Figure 5

Apoptosis in bile acid-treated CHO.asbt.35 cells. (A) Cells were treated with various bile acids (100 μM) for 2 h, and then caspase 8 activity was assayed in cellular extracts using the caspase 8 fluorogenic substrate, Z-IETD-AFC. Both glycine- and taurine-conjugated bile acids induced the activation of caspase 8 in CHO.asbt.35 cells (dark bars), but not in CHO cells (white bars). Caspase 8 activity in GCDCA-treated cells inhibited in vitro by addition of the caspase 8 inhibitor Ac-IETD-cho to the cell extracts (right most bar, panel A). The basal level of caspase 8 activity in untreated cells is also shown by the (left most pair of bars, panel A). The values shown are mean ± SD (n = 3) and are representative of several experiments. (B) Fragmentation of genomic DNA in bile acid-treated CHO.asbt.35 cells. The cells were incubated with 50 μM taurine- or glycine-conjugated bile acids for 3 h. Both classes of conjugated bile acids induced DNA laddering in CHO.asbt.35 cells. Original magnification = 400X. These experiments were repeated three times with similar results.