<italic toggle="yes">Caenorhabditis elegans</italic> RIG-I Homolog Mediates Antiviral RNA Interference Downstream of Dicer-Dependent Biogenesis of Viral Small Interfering RNAs

ABSTRACT Dicer enzymes process virus-specific double-stranded RNA (dsRNA) into small interfering RNAs (siRNAs) to initiate specific antiviral defense by related RNA interference (RNAi) pathways in plants, insects, nematodes, and mammals. Antiviral RNAi in Caenorhabditis elegans requires Dicer-relate...

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Autores principales:	Stephanie R. Coffman, Jinfeng Lu, Xunyang Guo, Jing Zhong, Hongshan Jiang, Gina Broitman-Maduro, Wan-Xiang Li, Rui Lu, Morris Maduro, Shou-wei Ding
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2017
Materias:	Caenorhabditis elegans DRH-1 RNA interference antiviral defense Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/45ffc08346214478b128b610f1a9269b
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spelling	oai:doaj.org-article:45ffc08346214478b128b610f1a9269b2021-11-15T15:51:00Z<italic toggle="yes">Caenorhabditis elegans</italic> RIG-I Homolog Mediates Antiviral RNA Interference Downstream of Dicer-Dependent Biogenesis of Viral Small Interfering RNAs10.1128/mBio.00264-172150-7511https://doaj.org/article/45ffc08346214478b128b610f1a9269b2017-05-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.00264-17https://doaj.org/toc/2150-7511ABSTRACT Dicer enzymes process virus-specific double-stranded RNA (dsRNA) into small interfering RNAs (siRNAs) to initiate specific antiviral defense by related RNA interference (RNAi) pathways in plants, insects, nematodes, and mammals. Antiviral RNAi in Caenorhabditis elegans requires Dicer-related helicase 1 (DRH-1), not found in plants and insects but highly homologous to mammalian retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs), intracellular viral RNA sensors that trigger innate immunity against RNA virus infection. However, it remains unclear if DRH-1 acts analogously to initiate antiviral RNAi in C. elegans. Here, we performed a forward genetic screen to characterize antiviral RNAi in C. elegans. Using a mapping-by-sequencing strategy, we uncovered four loss-of-function alleles of drh-1, three of which caused mutations in the helicase and C-terminal domains conserved in RLRs. Deep sequencing of small RNAs revealed an abundant population of Dicer-dependent virus-derived small interfering RNAs (vsiRNAs) in drh-1 single and double mutant animals after infection with Orsay virus, a positive-strand RNA virus. These findings provide further genetic evidence for the antiviral function of DRH-1 and illustrate that DRH-1 is not essential for the sensing and Dicer-mediated processing of the viral dsRNA replicative intermediates. Interestingly, vsiRNAs produced by drh-1 mutants were mapped overwhelmingly to the terminal regions of the viral genomic RNAs, in contrast to random distribution of vsiRNA hot spots when DRH-1 is functional. As RIG-I translocates on long dsRNA and DRH-1 exists in a complex with Dicer, we propose that DRH-1 facilitates the biogenesis of vsiRNAs in nematodes by catalyzing translocation of the Dicer complex on the viral long dsRNA precursors. IMPORTANCE The helicase and C-terminal domains of mammalian RLRs sense intracellular viral RNAs to initiate the interferon-regulated innate immunity against RNA virus infection. Both of the domains from human RIG-I can substitute for the corresponding domains of DRH-1 to mediate antiviral RNAi in C. elegans, suggesting an analogous role for DRH-1 as an intracellular dsRNA sensor to initiate antiviral RNAi. Here, we developed a forward genetic screen for the identification of host factors required for antiviral RNAi in C. elegans. Characterization of four distinct drh-1 mutants obtained from the screen revealed that DRH-1 did not function to initiate antiviral RNAi. We show that DRH-1 acted in a downstream step to enhance Dicer-dependent biogenesis of viral siRNAs in C. elegans. As mammals produce Dicer-dependent viral siRNAs to target RNA viruses, our findings suggest a possible role for mammalian RLRs and interferon signaling in the biogenesis of viral siRNAs.Stephanie R. CoffmanJinfeng LuXunyang GuoJing ZhongHongshan JiangGina Broitman-MaduroWan-Xiang LiRui LuMorris MaduroShou-wei DingAmerican Society for MicrobiologyarticleCaenorhabditis elegansDRH-1RNA interferenceantiviral defenseMicrobiologyQR1-502ENmBio, Vol 8, Iss 2 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	Caenorhabditis elegans DRH-1 RNA interference antiviral defense Microbiology QR1-502
spellingShingle	Caenorhabditis elegans DRH-1 RNA interference antiviral defense Microbiology QR1-502 Stephanie R. Coffman Jinfeng Lu Xunyang Guo Jing Zhong Hongshan Jiang Gina Broitman-Maduro Wan-Xiang Li Rui Lu Morris Maduro Shou-wei Ding <italic toggle="yes">Caenorhabditis elegans</italic> RIG-I Homolog Mediates Antiviral RNA Interference Downstream of Dicer-Dependent Biogenesis of Viral Small Interfering RNAs
description	ABSTRACT Dicer enzymes process virus-specific double-stranded RNA (dsRNA) into small interfering RNAs (siRNAs) to initiate specific antiviral defense by related RNA interference (RNAi) pathways in plants, insects, nematodes, and mammals. Antiviral RNAi in Caenorhabditis elegans requires Dicer-related helicase 1 (DRH-1), not found in plants and insects but highly homologous to mammalian retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs), intracellular viral RNA sensors that trigger innate immunity against RNA virus infection. However, it remains unclear if DRH-1 acts analogously to initiate antiviral RNAi in C. elegans. Here, we performed a forward genetic screen to characterize antiviral RNAi in C. elegans. Using a mapping-by-sequencing strategy, we uncovered four loss-of-function alleles of drh-1, three of which caused mutations in the helicase and C-terminal domains conserved in RLRs. Deep sequencing of small RNAs revealed an abundant population of Dicer-dependent virus-derived small interfering RNAs (vsiRNAs) in drh-1 single and double mutant animals after infection with Orsay virus, a positive-strand RNA virus. These findings provide further genetic evidence for the antiviral function of DRH-1 and illustrate that DRH-1 is not essential for the sensing and Dicer-mediated processing of the viral dsRNA replicative intermediates. Interestingly, vsiRNAs produced by drh-1 mutants were mapped overwhelmingly to the terminal regions of the viral genomic RNAs, in contrast to random distribution of vsiRNA hot spots when DRH-1 is functional. As RIG-I translocates on long dsRNA and DRH-1 exists in a complex with Dicer, we propose that DRH-1 facilitates the biogenesis of vsiRNAs in nematodes by catalyzing translocation of the Dicer complex on the viral long dsRNA precursors. IMPORTANCE The helicase and C-terminal domains of mammalian RLRs sense intracellular viral RNAs to initiate the interferon-regulated innate immunity against RNA virus infection. Both of the domains from human RIG-I can substitute for the corresponding domains of DRH-1 to mediate antiviral RNAi in C. elegans, suggesting an analogous role for DRH-1 as an intracellular dsRNA sensor to initiate antiviral RNAi. Here, we developed a forward genetic screen for the identification of host factors required for antiviral RNAi in C. elegans. Characterization of four distinct drh-1 mutants obtained from the screen revealed that DRH-1 did not function to initiate antiviral RNAi. We show that DRH-1 acted in a downstream step to enhance Dicer-dependent biogenesis of viral siRNAs in C. elegans. As mammals produce Dicer-dependent viral siRNAs to target RNA viruses, our findings suggest a possible role for mammalian RLRs and interferon signaling in the biogenesis of viral siRNAs.
format	article
author	Stephanie R. Coffman Jinfeng Lu Xunyang Guo Jing Zhong Hongshan Jiang Gina Broitman-Maduro Wan-Xiang Li Rui Lu Morris Maduro Shou-wei Ding
author_facet	Stephanie R. Coffman Jinfeng Lu Xunyang Guo Jing Zhong Hongshan Jiang Gina Broitman-Maduro Wan-Xiang Li Rui Lu Morris Maduro Shou-wei Ding
author_sort	Stephanie R. Coffman
title	<italic toggle="yes">Caenorhabditis elegans</italic> RIG-I Homolog Mediates Antiviral RNA Interference Downstream of Dicer-Dependent Biogenesis of Viral Small Interfering RNAs
title_short	<italic toggle="yes">Caenorhabditis elegans</italic> RIG-I Homolog Mediates Antiviral RNA Interference Downstream of Dicer-Dependent Biogenesis of Viral Small Interfering RNAs
title_full	<italic toggle="yes">Caenorhabditis elegans</italic> RIG-I Homolog Mediates Antiviral RNA Interference Downstream of Dicer-Dependent Biogenesis of Viral Small Interfering RNAs
title_fullStr	<italic toggle="yes">Caenorhabditis elegans</italic> RIG-I Homolog Mediates Antiviral RNA Interference Downstream of Dicer-Dependent Biogenesis of Viral Small Interfering RNAs
title_full_unstemmed	<italic toggle="yes">Caenorhabditis elegans</italic> RIG-I Homolog Mediates Antiviral RNA Interference Downstream of Dicer-Dependent Biogenesis of Viral Small Interfering RNAs
title_sort	<italic toggle="yes">caenorhabditis elegans</italic> rig-i homolog mediates antiviral rna interference downstream of dicer-dependent biogenesis of viral small interfering rnas
publisher	American Society for Microbiology
publishDate	2017
url	https://doaj.org/article/45ffc08346214478b128b610f1a9269b
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<italic toggle="yes">Caenorhabditis elegans</italic> RIG-I Homolog Mediates Antiviral RNA Interference Downstream of Dicer-Dependent Biogenesis of Viral Small Interfering RNAs

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