Self-organized stress patterns drive state transitions in actin cortices

Area of Science:

• Biophysics
• Cell Biology
• Soft Matter Physics

Background:

• Biological functions depend on ordered structures and energy dissipation.
• Cellular mechanical resilience is governed by the adaptable actomyosin cortex.
• Actomyosin cortex dynamics involve transitions between steady states.

Purpose of the Study:

• To investigate the self-organization of model actomyosin cortices.
• To understand how cross-link density influences nonequilibrium steady states and flow patterns.
• To explore the implications for cellular mechanical properties and functions.

Main Methods:

• Constructed model actomyosin cortices with component turnover.
• Varied cross-link density to induce different steady states.
• Utilized fluorescent single-walled carbon nanotubes to track flow patterns.

Main Results:

• Model actomyosin cortices self-organized into distinct nonequilibrium steady states.
• Cross-link density modulated the feedback between actin structure and myosin motor organization.
• A marginally cross-linked state showed divergence-free flow, while higher density led to symmetry breaking and converging flow.

Conclusions:

• The study reveals self-organization principles in actomyosin networks.
• Cross-link density is a key factor in determining dynamic steady states and flow patterns.
• Observed self-organization of stress patterns has implications for biological functions.