title: Sequential inactivation of Rho GTPases and Lim kinase by Pseudomonas aeruginosa toxins ExoS and ExoT leads to endothelial monolayer breakdown.
abstract: Pseudomonas aeruginosa is a major human opportunistic pathogen and one of the most important causal agents of bacteremia. For non-blood-borne infection, bacterial dissemination requires the crossing of the vascular endothelium, the main barrier between blood and the surrounding tissues. Here, we investigated the effects of P. aeruginosa type 3 secretion effectors, namely ExoS, ExoT, and ExoY, on regulators of actin cytoskeleton dynamics in primary endothelial cells. ExoS and ExoT similarly affected the Lim kinase-cofilin pathway, thereby promoting actin filament severing. Cofilin activation was also observed in a mouse model of P. aeruginosa-induced acute pneumonia. Rho, Rac, and Cdc42 GTPases were sequentially inactivated, leading to inhibition of membrane ruffling, filopodia, and stress fiber collapse, and focal adhesion disruption. At the end of the process, ExoS and ExoT produced a dramatic retraction in all primary endothelial cell types tested and thus a rupture of the endothelial monolayer. ExoY alone had no effect in this context. Cell retraction could be counteracted by overexpression of actin cytoskeleton regulators. In addition, our data suggest that moesin is neither a direct exotoxin target nor an important player in this process. We conclude that any action leading to inhibition of actin filament breakdown will improve the barrier function of the endothelium during P. aeruginosa infection.
authors: INSERM, U1036, Biology of Cancer and Infection, Grenoble, France, phuber@cea.fr.
authors: P
authors: P
authors: Huber
authors: S
authors: S
authors: Bouillot
authors: S
authors: S
authors: Elsen
authors: I
authors: I
authors: Attrée
mesh_terms: D036002:ADP Ribose Transferases / Q000378:metabolism / Q000633:toxicity*; D008841:Actin Cytoskeleton / Q000187:drug effects; D000818:Animals; D001427:Bacterial Toxins / Q000378:metabolism / Q000633:toxicity*; D042783:Endothelial Cells / Q000187:drug effects / Q000382:microbiology* / Q000473:pathology; D004789:Enzyme Activation / Q000187:drug effects; D022001:Focal Adhesions / Q000187:drug effects; D020690:GTPase-Activating Proteins / Q000378:metabolism / Q000633:toxicity*; D054884:Host-Pathogen Interactions; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D054461:Lim Kinases / Q000378:metabolism*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D011552:Pseudomonas Infections / Q000201:enzymology / Q000382:microbiology / Q000473:pathology; D011550:Pseudomonas aeruginosa / Q000378:metabolism*; D020741:rho GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D001427:Bacterial Toxins; C477521:ExoT protein, Pseudomonas aeruginosa; D020690:GTPase-Activating Proteins; D036002:ADP Ribose Transferases; C444820:exoenzyme S; D054461:Lim Kinases; D020741:rho GTP-Binding Proteins
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