Load Adaptation of Lamellipodial Actin Networks

Area of Science:

• Cell Biology
• Biophysics
• Mechanobiology

Background:

• Actin filaments are crucial for cellular processes like endocytosis and motility.
• In vitro studies suggest actin network structure and dynamics are sensitive to mechanical forces.

Purpose of the Study:

• To investigate how lamellipodial actin in migrating cells responds to mechanical load.
• To elucidate the mechanism by which actin networks adapt their geometry to varying membrane tension.

Main Methods:

• Modulating membrane tension in migrating cells.
• Analyzing the geometry and dynamics of actin networks using microscopy.
• Investigating the role of Arp2/3-generated branching in actin network adaptation.

Main Results:

• Migrating cells' actin networks exhibit a canonical dendritic geometry at steady state.
• Increased membrane tension leads to a denser actin network with varied branch angles.
• Decreased tension results in a sparse network with perpendicular filaments, driven by polymerization dynamics and protection from capping.

Conclusions:

• Actin networks possess an intrinsic geometrical adaptation mechanism responding to mechanical load.
• This adaptation tunes protrusive force by reorganizing filament geometry based on load.
• The findings reveal a direct link between mechanical forces and cellular actin organization.