title: Poly(A)-specific ribonuclease mediates 3'-end trimming of Argonaute2-cleaved precursor microRNAs.
abstract: MicroRNAs (miRNAs) are typically generated as ~22-nucleotide double-stranded RNAs via the processing of precursor hairpins by the ribonuclease III enzyme Dicer, after which they are loaded into Argonaute (Ago) proteins to form an RNA-induced silencing complex (RISC). However, the biogenesis of miR-451, an erythropoietic miRNA conserved in vertebrates, occurs independently of Dicer and instead requires cleavage of the 3' arm of the pre-miR-451 precursor hairpin by Ago2. The 3' end of the Ago2-cleaved pre-miR-451 intermediate is then trimmed to the mature length by an unknown nuclease. Here, using a classical chromatographic approach, we identified poly(A)-specific ribonuclease (PARN) as the enzyme responsible for the 3'-5' exonucleolytic trimming of Ago2-cleaved pre-miR-451. Surprisingly, our data show that trimming of Ago2-cleaved precursor miRNAs is not essential for target silencing, indicating that RISC is functional with miRNAs longer than the mature length. Our findings define the maturation step in the miRNA biogenesis pathway that depends on Ago2-mediated cleavage.
authors.affiliation: Institute of Molecular and Cellular Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan; Department of Medical Genome Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan.
authors.forename: Mayuko
authors.initials: M
authors.lastname: Yoda
authors.forename: Daniel
authors.initials: D
authors.lastname: Cifuentes
authors.forename: Natsuko
authors.initials: N
authors.lastname: Izumi
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Sakaguchi
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Suzuki
authors.forename: Antonio J
authors.initials: AJ
authors.lastname: Giraldez
authors.forename: Yukihide
authors.initials: Y
authors.lastname: Tomari
mesh_terms: D000595:Amino Acid Sequence; D060565:Argonaute Proteins / Q000235:genetics* / Q000378:metabolism; D005095:Exoribonucleases / Q000378:metabolism*; D015870:Gene Expression; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D020014:K562 Cells; D035683:MicroRNAs / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D014162:Transfection
chemical_list: D060565:Argonaute Proteins; D005095:Exoribonucleases; D035683:MicroRNAs; C466422:AGO2 protein, human; C531201:MIRN451 microRNA, human