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Cell Cycle Analysis in the C. elegans Germline with the Thymidine Analog EdU
Published on: October 22, 2018
The EEL-1 ubiquitin ligase promotes DNA damage-induced germ cell apoptosis in C. elegans
1Developmental and Stem Cell Biology Program, Hospital for Sick Children, Toronto, Ontario, Canada.
Abstract:
E3 ubiquitin ligases target a growing number of pro- and anti-apoptotic proteins, including tumour suppressor p53, caspases, and the Bcl-2 family. The core apoptosis pathway is well conserved between mammals and Caenorhabditis elegans, but the extent to which ubiquitin ligases regulate apoptotic cell death is not known. To investigate the role of E3 ligases in apoptosis, we inhibited 108 of the 165 predicted E3 ubiquitin ligase genes by RNA interference and quantified apoptosis in the C. elegans germline after genotoxic stress. From this screen, we identified the homologous to E6-associated protein C terminus-domain E3 ligase EEL-1 as a positive regulator of apoptosis. Intriguingly, the human homologue of EEL-1, Huwe1/ARF-BP1/Mule/HectH9, has been reported to possess both pro- and anti-apoptotic functions through its ability to stimulate Mcl-1 and p53 degradation, respectively. Here, we demonstrate that eel-1 is required to promote DNA damage-induced germ cell apoptosis, but does not have a role in physiological germ cell apoptosis or developmental apoptosis in somatic tissue. Furthermore, eel-1 acts in parallel to the p53-like gene cep-1 and intersects the core apoptosis pathway upstream of the Bcl-2/Mcl-1 orthologue ced-9. Although ee1-1 mutants exhibit hypersensitivity to genotoxic stress they do not appear to be defective in DNA repair, suggesting a distinct role for EEL-1 in promoting damage-induced apoptosis in the germline.
Insights
E3 ubiquitin ligase EEL-1 promotes DNA damage-induced apoptosis in C. elegans germ cells. This study identifies EEL-1 as crucial for germline cell death following genotoxic stress.
Area of Science:
- Cell Biology
- Genetics
- Molecular Biology
Background:
- E3 ubiquitin ligases regulate apoptosis by targeting key proteins like p53 and Bcl-2 family members.
- The role of E3 ligases in apoptosis is conserved but not fully understood across species.
- Apoptosis pathways are critical for development and tissue homeostasis.
Purpose of the Study:
- To investigate the function of E3 ubiquitin ligases in regulating apoptosis.
- To identify specific E3 ligases involved in DNA damage-induced cell death.
- To elucidate the role of EEL-1 in the apoptosis pathway in Caenorhabditis elegans.
Main Methods:
- Conducted a large-scale RNA interference screen of E3 ubiquitin ligase genes in C. elegans.
- Quantified apoptosis in the germline following genotoxic stress.
- Analyzed the genetic interactions of eel-1 with known apoptosis regulators like cep-1 and ced-9.
Main Results:
- Identified EEL-1 as a positive regulator of apoptosis in the C. elegans germline.
- Demonstrated that eel-1 is specifically required for DNA damage-induced germ cell apoptosis.
- Found that eel-1 acts in parallel to cep-1 and upstream of ced-9, suggesting a distinct role in the apoptosis pathway.
- eel-1 mutants showed hypersensitivity to genotoxic stress but no apparent DNA repair defects.
Conclusions:
- EEL-1 plays a critical role in promoting germ cell apoptosis in response to DNA damage.
- EEL-1's function is specific to genotoxic stress-induced apoptosis in the germline, not physiological or developmental apoptosis.
- EEL-1 represents a novel component of the DNA damage response pathway, acting upstream of core apoptotic regulators.
