Abstract
The purpose of the study was to assess the rate of protein synthesis (PS) and elucidate signalling pathways regulating PS in mouse soleus (Sol) and tibialis anterior (TA) muscles following chronic hypergravity (30-day centrifugation at 2G). The content of the key signalling proteins of the various anabolic signalling pathways was determined by Western-blotting. The rate of PS was assessed using in-vivo SUnSET technique. An exposure to 2G centrifugation did not induce any significant changes in the rate of PS as well as phosphorylation status of the key anabolic markers (AKT, p70s6k, 4E-BP1, GSK-3beta, eEF2) in Sol. On the contrary, a significant 55% increase in PS (p < 0.05) was found in TA. The cause of such a rise in PS could be associated with an increase in AKT (+72%, p < 0.05), GSK-3beta (+60%, p < 0.05) and p70s6k (+40%, p < 0.05) phosphorylation, as well as a decrease in eEF2 phosphorylation (−46%, p < 0.05) as compared to control values. Thus, the results of our study indicate that 30-day 2G centrifugation induces a distinct anabolic response in mouse Sol and TA muscles. The activation of the PS rate in TA could be linked to an up-regulation of both mTORC1-dependent and mTORC1-independent signalling pathways.
Highlights
Translation and can be modified following altered gravitational environment is eukaryotic elongation factor 2. eEF2 is able to inhibit translation elongation being phosphorylated on the Thr[56] residue by eEF2 kinase[20]
Here we report, for the first time, the effect of 30-day 2G-centrufugation on the key markers of signalling pathways involved in the regulation of mRNA translation in murine Sol and tibialis anterior (TA) muscles
We hypothesized that an exposure to chronic hypergravity would lead to alternations in phosphorylation of anabolic signalling molecules resulting in an increase in protein synthesis (PS) and subsequent hypertrophy of skeletal muscles
Summary
Translation and can be modified following altered gravitational environment is eukaryotic elongation factor 2 (eEF2). eEF2 is able to inhibit translation elongation being phosphorylated on the Thr[56] residue by eEF2 kinase[20]. Translation and can be modified following altered gravitational environment is eukaryotic elongation factor 2 (eEF2). To our knowledge, there is a lack of data concerning the activity of anabolic signalling pathways as well as the rate of PS in rodent skeletal muscle following an exposure to chronic hypergravity. The purpose of the present study was to measure the rate of PS and the activity of the key markers of various anabolic signalling pathways in mouse Sol and tibialis anterior (TA) following 30-day centrifugation at 2G. We hypothesized that an exposure to chronic hypergravity would activate anabolic signalling pathways with subsequent rise in PS in mouse skeletal muscles. We aimed to compare anabolic signalling responses in two hindlimb muscles, i.e. dorsal extensor (Sol) and dorsal flexor (TA) after chronic 2G hypergravity
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