Figure 7. GYS1 mediates glycogen accumulation during hypoxia.

c2c12 myoblasts were transfected with siRNA against mouse GYS1 (GYS1), siRNA containing an irrelevant sequence (Control). 24 hours after transfections cells were cultured for 12 hours under 21% (Nx) or 1% oxygen (Hx), then each sample was split and processed to determine GYS1 mRNA (A), protein levels (B) or glycogen content (C). The experiment was repeated twice with similar results. GYS1 mRNA levels (D) and glycogen content (E) were determined in Hepa C1 cells stably expressing a shRNA directed to GYS1 or a control shRNA. Results from four independent experiments are represented. *, p<0.05; **, p<0.01; as compared to samples expressing control shRNA and exposed to normoxia. (F) c2c12 myotubes were infected with AdGYS1 or Adβ-Gal. 24 hours after infection cells were processed for glycogen content determination. Parallel cultures were exposed to normoxia or hypoxia for 12 hours and processed for glycogen determination. Graphs represent the mean of duplicated measures and error bars the range, the experiment was repeated twice with similar results.