Proteomic analysis and protein carbonylation profile in trained and untrained rat muscles

Understanding the relationship between physical exercise, reactive oxygen species (ROS) and skeletal muscle modification is important in order to better identify the benefits or the damages that appropriate or inappropriate exercise can induce. Unbalanced ROS levels can lead to oxidation of cellular macromolecules a major class of protein oxidative modification is carbonylation. The aim of this investigation was to study muscle protein expression and carbonylation patterns in trained and untrained animal models. We analyzed two muscles characterized by different metabolisms: tibialis anterior and soleus. Whilst tibialis anterior is mostly composed of fast-twitch fibers, the soleus muscle is mostly composed of slow-twitch fibers. By a proteomic approach we identified 15 protein spots whose expression is influenced by training. Among them, in tibalis anterior we observed a down-regulation of several glycolitic enzymes. Concerning carbonylation, we observed the existence of a high basal level of protein carbonylation. Although this level shows some variation among individual animals, several proteins (mostly involved in energy metabolism, muscle contraction, and stress response) appear carbonylated in all animals and in both types of skeletal muscle. Moreover we identified 13 spots whose carbonylation increases after training. The increased carbonylation level may be correlated with the reduced CAT and SOD1 enzymes activity in both skeletal muscles. An important challenge for future investigation in this field will be to understand the impact of carbonylation on specific proteins and to evaluate whether and in which circumstances this basal level, which is supposedly well tolerated by cells, may increase as to hamper their functions.