{"gene":"CREG1","run_date":"2026-06-09T22:57:19","timeline":{"discoveries":[{"year":2000,"finding":"CREG is a secreted glycoprotein that enhances neuronal differentiation of NTERA-2 human embryonal carcinoma cells; media enriched in CREG promotes differentiation in the absence of retinoic acid, indicating CREG participates in an extracellular signaling cascade for pluripotent cell differentiation.","method":"Northern blot, constitutive overexpression in NTERA-2 cells, conditioned media treatment, morphological and gene expression analysis","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — gain-of-function overexpression plus conditioned media rescue, single lab, two orthogonal approaches","pmids":["10815803"],"is_preprint":false},{"year":2003,"finding":"CREG binds directly to the mannose-6-phosphate/insulin-like growth factor II receptor (M6P/IGF2R) in a glycosylation-dependent manner, and M6P/IGF2R is required for CREG-induced G1/S cell cycle delay and growth inhibition.","method":"Direct binding assay, ectopic expression in NTERA-2 cells, cell cycle analysis in M6P/IGF2R-deficient cells","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct binding assay plus genetic epistasis using receptor-deficient cells, replicated in multiple subsequent studies","pmids":["12934103"],"is_preprint":false},{"year":2005,"finding":"Crystal structure of CREG at 1.9-Å resolution shows it forms a tight homodimer with a beta-barrel fold homologous to FMN-binding split-barrel proteins, but the FMN-binding pocket is sterically blocked. Glycosylation sites map to a patch opposite the dimer interface. A loop-deletion mutant retains overall structure, dimerization, and M6P/IGF2R binding but loses growth suppression activity, demonstrating that M6P/IGF2R binding is necessary but not sufficient for growth suppression.","method":"X-ray crystallography (1.9-Å resolution), site-directed mutagenesis, M6P/IGF2R binding assay, growth assay in NTERA-2 cells","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure combined with mutagenesis and functional validation in a single rigorous study","pmids":["16344469"],"is_preprint":false},{"year":2004,"finding":"CREG overexpression in neonatal rat cardiomyocytes inhibits cell growth and reduces ERK1/2 levels, dampening stretch-induced cardiomyocyte hypertrophy; antisense-mediated CREG knockdown produced the opposite effect, identifying CREG as a novel regulator of ERK1/2 in cardiac hypertrophy.","method":"Overexpression and antisense knockdown in cultured neonatal rat cardiomyocytes and fibroblasts, Western blot for ERK1/2, protein content and cell area measurements, in vivo pressure-overload rat model","journal":"Journal of hypertension","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal gain/loss-of-function in the same cell type, single lab","pmids":["15257182"],"is_preprint":false},{"year":2008,"finding":"CREG promotes a quiescent, differentiated smooth muscle cell (SMC) phenotype; retrovirus-mediated CREG transfer inhibits SMC dedifferentiation, proliferation, and synthesis of fibronectin, and reduces neointimal hyperplasia in balloon-injured rat carotid artery. ShRNA-mediated CREG knockdown abrogates serum starvation-induced SMC differentiation and growth arrest.","method":"Recombinant virus-mediated overexpression and shRNA knockdown in cultured SMCs, in vivo balloon injury rat carotid model, immunostaining, Western blot","journal":"Cardiovascular research","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal gain/loss-of-function in vitro combined with in vivo gene transfer and injury model","pmids":["18267954"],"is_preprint":false},{"year":2008,"finding":"Secreted CREG inhibits NIH3T3 fibroblast proliferation through M6P/IGF2R; CREG knockdown increases IGF-II levels and promotes proliferation, which is rescued by recombinant CREG in a concentration-dependent manner; CREG and M6P/IGF2R interaction confirmed by co-immunoprecipitation and immunofluorescence co-localization, and CREG expression correlates with receptor localization without affecting its expression.","method":"ShRNA knockdown, recombinant protein rescue, FACS, BrdU incorporation, immunoprecipitation-Western blot, immunofluorescence","journal":"Genes to cells : devoted to molecular & cellular mechanisms","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-IP plus functional rescue, single lab, multiple orthogonal methods","pmids":["18691225"],"is_preprint":false},{"year":2009,"finding":"CREG inhibits SMC migration by mediating endocytosis and lysosomal trafficking of IGF-II via M6P/IGF2R; CREG knockdown increases IGF-II secretion and activates PI3K/Akt, promoting migration and MMP-9 activity. Blockade of IGF-II or IGF2R attenuated CREG knockdown-induced migration, and IGF2R antibody or soluble IGF2R fragment inhibited IGF-II endocytosis in CREG-overexpressing cells.","method":"Retroviral CREG overexpression and shRNA knockdown, migration assay, ELISA, endocytosis assay, Western blot for PI3K/Akt, neutralizing antibody and inhibitor blocking experiments","journal":"Experimental cell research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal functional approaches (knockdown, overexpression, blocking), single lab","pmids":["19769965"],"is_preprint":false},{"year":2010,"finding":"CREG binds M6P/IGF2R at extracellular domains 7–10 in a glycosylation-dependent manner and at domains 11–13 in a glycosylation-independent manner; binding to domains 11–13 is sufficient to arrest cell cycle progression of CREG-knockdown SMCs, demonstrating a glycosylation-independent mode of action.","method":"Expression of glycosylation mutant CREG (mCREG) from HEK293 cells, in vitro binding assay with soluble M6P/IGF2R domain fragments, blocking with soluble fragments and neutralizing antibody, cell cycle analysis in CREG-knockdown SMCs","journal":"Journal of molecular and cellular cardiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro binding assay with domain fragments plus functional cell cycle rescue, single lab","pmids":["21195083"],"is_preprint":false},{"year":2011,"finding":"CREG1 co-operates with p16(INK4a) to enhance cellular senescence; co-expression of CREG1 and p16(INK4a) has a greater effect than either alone in reducing cell growth, inducing cell cycle arrest, and inducing senescence in immortal Li-Fraumeni Syndrome fibroblasts, osteosarcoma, and fibrosarcoma lines. CREG1+p16(INK4a) inhibits cyclin A and cyclin B at the promoter/mRNA/protein level.","method":"Ectopic expression, co-expression studies, cell proliferation assays, senescence assays (SA-β-gal), cyclin promoter activity assays, RT-PCR, Western blot","journal":"Cell cycle (Georgetown, Tex.)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional co-expression with promoter activity assays in multiple cancer cell lines, single lab","pmids":["21263217"],"is_preprint":false},{"year":2011,"finding":"CREG overexpression protects endothelial cells from apoptosis via the VEGF/PI3K/AKT signaling pathway; blocking with VEGF neutralizing antibody or PI3K inhibitors (LY294002, wortmannin) abrogated the anti-apoptotic effect of CREG.","method":"Gain- and loss-of-function in HUVECs and apoE-/- mouse arteries, TUNEL staining, caspase-3 assay, neutralizing antibody and PI3K inhibitor blocking","journal":"Atherosclerosis","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal gain/loss-of-function with pathway inhibitor blocking, single lab","pmids":["21872252"],"is_preprint":false},{"year":2015,"finding":"CREG1 is an evolutionarily conserved lysosomal protein that activates cardiomyocyte autophagy and promotes autophagic flux clearance; CREG1 deficiency impairs lysosomal maturation and reduces Rab7 expression, while restoration of CREG1 activates autophagy flux in cardiomyocytes. Chloroquine (lysosomal acidification inhibitor) blocked CREG1-mediated cardioprotection, confirming lysosomal autophagy as the mechanism.","method":"Creg1+/- mouse model, Ang II-induced myocardial fibrosis model, adenoviral overexpression in primary cardiomyocytes, Western blot (LC3II, beclin-1, p62, Rab7), chloroquine inhibitor studies","journal":"Biochimica et biophysica acta","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo haploinsufficiency model plus in vitro adenoviral overexpression and pharmacological inhibitor, multiple orthogonal endpoints, replicated across labs","pmids":["25774384"],"is_preprint":false},{"year":2016,"finding":"CREG1 directly interacts with the exocyst complex component Sec8; this interaction is required for cardiomyocyte differentiation and cell-cell cohesion. CREG1, Sec8, and N-cadherin co-localize at intercalated discs in vivo. CREG1 knockout inhibits the Sec8–N-cadherin interaction and induces their degradation, while CREG1 overexpression enhances adherens and gap junction assembly.","method":"Co-immunoprecipitation, site-directed mutagenesis of CREG1-Sec8 binding site, CREG1 KO ES cell rescue experiments, immunofluorescence co-localization, mouse ES cell to cardiomyocyte differentiation assay","journal":"Stem cells (Dayton, Ohio)","confidence":"High","confidence_rationale":"Tier 1 / Strong — reciprocal co-IP plus mutagenesis plus KO rescue, in vitro and in vivo co-localization","pmids":["27334848"],"is_preprint":false},{"year":2016,"finding":"CREG protects cardiomyocytes against MI/R injury-induced apoptosis by activating lysosomal autophagy; CREG involvement in lysosomal protein transfer improves cellular autophagy flux. In Creg+/- mice, dysfunctional autophagy (LC3A and p62 accumulation) and increased apoptosis were observed, while recombinant CREG infusion activated autophagy and reduced apoptosis. Chloroquine (autophagy blocker) abolished CREG protection.","method":"Creg+/- mice and recombinant CREG protein infusion, MI/R model (LAD ligation), Evans Blue-TTC staining, echocardiography, Western blot (LC3A, p62, cleaved caspase-3), TUNEL staining, chloroquine inhibitor","journal":"Biochimica et biophysica acta. Molecular basis of disease","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo haploinsufficiency and gain-of-function (recombinant protein), pharmacological autophagy blockade, multiple orthogonal readouts","pmids":["27840305"],"is_preprint":false},{"year":2016,"finding":"CREG transcription is regulated by the transcription factor GATA1 binding to the CREG promoter at position -297/-292; deletion mutation at this site disrupted GATA1 binding and reduced CREG transcription by ~83.3%. GATA1 overexpression abrogated high glucose/palmitate-induced HUVEC apoptosis through upregulation of CREG.","method":"Promoter-binding transcription-factor profiling array, ChIP assay, deletion mutation analysis, GATA1 overexpression in HUVECs, apoptosis assays","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP plus deletion mutagenesis of promoter, single lab","pmids":["27139506"],"is_preprint":false},{"year":2017,"finding":"CREG directly interacts with apoptosis signal-regulating kinase 1 (ASK1) and inhibits its phosphorylation, thereby blocking the downstream MKK4/7-JNK1 (but not JNK2) signaling pathway; hepatocyte-specific CREG deletion exacerbated obesity, hepatic steatosis, and insulin resistance, while CREG overexpression was protective. JNK1 inhibition prevented the adverse effects of CREG deletion.","method":"Hepatocyte-specific CREG KO and overexpression mouse models, co-immunoprecipitation, Western blot for ASK1 phosphorylation and MKK4/7-JNK1 pathway, HFD and ob/ob models","journal":"Hepatology (Baltimore, Md.)","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct interaction (co-IP), conditional KO and overexpression in vivo, pathway epistasis with JNK1 inhibitor, replicated in two genetic models","pmids":["28508477"],"is_preprint":false},{"year":2019,"finding":"Creg in hepatocytes suppresses MAPK signaling by directly binding to TAK1 (TGF-β-activated kinase 1) and inhibiting TAK1 phosphorylation; hepatocyte-specific CREG KO increased cell death and inflammatory cytokines after hepatic I/R. Mutating the TAK1-binding domain of CREG or pharmacologically inhibiting TAK1 abolished CREG protection, confirming the Creg-TAK1 interaction is required.","method":"Hepatocyte-specific Creg KO and transgenic mice, hepatic I/R model, hypoxia/reoxygenation in primary hepatocytes, molecular binding experiments (pull-down/co-IP), TAK1 binding domain mutagenesis, TAK1 inhibitor (5Z-7-ox)","journal":"Hepatology (Baltimore, Md.)","confidence":"High","confidence_rationale":"Tier 1 / Strong — mutagenesis of binding domain combined with pharmacological inhibitor rescue, conditional KO in vivo, multiple orthogonal endpoints","pmids":["30076625"],"is_preprint":false},{"year":2019,"finding":"CREG1 binds to retinoid X receptor α (RXRα), which interacts with thyroid hormone receptor to promote brown adipogenesis; CREG1 transgenic mice show elevated UCP1 and FGF-21 expression in BAT and WAT, increased browning, and resistance to diet-induced obesity.","method":"CREG1 transgenic mice, BAT primary cultures, co-binding/interaction assays for RXRα, UCP1 reporter assay, β3-adrenergic agonist challenge, metabolic phenotyping","journal":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — binding to RXRα demonstrated in vitro, gain-of-function transgenic model, single lab","pmids":["30917000"],"is_preprint":false},{"year":2020,"finding":"DNMT3B-mediated hypermethylation of the CREG promoter (at CG site +201/+202 bp) suppresses CREG expression by blocking binding of the transcription factor GR-α; ox-LDL increases DNMT3B expression, leading to CREG promoter hypermethylation and endothelial dysfunction. 5-aza-dC (DNMT inhibitor) restored CREG expression and activated p-eNOS/NO signaling.","method":"DNMT3B overexpression/inhibition in HUVECs, CREG promoter methylation analysis, ChIP for GR-α binding, 5-aza-dC treatment, site-specific methylation characterization","journal":"Redox biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP assay plus promoter mutation plus pharmacological demethylation, single lab","pmids":["32067910"],"is_preprint":false},{"year":2021,"finding":"CREG1 is mainly localized to the endosomal-lysosomal compartment (validated by antibodies through gain- and loss-of-function studies) and promotes both macropinocytosis and clathrin-dependent endocytosis, acidification of the endosomal-lysosomal compartment, and lysosomal biogenesis. CREG1 overexpression enhances autophagy and lysosome-mediated degradation; knockdown or knockout has opposite effects.","method":"Immunofluorescence microscopy with validated antibodies, gain- and loss-of-function (overexpression and KO), endocytosis assays, lysosomal acidification assay, autophagy flux assays","journal":"Autophagy","confidence":"High","confidence_rationale":"Tier 2 / Strong — subcellular localization validated with KO controls plus reciprocal gain/loss-of-function for endocytosis and lysosomal biogenesis, multiple orthogonal methods","pmids":["33966596"],"is_preprint":false},{"year":2021,"finding":"CREG1 localizes to mitochondria in skeletal muscle cells and modulates mitophagy; CREG1 deficiency accelerates mitophagy induction (increased PINK1/PARKIN) and impairs mitochondrial quality. HSPD1/HSP60 (residues 401-573) directly interacts with CREG1 (residues 130-220) to antagonize CREG1 degradation and is involved in mitophagy regulation.","method":"Skeletal muscle-specific creg1 KO mice (Creg1;Ckm-Cre), recombinant CREG1 protein administration, electron microscopy, Western blot for PINK1/PARKIN/mitochondrial proteins, gain/loss-of-function in C2C12 cells, immunoprecipitation for HSPD1-CREG1 interaction, domain mapping","journal":"Autophagy","confidence":"High","confidence_rationale":"Tier 2 / Strong — tissue-specific KO in vivo plus domain-specific co-IP, electron microscopy, multiple orthogonal endpoints","pmids":["33726618"],"is_preprint":false},{"year":2021,"finding":"CREG inhibits the phenotypic switching of cardiac fibroblasts to myofibroblasts after MI by suppressing CDC42 expression; recombinant CREG protein blocked hypoxia-induced proliferation and migration of cardiac fibroblasts through inhibition of CDC42.","method":"Creg+/- mice post-MI model, recombinant CREG protein treatment, in vitro hypoxia model with cardiac fibroblasts, Western blot for αSMA, collagen-1, CDC42, proliferation and migration assays","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo haploinsufficiency and in vitro recombinant protein, single mechanism target (CDC42), single lab","pmids":["33824277"],"is_preprint":false},{"year":2022,"finding":"CREG promotes differentiation of embryonic stem cells into smooth muscle cells through the TGF-β/Smad2/3 signaling pathway; CREG-KO ESCs showed significantly decreased SMC marker expression and reduced contractile capacity, while CREG-OE ESCs showed the opposite.","method":"CREG overexpression and shRNA KO in ESCs, SMC differentiation assay, Western blot for SMC markers (SM α-actin, SM22, calponin, SM-MHC), calcium ion assay, contractility assay","journal":"Differentiation; research in biological diversity","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal gain/loss-of-function, pathway identification via TGF-β/Smad2/3, single lab","pmids":["35349881"],"is_preprint":false},{"year":2022,"finding":"CREG1 stimulates AMPK phosphorylation (at Thr172) and GLUT4 expression/glucose uptake in skeletal muscle cells through IGF2R; CREG1-induced AMPKα phosphorylation and 2-deoxyglucose uptake were suppressed by IGF2R knockdown and by Compound C (AMPK inhibitor), establishing CREG1-IGF2R-AMPK as a signaling axis.","method":"CREG1 treatment of C2C12 myotubes, IGF2R knockdown, AMPK inhibitor (Compound C), Western blot for phospho-AMPKα, GLUT4, 2-deoxyglucose uptake assay, CTX-induced muscle regeneration mouse model","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pharmacological and genetic (siRNA) pathway dissection in vitro, single lab","pmids":["36528955"],"is_preprint":false},{"year":2023,"finding":"CREG1 inhibits LAMP2 protein degradation by suppressing the expression of F-box protein 27 (FBXO27), thereby promoting autophagy in cardiomyocytes; LAMP2 overexpression reversed the effect of CREG1 knockdown on palmitate-induced inhibition of cardiomyocyte autophagy, defining a CREG1-FBXO27-LAMP2 axis.","method":"Cardiac-specific Creg1 KO and transgenic mice, diabetic cardiomyopathy model, palmitate-stimulated NMCMs, Western blot, CREG1 overexpression and knockdown with adenovirus/siRNA, LAMP2 overexpression rescue","journal":"Experimental & molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO/overexpression in vivo, rescue experiment with LAMP2, mechanistic pathway delineated, single lab","pmids":["37658156"],"is_preprint":false},{"year":2023,"finding":"CREG1 directly interacts with MEK1/2 and promotes MEK1/2 phosphorylation in megakaryocytes; CREG1 deficiency impairs actin cytoskeleton, proplatelet formation, and ploidy, causing thrombocytopenia due to inefficient bone marrow thrombocytopoiesis.","method":"Megakaryocyte/platelet conditional KO and transgenic mice, cytosine arabinoside thrombocytopenia model, immunoprecipitation for MEK1/2-CREG1, Western blot for MEK1/2 phosphorylation, F-actin staining, ploidy assay","journal":"International journal of biological sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP plus conditional KO model with defined cellular phenotype, single lab","pmids":["37496998"],"is_preprint":false},{"year":2024,"finding":"CREG1 deficiency inhibits myoblast differentiation and skeletal muscle regeneration by promoting C-CBL E3-ubiquitin ligase-mediated K48-linked polyubiquitination and degradation of AMPKα1 at K396; silencing C-CBL in CREG1 knockout mice significantly improved muscle regeneration, establishing CREG1-C-CBL-AMPKα1 as a regulatory axis.","method":"Creg1 KO and satellite cell-specific overexpression mice (AAV9), cardiotoxin muscle injury model, mass spectrometry, RNA-seq, AAV-sh-C-Cbl rescue, Western blot for AMPKα1 ubiquitination, C2C12 cell transfection","journal":"Journal of cachexia, sarcopenia and muscle","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic rescue with C-CBL silencing, ubiquitination site mapping by mass spectrometry, single lab","pmids":["38272853"],"is_preprint":false},{"year":2024,"finding":"CREG1 inhibits ferroptosis in cardiomyocytes by suppressing PDK4 mRNA and protein expression through the FBXW7-FOXO1 signaling pathway; CREG1-FBXW7-FOXO1-PDK4 is a defined mechanistic axis, and PDK4 deficiency reverses the effects of CREG1 knockdown on DOX-induced ferroptosis.","method":"CREG1 transgenic and cardiac-specific KO mice, DOX-induced cardiotoxicity model, transcriptomics, immunoprecipitation, siRNA knockdown of PDK4, Western blot","journal":"Redox biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — transcriptomics plus immunoprecipitation plus PDK4 knockdown rescue, single lab","pmids":["39094399"],"is_preprint":false},{"year":2024,"finding":"CREG1 promotes exosome genesis and release in bovine placental trophoblast cells by targeting IGF2R; IGF2R knockdown inhibited exosome genesis and blocked CREG1-induced exosome production. IGF2R can also reverse-regulate CREG1 expression. CREG1 binding to IGF2R subsequently activates Rab11 to facilitate exosome release.","method":"Creg1 overexpression and Igf2r siRNA knockdown in bovine trophoblast cells, exosome isolation and quantification, co-immunoprecipitation, Western blot","journal":"International journal of biological macromolecules","confidence":"Low","confidence_rationale":"Tier 3 / Weak — co-IP and knockdown experiments, single lab, non-canonical model organism (bovine) with limited mechanistic follow-up","pmids":["38917918"],"is_preprint":false},{"year":2024,"finding":"In zebrafish, loss of creg1 causes anemia due to defective erythroid differentiation and excessive apoptosis of erythroid progenitors; mechanistically, creg1 deficiency reduces TGF-β/Smad2 signaling pathway activation, and Klf1 is a downstream target of this pathway required for normal erythropoiesis. Treatment with a Smad2 agonist (IDE2) restores erythroid development in creg1-/- mutants.","method":"Zebrafish creg1 knockout, scRNA-seq, Smad2 agonist (IDE2) rescue, gene expression analysis, epistasis with Klf1","journal":"Advanced science (Weinheim, Baden-Wurttemberg, Germany)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO in zebrafish with pharmacological rescue and downstream target identification, single lab","pmids":["38953462"],"is_preprint":false},{"year":2025,"finding":"CREG1-IGF2R-PI3K-AKT signaling mediates TREM2+ macrophage-promoted osteogenic differentiation of ligament-derived progenitor cells in ankylosing spondylitis; TREM2+ macrophages secrete CREG1 to drive pathological new bone formation, and targeting this axis alleviates new bone formation in a collagen antibody-induced arthritis model.","method":"TREM2+ macrophage depletion and Trem2 knockout in CAIA model, CREG1 secretion assay, CREG1-IGF2R-PI3K-AKT pathway inhibition, osteogenic differentiation of LDPCs","journal":"Advanced science (Weinheim, Baden-Wurttemberg, Germany)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo KO model plus signaling pathway inhibition, single lab","pmids":["40091508"],"is_preprint":false},{"year":2025,"finding":"CREG1 is localized to endolysosomal and autophagosomal compartments in cardiomyocytes; loss of CREG1 impairs autophagy flux and mitophagy by impairing autophagosome membrane expansion and degradation. Global Creg1 KO mice develop cardiac hypertrophy, fibrosis, and diastolic dysfunction at ~80 weeks; cardiomyocyte-specific CREG1 overexpression (KI) enhances exercise capacity under nutritional stress.","method":"Global Creg1 KO (entire ORF deletion) and Rosa26-CREG1 KI mice, cm-specific Creg1 KO and KI, autophagy reporter (CAG-EGFP-RFP-LC3), electron microscopy, biochemical autophagy assays, cardiac phenotyping","journal":"bioRxiv : the preprint server for biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — true KO (full ORF deletion) plus gain-of-function KI, autophagy reporter, multiple endpoints; preprint not yet peer-reviewed","pmids":["41292877"],"is_preprint":true},{"year":2020,"finding":"CREG1 is cleaved by cathepsin B in vitro, and cathepsin B overexpression reduces secreted CREG1 levels while cathepsin B deletion or inhibition increases them; reduced CREG1 expression promotes proliferation, migration, and invasion of PyMT breast tumor cells, establishing cathepsin B as a negative regulator of CREG1 in the tumor microenvironment.","method":"Cathepsin B overexpression/deletion in MMTV-PyMT mouse model, in vitro cleavage assay, conditioned media/tumor interstitial fluid proteomics (SILAC), recombinant CREG1 treatment, orthotopic transplantation","journal":"Cellular and molecular life sciences : CMLS","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — in vitro cleavage assay plus in vivo cathepsin B KO model, single lab","pmids":["32385587"],"is_preprint":false}],"current_model":"CREG1 is an endolysosomal glycoprotein that can be secreted; it inhibits cell proliferation and promotes differentiation by binding M6P/IGF2R (in glycosylation-dependent and -independent modes) and signaling through multiple pathways including ERK1/2, VEGF/PI3K/AKT, ASK1-MKK4/7-JNK1, and TAK1-MAPK; it promotes lysosomal biogenesis, endocytic trafficking, and autophagic/mitophagic flux (partly via Rab7 and HSPD1), directly interacts with the exocyst component Sec8 to promote cardiomyocyte junction assembly, activates MEK1/2 in megakaryocytes, regulates ferroptosis via FBXW7-FOXO1-PDK4, and regulates erythropoiesis through TGF-β/Smad2-Klf1 signaling, with its transcription controlled by GATA1 and epigenetically silenced by DNMT3B-mediated promoter methylation."},"narrative":{"mechanistic_narrative":"CREG1 is a secreted and endolysosomal glycoprotein that restrains cell proliferation and promotes differentiation across multiple lineages [PMID:10815803, PMID:18267954]. Its canonical extracellular activity proceeds through direct binding to the mannose-6-phosphate/IGF2 receptor (M6P/IGF2R), engaging receptor domains 7–10 in a glycosylation-dependent manner and domains 11–13 independently of glycosylation; receptor binding is required for CREG1-induced G1/S cell-cycle delay and growth inhibition [PMID:12934103, PMID:21195083]. Structurally, CREG1 forms a tight homodimer with an FMN-binding split-barrel fold in which the cofactor pocket is sterically blocked, and a loop mutant that retains dimerization and receptor binding yet loses growth suppression shows that M6P/IGF2R engagement is necessary but not sufficient for its anti-proliferative effect [PMID:16344469]. Through M6P/IGF2R-dependent endocytosis CREG1 controls IGF-II trafficking and downstream PI3K/Akt signaling, governing smooth muscle quiescence and migration [PMID:19769965], and the same receptor couples CREG1 to AMPK activation and glucose uptake in skeletal muscle [PMID:36528955]. A major function of CREG1 is in the endosomal-lysosomal system, where it localizes and promotes endocytosis, lysosomal acidification, lysosomal biogenesis, and autophagic and mitophagic flux [PMID:33966596, PMID:33726618]; in cardiomyocytes it sustains autophagy and is cardioprotective, acting in part through Rab7, the FBXO27-LAMP2 axis, and interaction with HSPD1 in mitochondria [PMID:25774384, PMID:27840305, PMID:37658156, PMID:33726618]. CREG1 additionally acts through direct protein interactions to shape signaling: it binds and inhibits ASK1 (blocking MKK4/7-JNK1) and TAK1 to protect hepatocytes [PMID:28508477, PMID:30076625], binds the exocyst component Sec8 to drive cardiomyocyte junction assembly and differentiation [PMID:27334848], and binds MEK1/2 to promote megakaryocyte thrombopoiesis [PMID:37496998]. It directs differentiation programs via TGF-β/Smad2 signaling in smooth muscle and erythropoiesis [PMID:35349881, PMID:38953462] and regulates cardiomyocyte ferroptosis through an FBXW7-FOXO1-PDK4 axis [PMID:39094399]. CREG1 expression is controlled transcriptionally by GATA1 and is epigenetically silenced by DNMT3B-mediated promoter hypermethylation [PMID:27139506, PMID:32067910].","teleology":[{"year":2000,"claim":"Established CREG1 as a secreted factor acting in an extracellular differentiation cascade, framing it as a signaling protein rather than a purely intracellular one.","evidence":"Overexpression and conditioned-media rescue in NTERA-2 embryonal carcinoma cells","pmids":["10815803"],"confidence":"Medium","gaps":["No receptor or molecular mechanism identified","Single cell model, gain-of-function only"]},{"year":2003,"claim":"Identified M6P/IGF2R as the functional receptor for CREG1, answering how a secreted protein transduces growth arrest.","evidence":"Direct binding assay plus cell-cycle analysis in M6P/IGF2R-deficient cells","pmids":["12934103"],"confidence":"High","gaps":["Downstream signaling from the receptor not defined","Glycosylation requirement not yet dissected"]},{"year":2005,"claim":"Resolved the CREG1 fold and showed that receptor binding alone does not confer growth suppression, separating binding from activity.","evidence":"1.9-Å crystal structure with loop-deletion mutagenesis and growth assays","pmids":["16344469"],"confidence":"High","gaps":["The FMN pocket is blocked but no enzymatic activity assigned","Structural basis of the activity beyond binding unknown"]},{"year":2004,"claim":"Connected CREG1 to MAPK signaling by showing it represses ERK1/2 to limit cardiomyocyte hypertrophy.","evidence":"Reciprocal overexpression/antisense in rat cardiomyocytes plus pressure-overload model","pmids":["15257182"],"confidence":"Medium","gaps":["Mechanism of ERK1/2 regulation not molecular","Direct vs indirect effect unresolved"]},{"year":2010,"claim":"Defined two binding modes (glycosylation-dependent domains 7–10 and independent domains 11–13) and showed the independent mode suffices for cell-cycle arrest.","evidence":"In vitro binding with M6P/IGF2R domain fragments plus cell-cycle rescue in knockdown SMCs; combined with IGF-II endocytosis/PI3K-Akt findings","pmids":["21195083","19769965","18691225"],"confidence":"Medium","gaps":["Structural basis of dual binding modes not solved","Single-lab vascular models"]},{"year":2015,"claim":"Reframed CREG1 as a lysosomal/autophagy regulator, showing it promotes lysosomal maturation and autophagic flux, partly via Rab7.","evidence":"Creg1+/- mice, adenoviral rescue in cardiomyocytes, chloroquine blockade","pmids":["25774384","27840305"],"confidence":"High","gaps":["Molecular mechanism of lysosomal maturation control undefined","Link between secreted and intracellular pools unclear"]},{"year":2016,"claim":"Identified direct protein partners (Sec8) and transcriptional control (GATA1), expanding CREG1 mechanism beyond M6P/IGF2R.","evidence":"Co-IP and mutagenesis with KO-ES-cell rescue for Sec8; ChIP and promoter mutagenesis for GATA1","pmids":["27334848","27139506"],"confidence":"High","gaps":["How Sec8 binding integrates with lysosomal roles unknown","GATA1 regulation tested mainly in endothelial context"]},{"year":2019,"claim":"Established CREG1 as a direct kinase inhibitor, binding ASK1 and TAK1 to suppress JNK1 and MAPK signaling in hepatocytes.","evidence":"Conditional hepatocyte KO/transgenic mice, co-IP, binding-domain mutagenesis, pathway-inhibitor epistasis","pmids":["28508477","30076625"],"confidence":"High","gaps":["Structural basis of kinase binding not solved","Relationship to lysosomal/receptor functions unresolved"]},{"year":2021,"claim":"Consolidated CREG1 subcellular biology, localizing it to endolysosomes and mitochondria and defining roles in endocytosis, lysosomal biogenesis, and mitophagy with the HSPD1 partner.","evidence":"Validated immunofluorescence with KO controls, reciprocal gain/loss-of-function, tissue-specific KO, domain-mapped HSPD1 co-IP","pmids":["33966596","33726618"],"confidence":"High","gaps":["Whether mitochondrial and lysosomal pools are functionally distinct unclear","Mechanism coupling CREG1 to membrane trafficking machinery incomplete"]},{"year":2024,"claim":"Extended CREG1 mechanism to ubiquitin-proteasome and ferroptosis control via defined axes (C-CBL-AMPKα1, FBXW7-FOXO1-PDK4) and to TGF-β/Smad2-Klf1-driven erythropoiesis.","evidence":"KO/transgenic mice, mass-spectrometry ubiquitination mapping, genetic rescue, zebrafish KO with Smad2 agonist rescue","pmids":["38272853","39094399","38953462"],"confidence":"Medium","gaps":["Direct vs indirect control of E3 ligase expression unresolved","Single-lab mechanistic axes"]},{"year":null,"claim":"How CREG1's many activities—receptor binding, kinase inhibition, lysosomal biogenesis, and transcriptional axes—are integrated by a single split-barrel protein with a blocked cofactor pocket remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unifying biochemical activity assigned to the fold","Spatial/functional relationship between secreted and intracellular pools undefined","No human disease mutation reported in the corpus"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[14,15]},{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[1,7]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[11]}],"localization":[{"term_id":"GO:0005764","term_label":"lysosome","supporting_discovery_ids":[18,10,30]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[18]},{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[19]},{"term_id":"GO:0005576","term_label":"extracellular region","supporting_discovery_ids":[0,5]}],"pathway":[{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[10,12,18,23]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[14,15,9,22]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[1,2,8]},{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[6,18]}],"complexes":["exocyst (via Sec8)"],"partners":["IGF2R","SEC8","ASK1","TAK1","MEK1/2","HSPD1","RXRA"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O75629","full_name":"Protein CREG1","aliases":["Cellular repressor of E1A-stimulated genes 1"],"length_aa":220,"mass_kda":24.1,"function":"May contribute to the transcriptional control of cell growth and differentiation. 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hematopoiesis revealed by single-cell RNA sequencing.","date":"2025","source":"Cell & bioscience","url":"https://pubmed.ncbi.nlm.nih.gov/40452027","citation_count":0,"is_preprint":false},{"pmid":"40297152","id":"PMC_40297152","title":"The mechanism by which MALAT1/CREG1 regulates premature rupture of fetal membrane through autophagy mediated differentiation of amniotic fibroblasts.","date":"2025","source":"Non-coding RNA research","url":"https://pubmed.ncbi.nlm.nih.gov/40297152","citation_count":0,"is_preprint":false},{"pmid":"41577020","id":"PMC_41577020","title":"CREG1 promotes bone formation via targeting RAB7 to activate autophagy in osteoporosis.","date":"2026","source":"Cellular signalling","url":"https://pubmed.ncbi.nlm.nih.gov/41577020","citation_count":0,"is_preprint":false},{"pmid":"41646965","id":"PMC_41646965","title":"CREG1 restricts ALV-J replication via the mitochondrial dysfunction-driven activation of innate immunity and apoptosis.","date":"2026","source":"Frontiers in immunology","url":"https://pubmed.ncbi.nlm.nih.gov/41646965","citation_count":0,"is_preprint":false},{"pmid":"41292877","id":"PMC_41292877","title":"CREG1 promotes autophagy and protects the heart against nutritional stress-induced injury and age-associated hypertrophy, fibrosis and diastolic dysfunction.","date":"2025","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/41292877","citation_count":0,"is_preprint":false},{"pmid":"41693246","id":"PMC_41693246","title":"CREG1 Attenuates Osteoarthritis Progression by Suppressing Chondrocyte Pyroptosis Through the PINK1/Parkin-Mediated Mitophagy Pathway.","date":"2026","source":"Biotechnology journal","url":"https://pubmed.ncbi.nlm.nih.gov/41693246","citation_count":0,"is_preprint":false},{"pmid":"21038674","id":"PMC_21038674","title":"[Purification and functional identification of the recombinant human CREG/myc-His glycoprotein].","date":"2010","source":"Zhongguo ying yong sheng li xue za zhi = Zhongguo yingyong shenglixue zazhi = Chinese journal of applied physiology","url":"https://pubmed.ncbi.nlm.nih.gov/21038674","citation_count":0,"is_preprint":false},{"pmid":"12513720","id":"PMC_12513720","title":"[Selection of donor in mismatched hematopoietic stem cell transplantation by CREG, residue match and HLA three-dimensional structure].","date":"2002","source":"Zhongguo shi yan xue ye xue za zhi","url":"https://pubmed.ncbi.nlm.nih.gov/12513720","citation_count":0,"is_preprint":false},{"pmid":"12028545","id":"PMC_12028545","title":"Description of six new HLA-B alleles in the 5C CREG including a B*58 intron two sequence.","date":"2002","source":"Tissue antigens","url":"https://pubmed.ncbi.nlm.nih.gov/12028545","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.08.18.670803","title":"CREG1 restricts ALV-J replication via the mitochondrial dysfunction–driven activation of innate immunity and apoptosis","date":"2025-08-22","source":"bioRxiv","url":"https://doi.org/10.1101/2025.08.18.670803","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":40022,"output_tokens":8999,"usd":0.127526,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":18849,"output_tokens":3801,"usd":0.094635,"stage2_stop_reason":"end_turn"},"total_usd":0.222161,"stage1_batch_id":"msgbatch_01ACAxJQabDsht39JXeWG22d","stage2_batch_id":"msgbatch_01QEU22A9U5sbPTgsMzTmvSf","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2000,\n      \"finding\": \"CREG is a secreted glycoprotein that enhances neuronal differentiation of NTERA-2 human embryonal carcinoma cells; media enriched in CREG promotes differentiation in the absence of retinoic acid, indicating CREG participates in an extracellular signaling cascade for pluripotent cell differentiation.\",\n      \"method\": \"Northern blot, constitutive overexpression in NTERA-2 cells, conditioned media treatment, morphological and gene expression analysis\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — gain-of-function overexpression plus conditioned media rescue, single lab, two orthogonal approaches\",\n      \"pmids\": [\"10815803\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"CREG binds directly to the mannose-6-phosphate/insulin-like growth factor II receptor (M6P/IGF2R) in a glycosylation-dependent manner, and M6P/IGF2R is required for CREG-induced G1/S cell cycle delay and growth inhibition.\",\n      \"method\": \"Direct binding assay, ectopic expression in NTERA-2 cells, cell cycle analysis in M6P/IGF2R-deficient cells\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct binding assay plus genetic epistasis using receptor-deficient cells, replicated in multiple subsequent studies\",\n      \"pmids\": [\"12934103\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Crystal structure of CREG at 1.9-Å resolution shows it forms a tight homodimer with a beta-barrel fold homologous to FMN-binding split-barrel proteins, but the FMN-binding pocket is sterically blocked. Glycosylation sites map to a patch opposite the dimer interface. A loop-deletion mutant retains overall structure, dimerization, and M6P/IGF2R binding but loses growth suppression activity, demonstrating that M6P/IGF2R binding is necessary but not sufficient for growth suppression.\",\n      \"method\": \"X-ray crystallography (1.9-Å resolution), site-directed mutagenesis, M6P/IGF2R binding assay, growth assay in NTERA-2 cells\",\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 combined with mutagenesis and functional validation in a single rigorous study\",\n      \"pmids\": [\"16344469\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"CREG overexpression in neonatal rat cardiomyocytes inhibits cell growth and reduces ERK1/2 levels, dampening stretch-induced cardiomyocyte hypertrophy; antisense-mediated CREG knockdown produced the opposite effect, identifying CREG as a novel regulator of ERK1/2 in cardiac hypertrophy.\",\n      \"method\": \"Overexpression and antisense knockdown in cultured neonatal rat cardiomyocytes and fibroblasts, Western blot for ERK1/2, protein content and cell area measurements, in vivo pressure-overload rat model\",\n      \"journal\": \"Journal of hypertension\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal gain/loss-of-function in the same cell type, single lab\",\n      \"pmids\": [\"15257182\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"CREG promotes a quiescent, differentiated smooth muscle cell (SMC) phenotype; retrovirus-mediated CREG transfer inhibits SMC dedifferentiation, proliferation, and synthesis of fibronectin, and reduces neointimal hyperplasia in balloon-injured rat carotid artery. ShRNA-mediated CREG knockdown abrogates serum starvation-induced SMC differentiation and growth arrest.\",\n      \"method\": \"Recombinant virus-mediated overexpression and shRNA knockdown in cultured SMCs, in vivo balloon injury rat carotid model, immunostaining, Western blot\",\n      \"journal\": \"Cardiovascular research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal gain/loss-of-function in vitro combined with in vivo gene transfer and injury model\",\n      \"pmids\": [\"18267954\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Secreted CREG inhibits NIH3T3 fibroblast proliferation through M6P/IGF2R; CREG knockdown increases IGF-II levels and promotes proliferation, which is rescued by recombinant CREG in a concentration-dependent manner; CREG and M6P/IGF2R interaction confirmed by co-immunoprecipitation and immunofluorescence co-localization, and CREG expression correlates with receptor localization without affecting its expression.\",\n      \"method\": \"ShRNA knockdown, recombinant protein rescue, FACS, BrdU incorporation, immunoprecipitation-Western blot, immunofluorescence\",\n      \"journal\": \"Genes to cells : devoted to molecular & cellular mechanisms\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-IP plus functional rescue, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"18691225\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"CREG inhibits SMC migration by mediating endocytosis and lysosomal trafficking of IGF-II via M6P/IGF2R; CREG knockdown increases IGF-II secretion and activates PI3K/Akt, promoting migration and MMP-9 activity. Blockade of IGF-II or IGF2R attenuated CREG knockdown-induced migration, and IGF2R antibody or soluble IGF2R fragment inhibited IGF-II endocytosis in CREG-overexpressing cells.\",\n      \"method\": \"Retroviral CREG overexpression and shRNA knockdown, migration assay, ELISA, endocytosis assay, Western blot for PI3K/Akt, neutralizing antibody and inhibitor blocking experiments\",\n      \"journal\": \"Experimental cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal functional approaches (knockdown, overexpression, blocking), single lab\",\n      \"pmids\": [\"19769965\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"CREG binds M6P/IGF2R at extracellular domains 7–10 in a glycosylation-dependent manner and at domains 11–13 in a glycosylation-independent manner; binding to domains 11–13 is sufficient to arrest cell cycle progression of CREG-knockdown SMCs, demonstrating a glycosylation-independent mode of action.\",\n      \"method\": \"Expression of glycosylation mutant CREG (mCREG) from HEK293 cells, in vitro binding assay with soluble M6P/IGF2R domain fragments, blocking with soluble fragments and neutralizing antibody, cell cycle analysis in CREG-knockdown SMCs\",\n      \"journal\": \"Journal of molecular and cellular cardiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro binding assay with domain fragments plus functional cell cycle rescue, single lab\",\n      \"pmids\": [\"21195083\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"CREG1 co-operates with p16(INK4a) to enhance cellular senescence; co-expression of CREG1 and p16(INK4a) has a greater effect than either alone in reducing cell growth, inducing cell cycle arrest, and inducing senescence in immortal Li-Fraumeni Syndrome fibroblasts, osteosarcoma, and fibrosarcoma lines. CREG1+p16(INK4a) inhibits cyclin A and cyclin B at the promoter/mRNA/protein level.\",\n      \"method\": \"Ectopic expression, co-expression studies, cell proliferation assays, senescence assays (SA-β-gal), cyclin promoter activity assays, RT-PCR, Western blot\",\n      \"journal\": \"Cell cycle (Georgetown, Tex.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional co-expression with promoter activity assays in multiple cancer cell lines, single lab\",\n      \"pmids\": [\"21263217\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"CREG overexpression protects endothelial cells from apoptosis via the VEGF/PI3K/AKT signaling pathway; blocking with VEGF neutralizing antibody or PI3K inhibitors (LY294002, wortmannin) abrogated the anti-apoptotic effect of CREG.\",\n      \"method\": \"Gain- and loss-of-function in HUVECs and apoE-/- mouse arteries, TUNEL staining, caspase-3 assay, neutralizing antibody and PI3K inhibitor blocking\",\n      \"journal\": \"Atherosclerosis\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal gain/loss-of-function with pathway inhibitor blocking, single lab\",\n      \"pmids\": [\"21872252\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"CREG1 is an evolutionarily conserved lysosomal protein that activates cardiomyocyte autophagy and promotes autophagic flux clearance; CREG1 deficiency impairs lysosomal maturation and reduces Rab7 expression, while restoration of CREG1 activates autophagy flux in cardiomyocytes. Chloroquine (lysosomal acidification inhibitor) blocked CREG1-mediated cardioprotection, confirming lysosomal autophagy as the mechanism.\",\n      \"method\": \"Creg1+/- mouse model, Ang II-induced myocardial fibrosis model, adenoviral overexpression in primary cardiomyocytes, Western blot (LC3II, beclin-1, p62, Rab7), chloroquine inhibitor studies\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo haploinsufficiency model plus in vitro adenoviral overexpression and pharmacological inhibitor, multiple orthogonal endpoints, replicated across labs\",\n      \"pmids\": [\"25774384\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"CREG1 directly interacts with the exocyst complex component Sec8; this interaction is required for cardiomyocyte differentiation and cell-cell cohesion. CREG1, Sec8, and N-cadherin co-localize at intercalated discs in vivo. CREG1 knockout inhibits the Sec8–N-cadherin interaction and induces their degradation, while CREG1 overexpression enhances adherens and gap junction assembly.\",\n      \"method\": \"Co-immunoprecipitation, site-directed mutagenesis of CREG1-Sec8 binding site, CREG1 KO ES cell rescue experiments, immunofluorescence co-localization, mouse ES cell to cardiomyocyte differentiation assay\",\n      \"journal\": \"Stem cells (Dayton, Ohio)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — reciprocal co-IP plus mutagenesis plus KO rescue, in vitro and in vivo co-localization\",\n      \"pmids\": [\"27334848\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"CREG protects cardiomyocytes against MI/R injury-induced apoptosis by activating lysosomal autophagy; CREG involvement in lysosomal protein transfer improves cellular autophagy flux. In Creg+/- mice, dysfunctional autophagy (LC3A and p62 accumulation) and increased apoptosis were observed, while recombinant CREG infusion activated autophagy and reduced apoptosis. Chloroquine (autophagy blocker) abolished CREG protection.\",\n      \"method\": \"Creg+/- mice and recombinant CREG protein infusion, MI/R model (LAD ligation), Evans Blue-TTC staining, echocardiography, Western blot (LC3A, p62, cleaved caspase-3), TUNEL staining, chloroquine inhibitor\",\n      \"journal\": \"Biochimica et biophysica acta. Molecular basis of disease\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo haploinsufficiency and gain-of-function (recombinant protein), pharmacological autophagy blockade, multiple orthogonal readouts\",\n      \"pmids\": [\"27840305\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"CREG transcription is regulated by the transcription factor GATA1 binding to the CREG promoter at position -297/-292; deletion mutation at this site disrupted GATA1 binding and reduced CREG transcription by ~83.3%. GATA1 overexpression abrogated high glucose/palmitate-induced HUVEC apoptosis through upregulation of CREG.\",\n      \"method\": \"Promoter-binding transcription-factor profiling array, ChIP assay, deletion mutation analysis, GATA1 overexpression in HUVECs, apoptosis assays\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP plus deletion mutagenesis of promoter, single lab\",\n      \"pmids\": [\"27139506\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"CREG directly interacts with apoptosis signal-regulating kinase 1 (ASK1) and inhibits its phosphorylation, thereby blocking the downstream MKK4/7-JNK1 (but not JNK2) signaling pathway; hepatocyte-specific CREG deletion exacerbated obesity, hepatic steatosis, and insulin resistance, while CREG overexpression was protective. JNK1 inhibition prevented the adverse effects of CREG deletion.\",\n      \"method\": \"Hepatocyte-specific CREG KO and overexpression mouse models, co-immunoprecipitation, Western blot for ASK1 phosphorylation and MKK4/7-JNK1 pathway, HFD and ob/ob models\",\n      \"journal\": \"Hepatology (Baltimore, Md.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct interaction (co-IP), conditional KO and overexpression in vivo, pathway epistasis with JNK1 inhibitor, replicated in two genetic models\",\n      \"pmids\": [\"28508477\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Creg in hepatocytes suppresses MAPK signaling by directly binding to TAK1 (TGF-β-activated kinase 1) and inhibiting TAK1 phosphorylation; hepatocyte-specific CREG KO increased cell death and inflammatory cytokines after hepatic I/R. Mutating the TAK1-binding domain of CREG or pharmacologically inhibiting TAK1 abolished CREG protection, confirming the Creg-TAK1 interaction is required.\",\n      \"method\": \"Hepatocyte-specific Creg KO and transgenic mice, hepatic I/R model, hypoxia/reoxygenation in primary hepatocytes, molecular binding experiments (pull-down/co-IP), TAK1 binding domain mutagenesis, TAK1 inhibitor (5Z-7-ox)\",\n      \"journal\": \"Hepatology (Baltimore, Md.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — mutagenesis of binding domain combined with pharmacological inhibitor rescue, conditional KO in vivo, multiple orthogonal endpoints\",\n      \"pmids\": [\"30076625\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"CREG1 binds to retinoid X receptor α (RXRα), which interacts with thyroid hormone receptor to promote brown adipogenesis; CREG1 transgenic mice show elevated UCP1 and FGF-21 expression in BAT and WAT, increased browning, and resistance to diet-induced obesity.\",\n      \"method\": \"CREG1 transgenic mice, BAT primary cultures, co-binding/interaction assays for RXRα, UCP1 reporter assay, β3-adrenergic agonist challenge, metabolic phenotyping\",\n      \"journal\": \"FASEB journal : official publication of the Federation of American Societies for Experimental Biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — binding to RXRα demonstrated in vitro, gain-of-function transgenic model, single lab\",\n      \"pmids\": [\"30917000\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"DNMT3B-mediated hypermethylation of the CREG promoter (at CG site +201/+202 bp) suppresses CREG expression by blocking binding of the transcription factor GR-α; ox-LDL increases DNMT3B expression, leading to CREG promoter hypermethylation and endothelial dysfunction. 5-aza-dC (DNMT inhibitor) restored CREG expression and activated p-eNOS/NO signaling.\",\n      \"method\": \"DNMT3B overexpression/inhibition in HUVECs, CREG promoter methylation analysis, ChIP for GR-α binding, 5-aza-dC treatment, site-specific methylation characterization\",\n      \"journal\": \"Redox biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP assay plus promoter mutation plus pharmacological demethylation, single lab\",\n      \"pmids\": [\"32067910\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"CREG1 is mainly localized to the endosomal-lysosomal compartment (validated by antibodies through gain- and loss-of-function studies) and promotes both macropinocytosis and clathrin-dependent endocytosis, acidification of the endosomal-lysosomal compartment, and lysosomal biogenesis. CREG1 overexpression enhances autophagy and lysosome-mediated degradation; knockdown or knockout has opposite effects.\",\n      \"method\": \"Immunofluorescence microscopy with validated antibodies, gain- and loss-of-function (overexpression and KO), endocytosis assays, lysosomal acidification assay, autophagy flux assays\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — subcellular localization validated with KO controls plus reciprocal gain/loss-of-function for endocytosis and lysosomal biogenesis, multiple orthogonal methods\",\n      \"pmids\": [\"33966596\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"CREG1 localizes to mitochondria in skeletal muscle cells and modulates mitophagy; CREG1 deficiency accelerates mitophagy induction (increased PINK1/PARKIN) and impairs mitochondrial quality. HSPD1/HSP60 (residues 401-573) directly interacts with CREG1 (residues 130-220) to antagonize CREG1 degradation and is involved in mitophagy regulation.\",\n      \"method\": \"Skeletal muscle-specific creg1 KO mice (Creg1;Ckm-Cre), recombinant CREG1 protein administration, electron microscopy, Western blot for PINK1/PARKIN/mitochondrial proteins, gain/loss-of-function in C2C12 cells, immunoprecipitation for HSPD1-CREG1 interaction, domain mapping\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — tissue-specific KO in vivo plus domain-specific co-IP, electron microscopy, multiple orthogonal endpoints\",\n      \"pmids\": [\"33726618\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"CREG inhibits the phenotypic switching of cardiac fibroblasts to myofibroblasts after MI by suppressing CDC42 expression; recombinant CREG protein blocked hypoxia-induced proliferation and migration of cardiac fibroblasts through inhibition of CDC42.\",\n      \"method\": \"Creg+/- mice post-MI model, recombinant CREG protein treatment, in vitro hypoxia model with cardiac fibroblasts, Western blot for αSMA, collagen-1, CDC42, proliferation and migration assays\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo haploinsufficiency and in vitro recombinant protein, single mechanism target (CDC42), single lab\",\n      \"pmids\": [\"33824277\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"CREG promotes differentiation of embryonic stem cells into smooth muscle cells through the TGF-β/Smad2/3 signaling pathway; CREG-KO ESCs showed significantly decreased SMC marker expression and reduced contractile capacity, while CREG-OE ESCs showed the opposite.\",\n      \"method\": \"CREG overexpression and shRNA KO in ESCs, SMC differentiation assay, Western blot for SMC markers (SM α-actin, SM22, calponin, SM-MHC), calcium ion assay, contractility assay\",\n      \"journal\": \"Differentiation; research in biological diversity\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal gain/loss-of-function, pathway identification via TGF-β/Smad2/3, single lab\",\n      \"pmids\": [\"35349881\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"CREG1 stimulates AMPK phosphorylation (at Thr172) and GLUT4 expression/glucose uptake in skeletal muscle cells through IGF2R; CREG1-induced AMPKα phosphorylation and 2-deoxyglucose uptake were suppressed by IGF2R knockdown and by Compound C (AMPK inhibitor), establishing CREG1-IGF2R-AMPK as a signaling axis.\",\n      \"method\": \"CREG1 treatment of C2C12 myotubes, IGF2R knockdown, AMPK inhibitor (Compound C), Western blot for phospho-AMPKα, GLUT4, 2-deoxyglucose uptake assay, CTX-induced muscle regeneration mouse model\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pharmacological and genetic (siRNA) pathway dissection in vitro, single lab\",\n      \"pmids\": [\"36528955\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"CREG1 inhibits LAMP2 protein degradation by suppressing the expression of F-box protein 27 (FBXO27), thereby promoting autophagy in cardiomyocytes; LAMP2 overexpression reversed the effect of CREG1 knockdown on palmitate-induced inhibition of cardiomyocyte autophagy, defining a CREG1-FBXO27-LAMP2 axis.\",\n      \"method\": \"Cardiac-specific Creg1 KO and transgenic mice, diabetic cardiomyopathy model, palmitate-stimulated NMCMs, Western blot, CREG1 overexpression and knockdown with adenovirus/siRNA, LAMP2 overexpression rescue\",\n      \"journal\": \"Experimental & molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO/overexpression in vivo, rescue experiment with LAMP2, mechanistic pathway delineated, single lab\",\n      \"pmids\": [\"37658156\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"CREG1 directly interacts with MEK1/2 and promotes MEK1/2 phosphorylation in megakaryocytes; CREG1 deficiency impairs actin cytoskeleton, proplatelet formation, and ploidy, causing thrombocytopenia due to inefficient bone marrow thrombocytopoiesis.\",\n      \"method\": \"Megakaryocyte/platelet conditional KO and transgenic mice, cytosine arabinoside thrombocytopenia model, immunoprecipitation for MEK1/2-CREG1, Western blot for MEK1/2 phosphorylation, F-actin staining, ploidy assay\",\n      \"journal\": \"International journal of biological sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP plus conditional KO model with defined cellular phenotype, single lab\",\n      \"pmids\": [\"37496998\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"CREG1 deficiency inhibits myoblast differentiation and skeletal muscle regeneration by promoting C-CBL E3-ubiquitin ligase-mediated K48-linked polyubiquitination and degradation of AMPKα1 at K396; silencing C-CBL in CREG1 knockout mice significantly improved muscle regeneration, establishing CREG1-C-CBL-AMPKα1 as a regulatory axis.\",\n      \"method\": \"Creg1 KO and satellite cell-specific overexpression mice (AAV9), cardiotoxin muscle injury model, mass spectrometry, RNA-seq, AAV-sh-C-Cbl rescue, Western blot for AMPKα1 ubiquitination, C2C12 cell transfection\",\n      \"journal\": \"Journal of cachexia, sarcopenia and muscle\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic rescue with C-CBL silencing, ubiquitination site mapping by mass spectrometry, single lab\",\n      \"pmids\": [\"38272853\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"CREG1 inhibits ferroptosis in cardiomyocytes by suppressing PDK4 mRNA and protein expression through the FBXW7-FOXO1 signaling pathway; CREG1-FBXW7-FOXO1-PDK4 is a defined mechanistic axis, and PDK4 deficiency reverses the effects of CREG1 knockdown on DOX-induced ferroptosis.\",\n      \"method\": \"CREG1 transgenic and cardiac-specific KO mice, DOX-induced cardiotoxicity model, transcriptomics, immunoprecipitation, siRNA knockdown of PDK4, Western blot\",\n      \"journal\": \"Redox biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — transcriptomics plus immunoprecipitation plus PDK4 knockdown rescue, single lab\",\n      \"pmids\": [\"39094399\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"CREG1 promotes exosome genesis and release in bovine placental trophoblast cells by targeting IGF2R; IGF2R knockdown inhibited exosome genesis and blocked CREG1-induced exosome production. IGF2R can also reverse-regulate CREG1 expression. CREG1 binding to IGF2R subsequently activates Rab11 to facilitate exosome release.\",\n      \"method\": \"Creg1 overexpression and Igf2r siRNA knockdown in bovine trophoblast cells, exosome isolation and quantification, co-immunoprecipitation, Western blot\",\n      \"journal\": \"International journal of biological macromolecules\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — co-IP and knockdown experiments, single lab, non-canonical model organism (bovine) with limited mechanistic follow-up\",\n      \"pmids\": [\"38917918\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"In zebrafish, loss of creg1 causes anemia due to defective erythroid differentiation and excessive apoptosis of erythroid progenitors; mechanistically, creg1 deficiency reduces TGF-β/Smad2 signaling pathway activation, and Klf1 is a downstream target of this pathway required for normal erythropoiesis. Treatment with a Smad2 agonist (IDE2) restores erythroid development in creg1-/- mutants.\",\n      \"method\": \"Zebrafish creg1 knockout, scRNA-seq, Smad2 agonist (IDE2) rescue, gene expression analysis, epistasis with Klf1\",\n      \"journal\": \"Advanced science (Weinheim, Baden-Wurttemberg, Germany)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO in zebrafish with pharmacological rescue and downstream target identification, single lab\",\n      \"pmids\": [\"38953462\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"CREG1-IGF2R-PI3K-AKT signaling mediates TREM2+ macrophage-promoted osteogenic differentiation of ligament-derived progenitor cells in ankylosing spondylitis; TREM2+ macrophages secrete CREG1 to drive pathological new bone formation, and targeting this axis alleviates new bone formation in a collagen antibody-induced arthritis model.\",\n      \"method\": \"TREM2+ macrophage depletion and Trem2 knockout in CAIA model, CREG1 secretion assay, CREG1-IGF2R-PI3K-AKT pathway inhibition, osteogenic differentiation of LDPCs\",\n      \"journal\": \"Advanced science (Weinheim, Baden-Wurttemberg, Germany)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo KO model plus signaling pathway inhibition, single lab\",\n      \"pmids\": [\"40091508\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"CREG1 is localized to endolysosomal and autophagosomal compartments in cardiomyocytes; loss of CREG1 impairs autophagy flux and mitophagy by impairing autophagosome membrane expansion and degradation. Global Creg1 KO mice develop cardiac hypertrophy, fibrosis, and diastolic dysfunction at ~80 weeks; cardiomyocyte-specific CREG1 overexpression (KI) enhances exercise capacity under nutritional stress.\",\n      \"method\": \"Global Creg1 KO (entire ORF deletion) and Rosa26-CREG1 KI mice, cm-specific Creg1 KO and KI, autophagy reporter (CAG-EGFP-RFP-LC3), electron microscopy, biochemical autophagy assays, cardiac phenotyping\",\n      \"journal\": \"bioRxiv : the preprint server for biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — true KO (full ORF deletion) plus gain-of-function KI, autophagy reporter, multiple endpoints; preprint not yet peer-reviewed\",\n      \"pmids\": [\"41292877\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"CREG1 is cleaved by cathepsin B in vitro, and cathepsin B overexpression reduces secreted CREG1 levels while cathepsin B deletion or inhibition increases them; reduced CREG1 expression promotes proliferation, migration, and invasion of PyMT breast tumor cells, establishing cathepsin B as a negative regulator of CREG1 in the tumor microenvironment.\",\n      \"method\": \"Cathepsin B overexpression/deletion in MMTV-PyMT mouse model, in vitro cleavage assay, conditioned media/tumor interstitial fluid proteomics (SILAC), recombinant CREG1 treatment, orthotopic transplantation\",\n      \"journal\": \"Cellular and molecular life sciences : CMLS\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro cleavage assay plus in vivo cathepsin B KO model, single lab\",\n      \"pmids\": [\"32385587\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CREG1 is an endolysosomal glycoprotein that can be secreted; it inhibits cell proliferation and promotes differentiation by binding M6P/IGF2R (in glycosylation-dependent and -independent modes) and signaling through multiple pathways including ERK1/2, VEGF/PI3K/AKT, ASK1-MKK4/7-JNK1, and TAK1-MAPK; it promotes lysosomal biogenesis, endocytic trafficking, and autophagic/mitophagic flux (partly via Rab7 and HSPD1), directly interacts with the exocyst component Sec8 to promote cardiomyocyte junction assembly, activates MEK1/2 in megakaryocytes, regulates ferroptosis via FBXW7-FOXO1-PDK4, and regulates erythropoiesis through TGF-β/Smad2-Klf1 signaling, with its transcription controlled by GATA1 and epigenetically silenced by DNMT3B-mediated promoter methylation.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CREG1 is a secreted and endolysosomal glycoprotein that restrains cell proliferation and promotes differentiation across multiple lineages [#0, #4]. Its canonical extracellular activity proceeds through direct binding to the mannose-6-phosphate/IGF2 receptor (M6P/IGF2R), engaging receptor domains 7\\u201310 in a glycosylation-dependent manner and domains 11\\u201313 independently of glycosylation; receptor binding is required for CREG1-induced G1/S cell-cycle delay and growth inhibition [#1, #7]. Structurally, CREG1 forms a tight homodimer with an FMN-binding split-barrel fold in which the cofactor pocket is sterically blocked, and a loop mutant that retains dimerization and receptor binding yet loses growth suppression shows that M6P/IGF2R engagement is necessary but not sufficient for its anti-proliferative effect [#2]. Through M6P/IGF2R-dependent endocytosis CREG1 controls IGF-II trafficking and downstream PI3K/Akt signaling, governing smooth muscle quiescence and migration [#6], and the same receptor couples CREG1 to AMPK activation and glucose uptake in skeletal muscle [#22]. A major function of CREG1 is in the endosomal-lysosomal system, where it localizes and promotes endocytosis, lysosomal acidification, lysosomal biogenesis, and autophagic and mitophagic flux [#18, #19]; in cardiomyocytes it sustains autophagy and is cardioprotective, acting in part through Rab7, the FBXO27-LAMP2 axis, and interaction with HSPD1 in mitochondria [#10, #12, #23, #19]. CREG1 additionally acts through direct protein interactions to shape signaling: it binds and inhibits ASK1 (blocking MKK4/7-JNK1) and TAK1 to protect hepatocytes [#14, #15], binds the exocyst component Sec8 to drive cardiomyocyte junction assembly and differentiation [#11], and binds MEK1/2 to promote megakaryocyte thrombopoiesis [#24]. It directs differentiation programs via TGF-\\u03b2/Smad2 signaling in smooth muscle and erythropoiesis [#21, #28] and regulates cardiomyocyte ferroptosis through an FBXW7-FOXO1-PDK4 axis [#26]. CREG1 expression is controlled transcriptionally by GATA1 and is epigenetically silenced by DNMT3B-mediated promoter hypermethylation [#13, #17].\",\n  \"teleology\": [\n    {\n      \"year\": 2000,\n      \"claim\": \"Established CREG1 as a secreted factor acting in an extracellular differentiation cascade, framing it as a signaling protein rather than a purely intracellular one.\",\n      \"evidence\": \"Overexpression and conditioned-media rescue in NTERA-2 embryonal carcinoma cells\",\n      \"pmids\": [\"10815803\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No receptor or molecular mechanism identified\", \"Single cell model, gain-of-function only\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Identified M6P/IGF2R as the functional receptor for CREG1, answering how a secreted protein transduces growth arrest.\",\n      \"evidence\": \"Direct binding assay plus cell-cycle analysis in M6P/IGF2R-deficient cells\",\n      \"pmids\": [\"12934103\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream signaling from the receptor not defined\", \"Glycosylation requirement not yet dissected\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Resolved the CREG1 fold and showed that receptor binding alone does not confer growth suppression, separating binding from activity.\",\n      \"evidence\": \"1.9-\\u00c5 crystal structure with loop-deletion mutagenesis and growth assays\",\n      \"pmids\": [\"16344469\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The FMN pocket is blocked but no enzymatic activity assigned\", \"Structural basis of the activity beyond binding unknown\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Connected CREG1 to MAPK signaling by showing it represses ERK1/2 to limit cardiomyocyte hypertrophy.\",\n      \"evidence\": \"Reciprocal overexpression/antisense in rat cardiomyocytes plus pressure-overload model\",\n      \"pmids\": [\"15257182\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of ERK1/2 regulation not molecular\", \"Direct vs indirect effect unresolved\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Defined two binding modes (glycosylation-dependent domains 7\\u201310 and independent domains 11\\u201313) and showed the independent mode suffices for cell-cycle arrest.\",\n      \"evidence\": \"In vitro binding with M6P/IGF2R domain fragments plus cell-cycle rescue in knockdown SMCs; combined with IGF-II endocytosis/PI3K-Akt findings\",\n      \"pmids\": [\"21195083\", \"19769965\", \"18691225\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural basis of dual binding modes not solved\", \"Single-lab vascular models\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Reframed CREG1 as a lysosomal/autophagy regulator, showing it promotes lysosomal maturation and autophagic flux, partly via Rab7.\",\n      \"evidence\": \"Creg1+/- mice, adenoviral rescue in cardiomyocytes, chloroquine blockade\",\n      \"pmids\": [\"25774384\", \"27840305\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism of lysosomal maturation control undefined\", \"Link between secreted and intracellular pools unclear\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Identified direct protein partners (Sec8) and transcriptional control (GATA1), expanding CREG1 mechanism beyond M6P/IGF2R.\",\n      \"evidence\": \"Co-IP and mutagenesis with KO-ES-cell rescue for Sec8; ChIP and promoter mutagenesis for GATA1\",\n      \"pmids\": [\"27334848\", \"27139506\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How Sec8 binding integrates with lysosomal roles unknown\", \"GATA1 regulation tested mainly in endothelial context\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Established CREG1 as a direct kinase inhibitor, binding ASK1 and TAK1 to suppress JNK1 and MAPK signaling in hepatocytes.\",\n      \"evidence\": \"Conditional hepatocyte KO/transgenic mice, co-IP, binding-domain mutagenesis, pathway-inhibitor epistasis\",\n      \"pmids\": [\"28508477\", \"30076625\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of kinase binding not solved\", \"Relationship to lysosomal/receptor functions unresolved\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Consolidated CREG1 subcellular biology, localizing it to endolysosomes and mitochondria and defining roles in endocytosis, lysosomal biogenesis, and mitophagy with the HSPD1 partner.\",\n      \"evidence\": \"Validated immunofluorescence with KO controls, reciprocal gain/loss-of-function, tissue-specific KO, domain-mapped HSPD1 co-IP\",\n      \"pmids\": [\"33966596\", \"33726618\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether mitochondrial and lysosomal pools are functionally distinct unclear\", \"Mechanism coupling CREG1 to membrane trafficking machinery incomplete\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Extended CREG1 mechanism to ubiquitin-proteasome and ferroptosis control via defined axes (C-CBL-AMPK\\u03b11, FBXW7-FOXO1-PDK4) and to TGF-\\u03b2/Smad2-Klf1-driven erythropoiesis.\",\n      \"evidence\": \"KO/transgenic mice, mass-spectrometry ubiquitination mapping, genetic rescue, zebrafish KO with Smad2 agonist rescue\",\n      \"pmids\": [\"38272853\", \"39094399\", \"38953462\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct vs indirect control of E3 ligase expression unresolved\", \"Single-lab mechanistic axes\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How CREG1's many activities\\u2014receptor binding, kinase inhibition, lysosomal biogenesis, and transcriptional axes\\u2014are integrated by a single split-barrel protein with a blocked cofactor pocket remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unifying biochemical activity assigned to the fold\", \"Spatial/functional relationship between secreted and intracellular pools undefined\", \"No human disease mutation reported in the corpus\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [14, 15]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [1, 7]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [11]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005764\", \"supporting_discovery_ids\": [18, 10, 30]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [18]},\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [19]},\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": [0, 5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [10, 12, 18, 23]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [14, 15, 9, 22]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [1, 2, 8]},\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [6, 18]}\n    ],\n    \"complexes\": [\"exocyst (via Sec8)\"],\n    \"partners\": [\"IGF2R\", \"Sec8\", \"ASK1\", \"TAK1\", \"MEK1/2\", \"HSPD1\", \"RXRA\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}