The mouse Pramel1 regulates spermatogonial development by inhibiting the retinoic acid (RA) signaling during spermatogenesis.

Spermatogenesis begins when cell-fate committed prospermatogonia migrates to the basement membrane and initiate spermatogenesis in response to retinoic acid (RA) in the neonatal testis. The underlying cellular and molecular mechanisms in this process are not fully understood. Here, we report findings on the involvement of a cancer-testis antigen, PRAMEL1, in the initiation and maintenance of spermatogenesis. By analyzing mouse models with either global or conditional Pramel1 inactivation, we found that PRAMEL1 regulates the RA responsiveness of the subtypes of prospermatogonia in the neonatal testis, and affects their homing process during the initiation of spermatogenesis. Pramel1 deficiency led to an increased fecundity in juvenile males and decreased fecundity in mature males. In addition, Pramel1 deficiency resulted in a regional Sertoli cell-only (SCO) phenotype during the first round of spermatogenesis, which was rescued by the administration of the RA inhibitor, WIN18,446, suggesting that PRAMEL1 functions as an inhibitor of RA signaling in germ cells. Overall, our findings suggest that PRAMEL1 fine-tunes RA signaling, playing a crucial role in the proper establishment of the first and subsequent rounds of spermatogenesis.