Craniofacial dysmorphologies are among the most common human birth defects. However, the multifactorial basis of these defects has hindered our identification of culpable genes and toxicants. Thousands of environment toxicants and genes exist that may interact to cause defects. Environmental exposures likely occur in mixtures, and genetic variation can sensitize embryos to these toxic mixtures. Thus, the number of possible interactions that require examination exceeds the hundreds of thousands. While still a dizzying number of potential interactions, modern transcriptomic approaches provide opportunities to identify those chemicals and genes most likely to interact. This F32 proposal leverages the high-throughput capabilities of the zebrafish to characterize co-environmental (aim 1) and gene-environment (aim 2) interactions that cause craniofacial defects.
In aim 1, I will bioinformatically define clusters of toxicants that have correlated transcriptomic effects to predict pairs or groups of chemicals that are most likely to interact synergistically. Next, I will test these interactions in vivo using a fluorescent plate reader to measure neural crest defects in high throughput.
In aim 2, I will identify disrupted gene networks that are enriched for genes associated with craniofacial disease. I will then map each toxicant?s differentially expressed genes onto these gene modules to define gene-toxicant combinations that are predicted to interact. I will mutate these genes of interest using CRISPR/Cas9 to rapidly characterize gene-environment interactions.
Aim 1 will characterize mechanistically similar environmental toxicants that can synergize to cause defects, improving risk communication and providing a direct avenue to birth defect prevention.
Aim 2 will define specific susceptibility genes, improving our ability to identify at-risk human populations. Together, this large-scale identification of chemical and genetic interactors will greatly advance our understanding of the multifactorial basis of craniofacial birth defects.
The purpose of this proposal is to characterize genetic and environmental factors that synergistically interact to cause head and face birth defects. The results obtained will greatly increase our understanding of the multifactorial basis of craniofacial birth defects in humans.
