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Lyu Z, Yang X, Yahashiri A, Ha S, McCausland JW, Chen X, Britton BM, Weiss DS, Xiao J. E. coli FtsN coordinates synthesis and degradation of septal peptidoglycan by partitioning between a synthesis track and a denuded glycan track. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.13.594014. [PMID: 39253420 PMCID: PMC11383011 DOI: 10.1101/2024.05.13.594014] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/11/2024]
Abstract
The E. coli cell division protein FtsN was proposed to coordinate septal peptidoglycan (sPG) synthesis and degradation to ensure robust cell wall constriction without lethal lesions. Although the precise mechanism remains unclear, previous work highlights the importance of two FtsN domains: the E domain, which interacts with and activates the sPG synthesis complex FtsWIQLB, and the SPOR domain, which binds to denuded glycan (dnG) strands, key intermediates in sPG degradation. Here, we used single-molecule tracking of FtsN and FtsW (a proxy for the sPG synthesis complex FtsWIQLB) to investigate how FtsN coordinates the two opposing processes. We observed dynamic behaviors indicating that FtsN's SPOR domain binds to dnGs cooperatively, which both sequesters the sPG synthesis complex on dnG (termed as the dnG-track) and protects dnGs from degradation by lytic transglycosylases (LTs). The release of the SPOR domain from dnGs leads to activating the sPG synthesis complex on the sPG-track and simultaneously exposing those same dnGs to degradation. Furthermore, FtsN's SPOR domain self-interacts and facilitates the formation of a multimeric sPG synthesis complex on both tracks. The cooperative self-interaction of the SPOR domain creates a sensitive switch to regulate the partitioning of FtsN between the dnG- and sPG-tracks, thereby controlling the balance between sequestered and active populations of the sPG synthesis complex. As such, FtsN coordinates sPG synthesis and degradation in space and time.
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Yu B, Chen Y, Yan Y, Lu X, Zhu B. DNA-terminus-dependent transcription by T7 RNA polymerase and its C-helix mutants. Nucleic Acids Res 2024; 52:8443-8453. [PMID: 38979568 DOI: 10.1093/nar/gkae593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 03/28/2024] [Accepted: 06/25/2024] [Indexed: 07/10/2024] Open
Abstract
The remarkable success of messenger RNA (mRNA)-based vaccines has underscored their potential as a novel biotechnology platform for vaccine development and therapeutic protein delivery. However, the single-subunit RNA polymerase from bacteriophage T7 widely used for in vitro transcription is well known to generate double-stranded RNA (dsRNA) by-products that strongly stimulate the mammalian innate immune response. The dsRNA was reported to be originated from self-templated RNA extension or promoter-independent transcription. Here, we identified that the primary source of the full-length dsRNA during in vitro transcription is the DNA-terminus-initiated transcription by T7 RNA polymerase. Guanosines or cytosines at the end of DNA templates enhance the DNA-terminus-initiated transcription. Moreover, we found that aromatic residues located at position 47 in the C-helix lead to a significant reduction in the production of full-length dsRNA. As a result, the mRNA synthesized using the T7 RNA polymerase G47W mutant exhibits higher expression efficiency and lower immunogenicity compared to the mRNA produced using the wild-type T7 RNA polymerase.
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Affiliation(s)
- Bingbing Yu
- Key Laboratory of Molecular Biophysics, Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Yifan Chen
- Key Laboratory of Molecular Biophysics, Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Yan Yan
- Key Laboratory of Molecular Biophysics, Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Xueling Lu
- Key Laboratory of Molecular Biophysics, Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Bin Zhu
- Key Laboratory of Molecular Biophysics, Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
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3
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Rehwinkel J, Mehdipour P. ADAR1: from basic mechanisms to inhibitors. Trends Cell Biol 2024:S0962-8924(24)00120-X. [PMID: 39030076 DOI: 10.1016/j.tcb.2024.06.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Revised: 06/17/2024] [Accepted: 06/20/2024] [Indexed: 07/21/2024]
Abstract
Adenosine deaminase acting on RNA 1 (ADAR1) converts adenosine to inosine in double-stranded RNA (dsRNA) molecules, a process known as A-to-I editing. ADAR1 deficiency in humans and mice results in profound inflammatory diseases characterised by the spontaneous induction of innate immunity. In cells lacking ADAR1, unedited RNAs activate RNA sensors. These include melanoma differentiation-associated gene 5 (MDA5) that induces the expression of cytokines, particularly type I interferons (IFNs), protein kinase R (PKR), oligoadenylate synthase (OAS), and Z-DNA/RNA binding protein 1 (ZBP1). Immunogenic RNAs 'defused' by ADAR1 may include transcripts from repetitive elements and other long duplex RNAs. Here, we review these recent fundamental discoveries and discuss implications for human diseases. Some tumours depend on ADAR1 to escape immune surveillance, opening the possibility of unleashing anticancer therapies with ADAR1 inhibitors.
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Affiliation(s)
- Jan Rehwinkel
- Medical Research Council Translational Immune Discovery Unit, Medical Research Council Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DS, UK.
| | - Parinaz Mehdipour
- Ludwig Institute for Cancer Research, Nuffield Department of Medicine, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Headington, Oxford OX3 7DQ, UK.
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Lenk R, Kleindienst W, Szabó GT, Baiersdörfer M, Boros G, Keller JM, Mahiny AJ, Vlatkovic I. Understanding the impact of in vitro transcription byproducts and contaminants. Front Mol Biosci 2024; 11:1426129. [PMID: 39050733 PMCID: PMC11266732 DOI: 10.3389/fmolb.2024.1426129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Accepted: 06/14/2024] [Indexed: 07/27/2024] Open
Abstract
The success of messenger (m)RNA-based vaccines against SARS-CoV-2 during the COVID-19 pandemic has led to rapid growth and innovation in the field of mRNA-based therapeutics. However, mRNA production, whether in small amounts for research or large-scale GMP-grade for biopharmaceutics, is still based on the In Vitro Transcription (IVT) reaction developed in the early 1980s. The IVT reaction exploits phage RNA polymerase to catalyze the formation of an engineered mRNA that depends on a linearized DNA template, nucleotide building blocks, as well as pH, temperature, and reaction time. But depending on the IVT conditions and subsequent purification steps, diverse byproducts such as dsRNA, abortive RNAs and RNA:DNA hybrids might form. Unwanted byproducts, if not removed, could be formulated together with the full-length mRNA and cause an immune response in cells by activating host pattern recognition receptors. In this review, we summarize the potential types of IVT byproducts, their known biological activity, and how they can impact the efficacy and safety of mRNA therapeutics. In addition, we briefly overview non-nucleotide-based contaminants such as RNases, endotoxin and metal ions that, when present in the IVT reaction, can also influence the activity of mRNA-based drugs. We further discuss current approaches aimed at adjusting the IVT reaction conditions or improving mRNA purification to achieve optimal performance for medical applications.
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Shibata K, Moriizumi H, Onomoto K, Kaneko Y, Miyakawa T, Zenno S, Tanokura M, Yoneyama M, Takahashi T, Ui-Tei K. Caspase-mediated processing of TRBP regulates apoptosis during viral infection. Nucleic Acids Res 2024; 52:5209-5225. [PMID: 38636948 PMCID: PMC11109963 DOI: 10.1093/nar/gkae246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 03/14/2024] [Accepted: 03/26/2024] [Indexed: 04/20/2024] Open
Abstract
RNA silencing is a post-transcriptional gene-silencing mechanism mediated by microRNAs (miRNAs). However, the regulatory mechanism of RNA silencing during viral infection is unclear. TAR RNA-binding protein (TRBP) is an enhancer of RNA silencing that induces miRNA maturation by interacting with the ribonuclease Dicer. TRBP interacts with a virus sensor protein, laboratory of genetics and physiology 2 (LGP2), in the early stage of viral infection of human cells. Next, it induces apoptosis by inhibiting the maturation of miRNAs, thereby upregulating the expression of apoptosis regulatory genes. In this study, we show that TRBP undergoes a functional conversion in the late stage of viral infection. Viral infection resulted in the activation of caspases that proteolytically processed TRBP into two fragments. The N-terminal fragment did not interact with Dicer but interacted with type I interferon (IFN) signaling modulators, such as protein kinase R (PKR) and LGP2, and induced ER stress. The end results were irreversible apoptosis and suppression of IFN signaling. Our results demonstrate that the processing of TRBP enhances apoptosis, reducing IFN signaling during viral infection.
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Affiliation(s)
- Keiko Shibata
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan
| | - Harune Moriizumi
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan
| | - Koji Onomoto
- Division of Molecular Immunology, Medical Mycology Research Center, Chiba University, Chiba 260-8673, Japan
| | - Yuka Kaneko
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan
| | - Takuya Miyakawa
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
| | - Shuhei Zenno
- Department of Biotechnology, Faculty of Engineering, Maebashi Institute of Technology, Gunma 371-0816, Japan
| | - Masaru Tanokura
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Mitsutoshi Yoneyama
- Division of Molecular Immunology, Medical Mycology Research Center, Chiba University, Chiba 260-8673, Japan
- Division of Pandemic and Post-disaster Infectious Diseases, Research Institute of Disaster Medicine, Chiba University, Chiba 260-8673, Japan
| | - Tomoko Takahashi
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
| | - Kumiko Ui-Tei
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba 277-8561, Japan
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Jarmoskaite I, Li JB. Multifaceted roles of RNA editing enzyme ADAR1 in innate immunity. RNA (NEW YORK, N.Y.) 2024; 30:500-511. [PMID: 38531645 PMCID: PMC11019752 DOI: 10.1261/rna.079953.124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 02/09/2024] [Indexed: 03/28/2024]
Abstract
Innate immunity must be tightly regulated to enable sensitive pathogen detection while averting autoimmunity triggered by pathogen-like host molecules. A hallmark of viral infection, double-stranded RNAs (dsRNAs) are also abundantly encoded in mammalian genomes, necessitating surveillance mechanisms to distinguish "self" from "nonself." ADAR1, an RNA editing enzyme, has emerged as an essential safeguard against dsRNA-induced autoimmunity. By converting adenosines to inosines (A-to-I) in long dsRNAs, ADAR1 covalently marks endogenous dsRNAs, thereby blocking the activation of the cytoplasmic dsRNA sensor MDA5. Moreover, beyond its editing function, ADAR1 binding to dsRNA impedes the activation of innate immune sensors PKR and ZBP1. Recent landmark studies underscore the utility of silencing ADAR1 for cancer immunotherapy, by exploiting the ADAR1-dependence developed by certain tumors to unleash an antitumor immune response. In this perspective, we summarize the genetic and mechanistic evidence for ADAR1's multipronged role in suppressing dsRNA-mediated autoimmunity and explore the evolving roles of ADAR1 as an immuno-oncology target.
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Affiliation(s)
- Inga Jarmoskaite
- Department of Genetics, Stanford University, Stanford, California 94305, USA
- AIRNA Corporation, Cambridge, Massachusetts 02142, USA
| | - Jin Billy Li
- Department of Genetics, Stanford University, Stanford, California 94305, USA
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Yoneyama M, Kato H, Fujita T. Physiological functions of RIG-I-like receptors. Immunity 2024; 57:731-751. [PMID: 38599168 DOI: 10.1016/j.immuni.2024.03.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2024] [Revised: 02/19/2024] [Accepted: 03/04/2024] [Indexed: 04/12/2024]
Abstract
RIG-I-like receptors (RLRs) are crucial for pathogen detection and triggering immune responses and have immense physiological importance. In this review, we first summarize the interferon system and innate immunity, which constitute primary and secondary responses. Next, the molecular structure of RLRs and the mechanism of sensing non-self RNA are described. Usually, self RNA is refractory to the RLR; however, there are underlying host mechanisms that prevent immune reactions. Studies have revealed that the regulatory mechanisms of RLRs involve covalent molecular modifications, association with regulatory factors, and subcellular localization. Viruses have evolved to acquire antagonistic RLR functions to escape the host immune reactions. Finally, the pathologies caused by the malfunction of RLR signaling are described.
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Affiliation(s)
- Mitsutoshi Yoneyama
- Division of Molecular Immunology, Medical Mycology Research Center, Chiba University, Chiba, Japan; Division of Pandemic and Post-disaster Infectious Diseases, Research Institute of Disaster Medicine, Chiba University, Chiba, Japan
| | - Hiroki Kato
- Institute of Cardiovascular Immunology, Medical Faculty, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Takashi Fujita
- Institute of Cardiovascular Immunology, Medical Faculty, University Hospital Bonn, University of Bonn, Bonn, Germany; Laboratory of Regulatory Information, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, Japan.
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8
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de Reuver R, Maelfait J. Novel insights into double-stranded RNA-mediated immunopathology. Nat Rev Immunol 2024; 24:235-249. [PMID: 37752355 DOI: 10.1038/s41577-023-00940-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2023] [Indexed: 09/28/2023]
Abstract
Recent progress in human and mouse genetics has transformed our understanding of the molecular mechanisms by which recognition of self double-stranded RNA (self-dsRNA) causes immunopathology. Novel mouse models recapitulate loss-of-function mutations in the RNA editing enzyme ADAR1 that are found in patients with Aicardi-Goutières syndrome (AGS) - a monogenic inflammatory disease associated with increased levels of type I interferon. Extensive analyses of the genotype-phenotype relationships in these mice have now firmly established a causal relationship between increased intracellular concentrations of endogenous immunostimulatory dsRNA and type I interferon-driven immunopathology. Activation of the dsRNA-specific immune sensor MDA5 perpetuates the overproduction of type I interferons, and chronic engagement of the interferon-inducible innate immune receptors PKR and ZBP1 by dsRNA drives immunopathology by activating an integrated stress response or by inducing excessive cell death. Biochemical and genetic data support a role for the p150 isoform of ADAR1 in the cytosol in suppressing the spontaneous, pathological response to self-dsRNA.
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Affiliation(s)
- Richard de Reuver
- VIB-UGent Center for Inflammation Research, Ghent, Belgium
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Jonathan Maelfait
- VIB-UGent Center for Inflammation Research, Ghent, Belgium.
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium.
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9
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Singh R, Wu Y, Herrero Del Valle A, Leigh KE, Mong S, Cheng MTK, Ferguson BJ, Modis Y. Contrasting functions of ATP hydrolysis by MDA5 and LGP2 in viral RNA sensing. J Biol Chem 2024; 300:105711. [PMID: 38309507 PMCID: PMC10909783 DOI: 10.1016/j.jbc.2024.105711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 01/16/2024] [Accepted: 01/24/2024] [Indexed: 02/05/2024] Open
Abstract
Cytosolic long dsRNA, among the most potent proinflammatory signals, is recognized by melanoma differentiation-associated protein 5 (MDA5). MDA5 binds dsRNA cooperatively forming helical filaments. ATP hydrolysis by MDA5 fulfills a proofreading function by promoting dissociation of shorter endogenous dsRNs from MDA5 while allowing longer viral dsRNAs to remain bound leading to activation of interferon-β responses. Here, we show that adjacent MDA5 subunits in MDA5-dsRNA filaments hydrolyze ATP cooperatively, inducing cooperative filament disassembly. Consecutive rounds of ATP hydrolysis amplify the filament footprint, displacing tightly bound proteins from dsRNA. Our electron microscopy and biochemical assays show that LGP2 binds to dsRNA at internal binding sites through noncooperative ATP hydrolysis. Unlike MDA5, LGP2 has low nucleic acid selectivity and can hydrolyze GTP and CTP as well as ATP. Binding of LGP2 to dsRNA promotes nucleation of MDA5 filament assembly resulting in shorter filaments. Molecular modeling identifies an internally bound MDA5-LGP2-RNA complex, with the LGP2 C-terminal tail forming the key contacts with MDA5. These contacts are specifically required for NTP-dependent internal RNA binding. We conclude that NTPase-dependent binding of LGP2 to internal dsRNA sites complements NTPase-independent binding to dsRNA ends, via distinct binding modes, to increase the number and signaling output of MDA5-dsRNA complexes.
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Affiliation(s)
- Rahul Singh
- Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Cambridge, UK; Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Department of Medicine, University of Cambridge, Cambridge, UK; Department of Pathology, University of Cambridge, Cambridge, UK
| | - Yuan Wu
- Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Cambridge, UK; Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Department of Medicine, University of Cambridge, Cambridge, UK
| | - Alba Herrero Del Valle
- Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Cambridge, UK; Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Department of Medicine, University of Cambridge, Cambridge, UK
| | - Kendra E Leigh
- Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Cambridge, UK; Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Department of Medicine, University of Cambridge, Cambridge, UK
| | - Sai Mong
- Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Cambridge, UK; Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Department of Medicine, University of Cambridge, Cambridge, UK
| | - Mark T K Cheng
- Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Cambridge, UK; Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Department of Medicine, University of Cambridge, Cambridge, UK
| | - Brian J Ferguson
- Department of Pathology, University of Cambridge, Cambridge, UK.
| | - Yorgo Modis
- Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Cambridge, UK; Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Department of Medicine, University of Cambridge, Cambridge, UK.
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10
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Luan X, Wang L, Song G, Zhou W. Innate immune responses to RNA: sensing and signaling. Front Immunol 2024; 15:1287940. [PMID: 38343534 PMCID: PMC10854198 DOI: 10.3389/fimmu.2024.1287940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 01/11/2024] [Indexed: 02/15/2024] Open
Abstract
Nucleic acids are among the most essential PAMPs (pathogen-associated molecular patterns). Animals have evolved numerous sensors to recognize nucleic acids and trigger immune signaling against pathogen replication, cellular stress and cancer. Many sensor proteins (e.g., cGAS, AIM2, and TLR9) recognize the molecular signature of infection or stress and are responsible for the innate immune response to DNA. Remarkably, recent evidence demonstrates that cGAS-like receptors acquire the ability to sense RNA in some forms of life. Compared with the nucleic-acid sensing by cGAS, innate immune responses to RNA are based on various RNA sensors, including RIG-I, MDA5, ADAR1, TLR3/7/8, OAS1, PKR, NLRP1/6, and ZBP1, via a broad-spectrum signaling axis. Importantly, new advances have brought to light the potential clinical application of targeting these signaling pathways. Here, we highlight the latest discoveries in the field. We also summarize the activation and regulatory mechanisms of RNA-sensing signaling. In addition, we discuss how RNA sensing is tightly controlled in cells and why the disruption of immune homeostasis is linked to disease.
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Affiliation(s)
- Xiaohan Luan
- Shenzhen Key Laboratory of Biomolecular Assembling and Regulation, Southern University of Science and Technology, Shenzhen, Guangdong, China
- Department of Immunology and Microbiology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Lei Wang
- Department of Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Guangji Song
- Department of Immunology and Microbiology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Wen Zhou
- Shenzhen Key Laboratory of Biomolecular Assembling and Regulation, Southern University of Science and Technology, Shenzhen, Guangdong, China
- Department of Immunology and Microbiology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong, China
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Youssef M, Hitti C, Puppin Chaves Fulber J, Kamen AA. Enabling mRNA Therapeutics: Current Landscape and Challenges in Manufacturing. Biomolecules 2023; 13:1497. [PMID: 37892179 PMCID: PMC10604719 DOI: 10.3390/biom13101497] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 10/05/2023] [Accepted: 10/06/2023] [Indexed: 10/29/2023] Open
Abstract
Recent advances and discoveries in the structure and role of mRNA as well as novel lipid-based delivery modalities have enabled the advancement of mRNA therapeutics into the clinical trial space. The manufacturing of these products is relatively simple and eliminates many of the challenges associated with cell culture production of viral delivery systems for gene and cell therapy applications, allowing rapid production of mRNA for personalized treatments, cancer therapies, protein replacement and gene editing. The success of mRNA vaccines during the COVID-19 pandemic highlighted the immense potential of this technology as a vaccination platform, but there are still particular challenges to establish mRNA as a widespread therapeutic tool. Immunostimulatory byproducts can pose a barrier for chronic treatments and different production scales may need to be considered for these applications. Moreover, long-term storage of mRNA products is notoriously difficult. This review provides a detailed overview of the manufacturing steps for mRNA therapeutics, including sequence design, DNA template preparation, mRNA production and formulation, while identifying the challenges remaining in the dose requirements, long-term storage and immunotolerance of the product.
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Affiliation(s)
| | | | | | - Amine A. Kamen
- Department of Bioengineering, McGill University, Montreal, QC H3A 0G4, Canada; (M.Y.); (C.H.); (J.P.C.F.)
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12
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Abo-Samaha MI, Sharaf MM, El-Nahas AF, Odemuyiwa SO. Length-Dependent Modulation of B Cell Activating Factor Transcripts in Chicken Macrophage by Viral Double-Stranded RNA. Vaccines (Basel) 2023; 11:1561. [PMID: 37896964 PMCID: PMC10611291 DOI: 10.3390/vaccines11101561] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 09/24/2023] [Accepted: 09/29/2023] [Indexed: 10/29/2023] Open
Abstract
Viral double-stranded RNA (dsRNA) interacts with Retinoic-acid-inducible-gene-1 (RIG-1)-like receptors (RLRs) to induce type 1 interferons. Melanoma-derived-antigen-5 (MDA-5), an RLR, but not RIG-1, is found in chickens. Ducks express both RIG-1 and MDA-5, a possible cause of differences in susceptibility to influenza virus infection between chickens and ducks. Using the HD11 chicken macrophage cell line and an RT2 Profiler PCR-array system, we showed that high-molecular-weight poly(I:C), HMW-poly(I:C), upregulates CCL4, interferon-gamma, interleukin-1, and interleukin-6 mRNA transcripts. HMW-poly(I:C), an in vitro surrogate of long dsRNA species, also induces the upregulation of IL-12B and B cell activating factor (BAFF). Conversely, low-molecular-weight poly(I:C), LMW-poly(I:C) did not induce a distinct cytokine expression pattern. Nonetheless, co-transfection of LMW and HMW-poly(I:C) significantly reduced the upregulation of IL12B and BAFF by HMW-poly(I:C). These findings support previous studies that found no expression of RIG-1, a receptor for short dsRNA species, in chicken cells. Surprisingly, however, our data suggested that in the absence of RIG-1 in chicken macrophages, short dsRNA species may inhibit macrophage-mediated B cell development and survival by modulating the expression of BAFF without significantly reducing type 1 interferon response.
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Affiliation(s)
- Magda I. Abo-Samaha
- Department of Pathobiology, College of Veterinary Medicine, Tuskegee University, Tuskegee, AL 36830, USA;
- Department of Animal Husbandry and Animal Wealth Development, Faculty of Veterinary Medicine, Alexandria University, Alexandria 5410012, Egypt; (M.M.S.); (A.F.E.-N.)
| | - Mohammed M. Sharaf
- Department of Animal Husbandry and Animal Wealth Development, Faculty of Veterinary Medicine, Alexandria University, Alexandria 5410012, Egypt; (M.M.S.); (A.F.E.-N.)
| | - Abeer F. El-Nahas
- Department of Animal Husbandry and Animal Wealth Development, Faculty of Veterinary Medicine, Alexandria University, Alexandria 5410012, Egypt; (M.M.S.); (A.F.E.-N.)
| | - Solomon O. Odemuyiwa
- Department of Pathobiology, College of Veterinary Medicine, Tuskegee University, Tuskegee, AL 36830, USA;
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211, USA
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13
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Paget M, Cadena C, Ahmad S, Wang HT, Jordan TX, Kim E, Koo B, Lyons SM, Ivanov P, tenOever B, Mu X, Hur S. Stress granules are shock absorbers that prevent excessive innate immune responses to dsRNA. Mol Cell 2023; 83:1180-1196.e8. [PMID: 37028415 PMCID: PMC10170497 DOI: 10.1016/j.molcel.2023.03.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Revised: 09/08/2022] [Accepted: 03/08/2023] [Indexed: 04/09/2023]
Abstract
Proper defense against microbial infection depends on the controlled activation of the immune system. This is particularly important for the RIG-I-like receptors (RLRs), which recognize viral dsRNA and initiate antiviral innate immune responses with the potential of triggering systemic inflammation and immunopathology. Here, we show that stress granules (SGs), molecular condensates that form in response to various stresses including viral dsRNA, play key roles in the controlled activation of RLR signaling. Without the SG nucleators G3BP1/2 and UBAP2L, dsRNA triggers excessive inflammation and immune-mediated apoptosis. In addition to exogenous dsRNA, host-derived dsRNA generated in response to ADAR1 deficiency is also controlled by SG biology. Intriguingly, SGs can function beyond immune control by suppressing viral replication independently of the RLR pathway. These observations thus highlight the multi-functional nature of SGs as cellular "shock absorbers" that converge on protecting cell homeostasis by dampening both toxic immune response and viral replication.
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Affiliation(s)
- Max Paget
- Program in Virology, Division of Medical Sciences, Harvard Medical School, Boston, MA 02115, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Cristhian Cadena
- Program in Virology, Division of Medical Sciences, Harvard Medical School, Boston, MA 02115, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Sadeem Ahmad
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston, MA 02115, USA
| | - Hai-Tao Wang
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Tristan X Jordan
- Department of Microbiology, New York University, Grossman School of Medicine, New York, NY 10016, USA
| | - Ehyun Kim
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Beechui Koo
- Morrisey School of Arts and Science, Boston College, Boston, MA 02467, USA
| | - Shawn M Lyons
- Department of Medicine, Harvard Medical School, Boston, MA 02115, USA; Division of Rheumatology, Inflammation, and Immunity, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Pavel Ivanov
- Department of Medicine, Harvard Medical School, Boston, MA 02115, USA; Division of Rheumatology, Inflammation, and Immunity, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Benjamin tenOever
- Department of Microbiology, New York University, Grossman School of Medicine, New York, NY 10016, USA
| | - Xin Mu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Sun Hur
- Program in Virology, Division of Medical Sciences, Harvard Medical School, Boston, MA 02115, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston, MA 02115, USA.
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14
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Dousis A, Ravichandran K, Hobert EM, Moore MJ, Rabideau AE. An engineered T7 RNA polymerase that produces mRNA free of immunostimulatory byproducts. Nat Biotechnol 2023; 41:560-568. [PMID: 36357718 PMCID: PMC10110463 DOI: 10.1038/s41587-022-01525-6] [Citation(s) in RCA: 53] [Impact Index Per Article: 53.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 09/22/2022] [Indexed: 11/12/2022]
Abstract
In vitro transcription (IVT) is a DNA-templated process for synthesizing long RNA transcripts, including messenger RNA (mRNA). For many research and commercial applications, IVT of mRNA is typically performed using bacteriophage T7 RNA polymerase (T7 RNAP) owing to its ability to produce full-length RNA transcripts with high fidelity; however, T7 RNAP can also produce immunostimulatory byproducts such as double-stranded RNA that can affect protein expression. Such byproducts require complex purification processes, using methods such as reversed-phase high-performance liquid chromatography, to yield safe and effective mRNA-based medicines. To minimize the need for downstream purification processes, we rationally and computationally engineered a double mutant of T7 RNAP that produces substantially less immunostimulatory RNA during IVT compared with wild-type T7 RNAP. The resulting mutant allows for a simplified production process with similar mRNA potency, lower immunostimulatory content and quicker manufacturing time compared with wild-type T7 RNAP. Herein, we describe the computational design and development of this improved T7 RNAP variant.
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Affiliation(s)
- Athanasios Dousis
- Moderna, Inc., Cambridge, MA, USA
- Tessera Therapeutics, Somerville, MA, USA
| | | | - Elissa M Hobert
- Moderna, Inc., Cambridge, MA, USA
- Laronde, Cambridge, MA, USA
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15
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Ke PY. Crosstalk between Autophagy and RLR Signaling. Cells 2023; 12:cells12060956. [PMID: 36980296 PMCID: PMC10047499 DOI: 10.3390/cells12060956] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 03/17/2023] [Accepted: 03/20/2023] [Indexed: 03/30/2023] Open
Abstract
Autophagy plays a homeostatic role in regulating cellular metabolism by degrading unwanted intracellular materials and acts as a host defense mechanism by eliminating infecting pathogens, such as viruses. Upon viral infection, host cells often activate retinoic acid-inducible gene I (RIG-I)-like receptor (RLR) signaling to induce the transcription of type I interferons, thus establishing the first line of the innate antiviral response. In recent years, numerous studies have shown that virus-mediated autophagy activation may benefit viral replication through different actions on host cellular processes, including the modulation of RLR-mediated innate immunity. Here, an overview of the functional molecules and regulatory mechanism of the RLR antiviral immune response as well as autophagy is presented. Moreover, a summary of the current knowledge on the biological role of autophagy in regulating RLR antiviral signaling is provided. The molecular mechanisms underlying the crosstalk between autophagy and RLR innate immunity are also discussed.
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Affiliation(s)
- Po-Yuan Ke
- Department of Biochemistry & Molecular Biology, Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan
- Liver Research Center, Chang Gung Memorial Hospital, Taoyuan 33305, Taiwan
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16
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IFN-Induced PARPs—Sensors of Foreign Nucleic Acids? Pathogens 2023; 12:pathogens12030457. [PMID: 36986379 PMCID: PMC10057411 DOI: 10.3390/pathogens12030457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Revised: 03/10/2023] [Accepted: 03/12/2023] [Indexed: 03/17/2023] Open
Abstract
Cells have developed different strategies to cope with viral infections. Key to initiating a defense response against viruses is the ability to distinguish foreign molecules from their own. One central mechanism is the perception of foreign nucleic acids by host proteins which, in turn, initiate an efficient immune response. Nucleic acid sensing pattern recognition receptors have evolved, each targeting specific features to discriminate viral from host RNA. These are complemented by several RNA-binding proteins that assist in sensing of foreign RNAs. There is increasing evidence that the interferon-inducible ADP-ribosyltransferases (ARTs; PARP9—PARP15) contribute to immune defense and attenuation of viruses. However, their activation, subsequent targets, and precise mechanisms of interference with viruses and their propagation are still largely unknown. Best known for its antiviral activities and its role as RNA sensor is PARP13. In addition, PARP9 has been recently described as sensor for viral RNA. Here we will discuss recent findings suggesting that some PARPs function in antiviral innate immunity. We expand on these findings and integrate this information into a concept that outlines how the different PARPs might function as sensors of foreign RNA. We speculate about possible consequences of RNA binding with regard to the catalytic activities of PARPs, substrate specificity and signaling, which together result in antiviral activities.
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17
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Miyamoto M, Himeda T, Ishihara K, Okuwa T, Kobayashi D, Nameta M, Karasawa Y, Chunhaphinyokul B, Yoshida Y, Tanaka N, Higuchi M, Komuro A. Theilovirus 3C Protease Cleaves the C-Terminal Domain of the Innate Immune RNA Sensor, Melanoma Differentiation-Associated Gene 5, and Impairs Double-Stranded RNA-Mediated IFN Response. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2023; 210:335-347. [PMID: 36525065 DOI: 10.4049/jimmunol.2200565] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 11/09/2022] [Indexed: 01/04/2023]
Abstract
Melanoma differentiation-associated gene 5 (MDA5), a member of the retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs), has pivotal roles in innate immune responses against many positive-stranded RNA viruses, including picornavirus and coronavirus. Upon engagement with dsRNA derived from viral infection, MDA5 initiates coordinated signal transduction leading to type I IFN induction to restrict viral replication. In this study, we describe a targeted cleavage events of MDA5 by the 3C protease from Theilovirus. Upon ectopic expression of theilovirus 3C protease from Saffold virus or Theiler's murine encephalomyelitis virus but not encephalomyocarditis virus, fragments of cleaved MDA5 were observed in a dose-dependent manner. When enzymatically inactive Theilovirus 3C protease was expressed, MDA5 cleavage was completely abrogated. Mass spectrometric analysis identified two cleavage sites at the C terminus of MDA5, cleaving off one of the RNA-binding domains. The same cleavage pattern was observed during Theilovirus infection. The cleavage of MDA5 by Theilovirus protease impaired ATP hydrolysis, RNA binding, and filament assembly on RNA, resulting in dysfunction of MDA5 as an innate immune RNA sensor for IFN induction. Furthermore, the cleavage-resistant MDA5 mutant against the 3C protease showed an enhanced IFN response during Saffold virus infection, indicating that Theilovirus has a strategy to circumvent the antiviral immune response by cleaving MDA5 using 3C protease. In summary, these data suggest MDA5 cleavage by 3C protease as a novel immune evasive strategy of Theilovirus.
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Affiliation(s)
- Masahiko Miyamoto
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences, Niigata, Japan
| | - Toshiki Himeda
- Department of Microbiology, Kanazawa Medical University School of Medicine, Ishikawa, Japan
| | - Kazuki Ishihara
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences, Niigata, Japan
| | - Takako Okuwa
- Department of Microbiology, Kanazawa Medical University School of Medicine, Ishikawa, Japan
| | - Daiki Kobayashi
- Omics Unit, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Masaaki Nameta
- Electron Microscope Core Facility, Niigata University, Niigata, Japan
| | - Yu Karasawa
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences, Niigata, Japan
| | - Benyapa Chunhaphinyokul
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences, Niigata, Japan
| | - Yutaka Yoshida
- Department of Structural Pathology, Kidney Research Center, Niigata University, Niigata, Japan; and
| | - Nobuyuki Tanaka
- Division of Tumor Immunology, Miyagi Cancer Center Research Institute, Medeshima-Shiode, Natori, Miyagi, Japan
| | - Masaya Higuchi
- Department of Microbiology, Kanazawa Medical University School of Medicine, Ishikawa, Japan
| | - Akihiko Komuro
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences, Niigata, Japan
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18
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Nassour J, Aguiar LG, Correia A, Schmidt TT, Mainz L, Przetocka S, Haggblom C, Tadepalle N, Williams A, Shokhirev MN, Akincilar SC, Tergaonkar V, Shadel GS, Karlseder J. Telomere-to-mitochondria signalling by ZBP1 mediates replicative crisis. Nature 2023; 614:767-773. [PMID: 36755096 PMCID: PMC9946831 DOI: 10.1038/s41586-023-05710-8] [Citation(s) in RCA: 52] [Impact Index Per Article: 52.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 01/05/2023] [Indexed: 02/10/2023]
Abstract
Cancers arise through the accumulation of genetic and epigenetic alterations that enable cells to evade telomere-based proliferative barriers and achieve immortality. One such barrier is replicative crisis-an autophagy-dependent program that eliminates checkpoint-deficient cells with unstable telomeres and other cancer-relevant chromosomal aberrations1,2. However, little is known about the molecular events that regulate the onset of this important tumour-suppressive barrier. Here we identified the innate immune sensor Z-DNA binding protein 1 (ZBP1) as a regulator of the crisis program. A crisis-associated isoform of ZBP1 is induced by the cGAS-STING DNA-sensing pathway, but reaches full activation only when associated with telomeric-repeat-containing RNA (TERRA) transcripts that are synthesized from dysfunctional telomeres. TERRA-bound ZBP1 oligomerizes into filaments on the outer mitochondrial membrane of a subset of mitochondria, where it activates the innate immune adapter protein mitochondrial antiviral-signalling protein (MAVS). We propose that these oligomerization properties of ZBP1 serve as a signal amplification mechanism, where few TERRA-ZBP1 interactions are sufficient to launch a detrimental MAVS-dependent interferon response. Our study reveals a mechanism for telomere-mediated tumour suppression, whereby dysfunctional telomeres activate innate immune responses through mitochondrial TERRA-ZBP1 complexes to eliminate cells destined for neoplastic transformation.
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Affiliation(s)
- Joe Nassour
- The Salk Institute for Biological Studies, La Jolla, CA, USA
| | | | - Adriana Correia
- The Salk Institute for Biological Studies, La Jolla, CA, USA
- Departamento de Biologia Vegetal, Faculdade de Ciências da Universidade de Lisboa (FCUL), Lisbon, Portugal
| | | | - Laura Mainz
- The Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Sara Przetocka
- The Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Candy Haggblom
- The Salk Institute for Biological Studies, La Jolla, CA, USA
| | | | - April Williams
- The Salk Institute for Biological Studies, La Jolla, CA, USA
| | | | - Semih C Akincilar
- A*STAR Division of Cancer Genetics, Institute of Molecular and Cell Biology (IMCB), Singapore, Singapore
- Therapeutics Laboratory of NFκB Signaling, Institute of Molecular and Cell Biology (IMCB), Singapore, Singapore
| | - Vinay Tergaonkar
- A*STAR Division of Cancer Genetics, Institute of Molecular and Cell Biology (IMCB), Singapore, Singapore
- Therapeutics Laboratory of NFκB Signaling, Institute of Molecular and Cell Biology (IMCB), Singapore, Singapore
- Department of Pathology, Yong Loo Lin School of Medicine, National University of Singapore (NUS), Singapore, Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore (NUS), Singapore, Singapore
| | - Gerald S Shadel
- The Salk Institute for Biological Studies, La Jolla, CA, USA.
| | - Jan Karlseder
- The Salk Institute for Biological Studies, La Jolla, CA, USA.
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19
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Hu SB, Heraud-Farlow J, Sun T, Liang Z, Goradia A, Taylor S, Walkley CR, Li JB. ADAR1p150 Prevents MDA5 and PKR Activation via Distinct Mechanisms to Avert Fatal Autoinflammation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.25.525475. [PMID: 36747811 PMCID: PMC9900771 DOI: 10.1101/2023.01.25.525475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Effective immunity requires the innate immune system to distinguish foreign (non-self) nucleic acids from cellular (self) nucleic acids. Cellular double-stranded RNAs (dsRNAs) are edited by the RNA editing enzyme ADAR1 to prevent their dsRNA structure pattern being recognized as viral dsRNA by cytoplasmic dsRNA sensors including MDA5, PKR and ZBP1. A loss of ADAR1-mediated RNA editing of cellular dsRNA activates MDA5. However, additional RNA editing-independent functions of ADAR1 have been proposed, but a specific mechanism has not been delineated. We now demonstrate that the loss of ADAR1-mediated RNA editing specifically activates MDA5, while loss of the cytoplasmic ADAR1p150 isoform or its dsRNA binding activity enabled PKR activation. Deleting both MDA5 and PKR resulted in complete rescue of the embryonic lethality of Adar1p150 -/- mice to adulthood, contrasting with the limited or no rescue by removing MDA5, PKR or ZBP1 alone, demonstrating that this is a species conserved function of ADAR1p150. Our findings demonstrate that MDA5 and PKR are the primary in vivo effectors of fatal autoinflammation following the loss of ADAR1p150.
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20
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Li H, Guo Y, Qi W, Liao M. N 6-methyladenosine modification of viral RNA and its role during the recognition process of RIG-I-like receptors. Front Immunol 2022; 13:1031200. [PMID: 36582239 PMCID: PMC9792670 DOI: 10.3389/fimmu.2022.1031200] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 11/17/2022] [Indexed: 12/15/2022] Open
Abstract
N6-methyladenosine (m6A) is the most abundant RNA chemical modification in eukaryotes and is also found in the RNAs of many viruses. In recent years, m6A RNA modification has been reported to have a role not only in the replication of numerous viruses but also in the innate immune escape process. In this review, we describe the viruses that contain m6A in their genomes or messenger RNAs (mRNAs), and summarize the effects of m6A on the replication of different viruses. We also discuss how m6A modification helps viral RNAs escape recognition by exogenous RNA sensors, such as retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs), during viral invasion. Overall, the goal of our review is to summarize how m6A regulates viral replication and facilitates innate immune escape. Furthermore, we elaborate on the potential of m6A as a novel antiviral target.
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Affiliation(s)
- Huanan Li
- National Avian Influenza Para-Reference Laboratory (Guangzhou), South China Agricultural University, Guangzhou, China,Key Laboratory of Zoonosis, Ministry of Agriculture and Rural Affairs, Guangzhou, China,National and Regional Joint Engineering Laboratory for Medicament of Zoonoses Prevention and Control, Guangzhou, China,Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou, China
| | - Yang Guo
- National Avian Influenza Para-Reference Laboratory (Guangzhou), South China Agricultural University, Guangzhou, China,Key Laboratory of Zoonosis, Ministry of Agriculture and Rural Affairs, Guangzhou, China,National and Regional Joint Engineering Laboratory for Medicament of Zoonoses Prevention and Control, Guangzhou, China,Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou, China
| | - Wenbao Qi
- National Avian Influenza Para-Reference Laboratory (Guangzhou), South China Agricultural University, Guangzhou, China,Key Laboratory of Zoonosis, Ministry of Agriculture and Rural Affairs, Guangzhou, China,National and Regional Joint Engineering Laboratory for Medicament of Zoonoses Prevention and Control, Guangzhou, China,Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou, China,Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China,*Correspondence: Wenbao Qi, ; Ming Liao,
| | - Ming Liao
- National Avian Influenza Para-Reference Laboratory (Guangzhou), South China Agricultural University, Guangzhou, China,Key Laboratory of Zoonosis, Ministry of Agriculture and Rural Affairs, Guangzhou, China,National and Regional Joint Engineering Laboratory for Medicament of Zoonoses Prevention and Control, Guangzhou, China,Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou, China,Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China,Guangdong Academy of Agricultural Sciences, Guangzhou, China,*Correspondence: Wenbao Qi, ; Ming Liao,
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21
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Diallo MA, Pirotte S, Hu Y, Morvan L, Rakus K, Suárez NM, PoTsang L, Saneyoshi H, Xu Y, Davison A, Tompa P, Sussman J, Vanderplasschen A. A fish herpesvirus highlights functional diversities among Zα domains related to phase separation induction and A-to-Z conversion. Nucleic Acids Res 2022; 51:806-830. [PMID: 36130731 PMCID: PMC9881149 DOI: 10.1093/nar/gkac761] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 08/18/2022] [Accepted: 08/25/2022] [Indexed: 02/06/2023] Open
Abstract
Zalpha (Zα) domains bind to left-handed Z-DNA and Z-RNA. The Zα domain protein family includes cellular (ADAR1, ZBP1 and PKZ) and viral (vaccinia virus E3 and cyprinid herpesvirus 3 (CyHV-3) ORF112) proteins. We studied CyHV-3 ORF112, which contains an intrinsically disordered region and a Zα domain. Genome editing of CyHV-3 indicated that the expression of only the Zα domain of ORF112 was sufficient for normal viral replication in cell culture and virulence in carp. In contrast, its deletion was lethal for the virus. These observations revealed the potential of the CyHV-3 model as a unique platform to compare the exchangeability of Zα domains expressed alone in living cells. Attempts to rescue the ORF112 deletion by a broad spectrum of cellular, viral, and artificial Zα domains showed that only those expressing Z-binding activity, the capacity to induce liquid-liquid phase separation (LLPS), and A-to-Z conversion, could rescue viral replication. For the first time, this study reports the ability of some Zα domains to induce LLPS and supports the biological relevance of dsRNA A-to-Z conversion mediated by Zα domains. This study expands the functional diversity of Zα domains and stimulates new hypotheses concerning the mechanisms of action of proteins containing Zα domains.
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Affiliation(s)
| | | | - Yunlong Hu
- Department of Infectious and Parasitic Diseases, Immunology-Vaccinology, University of Liège, Liège B-4000, Belgium
| | - Léa Morvan
- Department of Infectious and Parasitic Diseases, Immunology-Vaccinology, University of Liège, Liège B-4000, Belgium
| | - Krzysztof Rakus
- Department of Infectious and Parasitic Diseases, Immunology-Vaccinology, University of Liège, Liège B-4000, Belgium,Department of Evolutionary Immunology, Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian University, Krakow 30387, Poland
| | - Nicolás M Suárez
- MRC-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, UK
| | - Lee PoTsang
- Department of Infectious and Parasitic Diseases, Immunology-Vaccinology, University of Liège, Liège B-4000, Belgium,Department of Aquaculture, National Taiwan Ocean University, Keelung 202, Taiwan
| | - Hisao Saneyoshi
- Department of Medical Sciences, Division of Chemistry, University of Miyazaki, Miyazaki 889-1692, Japan
| | - Yan Xu
- Department of Medical Sciences, Division of Chemistry, University of Miyazaki, Miyazaki 889-1692, Japan
| | - Andrew J Davison
- MRC-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, UK
| | - Peter Tompa
- VIB-VUB Center for Structural Biology, Vrije Universiteit Brussel, Brussel B-1050, Belgium
| | - Joel L Sussman
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
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22
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Chen YG, Hur S. Cellular origins of dsRNA, their recognition and consequences. Nat Rev Mol Cell Biol 2022; 23:286-301. [PMID: 34815573 PMCID: PMC8969093 DOI: 10.1038/s41580-021-00430-1] [Citation(s) in RCA: 143] [Impact Index Per Article: 71.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/12/2021] [Indexed: 01/02/2023]
Abstract
Double-stranded RNA (dsRNA) is associated with most viral infections - it either constitutes the viral genome (in the case of dsRNA viruses) or is generated in host cells during viral replication. Hence, nearly all organisms have the capability of recognizing dsRNA and mounting a response, the primary aim of which is to mitigate the potential infection. In vertebrates, a set of innate immune receptors for dsRNA induce a multitude of cell-intrinsic and cell-extrinsic immune responses upon dsRNA recognition. Notably, recent studies showed that vertebrate cells can accumulate self-derived dsRNAs or dsRNA-like species upon dysregulation of several cellular processes, activating the very same immune pathways as in infected cells. On the one hand, such aberrant immune activation in the absence of infection can lead to pathogenesis of immune disorders, such as Aicardi-Goutières syndrome. On the other hand, the same innate immune reaction can be induced in a controlled setting for a therapeutic benefit, as occurs in immunotherapies. In this Review, we describe mechanisms by which immunostimulatory dsRNAs are generated in mammalian cells, either by viruses or by the host cells, and how cells respond to them, with the focus on recent developments regarding the role of cellular dsRNAs in immune modulation.
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Affiliation(s)
- Y Grace Chen
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT, USA.
| | - Sun Hur
- Harvard Medical School & Boston Children's Hospital, Boston, MA, USA.
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23
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Price AM, Steinbock RT, Di C, Hayer K, Li Y, Herrmann C, Parenti N, Whelan J, Weiss S, Weitzman M. Adenovirus prevents dsRNA formation by promoting efficient splicing of viral RNA. Nucleic Acids Res 2022; 50:1201-1220. [PMID: 34671803 PMCID: PMC8860579 DOI: 10.1093/nar/gkab896] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 09/10/2021] [Accepted: 10/08/2021] [Indexed: 12/14/2022] Open
Abstract
Eukaryotic cells recognize intracellular pathogens through pattern recognition receptors, including sensors of aberrant nucleic acid structures. Sensors of double-stranded RNA (dsRNA) are known to detect replication intermediates of RNA viruses. It has long been suggested that annealing of mRNA from symmetrical transcription of both top and bottom strands of DNA virus genomes can produce dsRNA during infection. Supporting this hypothesis, nearly all DNA viruses encode inhibitors of dsRNA-recognition pathways. However, direct evidence that DNA viruses produce dsRNA is lacking. Contrary to dogma, we show that the nuclear-replicating DNA virus adenovirus (AdV) does not produce detectable levels of dsRNA during infection. In contrast, abundant dsRNA is detected within the nucleus of cells infected with AdV mutants defective for viral RNA processing. In the presence of nuclear dsRNA, the cytoplasmic dsRNA sensor PKR is relocalized and activated within the nucleus. Accumulation of viral dsRNA occurs in the late phase of infection, when unspliced viral transcripts form intron/exon base pairs between top and bottom strand transcripts. We propose that DNA viruses actively limit dsRNA formation by promoting efficient splicing and mRNA processing, thus avoiding detection and restriction by host innate immune sensors of pathogenic nucleic acids.
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Affiliation(s)
- Alexander M Price
- Division of Protective Immunity, Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Robert T Steinbock
- Division of Protective Immunity, Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
- Cell & Molecular Biology Graduate Group, University of Pennsylvania, Philadelphia, PA, USA
| | - Chao Di
- Department of Biomedical and Health Informatics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Katharina E Hayer
- Department of Biomedical and Health Informatics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Yize Li
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Christin Herrmann
- Division of Protective Immunity, Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
- Cell & Molecular Biology Graduate Group, University of Pennsylvania, Philadelphia, PA, USA
| | - Nicholas A Parenti
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jillian N Whelan
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Susan R Weiss
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Matthew D Weitzman
- Division of Protective Immunity, Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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24
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Jia J, Fu J, Tang H. Activation and Evasion of RLR Signaling by DNA Virus Infection. Front Microbiol 2022; 12:804511. [PMID: 34987495 PMCID: PMC8721196 DOI: 10.3389/fmicb.2021.804511] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 12/02/2021] [Indexed: 12/24/2022] Open
Abstract
Antiviral innate immune response triggered by nucleic acid recognition plays an extremely important role in controlling viral infections. The initiation of antiviral immune response against RNA viruses through ligand recognition of retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs) was extensively studied. RLR’s role in DNA virus infection, which is less known, is increasing attention. Here, we review the research progress of the ligand recognition of RLRs during the DNA virus infection process and the viral evasion mechanism from host immune responses.
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Affiliation(s)
- Junli Jia
- Department of Immunology, Nanjing Medical University, Nanjing, China
| | - Jiangan Fu
- Genor Biopharma Co., Ltd., Shanghai, China
| | - Huamin Tang
- Department of Immunology, Nanjing Medical University, Nanjing, China.,Laboratory Center for Basic Medical Sciences, Nanjing Medical University, Nanjing, China.,Key Laboratory of Antibody Technique of Ministry of Health, Nanjing Medical University, Nanjing, China
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25
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Abstract
Birds are important hosts for many RNA viruses, including influenza A virus, Newcastle disease virus, West Nile virus and coronaviruses. Innate defense against RNA viruses in birds involves detection of viral RNA by pattern recognition receptors. Several receptors of different classes are involved, such as endosomal toll-like receptors and cytoplasmic retinoic acid-inducible gene I-like receptors, and their downstream adaptor proteins. The function of these receptors and their antagonism by viruses is well established in mammals; however, this has received less attention in birds. These receptors have been characterized in a few bird species, and the completion of avian genomes will permit study of their evolution. For each receptor, functional work has established ligand specificity and activation by viral infection. Engagement of adaptors, regulation by modulators and the supramolecular organization of proteins required for activation are incompletely understood in both mammals and birds. These receptors bind conserved nucleic acid agonists such as single- or double-stranded RNA and generally show purifying selection, particularly the ligand binding regions. However, in birds, these receptors and adaptors differ between species, and between individuals, suggesting that they are under selection for diversification over time. Avian receptors and signalling pathways, like their mammalian counterparts, are targets for antagonism by a variety of viruses, intent on escape from innate immune responses.
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26
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Yu Q, Herrero Del Valle A, Singh R, Modis Y. MDA5 disease variant M854K prevents ATP-dependent structural discrimination of viral and cellular RNA. Nat Commun 2021; 12:6668. [PMID: 34795277 PMCID: PMC8602431 DOI: 10.1038/s41467-021-27062-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 10/28/2021] [Indexed: 11/09/2022] Open
Abstract
Our innate immune responses to viral RNA are vital defenses. Long cytosolic double-stranded RNA (dsRNA) is recognized by MDA5. The ATPase activity of MDA5 contributes to its dsRNA binding selectivity. Mutations that reduce RNA selectivity can cause autoinflammatory disease. Here, we show how the disease-associated MDA5 variant M854K perturbs MDA5-dsRNA recognition. M854K MDA5 constitutively activates interferon signaling in the absence of exogenous RNA. M854K MDA5 lacks ATPase activity and binds more stably to synthetic Alu:Alu dsRNA. CryoEM structures of MDA5-dsRNA filaments at different stages of ATP hydrolysis show that the K854 sidechain forms polar bonds that constrain the conformation of MDA5 subdomains, disrupting key steps in the ATPase cycle- RNA footprint expansion and helical twist modulation. The M854K mutation inhibits ATP-dependent RNA proofreading via an allosteric mechanism, allowing MDA5 to form signaling complexes on endogenous RNAs. This work provides insights on how MDA5 recognizes dsRNA in health and disease.
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MESH Headings
- Adenosine Triphosphatases/genetics
- Adenosine Triphosphatases/metabolism
- Adenosine Triphosphatases/ultrastructure
- Adenosine Triphosphate/metabolism
- Cryoelectron Microscopy
- HEK293 Cells
- Humans
- Immunity, Innate/genetics
- Inflammation/genetics
- Inflammation/metabolism
- Interferon-Induced Helicase, IFIH1/chemistry
- Interferon-Induced Helicase, IFIH1/genetics
- Interferon-Induced Helicase, IFIH1/metabolism
- Models, Molecular
- Mutation, Missense
- Nucleic Acid Conformation
- Protein Binding
- Protein Conformation
- RNA, Double-Stranded/chemistry
- RNA, Double-Stranded/genetics
- RNA, Double-Stranded/metabolism
- RNA, Viral/genetics
- RNA, Viral/metabolism
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Affiliation(s)
- Qin Yu
- Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, UK
- Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), University of Cambridge School of Clinical Medicine, Cambridge, CB2 0AW, UK
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Alba Herrero Del Valle
- Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, UK
- Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), University of Cambridge School of Clinical Medicine, Cambridge, CB2 0AW, UK
| | - Rahul Singh
- Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, UK
- Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), University of Cambridge School of Clinical Medicine, Cambridge, CB2 0AW, UK
| | - Yorgo Modis
- Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, UK.
- Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), University of Cambridge School of Clinical Medicine, Cambridge, CB2 0AW, UK.
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27
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Abstract
In vitro-transcribed RNAs are emerging as new biologics for therapeutic innovation, as exemplified by their application recently in SARS-CoV-2 vaccinations. RNAs prepared by in vitro transcription (IVT) allow transient expression of proteins of interest, conferring safety over DNA- or virus-mediated gene delivery systems. However, in vitro-transcribed RNAs should be used with caution because of their immunogenicity, which is in part triggered by double-stranded RNA (dsRNA) byproducts during IVT. Cellular innate immune response to dsRNA byproducts can lead to undesirable consequences, including suppression of protein synthesis and cell death, which in turn can detrimentally impact the efficacy of mRNA therapy. Thus, it is critical to understand the nature of IVT byproducts and the mechanisms by which they trigger innate immune responses.Our lab has been investigating the mechanisms by which the innate immune system discriminates between "self" and "nonself" RNA, with the focus on the cytoplasmic dsRNA receptors retinoic acid-inducible gene I (RIG-I) and melanoma differentiation-associated 5 (MDA5). We have biochemically and structurally characterized critical events involving RNA discrimination and signal transduction by RIG-I or MDA5. We have used in vitro-transcribed RNAs as tools to investigate RNA specificity of RIG-I and MDA5, which required optimization of the IVT reaction and purification processes to eliminate the effect of IVT byproducts. In this Account, we summarize our current understanding of RIG-I and MDA5 and IVT reactions and propose future directions for improving IVT as a method to generate both research tools and therapeutics. Other critical proteins in cellular innate immune response to dsRNAs are also discussed. We arrange the contents in the following order: (i) innate immunity sensors for nonself RNA, including the RIG-I-like receptors (RLRs) in the cytosol and the toll-like receptors (TLRs) in the endosome, as well as cytoplasmic dsRNA-responding proteins, including protein kinase R (PKR) and 2',5'-oligoadenylate synthetases (OASes), illustrating the feature of protein-RNA binding and its consequences; (ii) the immunogenicity of IVT byproducts, specifically the generation of dsRNA molecules during IVT; and (iii) methods to reduce IVT RNA immunogenicity, including optimizations of RNA polymerases, reagents, and experimental conditions during IVT and subsequent purification.
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Affiliation(s)
- Xin Mu
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
- Tianjin University and Health-Biotech United Group Joint Laboratory of Innovative Drug Development and Translational Medicine, Tianjin University, Tianjin 300072, China
| | - Sun Hur
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, United States
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts 02115, United States
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28
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Li K, Zheng J, Wirawan M, Trinh NM, Fedorova O, Griffin PR, Pyle AM, Luo D. Insights into the structure and RNA-binding specificity of Caenorhabditis elegans Dicer-related helicase 3 (DRH-3). Nucleic Acids Res 2021; 49:9978-9991. [PMID: 34403472 PMCID: PMC8464030 DOI: 10.1093/nar/gkab712] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 07/31/2021] [Accepted: 08/03/2021] [Indexed: 12/17/2022] Open
Abstract
DRH-3 is critically involved in germline development and RNA interference (RNAi) facilitated chromosome segregation via the 22G-siRNA pathway in Caenorhabditis elegans. DRH-3 has similar domain architecture to RIG-I-like receptors (RLRs) and belongs to the RIG-I-like RNA helicase family. The molecular understanding of DRH-3 and its function in endogenous RNAi pathways remains elusive. In this study, we solved the crystal structures of the DRH-3 N-terminal domain (NTD) and the C-terminal domains (CTDs) in complex with 5'-triphosphorylated RNAs. The NTD of DRH-3 adopts a distinct fold of tandem caspase activation and recruitment domains (CARDs) structurally similar to the CARDs of RIG-I and MDA5, suggesting a signaling function in the endogenous RNAi biogenesis. The CTD preferentially recognizes 5'-triphosphorylated double-stranded RNAs bearing the typical features of secondary siRNA transcripts. The full-length DRH-3 displays unique structural dynamics upon binding to RNA duplexes that differ from RIG-I or MDA5. These features of DRH-3 showcase the evolutionary divergence of the Dicer and RLR family of helicases.
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Affiliation(s)
- Kuohan Li
- Lee Kong Chian School of Medicine, Nanyang Technological University, EMB 03-07, 59 Nanyang Drive 636921, Singapore.,School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive 637551, Singapore.,NTU Institute of Structural Biology, Nanyang Technological University, EMB 06-01, 59 Nanyang Drive 636921, Singapore
| | - Jie Zheng
- The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Melissa Wirawan
- Lee Kong Chian School of Medicine, Nanyang Technological University, EMB 03-07, 59 Nanyang Drive 636921, Singapore.,NTU Institute of Structural Biology, Nanyang Technological University, EMB 06-01, 59 Nanyang Drive 636921, Singapore
| | - Nguyen Mai Trinh
- Lee Kong Chian School of Medicine, Nanyang Technological University, EMB 03-07, 59 Nanyang Drive 636921, Singapore.,NTU Institute of Structural Biology, Nanyang Technological University, EMB 06-01, 59 Nanyang Drive 636921, Singapore
| | - Olga Fedorova
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA.,Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | | | - Anna M Pyle
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA.,Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Dahai Luo
- Lee Kong Chian School of Medicine, Nanyang Technological University, EMB 03-07, 59 Nanyang Drive 636921, Singapore.,School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive 637551, Singapore.,NTU Institute of Structural Biology, Nanyang Technological University, EMB 06-01, 59 Nanyang Drive 636921, Singapore
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29
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Thoresen D, Wang W, Galls D, Guo R, Xu L, Pyle AM. The molecular mechanism of RIG-I activation and signaling. Immunol Rev 2021; 304:154-168. [PMID: 34514601 PMCID: PMC9293153 DOI: 10.1111/imr.13022] [Citation(s) in RCA: 104] [Impact Index Per Article: 34.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Revised: 08/10/2021] [Accepted: 08/17/2021] [Indexed: 12/25/2022]
Abstract
RIG‐I is our first line of defense against RNA viruses, serving as a pattern recognition receptor that identifies molecular features common among dsRNA and ssRNA viral pathogens. RIG‐I is maintained in an inactive conformation as it samples the cellular space for pathogenic RNAs. Upon encounter with the triphosphorylated terminus of blunt‐ended viral RNA duplexes, the receptor changes conformation and releases a pair of signaling domains (CARDs) that are selectively modified and interact with an adapter protein (MAVS), thereby triggering a signaling cascade that stimulates transcription of interferons. Here, we describe the structural determinants for specific RIG‐I activation by viral RNA, and we describe the strategies by which RIG‐I remains inactivated in the presence of host RNAs. From the initial RNA triggering event to the final stages of interferon expression, we describe the experimental evidence underpinning our working knowledge of RIG‐I signaling. We draw parallels with behavior of related proteins MDA5 and LGP2, describing evolutionary implications of their collective surveillance of the cell. We conclude by describing the cell biology and immunological investigations that will be needed to accurately describe the role of RIG‐I in innate immunity and to provide the necessary foundation for pharmacological manipulation of this important receptor.
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Affiliation(s)
- Daniel Thoresen
- Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Wenshuai Wang
- Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Drew Galls
- Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Rong Guo
- Chemistry, Yale University, New Haven, CT, USA
| | - Ling Xu
- Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Anna Marie Pyle
- Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA.,Chemistry, Yale University, New Haven, CT, USA.,Howard Hughes Medical Institute, Yale University, New Haven, CT, USA
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30
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Yang Z, Wang J, He B, Zhang X, Li X, Kuang E. RTN3 inhibits RIG-I-mediated antiviral responses by impairing TRIM25-mediated K63-linked polyubiquitination. eLife 2021; 10:e68958. [PMID: 34313226 PMCID: PMC8315805 DOI: 10.7554/elife.68958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 07/12/2021] [Indexed: 11/26/2022] Open
Abstract
Upon viral RNA recognition, the RIG-I signalosome continuously generates IFNs and cytokines, leading to neutrophil recruitment and inflammation. Thus, attenuation of excessive immune and inflammatory responses is crucial to restore immune homeostasis and prevent unwarranted damage, yet few resolving mediators have been identified. In the present study, we demonstrated that RTN3 is strongly upregulated during RNA viral infection and acts as an inflammation-resolving regulator. Increased RTN3 aggregates on the endoplasmic reticulum and interacts with both TRIM25 and RIG-I, subsequently impairing K63-linked polyubiquitination and resulting in both IRF3 and NF-κB inhibition. Rtn3 overexpression in mice causes an obvious inflammation resolving phenomenon when challenged with VSV, Rtn3-overexpressing mice display significantly decreased neutrophil numbers and inflammatory cell infiltration, which is accompanied by reduced tissue edema in the liver and thinner alveolar interstitium. Taken together, our findings identify RTN3 as a conserved negative regulator of immune and inflammatory responses and provide insights into the negative feedback that maintains immune and inflammatory homeostasis.
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Affiliation(s)
- Ziwei Yang
- Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-Sen UniversityGuangzhouChina
- Key Laboratory of Tropical Disease Control (Sun Yat-Sen University), Ministry of EducationGuangzhouChina
| | - Jun Wang
- Zhongshan School of Medicine, Sun Yat-Sen UniversityGuangzhouChina
| | - Bailin He
- Zhongshan School of Medicine, Sun Yat-Sen UniversityGuangzhouChina
| | - Xiaolin Zhang
- Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-Sen UniversityGuangzhouChina
| | - Xiaojuan Li
- Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-Sen UniversityGuangzhouChina
- Key Laboratory of Tropical Disease Control (Sun Yat-Sen University), Ministry of EducationGuangzhouChina
| | - Ersheng Kuang
- Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-Sen UniversityGuangzhouChina
- Key Laboratory of Tropical Disease Control (Sun Yat-Sen University), Ministry of EducationGuangzhouChina
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31
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Herzner AM, Khan Z, Van Nostrand EL, Chan S, Cuellar T, Chen R, Pechuan-Jorge X, Komuves L, Solon M, Modrusan Z, Haley B, Yeo GW, Behrens TW, Albert ML. ADAR and hnRNPC deficiency synergize in activating endogenous dsRNA-induced type I IFN responses. J Exp Med 2021; 218:212507. [PMID: 34297039 PMCID: PMC8313407 DOI: 10.1084/jem.20201833] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 09/11/2020] [Accepted: 06/24/2021] [Indexed: 01/26/2023] Open
Abstract
Cytosolic double-stranded RNA (dsRNA) initiates type I IFN responses. Endogenous retroelements, notably Alu elements, constitute a source of dsRNA. Adenosine-to-inosine (A-to-I) editing by ADAR induces mismatches in dsRNA and prevents recognition by MDA5 and autoinflammation. To identify additional endogenous dsRNA checkpoints, we conducted a candidate screen in THP-1 monocytes and found that hnRNPC and ADAR deficiency resulted in synergistic induction of MDA5-dependent IFN responses. RNA-seq analysis demonstrated dysregulation of Alu-containing introns in hnRNPC-deficient cells via utilization of unmasked cryptic splice sites, including introns containing ADAR-dependent A-to-I editing clusters. These putative MDA5 ligands showed reduced editing in the absence of ADAR, providing a plausible mechanism for the combined effects of hnRNPC and ADAR. This study contributes to our understanding of the control of repetitive element-induced autoinflammation and suggests that patients with hnRNPC-mutated tumors might maximally benefit from ADAR inhibition-based immunotherapy.
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Affiliation(s)
| | - Zia Khan
- Department of Human Genetics, Genentech, South San Francisco, CA
| | - Eric L Van Nostrand
- Department of Cellular and Molecular Medicine, Stem Cell Program and the Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA
| | - Sara Chan
- Department of Pathology, Genentech, South San Francisco, CA
| | - Trinna Cuellar
- Department of Molecular Biology, Genentech, South San Francisco, CA
| | - Ronald Chen
- Department of Human Genetics, Genentech, South San Francisco, CA
| | | | - Laszlo Komuves
- Department of Pathology, Genentech, South San Francisco, CA
| | - Margaret Solon
- Department of Pathology, Genentech, South San Francisco, CA
| | - Zora Modrusan
- Department of Microchemistry, Proteomics & Lipidomics and Next Generation Sequencing, Genentech, South San Francisco, CA
| | - Benjamin Haley
- Department of Molecular Biology, Genentech, South San Francisco, CA
| | - Gene W Yeo
- Department of Cellular and Molecular Medicine, Stem Cell Program and the Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA
| | | | - Matthew L Albert
- Department of Cancer Immunology, Genentech, South San Francisco, CA
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32
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Lewandowska M, Sharoni T, Admoni Y, Aharoni R, Moran Y. Functional characterization of the cnidarian antiviral immune response reveals ancestral complexity. Mol Biol Evol 2021; 38:4546-4561. [PMID: 34180999 PMCID: PMC8476169 DOI: 10.1093/molbev/msab197] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Animals evolved a broad repertoire of innate immune sensors and downstream effector cascades for defense against RNA viruses. Yet, this system varies greatly among different bilaterian animals, masking its ancestral state. In this study, we aimed to characterize the antiviral immune response of the cnidarian Nematostella vectensis and decipher the function of the retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs) known to detect viral double-stranded RNA (dsRNA) in bilaterians but activate different antiviral pathways in vertebrates and nematodes. We show that polyinosinic:polycytidylic acid (poly(I:C)), a mimic of long viral dsRNA and a primary ligand for the vertebrate RLR melanoma differentiation-associated protein 5 (MDA5), triggers a complex antiviral immune response bearing features distinctive for both vertebrate and invertebrate systems. Importantly, a well-characterized agonist of the vertebrate RIG-I receptor does not induce a significant transcriptomic response that bears signature of the antiviral immune response, which experimentally supports the results of a phylogenetic analysis indicating clustering of the two N. vectensis RLR paralogs (NveRLRa and NveRLRb) with MDA5. Furthermore, the results of affinity assays reveal that NveRLRb binds poly(I:C) and long dsRNA and its knockdown impairs the expression of putative downstream effector genes including RNA interference components. Our study provides for the first time the functional evidence for the conserved role of RLRs in initiating immune response to dsRNA that originated before the cnidarian–bilaterian split and lay a strong foundation for future research on the evolution of the immune responses to RNA viruses.
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Affiliation(s)
- Magda Lewandowska
- Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, Faculty of Science, Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Ton Sharoni
- Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, Faculty of Science, Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Yael Admoni
- Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, Faculty of Science, Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Reuven Aharoni
- Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, Faculty of Science, Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Yehu Moran
- Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, Faculty of Science, Hebrew University of Jerusalem, Jerusalem 9190401, Israel
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33
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Markiewicz L, Drazkowska K, Sikorski PJ. Tricks and threats of RNA viruses - towards understanding the fate of viral RNA. RNA Biol 2021; 18:669-687. [PMID: 33618611 PMCID: PMC8078519 DOI: 10.1080/15476286.2021.1875680] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 12/22/2020] [Accepted: 01/09/2021] [Indexed: 12/24/2022] Open
Abstract
Human innate cellular defence pathways have evolved to sense and eliminate pathogens, of which, viruses are considered one of the most dangerous. Their relatively simple structure makes the identification of viral invasion a difficult task for cells. In the course of evolution, viral nucleic acids have become one of the strongest and most reliable early identifiers of infection. When considering RNA virus recognition, RNA sensing is the central mechanism in human innate immunity, and effectiveness of this sensing is crucial for triggering an appropriate antiviral response. Although human cells are armed with a variety of highly specialized receptors designed to respond only to pathogenic viral RNA, RNA viruses have developed an array of mechanisms to avoid being recognized by human interferon-mediated cellular defence systems. The repertoire of viral evasion strategies is extremely wide, ranging from masking pathogenic RNA through end modification, to utilizing sophisticated techniques to deceive host cellular RNA degrading enzymes, and hijacking the most basic metabolic pathways in host cells. In this review, we aim to dissect human RNA sensing mechanisms crucial for antiviral immune defences, as well as the strategies adopted by RNA viruses to avoid detection and degradation by host cells. We believe that understanding the fate of viral RNA upon infection, and detailing the molecular mechanisms behind virus-host interactions, may be helpful for developing more effective antiviral strategies; which are urgently needed to prevent the far-reaching consequences of widespread, highly pathogenic viral infections.
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34
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McFadden MJ, Horner SM. N 6-Methyladenosine Regulates Host Responses to Viral Infection. Trends Biochem Sci 2021; 46:366-377. [PMID: 33309325 PMCID: PMC8052259 DOI: 10.1016/j.tibs.2020.11.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 11/09/2020] [Accepted: 11/13/2020] [Indexed: 12/11/2022]
Abstract
Recent discoveries have revealed that, during viral infection, the presence of the RNA modification N6-methyladenosine (m6A) on viral and cellular RNAs has profound impacts on infection outcome. Although m6A directly regulates many viral RNA processes, its effects on cellular RNAs and pathways during infection have only recently begun to be elucidated. Disentangling the effects of m6A on viral and host RNAs remains a challenge for the field. m6A has been found to regulate host responses such as viral RNA sensing, cytokine responses, and immune cell functions. We highlight recent findings describing how m6A modulates host responses to viral infection and discuss future directions that will lead to a synergistic understanding of the processes by which m6A regulates viral infection.
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Affiliation(s)
- Michael J McFadden
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Stacy M Horner
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA; Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA.
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35
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Wang HT, Hur S. Substrate recognition by TRIM and TRIM-like proteins in innate immunity. Semin Cell Dev Biol 2021; 111:76-85. [PMID: 33092958 PMCID: PMC7572318 DOI: 10.1016/j.semcdb.2020.09.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 09/28/2020] [Indexed: 12/23/2022]
Abstract
TRIM (Tripartite motif) and TRIM-like proteins have emerged as an important class of E3 ligases in innate immunity. Their functions range from activation or regulation of innate immune signaling pathway to direct detection and restriction of pathogens. Despite the importance, molecular mechanisms for many TRIM/TRIM-like proteins remain poorly characterized, in part due to challenges of identifying their substrates. In this review, we discuss several TRIM/TRIM-like proteins in RNA sensing pathways and viral restriction functions. We focus on those containing PRY-SPRY, the domain most frequently used for substrate recognition, and discuss emerging mechanisms that are commonly utilized by several TRIM/TRIM-like proteins to tightly control their interaction with the substrates.
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Affiliation(s)
- Hai-Tao Wang
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Sun Hur
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA.
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36
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Onomoto K, Onoguchi K, Yoneyama M. Regulation of RIG-I-like receptor-mediated signaling: interaction between host and viral factors. Cell Mol Immunol 2021; 18:539-555. [PMID: 33462384 PMCID: PMC7812568 DOI: 10.1038/s41423-020-00602-7] [Citation(s) in RCA: 188] [Impact Index Per Article: 62.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 11/17/2020] [Indexed: 01/31/2023] Open
Abstract
Retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs) are RNA sensor molecules that play essential roles in innate antiviral immunity. Among the three RLRs encoded by the human genome, RIG-I and melanoma differentiation-associated gene 5, which contain N-terminal caspase recruitment domains, are activated upon the detection of viral RNAs in the cytoplasm of virus-infected cells. Activated RLRs induce downstream signaling via their interactions with mitochondrial antiviral signaling proteins and activate the production of type I and III interferons and inflammatory cytokines. Recent studies have shown that RLR-mediated signaling is regulated by interactions with endogenous RNAs and host proteins, such as those involved in stress responses and posttranslational modifications. Since RLR-mediated cytokine production is also involved in the regulation of acquired immunity, the deregulation of RLR-mediated signaling is associated with autoimmune and autoinflammatory disorders. Moreover, RLR-mediated signaling might be involved in the aberrant cytokine production observed in coronavirus disease 2019. Since the discovery of RLRs in 2004, significant progress has been made in understanding the mechanisms underlying the activation and regulation of RLR-mediated signaling pathways. Here, we review the recent advances in the understanding of regulated RNA recognition and signal activation by RLRs, focusing on the interactions between various host and viral factors.
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Affiliation(s)
- Koji Onomoto
- Division of Molecular Immunology, Medical Mycology Research Center, Chiba University, 1-8-1, Inohana, Chuo-ku, Chiba, 260-8673, Japan
| | - Kazuhide Onoguchi
- Division of Molecular Immunology, Medical Mycology Research Center, Chiba University, 1-8-1, Inohana, Chuo-ku, Chiba, 260-8673, Japan
| | - Mitsutoshi Yoneyama
- Division of Molecular Immunology, Medical Mycology Research Center, Chiba University, 1-8-1, Inohana, Chuo-ku, Chiba, 260-8673, Japan.
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Sadeq S, Al-Hashimi S, Cusack CM, Werner A. Endogenous Double-Stranded RNA. Noncoding RNA 2021; 7:15. [PMID: 33669629 PMCID: PMC7930956 DOI: 10.3390/ncrna7010015] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 02/15/2021] [Accepted: 02/17/2021] [Indexed: 02/07/2023] Open
Abstract
The birth of long non-coding RNAs (lncRNAs) is closely associated with the presence and activation of repetitive elements in the genome. The transcription of endogenous retroviruses as well as long and short interspersed elements is not only essential for evolving lncRNAs but is also a significant source of double-stranded RNA (dsRNA). From an lncRNA-centric point of view, the latter is a minor source of bother in the context of the entire cell; however, dsRNA is an essential threat. A viral infection is associated with cytoplasmic dsRNA, and endogenous RNA hybrids only differ from viral dsRNA by the 5' cap structure. Hence, a multi-layered defense network is in place to protect cells from viral infections but tolerates endogenous dsRNA structures. A first line of defense is established with compartmentalization; whereas endogenous dsRNA is found predominantly confined to the nucleus and the mitochondria, exogenous dsRNA reaches the cytoplasm. Here, various sensor proteins recognize features of dsRNA including the 5' phosphate group of viral RNAs or hybrids with a particular length but not specific nucleotide sequences. The sensors trigger cellular stress pathways and innate immunity via interferon signaling but also induce apoptosis via caspase activation. Because of its central role in viral recognition and immune activation, dsRNA sensing is implicated in autoimmune diseases and used to treat cancer.
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Affiliation(s)
| | | | | | - Andreas Werner
- Biosciences Institute, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; (S.S.); (S.A.-H.); (C.M.C.)
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Pulido MR, Martínez-Salas E, Sobrino F, Sáiz M. MDA5 cleavage by the Leader protease of foot-and-mouth disease virus reveals its pleiotropic effect against the host antiviral response. Cell Death Dis 2020; 11:718. [PMID: 32879301 PMCID: PMC7468288 DOI: 10.1038/s41419-020-02931-x] [Citation(s) in RCA: 10] [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: 05/20/2020] [Revised: 08/03/2020] [Accepted: 08/03/2020] [Indexed: 02/06/2023]
Abstract
The RIG-I-like receptor (RLR) melanoma differentiation-associated gene 5 (MDA5) plays a key role in triggering innate antiviral response during infection by RNA viruses. MDA5 activation leads to transcription induction of type-I interferon (IFN) and proinflammatory cytokines. MDA5 has also been associated with autoimmune and autoinflammatory diseases by dysfunctional activation of innate immune response in the absence of infection. Here, we show how foot-and-mouth disease virus (FMDV) counteracts the specific antiviral effect exerted by MDA5 targeting the protein for cleavage by the viral Leader protease (Lpro). MDA5 overexpression had an inhibitory effect on FMDV infection in IFN-competent cells. Remarkably, immunostimulatory viral RNA co-immunoprecipitated with MDA5 in infected cells. Moreover, specific cleavage of MDA5 by Lpro was detected in co-transfected cells, as well as during the course of FMDV infection. A significant reduction in IFN induction associated with MDA5 cleavage was detected by comparison with a non-cleavable MDA5 mutant protein with preserved antiviral activity. The Lpro cleavage site in MDA5 was identified as the RGRAR sequence in the conserved helicase motif VI, coinciding with that recently reported for Lpro in LGP2, another member of the RLRs family involved in antiviral defenses. Interestingly, specific mutations within the MDA5 Lpro target sequence have been associated with immune disease in mice and humans. Our results reveal a pleiotropic strategy for immune evasion based on a viral protease targeting phylogenetically conserved domains of immune sensors. Identification of viral strategies aimed to disrupt MDA5 functionality may also contribute to develop new treatment tools for MDA5-related disorders.
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Affiliation(s)
| | | | | | - Margarita Sáiz
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain.
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Vogel OA, Han J, Liang CY, Manicassamy S, Perez JT, Manicassamy B. The p150 Isoform of ADAR1 Blocks Sustained RLR signaling and Apoptosis during Influenza Virus Infection. PLoS Pathog 2020; 16:e1008842. [PMID: 32898178 PMCID: PMC7500621 DOI: 10.1371/journal.ppat.1008842] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 09/18/2020] [Accepted: 07/28/2020] [Indexed: 12/24/2022] Open
Abstract
Signaling through retinoic acid inducible gene I (RIG-I) like receptors (RLRs) is tightly regulated, with activation occurring upon sensing of viral nucleic acids, and suppression mediated by negative regulators. Under homeostatic conditions aberrant activation of melanoma differentiation-associated protein-5 (MDA5) is prevented through editing of endogenous dsRNA by RNA editing enzyme Adenosine Deaminase Acting on RNA (ADAR1). In addition, ADAR1 is postulated to play pro-viral and antiviral roles during viral infections that are dependent or independent of RNA editing activity. Here, we investigated the importance of ADAR1 isoforms in modulating influenza A virus (IAV) replication and revealed the opposing roles for ADAR1 isoforms, with the nuclear p110 isoform restricting versus the cytoplasmic p150 isoform promoting IAV replication. Importantly, we demonstrate that p150 is critical for preventing sustained RIG-I signaling, as p150 deficient cells showed increased IFN-β expression and apoptosis during IAV infection, independent of RNA editing activity. Taken together, the p150 isoform of ADAR1 is important for preventing sustained RIG-I induced IFN-β expression and apoptosis during viral infection.
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Affiliation(s)
- Olivia A. Vogel
- Department of Microbiology, University of Chicago, Chicago, Illinois, United States of America
| | - Julianna Han
- Department of Microbiology, University of Chicago, Chicago, Illinois, United States of America
| | - Chieh-Yu Liang
- Department of Microbiology and Immunology, University of Iowa, Iowa City, Iowa, United States of America
| | - Santhakumar Manicassamy
- Cancer Immunology, Inflammation, and Tolerance Program, GRU Cancer Center, Augusta University, Augusta, Georgia
| | - Jasmine T. Perez
- Department of Microbiology, University of Chicago, Chicago, Illinois, United States of America
| | - Balaji Manicassamy
- Department of Microbiology and Immunology, University of Iowa, Iowa City, Iowa, United States of America
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Stok JE, Vega Quiroz ME, van der Veen AG. Self RNA Sensing by RIG-I–like Receptors in Viral Infection and Sterile Inflammation. THE JOURNAL OF IMMUNOLOGY 2020; 205:883-891. [DOI: 10.4049/jimmunol.2000488] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 05/28/2020] [Indexed: 12/18/2022]
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Heraud-Farlow JE, Walkley CR. What do editors do? Understanding the physiological functions of A-to-I RNA editing by adenosine deaminase acting on RNAs. Open Biol 2020; 10:200085. [PMID: 32603639 PMCID: PMC7574547 DOI: 10.1098/rsob.200085] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Adenosine-to-inosine (A-to-I) editing is a post-transcriptional modification of RNA which changes its sequence, coding potential and secondary structure. Catalysed by the adenosine deaminase acting on RNA (ADAR) proteins, ADAR1 and ADAR2, A-to-I editing occurs at approximately 50 000-150 000 sites in mice and into the millions of sites in humans. The vast majority of A-to-I editing occurs in repetitive elements, accounting for the discrepancy in total numbers of sites between species. The species-conserved primary role of editing by ADAR1 in mammals is to suppress innate immune activation by unedited cell-derived endogenous RNA. In the absence of editing, inverted paired sequences, such as Alu elements, are thought to form stable double-stranded RNA (dsRNA) structures which trigger activation of dsRNA sensors, such as MDA5. A small subset of editing sites are within coding sequences and are evolutionarily conserved across metazoans. Editing by ADAR2 has been demonstrated to be physiologically important for recoding of neurotransmitter receptors in the brain. Furthermore, changes in RNA editing are associated with various pathological states, from the severe autoimmune disease Aicardi-Goutières syndrome, to various neurodevelopmental and psychiatric conditions and cancer. However, does detection of an editing site imply functional importance? Genetic studies in humans and genetically modified mouse models together with evolutionary genomics have begun to clarify the roles of A-to-I editing in vivo. Furthermore, recent developments suggest there may be the potential for distinct functions of editing during pathological conditions such as cancer.
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Affiliation(s)
- Jacki E Heraud-Farlow
- Cancer and RNA Laboratory, St Vincent's Institute of Medical Research, Fitzroy, VIC 3065, Australia.,Department of Medicine, St Vincent's Hospital, Melbourne Medical School, University of Melbourne, Fitzroy, VIC 3065, Australia
| | - Carl R Walkley
- Cancer and RNA Laboratory, St Vincent's Institute of Medical Research, Fitzroy, VIC 3065, Australia.,Department of Medicine, St Vincent's Hospital, Melbourne Medical School, University of Melbourne, Fitzroy, VIC 3065, Australia.,Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC 3000, Australia
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Guallar D, Fuentes-Iglesias A, Souto Y, Ameneiro C, Freire-Agulleiro O, Pardavila JA, Escudero A, Garcia-Outeiral V, Moreira T, Saenz C, Xiong H, Liu D, Xiao S, Hou Y, Wu K, Torrecilla D, Hartner JC, Blanco MG, Lee LJ, López M, Walkley CR, Wang J, Fidalgo M. ADAR1-Dependent RNA Editing Promotes MET and iPSC Reprogramming by Alleviating ER Stress. Cell Stem Cell 2020; 27:300-314.e11. [PMID: 32396862 DOI: 10.1016/j.stem.2020.04.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 04/02/2020] [Accepted: 04/23/2020] [Indexed: 12/31/2022]
Abstract
RNA editing of adenosine to inosine (A to I) is catalyzed by ADAR1 and dramatically alters the cellular transcriptome, although its functional roles in somatic cell reprogramming are largely unexplored. Here, we show that loss of ADAR1-mediated A-to-I editing disrupts mesenchymal-to-epithelial transition (MET) during induced pluripotent stem cell (iPSC) reprogramming and impedes acquisition of induced pluripotency. Using chemical and genetic approaches, we show that absence of ADAR1-dependent RNA editing induces aberrant innate immune responses through the double-stranded RNA (dsRNA) sensor MDA5, unleashing endoplasmic reticulum (ER) stress and hindering epithelial fate acquisition. We found that A-to-I editing impedes MDA5 sensing and sequestration of dsRNAs encoding membrane proteins, which promote ER homeostasis by activating the PERK-dependent unfolded protein response pathway to consequently facilitate MET. This study therefore establishes a critical role for ADAR1 and its A-to-I editing activity during cell fate transitions and delineates a key regulatory layer underlying MET to control efficient reprogramming.
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Affiliation(s)
- Diana Guallar
- Center for Research in Molecular Medicine and Chronic Diseases (CiMUS), Universidade de Santiago de Compostela (USC)-Health Research Institute (IDIS), Santiago de Compostela 15782, Spain; Department of Biochemistry and Molecular Biology, USC, Santiago de Compostela 15782, Spain.
| | - Alejandro Fuentes-Iglesias
- Center for Research in Molecular Medicine and Chronic Diseases (CiMUS), Universidade de Santiago de Compostela (USC)-Health Research Institute (IDIS), Santiago de Compostela 15782, Spain; Department of Physiology, USC, Santiago de Compostela 15782, Spain
| | - Yara Souto
- Center for Research in Molecular Medicine and Chronic Diseases (CiMUS), Universidade de Santiago de Compostela (USC)-Health Research Institute (IDIS), Santiago de Compostela 15782, Spain; Department of Physiology, USC, Santiago de Compostela 15782, Spain
| | - Cristina Ameneiro
- Center for Research in Molecular Medicine and Chronic Diseases (CiMUS), Universidade de Santiago de Compostela (USC)-Health Research Institute (IDIS), Santiago de Compostela 15782, Spain; Department of Physiology, USC, Santiago de Compostela 15782, Spain
| | - Oscar Freire-Agulleiro
- Center for Research in Molecular Medicine and Chronic Diseases (CiMUS), Universidade de Santiago de Compostela (USC)-Health Research Institute (IDIS), Santiago de Compostela 15782, Spain; Department of Physiology, USC, Santiago de Compostela 15782, Spain; NeurObesity Group & CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Santiago de Compostela 15706, Spain
| | - Jose Angel Pardavila
- Center for Research in Molecular Medicine and Chronic Diseases (CiMUS), Universidade de Santiago de Compostela (USC)-Health Research Institute (IDIS), Santiago de Compostela 15782, Spain; Department of Physiology, USC, Santiago de Compostela 15782, Spain
| | - Adriana Escudero
- Center for Research in Molecular Medicine and Chronic Diseases (CiMUS), Universidade de Santiago de Compostela (USC)-Health Research Institute (IDIS), Santiago de Compostela 15782, Spain; Department of Physiology, USC, Santiago de Compostela 15782, Spain
| | - Vera Garcia-Outeiral
- Center for Research in Molecular Medicine and Chronic Diseases (CiMUS), Universidade de Santiago de Compostela (USC)-Health Research Institute (IDIS), Santiago de Compostela 15782, Spain; Department of Physiology, USC, Santiago de Compostela 15782, Spain
| | - Tiago Moreira
- Center for Research in Molecular Medicine and Chronic Diseases (CiMUS), Universidade de Santiago de Compostela (USC)-Health Research Institute (IDIS), Santiago de Compostela 15782, Spain
| | - Carmen Saenz
- The Black Family Stem Cell Institute, Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Heng Xiong
- BGI-Shenzhen, Shenzhen 518083, China; China National GeneBank-Shenzhen, BGI-Shenzhen, Shenzhen 518083, China
| | - Dongbing Liu
- BGI-Shenzhen, Shenzhen 518083, China; China National GeneBank-Shenzhen, BGI-Shenzhen, Shenzhen 518083, China
| | - Shidi Xiao
- BGI-Shenzhen, Shenzhen 518083, China; Hubei Key Laboratory of Agricultural Bioinformatics, College of Informatics, Huazhong Agricultural University, Wuhan 430070, China
| | - Yong Hou
- BGI-Shenzhen, Shenzhen 518083, China; China National GeneBank-Shenzhen, BGI-Shenzhen, Shenzhen 518083, China
| | - Kui Wu
- BGI-Shenzhen, Shenzhen 518083, China; China National GeneBank-Shenzhen, BGI-Shenzhen, Shenzhen 518083, China
| | - Daniel Torrecilla
- Center for Research in Molecular Medicine and Chronic Diseases (CiMUS), Universidade de Santiago de Compostela (USC)-Health Research Institute (IDIS), Santiago de Compostela 15782, Spain
| | - Jochen C Hartner
- Horizon Discovery, Cambridge Research Park, Cambridge CB25 9TL, UK
| | - Miguel G Blanco
- Department of Biochemistry and Molecular Biology, USC, Santiago de Compostela 15782, Spain
| | - Leo J Lee
- BGI-Shenzhen, Shenzhen 518083, China; Department of Electrical and Computer Engineering, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3G4, Canada
| | - Miguel López
- Center for Research in Molecular Medicine and Chronic Diseases (CiMUS), Universidade de Santiago de Compostela (USC)-Health Research Institute (IDIS), Santiago de Compostela 15782, Spain; Department of Physiology, USC, Santiago de Compostela 15782, Spain; NeurObesity Group & CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Santiago de Compostela 15706, Spain
| | - Carl R Walkley
- St. Vincent's Institute of Medical Research, Fitzroy, VIC 3065, Australia; Department of Medicine, St. Vincent's Hospital, University of Melbourne, Fitzroy, VIC 3065, Australia; Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC 3000, Australia
| | - Jianlong Wang
- The Black Family Stem Cell Institute, Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Department of Medicine, Columbia Center for Human Development, Columbia University Irving Medical Center, New York, NY 10032, USA.
| | - Miguel Fidalgo
- Center for Research in Molecular Medicine and Chronic Diseases (CiMUS), Universidade de Santiago de Compostela (USC)-Health Research Institute (IDIS), Santiago de Compostela 15782, Spain; Department of Physiology, USC, Santiago de Compostela 15782, Spain.
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Mutual Regulation of RNA Silencing and the IFN Response as an Antiviral Defense System in Mammalian Cells. Int J Mol Sci 2020; 21:ijms21041348. [PMID: 32079277 PMCID: PMC7072894 DOI: 10.3390/ijms21041348] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 02/14/2020] [Accepted: 02/15/2020] [Indexed: 12/20/2022] Open
Abstract
RNA silencing is a posttranscriptional gene silencing mechanism directed by endogenous small non-coding RNAs called microRNAs (miRNAs). By contrast, the type-I interferon (IFN) response is an innate immune response induced by exogenous RNAs, such as viral RNAs. Endogenous and exogenous RNAs have typical structural features and are recognized accurately by specific RNA-binding proteins in each pathway. In mammalian cells, both RNA silencing and the IFN response are induced by double-stranded RNAs (dsRNAs) in the cytoplasm, but have long been considered two independent pathways. However, recent reports have shed light on crosstalk between the two pathways, which are mutually regulated by protein–protein interactions triggered by viral infection. This review provides brief overviews of RNA silencing and the IFN response and an outline of the molecular mechanism of their crosstalk and its biological implications. Crosstalk between RNA silencing and the IFN response may reveal a novel antiviral defense system that is regulated by miRNAs in mammalian cells.
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Avian Pattern Recognition Receptor Sensing and Signaling. Vet Sci 2020; 7:vetsci7010014. [PMID: 32012730 PMCID: PMC7157566 DOI: 10.3390/vetsci7010014] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Revised: 01/16/2020] [Accepted: 01/23/2020] [Indexed: 02/07/2023] Open
Abstract
Pattern recognition receptors (PRRs) are a class of immune sensors that play a critical role in detecting and responding to several conserved patterns of microorganisms. As such, they play a major role in the maintenance of immune homeostasis and anti-microbial defense. Fundamental knowledge pertaining to the discovery of PRR functions and their ligands continue to advance the understanding of immune system and disease resistance, which led to the rational design and/or application of various PRR ligands as vaccine adjuvants. In addition, the conserved nature of many PRRs throughout the animal kingdom has enabled the utilization of the comparative genomics approach in PRR identification and the study of evolution, structural features, and functions in many animal species including avian. In the present review, we focused on PRR sensing and signaling functions in the avian species, domestic chicken, mallard, and domestic goose. In addition to summarizing recent advances in the understanding of avian PRR functions, the present review utilized a comparative biology approach to identify additional PRRs, whose functions have been well studied in mammalians but await functional characterization in avian.
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Ablasser A, Hur S. Regulation of cGAS- and RLR-mediated immunity to nucleic acids. Nat Immunol 2020; 21:17-29. [PMID: 31819255 DOI: 10.1038/s41590-019-0556-1] [Citation(s) in RCA: 202] [Impact Index Per Article: 50.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 10/29/2019] [Indexed: 12/13/2022]
Abstract
Pathogen-derived nucleic acids are crucial signals for innate immunity. Despite the structural similarity between those and host nucleic acids, mammalian cells have been able to evolve powerful innate immune signaling pathways that originate from the detection of cytosolic nucleic acid species, one of the most prominent being the cGAS-STING pathway for DNA and the RLR-MAVS pathway for RNA, respectively. Recent advances have revealed a plethora of regulatory mechanisms that are crucial for balancing the activity of nucleic acid sensors for the maintenance of overall cellular homeostasis. Elucidation of the various mechanisms that enable cells to maintain control over the activity of cytosolic nucleic acid sensors has provided new insight into the pathology of human diseases and, at the same time, offers a rich and largely unexplored source for new therapeutic targets. This Review addresses the emerging literature on regulation of the sensing of cytosolic DNA and RNA via cGAS and RLRs.
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Affiliation(s)
- Andrea Ablasser
- Global Health Institute, Swiss Federal Institute of Technology, Lausanne, Switzerland.
| | - Sun Hur
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA.
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA.
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Cadena C, Hur S. Filament-like Assemblies of Intracellular Nucleic Acid Sensors: Commonalities and Differences. Mol Cell 2019; 76:243-254. [PMID: 31626748 PMCID: PMC6880955 DOI: 10.1016/j.molcel.2019.09.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 09/13/2019] [Accepted: 09/19/2019] [Indexed: 12/25/2022]
Abstract
Self versus non-self discrimination by innate immune sensors is critical for mounting effective immune responses against pathogens while avoiding harmful auto-inflammatory reactions against the host. Foreign DNA and RNA sensors must discriminate between self versus non-self nucleic acids, despite their shared building blocks and similar physicochemical properties. Recent structural and biochemical studies suggest that multiple steps of filament-like assembly are required for the functions of several nucleic acid sensors. Here, we discuss ligand discrimination and oligomerization of RIG-I-like receptors, AIM2-like receptors, and cGAS. We discuss how filament-like assembly allows for robust and accurate discrimination of self versus non-self nucleic acids and how these assemblies enable sensing of multiple distinct features in foreign nucleic acids, including structure, length, and modifications. We also discuss how individual receptors differ in their assembly and disassembly mechanisms and how these differences contribute to the diversity in nucleic acid specificity and pathogen detection strategies.
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Affiliation(s)
- Cristhian Cadena
- Program in Virology, Division of Medical Sciences, Harvard Medical School, Boston, MA 02115, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, MA 02115, USA
| | - Sun Hur
- Program in Virology, Division of Medical Sciences, Harvard Medical School, Boston, MA 02115, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, MA 02115, USA.
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Mandhana R, Qian LK, Horvath CM. Constitutively Active MDA5 Proteins Are Inhibited by Paramyxovirus V Proteins. J Interferon Cytokine Res 2019; 38:319-332. [PMID: 30130154 DOI: 10.1089/jir.2018.0049] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Excessive interferon (IFN) production and signaling can lead to immunological and developmental defects giving rise to autoimmune diseases referred to collectively as "type I interferonopathies." A subset of these diseases is caused by monogenic mutations affecting proteins involved in nucleic acid sensing, homeostasis, and metabolism. Interferonopathic mutations in the cytosolic antiviral sensor MDA5 render it constitutively hyperactive, resulting in chronic IFN production and IFN-stimulated gene expression. Few therapeutic options are available for patients with interferonopathic diseases, but a large number of IFN evasion and antagonism strategies have evolved in viral pathogens that can counteract IFN production and signaling to enhance virus replication. To test the hypothesis that these natural IFN suppressors could be used to subdue the activity of interferonopathic signaling proteins, hyperactive MDA5 variants were assessed for susceptibility to a family of viral MDA5 inhibitors. In this study, Paramyxovirus V proteins were tested for their ability to counteract constitutively active MDA5 proteins. Results indicate that the V proteins are able to bind to and disrupt the signaling activity of these MDA5 proteins, irrespective of their specific mutations, reducing IFN production and IFN-stimulated gene expression to effectively suppress the hyperactive antiviral response.
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Affiliation(s)
- Roli Mandhana
- Department of Molecular Biosciences, Northwestern University , Evanston, Illinois
| | - Lily K Qian
- Department of Molecular Biosciences, Northwestern University , Evanston, Illinois
| | - Curt M Horvath
- Department of Molecular Biosciences, Northwestern University , Evanston, Illinois
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48
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Nguyen TA, Bieging-Rolett KT, Putoczki TL, Wicks IP, Attardi LD, Pang KC. SIDT2 RNA Transporter Promotes Lung and Gastrointestinal Tumor Development. iScience 2019; 20:14-24. [PMID: 31546103 PMCID: PMC6817685 DOI: 10.1016/j.isci.2019.09.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 08/20/2019] [Accepted: 09/05/2019] [Indexed: 02/07/2023] Open
Abstract
RNautophagy is a newly described type of selective autophagy whereby cellular RNAs are transported into lysosomes for degradation. This process involves the transmembrane protein SIDT2, which transports double-stranded RNA (dsRNA) across the endolysosomal membrane. We previously demonstrated that SIDT2 is a transcriptional target of p53, but its role in tumorigenesis, if any, is unclear. Unexpectedly, we show here that Sidt2−/− mice with concurrent oncogenic KrasG12D activation develop significantly fewer tumors than littermate controls in a mouse model of lung adenocarcinoma. Consistent with this observation, loss of SIDT2 also leads to enhanced survival and delayed tumor development in an Apcmin/+ mouse model of intestinal cancer. Within the intestine, Apcmin/+;Sidt2−/− mice display accumulation of dsRNA in association with increased phosphorylation of eIF2α and JNK as well as elevated rates of apoptosis. Taken together, our data demonstrate a role for SIDT2, and by extension RNautophagy, in promoting tumor development. Loss of the SIDT2 double-stranded RNA (dsRNA) transporter leads to accumulation of dsRNA in tissues is associated with increased apoptosis reduces tumor burden in mouse models of lung adenocarcinoma and intestinal cancer
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Affiliation(s)
- Tan A Nguyen
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia; Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Kathryn T Bieging-Rolett
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, USA; Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Tracy L Putoczki
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia; Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Ian P Wicks
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia; Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Laura D Attardi
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, USA; Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Ken C Pang
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia; Murdoch Children's Research Institute, Parkville, VIC, Australia; Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia; Department of Psychiatry, University of Melbourne, Parkville, VIC, Australia.
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49
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Cadena C, Ahmad S, Xavier A, Willemsen J, Park S, Park JW, Oh SW, Fujita T, Hou F, Binder M, Hur S. Ubiquitin-Dependent and -Independent Roles of E3 Ligase RIPLET in Innate Immunity. Cell 2019; 177:1187-1200.e16. [PMID: 31006531 PMCID: PMC6525047 DOI: 10.1016/j.cell.2019.03.017] [Citation(s) in RCA: 119] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 01/28/2019] [Accepted: 03/07/2019] [Indexed: 01/22/2023]
Abstract
The conventional view posits that E3 ligases function primarily through conjugating ubiquitin (Ub) to their substrate molecules. We report here that RIPLET, an essential E3 ligase in antiviral immunity, promotes the antiviral signaling activity of the viral RNA receptor RIG-I through both Ub-dependent and -independent manners. RIPLET uses its dimeric structure and a bivalent binding mode to preferentially recognize and ubiquitinate RIG-I pre-oligomerized on dsRNA. In addition, RIPLET can cross-bridge RIG-I filaments on longer dsRNAs, inducing aggregate-like RIG-I assemblies. The consequent receptor clustering synergizes with the Ub-dependent mechanism to amplify RIG-I-mediated antiviral signaling in an RNA-length dependent manner. These observations show the unexpected role of an E3 ligase as a co-receptor that directly participates in receptor oligomerization and ligand discrimination. It also highlights a previously unrecognized mechanism by which the innate immune system measures foreign nucleic acid length, a common criterion for self versus non-self nucleic acid discrimination.
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Affiliation(s)
- Cristhian Cadena
- Program in Virology, Division of Medical Sciences, Harvard Medical School, Boston, MA 02115, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, MA 02115, USA
| | - Sadeem Ahmad
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, MA 02115, USA
| | - Audrey Xavier
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, MA 02115, USA; Institute of Chemistry and Biochemistry, Free University of Berlin, Germany
| | - Joschka Willemsen
- Research Group "Dynamics of Early Viral Infection and the Innate Antiviral Response" (division F170), German Cancer Research Center, 69120 Heidelberg, Germany
| | - Sehoon Park
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, MA 02115, USA
| | - Ji Woo Park
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, MA 02115, USA; Biology Department, Boston College, Chestnut Hill, MA, USA
| | - Seong-Wook Oh
- Laboratory of Molecular Genetics, Institute for Frontier Life and Medical Sciences, Kyoto University, Japan
| | - Takashi Fujita
- Laboratory of Molecular Genetics, Institute for Frontier Life and Medical Sciences, Kyoto University, Japan
| | - Fajian Hou
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, China
| | - Marco Binder
- Research Group "Dynamics of Early Viral Infection and the Innate Antiviral Response" (division F170), German Cancer Research Center, 69120 Heidelberg, Germany
| | - Sun Hur
- Program in Virology, Division of Medical Sciences, Harvard Medical School, Boston, MA 02115, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, MA 02115, USA.
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50
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Abstract
PURPOSE OF REVIEW The direct modification of RNA is now understood to be widespread, evolutionarily conserved and of consequence to cellular and organismal homeostasis. adenosine-to-inosine (A-to-I) RNA editing is one of the most common mammalian RNA modifications. Transcriptome-wide maps of the A-to-I editing exist, yet functions for the majority of editing sites remain opaque. Herein we discuss how hematology has been applied to determine physiological and malignant functions of A-to-I editing. RECENT FINDINGS Functional studies have established that A-to-I editing and ADAR1, responsible for the majority of editing in blood cells, are essential for normal blood cell homeostasis. ADAR1 edits endogenous RNA and reshapes its secondary structure, preventing MDA5 from perceiving the cells own RNA as pathogenic. Roles for ADAR1 in human leukaemia, and most recently, cancer cell intrinsic and extrinsic functions of ADAR1 have been identified that highlight ADAR1 as a therapeutic target in cancer. SUMMARY The studies reviewed have identified the key physiological function of ADAR1 and mechanistic basis for A-to-I editing in normal physiology and have now been extended to cancer. As our understanding of the biology and consequences of A-to-I editing evolve, it may be possible to target ADAR1 function advantageously in a number of settings.
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