YopH prevents monocyte chemoattractant protein 1 expression in macrophages and T‐cell proliferation through inactivation of the phosphatidylinositoI 3‐kinase pathway

• Published in: Molecular microbiology 2002-08, Vol.45 (3), p.805-815
• Main Authors: Sauvonnet, Nathalie, Lambermont, Isabelle, Bruggen, Pierre van der, Cornelis, Guy R.
• Format: Article
• Language: English
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1046/j.1365-2958.2002.03053.x

Summary Phosphatidylinositol 3‐kinase (PI 3‐kinase) and its target protein kinase B (Akt) are involved in various processes including internalization, chemotaxis and proliferation. We analysed the activation of Akt in J774 macrophages infected with virulent (pYV+) or avirulent (pYV−) Yersinia enterocolitica. During the early stage of infection with pYV+ and pYV− bacteria, Akt and its targets, glycogen synthase kinase 3 (GSK‐3) and forkhead transcription factor (FKHRL1), became phosphorylated. This phosphorylation induction was inhibited by wortmannin and thus dependent on PI 3‐kinase. When infection was carried out with pYV+ bacteria but not with pYV− bacteria, Akt and its targets became dephosphorylated at later time points. Using single knock‐out mutants in bacterial effector genes, we have determined that the tyrosine phosphatase YopH was responsible for the inactivation of the PI 3‐kinase cascade. In macrophages, this inactivation correlated with the downregulation of mRNA coding for monocyte chemoattractant protein 1 (MCP‐1), suggesting that YopH inhibits recruitment of macrophages to lymph nodes. We also analysed the effects of Y. enterocolitica infection on the proliferation of T lymphocytes. Consistent with the observation that YopH inactivated the Akt pathway, YopH inhibited PI 3‐kinase‐dependent secretion of interleukin 2 and proliferation. These data reveal a new effect of YopH in Yersinia pathogenesis.