Caspase7

Pro-caspase9 Caspase9

Caspases play a key role during apoptotic execution. In an attempt to elucidate the specific role of caspase-7 we generated a chicken DT40 cell line in which both alleles of the gene were disrupted. Viability assays showed that caspase-7 -/- clones are more resistant to the common apoptosis-inducing drugs etoposide and staurosporine. Caspase-7 -/- cells show a delay in phosphatidylserine externalization and DNA fragmentation as well as cleavage of the caspase substrates PARP and lamins B1 and B2. Caspase affinity labeling and activity assays indicated that deficient cells exhibit a delay in caspase activation when compared to wild type DT40 cells, providing an explanation for the differences in apoptotic execution between caspase-7 null and wild type DT40 cells. These results strongly suggest that caspase-7 is involved earlier than other effector caspases in the apoptotic execution process in DT40 B lymphocytes.l