Cytochrome c release from mitochondria of early postimplantation murine embryos exposed to 4-hydroperoxycyclophosphamide, heat shock, and staurosporine.
Cell death is an early and common event in the pathogenesis associated with the abnormal development induced by a variety of teratogens. Previously, we showed that the cell death induced in day 9 mouse embryos by three teratogens, hyperthermia (HS), 4-hydroperoxycyclophosphamide (4-CP), and sodium arsenite (As), is apoptotic in nature involving the activation of caspase-3, cleavage of poly(ADP-ribose) polymerase (PARP), and DNA fragmentation. We now show that HS, 4-CP, and staurosporine (ST) induce the release of cytochrome c from mitochondria with kinetics suggesting a causal relationship with the activation of caspase-3 and caspase-2. This causal relationship is supported by data showing that procaspase-3 and -2 can be activated in vitro by the addition of cytochrome c to a S-100 fraction prepared from control day 9 embryos. Together, these data support the notion that these three teratogens induce changes in embryonic mitochondria resulting in the release of cytochrome c and the subsequent activation of caspase-9, the upstream activator of caspase-3. Previously, we also showed that cells within the day 9 mouse embryo are differentially sensitive/resistant to the cell death-inducing potential of HS, 4-CP, and As. The most dramatic example of this differential sensitivity is the complete resistance of heart cells, characterized by the lack of caspase-3 activation, PARP cleavage, and DNA fragmentation. We now show that this block in the terminal phase of the apoptotic pathway in heart cells is associated with a lack of teratogen-induced release of cytochrome c. Together, our data indicate that mitochondria play a pivotal role in cell death during the early phases of teratogenesis.
Mirkes
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PE
Birth Defects Research Laboratory, University of Washington, Seattle, Washington, 98195, USA.
Little
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SA
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D020169:Caspases / Q000378:metabolism; D046508:Culture Techniques; D003520:Cyclophosphamide / Q000031:analogs & derivatives* / Q000633:toxicity; D003574:Cytochrome c Group / Q000378:metabolism*; D053938:DNA Fragmentation; D010064:Embryo Implantation / Q000502:physiology*; D004622:Embryo, Mammalian; D004789:Enzyme Activation; D005260:Female; D006979:Hyperthermia, Induced / Q000009:adverse effects*; D008297:Male; D051379:Mice; D008928:Mitochondria / Q000201:enzymology / Q000378:metabolism*; D009206:Myocardium / Q000166:cytology; D011247:Pregnancy; D019311:Staurosporine / Q000633:toxicity*; D013723:Teratogens / Q000633:toxicity*
D003574:Cytochrome c Group; D013723:Teratogens; D003520:Cyclophosphamide; D020169:Caspases; D019311:Staurosporine; C011272:perfosfamide