scholarly journals Ubiquitin systems mark pathogen-containing vacuoles as targets for host defense by guanylate binding proteins

2015 ◽  
Vol 112 (41) ◽  
pp. E5628-E5637 ◽  
Author(s):  
Arun K. Haldar ◽  
Clémence Foltz ◽  
Ryan Finethy ◽  
Anthony S. Piro ◽  
Eric M. Feeley ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Microbial Growth ◽  
E3 Ubiquitin Ligase ◽  
Host Cells ◽  
Tnf Receptor ◽  
Host Proteins ◽  
Growth And Survival ◽  
Guanylate Binding Protein ◽  
Rhoptry Protein ◽  
Necrosis Factor

Many microbes create and maintain pathogen-containing vacuoles (PVs) as an intracellular niche permissive for microbial growth and survival. The destruction of PVs by IFNγ-inducible guanylate binding protein (GBP) and immunity-related GTPase (IRG) host proteins is central to a successful immune response directed against numerous PV-resident pathogens. However, the mechanism by which IRGs and GBPs cooperatively detect and destroy PVs is unclear. We find that host cell priming with IFNγ prompts IRG-dependent association of Toxoplasma- and Chlamydia-containing vacuoles with ubiquitin through regulated translocation of the E3 ubiquitin ligase tumor necrosis factor (TNF) receptor associated factor 6 (TRAF6). This initial ubiquitin labeling elicits p62-mediated escort and deposition of GBPs to PVs, thereby conferring cell-autonomous immunity. Hypervirulent strains of Toxoplasma gondii evade this process via specific rhoptry protein kinases that inhibit IRG function, resulting in blockage of downstream PV ubiquitination and GBP delivery. Our results define a ubiquitin-centered mechanism by which host cells deliver GBPs to PVs and explain how hypervirulent parasites evade GBP-mediated immunity.

scholarly journals Herpes Simplex Virus 1 E3 Ubiquitin Ligase ICP0 Protein Inhibits Tumor Necrosis Factor Alpha-Induced NF-κB Activation by Interacting with p65/RelA and p50/NF-κB1

2013 ◽  
Vol 87 (23) ◽  
pp. 12935-12948 ◽  
Author(s):  
Jie Zhang ◽  
Kezhen Wang ◽  
Shuai Wang ◽  
Chunfu Zheng
Keyword(s):  
Tumor Necrosis Factor ◽  
Ubiquitin Ligase ◽  
Tumor Necrosis ◽  
Nuclear Translocation ◽  
E3 Ubiquitin Ligase ◽  
Necrosis Factor Alpha ◽  
Tnf Α ◽  
Factor Alpha ◽  
Necrosis Factor ◽  
Hsv 1

NF-κB plays central roles in regulation of diverse biological processes, including innate and adaptive immunity and inflammation. HSV-1 is the archetypal member of the alphaherpesviruses, with a large genome encoding over 80 viral proteins, many of which are involved in virus-host interactions and show immune modulatory capabilities. In this study, we demonstrated that the HSV-1 ICP0 protein, a viral E3 ubiquitin ligase, was shown to significantly suppress tumor necrosis factor alpha (TNF-α)-mediated NF-κB activation. ICP0 was demonstrated to bind to the NF-κB subunits p65 and p50 by coimmunoprecipitation analysis. ICP0 bound to the Rel homology domain (RHD) of p65. Fluorescence microscopy demonstrated that ICP0 abolished nuclear translocation of p65 upon TNF-α stimulation. Also, ICP0 degraded p50 via its E3 ubiquitin ligase activity. The RING finger (RF) domain mutant ICP0 (ICP0-RF) lost its ability to inhibit TNF-α-mediated NF-κB activation and p65 nuclear translocation and degrade p50. Notably, the RF domain of ICP0 was sufficient to interact with p50 and abolish NF-κB reporter gene activity. Here, it is for the first time shown that HSV-1 ICP0 interacts with p65 and p50, degrades p50 through the ubiquitin-proteasome pathway, and prevents NF-κB-dependent gene expression, which may contribute to immune evasion and pathogenesis of HSV-1.

scholarly journals NOD1 is super-activated through spatially-selective ubiquitination by the Salmonella effector SspH2

2021 ◽  
Author(s):  
Cole Delyea ◽  
Shu Luo ◽  
Bradley E Dubrule ◽  
Olivier Julien ◽  
Amit P Bhavsar
Keyword(s):  
Mass Spectrometry ◽  
Ubiquitin Ligase ◽  
Inflammatory Cytokine ◽  
E3 Ubiquitin Ligase ◽  
Cytokine Secretion ◽  
Host Cells ◽  
List Type ◽  
The Novel ◽  
Inflammatory Signaling ◽  
Lysine Residues

As part of its pathogenesis, Salmonella enterica serovar Typhimurium delivers effector proteins into host cells. One effector is SspH2, a member of the novel E3 ubiquitin ligase family, interacts with, and enhances, NOD1 pro-inflammatory signaling, though the underlying mechanisms are unclear. Here, we report the novel discovery that SspH2 interacts with multiple members of the NLRC family to enhance pro-inflammatory signaling that results from targeted ubiquitination. We show that SspH2 modulates host innate immunity by interacting with both NOD1 and NOD2 in mammalian epithelial cell culture. We also show that SspH2 specifically interacts with the NBD and LRR domains of NOD1 and super-activates NOD1- and NOD2-mediated cytokine secretion via the NF-κB pathway. Mass spectrometry analyses identified lysine residues in NOD1 that were ubiquitinated after interaction with SspH2. Through NOD1 mutational analyses, we identified four key lysine residues that are required for NOD1 super-activation by SspH2, but not its basal activity. These critical lysine residues are positioned in the same region of NOD1 and define a surface on NOD1 that is targeted by SspH2. Overall, this work provides evidence for post-translational modification of NOD1 by ubiquitin, and uncovers a unique mechanism of spatially-selective ubiquitination to enhance the activation of an archetypal NLR.

scholarly journals The E3 Ubiquitin Ligase Siah-1 Suppresses Avian Reovirus Infection by Targeting p10 for Degradation

2018 ◽  
Vol 92 (6) ◽  
Author(s):  
Xiang Chen ◽  
Zhiyuan He ◽  
Mengjiao Fu ◽  
Yongqiang Wang ◽  
Haiyang Wu ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Ubiquitin Ligase ◽  
Respiratory Diseases ◽  
E3 Ubiquitin Ligase ◽  
Syncytium Formation ◽  
Host Cells ◽  
Avian Reovirus ◽  
Chronic Respiratory Diseases ◽  
Multicomponent Complex ◽  
Seven In Absentia

ABSTRACTAvian reovirus (ARV) causes viral arthritis, chronic respiratory diseases, retarded growth, and malabsorption syndrome. The ARV p10 protein, a viroporin responsible for the induction of cell syncytium formation and apoptosis, is rapidly degraded in host cells. Our previous report demonstrated that cellular lysosome-associated membrane protein 1 (LAMP-1) interacted with p10 and was involved in its degradation. However, the molecular mechanism underlying LAMP-1-mediated p10 degradation remains elusive. We report here that the E3 ubiquitin ligase seven in absentia homolog 1 (Siah-1) is critical for p10 ubiquitylation. Our data show that Siah-1 ubiquitylated p10 and targeted it for proteasome degradation. Furthermore, the ubiquitylation of p10 by Siah-1 required the participation of LAMP-1 by forming a multicomponent complex. Thus, LAMP-1 promotes the proteasomal degradation of p10 via interacting with both p10 and the E3 ligase Siah-1. These data establish a novel host defense mechanism where LAMP-1 serves as a scaffold for both Siah-1 and p10 that allows the E3 ligase targeting p10 for ubiquitylation and degradation to suppress ARV infection.IMPORTANCEAvian reovirus (ARV) is an important poultry pathogen causing viral arthritis, chronic respiratory diseases, retarded growth, and malabsorption syndrome, leading to considerable economic losses to the poultry industry across the globe. The ARV p10 protein is a virulence factor responsible for the induction of cell syncytium formation and apoptosis and is rapidly degraded in host cells. We previously found that cellular lysosome-associated membrane protein 1 (LAMP-1) interacts with p10 and is involved in its degradation. Here we report that the E3 ubiquitin ligase seven in absentia homolog 1 (Siah-1) ubiquitylated p10 and targeted it for proteasomal degradation. Furthermore, the ubiquitylation of p10 by Siah-1 required the participation of LAMP-1 by forming a multicomponent complex. Thus, LAMP-1 serves as an adaptor to allow Siah-1 to target p10 for degradation, thereby suppressing ARV growth in host cells.

scholarly journals THP-1 Cell Apoptosis in Response to Mycobacterial Infection

2003 ◽  
Vol 71 (1) ◽  
pp. 254-259 ◽  
Author(s):  
Carrie J. Riendeau ◽  
Hardy Kornfeld
Keyword(s):  
Alveolar Macrophages ◽  
Mycobacterial Infection ◽  
Host Cells ◽  
Tnf Receptor ◽  
Wild Type ◽  
Necrosis Factor Alpha ◽  
Retroviral Transduction ◽  
Tnf Α ◽  
Factor Alpha ◽  
Necrosis Factor

ABSTRACT We previously reported that Mycobacterium tuberculosis infection primes human alveolar macrophages (HAM) for tumor necrosis factor alpha (TNF-α)-mediated apoptosis and that macrophage apoptosis is associated with killing internalized bacilli. Virulent mycobacterial strains elicit much less apoptosis than attenuated strains, implying that apoptosis is a defense against intracellular infection. The present study evaluated the potential for phorbol myristate acetate-differentiated THP-1 cells to mimic this response of primary macrophages. Consistent with the behavior of alveolar macrophages, attenuated M. tuberculosis H37Ra and Mycobacterium bovis BCG strongly induce THP-1 apoptosis, which requires endogenous TNF. THP-1 apoptosis is associated with reduced viability of infecting BCG. In contrast, virulent wild-type M. tuberculosis H37Rv and M. bovis do not increase THP-1 apoptosis over baseline. BCG induced early activation of caspase 10 and 9, followed by caspase 3. In contrast, wild-type M. bovis infection failed to activate any caspases in THP-1 cells. BCG-induced THP-1 apoptosis is blocked by retroviral transduction with vectors expressing crmA but not bcl-2. We conclude that differentiated THP-1 cells faithfully model the apoptosis response of HAM. Analysis of the THP-1 cell response to infection with virulent mycobacteria suggests that TNF death signals are blocked proximal to initiator caspase activation, at the level of TNF receptor 1 or its associated intracytoplasmic adaptor complex. Interference with TNF death signaling may be a virulence mechanism that allows M. tuberculosis to circumvent innate defenses leading to apoptosis of infected host cells.

scholarly journals TNF receptor–associated factor 6 interacts with ALS-linked misfolded superoxide dismutase 1 and promotes aggregation

2020 ◽  
Vol 295 (12) ◽  
pp. 3808-3825 ◽  
Author(s):  
Sabrina Semmler ◽  
Myriam Gagné ◽  
Pranav Garg ◽  
Sarah R. Pickles ◽  
Charlotte Baudouin ◽  
...  
Keyword(s):  
Superoxide Dismutase ◽  
Motor Neurons ◽  
Ubiquitin Ligase ◽  
Protein Misfolding ◽  
E3 Ubiquitin Ligase ◽  
Tnf Receptor ◽  
Superoxide Dismutase 1 ◽  
Associated Factor ◽  
Independent Events ◽  
Misfolded Sod1

Amyotrophic lateral sclerosis (ALS) is a fatal disease, characterized by the selective loss of motor neurons leading to paralysis. Mutations in the gene encoding superoxide dismutase 1 (SOD1) are the second most common cause of familial ALS, and considerable evidence suggests that these mutations result in an increase in toxicity due to protein misfolding. We previously demonstrated in the SOD1G93A rat model that misfolded SOD1 exists as distinct conformers and forms deposits on mitochondrial subpopulations. Here, using SOD1G93A rats and conformation-restricted antibodies specific for misfolded SOD1 (B8H10 and AMF7-63), we identified the interactomes of the mitochondrial pools of misfolded SOD1. This strategy identified binding proteins that uniquely interacted with either AMF7-63 or B8H10-reactive SOD1 conformers as well as a high proportion of interactors common to both conformers. Of this latter set, we identified the E3 ubiquitin ligase TNF receptor–associated factor 6 (TRAF6) as a SOD1 interactor, and we determined that exposure of the SOD1 functional loops facilitates this interaction. Of note, this conformational change was not universally fulfilled by all SOD1 variants and differentiated TRAF6 interacting from TRAF6 noninteracting SOD1 variants. Functionally, TRAF6 stimulated polyubiquitination and aggregation of the interacting SOD1 variants. TRAF6 E3 ubiquitin ligase activity was required for the former but was dispensable for the latter, indicating that TRAF6-mediated polyubiquitination and aggregation of the SOD1 variants are independent events. We propose that the interaction between misfolded SOD1 and TRAF6 may be relevant to the etiology of ALS.

scholarly journals TNF receptor associated factor 6 interacts with ALS-linked misfolded superoxide dismutase 1 and promotes aggregation

2019 ◽  
Author(s):  
Sabrina Semmler ◽  
Myriam Gagné ◽  
Pranav Garg ◽  
Sarah Pickles ◽  
Charlotte Baudouin ◽  
...  
Keyword(s):  
Superoxide Dismutase ◽  
Motor Neurons ◽  
Ubiquitin Ligase ◽  
Protein Misfolding ◽  
E3 Ubiquitin Ligase ◽  
Tnf Receptor ◽  
Gene Encoding ◽  
Associated Factor ◽  
Independent Events ◽  
Misfolded Sod1

ABSTRACTAmyotrophic lateral sclerosis (ALS) is a fatal disease, characterized by the selective loss of motor neurons leading to paralysis. Mutations in the gene encoding superoxide dismutase 1 (SOD1) are the second most common cause of familial ALS, and considerable evidence suggests that these mutations result in an increase in toxicity due to protein misfolding. We previously demonstrated in the SOD1G93A rat model that misfolded SOD1 exists as distinct conformers and forms deposits on mitochondrial subpopulations. Here, using SOD1G93A rats and conformation-restricted antibodies specific for misfolded SOD1 (B8H10 and AMF7-63), we identified the interactomes of the mitochondrial pools of misfolded SOD1. This strategy identified binding proteins that uniquely interacted with either AMF7-63 or B8H10-reactive SOD1 conformers as well as with a high proportion of interactors common to both conformers. Of this latter set, we identified the E3 ubiquitin ligase TNF receptor-associated factor 6 (TRAF6) as a SOD1 interactor and determined that exposure of the SOD1 functional loops facilitates this interaction. Of note, this conformational change was not universally fulfilled by all SOD1 variants and differentiated TRAF6-interacting from TRAF6 non-interacting SOD1 variants. Functionally, TRAF6 stimulated polyubiquitination and aggregation of the interacting SOD1 variants. TRAF6 E3 ubiquitin ligase activity was required for the former, but was dispensable for the latter, indicating that TRAF6-mediated polyubiquitination and aggregation of the SOD1 variants are independent events. We propose that the interaction between misfolded SOD1 and TRAF6 may be relevant to the etiology of ALS.

scholarly journals A dominant-negative F-box deleted mutant of E3 ubiquitin ligase, β-TrCP1/FWD1, markedly reduces myeloma cell growth and survival in mice

Oncotarget ◽  
2015 ◽  
Vol 6 (25) ◽  
pp. 21589-21602 ◽  
Author(s):  
Ramaswamy Sharma ◽  
Paul J. Williams ◽  
Anjana Gupta ◽  
Brandon McCluskey ◽  
Shylesh Bhaskaran ◽  
...  
Keyword(s):  
Cell Growth ◽  
Ubiquitin Ligase ◽  
E3 Ubiquitin Ligase ◽  
Myeloma Cell ◽  
Dominant Negative ◽  
Growth And Survival ◽  
Cell Growth And Survival

scholarly journals Human cytomegalovirus protein RL1 degrades the antiviral factor SLFN11 via recruitment of the CRL4 E3 ubiquitin ligase complex

2021 ◽  
Author(s):  
Katie Nightingale ◽  
Ceri A Fielding ◽  
Cassie Zerbe ◽  
Leah Hunter ◽  
Martin Potts ◽  
...  
Keyword(s):  
Human Cytomegalovirus ◽  
Ubiquitin Ligase ◽  
Immune Evasion ◽  
E3 Ubiquitin Ligase ◽  
Restriction Factor ◽  
Host Proteins ◽  
Viral Immune Evasion ◽  
Tandem Mass Tag ◽  
Ubiquitin Ligase Complex ◽  
Antiviral Innate Immunity

Human cytomegalovirus (HCMV) is an important human pathogen and a paradigm of viral immune evasion, targeting intrinsic, innate and adaptive immunity. We have employed two novel, orthogonal multiplexed tandem mass tag-based proteomic screens to identify host proteins downregulated by viral factors expressed during the latest phases of viral infection. This approach revealed that the HIV-1 restriction factor Schlafen-11 (SLFN11) was degraded by the poorly characterised, late-expressed HCMV protein RL1, via recruitment of the Cullin4-RING E3 Ubiquitin Ligase (CRL4) complex. SLFN11 potently restricted HCMV infection, inhibiting the formation and spread of viral plaques. Overall, we show that a restriction factor previously thought only to inhibit RNA viruses additionally restricts HCMV. We define the mechanism of viral antagonism and also describe an important resource for revealing additional molecules of importance in antiviral innate immunity and viral immune evasion.

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