Effect of an anti-myostatin antibody on skeletal muscle gene expression in mice
Ontology highlight
ABSTRACT: More than 2,000 genes appear to be upregulated or downregulated in skeletal muscle of mice with constitutive knockout of myostatin (Steelman et al., FASEB J 20:580-2, 2006). This study was done to determine whether inhibition of myostatin activity in mature mice has similar effects on the pattern of gene expression. Keywords: Differential expression in treated and control mice
Project description:To identify microRNAs involved in myostatin-deficient muscular hypertrophy, we compared miRNA expression in wild-type and myostatin knockout mice. Total RNA, isolated from three wild-type or myostatin knockout mice, was pooled and then used for microarray analysis.
Project description:To identify microRNAs involved in myostatin-deficient muscular hypertrophy, we compared miRNA expression in wild-type and myostatin knockout mice.
Project description:Inhibition of myostatin signaling induces strong skeletal muscle growth making it an attractive target to treat muscle wasting and sarcopenia. However, the biological function of myostatin in the heart is barely understood. We demonstrate that conditional inactivation of myostatin in the adult murine heart leads to cardiac hypertrophy, heart failure and increased lethality. To induce cardiomyocyte specific loss of myostatin a conditionally active Mstn^fl/fl allele was generated by insertion of loxP elements upstream and downstream of exons 1 and 2 of the mouse myostatin gene. The selection cassette was removed in vivo by flp-recombination. To inactivate myostatin, mice were mated to alphaMyHC-MCM mice (Sohal, DS, et al. (2001) Circulation Research 89, 20-25). Cre-recombination was achieved by intraperitoneal administration of Tamoxifen (40 mg/kg) for 5 consecutive days. The respective control alphaMyHC-MCM animals were equally treated.
Project description: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.
Project description: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. Experiment Overall Design: Comparison of muscle gene expression in 5 mice with postdevelopmental myostatin knockout and 5 control mice
Project description:Because myostatin normally limits skeletal muscle growth, there is an extensive effort to develop myostatin inhibitors for clinical use. One potential concern is that in patients with muscle degenerative diseases, inducing hypertrophy may increase stress on dystrophic fibers. Here, we show that blocking the myostatin pathway in dysferlin mutant mice results in early improvement in histopathology but ultimately accelerates muscle degeneration. Hence, benefits of this approach should be weighed against these potential detrimental effects.
Project description: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. 12 samples, 6 from sedentary mice and 6 from active (wheel running) mice. 3 control and 3 myostatin-deficient mice within each activity level.
Project description:Myostatin (GDF8) is a member of the TGF-beta family of proteins which is predominantly expressed in skeletal muscle and acts as a negative regulator of muscle mass. Inhibition of myostatin leads to muscle hypertrophy and has been shown to mitigate insulin resistance in mouse models of type 2 diabetes, although the mechanisms underlying this effect are unclear. We found that myostatin inhibition by AAV-mediated overexpression of the myostatin propeptide improves skeletal muscle insulin sensitivity in mice made insulin-resistant by high fat diet feeding. To gain insight into potential gene expression changes responsible for this effect, we performed microarray analysis on skeletal muscle samples from high fat diet-fed mice with and without myostatin inhibition.
Project description:Because myostatin normally limits skeletal muscle growth, there is an extensive effort to develop myostatin inhibitors for clinical use. One potential concern is that in patients with muscle degenerative diseases, inducing hypertrophy may increase stress on dystrophic fibers. Here, we show that blocking the myostatin pathway in dysferlin mutant mice results in early improvement in histopathology but ultimately accelerates muscle degeneration. Hence, benefits of this approach should be weighed against these potential detrimental effects. Affymetrix Mouse Exon 1.0 ST arrays were hybridized in three biologically independent experiments with RNA from quadriceps muscles of wt, Dysf-/-, F66, F66;Dysf-/- mice, and ACVR2B/Fc-injected wt and Dysf-/- mice at the age of 10 weeks (3 duplicates in 6 different groups, 18 samples).
Project description: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.