Nano-scale actin-network characterization of fibroblast cells lacking functional Arp2/3 complex

Area of Science:

• Cell Biology
• Biophysics

Background:

• The Arp2/3 complex is traditionally considered the main driver of cell protrusion during migration.
• This complex controls actin filament network assembly at the cell's leading edge.

Purpose of the Study:

• To investigate the role of the Arp2/3 complex in cell migration and actin network organization.
• To reconcile the established role of Arp2/3 with observations of normal migration speeds in its absence.

Main Methods:

• Correlative fluorescence and cryo-electron tomography.
• Large-scale imaging and automated actin network analysis.
• Quantitative, single-filament level analysis.

Main Results:

• Mouse fibroblasts lacking functional Arp2/3 complex exhibit normal migration rates.
• Absence of Arp2/3 complex significantly alters the nanoscale architecture of actin networks.
• Cells without Arp2/3 fail to regulate location-dependent actin filament growth and organization.

Conclusions:

• The Arp2/3 complex's role in cell migration may be more nuanced than previously thought.
• Arp2/3 complex absence impacts actin organization at a fundamental, nanoscale level, independent of its role in dendritic network formation.