Figure 7.

S. aureusα-toxin signals cell death and caspase activation independently of death receptor pathways. Assessment of cell death (A and B) and DEVDase activity (C and D) in Jurkat cells (•), Jurkat-R cells (▪), FADD-deficient Jurkat cells (▴), and caspase-8–deficient Jurkat cells (▾). Cells were incubated with increasing concentrations of RN6390 supernatant (A and C), anti-CD95 (B and D), or etoposide (D). (E) Western blot analyses demonstrating the activation of caspase-8 in Jurkat-R cells (top) and FADD-deficient cells (bottom) that were either left untreated (control) or incubated for 4 h with the indicated concentrations of α-toxin. As a control, cells were treated for 4 h with anti-CD95 or etoposide. The blots show the uncleaved precursor forms and the p43/p41 intermediate fragments of caspase-8.