Effect of monomethylarsonous acid (MMAIII) on primary fibroblasts in vitro derived from Diversity Outbred (DO) mice aged 4-6 weeks

Genetically diverse cell populations derived from mice are powerful tools for studying gene-environment interactions. Using fibroblasts derived from Diversity Outbred (DO) mice, we performed a high-content screen (HCS) of cell morphology changes to the oxidative stress and DNA damage-inducing arsenic metabolite monomethylarsonous acid (MMAIII). We show that fibroblast morphological changes in response to increasing MMAIII exposure can be modeled using dose-response modeling. We use dose-response model parameters (i.e., EC50) as traits to map cell morphology quantitative trait loci (QTL) in response to MMAIII exposure. We find that dose-response cmQTLs overlap many known genes associated with arsenic susceptibility, including Abcc4 and Txnrd1, and also represent novel targets, including Xrcc2. Moreover, we show that the cmQTL effects are reproducible and how mouse genetics can be leveraged in a systems toxicological approach to find candidate genes and support experimental validation. In summary, our work demonstrates that cmQTLs reflect the key molecular events that are known to occur during acute arsenic exposure, which are adaptable across chemicals and cell culture models. To assess transcription changes in genetically diverse muring fibroblasts exposed to MMAIII, we selected 16 fibroblasts line from DO mice based on their haplotype at mouse chromosome 10:82.9 Mbp (GRCm38). We performed gene expression analysis obtained from RNA-seq of these 16 fibroblast lines in unexposed and 0.75 uM MMAIII exposed culture conditions. These dtaa were used for differential expression analysis and gene set enrichment analyss, in addition to supporting gene candidates within cmQTL intervals based on overall expression and differences in expression following MMAIII exposure.