An Anabolic Signaling Response of Rat Soleus Muscle to Eccentric Contractions Following Hindlimb Unloading: A Potential Role of Stretch-Activated Ion Channels

• Published in: International journal of molecular sciences 2019-03, Vol.20 (5), p.1165
• Main Authors: Tyganov, Sergey, Mirzoev, Timur, Shenkman, Boris
• Format: Article
• Language: English
• Subjects: anabolic signaling; eccentric contractions; Extracellular signal-regulated kinase; Glycogen; Glycogen synthase kinase 3; Glycogens; hindlimb unloading; Initiation factor eIF-2; Ion channels; Kinases; Muscles; Musculoskeletal system; Phosphorylation; Protein biosynthesis; Protein synthesis; Proteins; Ribosomal protein S6; Ribosomal protein S6 kinase; Signal transduction; Soleus muscle; stretch-activated channels
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms20051165

Mechanisms that convert a mechanical signal into a biochemical response in an atrophied skeletal muscle remain poorly understood. The aims of the study were to evaluate a temporal response of anabolic signaling and protein synthesis (PS) to eccentric contractions (EC) in rat soleus during hindlimb unloading (HU); and to assess a possible role of stretch-activated ion channels (SAC) in the propagation of a mechanical signal to mTORC1 following HU. Following HU, an isolated soleus was subjected to EC. Upon completion of EC, muscles were collected for western blot analyses to determine the content/phosphorylation of the key anabolic markers. We found that a degree of EC-induced p70S6K phosphorylation and the rate of PS in the soleus of 3- and 7-day unloaded rats was significantly less than that in control. A decrease in EC-induced phosphorylation of p70S6K, RPS6 and PS in the 7-day unloaded soleus treated with SAC inhibitor did not differ from that of the 7-day unloaded soleus without SAC blockade. The results of the study suggest that (i) HU results in a blunted anabolic response to a bout of EC, (ii) attenuation of mTORC1-signaling and PS in response to EC in unloaded soleus may be associated with inactivation of SAC.