In eukaryotes, the genetic material DNA is complexed with proteins and packaged into chromatin. The proteins that organize the DNA are called histones. The interplay between the genetic information in DNA and the additional (or epigenetic) information conferred by the type of association with these histones determines cell fate. The long-term goal of this project is to understand how epigenetic information is interpreted by cellular machineries that instigate changes in gene expression to regulate growth and differentiation. One form of epigenetic information is the modification of histones by attachment of a small protein called ubiquitin. In organisms ranging from flies to human, histones H2A and H2B each can be modified with ubiquitin, but with different biological consequences. Whereas H2A ubiquitination is associated with gene silencing and DNA repair processes, H2B ubiquitination plays critical roles in active gene expression. How ubiquitin attached to H2A and H2B histones are interpreted as distinct signals that result in these different downstream effects is unknown. To address this knowledge gap, methods will be developed to obtain chemically homogeneous ubiquitin-H2A (or H2B) to identify proteins whose associations with chromatin are regulated by ubiquitin. A combination of biophysical and biochemical techniques will be used to characterize potential interactions between ubiquitin and histones and to investigate the functional significance of H2B ubiquitination in gene expression. Overall, this project will establish a new approach to study epigenetics and will provide mechanistic details as to how one type of epigenetic information regulates gene expression and ultimately cell fate. Broader impacts: In addition to its scientific significance in the areas of epigenetics and gene expression, this project provides outstanding training opportunities for undergraduate and graduate students. Many aspects of these studies involve biochemical experiments that are well-suited for undergraduates who may have limited time as well as limited laboratory experience. The employment of a variety of biochemical, biophysical and cutting-edge proteomics technologies provide broad training for graduate students and postdocs. In addition, as part of the broader impact efforts, workshops will be provided to graduate students and postdocs on innovative scientific teaching methods and mentor training. Overall, this project will have a direct positive impact on tomorrow's science educators.
