First published online December 20, 2006
Journal of Cell Science 120, 103e (2007)
© The Company of Biologists Limited
Paxillin makes the switch
Three types of integrin-based adhesion connect cells to the extracellular matrix: focal complexes (FXs) drive cell spreading and migration; focal adhesions (FAs) mediate robust adhesion to the matrix; and fibrillar adhesions (FBs) mediate matrix remodelling. But what regulates the distribution and dynamics of these interconvertible adhesions? On p. 137 Ronen Zaidel-Bar and co-authors report that tyrosine phosphorylation of the FA-associated adaptor protein paxillin acts as a major switch in their regulation. The authors use live-cell imaging to show that tyrosine-phosphorylated paxillin is associated with FXs and FAs but absent from FBs and that mechanical force negatively regulates the proportion of paxillin that is phosphorylated. Overexpression of a non-phosphorylatable mutant of paxillin enhances FB formation, they report, whereas overexpression of a phosphomimetic mutant induces FX and FA formation. The phosphomimetic mutant also enhances adhesion turnover, probably by recruiting focal adhesion kinase (FAK). The authors use these data to construct a model in which paxillin phosphorylation, FAK and mechanical forces concertedly regulate the assembly and turnover of integrin-based adhesions.
Related articles in JCS:
- A paxillin tyrosine phosphorylation switch regulates the assembly and form of cell-matrix adhesions
- Ronen Zaidel-Bar, Ron Milo, Zvi Kam, and Benjamin Geiger
JCS 2007 120: 137-148.
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