Theoretical study of actin layers attachment and separation.

Area of Science:

• Biophysics
• Cell Biology
• Theoretical Biology

Background:

• Animal cell cortical layers are dense actin networks.
• Actin dynamics are crucial for cell shape and mechanics.
• Active gel theory describes materials with self-propulsion.

Purpose of the Study:

• To theoretically investigate the merging and separation dynamics of two actin dense layers.
• To understand the mechanical properties and stability of a single merged actin layer.
• To identify factors influencing the resilience and potential rupture of these cellular structures.

Main Methods:

• Utilizing the theory of active gels to model actin-based cellular structures.
• Simulating the binding and stretching behaviors of two distinct actin dense layers.
• Analyzing the contractile properties of the actomyosin gel and the role of myosin motors.

Main Results:

• Two actin dense layers merge to form a single layer, similar to a lamellipodium.
• The merged layer exhibits resilience to stretching, resisting separation up to a critical length.
• This resistance is attributed to the high contractility of the actomyosin gel.
• Actin filament nematic order along polymerizing membranes acts as a destabilizing factor for the stretched layer.

Conclusions:

• The merging and separation behavior of actin layers are governed by active gel properties, particularly actomyosin contractility.
• The stability of the merged layer is a complex interplay of contractile forces and filament organization.
• Nematic order in actin filaments can compromise the structural integrity of stretched cellular layers.