The Role of Alkbh1 in the Epigenetic Regulation of Extraembryonic Development and Early Embryogenesis
Date of Award
Spring 2024
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Genetics
First Advisor
Xiao, Andrew
Abstract
Successful embryogenesis requires regulated and organized stem cell differentiation from the very first cell fate decision through terminal differentiation of daughter cells within tissues. A key regulatory mechanism of stem cell differentiation and cellular identity is epigenetic regulation, whereby sequence-preserving modifications to individual bases of DNA and histone-modifications work in concert to regulate nucleosome deposition and chromatin accessibility. The past several decades of stem cell and epigenetics research have uncovered a complex regulatory environment during placental development that is not only necessary for the propagation of any mammalian species or individual, but approximates that of malignant disease. Studying the basic mechanisms of development and stem cell differentiation is a critical area of research for understanding the environmental and innate factors that underlie mammalian reproduction, carcinogenesis, and gestational disease. In this dissertation I examine the role of the N(6)-methyladenine (N6-mA) demethylase Alkbh1 in the epigenetic regulation of the developing murine placenta. While the concentration of N6-mA has been found to be mediated by Alkbh1 in in vitro embryonic stem cell models, the mechanisms through which N6-mA functions as an epigenetic mark in development were previously unstudied in vivo. This dissertation examines the role of N6-mA regulation via Alkbh1 perturbation during in vivo embryogenesis and in vitro models of trophoblast development. I provide evidence that N6-mA is enriched in developing trophoblast stem cells in vitro and that deletion of Alkbh1 in vivo leads to enriched levels of N6-mA in the developing placenta. I identify that in Alkbh1 knockouts N6-mA is deposited in the epigenetically sensitive trophoblast giant cells in the murine placenta and demonstrate that perturbation of Alkbh1 in vivo is embryonic lethal mid-gestation due to restriction of trophoblast stem cell differentiation into the trophoblast giant cell lineage. I characterize the placental phenotype of Alkbh1 deletion using both genetic and CRISPR/Cas9 models of Alkbh1 deletion and explore the transcriptional mechanisms underlying trophoblast giant cell lineage restriction due to Alkbh1 deletion. I determine that N6-mA and Alkbh1 do not regulate the epigenetic imprinting status of canonically imprinted loci, but find that it alters H3K27me3 deposition in developing giant cells via PRC2. Differentiating stem cells in the placenta are exquisitely sensitive to epigenetic perturbations, and this thesis defines the necessity of the regulation of the recently recognized epigenetic mark N6-mA in the differentiation of placental tissue via perturbation of its eraser Alkbh1.
Recommended Citation
Alderman III, Myles Harris, "The Role of Alkbh1 in the Epigenetic Regulation of Extraembryonic Development and Early Embryogenesis" (2024). Yale Graduate School of Arts and Sciences Dissertations. 1385.
https://elischolar.library.yale.edu/gsas_dissertations/1385
