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

Caption: Quantitative model of Golgi self-organisation between a source (the endoplasmic reticulum – E.R. – left, blue) and an exit (e.g. the Trans Golgi Network – right, green). The source emits immature vesicles (blue). Larger compartments are formed through homotypic fusion and vesicular budding. A steady-state is obtained when the in-flux is balanced by the out-flux.

Cell crawling requires the generation of intracellular forces by the cytoskeleton and their transmission to an extracellular substrate through specific adhesion molecules. Crawling cells show many features of excitable systems, such as spontaneous symmetry breaking and crawling in the absence of external cues, and periodic and propagating waves of activity. We use quantitative modelling of cellular traction force to show that many nonlinear dynamical patterns observed in spreading and crawling cells, such as spontaneous symmetry breaking and motion and periodic and travelling waves can result from the stick-slip dynamics of mechano-sensitive cell-substrate adhesion. The model also highlights the role of membrane tension in providing the long-range mechanical communication across the cell.