The crucial role of elasticity in regulating liquid-liquid phase separation in cells

TL;DR

This paper demonstrates that elasticity significantly influences liquid-liquid phase separation in cells, acting as a mechanical switch that affects droplet behavior and transport, with implications for cellular organization.

Contribution

It combines experimental data with theoretical models to quantitatively analyze how nonlinear elasticity impacts phase separation and intracellular transport mechanisms.

Findings

Phase separation is highly sensitive to elastic properties.

Elasticity can serve as a mechanical switch for phase states.

Mechanically driven transport occurs at biologically relevant timescales.

Abstract

Liquid-liquid phase separation has emerged as a fundamental mechanism underlying intracellular organization, with evidence for it being reported in numerous different systems. However, there is a growing concern regarding the lack of quantitative rigor in the techniques employed to study phase separation, and their ability to account for the complex nature of the cellular milieu, which affects key experimentally observable measures, such as the shape, size and transport dynamics of liquid droplets. Here we bridge this gap by combining recent experimental data with theoretical predictions that capture the subtleties of nonlinear elasticity and fluid transport. We show that within a biologically accessible range of material parameters, phase separation is highly sensitive to elastic properties and can thus be used as a mechanical switch to rapidly transition between different states in cellular systems. Furthermore, we show that this active mechanically mediated mechanism can drive transport across cells at biologically relevant timescales and could play a crucial role in promoting spatial localization of condensates; whether cells exploit such mechanisms for transport of their constituents, remains an open question.