Graduate Student (PhD) Baylor College of Medicine Houston, Texas, United States
Abstract Authors: Avery A. Ahmed1,2; Bethany K. Patton1,3; Matthew Meyer4; and Stephanie A. Pangas1,2,3,5,6
1Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, USA.
2Graduate Program in Development, Disease Models & Therapeutics, Baylor College of Medicine, Houston, Texas, USA. averym@bcm.edu
3Graduate Program in Molecular & Cellular Biology, Baylor College of Medicine, Houston, Texas, USA.
4Shared Equipment Authority, Rice University, Houston, Texas, USA.
5Graduate Program in Biochemistry & Molecular Biology, Baylor College of Medicine, Houston, Texas, USA.
6Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, Texas, USA.
Abstract Text: Reproductive decline and infertility in women are largely caused by diminished oocyte quality and quantity. The mechanisms underlying this decline are not yet fully understood but are attributed to various factors, including mitochondrial dysfunction, improper oocyte-granulosa cell communication, and changes to proteostasis. Neddylation, a ubiquitin-like post-translational modification that affects protein homeostasis and quality control, is implicated in various health conditions, but its role in oocyte biology remains unknown. Using CRISPR/Cas9 gene editing, we generated a novel conditional allele of Uba3, an essential enzyme in the NEDDylation pathway, and crossed it with the oocyte-specific cre driver line, Gdf9-icre. Continuous mating for 6-months of Uba3 conditional knockout (“cKO”) females failed to produce any pups, indicating that NEDDylation is required for female fertility. By histological and morphometric analysis,12 week old Uba3 cKO ovaries are nearly devoid of follicles - severe premature aging phenotype. Prior to ovulation, GV oocytes of Uba3 cKO mice have significantly higher levels of reactive oxygen species (ROS). Transmission electron microscopy showed that mitochondrial morphology was significantly altered in Uba3 cKO oocytes. Additionally, Uba3 cKO oocytes lack well-developed transzonal projections (TZPs), structures that span the zona pellucida to allow for bidirectional communication with the oocyte and surrounding somatic cells. By transcriptomic analysis of fully grown GV oocytes, we discovered changes in genes related to cell adhesion as well as cell projection. Thus, NEDDylation appears to be essential for maintaining oocyte organelle integrity and overall female fertility. Further studies will seek to elucidate NEDDylation targets as mediators of reproductive disease and oocyte aging. These studies were supported by NIH grants T32HD098068 and R21HD109807.
