Specific Mechanical and Structural Responses of Cortical and Cytosolic Cytoskeleton in Living Adherent Cells

We studied the relation between actin structural changes and cytoskeleton mechanical properties in living adherent epithelial alveolar cells, before and during actin depolymerization. The mechanical response of adherent alveolar epithelial cells was measured using magnetic twisting cytometry and a two-component model representing the cortical and the cytosolic elastic components at equilibrium. Chemiluminescent staining of the actin cytoskeleton was performed in the same living cells to estimate the intracellular actin density distribution for each cytoskeleton component. We found that (i) cytoskeleton alterations induced by actin depolymerization differed between the cortical and cytosolic cytoskeleton components (e.g., -30% and -49%, respectively, at a stress of 31 Pa) and that (ii) the concomitant change in actin distribution was also different (e.g., actin volume decrease was -7% and -19% for the cortical and cytosolic components, respectively).