Actin cortex rearrangement caused by coupling with the lipid bilayer-modeling considerations.

Studies of cell membrane fluctuations under micro rheological measurements suggest that coupling between the lipid bilayer and the actin cortex can affects viscoelastic behavior of the single cell membranes. Coupling induces anomalous nature of energy dissipation during rearrangement of both: the actin cortex and the lipid bilayer. The actin cortex ability to rearrange for various cell types: erythrocytes, Jurkat cells, fibroblasts, epithelial lung cells, and muscle cells based on experimental data for storage and loss moduli versus angular velocity are considered. The cortex of softer cells such as erythrocytes, Jurkat cells, and fibroblasts has the ability to rearrange at low angular velocities which is quantified by their rearrangement time and the average size of the cortex micro domains. The rearrangement time of the cortex for Jurkat cells and fibroblasts is at the order of magnitude higher than that for erythrocytes, i.e., 2.70-7.53 s. The average size of the cortex micro domains for erythrocytes varied from 3.0 to 5.3 μm, for Jurkat cells is ~0.20-0.22 μm and for fibroblasts is ~36 nm. Lower size of the micro domains and higher rearrangement time indicate the stiffer cortex structure. The cortex rearrangement for stiffer cells such as epithelial lung cells and muscle cells has never been observed.