Cell vacuolation induced by the VacA cytotoxin of Helicobacter pylori is regulated by the Rac1 GTPase

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Colleges, School and Institutes


Chronic gastric infection with the Gram-negative bacterium Helicobacter pylori is a major contributing factor in the development of duodenal ulcers and is believed to be a significant risk factor in the development of gastric tumors. The VacA cytotoxin of H. pylori is a 90-kDa secreted protein that forms trans-membrane ion channels. In epithelial cells, VacA activity is associated with the rapid formation of acidic vacuoles enriched for late endosomal and lysosomal markers. Rac1 is a member of the Rho family of small GTP-binding proteins that regulate reorganization of the actin cytoskeleton and intracellular signal transduction and are being shown increasingly to play a role in membrane trafficking events. In this study we report that: (i) green fluorescent-tagged Rac1 localizes around the perimeter of the vacuoles induced by VacA; (ii) expression of dominant negative Rac1 in epithelial cells inhibits vacuole formation; (iii) expression of constitutively active Rac1 potentiates the activity of VacA. Taken together, these data demonstrate a role for Rac1 in the regulation of VacA activity.


Original languageEnglish
Pages (from-to)14009-12
Number of pages4
JournalJournal of Biological Chemistry
Issue number19
Publication statusPublished - 2000


  • Helicobacter pylori, Rac, Rho GTPases, VacA, epithelial cells