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Latanova A, Starodubova E, Karpov V. Flaviviridae Nonstructural Proteins: The Role in Molecular Mechanisms of Triggering Inflammation. Viruses 2022; 14:v14081808. [PMID: 36016430 PMCID: PMC9414172 DOI: 10.3390/v14081808] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 08/13/2022] [Accepted: 08/15/2022] [Indexed: 12/24/2022] Open
Abstract
Members of the Flaviviridae family are posing a significant threat to human health worldwide. Many flaviviruses are capable of inducing severe inflammation in humans. Flaviviridae nonstructural proteins, apart from their canonical roles in viral replication, have noncanonical functions strongly affecting antiviral innate immunity. Among these functions, antagonism of type I IFN is the most investigated; meanwhile, more data are accumulated on their role in the other pathways of innate response. This review systematizes the last known data on the role of Flaviviridae nonstructural proteins in molecular mechanisms of triggering inflammation, with an emphasis on their interactions with TLRs and RLRs, interference with NF-κB and cGAS-STING signaling, and activation of inflammasomes.
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Ugarković Đ, Sermek A, Ljubić S, Feliciello I. Satellite DNAs in Health and Disease. Genes (Basel) 2022; 13:genes13071154. [PMID: 35885937 PMCID: PMC9324158 DOI: 10.3390/genes13071154] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 06/20/2022] [Accepted: 06/24/2022] [Indexed: 12/10/2022] Open
Abstract
Tandemly repeated satellite DNAs are major components of centromeres and pericentromeric heterochromatin which are crucial chromosomal elements responsible for accurate chromosome segregation. Satellite DNAs also contribute to genome evolution and the speciation process and are important for the maintenance of the entire genome inside the nucleus. In addition, there is increasing evidence for active and tightly regulated transcription of satellite DNAs and for the role of their transcripts in diverse processes. In this review, we focus on recent discoveries related to the regulation of satellite DNA expression and the role of their transcripts, either in heterochromatin establishment and centromere function or in gene expression regulation under various biological contexts. We discuss the role of satellite transcripts in the stress response and environmental adaptation as well as consequences of the dysregulation of satellite DNA expression in cancer and their potential use as cancer biomarkers.
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Affiliation(s)
- Đurđica Ugarković
- Department of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia; (A.S.); (S.L.)
- Correspondence: (Đ.U.); (I.F.); Tel.: +385-1-4561-083 (D.U.); +39-081-746-4317 (I.F.)
| | - Antonio Sermek
- Department of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia; (A.S.); (S.L.)
| | - Sven Ljubić
- Department of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia; (A.S.); (S.L.)
| | - Isidoro Feliciello
- Department of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia; (A.S.); (S.L.)
- Department of Clinical Medicine and Surgery, School of Medicine, University of Naples Federico II, Via Pansini 5, 80131 Naples, Italy
- Correspondence: (Đ.U.); (I.F.); Tel.: +385-1-4561-083 (D.U.); +39-081-746-4317 (I.F.)
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Chen H, Jiang L, Chen S, Hu Q, Huang Y, Wu Y, Chen W. HBx inhibits DNA sensing signaling pathway via ubiquitination and autophagy of cGAS. Virol J 2022; 19:55. [PMID: 35346247 PMCID: PMC8962493 DOI: 10.1186/s12985-022-01785-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 03/11/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Cyclic GMP-AMP synthase (cGAS) is a crucial DNA sensor and plays an important role in host antiviral innate immune responses. During hepatitis B virus (HBV) infection, the cGAS signaling pathway can suppress HBV replication. As an important regulatory protein of HBV, hepatitis B virus X protein (HBx) may serve as an antagonistic character to the cGAS/STING signaling pathway. In this study, we aim to investigate the functional role of HBx in the cGAS/STING signaling pathway. METHODS The effects of HBx on IFN-β promoter activity were measured by Dual-luciferase reporter assays. Ubiquitination and autophagy were analyzed by Western-blot and Co-immunoprecipitation assays. RESULTS Our results show that HBx down-regulates IFN-I production by directly promoting ubiquitination and autophagy degradation of cGAS. CONCLUSIONS HBV can antagonize host cGAS DNA sensing to promote HBV replication and provide novel insights to develop novel approaches against HBV infection.
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Affiliation(s)
- Hong Chen
- Department of Laboratory Medicine, The Second Affiliated Hospital of Chongqing Medical University, No.74 Linjing Road, Yuzhong District, Chongqing, 400010, China
| | - Linshan Jiang
- Department of Laboratory Medicine, The Second Affiliated Hospital of Chongqing Medical University, No.74 Linjing Road, Yuzhong District, Chongqing, 400010, China
| | - Shu Chen
- Department of Laboratory Medicine, The Second Affiliated Hospital of Chongqing Medical University, No.74 Linjing Road, Yuzhong District, Chongqing, 400010, China
| | - Qin Hu
- Department of Laboratory Medicine, The Second Affiliated Hospital of Chongqing Medical University, No.74 Linjing Road, Yuzhong District, Chongqing, 400010, China
| | - Ying Huang
- Department of Infectious Diseases, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Ying Wu
- Clinical Medicine Research Centre, Liuzhou People's Hospital, Guangxi Medical University, Liuzhou, China.
| | - Weixian Chen
- Department of Laboratory Medicine, The Second Affiliated Hospital of Chongqing Medical University, No.74 Linjing Road, Yuzhong District, Chongqing, 400010, China.
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Anwar S, Ul Islam K, Azmi MI, Iqbal J. cGAS-STING-mediated sensing pathways in DNA and RNA virus infections: crosstalk with other sensing pathways. Arch Virol 2021; 166:3255-3268. [PMID: 34622360 DOI: 10.1007/s00705-021-05211-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 07/04/2021] [Indexed: 12/25/2022]
Abstract
Viruses cause a variety of diseases in humans and other organisms. The most important defense mechanism against viral infections is initiated when the viral genome is sensed by host proteins, and this results in interferon production and pro-inflammatory cytokine responses. The sensing of the viral genome or its replication intermediates within host cells is mediated by cytosolic proteins. For example, cGAS and IFI16 recognize non-self DNA, and RIG-I and MDA5 recognize non-self RNA. Once these sensors are activated, they trigger a cascade of reactions activating downstream molecules, which eventually results in the transcriptional activation of type I and III interferons, which play a critical role in suppressing viral propagation, either by directly limiting their replication or by inducing host cells to inhibit viral protein synthesis. The immune response against viruses relies solely upon sensing of viral genomes and their downstream signaling molecules. Although DNA and RNA viruses are sensed by distinct classes of receptor proteins, there is a possibility of overlap between the viral DNA and viral RNA sensing mechanisms. In this review, we focus on various host sensing molecules and discuss the associated signaling pathways that are activated in response to different viral infections. We further highlight the possibility of crosstalk between the cGAS-STING and the RIG-I-MAVS pathways to limit viral infections. This comprehensive review delineates the mechanisms by which different viruses evade host cellular responses to sustain within the host cells.
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Affiliation(s)
- Saleem Anwar
- Multidisciplinary Centre for Advanced Research and Studies, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025, India
| | - Khursheed Ul Islam
- Multidisciplinary Centre for Advanced Research and Studies, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025, India
| | - Md Iqbal Azmi
- Multidisciplinary Centre for Advanced Research and Studies, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025, India
| | - Jawed Iqbal
- Multidisciplinary Centre for Advanced Research and Studies, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025, India.
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Wang Z, Chen J, Wu X, Ma D, Zhang X, Li R, Han C, Liu H, Yin X, Du Q, Tong D, Huang Y. PCV2 targets cGAS to inhibit type I interferon induction to promote other DNA virus infection. PLoS Pathog 2021; 17:e1009940. [PMID: 34543359 PMCID: PMC8483418 DOI: 10.1371/journal.ppat.1009940] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 09/30/2021] [Accepted: 09/03/2021] [Indexed: 01/28/2023] Open
Abstract
Viruses use diverse strategies to impair the antiviral immunity of host in order to promote infection and pathogenesis. Herein, we found that PCV2 infection promotes the infection of DNA viruses through inhibiting IFN-β induction in vivo and in vitro. In the early phase of infection, PCV2 promotes the phosphorylation of cGAS at S278 via activation of PI3K/Akt signaling, which directly silences the catalytic activity of cGAS. Subsequently, phosphorylation of cGAS at S278 can facilitate the K48-linked poly-ubiquitination of cGAS at K389, which can been served as a signal for recognizing by the ubiquitin-binding domain of histone deacetylase 6 (HDAC6), to promote the translocation of K48-ubiquitinated-cGAS from cytosol to autolysosome depending on the deacetylase activity of HDAC6, thereby eventually resulting in a markedly increased cGAS degradation in PCV2 infection-induced autophagic cells relative to Earle’s Balanced Salt Solution (EBSS)-induced autophagic cells (a typical starving autophagy). Importantly, we found that PCV2 Cap and its binding protein gC1qR act as predominant regulators to promote porcine cGAS phosphorylation and HDAC6 activation through mediating PI3K/AKT signaling and PKCδ signaling activation. Based on this finding, gC1qR-binding activity deficient PCV2 mutant (PCV2RmA) indeed shows a weakened inhibitory effect on IFN-β induction and a weaker boost effect for other DNA viruses infection compared to wild-type PCV2. Collectively, our findings illuminate a systematic regulation mechanism by which porcine circovirus counteracts the cGAS-STING signaling pathway to inhibit the type I interferon induction and promote DNA virus infection, and identify gC1qR as an important regulator for the immunosuppression induced by PCV2. PCV2 is well known for its ability to induce immunosuppression in pigs. However, how PCV2 infection interferes cGAS-STING signaling is still poorly understood. Herein, we demonstrate that PCV2 infection can phosphorylate porcine cGAS via gC1qR-mediated PI3K/AKT signaling to silence the catalytic activity of cGAS, while activates PKCδ signaling to promote histone deacetylase 6 (HDAC6) activation depending on the assistance of gC1qR. Subsequently, phosphorylation of cGAS facilitates the poly-ubiquitination of cGAS, then ubiquitinated-cGAS proteins are recruited and transported to autolysosome by activated HDAC6 depending on its deacetylase activity and ubiquitin-binding function, thereby eventually resulting in the autophagic degradation of cGAS in PCV2-infected cells. This study reveals that PCV2 can inhibit the activation of cGAS signaling pathway through two different mechanisms at different stages of infection and clarifies the internal relationship and cooperation model between these two mechanisms.
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Affiliation(s)
- Zhenyu Wang
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Jing Chen
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Xingchen Wu
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Dan Ma
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Xiaohua Zhang
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Ruizhen Li
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Cong Han
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Haixin Liu
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Xiangrui Yin
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Qian Du
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Dewen Tong
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
- * E-mail: (DT); (YH)
| | - Yong Huang
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
- * E-mail: (DT); (YH)
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Schustak J, Twarog M, Wu X, Wu HY, Huang Q, Bao Y. Mechanism of Nucleic Acid Sensing in Retinal Pigment Epithelium (RPE): RIG-I Mediates Type I Interferon Response in Human RPE. J Immunol Res 2021; 2021:9975628. [PMID: 34239945 PMCID: PMC8235977 DOI: 10.1155/2021/9975628] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 05/12/2021] [Accepted: 05/21/2021] [Indexed: 11/17/2022] Open
Abstract
Age-related macular degeneration (AMD), a degenerative disease of the outer retina, is the leading cause of blindness among the elderly. A hallmark of geographic atrophy (GA), an advanced type of nonneovascular AMD (dry AMD), is photoreceptor and retinal pigment epithelium (RPE) cell death. Currently, there are no FDA-approved therapies for GA due to a lack of understanding of the disease-causing mechanisms. Increasing evidence suggests that chronic inflammation plays a predominant role in the pathogenesis of dry AMD. Dead or stressed cells release danger signals and inflammatory factors, which causes further damage to neighboring cells. It has been reported that type I interferon (IFN) response is activated in RPE cells in patients with AMD. However, how RPE cells sense stress to initiate IFN response and cause further damage to the retina are still unknown. Although it has been reported that RPE can respond to extracellularly added dsRNA, it is unknown whether and how RPE detects and senses internally generated or internalized nucleic acids. Here, we elucidated the molecular mechanism by which RPE cells sense intracellular nucleic acids. Our data demonstrate that RPE cells can respond to intracellular RNA and induce type I IFN responses via the RIG-I (DExD/H-box helicase 58, DDX58) RNA helicase. In contrast, we showed that RPE cells were unable to directly sense and respond to DNA through the cGAS-STING pathway. We demonstrated that this was due to the absence of the cyclic GMP-AMP synthase (cGAS) DNA sensor in these cells. The activation of IFN response via RIG-I induced expression of cell death effectors and caused barrier function loss in RPE cells. These data suggested that RPE-intrinsic pathways of nucleic acid sensing are biased toward RNA sensing.
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Affiliation(s)
- Joshua Schustak
- The Department of Ophthalmology, Novartis Institutes for BioMedical Research, 22 Windsor Street, Cambridge, MA, USA
| | - Michael Twarog
- The Department of Ophthalmology, Novartis Institutes for BioMedical Research, 22 Windsor Street, Cambridge, MA, USA
| | - Xiaoqiu Wu
- The Department of Ophthalmology, Novartis Institutes for BioMedical Research, 22 Windsor Street, Cambridge, MA, USA
| | - Henry Y. Wu
- The Department of Ophthalmology, Novartis Institutes for BioMedical Research, 22 Windsor Street, Cambridge, MA, USA
| | - Qian Huang
- The Department of Ophthalmology, Novartis Institutes for BioMedical Research, 22 Windsor Street, Cambridge, MA, USA
| | - Yi Bao
- The Department of Ophthalmology, Novartis Institutes for BioMedical Research, 22 Windsor Street, Cambridge, MA, USA
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Barrera MJ, Aguilera S, Castro I, Carvajal P, Jara D, Molina C, González S, González MJ. Dysfunctional mitochondria as critical players in the inflammation of autoimmune diseases: Potential role in Sjögren's syndrome. Autoimmun Rev 2021; 20:102867. [PMID: 34118452 DOI: 10.1016/j.autrev.2021.102867] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Accepted: 04/11/2021] [Indexed: 12/13/2022]
Abstract
Relevant reviews highlight the association between dysfunctional mitochondria and inflammation, but few studies address the contribution of mitochondria and mitochondria-endoplasmic reticulum (ER) contact sites (MERCs) to cellular homeostasis and inflammatory signaling. The present review outlines the important role of mitochondria in cellular homeostasis and how dysfunctional mitochondrion can release and misplace mitochondrial components (cardiolipin, mitochondrial DNA (mtDNA), and mitochondrial formylated peptides) through multiple mechanisms. These components can act as damage-associated molecular patterns (DAMPs) and induce an inflammatory response via pattern recognition receptors (PRRs). Accumulation of damaged ROS-generating mitochondria, accompanied by the release of mitochondrial DAMPs, can activate PRRs such as the NLRP3 inflammasome, TLR9, cGAS/STING, and ZBP1. This process would explain the chronic inflammation that is observed in autoimmune diseases such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), type I diabetes (T1D), and Sjögren's syndrome. This review also provides a comprehensive overview of the importance of MERCs to mitochondrial function and morphology, cellular homeostasis, and the inflammatory response. MERCs play an important role in calcium homeostasis by mediating the transfer of calcium from the ER to the mitochondria and thereby facilitating the production of ATP. They also contribute to the synthesis and transfer of phospholipids, protein folding in the ER, mitochondrial fission, mitochondrial fusion, initiation of autophagosome formation, regulation of cell death/survival signaling, and regulation of immune responses. Therefore, alterations within MERCs could increase inflammatory signaling, modulate ER stress responses, cell homeostasis, and ultimately, the cell fate. This study shows severe ultrastructural alterations of mitochondria in salivary gland cells from Sjögren's syndrome patients for the first time, which could trigger alterations in cellular bioenergetics. This finding could explain symptoms such as fatigue and malfunction of the salivary glands in Sjögren's syndrome patients, which would contribute to the chronic inflammatory pathology of the disease. However, this is only a first step in solving this complex puzzle, and several other important factors such as changes in mitochondrial morphology, functionality, and their important contacts with other organelles require further in-depth study. Future work should focus on detecting the key milestones that are related to inflammation in patients with autoimmune diseases, such as Sjögren´s syndrome.
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Affiliation(s)
- María-José Barrera
- Facultad de Odontología, Universidad San Sebastián, Bellavista 7, Santiago, 8420524, Chile
| | | | - Isabel Castro
- Departamento de Tecnología Médica, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Patricia Carvajal
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Daniela Jara
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Claudio Molina
- Facultad de Odontología, Universidad San Sebastián, Bellavista 7, Santiago, 8420524, Chile
| | - Sergio González
- Escuela de Odontología, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
| | - María-Julieta González
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile.
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Fang Y, Peng K. Regulation of innate immune responses by cell death-associated caspases during virus infection. FEBS J 2021; 289:4098-4111. [PMID: 34089572 DOI: 10.1111/febs.16051] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 05/04/2021] [Accepted: 06/03/2021] [Indexed: 01/04/2023]
Abstract
Viruses are obligate intracellular pathogens that rely on cellular machinery for successful replication and dissemination. The host cells encode a number of different strategies to sense and restrict the invading viral pathogens. Caspase-mediated programmed cell death pathways that are triggered by virus infection, such as apoptosis and pyroptosis, provide a means for the infected cells to limit viral proliferation, leading to suicidal cell death (apoptosis) or lytic cell death and alerting uninfected cells to mount anti-viral responses (pyroptosis). However, some viruses can employ activated caspases to dampen the anti-viral responses and facilitate viral replication through cleavage of critical molecules of the innate immune pathways. The regulation of innate immune responses by caspase activation during virus infection has recently become an important topic. In this review, we briefly introduce the characteristics of different classes of caspases and the cell death pathways regulated by these caspases. We then describe how viruses trigger or dampen caspase activation during infection and how these activated caspases regulate three major innate immune response pathways of viral infections: the retinoic acid-inducible gene I-like receptor, toll-like receptor and cyclic GMP-AMP synthase-stimulator of interferon genes pathways.
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Affiliation(s)
- Yujie Fang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Ke Peng
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
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Leclerc S, Kitagawa K. The Role of Human Centromeric RNA in Chromosome Stability. Front Mol Biosci 2021; 8:642732. [PMID: 33869284 PMCID: PMC8044762 DOI: 10.3389/fmolb.2021.642732] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 02/26/2021] [Indexed: 12/20/2022] Open
Abstract
Chromosome instability is a hallmark of cancer and is caused by inaccurate segregation of chromosomes. One cellular structure used to avoid this fate is the kinetochore, which binds to the centromere on the chromosome. Human centromeres are poorly understood, since sequencing and analyzing repeated alpha-satellite DNA regions, which can span a few megabases at the centromere, are particularly difficult. However, recent analyses revealed that these regions are actively transcribed and that transcription levels are tightly regulated, unveiling a possible role of RNA at the centromere. In this short review, we focus on the recent discovery of the function of human centromeric RNA in the regulation and structure of the centromere, and discuss the consequences of dysregulation of centromeric RNA in cancer.
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Affiliation(s)
- Simon Leclerc
- Greehey Children's Cancer Research Institute, Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Katsumi Kitagawa
- Greehey Children's Cancer Research Institute, Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
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10
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Singh H, Koury J, Kaul M. Innate Immune Sensing of Viruses and Its Consequences for the Central Nervous System. Viruses 2021; 13:v13020170. [PMID: 33498715 PMCID: PMC7912342 DOI: 10.3390/v13020170] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 01/19/2021] [Accepted: 01/20/2021] [Indexed: 12/13/2022] Open
Abstract
Viral infections remain a global public health concern and cause a severe societal and economic burden. At the organismal level, the innate immune system is essential for the detection of viruses and constitutes the first line of defense. Viral components are sensed by host pattern recognition receptors (PRRs). PRRs can be further classified based on their localization into Toll-like receptors (TLRs), C-type lectin receptors (CLR), retinoic acid-inducible gene-I (RIG-I)-like receptors (RLRs), NOD-like receptors (NLRs) and cytosolic DNA sensors (CDS). TLR and RLR signaling results in production of type I interferons (IFNα and -β) and pro-inflammatory cytokines in a cell-specific manner, whereas NLR signaling leads to the production of interleukin-1 family proteins. On the other hand, CLRs are capable of sensing glycans present in viral pathogens, which can induce phagocytic, endocytic, antimicrobial, and pro- inflammatory responses. Peripheral immune sensing of viruses and the ensuing cytokine response can significantly affect the central nervous system (CNS). But viruses can also directly enter the CNS via a multitude of routes, such as the nasal epithelium, along nerve fibers connecting to the periphery and as cargo of infiltrating infected cells passing through the blood brain barrier, triggering innate immune sensing and cytokine responses directly in the CNS. Here, we review mechanisms of viral immune sensing and currently recognized consequences for the CNS of innate immune responses to viruses.
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Affiliation(s)
- Hina Singh
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA 92521, USA; (H.S.); (J.K.)
- Infectious and Inflammatory Disease Center, Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Jeffrey Koury
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA 92521, USA; (H.S.); (J.K.)
| | - Marcus Kaul
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA 92521, USA; (H.S.); (J.K.)
- Infectious and Inflammatory Disease Center, Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
- Correspondence:
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11
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Rosenthal K, Becker M, Rolf J, Siedentop R, Hillen M, Nett M, Lütz S. Catalytic Promiscuity of cGAS: A Facile Enzymatic Synthesis of 2'-3'-Linked Cyclic Dinucleotides. Chembiochem 2020; 21:3225-3228. [PMID: 32633874 PMCID: PMC7754487 DOI: 10.1002/cbic.202000433] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Indexed: 12/19/2022]
Abstract
Cyclic GMP-AMP synthase (cGAS) is a cytosolic DNA sensor that catalyzes the synthesis of the cyclic GMP-AMP dinucleotide 2'3'-cGAMP. 2'3'-cGAMP functions as inducer for the production of type I interferons. Derivatives of this important second messenger are highly valuable for pharmaceutical applications. However, the production of these analogues requires complex, multistep syntheses. Herein, human cGAS is shown to react with a series of unnatural nucleotides, thus leading to novel cyclic dinucleotides. Most substrate derivatives with modifications at the nucleobase, ribose, and the α-thio phosphate were accepted. These results demonstrate the catalytic promiscuity of human cGAS and its utility for the biocatalytic synthesis of cyclic dinucleotide derivatives.
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Affiliation(s)
- Katrin Rosenthal
- Department of Biochemical and Chemical EngineeringChair for Bioprocess EngineeringTU Dortmund University Emil-Figge-Strasse 6644227DortmundGermany
| | - Martin Becker
- Department of Biochemical and Chemical EngineeringChair for Bioprocess EngineeringTU Dortmund University Emil-Figge-Strasse 6644227DortmundGermany
| | - Jascha Rolf
- Department of Biochemical and Chemical EngineeringChair for Bioprocess EngineeringTU Dortmund University Emil-Figge-Strasse 6644227DortmundGermany
| | - Regine Siedentop
- Department of Biochemical and Chemical EngineeringChair for Bioprocess EngineeringTU Dortmund University Emil-Figge-Strasse 6644227DortmundGermany
| | - Michael Hillen
- Department of Biochemical and Chemical EngineeringChair for Bioprocess EngineeringTU Dortmund University Emil-Figge-Strasse 6644227DortmundGermany
| | - Markus Nett
- Department of Biochemical and Chemical EngineeringLaboratory of Technical BiologyTU Dortmund UniversityEmil-Figge-Strasse 6644227DortmundGermany
| | - Stephan Lütz
- Department of Biochemical and Chemical EngineeringChair for Bioprocess EngineeringTU Dortmund University Emil-Figge-Strasse 6644227DortmundGermany
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12
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Sun Y, Cheng Y. STING or Sting: cGAS-STING-Mediated Immune Response to Protozoan Parasites. Trends Parasitol 2020; 36:773-784. [PMID: 32736985 DOI: 10.1016/j.pt.2020.07.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 06/18/2020] [Accepted: 07/01/2020] [Indexed: 02/06/2023]
Abstract
Emerging evidence suggests that the DNA-sensing pathway plays a crucial role in innate immunity against multiple diseases, especially infectious diseases. Cyclic GMP-AMP synthase (cGAS), as a DNA sensor, and stimulator of interferon (IFN) genes (STING), as an adaptor protein, are the central components that link DNA sensing to immunologic functions - including, but not limited to, the type I IFN response. Recently, a series of studies have revealed that genomic DNA from protozoan parasites triggers the cGAS-STING pathway, and these studies identified the positive and negative regulators that modulate the signaling in parasite infection. Here, we summarize current understanding of the critical functions and potential applications of the cGAS-STING axis in parasitic diseases, specifically those caused by malaria parasites.
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Affiliation(s)
- Yifan Sun
- Laboratory of Pathogen Infection and Immunity, Department of Public Health and Preventive Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi 214122, Jiangsu, People's Republic of China
| | - Yang Cheng
- Laboratory of Pathogen Infection and Immunity, Department of Public Health and Preventive Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi 214122, Jiangsu, People's Republic of China.
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13
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Li M, Shu HB. Dephosphorylation of cGAS by PPP6C impairs its substrate binding activity and innate antiviral response. Protein Cell 2020; 11:584-599. [PMID: 32474700 PMCID: PMC7381519 DOI: 10.1007/s13238-020-00729-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Accepted: 04/24/2020] [Indexed: 12/12/2022] Open
Abstract
The cyclic GMP-AMP (cGAMP) synthase (cGAS) plays a critical role in host defense by sensing cytosolic DNA derived from microbial pathogens or mis-located cellular DNA. Upon DNA binding, cGAS utilizes GTP and ATP as substrates to synthesize cGAMP, leading to MITA-mediated innate immune response. In this study, we identified the phosphatase PPP6C as a negative regulator of cGAS-mediated innate immune response. PPP6C is constitutively associated with cGAS in un-stimulated cells. DNA virus infection causes rapid disassociation of PPP6C from cGAS, resulting in phosphorylation of human cGAS S435 or mouse cGAS S420 in its catalytic pocket. Mutation of this serine residue of cGAS impairs its ability to synthesize cGAMP upon DNA virus infection. In vitro experiments indicate that S420-phosphorylated mcGAS has higher affinity to GTP and enzymatic activity. PPP6C-deficiency promotes innate immune response to DNA virus in various cells. Our findings suggest that PPP6C-mediated dephosphorylation of a catalytic pocket serine residue of cGAS impairs its substrate binding activity and innate immune response, which provides a mechanism for keeping the DNA sensor cGAS inactive in the absence of infection to avoid autoimmune response.
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Affiliation(s)
- Mi Li
- Department of Infectious Diseases, Frontier Science Center for Immunology and Metabolism, Medical Research Institute, Zhongnan Hospital of Wuhan University, College of Life Sciences, Wuhan University, Wuhan, 430071, China
| | - Hong-Bing Shu
- Department of Infectious Diseases, Frontier Science Center for Immunology and Metabolism, Medical Research Institute, Zhongnan Hospital of Wuhan University, College of Life Sciences, Wuhan University, Wuhan, 430071, China.
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14
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USP29 maintains the stability of cGAS and promotes cellular antiviral responses and autoimmunity. Cell Res 2020; 30:914-927. [PMID: 32457395 PMCID: PMC7608407 DOI: 10.1038/s41422-020-0341-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 05/12/2020] [Indexed: 02/07/2023] Open
Abstract
Cyclic GMP-AMP synthase (cGAS) is an essential sensor of cytosolic DNA and critically mediates innate immune responses and autoimmunity. Modulating the activity and stability of cGAS provides potential strategies for treating viral or autoimmune diseases. Here, we report that ubiquitin-specific protease 29 (USP29) deubiquitinates and stabilizes cGAS and promotes cellular antiviral responses and autoimmunity. Knockdown or knockout of USP29 severely impairs Herpes simplex virus 1 (HSV-1)- or cytosolic DNA-induced expression of type I interferons (IFNs) and proinflammatory cytokines. Consistently, Usp29m/m mice produce decreased type I IFNs and proinflammatory cytokines after HSV-1 infection and are hypersensitive to HSV-1 infection compared to the wild-type littermates. In addition, genetic ablation of USP29 in Trex1−/− mice eliminated the detectable pathological and molecular autoimmune phenotypes. Mechanistically, USP29 constitutively interacts with cGAS, deconjugates K48-linked polyubiquitin chains from cGAS and stabilizes cGAS in uninfected cells or after HSV-1 infection. Reconstitution of cGAS into Usp29−/− cells fully rescues type I IFN induction and cellular antiviral responses after HSV-1 infection. Our findings thus reveal a critical role of USP29 in the innate antiviral responses against DNA viruses and autoimmune diseases and provide insight into the regulation of cGAS.
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15
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Yin X, Langer S, Zhang Z, Herbert KM, Yoh S, König R, Chanda SK. Sensor Sensibility-HIV-1 and the Innate Immune Response. Cells 2020; 9:E254. [PMID: 31968566 PMCID: PMC7016969 DOI: 10.3390/cells9010254] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 01/14/2020] [Accepted: 01/15/2020] [Indexed: 02/07/2023] Open
Abstract
Innate immunity represents the human immune system's first line of defense against a pathogenic intruder and is initiated by the recognition of conserved molecular structures known as pathogen-associated molecular patterns (PAMPs) by specialized cellular sensors, called pattern recognition receptors (PRRs). Human immunodeficiency virus type 1 (HIV-1) is a unique human RNA virus that causes acquired immunodeficiency syndrome (AIDS) in infected individuals. During the replication cycle, HIV-1 undergoes reverse transcription of its RNA genome and integrates the resulting DNA into the human genome. Subsequently, transcription of the integrated provirus results in production of new virions and spreading infection of the virus. Throughout the viral replication cycle, numerous nucleic acid derived PAMPs can be recognized by a diverse set of innate immune sensors in infected cells. However, HIV-1 has evolved efficient strategies to evade or counteract this immune surveillance and the downstream responses. Understanding the molecular underpinnings of the concerted actions of the innate immune system, as well as the corresponding viral evasion mechanisms during infection, is critical to understanding HIV-1 transmission and pathogenesis, and may provide important guidance for the design of appropriate adjuvant and vaccine strategies. Here, we summarize current knowledge of the molecular basis for sensing HIV-1 in human cells, including CD4+ T cells, dendritic cells, and macrophages. Furthermore, we discuss the underlying mechanisms by which innate sensing is regulated, and describe the strategies developed by HIV-1 to evade sensing and immune responses.
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Affiliation(s)
- Xin Yin
- Immunity and Pathogenesis Program, Infectious and Inflammatory Disease Center, Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA; (X.Y.); (S.L.); (Z.Z.); (K.M.H.); (S.Y.); (R.K.)
| | - Simon Langer
- Immunity and Pathogenesis Program, Infectious and Inflammatory Disease Center, Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA; (X.Y.); (S.L.); (Z.Z.); (K.M.H.); (S.Y.); (R.K.)
- Boehringer Ingelheim Pharma GmbH & Co. KG, 55216 Ingelheim am Rhein, Germany
| | - Zeli Zhang
- Immunity and Pathogenesis Program, Infectious and Inflammatory Disease Center, Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA; (X.Y.); (S.L.); (Z.Z.); (K.M.H.); (S.Y.); (R.K.)
- Division of Vaccine Discovery, La Jolla Institute for Immunology, 9420 Athena Cir, La Jolla, CA 92037, USA
| | - Kristina M. Herbert
- Immunity and Pathogenesis Program, Infectious and Inflammatory Disease Center, Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA; (X.Y.); (S.L.); (Z.Z.); (K.M.H.); (S.Y.); (R.K.)
| | - Sunnie Yoh
- Immunity and Pathogenesis Program, Infectious and Inflammatory Disease Center, Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA; (X.Y.); (S.L.); (Z.Z.); (K.M.H.); (S.Y.); (R.K.)
| | - Renate König
- Immunity and Pathogenesis Program, Infectious and Inflammatory Disease Center, Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA; (X.Y.); (S.L.); (Z.Z.); (K.M.H.); (S.Y.); (R.K.)
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, 63225 Langen, Germany
| | - Sumit K. Chanda
- Immunity and Pathogenesis Program, Infectious and Inflammatory Disease Center, Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA; (X.Y.); (S.L.); (Z.Z.); (K.M.H.); (S.Y.); (R.K.)
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