Volume changes during active shape fluctuations in cells

TL;DR

This study reveals that water transport is essential for cell bleb formation, highlighting the role of fluid dynamics in active cell shape changes through combined experiments and modeling.

Contribution

The paper demonstrates experimentally and theoretically that membrane permeability and water flow are crucial for bleb formation, a novel insight into cell shape dynamics.

Findings

Water transport is necessary for bleb formation.

Permeable membranes facilitate membrane-cortex deformations.

Hydrodynamics and elasticity balance is key in cell shape changes.

Abstract

Cells modify their volume in response to changes in osmotic pressure but it is usually assumed that other active shape variations do not involve significant volume fluctuations. Here we report experiments demonstrating that water transport in and out of the cell is needed for the formation of blebs, commonly observed protrusions in the plasma membrane driven by cortex contraction. We develop and simulate a model of fluid mediated membrane-cortex deformations and show that a permeable membrane is necessary for bleb formation which is otherwise impaired. Taken together our experimental and theoretical results emphasize the subtle balance between hydrodynamics and elasticity in actively driven cell morphological changes.