Protrusive Forces Generated by Dendritic Actin Networks During Cell Crawling

Abstract

Cell protrusions during crawling motility involve growth of a dendritic actin network at the leading edge. Numerous studies over the last several decades have revealed the identity of key proteins involved in dendritic actin networks and elucidated how these proteins interact with each other during network assembly and growth, enabling reconstitution in vitro. While it is clear that growth of these networks can displace loads, the mechanism and dynamics of force generation continue to be a subject of investigation. In this chapter we describe current theories for the underlying mechanism of force generation by dendritic actin networks and discuss experimental measurements that quantify the magnitude and dynamics of the forces. Reconstitution studies have played a central role in measurements of force generation by dendritic actin networks and demonstrated how the combination of a small set of proteins leads to complex history dependent growth. Measurements of protrusion in crawling cells are now beginning to test the predictions of these reconstitution studies. We conclude by discussing how dendritic actin network growth can be integrated into an overall understanding of cell protrusions during crawling motility.