{"gene":"PCOLCE","run_date":"2026-06-10T05:19:53","timeline":{"discoveries":[{"year":1994,"finding":"PCOLCE (PCPE-1) is a glycoprotein that binds the COOH-terminal propeptide of type I procollagen and enhances procollagen C-proteinase activity. The 36-kDa processed form (amino-terminal portion of the 55-kDa protein) retains full C-proteinase enhancing activity and the ability to bind the COOH-terminal propeptide. The protein comprises two CUB domains (the most conserved region) thought to mediate protein-protein interactions.","method":"Protein purification, partial amino acid sequencing, cDNA cloning, biochemical activity assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — protein purified to homogeneity, biochemical activity reconstituted in vitro, domain mapping performed, replicated by multiple subsequent studies","pmids":["7523404"],"is_preprint":false},{"year":2002,"finding":"PCPE-1 is a collagen-binding protein capable of binding at multiple sites on the triple-helical portions of fibrillar collagens, and can compete for such binding with procollagen C-proteinases. This triple-helical collagen binding is distinct from its C-propeptide binding.","method":"Solid-phase binding assays, competition binding assays with procollagen C-proteinases","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct in vitro binding assays with purified proteins, multiple binding sites characterized, replicated across two PCPE paralogs","pmids":["12393877"],"is_preprint":false},{"year":2005,"finding":"PCPE-1 enhancing activity is substrate-specific: it stimulates BMP-1-mediated C-terminal processing of fibrillar procollagens (I, II, III) but has no effect on BMP-1 processing of procollagen VII, procollagen V N-propeptide, laminin 5 gamma2 chain, osteoglycin, prolysyl oxidase, or chordin. Enhancement of procollagen III processing requires the native disulfide-bonded C-propeptide conformation but not the intact triple-helical region, indicating PCPE-1 acts via recognition of C-propeptide and C-telopeptide regions.","method":"In vitro BMP-1 processing assays with multiple substrates, use of native vs. denatured procollagen III substrates","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — reconstituted in vitro with multiple substrates and orthogonal substrate modifications, rigorous negative controls included","pmids":["15834133"],"is_preprint":false},{"year":2005,"finding":"PCPE-1 does not enhance BMP-1 chordinase activity. The CUB3 domain of BMP-1 augments the PCPE-1-mediated enhancement of procollagen C-proteinase activity, and a minimal BMP-1 lacking EGF and CUB3 domains is enhanced by PCPE-1 but less efficiently than full-length BMP-1.","method":"In vitro BMP-1/mTLL-2 domain swap experiments, procollagen C-proteinase activity assays, chordin cleavage assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — domain swap mutagenesis with reconstituted in vitro activity assays, multiple orthogonal experiments","pmids":["15817489"],"is_preprint":false},{"year":2010,"finding":"The NTR (netrin-like) domain of PCPE-1 mediates binding to cell surface heparan sulfate proteoglycans (HSPGs) with high nanomolar affinity in a calcium-dependent manner, anchoring PCPE-1 to the cell membrane and enabling pericellular enhancement of BMP-1 procollagen C-proteinase activity. The CUB domains bind procollagen C-propeptides and are required for enhancing activity.","method":"Surface plasmon resonance (SPR), cell attachment assays, immunofluorescence, heparin competition assays, domain-specific antibody inhibition, procollagen processing activity assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (SPR, cell assays, immunofluorescence, activity assays) in single study with rigorous controls","pmids":["20729553"],"is_preprint":false},{"year":2014,"finding":"The NTR domain of PCPE-1 mediates binding to syndecans-1, -2, and -4 via their glycosaminoglycan chains, and also to fibronectin. Fibronectin binding inhibits cell attachment to PCPE-1 but does not affect PCPE-1 enhancing activity. Cell attachment to PCPE-1 is not associated with cell spreading or actin filament formation, indicating PCPE-1 is not an adhesive protein.","method":"Pull-down experiments, ELISA-type binding assays, co-immunoprecipitation, cell attachment assays with fibronectin competition","journal":"The international journal of biochemistry & cell biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal binding assays and Co-IP, single lab, multiple orthogonal methods","pmids":["25286301"],"is_preprint":false},{"year":2007,"finding":"PCPE-1 interacts with beta2-microglobulin (beta2-m) via its NTR domain (not the CUB domains). PCPE-1 co-localizes and forms a complex with beta2-m in synovial tissues from dialysis-related amyloidosis patients. beta2-m does not alter BMP-1/PCP activity or PCPE-1-enhanced BMP-1 activity. PCPE-1 does not stimulate beta2-m amyloid fibril formation from monomeric beta2-m in vitro.","method":"Yeast two-hybrid screening, immunoprecipitation, solid-phase binding assays, pull-down assays, thioflavin T fluorescence spectroscopy, electron microscopy, immunohistochemistry","journal":"Matrix biology : journal of the International Society for Matrix Biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (Y2H, Co-IP, pulldown, in vitro amyloid assays), single lab","pmids":["18164932"],"is_preprint":false},{"year":2016,"finding":"Kinetic characterization of BMP-1-mediated C-terminal processing of procollagen type I shows that PCPE-1 (intact) and its isolated CUB domains fragment both stimulate BMP-1 activity, while the NTR domain alone does not enhance processing, confirming the CUB domains as the catalytically relevant enhancing unit.","method":"Enzyme kinetic assays (Km, Vmax, Kcat determination) with intact PCPE-1, CUB domain fragment, and NTR domain","journal":"Data in brief","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — rigorous in vitro kinetic reconstitution, single lab, single publication","pmids":["27872885"],"is_preprint":false},{"year":2013,"finding":"PCOLCE localizes not only to the extracellular matrix but also within the nucleus of muscle cells. Nuclear localization changes during myoblast cell fusion. PCOLCE binds soluble PABPN1 and co-localizes with aggregated PABPN1 (with preference for mutant expPABPN1) in oculopharyngeal muscular dystrophy (OPMD). In OPMD patient muscles, extracellular PCOLCE is depleted with concomitant enrichment in the nuclear compartment, suggesting PCOLCE shuttles between ECM and nucleus.","method":"Subcellular fractionation, immunofluorescence, co-immunoprecipitation, muscle biopsy immunostaining, cross-species mRNA expression profiling","journal":"BMC neurology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP and immunofluorescence localization with functional context, single lab, two orthogonal methods","pmids":["23815790"],"is_preprint":false},{"year":2017,"finding":"PCPE-1 (Pcolce) knockout mice show increased neoangiogenesis following alkali burn corneal injury compared to wild-type, and aortic ring assays confirmed PCPE-1 has anti-angiogenic activity. Pcolce-/- primary corneal keratocytes show reduced procollagen I processing, consistent with PCPE-1 role in corneal collagen deposition. Pcolce-/- mice also show abnormalities of epithelial basement membrane and re-epithelialization after corneal injury.","method":"Pcolce knockout mouse model, alkali burn and full-thickness excision corneal injury models, aortic ring assays, procollagen processing assays in primary keratocytes","journal":"Cell and tissue research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO mouse with defined phenotypic readouts and in vitro aortic ring confirmation, single lab","pmids":["28936615"],"is_preprint":false},{"year":2018,"finding":"PCPE1 and secreted frizzled-related protein 2 (sFRP2) have a synergistic effect on BMP1-mediated procollagen processing. A direct interaction between the Frizzled domain of sFRP2 and the CUB domain of PCPE1 was demonstrated, and this interaction enhances the cleavage activity of BMP1 on procollagen. Simultaneous knockdown of both proteins in mouse embryonic fibroblasts reduces collagen formation, and double knockdown in zebrafish produces dorsalized phenotypes.","method":"Co-immunoprecipitation (direct protein interaction), siRNA knockdown in MEFs (collagen formation assay), zebrafish knockdown (phenotypic epistasis)","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP binding assay plus cellular and in vivo epistasis, single lab, multiple orthogonal methods","pmids":["30411347"],"is_preprint":false},{"year":2019,"finding":"TWIST1 transcriptionally upregulates PCOLCE in osteosarcoma cells. N-linked glycosylation of PCOLCE at Asn29 is required for its pro-migratory and pro-invasive functions, as the N29Q mutant fails to promote migration, invasion, and metastasis. PCOLCE knockdown impairs migration, invasion, and lung metastasis in a spontaneous osteosarcoma model.","method":"ChIP assay (TWIST1 binding to PCOLCE promoter), luciferase reporter assay, PNGase F treatment + Western blot (glycosylation mapping), shRNA knockdown (Transwell migration/invasion, in vivo metastasis model), wild-type vs. N29Q mutant rescue","journal":"Theranostics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (ChIP, luciferase, glycosylation mutagenesis, in vivo KD), single lab","pmids":["31285765"],"is_preprint":false},{"year":2022,"finding":"Pcolce knockout mice fed a NASH-inducing diet show significant reduction in liver fibrosis and total/insoluble collagen content without changes in steatosis, inflammation, or expression of fibrosis-related genes, demonstrating that PCPE-1 specifically promotes collagen fibril deposition in fibrotic liver without affecting upstream inflammatory or transcriptional fibrosis pathways.","method":"Global constitutive Pcolce-/- mouse model, dietary NASH model, histological and biochemical collagen quantification, gene expression analysis","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO mouse with specific phenotypic readout (fibrosis but not inflammation), single lab, clean genetic model","pmids":["35148334"],"is_preprint":false},{"year":2024,"finding":"The CUB domains of PCPE-1 carry the procollagen enhancing activity. Nanobodies (I5 and H4) directed against the CUB domains inhibit PCPE-1 interaction with procollagens and reduce procollagen cleavage in vitro. Crystal structure of the PCPE-1/H4/I5 complex revealed distinct epitopes on the CUB domains for the two nanobodies. A biparatopic diabody (diab-D1) with sub-nanomolar affinity for PCPE-1 is a potent antagonist that reduces proteolytic maturation of procollagen I in human dermal fibroblast cultures.","method":"Crystal structure determination, in vitro procollagen processing inhibition assays, nanobody affinity measurements, cell-based procollagen processing assay in human dermal fibroblasts","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure with functional validation by in vitro assay and cell-based assay, single lab but multiple orthogonal methods","pmids":["38901640"],"is_preprint":false},{"year":2024,"finding":"PCPE-1 is a BAT (brown adipose tissue)-derived adipokine that promotes liver fibrosis in obesity-induced MASH. BAT-specific or systemic PCPE-1 depletion ameliorates liver fibrosis, while BAT-specific PCPE-1 overexpression enhances hepatic fibrosis. High-calorie diet-induced ER stress increases PCPE-1 production in BAT through IRE-1/JNK/c-Fos/c-Jun signaling.","method":"BAT-specific and systemic Pcolce knockout/overexpression mouse models, dietary obesity/MASH model, liver fibrosis quantification, signaling pathway analysis (IRE-1/JNK/c-Fos/c-Jun inhibition experiments)","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — tissue-specific KO and gain-of-function in vivo, signaling pathway elucidated, multiple genetic models, single lab but multiple orthogonal approaches","pmids":["39160276"],"is_preprint":false},{"year":2024,"finding":"SOX9 transcriptionally activates PCOLCE in neurofibroma cells. PCOLCE enhances PCOLCE-dependent activation of collagen VI secretion downstream of SOX9. NF1 mutation promotes nuclear translocation and transcriptional activity of SOX9, leading to increased PCOLCE expression.","method":"4D label-free proteomics, Western blot, immunofluorescence, GEO transcriptomic validation, in vivo tumor transplantation model","journal":"Molecular neurobiology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — transcriptional regulation inferred from expression changes and SOX9 perturbation, no direct promoter binding assay for PCOLCE shown in abstract, single lab","pmids":["38436832"],"is_preprint":false},{"year":2026,"finding":"Systemic and BAT-specific PCPE-1 depletion ameliorates LV fibrosis and diastolic dysfunction in obese HFpEF mice and in aged mice. BAT-specific PCPE-1 overexpression aggravates LV fibrosis and diastolic dysfunction. ROS/DNA damage/c-Fos/c-Jun signaling increases PCPE-1 production in brown adipocytes with aging.","method":"Systemic and BAT-specific Pcolce knockout and overexpression mouse models, aging and dietary obesity models, LV functional assessment, cardiac fibrosis quantification, signaling pathway analysis","journal":"JCI insight","confidence":"High","confidence_rationale":"Tier 2 / Strong — tissue-specific KO and gain-of-function in vivo with defined functional readout, signaling mechanism identified, multiple genetic models","pmids":["41955016"],"is_preprint":false}],"current_model":"PCPE-1 (PCOLCE) is an extracellular matrix glycoprotein whose CUB domains bind the C-propeptide (and C-telopeptide region) of fibrillar procollagens (types I–III) to specifically stimulate their C-terminal proteolytic maturation by BMP-1/tolloid-like proteinases, while its NTR domain anchors PCPE-1 to cell surfaces via heparan sulfate proteoglycans (syndecans-1/2/4) and fibronectin, enabling pericellular collagen assembly; PCPE-1 also functions as a BAT-derived adipokine whose secretion is induced by ER stress via IRE-1/JNK/c-Fos/c-Jun signaling and which systemically promotes fibrosis in liver and heart, and additionally exhibits anti-angiogenic activity and nuclear localization where it binds PABPN1."},"narrative":{"mechanistic_narrative":"PCOLCE (PCPE-1) is a secreted extracellular matrix glycoprotein that specifically accelerates the C-terminal proteolytic maturation of fibrillar procollagens, thereby controlling the rate-limiting step of collagen fibril deposition [PMID:7523404, PMID:15834133]. Its two CUB domains recognize the disulfide-bonded C-propeptide and C-telopeptide regions of procollagens I, II, and III and constitute the enhancing unit that stimulates BMP-1/tolloid-like proteinase activity, an effect that is substrate-restricted to fibrillar procollagens and does not extend to other BMP-1 substrates such as chordin or procollagen VII [PMID:15834133, PMID:15817489, PMID:27872885, PMID:38901640]. The C-terminal NTR (netrin-like) domain provides spatial control by anchoring PCPE-1 to the cell surface through calcium-dependent binding to heparan sulfate proteoglycans, including syndecans-1/-2/-4, and to fibronectin, localizing enhancing activity to the pericellular environment [PMID:20729553, PMID:25286301]. PCPE-1 activity is further potentiated by direct partners that engage the CUB domains, including sFRP2, whose Frizzled domain synergizes with PCPE-1 to boost BMP-1-mediated procollagen cleavage in fibroblasts and in vivo [PMID:30411347]. Genetic loss of Pcolce in mice impairs procollagen I processing and reduces collagen deposition in cornea, liver, and heart, establishing PCPE-1 as a driver of pathological fibrosis [PMID:28936615, PMID:35148334]; beyond its matrix role it acts as a brown-adipose-tissue-derived adipokine whose secretion is induced by ER stress (IRE-1/JNK/c-Fos/c-Jun) or aging-associated ROS/DNA-damage signaling and which systemically promotes liver and cardiac fibrosis [PMID:39160276, PMID:41955016]. PCPE-1 additionally exhibits anti-angiogenic activity [PMID:28936615] and can localize to the nucleus, where it binds PABPN1 [PMID:23815790]. Inhibitory nanobodies and a biparatopic diabody targeting the CUB domains block procollagen processing, defining PCPE-1 as a tractable anti-fibrotic target [PMID:38901640].","teleology":[{"year":1994,"claim":"Established the foundational activity of PCOLCE: that a discrete glycoprotein binds the procollagen C-propeptide and enhances its proteolytic processing, and localized this function to its conserved CUB-domain region.","evidence":"Protein purification, partial sequencing, cDNA cloning, and in vitro C-proteinase enhancing assays","pmids":["7523404"],"confidence":"High","gaps":["Identity of the protease being enhanced not yet defined as BMP-1","Role of the NTR domain unknown"]},{"year":2002,"claim":"Distinguished a second collagen-binding mode of PCPE-1 — binding along triple-helical regions that competes with the C-proteinase — separating it from C-propeptide recognition.","evidence":"Solid-phase and competition binding assays with purified proteins","pmids":["12393877"],"confidence":"High","gaps":["Functional consequence of triple-helix binding for enhancement unclear","In vivo relevance not addressed"]},{"year":2005,"claim":"Defined the substrate specificity and structural requirements of enhancement, showing PCPE-1 acts on fibrillar procollagens via the native C-propeptide and that BMP-1 CUB3 augments the effect.","evidence":"In vitro BMP-1 processing assays across multiple substrates, native vs. denatured substrates, and BMP-1/mTLL-2 domain swaps","pmids":["15834133","15817489"],"confidence":"High","gaps":["Atomic details of the PCPE-1/procollagen interface not resolved","How CUB3 of BMP-1 contributes mechanistically unknown"]},{"year":2010,"claim":"Resolved how enhancing activity is spatially confined, demonstrating the NTR domain tethers PCPE-1 to cell-surface heparan sulfate proteoglycans to enable pericellular procollagen processing.","evidence":"SPR, cell attachment, immunofluorescence, heparin competition, and processing assays","pmids":["20729553"],"confidence":"High","gaps":["Specific proteoglycan partners not yet identified","In vivo contribution of membrane anchoring untested"]},{"year":2014,"claim":"Identified the specific NTR-domain partners (syndecans-1/-2/-4 and fibronectin) and showed PCPE-1 is a localizer rather than an adhesion molecule.","evidence":"Pull-down, ELISA-type binding, Co-IP, and cell attachment assays with fibronectin competition","pmids":["25286301"],"confidence":"Medium","gaps":["Single lab, reciprocal in vivo validation lacking","Functional role of fibronectin binding beyond cell attachment unclear"]},{"year":2007,"claim":"Connected PCPE-1 to amyloid pathology by identifying beta2-microglobulin as an NTR-domain partner, while excluding a direct role in amyloid fibril formation or BMP-1 modulation.","evidence":"Yeast two-hybrid, Co-IP, pull-down, thioflavin T assays, EM, and immunohistochemistry","pmids":["18164932"],"confidence":"Medium","gaps":["Physiological significance of the beta2-m interaction unresolved","Single lab finding"]},{"year":2013,"claim":"Uncovered an unexpected nuclear pool of PCOLCE that binds PABPN1 and redistributes from ECM to nucleus in oculopharyngeal muscular dystrophy, implying a non-matrix function.","evidence":"Subcellular fractionation, immunofluorescence, Co-IP, and muscle biopsy immunostaining","pmids":["23815790"],"confidence":"Medium","gaps":["Mechanism of nuclear import unknown","Functional consequence of PABPN1 binding undefined"]},{"year":2016,"claim":"Kinetically confirmed that the CUB domains alone reproduce enhancement while the NTR domain does not, formally assigning the catalytic-enhancing role to CUB.","evidence":"Enzyme kinetic assays with intact protein, CUB fragment, and NTR domain","pmids":["27872885"],"confidence":"Medium","gaps":["Single publication","No structural basis for the kinetic effect"]},{"year":2017,"claim":"Provided the first genetic loss-of-function evidence in vivo, showing PCPE-1 is required for corneal collagen processing and possesses intrinsic anti-angiogenic activity.","evidence":"Pcolce knockout mice, corneal injury models, aortic ring assays, keratocyte processing assays","pmids":["28936615"],"confidence":"Medium","gaps":["Molecular basis of anti-angiogenic activity unknown","Single lab"]},{"year":2018,"claim":"Identified sFRP2 as a CUB-domain partner that synergistically boosts BMP-1 procollagen processing, expanding the set of PCPE-1 co-activators.","evidence":"Co-IP, siRNA knockdown in MEFs, and zebrafish double-knockdown epistasis","pmids":["30411347"],"confidence":"Medium","gaps":["Structural detail of the sFRP2/CUB interface lacking","Single lab"]},{"year":2019,"claim":"Linked PCOLCE to tumor progression, showing TWIST1-driven expression and N29 glycosylation are required for pro-migratory/pro-metastatic function in osteosarcoma.","evidence":"ChIP, luciferase reporter, glycosylation mapping/mutagenesis, shRNA knockdown, and in vivo metastasis model","pmids":["31285765"],"confidence":"Medium","gaps":["Whether pro-metastatic function depends on procollagen processing unclear","Single lab"]},{"year":2022,"claim":"Demonstrated that PCPE-1 specifically drives collagen fibril deposition in liver fibrosis without altering upstream inflammation or fibrosis-gene transcription, positioning it at the post-translational maturation step.","evidence":"Global Pcolce-/- mice in a dietary NASH model with histological and biochemical collagen quantification","pmids":["35148334"],"confidence":"Medium","gaps":["Cellular source of PCPE-1 in liver not identified here","Single lab"]},{"year":2024,"claim":"Defined the CUB domains structurally as the procollagen-binding/enhancing module and validated them as a druggable anti-fibrotic target using nanobodies and a biparatopic diabody.","evidence":"Crystal structure of PCPE-1/nanobody complex, in vitro inhibition assays, and cell-based processing assays in human dermal fibroblasts","pmids":["38901640"],"confidence":"High","gaps":["No structure of PCPE-1 bound to procollagen","In vivo efficacy of antagonists not tested"]},{"year":2024,"claim":"Reframed PCPE-1 as an endocrine adipokine, showing BAT-derived PCPE-1 induced by ER stress signaling promotes liver fibrosis systemically.","evidence":"BAT-specific and systemic Pcolce knockout/overexpression mice, MASH model, and IRE-1/JNK/c-Fos/c-Jun pathway inhibition","pmids":["39160276"],"confidence":"High","gaps":["Receptor/uptake mechanism for circulating PCPE-1 unknown","Whether the same applies to non-hepatic fibrosis pursued separately"]},{"year":2024,"claim":"Extended the regulatory map by implicating SOX9 in driving PCOLCE expression and collagen VI secretion in NF1-mutant neurofibroma.","evidence":"Proteomics, Western blot, immunofluorescence, transcriptomic validation, and in vivo tumor model","pmids":["38436832"],"confidence":"Low","gaps":["No direct SOX9 promoter-binding assay for PCOLCE shown","Single lab, transcriptional regulation inferred from perturbation"]},{"year":2026,"claim":"Generalized the adipokine paradigm to the heart, showing BAT-derived PCPE-1 induced by aging/ROS signaling drives cardiac fibrosis and diastolic dysfunction in HFpEF.","evidence":"Systemic and BAT-specific Pcolce knockout/overexpression mice in aging and obesity models with LV functional and fibrosis readouts","pmids":["41955016"],"confidence":"High","gaps":["Target organ receptor for circulating PCPE-1 still unidentified","Translation to human HFpEF untested"]},{"year":null,"claim":"How circulating PCPE-1 is taken up by target tissues, and how its nuclear/PABPN1-binding and anti-angiogenic activities relate mechanistically to its procollagen-processing role, remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No receptor identified for endocrine PCPE-1","Nuclear function mechanistically uncharacterized","Structural basis of substrate specificity incomplete"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,2,4,7,13]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[0,1,2]},{"term_id":"GO:0048018","term_label":"receptor ligand activity","supporting_discovery_ids":[14,16]}],"localization":[{"term_id":"GO:0005576","term_label":"extracellular region","supporting_discovery_ids":[0,8,12]},{"term_id":"GO:0031012","term_label":"extracellular matrix","supporting_discovery_ids":[8,9]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[4,5]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[8]}],"pathway":[{"term_id":"R-HSA-1474244","term_label":"Extracellular matrix organization","supporting_discovery_ids":[0,2,9,12]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[12,14,16]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[0,2,4,13]}],"complexes":[],"partners":["BMP1","SDC1","SDC2","SDC4","FN1","B2M","PABPN1","SFRP2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q15113","full_name":"Procollagen C-endopeptidase enhancer 1","aliases":["Procollagen COOH-terminal proteinase enhancer 1","PCPE-1","Procollagen C-proteinase enhancer 1","Type 1 procollagen C-proteinase enhancer protein","Type I procollagen COOH-terminal proteinase enhancer"],"length_aa":449,"mass_kda":48.0,"function":"Binds to the C-terminal propeptide of type I procollagen and enhances procollagen C-proteinase activity C-terminal processed part of PCPE (CT-PCPE) may have an metalloproteinase inhibitory activity","subcellular_location":"Secreted","url":"https://www.uniprot.org/uniprotkb/Q15113/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/PCOLCE","classification":"Not Classified","n_dependent_lines":9,"n_total_lines":1208,"dependency_fraction":0.0074503311258278145},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/PCOLCE","total_profiled":1310},"omim":[{"mim_id":"607064","title":"PROCOLLAGEN C-ENDOPEPTIDASE ENHANCER 2; PCOLCE2","url":"https://www.omim.org/entry/607064"},{"mim_id":"604633","title":"EGF-CONTAINING FIBULIN-LIKE EXTRACELLULAR MATRIX PROTEIN 2; EFEMP2","url":"https://www.omim.org/entry/604633"},{"mim_id":"600270","title":"PROCOLLAGEN C-ENDOPEPTIDASE ENHANCER; PCOLCE","url":"https://www.omim.org/entry/600270"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Golgi apparatus","reliability":"Approved"},{"location":"Vesicles","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in many","driving_tissues":[],"url":"https://www.proteinatlas.org/search/PCOLCE"},"hgnc":{"alias_symbol":["PCPE","PCPE1"],"prev_symbol":[]},"alphafold":{"accession":"Q15113","domains":[{"cath_id":"2.60.120.290","chopping":"40-151","consensus_level":"high","plddt":88.4642,"start":40,"end":151},{"cath_id":"2.60.120.290","chopping":"161-275","consensus_level":"high","plddt":89.014,"start":161,"end":275},{"cath_id":"2.40.50.120","chopping":"329-435","consensus_level":"high","plddt":88.8832,"start":329,"end":435}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q15113","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q15113-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q15113-F1-predicted_aligned_error_v6.png","plddt_mean":79.56},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PCOLCE","jax_strain_url":"https://www.jax.org/strain/search?query=PCOLCE"},"sequence":{"accession":"Q15113","fasta_url":"https://rest.uniprot.org/uniprotkb/Q15113.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q15113/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q15113"}},"corpus_meta":[{"pmid":"12393877","id":"PMC_12393877","title":"PCOLCE2 encodes a functional procollagen C-proteinase enhancer (PCPE2) that is a collagen-binding protein differing in distribution of expression and post-translational modification from the previously described PCPE1.","date":"2002","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12393877","citation_count":118,"is_preprint":false},{"pmid":"15834133","id":"PMC_15834133","title":"Substrate-specific modulation of a multisubstrate proteinase. C-terminal processing of fibrillar procollagens is the only BMP-1-dependent activity to be enhanced by PCPE-1.","date":"2005","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15834133","citation_count":93,"is_preprint":false},{"pmid":"7523404","id":"PMC_7523404","title":"Type I procollagen COOH-terminal proteinase enhancer protein: identification, primary structure, and chromosomal localization of the cognate human gene (PCOLCE).","date":"1994","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/7523404","citation_count":88,"is_preprint":false},{"pmid":"31285765","id":"PMC_31285765","title":"Up-regulation of PCOLCE by TWIST1 promotes metastasis in Osteosarcoma.","date":"2019","source":"Theranostics","url":"https://pubmed.ncbi.nlm.nih.gov/31285765","citation_count":60,"is_preprint":false},{"pmid":"34435180","id":"PMC_34435180","title":"Procollagen C-proteinase enhancer-1 (PCPE-1), a potential biomarker and therapeutic target for fibrosis.","date":"2021","source":"Matrix biology plus","url":"https://pubmed.ncbi.nlm.nih.gov/34435180","citation_count":36,"is_preprint":false},{"pmid":"15817489","id":"PMC_15817489","title":"Identification of the minimal domain structure of bone morphogenetic protein-1 (BMP-1) for chordinase activity: chordinase activity is not enhanced by procollagen C-proteinase enhancer-1 (PCPE-1).","date":"2005","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15817489","citation_count":36,"is_preprint":false},{"pmid":"20729553","id":"PMC_20729553","title":"Binding of procollagen C-proteinase enhancer-1 (PCPE-1) to heparin/heparan sulfate: properties and role in PCPE-1 interaction with cells.","date":"2010","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/20729553","citation_count":35,"is_preprint":false},{"pmid":"25286301","id":"PMC_25286301","title":"The NTR domain of procollagen C-proteinase enhancer-1 (PCPE-1) mediates PCPE-1 binding to syndecans-1, -2 and -4 as well as fibronectin.","date":"2014","source":"The international journal of biochemistry & cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/25286301","citation_count":19,"is_preprint":false},{"pmid":"28936615","id":"PMC_28936615","title":"Procollagen C-proteinase enhancer 1 (PCPE-1) functions as an anti-angiogenic factor and enhances epithelial recovery in injured cornea.","date":"2017","source":"Cell and tissue research","url":"https://pubmed.ncbi.nlm.nih.gov/28936615","citation_count":19,"is_preprint":false},{"pmid":"12393284","id":"PMC_12393284","title":"PCOLCE deletion and expression analyses in uterine leiomyomata.","date":"2002","source":"Cancer genetics and cytogenetics","url":"https://pubmed.ncbi.nlm.nih.gov/12393284","citation_count":16,"is_preprint":false},{"pmid":"23815790","id":"PMC_23815790","title":"Nuclear entrapment and extracellular depletion of PCOLCE is associated with muscle degeneration in oculopharyngeal muscular dystrophy.","date":"2013","source":"BMC neurology","url":"https://pubmed.ncbi.nlm.nih.gov/23815790","citation_count":15,"is_preprint":false},{"pmid":"26402709","id":"PMC_26402709","title":"Penetration of HIV-1 Tat47-57 into PC/PE Bilayers Assessed by MD Simulation and X-ray Scattering.","date":"2015","source":"Membranes","url":"https://pubmed.ncbi.nlm.nih.gov/26402709","citation_count":14,"is_preprint":false},{"pmid":"35148334","id":"PMC_35148334","title":"Procollagen C-Proteinase Enhancer-1 (PCPE-1) deficiency in mice reduces liver fibrosis but not NASH progression.","date":"2022","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/35148334","citation_count":13,"is_preprint":false},{"pmid":"19361460","id":"PMC_19361460","title":"Different patterns of human serum procollagen C-proteinase enhancer1 (PCPE1).","date":"2009","source":"Clinica chimica acta; international journal of clinical chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/19361460","citation_count":13,"is_preprint":false},{"pmid":"36596064","id":"PMC_36596064","title":"A pan-cancer analysis of the oncogenic role of procollagen C-endopeptidase enhancer (PCOLCE) in human.","date":"2022","source":"Medicine","url":"https://pubmed.ncbi.nlm.nih.gov/36596064","citation_count":12,"is_preprint":false},{"pmid":"39160276","id":"PMC_39160276","title":"PCPE-1, a brown adipose tissue-derived cytokine, promotes obesity-induced liver fibrosis.","date":"2024","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/39160276","citation_count":11,"is_preprint":false},{"pmid":"18164932","id":"PMC_18164932","title":"Procollagen C-proteinase enhancer-1 (PCPE-1) interacts with beta2-microglobulin (beta2-m) and may help initiate beta2-m amyloid fibril formation in connective tissues.","date":"2007","source":"Matrix biology : journal of the International Society for Matrix Biology","url":"https://pubmed.ncbi.nlm.nih.gov/18164932","citation_count":11,"is_preprint":false},{"pmid":"38049428","id":"PMC_38049428","title":"Identification of PCPE-2 as the endogenous specific inhibitor of human BMP-1/tolloid-like proteinases.","date":"2023","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/38049428","citation_count":10,"is_preprint":false},{"pmid":"30411347","id":"PMC_30411347","title":"Synergistic effect of PCPE1 and sFRP2 on the processing of procollagens via BMP1.","date":"2018","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/30411347","citation_count":9,"is_preprint":false},{"pmid":"39251075","id":"PMC_39251075","title":"PCPE-2 (procollagen C-proteinase enhancer-2): The non-identical twin of PCPE-1.","date":"2024","source":"Matrix biology : journal of the International Society for Matrix Biology","url":"https://pubmed.ncbi.nlm.nih.gov/39251075","citation_count":6,"is_preprint":false},{"pmid":"38436832","id":"PMC_38436832","title":"SOX9 Promotes Collagen VI Secretion by Upregulating PCOLCE in Neurofibroma.","date":"2024","source":"Molecular neurobiology","url":"https://pubmed.ncbi.nlm.nih.gov/38436832","citation_count":4,"is_preprint":false},{"pmid":"30840244","id":"PMC_30840244","title":"Procollagen C-Proteinase Enhancer 1 (PCPE-1) in Liver Fibrosis.","date":"2019","source":"Methods in molecular biology (Clifton, N.J.)","url":"https://pubmed.ncbi.nlm.nih.gov/30840244","citation_count":4,"is_preprint":false},{"pmid":"30920659","id":"PMC_30920659","title":"Synergistic effect of PCPE1 and sFRP2 on the processing of procollagens via BMP1.","date":"2019","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/30920659","citation_count":4,"is_preprint":false},{"pmid":"27872885","id":"PMC_27872885","title":"Data comparing the kinetics of procollagen type I processing by bone morphogenetic protein 1 (BMP-1) with and without procollagen C-proteinase enhancer 1 (PCPE-1).","date":"2016","source":"Data in brief","url":"https://pubmed.ncbi.nlm.nih.gov/27872885","citation_count":4,"is_preprint":false},{"pmid":"10723726","id":"PMC_10723726","title":"Comparative analysis of the PCOLCE region in Fugu rubripes using a new automated annotation tool.","date":"2000","source":"Mammalian genome : official journal of the International Mammalian Genome Society","url":"https://pubmed.ncbi.nlm.nih.gov/10723726","citation_count":4,"is_preprint":false},{"pmid":"38901640","id":"PMC_38901640","title":"Mono- and Bi-specific Nanobodies Targeting the CUB Domains of PCPE-1 Reduce the Proteolytic Processing of Fibrillar Procollagens.","date":"2024","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/38901640","citation_count":2,"is_preprint":false},{"pmid":"39909491","id":"PMC_39909491","title":"Anti-citrullinated procollagen C-endopeptidase enhancer antibody (anti-PCOLCE): a potential biomarker for seronegative rheumatoid arthritis.","date":"2025","source":"Rheumatology (Oxford, England)","url":"https://pubmed.ncbi.nlm.nih.gov/39909491","citation_count":2,"is_preprint":false},{"pmid":"40658197","id":"PMC_40658197","title":"Evaluating serum biomarkers in keratoconus: the role of PCPE-1 and PCPE-2 in collagen metabolism and disease progression.","date":"2025","source":"Graefe's archive for clinical and experimental ophthalmology = Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie","url":"https://pubmed.ncbi.nlm.nih.gov/40658197","citation_count":1,"is_preprint":false},{"pmid":"41955016","id":"PMC_41955016","title":"PCPE-1 promotes cardiac fibrosis with aging and obesity.","date":"2026","source":"JCI insight","url":"https://pubmed.ncbi.nlm.nih.gov/41955016","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":16912,"output_tokens":4745,"usd":0.060956,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":12854,"output_tokens":4834,"usd":0.09256,"stage2_stop_reason":"end_turn"},"total_usd":0.153516,"stage1_batch_id":"msgbatch_013a8chtv3AWyTqv4z4sEF4C","stage2_batch_id":"msgbatch_01AHsuW63vinsvuTgzmQ3n62","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1994,\n      \"finding\": \"PCOLCE (PCPE-1) is a glycoprotein that binds the COOH-terminal propeptide of type I procollagen and enhances procollagen C-proteinase activity. The 36-kDa processed form (amino-terminal portion of the 55-kDa protein) retains full C-proteinase enhancing activity and the ability to bind the COOH-terminal propeptide. The protein comprises two CUB domains (the most conserved region) thought to mediate protein-protein interactions.\",\n      \"method\": \"Protein purification, partial amino acid sequencing, cDNA cloning, biochemical activity assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — protein purified to homogeneity, biochemical activity reconstituted in vitro, domain mapping performed, replicated by multiple subsequent studies\",\n      \"pmids\": [\"7523404\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"PCPE-1 is a collagen-binding protein capable of binding at multiple sites on the triple-helical portions of fibrillar collagens, and can compete for such binding with procollagen C-proteinases. This triple-helical collagen binding is distinct from its C-propeptide binding.\",\n      \"method\": \"Solid-phase binding assays, competition binding assays with procollagen C-proteinases\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct in vitro binding assays with purified proteins, multiple binding sites characterized, replicated across two PCPE paralogs\",\n      \"pmids\": [\"12393877\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"PCPE-1 enhancing activity is substrate-specific: it stimulates BMP-1-mediated C-terminal processing of fibrillar procollagens (I, II, III) but has no effect on BMP-1 processing of procollagen VII, procollagen V N-propeptide, laminin 5 gamma2 chain, osteoglycin, prolysyl oxidase, or chordin. Enhancement of procollagen III processing requires the native disulfide-bonded C-propeptide conformation but not the intact triple-helical region, indicating PCPE-1 acts via recognition of C-propeptide and C-telopeptide regions.\",\n      \"method\": \"In vitro BMP-1 processing assays with multiple substrates, use of native vs. denatured procollagen III substrates\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — reconstituted in vitro with multiple substrates and orthogonal substrate modifications, rigorous negative controls included\",\n      \"pmids\": [\"15834133\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"PCPE-1 does not enhance BMP-1 chordinase activity. The CUB3 domain of BMP-1 augments the PCPE-1-mediated enhancement of procollagen C-proteinase activity, and a minimal BMP-1 lacking EGF and CUB3 domains is enhanced by PCPE-1 but less efficiently than full-length BMP-1.\",\n      \"method\": \"In vitro BMP-1/mTLL-2 domain swap experiments, procollagen C-proteinase activity assays, chordin cleavage assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — domain swap mutagenesis with reconstituted in vitro activity assays, multiple orthogonal experiments\",\n      \"pmids\": [\"15817489\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"The NTR (netrin-like) domain of PCPE-1 mediates binding to cell surface heparan sulfate proteoglycans (HSPGs) with high nanomolar affinity in a calcium-dependent manner, anchoring PCPE-1 to the cell membrane and enabling pericellular enhancement of BMP-1 procollagen C-proteinase activity. The CUB domains bind procollagen C-propeptides and are required for enhancing activity.\",\n      \"method\": \"Surface plasmon resonance (SPR), cell attachment assays, immunofluorescence, heparin competition assays, domain-specific antibody inhibition, procollagen processing activity assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (SPR, cell assays, immunofluorescence, activity assays) in single study with rigorous controls\",\n      \"pmids\": [\"20729553\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"The NTR domain of PCPE-1 mediates binding to syndecans-1, -2, and -4 via their glycosaminoglycan chains, and also to fibronectin. Fibronectin binding inhibits cell attachment to PCPE-1 but does not affect PCPE-1 enhancing activity. Cell attachment to PCPE-1 is not associated with cell spreading or actin filament formation, indicating PCPE-1 is not an adhesive protein.\",\n      \"method\": \"Pull-down experiments, ELISA-type binding assays, co-immunoprecipitation, cell attachment assays with fibronectin competition\",\n      \"journal\": \"The international journal of biochemistry & cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal binding assays and Co-IP, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"25286301\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"PCPE-1 interacts with beta2-microglobulin (beta2-m) via its NTR domain (not the CUB domains). PCPE-1 co-localizes and forms a complex with beta2-m in synovial tissues from dialysis-related amyloidosis patients. beta2-m does not alter BMP-1/PCP activity or PCPE-1-enhanced BMP-1 activity. PCPE-1 does not stimulate beta2-m amyloid fibril formation from monomeric beta2-m in vitro.\",\n      \"method\": \"Yeast two-hybrid screening, immunoprecipitation, solid-phase binding assays, pull-down assays, thioflavin T fluorescence spectroscopy, electron microscopy, immunohistochemistry\",\n      \"journal\": \"Matrix biology : journal of the International Society for Matrix Biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (Y2H, Co-IP, pulldown, in vitro amyloid assays), single lab\",\n      \"pmids\": [\"18164932\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Kinetic characterization of BMP-1-mediated C-terminal processing of procollagen type I shows that PCPE-1 (intact) and its isolated CUB domains fragment both stimulate BMP-1 activity, while the NTR domain alone does not enhance processing, confirming the CUB domains as the catalytically relevant enhancing unit.\",\n      \"method\": \"Enzyme kinetic assays (Km, Vmax, Kcat determination) with intact PCPE-1, CUB domain fragment, and NTR domain\",\n      \"journal\": \"Data in brief\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — rigorous in vitro kinetic reconstitution, single lab, single publication\",\n      \"pmids\": [\"27872885\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"PCOLCE localizes not only to the extracellular matrix but also within the nucleus of muscle cells. Nuclear localization changes during myoblast cell fusion. PCOLCE binds soluble PABPN1 and co-localizes with aggregated PABPN1 (with preference for mutant expPABPN1) in oculopharyngeal muscular dystrophy (OPMD). In OPMD patient muscles, extracellular PCOLCE is depleted with concomitant enrichment in the nuclear compartment, suggesting PCOLCE shuttles between ECM and nucleus.\",\n      \"method\": \"Subcellular fractionation, immunofluorescence, co-immunoprecipitation, muscle biopsy immunostaining, cross-species mRNA expression profiling\",\n      \"journal\": \"BMC neurology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP and immunofluorescence localization with functional context, single lab, two orthogonal methods\",\n      \"pmids\": [\"23815790\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"PCPE-1 (Pcolce) knockout mice show increased neoangiogenesis following alkali burn corneal injury compared to wild-type, and aortic ring assays confirmed PCPE-1 has anti-angiogenic activity. Pcolce-/- primary corneal keratocytes show reduced procollagen I processing, consistent with PCPE-1 role in corneal collagen deposition. Pcolce-/- mice also show abnormalities of epithelial basement membrane and re-epithelialization after corneal injury.\",\n      \"method\": \"Pcolce knockout mouse model, alkali burn and full-thickness excision corneal injury models, aortic ring assays, procollagen processing assays in primary keratocytes\",\n      \"journal\": \"Cell and tissue research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO mouse with defined phenotypic readouts and in vitro aortic ring confirmation, single lab\",\n      \"pmids\": [\"28936615\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"PCPE1 and secreted frizzled-related protein 2 (sFRP2) have a synergistic effect on BMP1-mediated procollagen processing. A direct interaction between the Frizzled domain of sFRP2 and the CUB domain of PCPE1 was demonstrated, and this interaction enhances the cleavage activity of BMP1 on procollagen. Simultaneous knockdown of both proteins in mouse embryonic fibroblasts reduces collagen formation, and double knockdown in zebrafish produces dorsalized phenotypes.\",\n      \"method\": \"Co-immunoprecipitation (direct protein interaction), siRNA knockdown in MEFs (collagen formation assay), zebrafish knockdown (phenotypic epistasis)\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP binding assay plus cellular and in vivo epistasis, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"30411347\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"TWIST1 transcriptionally upregulates PCOLCE in osteosarcoma cells. N-linked glycosylation of PCOLCE at Asn29 is required for its pro-migratory and pro-invasive functions, as the N29Q mutant fails to promote migration, invasion, and metastasis. PCOLCE knockdown impairs migration, invasion, and lung metastasis in a spontaneous osteosarcoma model.\",\n      \"method\": \"ChIP assay (TWIST1 binding to PCOLCE promoter), luciferase reporter assay, PNGase F treatment + Western blot (glycosylation mapping), shRNA knockdown (Transwell migration/invasion, in vivo metastasis model), wild-type vs. N29Q mutant rescue\",\n      \"journal\": \"Theranostics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (ChIP, luciferase, glycosylation mutagenesis, in vivo KD), single lab\",\n      \"pmids\": [\"31285765\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Pcolce knockout mice fed a NASH-inducing diet show significant reduction in liver fibrosis and total/insoluble collagen content without changes in steatosis, inflammation, or expression of fibrosis-related genes, demonstrating that PCPE-1 specifically promotes collagen fibril deposition in fibrotic liver without affecting upstream inflammatory or transcriptional fibrosis pathways.\",\n      \"method\": \"Global constitutive Pcolce-/- mouse model, dietary NASH model, histological and biochemical collagen quantification, gene expression analysis\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO mouse with specific phenotypic readout (fibrosis but not inflammation), single lab, clean genetic model\",\n      \"pmids\": [\"35148334\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"The CUB domains of PCPE-1 carry the procollagen enhancing activity. Nanobodies (I5 and H4) directed against the CUB domains inhibit PCPE-1 interaction with procollagens and reduce procollagen cleavage in vitro. Crystal structure of the PCPE-1/H4/I5 complex revealed distinct epitopes on the CUB domains for the two nanobodies. A biparatopic diabody (diab-D1) with sub-nanomolar affinity for PCPE-1 is a potent antagonist that reduces proteolytic maturation of procollagen I in human dermal fibroblast cultures.\",\n      \"method\": \"Crystal structure determination, in vitro procollagen processing inhibition assays, nanobody affinity measurements, cell-based procollagen processing assay in human dermal fibroblasts\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure with functional validation by in vitro assay and cell-based assay, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"38901640\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"PCPE-1 is a BAT (brown adipose tissue)-derived adipokine that promotes liver fibrosis in obesity-induced MASH. BAT-specific or systemic PCPE-1 depletion ameliorates liver fibrosis, while BAT-specific PCPE-1 overexpression enhances hepatic fibrosis. High-calorie diet-induced ER stress increases PCPE-1 production in BAT through IRE-1/JNK/c-Fos/c-Jun signaling.\",\n      \"method\": \"BAT-specific and systemic Pcolce knockout/overexpression mouse models, dietary obesity/MASH model, liver fibrosis quantification, signaling pathway analysis (IRE-1/JNK/c-Fos/c-Jun inhibition experiments)\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — tissue-specific KO and gain-of-function in vivo, signaling pathway elucidated, multiple genetic models, single lab but multiple orthogonal approaches\",\n      \"pmids\": [\"39160276\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"SOX9 transcriptionally activates PCOLCE in neurofibroma cells. PCOLCE enhances PCOLCE-dependent activation of collagen VI secretion downstream of SOX9. NF1 mutation promotes nuclear translocation and transcriptional activity of SOX9, leading to increased PCOLCE expression.\",\n      \"method\": \"4D label-free proteomics, Western blot, immunofluorescence, GEO transcriptomic validation, in vivo tumor transplantation model\",\n      \"journal\": \"Molecular neurobiology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — transcriptional regulation inferred from expression changes and SOX9 perturbation, no direct promoter binding assay for PCOLCE shown in abstract, single lab\",\n      \"pmids\": [\"38436832\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Systemic and BAT-specific PCPE-1 depletion ameliorates LV fibrosis and diastolic dysfunction in obese HFpEF mice and in aged mice. BAT-specific PCPE-1 overexpression aggravates LV fibrosis and diastolic dysfunction. ROS/DNA damage/c-Fos/c-Jun signaling increases PCPE-1 production in brown adipocytes with aging.\",\n      \"method\": \"Systemic and BAT-specific Pcolce knockout and overexpression mouse models, aging and dietary obesity models, LV functional assessment, cardiac fibrosis quantification, signaling pathway analysis\",\n      \"journal\": \"JCI insight\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — tissue-specific KO and gain-of-function in vivo with defined functional readout, signaling mechanism identified, multiple genetic models\",\n      \"pmids\": [\"41955016\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PCPE-1 (PCOLCE) is an extracellular matrix glycoprotein whose CUB domains bind the C-propeptide (and C-telopeptide region) of fibrillar procollagens (types I–III) to specifically stimulate their C-terminal proteolytic maturation by BMP-1/tolloid-like proteinases, while its NTR domain anchors PCPE-1 to cell surfaces via heparan sulfate proteoglycans (syndecans-1/2/4) and fibronectin, enabling pericellular collagen assembly; PCPE-1 also functions as a BAT-derived adipokine whose secretion is induced by ER stress via IRE-1/JNK/c-Fos/c-Jun signaling and which systemically promotes fibrosis in liver and heart, and additionally exhibits anti-angiogenic activity and nuclear localization where it binds PABPN1.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PCOLCE (PCPE-1) is a secreted extracellular matrix glycoprotein that specifically accelerates the C-terminal proteolytic maturation of fibrillar procollagens, thereby controlling the rate-limiting step of collagen fibril deposition [#0, #2]. Its two CUB domains recognize the disulfide-bonded C-propeptide and C-telopeptide regions of procollagens I, II, and III and constitute the enhancing unit that stimulates BMP-1/tolloid-like proteinase activity, an effect that is substrate-restricted to fibrillar procollagens and does not extend to other BMP-1 substrates such as chordin or procollagen VII [#2, #3, #7, #13]. The C-terminal NTR (netrin-like) domain provides spatial control by anchoring PCPE-1 to the cell surface through calcium-dependent binding to heparan sulfate proteoglycans, including syndecans-1/-2/-4, and to fibronectin, localizing enhancing activity to the pericellular environment [#4, #5]. PCPE-1 activity is further potentiated by direct partners that engage the CUB domains, including sFRP2, whose Frizzled domain synergizes with PCPE-1 to boost BMP-1-mediated procollagen cleavage in fibroblasts and in vivo [#10]. Genetic loss of Pcolce in mice impairs procollagen I processing and reduces collagen deposition in cornea, liver, and heart, establishing PCPE-1 as a driver of pathological fibrosis [#9, #12]; beyond its matrix role it acts as a brown-adipose-tissue-derived adipokine whose secretion is induced by ER stress (IRE-1/JNK/c-Fos/c-Jun) or aging-associated ROS/DNA-damage signaling and which systemically promotes liver and cardiac fibrosis [#14, #16]. PCPE-1 additionally exhibits anti-angiogenic activity [#9] and can localize to the nucleus, where it binds PABPN1 [#8]. Inhibitory nanobodies and a biparatopic diabody targeting the CUB domains block procollagen processing, defining PCPE-1 as a tractable anti-fibrotic target [#13].\",\n  \"teleology\": [\n    {\n      \"year\": 1994,\n      \"claim\": \"Established the foundational activity of PCOLCE: that a discrete glycoprotein binds the procollagen C-propeptide and enhances its proteolytic processing, and localized this function to its conserved CUB-domain region.\",\n      \"evidence\": \"Protein purification, partial sequencing, cDNA cloning, and in vitro C-proteinase enhancing assays\",\n      \"pmids\": [\"7523404\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the protease being enhanced not yet defined as BMP-1\", \"Role of the NTR domain unknown\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Distinguished a second collagen-binding mode of PCPE-1 — binding along triple-helical regions that competes with the C-proteinase — separating it from C-propeptide recognition.\",\n      \"evidence\": \"Solid-phase and competition binding assays with purified proteins\",\n      \"pmids\": [\"12393877\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of triple-helix binding for enhancement unclear\", \"In vivo relevance not addressed\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Defined the substrate specificity and structural requirements of enhancement, showing PCPE-1 acts on fibrillar procollagens via the native C-propeptide and that BMP-1 CUB3 augments the effect.\",\n      \"evidence\": \"In vitro BMP-1 processing assays across multiple substrates, native vs. denatured substrates, and BMP-1/mTLL-2 domain swaps\",\n      \"pmids\": [\"15834133\", \"15817489\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Atomic details of the PCPE-1/procollagen interface not resolved\", \"How CUB3 of BMP-1 contributes mechanistically unknown\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Resolved how enhancing activity is spatially confined, demonstrating the NTR domain tethers PCPE-1 to cell-surface heparan sulfate proteoglycans to enable pericellular procollagen processing.\",\n      \"evidence\": \"SPR, cell attachment, immunofluorescence, heparin competition, and processing assays\",\n      \"pmids\": [\"20729553\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific proteoglycan partners not yet identified\", \"In vivo contribution of membrane anchoring untested\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Identified the specific NTR-domain partners (syndecans-1/-2/-4 and fibronectin) and showed PCPE-1 is a localizer rather than an adhesion molecule.\",\n      \"evidence\": \"Pull-down, ELISA-type binding, Co-IP, and cell attachment assays with fibronectin competition\",\n      \"pmids\": [\"25286301\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab, reciprocal in vivo validation lacking\", \"Functional role of fibronectin binding beyond cell attachment unclear\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Connected PCPE-1 to amyloid pathology by identifying beta2-microglobulin as an NTR-domain partner, while excluding a direct role in amyloid fibril formation or BMP-1 modulation.\",\n      \"evidence\": \"Yeast two-hybrid, Co-IP, pull-down, thioflavin T assays, EM, and immunohistochemistry\",\n      \"pmids\": [\"18164932\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Physiological significance of the beta2-m interaction unresolved\", \"Single lab finding\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Uncovered an unexpected nuclear pool of PCOLCE that binds PABPN1 and redistributes from ECM to nucleus in oculopharyngeal muscular dystrophy, implying a non-matrix function.\",\n      \"evidence\": \"Subcellular fractionation, immunofluorescence, Co-IP, and muscle biopsy immunostaining\",\n      \"pmids\": [\"23815790\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of nuclear import unknown\", \"Functional consequence of PABPN1 binding undefined\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Kinetically confirmed that the CUB domains alone reproduce enhancement while the NTR domain does not, formally assigning the catalytic-enhancing role to CUB.\",\n      \"evidence\": \"Enzyme kinetic assays with intact protein, CUB fragment, and NTR domain\",\n      \"pmids\": [\"27872885\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single publication\", \"No structural basis for the kinetic effect\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Provided the first genetic loss-of-function evidence in vivo, showing PCPE-1 is required for corneal collagen processing and possesses intrinsic anti-angiogenic activity.\",\n      \"evidence\": \"Pcolce knockout mice, corneal injury models, aortic ring assays, keratocyte processing assays\",\n      \"pmids\": [\"28936615\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular basis of anti-angiogenic activity unknown\", \"Single lab\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Identified sFRP2 as a CUB-domain partner that synergistically boosts BMP-1 procollagen processing, expanding the set of PCPE-1 co-activators.\",\n      \"evidence\": \"Co-IP, siRNA knockdown in MEFs, and zebrafish double-knockdown epistasis\",\n      \"pmids\": [\"30411347\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural detail of the sFRP2/CUB interface lacking\", \"Single lab\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Linked PCOLCE to tumor progression, showing TWIST1-driven expression and N29 glycosylation are required for pro-migratory/pro-metastatic function in osteosarcoma.\",\n      \"evidence\": \"ChIP, luciferase reporter, glycosylation mapping/mutagenesis, shRNA knockdown, and in vivo metastasis model\",\n      \"pmids\": [\"31285765\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether pro-metastatic function depends on procollagen processing unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Demonstrated that PCPE-1 specifically drives collagen fibril deposition in liver fibrosis without altering upstream inflammation or fibrosis-gene transcription, positioning it at the post-translational maturation step.\",\n      \"evidence\": \"Global Pcolce-/- mice in a dietary NASH model with histological and biochemical collagen quantification\",\n      \"pmids\": [\"35148334\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Cellular source of PCPE-1 in liver not identified here\", \"Single lab\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Defined the CUB domains structurally as the procollagen-binding/enhancing module and validated them as a druggable anti-fibrotic target using nanobodies and a biparatopic diabody.\",\n      \"evidence\": \"Crystal structure of PCPE-1/nanobody complex, in vitro inhibition assays, and cell-based processing assays in human dermal fibroblasts\",\n      \"pmids\": [\"38901640\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No structure of PCPE-1 bound to procollagen\", \"In vivo efficacy of antagonists not tested\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Reframed PCPE-1 as an endocrine adipokine, showing BAT-derived PCPE-1 induced by ER stress signaling promotes liver fibrosis systemically.\",\n      \"evidence\": \"BAT-specific and systemic Pcolce knockout/overexpression mice, MASH model, and IRE-1/JNK/c-Fos/c-Jun pathway inhibition\",\n      \"pmids\": [\"39160276\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Receptor/uptake mechanism for circulating PCPE-1 unknown\", \"Whether the same applies to non-hepatic fibrosis pursued separately\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Extended the regulatory map by implicating SOX9 in driving PCOLCE expression and collagen VI secretion in NF1-mutant neurofibroma.\",\n      \"evidence\": \"Proteomics, Western blot, immunofluorescence, transcriptomic validation, and in vivo tumor model\",\n      \"pmids\": [\"38436832\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No direct SOX9 promoter-binding assay for PCOLCE shown\", \"Single lab, transcriptional regulation inferred from perturbation\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Generalized the adipokine paradigm to the heart, showing BAT-derived PCPE-1 induced by aging/ROS signaling drives cardiac fibrosis and diastolic dysfunction in HFpEF.\",\n      \"evidence\": \"Systemic and BAT-specific Pcolce knockout/overexpression mice in aging and obesity models with LV functional and fibrosis readouts\",\n      \"pmids\": [\"41955016\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Target organ receptor for circulating PCPE-1 still unidentified\", \"Translation to human HFpEF untested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How circulating PCPE-1 is taken up by target tissues, and how its nuclear/PABPN1-binding and anti-angiogenic activities relate mechanistically to its procollagen-processing role, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No receptor identified for endocrine PCPE-1\", \"Nuclear function mechanistically uncharacterized\", \"Structural basis of substrate specificity incomplete\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 2, 4, 7, 13]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [0, 1, 2]},\n      {\"term_id\": \"GO:0048018\", \"supporting_discovery_ids\": [14, 16]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": [0, 8, 12]},\n      {\"term_id\": \"GO:0031012\", \"supporting_discovery_ids\": [8, 9]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [4, 5]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [8]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1474244\", \"supporting_discovery_ids\": [0, 2, 9, 12]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [12, 14, 16]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [0, 2, 4, 13]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"BMP1\", \"SDC1\", \"SDC2\", \"SDC4\", \"FN1\", \"B2M\", \"PABPN1\", \"SFRP2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}