CYTOCHROME-C RELEASE AND CASPASE ACTIVATION IN HYDROGEN PEROXIDE-INDUCED AND TRIBUTYLTIN-INDUCED APOPTOSIS

The ability of H2O2 and tributyltin (TBT) to trigger pro-caspase activ ation via export of cytochrome c from mitochondria to the cytoplasm wa s investigated, Treatment of Jurkat T lymphocytes with H2O2 resulted i n the appearance of cytochrome c in the cytosol within 2 h. This was a t least 1 h before caspase activation was observed. TBT caused cytochr ome c release already after 5 min, followed by caspase activation with in 1 h, Measurement of mitochondrial membrane potential (Delta Psi(m)) showed that both H2O2 and TBT dissipated Delta Psi(m), but with diffe rent time courses. TBT caused a concomitant loss of Delta Psi(m) and r elease of cytochrome c, whereas cytochrome c release and caspase activ ation preceded and apparent Delta Psi(m) loss in H2O2-treated cells, T hus, our results suggest that different mechanisms are involved in tri ggering cytochrome c release with these apoptosis-inducing agents. (C) 1998 Federation of European Biochemical Societies.