Modulation of Actin Polymerization using Curved Nanotopographic Surfaces

Exploring the mechanisms by which actin polymerizes and contributes to cell motility can offer valuable insights into biological processes such as cancer metastasis and wound healing. Structural factors, such as the surface features of the extracellular matrix, can influence how cells migrate. Previous research has suggested that nanotextured surfaces composed of parallel ridges may bias actin-wave polymerization bidirectionally along the ridges. However, extracellular environments are rarely composed of such well aligned surfaces. For better modelling of the heterogeneity in the extracellular environment, we sought to understand the cell sensing of Dictyostelium discoideum cells on curved nanotextured ridges. Fluorescently tagged actin in D. discoideum was imaged on several textures of varying degrees of curvature, and actin polymerization was characterized using optical flow. We show that curved textures modulate the degree of directional bias in actin polymerization. Surfaces with low levels of curvature retain the ability to bias actin polymerization, whereas surfaces with high levels of curvature strongly reduce polymerization bias. This effect appears to be associated with local alignment between actin polymerization and the ridge orientation.