2023
Inhibition of HSD17B13 protects against liver fibrosis by inhibition of pyrimidine catabolism in nonalcoholic steatohepatitis
Luukkonen P, Sakuma I, Gaspar R, Mooring M, Nasiri A, Kahn M, Zhang X, Zhang D, Sammalkorpi H, Penttilä A, Orho-Melander M, Arola J, Juuti A, Zhang X, Yimlamai D, Yki-Järvinen H, Petersen K, Shulman G. Inhibition of HSD17B13 protects against liver fibrosis by inhibition of pyrimidine catabolism in nonalcoholic steatohepatitis. Proceedings Of The National Academy Of Sciences Of The United States Of America 2023, 120: e2217543120. PMID: 36669104, PMCID: PMC9942818, DOI: 10.1073/pnas.2217543120.Peer-Reviewed Original ResearchConceptsNonalcoholic fatty liver diseaseLiver fibrosisLiver diseaseCommon chronic liver diseaseChronic liver diseaseFatty liver diseaseRisk of fibrosisDistinct mouse modelsPyrimidine catabolismNonalcoholic steatohepatitisMouse modelTherapeutic targetFibrosisDihydropyrimidine dehydrogenaseHuman liverA variantCommon variantsMetabolomics approachDiseaseMiceInhibitionCatabolismKnockdownSteatohepatitisGimeracil
2022
Q-Flux: A method to assess hepatic mitochondrial succinate dehydrogenase, methylmalonyl-CoA mutase, and glutaminase fluxes in vivo
Hubbard B, LaMoia T, Goedeke L, Gaspar R, Galsgaard K, Kahn M, Mason G, Shulman G. Q-Flux: A method to assess hepatic mitochondrial succinate dehydrogenase, methylmalonyl-CoA mutase, and glutaminase fluxes in vivo. Cell Metabolism 2022, 35: 212-226.e4. PMID: 36516861, PMCID: PMC9887731, DOI: 10.1016/j.cmet.2022.11.011.Peer-Reviewed Original ResearchDyrk1b promotes hepatic lipogenesis by bypassing canonical insulin signaling and directly activating mTORC2 in mice
Bhat N, Narayanan A, Fathzadeh M, Kahn M, Zhang D, Goedeke L, Neogi A, Cardone RL, Kibbey RG, Fernandez-Hernando C, Ginsberg HN, Jain D, Shulman G, Mani A. Dyrk1b promotes hepatic lipogenesis by bypassing canonical insulin signaling and directly activating mTORC2 in mice. Journal Of Clinical Investigation 2022, 132: e153724. PMID: 34855620, PMCID: PMC8803348, DOI: 10.1172/jci153724.Peer-Reviewed Original ResearchConceptsDe novo lipogenesisNonalcoholic steatohepatitisInsulin resistanceHepatic lipogenesisElevated de novo lipogenesisNonalcoholic fatty liver diseaseFatty liver diseaseLiver of patientsHepatic glycogen storageHigh-sucrose dietHepatic insulin resistanceFatty acid uptakeMetabolic syndromeLiver diseaseHepatic steatosisTriacylglycerol secretionNovo lipogenesisHepatic insulinTherapeutic targetImpaired activationAcid uptakeGlycogen storageMouse liverLiverLipogenesis
2020
Membrane-bound sn-1,2-diacylglycerols explain the dissociation of hepatic insulin resistance from hepatic steatosis in MTTP knockout mice
Abulizi A, Vatner DF, Ye Z, Wang Y, Camporez JP, Zhang D, Kahn M, Lyu K, Sirwi A, Cline GW, Hussain MM, Aspichueta P, Samuel VT, Shulman GI. Membrane-bound sn-1,2-diacylglycerols explain the dissociation of hepatic insulin resistance from hepatic steatosis in MTTP knockout mice. Journal Of Lipid Research 2020, 61: 1565-1576. PMID: 32907986, PMCID: PMC7707176, DOI: 10.1194/jlr.ra119000586.Peer-Reviewed Original ResearchConceptsHepatic insulin resistanceInsulin resistanceHepatic insulin sensitivityHepatic steatosisLipid-induced hepatic insulin resistancePKCε activationInsulin sensitivityKnockout miceNormal hepatic insulin sensitivityWild-type control miceHepatic ceramide contentHyperinsulinemic-euglycemic clampComprehensive metabolic phenotypingLipid dropletsHepatic DAG contentDAG contentGlucose intoleranceControl miceMTTP activityHepatic insulinAnimal modelsSteatosisAKT Ser/ThrMiceMetabolic phenotypingA Membrane-Bound Diacylglycerol Species Induces PKCϵ-Mediated Hepatic Insulin Resistance
Lyu K, Zhang Y, Zhang D, Kahn M, Ter Horst KW, Rodrigues MRS, Gaspar RC, Hirabara SM, Luukkonen PK, Lee S, Bhanot S, Rinehart J, Blume N, Rasch MG, Serlie MJ, Bogan JS, Cline GW, Samuel VT, Shulman GI. A Membrane-Bound Diacylglycerol Species Induces PKCϵ-Mediated Hepatic Insulin Resistance. Cell Metabolism 2020, 32: 654-664.e5. PMID: 32882164, PMCID: PMC7544641, DOI: 10.1016/j.cmet.2020.08.001.Peer-Reviewed Original ResearchConceptsPlasma membraneEndoplasmic reticulumHigh-fat diet-induced hepatic insulin resistanceSubcellular fractionation methodInsulin receptor kinaseKey lipid speciesHepatic insulin resistanceDiet-induced hepatic insulin resistanceReceptor kinaseDiacylglycerol acyltransferase 2Molecular mechanismsAcute knockdownPhosphorylationLipid dropletsLipid speciesAcyltransferase 2KnockdownLiver-specific overexpressionDAG accumulationPKCϵDAG contentMembraneFractionation methodKinaseMitochondria
2019
Hepatic insulin sensitivity is improved in high‐fat diet‐fed Park2 knockout mice in association with increased hepatic AMPK activation and reduced steatosis
Edmunds LR, Huckestein BR, Kahn M, Zhang D, Chu Y, Zhang Y, Wendell SG, Shulman GI, Jurczak MJ. Hepatic insulin sensitivity is improved in high‐fat diet‐fed Park2 knockout mice in association with increased hepatic AMPK activation and reduced steatosis. Physiological Reports 2019, 7: e14281. PMID: 31724300, PMCID: PMC6854109, DOI: 10.14814/phy2.14281.Peer-Reviewed Original ResearchConceptsPark2 KO miceHepatic insulin sensitivityKO miceInsulin sensitivityInsulin resistanceShort-term HFD feedingDiet-induced hepatic insulin resistanceWhole-body insulin sensitivityPark2 knockout miceImproved hepatic insulin sensitivityDiet-induced obesityHigh-fat dietBioactive lipid speciesTumor necrosis factorHepatic insulin resistanceHepatic AMPK activationNegative energy balanceEndoplasmic reticulum stress responseRegular chowCytokine levelsHFD feedingReduced steatosisChronic HFDInterleukin-6Necrosis factor
2018
In vivo studies on the mechanism of methylene cyclopropyl acetic acid and methylene cyclopropyl glycine-induced hypoglycemia.
Qiu Y, Perry RJ, Camporez JG, Zhang XM, Kahn M, Cline GW, Shulman GI, Vatner DF. In vivo studies on the mechanism of methylene cyclopropyl acetic acid and methylene cyclopropyl glycine-induced hypoglycemia. Biochemical Journal 2018, 475: 1063-1074. PMID: 29483297, PMCID: PMC5884121, DOI: 10.1042/bcj20180063.Peer-Reviewed Original Research
2015
Hepatic insulin resistance and increased hepatic glucose production in mice lacking Fgf21
Camporez JP, Asrih M, Zhang D, Kahn M, Samuel VT, Jurczak MJ, Jornayvaz FR. Hepatic insulin resistance and increased hepatic glucose production in mice lacking Fgf21. Journal Of Endocrinology 2015, 226: 207-217. PMID: 26203166, DOI: 10.1530/joe-15-0136.Peer-Reviewed Original ResearchConceptsHepatic insulin resistanceFGF21 KO miceInsulin resistanceHepatic glucose productionKetogenic dietKO miceHepatic glucoseLipid metabolismGlucose productionFibroblast growth factor 21Littermate WT controlsRole of FGF21Growth factor 21Plasma glucagon levelsType 2 diabetesPotential pharmacological agentsFGF21 resistanceGlucagon levelsFactor 21Fat massMale miceWT littermatesPharmacological agentsWT controlsInsulin action
2013
Saturated and unsaturated fat induce hepatic insulin resistance independently of TLR-4 signaling and ceramide synthesis in vivo
Galbo T, Perry RJ, Jurczak MJ, Camporez J, Alves TC, Kahn M, Guigni BA, Serr J, Zhang D, Bhanot S, Samuel VT, Shulman GI. Saturated and unsaturated fat induce hepatic insulin resistance independently of TLR-4 signaling and ceramide synthesis in vivo. Proceedings Of The National Academy Of Sciences Of The United States Of America 2013, 110: 12780-12785. PMID: 23840067, PMCID: PMC3732992, DOI: 10.1073/pnas.1311176110.Peer-Reviewed Original ResearchConceptsHepatic insulin resistanceFat-induced hepatic insulin resistanceInsulin resistanceToll-like receptor 4 receptorTLR-4 knockout miceFat-induced insulin resistanceTLR-4 activationTLR-4 signalingType 2 diabetesImpairment of insulinInhibition of insulinCeramide synthesisActivation of PKCεTLR-4Hepatic steatosisHepatic accumulationKnockout miceIRS-2 signalingReceptor signalingCeramide accumulationAntisense oligonucleotideInsulinPrimary eventImpairmentFatty acidsTargeting Pyruvate Carboxylase Reduces Gluconeogenesis and Adiposity and Improves Insulin Resistance
Kumashiro N, Beddow SA, Vatner DF, Majumdar SK, Cantley JL, Guebre-Egziabher F, Fat I, Guigni B, Jurczak MJ, Birkenfeld AL, Kahn M, Perler BK, Puchowicz MA, Manchem VP, Bhanot S, Still CD, Gerhard GS, Petersen KF, Cline GW, Shulman GI, Samuel VT. Targeting Pyruvate Carboxylase Reduces Gluconeogenesis and Adiposity and Improves Insulin Resistance. Diabetes 2013, 62: 2183-2194. PMID: 23423574, PMCID: PMC3712050, DOI: 10.2337/db12-1311.Peer-Reviewed Original ResearchConceptsPyruvate carboxylaseAntisense oligonucleotideHepatocyte fatty acid oxidationInsulin resistanceNonalcoholic fatty liver diseaseZucker diabetic fatty ratsHigh fat-fed ratsFatty liver diseaseLiver biopsy specimensDiabetic fatty ratsPlasma lipid concentrationsType 2 diabetesHepatic insulin sensitivityHuman liver biopsy specimensEndogenous glucose productionHepatic insulin resistancePlasma glucose concentrationPotential therapeutic approachSpecific antisense oligonucleotideFat-fed ratsCarboxylaseFatty acid oxidationDe novo fatty acid synthesisLiver diseaseTissue-specific inhibitionCellular Mechanisms by Which FGF21 Improves Insulin Sensitivity in Male Mice
Camporez JP, Jornayvaz FR, Petersen MC, Pesta D, Guigni BA, Serr J, Zhang D, Kahn M, Samuel VT, Jurczak MJ, Shulman GI. Cellular Mechanisms by Which FGF21 Improves Insulin Sensitivity in Male Mice. Endocrinology 2013, 154: 3099-3109. PMID: 23766126, PMCID: PMC3749479, DOI: 10.1210/en.2013-1191.Peer-Reviewed Original ResearchMeSH KeywordsAdipose Tissue, BrownAnimalsCells, CulturedDiet, High-FatDrug ImplantsEnergy MetabolismFibroblast Growth FactorsGlucose IntoleranceHumansInfusions, SubcutaneousInsulin ResistanceIsoenzymesLipectomyLipid MetabolismLiverMaleMiceMice, Inbred C57BLMuscle, SkeletalProtein Kinase CProtein Kinase C-epsilonProtein Kinase C-thetaRecombinant ProteinsConceptsType 2 diabetesInsulin resistanceRegular chowInsulin sensitivityInsulin actionNonalcoholic fatty liver diseaseFibroblast growth factor 21Fatty liver diseasePeripheral insulin sensitivityEffects of FGF21HFD-fed miceGrowth factor 21High-fat dietCellular mechanismsWild-type miceWhite adipose tissueMuscle insulin resistanceMuscle ceramide contentProtein kinase Cε activationFGF21 administrationLiver diseaseFactor 21Male miceNovel therapiesAdipose tissueCellular Mechanism by Which Estradiol Protects Female Ovariectomized Mice From High-Fat Diet-Induced Hepatic and Muscle Insulin Resistance
Camporez JP, Jornayvaz FR, Lee HY, Kanda S, Guigni BA, Kahn M, Samuel VT, Carvalho CR, Petersen KF, Jurczak MJ, Shulman GI. Cellular Mechanism by Which Estradiol Protects Female Ovariectomized Mice From High-Fat Diet-Induced Hepatic and Muscle Insulin Resistance. Endocrinology 2013, 154: 1021-1028. PMID: 23364948, PMCID: PMC3578999, DOI: 10.1210/en.2012-1989.Peer-Reviewed Original ResearchConceptsEstrogen replacement therapyOVX miceMuscle insulin sensitivityMuscle insulin resistanceInsulin resistanceInsulin sensitivityReplacement therapyHigh-fat diet feedingWhole-body insulin resistanceWhole-body insulin sensitivityFemale ovariectomized miceEctopic lipid depositionWhole-body energy expenditureType 2 diabetesEnergy expenditureWeeks of ageWhole-body energy homeostasisProtein kinase Cε activationHepatic DAG contentLivers of shamPostmenopausal womenSham miceOvariectomized miceGlucose toleranceE2 treatmentRole of patatin‐like phospholipase domain‐containing 3 on lipid‐induced hepatic steatosis and insulin resistance in rats
Kumashiro N, Yoshimura T, Cantley JL, Majumdar SK, Guebre‐Egziabher F, Kursawe R, Vatner DF, Fat I, Kahn M, Erion DM, Zhang X, Zhang D, Manchem VP, Bhanot S, Gerhard GS, Petersen KF, Cline GW, Samuel VT, Shulman GI. Role of patatin‐like phospholipase domain‐containing 3 on lipid‐induced hepatic steatosis and insulin resistance in rats. Hepatology 2013, 57: 1763-1772. PMID: 23175050, PMCID: PMC3597437, DOI: 10.1002/hep.26170.Peer-Reviewed Original ResearchCGI-58 knockdown sequesters diacylglycerols in lipid droplets/ER-preventing diacylglycerol-mediated hepatic insulin resistance
Cantley JL, Yoshimura T, Camporez JP, Zhang D, Jornayvaz FR, Kumashiro N, Guebre-Egziabher F, Jurczak MJ, Kahn M, Guigni BA, Serr J, Hankin J, Murphy RC, Cline GW, Bhanot S, Manchem VP, Brown JM, Samuel VT, Shulman GI. CGI-58 knockdown sequesters diacylglycerols in lipid droplets/ER-preventing diacylglycerol-mediated hepatic insulin resistance. Proceedings Of The National Academy Of Sciences Of The United States Of America 2013, 110: 1869-1874. PMID: 23302688, PMCID: PMC3562813, DOI: 10.1073/pnas.1219456110.Peer-Reviewed Original ResearchMeSH Keywords1-Acylglycerol-3-Phosphate O-AcyltransferaseAdipose Tissue, WhiteAnimalsCell MembraneDiet, High-FatDiglyceridesEndoplasmic ReticulumGene ExpressionGene Knockdown TechniquesHumansImmunoblottingInjections, IntraperitonealInsulin ResistanceLipidsLiverMaleMiceMice, Inbred C57BLOligonucleotides, AntisenseProtein Kinase C-epsilonProtein TransportReverse Transcriptase Polymerase Chain ReactionConceptsHepatic insulin resistanceInsulin resistanceHepatic steatosisCGI-58 knockdownHigh-fat fed miceHyperinsulinemic-euglycemic clamp studiesSevere hepatic steatosisCGI-58 expressionFat-fed miceLipid-induced hepatic insulin resistanceChanarin-Dorfman syndromeComparative gene identification-58Lipid droplet-associated proteinAdipose triglyceride lipaseDroplet-associated proteinAntisense oligonucleotide treatmentInsulin sensitivityASO treatmentClamp studiesLipotoxic conditionsKnockdown miceCGI-58PKCε activationMiceTriglyceride lipase
2012
The Role of the Carbohydrate Response Element-Binding Protein in Male Fructose-Fed Rats
Erion DM, Popov V, Hsiao JJ, Vatner D, Mitchell K, Yonemitsu S, Nagai Y, Kahn M, Gillum MP, Dong J, Murray SF, Manchem VP, Bhanot S, Cline GW, Shulman GI, Samuel VT. The Role of the Carbohydrate Response Element-Binding Protein in Male Fructose-Fed Rats. Endocrinology 2012, 154: 36-44. PMID: 23161873, PMCID: PMC3529388, DOI: 10.1210/en.2012-1725.Peer-Reviewed Original ResearchConceptsDe novo lipogenesisResponse element-binding proteinCarbohydrate response element-binding proteinASO treatmentHepatic expressionNovo lipogenesisElement-binding proteinInsulin-stimulated peripheral glucose uptakeNonalcoholic fatty liver diseaseAntisense oligonucleotideMale Sprague-Dawley ratsHepatic de novo lipogenesisFructose-fed groupHepatic insulin responsivenessFatty liver diseaseFructose fed ratsPeripheral glucose uptakeHyperinsulinemic-euglycemic clampHigh-fat dietHepatic lipid contentHepatic triglyceride secretionHepatic insulin sensitivitySprague-Dawley ratsPlasma triglyceride concentrationsPlasma uric acid
2011
Dissociation of Inositol-requiring Enzyme (IRE1α)-mediated c-Jun N-terminal Kinase Activation from Hepatic Insulin Resistance in Conditional X-box-binding Protein-1 (XBP1) Knock-out Mice*
Jurczak MJ, Lee AH, Jornayvaz FR, Lee HY, Birkenfeld AL, Guigni BA, Kahn M, Samuel VT, Glimcher LH, Shulman GI. Dissociation of Inositol-requiring Enzyme (IRE1α)-mediated c-Jun N-terminal Kinase Activation from Hepatic Insulin Resistance in Conditional X-box-binding Protein-1 (XBP1) Knock-out Mice*. Journal Of Biological Chemistry 2011, 287: 2558-2567. PMID: 22128176, PMCID: PMC3268415, DOI: 10.1074/jbc.m111.316760.Peer-Reviewed Original ResearchAnimalsDNA-Binding ProteinsEndoplasmic ReticulumEndoplasmic Reticulum Chaperone BiPEndoplasmic Reticulum StressEndoribonucleasesEukaryotic Initiation Factor-2Heat-Shock ProteinsInsulin Receptor Substrate ProteinsInsulin ResistanceJNK Mitogen-Activated Protein KinasesLipid MetabolismLiverMiceMice, KnockoutPhosphorylationProtein Serine-Threonine KinasesRegulatory Factor X Transcription FactorsSignal TransductionTranscription FactorsX-Box Binding Protein 1Influence of the Hepatic Eukaryotic Initiation Factor 2α (eIF2α) Endoplasmic Reticulum (ER) Stress Response Pathway on Insulin-mediated ER Stress and Hepatic and Peripheral Glucose Metabolism*
Birkenfeld AL, Lee HY, Majumdar S, Jurczak MJ, Camporez JP, Jornayvaz FR, Frederick DW, Guigni B, Kahn M, Zhang D, Weismann D, Arafat AM, Pfeiffer AF, Lieske S, Oyadomari S, Ron D, Samuel VT, Shulman GI. Influence of the Hepatic Eukaryotic Initiation Factor 2α (eIF2α) Endoplasmic Reticulum (ER) Stress Response Pathway on Insulin-mediated ER Stress and Hepatic and Peripheral Glucose Metabolism*. Journal Of Biological Chemistry 2011, 286: 36163-36170. PMID: 21832042, PMCID: PMC3196114, DOI: 10.1074/jbc.m111.228817.Peer-Reviewed Original ResearchConceptsHepatic glucose productionInsulin sensitivityInsulin resistanceCaloric excessER stressHigh-fat diet-fed miceBasal plasma glucose concentrationsGlucose productionIGFBP-3 levelsHepatic ERPeripheral glucose metabolismTissue insulin sensitivityDiet-fed miceHepatic lipid accumulationHigh-fat dietHyperinsulinemic-euglycemic clampHepatic insulin sensitivityInfusion of insulinPlasma glucose concentrationEndoplasmic reticulum stress response pathwayEndoplasmic reticulum stressInsulin-stimulated muscleIGFBP-3Fat dietMuscle glucoseRegulation of hepatic fat and glucose oxidation in rats with lipid‐induced hepatic insulin resistance
Alves TC, Befroy DE, Kibbey RG, Kahn M, Codella R, Carvalho RA, Petersen K, Shulman GI. Regulation of hepatic fat and glucose oxidation in rats with lipid‐induced hepatic insulin resistance. Hepatology 2011, 53: 1175-1181. PMID: 21400553, PMCID: PMC3077048, DOI: 10.1002/hep.24170.Peer-Reviewed Original ResearchConceptsLipid-induced hepatic insulin resistanceHepatic insulin resistanceInsulin resistanceTricarboxylic acid fluxFatty acid oxidationPyruvate dehydrogenaseHyperinsulinemic-euglycemic clampHyperinsulinemic-hyperglycemic clampInfusion of somatostatinSubstrate availabilityHigh-fat dietPlasma glucose concentrationRegulationCritical rolePyruvate dehydrogenase fluxHepatic fatHyperglycemic clampAcid oxidationAwake ratsBasal concentrations
2009
Prevention of Hepatic Steatosis and Hepatic Insulin Resistance by Knockdown of cAMP Response Element-Binding Protein
Erion DM, Ignatova ID, Yonemitsu S, Nagai Y, Chatterjee P, Weismann D, Hsiao JJ, Zhang D, Iwasaki T, Stark R, Flannery C, Kahn M, Carmean CM, Yu XX, Murray SF, Bhanot S, Monia BP, Cline GW, Samuel VT, Shulman GI. Prevention of Hepatic Steatosis and Hepatic Insulin Resistance by Knockdown of cAMP Response Element-Binding Protein. Cell Metabolism 2009, 10: 499-506. PMID: 19945407, PMCID: PMC2799933, DOI: 10.1016/j.cmet.2009.10.007.Peer-Reviewed Original ResearchConceptsHepatic insulin resistanceNonalcoholic fatty liver diseaseCAMP response element-binding proteinInsulin resistanceResponse element-binding proteinASO treatmentElement-binding proteinCREB expressionType 2 diabetes mellitusOb/ob miceFatty liver diseaseHepatic triglyceride contentPlasma glucose concentrationFed rat modelAttractive therapeutic targetAntisense oligonucleotideDiabetes mellitusLiver diseaseZDF ratsHepatic steatosisOb micePostprandial hyperglycemiaPlasma cholesterolRat modelTriglyceride concentrationsSensitivity of Lipid Metabolism and Insulin Signaling to Genetic Alterations in Hepatic Peroxisome Proliferator–Activated Receptor-γ Coactivator-1α Expression
Estall JL, Kahn M, Cooper MP, Fisher FM, Wu MK, Laznik D, Qu L, Cohen DE, Shulman GI, Spiegelman BM. Sensitivity of Lipid Metabolism and Insulin Signaling to Genetic Alterations in Hepatic Peroxisome Proliferator–Activated Receptor-γ Coactivator-1α Expression. Diabetes 2009, 58: 1499-1508. PMID: 19366863, PMCID: PMC2699879, DOI: 10.2337/db08-1571.Peer-Reviewed Original ResearchMeSH KeywordsAdipose TissueAnimalsBlood GlucoseBody CompositionCell Culture TechniquesCrosses, GeneticFatty LiverFemaleGene Expression RegulationHepatocytesHomeostasisInsulinInsulin ResistanceIntegrasesKetonesLipidsLiverMiceMice, TransgenicPeroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alphaRNA, Small InterferingTrans-ActivatorsTranscription FactorsTriglyceridesConceptsPGC-1alpha levelsCre/lox systemExpression of genesKey metabolic enzymesKey metabolic pathwaysPGC-1alpha activityPGC-1alpha expressionPeroxisome proliferator-activated receptor gamma coactivatorReceptor γ coactivatorLipid metabolismProliferator-activated receptor gamma coactivatorComplete genetic ablationTranscriptional coactivatorNutrient deprivationReceptor gamma coactivatorPGC-1alphaFatty acid oxidationOxidative phosphorylationMetabolic enzymesLox systemCoactivatorLipid homeostasisMetabolic pathwaysGenetic ablationGenetic alterations