Fast Force Loading Disrupts Molecular Binding Stability in Human and Mouse Cell Adhesions

Area of Science:

• Biophysics
• Cellular Mechanics
• Molecular Interactions

Background:

• Force is crucial for cell adhesion and mechanosignaling, affecting receptor-ligand bond dissociation rates (off-rates).
• The precise mechanism by which force regulates these off-rates remains unclear.
• Discrepancies exist between different dynamic force spectroscopy (DFS) assays (force-clamp vs. force-ramp) when measuring the force-off-rate relationship.

Purpose of the Study:

• To investigate the mechanism of force-dependent regulation of receptor-ligand bond dissociation.
• To reconcile contradictory results obtained from different DFS assay methods.
• To develop a unified biophysical model for bond dissociation under varying force conditions.

Main Methods:

• Employed a live-cell dynamic force spectroscopy (DFS) technique using a biomembrane force probe.
• Measured single-bond dissociation in three key receptor-ligand systems: GPIbα-VWF, TCR-OVA peptide:MHC, and αIIbβ3-fibrinogen.
• Utilized parallel force-clamp and force-ramp assays to compare results.

Main Results:

• Force loading rate was identified as a critical factor disrupting molecular bond stability.
• Faster force loading promotes bonds to transition to a faster-dissociating state.
• A novel biophysical model incorporating force magnitude and loading rate successfully reconciled DFS assay discrepancies across all tested systems.

Conclusions:

• A new paradigm for understanding force-regulated receptor-ligand interactions has been established.
• The findings provide guidelines for the appropriate application of different DFS technologies.
• This work demonstrates the potential of using diverse DFS assays to address specific biological questions in cell adhesion and mechanosignaling.