Contractility and retrograde flow in lamellipodium motion

Area of Science:

• Biophysics
• Cell Biology
• Rheology

Background:

• Cell locomotion is crucial for biological processes.
• The actin cytoskeleton drives cell movement.
• Understanding the physical mechanisms of cell motility is key.

Purpose of the Study:

• To develop a phenomenological model of cell locomotion on solid substrates.
• To describe the actin cytoskeleton in the lamellipodium as a viscous polar gel.
• To relate material properties to cell velocity and forces exerted on the substrate.

Main Methods:

• Developed constitutive equations for a viscous polar gel with intrinsic activity.
• Modeled actin polymerization at the leading edge.
• Used a two-dimensional description to calculate lamellipodium thickness, flow, and forces.

Main Results:

• Calculated steady-state lamellipodium thickness profile and flow profiles.
• Estimated cell velocity as a function of external forces.
• Observed retrograde flow in the lamellipodium and dipolar force distribution.

Conclusions:

• The viscous polar gel model accurately describes cell locomotion.
• The model is consistent with experimentally observed retrograde flow and force distribution.
• This framework provides insights into the physical basis of cell motility.