Identifying Toxicity Mechanisms of Trichloroethylene

Trichloroethylene (TCE) is an industrial solvent and a common drinking water contaminate. Previous studies identified the TCE metabolites DCVG and DCVC as the moieties causing increased kidney toxicity and cancer, yet the underlying molecular events remain unknown or debated. Using a functional genomics approach in yeast, parallel deletion analysis, we aim to obtain a better understanding of the mechanisms involved in DCVG and DCVC toxicity. As many of the pathways and gene functions in yeast are conserved in higher eukaryotes, results from this analysis can inform studies in higher organisms. The yeast deletion library was treated with DCVG or DCVC for a short-term exposure of 5 generations. Enrichment analysis of both genetic profiles revealed genes involved in DNA repair and DNA damage response.  Individual growth confirmations of DNA repair genes such as Rad18, Rad5, Rev1, and Rad10 showed increased sensitivity to both metabolites, implicating DNA damage as a possible mechanism of toxicity. In addition, similar gene sensitivities were seen in experiments with formaldehyde and other DNA damaging agents.  Rad18, Rad5 and Rev1 function as critical components of error prone and error free post-replication repair pathways in yeast and humans, suggesting DCVG and DCVC may cause DNA lesions that lead to genome instability and toxicity. Future work will focus on identifying the favored mechanism of repair and the type of lesions caused by these metabolites. Altogether this work will provide further insight on potential genotoxic mechanisms leading to TCE-induced kidney toxicity.