167-OR: Exercise Training Alters Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1 Alpha (PGC-1 Alpha) DNA Methylation in Human Skeletal Muscle

Exercise training improves insulin sensitivity in skeletal muscle and increases mitochondrial function. These improvements are due, in part, to an increase in expression of peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1 alpha). The effect of exercise training on epigenetic factors, such as DNA methylation remains elusive. The aim of this study was to determine whether an 8-week exercise training alters DNA methylation of PGC-1 alpha. Fourteen participants (5M/9F; age 34.2±3.0 years) were studied before and after 8-weeks of supervised exercise training (60% of VO2peak for 20 minutes, 3 times per week; gradually increased to 70% of VO2peak for 45 minutes, 4 times per week). Euglycemic hyperinsulinemic clamps in combination with vastus lateralis muscle biopsies were obtained before and after the exercise training. Training increased peak aerobic capacity (VO2peak) from 31.9±1.0 to 36.5±1.4 ml∙min^-1∙kg FFM^-1 (P = 0.013) and improved insulin sensitivity from 7.0±2.1 to 9.2±2.3 ml·kg FFM⁻¹·min⁻¹. Genomic DNA was extracted and pyrosequencing methylation analysis was performed on CpG -816 and -783 bp upstream transcription start site (TSS). Methylation analysis revealed a significantly decreased methylation at CpG -816 bp following exercise (pre = 16.8±0.9 % versus post = 14.2±0.5 %, P = 0.035). For CpG -783 bp, methylation did not change following exercise (pre = 11±0.6 % versus post = 11.5±0.7 %, P = NS). Our results showed that exercise training improved insulin sensitivity and peak aerobic capacity. In addition, we provide evidence that exercise training alters PGC-1 alpha methylation at CpG -816 bp. We propose that the increased response of insulin action in muscle following exercise training is due, in part, to epigenetic modifications.