[The apoptosis of vero cells induced by Shiga toxin 2e].

OBJECTIVE

Shiga-like toxin-producing Escherichia coli (STEC) causes edema disease in piglets and hemolytic uremic syndrome in human. Shiga-like toxins (Stxs) produced by STEC induce mammalian cells death via either necrosis or apoptosis. However, the ability of stx2e, separated from edema disease (Stx2e), to trigger apoptosis and the sequence of intracellular signaling events have not yet been completely defined. In this study we investigated the apoptotic effects of Stx2e on Vero cells.

METHODS

Vero cells were treated with different concentrations of Stx2e for different time and the apoptotic cells were characterized by acridine orange and ethidium bromide fluorescent dye staining. The fragmentation of chromatin from Vero cells treated with Stx2e were detected by agarose gel electrophoresis. The expression patterns of apoptosis-associated factors were assayed by Western blotting.

RESULTS

Stx2e-treated cells showed characteristic features of apoptosis, including membrane blebbing, DNA fragmentation, chromatin condensation, and the formation of apoptotic bodies, whereas ricin did not induce apoptosis of Vero cells even at a high dose. Fluorescent dye staining showed that Stx2e induced apoptosis of Vero cells in dose- and time-dependent manners. Caspase-3 was activated whereas expression levels of bcl2 associated X protein (Bax) and caspase-9 had no change compared with the negative control.

CONCLUSION

Stx2e induced intensively apoptosis of Vero cells, which was mediated through the mitochondrion-independent pathway and might be throught a receptor-dependent pathway.