Inactivation of Exosc10 in the oocyte impairs oocyte development and maturation, leading to a depletion of the ovarian reserve in mice.

EXOSC10 is a catalytic subunit of the nuclear RNA exosome with an exoribonuclease activity. The enzyme processes and degrades different classes of RNAs. To delineate the role of EXOSC10 during oocyte growth, specific Exosc10 inactivation was performed in the oocytes from the primordial follicle stage onward using the Gdf9-iCre; Exosc10f/- mouse model (Exosc10cKO(Gdf9)). Exosc10cKO(Gdf9) female mice are infertile. The onset of puberty and the estrus cycle in mutants are initially normal and ovaries contain all follicle classes. By the age of eight weeks, vaginal smears reveal irregular estrus cycles and mutant ovaries display a complete depletion of follicles. Mutant oocytes retrieved from the oviduct are degenerated, sometimes showing an enlarged polar body which may reflect a defective first meiotic division. Under fertilization conditions, the mutant oocytes do not enter into an embryonic development process. Furthermore, we conducted a comparative proteome analysis of wild type and Exosc10 knockout mouse ovaries and identified EXOSC10-dependent proteins involved in many biological processes, such as meiotic cell cycle progression and oocyte maturation. Our results unambiguously demonstrate an essential role for EXOSC10 in oogenesis and may serve as a model for primary ovarian insufficiency in humans.