Human Epidermal Growth Factor Receptor 2 Dynamics Regulated by Actin-Filament Integrity on Cell Membranes Revealed by...

Area of Science:

• Cell biology
• Biophysics
• Nanotechnology

Background:

• Transmembrane protein dynamics are crucial for cellular functions.
• The cell membrane's cytoskeleton, particularly actin filaments, influences protein behavior.
• Understanding receptor organization is key to cell signaling and disease research.

Purpose of the Study:

• To investigate how actin filament integrity regulates transmembrane protein dynamics (lateral motion and orientation) on cell membranes.
• To explore the role of the cytoskeleton in organizing receptor behavior in living cancer cells.

Main Methods:

• Utilized anisotropic gold nanostars functionalized with HER2-targeting aptamers as optical probes.
• Employed differential interference contrast microscopy for real-time tracking of HER2 receptor dynamics.
• Disrupted actin filaments using latrunculin A to compare receptor behavior in intact vs. disrupted cytoskeletons.
• Applied two-dimensional single-nanoconstruct tracking analysis.

Main Results:

• Intact actin filaments restricted the lateral mobility of HER2 receptors, indicating membrane compartmentalization.
• Disruption of actin filaments led to Brownian motion of HER2 receptors.
• Receptor orientation showed reduced freedom (longer rotational dwell times) when actin was intact.
• Coordinated translation-rotation regulation by actin occurred primarily under directed diffusion modes.

Conclusions:

• Actin filament integrity is a critical regulator of both lateral and orientational dynamics of transmembrane proteins.
• Cytoskeletal architecture plays a significant role in organizing receptor dynamics within the cell membrane.
• Two-dimensional single-nanoconstruct tracking offers a valuable real-time method to study cytoskeleton-receptor interactions.