Non-genetic information has recently been shown to regulate an increasing number of complex phenotypes, including physical appearance, energy metabolism, behavioral state, and longevity. How epigenetic information is transmitted from generation to generation is still largely unknown. Anything in the zygote, which is not the DNA itself, could carry this non-genetic information. Here we propose taking advantage of the nematode C. elegans, where we have characterized several examples of transgenerational epigenetic inheritance, to identify the heritable material that regulates epigenetic memory. We have identified that C. elegans contain an ancient form of DNA methylation, on the 6th position of the purine ring in adenines (6mA), which was previously thought to only occur in unicellular organisms. We were the first to identify this methylation in Metazoa and additionally found that this modification increases progressively in a paradigm of epigenetic memory. Here we propose to characterize this novel epigenetic modification in eukaryotes by identifying in which specific tissues and genomic locations 6mA modifications occur. We will also identify and characterize the enzymes that add, remove and recognize this modification. Finally we will combine metabolic methyl-labeling and directed methylation and demethylation to determine whether 6mA is the heritable material. Together this application will define a fundamental new layer of conserved epigenetic regulation and begin to identify whether 6mA can transmit a molecular memory across generations.
Relevancy Statement There are increasing examples that environmental manipulations have a transgenerational effect on human health. However, the molecules that specifically carry this non-genetic information across generations are unknown. By using a robust paradigm of epigenetic inheritance in the genetically tractable C. elegans we can define basic conserved mechanisms of transgenerational inheritance. We have discovered N6- methyladenine (6mA) as a new DNA modification that occurs in Metazoa and identified enzymes that regulate the addition and removal of this modification. The proposed research will characterize the effect of 6mA on transcription and chromatin structure and will examine its potential role as a carrier of epigenetic information in transgenerational epigenetic inheritance. Because the regulation of chromatin is a highly conserved process, it is likely that these proposed studies will help to define basic mechanisms of transgenerational inheritance. This work will lay a foundation for understanding this process in more complex systems, including inherited disorders in humans.
