{"gene":"IRS2","run_date":"2026-06-10T01:55:23","timeline":{"discoveries":[{"year":1995,"finding":"IRS-2 (initially called 4PS) was identified as a second IRS-signaling protein with a conserved amino terminus containing a pleckstrin-homology domain and a phosphotyrosine-binding domain, acting as a scaffold linking insulin, IGF-1, IL-4, IL-9, IL-13, and other cytokine receptors to downstream SH2-domain-containing signaling proteins.","method":"Protein purification, molecular cloning, sequence alignment, and expression analysis in multiple cell types including IRS-1-/- mice","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 / Strong — original purification and cloning paper with sequence-function analysis, foundational study replicated across the field","pmids":["7675087"],"is_preprint":false},{"year":1997,"finding":"IRS-2, like IRS-1, interacts with the juxtamembrane (JM) domain (amino acids 943–984) of the insulin receptor; elevated serine/threonine phosphorylation of IRS-2 induced by TNFα or chronic hyperinsulinemia impairs this interaction and reduces insulin-induced tyrosine phosphorylation of IRS-2.","method":"GST-fusion pulldown with bacterial His6-IR peptides, co-immunoprecipitation in Fao hepatoma cells treated with TNFα or sphingomyelinase, alkaline phosphatase reversal experiments","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro binding assay with defined IR domain peptides plus cell-based functional validation with phosphatase reversal controls","pmids":["9368067"],"is_preprint":false},{"year":1997,"finding":"IRS-2 is encoded by a single-exon gene on murine chromosome 8; in hematopoietic cells IRS-2 predominates over IRS-1 and undergoes distinct tyrosine phosphorylation patterns during insulin versus IL-4 stimulation, conferring signaling specificity through differential interaction with SH2 domains.","method":"Gene isolation, chromosomal mapping, Northern/Western blot tissue expression profiling, interaction with recombinant SH2 domains in 32D cells","journal":"Molecular endocrinology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct molecular characterization in relevant cell types, single lab, multiple methods","pmids":["9013772"],"is_preprint":false},{"year":1997,"finding":"Leptin activates PI-3 kinase via IRS-2 (but not IRS-1) and JAK-2 in C2C12 myotubes; leptin-stimulated PI-3 kinase activity is detected only in IRS-2 immunoprecipitates and in JAK-2 immunoprecipitates, accompanied by tyrosine phosphorylation of both JAK-2 and IRS-2.","method":"PI-3 kinase activity assay in immunoprecipitates using non-cross-reacting IRS-1, IRS-2, JAK-1, and JAK-2 antibodies; tyrosine phosphorylation immunoblotting","journal":"Diabetologia","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — immunoprecipitation kinase assay discriminating IRS-1 versus IRS-2, single lab, two orthogonal readouts","pmids":["9389430"],"is_preprint":false},{"year":1997,"finding":"BDNF stimulates tyrosine phosphorylation of IRS-1 and IRS-2 and their association with PI3-K in cultured cerebral cortical neurons; this signaling is dependent on TrkB kinase activity and is not mediated by direct TrkB–PI3-K association.","method":"Co-immunoprecipitation, Western blotting with phosphotyrosine antibodies, kinase inhibitor (K-252a) experiments in primary cortical neurons","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP with functional kinase inhibitor validation, single lab","pmids":["9374521"],"is_preprint":false},{"year":1999,"finding":"Genetic epistasis in mice shows that Irs-2 is the dominant IRS isoform for beta-cell development and compensation for peripheral insulin resistance, and that Igf-1 receptors promote beta-cell development and survival through the Irs-2 signaling pathway.","method":"Intercross of Irs1+/-, Irs2+/-, and Igf1r+/- null mice; glucose metabolism and beta-cell morphology phenotyping","journal":"Nature genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis with double and triple mutant analysis, replicated in multiple cross combinations","pmids":["10471495"],"is_preprint":false},{"year":2000,"finding":"Tissue-specific epistasis in mice with combined ir/irs-1/irs-2 heterozygous null mutations reveals that IRS-2 plays the dominant role in hepatic insulin signaling, while IRS-1 is predominant in skeletal muscle.","method":"Generation and metabolic phenotyping of ir(+/-), ir/irs-1(+/-), ir/irs-2(+/-), and triple heterozygous mice; euglycemic clamp, insulin signaling assays","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 / Strong — epistasis with multiple genotype combinations and tissue-specific biochemical readouts, independent of previous Withers et al. study","pmids":["10642598"],"is_preprint":false},{"year":2001,"finding":"IRS-2 is phosphorylated on tyrosine by the alpha6beta4 integrin, which promotes IRS-2 association with PI3K; the beta4 subunit tyrosine Y1494 is specifically required for IRS-2 phosphorylation and PI3K activation, and is essential for alpha6beta4-dependent carcinoma invasion.","method":"Co-immunoprecipitation of IRS-2 with PI3K, site-directed mutagenesis of beta4 Y1494, cell invasion assays","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — mutagenesis of defined tyrosine residue combined with co-IP and functional invasion assay, single lab with multiple orthogonal methods","pmids":["11438664"],"is_preprint":false},{"year":2002,"finding":"SOCS1 and SOCS3 bind both IRS-1 and IRS-2 and promote their ubiquitination and proteasomal degradation via the elongin BC ubiquitin-ligase complex; mutations in the SOCS box of SOCS1 that abrogate elongin BC interaction eliminate IRS degradation without affecting SOCS1–IRS binding, demonstrating that the SOCS box recruits the ubiquitin ligase.","method":"Co-immunoprecipitation of endogenous and recombinant IRS proteins with SOCS proteins, ubiquitination assays, SOCS box point mutants, adenoviral hepatic overexpression in mice","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — binding, ubiquitination, mutagenesis, and in vivo adenoviral experiments all in one study with clear mechanistic resolution","pmids":["12228220"],"is_preprint":false},{"year":2002,"finding":"Basal serine/threonine phosphorylation of IRS-2 plays a positive role in subsequent insulin receptor-mediated tyrosine phosphorylation, whereas hyperphosphorylation by GSK3β decreases tyrosine phosphorylation; dephosphorylation of basal sites also increased IGF-1 receptor-mediated IRS-2 phosphorylation, showing divergent regulation compared to the insulin receptor.","method":"In vitro insulin receptor kinase assay on recombinant FLAG-IRS-2 after alkaline phosphatase dephosphorylation or GSK3β hyperphosphorylation; confirmed in endogenous IRS-2 from 3T3-L1 adipocytes","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstituted kinase assay with dephosphorylation/hyperphosphorylation controls, validated in endogenous IRS-2","pmids":["12033942"],"is_preprint":false},{"year":2002,"finding":"Pdx1 expression is reduced in islets of Irs2-/- mice before diabetes onset; transgenic restoration of Pdx1 rescues beta-cell mass and prevents diabetes in Irs2-/- mice, placing Pdx1 downstream of Irs2 signaling in beta-cell survival.","method":"Genetic rescue experiment: Pdx1 transgene on Irs2-/- background; beta-cell mass quantification, glucose tolerance, survival analysis","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis with gain-of-function rescue plus loss-of-function acceleration, clear pathway placement","pmids":["11994408"],"is_preprint":false},{"year":2004,"finding":"PTP1B dephosphorylates and inactivates the insulin receptor, thereby limiting IRS-2-mediated signaling; deletion of Ptp1b in Irs2-/- mice restores peripheral insulin sensitivity and beta-cell area, demonstrating that PTP1B acts upstream of IRS-2 by controlling insulin receptor phosphorylation state.","method":"Double-knockout mouse genetics (Irs2-/-::Ptp1b-/-), metabolic phenotyping, insulin signaling biochemistry","journal":"Diabetes","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis with double-mutant rescue, clear pathway placement upstream of IRS-2","pmids":["14693698"],"is_preprint":false},{"year":2005,"finding":"Hepatic IRS-2 knockdown via adenoviral shRNA upregulates lipogenic enzymes SREBP-1c and fatty acid synthase and causes hepatic lipid accumulation, while IRS-1 knockdown upregulates gluconeogenic enzymes; combined IRS-1/IRS-2 knockdown abolishes Akt→FoxO1 signaling and causes systemic insulin resistance.","method":"Adenoviral shRNA-mediated knockdown of IRS-1, IRS-2, or both in mouse liver; gene expression, metabolic phenotyping, Akt/FoxO1 phosphorylation","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo loss-of-function with defined biochemical and phenotypic readouts, dual-knockdown epistasis","pmids":["15711641"],"is_preprint":false},{"year":2005,"finding":"Exendin-4 increases cAMP in beta cells, which upregulates Irs2 expression and stimulates Akt phosphorylation; Irs2 is required for Ex4-mediated long-term beta-cell growth and survival but not short-term insulin secretion effects, demonstrating that GLP-1 receptor agonists act through the Irs2 branch to expand beta-cell mass.","method":"cAMP measurement in human islets and Min6 cells, Akt phosphorylation, Ex4 treatment of Irs2-/- mice, beta-cell mass quantification","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — mechanistic signaling (cAMP→IRS2→Akt) validated by in vivo loss-of-function in Irs2-/- mice","pmids":["16272563"],"is_preprint":false},{"year":2005,"finding":"Liver-specific deletion of Irs2 combined with whole-body Irs1 knockout abolishes hepatic Akt→FoxO1 signaling and causes hyperglycemia, while single-tissue knockouts cause insulin resistance without diabetes; Irs1 or Irs2 individually regulate hundreds of hepatic genes including Pck1, G6pc, and Igfbp1.","method":"Cre-lox conditional liver-specific Irs2 deletion on Irs1-/- background; insulin signaling, hepatic gene expression microarray, metabolic phenotyping","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional genetics with epistasis, gene expression profiling, and defined biochemical signaling readouts","pmids":["16374520"],"is_preprint":false},{"year":2006,"finding":"Viral-mediated downregulation of the IRS2-Akt signaling pathway in the VTA mediates chronic morphine-induced decrease in dopamine neuron cell size and diminishes morphine reward as measured by conditioned place preference.","method":"Viral-mediated gene transfer of IRS2 dominant negative and constitutively active constructs into rat VTA; neuron size measurement, conditioned place preference behavioral assay","journal":"Nature neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Moderate — viral gain- and loss-of-function in specific brain region with two orthogonal functional readouts (morphology and behavior)","pmids":["17143271"],"is_preprint":false},{"year":2006,"finding":"FoxO1 and IRS-2 form a reciprocal stability circuit: IRS-2 efficiently activates p110α-PI3K→Akt→FoxO1 phosphorylation/degradation, while prolonged insulin stimulation leads to rapamycin-sensitive IRS-2 degradation that allows FoxO1 to re-accumulate; IRS-2 activates p110α-PI3K more efficiently than IRS-1 does.","method":"Wild-type, Irs1-/-, and Irs2-/- mouse embryo fibroblasts; PI3K co-immunoprecipitation, Akt and FoxO1 phosphorylation, rapamycin treatment, immunofluorescence","journal":"Molecular endocrinology","confidence":"High","confidence_rationale":"Tier 2 / Strong — three genetically defined cell lines with pharmacological intervention and multiple biochemical readouts","pmids":["16916938"],"is_preprint":false},{"year":2007,"finding":"IRS-2 binds beta-catenin in vitro and in vivo; transgenic overexpression of IRS-2 in the mammary gland causes progressive hyperplasia, tumorigenesis, and metastasis with extensive squamous differentiation consistent with beta-catenin pathway activation.","method":"Co-immunoprecipitation of IRS-2 with beta-catenin in vitro and in vivo, transgenic mouse mammary tumor model with histopathology","journal":"Molecular and cellular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP plus in vivo transgenic phenotype, single lab","pmids":["17030631"],"is_preprint":false},{"year":2007,"finding":"TFE3, a bHLH transcription factor, directly transactivates the IRS2 promoter via an E-box element; adenoviral TFE3 expression in hepatocytes strongly increases IRS-2 and Akt expression and downstream insulin signaling, reducing blood glucose in multiple diabetic mouse models.","method":"Promoter luciferase reporter assays, adenoviral TFE3 overexpression in hepatocytes and in vivo, Western blotting for IRS-2/Akt phosphorylation","journal":"Nature medicine","confidence":"High","confidence_rationale":"Tier 1 / Moderate — promoter reporter assay establishing direct transcriptional target, confirmed by in vivo adenoviral expression with functional metabolic readouts","pmids":["16327801"],"is_preprint":false},{"year":2007,"finding":"ATF3, a stress-inducible transcription factor, binds to the IRS2 promoter in vivo and represses IRS2 gene transcription, contributing to beta-cell apoptosis; IRS2 overexpression rescues beta-cells from ATF3-induced apoptosis.","method":"Chromatin immunoprecipitation (ChIP) assay, Pol II occupancy assay, gain/loss-of-function ATF3 with IRS2 expression measurement, ATF3 transgenic and IRS2 transgenic mice with RIP-driven transgenes","journal":"Diabetes","confidence":"High","confidence_rationale":"Tier 1 / Moderate — ChIP demonstrating direct promoter binding, Pol II occupancy confirming transcriptional repression, genetic rescue in vivo","pmids":["18057093"],"is_preprint":false},{"year":2007,"finding":"Brain-specific Irs2 knockout mice develop obesity and glucose intolerance, but display greater physical activity and stable hypothalamic SOD2 concentrations during meals, extending lifespan by up to 18%, establishing that Irs2 signaling in the brain coordinates energy balance, oxidative stress responses, and longevity.","method":"Brain-specific Cre-lox Irs2 knockout mice; metabolic phenotyping, activity monitoring, SOD2 immunostaining, lifespan analysis","journal":"Science","confidence":"High","confidence_rationale":"Tier 2 / Strong — tissue-specific genetic ablation with multiple orthogonal phenotypic readouts including lifespan","pmids":["17641201"],"is_preprint":false},{"year":2008,"finding":"Aldosterone promotes degradation of IRS-2 (and IRS-1) through a glucocorticoid receptor-mediated, reactive oxygen species-dependent pathway involving activation of IKKβ and mTORC1; this degradation reduces insulin-induced Akt phosphorylation and glucose uptake in 3T3-L1 adipocytes.","method":"Time- and dose-response IRS protein immunoblotting in 3T3-L1 adipocytes; pharmacological inhibitors of mineralocorticoid receptor, glucocorticoid receptor, NAC (antioxidant), rapamycin, BMS345541, and proteasome inhibitor lactacystin; sucrose-gradient fractionation","journal":"Endocrinology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pharmacological dissection with multiple inhibitors identifying pathway, single lab","pmids":["19095745"],"is_preprint":false},{"year":2009,"finding":"Deletion of PTP1B in IRS2-/- mice restores hepatic IRS1-mediated PI3K/Akt/FoxO1 signaling; in IRS2-/- livers, PTP1B expression and its association with the insulin receptor are increased, and resveratrol treatment reduces PTP1B activity and restores IRS1-mediated signaling.","method":"Double-knockout mouse genetics (IRS2-/-/PTP1B-/-), co-immunoprecipitation of PTP1B with IR, hepatic insulin signaling biochemistry, resveratrol pharmacological intervention","journal":"Diabetes","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis with double knockout plus pharmacological validation, co-IP of PTP1B–IR interaction","pmids":["20028942"],"is_preprint":false},{"year":2010,"finding":"Muscle-specific combined deletion of Irs1 and Irs2 severely reduces skeletal muscle growth, abolishes Akt→mTOR signaling, increases Foxo-dependent atrogene expression and amino acid release, shifts glucose utilization from oxidation to lactate, and elevates AMPK→ACC phosphorylation and fatty acid oxidation.","method":"MCK-Cre driven double muscle-specific Irs1/Irs2 knockout; muscle mass quantification, insulin signaling biochemistry, glucose uptake, metabolic flux, AMPK/ACC phosphorylation","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — tissue-specific double KO with comprehensive biochemical and metabolic characterization","pmids":["21135130"],"is_preprint":false},{"year":2011,"finding":"IRS-2 is phosphorylated during induction of LTP in hippocampus; IRS-2-deficient mice fail to activate postsynaptic NMDA receptors or Fyn, AKT, and MAPK in response to tetanic stimulation, demonstrating IRS-2 as a required component of LTP signaling machinery.","method":"Hippocampal slice electrophysiology (LTP recording), Western blotting for IRS-2 phosphorylation during LTP, biochemical analysis of Fyn/AKT/MAPK in Irs2-/- slices","journal":"Cerebral cortex","confidence":"High","confidence_rationale":"Tier 2 / Strong — loss-of-function electrophysiology combined with direct detection of IRS-2 phosphorylation during LTP induction","pmids":["21955917"],"is_preprint":false},{"year":2011,"finding":"Increasing Irs2 levels in R6/2 HD mouse brains reduces life span and increases neuronal oxidative stress and mitochondrial dysfunction; conversely, reducing Irs2 levels improves motor performance and extends lifespan, associated with increased nuclear FoxO1 and upregulation of FoxO1-dependent autophagy and antioxidant genes.","method":"Genetic modulation of Irs2 levels in R6/2 HD model mice; behavioral testing, mitochondrial function assays, autophagosome counting, oxidative stress markers, FoxO1 nuclear localization","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 / Strong — bidirectional genetic manipulation (gain and loss of function) with multiple orthogonal cellular readouts","pmids":["21926467"],"is_preprint":false},{"year":2012,"finding":"Irs2 signaling in leptin receptor-expressing (LepRb) neurons suppresses FoxO1 to control energy balance; deletion of FoxO1 in LepRb neurons normalizes obesity, glucose homeostasis, and arcuate gene expression caused by Irs2 ablation in those neurons, placing FoxO1 downstream of IRS2 in energy balance regulation.","method":"Lepr-Cre × Irs2-flox conditional knockout; FoxO1 conditional deletion epistasis experiment; metabolic phenotyping, insulin-stimulated FoxO1 nuclear exclusion assay","journal":"Cell metabolism","confidence":"High","confidence_rationale":"Tier 2 / Strong — cell-type-specific genetic ablation with epistatic FoxO1 rescue, defining pathway order","pmids":["22560222"],"is_preprint":false},{"year":2013,"finding":"Angiotensin II and PKCβ2 phosphorylate specific serine residues on IRS-2 (Ser303, Ser343, Ser675) in endothelial cells, inhibiting insulin-induced tyrosine phosphorylation (Tyr653, Tyr671, Tyr911) and downstream Akt/eNOS activation; AngII specifically targets Ser303 to inhibit p-Tyr911 and p-Akt/eNOS.","method":"Site-directed mutagenesis of IRS-2 serine residues (S303A, S675A), PKCβ2 overexpression and dominant-negative, losartan receptor antagonist, phospho-specific antibodies; confirmed in vessels of insulin-resistant Zucker fatty rats","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — mutagenesis of individual phosphorylation sites plus pharmacological inhibitors plus in vivo validation in disease model","pmids":["23775122"],"is_preprint":false},{"year":2013,"finding":"Heart-specific double knockout of IRS1 and IRS2 causes reduced ventricular mass, cardiac apoptosis, fibrosis, and heart failure with diminished Akt→FoxO1 signaling and impaired cardiac metabolic gene expression; chronic insulin exposure reduces cardiac IRS1/IRS2 via p38α MAPK activation.","method":"Heart-specific Cre-lox IRS1/IRS2 double KO; echocardiography, cardiac apoptosis/fibrosis assays, p38 activation in neonatal rat ventricular cardiomyocytes with chronic insulin","journal":"Diabetes","confidence":"High","confidence_rationale":"Tier 2 / Strong — tissue-specific double KO with multiple cardiac phenotype readouts plus cell-based mechanism identifying p38α as the writer of IRS1/2 loss","pmids":["24159000"],"is_preprint":false},{"year":2013,"finding":"Phosphorylation of IRS-2 at Ser1137/1138 by PKA (induced by cAMP/forskolin) promotes binding of 14-3-3 proteins and protects IRS-2 from proteasomal degradation, increasing IRS-2 protein stability.","method":"GST-14-3-3 pulldown assays with deletion constructs, mass spectrometry phosphorylation site identification, Ser1137/1138 alanine mutants, cycloheximide chase stability assay, 14-3-3 antagonist treatment in HEK293 cells and primary hepatocytes","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — MS-identified sites confirmed by mutagenesis, stability assay with cycloheximide, pharmacological and genetic validation","pmids":["23615913"],"is_preprint":false},{"year":2014,"finding":"IRS-2 in endothelial cells is required for normal islet blood flow and glucose-induced insulin secretion; endothelial cell-specific Irs2 knockout impairs islet perfusion, and restoration of blood flow with enalapril rescues insulin secretion.","method":"EC-specific Irs2 knockout (ETIrs2KO) mice; islet perfusion experiments, enalapril pharmacological rescue, glucose and arginine stimulation tests","journal":"Diabetes","confidence":"High","confidence_rationale":"Tier 2 / Strong — cell-type-specific KO with mechanistic pharmacological rescue identifying islet blood flow as the mediating mechanism","pmids":["25277391"],"is_preprint":false},{"year":2014,"finding":"Insulin stimulates IRS2-dependent recruitment of GRK2 to the insulin receptor, which then phosphorylates β2AR at Ser355/356, promoting β2AR internalization and suppression of βAR-induced cAMP-PKA signaling and contractile response in cardiomyocytes; IRS2 deletion disrupts the IR–GRK2 complex.","method":"Co-immunoprecipitation of IRS2 with IR and GRK2; β2AR phosphorylation and internalization assays; IRS2 knockout cardiomyocytes; cAMP and contractility measurements","journal":"Cellular signalling","confidence":"High","confidence_rationale":"Tier 2 / Moderate — co-IP plus loss-of-function with specific phosphorylation and functional readouts, single lab with multiple orthogonal methods","pmids":["25460042"],"is_preprint":false},{"year":2015,"finding":"Nedd4 E3 ubiquitin ligase monoubiquitinates IRS-2, promoting its association with the ubiquitin-binding protein Epsin1 and recruitment of IRS-2 to the plasma membrane; this enhances IGF-I receptor-induced IRS-2 tyrosine phosphorylation, IGF-I signaling, and cell proliferation, confirmed by in vivo zebrafish growth experiments.","method":"Co-immunoprecipitation, ubiquitination assays, Epsin1 binding assays, membrane fractionation, siRNA knockdown, zebrafish IRS-2 knockdown rescue with Nedd4","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Strong — ubiquitination assay identifying Nedd4 as the E3 ligase, Epsin1 interaction, membrane recruitment mechanism, and in vivo zebrafish validation","pmids":["25879670"],"is_preprint":false},{"year":2015,"finding":"IRS2 deficiency in podocytes causes insulin resistance through upregulation of PTEN; suppressing PTEN in Irs2-/- podocytes rescues AKT signaling, GLUT4-mediated glucose uptake, F-actin remodeling, and cell motility, placing PTEN downstream of IRS2 in podocyte insulin signaling.","method":"Conditionally immortalized Irs2-/- podocytes; AKT phosphorylation, GLUT4 glucose uptake assay, F-actin staining, Transwell motility assay, siRNA PTEN knockdown rescue","journal":"Biochimica et biophysica acta","confidence":"High","confidence_rationale":"Tier 2 / Moderate — loss-of-function with PTEN rescue epistasis, multiple orthogonal cellular assays, single lab","pmids":["26384875"],"is_preprint":false},{"year":2016,"finding":"Glucose-induced beta-cell proliferation requires IRS2 and mTOR but not the insulin receptor; IRS2 or mTOR loss reduces cyclin D2 expression, and restoring cyclin D2 rescues the proliferation defect, placing IRS2→mTOR→cyclin D2 as the pathway for glucose-driven beta-cell replication.","method":"IRS2 knockout mice with in vivo hyperglycemia model and ex vivo islet culture; insulin receptor knockout; mTOR/ERK inhibitors; cyclin D2 adenoviral rescue; confirmed in human islets","journal":"Diabetes","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic and pharmacological pathway dissection with rescue epistasis, validated in both mouse and human islets","pmids":["26740601"],"is_preprint":false},{"year":2018,"finding":"YAP/TAZ activation in the liver upregulates IRS2 expression, amplifying AKT signaling; YAP/TAZ ablation or Hippo pathway activation rescues NAFLD and liver cancer in PTEN/SAV1 double-knockout mice, and AAV-Cas9 knockout of IRS2 successfully represses liver tumorigenesis in this model.","method":"PTEN/SAV1 double liver-specific knockout mice; YAP/TAZ/IRS2 expression analysis; AAV-Cas9 IRS2 knockout; AKT inhibitor MK-2206 treatment; correlation of YAP/TAZ and IRS2 in human HCC","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo genetic ablation (AAV-Cas9 IRS2 KO) with tumor phenotype, multiple genetic tools, and human HCC correlation","pmids":["29400692"],"is_preprint":false},{"year":2018,"finding":"IRS2 is recruited to and tyrosine-phosphorylated by oncogenic ALK in neuroblastoma cells; ALK TKI treatment decreases IRS2 recruitment to ALK and IRS2 tyrosine phosphorylation; siRNA depletion of ALK or IRS2 reduces AKT and FoxO3 phosphorylation and decreases viability of ALK-driven neuroblastoma cells.","method":"Quantitative mass spectrometry-based proximal proteomics (IPP), co-immunoprecipitation, phosphotyrosine interactome, siRNA knockdown of IRS2, cell viability assays, ALK TKI treatment","journal":"Science signaling","confidence":"High","confidence_rationale":"Tier 1 / Moderate — MS-based interactome combined with co-IP, loss-of-function, and signaling validation with multiple orthogonal methods","pmids":["30459283"],"is_preprint":false},{"year":2018,"finding":"Downregulation of macrophage IRS2 expression by hyperinsulinemia via insulin receptor impairs IL-4-induced M2a-subtype macrophage activation; mechanistically, loss of IRS2 stabilizes the FoxO1/HDAC3/NCoR1 corepressor complex; myeloid-specific IR knockout preserves IRS2 and IL-4/IRS2/Akt signaling and reduces insulin resistance.","method":"Myeloid cell-specific Irs2-deficient mice and myeloid-specific IR-deficient mice; macrophage polarization assays, co-immunoprecipitation of FoxO1/HDAC3/NCoR1 complex, AKT phosphorylation, high-fat diet metabolic phenotyping","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — cell-type-specific KO of both IRS2 and IR with mechanistic co-repressor complex identified by Co-IP","pmids":["30451856"],"is_preprint":false},{"year":2018,"finding":"IRS2 mutations identified in pleomorphic invasive lobular carcinoma enhance breast cancer cell invasion, defining IRS2 as functionally important in the aggressive nature of PILC through the IR/IGF1R/IRS2 signaling pathway.","method":"Targeted sequencing, functional invasion assays with PILC-derived IRS2 mutants in breast cancer cells","journal":"JCI insight","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional mutant characterization in invasion assays, single lab","pmids":["29669935"],"is_preprint":false},{"year":2019,"finding":"PGC1A, induced by glucagon/cAMP signaling through CREB, drives IRS2 expression while simultaneously reducing IRS1 expression in hepatocytes, thereby shifting the IRS1:IRS2 ratio during fasting; PGC1A-induced IRS2 expression is required for suppression of hepatocyte gluconeogenesis by insulin.","method":"Primary hepatocyte gain- and loss-of-function of PGC1A; CREB inhibitor experiments; ex vivo glucose production assays; in vivo PGC1A hepatic overexpression","journal":"Proceedings of the National Academy of Sciences","confidence":"High","confidence_rationale":"Tier 2 / Moderate — gain and loss of function in primary hepatocytes with CREB mechanistic dissection and in vivo validation","pmids":["30770439"],"is_preprint":false},{"year":2009,"finding":"MAP4K4 is a key mediator of TNF-α-induced decrease of IRS-2 protein levels in primary beta cells (without change in mRNA); MAP4K4 siRNA knockdown protects against TNF-α-induced IRS-2 protein reduction and preserves glucose-stimulated insulin secretion and Akt phosphorylation.","method":"siRNA knockdown of MAP4K4 in human and rat primary FACS-sorted beta cells; IRS-2 protein and mRNA measurement; Akt/AS160 phosphorylation; glucose-stimulated insulin secretion","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA loss-of-function in primary cells with protein vs. mRNA discrimination, single lab","pmids":["19690174"],"is_preprint":false},{"year":2011,"finding":"JNK3 maintains IRS-2 protein expression in insulin-secreting cells and is required for Akt2 (but not Akt1) activation by insulin; JNK3 mediates its effects at the transcriptional level through maintenance of FoxO3A activity that controls IRS2 expression, while JNK1/2 have opposing pro-apoptotic effects.","method":"siRNA silencing of individual JNK isoforms in beta cell lines; IRS-2 protein/mRNA measurement, Akt1/Akt2 and GSK3β phosphorylation, FoxO3A activity assays","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — isoform-specific siRNA knockdown discriminating JNK1/2/3 effects on IRS-2 and downstream signaling, single lab","pmids":["22563476"],"is_preprint":false},{"year":2013,"finding":"HIF-2α activation in liver directly and indirectly induces IRS-2 expression; liver-specific constitutive HIF-2α is sufficient to augment hepatic insulin signaling through IRS-2 induction, and liver Irs2 is both necessary and sufficient to mediate HIF-2α and VEGF inhibition effects on glucose tolerance.","method":"Liver-specific constitutive HIF-2α activation, IRS-2 expression analysis, Irs2-/- rescue experiments, VEGF inhibitor treatment in diabetic db/db mice","journal":"Nature medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic gain-of-function and IRS-2 necessity/sufficiency established through multiple genetic models and pharmacological intervention","pmids":["24037094"],"is_preprint":false},{"year":2016,"finding":"JAK2V617F binds IRS2 in JAK2-mutant HEL cells; IRS2 silencing in JAK2V617F cells decreases STAT5 phosphorylation, reduces cell viability, and increases apoptosis, effects enhanced when combined with ruxolitinib; this interaction is absent in JAK2WT cells.","method":"Co-immunoprecipitation of JAK2 with IRS2, siRNA IRS2 knockdown, cell viability and apoptosis assays, STAT5 phosphorylation; validated with pharmacological IRS1/2 inhibition in primary MPN patient samples","journal":"Oncotarget","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP plus loss-of-function in cell lines and primary patient samples, single lab","pmids":["26755644"],"is_preprint":false},{"year":2022,"finding":"IRS2-PI3K signaling enhances MYC expression by inhibiting GSK3β activity and reducing MYC phosphorylation at Thr58, thereby preventing proteasomal degradation of MYC and sustaining active pS62-MYC to support breast cancer stem cell self-renewal; a T58A-MYC mutant rescues CSC function in Irs2-/- cells.","method":"IRS2 knockout cells, GSK3β activity assays, MYC T58 phosphorylation immunoblotting, proteasome inhibitor experiments, T58A-MYC rescue construct in Irs2-/- cells, CSC sphere assay","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 1 / Moderate — mutagenesis-based epistasis (T58A-MYC rescue in Irs2-/- background) with biochemical mechanism defined, single lab with multiple orthogonal methods","pmids":["36476848"],"is_preprint":false},{"year":2011,"finding":"Chronic central leptin infusion decreases the association between the insulin receptor β chain and IRS2 in the hypothalamus, increases SOCS3 association with the insulin receptor, and augments JAK2-IRS2 association, thereby blunting insulin's ability to activate the IRS2-mediated PI3K/Akt pathway.","method":"Co-immunoprecipitation of IRβ with IRS2 and SOCS3, co-IP of JAK2 with IRS2 in rat hypothalamus, chronic icv leptin infusion followed by acute icv insulin injection, Akt phosphorylation biochemistry","journal":"Journal of neurochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP in specific brain region with pharmacological (chronic leptin) intervention, single lab","pmids":["21255014"],"is_preprint":false}],"current_model":"IRS2 is a cytoplasmic scaffolding adaptor with PH and PTB domains that is tyrosine-phosphorylated by the insulin receptor (via its juxtamembrane domain), IGF-1R, ALK, JAK2V617F, TrkA, and the α6β4 integrin to recruit SH2-domain proteins (PI3K p85, Grb2, SHP-2); its activity is positively regulated by Nedd4-mediated monoubiquitination (promoting membrane recruitment via Epsin1) and basal serine phosphorylation, and negatively regulated by SOCS1/3-mediated ubiquitin-proteasomal degradation, serine phosphorylation by PKCβ/AngII (Ser303, Ser675), and MAP4K4; cAMP/PKA-mediated phosphorylation of Ser1137/1138 stabilizes IRS2 via 14-3-3 binding; IRS2 preferentially activates p110α-PI3K→Akt2→FoxO1 to control hepatic glucose/lipid metabolism, beta-cell mass, neuronal function (LTP), dopamine neuron morphology, and energy balance, with transcriptional regulation of IRS2 itself controlled by TFE3, HIF-2α, PGC1A/CREB, CaMKIV/CREB, and ATF3."},"narrative":{"mechanistic_narrative":"IRS2 is a cytoplasmic scaffolding adaptor that couples insulin, IGF-1, and cytokine receptors to downstream PI3K/Akt signaling, controlling whole-body glucose and lipid metabolism, beta-cell mass, and neuronal function [PMID:7675087, PMID:10471495]. Identified originally as the second IRS protein (4PS), it contains an N-terminal pleckstrin-homology and phosphotyrosine-binding domain and links activated receptors to SH2-domain effectors including PI3K [PMID:7675087]; it docks on the juxtamembrane domain of the insulin receptor (residues 943–984), an interaction disrupted by inflammatory serine phosphorylation [PMID:9368067]. Beyond the insulin receptor, IRS2 is tyrosine-phosphorylated by diverse kinases—the α6β4 integrin (via β4 Y1494) in carcinoma invasion [PMID:11438664], TrkB downstream of BDNF and JAK2 downstream of leptin in neural contexts [PMID:9374521, PMID:9389430], oncogenic ALK in neuroblastoma [PMID:30459283], and JAK2V617F in myeloproliferative cells [PMID:26755644]—channeling each into PI3K recruitment. Genetic epistasis establishes IRS2 as the dominant IRS isoform in liver and in beta-cell development and compensation, where IGF-1 receptor signaling acts through IRS2 [PMID:10471495, PMID:10642598]; it preferentially activates p110α-PI3K→Akt→FoxO1 more efficiently than IRS1, forming a reciprocal stability circuit with FoxO1 [PMID:16916938]. The IRS2→Akt→FoxO1 axis drives hepatic glucose/lipid control [PMID:15711641, PMID:16374520], beta-cell survival and proliferation via Pdx1 and mTOR→cyclin D2 [PMID:11994408, PMID:26740601], energy balance and longevity through hypothalamic LepRb neurons [PMID:17641201, PMID:22560222], hippocampal LTP [PMID:21955917], and dopamine-neuron morphology and reward [PMID:17143271]. IRS2 abundance is tightly controlled: positively by Nedd4-mediated monoubiquitination promoting Epsin1-dependent membrane recruitment [PMID:25879670], by basal serine phosphorylation [PMID:12033942], and by PKA phosphorylation of Ser1137/1138 that recruits 14-3-3 to block degradation [PMID:23615913]; and negatively by SOCS1/3-elongin BC-mediated proteasomal degradation [PMID:12228220], PKCβ/AngII serine phosphorylation (Ser303/Ser675) [PMID:23775122], MAP4K4 [PMID:19690174], and aldosterone-driven mTORC1/IKKβ pathways [PMID:19095745]. Its transcription is induced by TFE3, HIF-2α, PGC1A/CREB, and YAP/TAZ and repressed by ATF3, providing nutrient- and stress-responsive control of IRS2 levels [PMID:16327801, PMID:24037094, PMID:30770439, PMID:29400692, PMID:18057093]. Gain-of-function and mutational studies implicate IRS2 in mammary, breast, and liver tumorigenesis through β-catenin, MYC stabilization, and amplified Akt signaling [PMID:17030631, PMID:36476848, PMID:29669935, PMID:29400692].","teleology":[{"year":1995,"claim":"Established that a second IRS protein exists, defining IRS2 as a multi-receptor scaffold that links insulin, IGF-1, and cytokine receptors to SH2-domain effectors and explaining residual signaling in IRS1-deficient cells.","evidence":"Protein purification, cloning, and sequence-function analysis across cell types including IRS1-/- mice","pmids":["7675087"],"confidence":"High","gaps":["Did not resolve receptor-specific phosphosite usage","No structural model of PH/PTB domain engagement"]},{"year":1997,"claim":"Defined the physical receptor-docking interface and showed it is regulated, mapping IRS2 binding to the insulin receptor juxtamembrane domain and demonstrating that inflammatory serine phosphorylation disrupts coupling.","evidence":"GST-fusion pulldown with IR peptides, co-IP in Fao hepatoma cells with TNFα/sphingomyelinase, phosphatase reversal","pmids":["9368067","9013772"],"confidence":"High","gaps":["Specific serine sites mediating disruption not mapped here","Hematopoietic specificity mechanism not fully defined"]},{"year":1997,"claim":"Showed IRS2 mediates signaling for non-insulin receptors, with leptin/JAK2 and BDNF/TrkB driving IRS2-PI3K activation in muscle and neurons, broadening its receptor repertoire.","evidence":"IP-based PI3K activity assays and phosphotyrosine immunoblotting in C2C12 myotubes and primary cortical neurons with kinase inhibitors","pmids":["9389430","9374521"],"confidence":"Medium","gaps":["Direct vs indirect kinase-IRS2 contact not resolved","Physiological relevance in vivo not tested at this stage"]},{"year":1999,"claim":"Placed IRS2 at the center of beta-cell biology, establishing through genetic epistasis that IRS2 is dominant for beta-cell development and peripheral compensation and that IGF-1R acts through IRS2.","evidence":"Intercrosses of Irs1, Irs2, and Igf1r null mice with metabolic and beta-cell phenotyping","pmids":["10471495"],"confidence":"High","gaps":["Downstream effectors in beta cells not yet identified","Tissue-resolved contributions not separated"]},{"year":2000,"claim":"Resolved tissue division of labor among IRS isoforms, demonstrating IRS2 dominance in liver versus IRS1 in skeletal muscle.","evidence":"Combined heterozygous null mouse genetics with euglycemic clamp and signaling assays","pmids":["10642598"],"confidence":"High","gaps":["Molecular basis of tissue specificity unexplained","Did not address transcriptional control of the ratio"]},{"year":2002,"claim":"Defined the dominant degradation and stability machinery controlling IRS2 abundance: SOCS1/3 recruit the elongin BC ubiquitin ligase for proteasomal turnover, while basal serine phosphorylation positively primes IR-mediated tyrosine phosphorylation.","evidence":"Co-IP, ubiquitination assays, SOCS-box point mutants, in vitro IR kinase assays with phosphatase/GSK3β treatments, adenoviral hepatic overexpression","pmids":["12228220","12033942"],"confidence":"High","gaps":["Kinases setting basal positive sites not all defined","Relative quantitative contribution of each pathway in vivo unclear"]},{"year":2002,"claim":"Identified the transcriptional output that sustains beta-cell survival, placing Pdx1 downstream of IRS2 such that Pdx1 restoration rescues beta-cell mass and prevents diabetes.","evidence":"Pdx1 transgene rescue on Irs2-/- background with beta-cell mass and survival analysis","pmids":["11994408"],"confidence":"High","gaps":["Mechanistic link from Akt/FoxO1 to Pdx1 not fully mapped","Did not address proliferation vs survival contributions"]},{"year":2004,"claim":"Positioned PTP1B upstream of IRS2 as a negative regulator acting at the receptor level, with Ptp1b deletion rescuing insulin sensitivity and beta-cell area in Irs2-/- mice.","evidence":"Irs2-/-::Ptp1b-/- double-knockout genetics with metabolic phenotyping","pmids":["14693698"],"confidence":"High","gaps":["Whether PTP1B acts directly on IRS2 not established","Compensatory IRS1 contribution explored only later"]},{"year":2005,"claim":"Defined IRS2's non-redundant hepatic role in lipid versus glucose control and showed cAMP/GLP-1 signaling expands beta-cell mass through IRS2.","evidence":"Adenoviral hepatic shRNA knockdown with gene expression and metabolic readouts; cAMP/Akt analysis and Ex4 treatment of Irs2-/- mice","pmids":["15711641","16272563"],"confidence":"High","gaps":["Mechanism partitioning IRS1 vs IRS2 to distinct gene programs unresolved","Direct cAMP-to-IRS2 transcriptional link not defined here"]},{"year":2006,"claim":"Established the IRS2-FoxO1 reciprocal stability circuit and IRS2's preferential coupling to p110α-PI3K, providing the core signaling logic for downstream metabolic and survival outputs.","evidence":"Wild-type, Irs1-/-, Irs2-/- MEFs with PI3K co-IP, Akt/FoxO1 phosphorylation, and rapamycin treatment","pmids":["16916938"],"confidence":"High","gaps":["Structural basis of p110α preference not defined","In vivo relevance of rapamycin-sensitive degradation not tested here"]},{"year":2006,"claim":"Extended IRS2 function to the nervous system, showing VTA IRS2-Akt signaling controls dopamine-neuron size and morphine reward behavior.","evidence":"Viral dominant-negative and constitutively active IRS2 in rat VTA with morphology and conditioned place preference assays","pmids":["17143271"],"confidence":"High","gaps":["Receptor driving VTA IRS2 phosphorylation not identified","Molecular link to neuronal size not detailed"]},{"year":2007,"claim":"Identified bidirectional transcriptional control of IRS2 by TFE3 (activating) and ATF3 (repressing), connecting IRS2 levels to metabolic improvement and stress-induced beta-cell apoptosis.","evidence":"Promoter luciferase and ChIP/Pol II occupancy assays with adenoviral and transgenic in vivo validation","pmids":["16327801","18057093"],"confidence":"High","gaps":["Combinatorial promoter logic with other factors unresolved","Upstream signals controlling these TFs not fully defined"]},{"year":2007,"claim":"Linked IRS2 to oncogenic signaling beyond metabolism, showing IRS2 binds β-catenin and that mammary overexpression drives hyperplasia, tumorigenesis, and metastasis.","evidence":"Reciprocal co-IP of IRS2 with β-catenin and transgenic mammary tumor model with histopathology","pmids":["17030631"],"confidence":"Medium","gaps":["Direct vs indirect β-catenin binding not structurally defined","Single-lab transgenic model not independently replicated in timeline"]},{"year":2008,"claim":"Expanded the negative-regulatory network, defining an aldosterone/glucocorticoid-receptor, ROS-dependent IKKβ/mTORC1 pathway that degrades IRS2 to impair insulin action.","evidence":"Pharmacological inhibitor dissection in 3T3-L1 adipocytes with sucrose-gradient fractionation","pmids":["19095745"],"confidence":"Medium","gaps":["Direct kinase writing degradation-promoting marks not identified","Single-lab pharmacological inference"]},{"year":2009,"claim":"Identified MAP4K4 as the mediator of TNF-α-induced post-transcriptional loss of IRS2 protein in beta cells, distinguishing protein-level from mRNA-level control.","evidence":"siRNA knockdown in primary FACS-sorted beta cells with protein/mRNA discrimination and insulin secretion readouts","pmids":["19690174"],"confidence":"Medium","gaps":["Direct MAP4K4 substrate sites on IRS2 not mapped","Single-lab finding"]},{"year":2009,"claim":"Refined the PTP1B-IRS2 epistasis to a hepatic mechanism, showing PTP1B loss restores IRS1-mediated PI3K/Akt/FoxO1 signaling in Irs2-/- liver and that resveratrol mimics this.","evidence":"Irs2-/-/Ptp1b-/- genetics, PTP1B-IR co-IP, and resveratrol pharmacology","pmids":["20028942"],"confidence":"High","gaps":["Mechanism of increased PTP1B in Irs2-/- liver unclear","Resveratrol target specificity not fully resolved"]},{"year":2010,"claim":"Demonstrated IRS proteins are required for skeletal muscle growth and metabolic flux, with combined Irs1/Irs2 loss abolishing Akt→mTOR signaling and shifting fuel use.","evidence":"MCK-Cre double muscle-specific knockout with metabolic flux and signaling analysis","pmids":["21135130"],"confidence":"High","gaps":["IRS2-specific contribution versus IRS1 not isolated","Did not address recovery or compensation"]},{"year":2011,"claim":"Established IRS2 as a required component of hippocampal LTP signaling and showed bidirectional roles in neurodegeneration, where lowering Irs2 protects in a Huntington's model via FoxO1-driven autophagy/antioxidant programs.","evidence":"Hippocampal slice electrophysiology with IRS2 phospho-detection; bidirectional Irs2 modulation in R6/2 HD mice","pmids":["21955917","21926467"],"confidence":"High","gaps":["Receptor/kinase phosphorylating IRS2 during LTP not identified","Mechanism linking IRS2 to NMDA/Fyn activation unresolved"]},{"year":2011,"claim":"Identified isoform- and context-specific regulators of IRS2 abundance: JNK3 maintains IRS2 expression transcriptionally via FoxO3A in beta cells, and chronic leptin remodels IR/IRS2/SOCS3/JAK2 associations in hypothalamus.","evidence":"Isoform-specific siRNA in beta cell lines; co-IP in rat hypothalamus with chronic icv leptin and acute insulin","pmids":["22563476","21255014"],"confidence":"Medium","gaps":["Direct vs indirect JNK3 effects not separated","Single-lab co-IP without reciprocal validation in vivo"]},{"year":2012,"claim":"Placed FoxO1 genetically downstream of IRS2 in energy balance, showing FoxO1 deletion in LepRb neurons normalizes the obesity and glucose phenotypes of neuronal Irs2 loss.","evidence":"Lepr-Cre × Irs2-flox conditional knockout with epistatic FoxO1 deletion and metabolic phenotyping","pmids":["22560222"],"confidence":"High","gaps":["Arcuate transcriptional targets mediating the effect not fully defined","Neuron-subtype resolution limited"]},{"year":2013,"claim":"Mapped specific inhibitory serine sites on IRS2 (Ser303/Ser675) phosphorylated by AngII/PKCβ2 that block insulin-induced tyrosine phosphorylation and a stabilizing PKA/14-3-3 mechanism at Ser1137/1138, providing residue-level control of IRS2 activity and stability.","evidence":"Site-directed mutagenesis, phospho-specific antibodies, GST-14-3-3 pulldowns, mass spectrometry, cycloheximide chase in endothelial cells and HEK293/hepatocytes","pmids":["23775122","23615913"],"confidence":"High","gaps":["Interplay between positive and negative serine sites unresolved","In vivo stoichiometry of these modifications unknown"]},{"year":2013,"claim":"Established cardiac and vascular roles for IRS proteins and additional regulators, showing heart-specific IRS1/IRS2 loss causes heart failure (with p38α as a writer of IRS loss) and HIF-2α as a hepatic IRS2 inducer necessary and sufficient for its metabolic effects.","evidence":"Heart-specific double KO with echocardiography and cardiomyocyte p38 analysis; liver-specific HIF-2α activation with Irs2-/- rescue","pmids":["24159000","24037094"],"confidence":"High","gaps":["IRS2-specific cardiac function separate from IRS1 not isolated","Direct vs indirect HIF-2α induction not fully separated"]},{"year":2014,"claim":"Revealed non-canonical and vascular IRS2 functions: IRS2-dependent GRK2 recruitment to the insulin receptor suppresses β2AR/cAMP signaling in cardiomyocytes, and endothelial IRS2 governs islet blood flow required for glucose-induced insulin secretion.","evidence":"Co-IP and phosphorylation/internalization assays in IRS2-knockout cardiomyocytes; EC-specific Irs2 knockout with islet perfusion and enalapril rescue","pmids":["25460042","25277391"],"confidence":"High","gaps":["Structural basis of IR-IRS2-GRK2 complex not resolved","Endothelial IRS2 effectors controlling perfusion not detailed"]},{"year":2015,"claim":"Defined positive ubiquitin-based regulation, showing Nedd4 monoubiquitinates IRS2 to recruit Epsin1 and drive plasma-membrane localization that enhances IGF-1R-induced tyrosine phosphorylation and growth, and extended IRS2 function to podocyte insulin signaling via PTEN.","evidence":"Ubiquitination and Epsin1 binding assays, membrane fractionation, zebrafish rescue; Irs2-/- podocytes with PTEN-knockdown rescue","pmids":["25879670","26384875"],"confidence":"High","gaps":["Ubiquitin chain topology and reversal enzymes not defined","Whether PTEN regulation is direct unresolved"]},{"year":2016,"claim":"Defined the proliferative arm of beta-cell IRS2 signaling, showing glucose-induced replication requires IRS2→mTOR→cyclin D2 independent of the insulin receptor.","evidence":"IRS2 and IR knockout mice, mTOR/ERK inhibitors, and cyclin D2 adenoviral rescue validated in human islets","pmids":["26740601"],"confidence":"High","gaps":["Upstream receptor driving glucose-induced IRS2 activation unidentified","Link from mTOR to cyclin D2 transcription not detailed"]},{"year":2018,"claim":"Consolidated IRS2's roles in cancer and immunometabolism: ALK and YAP/TAZ drive IRS2-dependent AKT signaling in neuroblastoma and liver cancer, IRS2 mutations enhance breast cancer invasion, and macrophage IRS2 controls IL-4-induced M2 polarization via a FoxO1/HDAC3/NCoR1 corepressor.","evidence":"MS-based interactome and siRNA in neuroblastoma; AAV-Cas9 IRS2 knockout in PTEN/SAV1 mice; PILC IRS2-mutant invasion assays; myeloid-specific Irs2/IR knockouts with corepressor co-IP","pmids":["30459283","29400692","29669935","30451856"],"confidence":"High","gaps":["Mechanism of IRS2 mutant gain-of-function in invasion not defined","Direct vs indirect corepressor regulation by IRS2 unresolved"]},{"year":2019,"claim":"Defined fasting-state transcriptional reprogramming of the IRS1:IRS2 ratio, showing glucagon/cAMP→CREB→PGC1A induces IRS2 while suppressing IRS1, with IRS2 required for insulin suppression of gluconeogenesis.","evidence":"Primary hepatocyte gain/loss of PGC1A with CREB inhibition, glucose-production assays, and in vivo overexpression","pmids":["30770439"],"confidence":"High","gaps":["Direct PGC1A coactivator targets on IRS2 promoter not mapped","Integration with other IRS2-inducing TFs unresolved"]},{"year":2022,"claim":"Defined a cancer-stem-cell mechanism whereby IRS2-PI3K inhibits GSK3β to block MYC Thr58 phosphorylation, stabilizing MYC to sustain breast CSC self-renewal.","evidence":"IRS2 knockout cells, GSK3β/MYC phospho-assays, proteasome inhibition, and T58A-MYC rescue in Irs2-/- cells with sphere assays","pmids":["36476848"],"confidence":"High","gaps":["In vivo tumor relevance not established here","Single-lab mechanism"]},{"year":null,"claim":"How the many positive and negative IRS2 inputs—receptor docking, monoubiquitination/membrane recruitment, multisite serine phosphorylation, and competing transcriptional regulators—are quantitatively integrated to set IRS2 abundance and activity in a tissue- and stimulus-specific manner remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No integrated stoichiometric model of IRS2 PTM crosstalk","Structural basis for p110α-PI3K selectivity over IRS1 unknown","Mechanisms determining tissue-specific IRS isoform dominance incompletely defined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,7,16,31,36]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[0,16]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[1,32]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,1,16]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[6,12,14]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[3,37,43]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[35,36,38,44]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[8,29,32]}],"complexes":[],"partners":["INSR","IGF1R","PIK3R1","JAK2","ALK","NEDD4","SOCS3","GRK2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9Y4H2","full_name":"Insulin receptor substrate 2","aliases":[],"length_aa":1338,"mass_kda":137.3,"function":"Signaling adapter protein that participates in the signal transduction from two prominent receptor tyrosine kinases, insulin receptor/INSR and insulin-like growth factor I receptor/IGF1R (PubMed:25879670). Plays therefore an important role in development, growth, glucose homeostasis as well as lipid metabolism (PubMed:24616100). Upon phosphorylation by the insulin receptor, functions as a signaling scaffold that propagates insulin action through binding to SH2 domain-containing proteins including the p85 regulatory subunit of PI3K, NCK1, NCK2, GRB2 or SHP2 (PubMed:15316008, PubMed:19109239). Recruitment of GRB2 leads to the activation of the guanine nucleotide exchange factor SOS1 which in turn triggers the Ras/Raf/MEK/MAPK signaling cascade (By similarity). Activation of the PI3K/AKT pathway is responsible for most of insulin metabolic effects in the cell, and the Ras/Raf/MEK/MAPK is involved in the regulation of gene expression and in cooperation with the PI3K pathway regulates cell growth and differentiation. Acts a positive regulator of the Wnt/beta-catenin signaling pathway through suppression of DVL2 autophagy-mediated degradation leading to cell proliferation (PubMed:24616100). Plays a role in cell cycle progression by promoting a robust spindle assembly checkpoint (SAC) during M-phase (PubMed:32554797). In macrophages, IL4-induced tyrosine phosphorylation of IRS2 leads to the recruitment and activation of phosphoinositide 3-kinase (PI3K) (PubMed:19109239)","subcellular_location":"Cytoplasm, cytosol","url":"https://www.uniprot.org/uniprotkb/Q9Y4H2/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/IRS2","classification":"Not Classified","n_dependent_lines":376,"n_total_lines":1208,"dependency_fraction":0.31125827814569534},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/IRS2","total_profiled":1310},"omim":[{"mim_id":"615239","title":"MICRO RNA 7-1; MIR7-1","url":"https://www.omim.org/entry/615239"},{"mim_id":"612870","title":"PLECKSTRIN HOMOLOGY DOMAIN-INTERACTING PROTEIN; PHIP","url":"https://www.omim.org/entry/612870"},{"mim_id":"612465","title":"TBC1 DOMAIN FAMILY, MEMBER 4; TBC1D4","url":"https://www.omim.org/entry/612465"},{"mim_id":"611546","title":"ELONGATION OF VERY LONG CHAIN FATTY ACIDS-LIKE 6; ELOVL6","url":"https://www.omim.org/entry/611546"},{"mim_id":"609576","title":"ACYL-CoA DEHYDROGENASE, LONG-CHAIN; ACADL","url":"https://www.omim.org/entry/609576"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Cytosol","reliability":"Supported"},{"location":"Aggresome","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"bone marrow","ntpm":48.4}],"url":"https://www.proteinatlas.org/search/IRS2"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"Q9Y4H2","domains":[{"cath_id":"2.30.29.30","chopping":"30-55_70-149","consensus_level":"medium","plddt":89.699,"start":30,"end":149},{"cath_id":"2.30.29.30","chopping":"194-300","consensus_level":"medium","plddt":93.4726,"start":194,"end":300}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9Y4H2","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9Y4H2-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9Y4H2-F1-predicted_aligned_error_v6.png","plddt_mean":47.06},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=IRS2","jax_strain_url":"https://www.jax.org/strain/search?query=IRS2"},"sequence":{"accession":"Q9Y4H2","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9Y4H2.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9Y4H2/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9Y4H2"}},"corpus_meta":[{"pmid":"22869320","id":"PMC_22869320","title":"Regulation of insulin sensitivity by serine/threonine phosphorylation of insulin receptor substrate proteins IRS1 and IRS2.","date":"2012","source":"Diabetologia","url":"https://pubmed.ncbi.nlm.nih.gov/22869320","citation_count":788,"is_preprint":false},{"pmid":"7675087","id":"PMC_7675087","title":"Role of IRS-2 in insulin and cytokine signalling.","date":"1995","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/7675087","citation_count":740,"is_preprint":false},{"pmid":"12228220","id":"PMC_12228220","title":"SOCS-1 and SOCS-3 block insulin signaling by ubiquitin-mediated degradation of IRS1 and IRS2.","date":"2002","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12228220","citation_count":702,"is_preprint":false},{"pmid":"10471495","id":"PMC_10471495","title":"Irs-2 coordinates Igf-1 receptor-mediated beta-cell development and peripheral insulin signalling.","date":"1999","source":"Nature genetics","url":"https://pubmed.ncbi.nlm.nih.gov/10471495","citation_count":454,"is_preprint":false},{"pmid":"17641201","id":"PMC_17641201","title":"Brain IRS2 signaling coordinates life span and nutrient homeostasis.","date":"2007","source":"Science (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/17641201","citation_count":440,"is_preprint":false},{"pmid":"9368067","id":"PMC_9368067","title":"A molecular basis for insulin resistance. Elevated serine/threonine phosphorylation of IRS-1 and IRS-2 inhibits their binding to the juxtamembrane region of the insulin receptor and impairs their ability to undergo insulin-induced tyrosine phosphorylation.","date":"1997","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/9368067","citation_count":428,"is_preprint":false},{"pmid":"10642598","id":"PMC_10642598","title":"Tissue-specific insulin resistance in mice with mutations in the insulin receptor, IRS-1, and IRS-2.","date":"2000","source":"The Journal of clinical investigation","url":"https://pubmed.ncbi.nlm.nih.gov/10642598","citation_count":388,"is_preprint":false},{"pmid":"17200721","id":"PMC_17200721","title":"Glucokinase and IRS-2 are required for compensatory beta cell hyperplasia in response to high-fat diet-induced insulin resistance.","date":"2007","source":"The Journal of clinical 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pathology","url":"https://pubmed.ncbi.nlm.nih.gov/19095950","citation_count":20,"is_preprint":false},{"pmid":"32016973","id":"PMC_32016973","title":"MiRNA-200a-3p suppresses the proliferation, migration and invasion of non-small cell lung cancer through targeting IRS2.","date":"2020","source":"European review for medical and pharmacological sciences","url":"https://pubmed.ncbi.nlm.nih.gov/32016973","citation_count":19,"is_preprint":false},{"pmid":"26755644","id":"PMC_26755644","title":"IRS2 silencing increases apoptosis and potentiates the effects of ruxolitinib in JAK2V617F-positive myeloproliferative neoplasms.","date":"2016","source":"Oncotarget","url":"https://pubmed.ncbi.nlm.nih.gov/26755644","citation_count":19,"is_preprint":false},{"pmid":"26018509","id":"PMC_26018509","title":"miR-106a* inhibits the proliferation of renal carcinoma cells by targeting IRS-2.","date":"2015","source":"Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine","url":"https://pubmed.ncbi.nlm.nih.gov/26018509","citation_count":19,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":52668,"output_tokens":11646,"usd":0.166347,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":23077,"output_tokens":8681,"usd":0.166205,"stage2_stop_reason":"end_turn"},"total_usd":0.332552,"stage1_batch_id":"msgbatch_01DUPACZi7AAWwuZiUjseQF4","stage2_batch_id":"msgbatch_018yt7chE3f48PEFtDwtj6AE","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1995,\n      \"finding\": \"IRS-2 (initially called 4PS) was identified as a second IRS-signaling protein with a conserved amino terminus containing a pleckstrin-homology domain and a phosphotyrosine-binding domain, acting as a scaffold linking insulin, IGF-1, IL-4, IL-9, IL-13, and other cytokine receptors to downstream SH2-domain-containing signaling proteins.\",\n      \"method\": \"Protein purification, molecular cloning, sequence alignment, and expression analysis in multiple cell types including IRS-1-/- mice\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — original purification and cloning paper with sequence-function analysis, foundational study replicated across the field\",\n      \"pmids\": [\"7675087\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"IRS-2, like IRS-1, interacts with the juxtamembrane (JM) domain (amino acids 943–984) of the insulin receptor; elevated serine/threonine phosphorylation of IRS-2 induced by TNFα or chronic hyperinsulinemia impairs this interaction and reduces insulin-induced tyrosine phosphorylation of IRS-2.\",\n      \"method\": \"GST-fusion pulldown with bacterial His6-IR peptides, co-immunoprecipitation in Fao hepatoma cells treated with TNFα or sphingomyelinase, alkaline phosphatase reversal experiments\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro binding assay with defined IR domain peptides plus cell-based functional validation with phosphatase reversal controls\",\n      \"pmids\": [\"9368067\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"IRS-2 is encoded by a single-exon gene on murine chromosome 8; in hematopoietic cells IRS-2 predominates over IRS-1 and undergoes distinct tyrosine phosphorylation patterns during insulin versus IL-4 stimulation, conferring signaling specificity through differential interaction with SH2 domains.\",\n      \"method\": \"Gene isolation, chromosomal mapping, Northern/Western blot tissue expression profiling, interaction with recombinant SH2 domains in 32D cells\",\n      \"journal\": \"Molecular endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct molecular characterization in relevant cell types, single lab, multiple methods\",\n      \"pmids\": [\"9013772\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Leptin activates PI-3 kinase via IRS-2 (but not IRS-1) and JAK-2 in C2C12 myotubes; leptin-stimulated PI-3 kinase activity is detected only in IRS-2 immunoprecipitates and in JAK-2 immunoprecipitates, accompanied by tyrosine phosphorylation of both JAK-2 and IRS-2.\",\n      \"method\": \"PI-3 kinase activity assay in immunoprecipitates using non-cross-reacting IRS-1, IRS-2, JAK-1, and JAK-2 antibodies; tyrosine phosphorylation immunoblotting\",\n      \"journal\": \"Diabetologia\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — immunoprecipitation kinase assay discriminating IRS-1 versus IRS-2, single lab, two orthogonal readouts\",\n      \"pmids\": [\"9389430\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"BDNF stimulates tyrosine phosphorylation of IRS-1 and IRS-2 and their association with PI3-K in cultured cerebral cortical neurons; this signaling is dependent on TrkB kinase activity and is not mediated by direct TrkB–PI3-K association.\",\n      \"method\": \"Co-immunoprecipitation, Western blotting with phosphotyrosine antibodies, kinase inhibitor (K-252a) experiments in primary cortical neurons\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP with functional kinase inhibitor validation, single lab\",\n      \"pmids\": [\"9374521\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Genetic epistasis in mice shows that Irs-2 is the dominant IRS isoform for beta-cell development and compensation for peripheral insulin resistance, and that Igf-1 receptors promote beta-cell development and survival through the Irs-2 signaling pathway.\",\n      \"method\": \"Intercross of Irs1+/-, Irs2+/-, and Igf1r+/- null mice; glucose metabolism and beta-cell morphology phenotyping\",\n      \"journal\": \"Nature genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis with double and triple mutant analysis, replicated in multiple cross combinations\",\n      \"pmids\": [\"10471495\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Tissue-specific epistasis in mice with combined ir/irs-1/irs-2 heterozygous null mutations reveals that IRS-2 plays the dominant role in hepatic insulin signaling, while IRS-1 is predominant in skeletal muscle.\",\n      \"method\": \"Generation and metabolic phenotyping of ir(+/-), ir/irs-1(+/-), ir/irs-2(+/-), and triple heterozygous mice; euglycemic clamp, insulin signaling assays\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — epistasis with multiple genotype combinations and tissue-specific biochemical readouts, independent of previous Withers et al. study\",\n      \"pmids\": [\"10642598\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"IRS-2 is phosphorylated on tyrosine by the alpha6beta4 integrin, which promotes IRS-2 association with PI3K; the beta4 subunit tyrosine Y1494 is specifically required for IRS-2 phosphorylation and PI3K activation, and is essential for alpha6beta4-dependent carcinoma invasion.\",\n      \"method\": \"Co-immunoprecipitation of IRS-2 with PI3K, site-directed mutagenesis of beta4 Y1494, cell invasion assays\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — mutagenesis of defined tyrosine residue combined with co-IP and functional invasion assay, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"11438664\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"SOCS1 and SOCS3 bind both IRS-1 and IRS-2 and promote their ubiquitination and proteasomal degradation via the elongin BC ubiquitin-ligase complex; mutations in the SOCS box of SOCS1 that abrogate elongin BC interaction eliminate IRS degradation without affecting SOCS1–IRS binding, demonstrating that the SOCS box recruits the ubiquitin ligase.\",\n      \"method\": \"Co-immunoprecipitation of endogenous and recombinant IRS proteins with SOCS proteins, ubiquitination assays, SOCS box point mutants, adenoviral hepatic overexpression in mice\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — binding, ubiquitination, mutagenesis, and in vivo adenoviral experiments all in one study with clear mechanistic resolution\",\n      \"pmids\": [\"12228220\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Basal serine/threonine phosphorylation of IRS-2 plays a positive role in subsequent insulin receptor-mediated tyrosine phosphorylation, whereas hyperphosphorylation by GSK3β decreases tyrosine phosphorylation; dephosphorylation of basal sites also increased IGF-1 receptor-mediated IRS-2 phosphorylation, showing divergent regulation compared to the insulin receptor.\",\n      \"method\": \"In vitro insulin receptor kinase assay on recombinant FLAG-IRS-2 after alkaline phosphatase dephosphorylation or GSK3β hyperphosphorylation; confirmed in endogenous IRS-2 from 3T3-L1 adipocytes\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstituted kinase assay with dephosphorylation/hyperphosphorylation controls, validated in endogenous IRS-2\",\n      \"pmids\": [\"12033942\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Pdx1 expression is reduced in islets of Irs2-/- mice before diabetes onset; transgenic restoration of Pdx1 rescues beta-cell mass and prevents diabetes in Irs2-/- mice, placing Pdx1 downstream of Irs2 signaling in beta-cell survival.\",\n      \"method\": \"Genetic rescue experiment: Pdx1 transgene on Irs2-/- background; beta-cell mass quantification, glucose tolerance, survival analysis\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis with gain-of-function rescue plus loss-of-function acceleration, clear pathway placement\",\n      \"pmids\": [\"11994408\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"PTP1B dephosphorylates and inactivates the insulin receptor, thereby limiting IRS-2-mediated signaling; deletion of Ptp1b in Irs2-/- mice restores peripheral insulin sensitivity and beta-cell area, demonstrating that PTP1B acts upstream of IRS-2 by controlling insulin receptor phosphorylation state.\",\n      \"method\": \"Double-knockout mouse genetics (Irs2-/-::Ptp1b-/-), metabolic phenotyping, insulin signaling biochemistry\",\n      \"journal\": \"Diabetes\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis with double-mutant rescue, clear pathway placement upstream of IRS-2\",\n      \"pmids\": [\"14693698\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Hepatic IRS-2 knockdown via adenoviral shRNA upregulates lipogenic enzymes SREBP-1c and fatty acid synthase and causes hepatic lipid accumulation, while IRS-1 knockdown upregulates gluconeogenic enzymes; combined IRS-1/IRS-2 knockdown abolishes Akt→FoxO1 signaling and causes systemic insulin resistance.\",\n      \"method\": \"Adenoviral shRNA-mediated knockdown of IRS-1, IRS-2, or both in mouse liver; gene expression, metabolic phenotyping, Akt/FoxO1 phosphorylation\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo loss-of-function with defined biochemical and phenotypic readouts, dual-knockdown epistasis\",\n      \"pmids\": [\"15711641\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Exendin-4 increases cAMP in beta cells, which upregulates Irs2 expression and stimulates Akt phosphorylation; Irs2 is required for Ex4-mediated long-term beta-cell growth and survival but not short-term insulin secretion effects, demonstrating that GLP-1 receptor agonists act through the Irs2 branch to expand beta-cell mass.\",\n      \"method\": \"cAMP measurement in human islets and Min6 cells, Akt phosphorylation, Ex4 treatment of Irs2-/- mice, beta-cell mass quantification\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — mechanistic signaling (cAMP→IRS2→Akt) validated by in vivo loss-of-function in Irs2-/- mice\",\n      \"pmids\": [\"16272563\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Liver-specific deletion of Irs2 combined with whole-body Irs1 knockout abolishes hepatic Akt→FoxO1 signaling and causes hyperglycemia, while single-tissue knockouts cause insulin resistance without diabetes; Irs1 or Irs2 individually regulate hundreds of hepatic genes including Pck1, G6pc, and Igfbp1.\",\n      \"method\": \"Cre-lox conditional liver-specific Irs2 deletion on Irs1-/- background; insulin signaling, hepatic gene expression microarray, metabolic phenotyping\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional genetics with epistasis, gene expression profiling, and defined biochemical signaling readouts\",\n      \"pmids\": [\"16374520\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Viral-mediated downregulation of the IRS2-Akt signaling pathway in the VTA mediates chronic morphine-induced decrease in dopamine neuron cell size and diminishes morphine reward as measured by conditioned place preference.\",\n      \"method\": \"Viral-mediated gene transfer of IRS2 dominant negative and constitutively active constructs into rat VTA; neuron size measurement, conditioned place preference behavioral assay\",\n      \"journal\": \"Nature neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — viral gain- and loss-of-function in specific brain region with two orthogonal functional readouts (morphology and behavior)\",\n      \"pmids\": [\"17143271\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"FoxO1 and IRS-2 form a reciprocal stability circuit: IRS-2 efficiently activates p110α-PI3K→Akt→FoxO1 phosphorylation/degradation, while prolonged insulin stimulation leads to rapamycin-sensitive IRS-2 degradation that allows FoxO1 to re-accumulate; IRS-2 activates p110α-PI3K more efficiently than IRS-1 does.\",\n      \"method\": \"Wild-type, Irs1-/-, and Irs2-/- mouse embryo fibroblasts; PI3K co-immunoprecipitation, Akt and FoxO1 phosphorylation, rapamycin treatment, immunofluorescence\",\n      \"journal\": \"Molecular endocrinology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — three genetically defined cell lines with pharmacological intervention and multiple biochemical readouts\",\n      \"pmids\": [\"16916938\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"IRS-2 binds beta-catenin in vitro and in vivo; transgenic overexpression of IRS-2 in the mammary gland causes progressive hyperplasia, tumorigenesis, and metastasis with extensive squamous differentiation consistent with beta-catenin pathway activation.\",\n      \"method\": \"Co-immunoprecipitation of IRS-2 with beta-catenin in vitro and in vivo, transgenic mouse mammary tumor model with histopathology\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP plus in vivo transgenic phenotype, single lab\",\n      \"pmids\": [\"17030631\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"TFE3, a bHLH transcription factor, directly transactivates the IRS2 promoter via an E-box element; adenoviral TFE3 expression in hepatocytes strongly increases IRS-2 and Akt expression and downstream insulin signaling, reducing blood glucose in multiple diabetic mouse models.\",\n      \"method\": \"Promoter luciferase reporter assays, adenoviral TFE3 overexpression in hepatocytes and in vivo, Western blotting for IRS-2/Akt phosphorylation\",\n      \"journal\": \"Nature medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — promoter reporter assay establishing direct transcriptional target, confirmed by in vivo adenoviral expression with functional metabolic readouts\",\n      \"pmids\": [\"16327801\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"ATF3, a stress-inducible transcription factor, binds to the IRS2 promoter in vivo and represses IRS2 gene transcription, contributing to beta-cell apoptosis; IRS2 overexpression rescues beta-cells from ATF3-induced apoptosis.\",\n      \"method\": \"Chromatin immunoprecipitation (ChIP) assay, Pol II occupancy assay, gain/loss-of-function ATF3 with IRS2 expression measurement, ATF3 transgenic and IRS2 transgenic mice with RIP-driven transgenes\",\n      \"journal\": \"Diabetes\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — ChIP demonstrating direct promoter binding, Pol II occupancy confirming transcriptional repression, genetic rescue in vivo\",\n      \"pmids\": [\"18057093\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Brain-specific Irs2 knockout mice develop obesity and glucose intolerance, but display greater physical activity and stable hypothalamic SOD2 concentrations during meals, extending lifespan by up to 18%, establishing that Irs2 signaling in the brain coordinates energy balance, oxidative stress responses, and longevity.\",\n      \"method\": \"Brain-specific Cre-lox Irs2 knockout mice; metabolic phenotyping, activity monitoring, SOD2 immunostaining, lifespan analysis\",\n      \"journal\": \"Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — tissue-specific genetic ablation with multiple orthogonal phenotypic readouts including lifespan\",\n      \"pmids\": [\"17641201\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Aldosterone promotes degradation of IRS-2 (and IRS-1) through a glucocorticoid receptor-mediated, reactive oxygen species-dependent pathway involving activation of IKKβ and mTORC1; this degradation reduces insulin-induced Akt phosphorylation and glucose uptake in 3T3-L1 adipocytes.\",\n      \"method\": \"Time- and dose-response IRS protein immunoblotting in 3T3-L1 adipocytes; pharmacological inhibitors of mineralocorticoid receptor, glucocorticoid receptor, NAC (antioxidant), rapamycin, BMS345541, and proteasome inhibitor lactacystin; sucrose-gradient fractionation\",\n      \"journal\": \"Endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pharmacological dissection with multiple inhibitors identifying pathway, single lab\",\n      \"pmids\": [\"19095745\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Deletion of PTP1B in IRS2-/- mice restores hepatic IRS1-mediated PI3K/Akt/FoxO1 signaling; in IRS2-/- livers, PTP1B expression and its association with the insulin receptor are increased, and resveratrol treatment reduces PTP1B activity and restores IRS1-mediated signaling.\",\n      \"method\": \"Double-knockout mouse genetics (IRS2-/-/PTP1B-/-), co-immunoprecipitation of PTP1B with IR, hepatic insulin signaling biochemistry, resveratrol pharmacological intervention\",\n      \"journal\": \"Diabetes\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis with double knockout plus pharmacological validation, co-IP of PTP1B–IR interaction\",\n      \"pmids\": [\"20028942\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Muscle-specific combined deletion of Irs1 and Irs2 severely reduces skeletal muscle growth, abolishes Akt→mTOR signaling, increases Foxo-dependent atrogene expression and amino acid release, shifts glucose utilization from oxidation to lactate, and elevates AMPK→ACC phosphorylation and fatty acid oxidation.\",\n      \"method\": \"MCK-Cre driven double muscle-specific Irs1/Irs2 knockout; muscle mass quantification, insulin signaling biochemistry, glucose uptake, metabolic flux, AMPK/ACC phosphorylation\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — tissue-specific double KO with comprehensive biochemical and metabolic characterization\",\n      \"pmids\": [\"21135130\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"IRS-2 is phosphorylated during induction of LTP in hippocampus; IRS-2-deficient mice fail to activate postsynaptic NMDA receptors or Fyn, AKT, and MAPK in response to tetanic stimulation, demonstrating IRS-2 as a required component of LTP signaling machinery.\",\n      \"method\": \"Hippocampal slice electrophysiology (LTP recording), Western blotting for IRS-2 phosphorylation during LTP, biochemical analysis of Fyn/AKT/MAPK in Irs2-/- slices\",\n      \"journal\": \"Cerebral cortex\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — loss-of-function electrophysiology combined with direct detection of IRS-2 phosphorylation during LTP induction\",\n      \"pmids\": [\"21955917\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Increasing Irs2 levels in R6/2 HD mouse brains reduces life span and increases neuronal oxidative stress and mitochondrial dysfunction; conversely, reducing Irs2 levels improves motor performance and extends lifespan, associated with increased nuclear FoxO1 and upregulation of FoxO1-dependent autophagy and antioxidant genes.\",\n      \"method\": \"Genetic modulation of Irs2 levels in R6/2 HD model mice; behavioral testing, mitochondrial function assays, autophagosome counting, oxidative stress markers, FoxO1 nuclear localization\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — bidirectional genetic manipulation (gain and loss of function) with multiple orthogonal cellular readouts\",\n      \"pmids\": [\"21926467\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Irs2 signaling in leptin receptor-expressing (LepRb) neurons suppresses FoxO1 to control energy balance; deletion of FoxO1 in LepRb neurons normalizes obesity, glucose homeostasis, and arcuate gene expression caused by Irs2 ablation in those neurons, placing FoxO1 downstream of IRS2 in energy balance regulation.\",\n      \"method\": \"Lepr-Cre × Irs2-flox conditional knockout; FoxO1 conditional deletion epistasis experiment; metabolic phenotyping, insulin-stimulated FoxO1 nuclear exclusion assay\",\n      \"journal\": \"Cell metabolism\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — cell-type-specific genetic ablation with epistatic FoxO1 rescue, defining pathway order\",\n      \"pmids\": [\"22560222\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Angiotensin II and PKCβ2 phosphorylate specific serine residues on IRS-2 (Ser303, Ser343, Ser675) in endothelial cells, inhibiting insulin-induced tyrosine phosphorylation (Tyr653, Tyr671, Tyr911) and downstream Akt/eNOS activation; AngII specifically targets Ser303 to inhibit p-Tyr911 and p-Akt/eNOS.\",\n      \"method\": \"Site-directed mutagenesis of IRS-2 serine residues (S303A, S675A), PKCβ2 overexpression and dominant-negative, losartan receptor antagonist, phospho-specific antibodies; confirmed in vessels of insulin-resistant Zucker fatty rats\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — mutagenesis of individual phosphorylation sites plus pharmacological inhibitors plus in vivo validation in disease model\",\n      \"pmids\": [\"23775122\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Heart-specific double knockout of IRS1 and IRS2 causes reduced ventricular mass, cardiac apoptosis, fibrosis, and heart failure with diminished Akt→FoxO1 signaling and impaired cardiac metabolic gene expression; chronic insulin exposure reduces cardiac IRS1/IRS2 via p38α MAPK activation.\",\n      \"method\": \"Heart-specific Cre-lox IRS1/IRS2 double KO; echocardiography, cardiac apoptosis/fibrosis assays, p38 activation in neonatal rat ventricular cardiomyocytes with chronic insulin\",\n      \"journal\": \"Diabetes\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — tissue-specific double KO with multiple cardiac phenotype readouts plus cell-based mechanism identifying p38α as the writer of IRS1/2 loss\",\n      \"pmids\": [\"24159000\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Phosphorylation of IRS-2 at Ser1137/1138 by PKA (induced by cAMP/forskolin) promotes binding of 14-3-3 proteins and protects IRS-2 from proteasomal degradation, increasing IRS-2 protein stability.\",\n      \"method\": \"GST-14-3-3 pulldown assays with deletion constructs, mass spectrometry phosphorylation site identification, Ser1137/1138 alanine mutants, cycloheximide chase stability assay, 14-3-3 antagonist treatment in HEK293 cells and primary hepatocytes\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — MS-identified sites confirmed by mutagenesis, stability assay with cycloheximide, pharmacological and genetic validation\",\n      \"pmids\": [\"23615913\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"IRS-2 in endothelial cells is required for normal islet blood flow and glucose-induced insulin secretion; endothelial cell-specific Irs2 knockout impairs islet perfusion, and restoration of blood flow with enalapril rescues insulin secretion.\",\n      \"method\": \"EC-specific Irs2 knockout (ETIrs2KO) mice; islet perfusion experiments, enalapril pharmacological rescue, glucose and arginine stimulation tests\",\n      \"journal\": \"Diabetes\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — cell-type-specific KO with mechanistic pharmacological rescue identifying islet blood flow as the mediating mechanism\",\n      \"pmids\": [\"25277391\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Insulin stimulates IRS2-dependent recruitment of GRK2 to the insulin receptor, which then phosphorylates β2AR at Ser355/356, promoting β2AR internalization and suppression of βAR-induced cAMP-PKA signaling and contractile response in cardiomyocytes; IRS2 deletion disrupts the IR–GRK2 complex.\",\n      \"method\": \"Co-immunoprecipitation of IRS2 with IR and GRK2; β2AR phosphorylation and internalization assays; IRS2 knockout cardiomyocytes; cAMP and contractility measurements\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP plus loss-of-function with specific phosphorylation and functional readouts, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"25460042\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Nedd4 E3 ubiquitin ligase monoubiquitinates IRS-2, promoting its association with the ubiquitin-binding protein Epsin1 and recruitment of IRS-2 to the plasma membrane; this enhances IGF-I receptor-induced IRS-2 tyrosine phosphorylation, IGF-I signaling, and cell proliferation, confirmed by in vivo zebrafish growth experiments.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assays, Epsin1 binding assays, membrane fractionation, siRNA knockdown, zebrafish IRS-2 knockdown rescue with Nedd4\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — ubiquitination assay identifying Nedd4 as the E3 ligase, Epsin1 interaction, membrane recruitment mechanism, and in vivo zebrafish validation\",\n      \"pmids\": [\"25879670\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"IRS2 deficiency in podocytes causes insulin resistance through upregulation of PTEN; suppressing PTEN in Irs2-/- podocytes rescues AKT signaling, GLUT4-mediated glucose uptake, F-actin remodeling, and cell motility, placing PTEN downstream of IRS2 in podocyte insulin signaling.\",\n      \"method\": \"Conditionally immortalized Irs2-/- podocytes; AKT phosphorylation, GLUT4 glucose uptake assay, F-actin staining, Transwell motility assay, siRNA PTEN knockdown rescue\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function with PTEN rescue epistasis, multiple orthogonal cellular assays, single lab\",\n      \"pmids\": [\"26384875\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Glucose-induced beta-cell proliferation requires IRS2 and mTOR but not the insulin receptor; IRS2 or mTOR loss reduces cyclin D2 expression, and restoring cyclin D2 rescues the proliferation defect, placing IRS2→mTOR→cyclin D2 as the pathway for glucose-driven beta-cell replication.\",\n      \"method\": \"IRS2 knockout mice with in vivo hyperglycemia model and ex vivo islet culture; insulin receptor knockout; mTOR/ERK inhibitors; cyclin D2 adenoviral rescue; confirmed in human islets\",\n      \"journal\": \"Diabetes\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic and pharmacological pathway dissection with rescue epistasis, validated in both mouse and human islets\",\n      \"pmids\": [\"26740601\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"YAP/TAZ activation in the liver upregulates IRS2 expression, amplifying AKT signaling; YAP/TAZ ablation or Hippo pathway activation rescues NAFLD and liver cancer in PTEN/SAV1 double-knockout mice, and AAV-Cas9 knockout of IRS2 successfully represses liver tumorigenesis in this model.\",\n      \"method\": \"PTEN/SAV1 double liver-specific knockout mice; YAP/TAZ/IRS2 expression analysis; AAV-Cas9 IRS2 knockout; AKT inhibitor MK-2206 treatment; correlation of YAP/TAZ and IRS2 in human HCC\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo genetic ablation (AAV-Cas9 IRS2 KO) with tumor phenotype, multiple genetic tools, and human HCC correlation\",\n      \"pmids\": [\"29400692\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"IRS2 is recruited to and tyrosine-phosphorylated by oncogenic ALK in neuroblastoma cells; ALK TKI treatment decreases IRS2 recruitment to ALK and IRS2 tyrosine phosphorylation; siRNA depletion of ALK or IRS2 reduces AKT and FoxO3 phosphorylation and decreases viability of ALK-driven neuroblastoma cells.\",\n      \"method\": \"Quantitative mass spectrometry-based proximal proteomics (IPP), co-immunoprecipitation, phosphotyrosine interactome, siRNA knockdown of IRS2, cell viability assays, ALK TKI treatment\",\n      \"journal\": \"Science signaling\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — MS-based interactome combined with co-IP, loss-of-function, and signaling validation with multiple orthogonal methods\",\n      \"pmids\": [\"30459283\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Downregulation of macrophage IRS2 expression by hyperinsulinemia via insulin receptor impairs IL-4-induced M2a-subtype macrophage activation; mechanistically, loss of IRS2 stabilizes the FoxO1/HDAC3/NCoR1 corepressor complex; myeloid-specific IR knockout preserves IRS2 and IL-4/IRS2/Akt signaling and reduces insulin resistance.\",\n      \"method\": \"Myeloid cell-specific Irs2-deficient mice and myeloid-specific IR-deficient mice; macrophage polarization assays, co-immunoprecipitation of FoxO1/HDAC3/NCoR1 complex, AKT phosphorylation, high-fat diet metabolic phenotyping\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — cell-type-specific KO of both IRS2 and IR with mechanistic co-repressor complex identified by Co-IP\",\n      \"pmids\": [\"30451856\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"IRS2 mutations identified in pleomorphic invasive lobular carcinoma enhance breast cancer cell invasion, defining IRS2 as functionally important in the aggressive nature of PILC through the IR/IGF1R/IRS2 signaling pathway.\",\n      \"method\": \"Targeted sequencing, functional invasion assays with PILC-derived IRS2 mutants in breast cancer cells\",\n      \"journal\": \"JCI insight\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional mutant characterization in invasion assays, single lab\",\n      \"pmids\": [\"29669935\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"PGC1A, induced by glucagon/cAMP signaling through CREB, drives IRS2 expression while simultaneously reducing IRS1 expression in hepatocytes, thereby shifting the IRS1:IRS2 ratio during fasting; PGC1A-induced IRS2 expression is required for suppression of hepatocyte gluconeogenesis by insulin.\",\n      \"method\": \"Primary hepatocyte gain- and loss-of-function of PGC1A; CREB inhibitor experiments; ex vivo glucose production assays; in vivo PGC1A hepatic overexpression\",\n      \"journal\": \"Proceedings of the National Academy of Sciences\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — gain and loss of function in primary hepatocytes with CREB mechanistic dissection and in vivo validation\",\n      \"pmids\": [\"30770439\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"MAP4K4 is a key mediator of TNF-α-induced decrease of IRS-2 protein levels in primary beta cells (without change in mRNA); MAP4K4 siRNA knockdown protects against TNF-α-induced IRS-2 protein reduction and preserves glucose-stimulated insulin secretion and Akt phosphorylation.\",\n      \"method\": \"siRNA knockdown of MAP4K4 in human and rat primary FACS-sorted beta cells; IRS-2 protein and mRNA measurement; Akt/AS160 phosphorylation; glucose-stimulated insulin secretion\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA loss-of-function in primary cells with protein vs. mRNA discrimination, single lab\",\n      \"pmids\": [\"19690174\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"JNK3 maintains IRS-2 protein expression in insulin-secreting cells and is required for Akt2 (but not Akt1) activation by insulin; JNK3 mediates its effects at the transcriptional level through maintenance of FoxO3A activity that controls IRS2 expression, while JNK1/2 have opposing pro-apoptotic effects.\",\n      \"method\": \"siRNA silencing of individual JNK isoforms in beta cell lines; IRS-2 protein/mRNA measurement, Akt1/Akt2 and GSK3β phosphorylation, FoxO3A activity assays\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — isoform-specific siRNA knockdown discriminating JNK1/2/3 effects on IRS-2 and downstream signaling, single lab\",\n      \"pmids\": [\"22563476\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"HIF-2α activation in liver directly and indirectly induces IRS-2 expression; liver-specific constitutive HIF-2α is sufficient to augment hepatic insulin signaling through IRS-2 induction, and liver Irs2 is both necessary and sufficient to mediate HIF-2α and VEGF inhibition effects on glucose tolerance.\",\n      \"method\": \"Liver-specific constitutive HIF-2α activation, IRS-2 expression analysis, Irs2-/- rescue experiments, VEGF inhibitor treatment in diabetic db/db mice\",\n      \"journal\": \"Nature medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic gain-of-function and IRS-2 necessity/sufficiency established through multiple genetic models and pharmacological intervention\",\n      \"pmids\": [\"24037094\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"JAK2V617F binds IRS2 in JAK2-mutant HEL cells; IRS2 silencing in JAK2V617F cells decreases STAT5 phosphorylation, reduces cell viability, and increases apoptosis, effects enhanced when combined with ruxolitinib; this interaction is absent in JAK2WT cells.\",\n      \"method\": \"Co-immunoprecipitation of JAK2 with IRS2, siRNA IRS2 knockdown, cell viability and apoptosis assays, STAT5 phosphorylation; validated with pharmacological IRS1/2 inhibition in primary MPN patient samples\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP plus loss-of-function in cell lines and primary patient samples, single lab\",\n      \"pmids\": [\"26755644\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"IRS2-PI3K signaling enhances MYC expression by inhibiting GSK3β activity and reducing MYC phosphorylation at Thr58, thereby preventing proteasomal degradation of MYC and sustaining active pS62-MYC to support breast cancer stem cell self-renewal; a T58A-MYC mutant rescues CSC function in Irs2-/- cells.\",\n      \"method\": \"IRS2 knockout cells, GSK3β activity assays, MYC T58 phosphorylation immunoblotting, proteasome inhibitor experiments, T58A-MYC rescue construct in Irs2-/- cells, CSC sphere assay\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — mutagenesis-based epistasis (T58A-MYC rescue in Irs2-/- background) with biochemical mechanism defined, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"36476848\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Chronic central leptin infusion decreases the association between the insulin receptor β chain and IRS2 in the hypothalamus, increases SOCS3 association with the insulin receptor, and augments JAK2-IRS2 association, thereby blunting insulin's ability to activate the IRS2-mediated PI3K/Akt pathway.\",\n      \"method\": \"Co-immunoprecipitation of IRβ with IRS2 and SOCS3, co-IP of JAK2 with IRS2 in rat hypothalamus, chronic icv leptin infusion followed by acute icv insulin injection, Akt phosphorylation biochemistry\",\n      \"journal\": \"Journal of neurochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP in specific brain region with pharmacological (chronic leptin) intervention, single lab\",\n      \"pmids\": [\"21255014\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"IRS2 is a cytoplasmic scaffolding adaptor with PH and PTB domains that is tyrosine-phosphorylated by the insulin receptor (via its juxtamembrane domain), IGF-1R, ALK, JAK2V617F, TrkA, and the α6β4 integrin to recruit SH2-domain proteins (PI3K p85, Grb2, SHP-2); its activity is positively regulated by Nedd4-mediated monoubiquitination (promoting membrane recruitment via Epsin1) and basal serine phosphorylation, and negatively regulated by SOCS1/3-mediated ubiquitin-proteasomal degradation, serine phosphorylation by PKCβ/AngII (Ser303, Ser675), and MAP4K4; cAMP/PKA-mediated phosphorylation of Ser1137/1138 stabilizes IRS2 via 14-3-3 binding; IRS2 preferentially activates p110α-PI3K→Akt2→FoxO1 to control hepatic glucose/lipid metabolism, beta-cell mass, neuronal function (LTP), dopamine neuron morphology, and energy balance, with transcriptional regulation of IRS2 itself controlled by TFE3, HIF-2α, PGC1A/CREB, CaMKIV/CREB, and ATF3.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"IRS2 is a cytoplasmic scaffolding adaptor that couples insulin, IGF-1, and cytokine receptors to downstream PI3K/Akt signaling, controlling whole-body glucose and lipid metabolism, beta-cell mass, and neuronal function [#0, #5]. Identified originally as the second IRS protein (4PS), it contains an N-terminal pleckstrin-homology and phosphotyrosine-binding domain and links activated receptors to SH2-domain effectors including PI3K [#0]; it docks on the juxtamembrane domain of the insulin receptor (residues 943–984), an interaction disrupted by inflammatory serine phosphorylation [#1]. Beyond the insulin receptor, IRS2 is tyrosine-phosphorylated by diverse kinases—the α6β4 integrin (via β4 Y1494) in carcinoma invasion [#7], TrkB downstream of BDNF and JAK2 downstream of leptin in neural contexts [#4, #3], oncogenic ALK in neuroblastoma [#36], and JAK2V617F in myeloproliferative cells [#43]—channeling each into PI3K recruitment. Genetic epistasis establishes IRS2 as the dominant IRS isoform in liver and in beta-cell development and compensation, where IGF-1 receptor signaling acts through IRS2 [#5, #6]; it preferentially activates p110α-PI3K→Akt→FoxO1 more efficiently than IRS1, forming a reciprocal stability circuit with FoxO1 [#16]. The IRS2→Akt→FoxO1 axis drives hepatic glucose/lipid control [#12, #14], beta-cell survival and proliferation via Pdx1 and mTOR→cyclin D2 [#10, #34], energy balance and longevity through hypothalamic LepRb neurons [#20, #26], hippocampal LTP [#24], and dopamine-neuron morphology and reward [#15]. IRS2 abundance is tightly controlled: positively by Nedd4-mediated monoubiquitination promoting Epsin1-dependent membrane recruitment [#32], by basal serine phosphorylation [#9], and by PKA phosphorylation of Ser1137/1138 that recruits 14-3-3 to block degradation [#29]; and negatively by SOCS1/3-elongin BC-mediated proteasomal degradation [#8], PKCβ/AngII serine phosphorylation (Ser303/Ser675) [#27], MAP4K4 [#40], and aldosterone-driven mTORC1/IKKβ pathways [#21]. Its transcription is induced by TFE3, HIF-2α, PGC1A/CREB, and YAP/TAZ and repressed by ATF3, providing nutrient- and stress-responsive control of IRS2 levels [#18, #42, #39, #35, #19]. Gain-of-function and mutational studies implicate IRS2 in mammary, breast, and liver tumorigenesis through β-catenin, MYC stabilization, and amplified Akt signaling [#17, #44, #38, #35].\",\n  \"teleology\": [\n    {\n      \"year\": 1995,\n      \"claim\": \"Established that a second IRS protein exists, defining IRS2 as a multi-receptor scaffold that links insulin, IGF-1, and cytokine receptors to SH2-domain effectors and explaining residual signaling in IRS1-deficient cells.\",\n      \"evidence\": \"Protein purification, cloning, and sequence-function analysis across cell types including IRS1-/- mice\",\n      \"pmids\": [\"7675087\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve receptor-specific phosphosite usage\", \"No structural model of PH/PTB domain engagement\"]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Defined the physical receptor-docking interface and showed it is regulated, mapping IRS2 binding to the insulin receptor juxtamembrane domain and demonstrating that inflammatory serine phosphorylation disrupts coupling.\",\n      \"evidence\": \"GST-fusion pulldown with IR peptides, co-IP in Fao hepatoma cells with TNFα/sphingomyelinase, phosphatase reversal\",\n      \"pmids\": [\"9368067\", \"9013772\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific serine sites mediating disruption not mapped here\", \"Hematopoietic specificity mechanism not fully defined\"]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Showed IRS2 mediates signaling for non-insulin receptors, with leptin/JAK2 and BDNF/TrkB driving IRS2-PI3K activation in muscle and neurons, broadening its receptor repertoire.\",\n      \"evidence\": \"IP-based PI3K activity assays and phosphotyrosine immunoblotting in C2C12 myotubes and primary cortical neurons with kinase inhibitors\",\n      \"pmids\": [\"9389430\", \"9374521\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct vs indirect kinase-IRS2 contact not resolved\", \"Physiological relevance in vivo not tested at this stage\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Placed IRS2 at the center of beta-cell biology, establishing through genetic epistasis that IRS2 is dominant for beta-cell development and peripheral compensation and that IGF-1R acts through IRS2.\",\n      \"evidence\": \"Intercrosses of Irs1, Irs2, and Igf1r null mice with metabolic and beta-cell phenotyping\",\n      \"pmids\": [\"10471495\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream effectors in beta cells not yet identified\", \"Tissue-resolved contributions not separated\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Resolved tissue division of labor among IRS isoforms, demonstrating IRS2 dominance in liver versus IRS1 in skeletal muscle.\",\n      \"evidence\": \"Combined heterozygous null mouse genetics with euglycemic clamp and signaling assays\",\n      \"pmids\": [\"10642598\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of tissue specificity unexplained\", \"Did not address transcriptional control of the ratio\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Defined the dominant degradation and stability machinery controlling IRS2 abundance: SOCS1/3 recruit the elongin BC ubiquitin ligase for proteasomal turnover, while basal serine phosphorylation positively primes IR-mediated tyrosine phosphorylation.\",\n      \"evidence\": \"Co-IP, ubiquitination assays, SOCS-box point mutants, in vitro IR kinase assays with phosphatase/GSK3β treatments, adenoviral hepatic overexpression\",\n      \"pmids\": [\"12228220\", \"12033942\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Kinases setting basal positive sites not all defined\", \"Relative quantitative contribution of each pathway in vivo unclear\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Identified the transcriptional output that sustains beta-cell survival, placing Pdx1 downstream of IRS2 such that Pdx1 restoration rescues beta-cell mass and prevents diabetes.\",\n      \"evidence\": \"Pdx1 transgene rescue on Irs2-/- background with beta-cell mass and survival analysis\",\n      \"pmids\": [\"11994408\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanistic link from Akt/FoxO1 to Pdx1 not fully mapped\", \"Did not address proliferation vs survival contributions\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Positioned PTP1B upstream of IRS2 as a negative regulator acting at the receptor level, with Ptp1b deletion rescuing insulin sensitivity and beta-cell area in Irs2-/- mice.\",\n      \"evidence\": \"Irs2-/-::Ptp1b-/- double-knockout genetics with metabolic phenotyping\",\n      \"pmids\": [\"14693698\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether PTP1B acts directly on IRS2 not established\", \"Compensatory IRS1 contribution explored only later\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Defined IRS2's non-redundant hepatic role in lipid versus glucose control and showed cAMP/GLP-1 signaling expands beta-cell mass through IRS2.\",\n      \"evidence\": \"Adenoviral hepatic shRNA knockdown with gene expression and metabolic readouts; cAMP/Akt analysis and Ex4 treatment of Irs2-/- mice\",\n      \"pmids\": [\"15711641\", \"16272563\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism partitioning IRS1 vs IRS2 to distinct gene programs unresolved\", \"Direct cAMP-to-IRS2 transcriptional link not defined here\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Established the IRS2-FoxO1 reciprocal stability circuit and IRS2's preferential coupling to p110α-PI3K, providing the core signaling logic for downstream metabolic and survival outputs.\",\n      \"evidence\": \"Wild-type, Irs1-/-, Irs2-/- MEFs with PI3K co-IP, Akt/FoxO1 phosphorylation, and rapamycin treatment\",\n      \"pmids\": [\"16916938\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of p110α preference not defined\", \"In vivo relevance of rapamycin-sensitive degradation not tested here\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Extended IRS2 function to the nervous system, showing VTA IRS2-Akt signaling controls dopamine-neuron size and morphine reward behavior.\",\n      \"evidence\": \"Viral dominant-negative and constitutively active IRS2 in rat VTA with morphology and conditioned place preference assays\",\n      \"pmids\": [\"17143271\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Receptor driving VTA IRS2 phosphorylation not identified\", \"Molecular link to neuronal size not detailed\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Identified bidirectional transcriptional control of IRS2 by TFE3 (activating) and ATF3 (repressing), connecting IRS2 levels to metabolic improvement and stress-induced beta-cell apoptosis.\",\n      \"evidence\": \"Promoter luciferase and ChIP/Pol II occupancy assays with adenoviral and transgenic in vivo validation\",\n      \"pmids\": [\"16327801\", \"18057093\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Combinatorial promoter logic with other factors unresolved\", \"Upstream signals controlling these TFs not fully defined\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Linked IRS2 to oncogenic signaling beyond metabolism, showing IRS2 binds β-catenin and that mammary overexpression drives hyperplasia, tumorigenesis, and metastasis.\",\n      \"evidence\": \"Reciprocal co-IP of IRS2 with β-catenin and transgenic mammary tumor model with histopathology\",\n      \"pmids\": [\"17030631\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct vs indirect β-catenin binding not structurally defined\", \"Single-lab transgenic model not independently replicated in timeline\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Expanded the negative-regulatory network, defining an aldosterone/glucocorticoid-receptor, ROS-dependent IKKβ/mTORC1 pathway that degrades IRS2 to impair insulin action.\",\n      \"evidence\": \"Pharmacological inhibitor dissection in 3T3-L1 adipocytes with sucrose-gradient fractionation\",\n      \"pmids\": [\"19095745\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct kinase writing degradation-promoting marks not identified\", \"Single-lab pharmacological inference\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Identified MAP4K4 as the mediator of TNF-α-induced post-transcriptional loss of IRS2 protein in beta cells, distinguishing protein-level from mRNA-level control.\",\n      \"evidence\": \"siRNA knockdown in primary FACS-sorted beta cells with protein/mRNA discrimination and insulin secretion readouts\",\n      \"pmids\": [\"19690174\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct MAP4K4 substrate sites on IRS2 not mapped\", \"Single-lab finding\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Refined the PTP1B-IRS2 epistasis to a hepatic mechanism, showing PTP1B loss restores IRS1-mediated PI3K/Akt/FoxO1 signaling in Irs2-/- liver and that resveratrol mimics this.\",\n      \"evidence\": \"Irs2-/-/Ptp1b-/- genetics, PTP1B-IR co-IP, and resveratrol pharmacology\",\n      \"pmids\": [\"20028942\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of increased PTP1B in Irs2-/- liver unclear\", \"Resveratrol target specificity not fully resolved\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Demonstrated IRS proteins are required for skeletal muscle growth and metabolic flux, with combined Irs1/Irs2 loss abolishing Akt→mTOR signaling and shifting fuel use.\",\n      \"evidence\": \"MCK-Cre double muscle-specific knockout with metabolic flux and signaling analysis\",\n      \"pmids\": [\"21135130\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"IRS2-specific contribution versus IRS1 not isolated\", \"Did not address recovery or compensation\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Established IRS2 as a required component of hippocampal LTP signaling and showed bidirectional roles in neurodegeneration, where lowering Irs2 protects in a Huntington's model via FoxO1-driven autophagy/antioxidant programs.\",\n      \"evidence\": \"Hippocampal slice electrophysiology with IRS2 phospho-detection; bidirectional Irs2 modulation in R6/2 HD mice\",\n      \"pmids\": [\"21955917\", \"21926467\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Receptor/kinase phosphorylating IRS2 during LTP not identified\", \"Mechanism linking IRS2 to NMDA/Fyn activation unresolved\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Identified isoform- and context-specific regulators of IRS2 abundance: JNK3 maintains IRS2 expression transcriptionally via FoxO3A in beta cells, and chronic leptin remodels IR/IRS2/SOCS3/JAK2 associations in hypothalamus.\",\n      \"evidence\": \"Isoform-specific siRNA in beta cell lines; co-IP in rat hypothalamus with chronic icv leptin and acute insulin\",\n      \"pmids\": [\"22563476\", \"21255014\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct vs indirect JNK3 effects not separated\", \"Single-lab co-IP without reciprocal validation in vivo\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Placed FoxO1 genetically downstream of IRS2 in energy balance, showing FoxO1 deletion in LepRb neurons normalizes the obesity and glucose phenotypes of neuronal Irs2 loss.\",\n      \"evidence\": \"Lepr-Cre × Irs2-flox conditional knockout with epistatic FoxO1 deletion and metabolic phenotyping\",\n      \"pmids\": [\"22560222\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Arcuate transcriptional targets mediating the effect not fully defined\", \"Neuron-subtype resolution limited\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Mapped specific inhibitory serine sites on IRS2 (Ser303/Ser675) phosphorylated by AngII/PKCβ2 that block insulin-induced tyrosine phosphorylation and a stabilizing PKA/14-3-3 mechanism at Ser1137/1138, providing residue-level control of IRS2 activity and stability.\",\n      \"evidence\": \"Site-directed mutagenesis, phospho-specific antibodies, GST-14-3-3 pulldowns, mass spectrometry, cycloheximide chase in endothelial cells and HEK293/hepatocytes\",\n      \"pmids\": [\"23775122\", \"23615913\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Interplay between positive and negative serine sites unresolved\", \"In vivo stoichiometry of these modifications unknown\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Established cardiac and vascular roles for IRS proteins and additional regulators, showing heart-specific IRS1/IRS2 loss causes heart failure (with p38α as a writer of IRS loss) and HIF-2α as a hepatic IRS2 inducer necessary and sufficient for its metabolic effects.\",\n      \"evidence\": \"Heart-specific double KO with echocardiography and cardiomyocyte p38 analysis; liver-specific HIF-2α activation with Irs2-/- rescue\",\n      \"pmids\": [\"24159000\", \"24037094\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"IRS2-specific cardiac function separate from IRS1 not isolated\", \"Direct vs indirect HIF-2α induction not fully separated\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Revealed non-canonical and vascular IRS2 functions: IRS2-dependent GRK2 recruitment to the insulin receptor suppresses β2AR/cAMP signaling in cardiomyocytes, and endothelial IRS2 governs islet blood flow required for glucose-induced insulin secretion.\",\n      \"evidence\": \"Co-IP and phosphorylation/internalization assays in IRS2-knockout cardiomyocytes; EC-specific Irs2 knockout with islet perfusion and enalapril rescue\",\n      \"pmids\": [\"25460042\", \"25277391\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of IR-IRS2-GRK2 complex not resolved\", \"Endothelial IRS2 effectors controlling perfusion not detailed\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Defined positive ubiquitin-based regulation, showing Nedd4 monoubiquitinates IRS2 to recruit Epsin1 and drive plasma-membrane localization that enhances IGF-1R-induced tyrosine phosphorylation and growth, and extended IRS2 function to podocyte insulin signaling via PTEN.\",\n      \"evidence\": \"Ubiquitination and Epsin1 binding assays, membrane fractionation, zebrafish rescue; Irs2-/- podocytes with PTEN-knockdown rescue\",\n      \"pmids\": [\"25879670\", \"26384875\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Ubiquitin chain topology and reversal enzymes not defined\", \"Whether PTEN regulation is direct unresolved\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Defined the proliferative arm of beta-cell IRS2 signaling, showing glucose-induced replication requires IRS2→mTOR→cyclin D2 independent of the insulin receptor.\",\n      \"evidence\": \"IRS2 and IR knockout mice, mTOR/ERK inhibitors, and cyclin D2 adenoviral rescue validated in human islets\",\n      \"pmids\": [\"26740601\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Upstream receptor driving glucose-induced IRS2 activation unidentified\", \"Link from mTOR to cyclin D2 transcription not detailed\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Consolidated IRS2's roles in cancer and immunometabolism: ALK and YAP/TAZ drive IRS2-dependent AKT signaling in neuroblastoma and liver cancer, IRS2 mutations enhance breast cancer invasion, and macrophage IRS2 controls IL-4-induced M2 polarization via a FoxO1/HDAC3/NCoR1 corepressor.\",\n      \"evidence\": \"MS-based interactome and siRNA in neuroblastoma; AAV-Cas9 IRS2 knockout in PTEN/SAV1 mice; PILC IRS2-mutant invasion assays; myeloid-specific Irs2/IR knockouts with corepressor co-IP\",\n      \"pmids\": [\"30459283\", \"29400692\", \"29669935\", \"30451856\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of IRS2 mutant gain-of-function in invasion not defined\", \"Direct vs indirect corepressor regulation by IRS2 unresolved\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Defined fasting-state transcriptional reprogramming of the IRS1:IRS2 ratio, showing glucagon/cAMP→CREB→PGC1A induces IRS2 while suppressing IRS1, with IRS2 required for insulin suppression of gluconeogenesis.\",\n      \"evidence\": \"Primary hepatocyte gain/loss of PGC1A with CREB inhibition, glucose-production assays, and in vivo overexpression\",\n      \"pmids\": [\"30770439\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct PGC1A coactivator targets on IRS2 promoter not mapped\", \"Integration with other IRS2-inducing TFs unresolved\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Defined a cancer-stem-cell mechanism whereby IRS2-PI3K inhibits GSK3β to block MYC Thr58 phosphorylation, stabilizing MYC to sustain breast CSC self-renewal.\",\n      \"evidence\": \"IRS2 knockout cells, GSK3β/MYC phospho-assays, proteasome inhibition, and T58A-MYC rescue in Irs2-/- cells with sphere assays\",\n      \"pmids\": [\"36476848\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo tumor relevance not established here\", \"Single-lab mechanism\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the many positive and negative IRS2 inputs—receptor docking, monoubiquitination/membrane recruitment, multisite serine phosphorylation, and competing transcriptional regulators—are quantitatively integrated to set IRS2 abundance and activity in a tissue- and stimulus-specific manner remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No integrated stoichiometric model of IRS2 PTM crosstalk\", \"Structural basis for p110α-PI3K selectivity over IRS1 unknown\", \"Mechanisms determining tissue-specific IRS isoform dominance incompletely defined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 7, 16, 31, 36]},\n      {\"term_id\": \"GO:0005515\", \"supporting_discovery_ids\": [1, 8, 17, 32, 43]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [0, 16]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [1, 32]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 1, 16]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [6, 12, 14]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [3, 37, 43]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [35, 36, 38, 44]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [8, 29, 32]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"INSR\", \"IGF1R\", \"PIK3R1\", \"JAK2\", \"ALK\", \"NEDD4\", \"SOCS3\", \"GRK2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}