Disruption of Barrier Integrity by Salmonella typhimurium Requires Activation of Cdc42 and Rac1 in Epithelial Cells
(English)Manuscript (preprint) (Other academic)
Epithelial cells that line the human intestinal mucosa constitute the initial sites of host invasion by bacterial pathogens. A number of bacteria, such as Salmonella and Yersinia, have been shown to disrupt the integrity of the epithelial barrier, although little is known about the mechanisms underlying that effect. We found that polarized MDCK-1 epithelial cells infected with invasive Salmonella typhimurium SLI344 exhibited marked changes in F-actin organization and a rapid decrease in transepithelial electrical resistance (TER). In contrast, infection with isogenic noninvasive mutants (hilA, prgH, and sipC) increased the TER in these cells. Pretreating MDCK-1 cells with the tyrosine kinase inhibitor genistein or the PI-3 kinase inhibitor wortmannin did not affect invasion and subsequent perturbation of the epithelial barrier by S. typhimurium. Instead, the specific geranylgeranyltransferase-1 inhibitor GGTI-298, but not the farnesyltransferase inhibitor FTI-277, clearly reversed the capacity of S. typhimurium to disrupt the epithelial barrier. The best-known substrates for GGTI-298 include Rho family GTPases, Racl and Cdc42. Infection with wild-type S. typhimurium increased the level of activated Racl and Cdc42 and caused these proteins to accumulate apically in MDCK-1 cells. GGTI-298-induced inactivation of Racl and Cdc42 prevented alteration of the tight and adherens junction-associated proteins Z0-1, occludin, and E-cadherin in MDCK-1 cells infected with invasive Salmonella. These results indicate that activation of Racl and Cdc42, but not tyrosine kinase or PI-3 kinase, is essential for disruption of barrier integrity by S. typhimurium in polarized MDCK-1 cells.
Salmonella typhimurium, epithelium, tight junctions, Rac1, Cdc42
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:liu:diva-80200OAI: oai:DiVA.org:liu-80200DiVA: diva2:546129