Effect of wheel running exercise and myostatin depletion on gene expression in triceps brachii muscles of mice

The purpose of this study was to determine whether postdevelopmental myostatin depletion influenced the changes in skeletal muscle gene expression profiles induced by a long-term increase in physical activity. Myostatin levels in muscles of adult male mice with floxed myostatin genes were reduced ~85% by activating Cre recombinase. Control mice with normal myostatin genes had the same Cre-activating treatment. Some of the mice were housed in ordinary cages throughout the study, limiting their physical activity. Other mice were given free access to running wheels for the final 12 weeks of the study. At the end of the study, comprehensive gene expression profiles of triceps brachii muscles were determined by RNA sequencing (RNA-Seq), with muscles from mice selected for similarity of running behavior throughout the period of wheel access. Wheel running increased expression of hundreds of mRNAs encoding proteins involved in oxidative energy metabolism, and this response was not affected by myostatin deficiency. The running-induced increase in the ratio of Myh1 mRNA (which encodes myosin heavy chain type 2x) to Myh4 mRNA (which encodes myosin heavy chain type 2b) also was not affected by myostatin depletion. At every threshold of P (computed by analysis of variance), the number of transcripts with interactions between activity level and myostatin level was fewer than the number expected by chance. These data suggest that myostatin is not required for transcriptional adaptations to moderate-intensity exercise. Overall design: 12 samples, 6 from sedentary mice and 6 from active (wheel running) mice. 3 control and 3 myostatin-deficient mice within each activity level.

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Caetano-Anollés K, Mishra S, Rodriguez-Zas SL