Focal adhesions as mechanosensors: the two-spring model

Ulrich S. Schwarz, Thorsten Erdmann and Ilka B. Bischofs

BioSystems 83: 225-232 (2006)

Adhesion-dependent cells actively sense the mechanical properties of
their environment through mechanotransductory processes at focal
adhesions, which are integrin-based contacts connecting the
extracellular matrix to the cytoskeleton.  Here we present first steps
towards a quantitative understanding of focal adhesions as
mechanosensors. It has been shown experimentally that high levels of
force are related to growth of and signaling at focal adhesions.  In
particular, activation of the small GTPase Rho through focal adhesions
leads to the formation of stress fibers. Here we discuss one way in
which force might regulate the internal state of focal adhesions,
namely by modulating the internal rupture dynamics of focal
adhesions. A simple two-spring model shows that the stiffer the
environment, the more efficient cellular force is built up at focal
adhesions by molecular motors interacting with the actin filaments.