5'-Triphosphate-Dependent Activation of PKR by RNAs with Short Stem-Loops
Subba Rao Nallagatla, Jungwook Hwang, Rebecca Toroney, Xiaofeng Zheng, Craig E. Cameron, Philip C. Bevilacqua
Abstract
Subba Rao Nallagatla, Jungwook Hwang, Rebecca Toroney, Xiaofeng Zheng, Craig E. Cameron, Philip C. Bevilacqua
Abstract
Molecular patterns in pathogenic RNAs can be recognized by the innate immune system, and a component of this response is the interferon-induced enzyme RNA-activated protein kinase (PKR). The major activators of PKR have been proposed to be long double-stranded RNAs. We report that RNAs with very limited secondary structures activate PKR in a 5'-triphosphate-dependent fashion in vitro and in vivo. Activation of PKR by 5'-triphosphate RNA is independent of RIG-I and is enhanced by treatment with type 1 interferon (IFN-alpha). Surveillance of molecular features at the 5' end of transcripts by PKR presents a means of allowing pathogenic RNA to be distinguished from self-RNA. The evidence presented here suggests that this form of RNA-based discrimination may be a critical step in mounting an early immune response.
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Molecular patterns in pathogenic RNAs can be recognized by the innate immune system, and a component of this response is the interferon-induced enzyme RNA-activated protein kinase (PKR). The major activators of PKR have been proposed to be long double-stranded RNAs. We report that RNAs with very limited secondary structures activate PKR in a 5'-triphosphate-dependent fashion in vitro and in vivo. Activation of PKR by 5'-triphosphate RNA is independent of RIG-I and is enhanced by treatment with type 1 interferon (IFN-alpha). Surveillance of molecular features at the 5' end of transcripts by PKR presents a means of allowing pathogenic RNA to be distinguished from self-RNA. The evidence presented here suggests that this form of RNA-based discrimination may be a critical step in mounting an early immune response.
Key concepts: Protein kinase R, RNA, Interferon, EIF-2 kinase, Innate immune system, Biology, Cell biology, Kinase