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bioRxiv · 10.1101/2024.05.17.594765

Force-activated zyxin assemblies coordinate actin nucleation and crosslinking to orchestrate stress fiber repair

Phua, D. Y. Z.·Sun, X.·Alushin, G. M.
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Abstract

As the cytoskeleton sustains cell and tissue forces, it incurs physical damage that must be repaired to maintain mechanical homeostasis. The LIM-domain protein zyxin detects force-induced ruptures in actin-myosin stress fibers, coordinating downstream repair factors to restore stress fiber integrity through unclear mechanisms. Here, we reconstitute stress fiber repair with purified proteins, uncovering detailed links between zyxins force-regulated binding interactions and cytoskeletal dynamics. In addition to binding individual tensed actin filaments (F-actin), zyxins LIM domains form force-dependent assemblies that bridge broken filament fragments. Zyxin assemblies engage repair factors through multi-valent interactions, coordinating nucleation of new F-actin by VASP and its crosslinking into aligned bundles by [a]-actinin. Through these combined activities, stress fiber repair initiates within the cores of micron-scale damage sites in cells, explaining how these F-actin depleted regions are rapidly restored. Thus, zyxins force-dependent organization of actin repair machinery inherently operates at the network scale to maintain cytoskeletal integrity.

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Phua, D. Y. Z., Sun, X., Alushin, G. M.. 2024-05-18. Force-activated zyxin assemblies coordinate actin nucleation and crosslinking to orchestrate stress fiber repair. https://doi.org/10.1101/2024.05.17.594765

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