title: Uracils at nucleotide position 9-11 are required for the rapid turnover of miR-29 family.
abstract: MicroRNAs are endogenous small RNA molecules that regulate gene expression. Although the biogenesis of microRNAs and their regulation have been thoroughly elucidated, the degradation of microRNAs has not been fully understood. Here by using the pulse-chase approach, we performed the direct measurement of microRNA lifespan. Five representative microRNAs demonstrated a general feature of relatively long lifespan. However, the decay dynamic varies considerably between these individual microRNAs. Mutation analysis of miR-29b sequence revealed that uracils at nucleotide position 9-11 are required for its rapid decay, in that both specific nucleotides and their position are critical. The effect of uracil-rich element on miR-29b decay dynamic occurs in duplex but not in single strand RNA. Moreover, analysis of published data on microRNA expression profile during development reveals that a substantial subset of microRNAs with the uracil-rich sequence tends to be down-regulated compared to those without the sequence. Among them, Northern blotting shows that miR-29c and fruit fly bantam possess a relatively rapid turnover rate. The effect of uracil-rich sequence on microRNA turnover depends on the sequence context. The present work indicates that microRNAs contain sequence information in the middle region besides the sequence element at both ends.
authors.affiliation: Department of Cardiology, Changhai Hospital, Shanghai, China.
authors.forename: Zhuo
authors.initials: Z
authors.lastname: Zhang
authors.forename: Jun
authors.initials: J
authors.lastname: Zou
authors.forename: Guo-Kun
authors.initials: GK
authors.lastname: Wang
authors.forename: Jun-Tao
authors.initials: JT
authors.lastname: Zhang
authors.forename: Shuang
authors.initials: S
authors.lastname: Huang
authors.forename: Yong-Wen
authors.initials: YW
authors.lastname: Qin
authors.forename: Qing
authors.initials: Q
authors.lastname: Jing
mesh_terms: D006367:HeLa Cells; D006801:Humans; D035683:MicroRNAs / Q000737:chemistry* / Q000378:metabolism*; D020871:RNA Stability; D012330:RNA, Double-Stranded / Q000378:metabolism; D014498:Uracil / Q000502:physiology*
chemical_list: D035683:MicroRNAs; D012330:RNA, Double-Stranded; D014498:Uracil