title: Frequency and fate of microRNA editing in human brain.
abstract: Primary transcripts of certain microRNA (miRNA) genes (pri-miRNAs) are subject to RNA editing that converts adenosine to inosine (A-->I RNA editing). However, the frequency of the pri-miRNA editing and the fate of edited pri-miRNAs remain largely to be determined. Examination of already known pri-miRNA editing sites indicated that adenosine residues of the UAG triplet sequence might be edited more frequently. In the present study, therefore, we conducted a large-scale survey of human pri-miRNAs containing the UAG triplet sequence. By direct sequencing of RT-PCR products corresponding to pri-miRNAs, we examined 209 pri-miRNAs and identified 43 UAG and also 43 non-UAG editing sites in 47 pri-miRNAs, which were highly edited in human brain. In vitro miRNA processing assay using recombinant Drosha-DGCR8 and Dicer-TRBP (the human immuno deficiency virus transactivating response RNA-binding protein) complexes revealed that a majority of pri-miRNA editing is likely to interfere with the miRNA processing steps. In addition, four new edited miRNAs with altered seed sequences were identified by targeted cloning and sequencing of the miRNAs that would be processed from edited pri-miRNAs. Our studies predict that approximately 16% of human pri-miRNAs are subject to A-->I editing and, thus, miRNA editing could have a large impact on the miRNA-mediated gene silencing.
authors.affiliation: The Wistar Institute.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Kawahara
authors.forename: Molly
authors.initials: M
authors.lastname: Megraw
authors.forename: Edward
authors.initials: E
authors.lastname: Kreider
authors.forename: Hisashi
authors.initials: H
authors.lastname: Iizasa
authors.forename: Louis
authors.initials: L
authors.lastname: Valente
authors.forename: Artemis G
authors.initials: AG
authors.lastname: Hatzigeorgiou
authors.forename: Kazuko
authors.initials: K
authors.lastname: Nishikura
mesh_terms: D000241:Adenosine / Q000378:metabolism; D000243:Adenosine Deaminase / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000378:metabolism*; D006801:Humans; D007288:Inosine / Q000378:metabolism; D051379:Mice; D035683:MicroRNAs / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D017393:RNA Editing; D012322:RNA Precursors / Q000737:chemistry / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D016601:RNA-Binding Proteins
chemical_list: D035683:MicroRNAs; D012322:RNA Precursors; D016601:RNA-Binding Proteins; D007288:Inosine; C567955:ADARB1 protein, human; D000243:Adenosine Deaminase; D000241:Adenosine