Gene expression profiling of skeletal muscles treated with a soluble activin type IIB receptor

Program in Genomics, Division of Genetics, Children's Hospital Boston, Harvard Medical School, Boston, USA.
Physiological Genomics (Impact Factor: 2.37). 04/2011; 43(8):398-407. DOI: 10.1152/physiolgenomics.00223.2010
Source: PubMed

ABSTRACT Inhibition of the myostatin signaling pathway is emerging as a promising therapeutic means to treat muscle wasting and degenerative disorders. Activin type IIB receptor (ActRIIB) is the putative myostatin receptor, and a soluble activin receptor (ActRIIB-Fc) has been demonstrated to potently inhibit a subset of transforming growth factor (TGF)-β family members including myostatin. To determine reliable and valid biomarkers for ActRIIB-Fc treatment, we assessed gene expression profiles for quadriceps muscles from mice treated with ActRIIB-Fc compared with mice genetically lacking myostatin and control mice. Expression of 134 genes was significantly altered in mice treated with ActRIIB-Fc over a 2-wk period relative to control mice (fold change > 1.5, P < 0.001), whereas the number of significantly altered genes in mice treated for 2 days was 38, demonstrating a time-dependent response to ActRIIB-Fc in overall muscle gene expression. The number of significantly altered genes in Mstn(-/-) mice relative to control mice was substantially higher (360), but for most of these genes the expression levels in the 2-wk treated mice were closer to the levels in the Mstn(-/-) mice than in control mice (P < 10⁻³⁰). Expression levels of 30 selected genes were further validated with quantitative real-time polymerase chain reaction (qPCR), and a correlation of ≥ 0.89 was observed between the fold changes from the microarray analysis and the qPCR analysis. These data suggest that treatment with ActRIIB-Fc results in overlapping but distinct gene expression signatures compared with myostatin genetic mutation. Differentially expressed genes identified in this study can be used as potential biomarkers for ActRIIB-Fc treatment, which is currently in clinical trials as a therapeutic agent for muscle wasting and degenerative disorders.

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Available from: Fedik Rahimov, Sep 18, 2014
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    • "Recent evidence showed that it also increases muscle mass after a single-dose treatment in humans (Attie et al., 2013), supporting its possible therapeutic use for some neuromuscular diseases and muscle wasting. However, there is also some evidence that it can have side-effects, such as decreased muscle oxidative capacity (Amthor et al., 2007; Hulmi et al., 2013a; Matsakas et al., 2010, 2012; Ploquin et al., 2012; Rahimov et al., 2011; Relizani et al., 2014). On the other hand, muscular dystrophy is in itself associated with a decrease in oxidative capacity and gene expression in skeletal muscle (Timmons et al., 2005). "
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    ABSTRACT: Duchenne Muscular Dystrophy is characterized by muscle wasting and decreased aerobic metabolism. Exercise and blocking of myostatin/activin signaling may independently or combined counteract muscle wasting and dystrophies. The effects of myostatin/activin blocking using soluble activin receptor-Fc (sActRIIB-Fc) administration and wheel running were tested alone or in combination for seven weeks in dystrophic mdx mice. Expression microarray analysis revealed decreased aerobic metabolism in the gastrocnemius muscle of mdx mice compared to healthy mice. This was not due to reduced home-cage physical activity, and was further downregulated upon sActRIIB-Fc treatment in enlarged muscles. However, exercise activated pathways of aerobic metabolism and counteracted the negative effects of sActRIIB-Fc. Exercise and sActRIIB-Fc synergistically increased expression of major urinary protein, but exercise blocked sActRIIB-Fc induced phosphorylation of STAT5 in gastrocnemius muscle. In conclusion, exercise alone or in combination with myostatin/activin blocking corrects aerobic gene expression profiles of dystrophic muscle towards healthy wild type mice profiles.
    Molecular and Cellular Endocrinology 10/2014; 399(C). DOI:10.1016/j.mce.2014.10.001 · 4.41 Impact Factor
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    ABSTRACT: Acute quadriplegic myopathy (AQM) or critical illness myopathy (CIM) is frequently observed in intensive care unit (ICU) patients. To elucidate duration-dependent effects of the ICU intervention on molecular and functional networks that control the muscle wasting and weakness associated with AQM, a gene expression profile was analyzed at time points varying from 6 hours to 14 days in a unique experimental rat model mimicking ICU conditions, i.e., post-synaptically paralyzed, mechanically ventilated and extensively monitored animals. During the observation period, 1583 genes were significantly up- or down-regulated by factors of two or greater. A significant temporal gene expression pattern was constructed at short (6 h-4 days), intermediate (5-8 days) and long (9-14 days) durations. A striking early and maintained up-regulation (6 h-14d) of muscle atrogenes (muscle ring-finger 1/tripartite motif-containing 63 and F-box protein 32/atrogin-1) was observed, followed by an up-regulation of the proteolytic systems at intermediate and long durations (5-14d). Oxidative stress response genes and genes that take part in amino acid catabolism, cell cycle arrest, apoptosis, muscle development, and protein synthesis together with myogenic factors were significantly up-regulated from 5 to 14 days. At 9-14 d, genes involved in immune response and the caspase cascade were up-regulated. At 5-14d, genes related to contractile (myosin heavy chain and myosin binding protein C), regulatory (troponin, tropomyosin), developmental, caveolin-3, extracellular matrix, glycolysis/gluconeogenesis, cytoskeleton/sarcomere regulation and mitochondrial proteins were down-regulated. An activation of genes related to muscle growth and new muscle fiber formation (increase of myogenic factors and JunB and down-regulation of myostatin) and up-regulation of genes that code protein synthesis and translation factors were found from 5 to 14 days. Novel temporal patterns of gene expression have been uncovered, suggesting a unique, coordinated and highly complex mechanism underlying the muscle wasting associated with AQM in ICU patients and providing new target genes and avenues for intervention studies.
    BMC Genomics 12/2011; 12(1):602. DOI:10.1186/1471-2164-12-602 · 3.99 Impact Factor
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    ABSTRACT: Loss of muscle mass and function occurs in various diseases. Myostatin blocking can attenuate muscle loss, but downstream signaling is not well known. Therefore, to elucidate associated signaling pathways, we used the soluble activin receptor IIb (sActRIIB-Fc) to block myostatin and activins in mice. Within two weeks, the treatment rapidly increased muscle size as expected, but decreased capillary density per area. sActRIIB-Fc increased muscle protein synthesis 1-2 days after the treatment correlating with enhanced mTORC1 signaling (phosphorylated rpS6 and S6K1, r=0.8). Concurrently, increased REDD1 and eIF2Bε protein contents and phosphorylation of 4EBP1 and AMPK was observed. In contrast, proangiogenic MAPK signaling and VEGF-A protein decreased. Hippo signaling is recently characterized regulator of organ size and an important regulator of myogenesis in vitro. The phosphorylation of YAP (Yes-Associated-Protein), a readout of activated Hippo signaling, increased after short and longer term myostatin and activin blocking and in exercised muscle. Moreover, dystrophic mdx mice had elevated phosphorylated and especially total YAP protein content. These results show that the blocking of myostatin and activins induce rapid skeletal muscle growth. This is associated with increased protein synthesis and mTORC1 signaling, but decreased capillary density and proangiogenic signaling. It is also shown for the first time that Hippo signaling is activated in skeletal muscle after myostatin blocking and exercise and also in dystrophic muscle. This suggests that Hippo signaling may have a role in skeletal muscle in various circumstances.
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