Structural basis of stress concentration in the cytoskeleton

Professor Y.C. Fung has shown that living tissues remodel extensively in response to mechanical forces such as blood pressure variations. At the cellular level, those mechanical perturbations must be perceived by individual cells. However, mechanisms of mechanochemical transduction in living cells remain a central challenge to cell biologists. Contrary to predictions by existing models of living cells, we reported previously that a local stress, applied via integrin receptors, is propagated to remote sites in the cytoplasm and is concentrated at discrete foci. Here we report that these foci of strains and stresses in the cytoplasm correspond to local peak deformation or local buckling of microtubules and are near the actin bundles of the cell. Multiple images at different z heights demonstrated more foci of concentrated displacements in the middle of the cell than at the apex or at the cell base. Together with previously published work, these findings underscore the importance of tensed bundled filamentous actin in intracellular mechanical stress distribution and signaling.