Figure 6. AMPK activation leads to maturation of contractile actomyosin bundles.
(A) U2OS cells grown on glass and treated with AMPK activator AICAR exhibited short dorsal stress fibers. Ventral stress fibers were typically localized close to cell edges, indicating early maturation of the contractile actomyosin bundles compared to control cells. (B) Western blot analysis of the corresponding samples showed elevation of Ser239-P-VASP in AICAR treated cells. A representative Western blot and quantification of three separate experiments (mean +/- SEM) are shown. (C) Activation of AMPK bypasses the need for stiff substrata in ventral stress fiber formation. U2OS cells grown on soft (0.5 kPa) matrix do not typically contain contractile ventral stress fibers, but their formation on soft matrix can be induced by AICAR. (D) Quantification of the amount of cells (%) containing ventral stress fibers. For each condition, 50–70 cells were analysed and the data are presented as mean +/- SEM.