Clustering of α ₅ β ₁ integrins determines adhesion strength whereas α _v β ₃ and talin enable mechanotransduction

TLDR

Fibronectin binds integrins α5β1 and αvβ3 to link cells to the extracellular matrix, but their distinct roles in adhesion are not yet understood. The authors measured adhesion strength by applying physiological nanonewton forces to fibronectin‑coated magnetic beads attached to cells. Clustering of fibronectin domains within 40 nm recruits α5β1 integrins, boosting adhesion strength six‑fold, while αvβ3 and talin are not required for force maintenance but mediate cytoskeletal linkage and force‑induced reinforcement, so high‑force adhesion relies on clustered α5β1 and mechanotransduction via αvβ3–talin.

Abstract

A key molecular link between cells and the extracellular matrix is the binding between fibronectin and integrins α 5 β 1 and α v β 3 . However, the roles of these different integrins in establishing adhesion remain unclear. We tested the adhesion strength of fibronectin-integrin-cytoskeleton linkages by applying physiological nanonewton forces to fibronectin-coated magnetic beads bound to cells. We report that the clustering of fibronectin domains within 40 nm led to integrin α 5 β 1 recruitment, and increased the ability to sustain force by over six-fold. This force was supported by α 5 β 1 integrin clusters. Importantly, we did not detect a role of either integrin α v β 3 or talin 1 or 2 in maintaining adhesion strength. Instead, these molecules enabled the connection to the cytoskeleton and reinforcement in response to an applied force. Thus, high matrix forces are primarily supported by clustered α 5 β 1 integrins, while less stable links to α v β 3 integrins initiate mechanotransduction, resulting in reinforcement of integrin-cytoskeleton linkages through talin-dependent bonds.