Contribution of cellular contractility to spatial and temporal variations in cellular stiffness

Abstract

Scanning probe microscopy and immunofluorescence observations indicated that cellular stiffness was attributed to a contractile network structure consisting of stress fibers. We measured temporal variations in cellular stiffness when cellular contractility was regulated by dosing with lysophosphatidic acid or Y-27632. This experiment reveals a clear relation between cellular stiffness and contractility: Increases in contractility cause cells to stiffen. On the other hand, decreases in contractility reduce cellular stiffness. In both cases, not only the stiffness of the stress fibers but also that of the whole of the cell varies. Immunofluorescence observations of myosin II and vinculin indicated that the stiffness variations induced by the regulation of cellular contractility were mainly due to rearrangements of the contractile actin network on the dorsal surface. Taken together, our findings provide evidence that the actin cytoskeletal network and its contractility features provide and modulate the mechanical stability of adherent cells.

Force measurements with the atomic force microscope: Technique, interpretation and applications

“…Experiments concerned changes in cell stiffness upon increasing Ca 2+ concentration [939,940] or the cellular contractility [941]. Also, the effect of cell differentiation [942], cell division [943], shear stress [917,944], culture time [307], and cell spreading [945] has been studied.…”

“…Results for the lactic acid bacteria could be explained on the basis of the different constituents of the cell surfaces (S-layer proteins, polysaccharides, lipoteichoic acids) present in the different strains. For more detailed understanding of the mechanical properties of cells, force volume imaging has been combined with chemical modification of different components of the cytoskeleton, like actin [941,1208,1211,1212], vinculin [1161,1213], actomyosin [1214], and microtubules [941,1215].…”

Diphosphorylation of the myosin regulatory light chain enhances the tension acting on stress fibers in fibroblasts

“…To measure the contractile force in a single cell, we used a mechanical-scanning probe microscope (M-SPM), which can visualize the spatial distribution of stiffness reflected by the tension in the stress fibers in a cell (Nagayama et al, 2004). By using the M-SPM, we were 4 successful in observing a dramatic change in cellular stiffness during cell migration (Nagayama et al, 2001) and in discovering tensional homeostasis against external deformation (Mizutani et al, 2004a).…”

“…By using the M-SPM, we were 4 successful in observing a dramatic change in cellular stiffness during cell migration (Nagayama et al, 2001) and in discovering tensional homeostasis against external deformation (Mizutani et al, 2004a). Our previous work showed that cellular stiffness increased on stimulation with lysophosphatidic acid (LPA) (Nagayama et al, 2004) that is a RhoA activator. Taking these findings into consideration, we concluded that the phosphorylation of MRLC increases cellular stiffness.…”

Development of a device to stretch tissue-like materials and to measure their mechanical properties by scanning probe microscopy

“…We modified the M-SPM to enable visualization of topography and local stiffness in living cells in order to investigate the cellular stiffness and mechanical response of the cells toward external loading force using force mapping mode under liquid conditions [10,11]. In order to measure the mechanical properties of a tissue-like material under an external loading force, we developed wide-range scanning probe microscopy (WR-SPM), which is a modification of a commercial M-SPM [12].…”