Interaction of fascin and protein kinase Cα: a novel intersection in cell adhesion and motility

Coordination of protrusive and contractile cell–matrix contacts is important for cell adhesion and migration, but the mechanisms involved are not well understood. We report an unexpected direct association between fascin, an actin‐bundling component of filopodia, microspikes and lamellipodial ribs, and protein kinase Cα (PKCα), a regulator of focal adhesions. The association is detectable by protein–protein binding in vitro , by coimmunoprecipitation from cell extracts, and in live cells as fluorescence resonance energy transfer detected by fluorescence imaging lifetime microscopy. The interaction is physiologically regulated by the extracellular matrix context of cells, depends on activation of PKCα and is mediated by the C1B domain of PKCα. Strikingly, a fascin mutant, fascin S39D, associates constitutively with PKCα. Through use of a newly developed set of membrane‐permeable peptides that separately inhibit either fascin/PKCα or fascin/actin binding, we have uncovered that specific blockade of the fascin/PKCα interaction increases cell migration on fibronectin in conjunction with increased fascin protrusions and remodeling of focal adhesions. These results identify the fascin–PKCα interaction as an important novel intersection in the regulation and networking of cell–matrix contacts.