Glucosylation of small-gtp binding rho proteins disrupts
endothelial barrier function.
Hippenstiel, S., S. Tannert-Otto, N. Vollrath1, M. Krll, I. Just, K.
Aktories, C. V. Eichel-Streiber, and N. Suttorp.
Department of Internal Medicine, Justus-Liebig-University, D-35392
Giessen, Germany; Department of Pharmacology and Toxicology, Albert
-Ludwigs-University, D-79104 Freiburg, Germany; Institut fr
Medizinische Mikrobiologie und Hygiene, Johannes Gutenberg
-University, D-55101 Mainz, Germany.
APStracts 3:0150L, 1996.
The endothelial cytoskeleton is important for the regulation of
endothelial barrier function. Small GTP-binding Rho proteins play a
central role in the organization of the microfilament system.
Clostridium difficile toxin B (TcdB) inactivates Rho-proteins by
glucosylation at threonine 37. We used TcdB as a probe to study the
role of Rho proteins in the regulation of endothelial barrier
function. TcdB time- (50-170 min) and dose-dependently (10-100 ng/ml)
increased the hydraulic conductivity of cultured porcine pulmonary
artery endothelial cell monolayers about tenfold. Simultaneously, the
albumin reflection coefficient decreased substantially from 0.8 to
0.15. Prior to endothelial hyperpermeability, TcdB reduced F-actin
content in a dose-dependent manner whereas G-actin content remained
unchanged. Finally, we proved for endothelial cells that TcdB caused
dose- (5-100 ng/ml) and time-dependent glucosylation of Rho proteins.
Phalloidin which stabilizes filamentous actin prevented the effect of
TcdB on endothelial permeability. In contrast to thrombin-, hydrogen
peroxide- or E. coli hemolysin-induced hyperpermeability the
elevation of cyclic nucleotides did not block TcdB-related
permeability. The data demonstrate a central role of small GTP
-binding Rho proteins for the control of endothelial barrier function.
Received 20 May 1996; accepted in final form 23 August 1996.
APS Manuscript Number L142-6.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 19 September 1996