title: A Combination of Actin Treadmilling and Cross-Linking Drives Contraction of Random Actomyosin Arrays.
abstract: We investigate computationally the self-organization and contraction of an initially random actomyosin ring. In the framework of a detailed physical model for a ring of cross-linked actin filaments and myosin-II clusters, we derive the force balance equations and solve them numerically. We find that to contract, actin filaments have to treadmill and to be sufficiently cross linked, and myosin has to be processive. The simulations reveal how contraction scales with mechanochemical parameters. For example, they show that the ring made of longer filaments generates greater force but contracts slower. The model predicts that the ring contracts with a constant rate proportional to the initial ring radius if either myosin is released from the ring during contraction and actin filaments shorten, or if myosin is retained in the ring, while the actin filament number decreases. We demonstrate that a balance of actin nucleation and compression-dependent disassembly can also sustain contraction. Finally, the model demonstrates that with time pattern formation takes place in the ring, worsening the contractile process. The more random the actin dynamics are, the higher the contractility will be.
authors.affiliation: Courant Institute of Mathematical Sciences, New York University, New York, New York.
authors.forename: Dietmar B
authors.initials: DB
authors.lastname: Oelz
authors.affiliation: Stowers Institute, Kansas City, Missouri.
authors.forename: Boris Y
authors.initials: BY
authors.lastname: Rubinstein
authors.affiliation: Courant Institute of Mathematical Sciences, New York University, New York, New York; Department of Biology, New York University, New York, New York. Electronic address: mogilner@cims.nyu.edu.
authors.forename: Alex
authors.initials: A
authors.lastname: Mogilner
mesh_terms: D000199:Actins / Q000737:chemistry*; D000205:Actomyosin / Q000737:chemistry*; D000818:Animals; D001696:Biomechanical Phenomena; D017173:Caenorhabditis elegans; D003198:Computer Simulation; D008954:Models, Biological; D024462:Myosin Type II / Q000737:chemistry; D009492:Neurospora crassa; D004718:Saccharomycetales
chemical_list: D000199:Actins; D000205:Actomyosin; D024462:Myosin Type II