Proteomic and transcriptomic response of human skeletal muscle to 12-week resistance training

Abstract

BACKGROUND: Decreased skeletal muscle mass and properties lead to the development of various pathologies and increased risk for injuries. Studies of the molecular mechanisms of skeletal muscle adaptation to resistance training to increase muscle mass and strength appear imperative for medicine and sports. AIM: To assess changes in the proteomic profile (quantitative panoramic mass spectrometric analysis) of skeletal muscles and the correlation of these changes with the expression of the corresponding mRNAs (RNA-sequencing) before and after 12 weeks of strength training and changes in the transcriptome 8 and 24 h after an acute resistance exercise with one leg. METHODS: Ten untrained men (aged 23 [20.8–25.9] years; body mass index, 22 [20.9–25.1] kg/m2) performed a two-legged seated platform press for 12 weeks (3 times/week, 50–75% of maximum voluntary contraction [MVC]). After training, the volunteers performed an acute strength exercise with one leg. Before and after 12 weeks of training, the MVC and volume of the quadriceps femoris muscle were assessed. Before and after training, as well as 8 and 24 h after the acute resistance exercise, a biopsy of the vastus lateralis muscle was performed from the loaded and contralateral limbs for immunohistochemical, proteomic (high-performance liquid chromatography-tandem mass spectrometry), and transcriptomic (RNA-sequencing) analyses. RESULTS: The 12-week strength training increased the MVC by 19%, quadriceps femoris volume by 12%, cross-sectional area of type 2 (fast) fibers by 29%, minimum Feret diameter of type 2 fibers by 10%, and type 1 (slow) fibers by 13%. Of the 1174 detected proteins, 24 increased, and 83 decreased in content. Strength training resulted in an increase in the expression levels of 142 and a decrease in 65 of the 12,112 mRNAs detected, with enrichment for the functional terms of the extracellular environment, matrix, basement membrane, etc. Changes in the contents of 433 mRNAs after 8 h and 639 mRNAs after 24 h were found when comparing the once-loaded muscle with the contralateral one (genes associated with contractile activity). Changes in the content of only a small part of proteins (5–9 out of 107) correlated with the changes in the corresponding mRNAs. CONCLUSION: Proteomic analysis showed that the 12-week resistance training had little effect on the relative abundance of high-abundance proteins in muscles. The increase in muscle mass induced by training appears to be explained by a similar change in the synthesis/degradation rates of the detected proteins. In the comparison of proteomic data with changes in mRNA expression after 12 weeks of training and 8 and 24 h after a single load (gene response specific to contractile activity), changes in protein contents caused by strength training were regulated mainly at the post-transcriptional level.