Murine cytomegalovirus encodes a miR-27 inhibitor disguised as a target

Valentina Libri, Aleksandra Helwak, Pascal Miesen, Diwakar Santhakumar, Jessica G. Borger, Grzegorz Kudla, Finn Grey, David Tollervey, Amy H. Buck

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73 Citations (Scopus)


Individual microRNAs (miRNAs) are rapidly down-regulated during conditions of cellular activation and infection, but factors mediating miRNA turnover are poorly understood. Infection of mouse cells with murine cytomegalovirus (MCMV) induces the rapid down-regulation of an antiviral cellular miRNA, miR-27. Here, we identify a transcript produced by MCMV that binds to miR-27 and mediates its degradation. UV-crosslinking and high-throughput sequencing [CRAC (UV-crosslinking and analysis of cDNA)] identified MCMV RNA segments associated with the miRNA-binding protein Argonaute 2 (Ago2). A cluster of hits mapped to a predicted miR-27-binding site in the 3′UTR of the previously uncharacterized ORF, m169. The expression kinetics of the m169 transcript correlated with degradation of miR-27 during infection, and m169 expression inhibited miR-27 functional activity in a reporter assay. siRNA knockdown of m169 demonstrated its requirement for miR-27 degradation following infection and did not affect other host miRNAs. Substitution of the miR-27-binding site in m169 to create complementarity to a different cellular miRNA, miR-24, resulted in down-regulation of only miR-24 following infection. The m169 transcript is cytoplasmic, capped, polyadenylated, and interacts with miRNA-27 through seed pairing: characteristic features of the normal messenger RNA (mRNA) targets of miRNAs. This virus-host interaction reveals a mode of miRNA regulation in which a mRNA directs the degradation of a miRNA. We speculate that RNA-mediated miRNA degradation could be a more general viral strategy for manipulating host cells.

Original languageEnglish
Pages (from-to)279-284
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number1
Publication statusPublished - 3 Jan 2012
Externally publishedYes


  • Herpesvirus
  • RNA crosslinking
  • RNA degradation
  • RNA turnover

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