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
modeling maternal metabolic dysfunction by inducing this mutation in results in 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: 3F31HD116488-02S1
NIH Institute/Center: NIH
Principal Investigator: Jenna Bergmann