Exercise prevents maternal high-fat diet-induced hypermethylation of the Pgc-1α gene and age-dependent metabolic dysfunction in the offspring

Abstract

Abnormal conditions during early development adversely affect later health. We investigated whether maternal exercise could protect offspring from adverse effects of a maternal high-fat diet (HFD) with a focus on the metabolic outcomes and epigenetic regulation of the metabolic master regulator, peroxisome proliferator-activated receptor γ coactivator-1α (Pgc-1α). Female C57BL/6 mice were exposed to normal chow, an HFD, or an HFD with voluntary wheel exercise for 6 weeks before and throughout pregnancy. Methylation of the Pgc-1α promoter at CpG site -260 and expression of Pgc-1α mRNA were assessed in skeletal muscle from neonatal and 12-month-old offspring, and glucose and insulin tolerance tests were performed in the female offspring at 6, 9, and 12 months. Hypermethylation of the Pgc-1α promoter caused by a maternal HFD was detected at birth and was maintained until 12 months of age with a trend of reduced expression of Pgc-1α mRNA (P = 0.065) and its target genes. Maternal exercise prevented maternal HFD-induced Pgc-1α hypermethylation and enhanced Pgc-1α and its target gene expression, concurrent with amelioration of age-associated metabolic dysfunction at 9 months of age in the offspring. Therefore, maternal exercise is a powerful lifestyle intervention for preventing maternal HFD-induced epigenetic and metabolic dysregulation in the offspring.

Figure 1

Maternal exercise prevents maternal HFD-induced hypermethylation of the Pgc-1α promoter in skeletal muscle in offspring. Pgc-1α promoter methylation and mRNA expression were assessed by pyrosequencing and real-time PCR, respectively, in offspring skeletal muscle and liver at birth. A: Schematic presentation of the structural feature of the Pgc-1α promoter. Circles represent CpG islands, labeled by the base pair number relative to the transcription start site, with site −260 highlighted in red. Open rectangles represent transcription factor binding sites. The arrow marks the transcription start site. Graphs show Pgc-1α promoter methylation at CpG site −260 in muscle (B) and liver (C). Graphs also show Pgc-1α mRNA in offspring skeletal muscle (D) and its correlation with Pgc-1α methylation status (E). *P < 0.05.

Figure 2

Maternal HFD‐induced Pgc-1α hypermethylation is maintained with reduced gene expression and abnormal metabolic function in aging mice. Pgc-1α promoter methylation and mRNA expression were assessed by pyrosequencing and real-time PCR, respectively, in offspring skeletal muscle at 12 months of age. Graphs show Pgc-1α promoter methylation at CpG site −260 (A), Pgc-1α mRNA expression (B), correlation between Pgc-1α methylation and gene expression (C), and mRNA expression of Glut4, Cox4, Cyt c, Myh2a, and Sod1 (D) in skeletal muscle at 12 months of age. Body weight and composition are presented as a growth profile from birth to 12 months (E); percentages of lean body mass (F) and fat mass (G) as measured by dual-energy X-ray absorptiometry at 12 months of age in female offspring are also shown. *P < 0.05; **P < 0.01; ***P < 0.001.

Figure 3

Maternal exercise protects offspring from maternal HFD‐induced metabolic dysfunction. Whole-body glucose tolerance and insulin sensitivity were assessed in aging female offspring following a bolus intraperitoneal injection of glucose or insulin, respectively, by measuring blood glucose over time. Graphs show blood glucose levels during GTTs and areas under the curve (AUC) at 6 (A and B, respectively), 9 (D and E, respectively) and 12 (G and H, respectively) months of age. Blood glucose levels during ITTs at 6 (C), 9 (F), and 12 (I) months of age also are shown. *P < 0.05; **P < 0.01.

Figure 4

Maternal exercise alone does not affect Pgc-1α promoter methylation in the skeletal muscle or glucose tolerance in offspring. Pgc-1α promoter methylation was assessed by pyrosequencing in skeletal muscle and glucose tolerance was assessed following a bolus intraperitoneal injection of glucose by measuring blood glucose over time in 18-week-old female and male offspring. Graphs show Pgc-1α promoter methylation at CpG site −260 in females (A) and males (B) and blood glucose during GTTs in females (C) and males (D).