PROJECT ABSTRACT
This project will investigate the function of a currently unstudied histone demethylase, Kdm4dl, in the
mouse preimplantation embryo. Many others have shown the developmental importance of activating genes
and repeat sequences during a process known as Embryonic Genome Activation (EGA), the moment when the
embryo switches on transcription for the first time. EGA involves activation of both protein coding genes as well
as repeat sequences that are critical for remodeling the chromatin environment of the early embryo. Yet, even
with its known developmental importance, the factors which facilitate EGA are still largely unknown. Here, for
the first time, I will investigate the importance of Kdm4dl, which catalytically removes the repressive histone
modification H3 Lysine 9 tri-methylation (H3K9me3), in early mouse embryogenesis. I hypothesize that Kdm4dl
is required for reprogramming the nuclei of the preimplantation embryo by removing repressive H3K9me3,
which facilitates strong activation of EGA-associated transcripts. In line with this hypothesis, my preliminary
data demonstrate temporally coordinated Kdm4dl protein expression during the 2-cell stage, when EGA
occurs. Moreover, Kdm4dl over-expression is sufficient to demethylate H3K9me3 in embryonic stem cells
leading to strong activation of EGA-associate transcripts and repeats. Combined, these preliminary data
provide further support for pursuing the project’s hypothesis further. The two outstanding questions I aim to
address are: 1. Is Kdm4dl expression sufficient to reprogram cells to a state of expanded potential, consistent
with a 2-cell-like totipotent state? and 2. Is Kdm4dl expression necessary for H3K9 demethylation and
activation of EGA-associated genes and repeats in vivo? To aid in addressing these questions, I have
developed both an innovative embryonic stem cell system which recapitulates the temporal dynamics of
Kdm4dl expression in the preimplantation embryo, and I have also established a Kdm4dl knockout mouse
model. This research project, combined with my detailed training plan, is consistent with my technical and
professional goals of becoming an independent academic investigator studying chromatin dynamics in the
early mammalian embryo, with relevance to human fertility.