Open AccessYopE of Yersinia , a GAP for Rho GTPases, selectively modulates Rac‐dependent actin structures in endothelial cells
Author(s) -
Andor Andreas,
Trülzsch Konrad,
Essler Markus,
Roggenkamp Andreas,
Wiedemann Agnès,
Heesemann Jürgen,
Aepfelbacher Martin
Publication year - 2001
Publication title -
cellular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.542
H-Index - 138
eISSN - 1462-5822
pISSN - 1462-5814
DOI - 10.1046/j.1462-5822.2001.00114.x
Subject(s) - rhoa , microbiology and biotechnology , cdc42 , effector , biology , yersinia , rac gtp binding proteins , stress fiber , gtpase , secretion , rac1 , actin cytoskeleton , actin , cytoskeleton , signal transduction , focal adhesion , biochemistry , cell , genetics , bacteria
Yersinia spp. inject effector proteins ( Y ersinia o uter p roteins, Yop s ) into target cells via a type III secretion apparatus. The effector YopE was recently shown to possess GAP activity towards the Rho GTPases RhoA, Rac and CDC42 in vitro . To investigate the intracellular, ‘ in vivo ’ targets of YopE we generated a Yersinia enterocolitica strain [WA(pYLCR+E)] that injects ‘life‐like’ amounts of YopE as only effector. Primary human umbilical vein endothelial cells (HUVEC) were infected with WA(pYLCR+E) and were then stimulated with: (i) bradykinin to induce actin microspikes followed by ruffles as an assay for CDC42 activity followed by CDC42 stimulated Rac activity; (ii) sphingosine‐1‐phosphate to form ruffles by direct Rac activation; or (iii) thrombin to generate actin stress fibres through Rho activation. In WA(pYLCR+E)‐infected HUVEC microspike formation stimulated with bradykinin remained intact but the subsequent development of ruffles was abolished. Furthermore, ruffle formation after stimulation with sphingosine‐1‐phosphate or thrombin induced production of stress fibres was unaltered in the infected cells. These data suggest that YopE is able to inhibit Rac‐ but not Rho‐ or CDC42‐regulated actin structures and, more specifically, that YopE is capable of blocking CDC42Hs dependent Rac activation but not direct Rac activation in HUVEC. This provides evidence for a considerable specificity of YopE towards selective Rac‐mediated signalling pathways in primary target cells of Yersinia .