Cell Biology

To Spread or Not to Spread

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Science  23 Nov 2007:
Vol. 318, Issue 5854, pp. 1218-1219
DOI: 10.1126/science.318.5854.1218d

When animal cells grow over a surface, they survey their surroundings and make decisions as to whether they should spread or retract from a certain path, processes that are central in cell migration and proliferation. Key to these decisions is the interaction of a group of membrane proteins, the integrins, with the surface on which the cells grow.

Flevaris et al. find that it is the calpaindependent proteolytic cleavage of the integrin subunit β3 at a specific tyrosine residue that acts as a molecular switch to help the cell change from spreading to retraction. In cells expressing a β3 integrin that cannot be cleaved, spreading is enhanced in comparison to retraction. On the other hand, in cells expressing only the cleaved form of β3, retraction is favored—a defect that can be overcome by expressing the downstream signaling protein RhoA. The effects of β3 appear to be mediated via an interaction of the intact integrin with the kinase c-Src at the plasma membrane, which in turn regulates RhoA-dependent contractile signaling. — SMH

J. Cell Biol. 179, 553 (2007).

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