Actin waves in the cortex of amoeboid cells — from data to modelsDr. Carsten Beta (University of Potsdam)

The actin-driven motility of eukaryotic cells plays a central role in many biological functions such as wound healing, embryonic morphogenesis, and cancer metastasis. It is coordinated by coherent patterns of activity in the actin cytoskeleton. Here, we present experimental results demonstrating the rich diversity of wave patterns in the actin cortex of motile cells. We show that actin waves mediate switches between different modes of motility, an amoeboid and a more persistent, keratocyte-like migratory mode, and may also trigger cell cycle-independent cytofission events. Our experimental findings can be qualitatively reproduced in the framework of a noisy bistable reaction-diffusion model that mimics the evolution of cortical patterns and couples to a dynamic phase field to take the cell shape dynamics into account. To establish a more quantitative link between the model and our experimental recordings, we develope a theory for parameter estimation of spatially extended activator–inhibitor systems based on a maximum likelihood ansatz. We exemplify this approach by estimating diffusivity and reaction terms of our model from both synthetic data and experimental fluorescence microscopy recordings of actin dynamics in amoeboid cells.