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Distinct cell killing properties of the Drosophila reaper, head involution defective, and grim genes
J P Wing1, L Zhou, L M Schwartz
1Biology Department, Morrill Science Center, University of Massachusetts, Amherst 01003, USA.
Abstract:
The Drosophila reaper, head involution defective (hid), and grim genes play key roles in regulating the activation of programmed cell death. Two useful systems for studying the functions of these genes are the embryonic CNS midline and adult eye. In this study we use the Gal4/UAS targeted gene expression system to demonstrate that unlike reaper or hid, expression of grim alone is sufficient to induce ectopic CNS midline cell death. We also show that in both the midline and eye, grim-induced cell death is not blocked by the Drosophila anti-apoptosis protein Diap2, which does block both reaper- and hid-induced cell death. grim can also function synergistically with reaper or hid to induce higher levels of midline cell death than observed for any of the genes individually. Finally we analyzed the function of a truncated Reaper-C protein which lacks the NH2-terminal 14 amino acids that are conserved between Reaper, Hid, and Grim. Ectopic expression of Reaper-C revealed cell killing activities distinct from full length Reaper, and indicated that the conserved NH2-terminal domain acts in part to modulate Reaper activity.
Insights
The grim gene alone triggers programmed cell death in Drosophila, unlike reaper or head involution defective (hid). Grim-induced cell death is resistant to Diap2 inhibition, highlighting its unique role in apoptosis regulation.
Area of Science:
- Molecular Biology
- Genetics
- Developmental Biology
Background:
- Programmed cell death (apoptosis) is crucial for development and tissue homeostasis.
- The Drosophila reaper, head involution defective (hid), and grim genes are key regulators of apoptosis.
- Studying these genes in the embryonic CNS midline and adult eye provides insights into apoptosis control.
Purpose of the Study:
- To investigate the distinct roles of grim, reaper, and hid in inducing programmed cell death in Drosophila.
- To determine the susceptibility of grim-induced cell death to inhibition by Diap2.
- To analyze the synergistic effects of grim with reaper or hid and the function of a truncated Reaper protein.
Main Methods:
- Utilized the Gal4/UAS targeted gene expression system in Drosophila.
- Examined gene function in embryonic CNS midline and adult eye tissues.
- Assessed cell death induction and inhibition by Diap2.
Main Results:
- Expression of grim alone induced ectopic CNS midline cell death, unlike reaper or hid.
- Grim-induced cell death was resistant to the Drosophila anti-apoptosis protein Diap2.
- Grim functioned synergistically with reaper or hid to enhance midline cell death.
- A truncated Reaper-C protein exhibited distinct cell-killing activities, suggesting the N-terminal domain modulates Reaper function.
Conclusions:
- Grim possesses unique properties in initiating programmed cell death, distinct from reaper and hid.
- The conserved N-terminal domain of Reaper plays a role in modulating its apoptotic activity.