Investigating how maternal metabolic dysfunction impacts mammalian gastrulation

Despite the high prevalence of pregnancy loss during the early post-implantation period, a detailed
understanding of cell and molecular workings at this stage of development remains elusive. During this period,
specification of the principal lineages of the future body occurs at the gastrulation stage, an evolutionary
conserved landmark event in life. While early embryonic cells are known to be sensitive to the changes in the
metabolite availability in their immediate surroundings, extremely little is known about the role of the intrauterine
metabolic environment during gastrulation and how it shapes embryo viability. The maternal metabolic
environment can be disrupted via somatic mutations in metabolic enzymes, such as the gain-of-function mutation
IDH2R140Q. This mutation leads to the conversion of the tricarboxylic acid cycle metabolite alpha-ketoglutarate
(αKG) into the epigenetically active metabolite 2-hydroxyglutarate (2-HG), which subsequently accumulates in
the bloodstream of affected patients and has downstream metabolic effects. In my preliminary work, I have
modeled maternal metabolic dysfunction by inducing this mutation in adult females, and the resulting embryos
demonstrate significant developmental delays at the time of gastrulation and failure to form distinct primary germ
layers. My work also revealed increased histone methylation, as well as differential expression of genes involved
in key developmental processes, such as cellular migration, as a response to 2-HG exposure in 2D cell culture.
Collectively, these findings suggest that maternal metabolic dysfunction driven by mutant IDH is prohibitive to
proper gastrulation. In light of these findings, I hypothesize that maternal 2-HG accumulation disrupts primary
germ layer formation via both bioenergetic and epigenetic mechanisms. My first aim is to characterize the
impact of IDH2R140Q-driven maternal metabolic dysfunction on primary germ layer formation. I will
characterize the morphological effects of maternal 2-HG accumulation using high-resolution 3D confocal
microscopy to investigate the spatiotemporal dynamics of germ layer cell specification and expansion. I further
will characterize the changes in mitochondrial activity and cell death caused by maternal 2-HG accumulation
using fluorescence-based assays. My second aim is to evaluate changes in the embryonic epigenetic
landscape caused by maternal 2-HG accumulation. I will identify variable histone modifications in exposed
embryos and the associated genomic loci using histone modification profiling followed by Cleavage Under
Targets and Tagmentation (CUT&Tag) in the embryonic portion of gastrulas. Together, this project will pave the
way toward a mechanistic and functional understanding of how maternal metabolic dysfunction modulates
embryonic development as well as adverse pregnancy outcomes. Thus, in addition to providing me with valuable
training that will further my career as a developmental biologist and reproductive medicine specialist, the
proposed research has significant potential to provide a rich source of new molecular and cellular targets for
therapeutic intervention in clinical settings where embryonic development is compromised.

Grant Number: 5F31HD116488-02
NIH Institute/Center: NIH
Principal Investigator: Jenna Bergmann