Collective dynamics of actomyosin cortex endow cells with intrinsic mechanosensing properties

TL;DR

This paper presents a minimal mechanical model demonstrating that actomyosin cortex dynamics enable cells to intrinsically sense and respond to environmental stiffness, affecting force generation and cell shape.

Contribution

It introduces a novel minimal model linking actomyosin interactions to cellular mechanosensing, explaining force and shape regulation without biochemical signaling.

Findings

Cells adapt force and shape based on environmental stiffness.

Model predicts maximum force and contraction speed of cells.

Force-velocity relationship similar to muscle contraction observed.

Abstract

Living cells adapt and respond actively to the mechanical properties of their environment. In addition to biochemical mechanotransduction, evidence exists for a myosin-dependent, purely mechanical sensitivity to the stiffness of the surroundings at the scale of the whole cell. Using a minimal model of the dynamics of actomyosin cortex, we show that the interplay of myosin power strokes with the rapidly remodelling actin network results in a regulation of force and cell shape that adapts to the stiffness of the environment. Instantaneous changes of the environment stiffness are found to trigger an intrinsic mechanical response of the actomyosin cortex. Cortical retrograde flow resulting from actin polymerisation at the edges is shown to be modulated by the stress resulting from myosin contractility, which in turn regulates the cell size in a force-dependent manner. The model describes the maximum force that cells can exert and the maximum speed at which they can contract, which are measured experimentally. These limiting cases are found to be associated with energy dissipation phenomena which are of the same nature as those taking place during the contraction of a whole muscle. This explains the fact that single nonmuscle cell and whole muscle contraction both follow a Hill-like force-velocity relationship.