Fascin is an actin filament bundling protein localized to lamellipodia and filopodia where it has important roles in cell motility. Regulation of fascin occurs through PKC-mediated phosphorylation of Ser-39 in the F-actin binding site. Cell permeant peptides that block PKC phosphorylation of Ser-39 increase cell migration, while peptides that block fascin binding to F-actin alter lamellipodial morphology and cause aberrant cell motility. Studies using RNA interference of fascin show that fibroblasts have reduced number and abnormal morphology of filopodia, while Ser-39 phosphorylation status may determine filopodial frequency. In Drosophila neurons, fascin deficiency causes alterations in actin filaments and leads to abnormal morphology of developing neurons. Thus, fascin is a critical element of actin-based motility in various cell types.
