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Abstract:
Membrane waves propagating along the cell circumference in a top down view have been observed with several eukaryotic cells (Döbereiner et al 2006 Phys. Rev. Lett. 97 10; Machacek and Danuser 2006 Biophys. J. 90 1439–52). We present a mathematical model reproducing these traveling membrane undulations during lamellipodial motility of cells on flat substrates. The model describes the interplay of pushing forces exerted by actin polymerization on the membrane, pulling forces of attached actin filaments on the cell edge, contractile forces powered by molecular motors across the actin gel and resisting membrane tension. The actin filament network in the bulk of lamellipodia obeys gel flow equations. We investigated in particular the dependence of wave properties on gel parameters and found that inhibition of myosin motors abolishes waves in some cells but not in others in agreement with experimental observations. The model provides a unifying mechanism explaining the dynamics of actin-based motility in a variety of systems.
