Cell morphogenesis via self-propelled treadmilling actin waves
Description
Actin dynamics mediate cell morphogenesis and motility. Actin filaments polymerize outward at cell protrusions such as the leading edge of migrating cells, thereby pushing the membrane to protrude. The current paradigm explains that actin dynamics are regulated by biochemical signaling pathways. However, it is unclear how cells can form protrusions even without local signaling cues. We found that arrays of treadmilling actin filaments emerge widely in migrating cells and translocate in the direction of polymerization as actin waves. Their arrival at the cell periphery pushed the plasma membrane to protrude. Furthermore, they accumulate at protrusions without local signaling cues, similar to self-propelled particles colliding with a boundary. This leads to further expansion of the protrusions, promoting cell polarization and migration. We propose that the self-propelled actin waves drive robust formation of protrusions during spontaneous cell morphogenesis, through a positive feedback interaction with actin-mediated protrusion and effective lateral inhibition.