Investigating the Role of H3K27me3 Demethylation in VEGFA Gene Activation Following Acute Exercise in Human Skeletal Muscle

Abstract

Skeletal muscle adapts to endurance exercise by tissular remodelling such as angiogenesis, the growth of novel capillaries, a response largely mediated by transcriptional activation of vascular endothelial growth factor A (VEGF). While VEGF expression is classically regulated by the hypoxia-inducible transcription factor (HIF), recent evidence in endothelial cells suggests that epigenetic mechanisms—specifically, the removal of the repressive histone mark H3K27me3—also play a key role in activating this angiogenic gene. It remains unclear however, whether skeletal muscle myocytes utilize similar chromatin-based regulation for VEGF transcription during exercise. This study proposal aims to determine whether acute endurance exercise in humans induces epigenetic remodeling at the VEGFA promoter in skeletal muscle through H3K27me3 demethylation, and whether this is accompanied by upregulation of histone demethylases. Recreationally active male and female participants will complete 60 minutes of treadmill running at 70–80% of their maximal oxygen uptake. Muscle biopsies will be collected from the vastus lateralis at baseline, immediately post-exercise, and 1- and 3-hours post-exercise. Chromatin immunoprecipitation followed by quantitative-PCR (ChIP-qPCR) will be used to assess H3K27me3 enrichment at the VEGFA promoter. VEGFA mRNA expression will be measured via real-time quantitative PCR, and protein expression of the histone demethylases JMJD3 (KDM6B) and KDM4B will be quantified by immunoblotting. Our hypothesized results include a time-dependent decrease in H3K27me3 enrichment at the VEGFA promoter post-exercise, with significant reductions at 1 and 3 hours. This will be paralleled by increased VEGFA mRNA expression and a rapid and sustained upregulation of JMJD3 and KDM4B protein levels. These results would suggest that myocytes may employ a conserved epigenetic mechanism, previously observed in endothelial cells, to regulate VEGFA expression in response to exercise-induced hypoxia. The coordinated reduction in H3K27me3 and upregulation of demethylases supports a chromatin remodeling model of angiogenic gene activation. This study would broaden our understanding of exercise-induced molecular adaptation by implicating histone modifications as regulators of VEGF expression in human skeletal muscle. Future work should investigate the cell-type specificity of these changes and their implications for long-term skeletal muscle remodeling to endurance exercise.