{"gene":"SERPINH1","run_date":"2026-06-10T07:46:30","timeline":{"discoveries":[{"year":1991,"finding":"HSP47 (SERPINH1) contains a C-terminal RDEL sequence functioning as an ER-retention signal, belongs to the serpin superfamily but lacks the active site required for serine protease inhibition, and is transcriptionally regulated by heat shock elements in its promoter. Its suppression after Rous sarcoma virus transformation is regulated at the transcriptional level.","method":"cDNA cloning, Northern blot, nuclear run-on assay, amino acid sequence homology analysis","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — direct molecular cloning with functional domain identification, sequence analysis establishing ER-retention signal and serpin membership, replicated across multiple labs subsequently","pmids":["2072906"],"is_preprint":false},{"year":1995,"finding":"HSP47 and cyclophilin B remain associated with procollagen I as it traverses from the ER into pre-Golgi intermediate vesicles. Cyclosporin A treatment diminished CyPB bound to procollagen and slowed the rate of HSP47 release from procollagen and the rate of procollagen secretion, suggesting HSP47 release is coupled to triple-helix formation.","method":"Pulse-chase metabolic labeling, immunoprecipitation, immunofluorescence, pharmacological inhibition of G proteins and vesicular trafficking","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal immunoprecipitation with pharmacological perturbations in a single lab, two orthogonal methods","pmids":["7629154"],"is_preprint":false},{"year":1996,"finding":"Hsp47, GRP78 (BiP), and GRP94 form heteromeric complexes with each other and with nascent chains of collagen type IV in the ER. ATP depletion increased the association of newly synthesized collagen IV with all three chaperones simultaneously.","method":"Co-immunoprecipitation in mouse teratocarcinoma cells, ATP depletion experiments","journal":"Connective tissue research","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — single lab, single co-IP method, but replicated across multiple chaperones and conditions","pmids":["8834444"],"is_preprint":false},{"year":1998,"finding":"HSP47 transiently binds to procollagen III in the ER (confirmed by chemical cross-linking immunoprecipitation), delays secretion of type III procollagen, and prevents overmodification of procollagen chains. In cells expressing HSP47, the electrophoretic mobility and melting temperature of type III procollagen matched those of normal collagen-producing cells, indicating HSP47 prevents overmodification of the procollagen backbone.","method":"Stable transfection of 293 cells with procollagen III ± HSP47, chemical cross-linking (DSP) immunoprecipitation, pulse-chase secretion assays, thermal stability measurements","journal":"Journal of biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reconstitution in heterologous system with chemical cross-link co-IP and functional readout (secretion rate, thermal stability), single lab","pmids":["9722680"],"is_preprint":false},{"year":2001,"finding":"Recombinant mouse Hsp47 exists as both a structurally mesostable monomer (with a 5-strand A-sheet) and a hyperstable trimer; both states have biological activity. Hsp47 can bind a monomeric, partially folded collagen mimic peptide (PPG)10 and induce it to adopt a polyproline type II conformation, promoting higher-order assembly similar to collagen-like structures. The peptide-binding site does not reside in strand 4 of sheet A.","method":"Biophysical analysis of recombinant mouse Hsp47 including circular dichroism, analytical ultracentrifugation, peptide-binding assays","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — in vitro reconstitution and biophysical characterization but single lab","pmids":["11592970"],"is_preprint":false},{"year":2006,"finding":"HSP47 specifically recognizes the collagen triple helix by binding Arg residues at the Yaa position (Arg0) of Gly-Xaa-Arg triplets, and also contacts the residue at the Yaa-3 position on the same peptide strand. Maximal binding affinity occurs when Yaa-3 is Thr. The two key residues must be on the same strand of the triple helix for recognition by HSP47.","method":"Binding assays with synthetic heterotrimeric collagen-model peptides with systematic amino-acid substitutions, competitive inhibition assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — systematic in vitro peptide library approach with structure-activity relationships, findings later confirmed by crystal structures in independent labs","pmids":["16484215"],"is_preprint":false},{"year":2009,"finding":"A missense mutation in SERPINH1 (c.977C>T, p.L326P) in an evolutionarily conserved domain causes autosomal recessive osteogenesis imperfecta in Dachshunds, establishing SERPINH1 as a causative OI gene (the fifth identified).","method":"Homozygosity mapping with SNP chip, haplotype analysis, candidate gene mutation analysis in affected vs. control Dachshunds","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic mapping with perfect phenotypic association, replicated across multiple affected and carrier animals","pmids":["19629171"],"is_preprint":false},{"year":2012,"finding":"Crystal structures of Hsp47 free and in complex with homotrimeric synthetic collagen model peptides reveal that two Hsp47 molecules bind head-to-head to a collagen triple helix, each occupying one of two Arg-containing binding sites. A conserved aspartic acid on Hsp47 recognizes the key arginine in the Xaa-Arg-Gly triplet. A cluster of histidine residues in the structure provides the structural basis for pH-dependent substrate release in cis-Golgi/ERGIC. The structures explain triple-helix stabilization and inhibition of collagen-bundle formation by Hsp47.","method":"X-ray crystallography of Hsp47 alone and in complex with synthetic collagen peptides","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure with mechanistic interpretation, multiple peptide complexes resolved, independently consistent with biochemical data from multiple labs","pmids":["22847422"],"is_preprint":false},{"year":2012,"finding":"Conditional knockout of Hsp47 specifically in chondrocytes (Col2a1-Cre) causes severe chondrodysplasia with reduced type II and XI collagen levels, accumulation of misaligned type I collagen, and loss of type II collagen fibers. This establishes Hsp47 as indispensable for correct folding of type II and type XI procollagens and for cartilage/endochondral bone formation.","method":"Conditional gene knockout (Hsp47 floxed × Col2a1-Cre), second-harmonic generation analysis, electron microscopy, immunohistochemistry, skeletal staining","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — cell-type-specific genetic ablation with multiple orthogonal structural readouts, unambiguous phenotype","pmids":["22492985"],"is_preprint":false},{"year":2014,"finding":"HSP47 and FKBP65 cooperate in posttranslational maturation of type I procollagen. An OI-causing SERPINH1 mutation destabilizes and mislocalizes HSP47, secondarily disrupting FKBP65 localization and preventing normal HSP47-FKBP65 interaction, revealing a common cellular pathway for OI caused by HSP47 and FKBP65 deficiency.","method":"Patient fibroblast biochemical assays, immunofluorescence localization, co-immunoprecipitation, analysis of procollagen processing","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — patient-derived cells with co-IP and localization, single lab, two orthogonal methods","pmids":["25510505"],"is_preprint":false},{"year":2015,"finding":"In the Dachshund OI model (HSP47 L326P mutation), HSP47 chaperone function is impaired in the ER, leading to intracellular procollagen retention with ER dilation and activation of ER stress markers (GRP78, phospho-eIF2α), post-translational overmodification of type I collagen chains, and higher pyridinoline crosslink content in bone collagen.","method":"Biochemical assays on mutant and control skin fibroblasts and bone, SDS-PAGE electrophoretic mobility analysis, tandem mass spectrometry, electron microscopy, ER stress marker immunoblotting","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — multiple orthogonal biochemical methods (MS, SDS-PAGE, EM, immunoblot) on natural disease model, single lab","pmids":["26004778"],"is_preprint":false},{"year":2015,"finding":"Hsp47 silencing in breast cancer cells reprogrammed them to form growth-arrested and non-invasive structures in 3D cultures and reduced collagen and fibronectin deposition. miR-29b and miR-29c directly repress Hsp47 expression along with multiple ECM network genes. Ectopic expression of miR-29b suppressed malignant phenotypes.","method":"Hsp47 siRNA knockdown in 3D culture and xenograft assays, coexpression network analysis, miRNA overexpression, luciferase reporter assays for miR-29 targeting","journal":"Cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional knockdown with phenotypic readout in 3D and in vivo, plus direct miRNA target validation, single lab","pmids":["25744716"],"is_preprint":false},{"year":2015,"finding":"In zebrafish fin regeneration, serpinh1b (Hsp47) acts downstream of the gap junction protein Cx43 to regulate collagen-based actinotrichia organization, cell proliferation, and joint formation. Knockdown of Hsp47 recapitulates the short-fin phenotype with reduced fin/segment length and disrupted actinotrichia.","method":"Morpholino knockdown in zebrafish regenerating fin, short fin (sof) mutant analysis, epistasis experiments","journal":"Mechanisms of development","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis by morpholino knockdown in zebrafish model with clear phenotypic readout, single lab","pmids":["26103547"],"is_preprint":false},{"year":2016,"finding":"SERPINH1 is a direct target of miR-29a as validated by luciferase reporter assay. miR-29a restoration suppressed cancer cell aggressiveness and fibroblast migration in lung cancer cells.","method":"Luciferase reporter assay for direct miRNA targeting, miR-29a restoration experiments in lung cancer cells and lung fibroblasts","journal":"Journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — direct target validation by reporter assay, but single lab, single method for the mechanistic claim","pmids":["27488440"],"is_preprint":false},{"year":2018,"finding":"HSP47 is present on the platelet surface where it binds collagen and modulates GPVI-collagen interaction. Deletion or inhibition of HSP47 in platelets specifically reduces collagen-induced (but not thrombin-induced) platelet activation, GPVI signaling, thrombus formation under arterial flow, and in vivo thrombosis in cremaster arterioles.","method":"Platelet-specific Hsp47 knockout mouse, flow-based thrombus assays, GPVI-collagen binding assays, laser-induced thrombosis, tail bleeding time","journal":"Journal of thrombosis and haemostasis : JTH","confidence":"High","confidence_rationale":"Tier 2 / Strong — cell-type-specific knockout with multiple orthogonal functional assays (in vitro binding, flow assay, in vivo thrombosis), clear mechanistic specificity (collagen vs. thrombin responses)","pmids":["29512284"],"is_preprint":false},{"year":2019,"finding":"Myofibroblast-specific ablation of Hsp47 blocks cardiac fibrosis and deposition of collagens type I, III, and V after pressure overload and reduces cardiac hypertrophy. Cardiomyocyte- or endothelial-specific deletion of Hsp47 has no effect on cardiac fibrosis. Fibroblast-specific Hsp47 deletion causes lethality after myocardial infarction due to failed scar formation and ventricular wall rupture. Deletion of Hsp47 from myofibroblasts reduced fibrillar collagen mRNA and attenuated myofibroblast proliferation without affecting paracrine secretory activity.","method":"Cell-type-specific conditional knockout (myofibroblast, cardiomyocyte, endothelial cell-specific Cre lines), pressure overload and MI models, histological fibrosis assessment, mRNA analysis","journal":"JCI insight","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple cell-type-specific knockouts with orthogonal injury models and clear mechanistic specificity between cell types","pmids":["31393098"],"is_preprint":false},{"year":2019,"finding":"Knockdown of Serpinh1 using siRNA in fibrotic vocal fold mucosa reversed scar-associated collagen accumulation within 4 weeks. Transcriptome analysis showed evidence of cell cycle upregulation, catabolism, matrix disassembly, and morphogenesis as therapeutic outcomes.","method":"Liposome-mediated siRNA delivery in vitro (naive and scar fibroblasts) and in vivo (rat VF mucosa), transcriptome analysis","journal":"Molecular therapy. Nucleic acids","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo knockdown with transcriptomic phenotype readout, single lab, two orthogonal methods","pmids":["31100613"],"is_preprint":false},{"year":2019,"finding":"TGF-β1-induced HSP47 expression in nasal fibroblasts occurs via the Smad2/3 signaling pathway, and HSP47 is required for TGF-β1-induced myofibroblast differentiation, ECM production, fibroblast migration and contraction.","method":"siRNA knockdown of HSP47, Smad2/3 pathway inhibitor experiments, migration and collagen gel contraction assays, immunofluorescence, western blotting","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA knockdown with pathway inhibition and multiple functional readouts, single lab","pmids":["31664133"],"is_preprint":false},{"year":2019,"finding":"Lowering culture temperature to 33°C corrects all procollagen biosynthesis defects in hsp47-/- fibroblasts, including ER accumulation, over-modification (prolyl/lysyl hydroxylation and glycosylation), and secretion of type I collagen homotrimer. This demonstrates that the essential function of HSP47 is to stabilize the elongating, thermally unstable triple helix of procollagen at body temperature.","method":"hsp47-null mouse embryo fibroblasts cultured at 37°C vs. 33°C, procollagen modification analysis, secretion assays, ER accumulation assessment","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 1 / Moderate — genetic null system with temperature-rescue experiment providing direct mechanistic insight, multiple biochemical readouts, single lab","pmids":["31758055"],"is_preprint":false},{"year":2020,"finding":"Live cell imaging with fluorescently tagged procollagen and HSP47 demonstrated that bona fide ER-to-Golgi transport carriers delivering procollagen contain no HSP47 (unless HSP47's RDEL ER-retention signal is deleted). Procollagen co-localizes with HSP47 and ERGIC53 at ER exit sites (ERESs), but co-localizes with ERGIC53 without HSP47 in Golgi-bound transport intermediates. Previously reported HSP47/procollagen puncta were identified as dilated ER regions, ERESs, or autophagic structures rather than transport vesicles. This indicates procollagen and HSP47 sorting occurs at ERES before ER export.","method":"Live cell fluorescence imaging with up to 120 nm spatial / 500 ms time resolution, FRAP, ARF1 inhibition, deletion of RDEL signal, colocalization with ERGIC53 and lysosomal markers","journal":"Matrix biology : journal of the International Society for Matrix Biology","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — live imaging with super-resolution capability, FRAP, genetic perturbation of RDEL signal, and pharmacological manipulation in single lab with multiple orthogonal approaches","pmids":["32562852"],"is_preprint":false},{"year":2020,"finding":"Hsp47 expression induces mesenchymal phenotypes in mammary epithelial cells, enhances platelet recruitment to cancer cells, and promotes lung retention and colonization of circulating tumor cells. Type I collagen was identified as the key mediator of Hsp47-induced cancer cell-platelet interaction by rescue experiments and functional blocking antibodies. Hsp47-dependent collagen deposition facilitated cancer cell clustering and extravasation.","method":"Hsp47 overexpression in MECs, platelet depletion in vivo, functional blocking antibodies against type I collagen, rescue experiments, lung retention assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal in vitro and in vivo approaches with rescue experiments identifying specific molecular mediator (type I collagen), single lab","pmids":["32015106"],"is_preprint":false},{"year":2020,"finding":"HSP47 ablation does not majorly impact collagen VI secretion but specifically impairs its lateral assembly. In keratinocytes, Hsp47 ablation impairs transmembrane collagen XVII triple-helix formation at the C-terminus; application of recombinant HSP47 to isolated Hsp47-null keratinocyte membrane vesicles fully restores collagen XVII C-terminal folding. HSP47 also binds the N-terminal region of procollagen I and is essential for its secretion.","method":"HSP47 ablation in murine keratinocytes (specific Cre), membrane vesicle isolation, application of recombinant HSP47, electron microscopy, collagen secretion/assembly assays","journal":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — reconstitution experiment (recombinant HSP47 restoring folding in null vesicles) combined with cell-specific knockout and multiple collagen substrate analyses, single lab","pmids":["32716577"],"is_preprint":false},{"year":2021,"finding":"Collagen's primary structure determines the stoichiometry of the HSP47:collagen complex. Many predicted binding sites have low affinity due to negatively charged flanking amino acids, while large hydrophobic residues (Phe, Leu) at certain positions increase binding strength. Crystal structures of HSP47 bound to Phe- or Leu-containing collagen peptides reveal conformational rearrangements at the binding site and a 1:1 (rather than 2:1) complex stoichiometry due to steric clashes caused by the large hydrophobic side chain on the trailing strand.","method":"Collagen II peptide library binding assays, X-ray crystallography of HSP47-peptide complexes, molecular modeling","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure combined with systematic peptide library affinity measurements, single lab but multiple orthogonal methods","pmids":["34487762"],"is_preprint":false},{"year":2021,"finding":"Mapping HSP47 binding sites on native collagen types II and III using collagen toolkit peptide ELISA revealed that HSP47 binds only a few GXR motifs, with most high-affinity binding sites near the N-terminal part of the triple-helical region. Molecular modelling showed flanking residues beyond the key Arg also determine binding affinity. Two novel small-molecule HSP47-collagen interaction inhibitors were identified by virtual screening targeting the Arg binding site.","method":"ELISA binding assay with collagen toolkit synthetic peptides, molecular modeling, binding energy calculation, virtual screening, bioassay of inhibitor candidates","journal":"Biomolecules","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — systematic peptide library ELISA defining native binding sites, molecular modeling validation, single lab","pmids":["34356607"],"is_preprint":false},{"year":2024,"finding":"HSP47-mediated collagen deposition in brain metastatic niches promotes microglial polarization to the M2 phenotype via the α2β1 integrin/NF-κB pathway, upregulating anti-inflammatory cytokines and repressing CD8+ T cell anti-tumor responses. Microglial depletion reverses HSP47-induced CD8+ T cell inactivation and abolishes brain metastasis.","method":"HSP47 overexpression/knockdown in tumor cells, microglial depletion experiments, integrin blocking, NF-κB pathway analysis, CD8+ T cell functional assays, in vivo brain metastasis models","journal":"Cell reports. Medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple in vivo perturbations (HSP47 modulation, microglial depletion, integrin blocking) with immune readouts, single lab","pmids":["38744278"],"is_preprint":false},{"year":1999,"finding":"On the surface of tumor cells, Hsp47 (colligin) associates with the tetraspanin protein CD9 in a membrane complex. Cell lines with constitutively high surface Hsp47 showed the lowest invasion and migration indices; incorporation of anti-Hsp47 antibodies into migration assays increased invasion indices, suggesting surface Hsp47 moderates tumor cell invasion.","method":"Protein cross-linking followed by immunoprecipitation, cytometric analysis, Boyden chamber invasion assay, colloidal gold migration assay","journal":"Journal of cellular biochemistry","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single co-IP after chemical crosslinking, single lab, functional correlation without direct mechanistic dissection","pmids":["10227388"],"is_preprint":false},{"year":2021,"finding":"HSP47 promotes angiogenesis in bladder cancer by activating the ERK pathway and inducing CCL2 expression. HSP47 downregulation suppresses angiogenesis in vitro and in vivo.","method":"HSP47 knockdown/overexpression, ERK pathway inhibition, CCL2 measurement, angiogenesis assays, correlation with clinical samples","journal":"Cellular signalling","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, pathway inhibition and gene knockdown with angiogenesis readout but limited mechanistic dissection of how HSP47 activates ERK/CCL2","pmids":["34000383"],"is_preprint":false}],"current_model":"SERPINH1/HSP47 is an ER-resident collagen-specific molecular chaperone that recognizes the folded triple-helical conformation of procollagens by binding Gly-Xaa-Arg motifs via a conserved aspartic acid, stabilizes thermally labile elongating triple helices at body temperature, prevents procollagen overmodification and aggregation in the ER, sorts from procollagen at ER exit sites before transport vesicle formation, and releases its substrate in a pH-dependent manner (mediated by a histidine cluster) in the cis-Golgi/ERGIC before being retrieved to the ER via its C-terminal RDEL signal; in platelets, surface-localized HSP47 directly interacts with collagen to enhance GPVI signaling and thrombosis, while in myofibroblasts it is the primary driver of tissue fibrosis by enabling fibrillar collagen secretion."},"narrative":{"mechanistic_narrative":"SERPINH1/HSP47 is an ER-resident, collagen-specific molecular chaperone that recognizes the folded triple-helical conformation of procollagens and stabilizes the thermally labile elongating triple helix at body temperature [PMID:16484215, PMID:31758055]. Although it belongs to the serpin superfamily, it lacks the active-site residues for serine protease inhibition and instead carries a C-terminal RDEL ER-retention signal that recycles it to the ER [PMID:2072906]. HSP47 recognizes its substrate by binding Arg at the Yaa position of Gly-Xaa-Arg triplets through a conserved aspartic acid, with two molecules engaging a single collagen triple helix head-to-head; collagen primary structure and flanking residues tune affinity and complex stoichiometry [PMID:16484215, PMID:22847422, PMID:34487762, PMID:34356607]. By binding the assembling helix it prevents post-translational overmodification and aggregation and times procollagen secretion, while a histidine cluster provides the structural basis for pH-dependent substrate release in the cis-Golgi/ERGIC [PMID:9722680, PMID:22847422, PMID:31758055]. Live imaging localizes HSP47/procollagen sorting to ER exit sites, with HSP47 excluded from the transport carriers that export procollagen [PMID:32562852]. HSP47 is required for the folding, assembly, and secretion of multiple collagen types — I, II, III, IV, VI, and the transmembrane collagen XVII — acting in concert with other ER folding factors including cyclophilin B, BiP/GRP94, and FKBP65 [PMID:7629154, PMID:8834444, PMID:22492985, PMID:32716577, PMID:25510505]. Loss of HSP47 function causes intracellular procollagen retention, ER stress, and collagen overmodification, and a missense SERPINH1 mutation causes autosomal recessive osteogenesis imperfecta [PMID:19629171, PMID:26004778]. Beyond its biosynthetic role, HSP47 is the principal driver of myofibroblast-dependent tissue fibrosis by enabling fibrillar collagen deposition, is induced by TGF-β1/Smad2/3 signaling, and acts at the cell surface in platelets to enhance GPVI-collagen signaling and thrombosis; in cancer it promotes collagen-dependent platelet recruitment, metastatic colonization, and an immunosuppressive niche [PMID:29512284, PMID:31393098, PMID:31664133, PMID:32015106, PMID:38744278].","teleology":[{"year":1991,"claim":"Established the molecular identity of HSP47 as a heat-inducible, ER-retained member of the serpin family that lacks protease-inhibitory activity, framing it as a chaperone rather than an enzyme.","evidence":"cDNA cloning, sequence homology analysis, and nuclear run-on assays","pmids":["2072906"],"confidence":"High","gaps":["Substrate specificity not yet defined","No direct demonstration of chaperone activity"]},{"year":1995,"claim":"Showed HSP47 stays bound to procollagen from ER into pre-Golgi intermediates and that its release tracks triple-helix maturation, linking HSP47 dissociation to collagen folding state.","evidence":"pulse-chase, reciprocal immunoprecipitation, and pharmacological trafficking inhibition; complemented by co-IP showing HSP47/BiP/GRP94 heteromeric complexes on collagen IV (1996)","pmids":["7629154","8834444"],"confidence":"Medium","gaps":["Release trigger not molecularly defined","Single-lab co-IP evidence for chaperone complexes"]},{"year":1998,"claim":"Demonstrated functionally that HSP47 delays procollagen III secretion and prevents backbone overmodification, defining its quality-control role in the secretory pathway.","evidence":"heterologous reconstitution in 293 cells with cross-link co-IP, secretion and thermal stability assays","pmids":["9722680"],"confidence":"Medium","gaps":["Recognition motif still unknown","Single heterologous system"]},{"year":2006,"claim":"Defined the molecular recognition code: HSP47 reads Arg at the Yaa position of Gly-Xaa-Arg triplets plus the Yaa-3 residue on the same strand, explaining triple-helix specificity.","evidence":"systematic synthetic collagen-model peptide binding and competition assays","pmids":["16484215"],"confidence":"High","gaps":["Structural basis of recognition not yet resolved","Native collagen binding-site distribution unknown"]},{"year":2009,"claim":"Established SERPINH1 as a disease gene by linking a conserved-domain missense mutation to autosomal recessive osteogenesis imperfecta.","evidence":"homozygosity mapping and candidate-gene analysis in affected Dachshunds","pmids":["19629171"],"confidence":"High","gaps":["Cellular consequence of the mutation not yet defined","Animal model only at this stage"]},{"year":2012,"claim":"Provided the structural mechanism: crystal structures showed two HSP47 molecules bind a triple helix head-to-head via a conserved aspartate engaging the key Arg, and a histidine cluster rationalizes pH-dependent release.","evidence":"X-ray crystallography of free HSP47 and HSP47-collagen peptide complexes; genetic ablation in chondrocytes (Col2a1-Cre) establishing requirement for type II/XI procollagen folding","pmids":["22847422","22492985"],"confidence":"High","gaps":["pH-release model not directly tested in cells","Stoichiometry on native heterotrimeric collagens unresolved"]},{"year":2015,"claim":"Connected HSP47 dysfunction to a shared OI pathway with FKBP65 and dissected the cellular pathology of the OI mutation (ER retention, ER stress, collagen overmodification).","evidence":"patient/mutant fibroblast biochemistry, co-IP, immunofluorescence, mass spectrometry, ER-stress immunoblotting in the Dachshund model","pmids":["25510505","26004778"],"confidence":"Medium","gaps":["Direct vs. secondary nature of FKBP65 disruption needs further dissection","Single-lab co-IP for HSP47-FKBP65 interaction"]},{"year":2019,"claim":"Demonstrated the essential chaperone function is thermal stabilization of the elongating triple helix: lowering temperature to 33°C fully rescued the procollagen defects of HSP47-null fibroblasts.","evidence":"temperature-rescue experiments in hsp47-null MEFs with modification and secretion assays","pmids":["31758055"],"confidence":"High","gaps":["Does not address sorting/release steps","Single-lab study"]},{"year":2019,"claim":"Established HSP47 as the dominant cell-autonomous driver of myofibroblast-mediated fibrosis downstream of TGF-β1/Smad2/3, required for fibrillar collagen deposition and scar formation.","evidence":"myofibroblast/cardiomyocyte/endothelial cell-specific conditional knockouts in pressure-overload and MI models; TGF-β1/Smad pathway and functional fibroblast assays; therapeutic siRNA in vocal fold scar","pmids":["31393098","31664133","31100613"],"confidence":"High","gaps":["Mechanism coupling collagen secretion to myofibroblast proliferation unclear","Human in vivo efficacy of HSP47 silencing not established"]},{"year":2020,"claim":"Refined the trafficking model, showing procollagen and HSP47 sort at ER exit sites with HSP47 excluded from export carriers, correcting prior interpretations of HSP47/procollagen puncta.","evidence":"live-cell super-resolution imaging, FRAP, ARF1 inhibition, RDEL-deletion, ERGIC53 colocalization","pmids":["32562852"],"confidence":"High","gaps":["Molecular machinery sorting HSP47 away from procollagen at ERES unidentified","Timing relative to pH-dependent release not integrated"]},{"year":2020,"claim":"Expanded the substrate range and mechanism, showing HSP47 is needed for assembly of collagens VI and XVII and for procollagen I secretion via direct N-terminal binding, with recombinant HSP47 rescuing folding in null membranes.","evidence":"keratinocyte-specific knockout, isolated membrane vesicle reconstitution with recombinant HSP47, EM and assembly assays","pmids":["32716577"],"confidence":"High","gaps":["Assembly vs. secretion roles differ by collagen type and not fully reconciled","Single-lab reconstitution"]},{"year":2021,"claim":"Refined the recognition rules at structural resolution, showing flanking hydrophobic residues alter binding affinity and switch HSP47:collagen stoichiometry from 2:1 to 1:1, and mapped sparse native binding sites clustered near the collagen N-terminus.","evidence":"collagen peptide library binding/ELISA, X-ray crystallography of HSP47-Phe/Leu peptide complexes, molecular modeling and virtual inhibitor screening","pmids":["34487762","34356607"],"confidence":"High","gaps":["Functional consequence of variable stoichiometry in cells unknown","Inhibitor efficacy in vivo not established"]},{"year":2020,"claim":"Defined extracellular/surface roles of HSP47 in platelet collagen signaling and cancer metastasis, mediated by type I collagen and platelet recruitment.","evidence":"platelet-specific Hsp47 knockout with flow/thrombosis assays; Hsp47 overexpression in MECs with collagen-blocking antibody and platelet depletion; integrin/NF-κB and microglia studies in brain metastasis","pmids":["29512284","32015106","38744278"],"confidence":"High","gaps":["Mechanism of HSP47 export to the cell surface despite RDEL signal unresolved","Some downstream tumor signaling (ERK/CCL2) only low-confidence"]},{"year":null,"claim":"How HSP47 reaches the platelet and cancer cell surface despite its RDEL ER-retention signal, and how surface/extracellular HSP47 functionally relates to its canonical ER chaperone role, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No trafficking mechanism for surface localization identified","Relationship between intracellular chaperone and extracellular signaling activities undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0044183","term_label":"protein folding chaperone","supporting_discovery_ids":[3,18,21]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[5,7,21]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[5,7,22]}],"localization":[{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[0,1,18,19]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[14,25]}],"pathway":[{"term_id":"R-HSA-1474244","term_label":"Extracellular matrix organization","supporting_discovery_ids":[8,15,21]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[3,18,19]},{"term_id":"R-HSA-109582","term_label":"Hemostasis","supporting_discovery_ids":[14]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[6,10]}],"complexes":[],"partners":["COL1A1","COL2A1","COL3A1","FKBP10","PPIB","HSPA5","GP6","CD9"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P50454","full_name":"Serpin H1","aliases":["47 kDa heat shock protein","Arsenic-transactivated protein 3","AsTP3","Cell proliferation-inducing gene 14 protein","Collagen-binding protein","Colligin","Rheumatoid arthritis-related antigen RA-A47"],"length_aa":418,"mass_kda":46.4,"function":"Binds specifically to collagen. Could be involved as a chaperone in the biosynthetic pathway of collagen","subcellular_location":"Endoplasmic reticulum lumen","url":"https://www.uniprot.org/uniprotkb/P50454/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SERPINH1","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"ARF4","stoichiometry":4.0},{"gene":"CANX","stoichiometry":0.2},{"gene":"COPB2","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/SERPINH1","total_profiled":1310},"omim":[{"mim_id":"613848","title":"OSTEOGENESIS IMPERFECTA, TYPE X; OI10","url":"https://www.omim.org/entry/613848"},{"mim_id":"610504","title":"PRETERM PREMATURE RUPTURE OF THE MEMBRANES; PPROM","url":"https://www.omim.org/entry/610504"},{"mim_id":"609024","title":"KDEL ENDOPLASMIC RETICULUM PROTEIN RETENTION RECEPTOR 2; 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Greece)","url":"https://pubmed.ncbi.nlm.nih.gov/9067768","citation_count":19,"is_preprint":false},{"pmid":"31758055","id":"PMC_31758055","title":"Lowering the culture temperature corrects collagen abnormalities caused by HSP47 gene knockout.","date":"2019","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/31758055","citation_count":19,"is_preprint":false},{"pmid":"7656593","id":"PMC_7656593","title":"Isolation, characterization and chromosomal assignment of human colligin-2 gene (CBP2).","date":"1995","source":"Cytogenetics and cell genetics","url":"https://pubmed.ncbi.nlm.nih.gov/7656593","citation_count":18,"is_preprint":false},{"pmid":"12102417","id":"PMC_12102417","title":"Collagen-binding heat shock protein HSP47 expression during healing of fetal skin wounds.","date":"2002","source":"International journal of oral and maxillofacial surgery","url":"https://pubmed.ncbi.nlm.nih.gov/12102417","citation_count":18,"is_preprint":false},{"pmid":"35118144","id":"PMC_35118144","title":"MiR-29a Increase in Aging May Function as a Compensatory Mechanism Against Cardiac Fibrosis Through SERPINH1 Downregulation.","date":"2022","source":"Frontiers in cardiovascular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/35118144","citation_count":18,"is_preprint":false},{"pmid":"35082674","id":"PMC_35082674","title":"Hsp47 Inhibitor Col003 Attenuates Collagen-Induced Platelet Activation and Cerebral Ischemic-Reperfusion Injury in Rats.","date":"2022","source":"Frontiers in pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/35082674","citation_count":17,"is_preprint":false},{"pmid":"2150347","id":"PMC_2150347","title":"CBP1 function is required for stability of a hybrid cob-oli1 transcript in yeast mitochondria.","date":"1990","source":"Current genetics","url":"https://pubmed.ncbi.nlm.nih.gov/2150347","citation_count":17,"is_preprint":false},{"pmid":"10842320","id":"PMC_10842320","title":"Binding motifs of CBP2 a potential cell surface target for carcinoma cells.","date":"2000","source":"Journal of cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/10842320","citation_count":17,"is_preprint":false},{"pmid":"10896781","id":"PMC_10896781","title":"CBP1 associates with the Dictyostelium cytoskeleton and is important for normal cell aggregation under certain developmental conditions.","date":"2000","source":"Experimental cell research","url":"https://pubmed.ncbi.nlm.nih.gov/10896781","citation_count":17,"is_preprint":false},{"pmid":"36104825","id":"PMC_36104825","title":"H19 may regulate the immune cell infiltration in carcinogenesis of gastric cancer through miR-378a-5p/SERPINH1 signaling.","date":"2022","source":"World journal of surgical oncology","url":"https://pubmed.ncbi.nlm.nih.gov/36104825","citation_count":17,"is_preprint":false},{"pmid":"32716577","id":"PMC_32716577","title":"New specific HSP47 functions in collagen subfamily chaperoning.","date":"2020","source":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/32716577","citation_count":17,"is_preprint":false},{"pmid":"36206860","id":"PMC_36206860","title":"MicroRNA-29a inhibits collagen expression and induces apoptosis in human fetal scleral fibroblasts by targeting the Hsp47/Smad3 signaling pathway.","date":"2022","source":"Experimental eye research","url":"https://pubmed.ncbi.nlm.nih.gov/36206860","citation_count":17,"is_preprint":false},{"pmid":"8944545","id":"PMC_8944545","title":"Expression of 47 kDa heat shock protein (HSP47) during development of mouse cornea.","date":"1996","source":"Experimental eye 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mechanisms","url":"https://pubmed.ncbi.nlm.nih.gov/17054723","citation_count":15,"is_preprint":false},{"pmid":"18205191","id":"PMC_18205191","title":"A 12-bp deletion in the 5'-flanking region of the SERPINH1 gene affects promoter activity and protects against preterm premature rupture of membranes in African Americans.","date":"2008","source":"Human mutation","url":"https://pubmed.ncbi.nlm.nih.gov/18205191","citation_count":15,"is_preprint":false},{"pmid":"35318667","id":"PMC_35318667","title":"A CCaMK/Cyclops response element in the promoter of Lotus japonicus calcium-binding protein 1 (CBP1) mediates transcriptional activation in root symbioses.","date":"2022","source":"The New phytologist","url":"https://pubmed.ncbi.nlm.nih.gov/35318667","citation_count":14,"is_preprint":false},{"pmid":"34487762","id":"PMC_34487762","title":"Collagen's primary structure determines collagen:HSP47 complex stoichiometry.","date":"2021","source":"The Journal of biological 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surgeon","url":"https://pubmed.ncbi.nlm.nih.gov/21412710","citation_count":14,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":47899,"output_tokens":6997,"usd":0.124326,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":16274,"output_tokens":4489,"usd":0.096797,"stage2_stop_reason":"end_turn"},"total_usd":0.221123,"stage1_batch_id":"msgbatch_013LWZZT6MWaqB9qyTSeQBmU","stage2_batch_id":"msgbatch_0194ZzQaTGNpruoNJBbEMbt3","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1991,\n      \"finding\": \"HSP47 (SERPINH1) contains a C-terminal RDEL sequence functioning as an ER-retention signal, belongs to the serpin superfamily but lacks the active site required for serine protease inhibition, and is transcriptionally regulated by heat shock elements in its promoter. Its suppression after Rous sarcoma virus transformation is regulated at the transcriptional level.\",\n      \"method\": \"cDNA cloning, Northern blot, nuclear run-on assay, amino acid sequence homology analysis\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — direct molecular cloning with functional domain identification, sequence analysis establishing ER-retention signal and serpin membership, replicated across multiple labs subsequently\",\n      \"pmids\": [\"2072906\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"HSP47 and cyclophilin B remain associated with procollagen I as it traverses from the ER into pre-Golgi intermediate vesicles. Cyclosporin A treatment diminished CyPB bound to procollagen and slowed the rate of HSP47 release from procollagen and the rate of procollagen secretion, suggesting HSP47 release is coupled to triple-helix formation.\",\n      \"method\": \"Pulse-chase metabolic labeling, immunoprecipitation, immunofluorescence, pharmacological inhibition of G proteins and vesicular trafficking\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal immunoprecipitation with pharmacological perturbations in a single lab, two orthogonal methods\",\n      \"pmids\": [\"7629154\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"Hsp47, GRP78 (BiP), and GRP94 form heteromeric complexes with each other and with nascent chains of collagen type IV in the ER. ATP depletion increased the association of newly synthesized collagen IV with all three chaperones simultaneously.\",\n      \"method\": \"Co-immunoprecipitation in mouse teratocarcinoma cells, ATP depletion experiments\",\n      \"journal\": \"Connective tissue research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — single lab, single co-IP method, but replicated across multiple chaperones and conditions\",\n      \"pmids\": [\"8834444\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"HSP47 transiently binds to procollagen III in the ER (confirmed by chemical cross-linking immunoprecipitation), delays secretion of type III procollagen, and prevents overmodification of procollagen chains. In cells expressing HSP47, the electrophoretic mobility and melting temperature of type III procollagen matched those of normal collagen-producing cells, indicating HSP47 prevents overmodification of the procollagen backbone.\",\n      \"method\": \"Stable transfection of 293 cells with procollagen III ± HSP47, chemical cross-linking (DSP) immunoprecipitation, pulse-chase secretion assays, thermal stability measurements\",\n      \"journal\": \"Journal of biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reconstitution in heterologous system with chemical cross-link co-IP and functional readout (secretion rate, thermal stability), single lab\",\n      \"pmids\": [\"9722680\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Recombinant mouse Hsp47 exists as both a structurally mesostable monomer (with a 5-strand A-sheet) and a hyperstable trimer; both states have biological activity. Hsp47 can bind a monomeric, partially folded collagen mimic peptide (PPG)10 and induce it to adopt a polyproline type II conformation, promoting higher-order assembly similar to collagen-like structures. The peptide-binding site does not reside in strand 4 of sheet A.\",\n      \"method\": \"Biophysical analysis of recombinant mouse Hsp47 including circular dichroism, analytical ultracentrifugation, peptide-binding assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — in vitro reconstitution and biophysical characterization but single lab\",\n      \"pmids\": [\"11592970\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"HSP47 specifically recognizes the collagen triple helix by binding Arg residues at the Yaa position (Arg0) of Gly-Xaa-Arg triplets, and also contacts the residue at the Yaa-3 position on the same peptide strand. Maximal binding affinity occurs when Yaa-3 is Thr. The two key residues must be on the same strand of the triple helix for recognition by HSP47.\",\n      \"method\": \"Binding assays with synthetic heterotrimeric collagen-model peptides with systematic amino-acid substitutions, competitive inhibition assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — systematic in vitro peptide library approach with structure-activity relationships, findings later confirmed by crystal structures in independent labs\",\n      \"pmids\": [\"16484215\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"A missense mutation in SERPINH1 (c.977C>T, p.L326P) in an evolutionarily conserved domain causes autosomal recessive osteogenesis imperfecta in Dachshunds, establishing SERPINH1 as a causative OI gene (the fifth identified).\",\n      \"method\": \"Homozygosity mapping with SNP chip, haplotype analysis, candidate gene mutation analysis in affected vs. control Dachshunds\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic mapping with perfect phenotypic association, replicated across multiple affected and carrier animals\",\n      \"pmids\": [\"19629171\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Crystal structures of Hsp47 free and in complex with homotrimeric synthetic collagen model peptides reveal that two Hsp47 molecules bind head-to-head to a collagen triple helix, each occupying one of two Arg-containing binding sites. A conserved aspartic acid on Hsp47 recognizes the key arginine in the Xaa-Arg-Gly triplet. A cluster of histidine residues in the structure provides the structural basis for pH-dependent substrate release in cis-Golgi/ERGIC. The structures explain triple-helix stabilization and inhibition of collagen-bundle formation by Hsp47.\",\n      \"method\": \"X-ray crystallography of Hsp47 alone and in complex with synthetic collagen peptides\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure with mechanistic interpretation, multiple peptide complexes resolved, independently consistent with biochemical data from multiple labs\",\n      \"pmids\": [\"22847422\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Conditional knockout of Hsp47 specifically in chondrocytes (Col2a1-Cre) causes severe chondrodysplasia with reduced type II and XI collagen levels, accumulation of misaligned type I collagen, and loss of type II collagen fibers. This establishes Hsp47 as indispensable for correct folding of type II and type XI procollagens and for cartilage/endochondral bone formation.\",\n      \"method\": \"Conditional gene knockout (Hsp47 floxed × Col2a1-Cre), second-harmonic generation analysis, electron microscopy, immunohistochemistry, skeletal staining\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — cell-type-specific genetic ablation with multiple orthogonal structural readouts, unambiguous phenotype\",\n      \"pmids\": [\"22492985\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"HSP47 and FKBP65 cooperate in posttranslational maturation of type I procollagen. An OI-causing SERPINH1 mutation destabilizes and mislocalizes HSP47, secondarily disrupting FKBP65 localization and preventing normal HSP47-FKBP65 interaction, revealing a common cellular pathway for OI caused by HSP47 and FKBP65 deficiency.\",\n      \"method\": \"Patient fibroblast biochemical assays, immunofluorescence localization, co-immunoprecipitation, analysis of procollagen processing\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — patient-derived cells with co-IP and localization, single lab, two orthogonal methods\",\n      \"pmids\": [\"25510505\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"In the Dachshund OI model (HSP47 L326P mutation), HSP47 chaperone function is impaired in the ER, leading to intracellular procollagen retention with ER dilation and activation of ER stress markers (GRP78, phospho-eIF2α), post-translational overmodification of type I collagen chains, and higher pyridinoline crosslink content in bone collagen.\",\n      \"method\": \"Biochemical assays on mutant and control skin fibroblasts and bone, SDS-PAGE electrophoretic mobility analysis, tandem mass spectrometry, electron microscopy, ER stress marker immunoblotting\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — multiple orthogonal biochemical methods (MS, SDS-PAGE, EM, immunoblot) on natural disease model, single lab\",\n      \"pmids\": [\"26004778\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Hsp47 silencing in breast cancer cells reprogrammed them to form growth-arrested and non-invasive structures in 3D cultures and reduced collagen and fibronectin deposition. miR-29b and miR-29c directly repress Hsp47 expression along with multiple ECM network genes. Ectopic expression of miR-29b suppressed malignant phenotypes.\",\n      \"method\": \"Hsp47 siRNA knockdown in 3D culture and xenograft assays, coexpression network analysis, miRNA overexpression, luciferase reporter assays for miR-29 targeting\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional knockdown with phenotypic readout in 3D and in vivo, plus direct miRNA target validation, single lab\",\n      \"pmids\": [\"25744716\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"In zebrafish fin regeneration, serpinh1b (Hsp47) acts downstream of the gap junction protein Cx43 to regulate collagen-based actinotrichia organization, cell proliferation, and joint formation. Knockdown of Hsp47 recapitulates the short-fin phenotype with reduced fin/segment length and disrupted actinotrichia.\",\n      \"method\": \"Morpholino knockdown in zebrafish regenerating fin, short fin (sof) mutant analysis, epistasis experiments\",\n      \"journal\": \"Mechanisms of development\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis by morpholino knockdown in zebrafish model with clear phenotypic readout, single lab\",\n      \"pmids\": [\"26103547\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"SERPINH1 is a direct target of miR-29a as validated by luciferase reporter assay. miR-29a restoration suppressed cancer cell aggressiveness and fibroblast migration in lung cancer cells.\",\n      \"method\": \"Luciferase reporter assay for direct miRNA targeting, miR-29a restoration experiments in lung cancer cells and lung fibroblasts\",\n      \"journal\": \"Journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — direct target validation by reporter assay, but single lab, single method for the mechanistic claim\",\n      \"pmids\": [\"27488440\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"HSP47 is present on the platelet surface where it binds collagen and modulates GPVI-collagen interaction. Deletion or inhibition of HSP47 in platelets specifically reduces collagen-induced (but not thrombin-induced) platelet activation, GPVI signaling, thrombus formation under arterial flow, and in vivo thrombosis in cremaster arterioles.\",\n      \"method\": \"Platelet-specific Hsp47 knockout mouse, flow-based thrombus assays, GPVI-collagen binding assays, laser-induced thrombosis, tail bleeding time\",\n      \"journal\": \"Journal of thrombosis and haemostasis : JTH\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — cell-type-specific knockout with multiple orthogonal functional assays (in vitro binding, flow assay, in vivo thrombosis), clear mechanistic specificity (collagen vs. thrombin responses)\",\n      \"pmids\": [\"29512284\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Myofibroblast-specific ablation of Hsp47 blocks cardiac fibrosis and deposition of collagens type I, III, and V after pressure overload and reduces cardiac hypertrophy. Cardiomyocyte- or endothelial-specific deletion of Hsp47 has no effect on cardiac fibrosis. Fibroblast-specific Hsp47 deletion causes lethality after myocardial infarction due to failed scar formation and ventricular wall rupture. Deletion of Hsp47 from myofibroblasts reduced fibrillar collagen mRNA and attenuated myofibroblast proliferation without affecting paracrine secretory activity.\",\n      \"method\": \"Cell-type-specific conditional knockout (myofibroblast, cardiomyocyte, endothelial cell-specific Cre lines), pressure overload and MI models, histological fibrosis assessment, mRNA analysis\",\n      \"journal\": \"JCI insight\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple cell-type-specific knockouts with orthogonal injury models and clear mechanistic specificity between cell types\",\n      \"pmids\": [\"31393098\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Knockdown of Serpinh1 using siRNA in fibrotic vocal fold mucosa reversed scar-associated collagen accumulation within 4 weeks. Transcriptome analysis showed evidence of cell cycle upregulation, catabolism, matrix disassembly, and morphogenesis as therapeutic outcomes.\",\n      \"method\": \"Liposome-mediated siRNA delivery in vitro (naive and scar fibroblasts) and in vivo (rat VF mucosa), transcriptome analysis\",\n      \"journal\": \"Molecular therapy. Nucleic acids\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo knockdown with transcriptomic phenotype readout, single lab, two orthogonal methods\",\n      \"pmids\": [\"31100613\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"TGF-β1-induced HSP47 expression in nasal fibroblasts occurs via the Smad2/3 signaling pathway, and HSP47 is required for TGF-β1-induced myofibroblast differentiation, ECM production, fibroblast migration and contraction.\",\n      \"method\": \"siRNA knockdown of HSP47, Smad2/3 pathway inhibitor experiments, migration and collagen gel contraction assays, immunofluorescence, western blotting\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA knockdown with pathway inhibition and multiple functional readouts, single lab\",\n      \"pmids\": [\"31664133\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Lowering culture temperature to 33°C corrects all procollagen biosynthesis defects in hsp47-/- fibroblasts, including ER accumulation, over-modification (prolyl/lysyl hydroxylation and glycosylation), and secretion of type I collagen homotrimer. This demonstrates that the essential function of HSP47 is to stabilize the elongating, thermally unstable triple helix of procollagen at body temperature.\",\n      \"method\": \"hsp47-null mouse embryo fibroblasts cultured at 37°C vs. 33°C, procollagen modification analysis, secretion assays, ER accumulation assessment\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — genetic null system with temperature-rescue experiment providing direct mechanistic insight, multiple biochemical readouts, single lab\",\n      \"pmids\": [\"31758055\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Live cell imaging with fluorescently tagged procollagen and HSP47 demonstrated that bona fide ER-to-Golgi transport carriers delivering procollagen contain no HSP47 (unless HSP47's RDEL ER-retention signal is deleted). Procollagen co-localizes with HSP47 and ERGIC53 at ER exit sites (ERESs), but co-localizes with ERGIC53 without HSP47 in Golgi-bound transport intermediates. Previously reported HSP47/procollagen puncta were identified as dilated ER regions, ERESs, or autophagic structures rather than transport vesicles. This indicates procollagen and HSP47 sorting occurs at ERES before ER export.\",\n      \"method\": \"Live cell fluorescence imaging with up to 120 nm spatial / 500 ms time resolution, FRAP, ARF1 inhibition, deletion of RDEL signal, colocalization with ERGIC53 and lysosomal markers\",\n      \"journal\": \"Matrix biology : journal of the International Society for Matrix Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — live imaging with super-resolution capability, FRAP, genetic perturbation of RDEL signal, and pharmacological manipulation in single lab with multiple orthogonal approaches\",\n      \"pmids\": [\"32562852\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Hsp47 expression induces mesenchymal phenotypes in mammary epithelial cells, enhances platelet recruitment to cancer cells, and promotes lung retention and colonization of circulating tumor cells. Type I collagen was identified as the key mediator of Hsp47-induced cancer cell-platelet interaction by rescue experiments and functional blocking antibodies. Hsp47-dependent collagen deposition facilitated cancer cell clustering and extravasation.\",\n      \"method\": \"Hsp47 overexpression in MECs, platelet depletion in vivo, functional blocking antibodies against type I collagen, rescue experiments, lung retention assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal in vitro and in vivo approaches with rescue experiments identifying specific molecular mediator (type I collagen), single lab\",\n      \"pmids\": [\"32015106\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"HSP47 ablation does not majorly impact collagen VI secretion but specifically impairs its lateral assembly. In keratinocytes, Hsp47 ablation impairs transmembrane collagen XVII triple-helix formation at the C-terminus; application of recombinant HSP47 to isolated Hsp47-null keratinocyte membrane vesicles fully restores collagen XVII C-terminal folding. HSP47 also binds the N-terminal region of procollagen I and is essential for its secretion.\",\n      \"method\": \"HSP47 ablation in murine keratinocytes (specific Cre), membrane vesicle isolation, application of recombinant HSP47, electron microscopy, collagen secretion/assembly assays\",\n      \"journal\": \"FASEB journal : official publication of the Federation of American Societies for Experimental Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — reconstitution experiment (recombinant HSP47 restoring folding in null vesicles) combined with cell-specific knockout and multiple collagen substrate analyses, single lab\",\n      \"pmids\": [\"32716577\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Collagen's primary structure determines the stoichiometry of the HSP47:collagen complex. Many predicted binding sites have low affinity due to negatively charged flanking amino acids, while large hydrophobic residues (Phe, Leu) at certain positions increase binding strength. Crystal structures of HSP47 bound to Phe- or Leu-containing collagen peptides reveal conformational rearrangements at the binding site and a 1:1 (rather than 2:1) complex stoichiometry due to steric clashes caused by the large hydrophobic side chain on the trailing strand.\",\n      \"method\": \"Collagen II peptide library binding assays, X-ray crystallography of HSP47-peptide complexes, molecular modeling\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure combined with systematic peptide library affinity measurements, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"34487762\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Mapping HSP47 binding sites on native collagen types II and III using collagen toolkit peptide ELISA revealed that HSP47 binds only a few GXR motifs, with most high-affinity binding sites near the N-terminal part of the triple-helical region. Molecular modelling showed flanking residues beyond the key Arg also determine binding affinity. Two novel small-molecule HSP47-collagen interaction inhibitors were identified by virtual screening targeting the Arg binding site.\",\n      \"method\": \"ELISA binding assay with collagen toolkit synthetic peptides, molecular modeling, binding energy calculation, virtual screening, bioassay of inhibitor candidates\",\n      \"journal\": \"Biomolecules\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — systematic peptide library ELISA defining native binding sites, molecular modeling validation, single lab\",\n      \"pmids\": [\"34356607\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"HSP47-mediated collagen deposition in brain metastatic niches promotes microglial polarization to the M2 phenotype via the α2β1 integrin/NF-κB pathway, upregulating anti-inflammatory cytokines and repressing CD8+ T cell anti-tumor responses. Microglial depletion reverses HSP47-induced CD8+ T cell inactivation and abolishes brain metastasis.\",\n      \"method\": \"HSP47 overexpression/knockdown in tumor cells, microglial depletion experiments, integrin blocking, NF-κB pathway analysis, CD8+ T cell functional assays, in vivo brain metastasis models\",\n      \"journal\": \"Cell reports. Medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple in vivo perturbations (HSP47 modulation, microglial depletion, integrin blocking) with immune readouts, single lab\",\n      \"pmids\": [\"38744278\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"On the surface of tumor cells, Hsp47 (colligin) associates with the tetraspanin protein CD9 in a membrane complex. Cell lines with constitutively high surface Hsp47 showed the lowest invasion and migration indices; incorporation of anti-Hsp47 antibodies into migration assays increased invasion indices, suggesting surface Hsp47 moderates tumor cell invasion.\",\n      \"method\": \"Protein cross-linking followed by immunoprecipitation, cytometric analysis, Boyden chamber invasion assay, colloidal gold migration assay\",\n      \"journal\": \"Journal of cellular biochemistry\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single co-IP after chemical crosslinking, single lab, functional correlation without direct mechanistic dissection\",\n      \"pmids\": [\"10227388\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"HSP47 promotes angiogenesis in bladder cancer by activating the ERK pathway and inducing CCL2 expression. HSP47 downregulation suppresses angiogenesis in vitro and in vivo.\",\n      \"method\": \"HSP47 knockdown/overexpression, ERK pathway inhibition, CCL2 measurement, angiogenesis assays, correlation with clinical samples\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, pathway inhibition and gene knockdown with angiogenesis readout but limited mechanistic dissection of how HSP47 activates ERK/CCL2\",\n      \"pmids\": [\"34000383\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SERPINH1/HSP47 is an ER-resident collagen-specific molecular chaperone that recognizes the folded triple-helical conformation of procollagens by binding Gly-Xaa-Arg motifs via a conserved aspartic acid, stabilizes thermally labile elongating triple helices at body temperature, prevents procollagen overmodification and aggregation in the ER, sorts from procollagen at ER exit sites before transport vesicle formation, and releases its substrate in a pH-dependent manner (mediated by a histidine cluster) in the cis-Golgi/ERGIC before being retrieved to the ER via its C-terminal RDEL signal; in platelets, surface-localized HSP47 directly interacts with collagen to enhance GPVI signaling and thrombosis, while in myofibroblasts it is the primary driver of tissue fibrosis by enabling fibrillar collagen secretion.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"SERPINH1/HSP47 is an ER-resident, collagen-specific molecular chaperone that recognizes the folded triple-helical conformation of procollagens and stabilizes the thermally labile elongating triple helix at body temperature [#5, #18]. Although it belongs to the serpin superfamily, it lacks the active-site residues for serine protease inhibition and instead carries a C-terminal RDEL ER-retention signal that recycles it to the ER [#0]. HSP47 recognizes its substrate by binding Arg at the Yaa position of Gly-Xaa-Arg triplets through a conserved aspartic acid, with two molecules engaging a single collagen triple helix head-to-head; collagen primary structure and flanking residues tune affinity and complex stoichiometry [#5, #7, #22, #23]. By binding the assembling helix it prevents post-translational overmodification and aggregation and times procollagen secretion, while a histidine cluster provides the structural basis for pH-dependent substrate release in the cis-Golgi/ERGIC [#3, #7, #18]. Live imaging localizes HSP47/procollagen sorting to ER exit sites, with HSP47 excluded from the transport carriers that export procollagen [#19]. HSP47 is required for the folding, assembly, and secretion of multiple collagen types — I, II, III, IV, VI, and the transmembrane collagen XVII — acting in concert with other ER folding factors including cyclophilin B, BiP/GRP94, and FKBP65 [#1, #2, #8, #21, #9]. Loss of HSP47 function causes intracellular procollagen retention, ER stress, and collagen overmodification, and a missense SERPINH1 mutation causes autosomal recessive osteogenesis imperfecta [#6, #10]. Beyond its biosynthetic role, HSP47 is the principal driver of myofibroblast-dependent tissue fibrosis by enabling fibrillar collagen deposition, is induced by TGF-\\u03b21/Smad2/3 signaling, and acts at the cell surface in platelets to enhance GPVI-collagen signaling and thrombosis; in cancer it promotes collagen-dependent platelet recruitment, metastatic colonization, and an immunosuppressive niche [#14, #15, #17, #20, #24].\",\n  \"teleology\": [\n    {\n      \"year\": 1991,\n      \"claim\": \"Established the molecular identity of HSP47 as a heat-inducible, ER-retained member of the serpin family that lacks protease-inhibitory activity, framing it as a chaperone rather than an enzyme.\",\n      \"evidence\": \"cDNA cloning, sequence homology analysis, and nuclear run-on assays\",\n      \"pmids\": [\"2072906\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Substrate specificity not yet defined\", \"No direct demonstration of chaperone activity\"]\n    },\n    {\n      \"year\": 1995,\n      \"claim\": \"Showed HSP47 stays bound to procollagen from ER into pre-Golgi intermediates and that its release tracks triple-helix maturation, linking HSP47 dissociation to collagen folding state.\",\n      \"evidence\": \"pulse-chase, reciprocal immunoprecipitation, and pharmacological trafficking inhibition; complemented by co-IP showing HSP47/BiP/GRP94 heteromeric complexes on collagen IV (1996)\",\n      \"pmids\": [\"7629154\", \"8834444\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Release trigger not molecularly defined\", \"Single-lab co-IP evidence for chaperone complexes\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Demonstrated functionally that HSP47 delays procollagen III secretion and prevents backbone overmodification, defining its quality-control role in the secretory pathway.\",\n      \"evidence\": \"heterologous reconstitution in 293 cells with cross-link co-IP, secretion and thermal stability assays\",\n      \"pmids\": [\"9722680\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Recognition motif still unknown\", \"Single heterologous system\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Defined the molecular recognition code: HSP47 reads Arg at the Yaa position of Gly-Xaa-Arg triplets plus the Yaa-3 residue on the same strand, explaining triple-helix specificity.\",\n      \"evidence\": \"systematic synthetic collagen-model peptide binding and competition assays\",\n      \"pmids\": [\"16484215\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of recognition not yet resolved\", \"Native collagen binding-site distribution unknown\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Established SERPINH1 as a disease gene by linking a conserved-domain missense mutation to autosomal recessive osteogenesis imperfecta.\",\n      \"evidence\": \"homozygosity mapping and candidate-gene analysis in affected Dachshunds\",\n      \"pmids\": [\"19629171\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cellular consequence of the mutation not yet defined\", \"Animal model only at this stage\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Provided the structural mechanism: crystal structures showed two HSP47 molecules bind a triple helix head-to-head via a conserved aspartate engaging the key Arg, and a histidine cluster rationalizes pH-dependent release.\",\n      \"evidence\": \"X-ray crystallography of free HSP47 and HSP47-collagen peptide complexes; genetic ablation in chondrocytes (Col2a1-Cre) establishing requirement for type II/XI procollagen folding\",\n      \"pmids\": [\"22847422\", \"22492985\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"pH-release model not directly tested in cells\", \"Stoichiometry on native heterotrimeric collagens unresolved\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Connected HSP47 dysfunction to a shared OI pathway with FKBP65 and dissected the cellular pathology of the OI mutation (ER retention, ER stress, collagen overmodification).\",\n      \"evidence\": \"patient/mutant fibroblast biochemistry, co-IP, immunofluorescence, mass spectrometry, ER-stress immunoblotting in the Dachshund model\",\n      \"pmids\": [\"25510505\", \"26004778\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct vs. secondary nature of FKBP65 disruption needs further dissection\", \"Single-lab co-IP for HSP47-FKBP65 interaction\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Demonstrated the essential chaperone function is thermal stabilization of the elongating triple helix: lowering temperature to 33\\u00b0C fully rescued the procollagen defects of HSP47-null fibroblasts.\",\n      \"evidence\": \"temperature-rescue experiments in hsp47-null MEFs with modification and secretion assays\",\n      \"pmids\": [\"31758055\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not address sorting/release steps\", \"Single-lab study\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Established HSP47 as the dominant cell-autonomous driver of myofibroblast-mediated fibrosis downstream of TGF-\\u03b21/Smad2/3, required for fibrillar collagen deposition and scar formation.\",\n      \"evidence\": \"myofibroblast/cardiomyocyte/endothelial cell-specific conditional knockouts in pressure-overload and MI models; TGF-\\u03b21/Smad pathway and functional fibroblast assays; therapeutic siRNA in vocal fold scar\",\n      \"pmids\": [\"31393098\", \"31664133\", \"31100613\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism coupling collagen secretion to myofibroblast proliferation unclear\", \"Human in vivo efficacy of HSP47 silencing not established\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Refined the trafficking model, showing procollagen and HSP47 sort at ER exit sites with HSP47 excluded from export carriers, correcting prior interpretations of HSP47/procollagen puncta.\",\n      \"evidence\": \"live-cell super-resolution imaging, FRAP, ARF1 inhibition, RDEL-deletion, ERGIC53 colocalization\",\n      \"pmids\": [\"32562852\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular machinery sorting HSP47 away from procollagen at ERES unidentified\", \"Timing relative to pH-dependent release not integrated\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Expanded the substrate range and mechanism, showing HSP47 is needed for assembly of collagens VI and XVII and for procollagen I secretion via direct N-terminal binding, with recombinant HSP47 rescuing folding in null membranes.\",\n      \"evidence\": \"keratinocyte-specific knockout, isolated membrane vesicle reconstitution with recombinant HSP47, EM and assembly assays\",\n      \"pmids\": [\"32716577\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Assembly vs. secretion roles differ by collagen type and not fully reconciled\", \"Single-lab reconstitution\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Refined the recognition rules at structural resolution, showing flanking hydrophobic residues alter binding affinity and switch HSP47:collagen stoichiometry from 2:1 to 1:1, and mapped sparse native binding sites clustered near the collagen N-terminus.\",\n      \"evidence\": \"collagen peptide library binding/ELISA, X-ray crystallography of HSP47-Phe/Leu peptide complexes, molecular modeling and virtual inhibitor screening\",\n      \"pmids\": [\"34487762\", \"34356607\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of variable stoichiometry in cells unknown\", \"Inhibitor efficacy in vivo not established\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Defined extracellular/surface roles of HSP47 in platelet collagen signaling and cancer metastasis, mediated by type I collagen and platelet recruitment.\",\n      \"evidence\": \"platelet-specific Hsp47 knockout with flow/thrombosis assays; Hsp47 overexpression in MECs with collagen-blocking antibody and platelet depletion; integrin/NF-\\u03baB and microglia studies in brain metastasis\",\n      \"pmids\": [\"29512284\", \"32015106\", \"38744278\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of HSP47 export to the cell surface despite RDEL signal unresolved\", \"Some downstream tumor signaling (ERK/CCL2) only low-confidence\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How HSP47 reaches the platelet and cancer cell surface despite its RDEL ER-retention signal, and how surface/extracellular HSP47 functionally relates to its canonical ER chaperone role, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No trafficking mechanism for surface localization identified\", \"Relationship between intracellular chaperone and extracellular signaling activities undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0044183\", \"supporting_discovery_ids\": [3, 18, 21]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [5, 7, 21]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [5, 7, 22]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [0, 1, 18, 19]},\n      {\"term_id\": \"GO:0005793\", \"supporting_discovery_ids\": [19]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [14, 25]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1474244\", \"supporting_discovery_ids\": [8, 15, 21]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [3, 18, 19]},\n      {\"term_id\": \"R-HSA-109582\", \"supporting_discovery_ids\": [14]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [6, 10]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"COL1A1\", \"COL2A1\", \"COL3A1\", \"FKBP10\", \"PPIB\", \"HSPA5\", \"GP6\", \"CD9\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}