Eight-Week Aerobic Training Activates Extracellular Matrix Biogenesis in Human Skeletal Muscle

Abstract

We aimed to investigate the effect of 8 weeks of moderate endurance training without considerable mechanical stress on the activation of extracellular matrix (ECM) gene expression in human skeletal muscle. Mechanical stress activates ECM biogenesis in the skeletal muscles, therefore only aerobic exercise on a cycling ergometer with concentric muscle contractions was used in the study. Skeletal muscle samples from m. vastus lateralis were taken from seven young untrained males before and after 8 weeks of aerobic training. Changes in the transcriptome (RNA sequencing) and proteome (shotgun quantitative proteomics analysis) were assessed in the samples; ECM-associated proteins (or matrisome) were determined using the Matrisome DB database. After training period, a change (mainly an increase) in the content of 14 ECM proteins and 134 mRNAs of ECM proteins was found. The largest increase in protein content was found for collagens 1 and 3 (1.7 and 2.2 times, respectively) – the main proteins of the human skeletal muscle’s ECM, which was consistent with an increase in the corresponding mRNA by 10–20 times. In addition, an increase in the expression of more than a hundred mRNAs of collagens, glycoproteins, proteoglycans, and enzymatic regulators of ECM was found, which occurs simultaneously with of an increase in the expression of genes of growth factors (IGF1, PDGFs, TGFB1, MDK, etc.) playing an important role in ECM biogenesis regulation. In conclusion, 8-week aerobic exercise training without considerable mechanical stress is a powerful stimulus for the activation of ECM biogenesis in skeletal muscle.