Identification of pararosaniline as a modifier of RNA splicing in Caenorhabditis elegans.

Posttranscriptional splicing of premessenger RNA (mRNA) is an evolutionarily conserved eukaryotic process for producing mature mRNA that is translated into proteins. Accurate splicing is necessary for normal growth and development, and aberrant splicing is increasingly evident in various human pathologies. To study environmental factors that influence RNA splicing, we employed a fluorescent Caenorhabditis elegans in vivo splicing reporter as a biomarker for splicing fidelity to screen against the US EPA ToxCast chemical library. We identified pararosaniline hydrochloride as a strong modifier of RNA splicing. Through gene expression analysis, we found that pararosaniline activates the oxidative stress response and alters the expression of key RNA splicing regulator genes. Physiological assays show that pararosaniline is deleterious to C. elegans development, reproduction, and aging. Through a targeted RNAi screen, we found that inhibiting protein translation can reverse pararosaniline's effect on the splicing reporter and provide significant protection against long-term pararosaniline toxicity. Together, this study reveals a new chemical modifier of RNA splicing and describes translation inhibition as a genetic mechanism to provide resistance.

High-throughput identification of oxidative stress-inducing environmental chemicals in the C. elegans system.

The metabolism of xenobiotic chemicals from the environment can produce reactive oxygen species leading to oxidative stress that is detrimental to the cell. To study the environmental factors that influence oxidative stress, we employed C. elegans engineered with a GFP tagged to the glutathione s-transferase 4 gene encoding a phase II enzyme as a biomarker for oxidative stress to screen against the U.S. EPA Toxcast library containing 4665 unique chemicals. We identified 49 chemicals that induced oxidative stress, as indicated by an increase in gst-4p::GFP signal. Quantitative PCR was used to measure the changes in mRNA expression corresponding to phase II detoxification enzymes to confirm the induction of oxidative stress for the top 10 chemicals. Among these chemicals include pesticides such as tepraloxydim, dichlone, pentachloronitrobenzene, and common industrial reagents such as ethyl acrylate and dinitrochlorobenzene. Overall, this study presents a comprehensive screening and identification of environmentally relevant chemicals that pose potential cellular toxicity as inducers of oxidative stress.