{"gene":"HSF1","run_date":"2026-06-10T01:55:22","timeline":{"discoveries":[{"year":1991,"finding":"Human HSF1 was cloned and shown to encode a protein with four conserved leucine zipper motifs. HSF1 produced in E. coli in the absence of heat shock is active as a DNA-binding transcription factor, indicating that its intrinsic activity is under negative control in human cells.","method":"cDNA cloning, recombinant protein expression in E. coli, DNA-binding assay","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct in vitro reconstitution of DNA-binding activity from recombinant protein; foundational cloning paper replicated broadly","pmids":["1871105"],"is_preprint":false},{"year":1994,"finding":"HSF1 and HSF2 bind distinct DNA sequences (alternating inverted nGAAn pentamers). HSF1 exhibits higher cooperativity and can occupy extended HSE sequences, and the domain responsible for cooperative interactions maps within or adjacent to the HSF1 DNA-binding domain, as demonstrated by chimeric HSF1/HSF2 proteins.","method":"SELEX (protein binding + PCR amplification of random sequences), EMSA, chimeric protein mutagenesis","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro SELEX and EMSA with mutagenesis and chimeric proteins in a single focused study","pmids":["7935474"],"is_preprint":false},{"year":1998,"finding":"Hsp70 and its cochaperone Hdj1 directly interact with the transactivation domain of HSF1 and repress heat shock gene transcription. Overexpression of either chaperone represses endogenous HSF1 transcriptional activity without affecting HSF1 DNA binding or inducible phosphorylation, identifying chaperone binding to the transactivation domain as the primary autoregulatory mechanism during attenuation.","method":"Co-immunoprecipitation, GAL4-HSF1 transactivation domain fusion reporter assay, overexpression of Hsp70/Hdj1","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP plus functional reporter assay, widely replicated across labs","pmids":["9499401"],"is_preprint":false},{"year":2003,"finding":"The co-chaperone/ubiquitin ligase CHIP induces trimerization and transcriptional activation of HSF1, and CHIP-deficient mice are temperature-sensitive and undergo multi-organ apoptosis upon environmental challenge, establishing CHIP as a positive regulator of HSF1 at the level of trimerization.","method":"CHIP knockout mouse phenotyping, HSF1 trimerization assay, transcriptional activation assays, stress-induced apoptosis measurement","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with defined phenotype combined with biochemical trimerization assay in multiple systems","pmids":["14532117"],"is_preprint":false},{"year":2005,"finding":"HSF1 directly binds a heat shock element within the XAF1 gene promoter (-862/-821 region) and represses XAF1 transcription, establishing HSF1 as a transcriptional repressor of a pro-apoptotic gene.","method":"Luciferase reporter assay, EMSA, chromatin immunoprecipitation (ChIP), site-directed mutagenesis of HSE","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — ChIP, EMSA, reporter assay and mutagenesis in one study provide orthogonal evidence","pmids":["16303760"],"is_preprint":false},{"year":2006,"finding":"HSF1-mediated transcription directly drives expression of the pro-apoptotic gene Tdag51. Hsp proteins bind directly to the N-terminal pleckstrin-homology-like (PHL) domain of Tdag51 and suppress its death-promoting activity, defining an HSF1-dependent death pathway counterbalanced by its own chaperone targets.","method":"Direct target gene identification (Tdag51 as HSF1 target), direct binding assay of Hsps to Tdag51 PHL domain, Tdag51-null mouse testis analysis","journal":"The EMBO journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO with defined phenotype plus binding assay; single lab study","pmids":["17024176"],"is_preprint":false},{"year":2008,"finding":"In yeast, the Yak1 kinase directly phosphorylates Hsf1 in vitro, leading to increased Hsf1 DNA-binding activity. Yak1 is under negative control of PKA, placing Hsf1 in a PKA-Yak1-Hsf1 signaling axis that links nutrient sensing to the heat shock response.","method":"In vitro kinase assay, EMSA (DNA binding assay), genetic epistasis (PKA/Pde2 overexpression)","journal":"Molecular microbiology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct in vitro kinase assay plus genetic epistasis in a single study","pmids":["18793336"],"is_preprint":false},{"year":2011,"finding":"Loss of HSF1 results in failure to arrest in G2 after ionizing radiation, reduced repair of double-strand DNA breaks, and failure of 53BP1 to accumulate at DNA damage sites, establishing HSF1 as required for DNA damage checkpoint activation and DNA repair.","method":"HSF1 loss-of-function (functional HSF1-deficient cells), cell cycle analysis, γH2AX and 53BP1 foci immunofluorescence","journal":"Radiation research","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — clean loss-of-function with defined cellular phenotypes; single lab, single study","pmids":["21557666"],"is_preprint":false},{"year":2015,"finding":"MEK directly phosphorylates HSF1, making HSF1 a new MEK substrate beyond ERK. MEK blockade inactivates HSF1 and provokes protein aggregation and amyloidogenesis in tumor cells, identifying the RAS-MEK-HSF1 axis as a proteostasis guardian in cancer.","method":"In vitro kinase assay (MEK phosphorylation of HSF1), biochemical fractionation, protein aggregation assays, in vivo tumor growth models","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct in vitro kinase assay plus in vivo genetic and pharmacologic validation in multiple models","pmids":["25679764"],"is_preprint":false},{"year":2015,"finding":"NEDD4 is the E3 ubiquitin ligase responsible for HSF1 degradation via the ubiquitin-proteasome system under α-synuclein proteotoxic stress. Acetylation status of Lys80 in the HSF1 DNA-binding domain is a critical determinant of HSF1 protein stability; SIRT1-mediated deacetylation attenuates NEDD4-mediated HSF1 degradation.","method":"Ubiquitination assay, NEDD4 knockdown, site-directed mutagenesis of Lys80, SIRT1 pharmacological activation, in vivo mouse and human tissue validation","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — multiple orthogonal methods (ubiquitination assay, mutagenesis, knockdown, in vivo models) in one study","pmids":["26503960"],"is_preprint":false},{"year":2015,"finding":"IER5 interacts with PP2A and its B55 regulatory subunits; B55 directly binds HSF1 and promotes HSF1 dephosphorylation, leading to activation of HSF1 target genes. IER5 functions as a positive feedback regulator of HSF1 through the PP2A/B55 complex.","method":"Co-immunoprecipitation, HSF1 dephosphorylation assay, target gene expression assay","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — Co-IP plus functional gene expression assay; single lab, single study","pmids":["25816751"],"is_preprint":false},{"year":2017,"finding":"HSF1 forms a ternary complex with PARP13 and PARP1; HSF1 recruits PARP1 through the scaffold protein PARP13. HDAC1 maintains PARP1 in the complex by deacetylating and inactivating PARP1. Upon DNA damage, auto-PARylated PARP1 dissociates and redistributes to DNA lesions, and disruption of this complex impairs DNA repair and gene expression.","method":"Co-immunoprecipitation, ChIP, HDAC1 functional assay, DNA damage repair assays, BRCA1-null tumor model","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, ChIP, and functional rescue in multiple systems in one study","pmids":["29158484"],"is_preprint":false},{"year":2017,"finding":"HSF1 transcriptionally regulates nicotinamide phosphoribosyltransferase in the NAD+ salvage pathway; loss of HSF1 reduces NAD+ and ATP levels, impairs NAD+-dependent deacetylase activity, increases protein acetylation, and disrupts mitochondrial integrity in hepatic cells.","method":"HSF1 KO cells/mice, NAD+/ATP measurement, NAD+-dependent deacetylase activity assay, ChIP for HSF1 at NAMPT promoter, mitochondrial integrity assays","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (KO, metabolite measurements, ChIP) in one study","pmids":["28183717"],"is_preprint":false},{"year":2017,"finding":"HSF1 directly binds the ATG4B gene promoter (at the -1429 to -1417 region) and upregulates ATG4B transcription, thereby enhancing protective autophagy in hepatocellular carcinoma cells treated with epirubicin.","method":"Luciferase reporter assay, ChIP assay, shRNA knockdown, in vivo xenograft","journal":"Cancer letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP and reporter assay with functional in vivo validation; single lab","pmids":["28889000"],"is_preprint":false},{"year":2017,"finding":"HSF1 triggers SQSTM1/p62 phosphorylation at S349 and S403 in an HSF1-dependent manner via casein kinase 1, promoting inclusion formation and autophagosome-mediated clearance of protein aggregates.","method":"HSF1 inhibition, phospho-specific antibodies, autophagy flux assays, inclusion formation assay","journal":"Autophagy","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — functional pathway assays with HSF1 inhibition; single lab, limited mechanistic depth in abstract","pmids":["27846364"],"is_preprint":false},{"year":2017,"finding":"In beta cells, glucolipotoxicity promotes HSF1 acetylation via interaction with the acetyltransferase CBP, which inhibits HSF1 DNA-binding activity and decreases target gene expression. A K80Q acetylation-mimicking mutant of HSF1 fails to protect against glucolipotoxicity, establishing K80 acetylation as a negative regulatory PTM.","method":"Gel shift assay (EMSA), western blot for HSF1-CBP interaction, HSF1 K80Q acetylation-mimicking mutant, gene expression analysis","journal":"Diabetologia","confidence":"Medium","confidence_rationale":"Tier 1-2 / Weak — EMSA, interaction assay, and mutagenesis; single lab study","pmids":["28547133"],"is_preprint":false},{"year":2018,"finding":"Yak1 kinase (yeast) and its downstream regulation of Hsf1 was validated as a two-component negative feedback loop: Hsp70 binds Hsf1 at conserved element 2 (CE2) with low affinity (~9 µM in vitro), releasing Hsf1 when Hsp70 is titrated by misfolded proteins. Removal of CE2 increases basal Hsf1 activity and delays deactivation; tandem CE2 repeats accelerate deactivation. An N-terminal domain of Hsf1 negatively regulates DNA binding.","method":"In vitro Hsp70-CE2 binding assay (affinity measurement), CE2 deletion and repeat mutants in cells, mathematical modeling validated by genetic uncoupling of Hsp70 induction","journal":"eLife","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro binding reconstitution with affinity measurement, plus genetic validation with multiple mutants in cells","pmids":["29393852"],"is_preprint":false},{"year":2018,"finding":"AKT1 phosphorylates HSF1 at multiple sites: S326 (required for transactivation), T142 (required for trimerization), S230 and T527 (required for gene transactivation and recruitment of TFIIB and CDK9). AKT1 is the most potent activator of HSF1 among several kinases tested (mTOR, p38, MEK1, DYRK2) that all phosphorylate S326.","method":"Mass spectrometry (identification of phosphosites), site-directed mutagenesis of HSF1 phosphosites, in vitro kinase assays, HSF1 trimerization assay, reporter assay for transactivation, TFIIB/CDK9 recruitment assay","journal":"The FEBS journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — mass spectrometry, mutagenesis, in vitro kinase assays and functional assays in one study","pmids":["35080342"],"is_preprint":false},{"year":2019,"finding":"PIM2 kinase phosphorylates HSF1 at Thr120, which disrupts HSF1 binding to the E3 ubiquitin ligase FBXW7, thereby stabilizing HSF1 protein. HSF1 pThr120 also promotes HSF1 binding to the PD-L1 promoter and enhances PD-L1 expression.","method":"In vitro kinase assay, Co-IP of HSF1 with FBXW7, HSF1 T120A mutant analysis, ChIP at PD-L1 promoter, in vivo xenograft","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — in vitro kinase assay, co-IP, mutagenesis, and ChIP in one study","pmids":["31409638"],"is_preprint":false},{"year":2019,"finding":"In budding yeast, Hsp70 inhibits Hsf1 DNA-binding activity through its canonical substrate-binding domain. During heat shock, cytoplasmic misfolded proteins derived from ongoing translation titrate Hsp70 away from Hsf1, releasing Hsf1 to activate the heat shock response. Blocking protein synthesis before stress prevents Hsf1 activation.","method":"In vitro reconstitution of Hsf1-Hsp70 complexes, EMSA, misfolded protein titration assay, genetic analysis of translation inhibition","journal":"eLife","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with EMSA plus genetic validation; mechanistically detailed","pmids":["31552827"],"is_preprint":false},{"year":2019,"finding":"HSF1 interacts with the pericentromeric protein shugoshin 2 (SGO2) during heat shock in a manner dependent on inducible phosphorylation of HSF1 at serine 326. SGO2 binds RNA Pol II with a hypophosphorylated C-terminal domain and is recruited to HSP70 promoter, where it facilitates Pol II recruitment and HSP70 expression.","method":"Co-IP of HSF1 and SGO2, phospho-S326 dependency assay, ChIP at HSP70 promoter, comparative analysis of HSF1 paralogs and mutants","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, ChIP, mutagenesis, and functional gene expression assays in one study","pmids":["31657478"],"is_preprint":false},{"year":2020,"finding":"AKT activates HSF1 via Ser230 phosphorylation. HSF1 physically neutralizes soluble amyloid oligomers (AOs) and shields HSP60 from direct assault by AOs, preventing HSP60 destabilization, mitochondrial proteome collapse, and apoptosis. This mechanism also operates in Alzheimer's disease models.","method":"In vitro AO-HSF1 binding assay, Hsf1-deficient mouse model with PI3K/AKT hyperactivation, phospho-site mutagenesis (S230A), mitochondrial integrity assays","journal":"Science advances","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct binding assay for HSF1-amyloid oligomers plus genetic and pharmacologic in vivo evidence; single lab","pmids":["33177089"],"is_preprint":false},{"year":2020,"finding":"HSF1 foci (nuclear stress bodies) form as small, fluid condensates that enlarge into gel-like indissoluble arrangements under prolonged stress. Foci dissolution (not formation) promotes HSF1 transcriptional activity and cell survival; cells with gel-like HSF1 foci show reduced chaperone gene induction and increased apoptosis, identifying phase transition of HSF1 as a cell-fate determinant.","method":"Live-cell microscopy (single-cell), FRAP, multiplexed tissue imaging, quantitative single-cell analysis","journal":"Nature cell biology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal imaging methods (FRAP, live-cell microscopy, tissue imaging) with functional single-cell readouts in one study","pmids":["32015439"],"is_preprint":false},{"year":2021,"finding":"HSF1 activation by proteotoxic stress requires concurrent protein synthesis; inhibiting translation before stress prevents Hsf1 activation across diverse stresses. Newly synthesized proteins are especially susceptible to proteotoxic conditions, and disruption of their assembly or localization is sufficient to activate Hsf1.","method":"Pharmacological translation inhibition (cycloheximide and others), ethanol-induced stress, nascent protein localization disruption assays in S. cerevisiae","journal":"Molecular biology of the cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — systematic genetic and pharmacologic dissection across multiple stresses; single lab","pmids":["34191586"],"is_preprint":false},{"year":2022,"finding":"HSF1 forms small nuclear condensates via liquid-liquid phase separation (LLPS) at HSP gene loci during heat shock, enriching transcription machinery through co-phase separation. HSP70 disperses HSF1 condensates to attenuate transcription after heat shock and prevents gel-like phase transition under extended stress. Phosphorylation at specific sites in the regulatory domain fine-tunes HSF1 phase-separation capacity.","method":"Super-resolution imaging, in vitro reconstitution of LLPS, high-throughput sequencing, phosphosite mutational analysis","journal":"Nature cell biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution of LLPS, super-resolution imaging, and sequencing with multiple orthogonal methods in one rigorous study","pmids":["35256776"],"is_preprint":false},{"year":2022,"finding":"HSF2 physically and functionally interacts with HSF1 across diverse cancer types; the two factors share notably similar chromatin occupancy and regulate a common set of genes including HSPs and non-canonical cancer targets. Loss of either HSF1 or HSF2 dysregulates the response to nutrient stress and reduces tumor progression, establishing HSF2 as a critical HSF1 cofactor in cancer.","method":"Co-immunoprecipitation of HSF1-HSF2, ChIP-seq (occupancy comparison), genetic knockdown of HSF1/HSF2, xenograft tumor models","journal":"Science advances","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, ChIP-seq, genetic KD, and in vivo validation in one study","pmids":["35294249"],"is_preprint":false},{"year":2022,"finding":"HSF1 phosphorylation at S419 by PLK1 recruits the TRRAP-TIP60 acetyltransferase complex to the HSP72 promoter. TIP60-mediated acetylation then recruits TRIM33 (a bromodomain-containing ubiquitin ligase), which cooperates with TRIM24 for mono-ubiquitination of histone H2B at K120, establishing an active chromatin state at HSP gene promoters.","method":"ChIP, Co-IP, PLK1 kinase assay, mutagenesis of HSF1-S419, histone modification analysis, melanoma cell proliferation assay","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — ChIP, Co-IP, kinase assay, and mutagenesis with histone modification readouts in one study","pmids":["35906200"],"is_preprint":false},{"year":2022,"finding":"Mitochondria-localizing HSF1 (mtHSF1) accumulates in Huntington's disease models and drives mitochondrial fission by activating Drp1 phosphorylation at S616 and suppresses SSBP1 oligomer formation, causing mitochondrial DNA deletion. A peptide inhibitor (DH1) blocking HSF1 mitochondrial localization ameliorates HD phenotypes.","method":"Subcellular fractionation, overexpression of mitochondria-targeting HSF1, Drp1-S616 phosphorylation assay, SSBP1 oligomerization assay, mtDNA deletion analysis, HD mouse model and human striatal organoids","journal":"EMBO molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple mechanistic assays in multiple models; single lab study","pmids":["35670111"],"is_preprint":false},{"year":2020,"finding":"In cardiomyocytes, HSF1 deficiency reduces GPX4 protein expression and disrupts iron homeostasis by transcriptionally regulating iron metabolism genes (Fth1, Tfrc, Slc40a1). HSF1 overexpression restores GPX4 expression by inhibiting ER stress (not autophagy), and Hsf1−/− mice show exacerbated ferroptosis with enhanced ER stress upon palmitic acid challenge.","method":"HSF1 overexpression/knockdown, Hsf1−/− mouse model, iron metabolism gene expression analysis (qPCR), ER stress inhibitor experiments, GPX4 western blot","journal":"Journal of molecular and cellular cardiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO mouse model plus mechanistic dissection of ER stress pathway; single lab","pmids":["33098823"],"is_preprint":false},{"year":2014,"finding":"HSF1-mediated neuroprotection does not require HSF1 trimerization (normally obligatory for HSP gene promoter binding). Protection is also independent of HSP70/HSP90 but requires classical HDACs and involves cooperation with SIRT1, defining a noncanonical, trimerization-independent neuroprotective mechanism.","method":"HSF1 trimerization-deficient mutants, HSP70 knockdown, HDAC inhibitor treatment, SIRT1 genetic/pharmacologic manipulation, cell culture models of Huntington's disease","journal":"The Journal of neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple mutants and pharmacologic tools in one study; single lab","pmids":["24478344"],"is_preprint":false},{"year":2016,"finding":"In Candida albicans, Hsp90 regulates Hsf1 activation both under basal conditions and during heat shock but with opposing effects; these effects are controlled in part at the level of Hsf1 expression and DNA binding. Hsp90 also modulates global transcription programs by regulating nucleosome levels at promoters of stress-responsive genes.","method":"RNA-seq, ChIP-seq (Hsf1 occupancy), Hsp90 inhibitor treatment, nucleosome occupancy assay","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genome-wide ChIP-seq and RNA-seq with functional pharmacological perturbation; ortholog study in C. albicans","pmids":["27226156"],"is_preprint":false},{"year":2014,"finding":"In budding yeast, Hsf1 is incapable of binding HSEs within a stably positioned, reconstituted nucleosome, but accesses nucleosomal sites during heat shock in concert with the RSC chromatin remodeling complex, which promotes chromatin disassembly.","method":"ChIP-seq (Hsf1 binding), nascent RNA-seq, Hsf1 nuclear depletion, in vitro nucleosome binding assay","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — in vitro nucleosome binding assay plus genome-wide ChIP-seq and nascent RNA-seq with genetic depletion","pmids":["30332327"],"is_preprint":false},{"year":2017,"finding":"ABL2 tyrosine kinase directly interacts with HSF1 protein via its SH3 domain at a noncanonical, proline-independent SH3 interaction motif, regulating HSF1 protein expression. Allosteric (but not ATP-competitive) ABL2 inhibition disrupts this interaction and impairs HSF1-driven E2F transcriptional targets required for brain metastasis outgrowth.","method":"Co-IP of ABL2 SH3 domain with HSF1, allosteric vs ATP-competitive inhibitor comparison, HSF1 knockdown, brain metastasis in vivo model","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct Co-IP plus pharmacologic discrimination of inhibitor mechanisms; single lab","pmids":["33318173"],"is_preprint":false},{"year":2016,"finding":"HSF1 Ser326 phosphorylation generates cell-to-cell variation in Hsp90 levels, and this variation (rather than average Hsf1 activity) promotes phenotypic plasticity and antifungal drug resistance in budding yeast. Hsp90 is required for enrichment of drug-resistant cells with high Hsf1 activity.","method":"Single-cell fluorescence microscopy, HSF1 phospho-mutant analysis (S326A), genetic Hsp90 manipulation, antifungal resistance assay","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — phospho-mutant analysis and single-cell imaging with functional phenotypic readout; single lab","pmids":["29562166"],"is_preprint":false},{"year":2015,"finding":"In CLL, HSF1 maintains a cytosolic complex with p97, HSP90, and HDAC6; HSF1 inhibition disrupts this complex, causing HSP90 acetylation and abrogating HSP90 chaperone function, leading to loss of HSP90 kinase clients (BTK, c-RAF, CDK4) and depletion of CDC37-HSP90 association.","method":"Co-IP of HSF1-p97-HSP90-HDAC6 complex, HSF1 knockdown/triptolide inhibition, HSP90 acetylation assay, client kinase depletion, in vivo Mec-1 leukemia model","journal":"Oncotarget","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP of multi-protein complex plus functional client depletion and in vivo validation; single lab","pmids":["26397138"],"is_preprint":false},{"year":2017,"finding":"FAM3C overexpression increases HSF1 expression in hepatocytes; HSF1 in turn elevates calmodulin (CaM) protein by inducing CALM1 transcription, which activates Akt in a Ca2+- and insulin-independent manner, defining a FAM3C-HSF1-CaM-Akt pathway controlling hepatic gluconeogenesis and lipid metabolism.","method":"HSF1 overexpression, CALM1 promoter-driven reporter assay, Akt activation assay, gluconeogenesis gene expression in vivo and in vitro, CaM-dependent rescue experiments","journal":"Diabetes","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — promoter reporter, genetic overexpression with functional metabolic readouts and in vivo validation; single lab","pmids":["28246289"],"is_preprint":false},{"year":2022,"finding":"HSF1 directly binds BDNF gene (Bdnf) promoters (promoters I and IV) in the hippocampus in vivo after kainic acid or footshock, and HSF1 overexpression increases BDNF mRNA and protein in primary neurons. HSF1 binding sites co-immunoprecipitate with pCREB at Bdnf promoters, suggesting functional cooperation.","method":"ChIP-qPCR in mouse hippocampus, luciferase reporter assay, viral HSF1 overexpression in neurons, immunohistochemistry","journal":"Journal of neurochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo ChIP-qPCR plus reporter and overexpression assays; single lab","pmids":["36227087"],"is_preprint":false},{"year":2014,"finding":"AMPKα (when dephosphorylated by PP2A/B56δ) phosphorylates HSF1 at Ser303, leading to transcriptional suppression of HSP70 and HSP27 under metal stress. PP2A B56δ physically interacts with AMPKα, establishing a PP2A-AMPKα-HSF1 signaling axis that regulates HSP expression.","method":"In vitro phosphorylation assay (AMPKα phosphorylation of HSF1 at S303), Co-IP of PP2A B56δ with AMPKα, siRNA knockdown, HSP expression analysis","journal":"Cellular signalling","confidence":"Medium","confidence_rationale":"Tier 1-2 / Weak — in vitro kinase assay and Co-IP; single lab, limited mechanistic detail in abstract","pmids":["24412756"],"is_preprint":false},{"year":2017,"finding":"HSF1 directly binds the HMGB1 promoter and negatively regulates HMGB1 transcription; HSF1 knockdown aggravates OVA-induced airway inflammation and hyperreactivity by promoting HMGB1 expression and activating the TLR4/MyD88/NF-κB pathway.","method":"ChIP assay, luciferase reporter assay, HSF1 knockdown in OVA asthma mouse model, ELISA for inflammatory markers","journal":"Life sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — ChIP and reporter assay plus in vivo KD; single lab","pmids":["31825792"],"is_preprint":false},{"year":2022,"finding":"Hsf1 directly binds the promoter of PPARγ coactivator-1α (PGC-1α) when phosphorylated at Ser326 and translocated to the nucleus, inducing mitochondrial biogenesis and oxidative metabolism in hepatocytes. HSF1 and PGC-1α deletion experiments confirmed the HSF1/PGC-1α pathway is independent of AMPK.","method":"ChIP-seq (HSF1 binding to PGC-1α promoter), phospho-HSF1 (S326) nuclear translocation assay, HSF1-deficiency rescue experiments, mitochondrial biogenesis assay","journal":"British journal of pharmacology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP-seq with genetic rescue experiments; single lab","pmids":["34783017"],"is_preprint":false},{"year":2021,"finding":"HSF1 is the prime transcription factor for ATG5 and ATG12 in melanocytes; HSF1 deficiency reduces ATG5 and ATG12 expression, leading to accumulation of intracellular ROS, mitochondrial membrane potential imbalance, and apoptosis under oxidative stress. HSF1 overexpression activates protective autophagy via ATG5/ATG12 upregulation.","method":"RNA-sequencing, HSF1 KD/overexpression, autophagy flux assay, ROS measurement, mitochondrial membrane potential assay","journal":"The Journal of investigative dermatology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — transcriptomics plus functional autophagy and cell death assays; single lab","pmids":["34780715"],"is_preprint":false},{"year":2016,"finding":"CHIP (C-terminus of Hsp70-interacting protein) mediates HSF1 stability and nuclear translocation through direct interaction via its tetratricopeptide repeat (TPR) domain. Doxorubicin diminishes the CHIP-HSF1 interaction and triggers proteasomal HSF1 degradation, relieving HSF1 repression of IGF-IIR expression and promoting cardiomyocyte apoptosis.","method":"Co-IP of CHIP and HSF1, domain-mapping (TPR domain), proteasome inhibitor experiments, IGF-IIR expression assay, CHIP overexpression rescue, in vitro and in vivo cardiac models","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — domain-specific Co-IP with functional rescue assays; single lab","pmids":["27809308"],"is_preprint":false},{"year":2019,"finding":"HSF1 directly binds the miR-214-3p promoter to increase its expression; miR-214-3p in turn targets and suppresses NFATc2 transcription. This HSF1-miR-214-3p-NFATc2 axis inhibits microglia activation and neuroinflammation in a Parkinson's disease mouse model.","method":"ChIP assay (HSF1 at miR-214-3p promoter), dual-luciferase assay (miR-214-3p target NFATc2), functional rescue in MPTP mouse model","journal":"Folia neuropathologica","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — ChIP and dual-luciferase plus in vivo rescue; single lab study with limited mechanistic depth in abstract","pmids":["37114961"],"is_preprint":false}],"current_model":"HSF1 is a stress-activated transcription factor that exists as a negatively regulated monomer in unstressed cells (held latent by Hsp90 and Hsp70 binding to its regulatory and transactivation domains); proteotoxic stress titrates Hsp70 away via misfolded proteins, releasing HSF1 to trimerize, translocate to the nucleus, and bind heat shock elements (HSEs) to drive chaperone gene expression through liquid-liquid phase separation condensates at target loci—a response attenuated by Hsp70 rebinding to the transactivation domain, HSP70-mediated condensate dispersal, and post-translational modifications including phosphorylation (at S326 by AKT1/mTOR/MEK/p38/PLK1, at T142 required for trimerization, at S419 required for TRRAP-TIP60 chromatin remodeling, and inhibitory phosphorylation at S303 by AMPKα), acetylation at K80 (by CBP, inhibitory; reversed by SIRT1), sumoylation, and ubiquitin-mediated degradation (by NEDD4 and FBXW7); beyond canonical HSP gene regulation, HSF1 represses pro-apoptotic targets (XAF1, HMGB1), activates non-canonical targets (ATG4B, ATG5/12, PD-L1, CALM1/CaM, Tdag51, BDNF, PGC-1α), forms a ternary complex with PARP13-PARP1 to regulate DNA repair, cooperates with HSF2 to drive a cancer-specific transcriptional program, and physically neutralizes amyloid oligomers to suppress proteotoxic amyloidogenesis."},"narrative":{"mechanistic_narrative":"HSF1 is the master stress-activated transcription factor of the heat shock response, driving chaperone gene expression while existing under negative control in unstressed cells [PMID:1871105, PMID:31552827]. Its intrinsic DNA-binding and transactivation activities are intrinsically active but held latent: Hsp70 binds the HSF1 transactivation domain (and, via a low-affinity conserved element CE2, the regulatory region) to repress transcription, and proteotoxic stress titrates Hsp70 away through misfolded proteins arising from ongoing translation, releasing HSF1 to trimerize and bind heat shock elements (HSEs) of inverted nGAAn pentamers [PMID:7935474, PMID:9499401, PMID:29393852, PMID:31552827, PMID:34191586]. Activation is positively driven by the co-chaperone/ubiquitin ligase CHIP, which promotes trimerization, and by IER5-PP2A/B55-mediated dephosphorylation [PMID:14532117, PMID:25816751, PMID:28547133]. Promoter engagement requires chromatin remodeling—HSF1 cannot access nucleosomal HSEs without the RSC complex, and PLK1 phosphorylation at S419 recruits the TRRAP-TIP60 acetyltransferase complex to establish active chromatin at HSP loci [PMID:35906200, PMID:30332327]. At target genes HSF1 nucleates liquid-liquid phase-separated condensates (nuclear stress bodies) that concentrate transcription machinery; HSP70 disperses these condensates to attenuate transcription, and a fluid-to-gel phase transition under prolonged stress switches the response from survival to apoptosis [PMID:32015439, PMID:35256776]. HSF1 activity is extensively tuned by phosphorylation, including activating sites S326 (by AKT1, mTOR, MEK, p38), T142 (trimerization), and S230, and inhibitory S303 by AMPKα, alongside acetylation at K80 by CBP (inhibitory, reversed by SIRT1) and degradation through NEDD4 and FBXW7, the latter blocked by PIM2 phosphorylation at T120 [PMID:25679764, PMID:26503960, PMID:28547133, PMID:35080342, PMID:31409638, PMID:24412756]. Beyond canonical chaperone induction, HSF1 represses pro-apoptotic targets (XAF1, HMGB1), activates autophagy genes (ATG4B, ATG5/12) and metabolic genes (NAMPT, PGC-1α, CALM1), forms a ternary complex with PARP13 and PARP1 to support DNA repair, cooperates with HSF2 to drive a cancer-specific transcriptional program, and physically neutralizes amyloid oligomers to suppress proteotoxicity [PMID:16303760, PMID:29158484, PMID:28183717, PMID:33177089, PMID:35294249, PMID:31825792, PMID:34783017, PMID:34780715].","teleology":[{"year":1991,"claim":"Establishing whether HSF1's activity is intrinsic or stress-gated: recombinant HSF1 from bacteria was DNA-binding competent without heat shock, showing the protein is intrinsically active and held under negative control in human cells.","evidence":"cDNA cloning and recombinant expression in E. coli with DNA-binding assay","pmids":["1871105"],"confidence":"High","gaps":["Did not identify the repressing factor","No structure of the DNA-binding or trimerization domains"]},{"year":1994,"claim":"Defining the DNA target: SELEX and chimeric proteins showed HSF1 recognizes inverted nGAAn pentamer HSEs with high cooperativity mapping to its DNA-binding domain, distinguishing it from HSF2.","evidence":"SELEX, EMSA, and chimeric HSF1/HSF2 mutagenesis in vitro","pmids":["7935474"],"confidence":"High","gaps":["Did not address in vivo nucleosomal access","Cooperativity mechanism at the molecular level unresolved"]},{"year":1998,"claim":"Identifying the autoregulatory brake: Hsp70/Hdj1 binding to the HSF1 transactivation domain represses transcription without altering DNA binding, defining chaperone titration as the core attenuation mechanism.","evidence":"Co-IP and GAL4-transactivation domain reporter with chaperone overexpression","pmids":["9499401"],"confidence":"High","gaps":["Quantitative affinity and stoichiometry not measured here","Did not address regulatory-domain Hsp70 binding"]},{"year":2003,"claim":"Identifying a positive regulator of activation: CHIP promotes HSF1 trimerization and transcription, and its loss causes stress-induced multi-organ apoptosis in mice.","evidence":"CHIP knockout mouse phenotyping with trimerization and transcription assays","pmids":["14532117"],"confidence":"High","gaps":["Direct biochemical step CHIP acts on during trimerization not fully resolved"]},{"year":2005,"claim":"Extending HSF1 beyond gene activation: HSF1 binds an HSE in the XAF1 promoter and represses this pro-apoptotic gene, establishing it as a direct transcriptional repressor.","evidence":"ChIP, EMSA, reporter assay, and HSE mutagenesis","pmids":["16303760"],"confidence":"High","gaps":["Co-repressor machinery for HSF1-mediated repression not identified"]},{"year":2008,"claim":"Linking nutrient signaling to the heat shock response: yeast Yak1 directly phosphorylates Hsf1 to increase DNA binding, under PKA negative control.","evidence":"In vitro kinase assay, EMSA, and genetic epistasis in yeast","pmids":["18793336"],"confidence":"High","gaps":["Phosphosites not mapped","Human ortholog of this axis not addressed"]},{"year":2011,"claim":"Connecting HSF1 to genome stability: HSF1 loss impairs the G2/IR checkpoint, double-strand break repair, and 53BP1 focus formation.","evidence":"HSF1-deficient cells with cell-cycle analysis and γH2AX/53BP1 immunofluorescence","pmids":["21557666"],"confidence":"Medium","gaps":["Single lab, single study","Direct molecular link to repair machinery not established here"]},{"year":2014,"claim":"Defining a trimerization-independent role: HSF1 neuroprotection in Huntington's models requires HDACs and SIRT1 cooperation but not trimerization or HSP70/90, revealing a noncanonical function.","evidence":"Trimerization-deficient mutants, HDAC inhibitors, and SIRT1 manipulation in HD cell models","pmids":["24478344"],"confidence":"Medium","gaps":["Direct target genes of this noncanonical mode unknown","Single lab"]},{"year":2014,"claim":"Establishing inhibitory phosphorylation: AMPKα phosphorylates HSF1 at S303 to suppress HSP70/HSP27 under metal stress, via a PP2A-AMPKα axis.","evidence":"In vitro kinase assay and Co-IP with HSP expression analysis","pmids":["24412756"],"confidence":"Medium","gaps":["Limited mechanistic detail","Single lab"]},{"year":2015,"claim":"Identifying degradation control: NEDD4 ubiquitinates HSF1 under α-synuclein stress, gated by K80 acetylation, which SIRT1 deacetylation reverses to stabilize HSF1.","evidence":"Ubiquitination assay, K80 mutagenesis, NEDD4 knockdown, and in vivo models","pmids":["26503960"],"confidence":"High","gaps":["Acetyltransferase for K80 not identified here","Interplay with other E3 ligases unresolved"]},{"year":2015,"claim":"Expanding the kinase repertoire: MEK directly phosphorylates HSF1, and the RAS-MEK-HSF1 axis guards proteostasis in tumors.","evidence":"In vitro kinase assay with protein aggregation and tumor models","pmids":["25679764"],"confidence":"High","gaps":["Phosphosite consequences for trimerization vs transactivation not fully separated here"]},{"year":2015,"claim":"Identifying an activating dephosphorylation circuit: IER5 recruits PP2A/B55 to dephosphorylate HSF1 and activate target genes as positive feedback.","evidence":"Co-IP, dephosphorylation assay, and target gene expression","pmids":["25816751"],"confidence":"Medium","gaps":["Specific sites dephosphorylated not defined","Single lab"]},{"year":2015,"claim":"Placing HSF1 in a cytosolic chaperone scaffold: in CLL, HSF1 maintains a p97-HSP90-HDAC6 complex whose disruption acetylates HSP90 and depletes its kinase clients.","evidence":"Co-IP of multi-protein complex with client depletion and in vivo leukemia model","pmids":["26397138"],"confidence":"Medium","gaps":["Cytosolic non-transcriptional role mechanistically distinct from nuclear function unclear","Single lab"]},{"year":2016,"claim":"Showing cell-to-cell HSF1 variation drives phenotypic outcomes: S326-dependent Hsf1 activity variation sets Hsp90 levels and antifungal drug resistance.","evidence":"Single-cell imaging with S326A mutant and Hsp90 manipulation in yeast","pmids":["29562166"],"confidence":"Medium","gaps":["Mechanism generating cell-to-cell variation unresolved","Yeast system"]},{"year":2017,"claim":"Linking HSF1 to a multi-protein DNA-repair complex: HSF1 scaffolds a ternary complex with PARP13 and PARP1, releasing auto-PARylated PARP1 to DNA lesions upon damage.","evidence":"Reciprocal Co-IP, ChIP, HDAC1 assays, and DNA repair models","pmids":["29158484"],"confidence":"High","gaps":["Structural basis of the ternary complex unknown","How damage signal triggers PARP1 release not detailed"]},{"year":2017,"claim":"Connecting HSF1 to NAD+ metabolism: HSF1 transcriptionally drives NAMPT, and its loss lowers NAD+/ATP, raises protein acetylation, and disrupts mitochondria.","evidence":"HSF1 KO cells/mice with metabolite measurement and NAMPT ChIP","pmids":["28183717"],"confidence":"High","gaps":["Tissue-specificity of the NAMPT axis not fully mapped"]},{"year":2017,"claim":"Defining non-canonical autophagy and metabolic targets: HSF1 directly activates ATG4B, induces CKI-dependent SQSTM1/p62 phosphorylation, and drives a FAM3C-HSF1-CaM-Akt metabolic pathway.","evidence":"ChIP, reporter assays, phospho-specific readouts, and metabolic assays across cell and mouse models","pmids":["28889000","27846364","28246289"],"confidence":"Medium","gaps":["Each pathway from a single study","Whether these are conserved across tissues unknown"]},{"year":2018,"claim":"Resolving the chaperone-titration mechanism biochemically: Hsp70 binds Hsf1 at a low-affinity CE2 element, and CE2 dosage tunes the timing of activation and deactivation.","evidence":"In vitro affinity measurement plus CE2 deletion/repeat mutants and modeling in yeast","pmids":["29393852"],"confidence":"High","gaps":["Human equivalent of CE2 dynamics not quantified","Role of transactivation-domain Hsp70 binding integrated only partially"]},{"year":2019,"claim":"Establishing the proteostatic sensing logic: cytoplasmic misfolded nascent proteins titrate Hsp70 from Hsf1 via its substrate-binding domain, and translation is required to generate the activating signal.","evidence":"In vitro reconstitution, EMSA, and translation-inhibition genetics in yeast","pmids":["31552827"],"confidence":"High","gaps":["Quantitative threshold of misfolded protein needed to activate not defined","Human in-cell confirmation pending"]},{"year":2019,"claim":"Mapping the activating phospho-code and a transcriptional cofactor: PIM2 phosphorylates T120 to block FBXW7 and drive PD-L1, while phospho-S326-dependent SGO2 recruitment facilitates Pol II loading at HSP70.","evidence":"Kinase assays, Co-IP, ChIP, and mutagenesis with xenograft models","pmids":["31409638","31657478"],"confidence":"High","gaps":["How S326 phosphorylation triggers SGO2 binding structurally unknown"]},{"year":2020,"claim":"Establishing phase separation as a cell-fate switch: HSF1 nuclear stress bodies form as fluid condensates whose dissolution promotes transcription and survival, while gel transition triggers apoptosis.","evidence":"FRAP, live-cell and multiplexed tissue imaging with single-cell readouts","pmids":["32015439"],"confidence":"High","gaps":["Molecular determinants of the fluid-to-gel transition not fully defined here"]},{"year":2020,"claim":"Revealing direct cytoprotective binding: AKT-S230-activated HSF1 physically neutralizes amyloid oligomers and shields HSP60 from mitochondrial collapse.","evidence":"In vitro AO-binding assay with Hsf1-deficient and S230A mutant models","pmids":["33177089"],"confidence":"Medium","gaps":["Structural basis of HSF1-oligomer interaction unknown","Single lab"]},{"year":2022,"claim":"Reconstituting HSF1 condensates and their dispersal: HSF1 undergoes LLPS at HSP loci to enrich transcription machinery, with HSP70 dispersing condensates and phosphorylation tuning phase-separation capacity.","evidence":"Super-resolution imaging, in vitro LLPS reconstitution, sequencing, and phosphosite analysis","pmids":["35256776"],"confidence":"High","gaps":["Which intrinsically disordered regions drive LLPS not fully mapped"]},{"year":2022,"claim":"Defining the cancer-specific cofactor and chromatin-remodeling step: HSF2 co-occupies chromatin with HSF1 to regulate shared targets, and PLK1-S419 phosphorylation recruits TRRAP-TIP60 to establish active chromatin at HSP promoters.","evidence":"Co-IP, ChIP-seq, kinase assay, and histone-modification analysis with tumor models","pmids":["35294249","35906200"],"confidence":"High","gaps":["How HSF1/HSF2 selectivity for cancer-specific loci is encoded unresolved"]},{"year":null,"claim":"How the layered regulatory inputs—chaperone titration, the multi-site phospho-code, acetylation, ubiquitination, and phase behavior—are integrated to produce locus- and tissue-specific HSF1 outputs (canonical HSP induction vs. non-canonical metabolic, apoptotic, and DNA-repair programs) remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified model linking phospho-state to condensate behavior and target selection","Tissue-specific target choice mechanism unknown","Structural basis of trimerization and DNA-binding regulation in human HSF1 not determined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[0,4,11,25,36,38,39,40]},{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[0,1,4,31]},{"term_id":"GO:0140313","term_label":"molecular sequestering activity","supporting_discovery_ids":[21]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[20,22,24,39]},{"term_id":"GO:0005654","term_label":"nucleoplasm","supporting_discovery_ids":[22,24]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[34]},{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[27]}],"pathway":[{"term_id":"R-HSA-8953897","term_label":"Cellular responses to stimuli","supporting_discovery_ids":[2,16,19,23]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[0,4,25,26]},{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[7,11]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[13,14,40]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[2,9,18]}],"complexes":["HSF1-PARP13-PARP1 ternary complex","HSF1-p97-HSP90-HDAC6 cytosolic complex","HSF1-HSF2 heterocomplex"],"partners":["HSP70","HSF2","PARP1","PARP13","CHIP","HSP90","AKT1","FBXW7"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q00613","full_name":"Heat shock factor protein 1","aliases":["Heat shock transcription factor 1","HSTF 1"],"length_aa":529,"mass_kda":57.3,"function":"Functions as a stress-inducible and DNA-binding transcription factor that plays a central role in the transcriptional activation of the heat shock response (HSR), leading to the expression of a large class of molecular chaperones, heat shock proteins (HSPs), that protect cells from cellular insult damage (PubMed:11447121, PubMed:12659875, PubMed:12917326, PubMed:15016915, PubMed:18451878, PubMed:1871105, PubMed:1986252, PubMed:25963659, PubMed:26754925, PubMed:7623826, PubMed:7760831, PubMed:8940068, PubMed:8946918, PubMed:9121459, PubMed:9341107, PubMed:9499401, PubMed:9535852, PubMed:9727490). In unstressed cells, is present in a HSP90-containing multichaperone complex that maintains it in a non-DNA-binding inactivated monomeric form (PubMed:11583998, PubMed:16278218, PubMed:9727490). Upon exposure to heat and other stress stimuli, undergoes homotrimerization and activates HSP gene transcription through binding to site-specific heat shock elements (HSEs) present in the promoter regions of HSP genes (PubMed:10359787, PubMed:11583998, PubMed:12659875, PubMed:16278218, PubMed:1871105, PubMed:1986252, PubMed:25963659, PubMed:26754925, PubMed:7623826, PubMed:7935471, PubMed:8455624, PubMed:8940068, PubMed:9499401, PubMed:9727490). Upon heat shock stress, forms a chromatin-associated complex with TTC5/STRAP and p300/EP300 to stimulate HSR transcription, therefore increasing cell survival (PubMed:18451878). Activation is reversible, and during the attenuation and recovery phase period of the HSR, returns to its unactivated form (PubMed:11583998, PubMed:16278218). Binds to inverted 5'-NGAAN-3' pentamer DNA sequences (PubMed:1986252, PubMed:26727489). Binds to chromatin at heat shock gene promoters (PubMed:25963659). Activates transcription of transcription factor FOXR1 which in turn activates transcription of the heat shock chaperones HSPA1A and HSPA6 and the antioxidant NADPH-dependent reductase DHRS2 (PubMed:34723967). Also serves several other functions independently of its transcriptional activity. Involved in the repression of Ras-induced transcriptional activation of the c-fos gene in heat-stressed cells (PubMed:9341107). Positively regulates pre-mRNA 3'-end processing and polyadenylation of HSP70 mRNA upon heat-stressed cells in a symplekin (SYMPK)-dependent manner (PubMed:14707147). Plays a role in nuclear export of stress-induced HSP70 mRNA (PubMed:17897941). Plays a role in the regulation of mitotic progression (PubMed:18794143). Also plays a role as a negative regulator of non-homologous end joining (NHEJ) repair activity in a DNA damage-dependent manner (PubMed:26359349). Involved in stress-induced cancer cell proliferation in a IER5-dependent manner (PubMed:26754925) (Microbial infection) Plays a role in latent human immunodeficiency virus (HIV-1) transcriptional reactivation. Binds to the HIV-1 long terminal repeat promoter (LTR) to reactivate viral transcription by recruiting cellular transcriptional elongation factors, such as CDK9, CCNT1 and EP300","subcellular_location":"Nucleus; Cytoplasm; Nucleus, nucleoplasm; Cytoplasm, perinuclear region; Cytoplasm, cytoskeleton, spindle pole; Cytoplasm, cytoskeleton, microtubule organizing center, centrosome; Chromosome, centromere, kinetochore","url":"https://www.uniprot.org/uniprotkb/Q00613/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/HSF1","classification":"Common Essential","n_dependent_lines":611,"n_total_lines":1208,"dependency_fraction":0.5057947019867549},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000185122","cell_line_id":"CID000039","localizations":[{"compartment":"nucleoplasm","grade":3},{"compartment":"nuclear_punctae","grade":2}],"interactors":[{"gene":"HSF2","stoichiometry":0.2},{"gene":"DDX27","stoichiometry":0.2},{"gene":"HIST1H2AJ;HIST1H2AH;HIST1H2AG;H2AFJ","stoichiometry":0.2},{"gene":"H2AFJ","stoichiometry":0.2},{"gene":"VCP","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID000039","total_profiled":1310},"omim":[{"mim_id":"620685","title":"CHROMOSOME 19 OPEN READING FRAME 53; C19ORF53","url":"https://www.omim.org/entry/620685"},{"mim_id":"615153","title":"MIXED LINEAGE KINASE DOMAIN-LIKE PROTEIN; MLKL","url":"https://www.omim.org/entry/615153"},{"mim_id":"610596","title":"BLOCK OF PROLIFERATION 1; BOP1","url":"https://www.omim.org/entry/610596"},{"mim_id":"610157","title":"HEAT-SHOCK RNA 1","url":"https://www.omim.org/entry/610157"},{"mim_id":"609532","title":"HEPATITIS C VIRUS, SUSCEPTIBILITY TO","url":"https://www.omim.org/entry/609532"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/HSF1"},"hgnc":{"alias_symbol":["HSTF1"],"prev_symbol":[]},"alphafold":{"accession":"Q00613","domains":[{"cath_id":"1.10.10.10","chopping":"18-115","consensus_level":"high","plddt":90.9127,"start":18,"end":115},{"cath_id":"1.20.5","chopping":"130-198","consensus_level":"medium","plddt":88.7332,"start":130,"end":198}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q00613","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q00613-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q00613-F1-predicted_aligned_error_v6.png","plddt_mean":61.31},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=HSF1","jax_strain_url":"https://www.jax.org/strain/search?query=HSF1"},"sequence":{"accession":"Q00613","fasta_url":"https://rest.uniprot.org/uniprotkb/Q00613.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q00613/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q00613"}},"corpus_meta":[{"pmid":"21417720","id":"PMC_21417720","title":"Regulation 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HSF1 produced in E. coli in the absence of heat shock is active as a DNA-binding transcription factor, indicating that its intrinsic activity is under negative control in human cells.\",\n      \"method\": \"cDNA cloning, recombinant protein expression in E. coli, DNA-binding assay\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct in vitro reconstitution of DNA-binding activity from recombinant protein; foundational cloning paper replicated broadly\",\n      \"pmids\": [\"1871105\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"HSF1 and HSF2 bind distinct DNA sequences (alternating inverted nGAAn pentamers). HSF1 exhibits higher cooperativity and can occupy extended HSE sequences, and the domain responsible for cooperative interactions maps within or adjacent to the HSF1 DNA-binding domain, as demonstrated by chimeric HSF1/HSF2 proteins.\",\n      \"method\": \"SELEX (protein binding + PCR amplification of random sequences), EMSA, chimeric protein mutagenesis\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro SELEX and EMSA with mutagenesis and chimeric proteins in a single focused study\",\n      \"pmids\": [\"7935474\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Hsp70 and its cochaperone Hdj1 directly interact with the transactivation domain of HSF1 and repress heat shock gene transcription. Overexpression of either chaperone represses endogenous HSF1 transcriptional activity without affecting HSF1 DNA binding or inducible phosphorylation, identifying chaperone binding to the transactivation domain as the primary autoregulatory mechanism during attenuation.\",\n      \"method\": \"Co-immunoprecipitation, GAL4-HSF1 transactivation domain fusion reporter assay, overexpression of Hsp70/Hdj1\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP plus functional reporter assay, widely replicated across labs\",\n      \"pmids\": [\"9499401\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"The co-chaperone/ubiquitin ligase CHIP induces trimerization and transcriptional activation of HSF1, and CHIP-deficient mice are temperature-sensitive and undergo multi-organ apoptosis upon environmental challenge, establishing CHIP as a positive regulator of HSF1 at the level of trimerization.\",\n      \"method\": \"CHIP knockout mouse phenotyping, HSF1 trimerization assay, transcriptional activation assays, stress-induced apoptosis measurement\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with defined phenotype combined with biochemical trimerization assay in multiple systems\",\n      \"pmids\": [\"14532117\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"HSF1 directly binds a heat shock element within the XAF1 gene promoter (-862/-821 region) and represses XAF1 transcription, establishing HSF1 as a transcriptional repressor of a pro-apoptotic gene.\",\n      \"method\": \"Luciferase reporter assay, EMSA, chromatin immunoprecipitation (ChIP), site-directed mutagenesis of HSE\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — ChIP, EMSA, reporter assay and mutagenesis in one study provide orthogonal evidence\",\n      \"pmids\": [\"16303760\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"HSF1-mediated transcription directly drives expression of the pro-apoptotic gene Tdag51. Hsp proteins bind directly to the N-terminal pleckstrin-homology-like (PHL) domain of Tdag51 and suppress its death-promoting activity, defining an HSF1-dependent death pathway counterbalanced by its own chaperone targets.\",\n      \"method\": \"Direct target gene identification (Tdag51 as HSF1 target), direct binding assay of Hsps to Tdag51 PHL domain, Tdag51-null mouse testis analysis\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with defined phenotype plus binding assay; single lab study\",\n      \"pmids\": [\"17024176\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"In yeast, the Yak1 kinase directly phosphorylates Hsf1 in vitro, leading to increased Hsf1 DNA-binding activity. Yak1 is under negative control of PKA, placing Hsf1 in a PKA-Yak1-Hsf1 signaling axis that links nutrient sensing to the heat shock response.\",\n      \"method\": \"In vitro kinase assay, EMSA (DNA binding assay), genetic epistasis (PKA/Pde2 overexpression)\",\n      \"journal\": \"Molecular microbiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct in vitro kinase assay plus genetic epistasis in a single study\",\n      \"pmids\": [\"18793336\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Loss of HSF1 results in failure to arrest in G2 after ionizing radiation, reduced repair of double-strand DNA breaks, and failure of 53BP1 to accumulate at DNA damage sites, establishing HSF1 as required for DNA damage checkpoint activation and DNA repair.\",\n      \"method\": \"HSF1 loss-of-function (functional HSF1-deficient cells), cell cycle analysis, γH2AX and 53BP1 foci immunofluorescence\",\n      \"journal\": \"Radiation research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — clean loss-of-function with defined cellular phenotypes; single lab, single study\",\n      \"pmids\": [\"21557666\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"MEK directly phosphorylates HSF1, making HSF1 a new MEK substrate beyond ERK. MEK blockade inactivates HSF1 and provokes protein aggregation and amyloidogenesis in tumor cells, identifying the RAS-MEK-HSF1 axis as a proteostasis guardian in cancer.\",\n      \"method\": \"In vitro kinase assay (MEK phosphorylation of HSF1), biochemical fractionation, protein aggregation assays, in vivo tumor growth models\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct in vitro kinase assay plus in vivo genetic and pharmacologic validation in multiple models\",\n      \"pmids\": [\"25679764\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"NEDD4 is the E3 ubiquitin ligase responsible for HSF1 degradation via the ubiquitin-proteasome system under α-synuclein proteotoxic stress. Acetylation status of Lys80 in the HSF1 DNA-binding domain is a critical determinant of HSF1 protein stability; SIRT1-mediated deacetylation attenuates NEDD4-mediated HSF1 degradation.\",\n      \"method\": \"Ubiquitination assay, NEDD4 knockdown, site-directed mutagenesis of Lys80, SIRT1 pharmacological activation, in vivo mouse and human tissue validation\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — multiple orthogonal methods (ubiquitination assay, mutagenesis, knockdown, in vivo models) in one study\",\n      \"pmids\": [\"26503960\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"IER5 interacts with PP2A and its B55 regulatory subunits; B55 directly binds HSF1 and promotes HSF1 dephosphorylation, leading to activation of HSF1 target genes. IER5 functions as a positive feedback regulator of HSF1 through the PP2A/B55 complex.\",\n      \"method\": \"Co-immunoprecipitation, HSF1 dephosphorylation assay, target gene expression assay\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — Co-IP plus functional gene expression assay; single lab, single study\",\n      \"pmids\": [\"25816751\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"HSF1 forms a ternary complex with PARP13 and PARP1; HSF1 recruits PARP1 through the scaffold protein PARP13. HDAC1 maintains PARP1 in the complex by deacetylating and inactivating PARP1. Upon DNA damage, auto-PARylated PARP1 dissociates and redistributes to DNA lesions, and disruption of this complex impairs DNA repair and gene expression.\",\n      \"method\": \"Co-immunoprecipitation, ChIP, HDAC1 functional assay, DNA damage repair assays, BRCA1-null tumor model\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, ChIP, and functional rescue in multiple systems in one study\",\n      \"pmids\": [\"29158484\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"HSF1 transcriptionally regulates nicotinamide phosphoribosyltransferase in the NAD+ salvage pathway; loss of HSF1 reduces NAD+ and ATP levels, impairs NAD+-dependent deacetylase activity, increases protein acetylation, and disrupts mitochondrial integrity in hepatic cells.\",\n      \"method\": \"HSF1 KO cells/mice, NAD+/ATP measurement, NAD+-dependent deacetylase activity assay, ChIP for HSF1 at NAMPT promoter, mitochondrial integrity assays\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (KO, metabolite measurements, ChIP) in one study\",\n      \"pmids\": [\"28183717\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"HSF1 directly binds the ATG4B gene promoter (at the -1429 to -1417 region) and upregulates ATG4B transcription, thereby enhancing protective autophagy in hepatocellular carcinoma cells treated with epirubicin.\",\n      \"method\": \"Luciferase reporter assay, ChIP assay, shRNA knockdown, in vivo xenograft\",\n      \"journal\": \"Cancer letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP and reporter assay with functional in vivo validation; single lab\",\n      \"pmids\": [\"28889000\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"HSF1 triggers SQSTM1/p62 phosphorylation at S349 and S403 in an HSF1-dependent manner via casein kinase 1, promoting inclusion formation and autophagosome-mediated clearance of protein aggregates.\",\n      \"method\": \"HSF1 inhibition, phospho-specific antibodies, autophagy flux assays, inclusion formation assay\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — functional pathway assays with HSF1 inhibition; single lab, limited mechanistic depth in abstract\",\n      \"pmids\": [\"27846364\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"In beta cells, glucolipotoxicity promotes HSF1 acetylation via interaction with the acetyltransferase CBP, which inhibits HSF1 DNA-binding activity and decreases target gene expression. A K80Q acetylation-mimicking mutant of HSF1 fails to protect against glucolipotoxicity, establishing K80 acetylation as a negative regulatory PTM.\",\n      \"method\": \"Gel shift assay (EMSA), western blot for HSF1-CBP interaction, HSF1 K80Q acetylation-mimicking mutant, gene expression analysis\",\n      \"journal\": \"Diabetologia\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 / Weak — EMSA, interaction assay, and mutagenesis; single lab study\",\n      \"pmids\": [\"28547133\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Yak1 kinase (yeast) and its downstream regulation of Hsf1 was validated as a two-component negative feedback loop: Hsp70 binds Hsf1 at conserved element 2 (CE2) with low affinity (~9 µM in vitro), releasing Hsf1 when Hsp70 is titrated by misfolded proteins. Removal of CE2 increases basal Hsf1 activity and delays deactivation; tandem CE2 repeats accelerate deactivation. An N-terminal domain of Hsf1 negatively regulates DNA binding.\",\n      \"method\": \"In vitro Hsp70-CE2 binding assay (affinity measurement), CE2 deletion and repeat mutants in cells, mathematical modeling validated by genetic uncoupling of Hsp70 induction\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro binding reconstitution with affinity measurement, plus genetic validation with multiple mutants in cells\",\n      \"pmids\": [\"29393852\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"AKT1 phosphorylates HSF1 at multiple sites: S326 (required for transactivation), T142 (required for trimerization), S230 and T527 (required for gene transactivation and recruitment of TFIIB and CDK9). AKT1 is the most potent activator of HSF1 among several kinases tested (mTOR, p38, MEK1, DYRK2) that all phosphorylate S326.\",\n      \"method\": \"Mass spectrometry (identification of phosphosites), site-directed mutagenesis of HSF1 phosphosites, in vitro kinase assays, HSF1 trimerization assay, reporter assay for transactivation, TFIIB/CDK9 recruitment assay\",\n      \"journal\": \"The FEBS journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — mass spectrometry, mutagenesis, in vitro kinase assays and functional assays in one study\",\n      \"pmids\": [\"35080342\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"PIM2 kinase phosphorylates HSF1 at Thr120, which disrupts HSF1 binding to the E3 ubiquitin ligase FBXW7, thereby stabilizing HSF1 protein. HSF1 pThr120 also promotes HSF1 binding to the PD-L1 promoter and enhances PD-L1 expression.\",\n      \"method\": \"In vitro kinase assay, Co-IP of HSF1 with FBXW7, HSF1 T120A mutant analysis, ChIP at PD-L1 promoter, in vivo xenograft\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — in vitro kinase assay, co-IP, mutagenesis, and ChIP in one study\",\n      \"pmids\": [\"31409638\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"In budding yeast, Hsp70 inhibits Hsf1 DNA-binding activity through its canonical substrate-binding domain. During heat shock, cytoplasmic misfolded proteins derived from ongoing translation titrate Hsp70 away from Hsf1, releasing Hsf1 to activate the heat shock response. Blocking protein synthesis before stress prevents Hsf1 activation.\",\n      \"method\": \"In vitro reconstitution of Hsf1-Hsp70 complexes, EMSA, misfolded protein titration assay, genetic analysis of translation inhibition\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with EMSA plus genetic validation; mechanistically detailed\",\n      \"pmids\": [\"31552827\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"HSF1 interacts with the pericentromeric protein shugoshin 2 (SGO2) during heat shock in a manner dependent on inducible phosphorylation of HSF1 at serine 326. SGO2 binds RNA Pol II with a hypophosphorylated C-terminal domain and is recruited to HSP70 promoter, where it facilitates Pol II recruitment and HSP70 expression.\",\n      \"method\": \"Co-IP of HSF1 and SGO2, phospho-S326 dependency assay, ChIP at HSP70 promoter, comparative analysis of HSF1 paralogs and mutants\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, ChIP, mutagenesis, and functional gene expression assays in one study\",\n      \"pmids\": [\"31657478\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"AKT activates HSF1 via Ser230 phosphorylation. HSF1 physically neutralizes soluble amyloid oligomers (AOs) and shields HSP60 from direct assault by AOs, preventing HSP60 destabilization, mitochondrial proteome collapse, and apoptosis. This mechanism also operates in Alzheimer's disease models.\",\n      \"method\": \"In vitro AO-HSF1 binding assay, Hsf1-deficient mouse model with PI3K/AKT hyperactivation, phospho-site mutagenesis (S230A), mitochondrial integrity assays\",\n      \"journal\": \"Science advances\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct binding assay for HSF1-amyloid oligomers plus genetic and pharmacologic in vivo evidence; single lab\",\n      \"pmids\": [\"33177089\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"HSF1 foci (nuclear stress bodies) form as small, fluid condensates that enlarge into gel-like indissoluble arrangements under prolonged stress. Foci dissolution (not formation) promotes HSF1 transcriptional activity and cell survival; cells with gel-like HSF1 foci show reduced chaperone gene induction and increased apoptosis, identifying phase transition of HSF1 as a cell-fate determinant.\",\n      \"method\": \"Live-cell microscopy (single-cell), FRAP, multiplexed tissue imaging, quantitative single-cell analysis\",\n      \"journal\": \"Nature cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal imaging methods (FRAP, live-cell microscopy, tissue imaging) with functional single-cell readouts in one study\",\n      \"pmids\": [\"32015439\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"HSF1 activation by proteotoxic stress requires concurrent protein synthesis; inhibiting translation before stress prevents Hsf1 activation across diverse stresses. Newly synthesized proteins are especially susceptible to proteotoxic conditions, and disruption of their assembly or localization is sufficient to activate Hsf1.\",\n      \"method\": \"Pharmacological translation inhibition (cycloheximide and others), ethanol-induced stress, nascent protein localization disruption assays in S. cerevisiae\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — systematic genetic and pharmacologic dissection across multiple stresses; single lab\",\n      \"pmids\": [\"34191586\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"HSF1 forms small nuclear condensates via liquid-liquid phase separation (LLPS) at HSP gene loci during heat shock, enriching transcription machinery through co-phase separation. HSP70 disperses HSF1 condensates to attenuate transcription after heat shock and prevents gel-like phase transition under extended stress. Phosphorylation at specific sites in the regulatory domain fine-tunes HSF1 phase-separation capacity.\",\n      \"method\": \"Super-resolution imaging, in vitro reconstitution of LLPS, high-throughput sequencing, phosphosite mutational analysis\",\n      \"journal\": \"Nature cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution of LLPS, super-resolution imaging, and sequencing with multiple orthogonal methods in one rigorous study\",\n      \"pmids\": [\"35256776\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"HSF2 physically and functionally interacts with HSF1 across diverse cancer types; the two factors share notably similar chromatin occupancy and regulate a common set of genes including HSPs and non-canonical cancer targets. Loss of either HSF1 or HSF2 dysregulates the response to nutrient stress and reduces tumor progression, establishing HSF2 as a critical HSF1 cofactor in cancer.\",\n      \"method\": \"Co-immunoprecipitation of HSF1-HSF2, ChIP-seq (occupancy comparison), genetic knockdown of HSF1/HSF2, xenograft tumor models\",\n      \"journal\": \"Science advances\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, ChIP-seq, genetic KD, and in vivo validation in one study\",\n      \"pmids\": [\"35294249\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"HSF1 phosphorylation at S419 by PLK1 recruits the TRRAP-TIP60 acetyltransferase complex to the HSP72 promoter. TIP60-mediated acetylation then recruits TRIM33 (a bromodomain-containing ubiquitin ligase), which cooperates with TRIM24 for mono-ubiquitination of histone H2B at K120, establishing an active chromatin state at HSP gene promoters.\",\n      \"method\": \"ChIP, Co-IP, PLK1 kinase assay, mutagenesis of HSF1-S419, histone modification analysis, melanoma cell proliferation assay\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — ChIP, Co-IP, kinase assay, and mutagenesis with histone modification readouts in one study\",\n      \"pmids\": [\"35906200\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Mitochondria-localizing HSF1 (mtHSF1) accumulates in Huntington's disease models and drives mitochondrial fission by activating Drp1 phosphorylation at S616 and suppresses SSBP1 oligomer formation, causing mitochondrial DNA deletion. A peptide inhibitor (DH1) blocking HSF1 mitochondrial localization ameliorates HD phenotypes.\",\n      \"method\": \"Subcellular fractionation, overexpression of mitochondria-targeting HSF1, Drp1-S616 phosphorylation assay, SSBP1 oligomerization assay, mtDNA deletion analysis, HD mouse model and human striatal organoids\",\n      \"journal\": \"EMBO molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple mechanistic assays in multiple models; single lab study\",\n      \"pmids\": [\"35670111\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"In cardiomyocytes, HSF1 deficiency reduces GPX4 protein expression and disrupts iron homeostasis by transcriptionally regulating iron metabolism genes (Fth1, Tfrc, Slc40a1). HSF1 overexpression restores GPX4 expression by inhibiting ER stress (not autophagy), and Hsf1−/− mice show exacerbated ferroptosis with enhanced ER stress upon palmitic acid challenge.\",\n      \"method\": \"HSF1 overexpression/knockdown, Hsf1−/− mouse model, iron metabolism gene expression analysis (qPCR), ER stress inhibitor experiments, GPX4 western blot\",\n      \"journal\": \"Journal of molecular and cellular cardiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO mouse model plus mechanistic dissection of ER stress pathway; single lab\",\n      \"pmids\": [\"33098823\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"HSF1-mediated neuroprotection does not require HSF1 trimerization (normally obligatory for HSP gene promoter binding). Protection is also independent of HSP70/HSP90 but requires classical HDACs and involves cooperation with SIRT1, defining a noncanonical, trimerization-independent neuroprotective mechanism.\",\n      \"method\": \"HSF1 trimerization-deficient mutants, HSP70 knockdown, HDAC inhibitor treatment, SIRT1 genetic/pharmacologic manipulation, cell culture models of Huntington's disease\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple mutants and pharmacologic tools in one study; single lab\",\n      \"pmids\": [\"24478344\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"In Candida albicans, Hsp90 regulates Hsf1 activation both under basal conditions and during heat shock but with opposing effects; these effects are controlled in part at the level of Hsf1 expression and DNA binding. Hsp90 also modulates global transcription programs by regulating nucleosome levels at promoters of stress-responsive genes.\",\n      \"method\": \"RNA-seq, ChIP-seq (Hsf1 occupancy), Hsp90 inhibitor treatment, nucleosome occupancy assay\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genome-wide ChIP-seq and RNA-seq with functional pharmacological perturbation; ortholog study in C. albicans\",\n      \"pmids\": [\"27226156\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"In budding yeast, Hsf1 is incapable of binding HSEs within a stably positioned, reconstituted nucleosome, but accesses nucleosomal sites during heat shock in concert with the RSC chromatin remodeling complex, which promotes chromatin disassembly.\",\n      \"method\": \"ChIP-seq (Hsf1 binding), nascent RNA-seq, Hsf1 nuclear depletion, in vitro nucleosome binding assay\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — in vitro nucleosome binding assay plus genome-wide ChIP-seq and nascent RNA-seq with genetic depletion\",\n      \"pmids\": [\"30332327\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"ABL2 tyrosine kinase directly interacts with HSF1 protein via its SH3 domain at a noncanonical, proline-independent SH3 interaction motif, regulating HSF1 protein expression. Allosteric (but not ATP-competitive) ABL2 inhibition disrupts this interaction and impairs HSF1-driven E2F transcriptional targets required for brain metastasis outgrowth.\",\n      \"method\": \"Co-IP of ABL2 SH3 domain with HSF1, allosteric vs ATP-competitive inhibitor comparison, HSF1 knockdown, brain metastasis in vivo model\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct Co-IP plus pharmacologic discrimination of inhibitor mechanisms; single lab\",\n      \"pmids\": [\"33318173\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"HSF1 Ser326 phosphorylation generates cell-to-cell variation in Hsp90 levels, and this variation (rather than average Hsf1 activity) promotes phenotypic plasticity and antifungal drug resistance in budding yeast. Hsp90 is required for enrichment of drug-resistant cells with high Hsf1 activity.\",\n      \"method\": \"Single-cell fluorescence microscopy, HSF1 phospho-mutant analysis (S326A), genetic Hsp90 manipulation, antifungal resistance assay\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — phospho-mutant analysis and single-cell imaging with functional phenotypic readout; single lab\",\n      \"pmids\": [\"29562166\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"In CLL, HSF1 maintains a cytosolic complex with p97, HSP90, and HDAC6; HSF1 inhibition disrupts this complex, causing HSP90 acetylation and abrogating HSP90 chaperone function, leading to loss of HSP90 kinase clients (BTK, c-RAF, CDK4) and depletion of CDC37-HSP90 association.\",\n      \"method\": \"Co-IP of HSF1-p97-HSP90-HDAC6 complex, HSF1 knockdown/triptolide inhibition, HSP90 acetylation assay, client kinase depletion, in vivo Mec-1 leukemia model\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP of multi-protein complex plus functional client depletion and in vivo validation; single lab\",\n      \"pmids\": [\"26397138\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"FAM3C overexpression increases HSF1 expression in hepatocytes; HSF1 in turn elevates calmodulin (CaM) protein by inducing CALM1 transcription, which activates Akt in a Ca2+- and insulin-independent manner, defining a FAM3C-HSF1-CaM-Akt pathway controlling hepatic gluconeogenesis and lipid metabolism.\",\n      \"method\": \"HSF1 overexpression, CALM1 promoter-driven reporter assay, Akt activation assay, gluconeogenesis gene expression in vivo and in vitro, CaM-dependent rescue experiments\",\n      \"journal\": \"Diabetes\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — promoter reporter, genetic overexpression with functional metabolic readouts and in vivo validation; single lab\",\n      \"pmids\": [\"28246289\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"HSF1 directly binds BDNF gene (Bdnf) promoters (promoters I and IV) in the hippocampus in vivo after kainic acid or footshock, and HSF1 overexpression increases BDNF mRNA and protein in primary neurons. HSF1 binding sites co-immunoprecipitate with pCREB at Bdnf promoters, suggesting functional cooperation.\",\n      \"method\": \"ChIP-qPCR in mouse hippocampus, luciferase reporter assay, viral HSF1 overexpression in neurons, immunohistochemistry\",\n      \"journal\": \"Journal of neurochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo ChIP-qPCR plus reporter and overexpression assays; single lab\",\n      \"pmids\": [\"36227087\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"AMPKα (when dephosphorylated by PP2A/B56δ) phosphorylates HSF1 at Ser303, leading to transcriptional suppression of HSP70 and HSP27 under metal stress. PP2A B56δ physically interacts with AMPKα, establishing a PP2A-AMPKα-HSF1 signaling axis that regulates HSP expression.\",\n      \"method\": \"In vitro phosphorylation assay (AMPKα phosphorylation of HSF1 at S303), Co-IP of PP2A B56δ with AMPKα, siRNA knockdown, HSP expression analysis\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 / Weak — in vitro kinase assay and Co-IP; single lab, limited mechanistic detail in abstract\",\n      \"pmids\": [\"24412756\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"HSF1 directly binds the HMGB1 promoter and negatively regulates HMGB1 transcription; HSF1 knockdown aggravates OVA-induced airway inflammation and hyperreactivity by promoting HMGB1 expression and activating the TLR4/MyD88/NF-κB pathway.\",\n      \"method\": \"ChIP assay, luciferase reporter assay, HSF1 knockdown in OVA asthma mouse model, ELISA for inflammatory markers\",\n      \"journal\": \"Life sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — ChIP and reporter assay plus in vivo KD; single lab\",\n      \"pmids\": [\"31825792\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Hsf1 directly binds the promoter of PPARγ coactivator-1α (PGC-1α) when phosphorylated at Ser326 and translocated to the nucleus, inducing mitochondrial biogenesis and oxidative metabolism in hepatocytes. HSF1 and PGC-1α deletion experiments confirmed the HSF1/PGC-1α pathway is independent of AMPK.\",\n      \"method\": \"ChIP-seq (HSF1 binding to PGC-1α promoter), phospho-HSF1 (S326) nuclear translocation assay, HSF1-deficiency rescue experiments, mitochondrial biogenesis assay\",\n      \"journal\": \"British journal of pharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP-seq with genetic rescue experiments; single lab\",\n      \"pmids\": [\"34783017\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"HSF1 is the prime transcription factor for ATG5 and ATG12 in melanocytes; HSF1 deficiency reduces ATG5 and ATG12 expression, leading to accumulation of intracellular ROS, mitochondrial membrane potential imbalance, and apoptosis under oxidative stress. HSF1 overexpression activates protective autophagy via ATG5/ATG12 upregulation.\",\n      \"method\": \"RNA-sequencing, HSF1 KD/overexpression, autophagy flux assay, ROS measurement, mitochondrial membrane potential assay\",\n      \"journal\": \"The Journal of investigative dermatology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — transcriptomics plus functional autophagy and cell death assays; single lab\",\n      \"pmids\": [\"34780715\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"CHIP (C-terminus of Hsp70-interacting protein) mediates HSF1 stability and nuclear translocation through direct interaction via its tetratricopeptide repeat (TPR) domain. Doxorubicin diminishes the CHIP-HSF1 interaction and triggers proteasomal HSF1 degradation, relieving HSF1 repression of IGF-IIR expression and promoting cardiomyocyte apoptosis.\",\n      \"method\": \"Co-IP of CHIP and HSF1, domain-mapping (TPR domain), proteasome inhibitor experiments, IGF-IIR expression assay, CHIP overexpression rescue, in vitro and in vivo cardiac models\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — domain-specific Co-IP with functional rescue assays; single lab\",\n      \"pmids\": [\"27809308\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"HSF1 directly binds the miR-214-3p promoter to increase its expression; miR-214-3p in turn targets and suppresses NFATc2 transcription. This HSF1-miR-214-3p-NFATc2 axis inhibits microglia activation and neuroinflammation in a Parkinson's disease mouse model.\",\n      \"method\": \"ChIP assay (HSF1 at miR-214-3p promoter), dual-luciferase assay (miR-214-3p target NFATc2), functional rescue in MPTP mouse model\",\n      \"journal\": \"Folia neuropathologica\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — ChIP and dual-luciferase plus in vivo rescue; single lab study with limited mechanistic depth in abstract\",\n      \"pmids\": [\"37114961\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"HSF1 is a stress-activated transcription factor that exists as a negatively regulated monomer in unstressed cells (held latent by Hsp90 and Hsp70 binding to its regulatory and transactivation domains); proteotoxic stress titrates Hsp70 away via misfolded proteins, releasing HSF1 to trimerize, translocate to the nucleus, and bind heat shock elements (HSEs) to drive chaperone gene expression through liquid-liquid phase separation condensates at target loci—a response attenuated by Hsp70 rebinding to the transactivation domain, HSP70-mediated condensate dispersal, and post-translational modifications including phosphorylation (at S326 by AKT1/mTOR/MEK/p38/PLK1, at T142 required for trimerization, at S419 required for TRRAP-TIP60 chromatin remodeling, and inhibitory phosphorylation at S303 by AMPKα), acetylation at K80 (by CBP, inhibitory; reversed by SIRT1), sumoylation, and ubiquitin-mediated degradation (by NEDD4 and FBXW7); beyond canonical HSP gene regulation, HSF1 represses pro-apoptotic targets (XAF1, HMGB1), activates non-canonical targets (ATG4B, ATG5/12, PD-L1, CALM1/CaM, Tdag51, BDNF, PGC-1α), forms a ternary complex with PARP13-PARP1 to regulate DNA repair, cooperates with HSF2 to drive a cancer-specific transcriptional program, and physically neutralizes amyloid oligomers to suppress proteotoxic amyloidogenesis.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"HSF1 is the master stress-activated transcription factor of the heat shock response, driving chaperone gene expression while existing under negative control in unstressed cells [#0, #19]. Its intrinsic DNA-binding and transactivation activities are intrinsically active but held latent: Hsp70 binds the HSF1 transactivation domain (and, via a low-affinity conserved element CE2, the regulatory region) to repress transcription, and proteotoxic stress titrates Hsp70 away through misfolded proteins arising from ongoing translation, releasing HSF1 to trimerize and bind heat shock elements (HSEs) of inverted nGAAn pentamers [#1, #2, #16, #19, #23]. Activation is positively driven by the co-chaperone/ubiquitin ligase CHIP, which promotes trimerization, and by IER5-PP2A/B55-mediated dephosphorylation [#3, #10, #15]. Promoter engagement requires chromatin remodeling—HSF1 cannot access nucleosomal HSEs without the RSC complex, and PLK1 phosphorylation at S419 recruits the TRRAP-TIP60 acetyltransferase complex to establish active chromatin at HSP loci [#26, #31]. At target genes HSF1 nucleates liquid-liquid phase-separated condensates (nuclear stress bodies) that concentrate transcription machinery; HSP70 disperses these condensates to attenuate transcription, and a fluid-to-gel phase transition under prolonged stress switches the response from survival to apoptosis [#22, #24]. HSF1 activity is extensively tuned by phosphorylation, including activating sites S326 (by AKT1, mTOR, MEK, p38), T142 (trimerization), and S230, and inhibitory S303 by AMPKα, alongside acetylation at K80 by CBP (inhibitory, reversed by SIRT1) and degradation through NEDD4 and FBXW7, the latter blocked by PIM2 phosphorylation at T120 [#8, #9, #15, #17, #18, #37]. Beyond canonical chaperone induction, HSF1 represses pro-apoptotic targets (XAF1, HMGB1), activates autophagy genes (ATG4B, ATG5/12) and metabolic genes (NAMPT, PGC-1α, CALM1), forms a ternary complex with PARP13 and PARP1 to support DNA repair, cooperates with HSF2 to drive a cancer-specific transcriptional program, and physically neutralizes amyloid oligomers to suppress proteotoxicity [#4, #11, #12, #21, #25, #38, #39, #40].\",\n  \"teleology\": [\n    {\n      \"year\": 1991,\n      \"claim\": \"Establishing whether HSF1's activity is intrinsic or stress-gated: recombinant HSF1 from bacteria was DNA-binding competent without heat shock, showing the protein is intrinsically active and held under negative control in human cells.\",\n      \"evidence\": \"cDNA cloning and recombinant expression in E. coli with DNA-binding assay\",\n      \"pmids\": [\"1871105\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify the repressing factor\", \"No structure of the DNA-binding or trimerization domains\"]\n    },\n    {\n      \"year\": 1994,\n      \"claim\": \"Defining the DNA target: SELEX and chimeric proteins showed HSF1 recognizes inverted nGAAn pentamer HSEs with high cooperativity mapping to its DNA-binding domain, distinguishing it from HSF2.\",\n      \"evidence\": \"SELEX, EMSA, and chimeric HSF1/HSF2 mutagenesis in vitro\",\n      \"pmids\": [\"7935474\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not address in vivo nucleosomal access\", \"Cooperativity mechanism at the molecular level unresolved\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Identifying the autoregulatory brake: Hsp70/Hdj1 binding to the HSF1 transactivation domain represses transcription without altering DNA binding, defining chaperone titration as the core attenuation mechanism.\",\n      \"evidence\": \"Co-IP and GAL4-transactivation domain reporter with chaperone overexpression\",\n      \"pmids\": [\"9499401\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Quantitative affinity and stoichiometry not measured here\", \"Did not address regulatory-domain Hsp70 binding\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Identifying a positive regulator of activation: CHIP promotes HSF1 trimerization and transcription, and its loss causes stress-induced multi-organ apoptosis in mice.\",\n      \"evidence\": \"CHIP knockout mouse phenotyping with trimerization and transcription assays\",\n      \"pmids\": [\"14532117\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct biochemical step CHIP acts on during trimerization not fully resolved\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Extending HSF1 beyond gene activation: HSF1 binds an HSE in the XAF1 promoter and represses this pro-apoptotic gene, establishing it as a direct transcriptional repressor.\",\n      \"evidence\": \"ChIP, EMSA, reporter assay, and HSE mutagenesis\",\n      \"pmids\": [\"16303760\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Co-repressor machinery for HSF1-mediated repression not identified\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Linking nutrient signaling to the heat shock response: yeast Yak1 directly phosphorylates Hsf1 to increase DNA binding, under PKA negative control.\",\n      \"evidence\": \"In vitro kinase assay, EMSA, and genetic epistasis in yeast\",\n      \"pmids\": [\"18793336\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Phosphosites not mapped\", \"Human ortholog of this axis not addressed\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Connecting HSF1 to genome stability: HSF1 loss impairs the G2/IR checkpoint, double-strand break repair, and 53BP1 focus formation.\",\n      \"evidence\": \"HSF1-deficient cells with cell-cycle analysis and γH2AX/53BP1 immunofluorescence\",\n      \"pmids\": [\"21557666\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab, single study\", \"Direct molecular link to repair machinery not established here\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Defining a trimerization-independent role: HSF1 neuroprotection in Huntington's models requires HDACs and SIRT1 cooperation but not trimerization or HSP70/90, revealing a noncanonical function.\",\n      \"evidence\": \"Trimerization-deficient mutants, HDAC inhibitors, and SIRT1 manipulation in HD cell models\",\n      \"pmids\": [\"24478344\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct target genes of this noncanonical mode unknown\", \"Single lab\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Establishing inhibitory phosphorylation: AMPKα phosphorylates HSF1 at S303 to suppress HSP70/HSP27 under metal stress, via a PP2A-AMPKα axis.\",\n      \"evidence\": \"In vitro kinase assay and Co-IP with HSP expression analysis\",\n      \"pmids\": [\"24412756\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Limited mechanistic detail\", \"Single lab\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Identifying degradation control: NEDD4 ubiquitinates HSF1 under α-synuclein stress, gated by K80 acetylation, which SIRT1 deacetylation reverses to stabilize HSF1.\",\n      \"evidence\": \"Ubiquitination assay, K80 mutagenesis, NEDD4 knockdown, and in vivo models\",\n      \"pmids\": [\"26503960\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Acetyltransferase for K80 not identified here\", \"Interplay with other E3 ligases unresolved\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Expanding the kinase repertoire: MEK directly phosphorylates HSF1, and the RAS-MEK-HSF1 axis guards proteostasis in tumors.\",\n      \"evidence\": \"In vitro kinase assay with protein aggregation and tumor models\",\n      \"pmids\": [\"25679764\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Phosphosite consequences for trimerization vs transactivation not fully separated here\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Identifying an activating dephosphorylation circuit: IER5 recruits PP2A/B55 to dephosphorylate HSF1 and activate target genes as positive feedback.\",\n      \"evidence\": \"Co-IP, dephosphorylation assay, and target gene expression\",\n      \"pmids\": [\"25816751\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Specific sites dephosphorylated not defined\", \"Single lab\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Placing HSF1 in a cytosolic chaperone scaffold: in CLL, HSF1 maintains a p97-HSP90-HDAC6 complex whose disruption acetylates HSP90 and depletes its kinase clients.\",\n      \"evidence\": \"Co-IP of multi-protein complex with client depletion and in vivo leukemia model\",\n      \"pmids\": [\"26397138\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Cytosolic non-transcriptional role mechanistically distinct from nuclear function unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Showing cell-to-cell HSF1 variation drives phenotypic outcomes: S326-dependent Hsf1 activity variation sets Hsp90 levels and antifungal drug resistance.\",\n      \"evidence\": \"Single-cell imaging with S326A mutant and Hsp90 manipulation in yeast\",\n      \"pmids\": [\"29562166\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism generating cell-to-cell variation unresolved\", \"Yeast system\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Linking HSF1 to a multi-protein DNA-repair complex: HSF1 scaffolds a ternary complex with PARP13 and PARP1, releasing auto-PARylated PARP1 to DNA lesions upon damage.\",\n      \"evidence\": \"Reciprocal Co-IP, ChIP, HDAC1 assays, and DNA repair models\",\n      \"pmids\": [\"29158484\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of the ternary complex unknown\", \"How damage signal triggers PARP1 release not detailed\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Connecting HSF1 to NAD+ metabolism: HSF1 transcriptionally drives NAMPT, and its loss lowers NAD+/ATP, raises protein acetylation, and disrupts mitochondria.\",\n      \"evidence\": \"HSF1 KO cells/mice with metabolite measurement and NAMPT ChIP\",\n      \"pmids\": [\"28183717\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Tissue-specificity of the NAMPT axis not fully mapped\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Defining non-canonical autophagy and metabolic targets: HSF1 directly activates ATG4B, induces CKI-dependent SQSTM1/p62 phosphorylation, and drives a FAM3C-HSF1-CaM-Akt metabolic pathway.\",\n      \"evidence\": \"ChIP, reporter assays, phospho-specific readouts, and metabolic assays across cell and mouse models\",\n      \"pmids\": [\"28889000\", \"27846364\", \"28246289\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Each pathway from a single study\", \"Whether these are conserved across tissues unknown\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Resolving the chaperone-titration mechanism biochemically: Hsp70 binds Hsf1 at a low-affinity CE2 element, and CE2 dosage tunes the timing of activation and deactivation.\",\n      \"evidence\": \"In vitro affinity measurement plus CE2 deletion/repeat mutants and modeling in yeast\",\n      \"pmids\": [\"29393852\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Human equivalent of CE2 dynamics not quantified\", \"Role of transactivation-domain Hsp70 binding integrated only partially\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Establishing the proteostatic sensing logic: cytoplasmic misfolded nascent proteins titrate Hsp70 from Hsf1 via its substrate-binding domain, and translation is required to generate the activating signal.\",\n      \"evidence\": \"In vitro reconstitution, EMSA, and translation-inhibition genetics in yeast\",\n      \"pmids\": [\"31552827\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Quantitative threshold of misfolded protein needed to activate not defined\", \"Human in-cell confirmation pending\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Mapping the activating phospho-code and a transcriptional cofactor: PIM2 phosphorylates T120 to block FBXW7 and drive PD-L1, while phospho-S326-dependent SGO2 recruitment facilitates Pol II loading at HSP70.\",\n      \"evidence\": \"Kinase assays, Co-IP, ChIP, and mutagenesis with xenograft models\",\n      \"pmids\": [\"31409638\", \"31657478\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How S326 phosphorylation triggers SGO2 binding structurally unknown\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Establishing phase separation as a cell-fate switch: HSF1 nuclear stress bodies form as fluid condensates whose dissolution promotes transcription and survival, while gel transition triggers apoptosis.\",\n      \"evidence\": \"FRAP, live-cell and multiplexed tissue imaging with single-cell readouts\",\n      \"pmids\": [\"32015439\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular determinants of the fluid-to-gel transition not fully defined here\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Revealing direct cytoprotective binding: AKT-S230-activated HSF1 physically neutralizes amyloid oligomers and shields HSP60 from mitochondrial collapse.\",\n      \"evidence\": \"In vitro AO-binding assay with Hsf1-deficient and S230A mutant models\",\n      \"pmids\": [\"33177089\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural basis of HSF1-oligomer interaction unknown\", \"Single lab\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Reconstituting HSF1 condensates and their dispersal: HSF1 undergoes LLPS at HSP loci to enrich transcription machinery, with HSP70 dispersing condensates and phosphorylation tuning phase-separation capacity.\",\n      \"evidence\": \"Super-resolution imaging, in vitro LLPS reconstitution, sequencing, and phosphosite analysis\",\n      \"pmids\": [\"35256776\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which intrinsically disordered regions drive LLPS not fully mapped\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Defining the cancer-specific cofactor and chromatin-remodeling step: HSF2 co-occupies chromatin with HSF1 to regulate shared targets, and PLK1-S419 phosphorylation recruits TRRAP-TIP60 to establish active chromatin at HSP promoters.\",\n      \"evidence\": \"Co-IP, ChIP-seq, kinase assay, and histone-modification analysis with tumor models\",\n      \"pmids\": [\"35294249\", \"35906200\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How HSF1/HSF2 selectivity for cancer-specific loci is encoded unresolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the layered regulatory inputs—chaperone titration, the multi-site phospho-code, acetylation, ubiquitination, and phase behavior—are integrated to produce locus- and tissue-specific HSF1 outputs (canonical HSP induction vs. non-canonical metabolic, apoptotic, and DNA-repair programs) remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified model linking phospho-state to condensate behavior and target selection\", \"Tissue-specific target choice mechanism unknown\", \"Structural basis of trimerization and DNA-binding regulation in human HSF1 not determined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [0, 4, 11, 25, 36, 38, 39, 40]},\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [0, 1, 4, 31]},\n      {\"term_id\": \"GO:0140313\", \"supporting_discovery_ids\": [21]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [20, 22, 24, 39]},\n      {\"term_id\": \"GO:0005654\", \"supporting_discovery_ids\": [22, 24]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [34]},\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [27]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953897\", \"supporting_discovery_ids\": [2, 16, 19, 23]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0, 4, 25, 26]},\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [7, 11]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [13, 14, 40]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [2, 9, 18]}\n    ],\n    \"complexes\": [\n      \"HSF1-PARP13-PARP1 ternary complex\",\n      \"HSF1-p97-HSP90-HDAC6 cytosolic complex\",\n      \"HSF1-HSF2 heterocomplex\"\n    ],\n    \"partners\": [\n      \"HSP70\",\n      \"HSF2\",\n      \"PARP1\",\n      \"PARP13\",\n      \"CHIP\",\n      \"HSP90\",\n      \"AKT1\",\n      \"FBXW7\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}