A Functional Genomics Approach in Yeast: The Role of DNA repair in Trichloroethylene Toxicity

Trichloroethylene (TCE) is a common drinking water contaminate and human carcinogen. Previous studies have implicated the TCE metabolite, DCVC, as a renal toxicant, yet the molecular events mediating renal toxicity remain convoluted. Using a functional genomics approach in yeast, we aimed to gain a better understanding of TCE renal toxicity mechanisms. The yeast deletion library was treated with DCVC to identify genes required in response to exposure. Enrichment analysis of microarray results revealed an overrepresentation of genes involved in mutagenic DNA repair processes. Flow cytometry was used to confirm sensitivity of translesion synthesis (TLS) and nucleotide excision repair (NER) deficient strains. These pathways exhibited greater DCVC sensitivity in comparison to other DNA repair pathways. In particular, the lacking polymerase zeta and upstream NER genes were greatly affected. These two distinct pathways collaborate to repair DNA interstrand crosslink damage in yeast and higher organisms. These preliminary results suggest DCVC exposure results in similar DNA damage. NER mutants were more sensitive to DCVC exposure compared to TLS mutants which further supports DNA interstrand crosslinks. Western blot analysis of post-translational modifications activation of the TLS repair pathway. The involvement of the error prone translesion synthesis repair can increase the rate of mutations and result in genome instability. Mutagenesis of important oncogenes can have implications for increased renal toxicity and cancer. In conclusion, preliminary data in yeast suggest an important role for DNA damage and repair mechanisms in mediating TCE renal toxicity.