title: Actin-myosin spatial patterns from a simplified isotropic viscoelastic model.
abstract: F-actin networks are involved in cell mechanical processes ranging from motility to endocytosis. The mesoscale architecture of assemblies of individual F-actin polymers that gives rise to micrometer-scale rheological properties is poorly understood, despite numerous in vivo and vitro studies. In vitro networks have been shown to organize into spatial patterns when spatially confined, including dense spherical shells inside spherical emulsion droplets. Here we develop a simplified model of an isotropic, compressible, viscoelastic material continually assembling and disassembling. We demonstrate that spherical shells emerge naturally when the strain relaxation rate (corresponding to internal network reorganization) is slower than the disassembly rate (corresponding to F-actin depolymerization). These patterns are consistent with recent experiments, including a collapse of shells to a central high-density focus of F-actin when either assembly or disassembly is reduced with drugs. Our results demonstrate how complex spatio-temporal patterns can emerge without spatially distributed force generation, polar alignment of F-actin polymers, or spatially nonuniform regulation of F-actin by upstream biochemical networks.
authors.affiliation: Department of Mathematics, University of California at Davis, Davis, California.
authors.forename: Owen L
authors.initials: OL
authors.lastname: Lewis
authors.affiliation: Department of Mathematics, University of California at Davis, Davis, California.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Guy
authors.affiliation: Department of Mathematics, Department of Physics and Astronomy, Center for Complex Biological Systems, University of California at Irvine, Irvine, California. Electronic address: jun.allard@uci.edu.
authors.forename: Jun F
authors.initials: JF
authors.lastname: Allard
mesh_terms: D000199:Actins / Q000737:chemistry*; D000465:Algorithms; D001696:Biomechanical Phenomena; D055119:Elastic Modulus; D008954:Models, Biological; D009218:Myosins / Q000737:chemistry*; D058105:Polymerization; D055682:Viscoelastic Substances / Q000737:chemistry
chemical_list: D000199:Actins; D055682:Viscoelastic Substances; D009218:Myosins