This project is a proof of principle of systems toxicology, a new approach to chemical safety evaluation that
integrates molecular, cellular, and physiological data in the context of a genetically diverse animal model to
develop testable hypotheses about the key molecular events leading to adverse outcomes following chemical
exposure. The project aims to capitalize on the potential of two powerful population-based model organism
resources, the Collaborative Cross (CC) and Diversity Outbred (DO) mice, to study the role of genetics in
conferring susceptibility to chemical exposures. Through an integrated set of experiments using arsenic
exposure in mice and cell lines, the molecular genetic basis of toxicological responses will be evaluated. This
project will test the hypothesis that genetic analysis in the context of a quantitative environmental perturbation
will reveal multiple, novel, and diverse biochemical networks that respond to chemical exposure. The
proposed integrated set of experiments will enable the discovery and validation of adverse outcome pathways
through three specific aims. Aim 1 will evaluate study designs for animal testing with genetically diverse DO
mice including sample size requirements for toxicity evaluation. G x E genetic loci will be mapped and
incorporated into predictive computational models, and testable hypotheses will be proposed for validation.
Aim 2 will conduct a parallel, population-level arsenic exposure study of in vitro primary cell cultures to identify
genetic factors underlying susceptibility and resistance using physiologically informative cellular phenotypes.
The data generated in the in vitro arsenic exposure study will allow determination of the extent to which
cytotoxicity, genotoxicity, and oxidative stress in cellular assays are physiologically informative for the
discovery of molecular pathways that drive susceptibility and/or response in the whole organism. Aim 3 will
identify key mechanisms in renal arsenic toxicity. This study will generate a model for the effect of arsenic
exposure on the kidney to predict outcomes that are contingent on genetic background. Collectively, this new
approach to toxicology using DO mice will address fundamental biological questions by combining chemical
interventions with genetic variation. It will establish causal pathways across multiple levels of molecular and
physiological outcomes to yield results with relevance to clinical translation.