Suppression of RNA interference by adenovirus virus-associated RNA.
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.
Andersson
M Gunnar
MG
Department of Medical Biochemistry and Microbiology, Uppsala Biomedical Center, Sweden.
Haasnoot
P C Joost
PC
Xu
Ning
N
Berenjian
Saideh
S
Berkhout
Ben
B
Akusjärvi
Göran
G
D000260:Adenoviruses, Human / Q000235:genetics*; D001483:Base Sequence; D002460:Cell Line; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D012367:RNA, Viral / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D043244:Ribonuclease III / Q000037:antagonists & inhibitors / Q000378:metabolism; D016662:Virus Integration; D019892:eIF-2 Kinase / Q000037:antagonists & inhibitors / Q000378:metabolism
D034741:RNA, Small Interfering; D012367:RNA, Viral; C052835:adenovirus associated RNA; D019892:eIF-2 Kinase; D043244:Ribonuclease III