Fascin Plays a Role in Stress Fiber Organization and Focal Adhesion Disassembly

• Published in: Current biology Vol. 24; no. 13; pp. 1492 - 1499
• Main Authors: Elkhatib, Nadia, Neu, Matthew B., Zensen, Carla, Schmoller, Kurt M., Louvard, Daniel, Bausch, Andreas R., Betz, Timo, Vignjevic, Danijela Matic
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 07-07-2014
• Subjects: Actins - metabolism; Analysis of Variance; Biomechanical Phenomena; Carrier Proteins - metabolism; Cell Line; Cell Movement - physiology; Focal Adhesions - metabolism; Green Fluorescent Proteins; Humans; Luminescent Proteins; Microfilament Proteins - metabolism; Microscopy, Fluorescence; Myosin Type II - metabolism; Polymerization; Red Fluorescent Protein; Stress Fibers - metabolism; Time-Lapse Imaging
• ISSN: 0960-9822; 1879-0445
• DOI: 10.1016/j.cub.2014.05.023

Migrating cells nucleate focal adhesions (FAs) at the cell front and disassemble them at the rear to allow cell translocation. FAs are made of a multiprotein complex, the adhesome, which connects integrins to stress fibers made of mixed-polarity actin filaments [1–5]. Myosin II-driven contraction of stress fibers generates tensile forces that promote adhesion growth [6–9]. However, tension must be tightly controlled, because if released, FAs disassemble [3, 10–12]. Conversely, excess tension can cause abrupt cell detachment resulting in the loss of a major part of the adhesion [9, 12]. Thus, both adhesion growth and disassembly depend on tensile forces generated by stress fiber contraction, but how this contractility is regulated remains unclear. Here, we show that the actin-bundling protein fascin crosslinks the actin filaments into parallel bundles at the stress fibers’ termini. Fascin prevents myosin II entry at this region and inhibits its activity in vitro. In fascin-depleted cells, polymerization of actin filaments at the stress fiber termini is slower, the actin cytoskeleton is reorganized into thicker stress fibers with a higher number of myosin II molecules, FAs are larger and less dynamic, and consequently, traction forces that cells exert on their substrate are larger. We also show that fascin dissociation from stress fibers is required to allow their severing by cofilin, leading to efficient disassembly of FAs.
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•Fascin contributes to stress fiber organization and dynamics•Focal adhesions in fascin-depleted cells have slower turnover•Fascin-depleted cells exhibit higher traction stress•Actin bundling by fascin opposes cofilin-mediated severing and FA disassembly
Elkhatib et al. show that the actin cross-bundling protein fascin contributes to stress fiber organization and focal adhesion (FA) dynamics, affecting traction forces that cells exert on their substrate. They also show that fascin dissociation from stress fibers is required to allow stress fiber severing by cofilin, leading to efficient disassembly of FAs.