Cell Shape Changes Driven by Actomyosin Contractility

A change in cell shapes occurs in various physiological processes. For example, cells undergoing migration or apoptosis transiently form bulges on the membrane called blebs. It has been suggested that the formation and retraction of cell blebs are induced by osmotic pressure and locally weak coupling between the cell cortex and the membrane. To better understand an intrinsic mechanism for bleb formation, we developed an agent-based cell-like model by incorporating our well-established actomyosin network model with a cell membrane simplified into a triangulated mesh. The cortex is coupled to the membrane by allowing a fraction of cross-linkers to bind to the membrane. We identified parametric spaces for bleb formation consisting of myosin density, cross-linking density, and the strength of coupling between the cortex and membrane. We also observed other interesting cell shape changes, such as contractile ring formation, cortical flow, and significant membrane deformation. We verified our computational results by comparing them with in vitro experimental results obtained under similar conditions. Our results provide insights into understanding how cell blebs emerge in physiological processes as well as how cell shapes change due to actomyosin contractility in general.