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Altered cytochrome c display precedes apoptotic cell death in Drosophila.

Varkey J, Chen P, Jemmerson R, Abrams JM - J. Cell Biol. (1999)

Bottom Line: We found that an overt alteration in cytochrome c anticipates programmed cell death (PCD) in Drosophila tissues, occurring at a time that considerably precedes other known indicators of apoptosis.In cell-free studies, cytosolic caspase activation was triggered by mitochondria from apoptotic cells but identical preparations from healthy cells were inactive.Our observations provide compelling validation of an early role for altered cytochrome c in PCD and suggest propagation of apoptotic physiology through reciprocal, feed-forward amplification involving cytochrome c and caspases.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology and Neuroscience, University of Texas, Southwestern Medical Center, Dallas, Texas 75235-9039, USA.

ABSTRACT
Drosophila affords a genetically well-defined system to study apoptosis in vivo. It offers a powerful extension to in vitro models that have implicated a requirement for cytochrome c in caspase activation and apoptosis. We found that an overt alteration in cytochrome c anticipates programmed cell death (PCD) in Drosophila tissues, occurring at a time that considerably precedes other known indicators of apoptosis. The altered configuration is manifested by display of an otherwise hidden epitope and occurs without release of the protein into the cytosol. Conditional expression of the Drosophila death activators, reaper or grim, provoked apoptogenic cytochrome c display and, surprisingly, caspase activity was necessary and sufficient to induce this alteration. In cell-free studies, cytosolic caspase activation was triggered by mitochondria from apoptotic cells but identical preparations from healthy cells were inactive. Our observations provide compelling validation of an early role for altered cytochrome c in PCD and suggest propagation of apoptotic physiology through reciprocal, feed-forward amplification involving cytochrome c and caspases.

Show MeSH
Altered cytochrome c display is provoked by caspase  action. Drosophila cells transiently transfected with pMt-(Δ1–33)- dcp-1, a vector which expresses dcp-1 lacking its prodomain,  exhibited characteristically punctate labeling with mAb 2G8. B  illustrates apoptogenic cytochrome c display induced by expression of the activated dcp-1 caspase. A shows uninduced control  cells.
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Figure 7: Altered cytochrome c display is provoked by caspase action. Drosophila cells transiently transfected with pMt-(Δ1–33)- dcp-1, a vector which expresses dcp-1 lacking its prodomain, exhibited characteristically punctate labeling with mAb 2G8. B illustrates apoptogenic cytochrome c display induced by expression of the activated dcp-1 caspase. A shows uninduced control cells.

Mentions: The data above demonstrate that caspase activity is required for apoptogenic cytochrome c display. To determine if caspase function is sufficient to trigger this change, we induced apoptosis in SL2 cells by conditional expression of an activated version of the Drosophila caspase, dcp-1. If deleted for its prodomain, this caspase provokes considerable apoptosis in mammalian cells (Song et al., 1997) and SL2 cells (this paper). When labeled with mAb 2G8, cells transfected and induced for pMt-(Δ1–33)-dcp-1 expression exhibited profound punctate cytochrome c staining (Fig. 7 B) with features indistinguishable from those associated with expression of the death activators.


Altered cytochrome c display precedes apoptotic cell death in Drosophila.

Varkey J, Chen P, Jemmerson R, Abrams JM - J. Cell Biol. (1999)

Altered cytochrome c display is provoked by caspase  action. Drosophila cells transiently transfected with pMt-(Δ1–33)- dcp-1, a vector which expresses dcp-1 lacking its prodomain,  exhibited characteristically punctate labeling with mAb 2G8. B  illustrates apoptogenic cytochrome c display induced by expression of the activated dcp-1 caspase. A shows uninduced control  cells.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2132929&req=5

Figure 7: Altered cytochrome c display is provoked by caspase action. Drosophila cells transiently transfected with pMt-(Δ1–33)- dcp-1, a vector which expresses dcp-1 lacking its prodomain, exhibited characteristically punctate labeling with mAb 2G8. B illustrates apoptogenic cytochrome c display induced by expression of the activated dcp-1 caspase. A shows uninduced control cells.
Mentions: The data above demonstrate that caspase activity is required for apoptogenic cytochrome c display. To determine if caspase function is sufficient to trigger this change, we induced apoptosis in SL2 cells by conditional expression of an activated version of the Drosophila caspase, dcp-1. If deleted for its prodomain, this caspase provokes considerable apoptosis in mammalian cells (Song et al., 1997) and SL2 cells (this paper). When labeled with mAb 2G8, cells transfected and induced for pMt-(Δ1–33)-dcp-1 expression exhibited profound punctate cytochrome c staining (Fig. 7 B) with features indistinguishable from those associated with expression of the death activators.

Bottom Line: We found that an overt alteration in cytochrome c anticipates programmed cell death (PCD) in Drosophila tissues, occurring at a time that considerably precedes other known indicators of apoptosis.In cell-free studies, cytosolic caspase activation was triggered by mitochondria from apoptotic cells but identical preparations from healthy cells were inactive.Our observations provide compelling validation of an early role for altered cytochrome c in PCD and suggest propagation of apoptotic physiology through reciprocal, feed-forward amplification involving cytochrome c and caspases.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology and Neuroscience, University of Texas, Southwestern Medical Center, Dallas, Texas 75235-9039, USA.

ABSTRACT
Drosophila affords a genetically well-defined system to study apoptosis in vivo. It offers a powerful extension to in vitro models that have implicated a requirement for cytochrome c in caspase activation and apoptosis. We found that an overt alteration in cytochrome c anticipates programmed cell death (PCD) in Drosophila tissues, occurring at a time that considerably precedes other known indicators of apoptosis. The altered configuration is manifested by display of an otherwise hidden epitope and occurs without release of the protein into the cytosol. Conditional expression of the Drosophila death activators, reaper or grim, provoked apoptogenic cytochrome c display and, surprisingly, caspase activity was necessary and sufficient to induce this alteration. In cell-free studies, cytosolic caspase activation was triggered by mitochondria from apoptotic cells but identical preparations from healthy cells were inactive. Our observations provide compelling validation of an early role for altered cytochrome c in PCD and suggest propagation of apoptotic physiology through reciprocal, feed-forward amplification involving cytochrome c and caspases.

Show MeSH