Characterization of cytoskeleton mechanical properties and 3D-actin structure in twisted adherent epithelial cells.

Evaluation of the cytoskeleton mechanical properties requires specific micromanipulation techniques such as the magnetic twisting cytometry technique, in which microbeads are specifically linked to the cytoskeleton via transmembrane receptors. The aim of the study was to assess the structural relationship between the bead and the cytoskeleton structure. The spatial arrangement of the CSK network was therefore studied in fixed cells probed by beads and stained for F-actin by rhodamined phalloïdine. The spatial character of the actin CSK network, both in the bead neighborhood and at the cell scale, could then be studied for various degrees of fluorescent intensity from 3D-images of the actin structure, reconstructed from z-stack views obtained by confocal microscopy. Results show the feasibility of the staining/reconstruction technique which allows to reveal the three-dimensional organization of the cytoskeleton structure including an internal cytosolic structure with a high fluorescent F-actin intensity, and a sub-membranous cortical structure with a low fluorescent F-actin intensity.