How do cells crawl?

“The amoeboid movement by which many types of cell crawl across surfaces has fascinated scientists ever since it was first observed using the earliest microscopes. Until recently, it has remained mysterious how cells extend the thin protrusion, known as a lamellipod, that enables them to move forward. In the past decade, however, extensive experimental work has shown that amoeboid motility is associated with the regulated polymerisation of branched actin filaments within the lamellipod. Now, researchers at the London Centre for Nanotechnology and in Cambridge have developed a physical model that explains how this polymerisation generates motion. In a paper published in Proceedings of the National Academy of Sciences, Christian Schreiber (Cambridge University), Murray Stewart (MRC Laboratory of Molecular Biology) and Tom Duke (LCN) propose that the key point is that the packing efficiency of randomly oriented rod-like filaments decreases rapidly as the filaments get longer.” More…