Release of cytochrome c from mitochondria precedes Bax translocation/activation in Triton X-100-induced apoptosis

The precise mechanisms by which sublytic concentrations of detergents induce apoptosis remain unclear. Recent studies reported the ability of nonionic detergents such as Triton X-100 to induce conformational change of Bax to the active form in vitro. Here we investigated whether activation of Bax might play a role in Triton X-100-induced apoptosis in cells. Although Bax translocation/activation was inhibited by caspase inhibitors, cytochrome c release from mitochondria was not affected in Triton X-100-induced apoptosis in U-937 cells. These results demonstrate that translocation/activation of Bax occurs downstream of cytochrome c release and caspase activation in Triton X-100-induced apoptosis.