Infect. Immun., Sep 1997, 3774-3780, Vol 65, No. 9
Copyright © 1997, American Society for Microbiology
V Aragon, K Chao and LA Dreyfus
Division of Cell Biology and Biophysics, University of Missouri-Kansas City, 64110, USA.
Cytolethal distending toxin (CDT) is a newly described toxin produced by a number of enteropathogens, including Campylobacter jejuni, various Escherichia coli strains, and a few Shigella species. CDT induces distension and eventual death of a number of transformed cell lines. Here, we extend previous studies by demonstrating that morphological changes in CDT-treated Chinese hamster ovary cells are coincident with changes in cytoskeletal structure and an inhibition of cell proliferation. CDT-treated cells underwent a progressive accumulation of F-actin assemblies which microscopically resembled actin stress fibers. Accumulation of the stress fiber-like structures in CDT-treated cells was accompanied by an apparent blockage of cell division. Multinucleation was detected in some cells but did not constitute a significant feature of CDT action. Although toxin-treated cells failed to divide, cell viability remained high for the first 4 days following toxin treatment, as evidenced by trypan blue exclusion and neutral red uptake. [3H]thymidine incorporation studies on CDT-treated cells were consistent with a blockage of cell proliferation without a direct inhibition of DNA synthesis. Although the progression of toxin action developed slowly, a 2-min exposure to CDT resulted in an irreversible development of toxicity. Together, our data indicate that CDT affects F- actin assembly within target cells and may interrupt the regulation or function of cell cycle-dependent events leading to cytokinesis.
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