Stick–slip model for actin-driven cell protrusions, cell polarization, and crawling

Significance
Spreading and crawling cells display rich nonlinear dynamics, which include periodic phases of growth and retraction of cellular protrusion, traveling waves along the cell edges, and spontaneous cell polarization and crawling. Using a theoretical model combining the mechanosensitivity of cell–substrate adhesion kinetics and linear cell viscoelastic mechanics, I show that the force-sensitive unbinding of adhesion bonds leads to stick–slip dynamics that recapitulate these dynamics’ features. The model also highlights the role of the cell membrane tension in controlling spontaneous symmetry breaking and the transition between spreading and crawling. This suggests that purely mechanical feedback loops, in addition to those involved in biochemical signaling networks, are key regulators of cell crawling.