Stretchable force sensors

Cells in the body somehow sense that they are continually being pushed and pulled. Yasuhiro Sawada, Michael Sheetz (Columbia University, New York, NY), and colleagues now reveal that cellular tension causes a normally coiled cytoskeletal protein to stretch out and, in so doing, communicate the force downstream. The resulting signals help to direct cells toward areas of lower tension during wound healing and development.

Sheetz's group previously showed that stretching the cell's entire cytoskeleton triggered phosphorylation of a cytoskeletal protein called p130Cas, which is found at cell–matrix contact sites. The inference was that p130Cas itself was stretched and that this stretching was required for its phosphorylation, but formal proof was lacking.

So the group set up a test system with a modified p130Cas. Biotinylation of both ends of p130Cas allowed it to be attached to and...