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Mitotic block and delayed lethality in HeLa epithelial cells exposed to Escherichia coli BM2-1 producing cytotoxic necrotizing factor type 1

Rycke, Jean de and Mazars, Philippe and Nougayrède, Jean-Philippe and Tasca, Christian and Boury, Michèle and Herault, Frédéric and Valette, Annie and Oswald, Eric Mitotic block and delayed lethality in HeLa epithelial cells exposed to Escherichia coli BM2-1 producing cytotoxic necrotizing factor type 1. (1996) Infection and immunity, 6 (5). 1694-705. ISSN 0019-9567

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Official URL: http://iai.asm.org/cgi/reprint/64/5/1694


The cytopathic effect (CPE) of Escherichia coli producing cytotoxic necrotizing factor type 1 (CNF1) was investigated by using a human epithelial cell (HeLa) model of infection with CNF1-producing E. coli BM2-1. This strain was shown to bind loosely, but massively, to HeLa cells. A 4-h interaction between bacteria and eukaryotic cells triggered the delayed appearance of a progressive dose-dependent CPE characterized by (i) intense swelling of cells accompanied by the formation of a dense network of actin stress fibers, (ii) inhibition of cell division due to a complete block in the G2 phase of the cell cycle, and (iii) nucleus swelling and chromatin fragmentation. These alterations resulted in cell death starting about 5 days after interaction. The absence of multinucleation clearly distinguished the CPE from the effect produced by cell-free culture supernatants of infected cells nor prevented by a CNF1-neutralizing antiserum. Pathogenicity was completely abolished after Tn5::phoA insertion mutagenesis in the cnf-1 structural gene but not restored by trans complementation with a recombinant plasmid containing intact cnf-1 and its promoter. These results suggest that a gene downstream of cnf-1, essential to the induction of the CPE, was affected by the mutation. On the other hand, transformation of the wild-type strain BM2-1 with the same recombinant plasmid leads to a significant increase in both CNF1 activity and CPE, demonstrating the direct contribution of CNF1 to the CPE. In conclusion, the pathogenicity of E. coli BM2-1 for HeLa cells results from a complex interaction involving cnf-1 and associated genes and possibly requiring a preliminary step of binding of bacterial organisms to target cells.

Item Type:Article
Additional Information:Thanks to American Society for Microbiology. The definitive version is available at http://iai.asm.org The original PDF of the article can be found at Infection and immunity website : http://iai.asm.org/cgi/reprint/64/5/1694
Audience (journal):International peer-reviewed journal
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Institution:French research institutions > Institut National de la Recherche Agronomique - INRA (FRANCE)
Université de Toulouse > Ecole Nationale Vétérinaire de Toulouse - ENVT (FRANCE)
French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
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Deposited On:23 Jul 2008 08:48

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