title: Cofilin promotes stimulus-induced lamellipodium formation by generating an abundant supply of actin monomers.
abstract: Cofilin stimulates actin filament disassembly and accelerates actin filament turnover. Cofilin is also involved in stimulus-induced actin filament assembly during lamellipodium formation. However, it is not clear whether this occurs by replenishing the actin monomer pool, through filament disassembly, or by creating free barbed ends, through its severing activity. Using photoactivatable Dronpa-actin, we show that cofilin is involved in producing more than half of all cytoplasmic actin monomers and that the rate of actin monomer incorporation into the tip of the lamellipodium is dependent on the size of this actin monomer pool. Finally, in cofilin-depleted cells, stimulus-induced actin monomer incorporation at the cell periphery is attenuated, but the incorporation of microinjected actin monomers is not. We propose that cofilin contributes to stimulus-induced actin filament assembly and lamellipodium extension by supplying an abundant pool of cytoplasmic actin monomers.
authors.affiliation: Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi, Japan.
authors.forename: Tai
authors.initials: T
authors.lastname: Kiuchi
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Ohashi
authors.forename: Souichi
authors.initials: S
authors.lastname: Kurita
authors.forename: Kensaku
authors.initials: K
authors.lastname: Mizuno
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D051339:Actin Depolymerizing Factors / Q000235:genetics* / Q000378:metabolism*; D000199:Actins / Q000378:metabolism*; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D003593:Cytoplasm / Q000378:metabolism*; D006801:Humans; D051379:Mice; D011554:Pseudopodia / Q000378:metabolism*
chemical_list: D051339:Actin Depolymerizing Factors; D000199:Actins