title: Rotavirus infection induces an increase in intracellular calcium concentration in human intestinal epithelial cells: role in microvillar actin alteration.
abstract: 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 ([Ca(2+)](i)) in Caco-2 cells, since Ca(2+) is known to be a determinant factor for actin cytoskeleton regulation. As measured by quin2 fluorescence, viral replication induced a progressive increase in [Ca(2+)](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 [Ca(2+)](i) was related only to an increase in Ca(2+) permeability of plasmalemma. At a late stage of infection, [Ca(2+)](i) elevation was due to both extracellular Ca(2+) influx and Ca(2+) release from the intracellular organelles, mainly the endoplasmic reticulum (ER). We noted that at this time the [Ca(2+)](i) increase was partially related to a phospholipase C (PLC)-dependent mechanism, which probably explains the Ca(2+) 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 [Ca(2+)](i) of uninfected Caco-2 cells, by a PLC-dependent efflux of Ca(2+) from the ER and by extracellular Ca(2+) influx. These supernatants induced a Ca(2+)-dependent microvillar F-actin alteration in uninfected Caco-2 cells, thus participating in rotavirus pathogenesis.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, Unité 510, Pathogènes et Fonctions des Cellules Epithéliales Polarisées, Faculté de Pharmacie, Université Paris XI, 92296 Châtenay-Malabry cedex, France.
authors.forename: J P
authors.initials: JP
authors.lastname: Brunet
authors.forename: J
authors.initials: J
authors.lastname: Cotte-Laffitte
authors.forename: C
authors.initials: C
authors.lastname: Linxe
authors.forename: A M
authors.initials: AM
authors.lastname: Quero
authors.forename: M
authors.initials: M
authors.lastname: Géniteau-Legendre
authors.forename: A
authors.initials: A
authors.lastname: Servin
mesh_terms: D000199:Actins / Q000378:metabolism*; D018938:Caco-2 Cells / Q000821:virology*; D002118:Calcium / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects / Q000821:virology; D006801:Humans; D008871:Microvilli / Q000378:metabolism; D012401:Rotavirus; D010738:Type C Phospholipases / Q000378:metabolism; D014764:Viral Proteins / Q000494:pharmacology; D014779:Virus Replication
chemical_list: D000199:Actins; D014764:Viral Proteins; D010738:Type C Phospholipases; D002118:Calcium