%0 Journal Article
%T Akt (protein kinase B) isoform phosphorylation and signaling downstream of mTOR (mammalian target of rapamycin) in denervated atrophic and hypertrophic mouse skeletal muscle
%A Marlene Norrby
%A Kim Evertsson
%A Ann-Kristin Fj£¿llstr£¿m
%A Anna Svensson
%A Sven T£¿gerud
%J Journal of Molecular Signaling
%D 2012
%I Ubiquity Press
%R 10.1186/1750-2187-7-7
%X In denervated hypertrophic muscle expression of total Akt1, Akt2, GSK-3beta, p70S6K1 and rpS6 proteins increased 2¨C10 fold whereas total 4EBP1 protein remained unaltered. In denervated atrophic muscle Akt1 and Akt2 total protein increased 2¨C16 fold. A small increase in expression of total rpS6 protein was also observed with no apparent changes in levels of total GSK-3beta, 4EBP1 or p70S6K1 proteins. The level of phosphorylated proteins increased 3¨C13 fold for all the proteins in hypertrophic denervated muscle. No significant changes in phosphorylated Akt1 or GSK-3beta were detected in atrophic denervated muscle. The phosphorylation levels of Akt2, 4EBP1, p70S6K1 and rpS6 were increased 2¨C18 fold in atrophic denervated muscle.The results are consistent with increased Akt/mTOR signaling in hypertrophic skeletal muscle. Decreased levels of phosphorylated Akt (S473/S474) were not observed in denervated atrophic muscle and results downstream of mTOR indicate increased protein synthesis in denervated atrophic anterior tibial muscle as well as in denervated hypertrophic hemidiaphragm muscle. Increased protein degradation, rather than decreased protein synthesis, is likely to be responsible for the loss of muscle mass in denervated atrophic muscles.
%K Akt
%K GSK-3¦Â
%K 4EBP1
%K p70S6K1
%K rpS6
%K Denervation
%K Skeletal muscle
%K Mouse
%K Phosphorylation
%U http://www.jmolecularsignaling.com/content/7/1/7/abstract