Intracellular Wave Dynamics Perturbed by Electric Fields and Nano-topography*

Cells can respond to dc Electric Fields (EFs) by directed migration along the fields. This phenomenon, called electrotaxis, is an important physiological process involved in wound healing and regeneration. However, the mechanism of how cells sense EFs and coordinate intracellular activities remain elusive. Recent studies have observed self-organized waves of coupled signal transduction and cytoskeletal activities in various cell types, and both experiments and simulation show that these intracellular waves drive protrusions and regulate cell random migration. In this study, we explore the roles of these intracellular waves during electrotaxis, by monitoring the dynamics of actin waves in response to EFs. We use electrofused giant Dictyostelium discoideum cells, which provide a large spatial extent for wave dynamics in a single cell. Our quantifications show that EFs bias the preferred location of wave initiation, increase wave areas, and guide wave propagation towards cathodes. We further add nano-topographies to provide spatially inhomogeneous perturbation on wave dynamics and show that the waves generated from different local topographic environments respond to EFs differently.