Both 20S and 19S proteasome components are essential for meiosis in male mice

The proteasome, an evolutionarily conserved proteolytic complex comprising the 20S core particle and 19S regulatory particles, performs both shared and distinct functions across various tissues and organs. Spermatogenesis, a highly complex developmental process, relies on proteasome activity at multiple stages to regulate protein turnover. In this study, we selected the 20S subunit PSMA1 and 19S regulatory subunit PSMD2 to investigate the potential functions of the proteasome in spermatogenesis. Using Psma1-EGFP and Psmd2-mCherry knock-in mouse models, we confirmed the expression of both subunits in all spermatogenic cell types, with pronounced presence in early germ cell development. To further clarify their functional significance, we specifically knocked out Psma1 and Psmd2 in germ cells. Deletion of either PSMA1 or PSMD2 led to disrupted spermatogenesis, characterized by the complete absence of sperm in the epididymis. Subsequent analysis indicated that loss of these proteasome components impaired meiotic initiation. Psma1 and Psmd2 knockout germ cells showed accumulation of DMRT1, a key regulator of mitosis-to-meiosis transition, leading to a reduction in STRA8 levels and consequent disruption of meiosis initiation. This study sheds light on the molecular mechanisms that govern meiotic initiation and identifies potential genes associated with male infertility.