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Andersson MG, Haasnoot PCJ, Xu N, Berenjian S, Berkhout B, Akusjärvi G. Suppression of RNA interference by adenovirus virus-associated RNA. J Virol 2005; 79:9556-65. [PMID: 16014917 PMCID: PMC1181602 DOI: 10.1128/jvi.79.15.9556-9565.2005] [Citation(s) in RCA: 252] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
We show that human adenovirus inhibits RNA interference (RNAi) at late times of infection by suppressing the activity of two key enzyme systems involved, Dicer and RNA-induced silencing complex (RISC). To define the mechanisms by which adenovirus blocks RNAi, we used a panel of mutant adenoviruses defective in virus-associated (VA) RNA expression. The results show that the virus-associated RNAs, VA RNAI and VA RNAII, function as suppressors of RNAi by interfering with the activity of Dicer. The VA RNAs bind Dicer and function as competitive substrates squelching Dicer. Further, we show that VA RNAI and VA RNAII are processed by Dicer, both in vitro and during a lytic infection, and that the resulting short interfering RNAs (siRNAs) are incorporated into active RISC. Dicer cleaves the terminal stem of both VA RNAI and VA RNAII. However, whereas both strands of the VA RNAI-specific siRNA are incorporated into RISC, the 3' strand of the VA RNAII-specific siRNA is selectively incorporated during a lytic infection. In summary, our work shows that adenovirus suppresses RNAi during a lytic infection and gives insight into the mechanisms of RNAi suppression by VA RNA.
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Affiliation(s)
- M Gunnar Andersson
- Department of Medical Biochemistry and Microbiology, Uppsala Biomedical Center, Sweden
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Provost P, Silverstein RA, Dishart D, Walfridsson J, Djupedal I, Kniola B, Wright A, Samuelsson B, Radmark O, Ekwall K. Dicer is required for chromosome segregation and gene silencing in fission yeast cells. Proc Natl Acad Sci U S A 2002; 99:16648-53. [PMID: 12482946 PMCID: PMC139198 DOI: 10.1073/pnas.212633199] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/18/2002] [Indexed: 12/31/2022] Open
Abstract
RNA interference is a form of gene silencing in which the nuclease Dicer cleaves double-stranded RNA into small interfering RNAs. Here we report a role for Dicer in chromosome segregation of fission yeast. Deletion of the Dicer (dcr1+) gene caused slow growth, sensitivity to thiabendazole, lagging chromosomes during anaphase, and abrogated silencing of centromeric repeats. As Dicer in other species, Dcr1p degraded double-stranded RNA into approximately 23 nucleotide fragments in vitro, and dcr1Delta cells were partially rescued by expression of human Dicer, indicating evolutionarily conserved functions. Expression profiling demonstrated that dcr1+ was required for silencing of two genes containing a conserved motif.
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Affiliation(s)
- Patrick Provost
- Department of Medical Biochemistry and Biophysics, Division of Physiological Chemistry II, Karolinska Institute, S-171 77 Stockholm, Sweden Europe
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Provost P, Dishart D, Doucet J, Frendewey D, Samuelsson B, Rådmark O. Ribonuclease activity and RNA binding of recombinant human Dicer. EMBO J 2002; 21:5864-74. [PMID: 12411504 PMCID: PMC131075 DOI: 10.1093/emboj/cdf578] [Citation(s) in RCA: 332] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
RNA silencing phenomena, known as post-transcriptional gene silencing in plants, quelling in fungi, and RNA interference (RNAi) in animals, are mediated by double-stranded RNA (dsRNA) and mechanistically intersect at the ribonuclease Dicer. Here, we report cloning and expression of the 218 kDa human Dicer, and characterization of its ribonuclease activity and dsRNA-binding properties. The recombinant enzyme generated approximately 21-23 nucleotide products from dsRNA. Processing of the microRNA let-7 precursor by Dicer produced an apparently mature let-7 RNA. Mg(2+) was required for dsRNase activity, but not for dsRNA binding, thereby uncoupling these reaction steps. ATP was dispensable for dsRNase activity in vitro. The Dicer.dsRNA complex formed at high KCl concentrations was catalytically inactive, suggesting that ionic interactions are involved in dsRNA cleavage. The putative dsRNA-binding domain located at the C-terminus of Dicer was demonstrated to bind dsRNA in vitro. Human Dicer expressed in mammalian cells colocalized with calreticulin, a resident protein of the endoplasmic reticulum. Availability of the recombinant Dicer protein will help improve our understanding of RNA silencing and other Dicer-related processes.
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Affiliation(s)
- Patrick Provost
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Scheeles väg 2, Stockholm, S-171 77, Sweden, Centre de Recherche en Rhumatologie et Immunologie, Centre de Recherche du CHUL, 2705 Blvd Laurier, Ste-Foy, Quebec, G1V 4G2, Canada and Regeneron Pharmaceuticals Inc., 777 Old Saw Mill River Road, Tarrytown, NY 10591-6707, USA Corresponding authors e-mail: or
| | - David Dishart
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Scheeles väg 2, Stockholm, S-171 77, Sweden, Centre de Recherche en Rhumatologie et Immunologie, Centre de Recherche du CHUL, 2705 Blvd Laurier, Ste-Foy, Quebec, G1V 4G2, Canada and Regeneron Pharmaceuticals Inc., 777 Old Saw Mill River Road, Tarrytown, NY 10591-6707, USA Corresponding authors e-mail: or
| | - Johanne Doucet
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Scheeles väg 2, Stockholm, S-171 77, Sweden, Centre de Recherche en Rhumatologie et Immunologie, Centre de Recherche du CHUL, 2705 Blvd Laurier, Ste-Foy, Quebec, G1V 4G2, Canada and Regeneron Pharmaceuticals Inc., 777 Old Saw Mill River Road, Tarrytown, NY 10591-6707, USA Corresponding authors e-mail: or
| | - David Frendewey
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Scheeles väg 2, Stockholm, S-171 77, Sweden, Centre de Recherche en Rhumatologie et Immunologie, Centre de Recherche du CHUL, 2705 Blvd Laurier, Ste-Foy, Quebec, G1V 4G2, Canada and Regeneron Pharmaceuticals Inc., 777 Old Saw Mill River Road, Tarrytown, NY 10591-6707, USA Corresponding authors e-mail: or
| | - Bengt Samuelsson
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Scheeles väg 2, Stockholm, S-171 77, Sweden, Centre de Recherche en Rhumatologie et Immunologie, Centre de Recherche du CHUL, 2705 Blvd Laurier, Ste-Foy, Quebec, G1V 4G2, Canada and Regeneron Pharmaceuticals Inc., 777 Old Saw Mill River Road, Tarrytown, NY 10591-6707, USA Corresponding authors e-mail: or
| | - Olof Rådmark
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Scheeles väg 2, Stockholm, S-171 77, Sweden, Centre de Recherche en Rhumatologie et Immunologie, Centre de Recherche du CHUL, 2705 Blvd Laurier, Ste-Foy, Quebec, G1V 4G2, Canada and Regeneron Pharmaceuticals Inc., 777 Old Saw Mill River Road, Tarrytown, NY 10591-6707, USA Corresponding authors e-mail: or
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