401
|
Chakrabarti A, Banerjee S, Franchi L, Loo YM, Gale M, Núñez G, Silverman RH. RNase L activates the NLRP3 inflammasome during viral infections. Cell Host Microbe 2015; 17:466-77. [PMID: 25816776 DOI: 10.1016/j.chom.2015.02.010] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 01/14/2015] [Accepted: 02/13/2015] [Indexed: 11/25/2022]
Abstract
The NLRP3 inflammasome assembles in response to danger signals, triggering self-cleavage of procaspase-1 and production of the proinflammatory cytokine IL-1β. Although virus infection activates the NLRP3 inflammasome, the underlying events remain incompletely understood. We report that virus activation of the NLRP3 inflammasome involves the 2',5'-oligoadenylate (2-5A) synthetase(OAS)/RNase L system, a component of the interferon-induced antiviral response that senses double-stranded RNA and activates endoribonuclease RNase L to cleave viral and cellular RNAs. The absence of RNase L reduces IL-1β production in influenza A virus-infected mice. RNA cleavage products generated by RNase L enhance IL-1β production but require the presence of 2',3'-cyclic phosphorylated termini characteristic of RNase L activity. Additionally, these cleavage products stimulate NLRP3 complex formation with the DExD/H-box helicase, DHX33, and mitochondrial adaptor protein, MAVS, which are each required for effective NLRP3 inflammasome activation. Thus, RNA cleavage events catalyzed by RNase L are required for optimal inflammasome activation during viral infections.
Collapse
Affiliation(s)
- Arindam Chakrabarti
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Shuvojit Banerjee
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Luigi Franchi
- Department of Pathology and Comprehensive Cancer Center, University of Michigan Medical School, Ann Arbor, MI 48109, USA; Lycera Corporation, Ann Arbor, MI 48109, USA
| | - Yueh-Ming Loo
- Department of Immunology, Center for Innate Immunity and Immune Disease, University of Washington School of Medicine, Seattle, WA 98195, USA
| | - Michael Gale
- Department of Immunology, Center for Innate Immunity and Immune Disease, University of Washington School of Medicine, Seattle, WA 98195, USA
| | - Gabriel Núñez
- Department of Pathology and Comprehensive Cancer Center, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Robert H Silverman
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
| |
Collapse
|
402
|
Innate immune recognition of DNA: A recent history. Virology 2015; 479-480:146-52. [PMID: 25816762 DOI: 10.1016/j.virol.2015.03.013] [Citation(s) in RCA: 174] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 02/14/2015] [Accepted: 03/03/2015] [Indexed: 12/15/2022]
Abstract
Innate immune DNA sensing underpins many physiological and pathological responses to DNA, including anti-viral immunity to DNA viruses. Although it has been appreciated for many years that cytosolic DNA can evoke a type I interferon response, it is only within the past decade that the cellular mechanisms responsible for such a response have been defined. Here we review the discoveries that led to an appreciation of the existence of cytosolic DNA sensor proteins, and discuss two key such sensors, cGAS and IFI16, in detail. DNA sensors operate via STING, a protein shown to have a central role in controlling altered gene induction in response to DNA in vivo, and as such to be central to a rapidly expanding list of both protective and harmful responses to DNA. We also discuss recent insights into how and when DNA stimulates innate immunity, and highlight current outstanding questions in the DNA sensing field.
Collapse
|
403
|
Katsnelson MA, Rucker LG, Russo HM, Dubyak GR. K+ efflux agonists induce NLRP3 inflammasome activation independently of Ca2+ signaling. THE JOURNAL OF IMMUNOLOGY 2015; 194:3937-52. [PMID: 25762778 DOI: 10.4049/jimmunol.1402658] [Citation(s) in RCA: 206] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 02/07/2015] [Indexed: 12/22/2022]
Abstract
Perturbation of intracellular ion homeostasis is a major cellular stress signal for activation of NLRP3 inflammasome signaling that results in caspase-1-mediated production of IL-1β and pyroptosis. However, the relative contributions of decreased cytosolic K(+) concentration versus increased cytosolic Ca(2+) concentration ([Ca(2+)]) remain disputed and incompletely defined. We investigated roles for elevated cytosolic [Ca(2+)] in NLRP3 activation and downstream inflammasome signaling responses in primary murine dendritic cells and macrophages in response to two canonical NLRP3 agonists (ATP and nigericin) that facilitate primary K(+) efflux by mechanistically distinct pathways or the lysosome-destabilizing agonist Leu-Leu-O-methyl ester. The study provides three major findings relevant to this unresolved area of NLRP3 regulation. First, increased cytosolic [Ca(2+)] was neither a necessary nor sufficient signal for the NLRP3 inflammasome cascade during activation by endogenous ATP-gated P2X7 receptor channels, the exogenous bacterial ionophore nigericin, or the lysosomotropic agent Leu-Leu-O-methyl ester. Second, agonists for three Ca(2+)-mobilizing G protein-coupled receptors (formyl peptide receptor, P2Y2 purinergic receptor, and calcium-sensing receptor) expressed in murine dendritic cells were ineffective as activators of rapidly induced NLRP3 signaling when directly compared with the K(+) efflux agonists. Third, the intracellular Ca(2+) buffer, BAPTA, and the channel blocker, 2-aminoethoxydiphenyl borate, widely used reagents for disruption of Ca(2+)-dependent signaling pathways, strongly suppressed nigericin-induced NLRP3 inflammasome signaling via mechanisms dissociated from their canonical or expected effects on Ca(2+) homeostasis. The results indicate that the ability of K(+) efflux agonists to activate NLRP3 inflammasome signaling can be dissociated from changes in cytosolic [Ca(2+)] as a necessary or sufficient signal.
Collapse
Affiliation(s)
| | - L Graham Rucker
- The Ohio State University College of Medicine, Columbus, OH 43210; and
| | - Hana M Russo
- Department of Pathology, Case Western Reserve University, Cleveland, OH 44106
| | - George R Dubyak
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106
| |
Collapse
|
404
|
Lian Z, Qi S, Zhou J, Schmid F. Solvent Determines Nature of Effective Interactions between Nanoparticles in Polymer Brushes. J Phys Chem B 2015; 119:4099-108. [DOI: 10.1021/jp511911g] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Zengju Lian
- Department
of Physics, Ningbo University, Fenghua Road 818, Ningbo 315211, P. R. China
| | - Shuanhu Qi
- Institut
für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg
7, D55099 Mainz, Germany
| | - Jiajia Zhou
- Institut
für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg
7, D55099 Mainz, Germany
| | - Friederike Schmid
- Institut
für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg
7, D55099 Mainz, Germany
| |
Collapse
|
405
|
Fang L, Choudhary S, Tian B, Boldogh I, Yang C, Ivanciuc T, Ma Y, Garofalo RP, Brasier AR. Ataxia telangiectasia mutated kinase mediates NF-κB serine 276 phosphorylation and interferon expression via the IRF7-RIG-I amplification loop in paramyxovirus infection. J Virol 2015; 89:2628-42. [PMID: 25520509 PMCID: PMC4325710 DOI: 10.1128/jvi.02458-14] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Accepted: 12/09/2014] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Respiratory syncytial virus (RSV) is a primary etiological agent of childhood lower respiratory tract disease. Molecular patterns induced by active infection trigger a coordinated retinoic acid-inducible gene I (RIG-I)-Toll-like receptor (TLR) signaling response to induce inflammatory cytokines and antiviral mucosal interferons. Recently, we discovered a nuclear oxidative stress-sensitive pathway mediated by the DNA damage response protein, ataxia telangiectasia mutated (ATM), in cytokine-induced NF-κB/RelA Ser 276 phosphorylation. Here we observe that ATM silencing results in enhanced single-strand RNA (ssRNA) replication of RSVand Sendai virus, due to decreased expression and secretion of type I and III interferons (IFNs), despite maintenance of IFN regulatory factor 3 (IRF3)-dependent IFN-stimulated genes (ISGs). In addition to enhanced oxidative stress, RSV replication enhances foci of phosphorylated histone 2AX variant (γH2AX), Ser 1981 phosphorylation of ATM, and IKKγ/NEMO-dependent ATM nuclear export, indicating activation of the DNA damage response. ATM-deficient cells show defective RSV-induced mitogen and stress-activated kinase 1 (MSK-1) Ser 376 phosphorylation and reduced RelA Ser 276 phosphorylation, whose formation is required for IRF7 expression. We observe that RelA inducibly binds the native IFN regulatory factor 7 (IRF7) promoter in an ATM-dependent manner, and IRF7 inducibly binds to the endogenous retinoic acid-inducible gene I (RIG-I) promoter. Ectopic IRF7 expression restores RIG-I expression and type I/III IFN expression in ATM-silenced cells. We conclude that paramyxoviruses trigger the DNA damage response, a pathway required for MSK1 activation of phospho Ser 276 RelA formation to trigger the IRF7-RIG-I amplification loop necessary for mucosal IFN production. These data provide the molecular pathogenesis for defects in the cellular innate immunity of patients with homozygous ATM mutations. IMPORTANCE RNA virus infections trigger cellular response pathways to limit spread to adjacent tissues. This "innate immune response" is mediated by germ line-encoded pattern recognition receptors that trigger activation of two, largely independent, intracellular NF-κB and IRF3 transcription factors. Downstream, expression of protective antiviral interferons is amplified by positive-feedback loops mediated by inducible interferon regulatory factors (IRFs) and retinoic acid inducible gene (RIG-I). Our results indicate that a nuclear oxidative stress- and DNA damage-sensing factor, ATM, is required to mediate a cross talk pathway between NF-κB and IRF7 through mediating phosphorylation of NF-κB. Our studies provide further information about the defects in cellular and innate immunity in patients with inherited ATM mutations.
Collapse
Affiliation(s)
- Ling Fang
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Sanjeev Choudhary
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas, USA Sealy Center for Molecular Medicine, University of Texas Medical Branch, Galveston, Texas, USA Institute for Translational Sciences, University of Texas Medical Branch, Galveston, Texas, USA
| | - Bing Tian
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas, USA Sealy Center for Molecular Medicine, University of Texas Medical Branch, Galveston, Texas, USA Institute for Translational Sciences, University of Texas Medical Branch, Galveston, Texas, USA
| | - Istvan Boldogh
- Sealy Center for Molecular Medicine, University of Texas Medical Branch, Galveston, Texas, USA Institute for Translational Sciences, University of Texas Medical Branch, Galveston, Texas, USA Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Chunying Yang
- Department of Radiation Oncology, Houston Methodist Research Institute, Weill Cornell University, Houston, Texas, USA
| | - Teodora Ivanciuc
- Department of Pediatrics, University of Texas Medical Branch, Galveston, Texas, USA
| | - Yinghong Ma
- Department of Pediatrics, University of Texas Medical Branch, Galveston, Texas, USA
| | - Roberto P Garofalo
- Sealy Center for Molecular Medicine, University of Texas Medical Branch, Galveston, Texas, USA Institute for Translational Sciences, University of Texas Medical Branch, Galveston, Texas, USA Department of Pediatrics, University of Texas Medical Branch, Galveston, Texas, USA
| | - Allan R Brasier
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas, USA Sealy Center for Molecular Medicine, University of Texas Medical Branch, Galveston, Texas, USA Institute for Translational Sciences, University of Texas Medical Branch, Galveston, Texas, USA
| |
Collapse
|
406
|
Daskalov A, Habenstein B, Martinez D, Debets AJM, Sabaté R, Loquet A, Saupe SJ. Signal transduction by a fungal NOD-like receptor based on propagation of a prion amyloid fold. PLoS Biol 2015; 13:e1002059. [PMID: 25671553 PMCID: PMC4344463 DOI: 10.1371/journal.pbio.1002059] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 12/29/2014] [Indexed: 01/09/2023] Open
Abstract
In the fungus Podospora anserina, the [Het-s] prion induces programmed cell death by activating the HET-S pore-forming protein. The HET-s β-solenoid prion fold serves as a template for converting the HET-S prion-forming domain into the same fold. This conversion, in turn, activates the HET-S pore-forming domain. The gene immediately adjacent to het-S encodes NWD2, a Nod-like receptor (NLR) with an N-terminal motif similar to the elementary repeat unit of the β-solenoid fold. NLRs are immune receptors controlling cell death and host defense processes in animals, plants and fungi. We have proposed that, analogously to [Het-s], NWD2 can activate the HET-S pore-forming protein by converting its prion-forming region into the β-solenoid fold. Here, we analyze the ability of NWD2 to induce formation of the β-solenoid prion fold. We show that artificial NWD2 variants induce formation of the [Het-s] prion, specifically in presence of their cognate ligands. The N-terminal motif is responsible for this prion induction, and mutations predicted to affect the β-solenoid fold abolish templating activity. In vitro, the N-terminal motif assembles into infectious prion amyloids that display a structure resembling the β-solenoid fold. In vivo, the assembled form of the NWD2 N-terminal region activates the HET-S pore-forming protein. This study documenting the role of the β-solenoid fold in fungal NLR function further highlights the general importance of amyloid and prion-like signaling in immunity-related cell fate pathways. The fungus Podospora anserina uses a prion amyloid fold as a signal transduction device between a Nod-like receptor and a downstream cell death execution protein. Although amyloids are best known as protein aggregates that are responsible for fatal neurodegenerative diseases, amyloid structures can also fulfill functional roles in cells. In particular, the controlled formation of amyloid structures appears to be involved in different signaling processes in the context of programmed cell death and host defense. The [Het-s] prion of the filamentous fungus Podospora anserina is a model system in which the 3-D structure of the prion form has been solved. The [Het-s] prion works as an activation switch for a second protein termed HET-S. HET-S is a pore-forming protein that is activated when the [Het-s] prion causes its C-terminal domain to adopt an amyloid-like fold. The protein encoded by the gene adjacent to het-S is a Nod-like receptor (NLR) called NWD2. NLRs are immune receptors that control host defense and cell death processes in plants, animals, and fungi. We show that NWD2 can template the formation of the [Het-s] prion fold in a ligand-controlled manner. NWD2 has an N-terminal motif homologous to the HET-S/s prion-forming region; we find that this region is both necessary and sufficient for its prion-inducing activity, and our functional and structural approaches reveal that the N-terminal region of NWD2 adopts a fold closely related to that of the HET-S/s prion. This study illustrates how the controlled formation of a prion amyloid fold can be used in a signaling process whereby a Nod-like receptor protein activates a downstream cell death execution domain.
Collapse
Affiliation(s)
- Asen Daskalov
- Non-self recognition in Fungi, Institut de Biochimie et de Génétique Cellulaire, UMR 5095, CNRS—Université de Bordeaux, Bordeaux, France
| | - Birgit Habenstein
- Institute of Chemistry & Biology of Membranes & Nanoobjects, CNRS, CBMN, UMR 5248, Pessac, France
| | - Denis Martinez
- Institute of Chemistry & Biology of Membranes & Nanoobjects, CNRS, CBMN, UMR 5248, Pessac, France
| | - Alfons J. M. Debets
- Laboratory of Genetics, Wageningen University, Droevendaalsesteeg, Wageningen, The Netherlands
| | - Raimon Sabaté
- Institut de Nanociència i nanotecnologia, Departament Fisicoquímica, Universitat de Barcelona, Joan XXIII s/n, Barcelona, Spain
| | - Antoine Loquet
- Institute of Chemistry & Biology of Membranes & Nanoobjects, CNRS, CBMN, UMR 5248, Pessac, France
| | - Sven J. Saupe
- Non-self recognition in Fungi, Institut de Biochimie et de Génétique Cellulaire, UMR 5095, CNRS—Université de Bordeaux, Bordeaux, France
- * E-mail:
| |
Collapse
|
407
|
Mechanisms of inflammasome activation: recent advances and novel insights. Trends Cell Biol 2015; 25:308-15. [PMID: 25639489 DOI: 10.1016/j.tcb.2014.12.009] [Citation(s) in RCA: 378] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Revised: 12/22/2014] [Accepted: 12/22/2014] [Indexed: 01/04/2023]
Abstract
Inflammasomes are cytosolic multiprotein platforms assembled in response to invading pathogens and other danger signals. Typically inflammasome complexes contain a sensor protein, an adaptor protein, and a zymogen - procaspase-1. Formation of inflammasome assembly results in processing of inactive procaspase-1 into an active cysteine-protease enzyme, caspase-1, which subsequently activates the proinflammatory cytokines, interleukins IL-1β and IL-18, and induces pyroptosis, a highly-pyrogenic inflammatory form of cell death. Studies over the past year have unveiled exciting new players and regulatory pathways that are involved in traditional inflammasome signaling, some of them even challenging the existing dogma. This review outlines these new insights in inflammasome research and discusses areas that warrant further exploration.
Collapse
|
408
|
Abstract
Innate immune responses depend on timely recognition of pathogenic or danger signals by multiple cell surface or cytoplasmic receptors and transmission of signals for proper counteractions through adaptor and effector molecules. At the forefront of innate immunity are four major signaling pathways, including those elicited by Toll-like receptors, RIG-I-like receptors, inflammasomes, or cGAS, each with its own cellular localization, ligand specificity, and signal relay mechanism. They collectively engage a number of overlapping signaling outcomes, such as NF-κB activation, interferon response, cytokine maturation, and cell death. Several proteins often assemble into a supramolecular complex to enable signal transduction and amplification. In this article, we review the recent progress in mechanistic delineation of proteins in these pathways, their structural features, modes of ligand recognition, conformational changes, and homo- and hetero-oligomeric interactions within the supramolecular complexes. Regardless of seemingly distinct interactions and mechanisms, the recurring themes appear to consist of autoinhibited resting-state receptors, ligand-induced conformational changes, and higher-order assemblies of activated receptors, adaptors, and signaling enzymes through conserved protein-protein interactions.
Collapse
Affiliation(s)
- Qian Yin
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, and
| | | | | | | |
Collapse
|
409
|
NLRP3 Inflammasome and Pathobiology in AMD. J Clin Med 2015; 4:172-92. [PMID: 26237026 PMCID: PMC4470247 DOI: 10.3390/jcm4010172] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 12/19/2014] [Indexed: 02/07/2023] Open
Abstract
Age-related macular degeneration (AMD) is the leading cause of central vision loss and blindness in the elderly. It is characterized by a progressive loss of photoreceptors in the macula due to damage to the retinal pigment epithelium (RPE). Clinically, it is manifested by drusen deposition between the RPE and underlying choroid and accumulation of lipofuscin in the RPE. End-stage disease is characterized by geographic atrophy (dry AMD) or choroidal neovascularization (wet AMD). The NLRP3 inflammasome has recently been implicated in the disease pathology. Here we review the current knowledge on the involvement of this multiprotein complex and its effector cytokines interleukin-1β (IL-1β) and IL-18 in AMD progression. We also describe cell death mechanisms that have been proposed to underlie RPE degeneration in AMD and discuss the role of autophagy in the regulation of disease progression.
Collapse
|
410
|
Smith C, Wang X, Yin H. Caspases come together over LPS. Trends Immunol 2015; 36:59-61. [PMID: 25573609 DOI: 10.1016/j.it.2014.12.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 12/03/2014] [Accepted: 12/23/2014] [Indexed: 11/16/2022]
Abstract
Caspases are cellular executors, initiating cell death. In a recent study, Shi et al. report that caspases 4/5/11 are cytosolic LPS receptors, becoming activated through oligomerization upon interaction with LPS. These findings shed new light on the mechanisms underlying caspase-mediated pyroptosis, and have implications for the development of effective drugs to treat sepsis.
Collapse
Affiliation(s)
- Christina Smith
- Department of Chemistry & Biochemistry and the BioFrontiers Institute, University of Colorado Boulder, 596 UCB, Boulder, CO 80309-0596, USA
| | - Xiaohui Wang
- Department of Chemistry & Biochemistry and the BioFrontiers Institute, University of Colorado Boulder, 596 UCB, Boulder, CO 80309-0596, USA; Chemical Biology Laboratory, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, 130022, China
| | - Hang Yin
- Department of Chemistry & Biochemistry and the BioFrontiers Institute, University of Colorado Boulder, 596 UCB, Boulder, CO 80309-0596, USA; Center of Basic Molecular Science and Department of Chemistry, Tsinghua University, Beijing, 100082, China.
| |
Collapse
|
411
|
Daskalov A, Saupe SJ. As a toxin dies a prion comes to life: A tentative natural history of the [Het-s] prion. Prion 2015; 9:184-9. [PMID: 26110610 PMCID: PMC4601334 DOI: 10.1080/19336896.2015.1038018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 03/25/2015] [Accepted: 03/28/2015] [Indexed: 01/20/2023] Open
Abstract
A variety of signaling pathways, in particular with roles in cell fate and host defense, operate by a prion-like mechanism consisting in the formation of open-ended oligomeric signaling complexes termed signalosomes. This mechanism emerges as a novel paradigm in signal transduction. Among the proteins forming such signaling complexes are the Nod-like receptors (NLR), involved in innate immunity. It now appears that the [Het-s] fungal prion derives from such a cell-fate defining signaling system controlled by a fungal NLR. What was once considered as an isolated oddity turns out to be related to a conserved and widespread signaling mechanism. Herein, we recall the relation of the [Het-s] prion to the signal transduction pathway controlled by the NWD2 Nod-like receptor, leading to activation of the HET-S pore-forming cell death execution protein. We explicit an evolutionary scenario in which formation of the [Het-s] prion is the result of an exaptation process or how a loss-of-function mutation in a pore-forming cell death execution protein (HET-S) has given birth to a functional prion ([Het-s]).
Collapse
Affiliation(s)
- Asen Daskalov
- Non-self recognition in Fungi; Institut de Biochimie et de Génétique Cellulaire; UMR 5095; CNRS - Université de Bordeaux; Bordeaux cedex, France
| | - Sven J Saupe
- Non-self recognition in Fungi; Institut de Biochimie et de Génétique Cellulaire; UMR 5095; CNRS - Université de Bordeaux; Bordeaux cedex, France
| |
Collapse
|
412
|
Compan V, Martín-Sánchez F, Baroja-Mazo A, López-Castejón G, Gomez AI, Verkhratsky A, Brough D, Pelegrín P. Apoptosis-associated speck-like protein containing a CARD forms specks but does not activate caspase-1 in the absence of NLRP3 during macrophage swelling. THE JOURNAL OF IMMUNOLOGY 2014; 194:1261-73. [PMID: 25552542 DOI: 10.4049/jimmunol.1301676] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain (ASC) is a key adaptor molecule required for the inflammatory processes. ASC acts by bridging NLRP proteins, such as NLRP3, with procaspase-1 within the inflammasome complex, which subsequently results in the activation of caspase-1 and the secretion of IL-1β and IL-18. In response to bacterial infection, ASC also forms specks by self-oligomerization to activate caspase-1 and induce pyroptosis. Hitherto, the role of these specks in NLRP3 inflammasome activation in response to danger signals, such as a hypotonic environment, largely has been unexplored. In this article, we report that, under hypotonic conditions and independently of NLRP3, ASC was able to form specks that did not activate caspase-1. These specks were not associated with pyroptosis and were controlled by transient receptor potential vanilloid 2 channel-mediated signaling. However, interaction with NLRP3 enhanced ASC speck formation, leading to fully functional inflammasomes and caspase-1 activation. This study reveals that the ASC speck can present different oligomerization assemblies and represents an essential step in the activation of functional NLRP3 inflammasomes.
Collapse
Affiliation(s)
- Vincent Compan
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom; and
| | - Fátima Martín-Sánchez
- Unidad de Inflamación y Cirugía Experimental, Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas, Hospital Clínico Universitario Virgen de la Arrixaca, Instituto Murciano de Investigación Biosanitaria-Arrixaca, 30120 Murcia, Spain
| | - Alberto Baroja-Mazo
- Unidad de Inflamación y Cirugía Experimental, Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas, Hospital Clínico Universitario Virgen de la Arrixaca, Instituto Murciano de Investigación Biosanitaria-Arrixaca, 30120 Murcia, Spain
| | - Gloria López-Castejón
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom; and
| | - Ana I Gomez
- Unidad de Inflamación y Cirugía Experimental, Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas, Hospital Clínico Universitario Virgen de la Arrixaca, Instituto Murciano de Investigación Biosanitaria-Arrixaca, 30120 Murcia, Spain
| | - Alexei Verkhratsky
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom; and
| | - David Brough
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom; and
| | - Pablo Pelegrín
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom; and Unidad de Inflamación y Cirugía Experimental, Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas, Hospital Clínico Universitario Virgen de la Arrixaca, Instituto Murciano de Investigación Biosanitaria-Arrixaca, 30120 Murcia, Spain
| |
Collapse
|
413
|
Abstract
Cell proliferation and cell death are integral elements in maintaining homeostatic balance in metazoans. Disease pathologies ensue when these processes are disturbed. A plethora of evidence indicates that malfunction of cell death can lead to inflammation, autoimmunity, or immunodeficiency. Programmed necrosis or necroptosis is a form of nonapoptotic cell death driven by the receptor interacting protein kinase 3 (RIPK3) and its substrate, mixed lineage kinase domain-like (MLKL). RIPK3 partners with its upstream adaptors RIPK1, TRIF, or DAI to signal for necroptosis in response to death receptor or Toll-like receptor stimulation, pathogen infection, or sterile cell injury. Necroptosis promotes inflammation through leakage of cellular contents from damaged plasma membranes. Intriguingly, many of the signal adaptors of necroptosis have dual functions in innate immune signaling. This unique signature illustrates the cooperative nature of necroptosis and innate inflammatory signaling pathways in managing cell and organismal stresses from pathogen infection and sterile tissue injury.
Collapse
Affiliation(s)
- Francis Ka-Ming Chan
- Department of Pathology, Immunology and Microbiology Program, University of Massachusetts Medical School, Worcester, Massachusetts 01605;
| | | | | |
Collapse
|
414
|
Liebert A, Bicknell B, Adams R. Prion Protein Signaling in the Nervous System—A Review and Perspective. ACTA ACUST UNITED AC 2014. [DOI: 10.4137/sti.s12319] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Prion protein (PrPC) was originally known as the causative agent of transmissible spongiform encephalopathy (TSE) but with recent research, its true function in cells is becoming clearer. It is known to act as a scaffolding protein, binding multiple ligands at the cell membrane and to be involved in signal transduction, passing information from the extracellular matrix (ECM) to the cytoplasm. Its role in the coordination of transmitters at the synapse, glyapse, and gap junction and in short- and long-range neurotrophic signaling gives PrPC a major part in neural transmission and nervous system signaling. It acts to regulate cellular function in multiple targets through its role as a controller of redox status and calcium ion flux. Given the importance of PrPC in cell physiology, this review considers its potential role in disease apart from TSE. The putative functions of PrPC point to involvement in neurodegenerative disease, neuropathic pain, chronic headache, and inflammatory disease including neuroinflammatory disease of the nervous system. Potential targets for the treatment of disease influenced by PrPC are discussed.
Collapse
Affiliation(s)
- Ann Liebert
- Faculty of Health Science, University of Sydney, Australia
| | - Brian Bicknell
- Faculty of Health Science, Australian Catholic University, Australia
| | | |
Collapse
|
415
|
Kagan JC, Magupalli VG, Wu H. SMOCs: supramolecular organizing centres that control innate immunity. Nat Rev Immunol 2014; 14:821-6. [PMID: 25359439 PMCID: PMC4373346 DOI: 10.1038/nri3757] [Citation(s) in RCA: 200] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The diverse receptor families of the innate immune system activate signal transduction pathways that are important for host defence, but common themes to explain the operation of these pathways remain undefined. In this Opinion article, we propose--on the basis of recent structural and cell biological studies--the concept of supramolecular organizing centres (SMOCs) as location-specific higher-order signalling complexes in which increased local concentrations of signalling components promote the intrinsically weak allosteric interactions that are required for enzyme activation. We suggest that SMOCs are assembled on various membrane-bound organelles or other intracellular sites, which may assist signal amplification to reach a response threshold and potentially define the specificity of cellular responses that are induced in response to infectious and non-infectious insults.
Collapse
Affiliation(s)
- Jonathan C Kagan
- Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02446, USA
| | - Venkat Giri Magupalli
- Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02446, USA
| | - Hao Wu
- Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02446, USA
| |
Collapse
|
416
|
Abstract
Pattern recognition receptors are essential mediators of host defense and inflammation in the gastrointestinal system. Recent data have revealed that toll-like receptors and nucleotide-binding domain and leucine-rich repeat-containing proteins (NLRs) function to maintain homeostasis between the host microbiome and mucosal immunity. The NLR proteins are a diverse class of cytoplasmic pattern recognition receptors. In humans, only about half of the identified NLRs have been adequately characterized. The majority of well-characterized NLRs participate in the formation of a multiprotein complex, termed the inflammasome, which is responsible for the maturation of interleukin-1β and interleukin-18. However, recent observations have also uncovered the presence of a novel subgroup of NLRs that function as positive or negative regulators of inflammation through modulating critical signaling pathways, including NF-κB. Dysregulation of specific NLRs from both proinflammatory and inhibitory subgroups have been associated with the development of inflammatory bowel disease (IBD) in genetically susceptible human populations. Our own preliminary retrospective data mining efforts have identified a diverse range of NLRs that are significantly altered at the messenger RNA level in colons from patients with IBD. Likewise, studies using genetically modified mouse strains have revealed that multiple NLR family members have the potential to dramatically modulate the immune response during IBD. Targeting NLR signaling represents a promising and novel therapeutic strategy. However, significant effort is necessary to translate the current understanding of NLR biology into effective therapies.
Collapse
|
417
|
Trendelenburg G. Molecular regulation of cell fate in cerebral ischemia: role of the inflammasome and connected pathways. J Cereb Blood Flow Metab 2014; 34:1857-67. [PMID: 25227604 PMCID: PMC4269743 DOI: 10.1038/jcbfm.2014.159] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 08/13/2014] [Accepted: 08/25/2014] [Indexed: 12/19/2022]
Abstract
Analogous to Toll-like receptors, NOD-like receptors represent a class of pattern recognition receptors, which are cytosolic and constitute part of different inflammasomes. These large protein complexes are activated not only by different pathogens, but also by sterile inflammation or by specific metabolic conditions. Mutations can cause hereditary autoinflammatory systemic diseases, and inflammasome activation has been linked to many multifactorial diseases, such as diabetes or cardiovascular diseases. Increasing data also support an important role in different central nervous diseases such as stroke. Thus, the current knowledge of the functional role of this intracellular 'master switch' of inflammation is discussed with a focus on its role in ischemic stroke, neurodegeneration, and also with regard to the recent data which argues for a relevant role in other organs or biologic systems which influence stroke incidence or prognosis.
Collapse
Affiliation(s)
- George Trendelenburg
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| |
Collapse
|
418
|
|
419
|
Lu A, Wu H. Structural mechanisms of inflammasome assembly. FEBS J 2014; 282:435-44. [PMID: 25354325 DOI: 10.1111/febs.13133] [Citation(s) in RCA: 159] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2014] [Revised: 10/14/2014] [Accepted: 10/24/2014] [Indexed: 01/20/2023]
Abstract
Inflammasomes are supramolecular signaling complexes that activate a subset of caspases known as the inflammatory caspases, an example of which is caspase 1. Upon stimulation by microbial and damage-associated signals, inflammasomes assemble to elicit the first line of host defense via the proteolytic maturation of cytokines interleukin-1β and interleukin-18, and by induction of pyroptotic cell death. Inflammasome assembly requires activation of an upstream sensor, a downstream effector and, in most cases, an adaptor molecule such as apoptosis-associate speck-like protein containing a caspase recruitment domain (ASC). Depending on whether ASC is required, inflammasomes can be categorized into ASC-dependent and ASC-independent inflammasomes. Here, we review current understandings of the structures of inflammasomes, as probed using traditional structural methods, as well as biochemical, biophysical and single-molecule methods. The key structural scaffold for inflammasome assembly is composed of filaments of Pyrin domains and caspase recruitment domains (CARD) in the sensor, adaptor and effector components. Nucleated polymerization appears to govern the ordered assembly process from activation of a Pyrin domain-containing sensor such as AIM2 by dsDNA or NLRP3 by extracellular particulates, to recruitment of the Pyrin domain and CARD-containing adaptor ASC, and finally to activation of CARD-containing caspase 1. The underlying filamentous architecture of inflammasomes and the cooperativity in the assembly may explain the 'all-or-none' response in inflammasome activation. Inflammasomes are tightly regulated by a number of cytosolic inhibitors, which may change the morphology and assembly kinetics of inflammasomes. Biochemical and cellular studies suggest that Pyrin domain and CARD filaments possess prion-like properties in propagating inflammasome activation within and between cells.
Collapse
Affiliation(s)
- Alvin Lu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Cambridge, MA, USA; Chemical Biology PhD Program, Harvard University, Cambridge, MA, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
| | | |
Collapse
|
420
|
Broderick L, De Nardo D, Franklin BS, Hoffman HM, Latz E. The inflammasomes and autoinflammatory syndromes. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2014; 10:395-424. [PMID: 25423351 DOI: 10.1146/annurev-pathol-012414-040431] [Citation(s) in RCA: 220] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Inflammation, a vital response of the immune system to infection and damage to tissues, can be initiated by various germline-encoded innate immune-signaling receptors. Among these, the inflammasomes are critical for activation of the potent proinflammatory interleukin-1 cytokine family. Additionally, inflammasomes can trigger and maintain inflammatory responses aimed toward excess nutrients and the numerous danger signals that appear in a variety of chronic inflammatory diseases. We discuss our understanding of how inflammasomes assemble to trigger caspase-1 activation and subsequent cytokine release, describe how genetic mutations in inflammasome-related genes lead to autoinflammatory syndromes, and review the contribution of inflammasome activation to various pathologies arising from metabolic dysfunction. Insights into the mechanisms that govern inflammasome activation will help in the development of novel therapeutic strategies, not only for managing genetic diseases associated with overactive inflammasomes, but also for treating common metabolic diseases for which effective therapies are currently lacking.
Collapse
|
421
|
Caspase-1 autoproteolysis is differentially required for NLRP1b and NLRP3 inflammasome function. Proc Natl Acad Sci U S A 2014; 111:17254-9. [PMID: 25404286 DOI: 10.1073/pnas.1415756111] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Inflammasomes are caspase-1-activating multiprotein complexes. The mouse nucleotide-binding domain and leucine rich repeat pyrin containing 1b (NLRP1b) inflammasome was identified as the sensor of Bacillus anthracis lethal toxin (LT) in mouse macrophages from sensitive strains such as BALB/c. Upon exposure to LT, the NLRP1b inflammasome activates caspase-1 to produce mature IL-1β and induce pyroptosis. Both processes are believed to depend on autoproteolysed caspase-1. In contrast to human NLRP1, mouse NLRP1b lacks an N-terminal pyrin domain (PYD), indicating that the assembly of the NLRP1b inflammasome does not require the adaptor apoptosis-associated speck-like protein containing a CARD (ASC). LT-induced NLRP1b inflammasome activation was shown to be impaired upon inhibition of potassium efflux, which is known to play a major role in NLRP3 inflammasome formation and ASC dimerization. We investigated whether NLRP3 and/or ASC were required for caspase-1 activation upon LT stimulation in the BALB/c background. The NLRP1b inflammasome activation was assessed in both macrophages and dendritic cells lacking either ASC or NLRP3. Upon LT treatment, the absence of NLRP3 did not alter the NLRP1b inflammasome activity. Surprisingly, the absence of ASC resulted in IL-1β cleavage and pyroptosis, despite the absence of caspase-1 autoprocessing activity. By reconstituting caspase-1/caspase-11(-/-) cells with a noncleavable or catalytically inactive mutant version of caspase-1, we directly demonstrated that noncleavable caspase-1 is fully active in response to the NLRP1b activator LT, whereas it is nonfunctional in response to the NLRP3 activator nigericin. Taken together, these results establish variable requirements for caspase-1 cleavage depending on the pathogen and the responding NLR.
Collapse
|
422
|
Antimicrobial inflammasomes: unified signalling against diverse bacterial pathogens. Curr Opin Microbiol 2014; 23:32-41. [PMID: 25461570 DOI: 10.1016/j.mib.2014.10.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 10/14/2014] [Accepted: 10/24/2014] [Indexed: 01/17/2023]
Abstract
Inflammasomes - molecular platforms for caspase-1 activation - have emerged as common hubs for a number of pathways that detect and respond to bacterial pathogens. Caspase-1 activation results in the secretion of bioactive IL-1β and IL-18 and pyroptosis, and thus launches a systemic immune and inflammatory response. In this review we discuss signal transduction leading to 'canonical' and 'non-canonical' activation of caspase-1 through the involvement of upstream caspases. Recent studies have identified a growing number of regulatory networks involving guanylate binding proteins, protein kinases, ubiquitylation and necroptosis related pathways that modulate inflammasome responses and immunity to bacterial infection. By being able to respond to extracellular, vacuolar and cytosolic bacteria, their cytosolic toxins or ligands for cell surface receptors, inflammasomes have emerged as important sentinels of infection.
Collapse
|
423
|
Dyrka W, Lamacchia M, Durrens P, Kobe B, Daskalov A, Paoletti M, Sherman DJ, Saupe SJ. Diversity and variability of NOD-like receptors in fungi. Genome Biol Evol 2014; 6:3137-58. [PMID: 25398782 PMCID: PMC4986451 DOI: 10.1093/gbe/evu251] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) are intracellular receptors that control innate immunity and other biotic interactions in animals and plants. NLRs have been characterized in plant and animal lineages, but in fungi, this gene family has not been systematically described. There is however previous indications of the involvement of NLR-like genes in nonself recognition and programmed cell death in fungi. We have analyzed 198 fungal genomes for the presence of NLRs and have annotated a total of 5,616 NLR candidates. We describe their phylogenetic distribution, domain organization, and evolution. Fungal NLRs are characterized by a great diversity of domain organizations, suggesting frequently occurring combinatorial assortments of different effector, NOD and repeat domains. The repeat domains are of the WD, ANK, and TPR type; no LRR motifs were found. As previously documented for WD-repeat domains of fungal NLRs, TPR, and ANK repeats evolve under positive selection and show highly conserved repeats and repeat length polymorphism, suggesting the possibility of concerted evolution of these repeats. We identify novel effector domains not previously found associated with NLRs, whereas others are related to effector domains of plant or animals NLRs. In particular, we show that the HET domain found in fungal NLRs may be related to Toll/interleukin-1 receptor domains found in animal and plant immune receptors. This description of fungal NLR repertoires reveals both similarities and differences with plant and animals NLR collections, highlights the importance of domain reassortment and repeat evolution and provides a novel entry point to explore the evolution of NLRs in eukaryotes.
Collapse
Affiliation(s)
- Witold Dyrka
- INRIA-Université Bordeaux-CNRS, MAGNOME, Talence, France
| | - Marina Lamacchia
- Institut de Biochimie et de Génétique Cellulaire, UMR 5095, CNRS-Université de Bordeaux, France
| | - Pascal Durrens
- INRIA-Université Bordeaux-CNRS, MAGNOME, Talence, France
| | - Bostjan Kobe
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Centre for Infectious Disease Research, University of Queensland, Brisbane, Queensland, Australia
| | - Asen Daskalov
- Institut de Biochimie et de Génétique Cellulaire, UMR 5095, CNRS-Université de Bordeaux, France
| | - Matthieu Paoletti
- Institut de Biochimie et de Génétique Cellulaire, UMR 5095, CNRS-Université de Bordeaux, France
| | | | - Sven J Saupe
- Institut de Biochimie et de Génétique Cellulaire, UMR 5095, CNRS-Université de Bordeaux, France
| |
Collapse
|
424
|
Cai X, Chen ZJ. Prion-like polymerization as a signaling mechanism. Trends Immunol 2014; 35:622-630. [PMID: 25457352 DOI: 10.1016/j.it.2014.10.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 10/14/2014] [Accepted: 10/15/2014] [Indexed: 12/25/2022]
Abstract
The innate immune system uses pattern recognition receptors such as RIG-I and NLRP3 to sense pathogen invasion and other danger signals. Activation of these receptors induces robust signal transduction cascades that trigger the production of cytokines important for host protection. MAVS and ASC are essential adaptor proteins downstream of RIG-I and NLRP3, respectively, and both contain N-terminal domains belonging to the death domain superfamily. Recent studies suggest that both MAVS and ASC form functional prion-like fibers through their respective death domains to propagate downstream signaling. Here, we review these findings, and in this context discuss the emerging concept of prion-like polymerization in signal transduction. We further examine the potential benefits of this signaling strategy, including signal amplification, host evolutionary advantage, and molecular memory.
Collapse
Affiliation(s)
- Xin Cai
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148, USA.
| | - Zhijian J Chen
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148, USA; Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148, USA.
| |
Collapse
|
425
|
Sahillioglu AC, Sumbul F, Ozoren N, Haliloglu T. Structural and dynamics aspects of ASC speck assembly. Structure 2014; 22:1722-1734. [PMID: 25458835 DOI: 10.1016/j.str.2014.09.011] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 09/17/2014] [Accepted: 09/17/2014] [Indexed: 10/24/2022]
Abstract
Activation of the inflammasome is accompanied by rapid formation of a micrometer-sized perinuclear structure called the ASC speck, a platform for caspase-1 activity. The ASC speck is often referred to as an aggregate and shares certain features with aggresomes. It is thus an open question whether the ASC speck formation takes place via nonspecific aggregation of hydrophobic patches or specific interactions of its domains; PYD and CARD, which belong to the death fold superfamily. Bringing together structure and dynamics studies using the Gaussian network model of PYD and CARD, and molecular dynamics simulations of the wild-type and in silico mutated PYD, with the mutational analysis on the ASC structure and its separate domains in human cells, we show that the ASC speck is an organized structure with at least two levels of distinct compaction mechanisms based on the specific interactions of PYD and CARD.
Collapse
Affiliation(s)
- Ali Can Sahillioglu
- Department of Molecular Biology and Genetics, Apoptosis and Cancer Immunology Laboratory (AKIL), Bogazici University, 34470 Istanbul, Turkey
| | - Fidan Sumbul
- Department of Chemical Engineering and Polymer Research Center, Bogazici University, 34470 Istanbul, Turkey
| | - Nesrin Ozoren
- Department of Molecular Biology and Genetics, Apoptosis and Cancer Immunology Laboratory (AKIL), Bogazici University, 34470 Istanbul, Turkey; Center for Life Sciences and Technologies, Bogazici University, 34470 Istanbul, Turkey.
| | - Turkan Haliloglu
- Department of Chemical Engineering and Polymer Research Center, Bogazici University, 34470 Istanbul, Turkey; Center for Life Sciences and Technologies, Bogazici University, 34470 Istanbul, Turkey.
| |
Collapse
|
426
|
Abstract
A new study (Wu et al., 2014) employs X-ray crystallography and cryoelectron microscopy (cryo-EM) to reveal how the caspase activation and recruitment domains (CARDs) of the cytosolic viral RNA sensor RIG-I nucleate the formation of large CARD filaments of the mitochondrial antiviral signaling protein MAVS to trigger the antiviral innate immune response.
Collapse
Affiliation(s)
- Karl-Peter Hopfner
- Department Biochemistry, Gene Center, Ludwig-Maximilians University, Feodor-Lynen-Strasse 25, 81377 Munich, Germany; Center for Integrated Protein Sciences, Gene Center, Ludwig-Maximilians University, Feodor-Lynen-Strasse 25, 81377 Munich, Germany; Graduate School for Quantitative Biosciences, Gene Center, Ludwig-Maximilians University, Feodor-Lynen-Strasse 25, 81377 Munich, Germany.
| |
Collapse
|
427
|
Affiliation(s)
- Lori Broderick
- Department of Pediatrics, University of California, La Jolla, San Diego, California, USA, and Rady Children's Hospital San Diego, San Diego, California, USA
| | - Hal M Hoffman
- Department of Pediatrics, University of California, La Jolla, San Diego, California, USA, the Department of Medicine, University of California, La Jolla, San Diego, California, USA, and Rady Children's Hospital San Diego, San Diego, California, USA
| |
Collapse
|
428
|
Ding S, Robek MD. Peroxisomal MAVS activates IRF1-mediated IFN-λ production. Nat Immunol 2014; 15:700-1. [PMID: 25045870 DOI: 10.1038/ni.2924] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Siyuan Ding
- Department of Pathology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Michael D Robek
- Department of Pathology, Yale University School of Medicine, New Haven, Connecticut, USA
| |
Collapse
|
429
|
Patel JR, García-Sastre A. Activation and regulation of pathogen sensor RIG-I. Cytokine Growth Factor Rev 2014; 25:513-23. [PMID: 25212896 DOI: 10.1016/j.cytogfr.2014.08.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 08/15/2014] [Indexed: 12/24/2022]
Abstract
Cells are equipped with a large set of pattern recognition receptors or sensors that detect foreign molecules such as pathogenic nucleic acids and initiate proinflammatory and antimicrobial innate immune responses. RIG-I is a cytosolic sensor that detects 5'-triphosphate double-stranded RNAs produced during infection. RIG-I is responsible for mounting an antimicrobial response against a variety of viruses and intracellular bacteria. RIG-I contains an intricate structural architecture that allows for efficient signaling downstream in the pathway and autoregulation. The RIG-I-mediated antimicrobial pathway is highly regulated in cells requiring various cofactors, negative regulators, and posttranslational modifications. Modulation of RIG-I and RIG-I-mediated signaling in cells by pathogens to evade recognition and activation of the antimicrobial pathway highlights the essential nature of RIG-I in the innate immune response.
Collapse
Affiliation(s)
- Jenish R Patel
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
| | - Adolfo García-Sastre
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Department of Medicine, Division of Infectious Diseases, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| |
Collapse
|
430
|
Structural mechanisms in NLR inflammasome signaling. Curr Opin Struct Biol 2014; 29:17-25. [PMID: 25201319 DOI: 10.1016/j.sbi.2014.08.011] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2014] [Revised: 07/25/2014] [Accepted: 08/05/2014] [Indexed: 01/28/2023]
Abstract
Members of the NOD-like receptor (NLR) family mediate the innate immune response to a wide range of pathogens, tissue damage and other cellular stresses. They achieve modulation of these signals by forming oligomeric signaling platforms, which in analogy to the apoptosome are predicted to adopt a defined oligomeric architecture and will here be referred to as NLR oligomers. Once formed, oligomers of the NLR proteins NLRP3 or NLRC4 'recruit' the adaptor protein ASC and the effector caspase-1, whereby NLRC4 can also directly interact with caspase-1. This results in large multi-protein assemblies, termed inflammasomes. Ultimately, the formation of these inflammasomes leads to the activation of caspase-1, which then processes the cytokines IL-1β and IL-18 triggering the immune response. Here we review new insights into NLR structure and implications on NLR oligomer formation as well as the nature of multi-protein inflammasomes. Of note, so dubbed 'canonical inflammasomes' can also be triggered by the NLR NLRP1b and the non-NLR protein AIM2, however the most detailed mechanistic information at hand pertains to NLRC4 while NLRP3 represents the quintessential inflammasome trigger. Thus these two NLRs are mainly used as examples in this article.
Collapse
|
431
|
Connolly DJ, Bowie AG. The emerging role of human PYHIN proteins in innate immunity: implications for health and disease. Biochem Pharmacol 2014; 92:405-14. [PMID: 25199457 DOI: 10.1016/j.bcp.2014.08.031] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 08/27/2014] [Accepted: 08/28/2014] [Indexed: 02/07/2023]
Abstract
The innate immune response depends on the ability of immune cells to detect pathogens through germline-encoded pattern recognition receptors (PRRs). Recently discovered PRRs include some members of the Pyrin and HIN domain (PYHIN) family, which are encoded on an interferon-inducible gene cluster located on chromosome 1q23. There are five human PYHIN proteins; Absent in melanoma 2 (AIM2), IFN-γ inducible protein 16 (IFI16), Myeloid cell nuclear differentiation antigen (MNDA), Pyrin and HIN domain family member 1 (PYHIN1) and the recently identified Pyrin domain only protein 3 (POP3). Early studies reported roles for these proteins in cell cycle control, tumour suppression and transcriptional regulation. AIM2 and IFI16 have now been shown to be immune sensors of non-self DNA, such as that produced by viruses in infected cells. AIM2 binds DNA to activate the inflammasome, while IFI16 detection of DNA can lead to the up-regulation of type I interferons or inflammasome activation. Recent studies have shown how IFI16 senses DNA viruses, and also how viruses evade detection by IFI16, while structural studies have greatly advanced our understanding of how AIM2 and IFI16 bind DNA to activate these immune responses. Furthermore, following the identification of POP3, interplay between members of this gene cluster has been established, with POP3 acting as a negative regulator of the AIM2 and IFI16 inflammasomes. In this review we discuss the current understanding of how PYHIN proteins function in innate immunity, their role in disease and the therapeutic possibilities that arise as a result.
Collapse
Affiliation(s)
- Dympna J Connolly
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland
| | - Andrew G Bowie
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland.
| |
Collapse
|
432
|
Schmitz ML, Kracht M, Saul VV. The intricate interplay between RNA viruses and NF-κB. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:2754-2764. [PMID: 25116307 PMCID: PMC7114235 DOI: 10.1016/j.bbamcr.2014.08.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/21/2014] [Revised: 08/01/2014] [Accepted: 08/02/2014] [Indexed: 12/19/2022]
Abstract
RNA viruses have rapidly evolving genomes which often allow cross-species transmission and frequently generate new virus variants with altered pathogenic properties. Therefore infections by RNA viruses are a major threat to human health. The infected host cell detects trace amounts of viral RNA and the last years have revealed common principles in the biochemical mechanisms leading to signal amplification that is required for mounting of a powerful antiviral response. Components of the RNA sensing and signaling machinery such as RIG-I-like proteins, MAVS and the inflammasome inducibly form large oligomers or even fibers that exhibit hallmarks of prions. Following a nucleation event triggered by detection of viral RNA, these energetically favorable and irreversible polymerization events trigger signaling cascades leading to the induction of antiviral and inflammatory responses, mediated by interferon and NF-κB pathways. Viruses have evolved sophisticated strategies to manipulate these host cell signaling pathways in order to ensure their replication. We will discuss at the examples of influenza and HTLV-1 viruses how a fascinating diversity of biochemical mechanisms is employed by viral proteins to control the NF-κB pathway at all levels.
Collapse
Affiliation(s)
- M Lienhard Schmitz
- Institute of Biochemistry, Medical Faculty, Friedrichstrasse 24, Justus-Liebig-University, 35392 Giessen, Germany.
| | - Michael Kracht
- Rudolf-Buchheim-Institute of Pharmacology, Justus-Liebig-University Giessen, D-35392 Giessen, Germany
| | - Vera V Saul
- Institute of Biochemistry, Medical Faculty, Friedrichstrasse 24, Justus-Liebig-University, 35392 Giessen, Germany
| |
Collapse
|
433
|
Franklin BS, Bossaller L, De Nardo D, Ratter JM, Stutz A, Engels G, Brenker C, Nordhoff M, Mirandola SR, Al-Amoudi A, Mangan M, Zimmer S, Monks B, Fricke M, Schmidt RE, Espevik T, Jones B, Jarnicki AG, Hansbro PM, Busto P, Marshak-Rothstein A, Hornemann S, Aguzzi A, Kastenmüller W, Latz E. The adaptor ASC has extracellular and 'prionoid' activities that propagate inflammation. Nat Immunol 2014; 15:727-37. [PMID: 24952505 PMCID: PMC4116676 DOI: 10.1038/ni.2913] [Citation(s) in RCA: 583] [Impact Index Per Article: 58.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 05/01/2014] [Indexed: 12/15/2022]
Abstract
Microbes or danger signals trigger inflammasome sensors, which induce polymerization of the adaptor ASC and the assembly of ASC specks. ASC specks recruit and activate caspase-1, which induces maturation of the cytokine interleukin 1β (IL-1β) and pyroptotic cell death. Here we found that after pyroptosis, ASC specks accumulated in the extracellular space, where they promoted further maturation of IL-1β. In addition, phagocytosis of ASC specks by macrophages induced lysosomal damage and nucleation of soluble ASC, as well as activation of IL-1β in recipient cells. ASC specks appeared in bodily fluids from inflamed tissues, and autoantibodies to ASC specks developed in patients and mice with autoimmune pathologies. Together these findings reveal extracellular functions of ASC specks and a previously unknown form of cell-to-cell communication.
Collapse
Affiliation(s)
- Bernardo S. Franklin
- Institute of Innate Immunity, University Hospitals, University of Bonn, 53127, Bonn, Germany
| | - Lukas Bossaller
- Department of Immunology and Rheumatology, Hannover Medical School, 30625 Hannover, Germany
- Department of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, Massachusetts, 01605, USA
| | - Dominic De Nardo
- Institute of Innate Immunity, University Hospitals, University of Bonn, 53127, Bonn, Germany
| | - Jacqueline M. Ratter
- Institute of Innate Immunity, University Hospitals, University of Bonn, 53127, Bonn, Germany
| | - Andrea Stutz
- Institute of Innate Immunity, University Hospitals, University of Bonn, 53127, Bonn, Germany
| | - Gudrun Engels
- Institute of Innate Immunity, University Hospitals, University of Bonn, 53127, Bonn, Germany
| | | | - Mark Nordhoff
- German Center for Neurodegenerative Diseases, 53175, Bonn, Germany
| | | | - Ashraf Al-Amoudi
- German Center for Neurodegenerative Diseases, 53175, Bonn, Germany
| | - Matthew Mangan
- Institute of Innate Immunity, University Hospitals, University of Bonn, 53127, Bonn, Germany
- German Center for Neurodegenerative Diseases, 53175, Bonn, Germany
| | - Sebastian Zimmer
- Department of Medicine/Cardiology, University of Bonn, 53105, Bonn, Germany
| | - Brian Monks
- Institute of Innate Immunity, University Hospitals, University of Bonn, 53127, Bonn, Germany
- Department of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, Massachusetts, 01605, USA
| | - Martin Fricke
- Department of Immunology and Rheumatology, Hannover Medical School, 30625 Hannover, Germany
| | - Reinhold E. Schmidt
- Department of Immunology and Rheumatology, Hannover Medical School, 30625 Hannover, Germany
| | - Terje Espevik
- Center of Molecular Inflammation Research, Department of Cancer Research and Molecular Medicine, NTNU, Trondheim 7491, Norway
| | - Bernadette Jones
- The University of Newcastle & Vaccines, Infection, Viruses & Asthma (VIVA), Hunter Medical Research Institute, Newcastle, Australia
| | - Andrew G. Jarnicki
- The University of Newcastle & Vaccines, Infection, Viruses & Asthma (VIVA), Hunter Medical Research Institute, Newcastle, Australia
| | - Philip M. Hansbro
- The University of Newcastle & Vaccines, Infection, Viruses & Asthma (VIVA), Hunter Medical Research Institute, Newcastle, Australia
| | - Patricia Busto
- Department of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, Massachusetts, 01605, USA
| | - Ann Marshak-Rothstein
- Department of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, Massachusetts, 01605, USA
| | - Simone Hornemann
- University Hospital Zürich, Institute of Neuropathology, CH–8091 Zürich, Switzerland
| | - Adriano Aguzzi
- University Hospital Zürich, Institute of Neuropathology, CH–8091 Zürich, Switzerland
| | - Wolfgang Kastenmüller
- Institute of Molecular Medicine and Experimental Immunology, University of Bonn, 53127, Bonn, Germany
| | - Eicke Latz
- Institute of Innate Immunity, University Hospitals, University of Bonn, 53127, Bonn, Germany
- Department of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, Massachusetts, 01605, USA
- German Center for Neurodegenerative Diseases, 53175, Bonn, Germany
- Center of Molecular Inflammation Research, Department of Cancer Research and Molecular Medicine, NTNU, Trondheim 7491, Norway
| |
Collapse
|
434
|
Reikine S, Nguyen JB, Modis Y. Pattern Recognition and Signaling Mechanisms of RIG-I and MDA5. Front Immunol 2014; 5:342. [PMID: 25101084 PMCID: PMC4107945 DOI: 10.3389/fimmu.2014.00342] [Citation(s) in RCA: 275] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Accepted: 07/05/2014] [Indexed: 12/25/2022] Open
Abstract
Most organisms rely on innate immune receptors to recognize conserved molecular structures from invading microbes. Two essential innate immune receptors, RIG-I and MDA5, detect viral double-stranded RNA in the cytoplasm. The inflammatory response triggered by these RIG-I-like receptors (RLRs) is one of the first and most important lines of defense against infection. RIG-I recognizes short RNA ligands with 5′-triphosphate caps. MDA5 recognizes long kilobase-scale genomic RNA and replication intermediates. Ligand binding induces conformational changes and oligomerization of RLRs that activate the signaling partner MAVS on the mitochondrial and peroxisomal membranes. This signaling process is under tight regulation, dependent on post-translational modifications of RIG-I and MDA5, and on regulatory proteins including unanchored ubiquitin chains and a third RLR, LGP2. Here, we review recent advances that have shifted the paradigm of RLR signaling away from the conventional linear signaling cascade. In the emerging RLR signaling model, large multimeric signaling platforms generate a highly cooperative, self-propagating, and context-dependent signal, which varies with the subcellular localization of the signaling platform.
Collapse
Affiliation(s)
- Stephanie Reikine
- Department of Molecular Biophysics and Biochemistry, Yale University , New Haven, CT , USA
| | - Jennifer B Nguyen
- Department of Molecular Biophysics and Biochemistry, Yale University , New Haven, CT , USA
| | - Yorgo Modis
- Department of Molecular Biophysics and Biochemistry, Yale University , New Haven, CT , USA
| |
Collapse
|
435
|
Wu B, Peisley A, Tetrault D, Li Z, Egelman EH, Magor KE, Walz T, Penczek PA, Hur S. Molecular imprinting as a signal-activation mechanism of the viral RNA sensor RIG-I. Mol Cell 2014; 55:511-23. [PMID: 25018021 DOI: 10.1016/j.molcel.2014.06.010] [Citation(s) in RCA: 186] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Revised: 05/12/2014] [Accepted: 06/02/2014] [Indexed: 12/24/2022]
Abstract
RIG-I activates interferon signaling pathways by promoting filament formation of the adaptor molecule, MAVS. Assembly of the MAVS filament is mediated by its CARD domain (CARD(MAVS)), and requires its interaction with the tandem CARDs of RIG-I (2CARD(RIG-I)). However, the precise nature of the interaction between 2CARD(RIG-I) and CARD(MAVS), and how this interaction leads to CARD(MAVS) filament assembly, has been unclear. Here we report a 3.6 Å electron microscopy structure of the CARD(MAVS) filament and a 3.4 Å crystal structure of the 2CARD(RIG-I):CARD(MAVS) complex, representing 2CARD(RIG-I) "caught in the act" of nucleating the CARD(MAVS) filament. These structures, together with functional analyses, show that 2CARD(RIG-I) acts as a template for the CARD(MAVS) filament assembly, by forming a helical tetrameric structure and recruiting CARD(MAVS) along its helical trajectory. Our work thus reveals that signal activation by RIG-I occurs by imprinting its helical assembly architecture on MAVS, a previously uncharacterized mechanism of signal transmission.
Collapse
Affiliation(s)
- Bin Wu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Children's Hospital Boston, Boston, MA 02115, USA
| | - Alys Peisley
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Children's Hospital Boston, Boston, MA 02115, USA
| | - David Tetrault
- Department of Biological Sciences and the Li Ka Shing Institute of Virology, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Zongli Li
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Edward H Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA
| | - Katharine E Magor
- Department of Biological Sciences and the Li Ka Shing Institute of Virology, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Thomas Walz
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Pawel A Penczek
- Department of Biochemistry and Molecular Biology, The University of Texas-Houston Medical School, Houston, TX 77030, USA
| | - Sun Hur
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Children's Hospital Boston, Boston, MA 02115, USA.
| |
Collapse
|
436
|
Mayle S, Boyle JP, Sekine E, Zurek B, Kufer TA, Monie TP. Engagement of nucleotide-binding oligomerization domain-containing protein 1 (NOD1) by receptor-interacting protein 2 (RIP2) is insufficient for signal transduction. J Biol Chem 2014; 289:22900-22914. [PMID: 24958724 PMCID: PMC4132792 DOI: 10.1074/jbc.m114.557900] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Following activation, the cytoplasmic pattern recognition receptor nucleotide-binding oligomerization domain-containing protein 1 (NOD1) interacts with its adaptor protein receptor-interacting protein 2 (RIP2) to propagate immune signaling and initiate a proinflammatory immune response. This interaction is mediated by the caspase recruitment domain (CARD) of both proteins. Polymorphisms in immune proteins can affect receptor function and predispose individuals to specific autoinflammatory disorders. In this report, we show that mutations in helix 2 of the CARD of NOD1 disrupted receptor function but did not interfere with RIP2 interaction. In particular, N43S, a rare polymorphism, resulted in receptor dysfunction despite retaining normal cellular localization, protein folding, and an ability to interact with RIP2. Mutation of Asn-43 resulted in an increased tendency to form dimers, which we propose is the source of this dysfunction. We also demonstrate that mutation of Lys-443 and Tyr-474 in RIP2 disrupted the interaction with NOD1. Mapping the key residues involved in the interaction between NOD1 and RIP2 to the known structures of CARD complexes revealed the likely involvement of both type I and type III interfaces in the NOD1·RIP2 complex. Overall we demonstrate that the NOD1-RIP2 signaling axis is more complex than previously assumed, that simple engagement of RIP2 is insufficient to mediate signaling, and that the interaction between NOD1 and RIP2 constitutes multiple CARD-CARD interfaces.
Collapse
Affiliation(s)
- Sophie Mayle
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, United Kingdom
| | - Joseph P Boyle
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, United Kingdom
| | - Eiki Sekine
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, United Kingdom
| | - Birte Zurek
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelsstrasse 19-21, 50935 Köln, Germany, and
| | - Thomas A Kufer
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelsstrasse 19-21, 50935 Köln, Germany, and
| | - Tom P Monie
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, United Kingdom,; Department of Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES, United Kingdom.
| |
Collapse
|
437
|
The NLRP3 inflammasome is released as a particulate danger signal that amplifies the inflammatory response. Nat Immunol 2014; 15:738-48. [PMID: 24952504 DOI: 10.1038/ni.2919] [Citation(s) in RCA: 604] [Impact Index Per Article: 60.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 05/09/2014] [Indexed: 12/17/2022]
Abstract
Assembly of the NLRP3 inflammasome activates caspase-1 and mediates the processing and release of the leaderless cytokine IL-1β and thereby serves a central role in the inflammatory response and in diverse human diseases. Here we found that upon activation of caspase-1, oligomeric NLRP3 inflammasome particles were released from macrophages. Recombinant oligomeric protein particles composed of the adaptor ASC or the p.D303N mutant form of NLRP3 associated with cryopyrin-associated periodic syndromes (CAPS) stimulated further activation of caspase-1 extracellularly, as well as intracellularly after phagocytosis by surrounding macrophages. We found oligomeric ASC particles in the serum of patients with active CAPS but not in that of patients with other inherited autoinflammatory diseases. Our findings support a model whereby the NLRP3 inflammasome, acting as an extracellular oligomeric complex, amplifies the inflammatory response.
Collapse
|
438
|
Abstract
Microbial and danger signals result in inflammasome activation and release of inflammatory cytokines through mechanisms that remain elusive. Cai et al. and Lu et al. show that triggering of inflammasome sensors induces prion-like polymerization of the adaptor ASC into filaments. These structures function as platforms for inflammatory cytokine production and represent a unified mechanism for inflammasome assembly.
Collapse
Affiliation(s)
- Jürgen Ruland
- Institut für Klinische Chemie und Pathobiochemie, Klinikum rechts der Isar, Technische Universität München, 81675 Munich, Germany.
| |
Collapse
|
439
|
Daskalov A, Gantner M, Wälti MA, Schmidlin T, Chi CN, Wasmer C, Schütz A, Ceschin J, Clavé C, Cescau S, Meier B, Riek R, Saupe SJ. Contribution of specific residues of the β-solenoid fold to HET-s prion function, amyloid structure and stability. PLoS Pathog 2014; 10:e1004158. [PMID: 24945274 PMCID: PMC4055769 DOI: 10.1371/journal.ppat.1004158] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 04/15/2014] [Indexed: 01/12/2023] Open
Abstract
The [Het-s] prion of the fungus Podospora anserina represents a good model system for studying the structure-function relationship in amyloid proteins because a high resolution solid-state NMR structure of the amyloid prion form of the HET-s prion forming domain (PFD) is available. The HET-s PFD adopts a specific β-solenoid fold with two rungs of β-strands delimiting a triangular hydrophobic core. A C-terminal loop folds back onto the rigid core region and forms a more dynamic semi-hydrophobic pocket extending the hydrophobic core. Herein, an alanine scanning mutagenesis of the HET-s PFD was conducted. Different structural elements identified in the prion fold such as the triangular hydrophobic core, the salt bridges, the asparagines ladders and the C-terminal loop were altered and the effect of these mutations on prion function, fibril structure and stability was assayed. Prion activity and structure were found to be very robust; only a few key mutations were able to corrupt structure and function. While some mutations strongly destabilize the fold, many substitutions in fact increase stability of the fold. This increase in structural stability did not influence prion formation propensity in vivo. However, if an Ala replacement did alter the structure of the core or did influence the shape of the denaturation curve, the corresponding variant showed a decreased prion efficacy. It is also the finding that in addition to the structural elements of the rigid core region, the aromatic residues in the C-terminal semi-hydrophobic pocket are critical for prion propagation. Mutations in the latter region either positively or negatively affected prion formation. We thus identify a region that modulates prion formation although it is not part of the rigid cross-β core, an observation that might be relevant to other amyloid models.
Collapse
Affiliation(s)
- Asen Daskalov
- Institut de Biochimie et de Génétique Cellulaire, Unité Mixte de Recherche 5095, Centre National de la Recherche Scientifique Université de Bordeaux, Bordeaux, France
| | - Matthias Gantner
- Laboratory of Physical Chemistry, Eidgenössische Technische Hochschule (ETH) Zürich, Zürich, Switzerland
| | - Marielle Aulikki Wälti
- Laboratory of Physical Chemistry, Eidgenössische Technische Hochschule (ETH) Zürich, Zürich, Switzerland
| | - Thierry Schmidlin
- Laboratory of Physical Chemistry, Eidgenössische Technische Hochschule (ETH) Zürich, Zürich, Switzerland
| | - Celestine N. Chi
- Laboratory of Physical Chemistry, Eidgenössische Technische Hochschule (ETH) Zürich, Zürich, Switzerland
| | - Christian Wasmer
- Laboratory of Physical Chemistry, Eidgenössische Technische Hochschule (ETH) Zürich, Zürich, Switzerland
| | - Anne Schütz
- Laboratory of Physical Chemistry, Eidgenössische Technische Hochschule (ETH) Zürich, Zürich, Switzerland
| | - Johanna Ceschin
- Institut de Biochimie et de Génétique Cellulaire, Unité Mixte de Recherche 5095, Centre National de la Recherche Scientifique Université de Bordeaux, Bordeaux, France
| | - Corinne Clavé
- Institut de Biochimie et de Génétique Cellulaire, Unité Mixte de Recherche 5095, Centre National de la Recherche Scientifique Université de Bordeaux, Bordeaux, France
| | - Sandra Cescau
- Institut de Biochimie et de Génétique Cellulaire, Unité Mixte de Recherche 5095, Centre National de la Recherche Scientifique Université de Bordeaux, Bordeaux, France
| | - Beat Meier
- Laboratory of Physical Chemistry, Eidgenössische Technische Hochschule (ETH) Zürich, Zürich, Switzerland
| | - Roland Riek
- Laboratory of Physical Chemistry, Eidgenössische Technische Hochschule (ETH) Zürich, Zürich, Switzerland
| | - Sven J. Saupe
- Institut de Biochimie et de Génétique Cellulaire, Unité Mixte de Recherche 5095, Centre National de la Recherche Scientifique Université de Bordeaux, Bordeaux, France
| |
Collapse
|
440
|
Ran Y, Shu HB, Wang YY. MITA/STING: a central and multifaceted mediator in innate immune response. Cytokine Growth Factor Rev 2014; 25:631-9. [PMID: 24929887 PMCID: PMC7108248 DOI: 10.1016/j.cytogfr.2014.05.003] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Revised: 05/03/2014] [Accepted: 05/12/2014] [Indexed: 01/29/2023]
Abstract
The recognition of nucleic acids is a general strategy used by the host to detect invading pathogens. Many studies have established that MITA/STING is a central component in the innate immune response to cytosolic DNA and RNA derived from pathogens. MITA can act both as a direct sensor of cyclic dinucleotides (CDNs) and as an adaptor for the recruitment of downstream signaling components. In both roles, MITA is part of signaling cascades that orchestrate innate immune defenses against various pathogens, including viruses, bacteria and parasites. Here, we highlight recent studies that have uncovered the molecular mechanisms of MITA-mediated signal transduction and regulation, and discuss some notable issues that remain elusive.
Collapse
Affiliation(s)
- Yong Ran
- Wuhan Institute of Virology, State Key Laboratory of Virology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Hong-Bing Shu
- College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Yan-Yi Wang
- Wuhan Institute of Virology, State Key Laboratory of Virology, Chinese Academy of Sciences, Wuhan 430072, China.
| |
Collapse
|
441
|
|
442
|
Silva JL, De Moura Gallo CV, Costa DCF, Rangel LP. Prion-like aggregation of mutant p53 in cancer. Trends Biochem Sci 2014; 39:260-7. [PMID: 24775734 DOI: 10.1016/j.tibs.2014.04.001] [Citation(s) in RCA: 149] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2014] [Revised: 03/31/2014] [Accepted: 04/02/2014] [Indexed: 12/19/2022]
Abstract
p53 is a master regulatory protein that participates in cellular processes such as apoptosis, DNA repair, and cell cycle control. p53 functions as a homotetrameric tumor suppressor, and is lost in more than 50% of human cancers. Recent studies have suggested that the formation of mutant p53 aggregates is associated with loss-of-function (LoF), dominant-negative (DN), and gain-of-function (GoF) effects. We propose that these phenomena can be explained by a prion-like behavior of mutant p53. We discuss the shared properties of cancer and neurodegenerative diseases and how the prion-like properties of p53 aggregates offer potential targets for drug development.
Collapse
Affiliation(s)
- Jerson L Silva
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; Instituto Nacional de Ciência e Tecnologia (INCT) de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil.
| | - Claudia V De Moura Gallo
- Instituto Nacional de Ciência e Tecnologia (INCT) de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; Departamento de Genética, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Danielly C F Costa
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; Instituto Nacional de Ciência e Tecnologia (INCT) de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
| | - Luciana P Rangel
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; Instituto Nacional de Ciência e Tecnologia (INCT) de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; Faculdade de Farmácia, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
| |
Collapse
|
443
|
|