Reduced PPARγ2 expression in adipose tissue of male rat offspring from obese dams is associated with epigenetic modifications

Abstract

According to the Developmental Origin of Health and Disease (DOHaD) concept, maternal obesity and accelerated growth in neonates program obesity later in life. White adipose tissue (WAT) has been the focus of developmental programming events, although underlying mechanisms remain elusive. In rodents, WAT development primarily occurs during lactation. We previously reported that adult rat offspring from dams fed a high-fat (HF) diet exhibited fat accumulation and decreased peroxisome proliferator-activated receptor γ (PPARγ) mRNA levels in WAT. We hypothesized that PPARg down-regulation occurs via epigeneticmal programming which takes place during adipogenesis. We therefore examined epigenetic modifications in thePPARg1 and PPARg2promoters in perirenal (pWAT) and inguinal fat pads of HF offspring at weaning (postnatal d 21) and in adulthood. Postnatal d 21 is a period characterized by active epigenomic remodeling in the PPARg2 promoter (DNA hypermethylation and depletion in active histone modification H3ac andH3K4me3) in pWAT, consistent with increased DNA methyl transferase and DNA methylation activities. Adult HF offspring exhibited sustained hypermethylation and histone modification H3ac of the PPARg2 promoter in both deposits, correlated with persistent decreased PPARg2 mRNA levels. Consistent with the DOHaD hypothesis, retained epigenetic marks provide a mechanistic basis for the cellular memory linking maternal obesity to a predisposition for later adiposity.