TRAIL causes cleavage of bid by caspase-8 and loss of mitochondrial membrane potential resulting in apoptosis in BJAB cells

A new member of the TNF family, tumor necrosis factor-related apoptosis-ind ucing ligand (TRAIL), has been shown to induce apoptosis. However, the mech anism for TRAIL-induced apoptosis remains to be clarified. SDS-PAGE and Wes tern blot analysis showed that cleavage of Bid was induced by a 1-h incubat ion of BJAB cells with TRAIL and was blocked by a caspase-8 inhibitor. Flow cytometry demonstrated that loss of mitochondrial membrane potential in BJ AB cells began about 1.5 h after the treatment with TRAIL and was apparent at 2 h in comparison with the control. DNA ladder formation, which is chara cteristic for apoptosis, in the cells treated with TRAIL was detected at 2 h and observed most effectively at 3 h. The time course study suggests that TRAIL causes cleavage of Bid via activation of caspase-8, subsequently the loss of mitochondrial membrane potential, resulting in apoptosis in BJAB c ells. (C) 1999 Academic Press.