Featured Publications
Lower Hepatic Fat Is Associated With Improved Insulin Secretion in a High-Risk Prediabetes Subphenotype During Lifestyle Intervention
Wagner R, Heni M, Kantartzis K, Sandforth A, Machann J, Schick F, Peter A, Fritsche L, Szendrödi J, Pfeiffer A, Schürmann A, Blüher M, Hauner H, Seissler J, Bornstein S, Roden M, Stefan N, Birkenfeld A, White M, Häring H, Fritsche A. Lower Hepatic Fat Is Associated With Improved Insulin Secretion in a High-Risk Prediabetes Subphenotype During Lifestyle Intervention. Diabetes 2022, 72: 362-366. PMID: 36525512, PMCID: PMC9935494, DOI: 10.2337/db22-0441.Peer-Reviewed Original ResearchMeSH KeywordsBlood GlucoseHumansInsulinInsulin ResistanceInsulin SecretionLife StyleLiverPrediabetic StateConceptsInsulin secretionLifestyle interventionLiver fatOral glucose tolerance testHigh liver fatLifestyle intervention studyGlucose tolerance testHigh-risk clustersHepatic fatTolerance testInsulin sensitivitySpecific subphenotypesIntervention studiesSecretionTime pointsInterventionPrediabetesGlycemic traitsFatSubphenotypesGlycemiaCluster 3TAZ inhibits glucocorticoid receptor and coordinates hepatic glucose homeostasis in normal physiological states
Xu S, Liu Y, Hu R, Wang M, Stöhr O, Xiong Y, Chen L, Kang H, Zheng L, Cai S, He L, Wang C, Copps K, White M, Miao J. TAZ inhibits glucocorticoid receptor and coordinates hepatic glucose homeostasis in normal physiological states. ELife 2021, 10: e57462. PMID: 34622775, PMCID: PMC8555985, DOI: 10.7554/elife.57462.Peer-Reviewed Original ResearchConceptsGluconeogenic gene promotersBinding of GRGene promoterGlucocorticoid receptorGlucose homeostasisLigand-binding domainGlucose productionOverexpression of TAZHepatic glucose homeostasisWW domainsBlood glucose concentrationPhysiological fastingGluconeogenic genesGR response elementResponse elementNovel roleTAZNormal physiological stateGR transactivationPhysiological statePromoterMouse liverPericentral hepatocytesPathological statesGlucose concentration
2021
Insulin action at a molecular level – 100 years of progress
White M, Kahn C. Insulin action at a molecular level – 100 years of progress. Molecular Metabolism 2021, 52: 101304. PMID: 34274528, PMCID: PMC8551477, DOI: 10.1016/j.molmet.2021.101304.Peer-Reviewed Original ResearchConceptsAmino acid sequenceType 2 diabetesFunction of insulinAcid sequenceMolecular knowledgeHuman diseasesInsulin-sensitive tissuesPhysiological functionsPhysiological roleInsulin receptorInsulin-resistant statesInsulin 100 yearsInsulin actionBlood glucoseCascadeInsulinDiabetesTissueDiscoveryRegulationTreatmentRemarkable advancesRoleSequenceYearsFoxO1 suppresses Fgf21 during hepatic insulin resistance to impair peripheral glucose utilization and acute cold tolerance
Stöhr O, Tao R, Miao J, Copps K, White M. FoxO1 suppresses Fgf21 during hepatic insulin resistance to impair peripheral glucose utilization and acute cold tolerance. Cell Reports 2021, 34: 108893. PMID: 33761350, PMCID: PMC8529953, DOI: 10.1016/j.celrep.2021.108893.Peer-Reviewed Original ResearchMeSH KeywordsAdaptation, PhysiologicalAdipocytes, BrownAdipose Tissue, BrownAnimalsBlood GlucoseBody WeightCold TemperatureDiet, High-FatFibroblast Growth FactorsForkhead Box Protein O1Gene Expression RegulationGlucoseHomeostasisInsulinInsulin Receptor Substrate ProteinsInsulin ResistanceLipid MetabolismLiverMice, KnockoutOrgan SpecificityOxidation-ReductionThermogenesisConceptsHepatic insulin resistanceInsulin resistanceGlucose utilizationHigher plasma Fgf21 levelsSevere hepatic insulin resistanceFGF21 knockout micePlasma FGF21 levelsPeripheral glucose utilizationInsulin-resistant miceThermogenic gene expressionFGF21 resistancePharmacologic formsFGF21 levelsCold intoleranceFGF21 functionMetabolic healthBAT functionGlucose homeostasisKnockout miceFGF21Adenoviral infectionMiceWeight lossSkeletal muscleAcute cold tolerance
2019
Phosphorylation of Forkhead Protein FoxO1 at S253 Regulates Glucose Homeostasis in Mice
Zhang K, Guo X, Yan H, Wu Y, Pan Q, Shen J, Li X, Chen Y, Li L, Qi Y, Xu Z, Xie W, Zhang W, Threadgill D, He L, Villarreal D, Sun Y, White M, Zheng H, Guo S. Phosphorylation of Forkhead Protein FoxO1 at S253 Regulates Glucose Homeostasis in Mice. Endocrinology 2019, 160: 1333-1347. PMID: 30951171, PMCID: PMC6482038, DOI: 10.1210/en.2018-00853.Peer-Reviewed Original ResearchConceptsKey phosphorylation sitesForkhead protein FoxO1Protein kinase BTranscription factor forkhead box O1Factor forkhead box O1FOXO1 nuclear localizationMultiple physiological functionsMouse Foxo1Forkhead box O1Pancreatic plasticityPhosphorylation sitesHuman FOXO1Nuclear localizationTarget genesMolecular basisS253Kinase BFoxO1 activityPhysiological functionsGlucose homeostasisBox O1Pancreatic β-cell functionFOXO1PhosphorylationHepatic glucose production
2013
IRS1Ser307 phosphorylation does not mediate mTORC1-induced insulin resistance
Herrema H, Lee J, Zhou Y, Copps K, White M, Ozcan U. IRS1Ser307 phosphorylation does not mediate mTORC1-induced insulin resistance. Biochemical And Biophysical Research Communications 2013, 443: 689-693. PMID: 24333417, PMCID: PMC3926104, DOI: 10.1016/j.bbrc.2013.12.023.Peer-Reviewed Original ResearchConceptsInsulin resistanceGlucose intoleranceInsulin sensitivityImpaired insulin receptorStress-induced insulin resistanceRapamycin complex 1 (mTORC1) activityPhosphorylation of IRS1Endoplasmic reticulum stressDiabetic miceER stress-induced insulin resistanceMammalian targetIRS1 phosphorylationReticulum stressMiceIntoleranceInsulin receptorVivoSer307
2012
Pulsatile Portal Vein Insulin Delivery Enhances Hepatic Insulin Action and Signaling
Matveyenko A, Liuwantara D, Gurlo T, Kirakossian D, Man C, Cobelli C, White M, Copps K, Volpi E, Fujita S, Butler P. Pulsatile Portal Vein Insulin Delivery Enhances Hepatic Insulin Action and Signaling. Diabetes 2012, 61: 2269-2279. PMID: 22688333, PMCID: PMC3425431, DOI: 10.2337/db11-1462.Peer-Reviewed Original ResearchMeSH KeywordsAnimalsBlood GlucoseDiabetes Mellitus, ExperimentalDiabetes Mellitus, Type 2DogsForkhead Transcription FactorsGlucokinaseInsulinInsulin Receptor Substrate ProteinsInsulin ResistanceInsulin SecretionLiverMaleNerve Tissue ProteinsPortal VeinProto-Oncogene Proteins c-aktRatsRats, Sprague-DawleySignal TransductionConceptsPulsatile insulin secretionHepatic insulin actionInsulin secretionHepatic insulinPortal veinInsulin deliveryPulsatile patternInsulin actionDiscrete insulin secretory burstsHepatic insulin receptor substrateImpaired activationType 2 diabetes mellitusSequential liver biopsiesIntraportal insulin infusionInsulin secretory burstsHepatic insulin resistanceHepatic portal veinExpression of glucokinaseGlycemic controlDiabetes mellitusLiver biopsyInsulin resistanceInsulin infusionSecretory burstsRat model
2011
Regulation of glucose homeostasis through a XBP-1–FoxO1 interaction
Zhou Y, Lee J, Reno C, Sun C, Park S, Chung J, Lee J, Fisher S, White M, Biddinger S, Ozcan U. Regulation of glucose homeostasis through a XBP-1–FoxO1 interaction. Nature Medicine 2011, 17: 356-365. PMID: 21317886, PMCID: PMC3897616, DOI: 10.1038/nm.2293.Peer-Reviewed Original ResearchMeSH KeywordsAnimalsBlood GlucoseDisease Models, AnimalDNA-Binding ProteinsForkhead Box Protein O1Forkhead Transcription FactorsGlucoseHomeostasisHydrolysisInsulin ResistanceLiverMiceMutationPhosphorylationReceptor, InsulinRegulatory Factor X Transcription FactorsSignal TransductionTranscription FactorsX-Box Binding Protein 1
2007
Plasma insulin levels predict the development of atherosclerosis when IRS2 deficiency is combined with severe hypercholesterolemia in apolipoprotein E-null mice.
Gonzalez-Navarro H, Vila-Caballer M, Pastor M, Vinue A, White M, Burks D, Andres V. Plasma insulin levels predict the development of atherosclerosis when IRS2 deficiency is combined with severe hypercholesterolemia in apolipoprotein E-null mice. Frontiers In Bioscience-Landmark 2007, 12: 2291-8. PMID: 17127239, DOI: 10.2741/2231.Peer-Reviewed Original ResearchMeSH KeywordsAnimalsApolipoproteins EAtherosclerosisBlood GlucoseDiabetes Mellitus, Type 2Diabetic AngiopathiesFemaleHypercholesterolemiaInsulinInsulin Receptor Substrate ProteinsIntracellular Signaling Peptides and ProteinsLipidsMacrophagesMaleMiceMice, KnockoutMuscle, Smooth, VascularPhosphoproteinsConceptsInsulin receptor substrate 2ApoE-/- miceDevelopment of atherosclerosisIrs2-/- miceSevere hypercholesterolemiaInsulin levelsType 2 diabetic patientsAtherosclerotic lesion burdenPre-diabetic patientsPlasma insulin levelsFat-fed miceAbsence of hyperglycaemiaDefective insulin signalingDiabetic patientsLesion burdenClinical manifestationsInsulin resistanceModerate hypercholesterolemiaApolipoprotein EGlucose levelsAtherosclerotic lesionsAtherosclerosisHypercholesterolemiaNull miceImportant modulator
2005
Reduced mitochondrial density and increased IRS-1 serine phosphorylation in muscle of insulin-resistant offspring of type 2 diabetic parents
Morino K, Petersen KF, Dufour S, Befroy D, Frattini J, Shatzkes N, Neschen S, White MF, Bilz S, Sono S, Pypaert M, Shulman GI. Reduced mitochondrial density and increased IRS-1 serine phosphorylation in muscle of insulin-resistant offspring of type 2 diabetic parents. Journal Of Clinical Investigation 2005, 115: 3587-3593. PMID: 16284649, PMCID: PMC1280967, DOI: 10.1172/jci25151.Peer-Reviewed Original ResearchMeSH KeywordsBiopsyBlood GlucoseBlotting, WesternBody Mass IndexBody WeightDiabetes Mellitus, Type 2DNA, MitochondrialFamily HealthFemaleGene Expression RegulationGlucose Clamp TechniqueGlucose Tolerance TestHumansHyperinsulinismImmunoprecipitationInsulinInsulin Receptor Substrate ProteinsInsulin ResistanceLipidsMaleMicroscopy, ElectronMicroscopy, Electron, TransmissionMitochondriaMusclesPhosphoproteinsPhosphorylationProtein Serine-Threonine KinasesReverse Transcriptase Polymerase Chain ReactionRNA, MessengerSerineSignal TransductionTime FactorsTranscription, GeneticTriglyceridesConceptsInsulin-resistant offspringIR offspringType 2 diabetesInsulin-stimulated muscle glucose uptakeType 2 diabetic parentsIntramyocellular lipid contentHyperinsulinemic-euglycemic clampMuscle glucose uptakeIRS-1 serine phosphorylationMuscle mitochondrial densityMitochondrial densityMuscle biopsy samplesSerine kinase cascadeInsulin-stimulated Akt activationDiabetic parentsInsulin resistanceControl subjectsBiopsy samplesGlucose uptakeLipid accumulationMitochondrial dysfunctionInsulin signalingAkt activationEarly defectsMuscleExendin-4 Uses Irs2 Signaling to Mediate Pancreatic β Cell Growth and Function*
Park S, Dong X, Fisher T, Dunn S, Omer A, Weir G, White M. Exendin-4 Uses Irs2 Signaling to Mediate Pancreatic β Cell Growth and Function*. Journal Of Biological Chemistry 2005, 281: 1159-1168. PMID: 16272563, DOI: 10.1074/jbc.m508307200.Peer-Reviewed Original ResearchMeSH KeywordsAnimalsBlood GlucoseCell LineCell SurvivalCyclic AMPDose-Response Relationship, DrugElectrophoresis, Polyacrylamide GelExenatideGenotypeGlucagon-Like Peptide-1 ReceptorGlucoseGuinea PigsHumansHyperglycemiaImmunoblottingImmunohistochemistryImmunoprecipitationInsulinInsulin Receptor Substrate ProteinsInsulin SecretionInsulin-Secreting CellsIntracellular Signaling Peptides and ProteinsIslets of LangerhansMiceMice, TransgenicModels, BiologicalModels, ChemicalPancreasPeptidesPhosphoproteinsPhosphorylationReceptor, InsulinReceptors, GlucagonReverse Transcriptase Polymerase Chain ReactionRNA, MessengerRNA, Small InterferingSignal TransductionTime FactorsVenomsConceptsGlucagon-like peptide-1 receptor agonistsPeptide-1 receptor agonistsReceptor agonistExendin-4Beta cellsProgressive beta cell lossShort-term therapeutic effectsInsulin-like growth factorBeta-cell lossProgression of diabetesBeta-cell massBeta-cell replicationBeta-cell growthPancreatic β-cell growthΒ-cell growthIrs2 branchPrevents diabetesInsulin/insulin-like growth factorCell growthInsulin secretionTherapeutic effectIRS2 expressionLong-term effectsFatal diabetesCell lossCyclins D2 and D1 Are Essential for Postnatal Pancreatic β-Cell Growth
Kushner J, Ciemerych M, Sicinska E, Wartschow L, Teta M, Long S, Sicinski P, White M. Cyclins D2 and D1 Are Essential for Postnatal Pancreatic β-Cell Growth. Molecular And Cellular Biology 2005, 25: 3752-3762. PMID: 15831479, PMCID: PMC1084308, DOI: 10.1128/mcb.25.9.3752-3762.2005.Peer-Reviewed Original ResearchConceptsBeta-cell massAdult beta-cell massD2 mRNA expressionCyclin D2 mRNA expressionBeta-cell proliferationMonths of agePancreatic β-cell growthBeta cell expansionΒ-cell growthGlucose intoleranceGlucose toleranceInsulin secretionGlucose homeostasisAdult miceBeta cellsIslet growthPancreatic isletsCyclin D1MRNA expressionDiabetesMiceCyclin D2Cyclin D3Adult murineIslet development
2004
Disruption of the SH2-B Gene Causes Age-Dependent Insulin Resistance and Glucose Intolerance
Duan C, Yang H, White M, Rui L. Disruption of the SH2-B Gene Causes Age-Dependent Insulin Resistance and Glucose Intolerance. Molecular And Cellular Biology 2004, 24: 7435-7443. PMID: 15314154, PMCID: PMC506995, DOI: 10.1128/mcb.24.17.7435-7443.2004.Peer-Reviewed Original ResearchMeSH KeywordsAdaptor Proteins, Signal TransducingAdipose TissueAgingAnimalsBlood GlucoseCarrier ProteinsCell LineDietary FatsGlucose IntoleranceHomeostasisHumansInsulinInsulin Receptor Substrate ProteinsInsulin ResistanceIntracellular Signaling Peptides and ProteinsIslets of LangerhansLiverMaleMiceMice, Inbred StrainsMice, KnockoutMitogen-Activated Protein KinasesMuscle, SkeletalPhosphatidylinositol 3-KinasesPhosphoproteinsProtein Serine-Threonine KinasesProto-Oncogene ProteinsProto-Oncogene Proteins c-aktReceptor, InsulinSignal TransductionConceptsSrc homology 2Insulin receptor substrate-1Insulin receptor activationInsulin receptorTyrosine phosphorylationSH2 domain-dependent mannerPleckstrin homology domain-containing adaptor proteinDomain-containing adaptor proteinDomain-dependent mannerReceptor substrate-1Skeletal muscleSH2 domainHomology 2Adaptor proteinReceptor activationSubstrate-1Physiological roleCultured cellsGlucose homeostasisERK1/2 pathwayDependent insulin resistancePhysiological enhancerSystemic deletionPhosphorylationIRS2Islet-Sparing Effects of Protein Tyrosine Phosphatase-1b Deficiency Delays Onset of Diabetes in IRS2 Knockout Mice
Kushner J, Haj F, Klaman L, Dow M, Kahn B, Neel B, White M. Islet-Sparing Effects of Protein Tyrosine Phosphatase-1b Deficiency Delays Onset of Diabetes in IRS2 Knockout Mice. Diabetes 2004, 53: 61-66. PMID: 14693698, DOI: 10.2337/diabetes.53.1.61.Peer-Reviewed Original ResearchMeSH KeywordsAnimalsBlood GlucoseCrosses, GeneticDiabetes Mellitus, Type 1Glucose Tolerance TestInsulinInsulin Receptor Substrate ProteinsIntracellular Signaling Peptides and ProteinsIslets of LangerhansKineticsLeptinMaleMiceMice, KnockoutModels, AnimalPhosphoproteinsProtein Tyrosine Phosphatase, Non-Receptor Type 1Protein Tyrosine PhosphatasesSignal TransductionConceptsPeripheral insulin sensitivityBeta-cell areaBeta-cell functionInsulin sensitivityPancreatic beta cell areaPancreatic beta-cell functionDecreased insulin requirementIrs2 knockout miceBeta cell homeostasisMonths of ageInsulin requirementsPeripheral actionsGlucose toleranceGlucose homeostasisKnockout miceDelay onsetMiceInsulin receptorPTP1B deficiencyDiabetesReceptor complexIRS2Novel roleInsulinDownstream targets
2002
Pdx1 restores β cell function in Irs2 knockout mice
Kushner J, Ye J, Schubert M, Burks D, Dow M, Flint C, Dutta S, Wright C, Montminy M, White M. Pdx1 restores β cell function in Irs2 knockout mice. Journal Of Clinical Investigation 2002, 109: 1193-1201. PMID: 11994408, PMCID: PMC150960, DOI: 10.1172/jci14439.Peer-Reviewed Original ResearchMeSH KeywordsAnimalsAnimals, NewbornBlood GlucoseBody WeightDiabetes Mellitus, Type 2FemaleHomeodomain ProteinsInsulinInsulin Receptor Substrate ProteinsIntracellular Signaling Peptides and ProteinsIslets of LangerhansMaleMiceMice, KnockoutPhosphoproteinsReceptor, InsulinSignal TransductionTrans-ActivatorsConceptsOnset of diabetesPeripheral insulin actionBeta-cell failureType 2 diabetesBeta-cell massEarly-onset diabetesIrs2 knockout micePancreatic beta-cell growthBeta-cell growthWeeks of ageIrs2 branchHepatocyte nuclear factorGlucose toleranceExpression of Pdx1Knockout miceBeta cellsDiabetesInsulin actionInsulin/MiceNuclear factorTranscription factor Pdx1Cell functionIsletsTransgenic expressionInsulin Signaling After Exercise in Insulin Receptor Substrate-2-Deficient Mice
Howlett K, Sakamoto K, Hirshman M, Aschenbach W, Dow M, White M, Goodyear L. Insulin Signaling After Exercise in Insulin Receptor Substrate-2-Deficient Mice. Diabetes 2002, 51: 479-483. PMID: 11812758, DOI: 10.2337/diabetes.51.2.479.Peer-Reviewed Original ResearchConceptsPhosphotyrosine-associated phosphatidylinositolIRS-2 tyrosine phosphorylationIRS-2 signalingInsulin receptor substrate-2-deficient (IRS2(-/-)) miceWild-type miceIRS-2-deficient miceEnhanced insulin actionWT miceTyrosine phosphorylationTreadmill exerciseInsulin receptor substrateInsulin actionMiceImmediate periodSkeletal muscleInsulin-stimulated responsesInsulin signalingMarked increaseReceptor substrateExerciseInsulinPresent studySignalingPhosphorylation
2000
Tissue-specific insulin resistance in mice with mutations in the insulin receptor, IRS-1, and IRS-2
Kido Y, Burks D, Withers D, Bruning J, Kahn C, White M, Accili D. Tissue-specific insulin resistance in mice with mutations in the insulin receptor, IRS-1, and IRS-2. Journal Of Clinical Investigation 2000, 105: 199-205. PMID: 10642598, PMCID: PMC377430, DOI: 10.1172/jci7917.Peer-Reviewed Original ResearchMeSH KeywordsAdipose TissueAnimalsBlood GlucoseCell SizeDiabetes Mellitus, Type 2Disease Models, AnimalHeterozygoteHomozygoteHyperglycemiaInsulinInsulin Receptor Substrate ProteinsInsulin ResistanceIntracellular Signaling Peptides and ProteinsIslets of LangerhansLiverMaleMiceMice, KnockoutMuscle, SkeletalMutationOrgan SpecificityPhosphatidylinositol 3-KinasesPhosphoproteinsReceptor, InsulinConceptsBeta-cell hyperplasiaSevere insulin resistanceInsulin resistanceSkeletal muscleInsulin actionAltered beta-cell functionCompensatory beta-cell hyperplasiaMild insulin resistanceTissue-specific insulin resistanceBeta-cell functionUnderlying metabolic abnormalitiesType 2 diabetesInsulin receptorHeterozygous null mutationsDiabetic miceMetabolic abnormalitiesInsulin receptor substrateAdipose tissueRole of IRSType 2MiceHyperplasiaLiverMuscleIRS-2
1999
Irs-2 coordinates Igf-1 receptor-mediated β-cell development and peripheral insulin signalling
Withers D, Burks D, Towery H, Altamuro S, Flint C, White M. Irs-2 coordinates Igf-1 receptor-mediated β-cell development and peripheral insulin signalling. Nature Genetics 1999, 23: 32-40. PMID: 10471495, DOI: 10.1038/12631.Peer-Reviewed Original ResearchMeSH KeywordsAge FactorsAnimalsApoptosisBlood GlucoseBody WeightFemaleGene Expression Regulation, DevelopmentalGlucose Tolerance TestInsulinInsulin Receptor Substrate ProteinsIntracellular Signaling Peptides and ProteinsIslets of LangerhansLiverMaleMiceMice, KnockoutMuscle, SkeletalPancreasPhosphoproteinsReceptor, IGF Type 1Signal TransductionTime FactorsConceptsIGF-1 receptorΒ-cell developmentIGF-1Glucose homeostasisΒ-cellsPeripheral insulin resistancePeripheral target tissuesEffect of insulinPancreatic β-cellsPeripheral insulinInsulin resistanceInsulin receptor substratePost-natal growthGlucose metabolismNull allelesTarget tissuesInsulinMiceReceptor substrateIR-1Carbohydrate metabolismReceptorsSurvivalCell growthPleiotropic effects
1998
Disruption of IRS-2 causes type 2 diabetes in mice
Withers D, Gutierrez J, Towery H, Burks D, Ren J, Previs S, Zhang Y, Bernal D, Pons S, Shulman G, Bonner-Weir S, White M. Disruption of IRS-2 causes type 2 diabetes in mice. Nature 1998, 391: 900-904. PMID: 9495343, DOI: 10.1038/36116.Peer-Reviewed Original ResearchMeSH KeywordsAnimalsBlood GlucoseCloning, MolecularDiabetes Mellitus, Type 2FemaleGene TargetingHumansInsulinInsulin Receptor Substrate ProteinsInsulin ResistanceIntracellular Signaling Peptides and ProteinsIslets of LangerhansLiverMaleMiceMice, Inbred C57BLMuscle, SkeletalPhosphatidylinositol 3-KinasesPhosphoproteinsPhosphorylationReceptor, InsulinRecombination, GeneticSignal TransductionConceptsType 2 diabetesInsulin resistanceHuman type 2 diabetesPancreatic β-cell functionInsulin secretion increasesSingle molecular abnormalityΒ-cell compensationIRS-2-deficient miceΒ-cell functionHuman type 2Insulin secretionInsulin receptor substrateGlucose homeostasisSecretion increasesInsulin actionType 2DiabetesMolecular abnormalitiesProgressive deteriorationSkeletal muscleIRS-2Insulin signalingIRS-1Mild resistanceMice