PROJECT SUMMARY
The central process of female reproduction is the formation of oocytes within the developing ovary, known as
oogenesis. This process is crucial for the formation of healthy oocytes and proper transmission of genetic and
epigenetic information to begin embryonic development. Abnormalities in ovarian development and oogenesis
are a leading cause of female infertility and disorders of sexual development, and furthermore are the cause of
many developmental disorders in the subsequent generation, such as Down syndrome and Angelman syndrome.
However, relatively little is known about the genetic regulation of human ovarian development. This is in
contrast to other organisms such as the mouse, where transgenic and knockout lines, and a short
reproductive cycle, have allowed much research in this area. An in vitro organoid model of human ovarian
development would help fill this gap, and enable an improved understanding of human ovarian
development that could lead to treatments for infertility and prevention of developmental disorders.
Ovarian development involves interactions between primordial germ cells (PGCs) and somatic cells (granulosa
cells). The granulosa cells enclose the PGCs within ovarian follicles, and support their differentiation into
oogonia, progression through meiosis, and development as oocytes. Therefore, both lineages will be required
to model this process in vitro. Existing methods allow differentiation of induced pluripotent stem cells (iPSCs)
into PGC-like cells, but these cells are in an immature state, retaining epigenetic characteristics of iPSCs. For
an in vitro model of oogenesis to be successful, improved methods must be developed to generate mature
germline cells and granulosa cells from iPSCs.
Reprogramming of cellular identity by expression of transcription factors (TFs) is a powerful technique that can
allow both reprogramming of somatic cells into iPSCs, and directed differentiation of iPSCs to specific cell
types. The Church lab has recently developed computational tools to predict TFs that specify cell identity, as
well as screening methods for combinatorial TF expression to find sets that can differentiate iPSCs to a cell
type of interest. The currently proposed research will identify TFs that can promote maturation of PGC-
like cells and produce granulosa cells from iPSCs. Results will be evaluated by single-cell
transcriptomic and epigenetic profiling, and by functional validation of key phenotypes. This research will
provide an improved understanding of the genetic regulation of ovarian development, leading to an in vitro
model of human oogenesis.