Nanos Homolog 2 (NANOS2)

Nanos2 suppressed meiosis in male mouse germ cells by preventing Stra8 expression, which was required for premeiotic DNA replication, after Cyp26b1 downregulation. Forced expression of Nanos2 in female germ cells resulted in inhibition of meiosis and induction of male-type differentiation, indicating that Nanos2 activates a male-specific genetic program.The weight of testes in 4-week-old mutant males was reduced to about 30% of normal, and no germ cells were detected. Morphologic examination revealed apoptotic germ cells after embryonic day 15.5, and apoptosis continued until the germ cells had completely disappeared by 4 weeks of age. In contrast, female gonads were morphologically and functionally normal, and homozygous female mice were fertile.