Figure 1.

Inhibition of AKT promotes net nuclear accumulation of FOXO1–GFP under control conditions and completely blocks the dramatic IGF1-induced net nuclear efflux of FOXO1–GFP. A, representative fluorescent images of FOXO1–GFP in skeletal muscle fibers under different conditions. The first column shows the fiber under transmitted light conditions and the 10-μm scale bar that applies to all images in the figure. Each row shows the same fiber at different times (top labels) during the experiment and illustrates a different experimental condition (right side labels). Image intensity here and in Fig. 2 was decreased at later times to avoid pixel saturation in the nuclei of FOXO1–GFP in samples with AKT inhibition. Note that this has no effect on N/C values because it applies to the entire image. B, time course experiment analysis of FOXO1–GFP N/C levels (average of N/C values from images shown in A, plus others, normalized to the average N/C before compounds were added) in the presence or absence of select compounds. For this and all further time-course graphs, significance is denoted as follows: *, P < 0.05; **, P < 0.01. Red asterisks correspond to red symbols, and black asterisks correspond to black symbols. There were no added compounds in control (A, top row; B, solid black line). AKT inhibitor VIII was added at 15 min (A, second and fourth rows; B, dashed lines). IGF1 was added at 30 min (A, third and fourth rows; B, red lines). C, N/C (not normalized) at the 90-min time point for each condition. Significance is denoted as follows: *, P < 0.05; **, P < 0.02; ***, P < 0.01 for this and all further 90-min time point graphs.