TY - JOUR T1 - Multiple Kinetics of Mitochondrial Cytochrome <em>c</em>Release in Drug-Induced Apoptosis JF - Molecular Pharmacology JO - Mol Pharmacol SP - 1008 LP - 1019 DO - 10.1124/mol.60.5.1008 VL - 60 IS - 5 AU - C. Marc Luetjens AU - Donat Kögel AU - Claus Reimertz AU - Heiko Düßmann AU - Andrea Renz AU - Klaus Schulze-Osthoff AU - Anna-Liisa Nieminen AU - Monika Poppe AU - Jochen H. M. Prehn Y1 - 2001/11/01 UR - http://molpharm.aspetjournals.org/content/60/5/1008.abstract N2 - We investigated cytochrome c release kinetics in response to three apoptosis-inducing agents (tumor necrosis factor-α, staurosporine, and valinomycin) in MCF-7/Casp-3 cells stably transfected with enhanced green fluorescent protein (EGFP)-tagged cytochrome c. All three agents induced significant caspase activation in the cultures determined by monitoring the cleavage of fluorigenic caspase substrates in extracts from drug-treated MCF-7/Casp-3 cells, albeit the valinomycin-induced activation was less pronounced. Time-lapse confocal microscopy showed that tumor necrosis factor-α and staurosporine caused rapid, one- or multiple-step release of cytochrome c-EGFP from mitochondria. In contrast, valinomycin-induced cytochromec-EGFP release occurred slowly over several hours. Unlike staurosporine, the valinomycin-induced cytochromec release was not associated with translocation of the proapoptotic Bax protein to the mitochondria, and was not accompanied by co-release of the proapoptotic Smac protein. Immunoprecipitation experiments revealed that cytochrome c was also released out of the cell into the extracellular space before loss of plasma membrane integrity. Our data indicate the existence of multiple kinetics of cytochrome c release in drug-induced apoptosis. ER -