Stra8, or Stimulated By Retinoic Acid Gene 8, is a gene induced by retinoic acid (RA) and plays vital roles in both male and female germ cell development. It is crucial for the transition from mitosis to meiosis in mammalian germ cells, associated with pathways like the cell cycle, apoptosis, and autophagy regulation. Genetic models, especially KO mouse models, have been instrumental in studying its functions [1,2,4,5,6,7].

In female mice, mutation of the RB-binding site of Stra8 delays meiotic entry, meiotic prophase progression, and leads to precocious depletion of the oocyte pool, suggesting Stra8-RB interaction is required for S phase entry and meiotic gene activation [1]. In male mice, Stra8 knockout leads to a muted RA response during spermatogonial development, with more transcripts typical of undifferentiated cells. Although spermatocytes can form, they fail to complete meiosis [2]. Stra8-deficient germ cells in male mice also fail to enter meiosis and show aberrant upregulation of autophagy-lysosome genes, indicating Stra8 suppresses autophagy during spermatogenesis by repressing Nr1d1 expression [7]. Moreover, Stra8 may inhibit apoptosis during mouse spermatogenesis via the AKT signaling pathway as observed in Stra8-knockout male mice [6].

In conclusion, Stra8 is an essential gatekeeper for meiotic initiation in both male and female germ cells. Mouse KO models have revealed its role in various processes related to germ cell development and have implications for understanding infertility-related diseases such as premature ovarian insufficiency, where mutations in Stra8 may contribute to the condition [3].