and endosomal sorting are coupled is unknown","Mechanism of TNFSF13B degradation and proteostasis maintenance undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[3,8]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[0,3]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[5,8]}],"localization":[{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[0,6]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[1,3]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[3,8]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[5,9]}],"complexes":[],"partners":["CD147","CD98","SHP2","RAB22A","CCDC181","CLN3","ANK3","TXLNG"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9UJC3","full_name":"Protein Hook homolog 1","aliases":[],"length_aa":728,"mass_kda":84.6,"function":"Component of the FTS/Hook/FHIP complex (FHF complex) (PubMed:18799622, PubMed:32073997). The FHF complex may function to promote vesicle trafficking and/or fusion via the homotypic vesicular protein sorting complex (the HOPS complex) (PubMed:18799622). FHF complex promotes the distribution of AP-4 complex to the perinuclear area of the cell (PubMed:32073997). Required for spermatid differentiation. Probably involved in the positioning of the microtubules of the manchette and the flagellum in relation to the membrane skeleton (By similarity)","subcellular_location":"Cytoplasm; Cytoplasm, cytoskeleton","url":"https://www.uniprot.org/uniprotkb/Q9UJC3/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/HOOK1","classification":"Not Classified","n_dependent_lines":4,"n_total_lines":1208,"dependency_fraction":0.0033112582781456954},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"PRKACA","stoichiometry":0.2},{"gene":"TOMM20A","stoichiometry":0.2},{"gene":"VDAC1","stoichiometry":0.2},{"gene":"VDAC3","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/HOOK1","total_profiled":1310},"omim":[{"mim_id":"620891","title":"COILED-COIL DOMAIN-CONTAINING PROTEIN 181; CCDC181","url":"https://www.omim.org/entry/620891"},{"mim_id":"620302","title":"WD REPEAT-CONTAINING PROTEIN 76; WDR76","url":"https://www.omim.org/entry/620302"},{"mim_id":"620230","title":"FHF COMPLEX SUBUNIT HOOK-INTERACTING PROTEIN 2B; FHIP2B","url":"https://www.omim.org/entry/620230"},{"mim_id":"620229","title":"FHF COMPLEX SUBUNIT HOOK-INTERACTING PROTEIN 1B; FHIP1B","url":"https://www.omim.org/entry/620229"},{"mim_id":"617312","title":"FHF COMPLEX SUBUNIT HOOK-INTERACTING PROTEIN 2A; FHIP2A","url":"https://www.omim.org/entry/617312"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"retina","ntpm":46.7}],"url":"https://www.proteinatlas.org/search/HOOK1"},"hgnc":{"alias_symbol":["HK1"],"prev_symbol":[]},"alphafold":{"accession":"Q9UJC3","domains":[{"cath_id":"1.10.418.10","chopping":"15-163","consensus_level":"high","plddt":85.1948,"start":15,"end":163},{"cath_id":"1.20.5","chopping":"181-231","consensus_level":"medium","plddt":92.2084,"start":181,"end":231},{"cath_id":"1.20.5","chopping":"466-528","consensus_level":"medium","plddt":85.361,"start":466,"end":528},{"cath_id":"1.20.5","chopping":"622-669","consensus_level":"medium","plddt":85.4408,"start":622,"end":669}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UJC3","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UJC3-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UJC3-F1-predicted_aligned_error_v6.png","plddt_mean":82.44},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=HOOK1","jax_strain_url":"https://www.jax.org/strain/search?query=HOOK1"},"sequence":{"accession":"Q9UJC3","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9UJC3.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9UJC3/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UJC3"}},"corpus_meta":[{"pmid":"12075009","id":"PMC_12075009","title":"The Hook1 gene is non-functional in the abnormal spermatozoon head shape (azh) mutant mouse.","date":"2002","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/12075009","citation_count":136,"is_preprint":false},{"pmid":"15471887","id":"PMC_15471887","title":"Interconnections of CLN3, Hook1 and Rab proteins link Batten disease to defects in the endocytic pathway.","date":"2004","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/15471887","citation_count":122,"is_preprint":false},{"pmid":"23589492","id":"PMC_23589492","title":"Microtubule-dependent endosomal sorting of clathrin-independent cargo by Hook1.","date":"2013","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/23589492","citation_count":111,"is_preprint":false},{"pmid":"17101785","id":"PMC_17101785","title":"Btn2, a Hook1 ortholog and potential Batten disease-related protein, mediates late endosome-Golgi protein sorting in yeast.","date":"2006","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/17101785","citation_count":67,"is_preprint":false},{"pmid":"25331952","id":"PMC_25331952","title":"SHP2 positively regulates TGFβ1-induced epithelial-mesenchymal transition modulated by its novel interacting protein Hook1.","date":"2014","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/25331952","citation_count":42,"is_preprint":false},{"pmid":"28283191","id":"PMC_28283191","title":"Ccdc181 is a microtubule-binding protein that interacts with Hook1 in haploid male germ cells and localizes to the sperm tail and motile cilia.","date":"2017","source":"European journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/28283191","citation_count":41,"is_preprint":false},{"pmid":"24284901","id":"PMC_24284901","title":"Hook1, microtubules, and Rab22: mediators of selective sorting of clathrin-independent endocytic cargo proteins on endosomes.","date":"2013","source":"Bioarchitecture","url":"https://pubmed.ncbi.nlm.nih.gov/24284901","citation_count":35,"is_preprint":false},{"pmid":"37085921","id":"PMC_37085921","title":"HOOK1 Inhibits the Progression of Renal Cell Carcinoma via TGF-β and TNFSF13B/VEGF-A Axis.","date":"2023","source":"Advanced science (Weinheim, Baden-Wurttemberg, Germany)","url":"https://pubmed.ncbi.nlm.nih.gov/37085921","citation_count":26,"is_preprint":false},{"pmid":"29423001","id":"PMC_29423001","title":"Hypoxia increases amyloid-β level in exosomes by enhancing the interaction between CD147 and Hook1.","date":"2018","source":"American journal of translational research","url":"https://pubmed.ncbi.nlm.nih.gov/29423001","citation_count":23,"is_preprint":false},{"pmid":"15823567","id":"PMC_15823567","title":"Elevation of Hook1 in a disease model of Batten disease does not affect a novel interaction between Ankyrin G and Hook1.","date":"2005","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/15823567","citation_count":19,"is_preprint":false},{"pmid":"29431277","id":"PMC_29431277","title":"MeCP2 AT-Hook1 mutations in patients with intellectual disability and/or schizophrenia disrupt DNA binding and chromatin compaction in vitro.","date":"2018","source":"Human mutation","url":"https://pubmed.ncbi.nlm.nih.gov/29431277","citation_count":17,"is_preprint":false},{"pmid":"17314312","id":"PMC_17314312","title":"Preservation of ejaculated mouse spermatozoa from fertile C57BL/6 and infertile Hook1/Hook1 mice collected from the uteri of mated females.","date":"2007","source":"Biology of reproduction","url":"https://pubmed.ncbi.nlm.nih.gov/17314312","citation_count":16,"is_preprint":false},{"pmid":"28718370","id":"PMC_28718370","title":"Hook1 inhibits malignancy and epithelial-mesenchymal transition in hepatocellular carcinoma.","date":"2017","source":"Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine","url":"https://pubmed.ncbi.nlm.nih.gov/28718370","citation_count":10,"is_preprint":false},{"pmid":"34897470","id":"PMC_34897470","title":"Regulation of Hook1-mediated endosomal sorting of clathrin-independent cargo by γ-taxilin.","date":"2022","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/34897470","citation_count":6,"is_preprint":false},{"pmid":"28399682","id":"PMC_28399682","title":"Clinical, Molecular, and Computational Analysis in Patients With a Novel Double Mutation and a New Synonymous Variant in MeCP2: Report of the First Missense Mutation Within the AT-hook1 Cluster in Rett Syndrome.","date":"2017","source":"Journal of child neurology","url":"https://pubmed.ncbi.nlm.nih.gov/28399682","citation_count":6,"is_preprint":false},{"pmid":"38807192","id":"PMC_38807192","title":"Protein homeostasis maintained by HOOK1 levels promotes the tumorigenic and stemness properties of ovarian cancer cells through reticulum stress and autophagy.","date":"2024","source":"Journal of experimental & clinical cancer research : CR","url":"https://pubmed.ncbi.nlm.nih.gov/38807192","citation_count":5,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9726,"output_tokens":2810,"usd":0.035664,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":10149,"output_tokens":3272,"usd":0.066272,"stage2_stop_reason":"end_turn"},"total_usd":0.101936,"stage1_batch_id":"msgbatch_01DUPACZi7AAWwuZiUjseQF4","stage2_batch_id":"msgbatch_018yt7chE3f48PEFtDwtj6AE","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2002,\n      \"finding\": \"Hook1 is responsible for linking the microtubular manchette and flagellum to cellular structures in spermatids; deletion of exons 10 and 11 creates a non-functional protein causing ectopic positioning of microtubular structures and the azh phenotype (abnormal sperm head shape and tail defects)\",\n      \"method\": \"Genetic mapping, cDNA isolation, genomic structure analysis, immunohistochemistry in azh mutant mice\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — loss-of-function mutation identified and validated with immunohistochemistry, replicated across multiple analyses in a well-characterized mouse model\",\n      \"pmids\": [\"12075009\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Hook1 physically interacts with endocytic Rab7, Rab9, and Rab11, placing it at the intersection of microtubule cytoskeleton and endocytic membrane trafficking; overexpression of CLN3 induces aggregation of Hook1, potentially by mediating its dissociation from microtubules; weak direct interaction between Hook1 and the cytoplasmic segments of CLN3 was demonstrated\",\n      \"method\": \"Co-immunoprecipitation, in vitro binding assay\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-IP for Rab interactions and in vitro binding for CLN3, single lab with two orthogonal methods\",\n      \"pmids\": [\"15471887\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Hook1 interacts with Ankyrin G (an adaptor protein bridging the spectrin-actin cytoskeleton and peripheral membrane targeting), and the two proteins co-localize; Hook1 also localizes to additional regions devoid of Ankyrin G, suggesting multiple binding partners\",\n      \"method\": \"Co-immunoprecipitation, co-localization immunofluorescence\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP and co-localization, single lab, no functional consequence established for this specific interaction\",\n      \"pmids\": [\"15823567\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Hook1 acts as a microtubule- and cargo-tethering protein that recognizes the cytoplasmic tail of CD147 and sorts CD147 and CD98 into Rab22a-dependent tubules for recycling back to the plasma membrane; depletion of Hook1 redirects CD44, CD98, and CD147 toward EEA1 compartments, impairs CD98 recycling to the PM, and inhibits cell spreading; MHC class I trafficking (normally routed to EEA1 compartments) is not affected by Hook1 depletion\",\n      \"method\": \"siRNA depletion, trafficking/recycling assays, fluorescence microscopy, cell spreading assay\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple CIE cargo proteins tested, loss-of-function with defined phenotypic readouts, specific cargo-tail recognition established, negative control (MHC-I) included\",\n      \"pmids\": [\"23589492\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Hook1, microtubules, and Rab22a work in coordination as an endosomal sorting machinery to route clathrin-independent endocytosis (CIE) cargo (CD44, CD98, CD147) into recycling endosomal tubules and back to the plasma membrane\",\n      \"method\": \"Review/commentary elaborating on experimental findings from PMID:23589492\",\n      \"journal\": \"Bioarchitecture\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mechanistic model supported by the primary research paper; this review provides additional context but relies on same experimental data\",\n      \"pmids\": [\"24284901\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Hook1 directly interacts with both the protein-tyrosine phosphatase domain and N-terminal SH2 domain of SHP2; Hook1 functions as an endogenous negative regulator of SHP2 phosphatase activity; down-regulation of Hook1 increases SHP2 activity and promotes TGFβ1-induced EMT, while overexpression of Hook1 inhibits EMT\",\n      \"method\": \"Yeast two-hybrid (bait: SHP2 PTP domain), co-immunoprecipitation, siRNA knockdown, overexpression, phosphatase activity assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct interaction confirmed by co-IP, functional consequence shown by knockdown/overexpression with activity assay, single lab with two orthogonal methods\",\n      \"pmids\": [\"25331952\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Ccdc181 directly interacts with Hook1 in haploid male germ cells; both proteins localize to the microtubular manchette of elongating spermatids; the interacting regions were mapped using yeast two-hybrid assays\",\n      \"method\": \"Yeast two-hybrid screen with testicular library, FRET analysis, immunofluorescence localization\",\n      \"journal\": \"European journal of cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — interaction validated by FRET in addition to yeast two-hybrid, co-localization shown, single lab\",\n      \"pmids\": [\"28283191\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Hypoxia enhances the interaction between CD147 and Hook1; interference with this interaction (via Rab22a knockdown) suppresses hypoxia-induced Aβ accumulation in exosomes, indicating that the CD147-Hook1 interaction is required for hypoxia-driven exosomal Aβ trafficking\",\n      \"method\": \"Co-immunoprecipitation in SH-SY5Y cells and in vivo in hypoxia-exposed mice, siRNA knockdown of Rab22a, ELISA for Aβ in exosomes\",\n      \"journal\": \"American journal of translational research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-IP in cells and in vivo, functional rescue by Rab22a knockdown, single lab with two orthogonal approaches\",\n      \"pmids\": [\"29423001\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"γ-Taxilin negatively regulates Hook1-mediated endosomal sorting: it binds to the C-terminal region of Hook1 and inhibits Hook1's interaction with its cargo CD98, thereby blocking CD98-positive tubular formation and recycling; depletion of Hook1, Rab10, or Rab22a attenuates the effect of γ-taxilin depletion on tubular formation\",\n      \"method\": \"Co-immunoprecipitation (interaction mapping), siRNA depletion of γ-taxilin/Hook1/Rab10/Rab22a, fluorescence microscopy of tubular formation, CD98 recycling assay, cell spreading assay\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — binding domain mapped by co-IP, epistasis established via multiple depletions, functional consequence in cargo recycling and cell spreading confirmed\",\n      \"pmids\": [\"34897470\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"HOOK1 inhibits RCC tumor growth and metastasis via canonical TGF-β/ALK5/p-Smad3 and non-canonical TGF-β/MEK/ERK/c-Myc pathways; HOOK1 promotes degradation of TNFSF13B through the ubiquitin-proteasome pathway to inhibit angiogenesis; HOOK1 transcription is regulated by E2F3 in a VHL-dependent manner\",\n      \"method\": \"siRNA knockdown, overexpression, Western blot for pathway components, ubiquitin-proteasome inhibitor assays, ChIP or transcription factor binding assays (implied)\",\n      \"journal\": \"Advanced science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — multiple pathway components assessed by knockdown/overexpression in single lab; proteasome pathway functional link established biochemically\",\n      \"pmids\": [\"37085921\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Loss of HOOK1 (by CRISPR/Cas9) in ovarian cancer cells increases endoplasmic reticulum stress via the unfolded protein response, leading to cell death specifically in the cancer stem cell population; HOOK1 thus maintains protein homeostasis and stemness properties; proteomic analysis revealed altered protein networks upon HOOK1 depletion\",\n      \"method\": \"CRISPR/Cas9 knockout, proteomic mass spectrometry, Western blot, flow cytometry, immunofluorescence, in vivo tumor formation assay\",\n      \"journal\": \"Journal of experimental & clinical cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — CRISPR KO with proteomic analysis and multiple orthogonal readouts in single lab\",\n      \"pmids\": [\"38807192\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"HOOK1 is a microtubule- and cargo-tethering protein that links the microtubular manchette/flagellum to cellular structures in spermatids (loss causing abnormal sperm morphology), acts as an endosomal cargo adaptor that recognizes cytoplasmic tails of clathrin-independent endocytosis (CIE) cargo proteins (CD44, CD98, CD147) and—together with Rab22a and microtubules—sorts them into recycling tubules for return to the plasma membrane; this activity is negatively regulated by γ-taxilin binding to Hook1's C-terminus; Hook1 also interacts with Rab7, Rab9, Rab11, Ankyrin G, and CLN3, functions as an endogenous inhibitor of SHP2 phosphatase activity, promotes TNFSF13B degradation via the ubiquitin-proteasome pathway, and maintains protein homeostasis to support cancer cell stemness.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"HOOK1 is a microtubule- and cargo-tethering protein that couples the microtubule cytoskeleton to membrane structures, functioning in both spermatid morphogenesis and endosomal cargo sorting [#0, #3]. In spermatids it links the microtubular manchette and flagellum to cellular structures, and a loss-of-function allele deleting exons 10–11 produces ectopic microtubular positioning and the azh phenotype of abnormal sperm head and tail morphology [#0]. As an endosomal adaptor, HOOK1 recognizes the cytoplasmic tails of clathrin-independent endocytosis (CIE) cargo such as CD147 and, in coordination with Rab22a and microtubules, sorts CD44, CD98, and CD147 into recycling tubules that return them to the plasma membrane, with HOOK1 depletion misrouting these cargoes to EEA1 compartments and impairing cell spreading [#3]. This sorting activity is negatively regulated by γ-taxilin, which binds the HOOK1 C-terminus and blocks its interaction with CD98 cargo to suppress tubular recycling [#8]. Beyond trafficking, HOOK1 directly binds the SH2 and phosphatase domains of SHP2 and acts as an endogenous inhibitor of SHP2 activity, thereby restraining TGFβ1-induced EMT [#5], and in renal cell carcinoma it suppresses tumor growth and metastasis through TGF-β signaling axes while promoting ubiquitin-proteasome-mediated degradation of TNFSF13B [#9]. In ovarian cancer stem cells, HOOK1 maintains protein homeostasis, and its loss elevates ER stress through the unfolded protein response to selectively kill the stem cell population [#10].\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"Established HOOK1's foundational role in tethering microtubular structures, answering whether the azh sperm phenotype reflects a defect in linking the manchette and flagellum to the cell.\",\n      \"evidence\": \"Genetic mapping and immunohistochemistry of a loss-of-function deletion allele in azh mutant mice\",\n      \"pmids\": [\"12075009\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular partners mediating manchette tethering not identified\", \"Does not address non-germline functions\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Placed HOOK1 at the intersection of microtubules and endocytic trafficking by showing physical interaction with endosomal Rab GTPases and CLN3.\",\n      \"evidence\": \"Co-immunoprecipitation of Rab7/Rab9/Rab11 and in vitro binding to CLN3 cytoplasmic segments\",\n      \"pmids\": [\"15471887\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"CLN3 interaction was weak\", \"Functional consequence of Rab binding not established\", \"Single lab\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Linked HOOK1 to the spectrin-actin cytoskeleton via Ankyrin G, hinting at multiple membrane-targeting partners.\",\n      \"evidence\": \"Co-immunoprecipitation and co-localization immunofluorescence\",\n      \"pmids\": [\"15823567\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single Co-IP and co-localization with no reciprocal validation\", \"No functional consequence established\", \"HOOK1 localizes to regions devoid of Ankyrin G, implying unidentified partners\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Defined HOOK1 as a CIE cargo adaptor, answering how clathrin-independent cargo is selected for recycling rather than degradation.\",\n      \"evidence\": \"siRNA depletion, cargo trafficking/recycling assays and cell spreading assay with MHC-I negative control\",\n      \"pmids\": [\"23589492\", \"24284901\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of cytoplasmic tail recognition not resolved\", \"How HOOK1 couples cargo to Rab22a tubules mechanistically unknown\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Revealed a signaling function distinct from trafficking by identifying HOOK1 as a direct endogenous inhibitor of SHP2 phosphatase and thereby a brake on EMT.\",\n      \"evidence\": \"Yeast two-hybrid, co-IP, knockdown/overexpression with phosphatase activity assay\",\n      \"pmids\": [\"25331952\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural mechanism of SHP2 inhibition unresolved\", \"Single lab\", \"Relationship between trafficking and signaling roles unclear\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Identified Ccdc181 as a germ-cell partner localizing with HOOK1 at the manchette, extending the spermatid tethering model molecularly.\",\n      \"evidence\": \"Yeast two-hybrid screen with testicular library, FRET, and immunofluorescence\",\n      \"pmids\": [\"28283191\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of the interaction in spermatids not tested\", \"Single lab\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Showed the CD147-HOOK1 interaction is co-opted under hypoxia to drive exosomal Aβ trafficking, connecting cargo adaptor function to disease-relevant secretion.\",\n      \"evidence\": \"Co-IP in SH-SY5Y cells and hypoxic mice, Rab22a knockdown rescue, exosome Aβ ELISA\",\n      \"pmids\": [\"29423001\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism linking HOOK1 sorting to exosome loading not detailed\", \"Single lab\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Identified γ-taxilin as a negative regulator that gates HOOK1 cargo binding, answering how the recycling pathway is switched off.\",\n      \"evidence\": \"Co-IP interaction mapping, epistatic siRNA depletions of γ-taxilin/Hook1/Rab10/Rab22a, recycling and cell spreading assays\",\n      \"pmids\": [\"34897470\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Signals controlling γ-taxilin binding unknown\", \"Structural basis of C-terminal regulation not resolved\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Established HOOK1 as a tumor suppressor in RCC acting through TGF-β pathways and ubiquitin-proteasome degradation of TNFSF13B, and placed it under E2F3/VHL transcriptional control.\",\n      \"evidence\": \"Knockdown/overexpression, Western blot, proteasome inhibitor assays, transcription factor binding assays\",\n      \"pmids\": [\"37085921\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct vs indirect role in TNFSF13B ubiquitination not resolved\", \"Single lab\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Connected HOOK1 to proteostasis in cancer stem cells, showing its loss triggers ER stress/UPR-driven death selectively in the stem population.\",\n      \"evidence\": \"CRISPR/Cas9 knockout, proteomic mass spectrometry, flow cytometry, in vivo tumor assays\",\n      \"pmids\": [\"38807192\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism linking HOOK1 trafficking to proteostasis unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How HOOK1's microtubule-tethering, cargo-adaptor, signaling-inhibitor, and proteostasis roles are mechanistically unified within a single protein remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model linking cargo, Rab, and microtubule binding\", \"Whether SHP2 inhibition and endosomal sorting are coupled is unknown\", \"Mechanism of TNFSF13B degradation and proteostasis maintenance undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [3, 8]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [0, 3]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [5, 8]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [0, 6]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [1, 3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [3, 8]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [5, 9]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"CD147\", \"CD98\", \"SHP2\", \"Rab22a\", \"CCDC181\", \"CLN3\", \"ANK3\", \"TXLNG\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":6,"faith_pct":83.33333333333333}}