scholarly journals Select targeting of intracellular Toll-interleukin-1 receptor resistance domains for protection against influenza-induced disease

2020 ◽  
Vol 26 (1) ◽  
pp. 26-34
Author(s):  
Kari Ann Shirey ◽  
Wendy Lai ◽  
Lindsey J Brown ◽  
Jorge C G Blanco ◽  
Robert Beadenkopf ◽  
...  
Keyword(s):  
Immune Responses ◽  
Intracellular Signaling ◽  
Interleukin 1 ◽  
Tir Domain ◽  
Close Proximity ◽  
Domain Interactions ◽  
Tir Domains ◽  
Molecular Patterns ◽  
Lps Signaling

TLRs are a family of PRRs that respond to PAMPs or host-derived Danger-Associated Molecular Patterns (DAMPs) to initiate host inflammation and immune responses. TLR dimerization and recruitment of adapter molecules is critical for intracellular signaling and is mediated through intracellular Toll-Interleukin 1 Receptor Resistance (TIR) domain interactions. Human TIR domains, including reported structures of TIR1, TIR2, TIR6, TIR10, TIRAP, and MyD88, contain Cysteine (Cys) interactions or modifications that are disproportionally at, or near, reported biological TIR interfaces, or in close proximity to functionally important regions. Therefore, we hypothesized that intracellular TIR Cys regulation may have greater functional importance than previously appreciated. Expression of mutant TLR4-C747S or treatment of TLR4 reporter cells with a small molecule, Cys-binding inhibitor of TLR4, TAK-242, abrogated LPS signaling in vitro. Using TAK-242, mice were protected from lethal influenza challenge as previously reported for extracellular TLR4 antagonists. Molecular modeling and sequence analysis of the region surrounding TLR4-Cys747 indicate conservation of a WxxxE motif identified among bacterial and NAD+-consuming TIRs, as well as within the TIRs domains of surface TLRs 1, 2, 4, 6, and 10. Together, these data support the hypothesis that critical Cys within the TIR domain are essential for TLR4 functionality.

scholarly journals Peptide-mediated Interference of TIR Domain Dimerization in MyD88 Inhibits Interleukin-1-dependent Activation of NF-κB

2005 ◽  
Vol 280 (16) ◽  
pp. 15809-15814 ◽  
Author(s):  
Maria Loiarro ◽  
Claudio Sette ◽  
Grazia Gallo ◽  
Andrea Ciacci ◽  
Nicola Fantò ◽  
...  
Keyword(s):  
Interleukin 1 ◽  
Cell System ◽  
Tir Domain ◽  
Loop Region ◽  
Good Target ◽  
A Cell ◽  
Tir Domains ◽  
Myeloid Differentiation Factor

Myeloid differentiation factor 88 (MyD88) plays a crucial role in the signaling pathways triggered by interleukin (IL)-1 and Toll-like receptors in several steps of innate host defense. A crucial event in this signaling pathway is represented by dimerization of MyD88, which allows the recruitment of downstream kinases like IRAK-1 and IRAK-4. Herein, we have investigated the function of the Toll/IL-1 receptor (TIR) domain in MyD88 homodimerization in cell-free andin vitroexperimental settings by using epta-peptides that mimic the BB-loop region of the conserved TIR domain of different proteins. By using a pull-down assay with purified glutathioneS-transferase-MyD88 TIR or co-immunoprecipitation experiments, we found that epta-peptides derived from the TIR domain of MyD88 and IL-18R are the most effective in inhibiting homodimerization with either the isolated TIR or full-length MyD88. Moreover, we demonstrated that a cell permeable analog of MyD88 epta-peptide inhibits homodimerization of MyD88 TIR domains in anin vitrocell system and significantly reduces IL-1 signaling, as assayed by activation of the downstream transcription factor NF-κB. Our results indicate that the BB-loop in TIR domain of MyD88 is a good target for specific inhibition of MyD88-mediated signalingin vivo.

scholarly journals Antiviral activity of bacterial TIR domains via signaling molecules that trigger cell death

2021 ◽  
Author(s):  
Gal Ofir ◽  
Ehud Herbst ◽  
Maya Baroz ◽  
Daniel Cohen ◽  
Adi Millman ◽  
...  
Keyword(s):  
Cell Death ◽  
Intracellular Signaling ◽  
Interleukin 1 ◽  
Signaling Molecules ◽  
Immune Systems ◽  
Tir Domain ◽  
Cyclic Adp Ribose ◽  
Molecular Signal ◽  
Tir Domains ◽  
Intracellular Signaling Molecules

AbstractThe Toll/interleukin-1 receptor (TIR) domain is a canonical component of animal and plant immune systems. In plants, intracellular pathogen sensing by immune receptors triggers their TIR domains to generate a molecule which is a variant of cyclic ADP-ribose (v-cADPR). This molecule is hypothesized to activate plant cell death via a yet unresolved pathway. TIR domains were recently also shown to be involved in a bacterial anti-phage defense system called Thoeris, but the mechanism of Thoeris defense remained unknown. In this study we report that phage infection triggers Thoeris TIR-domain proteins to produce an isomer of cyclic ADP-ribose. This molecular signal activates a second protein, ThsA, which then depletes the cell of the essential molecule nicotinamide adenine dinucleotide (NAD) and leads to abortive infection and cell death. We further show that similar to eukaryotic innate immune systems, bacterial TIR-domain proteins determine the immunological specificity to the invading pathogen. Our results describe a new antiviral signaling pathway in bacteria, and suggest that generation of intracellular signaling molecules is an ancient immunological function of TIR domains conserved in both plant and bacterial immunity.

scholarly journals Structural studies of nucleic acid sensing Toll-like receptor

2014 ◽  
Vol 70 (a1) ◽  
pp. C252-C252
Author(s):  
Umeharu Ohto ◽  
Hiromi Tanji ◽  
Takuma Shibata ◽  
Elena Krayukhina ◽  
Susumu Uchiyama ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Immune Responses ◽  
Intracellular Signaling ◽  
Bacterial Infections ◽  
Adaptor Proteins ◽  
Structural Basis ◽  
Close Proximity ◽  
Endosomal Membranes ◽  
Dimerization Interface ◽  
Molecular Patterns

Toll-like receptors (TLRs) sense pathogen-associated molecular patterns originating from invading microorganism and evoke innate immune responses. Among TLRs, TLR3, TLR7, TLR8, and TLR9 are localized to endosomal membranes and are responsible for the recognition of nucleic acids. TLR7 and TLR8 recognize single stranded RNA. In addition, TLR7 and TLR8 are activated by small chemical compounds. TLR9 recognizes DNA containing Cytosine-phosphate-Guanine motif. Theses nucleic acid sensing TLRs are attractive therapeutic targets for the modulation of immune responses in the viral and bacterial infections and in the pathogenesis of autoimmune diseases. However, the structural basis for the nucleic acid recognition and signaling mechanisms remains to be elucidated. Therefore, we conducted crystallographic studies of these TLRs. Recently, we have determined the crystal structures of the extracellular domain of human TLR8 in the unliganded form and in the liganded forms with chemical ligands (Tanji et al., 2013). Both unliganded and liganded forms of TLR8 were dimer. Ligands were located at two equivalent positions in the dimerization interface. The ligand binding induced the reorganization of the preformed dimer to the activated dimer such that the C-terminal regions of the two protomers are in close proximity to enable the subsequent dimerization of the intracellular signaling domains and its interactions with adaptor proteins.

scholarly journals TIR domains of plant immune receptors are 2',3'-cAMP/cGMP synthetases mediating cell death

2021 ◽  
Author(s):  
Dongli Yu ◽  
Wen Song ◽  
Eddie Yong Jun Tan ◽  
Li Liu ◽  
Yu Cao ◽  
...  
Keyword(s):  
Cell Death ◽  
Immune Responses ◽  
Interleukin 1 ◽  
Structural Data ◽  
Negative Regulator ◽  
Synthetase Activity ◽  
Leucine Rich Repeat ◽  
Tir Domain ◽  
Immune Receptors ◽  
Tir Domains

2′,3′-cAMP is a positional isomer of the well-established second messenger 3′,5′-cAMP, but little is known on the biology of this noncanonical cyclic nucleotide monophosphate (cNMP). Toll/interleukin-1 receptor (TIR) domains of nucleotide-binding leucine-rich repeat (NLR) immune receptors have NADase function necessary but insufficient to activate plant immune responses. Here we show that plant TIR proteins, besides being NADases, act as 2′,3′-cAMP/cGMP synthetases by hydrolyzing RNA/DNA. Structural data shows that a TIR domain adopts distinct oligomers with dual and exclusive enzymatic activity. Mutations specifically disrupting the synthetase activity abrogate TIR-mediated cell death in Nicotiana benthamiana, supporting an important role for these cNMPs in TIR signaling. Furthermore, the Arabidopsis negative regulator of TIR-NLR signaling, NUDT7 displays 2′,3′-cAMP/cGMP but not 3′,5′-cAMP/cGMP phosphodiesterase activity and suppresses cell death activity of TIRs in N. benthamiana. Our study identifies a novel family of 2′,3′-cAMP/cGMP synthetase and establishes a role for the noncanonical cNMPs in plant immune responses.

scholarly journals Broad-Spectrum Disease Resistance Conferred by the Overexpression of Rice RLCK BSR1 Results from an Enhanced Immune Response to Multiple MAMPs

2019 ◽  
Vol 20 (22) ◽  
pp. 5523 ◽  
Author(s):  
Yasukazu Kanda ◽  
Hitoshi Nakagawa ◽  
Yoko Nishizawa ◽  
Takashi Kamakura ◽  
Masaki Mori
Keyword(s):  
Disease Resistance ◽  
Immune Responses ◽  
Broad Spectrum ◽  
Transcriptional Activation ◽  
Intracellular Signaling ◽  
Cultured Cells ◽  
Plant Immunity ◽  
Production Of Hydrogen ◽  
Defense Related Gene ◽  
Molecular Patterns

Plants activate their immune system through intracellular signaling pathways after perceiving microbe-associated molecular patterns (MAMPs). Receptor-like cytoplasmic kinases mediate the intracellular signaling downstream of pattern-recognition receptors. BROAD-SPECTRUM RESISTANCE 1 (BSR1), a rice (Oryza sativa) receptor-like cytoplasmic kinase subfamily-VII protein, contributes to chitin-triggered immune responses. It is valuable for agriculture because its overexpression confers strong disease resistance to fungal and bacterial pathogens. However, it remains unclear how overexpressed BSR1 reinforces plant immunity. Here we analyzed immune responses using rice suspension-cultured cells and sliced leaf blades overexpressing BSR1. BSR1 overexpression enhances MAMP-triggered production of hydrogen peroxide (H2O2) and transcriptional activation of the defense-related gene in cultured cells and leaf strips. Furthermore, the co-cultivation of leaves with conidia of the blast fungus revealed that BSR1 overexpression allowed host plants to produce detectable oxidative bursts against compatible pathogens. BSR1 was also involved in the immune responses triggered by peptidoglycan and lipopolysaccharide. Thus, we concluded that the hyperactivation of MAMP-triggered immune responses confers BSR1-mediated robust resistance to broad-spectrum pathogens.

scholarly journals IL-36 signaling amplifies Th1 responses by enhancing proliferation and Th1 polarization of naive CD4+ T cells

Blood ◽  
2012 ◽  
Vol 120 (17) ◽  
pp. 3478-3487 ◽  
Author(s):  
Solenne Vigne ◽  
Gaby Palmer ◽  
Praxedis Martin ◽  
Céline Lamacchia ◽  
Deborah Strebel ◽  
...  
Keyword(s):  
T Cells ◽  
Immune Responses ◽  
Cd4 T Cells ◽  
Interleukin 1 ◽  
Th1 Cell ◽  
Critical Function ◽  
Mediators Of Inflammation ◽  
Th1 Polarization

AbstractThe interleukin-1 (IL-1) superfamily of cytokines comprises a set of pivotal mediators of inflammation. Among them, the action of IL-36 cytokines in immune responses has remained elusive. In a recent study, we demonstrated a direct effect of IL-36 on immune cells. Here we show that, among T cells, the IL-36 receptor is predominantly expressed on naive CD4+ T cells and that IL-36 cytokines act directly on naive T cells by enhancing both cell proliferation and IL-2 secretion. IL-36β acts in synergy with IL-12 to promote Th1 polarization and IL-36 signaling is also involved in mediating Th1 immune responses to Bacillus Calmette-Guerin infection in vivo. Our findings point toward a critical function of IL-36 in the priming of Th1 cell responses in vitro, and in adaptive immunity in a model of mycobacterial infection in vivo.

scholarly journals The Poxvirus Protein A52R Targets Toll-like Receptor Signaling Complexes to Suppress Host Defense

2003 ◽  
Vol 197 (3) ◽  
pp. 343-351 ◽  
Author(s):  
Mary T. Harte ◽  
Ismar R. Haga ◽  
Geraldine Maloney ◽  
Pearl Gray ◽  
Patrick C. Reading ◽  
...  
Keyword(s):  
Intracellular Signaling ◽  
Interleukin 1 ◽  
Tumor Necrosis Factor Receptor ◽  
Nuclear Factor Κb ◽  
Innate Immune ◽  
Altered Gene Expression ◽  
Altered Gene ◽  
Molecular Patterns ◽  
Transcription Factor Nuclear Factor ◽  
Necrosis Factor

Toll-like receptors (TLRs) are crucial in the innate immune response to pathogens, in that they recognize and respond to pathogen associated molecular patterns, which leads to activation of intracellular signaling pathways and altered gene expression. Vaccinia virus (VV), the poxvirus used to vaccinate against smallpox, encodes proteins that antagonize important components of host antiviral defense. Here we show that the VV protein A52R blocks the activation of the transcription factor nuclear factor κB (NF-κB) by multiple TLRs, including TLR3, a recently identified receptor for viral RNA. A52R associates with both interleukin 1 receptor–associated kinase 2 (IRAK2) and tumor necrosis factor receptor–associated factor 6 (TRAF6), two key proteins important in TLR signal transduction. Further, A52R could disrupt signaling complexes containing these proteins. A virus deletion mutant lacking the A52R gene was attenuated compared with wild-type and revertant controls in a murine intranasal model of infection. This study reveals a novel mechanism used by VV to suppress the host immunity. We demonstrate viral disabling of TLRs, providing further evidence for an important role for this family of receptors in the antiviral response.

scholarly journals Vaccination with Adenovirus Serotypes 35, 26, and 48 Elicits Higher Levels of Innate Cytokine Responses than Adenovirus Serotype 5 in Rhesus Monkeys

2012 ◽  
Vol 86 (18) ◽  
pp. 9590-9598 ◽  
Author(s):  
Jeffrey E. Teigler ◽  
M. Justin Iampietro ◽  
Dan H. Barouch
Keyword(s):  
Immune Responses ◽  
Rhesus Monkeys ◽  
Interleukin 1 ◽  
Experimental Models ◽  
Gamma Interferon ◽  
Vaccine Vectors ◽  
Adenovirus Serotype ◽  
Cytokine Responses ◽  
Serotype 5

Adenovirus (Ad) vaccine vectors have proven highly immunogenic in multiple experimental models, but the innate immune responses induced by these vectors remain poorly characterized. Here we report innate cytokine responses to 5 different Ad vectors in 26 rhesus monkeys. Vaccination with adenovirus serotype 35 (Ad35), Ad26, and Ad48 induced substantially higher levels of antiviral (gamma interferon [IFN-γ], 10-kDa gamma interferon-induced protein [IP-10]) and proinflammatory (interleukin 1 receptor antagonist [IL-1RA], IL-6) cytokines than vaccination with Ad5 on day 1 following immunization.In vitrostudies with capsid chimeric vectors and receptor-blocking monoclonal antibodies suggested that fiber-receptor interactions, as well as other capsid components, were critical for triggering these innate responses. Moreover, multiple cell populations, including dendritic cells, monocytes/macrophages, and T lymphocytes, contributed to these innate cytokine profiles. These data demonstrate that Ad35, Ad26, and Ad48, which utilize CD46 as their primary cellular receptor, induce significantly greater innate cytokine responses than Ad5, which uses the coxsackievirus and adenovirus receptor (CAR). These differences in innate triggering result in markedly different immunologic milieus for the subsequent generation of adaptive immune responses by these vaccine vectors.

scholarly journals Phosphatase PP2C6 negatively regulates phosphorylation status of Pti1b kinase, a regulator of flagellin-triggered immunity in tomato

2019 ◽  
Author(s):  
Fabian Giska ◽  
Gregory B. Martin
Keyword(s):  
Immune Responses ◽  
Plant Immunity ◽  
Active Form ◽  
Control Plant ◽  
Negative Regulator ◽  
Response To Treatment ◽  
Positive Regulators ◽  
Molecular Patterns

AbstractPlant immune responses, including the production of reactive oxygen species (ROS), are triggered when pattern recognition receptors (PRR) become activated upon detection of microbe-associated molecular patterns (MAMPs). Receptor-like cytoplasmic kinases are key components of PRR-dependent signaling pathways. In tomato two such kinases, Pti1a and Pti1b, are important positive regulators of the plant immune response. However, it is unknown how these kinases control plant immunity at the molecular level, and how their activity is regulated. To investigate these issues, we used mass spectrometry to search for interactors of Pti1b in Nicotiana benthamiana leaves and identified a protein phosphatase, PP2C6. An in vitro pull-down assay and in vivo split luciferase complementation assay verified this interaction. Pti1b was found to autophosphorylate on threonine-233 and this phosphorylation was abolished in the presence of PP2C6. An arginine-to-cysteine substitution at position 240 in the Arabidopsis MARIS kinase was previously reported to convert it into a constitutive-active form. The analogous substitution in Pti1b made it resistant to PP2C6 phosphatase activity, although it still interacted with PP2C6. Treatment of N. benthamiana leaves with the MAMP flg22 induced threonine phosphorylation of Pti1b. Expression of PP2C6, but not a phosphatase-inactive variant of this protein, in N. benthamiana leaves greatly reduced ROS production in response to treatment with MAMPs flg22 or csp22. The results indicate that PP2C6 acts as a negative regulator by dephosphorylating the Pti1b kinase, thereby interfering with its ability to activate plant immune responses.

scholarly journals Development of a novel TLR8 agonist for cancer immunotherapy

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Yuxun Wang ◽  
Heping Yang ◽  
Huanping Li ◽  
Shuda Zhao ◽  
Yikun Zeng ◽  
...  
Keyword(s):  
Immune Responses ◽  
Drug Targets ◽  
Ex Vivo ◽  
Phase 1 ◽  
Single Agent ◽  
Cancer Drug ◽  
Favorable Safety ◽  
Molecular Patterns

Abstract Toll-like receptors (TLRs) are a family of proteins that recognize pathogen associated molecular patterns (PAMPs). Their primary function is to activate innate immune responses while also involved in facilitating adaptive immune responses. Different TLRs exert distinct functions by activating varied immune cascades. Several TLRs are being pursued as cancer drug targets. We discovered a novel, highly potent and selective small molecule TLR8 agonist DN052. DN052 exhibited strong in vitro cellular activity with EC50 at 6.7 nM and was highly selective for TLR8 over other TLRs including TLR4, 7 and 9. DN052 displayed excellent in vitro ADMET and in vivo PK profiles. DN052 potently inhibited tumor growth as a single agent. Moreover, combination of DN052 with the immune checkpoint inhibitor, selected targeted therapeutics or chemotherapeutic drugs further enhanced efficacy of single agents. Mechanistically, treatment with DN052 resulted in strong induction of pro-inflammatory cytokines in ex vivo human PBMC assay and in vivo monkey study. GLP toxicity studies in rats and monkeys demonstrated favorable safety profile. This led to the advancement of DN052 into phase 1 clinical trials.

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