title: Exogenous siRNA mediates sequence-independent gene suppression by signaling through toll-like receptor 3.
abstract: RNA interference (RNAi) is a powerful method that specifically suppresses gene expression in a sequence-dependent manner whose machinery is found in organisms from fungi to mammals. Mammalian cells have developed a sequence-independent system of gene suppression often induced by viral replication that includes the recognition of double-stranded RNA (dsRNA) through Toll-like receptor 3 (TLR3) and induction of type I interferon synthesis. Interferon activates the transcription of a set of genes including dsRNA-activated protein kinase that suppresses protein synthesis and 2'-5'-oligoadenylate synthetase, which generates a product that activates RNase L to cleave RNA in a sequence-independent manner. We observed that 21-bp dsRNA, a key mediator of RNAi, not only induces sequence-specific gene suppression, but also signals TLR3 to induce type I interferon and activates sequence-independent suppression of protein synthesis and enhancement of mRNA degradation. This sequence-independent suppression was demonstrated for both an exogenously administered reporter gene as well as during the targeting of viral genes in the course of acute herpes simplex virus type I infection of keratinocytes. As TLR3 is expressed by many primary cell types and cell lines, this sequence-independent suppression should be considered in the design of experiments using small interfering RNA-mediated gene suppression.
authors.affiliation: Division of Neurosurgery, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Katalin
authors.initials: K
authors.lastname: Karikó
authors.forename: Prakash
authors.initials: P
authors.lastname: Bhuyan
authors.forename: John
authors.initials: J
authors.lastname: Capodici
authors.forename: Houping
authors.initials: H
authors.lastname: Ni
authors.forename: John
authors.initials: J
authors.lastname: Lubinski
authors.forename: Harvey
authors.initials: H
authors.lastname: Friedman
authors.forename: Drew
authors.initials: D
authors.lastname: Weissman
mesh_terms: D002460:Cell Line; D017930:Genes, Reporter; D018259:Herpesvirus 1, Human / Q000276:immunology / Q000472:pathogenicity; D006801:Humans; D008156:Luciferases / Q000235:genetics; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000235:genetics*; D034622:RNA Interference; D012330:RNA, Double-Stranded / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics*; D011956:Receptors, Cell Surface / Q000037:antagonists & inhibitors / Q000235:genetics*; D015398:Signal Transduction; D013489:Suppression, Genetic; D051196:Toll-Like Receptor 3; D051193:Toll-Like Receptors
chemical_list: D008562:Membrane Glycoproteins; D012330:RNA, Double-Stranded; D034741:RNA, Small Interfering; D011956:Receptors, Cell Surface; C495344:TLR3 protein, human; D051196:Toll-Like Receptor 3; D051193:Toll-Like Receptors; D008156:Luciferases