Actin filaments polymerizing against membranes power endocytosis, vesicular traffic, and cell motility. In vitro reconstitution studies suggest that the structure and the dynamics of actin networks respond to mechanical forces. We demonstrate that lamellipodial actin of migrating cells responds to mechanical load when membrane tension is modulated. In a steady state, migrating cell filaments assume the canonical dendritic geometry, defined by Arp2/3-generated 70° branch points. Increased tension triggers a dense network with a broadened range of angles, whereas decreased tension causes a shift to a sparse configuration dominated by filaments growing perpendicularly to the plasma membrane. We show that these responses emerge from the geometry of branched actin: when load per filament decreases, elongation speed increases and perpendicular filaments gradually outcompete others because they polymerize the shortest distance to the membrane, where they are protected from capping. This network-intrinsic geometrical adaptation mechanism tunes protrusive force in response to mechanical load.
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Mueller J, Szep G, Nemethova M, et al. Load adaptation of lamellipodial actin networks. Cell. 2017;171(1):188-200. doi:10.1016/j.cell.2017.07.051
Mueller, J., Szep, G., Nemethova, M., De Vries, I., Lieber, A., Winkler, C., … Sixt, M. K. (2017). Load adaptation of lamellipodial actin networks. Cell, 171(1), 188–200. https://doi.org/10.1016/j.cell.2017.07.051
Mueller, Jan, Gregory Szep, Maria Nemethova, Ingrid De Vries, Arnon Lieber, Christoph Winkler, Karsten Kruse, et al. “Load Adaptation of Lamellipodial Actin Networks.” Cell 171, no. 1 (2017): 188–200. https://doi.org/10.1016/j.cell.2017.07.051.
J. Mueller et al., “Load adaptation of lamellipodial actin networks,” Cell, vol. 171, no. 1, pp. 188–200, 2017.
Mueller J, Szep G, Nemethova M, De Vries I, Lieber A, Winkler C, Kruse K, Small J, Schmeiser C, Keren K, Hauschild R, Sixt MK. 2017. Load adaptation of lamellipodial actin networks. Cell. 171(1), 188–200.
Mueller, Jan, et al. “Load Adaptation of Lamellipodial Actin Networks.” Cell, vol. 171, no. 1, Cell Press, 2017, pp. 188–200, doi:10.1016/j.cell.2017.07.051.