title: Crawling and turning in a minimal reaction-diffusion cell motility model: Coupling cell shape and biochemistry.
abstract: We study a minimal model of a crawling eukaryotic cell with a chemical polarity controlled by a reaction-diffusion mechanism describing Rho GTPase dynamics. The size, shape, and speed of the cell emerge from the combination of the chemical polarity, which controls the locations where actin polymerization occurs, and the physical properties of the cell, including its membrane tension. We find in our model both highly persistent trajectories, in which the cell crawls in a straight line, and turning trajectories, where the cell transitions from crawling in a line to crawling in a circle. We discuss the controlling variables for this turning instability and argue that turning arises from a coupling between the reaction-diffusion mechanism and the shape of the cell. This emphasizes the surprising features that can arise from simple links between cell mechanics and biochemistry. Our results suggest that similar instabilities may be present in a broad class of biochemical descriptions of cell polarity.
authors.affiliation: Department of Physics, University of California, San Diego, La Jolla, California 92093, USA.
authors.forename: Brian A
authors.initials: BA
authors.lastname: Camley
authors.affiliation: Department of Mathematics, The George Washington University, Washington, DC 20052, USA.
authors.forename: Yanxiang
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Department of Mathematics and Graduate Program in Quantitative Biology, University of California, San Diego, La Jolla, California 92093, USA.
authors.forename: Bo
authors.initials: B
authors.lastname: Li
authors.affiliation: Department of Bioengineering, Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, USA.
authors.forename: Herbert
authors.initials: H
authors.lastname: Levine
authors.affiliation: Department of Physics, University of California, San Diego, La Jolla, California 92093, USA.
authors.forename: Wouter-Jan
authors.initials: WJ
authors.lastname: Rappel