title: Genetic variation in fatty acid-binding protein-4 and peroxisome proliferator-activated receptor gamma interactively influence insulin sensitivity and body composition in males.
abstract: Obesity and type 2 diabetes are closely related, multifactorial metabolic conditions characterized by alterations in energy metabolism and glucose homeostasis, respectively. Peroxisome proliferator-activated receptor gamma (PPARgamma) is a ligand-dependent transcription factor that regulates genes involved in lipid and glucose homeostasis, including the adipocyte-specific fatty acid-binding protein (FABP4). In turn, FABP4 binds fatty acids and transports them to the nucleus where the FABP4/fatty acid complex activates PPARgamma in a positive feedback loop. In this study, we tested the hypothesis that the polymorphisms, FABP4-376 and PPARgamma Pro12Ala, interactively influence insulin sensitivity and body composition in nondiabetic, Hispanic and non-Hispanic white males (n = 314) participating in the San Luis Valley Diabetes Study (SLVDS). Although the individual sites were not statistically significantly associated with any of the outcomes, we found statistically significant interaction terms in 2-way analysis of covariance (ANCOVA) models for homeostasis model assessment of insulin resistance (HOMA-IR) (P =.014) and lean mass (P =.019). While the PPARgamma Pro12Ala site was the only statistically significant predictor of fat mass in the 2-way model (P =.012), the FABP4 and PPARgamma main effect terms individually became stronger when considered in one model compared with the analysis of each polymorphism separately. These findings provide evidence that FABP4 and PPARgamma work together to influence a biologic pathway affecting insulin sensitivity and body composition, illustrating the importance of investigating the joint effect of genes in determining susceptibility for complex disease.
authors.affiliation: Department of Human Genetics, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA, USA.
authors.forename: Coleen M
authors.initials: CM
authors.lastname: Damcott
authors.forename: Susan P
authors.initials: SP
authors.lastname: Moffett
authors.forename: Eleanor
authors.initials: E
authors.lastname: Feingold
authors.forename: M Michael
authors.initials: MM
authors.lastname: Barmada
authors.forename: Julie A
authors.initials: JA
authors.lastname: Marshall
authors.forename: Richard F
authors.initials: RF
authors.lastname: Hamman
authors.forename: Robert E
authors.initials: RE
authors.lastname: Ferrell
mesh_terms: D000328:Adult; D001823:Body Composition / Q000235:genetics*; D002352:Carrier Proteins / Q000235:genetics*; D015331:Cohort Studies; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005838:Genotype; D006630:Hispanic or Latino; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D007333:Insulin Resistance / Q000235:genetics*; D008297:Male; D009154:Mutation / Q000235:genetics; D009363:Neoplasm Proteins; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics*; D025521:Tumor Suppressor Proteins; D014481:United States; D044465:White People
chemical_list: D002352:Carrier Proteins; C493410:FABP4 protein, human; C107608:FABP7 protein, human; C493411:Fabp4 protein, mouse; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D009363:Neoplasm Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins