TLR4 Signalling

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RESEA r CH HIGHLIGHTS INNATE IMMUNITY TLR4 signalling Toll-like receptor 4 (TLR4) is unique plasma membrane. Now, a study from sufficient to allow TRAM to localize among TLRs in its ability to activate Ruslan Medzhitov’s laboratory shows specifically to endosomes. These 20 two distinct signalling pathways that the two signalling pathways amino acids constitute a bipartite — one pathway is activated by the are induced sequentially and that localization domain — consisting of adaptors TIRAP (Toll/interleukin-1- the TRAM–TRIF pathway is only a myristoylation motif (the first 7 receptor (TIR)-domain-containing operational from early endosomes amino acids) and a polybasic domain adaptor protein) and MyD88, following endocytosis of TLR4. — that is commonly found in other which leads to the induction of The authors found it puzzling proteins that shuttle between the pro‑inflammatory cytokines, and that TLR4 is the only known TLR plasma membrane and endosomes. the second pathway is activated by capable of inducing the production Mutational analysis showed that the the adaptors TRIF (TIR-domain- of type I interferons from the plasma myristoylation motif is necessary containing adaptor protein inducing membrane so they decided to take for endosomal localization but interferon‑β) and TRAM (TRIF- a closer look at TLR4 signalling. both parts of the bipartite motif related adaptor molecule), which First, they assessed the subcellular are required for plasma-membrane leads to the induction of type I inter- localization of tagged TLR4 and found targeting. A TRAM transgene of ferons. Until now, it had been believed that it localized to both the plasma which the protein product resided that these two signalling pathways membrane and endosomal vesicles. specifically on endosomes retained were activated simultaneously at the They found that lipopolysaccharide- the ability to signal the production of induced TLR4 internalization was type I interferons. disrupted in the presence of a specific This study supports a model inhibitor of dynamin — a GTPase whereby ligand engagement of TLR4 that regulates the endocytosis of at the plasma membrane induces the ‘pinched-off’ invaginations of the TIRAP–MyD88 pathway. TLR4 is plasma membrane. Disruption of then endocytosed into endosomes to endocytosis abolished the TRAM– engage the TRAM–TRIF pathway. TRIF-dependent phosphorylation of These results also confirm that interferon-regulatory factor 3 (IRF3), TRAM, similar to TIRAP, is a ‘sorting’ a component of the pathway that leads adaptor that defines the location of to the production of type I interferons, subcellular TLR signalling, and that whereas TIRAP–MyD88-dependent receptors that induce the production signalling proceeded normally. of type I interferons all signal from Next, a deletional analysis of intracellular compartments. TRAM showed that the first 20 amino Elaine Bell acids constituted the minimum signal ORIGINAL RESEARCH PAPER Kagan, J. C. et al. for TRAM localization to both the TRAM couples endocytosis of Toll-like receptor 4 plasma membrane and endosomes, to the induction of interferon-β. Nature Immunol. 24 February 2008 (doi:10.1038/ni1569) but the first 7 amino acids were SUPERSTOCK naturE rEViEWS | iMMUnologY VOlumE 8 | april 2008 © 2008 Nature Publishing Group .

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TLR3-Dependent Activation of TLR2 Endogenous Ligands Via the Myd88 Signaling Pathway Augments the Innate Immune Response
cells Article TLR3-Dependent Activation of TLR2 Endogenous Ligands via the MyD88 Signaling Pathway Augments the Innate Immune Response 1 2, 1 3 Hellen S. Teixeira , Jiawei Zhao y, Ethan Kazmierski , Denis F. Kinane and Manjunatha R. Benakanakere 2,* 1 Department of Orthodontics, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19004, USA; [email protected] (H.S.T.); [email protected] (E.K.) 2 Department of Periodontics, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19004, USA; [email protected] 3 Periodontology Department, Bern Dental School, University of Bern, 3012 Bern, Switzerland; [email protected] * Correspondence: [email protected] Present address: Department of Pathology, Wayne State University School of Medicine, y 541 East Canfield Ave., Scott Hall 9215, Detroit, MI 48201, USA. Received: 30 June 2020; Accepted: 12 August 2020; Published: 17 August 2020 Abstract: The role of the adaptor molecule MyD88 is thought to be independent of Toll-like receptor 3 (TLR3) signaling. In this report, we demonstrate a previously unknown role of MyD88 in TLR3 signaling in inducing endogenous ligands of TLR2 to elicit innate immune responses. Of the various TLR ligands examined, the TLR3-specific ligand polyinosinic:polycytidylic acid (poly I:C), significantly induced TNF production and the upregulation of other TLR transcripts, in particular, TLR2. Accordingly, TLR3 stimulation also led to a significant upregulation of endogenous TLR2 ligands mainly, HMGB1 and Hsp60. By contrast, the silencing of TLR3 significantly downregulated MyD88 and TLR2 gene expression and pro-inflammatory IL1β, TNF, and IL8 secretion. The silencing of MyD88 similarly led to the downregulation of TLR2, IL1β, TNF and IL8, thus suggesting MyD88 / to somehow act downstream of TLR3.
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TLR4 and TLR9 Ligands Macrophages Induces Cross
Lymphotoxin β Receptor Activation on Macrophages Induces Cross-Tolerance to TLR4 and TLR9 Ligands This information is current as Nadin Wimmer, Barbara Huber, Nicola Barabas, Johann of September 27, 2021. Röhrl, Klaus Pfeffer and Thomas Hehlgans J Immunol 2012; 188:3426-3433; Prepublished online 22 February 2012; doi: 10.4049/jimmunol.1103324 http://www.jimmunol.org/content/188/7/3426 Downloaded from Supplementary http://www.jimmunol.org/content/suppl/2012/02/23/jimmunol.110332 Material 4.DC1 http://www.jimmunol.org/ References This article cites 42 articles, 13 of which you can access for free at: http://www.jimmunol.org/content/188/7/3426.full#ref-list-1 Why The JI? Submit online. • Rapid Reviews! 30 days* from submission to initial decision by guest on September 27, 2021 • No Triage! Every submission reviewed by practicing scientists • Fast Publication! 4 weeks from acceptance to publication *average Subscription Information about subscribing to The Journal of Immunology is online at: http://jimmunol.org/subscription Permissions Submit copyright permission requests at: http://www.aai.org/About/Publications/JI/copyright.html Email Alerts Receive free email-alerts when new articles cite this article. Sign up at: http://jimmunol.org/alerts The Journal of Immunology is published twice each month by The American Association of Immunologists, Inc., 1451 Rockville Pike, Suite 650, Rockville, MD 20852 Copyright © 2012 by The American Association of Immunologists, Inc. All rights reserved. Print ISSN: 0022-1767 Online ISSN: 1550-6606. The Journal of Immunology Lymphotoxin b Receptor Activation on Macrophages Induces Cross-Tolerance to TLR4 and TLR9 Ligands Nadin Wimmer,* Barbara Huber,* Nicola Barabas,* Johann Ro¨hrl,* Klaus Pfeffer,† and Thomas Hehlgans* Our previous studies indicated that lymphotoxin b receptor (LTbR) activation controls and downregulates inﬂammatory reac- tions.
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Nonredundant Roles of TIRAP and Myd88 in Airway Response to Endotoxin, Independent of TRIF, IL-1 and IL-18 Pathways
Laboratory Investigation (2006) 86, 1126–1135 & 2006 USCAP, Inc All rights reserved 0023-6837/06 $30.00 www.laboratoryinvestigation.org Nonredundant roles of TIRAP and MyD88 in airway response to endotoxin, independent of TRIF, IL-1 and IL-18 pathways Dieudonne´e Togbe1, Gorse Aurore1, Nicolas Noulin1,2, Vale´rie FJ Quesniaux1, Silvia Schnyder-Candrian1, Bruno Schnyder1, Virginie Vasseur1, Shizuo Akira3, Kasper Hoebe4, Bruce Beutler4, Bernhard Ryffel1,* and Isabelle Couillin1,* 1Molecular Immunology and Embryology, CNRS UMR6218, Transgenose Institute, Orleans, France; 2R&D Department, Key-Obs, Orleans, France; 3Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan and 4Department of Immunology, Scripps Research Institute, La Jolla, CA, USA Inhaled endotoxins induce an acute inflammatory response in the airways mediated through Toll-like receptor 4 (TLR4) and myeloid differentiation factor 88 (MyD88). However, the relative roles of the TLR4 adaptor proteins TIRAP and TRIF and of the MyD88-dependent IL-1 and IL-18 receptor pathways in this response are unclear. Here, we demonstrate that endotoxin-induced acute bronchoconstriction, vascular damage resulting in protein leak, Th1 cytokine and chemokine secretion and neutrophil recruitment in the airways are abrogated in mice deficient for either TIRAP or MyD88, but not in TRIF deficient mice. The contribution of other TLR-independent, MyD88-dependent signaling pathways was investigated in IL-1R1, IL-18R and caspase-1 (ICE)-deficient mice, which displayed normal airway responses to endotoxin. In conclusion, the TLR4-mediated, bronchoconstric- tion and acute inflammatory lung pathology to inhaled endotoxin critically depend on the expression of both adaptor proteins, TIRAP and MyD88, suggesting cooperative roles, while TRIF, IL-1R1, IL-18R signaling pathways are dispensable.
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Signaling Molecules§ Erin E
Veterinary Immunology and Immunopathology 112 (2006) 302–308 www.elsevier.com/locate/vetimm Short communication Cloning and radiation hybrid mapping of bovine toll-like receptor-4 (TLR-4) signaling molecules§ Erin E. Connor a, Elizabeth A. Cates a,b, John L. Williams c, Douglas D. Bannerman a,* a Bovine Functional Genomics Laboratory, U.S. Department of Agriculture, Agricultural Research Service, Beltsville, MD 20705, USA b University of Maryland, College Park, MD 20742, USA c Roslin Institute (Edinburgh), Roslin, Midlothian, Scotland, UK Received 17 January 2006; accepted 7 March 2006 Abstract Toll-like receptor (TLR)-4 is a transmembrane receptor for lipopolysaccharide, a highly pro-inﬂammatory component of the outer membrane of Gram-negative bacteria. To date, molecules of the TLR-4 signaling pathway have not been well characterized in cattle. The goal of this study was to clone and sequence the full-length coding regions of bovine genes involved in TLR-4 signaling including CASP8, IRAK1, LY96 (MD-2), TICAM2, TIRAP, TOLLIP and TRAF 6 and to position these genes, as well as MyD88 and TICAM1, on the bovine genome using radiation hybrid mapping. Results of this work indicate differences with a previously published bovine sequence for LY96 and a predicted sequence in the GenBank database for TIRAP based on the most recent assembly of the bovine genome. In addition, discrepancies between actual and predicted chromosomal map positions based on the Btau_2.0 genome assembly release were identiﬁed, although map positions were consistent with predicted locations based on the current bovine-human comparative map. Alignment of the bovine amino acid sequences with human and murine sequences showed a broad range in conservation, from 52 to 93%.
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Dephosphorylating TRAM TRIF-Dependent TLR4 Pathway by Phosphatase PTPN4 Preferentially Inhibits
Phosphatase PTPN4 Preferentially Inhibits TRIF-Dependent TLR4 Pathway by Dephosphorylating TRAM This information is current as Wanwan Huai, Hui Song, Lijuan Wang, Bingqing Li, Jing of September 29, 2021. Zhao, Lihui Han, Chengjiang Gao, Guosheng Jiang, Lining Zhang and Wei Zhao J Immunol published online 30 March 2015 http://www.jimmunol.org/content/early/2015/03/28/jimmun ol.1402183 Downloaded from Why The JI? Submit online. http://www.jimmunol.org/ • Rapid Reviews! 30 days* from submission to initial decision • No Triage! Every submission reviewed by practicing scientists • Fast Publication! 4 weeks from acceptance to publication *average by guest on September 29, 2021 Subscription Information about subscribing to The Journal of Immunology is online at: http://jimmunol.org/subscription Permissions Submit copyright permission requests at: http://www.aai.org/About/Publications/JI/copyright.html Email Alerts Receive free email-alerts when new articles cite this article. Sign up at: http://jimmunol.org/alerts The Journal of Immunology is published twice each month by The American Association of Immunologists, Inc., 1451 Rockville Pike, Suite 650, Rockville, MD 20852 Copyright © 2015 by The American Association of Immunologists, Inc. All rights reserved. Print ISSN: 0022-1767 Online ISSN: 1550-6606. Published March 30, 2015, doi:10.4049/jimmunol.1402183 The Journal of Immunology Phosphatase PTPN4 Preferentially Inhibits TRIF-Dependent TLR4 Pathway by Dephosphorylating TRAM Wanwan Huai,* Hui Song,* Lijuan Wang,† Bingqing Li,‡ Jing Zhao,* Lihui Han,* Chengjiang Gao,* Guosheng Jiang,‡ Lining Zhang,* and Wei Zhao* TLR4 recruits TRIF-related adaptor molecule (TRAM, also known as TICAM2) as a sorting adaptor to facilitate the interaction between TLR4 and TRIF and then initiate TRIF-dependent IRF3 activation.
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