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1091-6490110402013Oct01Proceedings of the National Academy of Sciences of the United States of AmericaProc Natl Acad Sci U S AHomologous RIG-I-like helicase proteins direct RNAi-mediated antiviral immunity in C. elegans by distinct mechanisms.160851609016085-9010.1073/pnas.1307453110RNAi-mediated antiviral immunity in Caenorhabditis elegans requires Dicer-related helicase 1 (DRH-1), which encodes the helicase and C-terminal domains homologous to the mammalian retinoic acid inducible gene I (RIG-I)-like helicase (RLH) family of cytosolic immune receptors. Here we show that the antiviral function of DRH-1 requires the RIG-I homologous domains as well as its worm-specific N-terminal domain. We also demonstrate that the helicase and C-terminal domains encoded by either worm DRH-2 or human RIG-I can functionally replace the corresponding domains of DRH-1 to mediate antiviral RNAi in C. elegans. Notably, substitutions in a three-residue motif of the C-terminal regulatory domain of RIG-I that physically interacts with viral double-stranded RNA abolish the antiviral activity of C-terminal regulatory domains of both RIG-I and DRH-1 in C. elegans. Genetic analysis revealed an essential role for both DRH-1 and DRH-3 in C. elegans antiviral RNAi targeting a natural viral pathogen. However, Northern blot and small RNA deep sequencing analyses indicate that DRH-1 acts to enhance production of viral primary siRNAs, whereas DRH-3 regulates antiviral RNAi by participating in the biogenesis of secondary siRNAs after Dicer-dependent production of primary siRNAs. We propose that DRH-1 facilitates the acquisition of viral double-stranded RNA by the worm dicing complex for the subsequent processing into primary siRNAs. The strong parallel for the antiviral function of RLHs in worms and mammals suggests that detection of viral double-stranded RNA may activate completely unrelated effector mechanisms or, alternatively, that the mammalian RLHs have a conserved activity to stimulate production of viral siRNAs for antiviral immunity by an RNAi effector mechanism.GuoXunyangXDepartment of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803.ZhangRuiRWangJeffreyJDingShou-WeiSWLuRuiRengR03 AI092159AINIAID NIH HHSUnited States1R03AI092159-01A1AINIAID NIH HHSUnited StatesJournal ArticleResearch Support, N.I.H., ExtramuralResearch Support, Non-U.S. Gov't20130916
United StatesProc Natl Acad Sci U S A75058760027-84240Caenorhabditis elegans Proteins0Oligonucleotides0RNA, Small Interfering0RNA, ViralEC 2.7.7.-DRH-1 protein, C elegansEC 2.7.7.-Drh-3 protein, C elegansEC 3.6.4.13DEAD-box RNA HelicasesIMAnimalsCaenorhabditis elegansimmunologyvirologyCaenorhabditis elegans ProteinsimmunologymetabolismDEAD-box RNA HelicasesimmunologymetabolismElectrophoresis, Polyacrylamide GelMicroscopy, FluorescenceOligonucleotidesgeneticsRNA InterferenceimmunologyRNA, Small InterferingmetabolismRNA, ViralmetabolismSequence Analysis, RNAThe authors declare no conflict of interest.2013918602013918602013121660201441ppublish24043766PMC379169810.1073/pnas.13074531101307453110Yoneyama M, et al. The RNA helicase RIG-I has an essential function in double-stranded RNA-induced innate antiviral responses. Nat Immunol. 2004;5(7):730–737.15208624Galiana-Arnoux D, Dostert C, Schneemann A, Hoffmann JA, Imler J-L. 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