Fig. 1

mTOR is activated in aged, fasted Myf5/Fktn KO muscle. a Western blot analysis of solubilized protein from the hind limb muscle of Myf5/Fktn LC and KO mice. b Quantification of Akt phosphorylation at T308 and S473, mTOR phosphorylation at S2448, S6 phosphorylation at S235/236, relative to total Akt, mTOR, and S6 protein, respectively, as a measure of protein activation. mTOR phosphorylation at S2448 normalized to total mTOR is significantly increased in KO muscle. Two-tailed Student’s t test; *p < 0.05. c Representative images of iliopsoas muscle from aged LC or KO mice. H&E staining and dystrophin (red), ColVI (green), and DAPI (blue) immunofluorescence are shown. Scale bar 100 μm. (d, Left) Quantification of ColVI in iliopsoas of aged mice reveals significantly increased collagen content in KO muscle. Two-tailed Student’s t test; *p < 0.05. (d, Right) Total S6 protein correlates with ColVI quantity in KO muscle (Pearson r = 0.8147; p = 0.0256). n = 8 Myf5/Fktn LC and 8 Myf5/Fktn KO mice (n = 7 per group for ColVI analysis due to tissue artifacts)