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Published on: March 15, 2019
Apoptosis in Drosophila: neither fish nor fowl (nor man, nor worm)
Sally Kornbluth1, Kristin White
1Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA. kornb001@mc.duke.edu
Abstract:
Studies in a wide variety of organisms have produced a general model for the induction of apoptosis in which multiple signaling pathways lead ultimately to activation of the caspase family of proteases. Once activated, these enzymes cleave key cellular substrates to promote the orderly dismantling of dying cells. A broad similarity exists in the cell death pathways operating in different organisms and there is a clear evolutionary conservation of apoptotic regulators such as caspases, Bcl-2 family members, inhibitor of apoptosis (IAP) proteins, IAP antagonists and caspase activators. Despite this, studies in Caenorhabditis elegans, Drosophila and vertebrates have revealed some apparent differences both in the way apoptosis is regulated and in the way individual molecules contribute to the propagation of the death signal. For example, whereas cytochrome c released from mitochondria clearly promotes caspase activation in vertebrates, there is no documented role for cytochrome c in C. elegans apoptosis and its role in Drosophila is highly controversial. In addition, the apoptotic potency of IAP antagonists appears to be greater in Drosophila than in vertebrates, indicating that IAPs may be of different relative importance in different organisms. Thus, although Drosophila, worms and humans share a host of apoptotic regulators, the way in which they function may not be identical.
Insights
Cell death pathways show evolutionary conservation across organisms, but molecular mechanisms of apoptosis differ. Key regulators like caspases are conserved, yet their precise roles and regulation vary between species.
Area of Science:
- Cell Biology
- Evolutionary Biology
- Genetics
Background:
- Apoptosis, or programmed cell death, is a fundamental biological process conserved across many organisms.
- A general model for apoptosis involves caspase activation through various signaling pathways, leading to cellular dismantling.
- Key apoptotic regulators, including caspases, Bcl-2 family members, and inhibitor of apoptosis (IAP) proteins, exhibit evolutionary conservation.
Purpose of the Study:
- To compare and contrast the regulation and molecular mechanisms of apoptosis across different species.
- To investigate the functional similarities and differences in apoptotic pathways, particularly concerning conserved regulators.
- To highlight variations in the roles of specific molecules, such as cytochrome c and IAP antagonists, in mediating cell death.
Main Methods:
- Comparative analysis of existing studies on apoptosis in model organisms (Caenorhabditis elegans, Drosophila, vertebrates).
- Review of literature focusing on the evolutionary conservation and functional divergence of apoptotic regulators.
- Examination of specific molecular players, including cytochrome c and IAP antagonists, in different species' death pathways.
Main Results:
- While core apoptotic machinery is conserved, significant differences exist in pathway regulation and molecular function across organisms.
- Cytochrome c's role in promoting caspase activation is established in vertebrates but absent or controversial in C. elegans and Drosophila.
- The relative importance and potency of IAP antagonists appear to vary, suggesting differential roles for IAPs in apoptosis regulation.
Conclusions:
- Despite shared apoptotic regulators, the precise mechanisms and functional outcomes of apoptosis are not identical across species.
- Understanding these inter-species variations is crucial for a comprehensive view of cell death processes.
- Further research is needed to elucidate the specific functional nuances of apoptotic pathways in diverse organisms.
