Structural basis for pre-miRNA-31 biogenesis

MicroRNAs (miRNAs) are a class of small non-coding RNAs that regulate protein gene expression post-transcriptionally. By base pairing with target mRNAs, miRNAs triggers mRNA degradation or translational suppression[1-4]. Abnormal miRNAs levels are associated with cancers, diabetes, neurological and other diseases[5-8]. RNA polymerase II transcribes primary miRNA (pri-miR) in the nucleus and pri-miRs are subsequently processed by Microprocessor, which is composed of Drosha and DiGeorge syndrome critical region 8 (DGCR8) proteins, to generate precursor miRNAs (pre-miRs). Pre-miRs are exported from the nucleus to the cytoplasm in a GTP-dependent manner by Exportin-5. In the cytoplasm, a pre-miRs are further processed by Dicer to generate 21-22 nt mature miRNA[4, 9]. Argonaute (Ago) protein loads one of mature miRNAs into protein and forms miRNA-induced silencing complex, which is responsible for mRNA degradation or translational suppression[2, 4]. We performed DMS-MaPseq in order to examine the effect of secondary and tertiary structural elements on post-transcriptional regulation of pre-miR-31