201
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Zheng Y, Gao C. E3 ubiquitin ligases, the powerful modulator of innate antiviral immunity. Cell Immunol 2019; 340:103915. [PMID: 31054776 DOI: 10.1016/j.cellimm.2019.04.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Revised: 02/26/2019] [Accepted: 04/03/2019] [Indexed: 12/27/2022]
Abstract
During viral infection, the innate immune system represents the first defense line of the human body. The pathogen associated molecular patterns (PAMPs) from the viruses are recognized by pattern recognition receptors (PRRs) of the host cell, especially from those of the immune cells. Sensing of PAMPs by PRRs elicits an elegant signal transduction system, ultimately leading to the production of type I interferons (IFNs) and proinflammatory cytokines. Ubiquitination, with its versatile functions, plays a central role in modulating almost every single step of this signaling cascade. Ubiquitin ligases, which catalyze different types of ubiquitination correlating with multiple functions, are the key participant in fine-tuning antiviral signal transduction. In this review, we focus on summarizing the ubiquitin ligases that regulate the key signaling molecules in antiviral innate immunity.
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Affiliation(s)
- Yi Zheng
- State Key Laboratory of Microbial Technology, Key Laboratory of Infection and Immunity of Shandong Province & Department of Immunology, The School of Basic Medical Sciences, Shandong University, Jinan, Shandong 250012, China
| | - Chengjiang Gao
- State Key Laboratory of Microbial Technology, Key Laboratory of Infection and Immunity of Shandong Province & Department of Immunology, The School of Basic Medical Sciences, Shandong University, Jinan, Shandong 250012, China.
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202
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Biondo C, Lentini G, Beninati C, Teti G. The dual role of innate immunity during influenza. Biomed J 2019; 42:8-18. [PMID: 30987709 PMCID: PMC6468094 DOI: 10.1016/j.bj.2018.12.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 12/14/2018] [Accepted: 12/20/2018] [Indexed: 12/25/2022] Open
Abstract
One of the distinguishing features of the 1918 pandemic is the occurrence of massive, potentially detrimental, activation of the innate immune system in critically ill patients. Whether this reflects an intrinsic capacity of the virus to induce an exaggerated inflammatory responses or its remarkable ability to reproduce in vivo is still open to debate. Tremendous progress has recently been made in our understanding of innate immune responses to influenza infection and it is now time to translate this knowledge into therapeutic strategies, particularly in view of the possible occurrence of future outbreaks caused by virulent strains.
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Affiliation(s)
- Carmelo Biondo
- Metchnikoff Laboratory, University of Messina, Messina, Italy
| | - Germana Lentini
- Metchnikoff Laboratory, University of Messina, Messina, Italy
| | | | - Giuseppe Teti
- Metchnikoff Laboratory, University of Messina, Messina, Italy.
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203
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He TS, Xie T, Li J, Yang YX, Li C, Wang W, Cao L, Rao H, Ju C, Xu LG. THO Complex Subunit 7 Homolog Negatively Regulates Cellular Antiviral Response against RNA Viruses by Targeting TBK1. Viruses 2019; 11:v11020158. [PMID: 30769920 PMCID: PMC6410154 DOI: 10.3390/v11020158] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 02/05/2019] [Accepted: 02/12/2019] [Indexed: 12/21/2022] Open
Abstract
RNA virus invasion induces a cytosolic RIG-I-like receptor (RLR) signaling pathway by promoting assembly of the Mitochondrial antiviral-signaling protein (MAVS) signalosome and triggers the rapid production of type I interferons (IFNs) and proinflammatory cytokines. During this process, the pivotal kinase TANK binding kinase 1 (TBK1) is recruited to the MAVS signalosome to transduce a robust innate antiviral immune response by phosphorylating transcription factors interferon regulatory factor 3 (IRF3) and nuclear factor (NF)-κB and promoting their nuclear translocation. However, the molecular mechanisms underlying the negative regulation of TBK1 are largely unknown. In the present study, we found that THO complex subunit 7 homolog (THOC7) negatively regulated the cellular antiviral response by promoting the proteasomal degradation of TBK1. THOC7 overexpression potently inhibited Sendai virus- or polyI:C-induced IRF3 dimerization and phosphorylation and IFN-β production. In contrast, THOC7 knockdown had the opposite effects. Moreover, we simulated a node-activated pathway to show that THOC7 regulated the RIG-I-like receptors (RLR)-/MAVS-dependent signaling cascade at the TBK1 level. Furthermore, THOC7 was involved in the MAVS signalosome and promoted TBK1 degradation by increasing its K48 ubiquitin-associated polyubiquitination. Together, these findings suggest that THOC7 negatively regulates type I IFN production by promoting TBK1 proteasomal degradation, thus improving our understanding of innate antiviral immune responses.
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Affiliation(s)
- Tian-Sheng He
- Key Laboratory of Functional Small Organic Molecules, Ministry of Education and College of Life Science, Jiangxi Normal University, 99 Ziyang Avenue, Nanchang 330022, Jiangxi, China.
| | - Tao Xie
- Key Laboratory of Functional Small Organic Molecules, Ministry of Education and College of Life Science, Jiangxi Normal University, 99 Ziyang Avenue, Nanchang 330022, Jiangxi, China.
| | - Jing Li
- Key Laboratory of Functional Small Organic Molecules, Ministry of Education and College of Life Science, Jiangxi Normal University, 99 Ziyang Avenue, Nanchang 330022, Jiangxi, China.
| | - Ya-Xian Yang
- Key Laboratory of Functional Small Organic Molecules, Ministry of Education and College of Life Science, Jiangxi Normal University, 99 Ziyang Avenue, Nanchang 330022, Jiangxi, China.
| | - Changsheng Li
- Key Laboratory of Functional Small Organic Molecules, Ministry of Education and College of Life Science, Jiangxi Normal University, 99 Ziyang Avenue, Nanchang 330022, Jiangxi, China.
| | - Weiying Wang
- Key Laboratory of Functional Small Organic Molecules, Ministry of Education and College of Life Science, Jiangxi Normal University, 99 Ziyang Avenue, Nanchang 330022, Jiangxi, China.
| | - Lingzhen Cao
- Key Laboratory of Functional Small Organic Molecules, Ministry of Education and College of Life Science, Jiangxi Normal University, 99 Ziyang Avenue, Nanchang 330022, Jiangxi, China.
| | - Hua Rao
- Key Laboratory of Functional Small Organic Molecules, Ministry of Education and College of Life Science, Jiangxi Normal University, 99 Ziyang Avenue, Nanchang 330022, Jiangxi, China.
| | - Cynthia Ju
- Department of Anesthesiology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA.
| | - Liang-Guo Xu
- Key Laboratory of Functional Small Organic Molecules, Ministry of Education and College of Life Science, Jiangxi Normal University, 99 Ziyang Avenue, Nanchang 330022, Jiangxi, China.
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204
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Abstract
Detection of double-stranded RNAs (dsRNAs) is a central mechanism of innate immune defense in many organisms. We here discuss several families of dsRNA-binding proteins involved in mammalian antiviral innate immunity. These include RIG-I-like receptors, protein kinase R, oligoadenylate synthases, adenosine deaminases acting on RNA, RNA interference systems, and other proteins containing dsRNA-binding domains and helicase domains. Studies suggest that their functions are highly interdependent and that their interdependence could offer keys to understanding the complex regulatory mechanisms for cellular dsRNA homeostasis and antiviral immunity. This review aims to highlight their interconnectivity, as well as their commonalities and differences in their dsRNA recognition mechanisms.
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Affiliation(s)
- Sun Hur
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA; .,Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts 02115, USA
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205
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Fan X, Jin T. Structures of RIG-I-Like Receptors and Insights into Viral RNA Sensing. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1172:157-188. [DOI: 10.1007/978-981-13-9367-9_8] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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206
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Jiang QX. Structural Variability in the RLR-MAVS Pathway and Sensitive Detection of Viral RNAs. Med Chem 2019; 15:443-458. [PMID: 30569868 PMCID: PMC6858087 DOI: 10.2174/1573406415666181219101613] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 10/23/2018] [Accepted: 12/12/2018] [Indexed: 12/25/2022]
Abstract
Cells need high-sensitivity detection of non-self molecules in order to fight against pathogens. These cellular sensors are thus of significant importance to medicinal purposes, especially for treating novel emerging pathogens. RIG-I-like receptors (RLRs) are intracellular sensors for viral RNAs (vRNAs). Their active forms activate mitochondrial antiviral signaling protein (MAVS) and trigger downstream immune responses against viral infection. Functional and structural studies of the RLR-MAVS signaling pathway have revealed significant supramolecular variability in the past few years, which revealed different aspects of the functional signaling pathway. Here I will discuss the molecular events of RLR-MAVS pathway from the angle of detecting single copy or a very low copy number of vRNAs in the presence of non-specific competition from cytosolic RNAs, and review key structural variability in the RLR / vRNA complexes, the MAVS helical polymers, and the adapter-mediated interactions between the active RLR / vRNA complex and the inactive MAVS in triggering the initiation of the MAVS filaments. These structural variations may not be exclusive to each other, but instead may reflect the adaptation of the signaling pathways to different conditions or reach different levels of sensitivity in its response to exogenous vRNAs.
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Affiliation(s)
- Qiu-Xing Jiang
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, United States
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207
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Ling T, Li SN, Weng GX, Wang W, Li C, Cao L, Rao H, Shu HB, Xu LG. TARBP2 negatively regulates IFN-β production and innate antiviral response by targeting MAVS. Mol Immunol 2018; 104:1-10. [DOI: 10.1016/j.molimm.2018.10.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 10/06/2018] [Accepted: 10/17/2018] [Indexed: 11/28/2022]
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208
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Dai T, Wu L, Wang S, Wang J, Xie F, Zhang Z, Fang X, Li J, Fang P, Li F, Jin K, Dai J, Yang B, Zhou F, van Dam H, Cai D, Huang H, Zhang L. FAF1 Regulates Antiviral Immunity by Inhibiting MAVS but Is Antagonized by Phosphorylation upon Viral Infection. Cell Host Microbe 2018; 24:776-790.e5. [PMID: 30472208 DOI: 10.1016/j.chom.2018.10.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Revised: 09/04/2018] [Accepted: 10/15/2018] [Indexed: 11/20/2022]
Abstract
Mitochondrial antiviral signaling protein (MAVS) is an adaptor of the innate immune receptor retinoic acid-inducible gene 1 (RIG-I) that links recognition of viral RNA to antiviral signaling. Upon interacting with RIG-I, MAVS undergoes lysine 63-linked poly-ubiquitination by the E3 ligase TRIM31 and subsequently aggregates to activate downstream signaling effectors. We find that the scaffold protein FAF1 forms aggregates that negatively regulate MAVS. FAF1 antagonizes the poly-ubiquitination and aggregation of MAVS by competing with TRIM31 for MAVS association. FAF1 knockout mice are more resistant to RNA virus infection, and FAF1 deficiency in myeloid cells results in enhanced innate signaling and reduced viral load and morbidity in vivo. Upon virus infection, the kinase IKKɛ directly phosphorylates FAF1 at Ser556 and triggers FAF1 de-aggregation. Moreover, Ser556 phosphorylation promotes FAF1 lysosomal degradation, consequently relieving FAF1-dependent suppression of MAVS. These findings establish FAF1 as a modulator of MAVS and uncover mechanisms that regulate FAF1 to insure timely activation of antiviral defense.
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Affiliation(s)
- Tong Dai
- MOE Laboratory of Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China; Institutes of Biology and Medical Science, Soochow University, Suzhou 215123, China
| | - Liming Wu
- The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China
| | - Shuai Wang
- Institutes of Biology and Medical Science, Soochow University, Suzhou 215123, China
| | - Jing Wang
- The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China
| | - Feng Xie
- MOE Laboratory of Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China; Institutes of Biology and Medical Science, Soochow University, Suzhou 215123, China
| | - Zhengkui Zhang
- MOE Laboratory of Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China; Institutes of Biology and Medical Science, Soochow University, Suzhou 215123, China
| | - Xiuwu Fang
- Institutes of Biology and Medical Science, Soochow University, Suzhou 215123, China
| | - Jingxian Li
- MOE Laboratory of Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
| | - Pengfei Fang
- MOE Laboratory of Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
| | - Fang Li
- MOE Laboratory of Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
| | - Ke Jin
- MOE Laboratory of Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
| | - Jianfeng Dai
- Institutes of Biology and Medical Science, Soochow University, Suzhou 215123, China
| | - Bing Yang
- MOE Laboratory of Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China; Department of Pharmaceutical Chemistry and the Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Fangfang Zhou
- Institutes of Biology and Medical Science, Soochow University, Suzhou 215123, China
| | - Hans van Dam
- Department of Molecular Cell Biology, Cancer Genomics Centre Netherlands, Leiden University Medical Center, Postbus 9600, 2300 RC Leiden, the Netherlands
| | - Dachuan Cai
- Department for Infectious Diseases, The Second Affiliated Hospital of Chonqing Medical University, Chongqing 400016, China
| | - Huizhe Huang
- Faculty of Basic Medical Sciences, Chonqing Medical University, Chongqing 400016, China
| | - Long Zhang
- MOE Laboratory of Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China.
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209
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Yu Q, Qu K, Modis Y. Cryo-EM Structures of MDA5-dsRNA Filaments at Different Stages of ATP Hydrolysis. Mol Cell 2018; 72:999-1012.e6. [PMID: 30449722 PMCID: PMC6310684 DOI: 10.1016/j.molcel.2018.10.012] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 08/09/2018] [Accepted: 10/09/2018] [Indexed: 12/24/2022]
Abstract
Double-stranded RNA (dsRNA) is a potent proinflammatory signature of viral infection. Long cytosolic dsRNA is recognized by MDA5. The cooperative assembly of MDA5 into helical filaments on dsRNA nucleates the assembly of a multiprotein type I interferon signaling platform. Here, we determined cryoelectron microscopy (cryo-EM) structures of MDA5-dsRNA filaments with different helical twists and bound nucleotide analogs at resolutions sufficient to build and refine atomic models. The structures identify the filament-forming interfaces, which encode the dsRNA binding cooperativity and length specificity of MDA5. The predominantly hydrophobic interface contacts confer flexibility, reflected in the variable helical twist within filaments. Mutation of filament-forming residues can result in loss or gain of signaling activity. Each MDA5 molecule spans 14 or 15 RNA base pairs, depending on the twist. Variations in twist also correlate with variations in the occupancy and type of nucleotide in the active site, providing insights on how ATP hydrolysis contributes to MDA5-dsRNA recognition. Cryo-EM structures of MDA5-dsRNA filaments determined for three catalytic states Filament forming interfaces are flexible and predominantly hydrophobic Mutation of filament-forming residues can cause loss or gain of IFN-β signaling ATPase cycle is coupled to changes in filament twist and size of the RNA footprint
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Affiliation(s)
- Qin Yu
- Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Kun Qu
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Yorgo Modis
- Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK.
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210
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Te Velthuis AJW, Long JC, Bauer DLV, Fan RLY, Yen HL, Sharps J, Siegers JY, Killip MJ, French H, Oliva-Martín MJ, Randall RE, de Wit E, van Riel D, Poon LLM, Fodor E. Mini viral RNAs act as innate immune agonists during influenza virus infection. Nat Microbiol 2018; 3:1234-1242. [PMID: 30224800 PMCID: PMC6203953 DOI: 10.1038/s41564-018-0240-5] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 08/07/2018] [Indexed: 12/17/2022]
Abstract
The molecular processes that determine the outcome of influenza virus infection in humans are multifactorial and involve a complex interplay between host, viral and bacterial factors1. However, it is generally accepted that a strong innate immune dysregulation known as 'cytokine storm' contributes to the pathology of infections with the 1918 H1N1 pandemic or the highly pathogenic avian influenza viruses of the H5N1 subtype2-4. The RNA sensor retinoic acid-inducible gene I (RIG-I) plays an important role in sensing viral infection and initiating a signalling cascade that leads to interferon expression5. Here, we show that short aberrant RNAs (mini viral RNAs (mvRNAs)), produced by the viral RNA polymerase during the replication of the viral RNA genome, bind to and activate RIG-I and lead to the expression of interferon-β. We find that erroneous polymerase activity, dysregulation of viral RNA replication or the presence of avian-specific amino acids underlie mvRNA generation and cytokine expression in mammalian cells. By deep sequencing RNA samples from the lungs of ferrets infected with influenza viruses, we show that mvRNAs are generated during infection in vivo. We propose that mvRNAs act as the main agonists of RIG-I during influenza virus infection.
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Affiliation(s)
- Aartjan J W Te Velthuis
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK.
- Division of Virology, Department of Pathology, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.
| | - Joshua C Long
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - David L V Bauer
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Rebecca L Y Fan
- School of Public Health, University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Hui-Ling Yen
- School of Public Health, University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Jane Sharps
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Jurre Y Siegers
- Department of Viroscience, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Marian J Killip
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
- Biomedical Sciences Research Complex, North Haugh, University of St Andrews, St Andrews, UK
| | - Hollie French
- Division of Virology, Department of Pathology, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK
| | | | - Richard E Randall
- Biomedical Sciences Research Complex, North Haugh, University of St Andrews, St Andrews, UK
| | - Emmie de Wit
- Laboratory of Virology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
| | - Debby van Riel
- Department of Viroscience, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Leo L M Poon
- School of Public Health, University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Ervin Fodor
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK.
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211
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Kawasaki T, Kawai T. Discrimination Between Self and Non-Self-Nucleic Acids by the Innate Immune System. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2018; 344:1-30. [PMID: 30798985 PMCID: PMC7105031 DOI: 10.1016/bs.ircmb.2018.08.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
During viral and bacterial infections, the innate immune system recognizes various types of pathogen-associated molecular patterns (PAMPs), such as nucleic acids, via a series of membrane-bound or cytosolic pattern-recognition receptors. These include Toll-like receptors (TLRs), RIG-I-like receptors (RLRs), AIM2-like receptors (ALRs), and cytosolic DNA sensors. The binding of PAMPs to these receptors triggers the production of type I interferon (IFN) and inflammatory cytokines. Type I IFN induces the expression of interferon stimulated genes (ISGs), which protect surrounding cells from infection. Some ISGs are nucleic acids-binding proteins that bind viral nucleic acids and suppress their replication. As nucleic acids are essential components that store and transmit genetic information in every species, infectious pathogens have developed systems to escape from the host nucleic acid recognition system. Host cells also have their own nucleic acids that are frequently released to the extracellular milieu or the cytoplasm during cell death or stress responses, which, if able to bind pattern-recognition receptors, would induce autoimmunity and inflammation. Therefore, host cells have acquired mechanisms to protect themselves from contact with their own nucleic acids. In this review, we describe recent research progress into the nucleic acid recognition mechanism and the molecular bases of discrimination between self and non-self-nucleic acids.
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Affiliation(s)
- Takumi Kawasaki
- Laboratory of Molecular Immunobiology, Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Japan.
| | - Taro Kawai
- Laboratory of Molecular Immunobiology, Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Japan.
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212
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Devarkar SC, Schweibenz B, Wang C, Marcotrigiano J, Patel SS. RIG-I Uses an ATPase-Powered Translocation-Throttling Mechanism for Kinetic Proofreading of RNAs and Oligomerization. Mol Cell 2018; 72:355-368.e4. [PMID: 30270105 PMCID: PMC6434538 DOI: 10.1016/j.molcel.2018.08.021] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 06/15/2018] [Accepted: 08/14/2018] [Indexed: 12/25/2022]
Abstract
RIG-I has a remarkable ability to specifically select viral 5'ppp dsRNAs for activation from a pool of cytosolic self-RNAs. The ATPase activity of RIG-I plays a role in RNA discrimination and activation, but the underlying mechanism was unclear. Using transient-state kinetics, we elucidated the ATPase-driven "kinetic proofreading" mechanism of RIG-I activation and RNA discrimination, akin to DNA polymerases, ribosomes, and T cell receptors. Even in the autoinhibited state of RIG-I, the C-terminal domain kinetically discriminates against self-RNAs by fast off rates. ATP binding facilitates dsRNA engagement but, interestingly, makes RIG-I promiscuous, explaining the constitutive signaling by Singleton-Merten syndrome-linked mutants that bind ATP without hydrolysis. ATP hydrolysis dissociates self-RNAs faster than 5'ppp dsRNA but, more importantly, drives RIG-I oligomerization through translocation, which we show to be regulated by helicase motif IVa. RIG-I translocates directionally from the dsRNA end into the stem region, and the 5'ppp end "throttles" translocation to provide a mechanism for threading and building a signaling-active oligomeric complex.
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Affiliation(s)
- Swapnil C Devarkar
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA
| | - Brandon Schweibenz
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA
| | - Chen Wang
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD 20892, USA
| | - Joseph Marcotrigiano
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD 20892, USA.
| | - Smita S Patel
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA.
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213
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Marques M, Ferreira AR, Ribeiro D. The Interplay between Human Cytomegalovirus and Pathogen Recognition Receptor Signaling. Viruses 2018; 10:v10100514. [PMID: 30241345 PMCID: PMC6212889 DOI: 10.3390/v10100514] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 09/15/2018] [Accepted: 09/19/2018] [Indexed: 12/26/2022] Open
Abstract
The cellular antiviral innate immune response is triggered upon recognition of specific viral components by a set of the host’s cytoplasmic or membrane-bound receptors. This interaction induces specific signaling cascades that culminate with the production of interferons and the expression of interferon-stimulated genes and pro-inflammatory cytokines that act as antiviral factors, suppressing viral replication and restricting infection. Here, we review and discuss the different mechanisms by which each of these receptors is able to recognize and signal infection by the human cytomegalovirus (HCMV), an important human pathogen mainly associated with severe brain defects in newborns and disabilities in immunocompromised individuals. We further present and discuss the many sophisticated strategies developed by HCMV to evade these different signaling mechanisms and counteract the cellular antiviral response, in order to support cell viability and sustain its slow replication cycle.
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Affiliation(s)
- Mariana Marques
- Institute of Biomedicine-iBiMED-and Department of Medical Sciences, University of Aveiro, 3810-193 Aveiro, Portugal.
| | - Ana Rita Ferreira
- Institute of Biomedicine-iBiMED-and Department of Medical Sciences, University of Aveiro, 3810-193 Aveiro, Portugal.
| | - Daniela Ribeiro
- Institute of Biomedicine-iBiMED-and Department of Medical Sciences, University of Aveiro, 3810-193 Aveiro, Portugal.
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214
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Zheng W, Satta Y. Functional Evolution of Avian RIG-I-Like Receptors. Genes (Basel) 2018; 9:genes9090456. [PMID: 30213147 PMCID: PMC6162795 DOI: 10.3390/genes9090456] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 09/06/2018] [Accepted: 09/06/2018] [Indexed: 12/24/2022] Open
Abstract
RIG-I-like receptors (retinoic acid-inducible gene-I-like receptors, or RLRs) are family of pattern-recognition receptors for RNA viruses, consisting of three members: retinoic acid-inducible gene I (RIG-I), melanoma differentiation-associated gene 5 (MDA5) and laboratory of genetics and physiology 2 (LGP2). To understand the role of RLRs in bird evolution, we performed molecular evolutionary analyses on the coding genes of avian RLRs using filtered predicted coding sequences from 62 bird species. Among the three RLRs, conservation score and dN/dS (ratio of nonsynonymous substitution rate over synonymous substitution rate) analyses indicate that avian MDA5 has the highest conservation level in the helicase domain but a lower level in the caspase recruitment domains (CARDs) region, which differs from mammals; LGP2, as a whole gene, has a lower conservation level than RIG-I or MDA5. We found evidence of positive selection across all bird lineages in RIG-I and MDA5 but only on the stem lineage of Galliformes in LGP2, which could be related to the loss of RIG-I in Galliformes. Analyses also suggest that selection relaxation may have occurred in LGP2 during the middle of bird evolution and the CARDs region of MDA5 contains many positively selected sites, which might explain its conservation level. Spearman’s correlation test indicates that species-to-ancestor dN/dS of RIG-I shows a negative correlation with endogenous retroviral abundance in bird genomes, suggesting the possibility of interaction between immunity and endogenous retroviruses during bird evolution.
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Affiliation(s)
- Wanjing Zheng
- Department of Evolutionary Studies of Biosystems, SOKENDAI (The Graduate University for Advanced Studies), Kanagawa 240-0193, Japan.
| | - Yoko Satta
- Department of Evolutionary Studies of Biosystems, SOKENDAI (The Graduate University for Advanced Studies), Kanagawa 240-0193, Japan.
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215
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Tan X, Sun L, Chen J, Chen ZJ. Detection of Microbial Infections Through Innate Immune Sensing of Nucleic Acids. Annu Rev Microbiol 2018; 72:447-478. [DOI: 10.1146/annurev-micro-102215-095605] [Citation(s) in RCA: 221] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Microbial infections are recognized by the innate immune system through germline-encoded pattern recognition receptors (PRRs). As most microbial pathogens contain DNA and/or RNA during their life cycle, nucleic acid sensing has evolved as an essential strategy for host innate immune defense. Pathogen-derived nucleic acids with distinct features are recognized by specific host PRRs localized in endolysosomes and the cytosol. Activation of these PRRs triggers signaling cascades that culminate in the production of type I interferons and proinflammatory cytokines, leading to induction of an antimicrobial state, activation of adaptive immunity, and eventual clearance of the infection. Here, we review recent progress in innate immune recognition of nucleic acids upon microbial infection, including pathways involving endosomal Toll-like receptors, cytosolic RNA sensors, and cytosolic DNA sensors. We also discuss the mechanisms by which infectious microbes counteract host nucleic acid sensing to evade immune surveillance.
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Affiliation(s)
- Xiaojun Tan
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9148, USA;, , , ,
- Center for Inflammation Research, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Lijun Sun
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9148, USA;, , , ,
- Center for Inflammation Research, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9148, USA
| | - Jueqi Chen
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9148, USA;, , , ,
- Center for Inflammation Research, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Zhijian J. Chen
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9148, USA;, , , ,
- Center for Inflammation Research, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9148, USA
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216
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Lai JH, Luo SF, Ho LJ. Operation of mitochondrial machinery in viral infection-induced immune responses. Biochem Pharmacol 2018; 156:348-356. [PMID: 30172712 PMCID: PMC7092938 DOI: 10.1016/j.bcp.2018.08.044] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Accepted: 08/29/2018] [Indexed: 01/05/2023]
Abstract
Mitochondria have been recognized as ancient bacteria that contain evolutionary endosymbionts. Metabolic pathways and inflammatory signals interact within mitochondria in response to different stresses, such as viral infections. In this commentary, we address several interesting questions, including (1) how do mitochondrial machineries participate in immune responses; (2) how do mitochondria mediate antiviral immunity; (3) what mechanisms involved in mitochondrial machinery, including the downregulation of mitochondrial DNA (mtDNA), disturbances of mitochondrial dynamics, and the induction of mitophagy and regulation of apoptosis, have been adopted by viruses to evade antiviral immunity; (4) what mechanisms involve the regulation of mitochondrial machineries in antiviral therapeutics; and (5) what are the potential challenges and perspectives in developing mitochondria-targeting antiviral treatments? This commentary provides a comprehensive review of the roles and mechanisms of mitochondrial machineries in immunity, viral infections and related antiviral therapeutics.
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Affiliation(s)
- Jenn-Haung Lai
- Division of Allergy, Immunology, and Rheumatology, Department of Internal Medicine, Chang Gung Memorial Hospital, Chang Gung University, Tao-Yuan, Taiwan, ROC; Graduate Institute of Medical Science, National Defense Medical Center, Taipei, Taiwan, ROC.
| | - Shue-Fen Luo
- Division of Allergy, Immunology, and Rheumatology, Department of Internal Medicine, Chang Gung Memorial Hospital, Chang Gung University, Tao-Yuan, Taiwan, ROC
| | - Ling-Jun Ho
- Institute of Cellular and System Medicine, National Health Research Institute, Zhunan, Taiwan, ROC.
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217
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Transgene-Assisted Genetic Screen Identifies rsd-6 and Novel Genes as Key Components of Antiviral RNA Interference in Caenorhabditis elegans. J Virol 2018; 92:JVI.00416-18. [PMID: 29950414 PMCID: PMC6096818 DOI: 10.1128/jvi.00416-18] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 06/16/2018] [Indexed: 12/21/2022] Open
Abstract
RNA interference (RNAi) is a widespread antiviral mechanism triggered by virus-produced double-stranded RNAs (dsRNAs). In Caenorhabditis elegans, antiviral RNAi involves a RIG-I-like RNA helicase, termed DRH-1 (dicer related RNA helicase 1), that is not required for classical RNAi triggered by artificial dsRNA. Currently, whether antiviral RNAi in C. elegans involves novel factors that are dispensable for classical RNAi remains an open question. To address this question, we designed and carried out a genetic screen that aims to identify novel genes involved in worm antiviral RNAi. By introducing extra copies of known antiviral RNAi genes into the reporter worms, we managed to reject alleles derived from 4 known antiviral RNAi genes, including the DRH-1 coding gene, during the screen. Our genetic screen altogether identified 25 alleles, which were assigned to 11 candidate genes and 2 known antiviral RNAi genes through genetic complementation tests. Using a mapping-by-sequencing strategy, we identified one of the candidate genes as rsd-6, a gene that helps maintain genome integrity through an endogenous gene-silencing pathway but was not known to be required for antiviral RNAi. More importantly, we found that two of the candidate genes are required for antiviral RNAi targeting Orsay virus, a natural viral pathogen of C. elegans, but dispensable for classical RNAi. Since drh-1 is so far the only antiviral RNAi gene not required for classical RNAi, we believe that our genetic screen led to identification of novel worm genes that may target virus-specific features to function in RNAi.IMPORTANCE In nematode worms, drh-1 detects virus-produced double-stranded RNA (dsRNA), thereby specifically contributing to antiviral RNA silencing. To identify drh-1-like genes with dedicated function in antiviral RNAi, we recently carried out a genetic screen that was designed to automatically reject all alleles derived from 4 known antiviral silencing genes, including drh-1 Of the 11 candidate genes identified, we found two of them to be required for antiviral silencing targeting a natural viral pathogen of C. elegans but not for classical RNA silencing triggered by artificial dsRNA. We believe that these two genes are novel components of worm antiviral RNAi, considering the fact that drh-1 is the only known antiviral RNAi gene that is dispensable for classical RNAi. This genetic screen also identified rsd-6, a gene that maintains genome integrity under unfavorable conditions, as a key regulator of worm antiviral silencing, demonstrating an interplay between antiviral immunity and genome integrity maintenance.
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218
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Valadkhan S, Plasek LM. Long Non-Coding RNA-Mediated Regulation of the Interferon Response: A New Perspective on a Familiar Theme. Pathog Immun 2018. [PMID: 30135954 PMCID: PMC6101671 DOI: 10.20411/pai.v3i1.252] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The interferon (IFN) response is a critical and ubiquitous component of the innate immune response to pathogens. Detailed studies in the last decades have elucidated the function of a large number of proteins that mediate the complex signaling pathways and gene expression programs involved in the interferon response. The recent discovery of the long non-coding RNAs (lncRNAs) as a new category of cellular effectors has led to studies aiming to understand the role of these transcripts in the IFN response. Several high throughput studies have shown that a large number of lncRNAs are differentially expressed following IFN stimulation and/or viral infections. In-depth study of a very small fraction of the identified lncRNAs has revealed critical roles for this class of transcripts in the regulation of multiple steps of the IFN response, and pointed to the presence of an extensive RNA-mediated regulatory network during the antiviral response. As the vast majority of the identified potential regulatory lncRNAs remain unstudied, it is highly likely that future studies will reveal a completely new perspective on the regulation of the IFN response, with lncRNA- and protein-mediated regulatory networks coordinating the duration, magnitude, and character of this aspect of the innate immune response. In addition to providing a more complete picture of the IFN response, these studies will likely identify new therapeutic targets that in the long term may impact the therapeutic options available against microbial infections and diseases of the immune system.
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Affiliation(s)
- Saba Valadkhan
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Leah M Plasek
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, Ohio
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219
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Abstract
Microbial nucleic acids are major signatures of invading pathogens, and their recognition by various host pattern recognition receptors (PRRs) represents the first step toward an efficient innate immune response to clear the pathogens. The nucleic acid-sensing PRRs are localized at the plasma membrane, the cytosol, and/or various cellular organelles. Sensing of nucleic acids and signaling by PRRs involve recruitment of distinct signaling components, and PRRs are intensively regulated by cellular organelle trafficking. PRR-mediated innate immune responses are also heavily regulated by posttranslational modifications, including phosphorylation, polyubiquitination, sumoylation, and glutamylation. In this review, we focus on our current understanding of recognition of microbial nucleic acid by PRRs, particularly on their regulation by organelle trafficking and posttranslational modifications. We also discuss how sensing of self nucleic acids and dysregulation of PRR-mediated signaling lead to serious human diseases.
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Affiliation(s)
- Ming-Ming Hu
- Medical Research Institute, School of Medicine, Wuhan University, Wuhan 430071, China; ,
| | - Hong-Bing Shu
- Medical Research Institute, School of Medicine, Wuhan University, Wuhan 430071, China; ,
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220
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Martin B, Decroly É. Mécanismes d’échappement des filovirus à l’immunité innée. Med Sci (Paris) 2018; 34:671-677. [DOI: 10.1051/medsci/20183408013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Le virus Ébola est un pathogène émergent important en Afrique où il a été responsable de plusieurs épidémies de fièvres hémorragiques associées à un taux de mortalité extrêmement élevée (jusqu’à 90 %). La pathogenèse des filovirus est, entre autres, liée à une réponse antivirale inadaptée. Cette famille de virus a en effet développé des stratégies d’échappement aux mécanismes précoces de l’immunité innée. Il en résulte une réplication virale massive qui induit une réponse immunitaire inappropriée à l’origine d’une réaction inflammatoire aiguë associée au syndrome hémorragique. Dans cette revue, nous décrivons les mécanismes utilisés par les filovirus, tels que le virus Ébola, pour échapper à la réponse immunitaire innée.
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221
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Lässig C, Lammens K, Gorenflos López JL, Michalski S, Fettscher O, Hopfner KP. Unified mechanisms for self-RNA recognition by RIG-I Singleton-Merten syndrome variants. eLife 2018; 7:e38958. [PMID: 30047865 PMCID: PMC6086658 DOI: 10.7554/elife.38958] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 07/24/2018] [Indexed: 12/13/2022] Open
Abstract
The innate immune sensor retinoic acid-inducible gene I (RIG-I) detects cytosolic viral RNA and requires a conformational change caused by both ATP and RNA binding to induce an active signaling state and to trigger an immune response. Previously, we showed that ATP hydrolysis removes RIG-I from lower-affinity self-RNAs (Lässig et al., 2015), revealing how ATP turnover helps RIG-I distinguish viral from self-RNA and explaining why a mutation in a motif that slows down ATP hydrolysis causes the autoimmune disease Singleton-Merten syndrome (SMS). Here we show that a different, mechanistically unexplained SMS variant, C268F, which is localized in the ATP-binding P-loop, can signal independently of ATP but is still dependent on RNA. The structure of RIG-I C268F in complex with double-stranded RNA reveals that C268F helps induce a structural conformation in RIG-I that is similar to that induced by ATP. Our results uncover an unexpected mechanism to explain how a mutation in a P-loop ATPase can induce a gain-of-function ATP state in the absence of ATP.
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Affiliation(s)
- Charlotte Lässig
- Department of BiochemistryLudwig-Maximilians-Universität MünchenMunichGermany
- Gene Center, Ludwig-Maximilians-Universität MünchenMunichGermany
| | - Katja Lammens
- Department of BiochemistryLudwig-Maximilians-Universität MünchenMunichGermany
- Gene Center, Ludwig-Maximilians-Universität MünchenMunichGermany
| | - Jacob Lucián Gorenflos López
- Department of BiochemistryLudwig-Maximilians-Universität MünchenMunichGermany
- Gene Center, Ludwig-Maximilians-Universität MünchenMunichGermany
| | - Sebastian Michalski
- Department of BiochemistryLudwig-Maximilians-Universität MünchenMunichGermany
- Gene Center, Ludwig-Maximilians-Universität MünchenMunichGermany
| | - Olga Fettscher
- Department of BiochemistryLudwig-Maximilians-Universität MünchenMunichGermany
- Gene Center, Ludwig-Maximilians-Universität MünchenMunichGermany
| | - Karl-Peter Hopfner
- Department of BiochemistryLudwig-Maximilians-Universität MünchenMunichGermany
- Gene Center, Ludwig-Maximilians-Universität MünchenMunichGermany
- Center for Integrated Protein Science MunichMunichGermany
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222
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Abstract
In a recent Cell paper, Jiang et al. (2018) have shown that lnc-Lsm3b, a long non-coding RNA induced by type I IFN late in the infection in mouse macrophages, prevents further activation of RIG-I acting as a decoy for RIG-I.
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Affiliation(s)
- Dominique Garcin
- Department of Microbiology and Molecular Medicine, Centre Médical Universitaire, 1 rue Michel Servet, 1211, Geneva 4, Switzerland.
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223
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Yong HY, Luo D. RIG-I-Like Receptors as Novel Targets for Pan-Antivirals and Vaccine Adjuvants Against Emerging and Re-Emerging Viral Infections. Front Immunol 2018; 9:1379. [PMID: 29973930 PMCID: PMC6019452 DOI: 10.3389/fimmu.2018.01379] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 06/04/2018] [Indexed: 12/18/2022] Open
Abstract
Emerging and re-emerging viruses pose a significant public health challenge around the world, among which RNA viruses are the cause of many major outbreaks of infectious diseases. As one of the early lines of defense in the human immune system, RIG-I-like receptors (RLRs) play an important role as sentinels to thwart the progression of virus infection. The activation of RLRs leads to an antiviral state in the host cells, which triggers the adaptive arm of immunity and ultimately the clearance of viral infections. Hence, RLRs are promising targets for the development of pan-antivirals and vaccine adjuvants. Here, we discuss the opportunities and challenges of developing RLR agonists into antiviral therapeutic agents and vaccine adjuvants against a broad range of viruses.
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Affiliation(s)
- Hui Yee Yong
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore.,NTU Institute of Structural Biology, Nanyang Technological University, Singapore, Singapore.,School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Dahai Luo
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore.,NTU Institute of Structural Biology, Nanyang Technological University, Singapore, Singapore
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224
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Arenaviral Nucleoproteins Suppress PACT-Induced Augmentation of RIG-I Function To Inhibit Type I Interferon Production. J Virol 2018; 92:JVI.00482-18. [PMID: 29669840 DOI: 10.1128/jvi.00482-18] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 04/13/2018] [Indexed: 12/28/2022] Open
Abstract
RIG-I is a major cytoplasmic sensor of viral pathogen-associated molecular pattern (PAMP) RNA and induces type I interferon (IFN) production upon viral infection. A double-stranded RNA (dsRNA)-binding protein, PACT, plays an important role in potentiating RIG-I function. We have shown previously that arenaviral nucleoproteins (NPs) suppress type I IFN production via their RNase activity to degrade PAMP RNA. We report here that NPs of arenaviruses block the PACT-induced enhancement of RIG-I function to mediate type I IFN production and that this inhibition is dependent on the RNase function of NPs, which is different from that of a known mechanism of other viral proteins to abolish the interaction between PACT and RIG-I. To understand the biological roles of PACT and RIG-I in authentic arenavirus infection, we analyze growth kinetics of recombinant Pichinde virus (PICV), a prototypical arenavirus, in RIG-I knockout (KO) and PACT KO mouse embryonic fibroblast (MEF) cells. Wild-type (WT) PICV grew at higher titers in both KO MEF lines than in normal MEFs, suggesting the important roles of these cellular proteins in restricting virus replication. PICV carrying the NP RNase catalytically inactive mutation could not grow in normal MEFs but could replicate to some extent in both KO MEF lines. The level of virus growth was inversely correlated with the amount of type I IFNs produced. These results suggest that PACT plays an important role in potentiating RIG-I function to produce type I IFNs in order to restrict arenavirus replication and that viral NP RNase activity is essential for optimal viral replication by suppressing PACT-induced RIG-I activation.IMPORTANCE We report here a new role of the nucleoproteins of arenaviruses that can block type I IFN production via their specific inhibition of the cellular protein sensors of virus infection (RIG-I and PACT). Our results suggest that PACT plays an important role in potentiating RIG-I function to produce type I IFNs in order to restrict arenavirus replication. This new knowledge can be exploited for the development of novel antiviral treatments and/or vaccines against some arenaviruses that can cause severe and lethal hemorrhagic fever diseases in humans.
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225
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Zhao K, Du J, Peng Y, Li P, Wang S, Wang Y, Hou J, Kang J, Zheng W, Hua S, Yu XF. LINE1 contributes to autoimmunity through both RIG-I- and MDA5-mediated RNA sensing pathways. J Autoimmun 2018; 90:105-115. [PMID: 29525183 DOI: 10.1016/j.jaut.2018.02.007] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 02/15/2018] [Accepted: 02/17/2018] [Indexed: 12/25/2022]
Abstract
Improper host immune activation leads to the development of the autoimmune disease Aicardi-Goutières syndrome (AGS), which is attributed to defined genetic mutations in such proteins as TREX1 and ADAR1. The mechanism of immune activation in AGS patients has not been thoroughly elucidated to date. In this study, we report that endogenous LINE1 components trigger IFNβ production in multiple human cell types, including those defective for cGAS/STING-mediated DNA sensing. In these cells, LINE1 DNA synthesis and retrotransposition were not required for LINE1-triggered immune activation, but RNA sensing pathways were essential. LINE1-triggered immune activation could be suppressed by diverse LINE1 inhibitors, including AGS-associated proteins targeting LINE1 RNA or proteins. However, AGS-associated ADAR1 or TREX1 mutants were defective in suppressing LINE1 retrotransposition or LINE1-triggered immune activation. Therefore, we have revealed a new function for LINE1 as an endogenous trigger of innate immune activation, which is important for understanding the molecular basis of IFN-based autoimmune diseases and may offer new intervention strategies.
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Affiliation(s)
- Ke Zhao
- Institute of Virology and AIDS Research, The First Hospital of Jilin University, 519 E. Minzhu St., Changchun, Jilin 130061, China.
| | - Juan Du
- Institute of Virology and AIDS Research, The First Hospital of Jilin University, 519 E. Minzhu St., Changchun, Jilin 130061, China
| | - Yanfeng Peng
- Institute of Virology and AIDS Research, The First Hospital of Jilin University, 519 E. Minzhu St., Changchun, Jilin 130061, China
| | - Peng Li
- Institute of Virology and AIDS Research, The First Hospital of Jilin University, 519 E. Minzhu St., Changchun, Jilin 130061, China
| | - Shaohua Wang
- Institute of Virology and AIDS Research, The First Hospital of Jilin University, 519 E. Minzhu St., Changchun, Jilin 130061, China
| | - Yu Wang
- Institute of Virology and AIDS Research, The First Hospital of Jilin University, 519 E. Minzhu St., Changchun, Jilin 130061, China
| | - Jingwei Hou
- Institute of Virology and AIDS Research, The First Hospital of Jilin University, 519 E. Minzhu St., Changchun, Jilin 130061, China
| | - Jian Kang
- Institute of Virology and AIDS Research, The First Hospital of Jilin University, 519 E. Minzhu St., Changchun, Jilin 130061, China
| | - Wenwen Zheng
- Institute of Virology and AIDS Research, The First Hospital of Jilin University, 519 E. Minzhu St., Changchun, Jilin 130061, China
| | - Shucheng Hua
- Institute of Virology and AIDS Research, The First Hospital of Jilin University, 519 E. Minzhu St., Changchun, Jilin 130061, China; Department of Internal Medicine, The First Hospital of Jilin University, Changchun, Jilin 130061, China.
| | - Xiao-Fang Yu
- Institute of Virology and AIDS Research, The First Hospital of Jilin University, 519 E. Minzhu St., Changchun, Jilin 130061, China; Cancer Institute (Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education), Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310009, China.
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226
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Nanson JD, Rahaman MH, Ve T, Kobe B. Regulation of signaling by cooperative assembly formation in mammalian innate immunity signalosomes by molecular mimics. Semin Cell Dev Biol 2018; 99:96-114. [PMID: 29738879 DOI: 10.1016/j.semcdb.2018.05.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 03/18/2018] [Accepted: 05/04/2018] [Indexed: 12/16/2022]
Abstract
Innate immunity pathways constitute the first line of defense against infections and cellular damage. An emerging concept in these pathways is that signaling involves the formation of finite (e.g. rings in NLRs) or open-ended higher-order assemblies (e.g. filamentous assemblies by members of the death-fold family and TIR domains). This signaling by cooperative assembly formation (SCAF) mechanism allows rapid and strongly amplified responses to minute amounts of stimulus. While the characterization of the molecular mechanisms of SCAF has seen rapid progress, little is known about its regulation. One emerging theme involves proteins produced both in host cells and by pathogens that appear to mimic the signaling components. Recently characterized examples involve the capping of the filamentous assemblies formed by caspase-1 CARDs by the CARD-only protein INCA, and those formed by caspase-8 by the DED-containing protein MC159. By contrast, the CARD-only protein ICEBERG and the DED-containing protein cFLIP incorporate into signaling filaments and presumably interfere with proximity based activation of caspases. We review selected examples of SCAF in innate immunity pathways and focus on the current knowledge on signaling component mimics produced by mammalian and pathogen cells and what is known about their mechanisms of action.
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Affiliation(s)
- Jeffrey D Nanson
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD, 4072, Australia
| | - Md Habibur Rahaman
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD, 4072, Australia
| | - Thomas Ve
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD, 4072, Australia; Institute for Glycomics, Griffith University, Southport, QLD, 4222, Australia
| | - Bostjan Kobe
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD, 4072, Australia.
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227
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Wu S, Lin J, Fu Y, Ou Q. RIG-I enhances interferon-α response by promoting antiviral protein expression in patients with chronic hepatitis B. Antivir Ther 2018; 23:575-583. [PMID: 29790851 DOI: 10.3851/imp3239] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/11/2018] [Indexed: 10/16/2022]
Abstract
BACKGROUND Interferon (IFN)-α is widely used for the treatment of chronic hepatitis B (CHB) infection due to the high rate of hepatitis B surface antigen (HBsAg) seroconversion. However, IFN-α treatment has a number of side effects. Thus, identification of molecular biomarkers to predict IFN-α therapeutic effect would be useful in the clinic. In this study, we aimed to investigate the role of retinoic acid-inducible gene-I (RIG-I) in prediction of IFN-α curative effect of CHB patients. METHODS A total of 65 CHB patients treated with pegylated IFN-α weekly for 48 weeks were enrolled. Real-time PCR was performed for detection of RIG-I and IFN-stimulated gene (ISG) expression. In vitro, the HepG2 cells were transfected with siRNA and levels of RIG-I and anti-HBV proteins were detected by western blot. The P-values were calculated in SPSS 18.0. The statistical significance level was accepted as P<0.05. RESULTS In this study, we found RIG-I expression in peripheral blood mononuclear cells was higher in responder than non-responder CHB patients treated with IFN-α therapy. In HBV-transfected HepG2 and Huh7 cells, RIG-I enhanced IFN-α response by promoting anti-HBV protein expression such as double-stranded RNA-dependent protein kinase (PKR), oligoadenylate synthetase (OAS), adenosine deaminase (ADAR1) and Mx protein. Knocking down of RIG-I could downregulate the expression of these proteins. Inhibited RIG-I expression by RIG-I siRNA deceased STAT1 phosphorylation. CONCLUSIONS Our results revealed RIG-I enhanced IFN-α response by promoting antiviral protein expression via the STAT1 pathway. RIG-I may be a new predictive factor for prediction of IFN-α efficacy in CHB patients.
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MESH Headings
- 2',5'-Oligoadenylate Synthetase/genetics
- 2',5'-Oligoadenylate Synthetase/immunology
- Adenosine Deaminase/genetics
- Adenosine Deaminase/immunology
- Adult
- Antiviral Agents/therapeutic use
- DEAD Box Protein 58/antagonists & inhibitors
- DEAD Box Protein 58/genetics
- DEAD Box Protein 58/immunology
- Female
- Follow-Up Studies
- Gene Expression Regulation/drug effects
- Gene Expression Regulation/immunology
- Hep G2 Cells
- Hepatitis B Surface Antigens/blood
- Hepatitis B virus/drug effects
- Hepatitis B virus/genetics
- Hepatitis B virus/immunology
- Hepatitis B, Chronic/drug therapy
- Hepatitis B, Chronic/immunology
- Hepatitis B, Chronic/virology
- Host-Pathogen Interactions/drug effects
- Host-Pathogen Interactions/genetics
- Host-Pathogen Interactions/immunology
- Humans
- Interferon-alpha/therapeutic use
- Leukocytes, Mononuclear/drug effects
- Leukocytes, Mononuclear/immunology
- Leukocytes, Mononuclear/virology
- Male
- Myxovirus Resistance Proteins/genetics
- Myxovirus Resistance Proteins/immunology
- Polyethylene Glycols/therapeutic use
- RNA, Small Interfering/genetics
- RNA, Small Interfering/metabolism
- RNA-Binding Proteins/genetics
- RNA-Binding Proteins/immunology
- Receptors, Immunologic
- Recombinant Proteins/therapeutic use
- STAT1 Transcription Factor/genetics
- STAT1 Transcription Factor/immunology
- Signal Transduction
- Treatment Outcome
- Viral Load/drug effects
- eIF-2 Kinase/genetics
- eIF-2 Kinase/immunology
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Affiliation(s)
- Shu Wu
- Department of Laboratory Medicine, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
- First Clinical College, Fujian Medical University, Fuzhou, China
| | - Jinpiao Lin
- Department of Laboratory Medicine, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
- First Clinical College, Fujian Medical University, Fuzhou, China
| | - Ya Fu
- Department of Laboratory Medicine, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
- First Clinical College, Fujian Medical University, Fuzhou, China
| | - Qishui Ou
- Department of Laboratory Medicine, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
- First Clinical College, Fujian Medical University, Fuzhou, China
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228
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Koliopoulos MG, Lethier M, van der Veen AG, Haubrich K, Hennig J, Kowalinski E, Stevens RV, Martin SR, Reis e Sousa C, Cusack S, Rittinger K. Molecular mechanism of influenza A NS1-mediated TRIM25 recognition and inhibition. Nat Commun 2018; 9:1820. [PMID: 29739942 PMCID: PMC5940772 DOI: 10.1038/s41467-018-04214-8] [Citation(s) in RCA: 112] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 04/13/2018] [Indexed: 02/04/2023] Open
Abstract
RIG-I is a viral RNA sensor that induces the production of type I interferon (IFN) in response to infection with a variety of viruses. Modification of RIG-I with K63-linked poly-ubiquitin chains, synthesised by TRIM25, is crucial for activation of the RIG-I/MAVS signalling pathway. TRIM25 activity is targeted by influenza A virus non-structural protein 1 (NS1) to suppress IFN production and prevent an efficient host immune response. Here we present structures of the human TRIM25 coiled-coil-PRYSPRY module and of complexes between the TRIM25 coiled-coil domain and NS1. These structures show that binding of NS1 interferes with the correct positioning of the PRYSPRY domain of TRIM25 required for substrate ubiquitination and provide a mechanistic explanation for how NS1 suppresses RIG-I ubiquitination and hence downstream signalling. In contrast, the formation of unanchored K63-linked poly-ubiquitin chains is unchanged by NS1 binding, indicating that RING dimerisation of TRIM25 is not affected by NS1.
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Affiliation(s)
- Marios G Koliopoulos
- Molecular Structure of Cell Signalling Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Mathilde Lethier
- European Molecular Biology Laboratory, 71 Avenue des Martyrs, 38042, Grenoble, Cedex 9, France
| | | | - Kevin Haubrich
- Structural and Computational Biology Unit, EMBL Heidelberg, Meyerhofstraße 1, 69117, Heidelberg, Germany
| | - Janosch Hennig
- Structural and Computational Biology Unit, EMBL Heidelberg, Meyerhofstraße 1, 69117, Heidelberg, Germany
| | - Eva Kowalinski
- European Molecular Biology Laboratory, 71 Avenue des Martyrs, 38042, Grenoble, Cedex 9, France
| | - Rebecca V Stevens
- Molecular Structure of Cell Signalling Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Stephen R Martin
- Structural Biology Science Technology Platform, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Caetano Reis e Sousa
- Immunobiology Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Stephen Cusack
- European Molecular Biology Laboratory, 71 Avenue des Martyrs, 38042, Grenoble, Cedex 9, France
| | - Katrin Rittinger
- Molecular Structure of Cell Signalling Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK.
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229
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Jiang M, Zhang S, Yang Z, Lin H, Zhu J, Liu L, Wang W, Liu S, Liu W, Ma Y, Zhang L, Cao X. Self-Recognition of an Inducible Host lncRNA by RIG-I Feedback Restricts Innate Immune Response. Cell 2018; 173:906-919.e13. [DOI: 10.1016/j.cell.2018.03.064] [Citation(s) in RCA: 157] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 02/17/2018] [Accepted: 03/26/2018] [Indexed: 12/25/2022]
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230
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Kumar A, Satpati P. Energetics of Preferential Binding of Retinoic Acid-Inducible Gene-I to Double-Stranded Viral RNAs with 5' Tri-/Diphosphate over 5' Monophosphate. ACS OMEGA 2018; 3:3786-3795. [PMID: 30023880 PMCID: PMC6044841 DOI: 10.1021/acsomega.7b02019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 03/23/2018] [Indexed: 06/08/2023]
Abstract
Retinoic acid-inducible gene-I (RIG-I) is a cytosolic sensor protein that recognizes viral RNAs and triggers an innate immune response in cells. Panhandle-like base-paired blunt-ended 5' ppp/pp-dsRNA is a characteristic feature of viral RNAs. Structural studies of RIG-I C-terminal domain bound 5' ppp/pp-dsRNA complexes show the direct interaction between all the 5' terminal phosphates (α, β, and γ) and protein, suggesting γ phosphate might be a major recognition determinant for RIG-I binding. Biochemical studies, however, suggest that 5' pp-dsRNA is the minimal determinant for RIG-I binding and antiviral response. Despite biochemical and structural studies, the origin of viral RNA recognition by RIG-I is an unsolved problem. X-ray structures of RIG-I bound dsRNA not only provide atomic insight into the interaction network but also provide sufficiently good models for computational studies. We report structure-based molecular dynamics (MD) free energy calculations to quantitatively estimate the energetics of RIG-I binding to dsRNA containing 5' ppp, 5' pp, and 5' p. The results suggest that RIG-I weakly discriminates between 5' ppp-dsRNA and 5' pp-dsRNA (favoring former) and strongly disfavors 5' p-dsRNA with respect to the rest. Interestingly, direct interaction between γ phosphate of 5' ppp-dsRNA and RIG-I is a robust feature of the MD simulations. dsRNA binding to RIG-I is associated with Mg2+ dissociation from the 5' phosphate/s of dsRNA. The higher Mg2+ dissociation penalty from 5' ppp-dsRNA with respect to 5' pp-dsRNA offsets most of the favorable interaction between RIG-I and γ phosphate of 5' ppp-dsRNA. This leads to weak discrimination between 5' ppp-dsRNA and 5' pp-dsRNA. 5' p-dsRNA is discriminated strongly because of the loss of interaction with RIG-I.
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231
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Liu Z, Wang J, Cheng H, Ke X, Sun L, Zhang QC, Wang HW. Cryo-EM Structure of Human Dicer and Its Complexes with a Pre-miRNA Substrate. Cell 2018; 173:1191-1203.e12. [PMID: 29706542 DOI: 10.1016/j.cell.2018.03.080] [Citation(s) in RCA: 102] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 01/02/2018] [Accepted: 03/28/2018] [Indexed: 12/26/2022]
Abstract
Human Dicer (hDicer) is a multi-domain protein belonging to the RNase III family. It plays pivotal roles in small RNA biogenesis during the RNA interference (RNAi) pathway by processing a diverse range of double-stranded RNA (dsRNA) precursors to generate ∼22 nt microRNA (miRNA) or small interfering RNA (siRNA) products for sequence-directed gene silencing. In this work, we solved the cryoelectron microscopy (cryo-EM) structure of hDicer in complex with its cofactor protein TRBP and revealed the precise spatial arrangement of hDicer's multiple domains. We further solved structures of the hDicer-TRBP complex bound with pre-let-7 RNA in two distinct conformations. In combination with biochemical analysis, these structures reveal a property of the hDicer-TRBP complex to promote the stability of pre-miRNA's stem duplex in a pre-dicing state. These results provide insights into the mechanism of RNA processing by hDicer and illustrate the regulatory role of hDicer's N-terminal helicase domain.
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Affiliation(s)
- Zhongmin Liu
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China 100084
| | - Jia Wang
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China 100084
| | - Hang Cheng
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China 100084; Joint Graduate Program of Peking-Tsinghua-NIBS, School of Life Sciences, Tsinghua University, Beijing, China 100084
| | - Xin Ke
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China 100084
| | - Lei Sun
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China 100084
| | - Qiangfeng Cliff Zhang
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China 100084
| | - Hong-Wei Wang
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China 100084.
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232
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Bhattarai D, Worku T, Dad R, Rehman ZU, Gong X, Zhang S. Mechanism of pattern recognition receptors (PRRs) and host pathogen interplay in bovine mastitis. Microb Pathog 2018; 120:64-70. [PMID: 29635052 DOI: 10.1016/j.micpath.2018.04.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 04/01/2018] [Accepted: 04/06/2018] [Indexed: 02/08/2023]
Abstract
Bacterial infection in the mammary gland parenchyma induces local and subsequently systemic inflammation that results in a complex disease. Mastitis in bovine is the result of various factors which function together. This review is aimed to analyze the factors involved in the pathogenesis of common bacterial species for bovine mastitis. The bacterial growth patterns, signaling pathway and the pathogen-associated molecular patterns (PAMPs) which activate immune responses is discussed. Clear differences in bacterial infection pattern are shown between bacterial species and illustrated TLRs, NLRs and RLGs molecular mechanism for the initiation of intramammary infection. The underlying reasons for the differences and the resulting host response are analyzed. Understandings of the mechanisms that activate and regulate these responses are central to the development of efficient anticipatory and treatment management. The knowledge of bovine mammary gland to common mastitis causing pathogens with possible immune mechanism could be a new conceptual understanding for the prospect of mastitis control program.
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Affiliation(s)
- Dinesh Bhattarai
- Key Laboratory of Animal Genetics, Breeding and Reproduction, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, 430071, China.
| | - Tesfaye Worku
- Key Laboratory of Animal Genetics, Breeding and Reproduction, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, 430071, China
| | - Rahim Dad
- Key Laboratory of Animal Genetics, Breeding and Reproduction, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, 430071, China
| | - Zia Ur Rehman
- Key Laboratory of Animal Genetics, Breeding and Reproduction, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, 430071, China
| | - Xiaoling Gong
- The Agricultural Broadcasting and Television School in Hubei Province, Wuhan, 430064, China
| | - Shujun Zhang
- Key Laboratory of Animal Genetics, Breeding and Reproduction, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, 430071, China.
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233
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Shah N, Beckham SA, Wilce JA, Wilce M. Combined roles of ATP and small hairpin RNA in the activation of RIG-I revealed by solution-based analysis. Nucleic Acids Res 2018; 46:3169-3186. [PMID: 29346611 PMCID: PMC5887321 DOI: 10.1093/nar/gkx1307] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2017] [Revised: 12/19/2017] [Accepted: 12/24/2017] [Indexed: 12/24/2022] Open
Abstract
RIG-I (retinoic acid inducible gene-I) is a cytosolic innate immune protein that senses viral dsRNA with a 5'-triphosphate overhang. Upon interaction with dsRNA a de-repression of the RIG-I CARD domains takes place that ultimately leads to the production of type I interferons and pro-inflammatory cytokines. Here we investigate the RIG-I conformational rearrangement upon interaction with an activating 5'-triphosphate-10-base pair dsRNA hairpin loop (10bp) compared with a less active 5'-triphosphate-8-base pair dsRNA hairpin loop (8bp). We use size-exclusion chromatography-coupled small-angle X-ray scattering (SAXS) and limited tryptic digest experiments to show that that upon binding to 10 bp, but not 8 bp, RIG-I becomes extended and shows greater flexibility, reflecting the release of its CARDs. We also examined the effect of different ATP analogues on the conformational changes of RIG-I/dsRNA complexes. Of the analogues tested, the addition of ATP transition state analogue ADP-AlFx further assisted in the complete activation of RIG-I in complex with 10bp and also to some extent RIG-I bound to 8bp. Together these data provide solution-based evidence for the molecular mechanism of innate immune signaling by RIG-I as stimulated by short hairpin RNA and ATP.
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Affiliation(s)
- Neelam Shah
- Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
| | - Simone A Beckham
- Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
| | - Jacqueline A Wilce
- Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
| | - Matthew C J Wilce
- Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
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234
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Haque N, Ouda R, Chen C, Ozato K, Hogg JR. ZFR coordinates crosstalk between RNA decay and transcription in innate immunity. Nat Commun 2018; 9:1145. [PMID: 29559679 PMCID: PMC5861047 DOI: 10.1038/s41467-018-03326-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 02/05/2018] [Indexed: 12/29/2022] Open
Abstract
Control of type I interferon production is crucial to combat infection while preventing deleterious inflammatory responses, but the extent of the contribution of post-transcriptional mechanisms to innate immune regulation is unclear. Here, we show that human zinc finger RNA-binding protein (ZFR) represses the interferon response by regulating alternative pre-mRNA splicing. ZFR expression is tightly controlled during macrophage development; monocytes express truncated ZFR isoforms, while macrophages induce full-length ZFR to modulate macrophage-specific alternative splicing. Interferon-stimulated genes are constitutively activated by ZFR depletion, and immunostimulation results in hyper-induction of interferon β (IFNβ/IFNB1). Through whole-genome analyses, we show that ZFR controls interferon signaling by preventing aberrant splicing and nonsense-mediated decay of histone variant macroH2A1/H2AFY mRNAs. Together, our data suggest that regulation of ZFR in macrophage differentiation guards against aberrant interferon responses and reveal a network of mRNA processing and decay that shapes the transcriptional response to infection. Type I interferon signaling is critical for the control of infection. Here the authors show that zinc finger RNA-binding protein (ZFR) can control type I interferon responses, and that this control is itself regulated by distinct ZFR truncation patterns that differ between monocytes and macrophages.
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Affiliation(s)
- Nazmul Haque
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, 50 South Drive, Room 2341, Bethesda, MD, 20892, USA.
| | - Ryota Ouda
- Division of Developmental Biology, National Institute of Child Health and Human Development, National Institutes of Health, 6 Center Drive, Room 2A01, Bethesda, MD, 20892, USA
| | - Chao Chen
- Division of Developmental Biology, National Institute of Child Health and Human Development, National Institutes of Health, 6 Center Drive, Room 2A01, Bethesda, MD, 20892, USA
| | - Keiko Ozato
- Division of Developmental Biology, National Institute of Child Health and Human Development, National Institutes of Health, 6 Center Drive, Room 2A01, Bethesda, MD, 20892, USA
| | - J Robert Hogg
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, 50 South Drive, Room 2341, Bethesda, MD, 20892, USA.
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235
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Lee SMY, Yip TF, Yan S, Jin DY, Wei HL, Guo RT, Peiris JSM. Recognition of Double-Stranded RNA and Regulation of Interferon Pathway by Toll-Like Receptor 10. Front Immunol 2018; 9:516. [PMID: 29616030 PMCID: PMC5865411 DOI: 10.3389/fimmu.2018.00516] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 02/27/2018] [Indexed: 12/16/2022] Open
Abstract
Toll-like receptor (TLR)-10 remains an orphan receptor without well-characterized ligands or functions. Here, we reveal that TLR10 is predominantly localized to endosomes and binds dsRNA in vitro at endosomal pH, suggesting that dsRNA is a ligand of TLR10. Recognition of dsRNA by TLR10 activates recruitment of myeloid differentiation primary response gene 88 for signal transduction and suppression of interferon regulatory factor-7 dependent type I IFN production. We also demonstrate crosstalk between TLR10 and TLR3, as they compete with each other for dsRNA binding. Our results suggest for the first time that dsRNA is a ligand for TLR10 and propose novel dual functions of TLR10 in regulating IFN signaling: first, recognition of dsRNA as a nucleotide-sensing receptor and second, sequestration of dsRNA from TLR3 to inhibit TLR3 signaling in response to dsRNA stimulation.
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Affiliation(s)
- Suki Man-Yan Lee
- HKU-Pasteur Research Pole and Center of Influenza Research, Li Ka Shing Faculty of Medicine, School of Public Health, The University of Hong Kong, Pokfulam, Hong Kong
| | - Tsz-Fung Yip
- HKU-Pasteur Research Pole and Center of Influenza Research, Li Ka Shing Faculty of Medicine, School of Public Health, The University of Hong Kong, Pokfulam, Hong Kong
| | - Sheng Yan
- HKU-Pasteur Research Pole and Center of Influenza Research, Li Ka Shing Faculty of Medicine, School of Public Health, The University of Hong Kong, Pokfulam, Hong Kong
| | - Dong-Yan Jin
- Li Ka Shing Faculty of Medicine, School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Hong-Li Wei
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
| | - Rey-Ting Guo
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
| | - Joseph Sriyal Malik Peiris
- HKU-Pasteur Research Pole and Center of Influenza Research, Li Ka Shing Faculty of Medicine, School of Public Health, The University of Hong Kong, Pokfulam, Hong Kong
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236
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Poirier EZ, Goic B, Tomé-Poderti L, Frangeul L, Boussier J, Gausson V, Blanc H, Vallet T, Loyd H, Levi LI, Lanciano S, Baron C, Merkling SH, Lambrechts L, Mirouze M, Carpenter S, Vignuzzi M, Saleh MC. Dicer-2-Dependent Generation of Viral DNA from Defective Genomes of RNA Viruses Modulates Antiviral Immunity in Insects. Cell Host Microbe 2018; 23:353-365.e8. [PMID: 29503180 PMCID: PMC5857290 DOI: 10.1016/j.chom.2018.02.001] [Citation(s) in RCA: 111] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 11/08/2017] [Accepted: 02/07/2018] [Indexed: 12/21/2022]
Abstract
The RNAi pathway confers antiviral immunity in insects. Virus-specific siRNA responses are amplified via the reverse transcription of viral RNA to viral DNA (vDNA). The nature, biogenesis, and regulation of vDNA are unclear. We find that vDNA produced during RNA virus infection of Drosophila and mosquitoes is present in both linear and circular forms. Circular vDNA (cvDNA) is sufficient to produce siRNAs that confer partially protective immunity when challenged with a cognate virus. cvDNAs bear homology to defective viral genomes (DVGs), and DVGs serve as templates for vDNA and cvDNA synthesis. Accordingly, DVGs promote the amplification of vDNA-mediated antiviral RNAi responses in infected Drosophila. Furthermore, vDNA synthesis is regulated by the DExD/H helicase domain of Dicer-2 in a mechanism distinct from its role in siRNA generation. We suggest that, analogous to mammalian RIG-I-like receptors, Dicer-2 functions like a pattern recognition receptor for DVGs to modulate antiviral immunity in insects.
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Affiliation(s)
- Enzo Z Poirier
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France; Institut Pasteur, Viral Populations and Pathogenesis, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France; University of Paris Diderot, Sorbonne Paris Cité, Cellule Pasteur, 75013 Paris, France
| | - Bertsy Goic
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France
| | - Lorena Tomé-Poderti
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France
| | - Lionel Frangeul
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France
| | - Jérémy Boussier
- Institut Pasteur, Immunobiology of Dendritic Cells, Institut National de la Santé et de la Recherche Médicale, U1223, 75015 Paris, France
| | - Valérie Gausson
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France
| | - Hervé Blanc
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France; Institut Pasteur, Viral Populations and Pathogenesis, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France
| | - Thomas Vallet
- Institut Pasteur, Viral Populations and Pathogenesis, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France
| | - Hyelee Loyd
- Department of Animal Science, Iowa State University, Ames, IA 50010, USA
| | - Laura I Levi
- Institut Pasteur, Viral Populations and Pathogenesis, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France
| | - Sophie Lanciano
- Institut de Recherche pour le Développement, DIADE, Université de Montpellier, Université de Perpignan, LGDP, 66860 Perpignan, France
| | - Chloé Baron
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France
| | - Sarah H Merkling
- Institut Pasteur, Insect-Virus Interactions, Centre National de la Recherche Scientifique URA 3012, 75015 Paris, France
| | - Louis Lambrechts
- Institut Pasteur, Insect-Virus Interactions, Centre National de la Recherche Scientifique URA 3012, 75015 Paris, France
| | - Marie Mirouze
- Institut de Recherche pour le Développement, DIADE, Université de Montpellier, Université de Perpignan, LGDP, 66860 Perpignan, France
| | - Susan Carpenter
- Department of Animal Science, Iowa State University, Ames, IA 50010, USA
| | - Marco Vignuzzi
- Institut Pasteur, Viral Populations and Pathogenesis, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France.
| | - Maria-Carla Saleh
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France.
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237
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Abstract
Innate immunity is traditionally thought of as the first line of defense against pathogens that enter the body. It is typically characterized as a rather weak defense mechanism, designed to restrict pathogen replication until the adaptive immune response generates a tailored response and eliminates the infectious agent. However, intensive research in recent years has resulted in better understanding of innate immunity as well as the discovery of many effector proteins, revealing its numerous powerful mechanisms to defend the host. Furthermore, this research has demonstrated that it is simplistic to strictly separate adaptive and innate immune functions since these two systems often work synergistically rather than sequentially. Here, we provide a broad overview of innate pattern recognition receptors in antiviral defense, with a focus on the TRIM family, and discuss their signaling pathways and mechanisms of action with special emphasis on the intracellular antibody receptor TRIM21.
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Affiliation(s)
| | - Leo C James
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom.
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238
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Masliah G, Maris C, König SL, Yulikov M, Aeschimann F, Malinowska AL, Mabille J, Weiler J, Holla A, Hunziker J, Meisner-Kober N, Schuler B, Jeschke G, Allain FHT. Structural basis of siRNA recognition by TRBP double-stranded RNA binding domains. EMBO J 2018; 37:embj.201797089. [PMID: 29449323 PMCID: PMC5852647 DOI: 10.15252/embj.201797089] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 01/10/2018] [Accepted: 01/12/2018] [Indexed: 11/23/2022] Open
Abstract
The accurate cleavage of pre‐micro(mi)RNAs by Dicer and mi/siRNA guide strand selection are important steps in forming the RNA‐induced silencing complex (RISC). The role of Dicer binding partner TRBP in these processes remains poorly understood. Here, we solved the solution structure of the two N‐terminal dsRNA binding domains (dsRBDs) of TRBP in complex with a functionally asymmetric siRNA using NMR, EPR, and single‐molecule spectroscopy. We find that siRNA recognition by the dsRBDs is not sequence‐specific but rather depends on the RNA shape. The two dsRBDs can swap their binding sites, giving rise to two equally populated, pseudo‐symmetrical complexes, showing that TRBP is not a primary sensor of siRNA asymmetry. Using our structure to model a Dicer‐TRBP‐siRNA ternary complex, we show that TRBP's dsRBDs and Dicer's RNase III domains bind a canonical 19 base pair siRNA on opposite sides, supporting a mechanism whereby TRBP influences Dicer‐mediated cleavage accuracy by binding the dsRNA region of the pre‐miRNA during Dicer cleavage.
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Affiliation(s)
- Gregoire Masliah
- Institute of Molecular Biology and Biophysics, ETH Zürich, Zürich, Switzerland
| | - Christophe Maris
- Institute of Molecular Biology and Biophysics, ETH Zürich, Zürich, Switzerland
| | | | - Maxim Yulikov
- Laboratory of Physical Chemistry, ETH Zürich, Zürich, Switzerland
| | | | - Anna L Malinowska
- Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich, Switzerland
| | - Julie Mabille
- Novartis Institutes for Biomedical Research, Basel, Switzerland
| | - Jan Weiler
- Novartis Institutes for Biomedical Research, Basel, Switzerland
| | - Andrea Holla
- Department of Biochemistry, University of Zürich, Zürich, Switzerland
| | - Juerg Hunziker
- Novartis Institutes for Biomedical Research, Basel, Switzerland
| | | | - Benjamin Schuler
- Department of Biochemistry, University of Zürich, Zürich, Switzerland
| | - Gunnar Jeschke
- Laboratory of Physical Chemistry, ETH Zürich, Zürich, Switzerland
| | - Frederic H-T Allain
- Institute of Molecular Biology and Biophysics, ETH Zürich, Zürich, Switzerland
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239
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Linehan MM, Dickey TH, Molinari ES, Fitzgerald ME, Potapova O, Iwasaki A, Pyle AM. A minimal RNA ligand for potent RIG-I activation in living mice. SCIENCE ADVANCES 2018; 4:e1701854. [PMID: 29492454 PMCID: PMC5821489 DOI: 10.1126/sciadv.1701854] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 01/22/2018] [Indexed: 05/08/2023]
Abstract
We have developed highly potent synthetic activators of the vertebrate immune system that specifically target the RIG-I receptor. When introduced into mice, a family of short, triphosphorylated stem-loop RNAs (SLRs) induces a potent interferon response and the activation of specific genes essential for antiviral defense. Using RNA sequencing, we provide the first in vivo genome-wide view of the expression networks that are initiated upon RIG-I activation. We observe that SLRs specifically induce type I interferons, subsets of interferon-stimulated genes (ISGs), and cellular remodeling factors. By contrast, polyinosinic:polycytidylic acid [poly(I:C)], which binds and activates multiple RNA sensors, induces type III interferons and several unique ISGs. The short length (10 to 14 base pairs) and robust function of SLRs in mice demonstrate that RIG-I forms active signaling complexes without oligomerizing on RNA. These findings demonstrate that SLRs are potent therapeutic and investigative tools for targeted modulation of the innate immune system.
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Affiliation(s)
| | - Thayne H. Dickey
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA
| | - Emanuela S. Molinari
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA
| | - Megan E. Fitzgerald
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA
| | - Olga Potapova
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA
| | - Akiko Iwasaki
- Department of Immunobiology, Yale University, New Haven, CT 06520, USA
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA
- Howard Hughes Medical Institute, Yale University, New Haven, CT 06520, USA
| | - Anna M. Pyle
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA
- Howard Hughes Medical Institute, Yale University, New Haven, CT 06520, USA
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Lee J, Park EB, Min J, Sung SE, Jang Y, Shin JS, Chun D, Kim KH, Hwang J, Lee MK, Go YY, Kwon D, Kim M, Kang SJ, Choi BS. Systematic editing of synthetic RIG-I ligands to produce effective antiviral and anti-tumor RNA immunotherapies. Nucleic Acids Res 2018; 46:1635-1647. [PMID: 29373735 PMCID: PMC5829749 DOI: 10.1093/nar/gky039] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 01/17/2018] [Indexed: 12/25/2022] Open
Abstract
Retinoic acid-inducible gene I (RIG-I) recognizes double-stranded viral RNAs (dsRNAs) containing two or three 5' phosphates. A few reports of 5'-PPP-independent RIG-I agonists have emerged, but little is known about the molecular principles underlying their recognition. We recently found that the bent duplex RNA from the influenza A panhandle promoter activates RIG-I even in the absence of a 5'-triphosphate moiety. Here, we report that non-canonical synthetic RNA oligonucleotides containing G-U wobble base pairs that form a bent helix can exert RIG-I-mediated antiviral and anti-tumor effects in a sequence- and site-dependent manner. We present synthetic RNAs that have been systematically modified to enhance their efficacy and we outline the basic principles for engineering RIG-I agonists applicable to immunotherapy.
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Affiliation(s)
- Janghyun Lee
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, South Korea
| | - Eun-Byeol Park
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, South Korea
| | - Jiyoun Min
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, South Korea
| | - Si-Eun Sung
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, South Korea
| | - Yejin Jang
- Center for Virus Research and Testing, Korea Research Institute of Chemical Technology, 141 Gajeong-ro, Yuseong-gu, Daejeon 34114, South Korea
| | - Jin Soo Shin
- Center for Virus Research and Testing, Korea Research Institute of Chemical Technology, 141 Gajeong-ro, Yuseong-gu, Daejeon 34114, South Korea
| | - Dongmin Chun
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, South Korea
| | - Ki-Hun Kim
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, South Korea
| | - Jihyun Hwang
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, South Korea
| | - Mi-Kyung Lee
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, South Korea
| | - Yun Young Go
- Center for Virus Research and Testing, Korea Research Institute of Chemical Technology, 141 Gajeong-ro, Yuseong-gu, Daejeon 34114, South Korea
| | - Dohyeong Kwon
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, South Korea
| | - Meehyein Kim
- Center for Virus Research and Testing, Korea Research Institute of Chemical Technology, 141 Gajeong-ro, Yuseong-gu, Daejeon 34114, South Korea
| | - Suk-Jo Kang
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, South Korea
| | - Byong-Seok Choi
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, South Korea
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241
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D'Cruz AA, Kershaw NJ, Hayman TJ, Linossi EM, Chiang JJ, Wang MK, Dagley LF, Kolesnik TB, Zhang JG, Masters SL, Griffin MDW, Gack MU, Murphy JM, Nicola NA, Babon JJ, Nicholson SE. Identification of a second binding site on the TRIM25 B30.2 domain. Biochem J 2018; 475:429-440. [PMID: 29259080 PMCID: PMC6200327 DOI: 10.1042/bcj20170427] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 12/18/2017] [Accepted: 12/19/2017] [Indexed: 12/29/2022]
Abstract
The retinoic acid-inducible gene-I (RIG-I) receptor recognizes short 5'-di- and triphosphate base-paired viral RNA and is a critical mediator of the innate immune response against viruses such as influenza A, Ebola, HIV and hepatitis C. This response is reported to require an orchestrated interaction with the tripartite motif 25 (TRIM25) B30.2 protein-interaction domain. Here, we present a novel second RIG-I-binding interface on the TRIM25 B30.2 domain that interacts with CARD1 and CARD2 (caspase activation and recruitment domains) of RIG-I and is revealed by the removal of an N-terminal α-helix that mimics dimerization of the full-length protein. Further characterization of the TRIM25 coiled-coil and B30.2 regions indicated that the B30.2 domains move freely on a flexible tether, facilitating RIG-I CARD recruitment. The identification of a dual binding mode for the TRIM25 B30.2 domain is a first for the SPRY/B30.2 domain family and may be a feature of other SPRY/B30.2 family members.
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Affiliation(s)
- Akshay A D'Cruz
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- The University of Melbourne, Parkville, Victoria, Australia
| | - Nadia J Kershaw
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- The University of Melbourne, Parkville, Victoria, Australia
| | - Thomas J Hayman
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- The University of Melbourne, Parkville, Victoria, Australia
| | - Edmond M Linossi
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- The University of Melbourne, Parkville, Victoria, Australia
| | - Jessica J Chiang
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, U. S. A
| | - May K Wang
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, U. S. A
| | - Laura F Dagley
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- The University of Melbourne, Parkville, Victoria, Australia
| | - Tatiana B Kolesnik
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | - Jian-Guo Zhang
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- The University of Melbourne, Parkville, Victoria, Australia
| | - Seth L Masters
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- The University of Melbourne, Parkville, Victoria, Australia
| | | | - Michaela U Gack
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, U. S. A
| | - James M Murphy
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- The University of Melbourne, Parkville, Victoria, Australia
| | - Nicos A Nicola
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- The University of Melbourne, Parkville, Victoria, Australia
| | - Jeffrey J Babon
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- The University of Melbourne, Parkville, Victoria, Australia
| | - Sandra E Nicholson
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- The University of Melbourne, Parkville, Victoria, Australia
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242
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Pickens JA, Tripp RA. Verdinexor Targeting of CRM1 is a Promising Therapeutic Approach against RSV and Influenza Viruses. Viruses 2018; 10:E48. [PMID: 29361733 PMCID: PMC5795461 DOI: 10.3390/v10010048] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Revised: 01/15/2018] [Accepted: 01/17/2018] [Indexed: 12/11/2022] Open
Abstract
Two primary causes of respiratory tract infections are respiratory syncytial virus (RSV) and influenza viruses, both of which remain major public health concerns. There are a limited number of antiviral drugs available for the treatment of RSV and influenza, each having limited effectiveness and each driving selective pressure for the emergence of drug-resistant viruses. Novel broad-spectrum antivirals are needed to circumvent problems with current disease intervention strategies, while improving the cytokine-induced immunopathology associated with RSV and influenza infections. In this review, we examine the use of Verdinexor (KPT-335, a novel orally bioavailable drug that functions as a selective inhibitor of nuclear export, SINE), as an antiviral with multifaceted therapeutic potential. KPT-335 works to (1) block CRM1 (i.e., Chromosome Region Maintenance 1; exportin 1 or XPO1) mediated export of viral proteins critical for RSV and influenza pathogenesis; and (2) repress nuclear factor κB (NF-κB) activation, thus reducing cytokine production and eliminating virus-associated immunopathology. The repurposing of SINE compounds as antivirals shows promise not only against RSV and influenza virus but also against other viruses that exploit the nucleus as part of their viral life cycle.
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Affiliation(s)
- Jennifer A Pickens
- Department of Infectious Diseases, University of Georgia, Athens, GA 30602, USA.
| | - Ralph A Tripp
- Department of Infectious Diseases, University of Georgia, Athens, GA 30602, USA.
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243
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Sinha NK, Iwasa J, Shen PS, Bass BL. Dicer uses distinct modules for recognizing dsRNA termini. Science 2018; 359:329-334. [PMID: 29269422 PMCID: PMC6154394 DOI: 10.1126/science.aaq0921] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 12/11/2017] [Indexed: 12/19/2022]
Abstract
Invertebrates rely on Dicer to cleave viral double-stranded RNA (dsRNA), and Drosophila Dicer-2 distinguishes dsRNA substrates by their termini. Blunt termini promote processive cleavage, while 3' overhanging termini are cleaved distributively. To understand this discrimination, we used cryo-electron microscopy to solve structures of Drosophila Dicer-2 alone and in complex with blunt dsRNA. Whereas the Platform-PAZ domains have been considered the only Dicer domains that bind dsRNA termini, unexpectedly, we found that the helicase domain is required for binding blunt, but not 3' overhanging, termini. We further showed that blunt dsRNA is locally unwound and threaded through the helicase domain in an adenosine triphosphate-dependent manner. Our studies reveal a previously unrecognized mechanism for optimizing antiviral defense and set the stage for the discovery of helicase-dependent functions in other Dicers.
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Affiliation(s)
- Niladri K. Sinha
- Department of Biochemistry, University of Utah, Salt Lake City, UT, 84112, USA
| | - Janet Iwasa
- Department of Biochemistry, University of Utah, Salt Lake City, UT, 84112, USA
| | - Peter S. Shen
- Department of Biochemistry, University of Utah, Salt Lake City, UT, 84112, USA
| | - Brenda L. Bass
- Department of Biochemistry, University of Utah, Salt Lake City, UT, 84112, USA
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244
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Cancer therapies activate RIG-I-like receptor pathway through endogenous non-coding RNAs. Oncotarget 2018; 7:26496-515. [PMID: 27034163 PMCID: PMC5041995 DOI: 10.18632/oncotarget.8420] [Citation(s) in RCA: 118] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Accepted: 03/05/2016] [Indexed: 12/14/2022] Open
Abstract
Emerging evidence indicates that ionizing radiation (IR) and chemotherapy activate Type I interferon (IFN) signaling in tumor and host cells. However, the mechanism of induction is poorly understood. We identified a novel radioprotective role for the DEXH box RNA helicase LGP2 (DHX58) through its suppression of IR-induced cytotoxic IFN-beta [1]. LGP2 inhibits activation of the RIG-I-like receptor (RLR) pathway upon binding of viral RNA to the cytoplasmic sensors RIG-I (DDX58) and MDA5 (IFIH1) and subsequent IFN signaling via the mitochondrial adaptor protein MAVS (IPS1). Here we show that MAVS is necessary for IFN-beta induction and interferon-stimulated gene expression in the response to IR. Suppression of MAVS conferred radioresistance in normal and cancer cells. Germline deletion of RIG-I, but not MDA5, protected mice from death following total body irradiation, while deletion of LGP2 accelerated the death of irradiated animals. In human tumors depletion of RIG-I conferred resistance to IR and different classes of chemotherapy drugs. Mechanistically, IR stimulated the binding of cytoplasmic RIG-I with small endogenous non-coding RNAs (sncRNAs), which triggered IFN-beta activity. We demonstrate that the small nuclear RNAs U1 and U2 translocate to the cytoplasm after IR treatment, thus stimulating the formation of RIG-I: RNA complexes and initiating downstream signaling events. Taken together, these findings suggest that the physiologic responses to radio-/chemo-therapy converge on an antiviral program in recruitment of the RLR pathway by a sncRNA-dependent activation of RIG-I which commences cytotoxic IFN signaling. Importantly, activation of interferon genes by radiation or chemotherapy is associated with a favorable outcome in patients undergoing treatment for cancer. To our knowledge, this is the first demonstration of a cell-intrinsic response to clinically relevant genotoxic treatments mediated by an RNA-dependent mechanism.
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245
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Fang R, Jiang Q, Zhou X, Wang C, Guan Y, Tao J, Xi J, Feng JM, Jiang Z. MAVS activates TBK1 and IKKε through TRAFs in NEMO dependent and independent manner. PLoS Pathog 2017; 13:e1006720. [PMID: 29125880 PMCID: PMC5699845 DOI: 10.1371/journal.ppat.1006720] [Citation(s) in RCA: 127] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 11/22/2017] [Accepted: 10/30/2017] [Indexed: 11/19/2022] Open
Abstract
Mitochondrial antiviral-signaling protein (MAVS) transmits signals from RIG-I-like receptors after RNA virus infections. However, the mechanism by which MAVS activates downstream components, such as TBK1 and IKKα/β, is unclear, although previous work suggests the involvement of NEMO or TBK1-binding proteins TANK, NAP1, and SINTBAD. Here, we report that MAVS-mediated innate immune activation is dependent on TRAFs, partially on NEMO, but not on TBK1-binding proteins. MAVS recruited TBK1/IKKε by TRAFs that were pre-associated with TBK1/IKKε via direct interaction between the coiled-coil domain of TRAFs and the SDD domain of TBK1/IKKε. TRAF2-/-3-/-5-/-6-/- cells completely lost RNA virus responses. TRAFs' E3 ligase activity was required for NEMO activation by synthesizing ubiquitin chains that bound to NEMO for NF-κB and TBK1/IKKε activation. NEMO-activated IKKα/β were important for TBK1/IKKε activation through IKKα/β-mediated TBK1/IKKε phosphorylation. Moreover, individual TRAFs differently mediated TBK1/IKKε activation and thus fine-tuned antiviral immunity under physiological conditions.
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Affiliation(s)
- Run Fang
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, School of Life Sciences, Peking University, Beijing, China
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Qifei Jiang
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, School of Life Sciences, Peking University, Beijing, China
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Xiang Zhou
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, School of Life Sciences, Peking University, Beijing, China
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Chenguang Wang
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, School of Life Sciences, Peking University, Beijing, China
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Yukun Guan
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, School of Life Sciences, Peking University, Beijing, China
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Jianli Tao
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, School of Life Sciences, Peking University, Beijing, China
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Jianzhong Xi
- Institute of Molecular Medicine, Peking University, Beijing, China
| | - Ji-Ming Feng
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Zhengfan Jiang
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, School of Life Sciences, Peking University, Beijing, China
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
- * E-mail:
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246
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Jie C, Luo Z, Chen H, Wang M, Yan C, Mao ZF, Xiao GK, Kurihara H, Li YF, He RR. Indirubin, a bisindole alkaloid from Isatis indigotica, reduces H1N1 susceptibility in stressed mice by regulating MAVS signaling. Oncotarget 2017; 8:105615-105629. [PMID: 29285277 PMCID: PMC5739664 DOI: 10.18632/oncotarget.22350] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2017] [Accepted: 07/18/2017] [Indexed: 12/22/2022] Open
Abstract
Isatis indigotica has a long history in treating virus infection and related symptoms in China. Nevertheless, its antivirus evidence in animal studies is not satisfactory, which might be due to the lack of appropriate animal model. Previously, we had utilized restraint stress to establish mouse H1N1 susceptibility model which was helpful in evaluating the anti-virus effect of medicines targeting host factors, such as type I interferon production. In this study, this model was employed to investigate the effect and mechanism of indirubin, a natural bisindole alkaloid from Isatis indigotica, on influenza A virus susceptibility. In the in vitro study, the stress hormone corticosterone was used to simulate restraint stress. Our results demonstrated that indirubin decreased the susceptibility to influenza virus with lowered mortality and alleviated lung damage in restraint-stressed mice model. Moreover, indirubin promoted the expression of interferon-β and interferon inducible transmembrane 3. In addition, indirubin maintained the morphology and function of mitochondria following influenza A virus infection. Further study revealed that indirubin promoted interferon-β production through promoting mitochondrial antiviral signaling pathway. Our study indicated that indirubin could be a candidate for the therapy of influenza.
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Affiliation(s)
- Chong Jie
- Anti-Stress and Health Research Center, College of Pharmacy, Jinan University, Guangzhou 510632, China.,Institute of Traditional Chinese Medicine & Natural Products, Jinan University, Guangzhou 510632, China
| | - Zhuo Luo
- Anti-Stress and Health Research Center, College of Pharmacy, Jinan University, Guangzhou 510632, China.,Institute of Traditional Chinese Medicine & Natural Products, Jinan University, Guangzhou 510632, China
| | - Huan Chen
- Anti-Stress and Health Research Center, College of Pharmacy, Jinan University, Guangzhou 510632, China.,Institute of Traditional Chinese Medicine & Natural Products, Jinan University, Guangzhou 510632, China
| | - Min Wang
- Department of Pharmacy, Hainan General Hospital, Hainan 570311, China
| | - Chang Yan
- Anti-Stress and Health Research Center, College of Pharmacy, Jinan University, Guangzhou 510632, China.,Institute of Traditional Chinese Medicine & Natural Products, Jinan University, Guangzhou 510632, China
| | - Zhong-Fu Mao
- Anti-Stress and Health Research Center, College of Pharmacy, Jinan University, Guangzhou 510632, China.,Institute of Traditional Chinese Medicine & Natural Products, Jinan University, Guangzhou 510632, China
| | - Gao-Keng Xiao
- Institute of Traditional Chinese Medicine & Natural Products, Jinan University, Guangzhou 510632, China
| | - Hiroshi Kurihara
- Anti-Stress and Health Research Center, College of Pharmacy, Jinan University, Guangzhou 510632, China.,Institute of Traditional Chinese Medicine & Natural Products, Jinan University, Guangzhou 510632, China
| | - Yi-Fang Li
- Anti-Stress and Health Research Center, College of Pharmacy, Jinan University, Guangzhou 510632, China.,Institute of Traditional Chinese Medicine & Natural Products, Jinan University, Guangzhou 510632, China
| | - Rong-Rong He
- Anti-Stress and Health Research Center, College of Pharmacy, Jinan University, Guangzhou 510632, China.,Institute of Traditional Chinese Medicine & Natural Products, Jinan University, Guangzhou 510632, China
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247
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Sarvestani ST, McAuley JL. The role of the NLRP3 inflammasome in regulation of antiviral responses to influenza A virus infection. Antiviral Res 2017; 148:32-42. [PMID: 29097227 DOI: 10.1016/j.antiviral.2017.10.020] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 10/20/2017] [Accepted: 10/27/2017] [Indexed: 12/25/2022]
Abstract
The innate immune system provides the host with both a dynamic barrier to prevent infection and a means to which rapid anti-microbial responses can be mounted. The inflammasome pathway is a critical host early response mechanism that enables detection of pathogens and initiates production of inflammatory cytokines, inducing recruitment of effector cells to the site of infection. The complete mechanism of inflammasome activation requires two signals: an initial priming step upon detection of pathogen, followed by activation of intracellular pattern recognition receptors critical to the formation of the inflammasome complex. The inflammasome complex is made of intracellular multiprotein oligomers which includes a sensor protein such as the nucleotide-binding oligomerization domain (NOD) like receptor proteins (NLRP), and an adapter protein, ASC, which critically activates pro-caspase-1. The mature caspase-1 then proteolytically cleaves cytosolic pro-IL-1β and pro-IL-18, which are then secreted as inflammatory cytokines that activate the inflammatory arm of the immune response to infection. Active caspase-1 also results in pyroptosis, which is a form of cell death triggered by inflammation. The induction and activation of IL-1β and IL-18 are considered critical signatures for inflammasome activation. With focus upon influenza A virus infection, this review will address present knowledge on the mechanisms of inflammasome complex activation, particularly how the viral components modulate activation of the cytosolic NOD-like receptor protein-3 (NLRP3)-dependent inflammasome complex. We also discuss potential therapeutic strategies that target the inflammasome to ameliorate illness, as well as novel methods of vaccination that target inflammasome stimulation with the aim to increase efficacy.
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Affiliation(s)
- Soroush T Sarvestani
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, 3000, Australia
| | - Julie L McAuley
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, 3000, Australia.
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248
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Molecular requirements for sensing of intracellular microbial nucleic acids by the innate immune system. Cytokine 2017; 98:4-14. [DOI: 10.1016/j.cyto.2016.10.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 10/11/2016] [Indexed: 12/24/2022]
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249
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Lu C, MacDougall M. RIG-I-Like Receptor Signaling in Singleton-Merten Syndrome. Front Genet 2017; 8:118. [PMID: 28955379 PMCID: PMC5600918 DOI: 10.3389/fgene.2017.00118] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 08/29/2017] [Indexed: 12/12/2022] Open
Abstract
Singleton-Merten syndrome (SMS) is an autosomal dominant, multi-system innate immune disorder characterized by early and severe aortic and valvular calcification, dental and skeletal abnormalities, psoriasis, glaucoma, and other varying clinical findings. Recently we identified a specific gain-of-function mutation in IFIH1, interferon induced with helicase C domain 1, segregated with this disease. SMS disease without hallmark dental anomalies, termed atypical SMS, has recently been reported caused by variants in DDX58, DEXD/H-box helicase 58. IFIH1 and DDX58 encode retinoic acid-inducible gene I (RIG-I)-like receptors family members melanoma differentiation-associated gene 5 and RIG-I, respectively. These cytosolic pattern recognition receptors function in viral RNA detection initiating an innate immune response through independent pathways that promote type I and type III interferon expression and proinflammatory cytokines. In this review, we focus on SMS as an innate immune disorder summarizing clinical features, molecular aspects of the pathogenetic pathway and discussing underlying mechanisms of the disease.
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Affiliation(s)
- Changming Lu
- Institute of Oral Health Research, School of Dentistry, University of Alabama at Birmingham, BirminghamAL, United States
| | - Mary MacDougall
- Faculty of Dentistry, University of British Columbia, VancouverBC, Canada
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Loquacious-PD facilitates Drosophila Dicer-2 cleavage through interactions with the helicase domain and dsRNA. Proc Natl Acad Sci U S A 2017; 114:E7939-E7948. [PMID: 28874570 DOI: 10.1073/pnas.1707063114] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Loquacious-PD (Loqs-PD) is required for biogenesis of many endogenous siRNAs in Drosophila In vitro, Loqs-PD enhances the rate of dsRNA cleavage by Dicer-2 and also enables processing of substrates normally refractory to cleavage. Using purified components, and Loqs-PD truncations, we provide a mechanistic basis for Loqs-PD functions. Our studies indicate that the 22 amino acids at the C terminus of Loqs-PD, including an FDF-like motif, directly interact with the Hel2 subdomain of Dicer-2's helicase domain. This interaction is RNA-independent, but we find that modulation of Dicer-2 cleavage also requires dsRNA binding by Loqs-PD. Furthermore, while the first dsRNA-binding motif of Loqs-PD is dispensable for enhancing cleavage of optimal substrates, it is essential for enhancing cleavage of suboptimal substrates. Finally, our studies define a previously unrecognized Dicer interaction interface and suggest that Loqs-PD is well positioned to recruit substrates into the helicase domain of Dicer-2.
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