Maternal obesity programs increased leptin gene expression in rat male offspring via epigenetic modifications in a depot-specific manner

Abstract

ObjectiveAccording to the Developmental Origin of Health and Disease (DOHaD) concept, maternal obesity and accelerated growth in neonates predispose offspring to white adipose tissue (WAT) accumulation. In rodents, adipogenesis mainly develops during lactation. The mechanisms underlying the phenomenon known as developmental programming remain elusive. We previously reported that adult rat offspring from high-fat diet-fed dams (called HF) exhibited hypertrophic adipocyte, hyperleptinemia and increased leptin mRNA levels in a depot-specific manner. We hypothesized that leptin upregulation occurs via epigenetic malprogramming, which takes place early during development of WAT.MethodsAs a first step, we identified in silico two potential enhancers located upstream and downstream of the leptin transcription start site that exhibit strong dynamic epigenomic remodeling during adipocyte differentiation. We then focused on epigenetic modifications (methylation, hydroxymethylation, and histone modifications) of the promoter and the two potential enhancers regulating leptin gene expression in perirenal (pWAT) and inguinal (iWAT) fat pads of HF offspring during lactation (postnatal days 12 (PND12) and 21 (PND21)) and in adulthood.ResultsPND12 is an active period for epigenomic remodeling in both deposits especially in the upstream enhancer, consistent with leptin gene induction during adipogenesis. Unlike iWAT, some of these epigenetic marks were still observable in pWAT of weaned HF offspring. Retained marks were only visible in pWAT of 9-month-old HF rats that showed a persistent “expandable” phenotype.ConclusionsConsistent with the DOHaD hypothesis, persistent epigenetic remodeling occurs at regulatory regions especially within intergenic sequences, linked to higher leptin gene expression in adult HF offspring in a depot-specific manner.

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

“…At PND21, HF male offspring displayed higher iWAT and pWAT deposit weights with increased leptin mRNA levels, marked adipocyte hypertrophy, and hyperplasia. HF 9M male rats showed persistent increased pWAT mass with elevated leptin mRNA levels, whereas this expandable phenotype was no longer observed in iWAT (2, 23). By contrast, both fat pads had persistently lower PPARγ expression.…”

“…Given that metabolic signals, including hormonal signaling pathways, play critical roles in determining chromatin structure (28), this study assessed the plasma metabolic profile in HF offspring. We previously reported that weaned and adult HF offspring exhibited hyperleptinemia (2, 23). The present study showed that serum triacylglycerol and insulin levels were elevated in HF male offspring at PND21 (Table 3).…”

“…Animal use accreditation by the French Ministry of Agriculture (04860) has been granted to our laboratory for experimentation with rats. Experiments were conducted in accordance with the principles of laboratory animal care (European Communities Council Directive of 1986, 86/609/EEC) as previously described (2, 23). One‐month‐old virgin female Wistar rats were purchased from Charles River Laboratories (L’Arbresle, France) and were housed in individual cages in a humidity‐controlled room with a 12:12‐h light–dark cycle.…”

“…Immunoblotting analysis was conducted as previously described (23). Monoclonal mouse antibody against PPARγ (sc‐7273) was purchased from Santa Cruz Biotechnology (Dallas, TX, USA) and was diluted 1:200.…”

“…We previously found that adult male rat offspring from dams fed a high‐fat diet (designated HF) displayed higher adiposity, hyperleptinemia, and elevated leptin gene expression in WAT (2). Persistent leptin up‐regulation occurs via epigenetic malprogramming during lactation in a depot‐specific manner (23). We also showed that adult HF offspring exhibited a decrease in peroxisome proliferator‐activated receptor γ (PPARγ) gene expression in perirenal (pWAT) fat pads (2).…”