BioProject

Peroxisome proliferator-activated receptor beta/delta protects against obesity by reducing dyslipidemia and insulin resistance via effects in various organs, including muscle, adipose tissue, liver, and heart. More...

Peroxisome proliferator-activated receptor beta/delta protects against obesity by reducing dyslipidemia and insulin resistance via effects in various organs, including muscle, adipose tissue, liver, and heart. However, nothing is known about the function of PPAR-beta in pancreas, a prime organ in the control of glucose metabolism. To gain insight into so far hypothetical functions of this PPAR isotype in insulin production, we specifically ablated Ppar-beta in pancreas. The mutated mice developed a chronic hyperinsulinemia, due to an increase in both beta-cell mass and insulin secretion. Gene expression profiling indicated a broad repressive function of PPAR-beta impacting the vesicular compartment, actin cytoskeleton, and metabolism of glucose and fatty acids. Analyses of insulin release from the islets revealed an increased second-phase glucose-stimulated insulin secretion. Higher levels of PKD, PKC-delta and diacyglycerol in mutated animals lead to an enhanced formation of trans-Golgi network (TGN)-to-plasma-membrane transport carriers in concert with F-actin disassembly, which resulted in increased insulin secretion and its associated systemic effects. Taken together, these results provide evidence for PPAR-beta playing a repressive role on beta-cell growth and insulin exocytosis, which shed new light on its anti-obesity action. Overall design: Pancreas-specific knock-out animals were generated by breeding mice harbouring a floxed Ppar-beta (PPARbetafl/fl) to mice expressing the Cre transgene under the control of the Pdx1 promoter (Pdx1Cre). Islets from 3 different animals from the knock-out group Pdx1Cre;PPARbetafl/fl and the control littermates group PPARbetafl/fl were compared. Less...