Exosc10 deficiency in the initial segment is dispensable for sperm maturation and male fertility in mice.

EXOSC10 is an exosome-associated ribonuclease that degrades and processes a wide range of transcripts in the nucleus. The initial segment (IS) of the epididymis is crucial for sperm transport and maturation in mice by affecting the absorption and secretion that is required for male fertility. However, the role of EXOSC10 ribonuclease-mediated RNA metabolism within the IS in the regulation of gene expression and sperm maturation remains unknown. Herein, we established an Exosc10 conditional knockout (Exosc10 cKO) mouse model by crossing Exosc10 ^F/F mice with Lcn9-Cre mice which expressed recombinase in the principal cells of IS as early as post-natal day 17. Morphological and histological analyses revealed that Exosc10 cKO males had normal spermatogenesis and development of IS. Moreover, the sperm concentration, morphology, motility, and frequency of acrosome reactions in the cauda epididymides of Exosc10 cKO mice were comparable with those of control mice. Thus, Exosc10 cKO males had normal fertility. Collectively, our genetic mouse model and findings demonstrate that loss of EXOSC10 in the IS of epididymis is dispensable for sperm maturation and male fertility.