Mechanisms of pertussis toxin-induced barrier dysfunction in bovine
pulmonary artery endothelial cell monolayers .
Patterson, Carolyn E., Ph. D., Jerome E. Stasek, M. D., Kane L. Schaphorst, M.
D., Harold W. Davis, Ph. D. and Joe G. N. Garcia, M. D.
Department of Medicine, Indiana University School of Medicine and Richard
L. Roudebush Veterans Administration Medical Center, Indianapolis, Indiana
46202
APStracts 2:0005L, 1995.
We have previously characterized several G proteins in endothelial cells (EC)
as substrates for the ADP-ribosyltransferase activity of both pertussis (PT)
and cholera toxin and described the modulation of key EC physiologic
responses, including gap formation and barrier function, by these toxins. In
this study, we investigated the mechanisms involved in PT-mediated regulation
of BPAEC barrier function. PT caused a dose-dependent increase in albumin
transfer, dependent upon action of the holotoxin since neither the heat
-inactivated PT, the isolated oligomer, nor the protomer induced EC
permeability. PT-induced gap formation and barrier dysfunction was additive
to either thrombin- or thrombin receptor activating peptide-induced
permeability, suggesting that thrombin and PT utilize distinct mechanisms. PT
did not result in Ca2+ mobilization or alter either basal or thrombin-induced
myosin light chain phosphorylation. However, PT stimulated PKC activation and
both PKC downregulation and PKC inhibition attenuated PT-induced permeabili
ty, indicating that PKC activity is involved in PT-induced barrier
dysfunction. Like thrombin-induced permeability, the PT effect was blocked by
prior increases in cAMP. Thus, PT catalyzed ADP-ribosylation of a G protein
(possibly other than Gi) may regulate cytoskeletal protein interactions,
leading to EC barrier dysfunction.
Received 15 September 1994; accepted in final form 13 January 1995.
APS Manuscript Number L274-4.
Article publication pending Am. J. Physiol. (Lung Cell. Mol. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 24 February 1995.