Encapsulated actomyosin patterns drive cell-like membrane shape changes

Cell shape changes from locomotion to cytokinesis are, to a large extent, driven by myosin-driven remodeling of cortical actin patterns. Passive crosslinkers such as alpha-actinin and fascin as well as actin nucleator Arp2/3 complex largely determine actin network architecture and, consequently, membrane shape changes. Here we reconstitute actomyosin networks inside cell-sized lipid bilayer vesicles and show that depending on vesicle size and concentrations of alpha-actinin and fascin actomyosin networks assemble into ring and aster-like patterns. Anchoring actin to the membrane does not change actin network architecture yet exerts forces and deforms the membrane when assembled in the form of a contractile ring. In the presence of alpha-actinin and fascin, an Arp2/3 complex-mediated actomyosin cortex is shown to assemble a ring-like pattern at the equatorial cortex followed by myosin-driven clustering and consequently blebbing. An active gel theory unifies a model for the observed membrane shape changes induced by the contractile cortex.

Automated summary

Cell shape changes during locomotion and cytokinesis are primarily driven by myosin-induced remodeling of cortical actin patterns. The architecture of actin networks, which largely determines the shape of the membrane, is influenced by passive crosslinkers such as alpha-actinin and fascin, as well as the actin nucleator Arp2/3 complex. By reconstituting actomyosin networks in cell-sized lipid bilayer vesicles, the study shows that the size of the vesicle and the concentrations of alpha-actinin and fascin can lead to the assembly of different actomyosin patterns, such as rings and aster-like structures.