Abstract
The aim of this study was to assess the response of key mTORC1 substrates to a bout of contractile stimuli under different times of functional unloading. Functional unloading of hind-limb muscles was carried out by the method of antiorthostatic suspension. Twenty-eight Wistar rats were divided into four groups: control, and hindlimb suspension for 1, 3, and 7 days. After hindlimb suspension, isolated soleus muscles of rats were subjected to a bout of ex vivo eccentric contractions. The contents of phosphorylated forms of p70s6k and 4E-BP1 were then determined using western blotting. It was found that an eccentric load resulted in a significant increase in p70s6k phosphorylation and reduced 4E-BP1 phosphorylation both in control and suspended rats, but in the case of suspension the response was dramatically reduced. Thus, it can be concluded that a bout of eccentric contractions of isolated rat soleus muscle during functional unloading causes a weaker activation of the Akt-mTORC1-p70s6k signaling pathway compared with the control. This may indicate that it is important to maintain muscle tone for a more efficient muscle perception of an external mechanical signal and subsequent activation of anabolic signaling pathways.
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Abbreviations
- p70s6k, p70:
-
ribosomal protein S6 kinase
- 4EBP1:
-
eukaryotic translation initiation factor 4E-binding protein
- EC:
-
eccentric contractions
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Original Russian Text © T.M. Mirzoev, S.A. Tyganov, I.O. Petrova, B.S. Shenkman, 2016, published in Biofizika, 2016, Vol. 61, No. 5, pp. 979–985.
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Mirzoev, T.M., Tyganov, S.A., Petrova, I.O. et al. The realization of a mechanical signal during gravitational unloading: The response of mTORC1 targets to eccentric contractions. BIOPHYSICS 61, 779–784 (2016). https://doi.org/10.1134/S0006350916050213
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DOI: https://doi.org/10.1134/S0006350916050213