Abstract
Here, we observed fibroblasts seeded onto a glass substrate on which Forster/fluorescence resonance energy transfer (FRET)-based tension sensors were immobilized. While the observation, actin or microtubule depolymerizers (cytochalasin D or nocodazole, respectively) were added to the culture medium to induce cell deformation. Cells began contracting within 5 min after the addition of cytochalasin D and assumed a round shape. During this contraction process, cell protrusions gradually shrank and disappeared. At the tip of these protrusions, there appeared dash-like areas with a low FRET index, indicating strong tension, and these areas disappeared within 90 min. These results suggest that the FRET-based tension sensor enabled the real-time visualization of tension induced by actin cytoskeletal reorganization and focal adhesion formation This is also supported by the observation of cells treated with nocodazole, which depolymerizes microtubules to increase tension across actin fibers. The distribution of areas with a low FRET index changed by the nocodazole treatment. The FRET-based tension sensor is useful to evaluate mechanical interactions between cells and materials.
