Expression and cytoprotective activity of the small GTPase RhoB induced by the Escherichia coli cytotoxic necrotizing factor 1

Stefanie C Huelsenbeck, Dennis Roggenkamp, Martin May, Johannes Huelsenbeck, Cord Herbert Brakebusch, Klemens Rottner, Markus Ladwein, Ingo Just, Gerhard Fritz, Gudula Schmidt, Harald Genth

2 Citations (Scopus)

Abstract

RhoB is the only member of the Rho subfamily of small GTPases, which is classified as an immediate early gene product. RhoB is up-regulated in response to growth factors as well as cytotoxic and genotoxic agents. Clostridial glucosylating toxins have been reported to evoke pronounced RhoB expression, based on the inactivation of Rho/Ras proteins. In this study, we report on a long lasting expression of RhoB in cultured cells upon activation of Rho proteins by the cytotoxic necrotizing factor 1 (CNF1) from Escherichia coli. The observations of this study highlight a new pathway involving Rac1, which positively regulates the activity of the rhoB promoter and RhoB expression. Conversely, the isomeric cytotoxic necrotizing factor from Yersinia pseudotuberculosis (CNFy) drives GTP-loading of basal RhoB but fails to cause activation of the rhoB promoter and thus its expression. CNF1 inhibits cytokinesis and induces the formation of bi-nucleated (tetraploid) cells. Upon long term treatment with CNF1, RhoB(-/-) mouse embryonic fibroblasts (MEFs) exhibit DNA fragmentation, phosphatidylserine exposure, and loss of membrane integrity, while RhoB(+/-) MEFs persist as bi-nucleated (tetraploid) cells without any signs of cell death. In conclusion, the cytoprotective RhoB response is not only evoked by bacterial protein toxins inactivating Rho/Ras proteins but also by the Rac1-activating toxin CNF1.
Original languageEnglish
JournalInternational Journal of Biochemistry & Cell Biology
Volume45
Issue number8
Pages (from-to)1767-75
Number of pages9
ISSN1357-2725
DOIs
Publication statusPublished - Aug 2013

Keywords

  • Animals
  • Bacterial Toxins
  • Cell Death
  • Cell Shape
  • Cytoprotection
  • Enzyme Activation
  • Escherichia coli
  • Escherichia coli Proteins
  • Gene Expression Regulation
  • HT29 Cells
  • HeLa Cells
  • Humans
  • Mice
  • NIH 3T3 Cells
  • Polyploidy
  • Promoter Regions, Genetic
  • RNA, Messenger
  • Transcriptional Activation
  • Yersinia pseudotuberculosis
  • rac1 GTP-Binding Protein
  • rhoB GTP-Binding Protein

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