scholarly journals A Computational Probe into the Structure and Dynamics of the Full-Length Toll-Like Receptor 3 in a Phospholipid Bilayer

2020 ◽  
Vol 21 (8) ◽  
pp. 2857
Author(s):  
Mahesh Chandra Patra ◽  
Maria Batool ◽  
Muhammad Haseeb ◽  
Sangdun Choi
Keyword(s):  
Interleukin 1 ◽  
Full Length ◽  
Phospholipid Bilayer ◽  
Type I Interferons ◽  
Type I ◽  
Toll Like Receptor ◽  
Phosphate Backbone ◽  
Dimerization Interface ◽  
Dynamics Simulations ◽  
Tir Domains

Toll-like receptor 3 (TLR3) provides the host with antiviral defense by initiating an immune signaling cascade for the production of type I interferons. The X-ray structures of isolated TLR3 ectodomain (ECD) and transmembrane (TM) domains have been reported; however, the structure of a membrane-solvated, full-length receptor remains elusive. We investigated an all-residue TLR3 model embedded inside a phospholipid bilayer using molecular dynamics simulations. The TLR3-ECD exhibited a ~30°–35° tilt on the membrane due to the electrostatic interaction between the N-terminal subdomain and phospholipid headgroups. Although the movement of dsRNA did not affect the dimer integrity of TLR3, its sugar-phosphate backbone was slightly distorted with the orientation of the ECD. TM helices exhibited a noticeable tilt and curvature but maintained a consistent crossing angle, avoiding the hydrophobic mismatch with the bilayer. Residues from the αD helix and the CD and DE loops of the Toll/interleukin-1 receptor (TIR) domains were partially absorbed into the lower leaflet of the bilayer. We found that the previously unknown TLR3-TIR dimerization interface could be stabilized by the reciprocal contact between αC and αD helices of one subunit and the αC helix and the BB loop of the other. Overall, the present study can be helpful to understand the signaling-competent form of TLR3 in physiological environments.

scholarly journals DDX3 directly facilitates IKKα activation and regulates downstream signalling pathways

2018 ◽  
Vol 475 (22) ◽  
pp. 3595-3607 ◽  
Author(s):  
Anthony Fullam ◽  
Lili Gu ◽  
Yvette Höhn ◽  
Martina Schröder
Keyword(s):  
Nuclear Factor Κb ◽  
Innate Immune ◽  
Type I Interferons ◽  
Signalling Pathways ◽  
Type I ◽  
Nuclear Factor ◽  
Toll Like Receptor ◽  
Disease States ◽  
Dead Box ◽  
Iκb Kinase

DDX3 is a DEAD-box RNA helicase that we and others have previously implicated in antiviral immune signalling pathways leading to type I interferon (IFN) induction. We previously demonstrated that it directly interacts with the kinase IKKε (IκB kinase ε), enhances it activation, and then facilitates phosphorylation of the transcription factor IRF3 by IKKε. However, the TLR7/9 (Toll-like receptor 7/9)-mediated pathway, one of the most physiologically relevant IFN induction pathways, proceeds independently of IKKε or the related kinase TBK1 (TANK-binding kinase 1). This pathway induces type I IFN production via the kinases NIK (NF-κB-inducing kinase) and IKKα and is activated when plasmacytoid dendritic cells sense viral nucleic acids. In the present study, we demonstrate that DDX3 also directly interacts with IKKα and enhances its autophosphorylation and -activation. Modulation of DDX3 expression consequently affected NIK/IKKα-mediated IRF7 phosphorylation and induction of type I interferons. In addition, alternative NF-κB (nuclear factor-κB) activation, another pathway regulated by NIK and IKKα, was also down-regulated in DDX3 knockdown cells. This substantially broadens the effects of DDX3 in innate immune signalling to pathways beyond TBK1/IKKε and IFN induction. Dysregulation of these pathways is involved in disease states, and thus, our research might implicate DDX3 as a potential target for their therapeutic manipulation.

The protective role of Toll-like receptor 3 and type-I interferons in the pathophysiology of vein graft disease

2018 ◽  
Vol 121 ◽  
pp. 16-24 ◽  
Author(s):  
K.H. Simons ◽  
M.R. de Vries ◽  
H.A.B. Peters ◽  
J.F. Hamming ◽  
J.W. Jukema ◽  
...  
Keyword(s):  
Vein Graft ◽  
Protective Role ◽  
Type I Interferons ◽  
Type I ◽  
Toll Like Receptor ◽  
Vein Graft Disease ◽  
Graft Disease

scholarly journals Counter-regulation in the IKK family

2011 ◽  
Vol 434 (1) ◽  
pp. e1-e2 ◽  
Author(s):  
Luke A. J. O'Neill
Keyword(s):  
Inflammatory Diseases ◽  
Interleukin 1 ◽  
Nuclear Factor Κb ◽  
Type I Interferons ◽  
Poly I:C ◽  
Type I ◽  
Control Mechanisms ◽  
Biochemical Journal ◽  
Regulatory Feedback Loop

The human IKK [IκB (inhibitor of NF-κB) kinase] family has four members; they are the central kinases of innate immunity. Two members, IKKα and IKKβ, the so-called canonical members, phosphoryate IκBα, leading to activation of the transcription factor NF-κB (nuclear factor κB), which controls the expression of many immune and inflammatory genes. The IKK-related proteins TBK-1 (TANK-binding kinase 1) and IKKϵ have a different substrate – IRF3 (interferon regulatory factor 3) – which regulates a different set of genes, the products of which include Type I interferons. Toll-like receptors (TLRs) such as the lipopolysaccharide receptor TLR4 or the poly(I:C) receptor TLR3 activate each of the IKKs, but the pro-inflammatory cytokine IL-1 (interleukin 1), which signals in a broadly similar way to the TLRs, has so far been shown to activate only the canonical IKKs. In this issue of the Biochemical Journal, Clark et al. bring new insights into the regulation of IKKs. They demonstrate that IL-1 is in fact able to activate IKKϵ/TBK-1, which occurs via IKKα/IKKβ. The consequence of this is not IRF3 activation, but a negative feedback effect on IKKα/IKKβ. This provides us with yet another regulatory feedback loop in a system already replete with control mechanisms. It attests yet again to the importance of keeping these innate immune pathways in check, since if they proceed uncontrolled, inflammatory diseases can occur. Importantly, this study utilized new and specific inhibitors of these kinases, suggesting that the interpretation of any effects the compound might have in vivo may be complex, since for example the inhibition of IKKϵ/TBK-1 might actually have a pro-inflammatory effect.

scholarly journals Toll-like receptor 9 trafficking and signaling for type I interferons requires PIKfyve activity

2015 ◽  
Vol 27 (9) ◽  
pp. 435-445 ◽  
Author(s):  
Kachiko Hayashi ◽  
Miwa Sasai ◽  
Akiko Iwasaki
Keyword(s):  
Type I Interferons ◽  
Type I ◽  
Toll Like Receptor

scholarly journals Toll-Like Receptor 3 Mediates Establishment of an Antiviral State against Hepatitis C Virus in Hepatoma Cells

2009 ◽  
Vol 83 (19) ◽  
pp. 9824-9834 ◽  
Author(s):  
Nan Wang ◽  
Yuqiong Liang ◽  
Santhana Devaraj ◽  
Jie Wang ◽  
Stanley M. Lemon ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Hepatitis Virus ◽  
Hepatoma Cells ◽  
Human Hepatocytes ◽  
Hcv Infection ◽  
Type I Interferons ◽  
Type I ◽  
Toll Like Receptor ◽  
Virus Infections

ABSTRACT Toll-like receptor-3 (TLR3) senses double-stranded RNA, initiating signaling that activates NF-κB and interferon regulatory factor 3 (IRF-3), thereby inducing the synthesis of proinflammatory cytokines, type I interferons, and numerous interferon-stimulated genes (ISGs). This pathway has not been extensively investigated in human hepatocytes, and its role in sensing and protecting against hepatitis virus infections is uncertain. We show here that primary human hepatocytes express TLR3 and robustly upregulate ISGs upon poly(I·C) stimulation. We also show that TLR3 senses hepatitis C virus (HCV) infection when expressed in permissive hepatoma cells, acting independently of retinoic acid-inducible gene I and inducing IRF-3 activation and the synthesis of ISGs that restrict virus replication. In turn, HCV infection reduces the abundance of TRIF, an essential TLR3 adaptor, and impairs poly(I·C)-induced signaling. The induction and disruption of TLR3 signaling by HCV may be important factors in determining the outcome of infection and the ability of HCV to establish persistent infections.

scholarly journals Type I Interferons Protect From Toll-Like Receptor 9–Associated Liver Injury and Regulate IL-1 Receptor Antagonist in Mice

2011 ◽  
Vol 140 (2) ◽  
pp. 697-708.e4 ◽  
Author(s):  
Jan Petrasek ◽  
Angela Dolganiuc ◽  
Timea Csak ◽  
Evelyn A. Kurt–Jones ◽  
Gyongyi Szabo
Keyword(s):  
Liver Injury ◽  
Receptor Antagonist ◽  
Type I Interferons ◽  
Type I ◽  
Toll Like Receptor

scholarly journals Toll-like Receptor 3–Mediated Suppression of TRAMP Prostate Cancer Shows the Critical Role of Type I Interferons in Tumor Immune Surveillance

2010 ◽  
Vol 70 (7) ◽  
pp. 2595-2603 ◽  
Author(s):  
Arnold I. Chin ◽  
Andrea K. Miyahira ◽  
Anthony Covarrubias ◽  
Juli Teague ◽  
Beichu Guo ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Critical Role ◽  
Immune Surveillance ◽  
Type I Interferons ◽  
Type I ◽  
Toll Like Receptor

Functional interfaces between TICAM-2/TRAM and TICAM-1/TRIF in TLR4 signaling

2017 ◽  
Vol 45 (4) ◽  
pp. 929-935 ◽  
Author(s):  
Kenji Funami ◽  
Misako Matsumoto ◽  
Hiroyuki Oshiumi ◽  
Fuyuhiko Inagaki ◽  
Tsukasa Seya
Keyword(s):  
Amino Acids ◽  
Type I Interferon ◽  
Structural Information ◽  
Interleukin 1 ◽  
Endotoxin Shock ◽  
Type I Interferons ◽  
Type I ◽  
Tir Domain ◽  
Adaptor Molecule ◽  
Acidic Amino Acids

Toll-like receptor 4 (TLR4) recognizes lipopolysaccharide (LPS), produces pro-inflammatory cytokines and type I interferons, and associates with a trigger of endotoxin shock. TLR4 is interacted with a TIR domain-containing adaptor molecule-2 (TICAM-2)/TRAM [TRIF (TIR domain-containing adaptor-inducing interferon-β)-related adaptor molecule] via its Toll–interleukin-1 receptor homology (TIR) domain. TICAM-2 acts as a scaffold protein and activates TIR domain-containing adaptor molecule-1 (TICAM-1)/TRIF. According to the structural analysis by NMR, TICAM-2 interacts with TICAM-1 by the acidic amino acids motif, E87/D88/D89. The TIR domain of TICAM-2 couples with the dimer of TIR domain of TLR4 beneath the membrane, and TICAM-2 itself also forms dimer and constitutes a binding site with TICAM-1. Endosomal localization of TICAM-2 is essential for TLR4-mediated type I interferon-inducing signal from the endosome. N-terminal myristoylation allows TICAM-2 to anchor to the endosomal membrane. Additionally, we have identified two acidic amino acids, D91/E92, as a functional motif that cooperatively determines endosomal localization of TICAM-2. This structural information of TICAM-2 suggests that the specific structure is indispensable for the endosomal localization and type I interferon production of TICAM-2. Taken together with the knowledge on cytoplasmic sensors for LPS, TICAM-2/TICAM-1 may conform to a signal network on TLR4 to facilitate induction of cytokine disorders.

Sign in / Sign up

Export Citation Format

Share Document