Interplay between myosin II and actin dynamics in chemotactic amoeba

Abstract

The actin cytoskeleton and its response to external chemical stimuli is fundamental to the mechanobiology of eukaryotic cells and their functions. One of the key players that governs the dynamics of the actin network is the motor protein myosin II. Based on a phase space embedding we have identified from experiments three phases in the cytoskeletal dynamics of starved Dictyostelium discoideum in response to a precisely controlled chemotactic stimulation. In the first two phases the dynamics of actin and myosin II in the cortex is uncoupled, while in the third phase the time scale for the recovery of cortical actin is determined by the myosin II dynamics. We report a theoretical model that captures the experimental observations quantitatively. The model predicts an increase in the optimal response time of actin with decreasing myosin II-actin coupling strength highlighting the role of myosin II in the robust control of cell contraction.

Receptor-induced transient responses in cells with oscillatory actin dynamics

“…This induces reorganization of the actin cytoskeleton and chemotactic migration of cells towards regions of higher cAMP concentration [1]. The cytoskeletal actomyosin system not only generates the forces required for amoeboid locomotion but also determines the shape and mechanical stability of the cells [2,3]. In our previous work, we have probed the dynamical properties of actin polymerization in response to external pulses of cAMP [4].…”