Figure 1From: Differential response of skeletal muscles to mTORC1 signaling during atrophy and hypertrophyAcute perturbation of mTORC1 affects muscle fiber size. Soleus muscle was electroporated with plasmids encoding shRNA directed to transcripts encoding CD4 (Cd4), raptor (Rptor) or TSC2 (Tsc2). Plasmids encoding NLS-GFP were co-electroporated to label transfected fibers. After four to six weeks, muscle fiber size was determined by staining mid-belly cross-sections with Alexa-594-labeled wheat germ agglutinin (red). Transfected muscle fibers were identified by the expression of nuclear-localized GFP (green; white asterisks). The experimental paradigms used were innervated muscle (A, B), reinnervated muscle after nerve crush (C, D) and denervated muscle (E, F). Quantifications (B, D, F) of cross-sectional area (CSA) of muscle fibers in each paradigm are given relative to CSA of neighboring, GFP-negative, non-electroporated fibers. Electroporation of plasmids encoding shRNA to Cd4 served as control. Scale bars (A, C, E) = 50 μm. Bars (B, D, F) represent mean ± SEM (N ≥3 mice and N ≥200 fibers were measured in each). In case of innervated muscles treated with shRNA to Tsc2 and with rapamycin (Tsc2 + Rapa) and denervated muscles electroporated with shRNA to Cd4, data represent mean ± SD (N = 2). P-values are ***P <0.001; **P <0.01; *P <0.05. Unless otherwise indicated, significance was determined compared to the control (shRNA to Cd4).Back to article page