Figure 9.
S. aureusα-toxin induces cytochrome c release in intact cells and isolated mitochondria in a Bcl-2–controlled manner. (A) Western blot analysis of cytosolic cytochrome c in Jurkat cells treated for the indicated times with 0.03 μg/ml α-toxin or for 8 h with 1 μg/ml staurosporine (Stauro). (B) Effect of α-toxin on isolated mitochondria. Isolated mitochondria from Jurkat (lanes 1–7) or from Bcl-2–overexpressing Jurkat cells (lanes 8–14) were incubated for 30 min with a buffer control (lanes 2 and 9), 10 μg/ml betulinic acid (lanes 3 and 10), or the indicated concentrations of α-toxin (lanes 4–7 and 11–14). The release of cytochrome c was detected by immunoblotting. Lanes 1 and 8 (total mitos) represent the complete amount of cytochrome c present in mitochondria from Jurkat and Jurkat Bcl-2 cells, respectively. (C) Measurement of the mitochondrial transmembrane potential (ΔΨm) in untreated (Control) Jurkat and Jurkat Bcl-2 cells or in cells treated for 4 h with etoposide or the indicated concentrations of α-toxin.