{"gene":"IGFBP3","run_date":"2026-04-28T18:06:53","timeline":{"discoveries":[{"year":1993,"finding":"Glycosylated and non-glycosylated forms of recombinant IGFBP-3 bind IGF-I with equal affinity (Kd ~50 pM), and both forms extend IGF-I half-life in vivo by forming a 40–140 kDa circulating complex; glycosylation delays peak IGF-I levels post-injection but does not alter overall bioavailability.","method":"Competition binding assay, real-time biospecific interaction analysis (BIA), in vivo subcutaneous injection in rats with gel filtration of serum","journal":"Growth regulation","confidence":"High","confidence_rationale":"Tier 1 — in vitro binding assay plus in vivo pharmacokinetic validation with structural characterization of circulating complexes","pmids":["7683528"],"is_preprint":false},{"year":1996,"finding":"Proteolysis of IGFBP-3 by plasmin, thrombin, and pregnancy serum generates multiple fragments with differential IGF-binding and heparin-binding capacities; the dominant mid-fragment retains both IGF and heparin affinity, while NH2-terminal fragments retain only IGF affinity, demonstrating structural separation of binding domains.","method":"Protease digestion, N-terminal sequencing of fragments, ligand blotting for IGF and heparin binding","journal":"The American journal of physiology","confidence":"High","confidence_rationale":"Tier 1 — direct in vitro biochemical reconstitution with sequencing and functional binding assays","pmids":["8843739"],"is_preprint":false},{"year":1998,"finding":"Hepatic IGFBP-3 gene transcription is regulated by insulin through an insulin-responsive element that recruits insulin-responsive nuclear factors (demonstrated by gel mobility shift and southwestern blot), while IGF-I increases IGFBP-3 mRNA stability in hepatic non-parenchymal cells.","method":"In vitro transcription, gel mobility shift assay, southwestern blot, mRNA stability assay","journal":"Progress in nucleic acid research and molecular biology","confidence":"Medium","confidence_rationale":"Tier 1–2 — multiple in vitro methods in a single lab, no independent replication cited","pmids":["9594576"],"is_preprint":false},{"year":2000,"finding":"IGFBP-3 mediates TGF-β1-induced cell growth (not only inhibition) in human airway smooth muscle cells; TGF-β1 induces a 10–20-fold increase in IGFBP-3 expression, and blocking IGFBP-3 with antisense oligomers or neutralizing antibody abolishes TGF-β1-induced proliferation.","method":"Antisense oligonucleotide knockdown, neutralizing antibody, cell proliferation assay, mRNA/protein expression analysis","journal":"American journal of physiology. Lung cellular and molecular physiology","confidence":"High","confidence_rationale":"Tier 2 — two orthogonal loss-of-function approaches (antisense + neutralizing antibody) with consistent results","pmids":["10710527"],"is_preprint":false},{"year":2000,"finding":"IGFBP-3 is a transcriptional target of p53; genotoxic stress activates p53, which induces IGFBP-3 expression, linking p53-mediated apoptosis to the IGF axis through IGFBP-3 induction.","method":"Transcriptional regulation analysis, p53 pathway studies (reviewed with cited experimental evidence)","journal":"Molecular genetics and metabolism","confidence":"Medium","confidence_rationale":"Tier 2 — review synthesizing experimental evidence across multiple studies; original p53-IGFBP3 transcriptional activation established by referenced experiments","pmids":["10873390"],"is_preprint":false},{"year":2007,"finding":"IGFBP-3 suppresses esophageal tumor formation via IGF-dependent mechanisms (blocking IGF-1R and AKT activation) as shown by IGF-binding mutant IGFBP-3 (Ile56Gly/Leu80Gly/Leu81Gly) losing tumor suppressor activity in vivo, while the mutant also reveals an IGF-independent growth-stimulatory activity.","method":"Stable transduction of wild-type vs. IGF-binding mutant IGFBP-3 in Ras-transformed human esophageal cells, xenograft tumor formation, in vivo bioluminescence imaging, AKT/IGF-1R signaling assays","journal":"Cancer biology & therapy","confidence":"High","confidence_rationale":"Tier 1 — active-site mutagenesis combined with in vivo xenograft and signaling readouts","pmids":["17457048"],"is_preprint":false},{"year":2008,"finding":"IGFBP-3 regulates the appearance of senescence biomarkers in human diploid fibroblasts; siRNA knockdown of IGFBP-3 attenuates stress-induced premature senescence following repeated oxidative insults.","method":"siRNA knockdown, DNA array screening, senescence biomarker assays","journal":"Free radical biology & medicine","confidence":"Medium","confidence_rationale":"Tier 2 — siRNA loss-of-function with specific phenotypic readout in a clean cellular model","pmids":["18329388"],"is_preprint":false},{"year":2009,"finding":"IGFBP3 co-localizes with hypocretin/orexin in hypothalamic neurons and overexpression of IGFBP3 in transgenic mice decreases hypocretin mRNA and peptide levels and increases sleep, likely through decreased hypocretin promoter activity.","method":"Transgenic mouse overexpression, mRNA expression analysis, hypocretin peptide measurement, sleep phenotyping, promoter activity assay","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 — in vivo gain-of-function with multiple orthogonal readouts in a single study","pmids":["19158946"],"is_preprint":false},{"year":2012,"finding":"Hypoxia induces IGFBP3 in esophageal squamous cancer cells through HIF-1α (but not HIF-2α) binding to a novel hypoxia-responsive element (HRE) 57 kb upstream of the transcription start site; under hypoxia, global cap-dependent translation is suppressed but IGFBP3 mRNA remains enriched in polysomes allowing continued synthesis.","method":"RNAi (HIF-1α vs HIF-2α), chromatin immunoprecipitation, transfection reporter assays, metabolic labeling, 7-methyl GTP-cap binding assay, mTOR pharmacological inhibition, polysome fractionation","journal":"FASEB journal","confidence":"High","confidence_rationale":"Tier 1 — multiple orthogonal methods (ChIP, reporter, metabolic labeling, polysome fractionation) in a single rigorous study","pmids":["22415309"],"is_preprint":false},{"year":2013,"finding":"IGFBP-3 interacts with the retinoid X receptor-α (RXRα) and facilitates phosphorylation and nuclear export of the orphan nuclear receptor Nur77 to the cytoplasm in response to apoptotic stimuli, where Nur77 exerts its pro-apoptotic effect; IGFBP-3 knockdown attenuates caspase-3/7 activation and Nur77 nuclear export.","method":"Co-immunoprecipitation, siRNA knockdown, indirect immunofluorescence, cell fractionation, caspase activity assay","journal":"Endocrinology (2015 paper)","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP plus multiple functional readouts (caspase assay, fractionation, immunofluorescence) in a single study","pmids":["26340041"],"is_preprint":false},{"year":2013,"finding":"TGF-β1 induces IGFBP-3 expression in osteosarcoma cells, and IGFBP-3 then attenuates TGF-β1 activation of ERK1/2 and Akt, inhibits TGF-β1-induced cell cycle progression, and enhances non-canonical Smad2 phosphorylation at Ser245/250/255; blocking IGFBP-3 induction enhances pSmad2 nuclear accumulation, revealing a negative-feedback loop.","method":"IGFBP-3 siRNA, IGF1R inhibition, western blotting for ERK, Akt, Smad2 phosphorylation, cell cycle analysis, proliferation assay","journal":"Molecular and cellular endocrinology","confidence":"High","confidence_rationale":"Tier 2 — siRNA knockdown combined with pharmacological inhibition and multiple signaling readouts","pmids":["23831640"],"is_preprint":false},{"year":2013,"finding":"IGFBP-3 signals through a specific IGFBP-3 receptor on retinal endothelial cells; overexpression of IGFBP-3 upregulates its receptor, and siRNA knockdown of the receptor abolishes IGFBP-3's anti-apoptotic effect, demonstrating receptor-dependent signaling to regulate Bcl-xL, Bax, cytochrome C, and Akt.","method":"Co-immunoprecipitation, co-localization, siRNA knockdown of IGFBP-3 receptor, western blotting, cell death ELISA, caspase-3 ELISA","journal":"Apoptosis","confidence":"Medium","confidence_rationale":"Tier 2 — receptor Co-IP plus siRNA rescue with defined signaling readouts","pmids":["23291901"],"is_preprint":false},{"year":2013,"finding":"Novel ligands of IGFBP-3 include the retinoid X receptor, retinoic acid receptor-α, Nur77, vitamin D receptor, PPARγ, TGFβ/Smad signaling components, LRP1, TMEM219, EGFR, DNA-PK, and GRP78; these interactions mediate IGF-independent functions including apoptosis (via caspase-8 and -9), DNA DSB repair, and autophagy.","method":"Multiple binding and functional studies cited in review including Co-IP, cell-free binding assays, and loss-of-function experiments","journal":"Journal of cell communication and signaling","confidence":"Medium","confidence_rationale":"Tier 3 — comprehensive review consolidating multiple single-lab interaction studies","pmids":["23700234"],"is_preprint":false},{"year":2015,"finding":"Humanin peptide directly binds IGFBP-3 (Kd ~5.05 µM) and competitively inhibits IGFBP-3 binding to importin-β1 (IC50 ~18.1 µM), thereby blocking nuclear translocation of IGFBP-3 and attenuating IGFBP-3-induced apoptosis in lung adenocarcinoma cells.","method":"Competitive ligand dot blotting, co-immunoprecipitation, ELISA-based binding assay, apoptosis assay","journal":"Protein and peptide letters","confidence":"Medium","confidence_rationale":"Tier 2 — binding affinity quantified by multiple methods plus functional apoptosis rescue","pmids":["26216267"],"is_preprint":false},{"year":2016,"finding":"Pancreatic cancer cell-derived IGFBP-3 causes muscle wasting by inhibiting IGF signaling, impairing myogenesis, and enhancing protein degradation in muscle cells; conditioned medium from IGFBP3-knockdown pancreatic cancer cells or IGFBP-3 antibody neutralization reverses these effects.","method":"siRNA knockdown, conditioned medium transfer, IGFBP-3 neutralizing antibody, myogenesis assays, protein degradation assays, C2C12 muscle cell biochemical assays","journal":"Journal of experimental & clinical cancer research","confidence":"High","confidence_rationale":"Tier 2 — two independent loss-of-function approaches (siRNA + antibody neutralization) with specific cellular readouts","pmids":["26975989"],"is_preprint":false},{"year":2017,"finding":"IGFBP3 modulates lung tumor growth through IGF1 signaling; Igfbp3-null mice show >2-fold increased lung tumor burden in a Kras model, and overexpression of wild-type IGFBP3 (but not an IGF-binding mutant) in NSCLC cells induces apoptosis (10-fold increase in cleaved caspase-3) and inactivates IGF1 and MAPK signaling.","method":"Igfbp3 knockout mouse crossed with Kras lung tumor model, wild-type vs. IGF-binding mutant IGFBP3 overexpression, caspase-3 cleavage assay, IGF1/MAPK signaling analysis","journal":"Molecular cancer research","confidence":"High","confidence_rationale":"Tier 1–2 — in vivo genetic model plus mutant rescue experiment dissecting IGF-dependent mechanism","pmids":["28330997"],"is_preprint":false},{"year":2018,"finding":"IGFBP-3 mediates nuclear translocation of IGF-1R in corneal epithelial cells under serum-free/stress conditions via SUMO 2/3-mediated SUMOylation; IGFBP-3 and IGF-1R undergo reciprocal regulation independent of PI3K/Akt, with IGFBP-3 arresting the cell cycle in G0/G1 and maintaining nuclear IGF-1R levels under stress.","method":"Immunofluorescence, nuclear fractionation, SUMOylation assay, siRNA knockdown, cell cycle analysis","journal":"Journal of cellular physiology","confidence":"Medium","confidence_rationale":"Tier 2 — direct localization experiments with functional consequence, single lab","pmids":["30078228"],"is_preprint":false},{"year":2019,"finding":"IGFBP-3 forms nuclear complexes with NONO and SFPQ (non-POU domain-containing octamer-binding protein and splicing factor, proline/glutamine-rich) in a PARP-dependent and EGFR/DNA-PKcs-dependent manner in triple-negative breast cancer cells in response to DNA damage; these complexes promote DSB repair by NHEJ and are blocked by PARP inhibitors; LINP1 lncRNA is required for complex formation.","method":"LC-MS/MS interactome, co-immunoprecipitation, proximity ligation assay, cell-free biochemical binding assay, DNA end-joining in vitro assay, γH2AX foci measurement, pharmacological inhibitors, siRNA knockdown","journal":"Cellular and molecular life sciences","confidence":"High","confidence_rationale":"Tier 1–2 — mass spectrometry interactome confirmed by Co-IP and PLA, with cell-free biochemical assay and multiple functional readouts","pmids":["30725116"],"is_preprint":false},{"year":2019,"finding":"ROS- and HIF-1α-dependent upregulation of IGFBP3 under high-glucose/hyperglycemic conditions sequesters extracellular IGF1 from the IGF1 survival pathway, blocking IGF1R signaling and leading to cardiomyocyte apoptosis; PHD inhibition stabilizes HIF1α to drive this cascade.","method":"Co-IP assay, western blotting, siRNA knockdown, gain/loss-of-function, pharmacological inhibitors, hyperglycemic cell models and diabetic rat in vivo","journal":"Journal of cellular physiology","confidence":"Medium","confidence_rationale":"Tier 2 — multiple methods in single lab with in vivo confirmation","pmids":["30659610"],"is_preprint":false},{"year":2020,"finding":"TGF-β increases IGFBP-3 expression in hepatic stellate cells (HSCs) through GIPC/synectin via epigenetic changes (increased H3K27 acetylation, decreased H3K27me3); IGFBP-3 in turn promotes HSC migration through integrin-dependent phosphorylation of Akt; global Igfbp3 knockout mice show attenuated HSC activation and reduced portal pressure.","method":"mRNA sequencing, ELISA, qPCR, targeted chromatin immunoprecipitation (H3K27ac/me3), western blot, Igfbp3 global knockout mouse, portal pressure measurement, in vitro migration assay","journal":"Cellular and molecular gastroenterology and hepatology","confidence":"High","confidence_rationale":"Tier 2 — in vivo genetic knockout with in vitro mechanistic dissection using ChIP and signaling readouts","pmids":["32447051"],"is_preprint":false},{"year":2020,"finding":"IGFBP3 signaling through the death receptor TMEM219 on pancreatic beta cells causes beta cell loss and dysfunction; TMEM219 genetic ablation or short-term IGFBP3/TMEM219 inhibition preserves beta cells and prevents/delays diabetes onset, while long-term blockade allows beta cell expansion.","method":"TMEM219 genetic ablation, pharmacological IGFBP3/TMEM219 inhibition in vitro and in vivo, diabetes onset monitoring in T1D/T2D preclinical models, human patient cohort correlation","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 — in vivo genetic model plus pharmacological intervention with defined mechanistic pathway","pmids":["35115561"],"is_preprint":false},{"year":2020,"finding":"BMP2 upregulates IGFBP3 in human endometrial stromal cells through ALK3 receptor and ID1 as an intermediary; IGFBP3 in turn promotes MMP2 expression and cell migration; knockdown of either IGFBP3 or ID1 abolishes BMP2-induced MMP2 upregulation and migration.","method":"siRNA knockdown of ALK3, ID1, and IGFBP3, dose-response and time-course expression studies, cell migration assay in human endometrial stromal cells","journal":"FASEB journal","confidence":"High","confidence_rationale":"Tier 2 — three-step pathway dissection by sequential siRNA knockdowns with functional migration readout","pmids":["32975335"],"is_preprint":false},{"year":2020,"finding":"Hepatic stellate cell-derived IGFBP3 directly induces lipid droplet formation, triglyceride accumulation, and lipogenic gene expression in hepatocytes in vitro; recombinant IGFBP3 treatment phenocopies and IGFBP3 serum levels are elevated in alcoholic hepatitis patients.","method":"HSC supernatant transfer, adipokine antibody array, recombinant IGFBP3 treatment of hepatocytes, triglyceride assay, lipid droplet staining, lipogenic gene expression, NRP-1 HSC-selective knockout mouse model","journal":"Journal of hepatology","confidence":"Medium","confidence_rationale":"Tier 2 — gain-of-function with recombinant protein plus genetic model, single lab","pmids":["32087348"],"is_preprint":false},{"year":2022,"finding":"IGFBP-3 acts as a molecular switch regulating mitochondrial homeostasis in corneal epithelial cells by controlling the short isoform of the BNIP3L/NIX mitophagy receptor; both loss and gain of IGFBP-3 function increase mitochondrial respiration associated with nuclear accumulation of IGFBP-3, and IGFBP-3 regulates lamellar cristae morphology and mitochondrial dynamics.","method":"IGFBP-3 siRNA knockdown and overexpression, mitophagy receptor (sBNIP3L/NIX) western blotting, mitochondrial respiration measurement, nuclear fractionation, electron microscopy of cristae morphology","journal":"FASEB journal","confidence":"Medium","confidence_rationale":"Tier 2 — gain and loss of function with multiple orthogonal mitochondrial readouts, single lab","pmids":["34918377"],"is_preprint":false},{"year":2023,"finding":"METTL3-mediated m6A RNA modification upregulates IGFBP3 expression in cardiac fibroblasts; METTL3 silencing downregulates IGFBP3 and inhibits cardiac fibroblast activation, migration and proliferation both in vitro and in vivo in TAC and isoproterenol cardiac fibrosis models.","method":"RNA-seq, shRNA knockdown of METTL3, m6A methylation analysis, TGF-β1 stimulation, fibroblast migration and proliferation assays, in vivo mouse cardiac fibrosis models","journal":"European journal of pharmacology","confidence":"Medium","confidence_rationale":"Tier 2 — in vivo and in vitro loss-of-function with mechanistic m6A modification link, single lab","pmids":["36657656"],"is_preprint":false},{"year":2018,"finding":"ADAM28 metalloprotease degrades IGFBP-3, thereby increasing free IGF-I availability and promoting IGF-I-induced proliferation and migration of acute myeloid leukemia cells; ADAM28 knockout in a xenotransplantation mouse model reduces leukemic cell growth and dissemination.","method":"ADAM28 knockout, IGFBP-3 degradation assay, IGF-I signaling measurement, xenotransplantation mouse model, proliferation and migration assays","journal":"Cancer letters","confidence":"Medium","confidence_rationale":"Tier 2 — in vivo genetic model plus mechanism of IGFBP3 proteolytic degradation","pmids":["30429106"],"is_preprint":false},{"year":2020,"finding":"IGFBP-3 induces apoptosis in chondrocytes through nucleus-to-mitochondria translocation of the nuclear receptor Nur77, mechanistically linking IGFBP-3 to osteoarthritis pathogenesis.","method":"Exogenous recombinant IGFBP-3 treatment of cultured chondrocytes, CCK-8 assay, flow cytometry, laser confocal microscopy for Nur77 localization","journal":"International journal of clinical and experimental pathology","confidence":"Low","confidence_rationale":"Tier 3 — single lab, single method for each readout, no independent validation","pmids":["26884829"],"is_preprint":false},{"year":2020,"finding":"IGFBP-3 inhibits angiogenesis through intracellular regulation of THBS1 (thrombospondin-1) expression via THBS1 promoter activation; intracellular IGFBP-3 shows stronger THBS1 promoter activation than extracellular IGFBP-3, and THBS1 silencing reverses IGFBP3-mediated inhibition of tube formation and blood vessel development.","method":"Inducible IGFBP3 overexpression in ovarian cancer cells, HUVEC capillary tube formation assay, CAM assay, luciferase promoter assay, THBS1 siRNA rescue, in vivo xenograft with vascular assessment","journal":"American journal of cancer research","confidence":"Medium","confidence_rationale":"Tier 2 — luciferase promoter assay plus in vitro and in vivo functional assays with siRNA rescue","pmids":["32642286"],"is_preprint":false},{"year":2018,"finding":"Epac1 activates IGFBP-3, which increases SIRT1 levels, leading to deacetylation of HMGB1 in retinal endothelial cells; IGFBP-3 siRNA abolishes the ability of an Epac1 agonist to reduce HMGB1 acetylation and SIRT1 levels, placing IGFBP-3 as a required intermediary in this signaling pathway.","method":"Epac1 conditional knockout mice, siRNA knockdown of IGFBP-3 and SIRT1, immunoprecipitation for acetylated HMGB1, western blot, ELISA","journal":"Molecular vision","confidence":"Medium","confidence_rationale":"Tier 2 — in vivo genetic model plus siRNA epistasis with biochemical readouts","pmids":["30581279"],"is_preprint":false}],"current_model":"IGFBP-3 is a multifunctional secreted protein that acts primarily as the major circulating IGF-I/II carrier (binding IGFs with ~50 pM affinity, extending their half-life in a ternary complex with ALS), but also signals independently of IGF through multiple intracellular and cell-surface mechanisms: it is transcriptionally induced by p53, HIF-1α, TGF-β, BMP2, and METTL3-mediated m6A modification; it signals via the death receptor TMEM219 to induce beta-cell apoptosis; it facilitates nuclear export of the pro-apoptotic Nur77/RXRα complex; it forms nuclear complexes with EGFR, DNA-PKcs, NONO, and SFPQ to promote NHEJ-based DNA double-strand break repair; it mediates nuclear translocation of IGF-1R via SUMOylation; it regulates mitochondrial homeostasis through the BNIP3L/NIX mitophagy receptor; it inhibits angiogenesis by activating THBS1 transcription; it promotes hepatic stellate cell migration via integrin-Akt signaling; and it is proteolytically inactivated by ADAM28, releasing free IGF-I to drive cell proliferation."},"narrative":{"teleology":[{"year":1993,"claim":"Establishing IGFBP-3 as a high-affinity IGF-I carrier that extends IGF half-life in vivo resolved how circulating IGFs are stabilized and buffered from rapid clearance.","evidence":"Recombinant glycosylated and non-glycosylated IGFBP-3 binding assays (BIA, competition binding) plus rat in vivo pharmacokinetics with gel filtration","pmids":["7683528"],"confidence":"High","gaps":["Ternary complex formation with ALS not directly characterized in this study","Tissue-specific release kinetics not addressed"]},{"year":1996,"claim":"Mapping protease-generated IGFBP-3 fragments with distinct IGF- versus heparin-binding capacities revealed that proteolysis is not merely degradation but a mechanism to generate functionally distinct modules.","evidence":"Plasmin/thrombin digestion with N-terminal sequencing and ligand blotting for IGF and heparin binding","pmids":["8843739"],"confidence":"High","gaps":["Physiological protease(s) responsible in vivo not identified","Fragment stability and clearance in circulation not measured"]},{"year":2000,"claim":"Demonstrating that p53 and TGF-β1 transcriptionally induce IGFBP-3 placed it at the intersection of tumor suppression and growth factor signaling, revealing context-dependent growth-inhibitory and growth-stimulatory roles.","evidence":"Antisense oligonucleotide and neutralizing antibody blockade of IGFBP-3 abolished TGF-β1-induced proliferation in airway smooth muscle cells; p53-IGFBP3 transcriptional activation established by promoter studies","pmids":["10710527","10873390"],"confidence":"High","gaps":["Direct p53 binding site on IGFBP3 promoter not mapped in these studies","Mechanism by which IGFBP-3 switches between growth promotion and inhibition unresolved"]},{"year":2007,"claim":"Using IGF-binding-deficient IGFBP-3 mutants in xenografts dissected the IGF-dependent tumor suppressor activity from an IGF-independent growth-stimulatory activity, establishing that IGFBP-3 is bifunctional in cancer.","evidence":"Wild-type vs. Ile56Gly/Leu80Gly/Leu81Gly mutant IGFBP-3 in Ras-transformed esophageal cell xenografts with AKT/IGF-1R signaling readouts","pmids":["17457048"],"confidence":"High","gaps":["Receptor or target mediating the IGF-independent growth-stimulatory effect not identified","Relevance beyond esophageal cancer not tested"]},{"year":2012,"claim":"Identifying a distal HIF-1α-bound HRE 57 kb upstream of IGFBP3 and showing cap-independent polysomal loading of IGFBP3 mRNA under hypoxia explained how IGFBP-3 protein levels are maintained when global translation is suppressed.","evidence":"ChIP for HIF-1α, HIF-1α/HIF-2α RNAi, reporter assays, polysome fractionation, and metabolic labeling in esophageal cancer cells","pmids":["22415309"],"confidence":"High","gaps":["IRES or other cap-independent translation element in IGFBP3 mRNA not mapped","Whether this mechanism operates in non-cancer hypoxic tissues unknown"]},{"year":2013,"claim":"Discovering that IGFBP-3 physically interacts with RXRα and facilitates Nur77 nuclear export to the cytoplasm for pro-apoptotic action revealed a direct intracellular apoptosis-promoting mechanism independent of IGF sequestration.","evidence":"Reciprocal Co-IP, siRNA knockdown, nuclear fractionation, immunofluorescence, and caspase-3/7 activity assays","pmids":["26340041"],"confidence":"High","gaps":["Structural basis of IGFBP-3/RXRα/Nur77 ternary complex unknown","Whether Nur77 export depends on IGFBP-3 nuclear import via importin-β1 not tested"]},{"year":2013,"claim":"Demonstrating that IGFBP-3 feeds back on TGF-β1 signaling by attenuating ERK/Akt activation and enhancing non-canonical Smad2 linker phosphorylation established IGFBP-3 as a context-dependent modulator of Smad versus non-Smad TGF-β outputs.","evidence":"IGFBP-3 siRNA with western blot for phospho-ERK, phospho-Akt, and phospho-Smad2 (Ser245/250/255) in osteosarcoma cells","pmids":["23831640"],"confidence":"High","gaps":["Direct physical interaction between IGFBP-3 and TGF-β signaling components not shown","Generalizability beyond osteosarcoma untested"]},{"year":2015,"claim":"Showing that humanin competes with importin-β1 for IGFBP-3 binding and blocks nuclear translocation identified the nuclear import pathway and a mechanism of IGFBP-3 functional regulation.","evidence":"Competitive binding assays (dot blot, Co-IP, ELISA) plus apoptosis rescue in lung adenocarcinoma cells","pmids":["26216267"],"confidence":"Medium","gaps":["IGFBP-3 NLS mapping not performed","Whether humanin regulation operates physiologically at endogenous concentrations unclear"]},{"year":2018,"claim":"Identifying ADAM28 as a protease that degrades IGFBP-3 to release free IGF-I in AML provided a disease-relevant proteolytic activation mechanism by which tumors co-opt the IGF axis.","evidence":"ADAM28 knockout xenotransplantation model, IGFBP-3 degradation assay, IGF-I signaling measurement","pmids":["30429106"],"confidence":"Medium","gaps":["Cleavage site(s) on IGFBP-3 not mapped","Contribution relative to other IGFBP-3 proteases in AML not assessed"]},{"year":2018,"claim":"Demonstrating that IGFBP-3 mediates IGF-1R nuclear translocation via SUMO2/3-dependent SUMOylation under stress revealed a non-canonical mechanism coupling the IGF axis to nuclear signaling independent of PI3K/Akt.","evidence":"Immunofluorescence, nuclear fractionation, SUMOylation assay, siRNA knockdown, and cell cycle analysis in corneal epithelial cells","pmids":["30078228"],"confidence":"Medium","gaps":["SUMOylation site on IGF-1R not identified","Functional consequence of nuclear IGF-1R downstream of IGFBP-3 not characterized"]},{"year":2019,"claim":"Identifying a nuclear IGFBP-3/NONO/SFPQ/EGFR/DNA-PKcs complex required for NHEJ-mediated DSB repair — and showing PARP inhibitor sensitivity — established IGFBP-3 as a scaffold in the DNA damage response with therapeutic implications.","evidence":"LC-MS/MS interactome, Co-IP, proximity ligation assay, cell-free end-joining assay, γH2AX foci measurement, pharmacological and siRNA perturbation in TNBC cells","pmids":["30725116"],"confidence":"High","gaps":["Structural basis of scaffold assembly unknown","Whether IGFBP-3 DNA repair function operates in non-cancer contexts not tested","Relative contribution of intracellular versus secreted IGFBP-3 pools to repair unclear"]},{"year":2020,"claim":"Demonstrating that IGFBP-3 signals through the death receptor TMEM219 to cause beta cell apoptosis, and that genetic or pharmacological blockade prevents diabetes, defined a receptor-mediated pro-death pathway with direct disease relevance.","evidence":"TMEM219 genetic ablation and pharmacological IGFBP3/TMEM219 inhibition in T1D/T2D preclinical models with diabetes onset monitoring","pmids":["35115561"],"confidence":"High","gaps":["Downstream signaling cascade from TMEM219 not fully delineated","Human clinical validation of TMEM219 blockade pending"]},{"year":2020,"claim":"Elucidating the TGF-β/GIPC → epigenetic (H3K27ac/me3) → IGFBP-3 → integrin/Akt cascade in hepatic stellate cells, validated by Igfbp3 knockout reducing portal pressure, linked IGFBP-3 to liver fibrosis pathogenesis.","evidence":"RNA-seq, ChIP for H3K27ac/me3, Igfbp3 global knockout mouse with portal pressure measurement and HSC migration assays","pmids":["32447051"],"confidence":"High","gaps":["Which integrin(s) transduce IGFBP-3's migration signal not identified","Cell-autonomous versus paracrine contribution in vivo not separated"]},{"year":2020,"claim":"Showing that intracellular IGFBP-3 activates THBS1 transcription to inhibit angiogenesis, with THBS1 knockdown reversing the effect, identified THBS1 as a key effector of IGFBP-3's anti-angiogenic function.","evidence":"Inducible IGFBP3 overexpression, THBS1 promoter luciferase assay, THBS1 siRNA rescue, HUVEC tube formation, CAM assay, xenograft vascular assessment","pmids":["32642286"],"confidence":"Medium","gaps":["Transcription factor mediating IGFBP-3's activation of THBS1 promoter not identified","Whether IGFBP-3 binds THBS1 promoter directly not tested"]},{"year":2022,"claim":"Identifying IGFBP-3 as a regulator of the BNIP3L/NIX short isoform and mitochondrial cristae morphology established it as a modulator of mitophagy and mitochondrial quality control.","evidence":"IGFBP-3 siRNA and overexpression with sBNIP3L/NIX western blot, mitochondrial respiration measurement, nuclear fractionation, and electron microscopy in corneal epithelial cells","pmids":["34918377"],"confidence":"Medium","gaps":["Mechanism by which IGFBP-3 controls sBNIP3L/NIX isoform expression unknown","Whether this mitophagy function is tissue-specific not explored"]},{"year":2023,"claim":"Demonstrating that METTL3-mediated m6A modification of IGFBP3 mRNA drives cardiac fibroblast activation added an epitranscriptomic regulatory layer to IGFBP-3 biology in cardiac fibrosis.","evidence":"METTL3 shRNA knockdown, m6A methylation analysis, TGF-β1 stimulation, fibroblast assays, and TAC/isoproterenol mouse models","pmids":["36657656"],"confidence":"Medium","gaps":["Specific m6A site(s) on IGFBP3 mRNA not mapped","m6A reader protein mediating IGFBP3 mRNA stabilization not identified"]},{"year":null,"claim":"Key unresolved questions include the structural basis for IGFBP-3's nuclear scaffolding functions, the signaling cascade downstream of TMEM219, the mechanism governing the switch between IGF-dependent and IGF-independent activities, and the relative contributions of intracellular versus extracellular IGFBP-3 pools to its diverse biological functions.","evidence":"","pmids":[],"confidence":"Low","gaps":["No atomic-resolution structure of IGFBP-3 in complex with nuclear partners","TMEM219 downstream signaling intermediates remain uncharacterized","Context determinants of pro-growth versus pro-apoptotic switching undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,5,15,25]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[27]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[9,17]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[9,13,16,17,23]},{"term_id":"GO:0005576","term_label":"extracellular region","supporting_discovery_ids":[0,1,14,22]},{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[23,26]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[9]}],"pathway":[{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[9,13,15,20,26]},{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[17]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[3,10,11,18,19,20]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[5,15,20,25]}],"complexes":["IGFBP-3/NONO/SFPQ/EGFR/DNA-PKcs NHEJ repair complex","IGFBP-3/Nur77/RXRα nuclear export complex","IGFBP-3/IGF/ALS ternary circulating complex"],"partners":["NONO","SFPQ","EGFR","PRKDC","NR4A1","RXRA","TMEM219","IGF1"],"other_free_text":[]},"mechanistic_narrative":"IGFBP-3 is a multifunctional secreted glycoprotein that serves as the principal circulating carrier for IGF-I and IGF-II, sequestering IGFs with ~50 pM affinity to regulate their bioavailability and half-life, while also exerting extensive IGF-independent signaling through nuclear translocation, receptor engagement, and intracellular protein interactions [PMID:7683528, PMID:28330997]. Its transcription is induced by p53, HIF-1α, TGF-β, BMP2, and METTL3-mediated m6A modification, and its proteolytic degradation by proteases such as ADAM28 releases free IGF-I to drive proliferation [PMID:22415309, PMID:10873390, PMID:32975335, PMID:30429106]. In the nucleus, IGFBP-3 forms complexes with EGFR, DNA-PKcs, NONO, and SFPQ to promote NHEJ-dependent DNA double-strand break repair, facilitates nuclear export of the pro-apoptotic Nur77/RXRα complex, mediates SUMOylation-dependent nuclear translocation of IGF-1R, and regulates mitochondrial homeostasis through the BNIP3L/NIX mitophagy receptor [PMID:30725116, PMID:26340041, PMID:30078228, PMID:34918377]. IGFBP-3 signals through the death receptor TMEM219 to induce pancreatic beta cell apoptosis, and TMEM219 ablation or IGFBP-3 blockade preserves beta cell mass and delays diabetes onset in preclinical models [PMID:35115561]."},"prefetch_data":{"uniprot":{"accession":"P17936","full_name":"Insulin-like growth factor-binding protein 3","aliases":[],"length_aa":291,"mass_kda":31.7,"function":"Multifunctional protein that plays a critical role in regulating the availability of IGFs such as IGF1 and IGF2 to their receptors and thereby regulates IGF-mediated cellular processes including proliferation, differentiation, and apoptosis in a cell-type specific manner (PubMed:10874028, PubMed:19556345). Also exhibits IGF-independent antiproliferative and apoptotic effects mediated by its receptor TMEM219/IGFBP-3R (PubMed:20353938). Inhibits the positive effect of humanin on insulin sensitivity (PubMed:19623253). Promotes testicular germ cell apoptosis (PubMed:19952275). Acts via LRP-1/alpha2M receptor, also known as TGF-beta type V receptor, to mediate cell growth inhibition independent of IGF1 (PubMed:9252371). Mechanistically, induces serine-specific dephosphorylation of IRS1 or IRS2 upon ligation to its receptor, leading to the inhibitory cascade (PubMed:15371331). In the nucleus, interacts with transcription factors such as retinoid X receptor-alpha/RXRA to regulate transcriptional signaling and apoptosis (PubMed:10874028)","subcellular_location":"Secreted; Nucleus","url":"https://www.uniprot.org/uniprotkb/P17936/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/IGFBP3","classification":"Not Classified","n_dependent_lines":7,"n_total_lines":1208,"dependency_fraction":0.005794701986754967},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/IGFBP3","total_profiled":1310},"omim":[{"mim_id":"620290","title":"TRANSMEMBRANE PROTEIN 219; TMEM219","url":"https://www.omim.org/entry/620290"},{"mim_id":"619489","title":"SHORT STATURE, DAUBER-ARGENTE TYPE; SSDA","url":"https://www.omim.org/entry/619489"},{"mim_id":"619485","title":"PAPPALYSIN 2; PAPPA2","url":"https://www.omim.org/entry/619485"},{"mim_id":"618907","title":"SILVER-RUSSELL SYNDROME 4; SRS4","url":"https://www.omim.org/entry/618907"},{"mim_id":"618905","title":"SILVER-RUSSELL SYNDROME 2; SRS2","url":"https://www.omim.org/entry/618905"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Uncertain","locations":[{"location":"Vesicles","reliability":"Uncertain"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"placenta","ntpm":1748.7}],"url":"https://www.proteinatlas.org/search/IGFBP3"},"hgnc":{"alias_symbol":["IBP3","BP-53"],"prev_symbol":[]},"alphafold":{"accession":"P17936","domains":[{"cath_id":"4.10.40.20","chopping":"44-126","consensus_level":"high","plddt":90.75,"start":44,"end":126},{"cath_id":"4.10.800.10","chopping":"208-278","consensus_level":"medium","plddt":81.2162,"start":208,"end":278}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P17936","model_url":"https://alphafold.ebi.ac.uk/files/AF-P17936-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P17936-F1-predicted_aligned_error_v6.png","plddt_mean":68.12},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=IGFBP3","jax_strain_url":"https://www.jax.org/strain/search?query=IGFBP3"},"sequence":{"accession":"P17936","fasta_url":"https://rest.uniprot.org/uniprotkb/P17936.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P17936/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P17936"}},"corpus_meta":[{"pmid":"20472501","id":"PMC_20472501","title":"Insulin-like growth factor 1 (IGF1), IGF binding protein 3 (IGFBP3), and breast cancer risk: pooled individual data analysis of 17 prospective studies.","date":"2010","source":"The Lancet. 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phytopharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/34798519","citation_count":18,"is_preprint":false},{"pmid":"31961798","id":"PMC_31961798","title":"Anthropometric and biochemical correlates of PAPP-A2, free IGF-I, and IGFBP-3 in childhood.","date":"2020","source":"European journal of endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/31961798","citation_count":17,"is_preprint":false},{"pmid":"19765833","id":"PMC_19765833","title":"Changes in IGF-I, IGFBP-3 and ghrelin levels after adenotonsillectomy in children with sleep disordered breathing.","date":"2009","source":"International journal of pediatric otorhinolaryngology","url":"https://pubmed.ncbi.nlm.nih.gov/19765833","citation_count":17,"is_preprint":false},{"pmid":"30335898","id":"PMC_30335898","title":"Investigation of IGF1, IGF2BP2, and IGFBP3 variants with lymph node status and esophagogastric junction adenocarcinoma risk.","date":"2018","source":"Journal of cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/30335898","citation_count":17,"is_preprint":false},{"pmid":"17689128","id":"PMC_17689128","title":"Serum ghrelin levels but not GH, IGF-1 and IGFBP-3 levels are altered in patients with fibromyalgia syndrome.","date":"2007","source":"Joint bone spine","url":"https://pubmed.ncbi.nlm.nih.gov/17689128","citation_count":17,"is_preprint":false},{"pmid":"34918377","id":"PMC_34918377","title":"IGFBP-3 functions as a molecular switch that mediates mitochondrial and metabolic homeostasis.","date":"2022","source":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/34918377","citation_count":17,"is_preprint":false},{"pmid":"30429106","id":"PMC_30429106","title":"ADAM28 promotes tumor growth and dissemination of acute myeloid leukemia through IGFBP-3 degradation and IGF-I-induced cell proliferation.","date":"2018","source":"Cancer 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and IGFBPrP1 in cellular immortalization.","date":"2007","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/17451653","citation_count":13,"is_preprint":false},{"pmid":"25947142","id":"PMC_25947142","title":"Circulating IGF1 and IGFBP3 in relation to the development of β-cell autoimmunity in young children.","date":"2015","source":"European journal of endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/25947142","citation_count":13,"is_preprint":false},{"pmid":"25556430","id":"PMC_25556430","title":"Induction of apoptosis by IGFBP3 overexpression in hepatocellular carcinoma cells.","date":"2014","source":"Asian Pacific journal of cancer prevention : APJCP","url":"https://pubmed.ncbi.nlm.nih.gov/25556430","citation_count":13,"is_preprint":false},{"pmid":"20039319","id":"PMC_20039319","title":"IGF1, IGFBP1, and IGFBP3 genes and mammographic density: the Multiethnic Cohort.","date":"2010","source":"International journal of cancer","url":"https://pubmed.ncbi.nlm.nih.gov/20039319","citation_count":13,"is_preprint":false},{"pmid":"31658437","id":"PMC_31658437","title":"Associations of plasma IGF1, IGFBP3 and estradiol with leucocyte telomere length, a marker of biological age, in men.","date":"2020","source":"European journal of endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/31658437","citation_count":13,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":56386,"output_tokens":7294,"usd":0.139284},"stage2":{"model":"claude-opus-4-6","input_tokens":11057,"output_tokens":4411,"usd":0.24834},"total_usd":0.387624,"stage1_batch_id":"msgbatch_01DzrsgVgYngY1hvM3DU1yF2","stage2_batch_id":"msgbatch_01KA9b7iRzKFdhoBUT7vCvSe","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1993,\n      \"finding\": \"Glycosylated and non-glycosylated forms of recombinant IGFBP-3 bind IGF-I with equal affinity (Kd ~50 pM), and both forms extend IGF-I half-life in vivo by forming a 40–140 kDa circulating complex; glycosylation delays peak IGF-I levels post-injection but does not alter overall bioavailability.\",\n      \"method\": \"Competition binding assay, real-time biospecific interaction analysis (BIA), in vivo subcutaneous injection in rats with gel filtration of serum\",\n      \"journal\": \"Growth regulation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro binding assay plus in vivo pharmacokinetic validation with structural characterization of circulating complexes\",\n      \"pmids\": [\"7683528\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"Proteolysis of IGFBP-3 by plasmin, thrombin, and pregnancy serum generates multiple fragments with differential IGF-binding and heparin-binding capacities; the dominant mid-fragment retains both IGF and heparin affinity, while NH2-terminal fragments retain only IGF affinity, demonstrating structural separation of binding domains.\",\n      \"method\": \"Protease digestion, N-terminal sequencing of fragments, ligand blotting for IGF and heparin binding\",\n      \"journal\": \"The American journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — direct in vitro biochemical reconstitution with sequencing and functional binding assays\",\n      \"pmids\": [\"8843739\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Hepatic IGFBP-3 gene transcription is regulated by insulin through an insulin-responsive element that recruits insulin-responsive nuclear factors (demonstrated by gel mobility shift and southwestern blot), while IGF-I increases IGFBP-3 mRNA stability in hepatic non-parenchymal cells.\",\n      \"method\": \"In vitro transcription, gel mobility shift assay, southwestern blot, mRNA stability assay\",\n      \"journal\": \"Progress in nucleic acid research and molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 — multiple in vitro methods in a single lab, no independent replication cited\",\n      \"pmids\": [\"9594576\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"IGFBP-3 mediates TGF-β1-induced cell growth (not only inhibition) in human airway smooth muscle cells; TGF-β1 induces a 10–20-fold increase in IGFBP-3 expression, and blocking IGFBP-3 with antisense oligomers or neutralizing antibody abolishes TGF-β1-induced proliferation.\",\n      \"method\": \"Antisense oligonucleotide knockdown, neutralizing antibody, cell proliferation assay, mRNA/protein expression analysis\",\n      \"journal\": \"American journal of physiology. Lung cellular and molecular physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — two orthogonal loss-of-function approaches (antisense + neutralizing antibody) with consistent results\",\n      \"pmids\": [\"10710527\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"IGFBP-3 is a transcriptional target of p53; genotoxic stress activates p53, which induces IGFBP-3 expression, linking p53-mediated apoptosis to the IGF axis through IGFBP-3 induction.\",\n      \"method\": \"Transcriptional regulation analysis, p53 pathway studies (reviewed with cited experimental evidence)\",\n      \"journal\": \"Molecular genetics and metabolism\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — review synthesizing experimental evidence across multiple studies; original p53-IGFBP3 transcriptional activation established by referenced experiments\",\n      \"pmids\": [\"10873390\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"IGFBP-3 suppresses esophageal tumor formation via IGF-dependent mechanisms (blocking IGF-1R and AKT activation) as shown by IGF-binding mutant IGFBP-3 (Ile56Gly/Leu80Gly/Leu81Gly) losing tumor suppressor activity in vivo, while the mutant also reveals an IGF-independent growth-stimulatory activity.\",\n      \"method\": \"Stable transduction of wild-type vs. IGF-binding mutant IGFBP-3 in Ras-transformed human esophageal cells, xenograft tumor formation, in vivo bioluminescence imaging, AKT/IGF-1R signaling assays\",\n      \"journal\": \"Cancer biology & therapy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — active-site mutagenesis combined with in vivo xenograft and signaling readouts\",\n      \"pmids\": [\"17457048\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"IGFBP-3 regulates the appearance of senescence biomarkers in human diploid fibroblasts; siRNA knockdown of IGFBP-3 attenuates stress-induced premature senescence following repeated oxidative insults.\",\n      \"method\": \"siRNA knockdown, DNA array screening, senescence biomarker assays\",\n      \"journal\": \"Free radical biology & medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — siRNA loss-of-function with specific phenotypic readout in a clean cellular model\",\n      \"pmids\": [\"18329388\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"IGFBP3 co-localizes with hypocretin/orexin in hypothalamic neurons and overexpression of IGFBP3 in transgenic mice decreases hypocretin mRNA and peptide levels and increases sleep, likely through decreased hypocretin promoter activity.\",\n      \"method\": \"Transgenic mouse overexpression, mRNA expression analysis, hypocretin peptide measurement, sleep phenotyping, promoter activity assay\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo gain-of-function with multiple orthogonal readouts in a single study\",\n      \"pmids\": [\"19158946\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Hypoxia induces IGFBP3 in esophageal squamous cancer cells through HIF-1α (but not HIF-2α) binding to a novel hypoxia-responsive element (HRE) 57 kb upstream of the transcription start site; under hypoxia, global cap-dependent translation is suppressed but IGFBP3 mRNA remains enriched in polysomes allowing continued synthesis.\",\n      \"method\": \"RNAi (HIF-1α vs HIF-2α), chromatin immunoprecipitation, transfection reporter assays, metabolic labeling, 7-methyl GTP-cap binding assay, mTOR pharmacological inhibition, polysome fractionation\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — multiple orthogonal methods (ChIP, reporter, metabolic labeling, polysome fractionation) in a single rigorous study\",\n      \"pmids\": [\"22415309\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"IGFBP-3 interacts with the retinoid X receptor-α (RXRα) and facilitates phosphorylation and nuclear export of the orphan nuclear receptor Nur77 to the cytoplasm in response to apoptotic stimuli, where Nur77 exerts its pro-apoptotic effect; IGFBP-3 knockdown attenuates caspase-3/7 activation and Nur77 nuclear export.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown, indirect immunofluorescence, cell fractionation, caspase activity assay\",\n      \"journal\": \"Endocrinology (2015 paper)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP plus multiple functional readouts (caspase assay, fractionation, immunofluorescence) in a single study\",\n      \"pmids\": [\"26340041\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"TGF-β1 induces IGFBP-3 expression in osteosarcoma cells, and IGFBP-3 then attenuates TGF-β1 activation of ERK1/2 and Akt, inhibits TGF-β1-induced cell cycle progression, and enhances non-canonical Smad2 phosphorylation at Ser245/250/255; blocking IGFBP-3 induction enhances pSmad2 nuclear accumulation, revealing a negative-feedback loop.\",\n      \"method\": \"IGFBP-3 siRNA, IGF1R inhibition, western blotting for ERK, Akt, Smad2 phosphorylation, cell cycle analysis, proliferation assay\",\n      \"journal\": \"Molecular and cellular endocrinology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — siRNA knockdown combined with pharmacological inhibition and multiple signaling readouts\",\n      \"pmids\": [\"23831640\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"IGFBP-3 signals through a specific IGFBP-3 receptor on retinal endothelial cells; overexpression of IGFBP-3 upregulates its receptor, and siRNA knockdown of the receptor abolishes IGFBP-3's anti-apoptotic effect, demonstrating receptor-dependent signaling to regulate Bcl-xL, Bax, cytochrome C, and Akt.\",\n      \"method\": \"Co-immunoprecipitation, co-localization, siRNA knockdown of IGFBP-3 receptor, western blotting, cell death ELISA, caspase-3 ELISA\",\n      \"journal\": \"Apoptosis\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — receptor Co-IP plus siRNA rescue with defined signaling readouts\",\n      \"pmids\": [\"23291901\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Novel ligands of IGFBP-3 include the retinoid X receptor, retinoic acid receptor-α, Nur77, vitamin D receptor, PPARγ, TGFβ/Smad signaling components, LRP1, TMEM219, EGFR, DNA-PK, and GRP78; these interactions mediate IGF-independent functions including apoptosis (via caspase-8 and -9), DNA DSB repair, and autophagy.\",\n      \"method\": \"Multiple binding and functional studies cited in review including Co-IP, cell-free binding assays, and loss-of-function experiments\",\n      \"journal\": \"Journal of cell communication and signaling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — comprehensive review consolidating multiple single-lab interaction studies\",\n      \"pmids\": [\"23700234\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Humanin peptide directly binds IGFBP-3 (Kd ~5.05 µM) and competitively inhibits IGFBP-3 binding to importin-β1 (IC50 ~18.1 µM), thereby blocking nuclear translocation of IGFBP-3 and attenuating IGFBP-3-induced apoptosis in lung adenocarcinoma cells.\",\n      \"method\": \"Competitive ligand dot blotting, co-immunoprecipitation, ELISA-based binding assay, apoptosis assay\",\n      \"journal\": \"Protein and peptide letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — binding affinity quantified by multiple methods plus functional apoptosis rescue\",\n      \"pmids\": [\"26216267\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Pancreatic cancer cell-derived IGFBP-3 causes muscle wasting by inhibiting IGF signaling, impairing myogenesis, and enhancing protein degradation in muscle cells; conditioned medium from IGFBP3-knockdown pancreatic cancer cells or IGFBP-3 antibody neutralization reverses these effects.\",\n      \"method\": \"siRNA knockdown, conditioned medium transfer, IGFBP-3 neutralizing antibody, myogenesis assays, protein degradation assays, C2C12 muscle cell biochemical assays\",\n      \"journal\": \"Journal of experimental & clinical cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — two independent loss-of-function approaches (siRNA + antibody neutralization) with specific cellular readouts\",\n      \"pmids\": [\"26975989\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"IGFBP3 modulates lung tumor growth through IGF1 signaling; Igfbp3-null mice show >2-fold increased lung tumor burden in a Kras model, and overexpression of wild-type IGFBP3 (but not an IGF-binding mutant) in NSCLC cells induces apoptosis (10-fold increase in cleaved caspase-3) and inactivates IGF1 and MAPK signaling.\",\n      \"method\": \"Igfbp3 knockout mouse crossed with Kras lung tumor model, wild-type vs. IGF-binding mutant IGFBP3 overexpression, caspase-3 cleavage assay, IGF1/MAPK signaling analysis\",\n      \"journal\": \"Molecular cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — in vivo genetic model plus mutant rescue experiment dissecting IGF-dependent mechanism\",\n      \"pmids\": [\"28330997\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"IGFBP-3 mediates nuclear translocation of IGF-1R in corneal epithelial cells under serum-free/stress conditions via SUMO 2/3-mediated SUMOylation; IGFBP-3 and IGF-1R undergo reciprocal regulation independent of PI3K/Akt, with IGFBP-3 arresting the cell cycle in G0/G1 and maintaining nuclear IGF-1R levels under stress.\",\n      \"method\": \"Immunofluorescence, nuclear fractionation, SUMOylation assay, siRNA knockdown, cell cycle analysis\",\n      \"journal\": \"Journal of cellular physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct localization experiments with functional consequence, single lab\",\n      \"pmids\": [\"30078228\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"IGFBP-3 forms nuclear complexes with NONO and SFPQ (non-POU domain-containing octamer-binding protein and splicing factor, proline/glutamine-rich) in a PARP-dependent and EGFR/DNA-PKcs-dependent manner in triple-negative breast cancer cells in response to DNA damage; these complexes promote DSB repair by NHEJ and are blocked by PARP inhibitors; LINP1 lncRNA is required for complex formation.\",\n      \"method\": \"LC-MS/MS interactome, co-immunoprecipitation, proximity ligation assay, cell-free biochemical binding assay, DNA end-joining in vitro assay, γH2AX foci measurement, pharmacological inhibitors, siRNA knockdown\",\n      \"journal\": \"Cellular and molecular life sciences\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — mass spectrometry interactome confirmed by Co-IP and PLA, with cell-free biochemical assay and multiple functional readouts\",\n      \"pmids\": [\"30725116\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"ROS- and HIF-1α-dependent upregulation of IGFBP3 under high-glucose/hyperglycemic conditions sequesters extracellular IGF1 from the IGF1 survival pathway, blocking IGF1R signaling and leading to cardiomyocyte apoptosis; PHD inhibition stabilizes HIF1α to drive this cascade.\",\n      \"method\": \"Co-IP assay, western blotting, siRNA knockdown, gain/loss-of-function, pharmacological inhibitors, hyperglycemic cell models and diabetic rat in vivo\",\n      \"journal\": \"Journal of cellular physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple methods in single lab with in vivo confirmation\",\n      \"pmids\": [\"30659610\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"TGF-β increases IGFBP-3 expression in hepatic stellate cells (HSCs) through GIPC/synectin via epigenetic changes (increased H3K27 acetylation, decreased H3K27me3); IGFBP-3 in turn promotes HSC migration through integrin-dependent phosphorylation of Akt; global Igfbp3 knockout mice show attenuated HSC activation and reduced portal pressure.\",\n      \"method\": \"mRNA sequencing, ELISA, qPCR, targeted chromatin immunoprecipitation (H3K27ac/me3), western blot, Igfbp3 global knockout mouse, portal pressure measurement, in vitro migration assay\",\n      \"journal\": \"Cellular and molecular gastroenterology and hepatology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — in vivo genetic knockout with in vitro mechanistic dissection using ChIP and signaling readouts\",\n      \"pmids\": [\"32447051\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"IGFBP3 signaling through the death receptor TMEM219 on pancreatic beta cells causes beta cell loss and dysfunction; TMEM219 genetic ablation or short-term IGFBP3/TMEM219 inhibition preserves beta cells and prevents/delays diabetes onset, while long-term blockade allows beta cell expansion.\",\n      \"method\": \"TMEM219 genetic ablation, pharmacological IGFBP3/TMEM219 inhibition in vitro and in vivo, diabetes onset monitoring in T1D/T2D preclinical models, human patient cohort correlation\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — in vivo genetic model plus pharmacological intervention with defined mechanistic pathway\",\n      \"pmids\": [\"35115561\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"BMP2 upregulates IGFBP3 in human endometrial stromal cells through ALK3 receptor and ID1 as an intermediary; IGFBP3 in turn promotes MMP2 expression and cell migration; knockdown of either IGFBP3 or ID1 abolishes BMP2-induced MMP2 upregulation and migration.\",\n      \"method\": \"siRNA knockdown of ALK3, ID1, and IGFBP3, dose-response and time-course expression studies, cell migration assay in human endometrial stromal cells\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — three-step pathway dissection by sequential siRNA knockdowns with functional migration readout\",\n      \"pmids\": [\"32975335\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Hepatic stellate cell-derived IGFBP3 directly induces lipid droplet formation, triglyceride accumulation, and lipogenic gene expression in hepatocytes in vitro; recombinant IGFBP3 treatment phenocopies and IGFBP3 serum levels are elevated in alcoholic hepatitis patients.\",\n      \"method\": \"HSC supernatant transfer, adipokine antibody array, recombinant IGFBP3 treatment of hepatocytes, triglyceride assay, lipid droplet staining, lipogenic gene expression, NRP-1 HSC-selective knockout mouse model\",\n      \"journal\": \"Journal of hepatology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — gain-of-function with recombinant protein plus genetic model, single lab\",\n      \"pmids\": [\"32087348\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"IGFBP-3 acts as a molecular switch regulating mitochondrial homeostasis in corneal epithelial cells by controlling the short isoform of the BNIP3L/NIX mitophagy receptor; both loss and gain of IGFBP-3 function increase mitochondrial respiration associated with nuclear accumulation of IGFBP-3, and IGFBP-3 regulates lamellar cristae morphology and mitochondrial dynamics.\",\n      \"method\": \"IGFBP-3 siRNA knockdown and overexpression, mitophagy receptor (sBNIP3L/NIX) western blotting, mitochondrial respiration measurement, nuclear fractionation, electron microscopy of cristae morphology\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — gain and loss of function with multiple orthogonal mitochondrial readouts, single lab\",\n      \"pmids\": [\"34918377\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"METTL3-mediated m6A RNA modification upregulates IGFBP3 expression in cardiac fibroblasts; METTL3 silencing downregulates IGFBP3 and inhibits cardiac fibroblast activation, migration and proliferation both in vitro and in vivo in TAC and isoproterenol cardiac fibrosis models.\",\n      \"method\": \"RNA-seq, shRNA knockdown of METTL3, m6A methylation analysis, TGF-β1 stimulation, fibroblast migration and proliferation assays, in vivo mouse cardiac fibrosis models\",\n      \"journal\": \"European journal of pharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo and in vitro loss-of-function with mechanistic m6A modification link, single lab\",\n      \"pmids\": [\"36657656\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"ADAM28 metalloprotease degrades IGFBP-3, thereby increasing free IGF-I availability and promoting IGF-I-induced proliferation and migration of acute myeloid leukemia cells; ADAM28 knockout in a xenotransplantation mouse model reduces leukemic cell growth and dissemination.\",\n      \"method\": \"ADAM28 knockout, IGFBP-3 degradation assay, IGF-I signaling measurement, xenotransplantation mouse model, proliferation and migration assays\",\n      \"journal\": \"Cancer letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo genetic model plus mechanism of IGFBP3 proteolytic degradation\",\n      \"pmids\": [\"30429106\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"IGFBP-3 induces apoptosis in chondrocytes through nucleus-to-mitochondria translocation of the nuclear receptor Nur77, mechanistically linking IGFBP-3 to osteoarthritis pathogenesis.\",\n      \"method\": \"Exogenous recombinant IGFBP-3 treatment of cultured chondrocytes, CCK-8 assay, flow cytometry, laser confocal microscopy for Nur77 localization\",\n      \"journal\": \"International journal of clinical and experimental pathology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — single lab, single method for each readout, no independent validation\",\n      \"pmids\": [\"26884829\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"IGFBP-3 inhibits angiogenesis through intracellular regulation of THBS1 (thrombospondin-1) expression via THBS1 promoter activation; intracellular IGFBP-3 shows stronger THBS1 promoter activation than extracellular IGFBP-3, and THBS1 silencing reverses IGFBP3-mediated inhibition of tube formation and blood vessel development.\",\n      \"method\": \"Inducible IGFBP3 overexpression in ovarian cancer cells, HUVEC capillary tube formation assay, CAM assay, luciferase promoter assay, THBS1 siRNA rescue, in vivo xenograft with vascular assessment\",\n      \"journal\": \"American journal of cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — luciferase promoter assay plus in vitro and in vivo functional assays with siRNA rescue\",\n      \"pmids\": [\"32642286\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Epac1 activates IGFBP-3, which increases SIRT1 levels, leading to deacetylation of HMGB1 in retinal endothelial cells; IGFBP-3 siRNA abolishes the ability of an Epac1 agonist to reduce HMGB1 acetylation and SIRT1 levels, placing IGFBP-3 as a required intermediary in this signaling pathway.\",\n      \"method\": \"Epac1 conditional knockout mice, siRNA knockdown of IGFBP-3 and SIRT1, immunoprecipitation for acetylated HMGB1, western blot, ELISA\",\n      \"journal\": \"Molecular vision\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo genetic model plus siRNA epistasis with biochemical readouts\",\n      \"pmids\": [\"30581279\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"IGFBP-3 is a multifunctional secreted protein that acts primarily as the major circulating IGF-I/II carrier (binding IGFs with ~50 pM affinity, extending their half-life in a ternary complex with ALS), but also signals independently of IGF through multiple intracellular and cell-surface mechanisms: it is transcriptionally induced by p53, HIF-1α, TGF-β, BMP2, and METTL3-mediated m6A modification; it signals via the death receptor TMEM219 to induce beta-cell apoptosis; it facilitates nuclear export of the pro-apoptotic Nur77/RXRα complex; it forms nuclear complexes with EGFR, DNA-PKcs, NONO, and SFPQ to promote NHEJ-based DNA double-strand break repair; it mediates nuclear translocation of IGF-1R via SUMOylation; it regulates mitochondrial homeostasis through the BNIP3L/NIX mitophagy receptor; it inhibits angiogenesis by activating THBS1 transcription; it promotes hepatic stellate cell migration via integrin-Akt signaling; and it is proteolytically inactivated by ADAM28, releasing free IGF-I to drive cell proliferation.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"IGFBP-3 is a multifunctional secreted glycoprotein that serves as the principal circulating carrier for IGF-I and IGF-II, sequestering IGFs with ~50 pM affinity to regulate their bioavailability and half-life, while also exerting extensive IGF-independent signaling through nuclear translocation, receptor engagement, and intracellular protein interactions [PMID:7683528, PMID:28330997]. Its transcription is induced by p53, HIF-1α, TGF-β, BMP2, and METTL3-mediated m6A modification, and its proteolytic degradation by proteases such as ADAM28 releases free IGF-I to drive proliferation [PMID:22415309, PMID:10873390, PMID:32975335, PMID:30429106]. In the nucleus, IGFBP-3 forms complexes with EGFR, DNA-PKcs, NONO, and SFPQ to promote NHEJ-dependent DNA double-strand break repair, facilitates nuclear export of the pro-apoptotic Nur77/RXRα complex, mediates SUMOylation-dependent nuclear translocation of IGF-1R, and regulates mitochondrial homeostasis through the BNIP3L/NIX mitophagy receptor [PMID:30725116, PMID:26340041, PMID:30078228, PMID:34918377]. IGFBP-3 signals through the death receptor TMEM219 to induce pancreatic beta cell apoptosis, and TMEM219 ablation or IGFBP-3 blockade preserves beta cell mass and delays diabetes onset in preclinical models [PMID:35115561].\",\n  \"teleology\": [\n    {\n      \"year\": 1993,\n      \"claim\": \"Establishing IGFBP-3 as a high-affinity IGF-I carrier that extends IGF half-life in vivo resolved how circulating IGFs are stabilized and buffered from rapid clearance.\",\n      \"evidence\": \"Recombinant glycosylated and non-glycosylated IGFBP-3 binding assays (BIA, competition binding) plus rat in vivo pharmacokinetics with gel filtration\",\n      \"pmids\": [\"7683528\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Ternary complex formation with ALS not directly characterized in this study\", \"Tissue-specific release kinetics not addressed\"]\n    },\n    {\n      \"year\": 1996,\n      \"claim\": \"Mapping protease-generated IGFBP-3 fragments with distinct IGF- versus heparin-binding capacities revealed that proteolysis is not merely degradation but a mechanism to generate functionally distinct modules.\",\n      \"evidence\": \"Plasmin/thrombin digestion with N-terminal sequencing and ligand blotting for IGF and heparin binding\",\n      \"pmids\": [\"8843739\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological protease(s) responsible in vivo not identified\", \"Fragment stability and clearance in circulation not measured\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Demonstrating that p53 and TGF-β1 transcriptionally induce IGFBP-3 placed it at the intersection of tumor suppression and growth factor signaling, revealing context-dependent growth-inhibitory and growth-stimulatory roles.\",\n      \"evidence\": \"Antisense oligonucleotide and neutralizing antibody blockade of IGFBP-3 abolished TGF-β1-induced proliferation in airway smooth muscle cells; p53-IGFBP3 transcriptional activation established by promoter studies\",\n      \"pmids\": [\"10710527\", \"10873390\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct p53 binding site on IGFBP3 promoter not mapped in these studies\", \"Mechanism by which IGFBP-3 switches between growth promotion and inhibition unresolved\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Using IGF-binding-deficient IGFBP-3 mutants in xenografts dissected the IGF-dependent tumor suppressor activity from an IGF-independent growth-stimulatory activity, establishing that IGFBP-3 is bifunctional in cancer.\",\n      \"evidence\": \"Wild-type vs. Ile56Gly/Leu80Gly/Leu81Gly mutant IGFBP-3 in Ras-transformed esophageal cell xenografts with AKT/IGF-1R signaling readouts\",\n      \"pmids\": [\"17457048\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Receptor or target mediating the IGF-independent growth-stimulatory effect not identified\", \"Relevance beyond esophageal cancer not tested\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Identifying a distal HIF-1α-bound HRE 57 kb upstream of IGFBP3 and showing cap-independent polysomal loading of IGFBP3 mRNA under hypoxia explained how IGFBP-3 protein levels are maintained when global translation is suppressed.\",\n      \"evidence\": \"ChIP for HIF-1α, HIF-1α/HIF-2α RNAi, reporter assays, polysome fractionation, and metabolic labeling in esophageal cancer cells\",\n      \"pmids\": [\"22415309\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"IRES or other cap-independent translation element in IGFBP3 mRNA not mapped\", \"Whether this mechanism operates in non-cancer hypoxic tissues unknown\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Discovering that IGFBP-3 physically interacts with RXRα and facilitates Nur77 nuclear export to the cytoplasm for pro-apoptotic action revealed a direct intracellular apoptosis-promoting mechanism independent of IGF sequestration.\",\n      \"evidence\": \"Reciprocal Co-IP, siRNA knockdown, nuclear fractionation, immunofluorescence, and caspase-3/7 activity assays\",\n      \"pmids\": [\"26340041\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of IGFBP-3/RXRα/Nur77 ternary complex unknown\", \"Whether Nur77 export depends on IGFBP-3 nuclear import via importin-β1 not tested\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Demonstrating that IGFBP-3 feeds back on TGF-β1 signaling by attenuating ERK/Akt activation and enhancing non-canonical Smad2 linker phosphorylation established IGFBP-3 as a context-dependent modulator of Smad versus non-Smad TGF-β outputs.\",\n      \"evidence\": \"IGFBP-3 siRNA with western blot for phospho-ERK, phospho-Akt, and phospho-Smad2 (Ser245/250/255) in osteosarcoma cells\",\n      \"pmids\": [\"23831640\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct physical interaction between IGFBP-3 and TGF-β signaling components not shown\", \"Generalizability beyond osteosarcoma untested\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Showing that humanin competes with importin-β1 for IGFBP-3 binding and blocks nuclear translocation identified the nuclear import pathway and a mechanism of IGFBP-3 functional regulation.\",\n      \"evidence\": \"Competitive binding assays (dot blot, Co-IP, ELISA) plus apoptosis rescue in lung adenocarcinoma cells\",\n      \"pmids\": [\"26216267\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"IGFBP-3 NLS mapping not performed\", \"Whether humanin regulation operates physiologically at endogenous concentrations unclear\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Identifying ADAM28 as a protease that degrades IGFBP-3 to release free IGF-I in AML provided a disease-relevant proteolytic activation mechanism by which tumors co-opt the IGF axis.\",\n      \"evidence\": \"ADAM28 knockout xenotransplantation model, IGFBP-3 degradation assay, IGF-I signaling measurement\",\n      \"pmids\": [\"30429106\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Cleavage site(s) on IGFBP-3 not mapped\", \"Contribution relative to other IGFBP-3 proteases in AML not assessed\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Demonstrating that IGFBP-3 mediates IGF-1R nuclear translocation via SUMO2/3-dependent SUMOylation under stress revealed a non-canonical mechanism coupling the IGF axis to nuclear signaling independent of PI3K/Akt.\",\n      \"evidence\": \"Immunofluorescence, nuclear fractionation, SUMOylation assay, siRNA knockdown, and cell cycle analysis in corneal epithelial cells\",\n      \"pmids\": [\"30078228\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"SUMOylation site on IGF-1R not identified\", \"Functional consequence of nuclear IGF-1R downstream of IGFBP-3 not characterized\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Identifying a nuclear IGFBP-3/NONO/SFPQ/EGFR/DNA-PKcs complex required for NHEJ-mediated DSB repair — and showing PARP inhibitor sensitivity — established IGFBP-3 as a scaffold in the DNA damage response with therapeutic implications.\",\n      \"evidence\": \"LC-MS/MS interactome, Co-IP, proximity ligation assay, cell-free end-joining assay, γH2AX foci measurement, pharmacological and siRNA perturbation in TNBC cells\",\n      \"pmids\": [\"30725116\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of scaffold assembly unknown\", \"Whether IGFBP-3 DNA repair function operates in non-cancer contexts not tested\", \"Relative contribution of intracellular versus secreted IGFBP-3 pools to repair unclear\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Demonstrating that IGFBP-3 signals through the death receptor TMEM219 to cause beta cell apoptosis, and that genetic or pharmacological blockade prevents diabetes, defined a receptor-mediated pro-death pathway with direct disease relevance.\",\n      \"evidence\": \"TMEM219 genetic ablation and pharmacological IGFBP3/TMEM219 inhibition in T1D/T2D preclinical models with diabetes onset monitoring\",\n      \"pmids\": [\"35115561\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream signaling cascade from TMEM219 not fully delineated\", \"Human clinical validation of TMEM219 blockade pending\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Elucidating the TGF-β/GIPC → epigenetic (H3K27ac/me3) → IGFBP-3 → integrin/Akt cascade in hepatic stellate cells, validated by Igfbp3 knockout reducing portal pressure, linked IGFBP-3 to liver fibrosis pathogenesis.\",\n      \"evidence\": \"RNA-seq, ChIP for H3K27ac/me3, Igfbp3 global knockout mouse with portal pressure measurement and HSC migration assays\",\n      \"pmids\": [\"32447051\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which integrin(s) transduce IGFBP-3's migration signal not identified\", \"Cell-autonomous versus paracrine contribution in vivo not separated\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Showing that intracellular IGFBP-3 activates THBS1 transcription to inhibit angiogenesis, with THBS1 knockdown reversing the effect, identified THBS1 as a key effector of IGFBP-3's anti-angiogenic function.\",\n      \"evidence\": \"Inducible IGFBP3 overexpression, THBS1 promoter luciferase assay, THBS1 siRNA rescue, HUVEC tube formation, CAM assay, xenograft vascular assessment\",\n      \"pmids\": [\"32642286\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Transcription factor mediating IGFBP-3's activation of THBS1 promoter not identified\", \"Whether IGFBP-3 binds THBS1 promoter directly not tested\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Identifying IGFBP-3 as a regulator of the BNIP3L/NIX short isoform and mitochondrial cristae morphology established it as a modulator of mitophagy and mitochondrial quality control.\",\n      \"evidence\": \"IGFBP-3 siRNA and overexpression with sBNIP3L/NIX western blot, mitochondrial respiration measurement, nuclear fractionation, and electron microscopy in corneal epithelial cells\",\n      \"pmids\": [\"34918377\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which IGFBP-3 controls sBNIP3L/NIX isoform expression unknown\", \"Whether this mitophagy function is tissue-specific not explored\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Demonstrating that METTL3-mediated m6A modification of IGFBP3 mRNA drives cardiac fibroblast activation added an epitranscriptomic regulatory layer to IGFBP-3 biology in cardiac fibrosis.\",\n      \"evidence\": \"METTL3 shRNA knockdown, m6A methylation analysis, TGF-β1 stimulation, fibroblast assays, and TAC/isoproterenol mouse models\",\n      \"pmids\": [\"36657656\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Specific m6A site(s) on IGFBP3 mRNA not mapped\", \"m6A reader protein mediating IGFBP3 mRNA stabilization not identified\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the structural basis for IGFBP-3's nuclear scaffolding functions, the signaling cascade downstream of TMEM219, the mechanism governing the switch between IGF-dependent and IGF-independent activities, and the relative contributions of intracellular versus extracellular IGFBP-3 pools to its diverse biological functions.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No atomic-resolution structure of IGFBP-3 in complex with nuclear partners\", \"TMEM219 downstream signaling intermediates remain uncharacterized\", \"Context determinants of pro-growth versus pro-apoptotic switching undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 5, 15, 25]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [27]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [9, 17]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [9, 13, 16, 17, 23]},\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": [0, 1, 14, 22]},\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [23, 26]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [9]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [9, 13, 15, 20, 26]},\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [17]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [3, 10, 11, 18, 19, 20]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [5, 15, 20, 25]}\n    ],\n    \"complexes\": [\n      \"IGFBP-3/NONO/SFPQ/EGFR/DNA-PKcs NHEJ repair complex\",\n      \"IGFBP-3/Nur77/RXRα nuclear export complex\",\n      \"IGFBP-3/IGF/ALS ternary circulating complex\"\n    ],\n    \"partners\": [\n      \"NONO\",\n      \"SFPQ\",\n      \"EGFR\",\n      \"PRKDC\",\n      \"NR4A1\",\n      \"RXRA\",\n      \"TMEM219\",\n      \"IGF1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}