Sex-specific skeletal muscle gene expression responses to exercise reveal novel direct mediators of insulin sensitivity change.
Understanding how exercise improves whole-body insulin sensitivity (Si) involves complex molecular signaling. This study examines skeletal muscle gene expression changes related to Si, considering sex differences, exercise amount, and intensity to identify pharmacologic targets mimicking exercise benefits. Fifty-three participants from STRRIDE (Studies of Targeted Risk Reduction Interventions through Defined Exercise) I and II completed eight months of aerobic training. Gene expression was assessed via Affymetrix and Illumina technologies, and Si was measured using intravenous glucose tolerance tests. A novel discovery protocol integrating literature-derived and data-driven modeling identified causal pathways and direct transcriptional targets. In women, exercise amount primarily influenced transcription factor targets, which were generally inhibitory, while in men, exercise intensity drove activating targets. Common transcription factors included ATF1, CEBPA, BACH2, and STAT1. Si-related transcriptional targets included TACR3 and TMC7 for intensity-driven effects, and GRIN3B and EIF3B for amount-driven effects. Two key pathways mediating Si improvements were identified: estrogen signaling and protein kinase C (PKC) signaling, both converging on the epidermal growth factor receptor (EGFR) and other relevant targets. The molecular pathways underlying Si improvements varied by sex and exercise parameters, highlighting potential skeletal muscle-specific drug targets such as EGFR to replicate the metabolic benefits of exercise.
