ABSTRACTEpithelial cells that line the human intestinal mucosa constitute the initial sites of host invasion by bacterial pathogens. A number of bacteria, such asSalmonellaandYersiniaspp., 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 invasiveSalmonella entericaserovar Typhimurium SL1344 exhibited marked changes in F-actin organization, an increase in the paracellular flux of dextran, and a rapid decrease in transepithelial electrical resistance (TER). In contrast, infection with an isogenic noninvasive mutant (hilA) increased the TER in these cells. Pretreating MDCK-1 cells with the inhibitors for tyrosine kinase (genistein) or phosphatidylinositol 3-kinase (wortmannin) did not affect invasion and subsequent perturbation of the epithelial barrier by serovar Typhimurium. Instead, the geranylgeranyltransferase 1 inhibitor GGTI-298, but not the farnesyltransferase inhibitor FTI-277, clearly reversed the capacity of serovar Typhimurium to disrupt the epithelial barrier. The substrates for GGTI-298 include Rho family GTPases, as indicated by inhibiting prenylation of Rac1 and Cdc42. Infection with wild-type serovar Typhimurium increased the level of activated Rac1 and Cdc42 and caused these proteins to accumulate apically in MDCK-1 cells. ThisSalmonella-induced accumulation of Rac1 and Cdc42 and alteration of the junction-associated proteins ZO-1, occludin, and E-cadherin in MDCK-1 cells were markedly inhibited by GGTI-298. These results suggest that activation of geranylgeranylated proteins, including Rac1 and Cdc42, is critical for disruption of barrier integrity by serovar Typhimurium in polarized MDCK-1 cells.

Tafazoli, F., Magnusson, K.-E., & Zheng, L. (2003). Disruption of Epithelial Barrier Integrity bySalmonella entericaSerovar Typhimurium Requires Geranylgeranylated Proteins. Infection and Immunity, 71(2), 872–881.