Skeletal muscle gene expression after myostatin knockout in mature mice

RNA from 5 mice with postdevelopmental knockout of myostatin and 5 mice with normal myostatin expression was analyzed with comprehensive oligonucleotide microarrays. Myostatin depletion affected the expression of several hundred genes at nominal P < 0.01, but fewer than a hundred effects were statistically significant according to a more stringent criterion (false discovery rate < 5%). Most of the effects were less than 1.5-fold in magnitude. In contrast to previously-reported effects of constitutive myostatin knockout, postdevelopmental knockout did not downregulate expression of genes encoding slow isoforms of contractile proteins or genes encoding proteins involved in energy metabolism. Several collagen genes were expressed at lower levels in the myostatin-deficient muscles, and this led to reduced tissue collagen levels as reflected by hydroxyproline content. Myostatin knockout tended to down-regulate the expression of sets of genes with promoter motifs for Smad3, Smad4, myogenin, NF-κB, serum response factor, and numerous other transcription factors. Main conclusions: in mature muscle, myostatin is a key transcriptional regulator of collagen genes, but not genes encoding contractile proteins or genes encoding proteins involved in energy metabolism. Comparison of muscle gene expression in 5 mice with postdevelopmental myostatin knockout and 5 control mice