851
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Qiao Q, Wu H. Supramolecular organizing centers (SMOCs) as signaling machines in innate immune activation. SCIENCE CHINA-LIFE SCIENCES 2015; 58:1067-72. [PMID: 26511517 PMCID: PMC4847730 DOI: 10.1007/s11427-015-4951-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 10/16/2015] [Indexed: 12/27/2022]
Abstract
Innate immunity offers the first line of defense against infections and other types of danger such as tumorigenesis. Its discovery provides tremendous therapeutic opportunities for numerous human diseases. Delving into the structural basis of signal transduction by innate immune receptors, our lab has recently helped to establish the new paradigm in which innate immune receptors transduce ligand-binding signals through formation of higher-order assemblies containing intracellular adapters, signaling enzymes and their substrates. These large signalosome assemblies may be visible under light microscopy as punctate structures in the μm scale, connecting to the underlying molecular structures in the nm scale. They drive proximity-induced enzyme activation, and provide a mechanism for signaling amplification by nucleated polymerization. These supramolecular signaling complexes also open new questions on their cellular organization and mode of regulation, pose challenges to our methodology, and afford valuable implications in drug discovery against these medically important pathways.
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Affiliation(s)
- Qi Qiao
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA.,Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Hao Wu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA. .,Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, 02115, USA.
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852
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Shiga Toxins Activate the NLRP3 Inflammasome Pathway To Promote Both Production of the Proinflammatory Cytokine Interleukin-1β and Apoptotic Cell Death. Infect Immun 2015; 84:172-86. [PMID: 26502906 DOI: 10.1128/iai.01095-15] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 10/16/2015] [Indexed: 02/06/2023] Open
Abstract
Shiga toxin (Stx)-mediated immune responses, including the production of the proinflammatory cytokines tumor necrosis-α (TNF-α) and interleukin-1β (IL-1β), may exacerbate vascular damage and accelerate lethality. However, the immune signaling pathway activated in response to Stx is not well understood. Here, we demonstrate that enzymatically active Stx, which leads to ribotoxic stress, triggers NLRP3 inflammasome-dependent caspase-1 activation and IL-1β secretion in differentiated macrophage-like THP-1 (D-THP-1) cells. The treatment of cells with a chemical inhibitor of glycosphingolipid biosynthesis, which suppresses the expression of the Stx receptor globotriaosylceramide and subsequent endocytosis of the toxin, substantially blocked activation of the NLRP3 inflammasome and processing of caspase-1 and IL-1β. Processing and release of both caspase-1 and IL-1β were significantly reduced or abolished in Stx-intoxicated D-THP-1 cells in which the expression of NLRP3 or ASC was stably knocked down. Furthermore, Stx mediated the activation of caspases involved in apoptosis in an NLRP3- or ASC-dependent manner. In Stx-intoxicated cells, the NLRP3 inflammasome triggered the activation of caspase-8/3, leading to the initiation of apoptosis, in addition to caspase-1-dependent pyroptotic cell death. Taken together, these results suggest that Stxs trigger the NLRP3 inflammasome pathway to release proinflammatory IL-1β as well as to promote apoptotic cell death.
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853
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Cui J, Chen Y, Wang HY, Wang RF. Mechanisms and pathways of innate immune activation and regulation in health and cancer. Hum Vaccin Immunother 2015; 10:3270-85. [PMID: 25625930 DOI: 10.4161/21645515.2014.979640] [Citation(s) in RCA: 207] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Research on innate immune signaling and regulation has recently focused on pathogen recognition receptors (PRRs) and their signaling pathways. Members of PRRs sense diverse microbial invasions or danger signals, and initiate innate immune signaling pathways, leading to proinflammatory cytokines production, which, in turn, instructs adaptive immune response development. Despite the diverse functions employed by innate immune signaling to respond to a variety of different pathogens, the innate immune response must be tightly regulated. Otherwise, aberrant, uncontrolled immune responses will lead to harmful, or even fatal, consequences. Therefore, it is essential to better discern innate immune signaling and many regulators, controlling various signaling pathways, have been identified. In this review, we focus on the recent advances in our understanding of the activation and regulation of innate immune signaling in the host response to pathogens and cancer.
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Key Words
- AIM2, absent in melanoma 2
- ALRs, AIM2-like receptors
- AMPK, AMP activated protein kinase
- ASC, apoptosis-associated speck-like protein containing a CARD
- Atg16L, autophagy related 16-like
- BMM, bone marrow-derived macrophage
- CARD, caspase recruitment domain
- CDNs, cyclic dinucleotides
- CLRs, C-type lectin receptors
- CMV, cytomegalovirus
- CYLD, the familial cylindromatosis tumor suppressor gene
- DAMPs, danger-associated molecular patterns
- DCs, dendritic cells
- DDX41, DEAD (Asp-Glu-Ala-Asp) box polypeptide 41
- ER, endoplasmic reticulum
- GBP5, guanylate-binding protein 5
- GSK3β, Glycogen synthase kinase 3β
- HCC, hepatocellular carcinoma
- IFI16, interferon, gamma-inducible protein 16
- IFN, interferon
- IKK, IkB kinase
- IKKi, inducible IkB kinase
- IRAK, interleukin-1 receptor-associated kinase
- IRF, interferon regulatory factor
- KSHV, Kaposi's sarcoma-associated herpesvirus
- LBP, LPS-binding protein
- LGP 2, laboratory of genetics and physiology 2
- LPS, lipopolysaccharide
- LRR, leucine-rich repeat
- LT, lethal toxin
- LUBAC, linear ubiquitin assembly complex
- MAVS, mitochondrial antiviral signaling protein
- MDA5, melanoma differentiation-associated protein 5
- MDP, muramyl dipeptide
- MIB, mind bomb
- MyD88, myeloid differentiation factor 88
- NAIPs, neuronal apoptosis inhibitory proteins
- NEMO, NF-kB essential modulator
- NLRs, Nod- like receptors
- NOD, nucleotide-binding oligomerization domain
- Nrdp1, neuregulin receptor degradation protein 1
- PAMPs, pathogen-associated molecular patterns
- PKC-d, protein kinase C delta
- PKR, dsRNA-dependent protein kinase
- PRRs
- PRRs, pathogen recognition receptors
- RACK1, receptor for activated C kinase 1
- RAUL, RTA-associated E3 ligase
- RIG-I, retinoic acid-inducible gene 1
- RIP, receptor-interacting protein
- RLRs, RIG-I-like receptors
- ROS, reactive oxygen species
- SARM, sterile a- and armadillo motif-containing protein
- SIGIRR, single Ig IL-1-related receptor
- SOCS, suppressor of cytokine signaling
- STING, stimulator of interferon gene
- TAK1, TGF-b-activating kinase 1
- TANK, TRAF family-member-associated NF-kB activator
- TBK1, TANK binding kinase 1
- TIR, Toll IL-1 receptor
- TIRAP, TIR domain-containing adapter protein
- TLRs, Toll-like receptors
- TRAF, TNFR-associated factor
- TRAILR, tumor-necrosis factor-related apoptosis-inducing ligand receptor
- TRAM, TRIF-related adaptor molecule
- TRIF, TIR domain-containing adaptor inducing IFN-b
- TRIMs, tripartite motif containing proteins
- TRIP, TRAF-interacting protein
- ULK1, autophagy related serine threonine UNC-51- like kinase
- cDC, conventional dendritic cell
- cGAS, cyclic GMP-AMP synthase
- cIAP, cellular inhibitor of apoptosis protein
- cancer
- iE-DAP, g-D-glutamyl-meso-diaminopimelic acid
- inflammation
- innate immunity
- pDC, plasmacytoid dendritic cell
- type I interferon
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Affiliation(s)
- Jun Cui
- a Key Laboratory of Gene Engineering of the Ministry of Education; State Key Laboratory of Biocontrol; School of Life Sciences ; Sun Yat-sen University ; Guangzhou , P. R. China
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854
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Interleukin-1 Family Cytokines in Liver Diseases. Mediators Inflamm 2015; 2015:630265. [PMID: 26549942 PMCID: PMC4624893 DOI: 10.1155/2015/630265] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 09/27/2015] [Indexed: 02/06/2023] Open
Abstract
The gene encoding IL-1 was sequenced more than 30 years ago, and many related cytokines, such as IL-18, IL-33, IL-36, IL-37, IL-38, IL-1 receptor antagonist (IL-1Ra), and IL-36Ra, have since been identified. IL-1 is a potent proinflammatory cytokine and is involved in various inflammatory diseases. Other IL-1 family ligands are critical for the development of diverse diseases, including inflammatory and allergic diseases. Only IL-1Ra possesses the leader peptide required for secretion from cells, and many ligands require posttranslational processing for activation. Some require inflammasome-mediated processing for activation and release, whereas others serve as alarmins and are released following cell membrane rupture, for example, by pyroptosis or necroptosis. Thus, each ligand has the proper molecular process to exert its own biological functions. In this review, we will give a brief introduction to the IL-1 family cytokines and discuss their pivotal roles in the development of various liver diseases in association with immune responses. For example, an excess of IL-33 causes liver fibrosis in mice via activation and expansion of group 2 innate lymphoid cells to produce type 2 cytokines, resulting in cell conversion into pro-fibrotic M2 macrophages. Finally, we will discuss the importance of IL-1 family cytokine-mediated molecular and cellular networks in the development of acute and chronic liver diseases.
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855
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Vajjhala PR, Lu A, Brown DL, Pang SW, Sagulenko V, Sester DP, Cridland SO, Hill JM, Schroder K, Stow JL, Wu H, Stacey KJ. The Inflammasome Adaptor ASC Induces Procaspase-8 Death Effector Domain Filaments. J Biol Chem 2015; 290:29217-30. [PMID: 26468282 DOI: 10.1074/jbc.m115.687731] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Indexed: 01/19/2023] Open
Abstract
Inflammasomes mediate inflammatory and cell death responses to pathogens and cellular stress signals via activation of procaspases-1 and -8. During inflammasome assembly, activated receptors of the NLR or PYHIN family recruit the adaptor protein ASC and initiate polymerization of its pyrin domain (PYD) into filaments. We show that ASC filaments in turn nucleate procaspase-8 death effector domain (DED) filaments in vitro and in vivo. Interaction between ASC PYD and procaspase-8 tandem DEDs optimally required both DEDs and represents an unusual heterotypic interaction between domains of the death fold superfamily. Analysis of ASC PYD mutants showed that interaction surfaces that mediate procaspase-8 interaction overlap with those required for ASC self-association and interaction with the PYDs of inflammasome initiators. Our data indicate that multiple types of death fold domain filaments form at inflammasomes and that PYD/DED and homotypic PYD interaction modes are similar. Interestingly, we observed condensation of procaspase-8 filaments containing the catalytic domain, suggesting that procaspase-8 interactions within and/or between filaments may be involved in caspase-8 activation. Procaspase-8 filaments may also be relevant to apoptosis induced by death receptors.
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Affiliation(s)
| | - Alvin Lu
- the Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, and the Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts 02115
| | - Darren L Brown
- the Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Siew Wai Pang
- From the School of Chemistry and Molecular Biosciences and
| | | | - David P Sester
- From the School of Chemistry and Molecular Biosciences and
| | | | - Justine M Hill
- From the School of Chemistry and Molecular Biosciences and
| | - Kate Schroder
- the Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Jennifer L Stow
- the Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Hao Wu
- the Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, and the Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts 02115
| | - Katryn J Stacey
- From the School of Chemistry and Molecular Biosciences and the Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia,
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856
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Structure and assembly of the mouse ASC inflammasome by combined NMR spectroscopy and cryo-electron microscopy. Proc Natl Acad Sci U S A 2015; 112:13237-42. [PMID: 26464513 DOI: 10.1073/pnas.1507579112] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Inflammasomes are multiprotein complexes that control the innate immune response by activating caspase-1, thus promoting the secretion of cytokines in response to invading pathogens and endogenous triggers. Assembly of inflammasomes is induced by activation of a receptor protein. Many inflammasome receptors require the adapter protein ASC [apoptosis-associated speck-like protein containing a caspase-recruitment domain (CARD)], which consists of two domains, the N-terminal pyrin domain (PYD) and the C-terminal CARD. Upon activation, ASC forms large oligomeric filaments, which facilitate procaspase-1 recruitment. Here, we characterize the structure and filament formation of mouse ASC in vitro at atomic resolution. Information from cryo-electron microscopy and solid-state NMR spectroscopy is combined in a single structure calculation to obtain the atomic-resolution structure of the ASC filament. Perturbations of NMR resonances upon filament formation monitor the specific binding interfaces of ASC-PYD association. Importantly, NMR experiments show the rigidity of the PYD forming the core of the filament as well as the high mobility of the CARD relative to this core. The findings are validated by structure-based mutagenesis experiments in cultured macrophages. The 3D structure of the mouse ASC-PYD filament is highly similar to the recently determined human ASC-PYD filament, suggesting evolutionary conservation of ASC-dependent inflammasome mechanisms.
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857
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Bryant CE, Orr S, Ferguson B, Symmons MF, Boyle JP, Monie TP. International Union of Basic and Clinical Pharmacology. XCVI. Pattern recognition receptors in health and disease. Pharmacol Rev 2015; 67:462-504. [PMID: 25829385 DOI: 10.1124/pr.114.009928] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Since the discovery of Toll, in the fruit fly Drosophila melanogaster, as the first described pattern recognition receptor (PRR) in 1996, many families of these receptors have been discovered and characterized. PRRs play critically important roles in pathogen recognition to initiate innate immune responses that ultimately link to the generation of adaptive immunity. Activation of PRRs leads to the induction of immune and inflammatory genes, including proinflammatory cytokines and chemokines. It is increasingly clear that many PRRs are linked to a range of inflammatory, infectious, immune, and chronic degenerative diseases. Several drugs to modulate PRR activity are already in clinical trials and many more are likely to appear in the near future. Here, we review the different families of mammalian PRRs, the ligands they recognize, the mechanisms of activation, their role in disease, and the potential of targeting these proteins to develop the anti-inflammatory therapeutics of the future.
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Affiliation(s)
- Clare E Bryant
- Departments of Veterinary Medicine (C.E.B., J.P.B., T.P.M.), Pathology (B.F.), and Biochemistry (M.F.S., J.P.B.), University of Cambridge, Cambridge, United Kingdom; and Institute of Infection and Immunity, Cardiff University, Cardiff, United Kingdom (S.O.)
| | - Selinda Orr
- Departments of Veterinary Medicine (C.E.B., J.P.B., T.P.M.), Pathology (B.F.), and Biochemistry (M.F.S., J.P.B.), University of Cambridge, Cambridge, United Kingdom; and Institute of Infection and Immunity, Cardiff University, Cardiff, United Kingdom (S.O.)
| | - Brian Ferguson
- Departments of Veterinary Medicine (C.E.B., J.P.B., T.P.M.), Pathology (B.F.), and Biochemistry (M.F.S., J.P.B.), University of Cambridge, Cambridge, United Kingdom; and Institute of Infection and Immunity, Cardiff University, Cardiff, United Kingdom (S.O.)
| | - Martyn F Symmons
- Departments of Veterinary Medicine (C.E.B., J.P.B., T.P.M.), Pathology (B.F.), and Biochemistry (M.F.S., J.P.B.), University of Cambridge, Cambridge, United Kingdom; and Institute of Infection and Immunity, Cardiff University, Cardiff, United Kingdom (S.O.)
| | - Joseph P Boyle
- Departments of Veterinary Medicine (C.E.B., J.P.B., T.P.M.), Pathology (B.F.), and Biochemistry (M.F.S., J.P.B.), University of Cambridge, Cambridge, United Kingdom; and Institute of Infection and Immunity, Cardiff University, Cardiff, United Kingdom (S.O.)
| | - Tom P Monie
- Departments of Veterinary Medicine (C.E.B., J.P.B., T.P.M.), Pathology (B.F.), and Biochemistry (M.F.S., J.P.B.), University of Cambridge, Cambridge, United Kingdom; and Institute of Infection and Immunity, Cardiff University, Cardiff, United Kingdom (S.O.)
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858
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Hu Z, Zhou Q, Zhang C, Fan S, Cheng W, Zhao Y, Shao F, Wang HW, Sui SF, Chai J. Structural and biochemical basis for induced self-propagation of NLRC4. Science 2015; 350:399-404. [PMID: 26449475 DOI: 10.1126/science.aac5489] [Citation(s) in RCA: 236] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 09/14/2015] [Indexed: 02/05/2023]
Abstract
Responding to stimuli, nucleotide-binding domain and leucine-rich repeat-containing proteins (NLRs) oligomerize into multiprotein complexes, termed inflammasomes, mediating innate immunity. Recognition of bacterial pathogens by NLR apoptosis inhibitory proteins (NAIPs) induces NLR family CARD domain-containing protein 4 (NLRC4) activation and formation of NAIP-NLRC4 inflammasomes. The wheel-like structure of a PrgJ-NAIP2-NLRC4 complex determined by cryogenic electron microscopy at 6.6 angstrom reveals that NLRC4 activation involves substantial structural reorganization that creates one oligomerization surface (catalytic surface). Once activated, NLRC4 uses this surface to catalyze the activation of an inactive NLRC4, self-propagating its active conformation to form the wheel-like architecture. NAIP proteins possess a catalytic surface matching the other oligomerization surface (receptor surface) of NLRC4 but not those of their own, ensuring that one NAIP is sufficient to initiate NLRC4 oligomerization.
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Affiliation(s)
- Zehan Hu
- Ministry of Education Key Laboratory of Protein Science, Center for Structural Biology, School of Life Sciences, Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China
| | - Qiang Zhou
- State Key Laboratory of Biomembrane and Membrane Biotechnology, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Chenlu Zhang
- Ministry of Education Key Laboratory of Protein Science, Center for Structural Biology, School of Life Sciences, Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China
| | - Shilong Fan
- Ministry of Education Key Laboratory of Protein Science, Center for Structural Biology, School of Life Sciences, Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China
| | - Wei Cheng
- Division of Respiratory and Critical Care Medicine, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, and Collaborative Innovation Center of Biotherapy, Chengdu, China
| | - Yue Zhao
- National Institute of Biological Sciences, Beijing 102206, China
| | - Feng Shao
- National Institute of Biological Sciences, Beijing 102206, China
| | - Hong-Wei Wang
- Ministry of Education Key Laboratory of Protein Science, Center for Structural Biology, School of Life Sciences, Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China
| | - Sen-Fang Sui
- State Key Laboratory of Biomembrane and Membrane Biotechnology, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
| | - Jijie Chai
- Ministry of Education Key Laboratory of Protein Science, Center for Structural Biology, School of Life Sciences, Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China.
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859
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Zhang L, Chen S, Ruan J, Wu J, Tong AB, Yin Q, Li Y, David L, Lu A, Wang WL, Marks C, Ouyang Q, Zhang X, Mao Y, Wu H. Cryo-EM structure of the activated NAIP2-NLRC4 inflammasome reveals nucleated polymerization. Science 2015; 350:404-9. [PMID: 26449474 DOI: 10.1126/science.aac5789] [Citation(s) in RCA: 292] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 09/14/2015] [Indexed: 12/15/2022]
Abstract
The NLR family apoptosis inhibitory proteins (NAIPs) bind conserved bacterial ligands, such as the bacterial rod protein PrgJ, and recruit NLR family CARD-containing protein 4 (NLRC4) as the inflammasome adapter to activate innate immunity. We found that the PrgJ-NAIP2-NLRC4 inflammasome is assembled into multisubunit disk-like structures through a unidirectional adenosine triphosphatase polymerization, primed with a single PrgJ-activated NAIP2 per disk. Cryo-electron microscopy (cryo-EM) reconstruction at subnanometer resolution revealed a ~90° hinge rotation accompanying NLRC4 activation. Unlike in the related heptameric Apaf-1 apoptosome, in which each subunit needs to be conformationally activated by its ligand before assembly, a single PrgJ-activated NAIP2 initiates NLRC4 polymerization in a domino-like reaction to promote the disk assembly. These insights reveal the mechanism of signal amplification in NAIP-NLRC4 inflammasomes.
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Affiliation(s)
- Liman Zhang
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA. Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Shuobing Chen
- Center for Quantitative Biology, Peking-Tsinghua Joint Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China. Department of Cancer Immunology and Virology, Intel Parallel Computing Center for Structural Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Jianbin Ruan
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA. Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Jiayi Wu
- Center for Quantitative Biology, Peking-Tsinghua Joint Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China. Department of Cancer Immunology and Virology, Intel Parallel Computing Center for Structural Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Alexander B Tong
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA. Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Qian Yin
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA. Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Yang Li
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA. Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Liron David
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA. Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Alvin Lu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA. Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Wei Li Wang
- Department of Cancer Immunology and Virology, Intel Parallel Computing Center for Structural Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA. Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Carolyn Marks
- Center for Nanoscale Systems, Harvard University, Cambridge, MA 02138, USA
| | - Qi Ouyang
- Center for Quantitative Biology, Peking-Tsinghua Joint Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Xinzheng Zhang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Youdong Mao
- Center for Quantitative Biology, Peking-Tsinghua Joint Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China. Department of Cancer Immunology and Virology, Intel Parallel Computing Center for Structural Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA. Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA.
| | - Hao Wu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA. Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA.
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860
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Tovar-y-Romo LB, Penagos-Puig A, Ramírez-Jarquín JO. Endogenous recovery after brain damage: molecular mechanisms that balance neuronal life/death fate. J Neurochem 2015; 136:13-27. [PMID: 26376102 DOI: 10.1111/jnc.13362] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 07/27/2015] [Accepted: 08/25/2015] [Indexed: 01/08/2023]
Abstract
Neuronal survival depends on multiple factors that comprise a well-fueled energy metabolism, trophic input, clearance of toxic substances, appropriate redox environment, integrity of blood-brain barrier, suppression of programmed cell death pathways and cell cycle arrest. Disturbances of brain homeostasis lead to acute or chronic alterations that might ultimately cause neuronal death with consequent impairment of neurological function. Although we understand most of these processes well when they occur independently from one another, we still lack a clear grasp of the concerted cellular and molecular mechanisms activated upon neuronal damage that intervene in protecting damaged neurons from death. In this review, we summarize a handful of endogenously activated mechanisms that balance molecular cues so as to determine whether neurons recover from injury or die. We center our discussion on mechanisms that have been identified to participate in stroke, although we consider different scenarios of chronic neurodegeneration as well. We discuss two central processes that are involved in endogenous repair and that, when not regulated, could lead to tissue damage, namely, trophic support and neuroinflammation. We emphasize the need to construct integrated models of neuronal degeneration and survival that, in the end, converge in neuronal fate after injury. Under neurodegenerative conditions, endogenously activated mechanisms balance out molecular cues that determine whether neurons contend toxicity or die. Many processes involved in endogenous repair may as well lead to tissue damage depending on the strength of stimuli. Signaling mediated by trophic factors and neuroinflammation are examples of these processes as they regulate different mechanisms that mediate neuronal demise including necrosis, apoptosis, necroptosis, pyroptosis and autophagy. In this review, we discuss recent findings on balanced regulation and their involvement in neuronal death.
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Affiliation(s)
- Luis B Tovar-y-Romo
- División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, D. F., México
| | - Andrés Penagos-Puig
- División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, D. F., México
| | - Josué O Ramírez-Jarquín
- División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, D. F., México
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861
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Rivers-Auty J, Brough D. Potassium efflux fires the canon: Potassium efflux as a common trigger for canonical and noncanonical NLRP3 pathways. Eur J Immunol 2015; 45:2758-61. [PMID: 26332156 DOI: 10.1002/eji.201545958] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Revised: 08/12/2015] [Accepted: 08/21/2015] [Indexed: 01/10/2023]
Abstract
Murine caspase-11 and its human orthologues, caspase-4 and caspase-5, activate an inflammatory response following cytoplasmic recognition of cell wall constituents from Gram-negative bacteria, such as LPS. This inflammatory response involves pyroptotic cell death and the concomitant release of IL-1α, as well as the production of IL-1β and IL-18 through the noncanonical NLR family, pyrin domain containing 3 (NLRP3) pathway. This commentary discusses three papers in this issue of the European Journal of Immunology that advance our understanding of the roles of caspase-11, -4, and -5 in the noncanonical pathway. By utilizing the new gene editing technique, clustered regularly interspaced short palindromic repeats (CRISPR), as well as sensitive cell imaging techniques, these papers establish that cytoplasmic LPS-dependent IL-1β production requires the NLRP3 inflammasome and that its activation is dependent on K(+) efflux, whereas IL-1α release and pyroptotic cell death pathways are NLRP3-independent. These findings expand on previous research implicating K(+) efflux as the principal trigger for NLRP3 activation and suggest that canonical and noncanonical NLRP3 pathways are not as dissimilar as first thought.
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Affiliation(s)
- Jack Rivers-Auty
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - David Brough
- Faculty of Life Sciences, University of Manchester, Manchester, UK
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862
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Abstract
The PYRIN domain (PYD) is a protein-protein interaction domain, which belongs to the death domain fold (DDF) superfamily. It is best known for its signaling function in innate immune responses and particularly in the assembly of inflammasomes, which are large protein complexes that allow the induced proximity-mediated activation of caspase-1 and subsequently the release of pro-inflammatory cytokines. The molecular mechanism of inflammasome assembly was only recently elucidated and specifically requires PYD oligomerization. Here we discuss the recent advances in our understanding of PYD signaling and its regulation by PYD-only proteins.
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863
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Abstract
The tumor necrosis factor receptors (TNFRs) play essential roles in innate and adaptive immunity. Depending on conditions, TNFR induces multiple cell fates including cell survival, cell apoptosis, and cell programmed necrosis. Here, we review recent progress in structural studies of the TNFR signaling pathway. The structural basis for the high order signal complexes, including the DISC, ripoptosome, necrosome, and RIP3/MLKL complex, may provide novel insights for understanding the biophysical principles of cell signaling cascades.
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864
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Jin T, Xiao TS. Activation and assembly of the inflammasomes through conserved protein domain families. Apoptosis 2015; 20:151-6. [PMID: 25398536 DOI: 10.1007/s10495-014-1053-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Inflammasomes are oligomeric protein complexes assembled through interactions among the death domain superfamily members, in particular the CARD and PYD domains. Recent progress has shed lights on how the ASC PYD can polymerize to form filaments using multiple domain:domain interfaces, and how the caspase4 CARD can recognize LPS to activate the non-classical inflammasome pathway. Comprehensive understanding of the molecular mechanisms of inflammasome activation and assembly require more extensive structural and biophysical dissection of the inflammasome components and complexes, in particular additional CARD or PYD filaments. Because of the variations in death domain structures and complexes observed so far, future work will undoubtedly shed lights on the mechanisms of inflammasome assembly as well as more surprises on the versatile structure and function of the death domain superfamily.
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Affiliation(s)
- Tengchuan Jin
- Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892, USA,
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865
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Freeman LC, Ting JPY. The pathogenic role of the inflammasome in neurodegenerative diseases. J Neurochem 2015; 136 Suppl 1:29-38. [PMID: 26119245 DOI: 10.1111/jnc.13217] [Citation(s) in RCA: 224] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 05/29/2015] [Accepted: 06/05/2015] [Indexed: 12/16/2022]
Abstract
The inflammasome is a large macromolecular complex that contains multiple copies of a receptor or sensor of pathogen-derived or damage-derived molecular patterns, pro-caspase-1, and an adaptor called ASC (apoptotic speck containing protein with a CARD), which results in caspase-1 maturation. Caspase-1 then mediates the release of pro-inflammatory cytokines such as IL-1β and IL-18. These cytokines play critical roles in mediating immune responses during inflammation and innate immunity. Broader studies of the inflammasome over the years have implicated their roles in the pathogenesis of a variety of inflammatory diseases. Recently, studies have shown that the inflammasome modulates neuroinflammatory cells and the initial stages of neuroinflammation. A secondary cascade of events associated with neuroinflammation (such as oxidative stress) has been shown to activate the inflammasome, making the inflammasome a promising therapeutic target in the modulation of neurodegenerative diseases. This review will focus on the pathogenic role that inflammasomes play in neurologic diseases such as Alzheimer's disease, traumatic brain injury, and multiple sclerosis. We here review the role of the inflammasome in the pathogenesis of traumatic brain injury (TBI). TBI is initiated by physical force exerted to head, resulting in neuronal injury and death. Primary insult is followed by a secondary cascade of events following neuroinflammation such as mitochondrial dysfunction, production of reactive oxygen species, potassium effluxes, and release of circulating DNA. These events can potentially trigger the activation of NLRP3, NLRP1, and AIM2 during TBI but have yet to be confirmed (dashed lines). NLRP3, NLRP1, and AIM2 associate with the adaptor protein ASC, which initiates the cleavage of pro-caspase-1 to the mature form of caspase-1 which cleaves pro-IL-1β and pro-IL-18 into their mature forms of IL-1β and IL-18.
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Affiliation(s)
- Leslie C Freeman
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, USA.,Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Jenny P-Y Ting
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, USA.,Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, North Carolina, USA.,Department of Genetics, Department of Microbiology and Immunology, Institute of Inflammatory Diseases, Center for Translational Immunology, University of North Carolina, Chapel Hill, North Carolina, USA
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866
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Sumbul F, Acuner-Ozbabacan SE, Haliloglu T. Allosteric Dynamic Control of Binding. Biophys J 2015; 109:1190-201. [PMID: 26338442 DOI: 10.1016/j.bpj.2015.08.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 08/12/2015] [Accepted: 08/13/2015] [Indexed: 12/31/2022] Open
Abstract
Proteins have a highly dynamic nature and there is a complex interrelation between their structural dynamics and binding behavior. By assuming various conformational ensembles, they perform both local and global fluctuations to interact with other proteins in a dynamic infrastructure adapted to functional motion. Here, we show that there is a significant association between allosteric mutations, which lead to high-binding-affinity changes, and the hinge positions of global modes, as revealed by a large-scale statistical analysis of data in the Structural Kinetic and Energetic Database of Mutant Protein Interactions (SKEMPI). We further examined the mechanism of allosteric dynamics by conducting studies on human growth hormone (hGH) and pyrin domain (PYD), and the results show how mutations at the hinge regions could allosterically affect the binding-site dynamics or induce alternative binding modes by modifying the ensemble of accessible conformations. The long-range dissemination of perturbations in local chemistry or physical interactions through an impact on global dynamics can restore the allosteric dynamics. Our findings suggest a mechanism for the coupling of structural dynamics to the modulation of protein interactions, which remains a critical phenomenon in understanding the effect of mutations that lead to functional changes in proteins.
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Affiliation(s)
- Fidan Sumbul
- Department of Chemical Engineering and Polymer Research Center, Bogazici University, Istanbul, Turkey
| | | | - Turkan Haliloglu
- Department of Chemical Engineering and Polymer Research Center, Bogazici University, Istanbul, Turkey.
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867
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Antonopoulos C, Russo HM, El Sanadi C, Martin BN, Li X, Kaiser WJ, Mocarski ES, Dubyak GR. Caspase-8 as an Effector and Regulator of NLRP3 Inflammasome Signaling. J Biol Chem 2015; 290:20167-84. [PMID: 26100631 PMCID: PMC4536427 DOI: 10.1074/jbc.m115.652321] [Citation(s) in RCA: 157] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 06/12/2015] [Indexed: 12/20/2022] Open
Abstract
We recently described the induction of noncanonical IL-1β processing via caspase-8 recruited to ripoptosome signaling platforms in myeloid leukocytes. Here, we demonstrate that activated NLRP3·ASC inflammasomes recruit caspase-8 to drive IL-1β processing in murine bone marrow-derived dendritic cells (BMDC) independent of caspase-1 and -11. Sustained stimulation (>2 h) of LPS-primed caspase-1-deficient (Casp1/11(-/-)) BMDC with the canonical NLRP3 inflammasome agonist nigericin results in release of bioactive IL-1β in conjunction with robust caspase-8 activation. This IL-1β processing and caspase-8 activation do not proceed in Nlrp3(-/-) or Asc(-/-) BMDC and are suppressed by pharmacological inhibition of caspase-8, indicating that caspase-8 can act as a direct IL-1β-converting enzyme during NLRP3 inflammasome activation. In contrast to the rapid caspase-1-mediated death of wild type (WT) BMDC via NLRP3-dependent pyroptosis, nigericin-stimulated Casp1/11(-/-) BMDC exhibit markedly delayed cell death via NLRP3-dependent apoptosis. Biochemical analyses of WT and Casp1/11(-/-) BMDC indicated that caspase-8 is proteolytically processed within detergent-insoluble ASC-enriched protein complexes prior to extracellular export during nigericin treatment. Although nigericin-stimulated caspase-1 activation and activity are only modestly attenuated in caspase-8-deficient (Casp8(-/-)Rip3(-/-)) BMDC, these cells do not exhibit the rapid loss of viability of WT cells. These results support a contribution of caspase-8 to both IL-1β production and regulated death signaling via NLRP3 inflammasomes. In the absence of caspase-1, NLRP3 inflammasomes directly utilize caspase-8 as both a pro-apoptotic initiator and major IL-1β-converting protease. In the presence of caspase-1, caspase-8 acts as a positive modulator of the NLRP3-dependent caspase-1 signaling cascades that drive both IL-1β production and pyroptotic death.
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Affiliation(s)
| | - Hana M Russo
- Pathology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | | | - Bradley N Martin
- Pathology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, the Department of Immunology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, and
| | - Xiaoxia Li
- the Department of Immunology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, and
| | - William J Kaiser
- the Department of Microbiology and Immunology, Emory Vaccine Center, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Edward S Mocarski
- the Department of Microbiology and Immunology, Emory Vaccine Center, Emory University School of Medicine, Atlanta, Georgia 30322
| | - George R Dubyak
- Pathology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, From the Departments of Physiology and Biophysics and
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868
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de Almeida L, Khare S, Misharin AV, Patel R, Ratsimandresy RA, Wallin MC, Perlman H, Greaves DR, Hoffman HM, Dorfleutner A, Stehlik C. The PYRIN Domain-only Protein POP1 Inhibits Inflammasome Assembly and Ameliorates Inflammatory Disease. Immunity 2015; 43:264-76. [PMID: 26275995 DOI: 10.1016/j.immuni.2015.07.018] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 05/08/2015] [Accepted: 05/27/2015] [Indexed: 01/21/2023]
Abstract
In response to infections and tissue damage, ASC-containing inflammasome protein complexes are assembled that promote caspase-1 activation, IL-1β and IL-18 processing and release, pyroptosis, and the release of ASC particles. However, excessive or persistent activation of the inflammasome causes inflammatory diseases. Therefore, a well-balanced inflammasome response is crucial for the maintenance of homeostasis. We show that the PYD-only protein POP1 inhibited ASC-dependent inflammasome assembly by preventing inflammasome nucleation, and consequently interfered with caspase-1 activation, IL-1β and IL-18 release, pyroptosis, and the release of ASC particles. There is no mouse ortholog for POP1, but transgenic expression of human POP1 in monocytes, macrophages, and dendritic cells protected mice from systemic inflammation triggered by molecular PAMPs, inflammasome component NLRP3 mutation, and ASC danger particles. POP1 expression was regulated by TLR and IL-1R signaling, and we propose that POP1 provides a regulatory feedback loop that shuts down excessive inflammatory responses and thereby prevents systemic inflammation.
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Affiliation(s)
- Lucia de Almeida
- Division of Rheumatology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Sonal Khare
- Division of Rheumatology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Alexander V Misharin
- Division of Rheumatology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Rajul Patel
- Division of Rheumatology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Rojo A Ratsimandresy
- Division of Rheumatology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Melissa C Wallin
- Division of Rheumatology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Harris Perlman
- Division of Rheumatology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - David R Greaves
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
| | - Hal M Hoffman
- Division of Rheumatology, Allergy, and Immunology, Department of Pediatrics, School of Medicine, University of California at San Diego (UCSD) and San Diego Branch, Ludwig Institute of Cancer Research, La Jolla, CA 92093, USA
| | - Andrea Dorfleutner
- Division of Rheumatology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
| | - Christian Stehlik
- Division of Rheumatology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Robert H. Lurie Comprehensive Cancer Center, Interdepartmental Immunobiology Center and Skin Disease Research Center, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
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869
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GVHD-associated, inflammasome-mediated loss of function in adoptively transferred myeloid-derived suppressor cells. Blood 2015; 126:1621-8. [PMID: 26265697 DOI: 10.1182/blood-2015-03-634691] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 07/24/2015] [Indexed: 02/08/2023] Open
Abstract
Myeloid-derived suppressor cells (MDSCs) are a naturally occurring immune regulatory population associated with inhibition of ongoing inflammatory responses. In vitro generation of MDSCs from bone marrow has been shown to enhance survival in an acute model of lethal graft-versus-host disease (GVHD). However, donor MDSC infusion only partially ameliorates GVHD lethality. In order to improve the potential therapeutic benefit and ultimately survival outcomes, we set out to investigate the fate of MDSCs after transfer in the setting of acute GVHD (aGVHD). MDSCs transferred to lethally irradiated recipients of allogeneic donor hematopoietic grafts are exposed to an intense inflammatory environment associated with aGVHD, which we now show directly undermines their suppressive capacity. Under a conditioning regimen and GVHD inflammatory settings, MDSCs rapidly lose suppressor function and their potential to inhibit GVHD lethality, which is associated with their induced conversion toward a mature inflammasome-activated state. We find even brief in vitro exposure to inflammasome-activating mediators negates the suppressive potential of cultured murine and human-derived MDSCs. Consistent with a role for the inflammasome, donor MDSCs deficient in the adaptor ASC (apoptosis-associated speck-like protein containing a CARD), which assembles inflammasome complexes, conferred improved survival of mice developing GVHD compared with wild-type donor MDSCs. These data suggest the use of MDSCs as a therapeutic approach for preventing GVHD and other systemic inflammatory conditions will be more effective when combined with approaches limiting in vivo MDSC inflammasome activation, empowering MDSCs to maintain their suppressive potential.
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870
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Sahillioğlu AC, Özören N. Artificial Loading of ASC Specks with Cytosolic Antigens. PLoS One 2015; 10:e0134912. [PMID: 26258904 PMCID: PMC4530869 DOI: 10.1371/journal.pone.0134912] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 07/15/2015] [Indexed: 12/14/2022] Open
Abstract
Inflammasome complexes form upon interaction of Nod Like Receptor (NLR) proteins with pathogen associated molecular patterns (PAPMS) inside the cytosol. Stimulation of a subset of inflammasome receptors including NLRP3, NLRC4 and AIM2 triggers formation of the micrometer-sized spherical supramolecular complex called the ASC speck. The ASC speck is thought to be the platform of inflammasome activity, but the reason why a supramolecular complex is preferred against oligomeric platforms remains elusive. We observed that a set of cytosolic proteins, including the model antigen ovalbumin, tend to co-aggregate on the ASC speck. We suggest that co-aggregation of antigenic proteins on the ASC speck during intracellular infection might be instrumental in antigen presentation.
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Affiliation(s)
- Ali Can Sahillioğlu
- Apoptosis and Cancer Immunology Laboratory (AKiL), Department of Molecular Biology and Genetics, Bogazici University, Istanbul, Turkey
| | - Nesrin Özören
- Apoptosis and Cancer Immunology Laboratory (AKiL), Department of Molecular Biology and Genetics, Bogazici University, Istanbul, Turkey
- Life Sciences and Technologies Research Center, Bogazici University, Istanbul, Turkey
- * E-mail:
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871
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Abstract
The innate immune system provides early defense against infections and also plays a key role in monitoring alterations of homeostasis in the body. DNA is highly immunostimulatory, and recent advances in this field have led to the identification of the innate immune sensors responsible for the recognition of DNA as well as the downstream pathways that are activated. Moreover, information on how cells regulate DNA-driven immune responses to avoid excessive inflammation is now emerging. Finally, several reports have demonstrated how defects in DNA sensing, signaling, and regulation are associated with susceptibility to infections or inflammatory diseases in humans and model organisms. In this review, the current literature on DNA-stimulated innate immune activation is discussed, and important new questions facing this field are proposed.
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872
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Morrone SR, Matyszewski M, Yu X, Delannoy M, Egelman EH, Sohn J. Assembly-driven activation of the AIM2 foreign-dsDNA sensor provides a polymerization template for downstream ASC. Nat Commun 2015. [PMID: 26197926 PMCID: PMC4525163 DOI: 10.1038/ncomms8827] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
AIM2 recognizes foreign dsDNA and assembles into the inflammasome, a filamentous supramolecular signalling platform required to launch innate immune responses. We show here that the pyrin domain of AIM2 (AIM2PYD) drives both filament formation and dsDNA binding. In addition, the dsDNA-binding domain of AIM2 also oligomerizes and assists in filament formation. The ability to oligomerize is critical for binding dsDNA, and in turn permits the size of dsDNA to regulate the assembly of the AIM2 polymers. The AIM2PYD oligomers define the filamentous structure, and the helical symmetry of the AIM2PYD filament is consistent with the filament assembled by the PYD of the downstream adaptor ASC. Our results suggest that the role of AIM2PYD is not autoinhibitory, but generating a structural template by coupling ligand binding and oligomerization is a key signal transduction mechanism in the AIM2 inflammasome. The AIM2 inflammasome complex is essential for defence against a number of human pathogens but how it assembles upon recognition of foreign DNA remains incompletely understood. Here Morrone et al. suggest the AIM2 pyrin domain acts in both DNA binding and filament assembly to generate a structural template for complex assembly.
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Affiliation(s)
- Seamus R Morrone
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine Baltimore, Maryland 21205, USA
| | - Mariusz Matyszewski
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine Baltimore, Maryland 21205, USA
| | - Xiong Yu
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine Charlottesville, Virginia 22908, USA
| | - Michael Delannoy
- Microscope Core Facilities, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
| | - Edward H Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine Charlottesville, Virginia 22908, USA
| | - Jungsan Sohn
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine Baltimore, Maryland 21205, USA
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873
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Brough D, Rothwell NJ, Allan SM. Interleukin-1 as a pharmacological target in acute brain injury. Exp Physiol 2015; 100:1488-94. [PMID: 26096539 DOI: 10.1113/ep085135] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 05/04/2015] [Accepted: 06/05/2015] [Indexed: 12/13/2022]
Abstract
NEW FINDINGS What is the topic of this review? This review discusses the latest findings on the contribution of inflammation to brain injury, how inflammation is a therapeutic target, and details of recent and forthcoming clinical studies. What advances does it highlight? Here we highlight recent advances on the role and regulation of inflammasomes, and the latest clinical progress in targeting inflammation. Acute brain injury is one of the leading causes of mortality and disability worldwide. Despite this, treatments for acute brain injuries are limited, and there remains a massive unmet clinical need. Inflammation has emerged as a major contributor to non-communicable diseases, and there is now substantial and growing evidence that inflammation, driven by the cytokine interleukin-1 (IL-1), worsens acute brain injury. Interleukin-1 is regulated by large, multimolecular complexes called inflammasomes. Here, we discuss the latest research on the regulation of inflammasomes and IL-1 in the brain, preclinical efforts to establish the IL-1 system as a therapeutic target, and the promise of recent and future clinical studies on blocking the action of IL-1 for the treatment of brain injury.
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Affiliation(s)
- David Brough
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - Nancy J Rothwell
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - Stuart M Allan
- Faculty of Life Sciences, University of Manchester, Manchester, UK
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874
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Single-cell imaging of inflammatory caspase dimerization reveals differential recruitment to inflammasomes. Cell Death Dis 2015; 6:e1813. [PMID: 26158519 PMCID: PMC4650733 DOI: 10.1038/cddis.2015.186] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 05/22/2015] [Indexed: 01/08/2023]
Abstract
The human inflammatory caspases, including caspase-1, -4, -5 and -12, are considered as key regulators of innate immunity protecting from sepsis and numerous inflammatory diseases. Caspase-1 is activated by proximity-induced dimerization following recruitment to inflammasomes but the roles of the remaining inflammatory caspases in inflammasome assembly are unclear. Here, we use caspase bimolecular fluorescence complementation to visualize the assembly of inflammasomes and dimerization of inflammatory caspases in single cells. We observed caspase-1 dimerization induced by the coexpression of a range of inflammasome proteins and by lipospolysaccharide (LPS) treatment in primary macrophages. Caspase-4 and -5 were only dimerized by select inflammasome proteins, whereas caspase-12 dimerization was not detected by any investigated treatment. Strikingly, we determined that certain inflammasome proteins could induce heterodimerization of caspase-1 with caspase-4 or -5. Caspase-5 homodimerization and caspase-1/-5 heterodimerization was also detected in LPS-primed primary macrophages in response to cholera toxin subunit B. The subcellular localization and organization of the inflammasome complexes varied markedly depending on the upstream trigger and on which caspase or combination of caspases were recruited. Three-dimensional imaging of the ASC (apoptosis-associated speck-like protein containing a caspase recruitment domain)/caspase-1 complexes revealed a large spherical complex of ASC with caspase-1 dimerized on the outer surface. In contrast, NALP1 (NACHT leucine-rich repeat protein 1)/caspase-1 complexes formed large filamentous structures. These results argue that caspase-1, -4 or -5 can be recruited to inflammasomes under specific circumstances, often leading to distinctly organized and localized complexes that may impact the functions of these proteases.
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875
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Radian AD, Khare S, Chu LH, Dorfleutner A, Stehlik C. ATP binding by NLRP7 is required for inflammasome activation in response to bacterial lipopeptides. Mol Immunol 2015; 67:294-302. [PMID: 26143398 DOI: 10.1016/j.molimm.2015.06.013] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 06/11/2015] [Accepted: 06/15/2015] [Indexed: 02/07/2023]
Abstract
Nucleotide-binding oligimerization domain (NOD)-like receptors (NLRs) are pattern recognition receptors (PRRs) involved in innate immune responses. NLRs encode a central nucleotide-binding domain (NBD) consisting of the NAIP, CIITA, HET-E and TP1 (NACHT) domain and the NACHT associated domain (NAD), which facilitates receptor oligomerization and downstream inflammasome signaling. The NBD contains highly conserved regions, known as Walker motifs, that are required for nucleotide binding and hydrolysis. The NLR containing a PYRIN domain (PYD) 7 (NLRP7) has been recently shown to assemble an ASC and caspase-1-containing high molecular weight inflammasome complex in response to microbial acylated lipopeptides and Staphylococcus aureus infection. However, the molecular mechanism responsible for NLRP7 inflammasome activation is still elusive. Here we demonstrate that the NBD of NLRP7 is an ATP binding domain and has ATPase activity. We further show that an intact nucleotide-binding Walker A motif is required for NBD-mediated nucleotide binding and hydrolysis, oligomerization, and NLRP7 inflammasome formation and activity. Accordingly, THP-1 cells expressing a mutated Walker A motif display defective NLRP7 inflammasome activation, interleukin (IL)-1β release and pyroptosis in response to acylated lipopeptides and S. aureus infection. Taken together, our results provide novel insights into the mechanism of NLRP7 inflammasome assembly.
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Affiliation(s)
- Alexander D Radian
- Division of Rheumatology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Driskill Graduate Program in Life Sciences (DGP), Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Sonal Khare
- Division of Rheumatology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Lan H Chu
- Division of Rheumatology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Driskill Graduate Program in Life Sciences (DGP), Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Andrea Dorfleutner
- Division of Rheumatology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
| | - Christian Stehlik
- Division of Rheumatology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Robert H. Lurie Comprehensive Cancer Center, Interdepartmental Immunobiology Center and Skin Disease Research Center, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
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876
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Wang H, Lei X, Xiao X, Yang C, Lu W, Huang Z, Leng Q, Jin Q, He B, Meng G, Wang J. Reciprocal Regulation between Enterovirus 71 and the NLRP3 Inflammasome. Cell Rep 2015; 12:42-48. [DOI: 10.1016/j.celrep.2015.05.047] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 04/13/2015] [Accepted: 05/28/2015] [Indexed: 11/30/2022] Open
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877
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Abstract
The prokaryotic origins of the actin cytoskeleton have been firmly established, but it has become clear that the bacterial actins form a wide variety of different filaments, different both from each other and from eukaryotic F-actin. We have used electron cryomicroscopy (cryo-EM) to examine the filaments formed by the protein crenactin (a crenarchaeal actin) from Pyrobaculum calidifontis, an organism that grows optimally at 90 °C. Although this protein only has ∼ 20% sequence identity with eukaryotic actin, phylogenetic analyses have placed it much closer to eukaryotic actin than any of the bacterial homologs. It has been assumed that the crenactin filament is double-stranded, like F-actin, in part because it would be hard to imagine how a single-stranded filament would be stable at such high temperatures. We show that not only is the crenactin filament single-stranded, but that it is remarkably similar to each of the two strands in F-actin. A large insertion in the crenactin sequence would prevent the formation of an F-actin-like double-stranded filament. Further, analysis of two existing crystal structures reveals six different subunit-subunit interfaces that are filament-like, but each is different from the others in terms of significant rotations. This variability in the subunit-subunit interface, seen at atomic resolution in crystals, can explain the large variability in the crenactin filaments observed by cryo-EM and helps to explain the variability in twist that has been observed for eukaryotic actin filaments.
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878
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Guo H, Callaway JB, Ting JPY. Inflammasomes: mechanism of action, role in disease, and therapeutics. Nat Med 2015; 21:677-87. [PMID: 26121197 DOI: 10.1038/nm.3893] [Citation(s) in RCA: 2233] [Impact Index Per Article: 248.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 05/28/2015] [Indexed: 02/06/2023]
Abstract
The inflammasomes are innate immune system receptors and sensors that regulate the activation of caspase-1 and induce inflammation in response to infectious microbes and molecules derived from host proteins. They have been implicated in a host of inflammatory disorders. Recent developments have greatly enhanced our understanding of the molecular mechanisms by which different inflammasomes are activated. Additionally, increasing evidence in mouse models, supported by human data, strongly implicates an involvement of the inflammasome in the initiation or progression of diseases with a high impact on public health, such as metabolic disorders and neurodegenerative diseases. Finally, recent developments pointing toward promising therapeutics that target inflammasome activity in inflammatory diseases have been reported. This review will focus on these three areas of inflammasome research.
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Affiliation(s)
- Haitao Guo
- The Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Justin B Callaway
- The Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Jenny P-Y Ting
- 1] The Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA. [2] Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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879
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Caspase-8 scaffolding function and MLKL regulate NLRP3 inflammasome activation downstream of TLR3. Nat Commun 2015; 6:7515. [PMID: 26104484 PMCID: PMC4480782 DOI: 10.1038/ncomms8515] [Citation(s) in RCA: 185] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Accepted: 05/15/2015] [Indexed: 12/17/2022] Open
Abstract
TLR2 promotes NLRP3 inflammasome activation via an early MyD88-IRAK1-dependent pathway that provides a priming signal (signal 1) necessary for activation of the inflammasome by a second potassium-depleting signal (signal 2). Here we show that TLR3 binding to dsRNA promotes post-translational inflammasome activation through intermediate and late TRIF/RIPK1/FADD-dependent pathways. Both pathways require the scaffolding but not the catalytic function of caspase-8 or RIPK1. Only the late pathway requires kinase competent RIPK3 and MLKL function. Mechanistically, FADD/caspase-8 scaffolding function provides a post-translational signal 1 in the intermediate pathway, whereas in the late pathway it helps the oligomerization of RIPK3, which together with MLKL provides both signal 1 and 2 for inflammasome assembly. Cytoplasmic dsRNA activates NLRP3 independent of TRIF, RIPK1, RIPK3 or mitochondrial DRP1, but requires FADD/caspase-8 in wildtype macrophages to remove RIPK3 inhibition. Our study provides a comprehensive analysis of pathways that lead to NLRP3 inflammasome activation in response to dsRNA. Inflammasome activation requires a complex and incompletely understood network of signalling events. Here the authors characterize step-by-step contributions of TLR3, caspase-8, RIPK3 and MLKL to the activation of NLRP3 inflammasome in response to double-stranded RNA.
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880
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Lu A, Li Y, Yin Q, Ruan J, Yu X, Egelman E, Wu H. Plasticity in PYD assembly revealed by cryo-EM structure of the PYD filament of AIM2. Cell Discov 2015; 1. [PMID: 26583071 PMCID: PMC4646227 DOI: 10.1038/celldisc.2015.13] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Absent in melanoma 2 (AIM2) is an essential cytosolic double-stranded DNA receptor that assembles with the adaptor, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), and caspase-1 to form the AIM2 inflammasome, which leads to proteolytic maturation of cytokines and pyroptotic cell death. AIM2 contains an N-terminal Pyrin domain (PYD) that interacts with ASC through PYD/PYD interactions and nucleates ASCPYD filament formation. To elucidate the molecular basis of AIM2-induced ASCPYD polymerization, we generated AIM2PYD filaments fused to green fluorescent protein (GFP) and determined its cryo-electron microscopic (cryo-EM) structure. The map showed distinct definition of helices, allowing fitting of the crystal structure. Surprisingly, the GFP-AIM2PYD filament is a 1-start helix with helical parameters distinct from those of the 3-start ASCPYD filament. However, despite the apparent symmetry difference, helical net and detailed interface analyses reveal minimal changes in subunit packing. GFP-AIM2PYD nucleated ASCPYD filament formation in comparable efficiency as untagged AIM2PYD, suggesting assembly plasticity in both AIM2PYD and ASCPYD. The DNA-binding domain of AIM2 is able to form AIM2/DNA filaments, within which the AIM2PYD is brought into proximity to template ASCPYD filament assembly. Because ASC is able to interact with many PYD-containing receptors for the formation of inflammasomes, the observed structural plasticity may be critically important for this versatility in the PYD/PYD interactions.
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Affiliation(s)
- Alvin Lu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA ; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
| | - Yang Li
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA ; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
| | - Qian Yin
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA ; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
| | - Jianbin Ruan
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA ; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
| | - Xiong Yu
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA, USA
| | - Edward Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA, USA
| | - Hao Wu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA ; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
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881
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Wu B, Hur S. How RIG-I like receptors activate MAVS. Curr Opin Virol 2015; 12:91-8. [PMID: 25942693 PMCID: PMC4470786 DOI: 10.1016/j.coviro.2015.04.004] [Citation(s) in RCA: 153] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 03/26/2015] [Accepted: 04/16/2015] [Indexed: 12/22/2022]
Abstract
RIG-I and MDA5 are well-conserved cytoplasmic pattern recognition receptors that detect viral RNAs during infection and activate the type I interferon (IFN)-mediated antiviral immune response. While much is known about how these receptors recognize viral RNAs, how they interact with their common signaling adaptor molecule MAVS and activate the downstream signaling pathway had been less clear. Previous studies have shown that the signaling domains (tandem CARDs or 2CARDs) of RIG-I and MDA5 must form homo-oligomers in order to interact with MAVS, and that their interactions lead to filament formation of MAVS, a pre-requisite for downstream signal activation. More recent data suggest that multiple mechanisms synergistically promote tetramer formation of RIG-I 2CARD, and that this tetramer resembles a lock-washer, which serves as a helical template to nucleate the MAVS filament. We here summarize these recent findings and discuss the current understanding of the signal activation mechanisms of RIG-I and MDA5.
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Affiliation(s)
- Bin Wu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, United States; Program in Cellular and Molecular Medicine, Boston Children's Hospital, United States
| | - Sun Hur
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, United States; Program in Cellular and Molecular Medicine, Boston Children's Hospital, United States.
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882
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Zhu W, Luo ZQ. A new way to detect the danger: Lysosomal cell death induced by a bacterial ribosomal protein. JOURNAL OF NATURE AND SCIENCE 2015; 1:e107. [PMID: 26052550 PMCID: PMC4457467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The death of immune cells in response to pathogens often dictates the outcome of an infection. In some contexts, pathogens specifically kill immune cells by producing highly potent toxins or by triggering host cell death pathways, thus ensuring successful infections. But for intracellular pathogens and viruses, the death of host cells normally is disastrous for their intracellular life cycle. Our recent experiments with the pathogen Legionella pneumophila revealed that the bacterial ribosomal protein RpsL is able to trigger lysosomal membrane permeabilization (LMP) and the subsequent macrophage cell death. Interestingly, a lysine to arginine mutation at the 88th residue, which also confers resistance to the antibiotic streptomycin, substantially impaired the cell death inducing activity of RpsL and allowed L. pneumophila to succeed in intracellular replication, suggesting the convergence of resistance mechanisms to innate immunity and antibiotics. The discovery of lysosomal cell death as an immune response to a bacterial ligand has expanded the spectrum of reactions that host cells can mount against bacterial infection; these observations provide a model to study the pathways that lead to the induction of LMP, a currently poorly understood cellular process involved in the development of many diseases.
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883
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Parry TL, Melehani JH, Ranek MJ, Willis MS. Functional Amyloid Signaling via the Inflammasome, Necrosome, and Signalosome: New Therapeutic Targets in Heart Failure. Front Cardiovasc Med 2015; 2:25. [PMID: 26664897 PMCID: PMC4671334 DOI: 10.3389/fcvm.2015.00025] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2015] [Accepted: 04/28/2015] [Indexed: 11/13/2022] Open
Abstract
As the most common cause of death and disability, globally, heart disease remains an incompletely understood enigma. A growing number of cardiac diseases are being characterized by the presence of misfolded proteins underlying their pathophysiology, including cardiac amyloidosis and dilated cardiomyopathy (DCM). At least nine precursor proteins have been implicated in the development of cardiac amyloidosis, most commonly caused by multiple myeloma light chain disease and disease-causing mutant or wildtype transthyretin (TTR). Similarly, aggregates with PSEN1 and COFILIN-2 have been identified in up to one-third of idiopathic DCM cases studied, indicating the potential predominance of misfolded proteins in heart failure. In this review, we present recent evidence linking misfolded proteins mechanistically with heart failure and present multiple lines of new therapeutic approaches that target the prevention of misfolded proteins in cardiac TTR amyloid disease. These include multiple small molecule pharmacological chaperones now in clinical trials designed specifically to support TTR folding by rational design, such as tafamidis, and chaperones previously developed for other purposes, such as doxycycline and tauroursodeoxycholic acid. Last, we present newly discovered non-pathological "functional" amyloid structures, such as the inflammasome and necrosome signaling complexes, which can be activated directly by amyloid. These may represent future targets to successfully attenuate amyloid-induced proteotoxicity in heart failure, as the inflammasome, for example, is being therapeutically inhibited experimentally in autoimmune disease. Together, these studies demonstrate multiple novel points in which new therapies may be used to primarily prevent misfolded proteins or to inhibit their downstream amyloid-mediated effectors, such as the inflammasome, to prevent proteotoxicity in heart failure.
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Affiliation(s)
- Traci L Parry
- McAllister Heart Institute, University of North Carolina , Chapel Hill, NC , USA
| | - Jason H Melehani
- Department of Pharmacology, University of North Carolina , Chapel Hill, NC , USA
| | - Mark J Ranek
- Section of Cardiology, Department of Medicine, The Institute for CardioScience, Johns Hopkins Medical Institutes , Baltimore, MD , USA
| | - Monte S Willis
- McAllister Heart Institute, University of North Carolina , Chapel Hill, NC , USA ; Department of Pathology and Laboratory Medicine, University of North Carolina , Chapel Hill, NC , USA
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884
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Inflammasomes-dependent regulation of IL-1β secretion induced by the virulent Mycobacterium bovis Beijing strain in THP-1 macrophages. Antonie van Leeuwenhoek 2015; 108:163-71. [DOI: 10.1007/s10482-015-0475-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 05/08/2015] [Indexed: 12/13/2022]
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885
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Abstract
Aging is the greatest risk factor for the development of chronic diseases such as arthritis, type 2 diabetes, cardiovascular disease, kidney disease, Alzheimer's disease, macular degeneration, frailty, and certain forms of cancers. It is widely regarded that chronic inflammation may be a common link in all these age-related diseases. This raises the question, can one alter the course of aging and potentially slow the development of all chronic diseases by manipulating the mechanisms that cause age-related inflammation? Emerging evidence suggests that pro-inflammatory cytokines interleukin-1 (IL-1) and IL-18 show an age-dependent regulation implicating inflammasome-mediated caspase-1 activation in the aging process. The Nod-like receptor (NLR) family of innate immune cell sensors, such as the nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) inflammasome controls the caspase-1 activation in myeloid-lineage cells in several organs during aging. The NLRP3 inflammasome is especially relevant to aging as it can get activated in response to structurally diverse damage-associated molecular patterns (DAMPs) such as extracellular ATP, excess glucose, ceramides, amyloids, urate, and cholesterol crystals, all of which increase with age. Interestingly, reduction in NLRP3-mediated inflammation prevents age-related insulin resistance, bone loss, cognitive decline, and frailty. NLRP3 is a major driver of age-related inflammation and therefore dietary or pharmacological approaches to lower aberrant inflammasome activation holds promise in reducing multiple chronic diseases of age and may enhance healthspan.
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Affiliation(s)
- Emily L. Goldberg
- Section of Comparative Medicine, Yale School of Medicine, New Haven, CT, USA
- Department of Immunobiology, Yale School of Medicine, New Haven, CT, USA
| | - Vishwa Deep Dixit
- Section of Comparative Medicine, Yale School of Medicine, New Haven, CT, USA
- Department of Immunobiology, Yale School of Medicine, New Haven, CT, USA
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886
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Kudryashev M, Wang RYR, Brackmann M, Scherer S, Maier T, Baker D, DiMaio F, Stahlberg H, Egelman EH, Basler M. Structure of the type VI secretion system contractile sheath. Cell 2015; 160:952-962. [PMID: 25723169 DOI: 10.1016/j.cell.2015.01.037] [Citation(s) in RCA: 178] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 11/17/2014] [Accepted: 01/20/2015] [Indexed: 12/15/2022]
Abstract
Bacteria use rapid contraction of a long sheath of the type VI secretion system (T6SS) to deliver effectors into a target cell. Here, we present an atomic-resolution structure of a native contracted Vibrio cholerae sheath determined by cryo-electron microscopy. The sheath subunits, composed of tightly interacting proteins VipA and VipB, assemble into a six-start helix. The helix is stabilized by a core domain assembled from four β strands donated by one VipA and two VipB molecules. The fold of inner and middle layers is conserved between T6SS and phage sheaths. However, the structure of the outer layer is distinct and suggests a mechanism of interaction of the bacterial sheath with an accessory ATPase, ClpV, that facilitates multiple rounds of effector delivery. Our results provide a mechanistic insight into assembly of contractile nanomachines that bacteria and phages use to translocate macromolecules across membranes.
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Affiliation(s)
- Mikhail Kudryashev
- Focal Area Infection Biology, Biozentrum, University of Basel, Klingelbergstrasse 50/70, CH-4056 Basel, Switzerland; Center for Cellular Imaging and NanoAnalytics, Biozentrum, University of Basel, Mattenstrasse 26, CH-4058 Basel, Switzerland
| | - Ray Yu-Ruei Wang
- Department of Biochemistry, University of Washington, 1705 NE Pacific Street, Seattle, WA 98195, USA; Graduate Program in Biological Physics, Structure and Design, University of Washington, Box 357350, Seattle, WA 98195, USA
| | - Maximilian Brackmann
- Focal Area Infection Biology, Biozentrum, University of Basel, Klingelbergstrasse 50/70, CH-4056 Basel, Switzerland
| | - Sebastian Scherer
- Center for Cellular Imaging and NanoAnalytics, Biozentrum, University of Basel, Mattenstrasse 26, CH-4058 Basel, Switzerland
| | - Timm Maier
- Focal Area Structural Biology, Biozentrum, University of Basel, Klingelbergstrasse 50/70, CH-4056 Basel, Switzerland
| | - David Baker
- Department of Biochemistry, University of Washington, 1705 NE Pacific Street, Seattle, WA 98195, USA
| | - Frank DiMaio
- Department of Biochemistry, University of Washington, 1705 NE Pacific Street, Seattle, WA 98195, USA
| | - Henning Stahlberg
- Center for Cellular Imaging and NanoAnalytics, Biozentrum, University of Basel, Mattenstrasse 26, CH-4058 Basel, Switzerland
| | - Edward H Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA.
| | - Marek Basler
- Focal Area Infection Biology, Biozentrum, University of Basel, Klingelbergstrasse 50/70, CH-4056 Basel, Switzerland.
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887
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Shin S, Brodsky IE. The inflammasome: Learning from bacterial evasion strategies. Semin Immunol 2015; 27:102-10. [PMID: 25914126 DOI: 10.1016/j.smim.2015.03.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 03/12/2015] [Indexed: 01/01/2023]
Abstract
The innate immune system plays a critical role in defense against microbial infection and employs germline-encoded pattern recognition receptors to detect broadly conserved microbial structures or activities. Pattern recognition receptors of the nucleotide binding domain/leucine rich repeat (NLR) family respond to particular microbial products or disruption of cellular physiology, and mediate the activation of an arm of the innate immune response termed the inflammasome. Inflammasomes are multiprotein complexes that are inducibly assembled in response to the contamination of the host cell cytosol by microbial products. Individual NLRs sense the presence of their cognate stimuli, and initiate assembly of inflammasomes via the adaptor protein apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) and the effector pro-enzyme caspase-1. Inflammasome activation leads to rapid release of pro-inflammatory mediators of the IL-1 family as well as the release of intracellular alarmins due to a lytic form of programmed cell death termed pyroptosis. Over the past 15 years, a great deal has been learned about the mechanisms that drive inflammasome activation in response to infection by diverse pathogens. However, pathogens have also evolved mechanisms to evade or suppress host defenses, and the mechanisms by which pathogens evade inflammasome activation are not well-understood. Here, we will discuss emerging evidence on how diverse pathogens evade inflammasome activation, and what these studies have revealed about inflammasome biology. Deeper understanding of pathogen evasion of inflammasome activation has the potential to lead to development of novel classes of immunomodulatory factors that could be used in the context of human inflammatory diseases.
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Affiliation(s)
- Sunny Shin
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - Igor E Brodsky
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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888
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Karasawa T, Kawashima A, Usui F, Kimura H, Shirasuna K, Inoue Y, Komada T, Kobayashi M, Mizushina Y, Sagara J, Takahashi M. Oligomerized CARD16 promotes caspase-1 assembly and IL-1β processing. FEBS Open Bio 2015; 5:348-56. [PMID: 25973362 PMCID: PMC4420773 DOI: 10.1016/j.fob.2015.04.011] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 04/17/2015] [Accepted: 04/17/2015] [Indexed: 12/26/2022] Open
Abstract
CARD16 is the most abundant CARD-only protein in hematopoietic cells. Unlike CARD17, CARD16 oligomerizes to form a filament-like structure. The filament-like structure formed by CARD16 promotes caspase 1 (CASP1) assembly. CASP1-dependent IL-1β processing is enhanced by CARD16. CARD16 colocalizes in ASC-speck by interacting with ASC.
Increasing evidence indicates that caspase recruitment domain (CARD)-mediated caspase-1 (CASP1) assembly is an essential process for its activation and subsequent interleukin (IL)-1β release, leading to the initiation of inflammation. Both CARD16 and CARD17 were previously reported as inhibitory homologs of CASP1; however, their molecular function remains unclear. Here, we identified that oligomerization activity allows CARD16 to function as a CASP1 activator. We investigated the molecular characteristics of CARD16 and CARD17 in transiently transfected HeLa cells. Although both CARD16 and CARD17 interacted with CASP1CARD, only CARD16 formed a homo-oligomer. Oligomerized CARD16 formed a filament-like structure with CASP1CARD and a speck with apoptosis-associated speck-like protein containing a CARD. A filament-like structure formed by CARD16 promoted CASP1 filament assembly and IL-1β release. In contrast, CARD17 did not form a homo-oligomer or filaments and inhibited CASP1-dependent IL-1β release. Mutated CARD16D27G, mimicking the CARD17 amino acid sequence, formed a homo-oligomer but failed to form a filament-like structure. Consequently, CARD16D27G weakly promoted CASP1 filament assembly and subsequent IL-1β release. These results suggest that oligomerized CARD16 promotes CARD-mediated molecular assembly and CASP1 activation.
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Key Words
- ANOVA, analysis of variance
- ASC, apoptosis-associated speck-like protein containing a caspase recruitment domain
- BS3, bis(sulfosccinimidyl)suberate
- Bcl10, B-cell lymphoma/leukemia 10
- CARD, caspase recruitment domain
- CARMA1, CARD-membrane-associated guanylate kinase 1
- CASP1, caspase-1
- COPs, CARD-only proteins
- Caspase
- Cytokine
- ELISA, enzyme-linked immunosorbent assay
- FCS, fetal calf serum
- IL, interleukin
- Inflammation
- Interleukin
- LPS, lipopolysaccharide
- LRRs, leucine-rich repeats
- NF-κB, nuclear factor kappa beta
- NLRs, nucleotide-binding domain leucine-rich repeat containing receptors
- PYD, pyrin domain
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Affiliation(s)
- Tadayoshi Karasawa
- Division of Inflammation Research, Center for Molecular Medicine, Jichi Medical University, Tochigi, Japan
- Corresponding authors at: Division of Inflammation Research, Center for Molecular Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan. Tel.: +81 285 58 7446; fax: +81 285 44 5365.
| | - Akira Kawashima
- Division of Inflammation Research, Center for Molecular Medicine, Jichi Medical University, Tochigi, Japan
| | - Fumitake Usui
- Division of Inflammation Research, Center for Molecular Medicine, Jichi Medical University, Tochigi, Japan
| | - Hiroaki Kimura
- Division of Inflammation Research, Center for Molecular Medicine, Jichi Medical University, Tochigi, Japan
| | - Koumei Shirasuna
- Division of Inflammation Research, Center for Molecular Medicine, Jichi Medical University, Tochigi, Japan
| | - Yoshiyuki Inoue
- Division of Inflammation Research, Center for Molecular Medicine, Jichi Medical University, Tochigi, Japan
| | - Takanori Komada
- Division of Inflammation Research, Center for Molecular Medicine, Jichi Medical University, Tochigi, Japan
| | - Motoi Kobayashi
- Division of Inflammation Research, Center for Molecular Medicine, Jichi Medical University, Tochigi, Japan
| | - Yoshiko Mizushina
- Division of Inflammation Research, Center for Molecular Medicine, Jichi Medical University, Tochigi, Japan
| | - Junji Sagara
- Department of Molecular Oncology, Shinshu University Graduate School of Medicine, Nagano, Japan
| | - Masafumi Takahashi
- Division of Inflammation Research, Center for Molecular Medicine, Jichi Medical University, Tochigi, Japan
- Corresponding authors at: Division of Inflammation Research, Center for Molecular Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan. Tel.: +81 285 58 7446; fax: +81 285 44 5365.
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889
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Egelman EH. Three-dimensional reconstruction of helical polymers. Arch Biochem Biophys 2015; 581:54-8. [PMID: 25912526 DOI: 10.1016/j.abb.2015.04.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 04/06/2015] [Accepted: 04/14/2015] [Indexed: 11/18/2022]
Abstract
The field of three-dimensional electron microscopy began more than 45years ago with a reconstruction of a helical phage tail, and helical polymers continue to be important objects for three-dimensional reconstruction due to the centrality of helical protein and nucleoprotein polymers in all aspects of biology. We are now witnessing a fundamental revolution in this area, made possible by direct electron detectors, which has led to near-atomic resolution for a number of important helical structures. Most importantly, the possibility of achieving such resolution routinely for a vast number of helical samples is within our reach. One of the main problems in helical reconstruction, ambiguities in assigning the helical symmetry, is overcome when one reaches a resolution where secondary structure is clearly visible. However, obstacles still exist due to the intrinsic variability within many helical filaments.
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Affiliation(s)
- Edward H Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia, Box 800733, Charlottesville, VA 22908, USA.
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890
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Jung YJ, Jun HK, Choi BK. Contradictory roles ofPorphyromonas gingivalisgingipains in caspase-1 activation. Cell Microbiol 2015; 17:1304-19. [DOI: 10.1111/cmi.12435] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Revised: 02/23/2015] [Accepted: 03/07/2015] [Indexed: 02/07/2023]
Affiliation(s)
- Young-Jung Jung
- Department of Oral Microbiology and Immunology, School of Dentistry; Seoul National University; 101 Daehak-ro, Jongno-gu Seoul 110-749 Korea
| | - Hye-Kyoung Jun
- Department of Oral Microbiology and Immunology, School of Dentistry; Seoul National University; 101 Daehak-ro, Jongno-gu Seoul 110-749 Korea
| | - Bong-Kyu Choi
- Department of Oral Microbiology and Immunology, School of Dentistry; Seoul National University; 101 Daehak-ro, Jongno-gu Seoul 110-749 Korea
- Dental Research Institute; Seoul National University; Seoul Korea
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891
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The hierarchical structural architecture of inflammasomes, supramolecular inflammatory machines. Curr Opin Struct Biol 2015; 31:75-83. [PMID: 25881155 DOI: 10.1016/j.sbi.2015.03.014] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 03/12/2015] [Accepted: 03/31/2015] [Indexed: 12/22/2022]
Abstract
Inflammasomes are caspase-1 activating, molecular inflammatory machines that proteolytically mature pro-inflammatory cytokines and induce pyroptotic cell death during innate immune responses. Recent structural studies of proteins that constitute inflammasomes have yielded fresh insights into their assembly mechanisms. In particular, these include a crystal structure of the CARD-containing NOD-like receptor NLRC4, the crystallographic and electron microscopy (EM) studies of the dsDNA sensors AIM2 and IFI16, and of the regulatory protein p202, and the cryo-EM filament structure of the PYD domain of the inflammasome adapter ASC. These data suggest inflammasome assembly that starts with ligand recognition and release of autoinhibition followed by step-wise rounds of nucleated polymerization from the sensors to the adapters, then to caspase-1. In this elegant manner, inflammasomes form by an 'all-or-none' cooperative mechanism, thereby amplifying the activation of caspase-1. The dense network of filamentous structures predicted by this model has been observed in cells as micron-sized puncta.
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892
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De Nardo D. Toll-like receptors: Activation, signalling and transcriptional modulation. Cytokine 2015; 74:181-9. [PMID: 25846205 DOI: 10.1016/j.cyto.2015.02.025] [Citation(s) in RCA: 289] [Impact Index Per Article: 32.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 02/26/2015] [Indexed: 02/06/2023]
Abstract
Families of innate immune receptors serve as the bodies primary defence system by recognising and rapidly responding to infection by microorganisms or to endogenous danger signals and initiating inflammatory processes. Whilst Toll-like receptors (TLRs) were the first family to be discovered, important and exciting discoveries continue to emerge into the molecular mechanisms that control their activation and regulation. Herein, I will provide an overview of TLR activation and their downstream signalling cascades, and discuss some of the recent findings concerning the assembly of a TLR oligomeric signalling platform, known as the Myddosome. Further, a brief examination of the importance of crosstalk between multiple TLRs or between TLRs and other innate immune receptors for appropriate and coordinated immune responses will be presented. Finally, I will discuss the importance of mechanisms that regulate TLRs with a focus on the role of activating transcription factor 3 (ATF3) in modulating transcriptional responses downstream of TLRs.
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Affiliation(s)
- Dominic De Nardo
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3050, Australia.
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893
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Schröder GF. Hybrid methods for macromolecular structure determination: experiment with expectations. Curr Opin Struct Biol 2015; 31:20-7. [DOI: 10.1016/j.sbi.2015.02.016] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 02/22/2015] [Accepted: 02/26/2015] [Indexed: 12/15/2022]
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894
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Choi JY, Kim CM, Seo EK, Bhat EA, Jang TH, Lee JH, Park HH. Crystal structure of human POP1 and its distinct structural feature for PYD domain. Biochem Biophys Res Commun 2015; 460:957-63. [PMID: 25839653 DOI: 10.1016/j.bbrc.2015.03.134] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 03/24/2015] [Indexed: 01/20/2023]
Abstract
Inflammatory caspases, such as caspase-1, which is critical for the innate immune response, are activated upon the formation of a molecular complex called the inflammasome. The inflammasome is composed of three proteins, the Nod-like receptor (NLRP, NLRC or AIM2), apoptosis associated speck-loke protein containing a caspase-recruitment domain (ASC), and caspase-1. ASC is an adaptor molecule that contains an N-terminal PYD domain and a C-terminal CARD domain for interaction with other proteins. Upon activation, the N-terminal PYD of ASC homotypically interacts with the PYD domain of the Nod-like receptor, while its C-terminal CARD homotypically interacts with the CARD domain of caspase-1. PYD only protein 1 (POP1) negatively regulates inflammatory response by blocking the formation of the inflammasome. POP1 directly binds to ASC via a PYD:PYD interaction, thereby preventing ASC recruitment to Nod-like receptor NLRPs. POP1-mediated regulation of inflammation is of great biological importance. Here, we report the crystal structure of human POP1 and speculate about the inhibitory mechanism of POP1-mediated inflammasome formation based on the current structure.
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Affiliation(s)
- Jae Young Choi
- School of Biotechnology and Graduate School of Biochemistry at Yeungnam University, Gyeongsan 712-749, South Korea
| | - Chang Min Kim
- School of Biotechnology and Graduate School of Biochemistry at Yeungnam University, Gyeongsan 712-749, South Korea
| | - Eun Kyung Seo
- School of Biotechnology and Graduate School of Biochemistry at Yeungnam University, Gyeongsan 712-749, South Korea
| | - Eijaz Ahmed Bhat
- School of Biotechnology and Graduate School of Biochemistry at Yeungnam University, Gyeongsan 712-749, South Korea
| | - Tae-Ho Jang
- School of Biotechnology and Graduate School of Biochemistry at Yeungnam University, Gyeongsan 712-749, South Korea
| | - Jun Hyuck Lee
- Division of Polar Life Sciences, Korea Polar Research Institute, Incheon 406-840, Republic of Korea; Department of Polar Sciences, Korea University of Science and Technology, Incheon 406-840, Republic of Korea
| | - Hyun Ho Park
- School of Biotechnology and Graduate School of Biochemistry at Yeungnam University, Gyeongsan 712-749, South Korea.
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895
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Li Z, Liu G, Sun L, Teng Y, Guo X, Jia J, Sha J, Yang X, Chen D, Sun Q. PPM1A regulates antiviral signaling by antagonizing TBK1-mediated STING phosphorylation and aggregation. PLoS Pathog 2015; 11:e1004783. [PMID: 25815785 PMCID: PMC4376777 DOI: 10.1371/journal.ppat.1004783] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 03/03/2015] [Indexed: 12/12/2022] Open
Abstract
Stimulator of interferon genes (STING, also known as MITA and ERIS) is critical in protecting the host against DNA pathogen invasion. However, the molecular mechanism underlying the regulation of STING remains unclear. Here, we show that PPM1A negatively regulates antiviral signaling by targeting STING in its phosphatase activity-dependent manner, and in a line with this, PPM1A catalytically dephosphorylates STING and TBK1 in vitro. Importantly, we provide evidence that whereas TBK1 promotes STING aggregation in a phosphorylation-dependent manner, PPM1A antagonizes STING aggregation by dephosphorylating both STING and TBK1, emphasizing that phosphorylation is crucial for the efficient activation of STING. Our findings demonstrate a novel regulatory circuit in which STING and TBK1 reciprocally regulate each other to enable efficient antiviral signaling activation, and PPM1A dephosphorylates STING and TBK1, thereby balancing this antiviral signal transduction. Innate antiviral immunity is essential for the host defense system that rapidly detects and eliminates invading viruses. STING, an endoplasmic reticulum (ER)-associated protein, plays important roles in the activation of type I IFN in response to DNA virus infection. Whereas excessive activation of STING can potentially cause lethal inflammatory diseases, STING activity must thus be precisely controlled to ensure the proper antiviral signaling transduction. However, the mechanisms of how STING activation is regulated are not fully understood. In this study, we find that PPM1A physically interacts with STING and negatively regulates STING-mediated antiviral signaling. Mechanistically, we find that PPM1A functions as a phosphatase that targets both STING and TBK1 for their dephosphorylation. Moreover, our study demonstrates that while TBK1 enhances STING aggregation in a kinase activity-dependent manner, PPM1A suppresses STING aggregation by dephosphorylating both STING and TBK1. Collectively, our study not only reveals that STING and TBK1 reciprocally regulate each other’s activity to elicit antiviral signaling, but also shows that PPM1A antagonizes STING aggregation by targeting both STING and TBK1, thereby maintaining proper antiviral responses.
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Affiliation(s)
- Zexing Li
- State Key Laboratory of Biomembrane and Membrane Biotechnology, Chinese Academy of Sciences, Chaoyang District, Beijing, China
| | - Ge Liu
- State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Chaoyang District, Beijing, China
| | - Liwei Sun
- State Key Laboratory of Biomembrane and Membrane Biotechnology, Chinese Academy of Sciences, Chaoyang District, Beijing, China
| | - Yan Teng
- State Key Laboratory of Proteomics, Genetic Laboratory of Development and Diseases, Institute of Biotechnology, Beijing, China
| | - Xuejiang Guo
- State Key Laboratory of Reproductive Medicine, Department of Histology and Embryology, Nanjing Medical University, Nanjing, China
| | - Jianhang Jia
- Markey Cancer Center, Department of Molecular and Cellular Biochemistry, The University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Jiahao Sha
- State Key Laboratory of Reproductive Medicine, Department of Histology and Embryology, Nanjing Medical University, Nanjing, China
| | - Xiao Yang
- State Key Laboratory of Proteomics, Genetic Laboratory of Development and Diseases, Institute of Biotechnology, Beijing, China
| | - Dahua Chen
- State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Chaoyang District, Beijing, China
| | - Qinmiao Sun
- State Key Laboratory of Biomembrane and Membrane Biotechnology, Chinese Academy of Sciences, Chaoyang District, Beijing, China
- * E-mail:
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896
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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.
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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.
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897
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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.
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898
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Affiliation(s)
- Alain Filloux
- Alain Filloux, MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK; E-mail:
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899
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Abstract
All aspects of the pathogenesis of atherosclerosis are critically influenced by the inflammatory response in vascular plaques. Research in the field of innate immunity from the past 2 decades has uncovered many novel mechanisms elucidating how immune cells sense microbes, tissue damage, and metabolic derangements. Here, we summarize which triggers of innate immunity appear during atherogenesis and by which pathways they can contribute to inflammation in atherosclerotic plaques. The increased understanding gained from studies assessing how immune activation is associated with the pathogenesis of atherosclerosis has provided many novel targets for potential therapeutic intervention. Excitingly, the concept that inflammation may be the core of cardiovascular disease is currently being clinically evaluated and will probably encourage further studies in this area.
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Affiliation(s)
- Sebastian Zimmer
- From the Medizinische Klinik und Poliklinik II (S.Z.) and Institute of Innate Immunity (A.G., E.L.), University Hospitals Bonn, Bonn, Germany; Department of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester (E.L.); and German Center of Neurodegenerative Diseases (DZNE), Bonn, Germany (E.L.)
| | - Alena Grebe
- From the Medizinische Klinik und Poliklinik II (S.Z.) and Institute of Innate Immunity (A.G., E.L.), University Hospitals Bonn, Bonn, Germany; Department of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester (E.L.); and German Center of Neurodegenerative Diseases (DZNE), Bonn, Germany (E.L.)
| | - Eicke Latz
- From the Medizinische Klinik und Poliklinik II (S.Z.) and Institute of Innate Immunity (A.G., E.L.), University Hospitals Bonn, Bonn, Germany; Department of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester (E.L.); and German Center of Neurodegenerative Diseases (DZNE), Bonn, Germany (E.L.).
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900
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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: 198] [Impact Index Per Article: 22.0] [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.
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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
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