On the move

Many cell types migrate through surrounding tissue: nerve cells reaching for their final destination, immune cells on the prowl for intruding pathogens, fibroblasts called in to close wounds and stray cancer cells that have escaped the confines of the primary tumor.

Cells on the move reach forward with lamellipodia and filopodia, cytoplasmic sheets and rods supported by branched networks or tight bundles of actin filaments, which are constantly remodeled to push forward. The Arp2/3 complex, which localizes to lamellipodia, was thought to help build the web of actin filaments that shapes lamellipodia by initiating the branching process. But it had been unclear whether Arp2/3 is actually required for lamellipodia formation and how it would affect cell motility.

“Our work demonstrates that the Arp2/3 complex plays a critical role in the formation of the branched array of actin fibers that forms the structural backbone of lamellipodia,” says Stowers Investigator Rong Li, PhD, who led the study. “Cells without functional lamellipodia are still highly motile but lose their ability to stay on track.”

Their study provides new insight into cell motility, a complex and integrated process that, when gone awry, can lead to various disease conditions such as cancer metastasis, birth defects, cardiovascular disease and compromised immune function.

The study was published in the April 9, 2012, online issue of the Journal of Cell Biology.