Helicobacter pylori CagA induces a transition from polarized to invasive phenotypes in MDCK cells

doi:10.1073/pnas.0502598102

Helicobacter pylori CagA induces a transition from polarized to invasive phenotypes in MDCK cells

^*Cellular Microbiology and BioInformatics Unit, Chiron Vaccines, Via Fiorentina 1, 53100 Siena, Italy; and Departments of ^†Microbiology and Immunology, ^‡Medicine, and ^§Pediatrics, Stanford University School of Medicine, Stanford, CA 94305-5124

Edited by E. Peter Greenberg, University of Washington School of Medicine, Seattle, WA (received for review March 30, 2005)

Abstract

CagA is a bacterial effector protein of Helicobacter pylori that is translocated via a type IV secretion system into gastric epithelial cells. We previously described that H. pylori require CagA to disrupt the organization and assembly of apical junctions in polarized epithelial cells. In this study, we provide evidence that CagA expression is not only sufficient to disrupt the apical junctions but also perturbs epithelial differentiation. CagA-expressing cells lose apicobasal polarity and cell–cell adhesion, extend migratory pseudopodia, and degrade basement membranes, acquiring an invasive phenotype. Expression of the CagA C-terminal domain, which contains the tyrosine phosphorylated EPIYA motifs, induces pseudopodial activity but is not sufficient to induce cell migration. Conversely, the N terminus targets CagA to the cell–cell junctions. Neither domain is sufficient to disrupt cell adhesion or cell polarity, but coexpressed in trans, the N terminus determines the localization of both polypeptides. We show that CagA induces a morphogenetic program in polarized Madin–Darby canine kidney cells resembling an epithelial-to-mesenchymal transition. We propose that altered cell–cell and cell matrix interactions may serve as an early event in H. pylori-induced carcinogenesis.

Footnotes

↵ ¶ To whom correspondence should be addressed at: Stanford University School of Medicine, 299 Campus Drive, Fairchild Building D041B, Stanford, CA 94305-5124. E-mail: amieva{at}stanford.edu.
Author contributions: F.B., L.T., A.C., and M.R.A. designed research; F.B., L.B., and M.R.A. performed research; and F.B., A.C., and M.R.A. analyzed data and wrote the paper.
Conflict of interest statement: No conflicts declared.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations: MDCK, Madin–Darby canine kidney; GFP, enhanced green fluorescent protein; RTK, receptor tyrosine kinase; EMT, epithelial-to-mesenchymal transition; MMP, matrix metalloproteinase.
Freely available online through the PNAS open access option.