Capturing the dynamic epigenome using single molecule and single cell approaches

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ABSTRACT Our bodies consist of billions of genetically identical cells that can exhibit distinct phenotypic or epigenetic states. The covalent and reversible modification of histones enables cells to establish heritable gene expression patterns without altering their genetic blueprint. Epigenetic mechanisms that control gene expression are essential to maintain cellular identity and program multicellular differentiation. Histone H3 lysine 9 methylation (H3K9me) is associated with transcription silencing and heterochromatin formation. Fission yeast (S. pombe) has a minimalist heterochromatin architecture that is amenable to high-throughput genetics and biochemistry. A trio of conserved proteins regulates heterochromatin, which includes, 1) an H3K9me specific ''writer,'' Clr4Suv39h that catalyzes H3K9me 2) an H3K9me specific ''reader,'' Swi6HP1 that binds to H3K9me chromatin and silences transcription and, 3) an H3K9me specific ''eraser,'' Epe1JmjC, that opposes heterochromatin assembly and epigenetic inheritance. Fusing Clr4 to the tetracycline-inducible TetR DNA binding domain facilitates rapid and reversible control of heterochromatin assembly. My lab’s innovative genetic strategy has enabled us to identify chromatin-associated factors with unique roles that are restricted to heterochromatin maintenance. As part of the Research Supplements to Promote Diversity in Health-Related Research program, the supplemental funding request will investigate the mechanisms that influence epigenetic silencing downstream of H3K9 methylation establishment. Specifically, the graduate student supported by this application will use in vitro reconstitution and single-molecule approaches to investigate the dynamic chromatin rearrangements that lead to epigenetic silencing. The supplement award will promote the research, career and professional training of a graduate student belonging to an NIH designated underrepresented category. The program of research outlined in this application is well-aligned and collaboratively developed with the candidate’s future career aspirations. Furthermore, all of the scientific goals described here are fully consistent with the proposed research directions of the parent award.