Investigating protein methylation in neural crest development

Once an egg is fertilized, that single cell must divide repeatedly to generate the trillions of cells that make up our bodies. In adults, most cells have specialized jobs to do. However, cells in early embryos have many options available to them. As developmental biologists, the Gammill lab studies how embryonic cells decide what their roles will be, as well as how cells with different jobs come together to create properly structured organs in their correct locations. In considering these questions, there is a particularly fascinating type of cell that appears as the brain and spinal cord form. These cells, called neural crest cells, are striking because they do not stay in the central nervous system where they are born. Instead, neural crest cells crawl away to other parts of the embryo and become many important structures, including bones in our face, part of our heart, pigment in our skin, as well as nerves that regulate digestion. Because neural crest cells make so many diverse parts of us, when these cells don't form correctly, a number of common birth defects can result. It is crucial to understand normal neural crest development so that we can identify ways that the food we eat, chemicals in our environment, and our family's medical history disrupt these normal processes. Moreover, neural crest cells provide a great example to learn how cells move and decide who they are. Specifically, this project studies how the addition of a molecular switch called 'methylation' on neural crest proteins (the machines that carry out cell function) regulates neural crest cell behavior and identity in early embryos. This project promotes training of numerous junior scientists, enhances the teaching curricula of the principal investigator, and engages the community to advance STEM learning.

The objective of this project is to understand how protein methylation regulates neural crest development, building on the Gammill lab's prior NSF-supported research that identified the histone H3 lysine 36 (H3K36) dimethylase NSD3 as the first neural crest-essential protein methyltransferase. To attain this objective, the research will: 1) reveal the relationship between H3K36me2 and gene expression, and the role of H3K36me2 in a key developmental cell fate decision, by comparing NSD3-dependent H3K36me2 and expressed genes in the neural crest genome-wide using ChIPseq and RNAseq as the neural crest developmental program is activated; 2) define the function of the neural crest-expressed H3K36 trimethylase SETD2 using chick transient genetics and molecular embryology, enabling future experiments to examine the interplay of H3K36me2 and me3 in the spatiotemporal regulation of neural crest gene expression and further increase understanding of H3K36 methylation in a developmental context; 3) investigate the mechanism by which non-histone protein methylation regulates neural crest migration by identifying and characterizing non-histone protein substrates of NSD3 using protein arrays, mass spectrometry, and chick transient genetic analysis. This project will give important new insight into neural crest development and fundamental mechanisms of cell migration, and establish post-translational methylation of non-histone proteins as a novel influence during development. Furthermore, this project will have broader impacts by training a postdoctoral fellow, a graduate student, and at least four undergraduates, disseminating research findings in publications and talks, and incorporating research progress into teaching as well as through numerous community outreach activities.