mDia1-nucleated bundled F-actin networks facilitate stress accumulation and contractility, whereas Arp2/3-nucleated branched networks prevent stress accumulation by inhibiting thick filament processivity.
F-actin architecture dictates myosin thick filament motion and stress generation, with bundled networks enhancing contractility and branched networks inhibiting it.
Active stresses are generated and transmitted throughout diverse F-actin architectures within the cell cytoskeleton, and drive essential behaviors of the cell, from cell division to migration. However, while the impact of F-actin architecture on the transmission of stress is well studied, the role of architecture on the ab initio generation of stresses remains less understood. Here, we assemble F-actin networks in vitro, whose architectures are varied from branched to bundled through F-actin nucleation via Arp2/3 and the formin mDia1. Within these architectures, we track the motions of embedded myosin thick filaments and connect them to the extent of F-actin network deformation. While mDia1-nucleated networks facilitate the accumulation of stress and drive contractility through enhanced actomyosin sliding, branched networks prevent stress accumulation through the inhibited processivity of thick filaments. The reduction in processivity is due to a decrease in translational and rotational motions constrained by the local density and geometry of F-actin.
Muresan et al. (Wed,) reported a other. F-actin networks nucleated via Arp2/3 vs mDia1 was evaluated on Myosin thick filament motion and F-actin network deformation. mDia1-nucleated bundled F-actin networks facilitate stress accumulation and contractility, whereas Arp2/3-nucleated branched networks prevent stress accumulation by inhibiting thick filament processivity.
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