Actin microridges characterized by laser scanning confocal and atomic force microscopy.

Area of Science:

• Cell Biology
• Biophysics
• Zebrafish models

Background:

• The cell surface of stratified epithelia plays a crucial role in tissue integrity and response to injury.
• Actin cytoskeleton dynamics are fundamental to cell shape, movement, and mechanical properties.

Purpose of the Study:

• To characterize the cell surface architecture of zebrafish stratified epithelium under simulated wound healing conditions.
• To investigate the structure, dynamics, and potential functions of actin filament networks on epithelial cells.

Main Methods:

• Combined light and atomic force microscopy (AFM) for high-resolution surface imaging.
• Time-lapse microscopy to observe dynamic changes in the actin network.
• Treatment with cytochalasin B to assess actin filament stability.

Main Results:

• Zebrafish epithelial cells display surface microridges (approx. 100 nm height) correlated with actin filament bundles.
• A dynamic network of actin bundles, insensitive to cytochalasin B, was observed with rapid severing and annealing.
• AFM revealed two types of actin bundle junctions: overlaps and integrated T- and Y-junctions.
• The network was present on the topmost epithelial layer, not on individual migrating cells.

Conclusions:

• The dynamic actin network on zebrafish stratified epithelium may function in cell surface compartmentalization.
• This network could provide resistance to mechanical stress and serve as a reservoir for F-actin.
• Understanding these structures offers insights into epithelial repair mechanisms.