Pulsatile contractions and pattern formation in excitable actomyosin cortex.

Area of Science:

• Cellular mechanics
• Biophysics
• Systems biology

Background:

• The actin cortex is a dynamic cellular structure.
• Its complex regulatory networks sense and transmit mechanical forces.
• Emergent dynamics of this mechanochemical system remain poorly understood.

Purpose of the Study:

• Investigate how chemical signaling and mechanical forces regulate stresses and patterns in the actin cortex.
• Model the RhoA signaling network coupled to an active actomyosin gel.
• Understand the interplay between biochemical regulation and mechanical properties.

Main Methods:

• Developed a reaction-diffusion model for the RhoA signaling network.
• Coupled the signaling model to an active actomyosin gel.
• Simulated the behavior of the coupled system under varying active stress.

Main Results:

• Mechanochemical feedback destabilizes homogeneous states, robustly generating pulsatile contractions.
• Tuning active stress leads to diverse emergent behaviors: propagating pulses, network structures, and topological turbulence.
• Demonstrated the generation of dynamic patterns from coupled chemical and mechanical processes.

Conclusions:

• Mechanochemical feedback is crucial for the emergent dynamics of the actin cortex.
• The developed model captures key behaviors of this active material.
• The study provides insights into how cells generate mechanical forces and patterns.