TY - JOUR

T1 - Expression and cytoprotective activity of the small GTPase RhoB induced by the Escherichia coli cytotoxic necrotizing factor 1

AU - Huelsenbeck, Stefanie C

AU - Roggenkamp, Dennis

AU - May, Martin

AU - Huelsenbeck, Johannes

AU - Brakebusch, Cord Herbert

AU - Rottner, Klemens

AU - Ladwein, Markus

AU - Just, Ingo

AU - Fritz, Gerhard

AU - Schmidt, Gudula

AU - Genth, Harald

N1 - Copyright © 2013 Elsevier Ltd. All rights reserved.

PY - 2013/8

Y1 - 2013/8

N2 - 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.

AB - 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.

KW - Animals

KW - Bacterial Toxins

KW - Cell Death

KW - Cell Shape

KW - Cytoprotection

KW - Enzyme Activation

KW - Escherichia coli

KW - Escherichia coli Proteins

KW - Gene Expression Regulation

KW - HT29 Cells

KW - HeLa Cells

KW - Humans

KW - Mice

KW - NIH 3T3 Cells

KW - Polyploidy

KW - Promoter Regions, Genetic

KW - RNA, Messenger

KW - Transcriptional Activation

KW - Yersinia pseudotuberculosis

KW - rac1 GTP-Binding Protein

KW - rhoB GTP-Binding Protein

U2 - 10.1016/j.biocel.2013.05.020

DO - 10.1016/j.biocel.2013.05.020

M3 - Journal article

C2 - 23732113

VL - 45

SP - 1767

EP - 1775

JO - International Journal of Biochemistry & Cell Biology

JF - International Journal of Biochemistry & Cell Biology

SN - 1357-2725

IS - 8

ER -