Study on induction of apoptosis on HeLa and Vero cells by recombinant shiga toxin and its subunits

Abstract

Verotoxin (VT) or shiga toxin (Stx) produced by enterohemorrhagic Escherichia coli (EHEC) and Shigella dysenteriae is AB5 holotoxin with potent protein synthesis inhibitor. VT can induce both apoptosis and necrosis depending on the cell type, it has been shown that VT-induced apoptosis and cytotoxicity are distinct processes, and the A subunit can be necessary for apoptosis. In other words, the precise role of each subunit in apoptosis signaling has yet to be established. In this study, induction of apoptosis has been examined by using both recombinant A and B subunits, and recombinant Stx (rStx) with different doses in HeLa and Vero cells. For this purpose, the polymyxin B extract of constructs expressing A, B and AB5 recombinant proteins was used. Therefore, amounts greater than normally reported were used to induce desire effects on cell lines. The apoptotic effect of A and B subunits appear at higher doses than that of rStx. The highest apoptotic effect was observed for rStx at low concentration, compared to A and B subunits. A or B subunits separately cannot induce the signaling pathway stimulated by holotoxin though A subunit, does induce laddering pattern similar to holotoxin. We concluded that both subunits are important in complete death signaling pathway. Since different concentration of A and B subunits and rStx was required in different assay, therefore, it could be emphasized that cell death or even apoptosis caused by either of the subunits or holotoxin depends on sensitivity or specificity of the assay and cell types used.

Isothiocyanates as effective agents against enterohemorrhagic Escherichia coli: insight to the mode of action

“…Measurement of bacterial lysate toxicity to human and simian cell lines was carried out as described previously 26 15 . Briefly, cell lines were cultivated in DMEM medium (Dulbecco, Gibco), pH 7.4, supplemented with 10% heat-inactivated fetal bovine serum (FBS), antibiotic and antimycotic solution (all purchased from Sigma, Germany), and incubated at 37 °C in a humidified 5% CO 2 atmosphere.…”

Phenethyl Isothiocyanate Inhibits Shiga Toxin Production in Enterohemorrhagic Escherichia coli by Stringent Response Induction

“…When prophage induction occurs in E. coli capable of Shiga toxin production, lysates of such bacterial cultures are toxic for human and simian cells (HeLa or Vero cell lines are routinely used in such tests [41]). Therefore, we tested whether PEITC can alleviate the toxicity of lysates of induced lysogens of STEC (the O157:H7 strain bearing a prophage ST2-8624 with native stx genes).…”

Inhibition of Cytotoxicity of Shiga Toxin of Escherichia coli O157:H7 on Vero Cells by Prosopis alba Griseb (Fabaceae) and Ziziphus mistol Griseb (Rhamnaceae) Extracts

“…Cell death by apoptosis provoked by Stx depends on the cell type and varies with the sensitivity or specificity of the assay used (6). Related to this, the capacity of Stx to induce apoptosis has been reported in different cell types, such as Vero cells (15), human renal proximal tubular epithelial cells (19), and human renal cortical epithelial cells (16).…”