{"gene":"HSBP1","run_date":"2026-06-10T01:55:22","timeline":{"discoveries":[{"year":1998,"finding":"HSBP1 is a 76-amino-acid nuclear protein that interacts with the heptad repeats of the HSF1 trimerization domain via its own hydrophobic heptad repeats, binding specifically to the active trimeric state of HSF1 during heat shock. This interaction negatively affects HSF1 DNA-binding activity, and overexpression of HSBP1 in mammalian cells represses HSF1 transactivation activity. During attenuation of HSF1, HSBP1 associates with Hsp70.","method":"Yeast two-hybrid, in vivo co-immunoprecipitation, overexpression in mammalian cells (transactivation assay), C. elegans overexpression with heat shock promoter-reporter construct","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal interaction assays, functional overexpression in two model systems (mammalian cells and C. elegans), multiple orthogonal methods in a single rigorous study","pmids":["9649501"],"is_preprint":false},{"year":1998,"finding":"HSBP1 is nuclear-localized in mammalian cells.","method":"Subcellular localization by direct imaging/fractionation","journal":"Genes & development","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — localization reported in the same rigorous multi-method study but localization itself described by a single approach","pmids":["9649501"],"is_preprint":false},{"year":2013,"finding":"Loss of HSBP1 in mouse embryoid bodies leads to disorganized germ layers, reduced endoderm markers (α-fetoprotein), elevated expression of neural crest inducers (Snail2, Tfap2α, Foxd3), and elevated HSF1 activity and Hsp expression. Knockdown of HSBP1 in zebrafish produces similar phenotypes, establishing an essential role for HSBP1 in early embryonic development and in suppressing HSF1 activity in vivo.","method":"Targeted gene disruption (knockout mice), morpholino knockdown in zebrafish, embryoid body differentiation assays, reporter/marker expression analysis","journal":"Developmental biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — loss-of-function in two independent model organisms with defined molecular phenotypes (elevated HSF1 activity, altered lineage markers)","pmids":["24380799"],"is_preprint":false},{"year":2017,"finding":"HSBP1 (HSPB1) undergoes pH-dependent structural changes mediated by protonation of His124; acquisition of a positive charge (protonation or H124K substitution) destabilizes the α-crystallin domain dimer interface, increases oligomeric size, and modestly increases chaperone holdase activity.","method":"Site-directed mutagenesis (H124K), biophysical analysis of oligomeric state, chaperone activity assay","journal":"Cell stress & chaperones","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — in vitro mutagenesis and functional assay in a single lab study; note this paper may discuss HSPB1 (the sHSP) rather than the 76-aa HSBP1, though it is indexed under HSBP1","pmids":["28332148"],"is_preprint":false},{"year":2018,"finding":"HSBP1 functions as a trimeric coiled-coil protein that localizes to centrosomes and promotes WASH complex assembly by dissociating the CCDC53 homotrimeric precursor, enabling formation of a ternary CCDC53–WASH–FAM21 complex. HSBP1 depletion phenocopies WASH depletion, impairs focal adhesion development and cell polarity, and reduces cell migration and invasion. HSBP1 is required for endosomal recycling of α5β1 integrins via the WASH/Arp2/3 pathway.","method":"Co-immunoprecipitation, pulldown, depletion (siRNA/shRNA) in human cancer cell lines and Dictyostelium, rescue experiments, focal adhesion and polarity assays, migration/invasion assays, centrosome localization by imaging","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, functional rescue, two independent organisms (human cells and Dictyostelium), multiple orthogonal readouts","pmids":["29844016"],"is_preprint":false},{"year":2021,"finding":"HSBP1 is a novel cytoplasmic coiled-coil protein that interacts with the ULK kinase complex subunits FIP200 and ATG13, binding them via FIP200. HSBP1 interaction with these complexes stabilizes ULK complex subunits and is required for autophagy induction; HSBP1 depletion reduces stability of ULK complex subunits and impairs autophagy initiation. Additionally, the FIP200–ATG13 subcomplex negatively regulates HSBP1's pro-picornaviral function.","method":"Co-immunoprecipitation, siRNA/CRISPR knockout, autophagy assays (LC3 flux, ULK complex stability), picornavirus replication assays","journal":"Frontiers in cellular and infection microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus KO with defined molecular and functional phenotypes, single lab, multiple orthogonal methods","pmids":["34869056"],"is_preprint":false},{"year":2025,"finding":"In fibroblasts stimulated by heat-inactivated S. aureus, HSBP1 is upregulated and mediates profibrotic effects (proliferation, expression of TGF-β1, VEGF, collagen I/III, α-SMA) and promotes autophagy (elevated LC3, Beclin-1, and autophagosomes); siRNA knockdown of HSBP1 reverses these effects and decreases autophagy.","method":"Proteomic analysis, siRNA knockdown, western blotting, immunofluorescence, transmission electron microscopy, flow cytometry","journal":"Wound repair and regeneration","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA knockdown with multiple molecular readouts and TEM confirmation of autophagy, single lab","pmids":["39823159"],"is_preprint":false}],"current_model":"HSBP1 is a small (76 aa) coiled-coil protein with multiple distinct molecular functions: in the nucleus it directly binds the heptad repeats of trimeric HSF1 to attenuate the heat shock transcriptional response (associating with Hsp70 during recovery); at centrosomes it acts as a trimeric scaffold that dissociates CCDC53 homotrimers to drive WASH complex assembly, thereby enabling Arp2/3-dependent endosomal actin branching, integrin recycling, focal adhesion formation, and cell polarity/migration; and in the cytoplasm it interacts with FIP200/ATG13 of the ULK complex to stabilize it and promote autophagy initiation, with this same interaction serving to restrain HSBP1's pro-picornaviral activity."},"narrative":{"mechanistic_narrative":"HSBP1 is a small coiled-coil protein that operates as a molecular hub across heat-shock attenuation, cytoskeletal remodeling, and autophagy [PMID:9649501, PMID:29844016, PMID:34869056]. In the nucleus, it binds the heptad repeats of the active trimeric form of HSF1 through its own hydrophobic heptad repeats, suppressing HSF1 DNA-binding and transactivation activity and associating with Hsp70 during attenuation of the heat-shock response [PMID:9649501]; loss of HSBP1 in mouse embryoid bodies and zebrafish elevates HSF1 activity and Hsp expression and disrupts germ-layer organization, establishing this repressive role as essential for early embryonic development [PMID:24380799]. As a trimeric coiled-coil scaffold at centrosomes, HSBP1 drives WASH complex assembly by dissociating the CCDC53 homotrimeric precursor to permit formation of the ternary CCDC53–WASH–FAM21 complex, thereby enabling endosomal recycling of α5β1 integrins, focal adhesion development, cell polarity, and migration/invasion via the WASH/Arp2/3 pathway [PMID:29844016]. In the cytoplasm, HSBP1 binds the ULK kinase complex through FIP200 (with ATG13), stabilizing ULK complex subunits to promote autophagy initiation, and this FIP200–ATG13 interaction also restrains an HSBP1 pro-picornaviral activity [PMID:34869056]. A pro-fibrotic, autophagy-promoting role for HSBP1 has also been documented in bacterially stimulated fibroblasts [PMID:39823159].","teleology":[{"year":1998,"claim":"Established HSBP1's founding function: how the heat-shock transcriptional response is attenuated once HSF1 trimerizes, by identifying a dedicated repressor of the active trimeric state.","evidence":"Yeast two-hybrid, reciprocal co-immunoprecipitation, overexpression transactivation assays in mammalian cells, and heat-shock reporter assays in C. elegans","pmids":["9649501"],"confidence":"High","gaps":["Did not resolve the stoichiometry of the HSBP1–HSF1–Hsp70 attenuation complex","Mechanism by which Hsp70 association completes HSF1 inactivation not defined"]},{"year":1998,"claim":"Placed HSBP1's HSF1-repressive activity in the correct compartment by demonstrating nuclear localization.","evidence":"Subcellular localization in mammalian cells","pmids":["9649501"],"confidence":"Medium","gaps":["Localization described by a single approach","Did not address the later-described centrosomal and cytoplasmic pools"]},{"year":2013,"claim":"Tested whether HSBP1's HSF1 repression matters physiologically, showing it is required in vivo for early development and for keeping HSF1 activity in check.","evidence":"Knockout mice (embryoid body differentiation) and zebrafish morpholino knockdown with lineage-marker and Hsp readouts","pmids":["24380799"],"confidence":"High","gaps":["Did not separate developmental defects caused by HSF1 derepression from HSF1-independent functions","Tissue-specific requirements not dissected"]},{"year":2018,"claim":"Revealed a function entirely distinct from transcriptional control: HSBP1 acts as a trimeric scaffold that chaperones WASH complex assembly, linking it to endosomal actin and integrin trafficking.","evidence":"Reciprocal Co-IP, pulldown, depletion/rescue in human cancer cells and Dictyostelium, centrosome imaging, focal adhesion/polarity and migration/invasion assays","pmids":["29844016"],"confidence":"High","gaps":["Structural basis for HSBP1-mediated CCDC53 homotrimer dissociation not resolved","How HSBP1 partitions between nuclear HSF1 and centrosomal WASH roles unknown"]},{"year":2021,"claim":"Connected HSBP1 to autophagy initiation by identifying it as a ULK-complex-associated protein that stabilizes FIP200/ATG13, and linked the same interaction to control of a pro-picornaviral activity.","evidence":"Co-IP mapping to FIP200, siRNA/CRISPR knockout, LC3 flux and ULK subunit stability assays, picornavirus replication assays","pmids":["34869056"],"confidence":"Medium","gaps":["Mechanism by which HSBP1 stabilizes ULK subunits not defined","Nature of HSBP1's pro-picornaviral activity and how FIP200–ATG13 restrains it unresolved","Single-lab study without reciprocal structural validation"]},{"year":2025,"claim":"Extended HSBP1's autophagy role to a disease-relevant context, implicating it in fibroblast-driven fibrosis downstream of bacterial stimulation.","evidence":"Proteomics, siRNA knockdown, western blot, immunofluorescence, TEM, and flow cytometry in S. aureus-stimulated fibroblasts","pmids":["39823159"],"confidence":"Medium","gaps":["Whether profibrotic effects depend on the ULK/autophagy axis versus other HSBP1 functions not established","Direct molecular partners in this setting not identified"]},{"year":null,"claim":"How HSBP1 coordinates its three biochemically separable activities—HSF1 repression, WASH assembly, and ULK stabilization—within a single 76-residue coiled-coil remains unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model integrating the heptad-repeat HSF1 interface with the trimeric scaffolding function","Regulatory signals partitioning HSBP1 between nucleus, centrosome, and cytoplasm unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[0,2]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[4]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,5]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,1]},{"term_id":"GO:0005815","term_label":"microtubule organizing center","supporting_discovery_ids":[4]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[5]}],"pathway":[{"term_id":"R-HSA-8953897","term_label":"Cellular responses to stimuli","supporting_discovery_ids":[0]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[5]},{"term_id":"R-HSA-9709957","term_label":"Sensory Perception","supporting_discovery_ids":[4]}],"complexes":["WASH complex","ULK kinase complex"],"partners":["HSF1","HSPA1A","CCDC53","WASHC1","FAM21","RB1CC1","ATG13"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O75506","full_name":"Heat shock factor-binding protein 1","aliases":["Nasopharyngeal carcinoma-associated antigen 13","NPC-A-13"],"length_aa":76,"mass_kda":8.5,"function":"Negative regulator of the heat shock response. Negatively affects HSF1 DNA-binding activity. May have a role in the suppression of the activation of the stress response during the aging process","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/O75506/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/HSBP1","classification":"Not Classified","n_dependent_lines":108,"n_total_lines":1208,"dependency_fraction":0.08940397350993377},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"WASF2","stoichiometry":4.0},{"gene":"ATG101","stoichiometry":0.2},{"gene":"CAPZB","stoichiometry":0.2},{"gene":"MIF","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/HSBP1","total_profiled":1310},"omim":[{"mim_id":"604553","title":"HEAT-SHOCK FACTOR-BINDING PROTEIN 1; HSBP1","url":"https://www.omim.org/entry/604553"},{"mim_id":"602195","title":"HEAT-SHOCK 27-KD PROTEIN 1; HSPB1","url":"https://www.omim.org/entry/602195"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nuclear speckles","reliability":"Supported"},{"location":"Plasma membrane","reliability":"Supported"},{"location":"Golgi apparatus","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/HSBP1"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"O75506","domains":[{"cath_id":"1.20.5","chopping":"28-53","consensus_level":"medium","plddt":98.0319,"start":28,"end":53}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O75506","model_url":"https://alphafold.ebi.ac.uk/files/AF-O75506-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O75506-F1-predicted_aligned_error_v6.png","plddt_mean":87.19},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=HSBP1","jax_strain_url":"https://www.jax.org/strain/search?query=HSBP1"},"sequence":{"accession":"O75506","fasta_url":"https://rest.uniprot.org/uniprotkb/O75506.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O75506/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O75506"}},"corpus_meta":[{"pmid":"9649501","id":"PMC_9649501","title":"Negative regulation of the heat shock transcriptional response by HSBP1.","date":"1998","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/9649501","citation_count":171,"is_preprint":false},{"pmid":"28332148","id":"PMC_28332148","title":"pH-dependent structural modulation is conserved in the human small heat shock protein HSBP1.","date":"2017","source":"Cell stress & chaperones","url":"https://pubmed.ncbi.nlm.nih.gov/28332148","citation_count":22,"is_preprint":false},{"pmid":"29844016","id":"PMC_29844016","title":"The trimeric coiled-coil HSBP1 protein promotes WASH complex assembly at centrosomes.","date":"2018","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/29844016","citation_count":19,"is_preprint":false},{"pmid":"24380799","id":"PMC_24380799","title":"An essential role for heat shock transcription factor binding protein 1 (HSBP1) during early embryonic development.","date":"2013","source":"Developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/24380799","citation_count":19,"is_preprint":false},{"pmid":"23572288","id":"PMC_23572288","title":"Genetic variations of HSBP1 gene and its effect on thermal performance traits in Chinese Holstein cattle.","date":"2013","source":"Molecular biology reports","url":"https://pubmed.ncbi.nlm.nih.gov/23572288","citation_count":11,"is_preprint":false},{"pmid":"26952354","id":"PMC_26952354","title":"Molecular cloning of hsf1 and hsbp1 cDNAs, and the expression of hsf1, hsbp1 and hsp70 under heat stress in the sea cucumber Apostichopus japonicus.","date":"2016","source":"Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/26952354","citation_count":10,"is_preprint":false},{"pmid":"24816843","id":"PMC_24816843","title":"Overexpression of HSBP1 is associated with resistance to radiotherapy in oral squamous epithelial carcinoma.","date":"2014","source":"Medical oncology (Northwood, London, England)","url":"https://pubmed.ncbi.nlm.nih.gov/24816843","citation_count":9,"is_preprint":false},{"pmid":"34869056","id":"PMC_34869056","title":"HSBP1 Is a Novel Interactor of FIP200 and ATG13 That Promotes Autophagy Initiation and Picornavirus Replication.","date":"2021","source":"Frontiers in cellular and infection microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/34869056","citation_count":7,"is_preprint":false},{"pmid":"39823159","id":"PMC_39823159","title":"Bacteria in hypertrophic scars promote scar formation through HSBP1-mediated autophagy.","date":"2025","source":"Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society","url":"https://pubmed.ncbi.nlm.nih.gov/39823159","citation_count":3,"is_preprint":false},{"pmid":"38830519","id":"PMC_38830519","title":"Structural and functional characterization of Hdh-HSBP1 and its involvement in heat stress and early development in Pacific abalone, Haliotis discus hannai.","date":"2024","source":"Fish & shellfish immunology","url":"https://pubmed.ncbi.nlm.nih.gov/38830519","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":6825,"output_tokens":2031,"usd":0.02547,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8954,"output_tokens":2736,"usd":0.056585,"stage2_stop_reason":"end_turn"},"total_usd":0.082055,"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\": 1998,\n      \"finding\": \"HSBP1 is a 76-amino-acid nuclear protein that interacts with the heptad repeats of the HSF1 trimerization domain via its own hydrophobic heptad repeats, binding specifically to the active trimeric state of HSF1 during heat shock. This interaction negatively affects HSF1 DNA-binding activity, and overexpression of HSBP1 in mammalian cells represses HSF1 transactivation activity. During attenuation of HSF1, HSBP1 associates with Hsp70.\",\n      \"method\": \"Yeast two-hybrid, in vivo co-immunoprecipitation, overexpression in mammalian cells (transactivation assay), C. elegans overexpression with heat shock promoter-reporter construct\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal interaction assays, functional overexpression in two model systems (mammalian cells and C. elegans), multiple orthogonal methods in a single rigorous study\",\n      \"pmids\": [\"9649501\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"HSBP1 is nuclear-localized in mammalian cells.\",\n      \"method\": \"Subcellular localization by direct imaging/fractionation\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — localization reported in the same rigorous multi-method study but localization itself described by a single approach\",\n      \"pmids\": [\"9649501\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Loss of HSBP1 in mouse embryoid bodies leads to disorganized germ layers, reduced endoderm markers (α-fetoprotein), elevated expression of neural crest inducers (Snail2, Tfap2α, Foxd3), and elevated HSF1 activity and Hsp expression. Knockdown of HSBP1 in zebrafish produces similar phenotypes, establishing an essential role for HSBP1 in early embryonic development and in suppressing HSF1 activity in vivo.\",\n      \"method\": \"Targeted gene disruption (knockout mice), morpholino knockdown in zebrafish, embryoid body differentiation assays, reporter/marker expression analysis\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — loss-of-function in two independent model organisms with defined molecular phenotypes (elevated HSF1 activity, altered lineage markers)\",\n      \"pmids\": [\"24380799\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"HSBP1 (HSPB1) undergoes pH-dependent structural changes mediated by protonation of His124; acquisition of a positive charge (protonation or H124K substitution) destabilizes the α-crystallin domain dimer interface, increases oligomeric size, and modestly increases chaperone holdase activity.\",\n      \"method\": \"Site-directed mutagenesis (H124K), biophysical analysis of oligomeric state, chaperone activity assay\",\n      \"journal\": \"Cell stress & chaperones\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro mutagenesis and functional assay in a single lab study; note this paper may discuss HSPB1 (the sHSP) rather than the 76-aa HSBP1, though it is indexed under HSBP1\",\n      \"pmids\": [\"28332148\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"HSBP1 functions as a trimeric coiled-coil protein that localizes to centrosomes and promotes WASH complex assembly by dissociating the CCDC53 homotrimeric precursor, enabling formation of a ternary CCDC53–WASH–FAM21 complex. HSBP1 depletion phenocopies WASH depletion, impairs focal adhesion development and cell polarity, and reduces cell migration and invasion. HSBP1 is required for endosomal recycling of α5β1 integrins via the WASH/Arp2/3 pathway.\",\n      \"method\": \"Co-immunoprecipitation, pulldown, depletion (siRNA/shRNA) in human cancer cell lines and Dictyostelium, rescue experiments, focal adhesion and polarity assays, migration/invasion assays, centrosome localization by imaging\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, functional rescue, two independent organisms (human cells and Dictyostelium), multiple orthogonal readouts\",\n      \"pmids\": [\"29844016\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"HSBP1 is a novel cytoplasmic coiled-coil protein that interacts with the ULK kinase complex subunits FIP200 and ATG13, binding them via FIP200. HSBP1 interaction with these complexes stabilizes ULK complex subunits and is required for autophagy induction; HSBP1 depletion reduces stability of ULK complex subunits and impairs autophagy initiation. Additionally, the FIP200–ATG13 subcomplex negatively regulates HSBP1's pro-picornaviral function.\",\n      \"method\": \"Co-immunoprecipitation, siRNA/CRISPR knockout, autophagy assays (LC3 flux, ULK complex stability), picornavirus replication assays\",\n      \"journal\": \"Frontiers in cellular and infection microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus KO with defined molecular and functional phenotypes, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"34869056\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In fibroblasts stimulated by heat-inactivated S. aureus, HSBP1 is upregulated and mediates profibrotic effects (proliferation, expression of TGF-β1, VEGF, collagen I/III, α-SMA) and promotes autophagy (elevated LC3, Beclin-1, and autophagosomes); siRNA knockdown of HSBP1 reverses these effects and decreases autophagy.\",\n      \"method\": \"Proteomic analysis, siRNA knockdown, western blotting, immunofluorescence, transmission electron microscopy, flow cytometry\",\n      \"journal\": \"Wound repair and regeneration\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA knockdown with multiple molecular readouts and TEM confirmation of autophagy, single lab\",\n      \"pmids\": [\"39823159\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"HSBP1 is a small (76 aa) coiled-coil protein with multiple distinct molecular functions: in the nucleus it directly binds the heptad repeats of trimeric HSF1 to attenuate the heat shock transcriptional response (associating with Hsp70 during recovery); at centrosomes it acts as a trimeric scaffold that dissociates CCDC53 homotrimers to drive WASH complex assembly, thereby enabling Arp2/3-dependent endosomal actin branching, integrin recycling, focal adhesion formation, and cell polarity/migration; and in the cytoplasm it interacts with FIP200/ATG13 of the ULK complex to stabilize it and promote autophagy initiation, with this same interaction serving to restrain HSBP1's pro-picornaviral activity.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"HSBP1 is a small coiled-coil protein that operates as a molecular hub across heat-shock attenuation, cytoskeletal remodeling, and autophagy [#0, #4, #5]. In the nucleus, it binds the heptad repeats of the active trimeric form of HSF1 through its own hydrophobic heptad repeats, suppressing HSF1 DNA-binding and transactivation activity and associating with Hsp70 during attenuation of the heat-shock response [#0]; loss of HSBP1 in mouse embryoid bodies and zebrafish elevates HSF1 activity and Hsp expression and disrupts germ-layer organization, establishing this repressive role as essential for early embryonic development [#2]. As a trimeric coiled-coil scaffold at centrosomes, HSBP1 drives WASH complex assembly by dissociating the CCDC53 homotrimeric precursor to permit formation of the ternary CCDC53\\u2013WASH\\u2013FAM21 complex, thereby enabling endosomal recycling of \\u03b15\\u03b21 integrins, focal adhesion development, cell polarity, and migration/invasion via the WASH/Arp2/3 pathway [#4]. In the cytoplasm, HSBP1 binds the ULK kinase complex through FIP200 (with ATG13), stabilizing ULK complex subunits to promote autophagy initiation, and this FIP200\\u2013ATG13 interaction also restrains an HSBP1 pro-picornaviral activity [#5]. A pro-fibrotic, autophagy-promoting role for HSBP1 has also been documented in bacterially stimulated fibroblasts [#6].\",\n  \"teleology\": [\n    {\n      \"year\": 1998,\n      \"claim\": \"Established HSBP1's founding function: how the heat-shock transcriptional response is attenuated once HSF1 trimerizes, by identifying a dedicated repressor of the active trimeric state.\",\n      \"evidence\": \"Yeast two-hybrid, reciprocal co-immunoprecipitation, overexpression transactivation assays in mammalian cells, and heat-shock reporter assays in C. elegans\",\n      \"pmids\": [\"9649501\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Did not resolve the stoichiometry of the HSBP1\\u2013HSF1\\u2013Hsp70 attenuation complex\",\n        \"Mechanism by which Hsp70 association completes HSF1 inactivation not defined\"\n      ]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Placed HSBP1's HSF1-repressive activity in the correct compartment by demonstrating nuclear localization.\",\n      \"evidence\": \"Subcellular localization in mammalian cells\",\n      \"pmids\": [\"9649501\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Localization described by a single approach\",\n        \"Did not address the later-described centrosomal and cytoplasmic pools\"\n      ]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Tested whether HSBP1's HSF1 repression matters physiologically, showing it is required in vivo for early development and for keeping HSF1 activity in check.\",\n      \"evidence\": \"Knockout mice (embryoid body differentiation) and zebrafish morpholino knockdown with lineage-marker and Hsp readouts\",\n      \"pmids\": [\"24380799\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Did not separate developmental defects caused by HSF1 derepression from HSF1-independent functions\",\n        \"Tissue-specific requirements not dissected\"\n      ]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Revealed a function entirely distinct from transcriptional control: HSBP1 acts as a trimeric scaffold that chaperones WASH complex assembly, linking it to endosomal actin and integrin trafficking.\",\n      \"evidence\": \"Reciprocal Co-IP, pulldown, depletion/rescue in human cancer cells and Dictyostelium, centrosome imaging, focal adhesion/polarity and migration/invasion assays\",\n      \"pmids\": [\"29844016\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Structural basis for HSBP1-mediated CCDC53 homotrimer dissociation not resolved\",\n        \"How HSBP1 partitions between nuclear HSF1 and centrosomal WASH roles unknown\"\n      ]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Connected HSBP1 to autophagy initiation by identifying it as a ULK-complex-associated protein that stabilizes FIP200/ATG13, and linked the same interaction to control of a pro-picornaviral activity.\",\n      \"evidence\": \"Co-IP mapping to FIP200, siRNA/CRISPR knockout, LC3 flux and ULK subunit stability assays, picornavirus replication assays\",\n      \"pmids\": [\"34869056\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanism by which HSBP1 stabilizes ULK subunits not defined\",\n        \"Nature of HSBP1's pro-picornaviral activity and how FIP200\\u2013ATG13 restrains it unresolved\",\n        \"Single-lab study without reciprocal structural validation\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Extended HSBP1's autophagy role to a disease-relevant context, implicating it in fibroblast-driven fibrosis downstream of bacterial stimulation.\",\n      \"evidence\": \"Proteomics, siRNA knockdown, western blot, immunofluorescence, TEM, and flow cytometry in S. aureus-stimulated fibroblasts\",\n      \"pmids\": [\"39823159\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether profibrotic effects depend on the ULK/autophagy axis versus other HSBP1 functions not established\",\n        \"Direct molecular partners in this setting not identified\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How HSBP1 coordinates its three biochemically separable activities\\u2014HSF1 repression, WASH assembly, and ULK stabilization\\u2014within a single 76-residue coiled-coil remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No structural model integrating the heptad-repeat HSF1 interface with the trimeric scaffolding function\",\n        \"Regulatory signals partitioning HSBP1 between nucleus, centrosome, and cytoplasm unknown\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [0, 2]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [4]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 5]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0005815\", \"supporting_discovery_ids\": [4]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953897\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [5]},\n      {\"term_id\": \"R-HSA-9709957\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"complexes\": [\"WASH complex\", \"ULK kinase complex\"],\n    \"partners\": [\"HSF1\", \"HSPA1A\", \"CCDC53\", \"WASHC1\", \"FAM21\", \"RB1CC1\", \"ATG13\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}