Nutrient restriction, inducer of yeast meiosis, induces mammalian meiotic initiation

From yeasts to mammals, the molecular machinery and chromosome structures carrying out meiosis are frequently conserved. However, the signal to initiate meiosis appears divergent: while nutrient restriction induces meiosis in the yeast system, retinoic acid (RA), a chordate morphogen, and its target, Stra8, are necessary but not sufficient to induce meiotic initiation in mammalian germ cells. Here, by using a combination of genetic, transcriptomic, cytologic approaches in mouse primary spermatogonial culture without the support of gonadal somatic cells, we show that nutrient restriction is both necessary and sufficient to robustly induce Spo11 -dependent meiotic DNA double strand breaks (DSBs) and Stra8 -dependent meiotic gene programs with RA, recapitulating those of early meiosis in vivo. Moreover, distinct network of 11 nutrient restriction-upregulated transcription factor genes was identified, whose expression does not require RA and is associated with early meiosis in vivo. Thus, our study proposes a conserved model, in which nutrient restriction induces meiotic initiation by upregulating key transcriptional factors for meiotic gene programs, and provides an in vitro platform to recapitulate meiotic initiation that will facilitate research and haploid gamete production.