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Journal of Virology, March 2000, p. 2323-2332, Vol. 74, No. 5
Institut National de la Santé et de la
Recherche Médicale, Unité 510, Pathogènes et
Fonctions des Cellules Épithéliales Polarisées,
Faculté de Pharmacie, Université Paris XI, 92296 Châtenay-Malabry cedex, France
Received 14 September 1999/Accepted 6 December 1999
Rotaviruses, which infect mature enterocytes of the small
intestine, are recognized as the most important cause of viral
gastroenteritis in young children. We have previously reported that
rotavirus infection induces microvillar F-actin disassembly in human
intestinal epithelial Caco-2 cells (N. Jourdan, J. P. Brunet, C. Sapin, A. Blais, J. Cotte-Laffitte, F. Forestier, A. M. Quero, G. Trugnan, and A. L. Servin, J. Virol. 72:7228-7236, 1998). In
this study, to determine the mechanism responsible for
rotavirus-induced F-actin alteration, we investigated the effect of
infection on intracellular calcium concentration
([Ca2+]i) in Caco-2 cells, since
Ca2+ is known to be a determinant factor for actin
cytoskeleton regulation. As measured by quin2 fluorescence, viral
replication induced a progressive increase in
[Ca2+]i from 7 h postinfection, which
was shown to be necessary and sufficient for microvillar F-actin
disassembly. During the first hours of infection, the increase in
[Ca2+]i was related only to an increase in
Ca2+ permeability of plasmalemma. At a late stage of
infection, [Ca2+]i elevation was due to both
extracellular Ca2+ influx and Ca2+ release from
the intracellular organelles, mainly the endoplasmic reticulum (ER). We
noted that at this time the [Ca2+]i increase
was partially related to a phospholipase C (PLC)-dependent mechanism,
which probably explains the Ca2+ release from the ER. We
also demonstrated for the first time that viral proteins or peptides,
released into culture supernatants of rotavirus-infected Caco-2 cells,
induced a transient increase in [Ca2+]i of
uninfected Caco-2 cells, by a PLC-dependent efflux of Ca2+
from the ER and by extracellular Ca2+ influx. These
supernatants induced a Ca2+-dependent microvillar F-actin
alteration in uninfected Caco-2 cells, thus participating in rotavirus pathogenesis.
0022-538X/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Rotavirus Infection Induces an Increase in
Intracellular Calcium Concentration in Human Intestinal Epithelial
Cells: Role in Microvillar Actin Alteration
*
Corresponding author. Mailing address: INSERM U-510,
Faculté de Pharmacie, 5 rue J. B. Clément, 92296 Châtenay-Malabry cedex, France. Phone and fax: 33-1 46 83 56 61. E-mail: alain.servin{at}cep.u-psud.fr.
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