Decisive role of mDia-family formins in cell cortex function of highly adherent cells.

Cortical formins, pivotal for the assembly of linear actin filaments beneath the membrane, exert only minor effects on unconfined cell migration of weakly and moderately adherent cells. However, their impact on migration and mechanostability of highly adherent cells remains poorly understood. Here, we demonstrate that loss of cortical actin filaments generated by the formins mDia1 and mDia3 drastically compromises cell migration and mechanics in highly adherent fibroblasts.

Electric Cell-Substrate Impedance Sensing as a Tool to Characterize Wound Healing Dynamics.

The electric cell-substrate impedance sensing (ECIS) is a well-established technique that allows for the real-time monitoring of cell cultures growing on gold-electrodes embedded in culture dishes. Its foundation lays on the insulating effect that cells present against the free-flow of electrons, as these passive electrical properties generate a characteristic complex impedance spectrum when a small-amplitude, non-invasive alternating current (AC) is provided through the electrodes, the living cells, and the culture media in the culture ware. In addition, it possesses the ability to create a wound that is highly confined to the electrode area by simply increasing the amplitude of the AC current in dependence of the pre-resistor strength for a defined pulse duration and at a specific frequency.

Prestress and Area Compressibility of Actin Cortices Determine the Viscoelastic Response of Living Cells.

Shape, dynamics, and viscoelastic properties of eukaryotic cells are primarily governed by a thin, reversibly cross-linked actomyosin cortex located directly beneath the plasma membrane. We obtain time-dependent rheological responses of fibroblasts and MDCK II cells from deformation-relaxation curves using an atomic force microscope to access the dependence of cortex fluidity on prestress. We introduce a viscoelastic model that treats the cell as a composite shell and assumes that relaxation of the cortex follows a power law giving access to cortical prestress, area-compressibility modulus, and the power law exponent (fluidity).