Evolving roles and dynamics for catch and slip bonds during adhesion cluster maturation

Area of Science:

• Cell biology
• Biophysics
• Materials science

Background:

• Focal adhesions connect cells to the extracellular matrix via integrins.
• These adhesions contain both catch bonds (strengthen with force) and slip bonds (weaken with force).
• Combinations of integrin types are crucial for focal adhesion stability and mechanosensing.

Purpose of the Study:

• To numerically investigate the interplay between catch and slip bonds within focal adhesions.
• To determine how slip bonds influence the collective behavior of catch bonds in integrin clusters.
• To understand the role of mixed-integrin compositions in focal adhesion mechanics.

Main Methods:

• Numerical simulations of mixed-integrin focal adhesions.
• Analysis of the collective behavior of catch and slip bonds under varying loads.
• Investigation of spatial distribution and integrin diffusivity in mixed adhesions.

Main Results:

• Mixing catch and slip bonds enhances mechanical integrity at low forces compared to pure-catch adhesions.
• The mixed system preserves the ability to strengthen the entire adhesion under applied force.
• Differential responses to loading lead to load-dependent integrin diffusivities via excluded volume interactions.

Conclusions:

• Mixed-integrin focal adhesions offer improved mechanical stability across a range of forces.
• The presence of slip bonds is critical for augmenting the function of catch bonds.
• These findings explain experimentally observed load-dependent integrin diffusion in focal adhesions.