Infection and Immunity, September 2000, p. 5335-5343, Vol. 68, No. 9
0019-9567/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
1-Integrins Allow
Binding and YopE-Mediated Perturbation of Epithelial Barriers by
Wild-Type Yersinia Bacteria
Division of Medical Microbiology, Department of Health and Environment, Linköping University, S-581 85 Linköping,1 and Department of Microbiology, National Defence Research Establishment, S-901 82 Umeå,2 Sweden
Received 16 February 2000/Returned for modification 30 March 2000/Accepted 30 May 2000
Using polarized epithelial cells, primarily MDCK-1, we assessed the
mode of binding and effects on epithelial cell structure and
permeability of Yersinia pseudotuberculosis yadA-deficient mutants. Initially, all bacteria except the invasin-deficient (inv) mutant adhered apically to the tight junction areas.
These contact points of adjacent cells displayed
1-integrins together with tight junction-associated ZO-1 and
occludin proteins. Indeed,
1-integrin expression was
maximal in the tight junction area and then gradually decreased along
the basolateral membranes. Wild-type bacteria also opened
gradually the tight junction to paracellular permeation of
different-sized markers, viz., 20-, 40-, and 70-kDa dextrans and 45-kDa
ovalbumin, as well as to their own translocation between adjacent
cells in intimate contact with
1-integrins. The effects on the
epithelial cells and their barrier properties could primarily be
attributed to expression of the Yersinia outer membrane
protein YopE, as the yopE mutant bound but caused no
cytotoxicity. Moreover, the apical structure of filamentous actin
(F-actin) was disturbed and tight junction-associated proteins (ZO-1
and occludin) were dispersed along the basolateral membranes. It is
concluded that the Yersinia bacteria attach to
1-integrins at tight junctions. Via this localized injection of
YopE, they perturb the F-actin structure and distribution of proteins
forming and regulating tight junctions. Thereby they promote
paracellular translocation of bacteria and soluble compounds.
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