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Updated: Jul 20, 2026
Optogenetic Random Mutagenesis Using Histone-miniSOG in C. elegans
Published on: November 14, 2016
Mutator phenotype of Caenorhabditis elegans DNA damage checkpoint mutants
Jasper Harris1, Mia Lowden, Iuval Clejan
1Department of Biology, University of North Carolina, NC 27599-3280, USA.
Abstract:
DNA damage response proteins identify sites of DNA damage and signal to downstream effectors that orchestrate either apoptosis or arrest of the cell cycle and DNA repair. The C. elegans DNA damage response mutants mrt-2, hus-1, and clk-2(mn159) displayed 8- to 15-fold increases in the frequency of spontaneous mutation in their germlines. Many of these mutations were small- to medium-sized deletions, some of which had unusual sequences at their breakpoints such as purine-rich tracts or direct or inverted repeats. Although DNA-damage-induced apoptosis is abrogated in the mrt-2, hus-1, and clk-2 mutant backgrounds, lack of the apoptotic branch of the DNA damage response pathway in cep-1/p53, ced-3, and ced-4 mutants did not result in a Mutator phenotype. Thus, DNA damage checkpoint proteins suppress the frequency of mutation by ensuring that spontaneous DNA damage is accurately repaired in C. elegans germ cells. Although DNA damage response defects that predispose humans to cancer are known to result in large-scale chromosome aberrations, our results suggest that small- to medium-sized deletions may also play roles in the development of cancer.
Insights
DNA damage response proteins in C. elegans suppress mutations by ensuring accurate DNA repair. Defects in these pathways can lead to deletions, potentially contributing to cancer development.
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- DNA damage response (DDR) proteins are crucial for detecting DNA lesions and initiating cellular responses like apoptosis, cell cycle arrest, and DNA repair.
- Defects in DDR pathways are linked to genomic instability and diseases such as cancer in humans.
Purpose of the Study:
- To investigate the role of specific DNA damage response mutants (mrt-2, hus-1, clk-2) in C. elegans germline mutation frequency.
- To determine if the apoptotic branch of the DDR pathway influences the mutator phenotype.
Main Methods:
- Analysis of spontaneous mutation frequency in C. elegans germlines of wild-type and mutant strains (mrt-2, hus-1, clk-2).
- Characterization of mutation types, including analysis of breakpoint sequences.
- Comparison of mutation frequencies in DDR mutants with and without functional apoptotic pathways (cep-1/p53, ced-3, ced-4).
Main Results:
- C. elegans mutants mrt-2, hus-1, and clk-2 exhibited significantly increased spontaneous germline mutation rates (8- to 15-fold).
- Mutations frequently involved small- to medium-sized deletions with unusual breakpoint sequences (e.g., purine-rich tracts, repeats).
- Disruption of the apoptotic DDR pathway (cep-1/p53, ced-3, ced-4) did not cause a mutator phenotype, indicating the checkpoint's role in repair, not apoptosis, suppresses mutation.
Conclusions:
- DNA damage checkpoint proteins in C. elegans suppress mutation frequency by promoting accurate repair of spontaneous DNA damage in germ cells.
- While human cancer is linked to large chromosomal aberrations from DDR defects, small- to medium-sized deletions may also contribute to cancer development.
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