Focal Adhesion Kinase: The Reversible Molecular Mechanosensor

Area of Science:

• Biophysics
• Cell Biology
• Mechanobiology

Background:

• Cellular responses to the environment are initiated by sensors.
• Mechanosensors are protein complexes converting mechanical stimuli into chemical signals.
• Focal adhesion kinase (FAK) acts as a mechanosensor, initiating signals upon phosphorylation.

Purpose of the Study:

• To develop a theoretical model for a reversible single-molecule stiffness sensor.
• To analyze the physical mechanism governing sensor conformation changes.
• To apply the model to FAK and understand its behavior under varying conditions.

Main Methods:

• Theoretical modeling of a single-molecule stiffness sensor.
• Analysis of conformation change rates based on substrate stiffness and cytoskeletal force.
• Comparison of model predictions with experimental cell phenotype observations.

Main Results:

• The model describes how FAK conformation changes depend on substrate stiffness and applied force.
• The sensor exhibits homeostasis, self-adjusting to match substrate stiffness for optimal sensitivity.
• Model results show good agreement with observed cellular phenotypes on different substrates.

Conclusions:

• The developed theoretical model provides insights into the physical mechanisms of mechanosensing.
• FAK functions as a homeostatic stiffness sensor, adapting its sensitivity to the cellular environment.
• This work advances the understanding of how cells sense and respond to mechanical cues.