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Fibronectin is a good catch for integrin

Kong et al. find a touch of romance in the engagement between integrin adhesion receptors and their extracellular matrix ligands. The more life tries to pull them apart, the more they want to stay together.

As a cell crawls along, integrin heterodimers bind extracellular matrix molecules such as fibronectin and help the cell gain traction. You might expect that the harder the integrin–fibronectin bond is pulled, the more likely it is to break. But some types of molecular bond—called catch bonds—actually grow stronger as more force is applied to them.

Researchers have long speculated that integrins might display this unusual behavior, but experiments measuring the forces that disrupt integrin–ligand interactions failed to find any evidence of catch bonds. Kong et al. took a slightly different approach. They used atomic force microscopy to measure how long individual bonds between ₅β₁ integrin and fibronectin lasted when pulled apart with constant forces. As the pulling force increased, the ₅β₁–fibronectin association lasted longer, indicating that the molecules do form catch bonds.

The increased force might induce a conformational change in the proteins that locks the bond tighter. Kong et al. provide evidence that this switch occurs in the extracellular head domain of ₅β₁. Senior author Cheng Zhu, however, speculates that such a conformational change could be propagated across the plasma membrane to the integrin's tail, altering its association with the cytoskeleton and downstream signaling molecules. Force-induced changes in adhesion strength and signaling may help cells migrate and respond to their local environment.

References

Kong, F., et al. 2009. J. Cell Biol. doi:10.1083/jcb.200810002.[Abstract/Free Full Text]

bshort{at}rockefeller.edu

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This Article Full Text (PDF, 509K) Alert me when this article is cited Services Email this article Similar articles in this journal Alert me to new content in the JCB Download to citation manager Citing Articles Citing Articles via CrossRef Google Scholar Articles by Short, B. PubMed Articles by Short, B. Social Bookmarking                            What's this?