Tudor-SN–mediated endonucleolytic decay of human cell microRNAs promotes G ₁ /S phase transition

Breaking down miRNAs Although much work has examined microRNA (miRNA) biogenesis, relatively little is known about miRNA decay. Elbarbary et al. now identify Tudor-SN, an endonuclease that interacts with the RNA-induced silencing complex. Tudor-SN targets miRNAs at CA and UA dinucleotides located more than five nucleotides from miRNA ends. Tudor-SN-mediated miRNA decay removes miRNAs that silence genes encoding proteins that are critical for the G 1 -to-S phase transition in the cell cycle. Science , this issue p. 859