Persistent Mitochondrial and Epigenetic Effects of Early Life Toxicant Exposure

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Duke University's Superfund Research Center examines the problem of early life exposure to hazardous chemicals and later life consequences. Growing evidence suggests that the toxic effects of certain chemicals on mitochondrial function can be highly persistent, and that some individuals may be more sensitive due to genetic differences. Mitochondria undergo biogenesis and major functional changes during early development and cellular differentiation, periods during which epigenetic reprogramming also occurs. We will test the hypotheses that mitochondrial toxicity during vulnerable, plastic windows of mitochondrial and epigenetic programming results in persistent mitochondrial dysfunction, persistent epigenetic repatterning, and that these changes are mechanistically linked. We will assess the persistence of both mitochondrial and epigenetic changes throughout life, and through three subsequent generations, to test the possibility that effects are persistent even in the absence of direct chemical exposure. We acknowledge and will also test the possibilities that persistent mitochondrial effects are not mediated by epigenetic changes, and that epigenetic changes may occur but not have effects on mitochondrial function. Finally, we will also test the hypothesis that mitochondrial dysfunction will be exacerbated in genetic backgrounds, chosen on the basis of human mitochondrial disease relevance, in which mitochondrial homeostatic processes are reduced. Innovative aspects of this proposal include: 1) examination of epigenetic and transcriptional changes linked to mitochondrial disruption during potentially sensitive windows of time early in development and during cellular differentiation; 2) analysis of less-studied histone modifications in conjunction with better-studied cytosine methylation; 3) systematic examination of the effects of deficiencies in genetic pathways that modulate mitochondrial toxicity; and 4) development of high-throughput, rapid, in vivo and in vitro systems for testing persistent and trasngenerational effects.