RT Journal Article
SR Electronic
T1 Filament Rigidity and Connectivity Tune the Deformation Modes of Active Biopolymer Networks
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 141796
DO 10.1101/141796
A1 Samantha Stam
A1 Simon L. Freedman
A1 Shiladitya Banerjee
A1 Kimberly L. Weirich
A1 Aaron R. Dinner
A1 Margaret L. Gardel
YR 2017
UL http://biorxiv.org/content/early/2017/05/24/141796.abstract
AB Molecular motors embedded within collections of actin and microtubule filaments underlie the dynamic behaviors of cytoskeletal assemblies. Understanding the physics of such motor-filament materials is critical to developing a physical model of the cytoskeleton and the design of biomimetic active materials. Here, we demonstrate through experiments and simulations that the rigidity and connectivity of filaments in active biopolymer networks regulates the anisotropy and the length scale of the underlying deformations, yielding materials with varying contractility. Semi-flexible filaments that can be compressed and bent by motor stresses undergo deformations that are predominantly biaxial. By contrast, rigid filament bundles contract via actomyosin sliding deformations that are predominantly uniaxial. Networks dominated by filament buckling are robustly contractile under a wide range of connectivities, while networks dominated by actomyosin sliding can be tuned from contractile to extensile through reduced connectivity via cross-linking. These results identify physical parameters that control the forces generated within motor-filament arrays, and provide insight into the self-organization and mechanics of cytoskeletal assemblies.Significance Statement The ability of living cells to spontaneously change their shape is necessary for physiological processes like cell migration and division. At the molecular scale, these shape changes are supported by forces and motions generated by molecular motors on biopolymers. However, how these microscopic forces give rise to shape changes at the cellular scale is unknown. Here, we used experimental measurements on reconstituted actomyosin networks and computer simulations to show that the polymer stiffness and connectivity can regulate the motor-generated stresses and resulting shape deformations. Importantly, we find that filament rigidity controls whether stresses transmitted are uniaxial or biaxial and that, for rigid filaments, the connectivity can control a transition between extensile and contractile deformations.