Actin Networks: Adapting to Load through Geometry Klemens Rottner, Frieda Kage  Current Biology  Volume 27, Issue 23, Pages R1274-R1277 (December 2017) DOI: 10.1016/j.cub.2017.10.042 Copyright © 2017 Elsevier Ltd Terms and Conditions

Figure 1 Actin network adaptation to experimental manipulation of plasma membrane load. (A) Examples of cellular micromanipulation scenarios employed by Mueller et al. [9], which allowed the authors to explore actin network dynamics and ultrastructural organization at steady state (middle) and upon increase (left) or decrease (right) of load exerted by the lamellipodial tip. (B) Summary of the consequences of experimental changes to load (left or right, see above) compared with steady-state organization of lamellipodial actin networks (middle). Prominent molecules that are essential (actin, Arp2/3 complex, capping protein [18]) or at least relevant (FMNL2/3 and Ena/VASP family of actin polymerases [19]) for network formation and organization are depicted. The lamellipodial Arp2/3 activator Scar/WAVE [20] and associated WAVE complex components are omitted for the sake of simplicity. Current Biology 2017 27, R1274-R1277DOI: (10.1016/j.cub.2017.10.042) Copyright © 2017 Elsevier Ltd Terms and Conditions

Figure 2 Modification of actin network appearance upon formin activation. Structured illumination microscopy (SIM) images of the phalloidin-stained actin cytoskeleton of a control B16-F1 cell lamellipodium (left) or the lamellipodium of a cell overexpressing an EGFP-tagged, constitutively active FMNL3 formin variant (middle and right), which promotes actin filament assembly at the lamellipodium tip [8]. Note the clear biasing of actin bundle angles in the lamellipodium towards 0° in cells overexpressing the FMNL3 variant (middle) compared with control (left). The yellow bracket marks the dimension of the lamellipodium; bar, 10 μm. (Images courtesy of Frieda Kage.) Current Biology 2017 27, R1274-R1277DOI: (10.1016/j.cub.2017.10.042) Copyright © 2017 Elsevier Ltd Terms and Conditions