Measuring mechanical tension across vinculin reveals regulation of focal adhesion dynamics

Intracellular forces defined The ability of cells to respond to physical forces is fundamental to development and physiology, including regulation of blood pressure, cell adhesion and migration. A major limitation to the study of these phenomena has been the difficulty of measuring molecular forces in cells in vivo. Grashoff et al. now report the development of a genetically encoded, fluorescent tension-sensing module capable of measuring mechanical forces across specific proteins in vivo. The sensor was tested on vinculin, a membrane-cytoskeletal protein that is recruited to focal adhesions and connects cell-adhesion molecules (integrins) to actin filaments. The data reveal a regulatory mechanism in which the ability of vinculin to bear force determines whether focal adhesions assemble or disassemble under force. This new biosensor should be applicable to other proteins involved in mechanotransduction.