Abstract
Filopodia are actin-rich cytoskeletal protrusions at the leading edge of motile cells. In neuronal growth cones they function as antennae, guiding axonal growth toward the appropriate cellular targets. Proper brain development relies on robust axonal guidance mechanisms, so it is imperative to understand how the actin cytoskeleton functions in remodeling to meet the demands of growth cone exploration. Here we show by cryo-electron tomography and fluorescence imaging that filopodia in neuronal growth cones switch between fascin-linked and cofilin-decorated states, and that this transition regulates the exclusion of fascin from the cofilactin bundle at the filopodial base by hyper-twisting individual filaments and rearranging their packing. Additionally, we show that cofilactin bundles contribute to the flexibility of filopodial actin networks, thus, likely regulating the efficiency of targeted neurite outgrowth.
Competing Interest Statement
The authors have declared no competing interest.