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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.

Abstract：

: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.

journal_name

Infect Immun

journal_title

Infection and immunity

authors

De Rycke J,Mazars P,Nougayrede JP,Tasca C,Boury M,Herault F,Valette A,Oswald E

doi

10.1128/IAI.64.5.1694-1705.1996

subject

Has Abstract

pub_date

1996-05-01 00:00:00

pages

1694-705

issue

eissn

0019-9567

issn

1098-5522

journal_volume

pub_type

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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.