scholarly journals Essential role of IPS-1 in innate immune responses against RNA viruses

2006 ◽  
Vol 203 (7) ◽  
pp. 1795-1803 ◽  
Author(s):  
Himanshu Kumar ◽  
Taro Kawai ◽  
Hiroki Kato ◽  
Shintaro Sato ◽  
Ken Takahashi ◽  
...  
Keyword(s):  
Rna Viruses ◽  
Rna Virus ◽  
Critical Role ◽  
Nuclear Factor Κb ◽  
Type I ◽  
Innate Immune Responses ◽  
Antiviral Responses ◽  
Deficient Mice

IFN-β promoter stimulator (IPS)-1 was recently identified as an adapter for retinoic acid–inducible gene I (RIG-I) and melanoma differentiation-associated gene 5 (Mda5), which recognize distinct RNA viruses. Here we show the critical role of IPS-1 in antiviral responses in vivo. IPS-1–deficient mice showed severe defects in both RIG-I– and Mda5-mediated induction of type I interferon and inflammatory cytokines and were susceptible to RNA virus infection. RNA virus–induced interferon regulatory factor-3 and nuclear factor κB activation was also impaired in IPS-1–deficient cells. IPS-1, however, was not essential for the responses to either DNA virus or double-stranded B-DNA. Thus, IPS-1 is the sole adapter in both RIG-I and Mda5 signaling that mediates effective responses against a variety of RNA viruses.

scholarly journals Thioredoxin 2 Negatively Regulates Innate Immunity to RNA Viruses by Disrupting the Assembly of the Virus-Induced Signaling Adaptor Complex

2020 ◽  
Vol 94 (7) ◽  
Author(s):  
Dan Li ◽  
Wenping Yang ◽  
Yi Ru ◽  
Jingjing Ren ◽  
Xiangtao Liu ◽  
...  
Keyword(s):  
Complex Formation ◽  
Rna Viruses ◽  
Critical Role ◽  
Type I Interferons ◽  
Type I ◽  
Host Proteins ◽  
Innate Antiviral Response ◽  
Thioredoxin 2

ABSTRACT The virus-induced signaling adaptor (VISA) complex plays a critical role in the innate immune response to RNA viruses. However, the mechanism of VISA complex formation remains unclear. Here, we demonstrate that thioredoxin 2 (TRX2) interacts with VISA at mitochondria both in vivo and in vitro. Knockdown and knockout of TRX2 enhanced the formation of the VISA-associated complex, as well as virus-triggered activation of interferon regulatory factor 3 (IRF3) and transcription of the interferon beta 1 (IFNB1) gene. TRX2 inhibits the formation of VISA aggregates by repressing reactive oxygen species (ROS) production, thereby disrupting the assembly of the VISA complex. Furthermore, our data suggest that the C93 residue of TRX2 is essential for inhibition of VISA aggregation, whereas the C283 residue of VISA is required for VISA aggregation. Collectively, these findings uncover a novel mechanism of TRX2 that negatively regulates VISA complex formation. IMPORTANCE The VISA-associated complex plays pivotal roles in inducing type I interferons (IFNs) and eliciting the innate antiviral response. Many host proteins are identified as VISA-associated-complex proteins, but how VISA complex formation is regulated by host proteins remains enigmatic. We identified the TRX2 protein as an important regulator of VISA complex formation. Knockout of TRX2 increases virus- or poly(I·C)-triggered induction of type I IFNs at the VISA level. Mechanistically, TRX2 inhibits the production of ROS at its C93 site, which impairs VISA aggregates at its C283 site, and subsequently impedes the assembly of the VISA complex. Our findings suggest that TRX2 plays an important role in the regulation of VISA complex assembly.

scholarly journals A critical role for IRAK4 kinase activity in Toll-like receptor–mediated innate immunity

2007 ◽  
Vol 204 (5) ◽  
pp. 1025-1036 ◽  
Author(s):  
Tae Whan Kim ◽  
Kirk Staschke ◽  
Katarzyna Bulek ◽  
Jianhong Yao ◽  
Kristi Peters ◽  
...  
Keyword(s):  
Immune Responses ◽  
Kinase Activity ◽  
Critical Role ◽  
Nuclear Factor Κb ◽  
Type I ◽  
Toll Like Receptor ◽  
Chemokine Production ◽  
Cytokines And Chemokines ◽  
Plasmacytoid Dcs

IRAK4 is a member of IL-1 receptor (IL-1R)–associated kinase (IRAK) family and has been shown to play an essential role in Toll-like receptor (TLR)–mediated signaling. We recently generated IRAK4 kinase-inactive knock-in mice to examine the role of kinase activity of IRAK4 in TLR-mediated signaling pathways. The IRAK4 kinase–inactive knock-in mice were completely resistant to lipopolysaccharide (LPS)- and CpG-induced shock, due to impaired TLR-mediated induction of proinflammatory cytokines and chemokines. Although inactivation of IRAK4 kinase activity did not affect the levels of TLR/IL-1R–mediated nuclear factor κB activation, a reduction of LPS-, R848-, and IL-1–mediated mRNA stability contributed to the reduced cytokine and chemokine production in bone marrow–derived macrophages from IRAK4 kinase–inactive knock-in mice. Both TLR7- and TLR9-mediated type I interferon production was abolished in plasmacytoid dendritic cells isolated from IRAK4 knock-in mice. In addition, influenza virus–induced production of interferons in plasmacytoid DCs was also dependent on IRAK4 kinase activity. Collectively, our results indicate that IRAK4 kinase activity plays a critical role in TLR-dependent immune responses.

scholarly journals The critical role of agrin in the hematopoietic stem cell niche

Blood ◽  
2011 ◽  
Vol 118 (10) ◽  
pp. 2733-2742 ◽  
Author(s):  
Cristina Mazzon ◽  
Achille Anselmo ◽  
Javier Cibella ◽  
Cristiana Soldani ◽  
Annarita Destro ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Critical Role ◽  
Hematopoietic Stem ◽  
Hematopoietic Stem Cell Niche ◽  
Cell Niche ◽  
Deficient Mice

Abstract Hematopoiesis is the process leading to the sustained production of blood cells by hematopoietic stem cells (HSCs). Growth, survival, and differentiation of HSCs occur in specialized microenvironments called “hematopoietic niches,” through molecular cues that are only partially understood. Here we show that agrin, a proteoglycan involved in the neuromuscular junction, is a critical niche-derived signal that controls survival and proliferation of HSCs. Agrin is expressed by multipotent nonhematopoietic mesenchymal stem cells (MSCs) and by differentiated osteoblasts lining the endosteal bone surface, whereas Lin−Sca1+c-Kit+ (LSK) cells express the α-dystroglycan receptor for agrin. In vitro, agrin-deficient MSCs were less efficient in supporting proliferation of mouse Lin−c-Kit+ cells, suggesting that agrin plays a role in the hematopoietic cell development. These results were indeed confirmed in vivo through the analysis of agrin knockout mice (Musk-L;Agrn−/−). Agrin-deficient mice displayed in vivo apoptosis of CD34+CD135− LSK cells and impaired hematopoiesis, both of which were reverted by an agrin-sufficient stroma. These data unveil a crucial role of agrin in the hematopoietic niches and in the cross-talk between stromal and hematopoietic stem cells.

scholarly journals S100A8/A9 modulates inflammatory collateral tissue damage during intraperitoneal origin systemic candidiasis

2020 ◽  
Author(s):  
Madhu Shankar ◽  
Nathalie Uwamahoro ◽  
Sandra Holmberg ◽  
Maria Joanna Niemiec ◽  
Johannes Roth ◽  
...  
Keyword(s):  
Tissue Damage ◽  
Critical Role ◽  
Specific Inhibitor ◽  
Surgical Intensive Care ◽  
Inflammatory Protein ◽  
Systemic Level ◽  
Combating Infection ◽  
Deficient Mice

AbstractPeritonitis is a leading cause of severe sepsis in surgical intensive care units, as over 70% of patients diagnosed with peritonitis develop septic shock. A critical role of the immune system is to return to homeostasis after combating infection. S100A8/A9 (calprotectin) is an antimicrobial, pro-inflammatory protein complex often used as a biomarker for diagnosis of disease activities in many inflammatory disorders. Here we describe the role of S100A8/A9 on inflammatory collateral tissue damage (ICTD).We performed an in vivo Candida albicans disseminated peritonitis mouse model using WT and S100A9-deficient mice and stimulated primary macrophages with recombinant S100A8/A9 in the presence or absence of the compound paquinimod, a specific inhibitor of S100A9. In addition, the effects on ICTD and fungal clearance were investigated. S100A9-deficient mice developed less ICTD than wildtype mice. Restoration of S100A8/A9 in S100A9 knockout mice resulted in increased ICTD and fungal clearance comparable to wildtype levels. Treatment with paquinimod abolished ICTD.The data indicated that S100A8/A9 controls ICTD levels and host antimicrobial modulation at a systemic level during intra-abdominal candidiasis (IAC).

scholarly journals Unraveling the Underlying Interaction Mechanism Between Dabie bandavirus and Innate Immune Response

2021 ◽  
Vol 12 ◽  
Author(s):  
Chuan-min Zhou ◽  
Xue-jie Yu
Keyword(s):  
Interaction Mechanism ◽  
Innate Immune ◽  
Type I ◽  
Innate Immune Responses ◽  
Structural Protein ◽  
Antiviral Responses ◽  
Host Virus Interactions ◽  
Virus Interactions ◽  
Severe Fever

The genus Bandavirus consists of seven tick-borne bunyaviruses, among which four are known to infect humans. Dabie bandavirus, severe fever with thrombocytopenia syndrome virus (SFTSV), poses serious threats to public health worldwide. SFTSV is a tick-borne virus mainly reported in China, South Korea, and Japan with a mortality rate of up to 30%. To date, most immunology-related studies focused on the antagonistic role of SFTSV non-structural protein (NSs) in sequestering RIG-I-like-receptors (RLRs)-mediated type I interferon (IFN) induction and type I IFN mediated signaling pathway. It is still elusive whether the interaction of SFTSV and other conserved innate immune responses exists. As of now, no specific vaccines or therapeutics are approved for SFTSV prevention or treatments respectively, in part due to a lack of comprehensive understanding of the molecular interactions occurring between SFTSV and hosts. Hence, it is necessary to fully understand the host-virus interactions including antiviral responses and viral evasion mechanisms. In this review, we highlight the recent progress in understanding the pathogenesis of SFTS and speculate underlying novel mechanisms in response to SFTSV infection.

scholarly journals The p110δ of PI3K plays a critical role in NK cell terminal maturation and cytokine/chemokine generation

2008 ◽  
Vol 205 (10) ◽  
pp. 2419-2435 ◽  
Author(s):  
Hailong Guo ◽  
Asanga Samarakoon ◽  
Bart Vanhaesebroeck ◽  
Subramaniam Malarkannan
Keyword(s):  
Nk Cells ◽  
Nk Cell ◽  
Critical Role ◽  
Cell Receptor ◽  
Cell Development ◽  
Effector Functions ◽  
Antiviral Responses

Phosphatidylinositol 3-kinases (PI3Ks) play a critical role in regulating B cell receptor– and T cell receptor–mediated signaling. However, their role in natural killer (NK) cell development and functions is not well understood. Using mice expressing p110δD910A, a catalytically inactive p110δ, we show that these mice had reduced NK cellularity, defective Ly49C and Ly49I NK subset maturation, and decreased CD27High NK numbers. p110δ inactivation marginally impaired NK-mediated cytotoxicity against tumor cells in vitro and in vivo. However, NKG2D, Ly49D, and NK1.1 receptor–mediated cytokine and chemokine generation by NK cells was severely affected in these mice. Further, p110δD910A/D910A NK cell–mediated antiviral responses through natural cytotoxicity receptor 1 were reduced. Analysis of signaling events demonstrates that p110δD910A/D910A NK cells had a reduced c-Jun N-terminal kinase 1/2 phosphorylation in response to NKG2D-mediated activation. These results reveal a previously unrecognized role of PI3K-p110δ in NK cell development and effector functions.

scholarly journals Critical role of interferons in gastrointestinal injury repair

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Constance McElrath ◽  
Vanessa Espinosa ◽  
Jian-Da Lin ◽  
Jianya Peng ◽  
Raghavendra Sridhar ◽  
...  
Keyword(s):  
Critical Role ◽  
Mucosal Healing ◽  
Type I ◽  
Acute Colitis ◽  
Colonic Injury ◽  
Epithelial Regeneration ◽  
Complex Interactions ◽  
Pleiotropic Functions ◽  
Deficient Mice

AbstractThe etiology of ulcerative colitis is poorly understood and is likely to involve perturbation of the complex interactions between the mucosal immune system and the commensal bacteria of the gut, with cytokines acting as important cross-regulators. Here we use IFN receptor-deficient mice in a dextran sulfate sodium (DSS) model of acute intestinal injury to study the contributions of type I and III interferons (IFN) to the initiation, progression and resolution of acute colitis. We find that mice lacking both types of IFN receptors exhibit enhanced barrier destruction, extensive loss of goblet cells and diminished proliferation of epithelial cells in the colon following DSS-induced damage. Impaired mucosal healing in double IFN receptor-deficient mice is driven by decreased amphiregulin expression, which IFN signaling can up-regulate in either the epithelial or hematopoietic compartment. Together, these data underscore the pleiotropic functions of IFNs and demonstrate that these critical antiviral cytokines also support epithelial regeneration following acute colonic injury.

scholarly journals Myeloid neddylation targets IRF7 and promotes host innate immunity against RNA viruses

2021 ◽  
Vol 17 (9) ◽  
pp. e1009901
Author(s):  
Min Zhao ◽  
Yaolin Zhang ◽  
Xiqin Yang ◽  
Jiayang Jin ◽  
Zhuo Shen ◽  
...  
Keyword(s):  
Innate Immunity ◽  
Virus Infection ◽  
Nuclear Translocation ◽  
Rna Viruses ◽  
Rna Virus ◽  
Innate Immune ◽  
Type I ◽  
Gene Promoters ◽  
Post Translational Modification

Neddylation, an important type of post-translational modification, has been implicated in innate and adapted immunity. But the role of neddylation in innate immune response against RNA viruses remains elusive. Here we report that neddylation promotes RNA virus-induced type I IFN production, especially IFN-α. More importantly, myeloid deficiency of UBA3 or NEDD8 renders mice less resistant to RNA virus infection. Neddylation is essential for RNA virus-triggered activation of Ifna gene promoters. Further exploration has revealed that mammalian IRF7undergoes neddylation, which is enhanced after RNA virus infection. Even though neddylation blockade does not hinder RNA virus-triggered IRF7 expression, IRF7 mutant defective in neddylation exhibits reduced ability to activate Ifna gene promoters. Neddylation blockade impedes RNA virus-induced IRF7 nuclear translocation without hindering its phosphorylation and dimerization with IRF3. By contrast, IRF7 mutant defective in neddylation shows enhanced dimerization with IRF5, an Ifna repressor when interacting with IRF7. In conclusion, our data demonstrate that myeloid neddylation contributes to host anti-viral innate immunity through targeting IRF7 and promoting its transcriptional activity.

scholarly journals p38 inhibition provides anti–DNA virus immunity by regulation of USP21 phosphorylation and STING activation

2017 ◽  
Vol 214 (4) ◽  
pp. 991-1010 ◽  
Author(s):  
Yunfei Chen ◽  
Lufan Wang ◽  
Jiali Jin ◽  
Yi Luan ◽  
Cong Chen ◽  
...  
Keyword(s):  
Virus Infection ◽  
Critical Role ◽  
Adaptor Protein ◽  
Type I Interferons ◽  
Type I ◽  
Innate Immune Responses ◽  
Dna Virus ◽  
Important Pathway ◽  
Hsv 1

Stimulator of IFN genes (STING) is a central adaptor protein that mediates the innate immune responses to DNA virus infection. Although ubiquitination is essential for STING function, how the ubiquitination/deubiquitination system is regulated by virus infection to control STING activity remains unknown. In this study, we found that USP21 is an important deubiquitinating enzyme for STING and that it negatively regulates the DNA virus–induced production of type I interferons by hydrolyzing K27/63-linked polyubiquitin chain on STING. HSV-1 infection recruited USP21 to STING at late stage by p38-mediated phosphorylation of USP21 at Ser538. Inhibition of p38 MAPK enhanced the production of IFNs in response to virus infection and protected mice from lethal HSV-1 infection. Thus, our study reveals a critical role of p38-mediated USP21 phosphorylation in regulating STING-mediated antiviral functions and identifies p38-USP21 axis as an important pathway that DNA virus adopts to avoid innate immunity responses.

scholarly journals Amyloidogenic processing of amyloid β protein precursor (APP) is enhanced in the brains of alcadein α–deficient mice

2020 ◽  
Vol 295 (28) ◽  
pp. 9650-9662 ◽  
Author(s):  
Naoya Gotoh ◽  
Yuhki Saito ◽  
Saori Hata ◽  
Haruka Saito ◽  
Daiki Ojima ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Adaptor Protein ◽  
Type I ◽  
Amyloid Β Protein ◽  
Protein Precursor ◽  
Amyloidogenic Processing ◽  
Β Amyloid ◽  
Deficient Mice

Alzheimer's disease (AD) is a very common neurodegenerative disorder, chiefly caused by increased production of neurotoxic β-amyloid (Aβ) peptide generated from proteolytic cleavage of β-amyloid protein precursor (APP). Except for familial AD arising from mutations in the APP and presenilin (PSEN) genes, the molecular mechanisms regulating the amyloidogenic processing of APP are largely unclear. Alcadein α/calsyntenin1 (ALCα/CLSTN1) is a neuronal type I transmembrane protein that forms a complex with APP, mediated by the neuronal adaptor protein X11-like (X11L or MINT2). Formation of the ALCα–X11L–APP tripartite complex suppresses Aβ generation in vitro, and X11L-deficient mice exhibit enhanced amyloidogenic processing of endogenous APP. However, the role of ALCα in APP metabolism in vivo remains unclear. Here, by generating ALCα-deficient mice and using immunohistochemistry, immunoblotting, and co-immunoprecipitation analyses, we verified the role of ALCα in the suppression of amyloidogenic processing of endogenous APP in vivo. We observed that ALCα deficiency attenuates the association of X11L with APP, significantly enhances amyloidogenic β-site cleavage of APP, especially in endosomes, and increases the generation of endogenous Aβ in the brain. Furthermore, we noted amyloid plaque formation in the brains of human APP-transgenic mice in an ALCα-deficient background. These results unveil a potential role of ALCα in protecting cerebral neurons from Aβ-dependent pathogenicity in AD.

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