Antagonist-induced deadhesion of specifically adhered vesicles

Area of Science:

• Biophysics
• Cell Adhesion Dynamics
• Surface Chemistry

Background:

• Cell adhesion is mediated by specific molecular interactions, such as E-selectin binding to Lewis(X).
• Understanding and controlling cell deadhesion is critical in biological processes and disease.

Purpose of the Study:

• To identify and characterize novel mechanisms of antagonist-induced deadhesion.
• To develop a theoretical framework for deadhesion processes.
• To establish a new method for determining receptor binding affinity.

Main Methods:

• Utilized a model system of giant vesicles adhering to flat substrates.
• Employed specific binding of surface-grafted E-selectin and vesicle-carrying oligosaccharide Lewis(X).
• Induced deadhesion via titration of monoclonal antibodies against E-selectin, combining experimental and theoretical approaches.

Main Results:

• Identified two distinct deadhesion mechanisms: contact zone retraction and antibody penetration.
• Observed equilibrium states as a balance between vesicle spreading pressure and antagonist-induced lateral pressure.
• Demonstrated sigmoidal ligand-antagonist concentration-dependent binding, revealing microdomain decomposition in adhesion zones.

Conclusions:

• The study elucidates two novel mechanisms governing antagonist-induced deadhesion.
• Provides a robust theoretical model for understanding adhesion and deadhesion dynamics.
• Offers a new quantitative method for assessing receptor-ligand and antagonist binding affinities.