Diffusive Interface Model for Actomyosin Driven Cell Oscillations

In this paper, we build phase-field models for the actomyosin driven cell oscillations. In our modeling, an oscillation starts from an actin cortex breakage. After the breakage, due to the unbalanced distribution of actin and myosin, there is unbalanced contraction force in different membrane components, which then results in the lipids transferring to the bulged membrane compartment. As such we can observe a cell oscillation. During the whole process, the actin and myosin polymerization and depolymerization play important roles. We give detailed formulations under the framework of phase-field methodology, in which phase-field functions are used to describe different parts of the cell membrane, integrated with the distribution of the actin and myosin at different components. The whole system is described as a set of time-dependent partial differential equations in three-dimensional space. Forward Euler method is used to solve the system. The spectral method is used for spatial discretizations for efficiency and accuracy purpose. Given carefully selected parameters, three-dimensional simulations are performed and compared with biological images. The simulations prove that actomyosin dynamics are the major reasons for cell oscillations. Further, our method can be easily extended into the simulations of cell polarization. We also compared our numerical simulations with biological experiments. This modeling gives an example of applying diffusive interface methods toward complex biology experiments.