Cell‐surface contacts determine volume and mechanical properties of human embryonic kidney 293 T cells

Abstract

Alterations in the organization of the cytoskeleton precede the escape of adherent cells from the framework of cell-cell and cell-matrix interactions into suspension.With cytoskeletal dynamics being linked to cell mechanical properties, many studies elucidated this relationship under either native adherent or suspended conditions. In contrast, tethered cells that mimic the transition between both states have not been the focus of recent research. Using human embryonic kidney 293 T cells we investigated all three conditions in the light of alterations in cellular shape, volume, as well as mechanical properties and relate these findings to the level, structure, and intracellular localization of filamentous actin (F-actin). For cells adhered to a substrate, our data shows that seeding density affects cell size but does not alter their elastic properties. Removing surface contacts leads to cell stiffening that is accompanied by changes in cell shape, and a reduction in cellular volume but no alterations in F-actin density. Instead, we observe changes in the organization of F-actin indicated by the appearance of blebs in the semi-adherent state. In summary, our work reveals an interplay between molecular and mechanical alterations when cells detach from a surface that is mainly dominated by cell morphology.

Dynamic mechanisms for membrane skeleton transitions

“…Cells in suspension and adhered cells have different mechanical properties ( 37 ). Therefore, we next investigated how the actin-spectrin meshwork differs in cell-like geometries in suspension, like red blood cells, and cells with adhesions, such as fibroblasts.…”

“…These mechanisms are difficult to examine in experiments in vivo due to technical restrictions. Finally, to test the generality of our work on a membrane patch, we modeled suspended and adhered cells, which have different mechanical properties ( 37 ). Furthermore, we showed how these cells can conserve their shape despite the continuous turnover of spectrin and stochastic dynamics of myosin, which are necessary for responding to imposed stresses.…”