Rho and F-actin self-organize within an artificial cell cortex

Area of Science:

• Cell Biology
• Biophysics
• Biochemistry

Background:

• The cell cortex, a dynamic layer beneath the plasma membrane, is crucial for cell adhesion, migration, and division.
• Cortical excitability, involving waves of filamentous-actin (F-actin) assembly and disassembly, is observed during cell division and locomotion.
• In vivo studies suggest coupled feedback loops involving Rho and F-actin generate cortical excitability, essential for processes like cytokinesis and spindle positioning.

Purpose of the Study:

• To investigate the self-organizing dynamics of cortical Rho and F-actin.
• To develop and utilize an artificial cell cortex model for studying these dynamics.
• To explore the mechanisms underlying Rho-GTPase-mediated cortical dynamics.

Main Methods:

• Reconstitution of an artificial cell cortex using Xenopus egg extract and supported lipid bilayers (SLBs).
• Observation and analysis of Rho and F-actin dynamics within the reconstituted system.
• Comparison of observed dynamics with previously characterized in vivo excitable dynamics.

Main Results:

• The artificial cortex spontaneously exhibited two distinct self-organized dynamic patterns: excitable waves and non-traveling oscillatory patches of Rho and F-actin.
• Both observed dynamic patterns shared properties and dependencies with in vivo cortical excitability.
• The findings demonstrate the self-organizing capacity of the cell cortex.

Conclusions:

• The cell cortex is a self-organizing structure capable of generating complex dynamic patterns.
• The reconstituted system provides a novel platform for investigating Rho-GTPase-mediated cortical dynamics.
• This work supports the hypothesis that intrinsic feedback mechanisms drive cortical excitability.