A placental growth factor is silenced in mouse embryos by the zinc finger protein ZFP568

Embryo viability relies on placental repression The insulin-like growth factor (IGF) signaling pathway controls maternal supply of and fetal demands for nutrients. Yang et al. report that the essential KRAB–zinc finger protein ZFP568 specifically and directly represses a placental-specific IGF2 transcript during early mouse development. Elimination of ZFP568 in vivo leads to the inappropriate early activation of transcription, which results in embryonic death owing to overexpression of IGF2 peptide. Thus, the specific, targeted preimplantation repression of a promoter is essential for viability. Science , this issue p. 757