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On page 177, Zhang et al. show that the extracellular domain of the 3?1 integrin can hijack a glycolipid- anchored receptor and thus trigger movement of an epithelial cell by inhibiting E-cadherin–mediated cell contacts.3 W# K W# m+ s
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Integrins on epithelial cells are well known to tether the cells to matrix components〞laminin-5 in the case of 3?1〞but are not usually associated with cell–cell contacts. Zhang et al. show that 3?1 can inhibit cell–cell contacts when 3 binds to the urokinase receptor, uPAR, a known inducer of cell migration in response to certain cytokines. Expression of both uPAR and 3?1 mobilized cells by reducing E-cadherin and -catenin levels at cell junctions, thus dissociating the cells. Other uPAR-induced changes included expression of several genes that are associated with the epithelial–mesenchymal transition, such as the transcription factor SLUG.
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The mesenchymal phenotype is a result of localized Src kinase activation induced by the uPAR–3?1 complex. Disruption of Src signaling by overexpression of its protein interaction domains inhibited uPAR-induced cell motility. High uPAR levels are associated with tumor metastasis and a poor prognosis. Since mutations in the 3 extracellular domain that abolish uPAR binding also block motility, mice expressing these mutants may have a better prognosis.(E-cadherin (green) contacts dissolve whe) |
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发表于 2009-3-6 00:38
发表于 2015-6-8 08:27
