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Horbach Marodin, Rafaela

University of British Columbia

Genome stability is crucial for the proper functioning of all living organisms. In eukaryotes, genome stability is safeguarded by an intricate network of mechanisms that detect DNA damage and mediate its repair. This network, termed the DNA damage response, ensures the integrity of the genome and its accurate transmission to daughter cells. Defects in DNA damage response mechanisms can result in unrepaired DNA damage, ultimately leading to the onset of genetic diseases. Several proteins have been shown to participate in the DNA damage response, including cohesin, a multi-protein complex that functions together with a collection of cohesion auxiliary factors. The full extent to which cohesin participates in the DNA damage response to maintain genome stability remains to be defined and is of great importance since cohesin mutations are associated with a variety of cancer types. Genetic interaction networks can provide insights into the involvement of genes in biological processes and can identify potential targets for therapeutic inhibition. This approach exploits the concept of synthetic lethality, which is a type of genetic interaction in which two individual genetic perturbations are viable but combining the perturbations results in lethality. Another type of genetic interaction, termed synthetic cytotoxicity, results in severe sensitivity to genotoxic agents that induce DNA damage. We used the synthetic genetic array methodology in Saccharomyces cerevisiae to generate synthetic lethal and synthetic cytotoxic interaction networks using cohesin mutations as query genes to identify DNA damage response factors that genetically interact with the cohesin complex. Retesting studies using spot assays found that cells expressing hypomorphic cohesin alleles were dependent on factors involved in DNA damage checkpoint, HR inhibition, and DNA damage tolerance, and that cohesin-defective cells rely on translesion synthesis for viability upon replication stress. Using missense mutations that abolish the catalytic activity of translesion synthesis polymerases in a manner to mimic the effect of therapeutic inhibition, we showed that dominant mutant forms of Rad30 and Rev3 are synthetic cytotoxic with several DNA damage response mutants, including cohesin. Overall, these data highlight the utility of yeast to expand our knowledge of functional genomics and to identify potential targets for anti-cancer treatments.

Text

2022-10-19

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/82911

Medical Genetics

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/