Lin-28 interaction with the Let-7 precursor loop mediates regulated microRNA processing

摘要: A hallmark of mammalian embryonic development is the widespread induction microRNA (miRNA) expression. Surprisingly, transcription many these small, noncoding RNAs unchanged through development; rather, a post-transcriptional regulatory event prevents accumulation mature miRNA species. Here, we present biochemical framework for regulated production Let-7 family miRNAs. Embryonic cells contain Drosha Inhibitor that processing primary transcript. This inhibitor specifically binds to conserved nucleotides in loop region precursor, and competitor mimic binding site restore processing. We have identified as stem cell specific protein Lin-28. Lin-28 has been previously implicated developmental pathways Caenorhabditis elegans, it promotes reprogramming human somatic into pluripotent cells. Our findings outline network establish novel role precursor Let-7.