Maternal alcohol consumption is the leading known non-genetic cause of mental retardation. Growing evidence, including provision of protection against ethanol's teratogenesis by exogenous antioxidants, suggests a major contribution of reactive oxygen species (ROS) to ethanol-induced teratogenesis. These findings provide a foundation for attaining our long-term goal which is directed toward the development of more effective strategies against ethanol's teratogenesis;strategies based on upregulation of endogenous antioxidants in ethanol-exposed embryos. As a necessary prerequisite to reaching this goal, in this application, we propose to investigate the role of Nrf2 signaling in modulating ethanol-induced teratogenesis. The HYPOTHESIS to be tested is that chemically-induced transcriptional activation of Nrf2 and subsequent induction of a broad spectrum of detoxifying and antioxidant proteins can act as an endogenous protective system against ethanol-induced teratogenesis. To this end, the following specific aims will be addressed:
Aim1 : To elucidate the molecular mechanisms underlying ethanol-induced activation of the Nrf2 pathway in early mouse embryos. For this work, we will a) determine the effects of ethanol on Nrf2 mRNA expression, b) determine the effects of ethanol on Nrf2 protein stabilization, c) investigate the potential of ethanol to promote Nrf2 nuclear translocation, Nrf2-DNA binding and activation of the antioxidant response element (ARE), and d) determine the effects of Nrf2 activation on the induction of its downstream target detoxifying and antioxidant genes.
Aim 2 : To investigate the protective role of the Nrf2 pathway in ethanol-induced oxidative stress and teratogenicity using a Nrf2 knockout mouse model. This will be accomplished by determining: a) whether interference with Nrf2 signaling leads to an exaggerated effect by ethanol on early mouse embryos, b) if the expected enhanced severity of dysmorphology in Nrf2-/- mice results from a deficiency in antioxidant response, and c) whether antioxidants can attenuate ethanol-induced teratogenesis in Nrf2-/- mice.
Aim 3 : To define the role of maternal dietary Nrf2 inducer in conferring in vivo protection against ethanol-induced teratogenesis. The insights gained from this study will elucidate the role of the Nrf2 pathway in modulation of oxidative stress following ethanol insult during embryogenesis. In addition, the results from this study are expected to yield innovative strategies for prevention of ethanol's teratogenesis.
The primary goal of this project is to define the role of Nrf2 signaling in modulating ethanol-induced oxidative injury and birth defects.
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