The germline is the only cell lineage capable of giving rise to the gametes. Defective germline development results in reduction or elimination of germ cells and ultimately causes infertility in humans, which affects 10- 15% of couples. Germ cell development begins early during embryonic development. After specification of primordial germ cells (PGCs), transcription is transiently repressed in PGCs. This is in stark contrast to the development of somatic lineages, which often relies on the activation of complex transcriptional programs. The establishment of such a transient genome-wide transcriptionally repressive state is critically important for early stages of the germline development, because it prevents PGCs from responding to surrounding signals that specify somatic cell fates. Failure to repress transcription during early stages of PGC development causes somatic differentiation and apoptosis of PGCs, which eventually leads to elimination of germ cells from the embryo. Understanding how this global transcriptionally repressive state is established in PGCs thus is highly relevant to human reproductive health. Our preliminary studies suggest that Dnd1, a RNA-binding protein required for vertebrate germ cell development, plays an essential role in establishing the genome- wide transcriptionally repressive state in PGCs. We found that Dnd1 protein is rapidly degraded by autophagy, making it intrinsically unstable. During development, Dnd1 is expressed at the right time and in the right place, and is required for the expression of Nanos1, which represses transcription in PGCs. We hypothesize that the genome-wide transcriptionally repressive state in PGCs is established through precisely regulated expression of Dnd1 protein.
Specific aims are:
Aim 1 : To determine if Dnd1 is a central upstream regulator of the transcriptional repression in PGCs.
Aim 2 : To investigate the mechanisms through which Dnd1 regulates nanos1 translation.
Aim 3 : To determine whether autophagy- dependent Dnd1 turnover is important for the germline development.

Public Health Relevance

Since human infertility affects 10-15% of couples, a deeper understanding of the development of the germline, the only cell lineage capable of giving rise to the gametes, is highly relevant to human reproductive health. Proper germline development requires the establishment of a transient genome-wide transcriptionally repressive state in early primordial germ cells (PGCs) to prevent somatic differentiation and apoptosis of PGCs. Here we propose to study in detail how this genome-wide transcriptionally repressive state is established in PGCs. Such knowledge will provide advances relevant to stem cell, developmental, and reproductive biology.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM111816-04
Application #
9399662
Study Section
Cellular, Molecular and Integrative Reproduction Study Section (CMIR)
Program Officer
Salazar, Desiree Lynn
Project Start
2015-04-01
Project End
2018-12-31
Budget Start
2018-01-01
Budget End
2018-12-31
Support Year
4
Fiscal Year
2018
Total Cost
Indirect Cost
Name
University of Illinois Urbana-Champaign
Department
Veterinary Sciences
Type
Schools of Veterinary Medicine
DUNS #
041544081
City
Champaign
State
IL
Country
United States
Zip Code
61820
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