Patterns make patterns: how hierarchical self-organization couples cell geometry to biochemical dynamics - Theory

Many cellular and developmental processes rely crucially on self-organization of protein patterns in space and time. When these protein patterns are coupled to force generation pathways, they can precisely pattern mechanical stress during processes such as cell division or tissue folding. Importantly, these mechanical processes generate shape deformations and cytoplasmic flows which, in turn, can modulate intracellular reaction-diffusion dynamics. This suggests a close coupling between cell mechanics and biochemical dynamics. But how do these protein patterns respond to a mechanically changing environment?
Here, we use the Rho GTPase driven surface contractions waves in starfish oocytes as a model system. We combine experimental results with a reaction-diffusion model and show how a cascade of coupled protein patterns creates a feedback loop between the Rho membrane dynamics and the cell shape. We posit that such hierarchical self-organization is a general mechanism for cells to sense changes in its global geometry.