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. 2012 Aug 16;12(2):200-10.
doi: 10.1016/j.chom.2012.05.019.

Degradation of host microRNAs by poxvirus poly(A) polymerase reveals terminal RNA methylation as a protective antiviral mechanism

Simone Backes  1 , Jillian S Shapiro, Leah R Sabin, Alissa M Pham, Ismarc Reyes, Bernard Moss, Sara Cherry, Benjamin R tenOever
Affiliations

Degradation of host microRNAs by poxvirus poly(A) polymerase reveals terminal RNA methylation as a protective antiviral mechanism

Simone Backes et al. Cell Host Microbe. .

Abstract

The life cycle of several viruses involves host or virally encoded small noncoding RNAs, which play important roles in posttranscriptional regulation. Small noncoding RNAs include microRNAs (miRNAs), which modulate the transcriptome, and small interfering RNAs (siRNAs), which are involved in pathogen defense in plants, worms, and insects. We show that insect and mammalian poxviruses induce the degradation of host miRNAs. The virally encoded poly(A) polymerase, which polyadenylates viral transcripts, also mediates 3' polyadenylation of host miRNAs, resulting in their degradation by the host machinery. In contrast, siRNAs, which are protected by 2'O-methylation (2'OMe), were not targeted by poxviruses. These findings suggest that poxviruses may degrade host miRNAs to promote replication and that virus-mediated small RNA degradation likely contributed to 2'OMe evolution.

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Figures

Figure 1
Figure 1. Poxvirus Infection Results in Loss of Host miRNAs in Insects
(A) Schematic of miR-34 processing and corresponding miRNA duplex (middle) and mature miRNAs (bottom). The mature miRNA sequence-specific reads were determined by deep sequencing of the 15–25 nt fraction of VACV-infected cells. Adenosines (A) in black depict nontemplated bases and percent representation reflects the portion of the corresponding sequence in the total miRNA-specific tailed fraction. (B) Deep-sequencing analysis of small RNA fractions of SINV-infected control (LacZ knockdown) and VACV-infected Ago1, Ago2, and control (GFP) knockdown Drosophila cells 72 hpi (moi of 300). Numbers reflect the percentage of polyadenylated species in relation to the unmodified mature species. (C) Northern blot of mock or VACV-infected Drosophila cells analyzed for miR-11, miR-34, miR-184, and U6 (72 hpi). (D) Northern blot of mock or AMEV-infected Amsacta moorei cells (moi of 10) analyzed for miR-11, miR-34, miR-184, and U6 (48 hpi). See also Figure S1 and Table S1.
Figure 2
Figure 2. Vaccinia Virus-Mediated Degradation of miRNAs
(A) Northern blot of RNA derived from BHK cells transfected with miR-124 expressing plasmid (p124) or infected with VACV, VSV, and SV expressing miR-124 (VV124, VSV124, and SV124, respectively) for 18 hr. Northern blots were probed for miR-124, miR-93, and U6. (B) Northern blot of RNA derived from BSC-1 cells infected with VV124 or VVctrl and analyzed for miR-124, miR-93, and U6 at the indicated time points. See also Figure S2.
Figure 3
Figure 3. An Early Viral Factor Mediates VACV-Induced miRNA Modification
Northern blot of RNA derived from BHK cells mock treated or infected with VV124 at an moi of 10 in presence or absence of cytosine arabinoside (AraC) or cyclohexamide (CHX) and harvested at the indicated hours postinfection (hpi). Northern blots were probed for miR-124, miR-93, and U6. See also Figure S3.
Figure 4
Figure 4. VACV Infection Induces miRNA-Specific Polyadenylation
(A and B) Schematic of pre-miR-124 (A) and pre-miR-31 (B) processing into miRNA duplex (middle) and mature miRNA (bottom). miRNA sequence-specific reads were determined by deep sequencing of the 20–35 nt fraction of VV124-infected BHK cells. Adenosines (A) in black depict nontemplated bases, and percent representation reflects the portion of the corresponding sequence represented in the total miRNA-specific tailed fraction. (C) Northern blot analysis of RNA derived from BHK cells mock treated or infected with VV124 for 18 hr (moi of 10). Small northern blots were probed for miR-124, miR-31, and U6. (D) Same as in (C) but probed for miR-124*, tRNA, and U6. See also Table S2.
Figure 5
Figure 5. VACV-Mediated miRNA Degradation Is Unbiased
(A) Deep-sequencing analysis (19–22 nt fraction) of mock and VV124-infected murine embryonic fibroblasts, 24 hpi (moi of 10). VACV-derived miR-124 (VV-miR-124) is depicted. (B) Northern blot of mammalian cells transfected with synthetic wild-type (miR-124) or tailed (miR-124(+1A)/miR-124(+7A)) miRNAs for 16 hr and probed for miR-124, miR-124*, miR-93, and U6. See also Figure S4 and Table S3.
Figure 6
Figure 6. VACV VP55-Mediated Tailing Inhibits miRNA Function
(A) Analysis of BHK cells transfected with scrambled (scbl) or VP55-specific siRNAs. Six hours posttransfection, cells were mock treated or infected with VV124 for 16 hr (moi of 10). Small northern blots were probed for miR-124, miR-93, and U6. (B) Analysis of BHK cells mock treated or transfected with plasmids expressing miR-124 (p124) and Flag-tagged VP55 and/or VP39 for 36 hr. Northern blots were probed for miR-124, miR-124*, and U6. (C) Analysis of BHK cells mock treated, infected with VVctrl, or transfected with plasmids expressing Flag-tagged VP55 and/or VP39 for 36 hr. Northern blots were probed for miR-93, tRNA, and U6. (D) BHK cells transfected with plasmids expressing miR-124 (p124), GFP-containing four tandem miR-124 target sites in the 3′ UTR (GFP-124T), and control or Flag-tagged VP55 for 36 hr. Top three panels: northern blot probed for miR-124, miR-93, and U6. Bottom three panels: immunoblots probed for Flag, GFP, and actin. See also Figure S5.
Figure 7
Figure 7. 3′-Terminal Nucleotide Methylation Protects Small RNAs from VACV-Mediated Ago-Dependent Polyadenylation
(A) Northern blot analysis of RNA derived from BHK cells transfected with plasmids expressing miR-124 (p124) and Flag-tagged Ago2 or GFP. Twenty-four hours posttransfection, cells were mock infected or infected with VV124 (moi of 10). Cell lysates were subjected to coimmunoprecipitations at the indicated hours postinfection (hpi) using anti-Flag antibody. Blots were probed for miR-124, miR-124*, and miR-93. (B) Schematic of synthetic miR-124 duplexed miRNAs including unmethylated passenger strand (top) and 2′OMe miRNA-124 guide strand (bottom). (C) Northern blot of RNA derived from BHK cells transfected with the miRNAs depicted in (B). Transfected cells were mock treated or VVctrl infected for 16 hr. Northern blot were probed for miR-124, miR-124*, miR-93, and U6.
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References

    1. Ameres SL, Horwich MD, Hung JH, Xu J, Ghildiyal M, Weng Z, Zamore PD. Target RNA-directed trimming and tailing of small silencing RNAs. Science. 2010;328:1534–1539. - PMC - PubMed
    1. Assarsson E, Greenbaum JA, Sundström M, Schaffer L, Hammond JA, Pasquetto V, Oseroff C, Hendrickson RC, Lefkowitz EJ, Tscharke DC, et al. Kinetic analysis of a complete poxvirus transcriptome reveals an immediate-early class of genes. Proc. Natl. Acad. Sci. USA. 2008;105:2140–2145. - PMC - PubMed
    1. Baek D, Villén J, Shin C, Camargo FD, Gygi SP, Bartel DP. The impact of microRNAs on protein output. Nature. 2008;455:64–71. - PMC - PubMed
    1. Barnes D, Kunitomi M, Vignuzzi M, Saksela K, Andino R. Harnessing endogenous miRNAs to control virus tissue tropism as a strategy for developing attenuated virus vaccines. Cell Host Microbe. 2008;4:239–248. - PMC - PubMed
    1. Bartel DP. MicroRNAs: genomics, biogenesis, mechanism, and function. Cell. 2004;116:281–297. - PubMed

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