Stick-slip model for actin-driven cell protrusions, cell polarization, and crawling.

Area of Science:

• Cellular dynamics and mechanics
• Biophysics of cell motility
• Cytoskeletal regulation

Background:

• Cell crawling involves intracellular forces and cell-substrate adhesion.
• Crawling cells exhibit excitable system behaviors like symmetry breaking and wave propagation.
• Previous models invoked cytoskeletal instabilities and biochemical feedback loops.

Purpose of the Study:

• To demonstrate that cell-substrate adhesion dynamics and linear mechanics suffice to explain nonlinear cell crawling patterns.
• To model cell-substrate adhesion using the molecular clutch model.
• To investigate the role of mechanical forces and membrane tension in cell motility.

Main Methods:

• Analytical formalism of the molecular clutch model.
• Modeling cell-substrate adhesion regulated by local mechanical forces.
• Analysis of linear cellular mechanics and membrane tension.

Main Results:

• Cellular traction forces exhibit stick-slip dynamics.
• Periodic waves of protrusion/retraction and propagating waves along the cell edge were reproduced.
• Spontaneous symmetry breaking, polarization, steady crawling, bipedal motion, and bistability were explained.
• Membrane tension was identified as crucial for long-range mechanical communication and symmetry breaking.

Conclusions:

• The interplay between adhesion dynamics and linear mechanics explains key cell crawling behaviors.
• The molecular clutch model provides a framework for understanding cell motility patterns.
• Mechanical factors, including membrane tension, play a significant role in cell polarization and movement.