Gupton Stephanie L, Eisenmann Kathryn, Alberts Arthur S, Waterman-Storer Clare M
Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
J Cell Sci. 2007 Oct 1;120(Pt 19):3475-87. doi: 10.1242/jcs.006049. Epub 2007 Sep 12.
Cell migration requires spatial and temporal regulation of filamentous actin (F-actin) dynamics. This regulation is achieved by distinct actin-associated proteins, which mediate polymerization, depolymerization, severing, contraction, bundling or engagement to the membrane. Mammalian Diaphanous-related (mDia) formins, which nucleate, processively elongate, and in some cases bundle actin filaments, have been extensively studied in vitro, but their function in the cell has been less well characterized. Here we study the role of mDia2 activity in the dynamic organization of F-actin in migrating epithelial cells. We find that mDia2 localizes in the lamella of migrating epithelial cells, where it is involved in the formation of a stable pool of cortical actin and in maintenance of polymerization-competent free filament barbed ends at focal adhesions. Specific inhibition of mDia2 alters focal adhesion turnover and reduces migration velocity. We suggest that the regulation of filament assembly dynamics at focal adhesions may be necessary for the formation of a stable pool of cortical lamella actin and the proper assembly and disassembly dynamics of focal adhesions, making mDia2 an important factor in epithelial cell migration.
细胞迁移需要对丝状肌动蛋白（F-肌动蛋白）动力学进行空间和时间调控。这种调控是通过不同的肌动蛋白相关蛋白实现的，这些蛋白介导聚合、解聚、切断、收缩、成束或与膜结合。哺乳动物中与Diaphanous相关的（mDia）formin蛋白能够成核、持续延长并在某些情况下使肌动蛋白丝成束，已在体外进行了广泛研究，但它们在细胞中的功能尚未得到很好的表征。在这里，我们研究了mDia2活性在迁移上皮细胞中F-肌动蛋白动态组织中的作用。我们发现mDia2定位于迁移上皮细胞的片状伪足中，在那里它参与形成稳定的皮质肌动蛋白池，并在粘着斑处维持具有聚合能力的游离丝的带刺末端。对mDia2的特异性抑制会改变粘着斑的周转并降低迁移速度。我们认为，粘着斑处丝状肌动蛋白组装动力学的调控对于形成稳定的皮质片状伪足肌动蛋白池以及粘着斑的正确组装和解聚动力学可能是必要的，这使得mDia2成为上皮细胞迁移的一个重要因素。
