Minimal model of cellular symmetry breaking

TL;DR

This paper introduces a minimal hydrodynamic model of the cell cortex that explains how cellular symmetry breaking, such as polarization and division, can emerge from active surface instabilities coupled with a passive fluid.

Contribution

The work presents a novel minimal model combining active surface stresses and passive fluid coupling to explain cellular symmetry breaking phenomena.

Findings

Spontaneous polarization can occur via mechano-chemical instabilities.

Formation of contractile rings is explained by the model.

External fields can guide pattern formation.

Abstract

The cell cortex, a thin film of active material assembled below the cell membrane, plays a key role in cellular symmetry breaking processes such as cell polarity establishment and cell division. Here, we present a minimal model of the self-organization of the cell cortex that is based on a hydrodynamic theory of curved active surfaces. Active stresses on this surface are regulated by a diffusing molecular species. We show that coupling of the active surface to a passive bulk fluid enables spontaneous polarization and the formation of a contractile ring on the surface via mechano-chemical instabilities. We discuss the role of external fields in guiding such pattern formation. Our work reveals that key features of cellular symmetry breaking and cell division can emerge in a minimal model via general dynamic instabilities.