Src, cortactin and Arp2/3 complex are required for E-cadherin-mediated internalization of Listeria into cells |
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Authors: | Sousa Sandra Cabanes Didier Bougnères Laurence Lecuit Marc Sansonetti Philippe Tran-Van-Nhieu Guy Cossart Pascale |
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Institution: | Institut Pasteur, Unité des Interactions Bactéries-Cellules; Inserm, U604; and INRA, USC2020, Paris F-75015, France. |
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Abstract: | Listeria monocytogenes is a food-borne pathogen able to invade non-phagocytic cells. InlA, a L. monocytogenes surface protein, interacts with human E-cadherin to promote bacterial entry. L. monocytogenes internalization is a dynamic process involving co-ordinated actin cytoskeleton rearrangements and host cell membrane remodelling at the site of bacterial attachment. Interaction between E-cadherin and catenins is required to promote Listeria entry, and for the establishment of adherens junctions in epithelial cells. Although several molecular factors promoting E-cadherin-mediated Listeria internalization have been identified, the proteins regulating the transient actin polymerization required at the bacterial entry site are unknown. Here we show that the Arp2/3 complex acts as an actin nucleator during the InlA/E-cadherin-dependent internalization. Using a variety of approaches including siRNA, expression of dominant negative derivatives and pharmacological inhibitors, we demonstrate the crucial role of cortactin in the activation of the Arp2/3 complex during InlA-mediated entry. We also show the requirement of the small GTPase Rac1 and that of Src-tyrosine kinase activity to promote Listeria internalization. Together, these data suggest a model in which Src tyrosine kinase and Rac1 promote recruitment of cortactin and activation of Arp2/3 at Listeria entry site, mimicking events that occur during adherens junction formation. |
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