Leptin deficiency unmasks the deleterious effects of impaired peroxisome proliferator-activated receptor γ function (P465L PPARγ) in mice
article
Peroxisome proliferator-activated receptor (PPAR)γ is a key transcription factor facilitating fat deposition in adipose tissue through its proadipogenic and lipogenic actions. Human patients with dominant-negative mutations in PPARγ display lipodystrophy and extreme insulin resistance. For this reason it was completely unexpected that mice harboring an equivalent mutation (P465L) in PPARγ developed normal amounts of adipose tissue and were insulin sensitive. This finding raised important doubts about the interspecies translatability of PPARγ-related findings, bringing into question the relevance of other PPARγ murine models. Here, we demonstrate that when expressed on a hyperphagic ob/ob background, the P465L PPARγ mutant grossly exacerbates the insulin resistance and metabolic disturbances associated with leptin deficiency, yet reduces whole-body adiposity and adipocyte size. In mouse, coexistence of the P465L PPARγ mutation and the leptin-deficient state creates a mismatch between insufficient adipose tissue expandability and excessive energy availability, unmasking the deleterious effects of PPARγ mutations on carbohydrate metabolism and replicating the characteristic clinical symptoms observed in human patients with dominant-negative PPARγ mutations. Thus, adipose tissue expandability is identified as an important factor for the development of insulin resistance in the context of positive energy balance. © 2006 by the American Diabetes Association. Chemicals / CAS: insulin, 9004-10-8; Blood Glucose; Insulin, 11061-68-0; Leptin; PPAR gamma
Topics
Peroxisome proliferator activated receptor gammaAdipose tissueAnimal cellAnimal experimentAnimal modelAnimal tissueCarbohydrate metabolismControlled studyEnergy balanceFemaleGene expressiongene mutationHomozygosityHyperphagiaInsulin resistanceInsulin sensitivityLipid metabolismLipid storageLipogenesisMaleMetabolic disorderNonhumanObesityPoint mutationProtein deficiencyProtein functionTissue distributionTissue expansionBloodGeneticsGlucose blood levelHomozygoteLethal geneMetabolismMouse mutantPathologyPhysiologyAdipose TissueAnimalsBlood GlucoseGene Expression ProfilingGenes, LethalHomozygoteInsulinInsulin ResistanceLeptinLipid MetabolismMiceMice, ObesePPAR gamma
TNO Identifier
239520
ISSN
00121797
Source
Diabetes, 55(10), pp. 2669-2677.
Pages
2669-2677
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