Tudor-SN-mediated endonucleolytic decay of human cell microRNAs promotes G1/S phase transition

MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression. The pathways that mediate mature miRNA decay are less well understood than those that mediate miRNA biogenesis. We found that functional miRNAs are degraded in human cells by the endonuclease Tudor-SN (TSN). In vitro, recombinant TSN initiated the decay of both protein-free and Argonaute 2–loaded miRNAs via endonucleolytic cleavage at CA and UA dinucleotides, preferentially at scissile bonds located more than five n