title: Homologous RIG-I-like helicase proteins direct RNAi-mediated antiviral immunity in C. elegans by distinct mechanisms.
abstract: RNAi-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.
authors.affiliation: Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803.
authors.forename: Xunyang
authors.initials: X
authors.lastname: Guo
authors.forename: Rui
authors.initials: R
authors.lastname: Zhang
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Wang
authors.forename: Shou-Wei
authors.initials: SW
authors.lastname: Ding
authors.forename: Rui
authors.initials: R
authors.lastname: Lu
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000276:immunology* / Q000821:virology*; D029742:Caenorhabditis elegans Proteins / Q000276:immunology / Q000378:metabolism*; D053487:DEAD-box RNA Helicases / Q000276:immunology / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D008856:Microscopy, Fluorescence; D009841:Oligonucleotides / Q000235:genetics; D034622:RNA Interference / Q000276:immunology*; D034741:RNA, Small Interfering / Q000378:metabolism; D012367:RNA, Viral / Q000378:metabolism*; D017423:Sequence Analysis, RNA
chemical_list: D029742:Caenorhabditis elegans Proteins; D009841:Oligonucleotides; D034741:RNA, Small Interfering; D012367:RNA, Viral; C461646:DRH-1 protein, C elegans; C524398:Drh-3 protein, C elegans; D053487:DEAD-box RNA Helicases
references.citation: Cell. 2011 Oct 14;147(2):409-22
references.pmid: 22000018
references.citation: Nat Immunol. 2008 Dec;9(12):1425-32
references.pmid: 18953338
references.citation: Int Immunol. 2012 Dec;24(12):739-49
references.pmid: 23087188
references.citation: PLoS Pathog. 2012;8(8):e1002872
references.pmid: 22916019
references.citation: Mol Cell. 2009 Oct 23;36(2):231-44
references.pmid: 19800275
references.citation: Curr Opin Virol. 2011 Dec;1(6):533-44
references.pmid: 22180767
references.citation: Cell. 2013 Jan 17;152(1-2):276-89
references.pmid: 23273991
references.citation: Cell. 2002 Jun 28;109(7):861-71
references.pmid: 12110183
references.citation: Nature. 2011 Sep 25;479(7373):423-7
references.pmid: 21947008
references.citation: Genes Dev. 2001 Oct 15;15(20):2654-9
references.pmid: 11641272
references.citation: PLoS Biol. 2011 Jan 25;9(1):e1000586
references.pmid: 21283608
references.citation: Nat Immunol. 2006 Jun;7(6):590-7
references.pmid: 16554838
references.citation: Nat Rev Immunol. 2010 Jan;10(1):47-58
references.pmid: 20029447
references.citation: Nature. 2005 Aug 18;436(7053):1040-1043
references.pmid: 16107851
references.citation: Cell. 2009 Oct 2;139(1):123-34
references.pmid: 19804758
references.citation: Cell Host Microbe. 2010 Jul 22;8(1):77-85
references.pmid: 20638644
references.citation: J Immunol. 2005 Sep 1;175(5):2851-8
references.pmid: 16116171
references.citation: Structure. 2010 Aug 11;18(8):1032-43
references.pmid: 20637642
references.citation: Nature. 2005 Aug 18;436(7053):1044-7
references.pmid: 16107852
references.citation: Cell. 1999 Oct 15;99(2):123-32
references.pmid: 10535731
references.citation: J Virol. 2013 May;87(10):5414-23
references.pmid: 23468484
references.citation: Proc Natl Acad Sci U S A. 1999 Nov 23;96(24):14147-52
references.pmid: 10570213
references.citation: Science. 2007 Jan 12;315(5809):244-7
references.pmid: 17158288
references.citation: Mol Cell. 2008 Feb 29;29(4):428-40
references.pmid: 18242112
references.citation: Cell. 2001 Nov 16;107(4):465-76
references.pmid: 11719187
references.citation: Nat Immunol. 2004 Jul;5(7):730-7
references.pmid: 15208624
references.citation: Nat Immunol. 2006 Jun;7(6):563-7
references.pmid: 16715068
references.citation: Proc Natl Acad Sci U S A. 2005 Dec 20;102(51):18420-4
references.pmid: 16339901
references.citation: Nucleic Acids Res. 2009 Apr;37(6):2014-25
references.pmid: 19208642
references.citation: Cell. 2006 Nov 17;127(4):747-57
references.pmid: 17110334
references.citation: J Immunol. 2005 Oct 15;175(8):5260-8
references.pmid: 16210631
references.citation: Proc Natl Acad Sci U S A. 2010 Jan 26;107(4):1512-7
references.pmid: 20080593
references.citation: J Virol. 2012 Nov;86(21):11645-53
references.pmid: 22896621
references.citation: Nat Struct Mol Biol. 2009 Feb;16(2):207-11
references.pmid: 19151723
references.citation: Cell. 2007 Aug 10;130(3):413-26
references.pmid: 17693253
references.citation: Science. 2007 Jan 12;315(5809):241-4
references.pmid: 17124291
references.citation: Immunity. 2008 Aug 15;29(2):178-81
references.pmid: 18701081
references.citation: PLoS Pathog. 2009 Feb;5(2):e1000286
references.pmid: 19197349
references.citation: EMBO Rep. 2011 Dec 23;13(1):7-8
references.pmid: 22157887
references.citation: Nature. 2006 May 4;441(7089):101-5
references.pmid: 16625202
references.citation: Cell. 2011 Dec 9;147(6):1248-56
references.pmid: 22119442
references.citation: Plant Cell. 2011 Apr;23(4):1625-38
references.pmid: 21467580
references.citation: Science. 2006 Jul 7;313(5783):68-71
references.pmid: 16741077
references.citation: Nat Rev Immunol. 2010 Sep;10(9):632-44
references.pmid: 20706278
references.citation: Cell. 2006 Jan 27;124(2):343-54
references.pmid: 16439208
references.citation: Proc Natl Acad Sci U S A. 2010 Jan 26;107(4):1606-11
references.pmid: 20080648
references.citation: PLoS Pathog. 2010 Feb 12;6(2):e1000764
references.pmid: 20169186