Journal Article

Self-organizing actin patterns shape membrane architecture but not cell mechanics

Sezgin, E., Eggeling, C., Chang, V. T., Felce, J. H., Charras, G., Li, D., Betzig, E., Fritzsche, M., Colin-York, H., Moeendarbary, E.

2017

Overview

Cell-free studies have demonstrated how collective action of actin-associated proteins can organize actin filaments into dynamic patterns, such as vortices, asters and stars. Using complementary microscopic techniques, we here show evidence of such self-organization of the actin cortex in living HeLa cells. During cell adhesion, an active multistage process naturally leads to pattern transitions from actin vortices over stars into asters. This process is primarily driven by Arp2/3 complex nucleation, but not by myosin motors, which is in contrast to what has been theoretically predicted and observed in vitro . Concomitant measurements of mechanics and plasma membrane fluidity demonstrate that changes in actin patterning alter membrane architecture but occur functionally independent of macroscopic cortex elasticity. Consequently, tuning the activity of the Arp2/3 complex to alter filament assembly may thus be a mechanism allowing cells to adjust their membrane architecture without affecting their macroscopic mechanical properties. In vitro models of actin organization show the formation of vortices, asters and stars. Here Fritzsche et al . show that such actin structures form in living cells in a manner dependent on the Arp2/3 complex but not myosin, and such structures influence membrane architecture but not cortex elasticity.

• Publisher: Nature Publishing Group UK,Nature Publishing Group,Nature Portfolio
• Subject: 631/57/2268 / 631/80/128/1276 / 631/80/2373/2238 / Actin Cytoskeleton - chemistry / Actin Cytoskeleton - metabolism / Actin Cytoskeleton - ultrastructure / Actin-Related Protein 2-3 Complex - chemistry / Actin-Related Protein 2-3 Complex - metabolism / Actin-Related Protein 2-3 Complex - ultrastructure / Actins - chemistry / Actins - metabolism / Actins - ultrastructure / Cell Adhesion / Cell Membrane - chemistry / Cell Membrane - metabolism / Cell Membrane - ultrastructure / Equilibrium / HEK293 Cells / HeLa Cells / Humanities and Social Sciences / Humans / Mechanical Phenomena / Mechanics / Membrane Fluidity / Membranes / Microscopy, Atomic Force / Microscopy, Electron, Scanning / Microscopy, Fluorescence / Models, Molecular / multidisciplinary / Protein Conformation / Proteins / Science / Science (multidisciplinary) / Vortices