The objective of this proposal is to illuminate epigenetic transcriptional regulation during mouse embryogenesis and stem cells through investigations of the Polycomb group. The Polycomb group comprises a prominent set of histone modifiers that are essential for the execution of diverse developmental processes, including X- chromosome inactivation, self-renewal and differentiation of embryonic stem cells, cell and tissue specification, and body patterning in mammals. The Polycomb repressive complex 2 (PRC2) catalyzes histone H3K27me3 through the methyltransferases EZH2 and its paralog EZH1. H3K27me3 functions as a key epigenetic mark in development and is dysregulated in human diseases. Through much work in Drosophila, PRC2-catalyzed H3K27me3 has been shown to epigenetically maintain transcriptional silencing. Through preliminary investigations in early mouse embryos, we propose that PRC2 may also initiate transcriptional silencing.
In Aim 1, we will therefore test the role of PRC2 in initiating epigenetic transcriptional silencing. We have further found the PRC2 protein EED can function independently of PRC complexes to execute epigenetic silencing in early embryos and in embryo embryo-derived stem cells.
In Aim 2, we will define the non-PRC role of EED in epigenetic silencing in preimplantation mouse embryos and its derived stem cells. Finally, countering the prevailing dogma that H3K27me3 is deposited solely by PRC2 our results demonstrate an additional H3K27me3 catalyst.
In Aim 3, we propose to identify and dissect the function of a novel H3K27me3 catalyst in extra-embryonic and embryonic stem cells. All three Aims utilize unbiased approaches to define novel functions and mechanisms of PRC2 proteins and H3K27me3 catalysis during mouse embryogenesis and in early embryo-derived stem cells. Our central hypothesis is that the mode of epigenetic regulation ascribed to the Polycomb group can occur via alternate mechanisms and proteins. The expected findings will increase our understanding of the epigenetic logic underlying embryonic development and how epigenetic dysregulation contributes to human disease.

Public Health Relevance

Chromatin modifications have been proposed as carriers of epigenetic transcriptional memory during development and disease. The precise contribution of chromatin changes to transcription, however, remains unclear. In this proposal, we aim to define novel mechanisms and factors that orchestrate mitotic and meiotic epigenetic transcriptional regulation. The findings promise to elucidate the epigenetic logic underlying embryonic development and inform our ability to alter gene expression by modulating the epigenome for therapeutic purposes.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
3R01HD095463-02S1
Application #
9994568
Study Section
Development - 2 Study Section (DEV2)
Program Officer
Ravindranath, Neelakanta
Project Start
2018-07-05
Project End
2023-04-30
Budget Start
2019-05-01
Budget End
2020-04-30
Support Year
2
Fiscal Year
2019
Total Cost
Indirect Cost
Name
University of Michigan Ann Arbor
Department
Genetics
Type
Schools of Medicine
DUNS #
073133571
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
Cloutier, Marissa; Harris, Clair; Gayen, Srimonta et al. (2018) Experimental Analysis of Imprinted Mouse X-Chromosome Inactivation. Methods Mol Biol 1861:177-203