201
|
Richards KH, Macdonald A. Putting the brakes on the anti-viral response: negative regulators of type I interferon (IFN) production. Microbes Infect 2011; 13:291-302. [PMID: 21256242 DOI: 10.1016/j.micinf.2010.12.007] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Revised: 12/23/2010] [Accepted: 12/27/2010] [Indexed: 12/23/2022]
Abstract
Type I IFNs (IFNα/β) are essential anti-viral cytokines produced in response to the detection of viral components by host pattern recognition receptors. IFNα/β production is transient, and aberrant activation can be hazardous to the host. In this article, we review our current understanding of host negative regulatory mechanisms that control IFNα/β production.
Collapse
Affiliation(s)
- Kathryn H Richards
- Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | | |
Collapse
|
202
|
Young JA, Sermwittayawong D, Kim HJ, Nandu S, An N, Erdjument-Bromage H, Tempst P, Coscoy L, Winoto A. Fas-associated death domain (FADD) and the E3 ubiquitin-protein ligase TRIM21 interact to negatively regulate virus-induced interferon production. J Biol Chem 2010; 286:6521-31. [PMID: 21183682 DOI: 10.1074/jbc.m110.172288] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The production of cytokines such as type I interferon (IFN) is an essential component of innate immunity. Insufficient amounts of cytokines lead to host sensitivity to infection, whereas abundant cytokine production can lead to inflammation. A tight regulation of cytokine production is, thus, essential for homeostasis of the immune system. IFN-α production during RNA virus infection is mediated by the master transcription factor IRF7, which is activated upon ubiquitination by TRAF6 and phosphorylation by IKKε and TBK1 kinases. We found that Fas-associated death domain (FADD), first described as an apoptotic protein, is involved in regulating IFN-α production through a novel interaction with TRIM21. TRIM21 is a member of a large family of proteins that can impart ubiquitin modification onto its cellular targets. The interaction between FADD and TRIM21 enhances TRIM21 ubiquitin ligase activity, and together they cooperatively repress IFN-α activation in Sendai virus-infected cells. FADD and TRIM21 can directly ubiquitinate IRF7, affect its phosphorylation status, and interfere with the ubiquitin ligase activity of TRAF6. Conversely, a reduction of FADD and TRIM21 levels leads to higher IFN-α induction, IRF7 phosphorylation, and lower titers of RNA virus of infected cells. We conclude that FADD and TRIM21 together negatively regulate the late IFN-α pathway in response to viral infection.
Collapse
Affiliation(s)
- Jennifer A Young
- Cancer Research Laboratory and Department of Molecular and Cellular Biology, University of California, Berkeley, California 94720, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
203
|
McNab FW, Rajsbaum R, Stoye JP, O'Garra A. Tripartite-motif proteins and innate immune regulation. Curr Opin Immunol 2010; 23:46-56. [PMID: 21131187 DOI: 10.1016/j.coi.2010.10.021] [Citation(s) in RCA: 200] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Accepted: 10/29/2010] [Indexed: 11/19/2022]
Abstract
The tripartite motif containing (TRIM) proteins are a family of proteins that have been implicated in many biological processes including cell differentiation, apoptosis, transcriptional regulation and signaling pathways. Many TRIM proteins are upregulated by the immunologically important Type I and Type II interferons and several, including TRIM5α and TRIM19/PML, restrict viral replication. There is growing evidence that TRIMs also play an important role in the broader immune response through regulating signaling pathways such as the RIG-I pathway. In this review we discuss recent research elucidating TRIM regulation of a number of pathways important in immunity and review the latest findings relating to viral restriction by TRIMs.
Collapse
Affiliation(s)
- Finlay W McNab
- Division of Immunoregulation, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK
| | | | | | | |
Collapse
|
204
|
Wenzel J, Zahn S, Tüting T. Pathogenesis of cutaneous lupus erythematosus: common and different features in distinct subsets. Lupus 2010; 19:1020-8. [PMID: 20693195 DOI: 10.1177/0961203310370046] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The term 'cutaneous lupus erythematosus' (CLE) comprises several related autoimmune skin disorders, defined as 'specific' skin manifestations of lupus erythematosus (LE). The spectrum of clinical presentation of CLE is wide, reaching from mild erythema to disseminated scarring skin lesions. There is increasing knowledge concerning the pathogenesis of LE skin lesions and it has been shown that a complex network of cutaneous cytokines, chemokines and adhesion molecules orchestrate and promote tissue injury observed in LE skin lesions. However, a complete understanding of the diverse pathophysiological mechanisms in the different CLE subsets does not exist. Here we review the main pathological features described in CLE patients against the background of the clinical diversity of different CLE subtypes.
Collapse
Affiliation(s)
- J Wenzel
- Department of Dermatology, University of Bonn, Germany.
| | | | | |
Collapse
|
205
|
Abstract
Cutaneous lupus erythematosus (CLE) may present as a clinically heterogeneous group of lupus-specific skin lesions that have common histopathological findings. Determination of the immunopathological sequence of events in this group of disorders has been challenging for dermatologists and immunologists but is vital for therapeutic targeting. We review animal models in which different aspects of immune alteration in CLE have been addressed. The MRL/lpr mouse develops spontaneous skin disease with some features of CLE. Study of this strain and related gene-manipulated strains has revealed roles for multiple cytokines, including interleukin (IL)-6, IL-18, and IL-21, in disease pathogenesis. A role for the growth factor colony stimulating factor 1 and the inflammatory protein high-mobility group box 1 has also been suggested. We discuss potential novel treatment options suggested by these models.
Collapse
Affiliation(s)
- M Ghoreishi
- Department of Dermatology and Skin Science and Child and Family Research Institute, University of British Columbia, Canada
| | | |
Collapse
|
206
|
B-cell epitopes of the intracellular autoantigens Ro/SSA and La/SSB: Tools to study the regulation of the autoimmune response. J Autoimmun 2010; 35:256-64. [DOI: 10.1016/j.jaut.2010.06.016] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
207
|
Abstract
BACKGROUND Primary Sjogren's syndrome (pSS) is characterized by the presence of autoantibodies targeting mainly the Ro/La ribonucleoprotein complex. It is now appreciated that the production of autoantibodies is an antigen-driven immune response. DESIGN In this review, candidate mechanisms for autoantigen presentation and perpetuation of the autoimmune response within the autoimmune tissue lesion of pSS are discussed. RESULTS Several studies have shown that the epithelial cell in labial salivary glands of patients with Sjogren's syndrome is activated, bearing characteristics of an antigen-presenting cell, as suggested by inappropriate expression of class II HLA and co-stimulatory molecules. Other studies have confirmed that in salivary glands, there is an increased autoantigen presentation via apoptotic blebs and bodies, exosomes and heat shock protein-mediated cross-priming. There is also an increased expression of interferon (IFN)-induced genes, such as the autoantigen Ro52, which provide negative feedback regulation in inflammation. Ro60 and La autoantigens also appear to play a major role in the local autoimmune response in Sjogren's syndrome. In this regard, La and Ro60 the messenger RNA (mRNA) expression is upregulated in the affected salivary glands with different isoforms of La autoantigen mRNA to be expressed in patients with pSS. At the protein level, La/SSB in pSS salivary glands is found to be post-translationally modified. CONCLUSIONS Autoantigen alterations in a microenvironment of local inflammation with increased in situ apoptosis, Toll-like receptor (TLR) signalling and antigen presentation may drive the autoimmune response and local autoantibody production in pSS.
Collapse
Affiliation(s)
- John G Routsias
- Department of Pathophysiology, School of Medicine, University of Athens, Greece
| | | |
Collapse
|
208
|
Mavragani CP, Crow MK. Activation of the type I interferon pathway in primary Sjogren’s syndrome. J Autoimmun 2010; 35:225-31. [DOI: 10.1016/j.jaut.2010.06.012] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
|
209
|
Wahren-Herlenius M. Immunological contribution to the pathogenesis of congenital heart block. Scand J Immunol 2010; 72:171-2. [PMID: 20696012 DOI: 10.1111/j.1365-3083.2010.02446.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
210
|
Hutter D, Silverman ED, Jaeggi ET. The benefits of transplacental treatment of isolated congenital complete heart block associated with maternal anti-Ro/SSA antibodies: a review. Scand J Immunol 2010; 72:235-41. [PMID: 20696021 DOI: 10.1111/j.1365-3083.2010.02440.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Isolated congenital complete atrio-ventricular block (CAVB) is associated with the transplacental passage of maternal autoantibodies directed to foetal Ro/SSA ribonucleoproteins. Their interactions most likely trigger the inflammation of the atrio-ventricular node and the myocardium in susceptible foetuses. The inflamed tissues may then heal with fibrosis that may cause heart block, endocardial fibroelastosis, and dilated cardiomyopathy. CAVB, the most common cardiac complication, typically develops between 18 and 24 gestational weeks. Untreated, the condition carries a significant mortality risk as the foetus needs to overcome the sudden drop in ventricular rate, the loss of normal atrial systolic contribution to ventricular filling, and perhaps concomitant myocardial inflammation and fibrosis. The rationale to treat a foetus at the stage of CAVB is primarily to mitigate myocardial inflammation and to augment foetal cardiac output. Maternal dexamethasone administration has been shown to improve incomplete foetal AV block, myocardial dysfunction, and cavity effusions. Beta-sympathomimetics may be useful to increase the foetal heart rate and myocardial contractility. Published data from our institution suggest an improved survival >90% if maternal high-dose dexamethasone was initiated at the time of CAVB detection and maintained during the pregnancy and if a beta-adrenergic drug was added at foetal heart rates below 55 beats/min. Despite the improvement in outcome, there is an ongoing debate about treatment-related risks. In this review, we will appraise the natural history of untreated CAVB, discuss currently available management options, and examine the results and risks of in-utero treatment of antibody-mediated CAVB.
Collapse
Affiliation(s)
- D Hutter
- Division of Cardiology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | | | | |
Collapse
|
211
|
Abstract
IMPORTANCE OF THE FIELD IL-23 is one of the most intriguing cytokine for its many immunological functions, which are the basis of its important role in host defense but also of its possible contribution to the pathogenesis of several diseases. AREAS COVERED IN THIS REVIEW The literature and patents about IL-23 pathway and their targeting in therapeutic potential applications. Findings published within the last 5 years receive particular attention. WHAT THE READER WILL GAIN An overview of the emerging role of IL-23 in physiological and pathological conditions and a review of the different approaches (IL-23 pathway-based) currently used for autoimmune diseases and cancer therapies and the results obtained both in preclinical models and in clinical trials. TAKE HOME MESSAGE Inhibition/targeting of IL-23 may be a good and novel therapeutic strategy, especially in the treatment of diseases like psoriasis, for which current treatments show more pronounced side effects than those of IL-23-blocking and employed as part of specific patient-tailored therapies in inflammatory bowel diseases.
Collapse
Affiliation(s)
- Mario M D'Elios
- University of Florence, Department of Internal Medicine, Viale Morgagni 85, 50134 Florence, Italy
| | | | | |
Collapse
|
212
|
|
213
|
Abstract
A healthy ocular surface environment is essential to preserve visual function, and as such the eye has evolved a complex network of mechanisms to maintain homeostasis. Fundamental to the health of the ocular surface is the immune system, designed to respond rapidly to environmental and microbial insults, whereas maintaining tolerance to self-antigens and commensal microbes. To this end, activation of the innate and adaptive immune response is tightly regulated to limit bystander tissue damage. However, aberrant activation of the immune system can result in autoimmunity to self-antigens localized to the ocular surface and associated tissues. Environmental, microbial and endogenous stress, antigen localization, and genetic factors provide the triggers underlying the immunological events that shape the outcome of the diverse spectrum of autoimmune-based ocular surface disorders.
Collapse
|
214
|
Winkler MA, Pan AA. Is there a link between the human TRIM21 and Trypanosoma cruzi Clone 36 genes in Chagas' disease? Mol Immunol 2010; 48:365-7. [PMID: 20709399 DOI: 10.1016/j.molimm.2010.07.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Accepted: 07/20/2010] [Indexed: 10/19/2022]
Abstract
The homology between TRIM21 and Trypanosoma cruzi Antigen Clone 36 nucleotide sequence was discovered in 1998 (Winkler et al., Parasite 5, 94-95) prior to the functions of Ro52, the TRIM21 protein product, being understood. Ro52 has since been shown to be an Ubiquitin ligase targeting transcription factors, Interferon Regulatory Factor 1 (IRF1) and Interferon Regulatory Factor 3 (IRF3), in immune cells. This communication explores the possibility that there is a connection between the Clone 36 homologous sequence and perturbation of the host immune system in Chagas' disease. RNA interference by the Clone 36 transcripts is hypothesized as a mechanism for host immune suppression during acute Chagas' disease and/or for autoimmunity in chronic Chagas' disease through down-regulation of Ro52. In the chronic forms of the disease such as Chagas Cardiomyopathy, Clone 36 RNA containing its repetitive motif may down-regulate levels of Ro52 in monocytes, fibroblasts, or T cells, allowing IRF 1 and IRF3 to continuously stimulate transcription of interferons alpha and beta, a pro-inflammatory state favoring autoimmunity. In acute Chagas' disease, messenger RNA from Clone 36 could interfere with host macrophage Ro52 RNA, down-regulating the level of Ro52 so that it would stimulate less cytokine production, including IL-12/p40. This theory is thought to help the parasite avoid attack by the innate immune system early in the acute phase of the disease. Experiments with transgenic mice and genetically modified T. cruzi are discussed which may provide insight to addressing these questions.
Collapse
Affiliation(s)
- Martin A Winkler
- Biotech Advisor, 1995 Via Tesoro, Las Cruces, NM 88005-8211, USA.
| | | |
Collapse
|
215
|
Tanaka M, Kamitani T. Cytoplasmic relocation of Daxx induced by Ro52 and FLASH. Histochem Cell Biol 2010; 134:297-306. [PMID: 20697732 DOI: 10.1007/s00418-010-0734-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/27/2010] [Indexed: 12/23/2022]
Abstract
The RING-finger protein Ro52/TRIM21 is known to be an autoantigen and is recognized by anti-Ro/SSA antibodies, which are commonly found in patients with Sjögren's syndrome and systemic lupus erythematosus. We recently showed that Ro52 is an E3 ubiquitin ligase and localizes to cytoplasmic bodies that are highly motile along the microtubule network. To expand our knowledge of Ro52, we searched partners co-operating with Ro52. We performed a yeast two-hybrid screening of a human brain cDNA library with Ro52 as bait. This screening identified several genes encoding Ro52-interacting proteins, including the apoptosis-related proteins, Daxx and FLASH. Further yeast two-hybrid assays revealed that Daxx binds to the B30.2 domain of Ro52 and that FLASH binds to coiled-coil domains of Ro52 through its death-effector domain-recruiting domain. These results suggest that Ro52, Daxx, and FLASH form heteromeric protein complexes. Indeed, this was supported by results of immunoprecipitation experiments in which we found that Daxx is co-immunoprecipitated with Ro52 in the presence of overexpressed FLASH. Importantly, our fluorescence microscopy revealed that, although Daxx is predominantly located in the nucleus, overexpression of both Ro52 and FLASH leads to relocation of Daxx into the cytoplasm. Thus, Ro52 seems to co-operate with FLASH to induce cytoplasmic localization of Daxx in cells.
Collapse
Affiliation(s)
- Makoto Tanaka
- Department of Medicine, Center for Molecular Chaperone/Radiobiology and Cancer Virology, MCG Cancer Center, Medical College of Georgia, 1410 Laney Walker Blvd., CN-3141, Augusta, GA 30912, USA
| | | |
Collapse
|
216
|
Abstract
Sjögren's syndrome (SS), a chronic autoimmune disorder, particularly compromises the function of exocrine glands. The involvement of these glands is characterized by focal, mononuclear cell infiltrates that surround the ducts and replace the secretory units. The pathogenetic mechanisms of this autoimmune exocrinopathy have not been fully elucidated. Immunologically-activated or apoptotic glandular epithelial cells that expose autoantigens in genetically predisposed individuals might drive autoimmune-mediated tissue injury. Alterations in several immune mediators, such as upregulation of type I interferon-regulated genes, abnormal expression of B-cell-activating factor and activation of the interleukin-23-type 17 T-helper cell pathway, have been reported. Extension of the pathological process that affects the exocrine glands into periepithelial and extraepithelial tissue can cause a considerable percentage of patients to exhibit systemic findings that involve the lungs, liver or kidneys. These manifestations develop as a result of lymphocytic invasion or an immune-complex-mediated process, or both, and present as skin vasculitis coupled with peripheral neuropathy or glomerulonephritis (or both). Patients with systemic extraepithelial manifestations display low serum levels of the complement component C4 and mixed type II cryoglobulins, and show an increased risk of developing non-Hodgkin lymphoma, thereby reflecting an overall worse prognosis with higher mortality rates than those without extraepithelial manifestations.
Collapse
|
217
|
Mok MY, Wu HJ, Lo Y, Lau CS. The relation of interleukin 17 (IL-17) and IL-23 to Th1/Th2 cytokines and disease activity in systemic lupus erythematosus. J Rheumatol 2010; 37:2046-52. [PMID: 20682672 DOI: 10.3899/jrheum.100293] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVE Interleukin 17 (IL-17) was recently linked to pathogenesis of systemic lupus erythematosus (SLE), but its relation to disease activity has not been well characterized. We examined the relation between serum levels of Th17 (IL-17, IL-23), Th1 (IL-12, interferon-γ), Th2 (IL-10, IL-6, IL-4) cytokines and disease activity in patients with SLE. METHODS Serum cytokines were measured by enzyme linked immunosorbent assays. Disease activity was determined by SLE disease activity index (SLEDAI), anti-dsDNA antibody, and C3 and C4 levels. RESULTS Serum levels of IL-17 (p < 0.001), IL-6 (p = 0.006) and IL-10 (p < 0.001) were higher in SLE patients (n = 70) compared to healthy controls (n = 36). Higher serum IL-23 level was found in patients with active disease with cutaneous manifestations (p = 0.004) and serositis (p = 0.04) compared to those without. Serum IL-17 level above the detection limit was more frequently found in patients who had active lupus nephritis (11/23, 47.8%) (p = 0.002), nonrenal active disease (9/15, 60%) (p = 0.001), and inactive lupus (21/32, 65.6%) (p < 0.001) compared to healthy controls (0%). Serum IL-17 levels were otherwise comparable between these 3 groups of patients and were not related to SLEDAI, glomerular filtration rate, activity or chronicity score and ISN/RPS criteria class among patients with active lupus nephritis. There was no significant correlation between serum IL-17/IL-23 and Th1 or Th2 cytokine levels. CONCLUSION SLE patients had higher serum IL-17 levels than healthy controls. Elevated serum IL-23 was found in patients with inflammatory manifestations including cutaneous involvement and serositis. The lack of correlation between Th17, Th1, and Th2 cytokines suggested independent regulatory mechanisms for these cytokines.
Collapse
Affiliation(s)
- Mo Yin Mok
- Division of Rheumatology and Clinical Immunology, Department of Medicine, Queen Mary Hospital, Hong Kong.
| | | | | | | |
Collapse
|
218
|
Niida M, Tanaka M, Kamitani T. Downregulation of active IKK beta by Ro52-mediated autophagy. Mol Immunol 2010; 47:2378-87. [PMID: 20627395 PMCID: PMC2918734 DOI: 10.1016/j.molimm.2010.05.004] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Accepted: 05/05/2010] [Indexed: 01/20/2023]
Abstract
Upon activation, NF-kappaB translocates into the nucleus and initiates many biological events. This NF-kappaB signaling is mainly induced by the protein kinase IKK beta. Early in this signaling pathway, IKK beta is phosphorylated for activation by several factors, such as pro-inflammatory cytokines and the Tax oncoprotein of human T-cell leukemia virus type 1 (HTLV-1). In cells expressing Tax protein, IKK beta is persistently phosphorylated, which chronically activates NF-kappaB signaling. But the active IKK beta is conjugated with a monoubiquitin by the E3 ubiquitin ligase Ro52, and the IKK beta-induced NF-kappaB signaling is downregulated. However, the mechanism of the downregulation has been unknown. Here, we show that Ro52-mediated monoubiquitination is involved in the subcellular translocation of active IKK beta to autophagosomes. Furthermore, using reporter assays, we show that Ro52 suppresses IKK beta-induced NF-kappaB signaling and that this suppression is blocked by an autophagy inhibitor. These results suggest that Ro52-mediated monoubiquitination plays a critical role in the downregulation of active IKK beta through autophagy.
Collapse
Affiliation(s)
- Motoko Niida
- Department of Cardiology, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA
| | | | | |
Collapse
|
219
|
Higgs R, Lazzari E, Wynne C, Ní Gabhann J, Espinosa A, Wahren-Herlenius M, Jefferies CA. Self protection from anti-viral responses--Ro52 promotes degradation of the transcription factor IRF7 downstream of the viral Toll-Like receptors. PLoS One 2010; 5:e11776. [PMID: 20668674 PMCID: PMC2909902 DOI: 10.1371/journal.pone.0011776] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Accepted: 07/01/2010] [Indexed: 12/23/2022] Open
Abstract
Ro52 is a member of the TRIM family of single-protein E3 ligases and is also a target for autoantibody production in systemic lupus erythematosus and Sjögren's syndrome. We previously demonstrated a novel function of Ro52 in the ubiquitination and proteasomal degradation of IRF3 following TLR3/4 stimulation. We now present evidence that Ro52 has a similar role in regulating the stability and activity of IRF7. Endogenous immunoprecipitation of Ro52-bound proteins revealed that IRF7 associates with Ro52, an effect which increases following TLR7 and TLR9 stimulation, suggesting that Ro52 interacts with IRF7 post-pathogen recognition. Furthermore, we show that Ro52 ubiquitinates IRF7 in a dose-dependent manner, resulting in a decrease in total IRF7 expression and a subsequent decrease in IFN-α production. IRF7 stability was increased in bone marrow-derived macrophages from Ro52-deficient mice stimulated with imiquimod or CpG-B, consistent with a role for Ro52 in the negative regulation of IRF7 signalling. Taken together, these results suggest that Ro52-mediated ubiquitination promotes the degradation of IRF7 following TLR7 and TLR9 stimulation. As Ro52 is known to be IFN-inducible, this system constitutes a negative-feedback loop that acts to protect the host from the prolonged activation of the immune response.
Collapse
Affiliation(s)
- Rowan Higgs
- Molecular and Cellular Therapeutics and RSCI Research Institute, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Elisa Lazzari
- Molecular and Cellular Therapeutics and RSCI Research Institute, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Claire Wynne
- Molecular and Cellular Therapeutics and RSCI Research Institute, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Joan Ní Gabhann
- Molecular and Cellular Therapeutics and RSCI Research Institute, Royal College of Surgeons in Ireland, Dublin, Ireland
| | | | | | - Caroline A. Jefferies
- Molecular and Cellular Therapeutics and RSCI Research Institute, Royal College of Surgeons in Ireland, Dublin, Ireland
- * E-mail:
| |
Collapse
|
220
|
Parvatiyar K, Barber GN, Harhaj EW. TAX1BP1 and A20 inhibit antiviral signaling by targeting TBK1-IKKi kinases. J Biol Chem 2010; 285:14999-15009. [PMID: 20304918 DOI: 10.1074/jbc.m110.109819] [Citation(s) in RCA: 133] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Induction of type I interferons by the transcription factor IRF3 is essential in the initiation of antiviral innate immunity. Activation of IRF3 requires C-terminal phosphorylation by the upstream kinases TBK1-IKKi, where IRF3 phosphorylation promotes dimerization, and subsequent nuclear translocation to the IFNbeta promoter. Recent studies have described the ubiquitin-editing enzyme A20 as a negative regulator of IRF3 signaling by associating with TBK1-IKKi; however, the regulatory mechanism of A20 inhibition remains unclear. Here we describe the adaptor protein, TAX1BP1, as a key regulator of A20 function in terminating signaling to IRF3. Murine embryonic fibroblasts (MEFs) deficient in TAX1BP1 displayed increased amounts of IFNbeta production upon viral challenge compared with WT MEFs. TAX1BP1 inhibited virus-mediated activation of IRF3 at the level of TBK1-IKKi. TAX1BP1 and A20 blocked antiviral signaling by disrupting Lys(63)-linked polyubiquitination of TBK1-IKKi independently of the A20 deubiquitination domain. Furthermore, TAX1BP1 was required for A20 effector function because A20 was defective for the targeting and inactivation of TBK1 and IKKi in Tax1bp1(-)(/)(-) MEFs. Additionally, we found the E3 ubiquitin ligase TRAF3 to play a critical role in promoting TBK1-IKKi ubiquitination. Collectively, our results demonstrate TBK1-IKKi to be novel substrates for A20 and further identify a novel mechanism whereby A20 and TAX1BP1 restrict antiviral signaling by disrupting a TRAF3-TBK1-IKKi signaling complex.
Collapse
Affiliation(s)
- Kislay Parvatiyar
- Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, Florida 33136
| | - Glen N Barber
- Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, Florida 33136; Department of Medicine, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, Florida 33136
| | - Edward W Harhaj
- Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, Florida 33136.
| |
Collapse
|
221
|
Crispín JC, Liossis SNC, Kis-Toth K, Lieberman LA, Kyttaris VC, Juang YT, Tsokos GC. Pathogenesis of human systemic lupus erythematosus: recent advances. Trends Mol Med 2010; 16:47-57. [PMID: 20138006 DOI: 10.1016/j.molmed.2009.12.005] [Citation(s) in RCA: 266] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Revised: 12/21/2009] [Accepted: 12/21/2009] [Indexed: 01/06/2023]
Abstract
Systemic lupus erythematosus (SLE) is an autoimmune disease with manifestations derived from the involvement of multiple organs including the kidneys, joints, nervous system and hematopoietic organs. Immune system aberrations, as well as heritable, hormonal and environmental factors interplay in the expression of organ damage. Recent contributions from different fields have developed our understanding of SLE and reshaped current pathogenic models. Here, we review recent findings that deal with (i) genes associated with disease expression; (ii) immune cell molecular abnormalities that lead to autoimmune pathology; (iii) the role of hormones and sex chromosomes in the development of disease; and (iv) environmental and epigenetic factors thought to contribute to the expression of SLE. Finally, we highlight molecular defects intimately associated with the disease process of SLE that might represent ideal therapeutic targets and disease biomarkers.
Collapse
Affiliation(s)
- José C Crispín
- Division of Rheumatology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | | | | | | | | | | | | |
Collapse
|
222
|
Dynamic movements of Ro52 cytoplasmic bodies along microtubules. Histochem Cell Biol 2009; 133:273-84. [PMID: 20013343 DOI: 10.1007/s00418-009-0669-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/01/2009] [Indexed: 12/22/2022]
Abstract
The RING-finger protein Ro52/TRIM21 is known as an autoantigen and is recognized by anti-Ro/SSA antibodies, which are commonly found in patients with Sjögren's syndrome and systemic lupus erythematosus. Recently, Ro52 has been shown to localize to distinct structures called cytoplasmic bodies and function as an E3 ubiquitin ligase. However, the Ro52 cytoplasmic bodies have not been well characterized. In this study, we investigated the Ro52 cytoplasmic bodies using fluorescence microscopy. This analysis revealed that the Ro52 cytoplasmic bodies are diffusely located in the cytoplasm and exist independently of TRIM5alpha cytoplasmic bodies. Our results further showed that the Ro52 cytoplasmic bodies are not stained with MitoTracker dye and are not colocalized with the proteasome subunit Rpt5, the caveolae component caveolin-1, the endosome markers (EEA1, Rab5, and Rab7), and the lysosome marker LAMP2. These results indicate that the Ro52 cytoplasmic bodies are not mitochondria, proteasome-enriched structures, caveolae, endosomes, or lysosomes. Importantly, the Ro52 cytoplasmic bodies are highly motile and are located along the microtubule network. These results suggest that the Ro52 cytoplasmic bodies are unidentified structures that are transported along the microtubule network.
Collapse
|
223
|
Ozato K, Yoshimi R, Chang TH, Wang H, Atsumi T, Morse HC. Comment on "Gene disruption study reveals a nonredundant role for TRIM21/Ro52 in NF-kappa B-dependent cytokine expression in fibroblasts". JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2009; 183:7619; author reply 720-1. [PMID: 20007569 PMCID: PMC3407881 DOI: 10.4049/jimmunol.0990103] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
224
|
Cheung YH, Loh C, Pau E, Kim J, Wither J. Insights into the genetic basis and immunopathogenesis of systemic lupus erythematosus from the study of mouse models. Semin Immunol 2009; 21:372-82. [DOI: 10.1016/j.smim.2009.10.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2009] [Accepted: 10/23/2009] [Indexed: 01/15/2023]
|
225
|
Abstract
Sjogren's syndrome (SS) is a slowly progressing autoimmune disease, affecting predominantly middle-aged women, with a female to male ratio reaching 9:1. It is characterized by lymphocytic infiltration of the exocrine glands, mainly the lacrimal and salivary glands, resulting in reduced secretory functions and oral and ocular dryness. The syndrome can present alone as primary SS (pSS) or in the context of underlying connective tissue disease as secondary SS (sSS). While the pathogenesis of the disease remains elusive, environmental, genetic and hormonal contributors seem to be involved. Over the last years, compelling evidence has suggested a pivotal role of the epithelium in orchestrating the immune response in the histopathological lesion of Sjogren's syndrome and the term "autoimmune epithelitis" has been proposed as an etiological term. Although the clinical manifestations of pSS patients are mainly those of an autoimmune exocrinopathy, almost half of patients develop extraglandular disease, which may be manifested either by epithelial lymphocytic invasion of lung, liver, or kidney (resulting in interstitial nephritis) or by skin vasculitis, peripheral neuropathy, glomerulonephritis, and low C4 levels. The latter reflect immune-complex mediated disease and confer increased risk for lymphoma development.
Collapse
Affiliation(s)
- Clio P Mavragani
- Department of Experimental Physiology, University of Athens, School of Medicine, Athens, Greece.
| | | |
Collapse
|
226
|
Pseudoviral immunity - a novel concept for lupus. Trends Mol Med 2009; 15:553-61. [PMID: 19896418 DOI: 10.1016/j.molmed.2009.10.004] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2009] [Revised: 09/22/2009] [Accepted: 10/07/2009] [Indexed: 12/24/2022]
Abstract
Systemic lupus erythematosus (SLE or lupus) is a polygenic syndrome of immunity against nuclear autoantigens. Recent data from several fields now suggest 'pseudoviral' immunity as a novel disease concept. Known lupus risk factors commonly compromise those mechanisms that protect chromatin and ribonucleoprotein particles from activating viral nucleic acid sensors. This process activates antigen-presenting cells and induces type I interferons. These central mediators of antiviral immunity have similar proinflammatory roles in lupus, explaining overlapping clinical manifestations, immunopathology and ultrastructural abnormalities in systemic viral infection and lupus. Structurally, chromatin and ribonucleoprotein particles resemble viral particles and have a similar potency to trigger antigen-specific B- and T-cell responses. Therefore, self nucleic acid-driven 'pseudoviral' immunity is evolving as another concept in understanding the pathogenesis of lupus and may offer novel targets for therapy.
Collapse
|
227
|
Bolland S, Garcia-Sastre A. Vicious circle: systemic autoreactivity in Ro52/TRIM21-deficient mice. ACTA ACUST UNITED AC 2009; 206:1647-51. [PMID: 19635865 PMCID: PMC2722177 DOI: 10.1084/jem.20091507] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Dysregulated innate responses, particularly excessive activation of interferon (IFN) pathways, have been implicated in the development of autoimmune pathologies. Autoreactivity frequently targets IFN-inducible genes such as the Ro autoantigens, which ubiquitinate and inhibit interferon regulatory factors (IRFs). A new study validates the role of these common autoantigens in preventing autoimmunity. The findings reveal that injury-induced systemic autoimmune disease is exacerbated in the absence of Ro52/Trim21 and is driven by the IL-23–Th17 pathway.
Collapse
Affiliation(s)
- Silvia Bolland
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Disease, National Institutes of Health, Rockville MD 20852, USA.
| | | |
Collapse
|