Matrix Stiffness-driven FAK Splicing Tunes Cell Mechanosensing

Cells can sense mechanical changes within the ECM through mechanosensors, most notably through the focal adhesion kinase (FAK). Using human-derived data and 2D/3D engineered models, we identified a ubiquitous and uncharacterized FAK isoform lacking exon 4 (FAKΔe4).

We demonstrated that FAKΔe4 splicing is regulated by substrate stiffness in a biphasic manner, in which an optimal stiffness is required for a maximal FAKΔe4 expression. We further showed that FAKΔe4 dictates at which stiffness optimal migration speed and invasion occurs, impairs focal adhesion dynamics and maturation, and shifts its autophosphorylation and downstream YAP nuclear translocation toward lower stiffness compared to the canonical FAK isoform.