51
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Ritchie C, Carozza JA, Li L. Biochemistry, Cell Biology, and Pathophysiology of the Innate Immune cGAS-cGAMP-STING Pathway. Annu Rev Biochem 2022; 91:599-628. [PMID: 35287475 DOI: 10.1146/annurev-biochem-040320-101629] [Citation(s) in RCA: 45] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In the decade since the discovery of the innate immune cyclic GMP-AMP synthase (cGAS)- 2'3'-cyclic GMP-AMP (cGAMP)- stimulator of interferon genes (STING) pathway, its proper activation and dysregulation have been rapidly implicated in many aspects of human disease. Understanding the biochemical, cellular, and regulatory mechanisms of this pathway is critical to developing therapeutic strategies that either harness it to boost defense or inhibit it to prevent unwanted inflammation. In this review, we first discuss how the second messenger cGAMP is synthesized by cGAS in response to double-stranded DNA and cGAMP's subsequent activation of cell-type-dependent STING signaling cascades with differential physiological consequences. We then review how cGAMP as an immunotransmitter mediates tightly controlled cell-cell communication by being exported from producing cells and imported into responding cells via cell-type-specific transporters. Finally, we review mechanisms by which the cGAS-cGAMP-STING pathway responds to different sources of mislocalized double-stranded DNA in pathogen defense, cancer, and autoimmune diseases. Expected final online publication date for the Annual Review of Biochemistry, Volume 91 is June 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Christopher Ritchie
- Department of Biochemistry, Stanford University, Stanford, California, USA.,ChEM-H Institute, Stanford University, Stanford, California, USA;
| | - Jacqueline A Carozza
- ChEM-H Institute, Stanford University, Stanford, California, USA; .,Department of Chemistry, Stanford University, Stanford, California, USA
| | - Lingyin Li
- Department of Biochemistry, Stanford University, Stanford, California, USA.,ChEM-H Institute, Stanford University, Stanford, California, USA;
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52
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Wang D, Zhao H, Shen Y, Chen Q. A Variety of Nucleic Acid Species Are Sensed by cGAS, Implications for Its Diverse Functions. Front Immunol 2022; 13:826880. [PMID: 35185917 PMCID: PMC8854490 DOI: 10.3389/fimmu.2022.826880] [Citation(s) in RCA: 5] [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: 12/01/2021] [Accepted: 01/20/2022] [Indexed: 12/20/2022] Open
Abstract
Cyclic GMP-AMP synthase (cGAS) recognizes double-stranded DNA (dsDNA) derived from invading pathogens and induces an interferon response via activation of the key downstream adaptor protein stimulator of interferon genes (STING). This is the most classic biological function of the cGAS-STING signaling pathway and is critical for preventing pathogenic microorganism invasion. In addition, cGAS can interact with various types of nucleic acids, including cDNA, DNA : RNA hybrids, and circular RNA, to contribute to a diverse set of biological functions. An increasing number of studies have revealed an important relationship between the cGAS-STING signaling pathway and autophagy, cellular senescence, antitumor immunity, inflammation, and autoimmune diseases. This review details the mechanism of action of cGAS as it interacts with different types of nucleic acids, its rich biological functions, and the potential for targeting this pathway to treat various diseases.
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Affiliation(s)
| | | | - Yangkun Shen
- Fujian Key Laboratory of Innate Immune Biology, Biomedical Research Center of South China, Fujian Normal University, Fuzhou, China
| | - Qi Chen
- Fujian Key Laboratory of Innate Immune Biology, Biomedical Research Center of South China, Fujian Normal University, Fuzhou, China
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53
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Zhang ZD, Zhong B. Regulation and function of the cGAS-MITA/STING axis in health and disease. CELL INSIGHT 2022; 1:100001. [PMID: 37192983 PMCID: PMC10120319 DOI: 10.1016/j.cellin.2021.100001] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 11/18/2021] [Accepted: 12/06/2021] [Indexed: 05/18/2023]
Abstract
The innate immune systems detect pathogens via pattern-recognition receptors including nucleic acid sensors and non-nucleic acid sensors. Cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) synthase (cGAS, also known as MB21D1) is a cytosolic DNA sensor that recognizes double-stranded DNA (dsDNA) and catalyzes the synthesis of 2',3'-cGAMP. Subsequently, 2',3'-cGAMP binds to the adaptor protein mediator of IRF3 activation (MITA, also known as STING, MPYS, ERIS, and TMEM173) to activate downstream signaling cascades. The cGAS-MITA/STING signaling critically mediates immune responses against DNA viruses, retroviruses, bacteria, and protozoan parasites. In addition, recent discoveries have extended our understanding of the roles of the cGAS-MITA/STING pathway in autoimmune diseases and cancers. Here, we summarize the identification and activation of cGAS and MITA/STING, present the updated functions and regulatory mechanisms of cGAS-MITA/STING signaling and provide a comprehensive understanding of the cGAS-MITA/STING axis in autoimmune diseases and cancers.
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Affiliation(s)
- Zhi-Dong Zhang
- Department of Gastrointestinal Surgery, Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
- Department of Pulmonary and Critical Care Medicine, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
- Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, 430071, China
- Wuhan Research Center for Infectious Diseases and Cancer, Chinese Academy of Medical Sciences, Wuhan, 430071, China
| | - Bo Zhong
- Department of Gastrointestinal Surgery, Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
- Department of Pulmonary and Critical Care Medicine, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
- Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, 430071, China
- Department of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China
- Wuhan Research Center for Infectious Diseases and Cancer, Chinese Academy of Medical Sciences, Wuhan, 430071, China
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54
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Bui TM, Sumagin R. Neutrophils and micronuclei: An emerging link between genomic instability and cancer-driven inflammation. Mutat Res 2022; 824:111778. [PMID: 35334355 PMCID: PMC9756381 DOI: 10.1016/j.mrfmmm.2022.111778] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 02/22/2022] [Accepted: 03/16/2022] [Indexed: 06/14/2023]
Abstract
Two recent studies by Bui and Butin-Israeli et al. have established the novel contribution of neutrophils to genomic instability induction and aberrant shaping of the DNA repair landscape, particularly observed in patients with inflammatory bowel diseases (IBD) and/or progressive colorectal cancer (CRC). In addition, these back-to-back studies uncovered a sharp increase in the numbers of micronuclei and lagging chromosomes in pre-cancerous and cancerous epithelium in response to prolonged PMN exposure. Given the emerging link between neutrophils and micronuclei as well as the established role of micronuclei in cGAS/STING activation, this special commentary aims to elaborate on the mechanisms by which CRC cells may adapt to neutrophil-driven genomic instability while concurrently sustain an inflamed tumor niche. We postulate that such tumor microenvironment with constant immune cell presence, inflammatory milieu, and cumulative DNA damage can drive tumor adaptation and resistance to therapeutic interventions. Finally, we discuss potential novel therapeutic approaches that can be leveraged to target this emerging neutrophil-micronuclei pathological axis, thereby preventing perpetual CRC inflammation and unwanted tumor adaptation.
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Affiliation(s)
- Triet M Bui
- Department of Pathology, Northwestern University Feinberg School of Medicine, 300 East Superior St., Chicago, IL 60611, USA
| | - Ronen Sumagin
- Department of Pathology, Northwestern University Feinberg School of Medicine, 300 East Superior St., Chicago, IL 60611, USA.
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55
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ROS-Induced mtDNA Release: The Emerging Messenger for Communication between Neurons and Innate Immune Cells during Neurodegenerative Disorder Progression. Antioxidants (Basel) 2021; 10:antiox10121917. [PMID: 34943020 PMCID: PMC8750316 DOI: 10.3390/antiox10121917] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/23/2021] [Accepted: 11/27/2021] [Indexed: 02/04/2023] Open
Abstract
One of the most striking hallmarks shared by various neurodegenerative diseases, including Parkinson’s disease, Alzheimer’s disease and amyotrophic lateral sclerosis, is microglia-mediated and astrocyte-mediated neuroinflammation. Although inhibitions of both harmful proteins and aggregation are major treatments for neurodegenerative diseases, whether the phenomenon of non-normal protein or peptide aggregation is causally related to neuronal loss and synaptic damage is still controversial. Currently, excessive production of reactive oxygen species (ROS), which induces mitochondrial dysfunction in neurons that may play a key role in the regulation of immune cells, is proposed as a regulator in neurological disorders. In this review, we propose that mitochondrial DNA (mtDNA) release due to ROS may act on microglia and astrocytes adjacent to neurons to induce inflammation through activation of innate immune responses (such as cGAS/STING). Elucidating the relationship between mtDNA and the formation of a pro-inflammatory microenvironment could contribute to a better understanding of the mechanism of crosstalk between neuronal and peripheral immune cells and lead to the development of novel therapeutic approaches to neurodegenerative diseases.
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56
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Li X, Li X, Xie C, Cai S, Li M, Jin H, Wu S, Cui J, Liu H, Zhao Y. cGAS guards against chromosome end-to-end fusions during mitosis and facilitates replicative senescence. Protein Cell 2021; 13:47-64. [PMID: 34676498 PMCID: PMC8776970 DOI: 10.1007/s13238-021-00879-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 09/06/2021] [Indexed: 01/07/2023] Open
Abstract
As a sensor of cytosolic DNA, the role of cyclic GMP-AMP synthase (cGAS) in innate immune response is well established, yet how its functions in different biological conditions remain to be elucidated. Here, we identify cGAS as an essential regulator in inhibiting mitotic DNA double-strand break (DSB) repair and protecting short telomeres from end-to-end fusion independent of the canonical cGAS-STING pathway. cGAS associates with telomeric/subtelomeric DNA during mitosis when TRF1/TRF2/POT1 are deficient on telomeres. Depletion of cGAS leads to mitotic chromosome end-to-end fusions predominantly occurring between short telomeres. Mechanistically, cGAS interacts with CDK1 and positions them to chromosome ends. Thus, CDK1 inhibits mitotic non-homologous end joining (NHEJ) by blocking the recruitment of RNF8. cGAS-deficient human primary cells are defective in entering replicative senescence and display chromosome end-to-end fusions, genome instability and prolonged growth arrest. Altogether, cGAS safeguards genome stability by controlling mitotic DSB repair to inhibit mitotic chromosome end-to-end fusions, thus facilitating replicative senescence.
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Affiliation(s)
- Xiaocui Li
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Xiaojuan Li
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Chen Xie
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Sihui Cai
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Mengqiu Li
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Heping Jin
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Shu Wu
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Jun Cui
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Haiying Liu
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, China. .,Department of Biochemistry, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, China.
| | - Yong Zhao
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, China.,State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, 510006, China
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57
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Su Q, Mehta S, Zhang J. Liquid-liquid phase separation: Orchestrating cell signaling through time and space. Mol Cell 2021; 81:4137-4146. [PMID: 34619090 DOI: 10.1016/j.molcel.2021.09.010] [Citation(s) in RCA: 67] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 08/16/2021] [Accepted: 09/08/2021] [Indexed: 12/19/2022]
Abstract
Cell signaling is a complex process. The faithful transduction of information into specific cellular actions depends on the synergistic effects of many regulatory molecules, nurtured by their strict spatiotemporal regulation. Over the years, we have gained copious insights into the subcellular architecture supporting this spatiotemporal control, including the roles of membrane-bound organelles and various signaling nanodomains. Recently, liquid-liquid phase separation (LLPS) has been recognized as another potentially ubiquitous framework for organizing signaling molecules with high specificity and precise spatiotemporal control in cells. Here, we review the pervasive role of LLPS in signal transduction, highlighting several key pathways that intersect with LLPS, including examples in which LLPS is controlled by signaling events. We also examine how LLPS orchestrates signaling by compartmentalizing signaling molecules, amplifying signals non-linearly, and moderating signaling dynamics. We focus on the specific molecules that drive LLPS and highlight the known functional and pathological consequences of LLPS in each pathway.
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Affiliation(s)
- Qi Su
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Sohum Mehta
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Jin Zhang
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA; Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA; Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA.
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58
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Bai J, Liu F. cGAS‒STING signaling and function in metabolism and kidney diseases. J Mol Cell Biol 2021; 13:728-738. [PMID: 34665236 PMCID: PMC8718186 DOI: 10.1093/jmcb/mjab066] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 09/01/2021] [Accepted: 09/02/2021] [Indexed: 12/03/2022] Open
Abstract
The cyclic GMP‒AMP synthase (cGAS)‒stimulator of interferon genes (STING) signaling pathway senses the presence of cytosolic DNA and, in turn, triggers downstream signaling to induce the expression of inflammatory and type I interferon genes in immune cells. Whereas the innate immune function of the cGAS‒STING pathway is well studied over the past years, emerging evidence suggests that this signaling pathway may have additional functions beyond innate immune surveillance. Consistent with this notion, dysregulation of the cGAS‒STING signaling pathway in adipocytes, hepatocytes, and renal proximal tubule epithelial cells are associated with metabolic dysfunction, impaired energy homeostasis, and kidney diseases. In this review, we summarize current understanding of the cGAS‒STING pathway in several metabolic diseases such as obesity, insulin resistance, alcoholic and nonalcoholic fatty liver diseases, as well as acute kidney injury and chronic kidney disease. We also review the interaction between the cGAS‒STING pathway and lipid metabolism. Lastly, we discuss potential mechanisms by which cGAS‒STING signaling regulates metabolism and point toward future avenues of research targeting the cGAS‒STING pathway as possible means to treat common metabolic disorders.
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Affiliation(s)
- Juli Bai
- Departments of Pharmacology, University of Texas Health at San Antonio, San Antonio, TX 78229, USA.,National Clinical Research Center for Metabolic Diseases, Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, Ministry of Education, and Department of Metabolism and Endocrinology, The Second Xiangya Hospital of Central South University, Changsha 410011, China
| | - Feng Liu
- Departments of Pharmacology, University of Texas Health at San Antonio, San Antonio, TX 78229, USA.,National Clinical Research Center for Metabolic Diseases, Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, Ministry of Education, and Department of Metabolism and Endocrinology, The Second Xiangya Hospital of Central South University, Changsha 410011, China
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59
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Zhong L, Shu HB. Mitotic inactivation of the cGAS‒MITA/STING pathways. J Mol Cell Biol 2021; 13:721-727. [PMID: 34609492 PMCID: PMC8718187 DOI: 10.1093/jmcb/mjab061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Revised: 08/12/2021] [Accepted: 08/23/2021] [Indexed: 11/13/2022] Open
Abstract
The cyclic guanosine monophosphate‒adenosine monophosphate synthase (cGAS)‒mediator of interferon response factor 3 activation/stimulator of interferon genes (MITA/STING) axis has emerged as a major pathway, which senses microbial or mislocated cellular DNA in the cytosol to trigger innate immune responses. cGAS senses cytosolic DNA without a preference of self- or nonself-DNA. How the cGAS‒MITA/STING axis is inactivated upon nuclear envelope breakdown (NEBD) at mitotic entry in vertebrate cells to avoid self-DNA sensing remains unclear until very recently. In this review, we summarize the recent advances on how cGAS responds to chromosomes upon NEBD and the mechanisms involved in the inactivation of the cGAS‒MITA/STING pathways in mitosis.
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Affiliation(s)
- Li Zhong
- Department of Infectious Diseases, Frontier Science Center for Immunology and Metabolism, Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Research Unit of Innate Immune and Inflammatory Diseases of the Chinese Academy of Medical Sciences, 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, Wuhan University, Research Unit of Innate Immune and Inflammatory Diseases of the Chinese Academy of Medical Sciences, Wuhan 430071, China
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60
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Regulation of cGAS-STING pathway - Implications for systemic lupus erythematosus. RHEUMATOLOGY AND IMMUNOLOGY RESEARCH 2021; 2:173-184. [PMID: 36465073 PMCID: PMC9524788 DOI: 10.2478/rir-2021-0023] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 10/07/2021] [Indexed: 12/22/2022]
Abstract
Abstract
Type I interferon (IFN-I) is implicated in the pathogenesis of systemic lupus erythematosus (SLE) and the closely associated monogenic autoinflammatory disorders termed the “interferonopathies.” Recently, the cytosolic DNA sensor cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS) and its downstream signaling adaptor stimulator of interferon genes (STING) have been identified as having important, if not central, roles in driving IFN-I expression in response to self-DNA. This review highlights the many ways in which this pathway is regulated in order to prevent self-DNA recognition and underlines the importance of maintaining tight control in order to prevent autoimmune disease. We will discuss the murine and human studies that have implicated the cGAS-STING pathway as being an important contributor to breakdown in tolerance in SLE and highlight the potential therapeutic application of this knowledge for the treatment of SLE.
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61
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de Oliveira Mann CC, Hopfner K. Nuclear cGAS: guard or prisoner? EMBO J 2021; 40:e108293. [PMID: 34250619 PMCID: PMC8365253 DOI: 10.15252/embj.2021108293] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 05/17/2021] [Accepted: 06/18/2021] [Indexed: 12/24/2022] Open
Abstract
cGAS, an innate immune sensor of cellular stress, recognizes double-stranded DNA mislocalized in the cytosol upon infection, mitochondrial stress, DNA damage, or malignancy. Early models suggested that cytosolic localization of cGAS prevents autoreactivity to nuclear and mitochondrial self-DNA, but this paradigm has shifted in light of recent findings of cGAS as a predominantly nuclear protein tightly bound to chromatin. This has raised the question how nuclear cGAS is kept inactive while being surrounded by chromatin, and what function nuclear localization of cGAS may serve in the first place? Cryo-EM structures have revealed that cGAS interacts with nucleosomes, the minimal units of chromatin, mainly via histones H2A/H2B, and that these protein-protein interactions block cGAS from DNA binding and thus prevent autoreactivity. Here, we discuss the biological implications of nuclear cGAS and its interaction with chromatin, including various mechanisms for nuclear cGAS inhibition, release of chromatin-bound cGAS, regulation of different cGAS pools in the cell, and chromatin structure/chromatin protein effects on cGAS activation leading to cGAS-induced autoimmunity.
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Affiliation(s)
- Carina C de Oliveira Mann
- Gene CenterLudwig‐Maximilians‐UniversitätMunichGermany
- Department of BiochemistryLudwig‐Maximilians‐UniversitätMunichGermany
| | - Karl‐Peter Hopfner
- Gene CenterLudwig‐Maximilians‐UniversitätMunichGermany
- Department of BiochemistryLudwig‐Maximilians‐UniversitätMunichGermany
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62
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Abstract
The cyclic GMP-AMP (cGAMP) synthase (cGAS) has been identified as a cytosolic double stranded DNA sensor that plays a pivotal role in the type I interferon and inflammation responses via the STING-dependent signaling pathway. In the past several years, a growing body of evidence has revealed that cGAS is also localized in the nucleus where it is associated with distinct nuclear substructures such as nucleosomes, DNA replication forks, the double-stranded breaks, and centromeres, suggesting that cGAS may have other functions in addition to its role in DNA sensing. However, while the innate immune function of cGAS is well established, the non-canonical nuclear function of cGAS remains poorly understood. Here, we review our current understanding of the complex nature of nuclear cGAS and point to open questions on the novel roles and the mechanisms of action of this protein as a key regulator of cell nuclear function, beyond its well-established role in dsDNA sensing and innate immune response.
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Affiliation(s)
- Juli Bai
- Departments of Pharmacology, University of Texas Health at San Antonio, San Antonio, TX, USA. .,National Clinical Research Center for Metabolic Diseases, Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, Ministry of Education, and Department of Metabolism and Endocrinology, The Second Xiangya Hospital of Central South University, Changsha, 410011, China.
| | - Feng Liu
- Departments of Pharmacology, University of Texas Health at San Antonio, San Antonio, TX, USA. .,National Clinical Research Center for Metabolic Diseases, Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, Ministry of Education, and Department of Metabolism and Endocrinology, The Second Xiangya Hospital of Central South University, Changsha, 410011, China.
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63
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Bennett ZT, Li S, Sumer BD, Gao J. Polyvalent design in the cGAS-STING pathway. Semin Immunol 2021; 56:101580. [PMID: 34920941 PMCID: PMC8792294 DOI: 10.1016/j.smim.2021.101580] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 12/06/2021] [Accepted: 12/09/2021] [Indexed: 01/02/2023]
Abstract
Polyvalent interactions mediate the formation of higher-order macromolecular assemblies to improve the sensitivity, specificity, and temporal response of biological signals. In host defense, innate immune pathways recognize danger signals to alert host of insult or foreign invasion, while limiting aberrant activation from auto-immunity and cellular senescence. Of recent attention are the unique higher-order assemblies in the cGAS-STING pathway. Natural stimulation of cGAS enzymes by dsDNA induces phase separation and enzymatic activation for switchlike production of cGAMP. Subsequent binding of cGAMP to STING induces oligomerization of STING molecules, offering a scaffold for kinase assembly and signaling transduction. Additionally, the discovery of PC7A, a synthetic polymer which activates STING through a non-canonical biomolecular condensation, illustrates the engineering design of agonists by polyvalency principles. Herein, we discuss a mechanistic and functional comparison of natural and synthetic agonists to advance our understanding in STING signaling and highlight the principles of polyvalency in innate immune activation. The combination of exogenous cGAMP along with synthetic PC7A stimulation of STING offers a synergistic strategy in spatiotemporal orchestration of the immune milieu for a safe and effective immunotherapy against cancer.
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Affiliation(s)
- Zachary T Bennett
- Department of Pharmacology, Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Suxin Li
- Department of Pharmacology, Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Baran D Sumer
- Department of Otolaryngology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jinming Gao
- Department of Pharmacology, Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Otolaryngology, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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64
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Molinaro C, Martoriati A, Cailliau K. Proteins from the DNA Damage Response: Regulation, Dysfunction, and Anticancer Strategies. Cancers (Basel) 2021; 13:3819. [PMID: 34359720 PMCID: PMC8345162 DOI: 10.3390/cancers13153819] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 07/22/2021] [Accepted: 07/26/2021] [Indexed: 12/21/2022] Open
Abstract
Cells respond to genotoxic stress through a series of complex protein pathways called DNA damage response (DDR). These monitoring mechanisms ensure the maintenance and the transfer of a correct genome to daughter cells through a selection of DNA repair, cell cycle regulation, and programmed cell death processes. Canonical or non-canonical DDRs are highly organized and controlled to play crucial roles in genome stability and diversity. When altered or mutated, the proteins in these complex networks lead to many diseases that share common features, and to tumor formation. In recent years, technological advances have made it possible to benefit from the principles and mechanisms of DDR to target and eliminate cancer cells. These new types of treatments are adapted to the different types of tumor sensitivity and could benefit from a combination of therapies to ensure maximal efficiency.
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Affiliation(s)
| | | | - Katia Cailliau
- Univ. Lille, CNRS, UMR 8576-UGSF-Unité de Glycobiologie Structurale et Fonctionnelle, F-59000 Lille, France; (C.M.); (A.M.)
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65
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Rech L, Rainer PP. The Innate Immune cGAS-STING-Pathway in Cardiovascular Diseases - A Mini Review. Front Cardiovasc Med 2021; 8:715903. [PMID: 34381828 PMCID: PMC8349977 DOI: 10.3389/fcvm.2021.715903] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 07/01/2021] [Indexed: 12/12/2022] Open
Abstract
Inflammation plays a central role in cardiovascular diseases (CVD). One pathway under investigation is the innate immune DNA sensor cyclic GMP-AMP synthase (cGAS) and its downstream receptor stimulator of interferon genes (STING). cGAS-STING upregulates type I interferons in response to pathogens. Recent studies show that also self-DNA may activate cGAS-STING, for instance, DNA released from nuclei or mitochondria during obesity or myocardial infarction. Here, we focus on emerging evidence describing the interaction of cGAS-STING with cardiovascular risk factors and disease. We also touch on translational therapeutic opportunities and potential further investigations.
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Affiliation(s)
- Lavinia Rech
- Division of Cardiology, Department of Internal Medicine, Medical University of Graz, Graz, Austria
| | - Peter P Rainer
- Division of Cardiology, Department of Internal Medicine, Medical University of Graz, Graz, Austria.,BioTechMed Graz, Graz, Austria
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66
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Hong Z, Ma T, Liu X, Wang C. cGAS-STING pathway: post-translational modifications and functions in sterile inflammatory diseases. FEBS J 2021; 289:6187-6208. [PMID: 34310043 DOI: 10.1111/febs.16137] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 07/12/2021] [Accepted: 07/22/2021] [Indexed: 02/06/2023]
Abstract
Cytoplasmic microbial and host aberrant DNAs act as danger signals and trigger host immune responses. Upon recognition, the cytosolic DNA sensor cyclic GMP-AMP synthase (cGAS) catalyzes the production of a second messenger 2'3'-cGAMP, which activates endoplasmic reticulum (ER)-associated stimulator of interferon (IFN) genes (STING) and ultimately leads to the induction of type I IFNs and inflammatory genes that collectively initiate host immune defense against microbial invasion. Inappropriate activation or suppression of this signaling pathway has been implicated in the development of some autoimmune diseases, sterile inflammation, and cancers. In this review, we describe how the activity of cGAS and STING is regulated by host post-translational modifications and summarize the recent advances of cell-specific cGAS-STING activation and its association in sterile inflammatory diseases. We also discuss key outstanding questions in the field, including how our knowledge of cGAS-STING pathway could be translated into clinical applications.
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Affiliation(s)
- Ze Hong
- State Key Laboratory of Natural Medicines, Department of Life Science and Technology, China Pharmaceutical University, Nanjing, China
| | - Tianchi Ma
- Center for Microbes, Development and Health, Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Xing Liu
- Center for Microbes, Development and Health, Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Chen Wang
- State Key Laboratory of Natural Medicines, Department of Life Science and Technology, China Pharmaceutical University, Nanjing, China
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67
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Kutay U, Jühlen R, Antonin W. Mitotic disassembly and reassembly of nuclear pore complexes. Trends Cell Biol 2021; 31:1019-1033. [PMID: 34294532 DOI: 10.1016/j.tcb.2021.06.011] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/28/2021] [Accepted: 06/28/2021] [Indexed: 12/19/2022]
Abstract
Nuclear pore complexes (NPCs) are huge protein assemblies within the nuclear envelope (NE) that serve as selective gates for macromolecular transport between nucleus and cytoplasm. When higher eukaryotic cells prepare for division, they rapidly disintegrate NPCs during NE breakdown such that nuclear and cytoplasmic components mix to enable the formation of a cytoplasmic mitotic spindle. At the end of mitosis, reassembly of NPCs is coordinated with the establishment of the NE around decondensing chromatin. We review recent progress on mitotic NPC disassembly and reassembly, focusing on vertebrate cells. We highlight novel mechanistic insights into how NPCs are rapidly disintegrated into conveniently reusable building blocks, and put divergent models of (post-)mitotic NPC assembly into a spatial and temporal context.
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Affiliation(s)
- Ulrike Kutay
- Institute of Biochemistry, Department of Biology, Eidgenössische Technische Hochschule (ETH) Zurich, Otto-Stern-Weg 3, 8093 Zurich, Switzerland.
| | - Ramona Jühlen
- Institute of Biochemistry and Molecular Cell Biology, Medical School, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University, Pauwelsstrasse 30, 52074 Aachen, Germany
| | - Wolfram Antonin
- Institute of Biochemistry and Molecular Cell Biology, Medical School, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University, Pauwelsstrasse 30, 52074 Aachen, Germany.
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68
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Wischnewski M, Ablasser A. Interplay of cGAS with chromatin. Trends Biochem Sci 2021; 46:822-831. [PMID: 34215510 DOI: 10.1016/j.tibs.2021.05.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 05/21/2021] [Accepted: 05/31/2021] [Indexed: 01/07/2023]
Abstract
Recognition of DNA is an evolutionarily highly conserved mechanism of immunity. In mammals, the cGAS-STING pathway plays a central role in coupling DNA sensing to the execution of innate immune mechanisms, both in contexts of infection as well as in noninfectious settings of cellular stress and injury. The indiscriminate ability of double-stranded DNA (dsDNA) to activate cGAS challenges our understanding on how engagement of this pathway is prevented on genomic self-DNA under homeostatic conditions. Here, we review recent discoveries on the regulation of cGAS on chromatin and we discuss implications for cGAS-dependent inflammatory phenotypes. We close by highlighting emerging developments on the role of nuclear cGAS and related open questions for future research.
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Affiliation(s)
- Marilena Wischnewski
- Global Health Institute, Swiss Federal Institute of Technology Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Andrea Ablasser
- Global Health Institute, Swiss Federal Institute of Technology Lausanne (EPFL), 1015 Lausanne, Switzerland.
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69
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Yu L, Liu P. Cytosolic DNA sensing by cGAS: regulation, function, and human diseases. Signal Transduct Target Ther 2021; 6:170. [PMID: 33927185 PMCID: PMC8085147 DOI: 10.1038/s41392-021-00554-y] [Citation(s) in RCA: 84] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 02/17/2021] [Accepted: 03/08/2021] [Indexed: 12/16/2022] Open
Abstract
Sensing invasive cytosolic DNA is an integral component of innate immunity. cGAS was identified in 2013 as the major cytosolic DNA sensor that binds dsDNA to catalyze the synthesis of a special asymmetric cyclic-dinucleotide, 2'3'-cGAMP, as the secondary messenger to bind and activate STING for subsequent production of type I interferons and other immune-modulatory genes. Hyperactivation of cGAS signaling contributes to autoimmune diseases but serves as an adjuvant for anticancer immune therapy. On the other hand, inactivation of cGAS signaling causes deficiency to sense and clear the viral and bacterial infection and creates a tumor-prone immune microenvironment to facilitate tumor evasion of immune surveillance. Thus, cGAS activation is tightly controlled. In this review, we summarize up-to-date multilayers of regulatory mechanisms governing cGAS activation, including cGAS pre- and post-translational regulations, cGAS-binding proteins, and additional cGAS regulators such as ions and small molecules. We will also reveal the pathophysiological function of cGAS and its product cGAMP in human diseases. We hope to provide an up-to-date review for recent research advances of cGAS biology and cGAS-targeted therapies for human diseases.
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Affiliation(s)
- Le Yu
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Pengda Liu
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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70
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Shen Z, Wei L, Yu ZB, Yao ZY, Cheng J, Wang YT, Song XT, Li M. The Roles of TRIMs in Antiviral Innate Immune Signaling. Front Cell Infect Microbiol 2021; 11:628275. [PMID: 33791238 PMCID: PMC8005608 DOI: 10.3389/fcimb.2021.628275] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 02/02/2021] [Indexed: 01/06/2023] Open
Abstract
The Tripartite motif (TRIM) protein family, which contains over 80 members in human sapiens, is the largest subfamily of the RING-type E3 ubiquitin ligase family. It is implicated in regulating various cellular functions, including cell cycle process, autophagy, and immune response. The dysfunction of TRIMs may lead to numerous diseases, such as systemic lupus erythematosus (SLE). Lots of studies in recent years have demonstrated that many TRIM proteins exert antiviral roles. TRIM proteins could affect viral replication by regulating the signaling pathways of antiviral innate immune responses. Besides, TRIM proteins can directly target viral components, which can lead to the degradation or functional inhibition of viral protein through degradative or non-degradative mechanisms and consequently interrupt the viral lifecycle. However, new evidence suggests that some viruses may manipulate TRIM proteins for their replication. Here, we summarize the latest discoveries on the interactions between TRIM protein and virus, especially TRIM proteins’ role in the signaling pathway of antiviral innate immune response and the direct “game” between them.
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Affiliation(s)
- Zhou Shen
- Key Laboratory of Immune Mechanism and Intervention on Serious Disease in Hebei Province, Department of Immunology, Hebei Medical University, Shijiazhuang, China.,Center Laboratory, Affiliated Hospital of Hebei University, Baoding, China
| | - Lin Wei
- Key Laboratory of Immune Mechanism and Intervention on Serious Disease in Hebei Province, Department of Immunology, Hebei Medical University, Shijiazhuang, China
| | - Zhi-Bo Yu
- Key Laboratory of Immune Mechanism and Intervention on Serious Disease in Hebei Province, Department of Immunology, Hebei Medical University, Shijiazhuang, China
| | - Zhi-Yan Yao
- Key Laboratory of Immune Mechanism and Intervention on Serious Disease in Hebei Province, Department of Immunology, Hebei Medical University, Shijiazhuang, China
| | - Jing Cheng
- Key Laboratory of Immune Mechanism and Intervention on Serious Disease in Hebei Province, Department of Immunology, Hebei Medical University, Shijiazhuang, China
| | - Yu-Tong Wang
- Key Laboratory of Immune Mechanism and Intervention on Serious Disease in Hebei Province, Department of Immunology, Hebei Medical University, Shijiazhuang, China
| | - Xiao-Tian Song
- Key Laboratory of Immune Mechanism and Intervention on Serious Disease in Hebei Province, Department of Immunology, Hebei Medical University, Shijiazhuang, China
| | - Miao Li
- Key Laboratory of Immune Mechanism and Intervention on Serious Disease in Hebei Province, Department of Immunology, Hebei Medical University, Shijiazhuang, China
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71
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CDK1 promotes the stemness of lung cancer cells through interacting with Sox2. Clin Transl Oncol 2021; 23:1743-1751. [PMID: 33721187 DOI: 10.1007/s12094-021-02575-z] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 02/15/2021] [Indexed: 12/17/2022]
Abstract
OBJECTIVES The promoting roles of cyclin dependent kinase 1 (CDK1) have been revealed in various tumors, however, its effects in the progression of cancer stem cells are still confusing. This work aims to explore the roles of CDK1 in regulating the stemness of lung cancer cells. METHODS Online dataset analysis was performed to evaluate the correlation between CDK1 exression and the survival of lung cancer patients. RT-qPCR, western blot, cell viability, sphere-formation analysis and ALDH activity detection were used to investigate the roles of CDK1 on lung cancer cell stemness, viability and chemotherapeutic sensitivity. Immunocoprecipitation (Co-IP) analysis and rescuing experiments were performed to reveal the underlying mechanisms contributing to CDK1-mediated effects on lung cancer cell stemness. RESULTS CDK1 mRNA expression was negatively correlated with the overall survival of lung cancer patients and remarkably increased in tumor spheres formed by lung cancer cells compared to the parental cells. Additionally, CDK1 positively regulated the stemness of lung cancer cells. Mechanistically, CDK1 could interact with Sox2 protein, but not other stemness markers (Oct4, Nanog and CD133). Furthermore, CDK1 increased the phosphorylation, cytoplasm-nuclear translocation and transcriptional activity of Sox2 protein in lung cancer cells. Moreover, CDK1 positively regulated the stemness of lung cancer cells in a Sox2-dependent manner. Finally, we revealed that inhibition of CDK1 enhanced the chemotherapeutic sensitivity, which was also rescued by Sox2 overexpression. CONCLUSIONS This work reveals a novel CDK1/Sox2 axis responsible for maintaining the stemness of lung cancer cells.
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72
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Kumar V. The Trinity of cGAS, TLR9, and ALRs Guardians of the Cellular Galaxy Against Host-Derived Self-DNA. Front Immunol 2021; 11:624597. [PMID: 33643304 PMCID: PMC7905024 DOI: 10.3389/fimmu.2020.624597] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Accepted: 12/29/2020] [Indexed: 12/15/2022] Open
Abstract
The immune system has evolved to protect the host from the pathogens and allergens surrounding their environment. The immune system develops in such a way to recognize self and non-self and develops self-tolerance against self-proteins, nucleic acids, and other larger molecules. However, the broken immunological self-tolerance leads to the development of autoimmune or autoinflammatory diseases. Pattern-recognition receptors (PRRs) are expressed by immunological cells on their cell membrane and in the cytosol. Different Toll-like receptors (TLRs), Nod-like receptors (NLRs) and absent in melanoma-2 (AIM-2)-like receptors (ALRs) forming inflammasomes in the cytosol, RIG (retinoic acid-inducible gene)-1-like receptors (RLRs), and C-type lectin receptors (CLRs) are some of the PRRs. The DNA-sensing receptor cyclic GMP–AMP synthase (cGAS) is another PRR present in the cytosol and the nucleus. The present review describes the role of ALRs (AIM2), TLR9, and cGAS in recognizing the host cell DNA as a potent damage/danger-associated molecular pattern (DAMP), which moves out to the cytosol from its housing organelles (nucleus and mitochondria). The introduction opens with the concept that the immune system has evolved to recognize pathogens, the idea of horror autotoxicus, and its failure due to the emergence of autoimmune diseases (ADs), and the discovery of PRRs revolutionizing immunology. The second section describes the cGAS-STING signaling pathway mediated cytosolic self-DNA recognition, its evolution, characteristics of self-DNAs activating it, and its role in different inflammatory conditions. The third section describes the role of TLR9 in recognizing self-DNA in the endolysosomes during infections depending on the self-DNA characteristics and various inflammatory diseases. The fourth section discusses about AIM2 (an ALR), which also binds cytosolic self-DNA (with 80–300 base pairs or bp) that inhibits cGAS-STING-dependent type 1 IFN generation but induces inflammation and pyroptosis during different inflammatory conditions. Hence, this trinity of PRRs has evolved to recognize self-DNA as a potential DAMP and comes into action to guard the cellular galaxy. However, their dysregulation proves dangerous to the host and leads to several inflammatory conditions, including sterile-inflammatory conditions autoinflammatory and ADs.
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Affiliation(s)
- Vijay Kumar
- Children's Health Queensland Clinical Unit, School of Clinical Medicine, Faculty of Medicine, Mater Research, University of Queensland, St. Lucia, Brisbane, QLD, Australia.,School of Biomedical Sciences, Faculty of Medicine, University of Queensland, St. Lucia, Brisbane, QLD, Australia
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73
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Zhang F, Yuan Y, Ma F. Function and Regulation of Nuclear DNA Sensors During Viral Infection and Tumorigenesis. Front Immunol 2021; 11:624556. [PMID: 33505405 PMCID: PMC7829187 DOI: 10.3389/fimmu.2020.624556] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Accepted: 11/25/2020] [Indexed: 12/13/2022] Open
Abstract
IFI16, hnRNPA2B1, and nuclear cGAS are nuclear-located DNA sensors that play important roles in initiating host antiviral immunity and modulating tumorigenesis. IFI16 triggers innate antiviral immunity, inflammasome, and suppresses tumorigenesis by recognizing double-stranded DNA (dsDNA), single-stranded DNA (ssDNA), damaged nuclear DNA, or cooperatively interacting with multiple tumor suppressors such as p53 and BRCA1. hnRNPA2B1 initiates interferon (IFN)-α/β production and enhances STING-dependent cytosolic antiviral signaling by directly binding viral dsDNA from invaded viruses and facilitating N6 -methyladenosine (m6A) modification of cGAS, IFI16, and STING mRNAs. Nuclear cGAS is recruited to double-stranded breaks (DSBs), suppresses DNA repair, and promotes tumorigenesis. This review briefly describes the nuclear functions of IFI16, hnRNPA2B1, and cGAS, and summarizes the transcriptional, post-transcriptional, and post-translational regulation of these nuclear DNA sensors.
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Affiliation(s)
- Fan Zhang
- Key Laboratory of Synthetic Biology Regulatory Elements, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.,Suzhou Institute of Systems Medicine, Suzhou, China
| | - Yi Yuan
- Key Laboratory of Synthetic Biology Regulatory Elements, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.,Suzhou Institute of Systems Medicine, Suzhou, China.,Department of Laboratory Medicine, Shanghai Tongji Hospital, School of Medicine of Tongji University, Shanghai, China
| | - Feng Ma
- Key Laboratory of Synthetic Biology Regulatory Elements, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.,Suzhou Institute of Systems Medicine, Suzhou, China
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74
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Balka KR, De Nardo D. Molecular and spatial mechanisms governing STING signalling. FEBS J 2020; 288:5504-5529. [PMID: 33237620 DOI: 10.1111/febs.15640] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 11/12/2020] [Accepted: 11/23/2020] [Indexed: 12/11/2022]
Abstract
Detection of microbial nucleic acids via innate immune receptors is critical for establishing host defence against pathogens. The DNA-sensing cGAS-STING pathway has gained increasing attention in the last decade as a key pathway for combating viral and bacterial infections. cGAS-STING activation primarily promotes the secretion of antiviral type I IFNs via the key transcription factor, IRF3. In addition, cGAS-STING signalling also elicits proinflammatory cytokines through NF-κB activity. Activation of IRF3 and NF-κB is mediated by the chief signalling receptor protein STING. Interestingly, STING undergoes significant trafficking events across multiple subcellular locations, which regulates both the activation of downstream signalling pathways, as well as appropriate termination of the responses. Studies to date have provided a comprehensive view of the regulation and role of the IRF3-IFN pathway downstream of STING. However, many aspects of STING signalling remain relatively poorly defined. This review will explore the current understanding of the mechanisms through which STING elicits inflammatory and antimicrobial responses, focusing on the precise signalling and intracellular trafficking events that occur. We will also discuss exciting and emerging concepts in the field, including the importance of IFN-independent STING responses for host defence and during STING-related disease.
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Affiliation(s)
- Katherine R Balka
- Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Vic., Australia
| | - Dominic De Nardo
- Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Vic., Australia
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75
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Hertzog J, Rehwinkel J. Regulation and inhibition of the DNA sensor cGAS. EMBO Rep 2020; 21:e51345. [PMID: 33155371 PMCID: PMC7726805 DOI: 10.15252/embr.202051345] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 10/01/2020] [Accepted: 10/14/2020] [Indexed: 12/13/2022] Open
Abstract
Cell-autonomous sensing of nucleic acids is essential for host defence against invading pathogens by inducing antiviral and inflammatory cytokines. cGAS has emerged in recent years as a non-redundant DNA sensor important for detection of many viruses and bacteria. Upon binding to DNA, cGAS synthesises the cyclic dinucleotide 2'3'-cGAMP that binds to the adaptor protein STING and thereby triggers IRF3- and NFκB-dependent transcription. In addition to infection, the pathophysiology of an ever-increasing number of sterile inflammatory conditions in humans involves the recognition of DNA through cGAS. Consequently, the cGAS/STING signalling axis has emerged as an attractive target for pharmacological modulation. However, the development of cGAS and STING inhibitors has just begun and a need for specific and effective compounds persists. In this review, we focus on cGAS and explore how its activation by immunostimulatory DNA is regulated by cellular mechanisms, viral immune modulators and small molecules. We further use our knowledge of cGAS modulation by cells and viruses to conceptualise potential new ways of pharmacological cGAS targeting.
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Affiliation(s)
- Jonny Hertzog
- MRC Human Immunology UnitMRC Weatherall Institute of Molecular MedicineRadcliffe Department of MedicineUniversity of OxfordOxfordUK
| | - Jan Rehwinkel
- MRC Human Immunology UnitMRC Weatherall Institute of Molecular MedicineRadcliffe Department of MedicineUniversity of OxfordOxfordUK
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76
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Wu Y, Li S. Role of Post-Translational Modifications of cGAS in Innate Immunity. Int J Mol Sci 2020; 21:ijms21217842. [PMID: 33105828 PMCID: PMC7660100 DOI: 10.3390/ijms21217842] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 10/18/2020] [Accepted: 10/20/2020] [Indexed: 12/23/2022] Open
Abstract
Cyclic GMP–AMP synthase (cGAS) is the synthase that generates the second messenger cyclic GMP–AMP (cGAMP) upon DNA binding. cGAS was first discovered as the cytosolic DNA sensor that detects DNA exposed in the cytoplasm either from pathogens or cellular damage. Activated cGAS instigates the signaling cascades to activate type I interferon (IFN) expression, critical for host defense and autoimmune diseases. In addition, cGAS plays a role in senescence, DNA repair, apoptosis, and tumorigenesis. Recently, various post-translational modifications (PTMs) of cGAS have been reported, such as phosphorylation, ubiquitination, acetylation, glutamylation, and sumoylation. These PTMs profoundly affect cGAS functions. Thus, here we review the recent reported PTMs of cGAS and how these PTMs regulate cGAS enzymatic activity, DNA binding, and protein stability, and discuss the potential future directions.
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Affiliation(s)
| | - Shitao Li
- Correspondence: ; Tel.: +1-504-988-2203
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77
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Kujirai T, Zierhut C, Takizawa Y, Kim R, Negishi L, Uruma N, Hirai S, Funabiki H, Kurumizaka H. Structural basis for the inhibition of cGAS by nucleosomes. Science 2020; 370:455-458. [PMID: 32912999 DOI: 10.1126/science.abd0237] [Citation(s) in RCA: 143] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 08/28/2020] [Indexed: 12/19/2022]
Abstract
The cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS) senses invasion of pathogenic DNA and stimulates inflammatory signaling, autophagy, and apoptosis. Organization of host DNA into nucleosomes was proposed to limit cGAS autoinduction, but the underlying mechanism was unknown. Here, we report the structural basis for this inhibition. In the cryo-electron microscopy structure of the human cGAS-nucleosome core particle (NCP) complex, two cGAS monomers bridge two NCPs by binding the acidic patch of the histone H2A-H2B dimer and nucleosomal DNA. In this configuration, all three known cGAS DNA binding sites, required for cGAS activation, are repurposed or become inaccessible, and cGAS dimerization, another prerequisite for activation, is inhibited. Mutating key residues linking cGAS and the acidic patch alleviates nucleosomal inhibition. This study establishes a structural framework for why cGAS is silenced on chromatinized self-DNA.
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Affiliation(s)
- Tomoya Kujirai
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Christian Zierhut
- Laboratory of Chromosome and Cell Biology, The Rockefeller University, New York, NY 10065, USA
| | - Yoshimasa Takizawa
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Ryan Kim
- Laboratory of Chromosome and Cell Biology, The Rockefeller University, New York, NY 10065, USA
| | - Lumi Negishi
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Nobuki Uruma
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.,Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan
| | - Seiya Hirai
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.,Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Hironori Funabiki
- Laboratory of Chromosome and Cell Biology, The Rockefeller University, New York, NY 10065, USA.
| | - Hitoshi Kurumizaka
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan. .,Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan.,Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
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78
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Uhlorn BL, Gamez ER, Li S, Campos SK. Attenuation of cGAS/STING activity during mitosis. Life Sci Alliance 2020; 3:e201900636. [PMID: 32661021 PMCID: PMC7368095 DOI: 10.26508/lsa.201900636] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 07/08/2020] [Accepted: 07/08/2020] [Indexed: 12/14/2022] Open
Abstract
The innate immune system recognizes cytosolic DNA associated with microbial infections and cellular stress via the cGAS/STING pathway, leading to activation of phospho-IRF3 and downstream IFN-I and senescence responses. To prevent hyperactivation, cGAS/STING is presumed to be nonresponsive to chromosomal self-DNA during open mitosis, although specific regulatory mechanisms are lacking. Given a role for the Golgi in STING activation, we investigated the state of the cGAS/STING pathway in interphase cells with artificially vesiculated Golgi and in cells arrested in mitosis. We find that whereas cGAS activity is impaired through interaction with mitotic chromosomes, Golgi integrity has little effect on the enzyme's production of cGAMP. In contrast, STING activation in response to either foreign DNA (cGAS-dependent) or exogenous cGAMP is impaired by a vesiculated Golgi. Overall, our data suggest a secondary means for cells to limit potentially harmful cGAS/STING responses during open mitosis via natural Golgi vesiculation.
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Affiliation(s)
- Brittany L Uhlorn
- Cancer Biology Graduate Interdisciplinary Program, The University of Arizona, Tucson, AZ, USA
| | - Eduardo R Gamez
- Department of Physiology, The University of Arizona, Tucson, AZ, USA
| | - Shuaizhi Li
- Department of Immunobiology, The University of Arizona, Tucson, AZ, USA
| | - Samuel K Campos
- Cancer Biology Graduate Interdisciplinary Program, The University of Arizona, Tucson, AZ, USA
- Department of Immunobiology, The University of Arizona, Tucson, AZ, USA
- BIO5 Institute, The University of Arizona, Tucson, AZ, USA
- Department of Molecular and Cellular Biology, The University of Arizona, Tucson, AZ, USA
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Zhang X, Bai XC, Chen ZJ. Structures and Mechanisms in the cGAS-STING Innate Immunity Pathway. Immunity 2020; 53:43-53. [PMID: 32668227 DOI: 10.1016/j.immuni.2020.05.013] [Citation(s) in RCA: 339] [Impact Index Per Article: 84.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 05/19/2020] [Accepted: 05/26/2020] [Indexed: 01/29/2023]
Abstract
Besides its role as the blueprint of life, DNA can also alert the cell to the presence of microbial pathogens as well as damaged or malignant cells. A major sensor of DNA that triggers the innate immune response is cyclic guanosine monophosphate (GMP)-adenosine monophosphate (AMP) (cGAMP) synthase (cGAS), which produces the second messenger cGAMP. cGAMP activates stimulator of interferon genes (STING), which activates a signaling cascade leading to the production of type I interferons and other immune mediators. Recent research has demonstrated an expanding role of the cGAS-cGAMP-STING pathway in many physiological and pathological processes, including host defense against microbial infections, anti-tumor immunity, cellular senescence, autophagy, and autoimmune and inflammatory diseases. Biochemical and structural studies have elucidated the mechanism of signal transduction in the cGAS pathway at the atomic resolution. This review focuses on the structural and mechanistic insights into the roles of cGAS and STING in immunity and diseases revealed by these recent studies.
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Affiliation(s)
- Xuewu Zhang
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA.
| | - Xiao-Chen Bai
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
| | - Zhijian J Chen
- Department of Molecular biology, University of Texas Southwestern Medical Center, Dallas, TX, USA; Center for Inflammation Research, University of Texas Southwestern Medical Center, Dallas, TX, USA; Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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