101
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Human coronavirus OC43 nucleocapsid protein binds microRNA 9 and potentiates NF-κB activation. J Virol 2013; 88:54-65. [PMID: 24109243 DOI: 10.1128/jvi.02678-13] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The human coronavirus OC43 is a major contributor to the common cold worldwide, though due to its low mortality rate, little research has focused on this human pathogen. The nucleocapsid is an essential structural protein with conserved functions across the coronavirus family. While a multitude of studies have examined nucleocapsid function, none have described the effects of OC43 nucleocapsid on the transcription factor NF-κB. We report that the nucleocapsid protein of OC43 causes potentiation of NF-κB activation. This prolonged activation is the direct result of the ability of the nucleocapsid to bind RNA, specifically microRNA 9 (miR-9), which is a negative regulator of NF-κB. This previously undescribed interaction between virus and host is a potential mechanism of immune evasion in RNA viruses.
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102
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YANG PANPAN, ZHOU TIANSHOU. RECEPTOR-DEPENDENT SENSITIVITY OF NF-κB TO LOW PHYSIOLOGICAL LEVEL. J BIOL SYST 2013. [DOI: 10.1142/s0218339013500186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In the NFκB signaling pathway, cells respond to different concentrations of the TNFα signal by means of NFκB transcription factors. Previous studies showed that most cells are activated under high-dose stimulations and NFκB activation results in oscillations in nuclear NFκB abundance. Here, by analyzing sensitivity gain for the response of the nuclear NFκB to the number of cell-surface receptors under low-dose stimulations, we show that changes in the receptor number can give rise to significant changes in the nonsaturation part of the dose–response curve, where the receptor activation rates are very sensitive to stimulations. In addition, the number of the activated receptors tends to increase in a large range of stimulation dose and can significantly influence the expression of the downstream genes. These results imply that the number of cell-surface receptors plays a role of information encoding like frequency or amplitude encoding described in previous studies.
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Affiliation(s)
- PANPAN YANG
- School of Mathematics and Computational Science, Sun Yat-Sen University, Guangzhou 510275, P.R. China
| | - TIANSHOU ZHOU
- School of Mathematics and Computational Science, Sun Yat-Sen University, Guangzhou 510275, P.R. China
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103
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Yu CJ, Chen YY, Peng SC, Wong DSH, Chuang YJ. Core network identification using parametric sensitivity and multi-way principal component analysis in NFkB signaling network. J Taiwan Inst Chem Eng 2013. [DOI: 10.1016/j.jtice.2013.01.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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104
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Brandes M, Klauschen F, Kuchen S, Germain RN. A systems analysis identifies a feedforward inflammatory circuit leading to lethal influenza infection. Cell 2013; 154:197-212. [PMID: 23827683 PMCID: PMC3763506 DOI: 10.1016/j.cell.2013.06.013] [Citation(s) in RCA: 293] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Revised: 02/13/2013] [Accepted: 06/10/2013] [Indexed: 11/15/2022]
Abstract
For acutely lethal influenza infections, the relative pathogenic contributions of direct viral damage to lung epithelium versus dysregulated immunity remain unresolved. Here, we take a top-down systems approach to this question. Multigene transcriptional signatures from infected lungs suggested that elevated activation of inflammatory signaling networks distinguished lethal from sublethal infections. Flow cytometry and gene expression analysis involving isolated cell subpopulations from infected lungs showed that neutrophil influx largely accounted for the predictive transcriptional signature. Automated imaging analysis, together with these gene expression and flow data, identified a chemokine-driven feedforward circuit involving proinflammatory neutrophils potently driven by poorly contained lethal viruses. Consistent with these data, attenuation, but not ablation, of the neutrophil-driven response increased survival without changing viral spread. These findings establish the primacy of damaging innate inflammation in at least some forms of influenza-induced lethality and provide a roadmap for the systematic dissection of infection-associated pathology.
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Affiliation(s)
- Marlène Brandes
- Lymphocyte Biology Section, Laboratory of Systems Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Frederick Klauschen
- Institut für Pathologie, Charité - Universitätsmedizin Berlin, Campus Mitte, 10117 Berlin, Germany
| | - Stefan Kuchen
- Genomics & Immunity, Laboratory of Molecular Immunogenetics, National Institute of Arthritis, Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Ronald N. Germain
- Lymphocyte Biology Section, Laboratory of Systems Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
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105
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Longo DM, Selimkhanov J, Kearns JD, Hasty J, Hoffmann A, Tsimring LS. Dual delayed feedback provides sensitivity and robustness to the NF-κB signaling module. PLoS Comput Biol 2013; 9:e1003112. [PMID: 23825938 PMCID: PMC3694842 DOI: 10.1371/journal.pcbi.1003112] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 04/26/2013] [Indexed: 01/22/2023] Open
Abstract
Many cellular stress-responsive signaling systems exhibit highly dynamic behavior with oscillatory features mediated by delayed negative feedback loops. What remains unclear is whether oscillatory behavior is the basis for a signaling code based on frequency modulation (FM) or whether the negative feedback control modules have evolved to fulfill other functional requirements. Here, we use experimentally calibrated computational models to interrogate the negative feedback loops that regulate the dynamic activity of the transcription factor NF-κB. Linear stability analysis of the model shows that oscillatory frequency is a hard-wired feature of the primary negative feedback loop and not a function of the stimulus, thus arguing against an FM signaling code. Instead, our modeling studies suggest that the two feedback loops may be tuned to provide for rapid activation and inactivation capabilities for transient input signals of a wide range of durations; by minimizing late phase oscillations response durations may be fine-tuned in a graded rather than quantized manner. Further, in the presence of molecular noise the dual delayed negative feedback system minimizes stochastic excursions of the output to produce a robust NF-κB response.
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Affiliation(s)
- Diane M. Longo
- Department of Bioengineering, University of California San Diego, La Jolla, California, United States of America
| | - Jangir Selimkhanov
- Department of Bioengineering, University of California San Diego, La Jolla, California, United States of America
- San Diego Center for Systems Biology, La Jolla, California, United States of America
| | - Jeffrey D. Kearns
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, United States of America
| | - Jeff Hasty
- Department of Bioengineering, University of California San Diego, La Jolla, California, United States of America
- San Diego Center for Systems Biology, La Jolla, California, United States of America
- Molecular Biology Section, Division of Biological Sciences, University of California San Diego, La Jolla, California, United States of America
- BioCircuits Institute, University of California San Diego, La Jolla, California, United States of America
| | - Alexander Hoffmann
- San Diego Center for Systems Biology, La Jolla, California, United States of America
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, United States of America
- BioCircuits Institute, University of California San Diego, La Jolla, California, United States of America
- * E-mail: (AH); (LST)
| | - Lev S. Tsimring
- San Diego Center for Systems Biology, La Jolla, California, United States of America
- BioCircuits Institute, University of California San Diego, La Jolla, California, United States of America
- * E-mail: (AH); (LST)
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106
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Encoding and decoding cellular information through signaling dynamics. Cell 2013; 152:945-56. [PMID: 23452846 DOI: 10.1016/j.cell.2013.02.005] [Citation(s) in RCA: 528] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Revised: 12/08/2012] [Accepted: 02/06/2013] [Indexed: 11/23/2022]
Abstract
A growing number of studies are revealing that cells can send and receive information by controlling the temporal behavior (dynamics) of their signaling molecules. In this Review, we discuss what is known about the dynamics of various signaling networks and their role in controlling cellular responses. We identify general principles that are emerging in the field, focusing specifically on how the identity and quantity of a stimulus is encoded in temporal patterns, how signaling dynamics influence cellular outcomes, and how specific dynamical patterns are both shaped and interpreted by the structure of molecular networks. We conclude by discussing potential functional roles for transmitting cellular information through the dynamics of signaling molecules and possible applications for the treatment of disease.
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107
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Komura T, Sakai Y, Honda M, Takamura T, Wada T, Kaneko S. ER stress induced impaired TLR signaling and macrophage differentiation of human monocytes. Cell Immunol 2013; 282:44-52. [PMID: 23665674 DOI: 10.1016/j.cellimm.2013.04.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Revised: 02/13/2013] [Accepted: 04/14/2013] [Indexed: 11/16/2022]
Abstract
Endoplasmic reticulum (ER) stress causes impairment of the intracellular protein synthesis machinery, affecting various organ functions and homeostasis systems, including immunity. We found that ER stress induced by the N-linked glycosylation inhibitor, tunicamycin, caused susceptibility to apoptosis in the human monocytic cell line, THP-1 cells. Importantly, prior to tunicamycin-induced apoptosis, the proinflammatory response to toll-like receptor (TLR) 4 ligand lipopolysaccharide (LPS) stimulation was attenuated with respect to the expression of the proinflammatory cytokines. This impaired expression of proinflammatory cytokines was a consequence of the inhibition of NF-κB activation. Moreover, tunicamycin-induced ER stress disturbed the differentiation of THP-1 cells into macrophages induced by phorbol-12-myristate-13-acetate treatment. We also confirmed that ER stress affected the response of primary human monocytes to TLR ligand and their ability to differentiate into macrophages. These data suggest that ER stress imposes an important pathological insult to the immune system, affecting the crucial functions of monocytes.
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Affiliation(s)
- Takuya Komura
- Disease Control and Homeostasis, Kanazawa University, 13-1, Takaramachi, Kanazawa 920-8641, Japan
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108
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Dimerization and ubiquitin mediated recruitment of A20, a complex deubiquitinating enzyme. Immunity 2013; 38:896-905. [PMID: 23602765 DOI: 10.1016/j.immuni.2013.03.008] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 03/27/2013] [Indexed: 01/10/2023]
Abstract
A20 is an anti-inflammatory protein linked to multiple human autoimmune diseases and lymphomas. A20 possesses a deubiquitinating motif and a zinc finger, ZF4, that binds ubiquitin and supports its E3 ubiquitin ligase activity. To understand how these activities mediate A20's physiological functions, we generated two lines of gene-targeted mice, abrogating either A20's deubiquitinating activity (Tnfaip3(OTU) mice) or A20's ZF4 (Tnfaip3(ZF4) mice). Both Tnfaip3(OTU) and Tnfaip3(ZF4) mice exhibited increased responses to TNF and sensitivity to colitis. A20's C103 deubiquitinating motif restricted both K48- and K63-linked ubiquitination of receptor interacting protein 1 (RIP1). A20's ZF4 was required for recruiting A20 to ubiquitinated RIP1. A20(OTU) proteins and A20(ZF4) proteins complemented each other to regulate RIP1 ubiquitination and NFκB signaling normally in compound mutant Tnfaip3(OTU/ZF4) cells. This complementation involved homodimerization of A20 proteins, and we have defined an extensive dimerization interface in A20. These studies reveal how A20 proteins collaborate to restrict TNF signaling.
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109
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Tomosada Y, Villena J, Murata K, Chiba E, Shimazu T, Aso H, Iwabuchi N, Xiao JZ, Saito T, Kitazawa H. Immunoregulatory effect of bifidobacteria strains in porcine intestinal epithelial cells through modulation of ubiquitin-editing enzyme A20 expression. PLoS One 2013; 8:e59259. [PMID: 23555642 PMCID: PMC3608626 DOI: 10.1371/journal.pone.0059259] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Accepted: 02/13/2013] [Indexed: 12/20/2022] Open
Abstract
Background We previously showed that evaluation of anti-inflammatory activities of lactic acid bacteria in porcine intestinal epithelial (PIE) cells is useful for selecting potentially immunobiotic strains. Objective The aims of the present study were: i) to select potentially immunomodulatory bifidobacteria that beneficially modulate the Toll-like receptor (TLR)-4-triggered inflammatory response in PIE cells and; ii) to gain insight into the molecular mechanisms involved in the anti-inflammatory effect of immunobiotics by evaluating the role of TLR2 and TLR negative regulators in the modulation of proinflammatory cytokine production and activation of mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) pathways in PIE cells. Results Bifidobacteria longum BB536 and B. breve M-16V strains significantly downregulated levels of interleukin (IL)-8, monocyte chemotactic protein (MCP)-1 and IL-6 in PIE cells challenged with heat-killed enterotoxigenic Escherichia coli. Moreover, BB536 and M-16V strains attenuated the proinflammatory response by modulating the NF-κB and MAPK pathways. In addition, our findings provide evidence for a key role for the ubiquitin-editing enzyme A20 in the anti-inflammatory effect of immunobiotic bifidobacteria in PIE cells. Conclusions We show new data regarding the mechanism involved in the anti-inflammatory effect of immunobiotics. Several strains with immunoregulatory capabilities used a common mechanism to induce tolerance in PIE cells. Immunoregulatory strains interacted with TLR2, upregulated the expression of A20 in PIE cells, and beneficially modulated the subsequent TLR4 activation by reducing the activation of MAPK and NF-κB pathways and the production of proinflammatory cytokines. We also show that the combination of TLR2 activation and A20 induction can be used as biomarkers to screen and select potential immunoregulatory bifidobacteria strains.
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Affiliation(s)
- Yohsuke Tomosada
- Food and Feed Immunology Group, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Julio Villena
- Food and Feed Immunology Group, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
- Laboratory of Clinical and Experimental Biochemistry, Reference Centre for Lactobacilli (CERELA-CONICET), Tucuman, Argentina
| | - Kozue Murata
- Food and Feed Immunology Group, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Eriko Chiba
- Food and Feed Immunology Group, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Tomoyuki Shimazu
- Laboratory of Animal Breeding and Genetics, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Hisashi Aso
- Cell Biology Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Noriyuki Iwabuchi
- Food Science and Technology Institute, Morinaga Milk Industry Co. Ltd, Zama, Kanagawa, Japan
| | - Jin-zhong Xiao
- Food Science and Technology Institute, Morinaga Milk Industry Co. Ltd, Zama, Kanagawa, Japan
| | - Tadao Saito
- Food and Feed Immunology Group, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Haruki Kitazawa
- Food and Feed Immunology Group, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
- * E-mail:
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110
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Ross CL, Harrison BS. Effect of pulsed electromagnetic field on inflammatory pathway markers in RAW 264.7 murine macrophages. J Inflamm Res 2013; 6:45-51. [PMID: 23576877 PMCID: PMC3617815 DOI: 10.2147/jir.s40269] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
In the treatment of bacterial infections, antibiotics have proven to be very effective, but the way in which antibiotics are dosed can create a lag time between the administration of the drug and its absorption at the site of insult. The time it takes an antibiotic to reach therapeutic levels can often be significantly increased if the vascular system is compromized. Bacteria can multiply pending the delivery of the drug, therefore, developing treatments that can inhibit the inflammatory response while waiting for antibiotics to take effect could help prevent medical conditions such as septic shock. The aim of this study was to examine the effect of a pulsed electromagnetic field on the production of inflammatory markers tumor necrosis factor (TNF), transcription factor nuclear factor kappa B (NFkB), and the expression of the A20 (tumor necrosis factor-alpha-induced protein 3), in an inflamed-cell model. Lipopolysaccharide-challenged cells were exposed to a pulsed electromagnetic field at various frequencies in order to determine which, if any, frequency would affect the TNF-NFkB-A20 inflammatory response pathway. Our study revealed that cells continuously exposed to a pulsed electromagnetic field at 5 Hz demonstrated significant changes in the downregulation of TNF-α and NFkB and also showed a trend in the down regulation of A20, as compared with controls. This treatment could be beneficial in modulating the immune response, in the presence of infection.
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Affiliation(s)
- Christina L Ross
- Akamai University, Department of Energy Medicine, Hilo, HI, USA ; Wake Forest Institute for Regenerative Medicine, Wake Forest Baptist Health, Winston-Salem, NC, USA
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111
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Zanella F, Dos Santos NR, Link W. Moving to the core: spatiotemporal analysis of Forkhead box O (FOXO) and nuclear factor-κB (NF-κB) nuclear translocation. Traffic 2013; 14:247-58. [PMID: 23231504 DOI: 10.1111/tra.12034] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Revised: 12/06/2012] [Accepted: 12/10/2012] [Indexed: 12/23/2022]
Abstract
Nuclear translocation of proteins is an essential aspect of normal cell function, and defects in this process have been detected in many disease-associated conditions. The detection and quantification of nuclear translocation was significantly boosted by the association of robotized microscopy with automated image analysis, a technology designated as high-content screening. Image-based high-content screening and analysis provides the means to systematically observe cellular translocation events in time and space in response to chemical or genetic perturbation at large scale. This approach yields powerful insights into the regulation of complex signaling networks independently of preconceived notions of mechanistic relationships. In this review, we briefly overview the different mechanisms involved in nucleocytoplasmic protein trafficking. In addition, we discuss high-content approaches used to interrogate the mechanistic and spatiotemporal dynamics of cellular signaling events using Forkhead box O (FOXO) proteins and the nuclear factor-κB (NF-κB) as important and clinically relevant examples.
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Affiliation(s)
- Fabian Zanella
- School of Medicine, Cardiology Division, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0613, USA
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112
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Pinna F, Sahle S, Beuke K, Bissinger M, Tuncay S, D'Alessandro LA, Gauges R, Raue A, Timmer J, Klingmüller U, Schirmacher P, Kummer U, Breuhahn K. A Systems Biology Study on NFκB Signaling in Primary Mouse Hepatocytes. Front Physiol 2012; 3:466. [PMID: 23293603 PMCID: PMC3533138 DOI: 10.3389/fphys.2012.00466] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2012] [Accepted: 11/26/2012] [Indexed: 12/14/2022] Open
Abstract
The cytokine tumor necrosis factor-alpha (TNFα) is one of the key factors during the priming phase of liver regeneration as well as in hepatocarcinogenesis. TNFα activates the nuclear factor κ-light-chain-enhancer of activated B cells (NFκB) signaling pathway and contributes to the conversion of quiescent hepatocytes to activated hepatocytes that are able to proliferate in response to growth factor stimulation. Different mathematical models have been previously established for TNFα/NFκB signaling in the context of tumor cells. Combining these mathematical models with time-resolved measurements of expression and phosphorylation of TNFα/NFκB pathway constituents in primary mouse hepatocytes revealed that an additional phosphorylation step of the NFκB isoform p65 has to be considered in the mathematical model in order to sufficiently describe the dynamics of pathway activation in the primary cells. Also, we addressed the role of basal protein turnover by experimentally measuring the degradation rate of pivotal players in the absence of TNFα and including this information in the model. To elucidate the impact of variations in the protein degradation rates on TNFα/NFκB signaling on the overall dynamic behavior we used global sensitivity analysis that accounts for parameter uncertainties and showed that degradation and translation of p65 had a major impact on the amplitude and the integral of p65 phosphorylation. Finally, our mathematical model of TNFα/NFκB signaling was able to predict the time-course of the complex formation of p65 and of the inhibitor of NFκB (IκB) in primary mouse hepatocytes, which was experimentally verified. Hence, we here present a mathematical model for TNFα/NFκB signaling in primary mouse hepatocytes that provides an important basis to quantitatively disentangle the complex interplay of multiple factors in liver regeneration and tumorigenesis.
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Affiliation(s)
- Federico Pinna
- Institute of Pathology, University Hospital of Heidelberg Heidelberg, Germany
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113
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McAllister CS, Taghavi N, Samuel CE. Protein kinase PKR amplification of interferon β induction occurs through initiation factor eIF-2α-mediated translational control. J Biol Chem 2012; 287:36384-92. [PMID: 22948139 PMCID: PMC3476304 DOI: 10.1074/jbc.m112.390039] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 08/31/2012] [Indexed: 12/24/2022] Open
Abstract
The protein kinase PKR is activated by RNA with double-stranded (ds) structure and subsequently impairs translation through phosphorylation of protein synthesis initiation factor eIF-2α. PKR also mediates activation of signal transduction pathways leading to interferon beta (IFN-β) gene induction following virus-infection or RNA transfection. We previously demonstrated in measles virus-infected cells that PKR is required for the maximal induction of IFN-β gene expression by the interferon promoter stimulator gene 1 (IPS-1) adaptor-dependent cytosolic RNA sensor pathway. While both IPS-1 and PKR are important mediators of IFN-β induction, with PKR contributing to an enhanced NF-κB activation, the mechanism by which PKR enhances NF-κB activity and amplifies IFN-β induction is unresolved. Herein we tested the possibility that PKR could activate signal transduction pathways indirectly through translational control responses. Following transfection with synthetic or natural dsRNAs or infection with measles virus, we observed increased mRNA but decreased protein levels for the inhibitor of NF-κB signaling, IκB-α, that correlated with PKR activation and eIF-2α phosphorylation. Importantly, knockdown of PKR increased IκB-α protein levels and impaired IFN-β induction. Additionally, inhibition of translation by cycloheximide treatment rescued IFN-β induction following PKR knockdown but not IPS-1 knockdown. Mutation of eIF-2α to prevent phosphorylation also impaired IFN-β induction in PKR-sufficient virus-infected cells. These results suggest that an eIF-2α-dependent translation inhibition mechanism is sufficient to explain the PKR-mediated amplification of IPS-1-dependent IFN-β induction by foreign RNA.
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Affiliation(s)
- Christopher S. McAllister
- From the Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California 93106
| | - Nora Taghavi
- From the Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California 93106
| | - Charles E. Samuel
- From the Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California 93106
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114
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Günel A. Modelling the interactions between TLR4 and IFNβ pathways. J Theor Biol 2012; 307:137-48. [PMID: 22575970 DOI: 10.1016/j.jtbi.2012.04.026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Revised: 04/17/2012] [Accepted: 04/18/2012] [Indexed: 02/06/2023]
Abstract
Bacterial lipopolysaccharide (LPS) association with their connate receptor TLR4 triggers Type I interferon signaling cascade through its MyD88 independent downstream. Compared to plethora of reported empirical data on both TLR4 and Type I interferon pathways, there is no known model to decipher crosstalk mechanisms between these two crucial innate immune pathogen activated pathways regulating vital transcriptional factors such as nuclear factor-κB (NFκB), IFNβ, the interferon-stimulated gene factor-3 (ISGF3) and an important cancer drug target protein kinase-R (PKR). Innate immune system is based on a sensitive balance of intricate interactions. In elucidating these interactions, in silico integration of pathways has great potential. Attempts confined to single pathway may not be effective in truly addressing source of real systems behavior. This is the first report combining toll-like receptor-4 (TLR4) and interferon beta (IFNβ) pathways in a single in silico model, analyzing their interactions, pinpointing the source of delay in PKR late phase activity and limiting the transcription of IFN and PKR by using a method including an statistical physics technique in reaction equations. The model quite successfully recapitulates published interferon regulatory factor-3 (IRF3) and IFNβ data from mouse macrophages and PKR data from mouse embryonic fibroblast cell lines. The simulations end up with an estimate of IRF3, IFNβ, ISGF3 dose dependent profiles mimicking nonlinear dose response characteristic of the system. Involvement of concomitant PKR downstream can unravel elusive mechanisms in specific profiles like NFκB regulation.
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Affiliation(s)
- Aylin Günel
- Istanbul Technical University Informatics Institute, Maslak, 34469, Istanbul, Turkiye.
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115
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Yang L, Boldin MP, Yu Y, Liu CS, Ea CK, Ramakrishnan P, Taganov KD, Zhao JL, Baltimore D. miR-146a controls the resolution of T cell responses in mice. ACTA ACUST UNITED AC 2012; 209:1655-70. [PMID: 22891274 PMCID: PMC3428948 DOI: 10.1084/jem.20112218] [Citation(s) in RCA: 230] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
By suppressing expression of TRAF6 and IRAK1, miR-146a regulates NF-κB activation in T cells through a negative feedback loop and controls the resolution of T cell responses in mice. T cell responses in mammals must be tightly regulated to both provide effective immune protection and avoid inflammation-induced pathology. NF-κB activation is a key signaling event induced by T cell receptor (TCR) stimulation. Dysregulation of NF-κB is associated with T cell–mediated inflammatory diseases and malignancies, highlighting the importance of negative feedback control of TCR-induced NF-κB activity. In this study we show that in mice, T cells lacking miR-146a are hyperactive in both acute antigenic responses and chronic inflammatory autoimmune responses. TCR-driven NF-κB activation up-regulates the expression of miR-146a, which in turn down-regulates NF-κB activity, at least partly through repressing the NF-κB signaling transducers TRAF6 and IRAK1. Thus, our results identify miR-146a as an important new member of the negative feedback loop that controls TCR signaling to NF-κB. Our findings also add microRNA to the list of regulators that control the resolution of T cell responses.
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Affiliation(s)
- Lili Yang
- Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA.
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116
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Moss BL, Elhammali A, Fowlkes T, Gross S, Vinjamoori A, Contag CH, Piwnica-Worms D. Interrogation of inhibitor of nuclear factor κB α/nuclear factor κB (IκBα/NF-κB) negative feedback loop dynamics: from single cells to live animals in vivo. J Biol Chem 2012; 287:31359-70. [PMID: 22807442 DOI: 10.1074/jbc.m112.364018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Full understanding of the biological significance of negative feedback processes requires interrogation at multiple scales as follows: in single cells, cell populations, and live animals in vivo. The transcriptionally coupled IκBα/NF-κB negative feedback loop, a pivotal regulatory node of innate immunity and inflammation, represents a model system for multiscalar reporters. Using a κB(5)→IκBα-FLuc bioluminescent reporter, we rigorously evaluated the dynamics of ΙκBα degradation and subsequent NF-κB transcriptional activity in response to diverse modes of TNFα stimulation. Modulating TNFα concentration or pulse duration yielded complex, reproducible, and differential ΙκBα dynamics in both cell populations and live single cells. Tremendous heterogeneity in the transcriptional amplitudes of individual responding cells was observed, which was greater than the heterogeneity in the transcriptional kinetics of responsive cells. Furthermore, administration of various TNFα doses in vivo generated ΙκBα dynamic profiles in the liver resembling those observed in single cells and populations of cells stimulated with TNFα pulses. This suggested that dose modulation of circulating TNFα was perceived by hepatocytes in vivo as pulses of increasing duration. Thus, a robust bioluminescent reporter strategy enabled rigorous quantitation of NF-κB/ΙκBα dynamics in both live single cells and cell populations and furthermore, revealed reproducible behaviors that informed interpretation of in vivo studies.
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Affiliation(s)
- Britney L Moss
- Molecular Imaging Center, Mallinckrodt Institute of Radiology, Department of Cell Biology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Abstract
Mathematical modeling has proved to be a critically important approach in the study of many complex networks and dynamic systems in physics, engineering, chemistry, and biology. The nuclear factor κB (NF-κB) system consists of more than 50 proteins and protein complexes and is both a highly networked and dynamic system. To date, mathematical modeling has only addressed a small fraction of the molecular species and their regulation, but when employed in conjunction with experimental analysis has already led to important insights. Here, we provide a personal account of studying how the NF-κB signaling system functions using mathematical descriptions of the molecular mechanisms. We focus on the insights gained about some of the key regulatory components: the control of the steady state, the signaling dynamics, and signaling crosstalk. We also discuss the biological relevance of these regulatory systems properties.
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Affiliation(s)
- Soumen Basak
- Systems Immunology Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, India
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118
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MAXWELL JAMESR, MARINOU IOANNA, KUET KARPING, OROZCO GISELA, MOORE DAVIDJ, BARTON ANNE, WORTHINGTON JANE, WILSON AGERRY. Rheumatoid Arthritis-associated Polymorphisms at 6q23 Are Associated with Radiological Damage in Autoantibody-positive RA. J Rheumatol 2012; 39:1781-5. [DOI: 10.3899/jrheum.120144] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Objective.Recent studies have identified 6q23 as an important susceptibility locus for rheumatoid arthritis (RA), with risk alleles at 3 single-nucleotide polymorphisms combining to give an effect size greater than that of these markers individually. We investigated whether these polymorphisms are also associated with disease severity measured by radiological damage.Methods.We studied 927 patients from a cross-sectional RA cohort. Median Larsen scores (LS) read from radiographs taken at study entry were compared by genotype at rs6920220, rs13207033, and rs5029937 according to a dominant model using negative binomial regression with stratification for autoantibody status.Results.Median LS was associated with genotype at rs6920220 [LS 31 GG vs 36 GA/AA (p = 0.02) in cyclic citrullinated peptide+ (CCP) RA] and rs13020220 [LS 37 GG vs 29 GA/AA (p = 0.02) in CCP+ RA] only in autoantibody-positive RA, with no association at rs5029937. Association was stronger for these markers in combination [LS 28 vs 42 for lowest vs highest risk genotype combination in rheumatoid factor positivity (p = 0.007), LS 28 vs 37 for anti-CCP+ (p = 0.01)].Conclusion.Established RA risk markers at 6q23 are associated also with radiographic severity in autoantibody-positive RA; as for susceptibility, the association for these markers in combination is stronger than that for markers alone.
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119
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Miani M, Colli ML, Ladrière L, Cnop M, Eizirik DL. Mild endoplasmic reticulum stress augments the proinflammatory effect of IL-1β in pancreatic rat β-cells via the IRE1α/XBP1s pathway. Endocrinology 2012; 153:3017-28. [PMID: 22529213 DOI: 10.1210/en.2011-2090] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The prevalence of obesity and type 1 diabetes in children is increasing worldwide. Insulin resistance and augmented circulating free fatty acids associated with obesity may cause pancreatic β-cell endoplasmic reticulum (ER) stress. We tested the hypothesis that mild ER stress predisposes β-cells to an exacerbated inflammatory response when exposed to IL-1β or TNF-α, cytokines that contribute to the pathogenesis of type 1 diabetes. INS-1E cells or primary rat β-cells were exposed to a low dose of the ER stressor cyclopiazonic acid (CPA) or free fatty acids, followed by low-dose IL-1β or TNF-α. ER stress signaling was inhibited by small interfering RNA. Cells were evaluated for proinflammatory gene expression by RT-PCR and ELISA, gene reporter activity, p65 activation by immunofluorescence, and apoptosis. CPA pretreatment enhanced IL-1β- induced, but not TNF-α-induced, expression of chemokine (C-C motif) ligand 2, chemokine (C-X-C motif) ligand 1, inducible nitric oxide synthase, and Fas via augmented nuclear factor κB (NF-κB) activation. X-box binding protein 1 (XBP1) and inositol-requiring enzyme 1, but not CCAAT/enhancer binding protein homologous protein, knockdown prevented the CPA-induced exacerbation of NF-κB-dependent genes and decreased IL-1β-induced NF-κB promoter activity. XBP1 modulated NF-κB activity via forkhead box O1 inhibition. In conclusion, rat β-cells facing mild ER stress are sensitized to IL-1β, generating a more intense and protracted inflammatory response through inositol-requiring enzyme 1/XBP1 activation. These observations link β-cell ER stress to the triggering of exacerbated local inflammation.
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Affiliation(s)
- Michela Miani
- Laboratory of Experimental Medicine, Erasmus Hospital, Université Libre de Bruxelles, B-1070 Brussels, Belgium
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120
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Liu Y, Bridges R, Wortham A, Kulesz-Martin M. NF-κB repression by PIAS3 mediated RelA SUMOylation. PLoS One 2012; 7:e37636. [PMID: 22649547 PMCID: PMC3359287 DOI: 10.1371/journal.pone.0037636] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Accepted: 04/26/2012] [Indexed: 01/21/2023] Open
Abstract
Negative regulation of the NF-κB transcription factor is essential for tissue homeostasis in response to stress and inflammation. NF-κB activity is regulated by a variety of biochemical mechanisms including phosphorylation, acetylation, and ubiquitination. In this study, we provide the first experimental evidence that NF-κB is regulated by SUMOylation, where the RelA subunit of NF-κB is SUMOylated by PIAS3, a member of the PIAS (protein inhibitor of activated STAT) protein family with E3 SUMO ligase activity. PIAS3-mediated NF-κB repression was compromised by either RelA mutant resistant to SUMOylation or PIAS3 mutant defective in SUMOylation. PIAS3-mediated SUMOylation of endogenous RelA was induced by NF-κB activation thus forming a negative regulatory loop. The SUMOylation of endogenous RelA was enhanced in IκBα null as compared with wild type fibroblasts. The RelA SUMOylation was induced by TNFα but not leptomycin B mediated RelA nuclear translocation. Furthermore, RelA mutants defective in DNA binding were not SUMOylated by PIAS3, suggesting that RelA DNA binding is a signal for PIAS3-mediated SUMOylation. These results support a novel negative feedback mechanism for NF-κB regulation by PIAS3-mediated RelA SUMOylation.
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Affiliation(s)
- Yuangang Liu
- Department of Dermatology, Oregon Health and Science University, Portland, Oregon, United States of America
- * E-mail: (YL); (MKM)
| | - Rebecca Bridges
- Department of Dermatology, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Aaron Wortham
- Department of Dermatology, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Molly Kulesz-Martin
- Department of Dermatology, Oregon Health and Science University, Portland, Oregon, United States of America
- * E-mail: (YL); (MKM)
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121
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Maxwell JR, Gowers IR, Kuet KP, Barton A, Worthington J, Wilson AG. Expression of the autoimmunity associated TNFAIP3 is increased in rheumatoid arthritis but does not differ according to genotype at 6q23. Rheumatology (Oxford) 2012; 51:1514-5. [PMID: 22623711 DOI: 10.1093/rheumatology/kes134] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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122
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Immunobiotic Lactobacillus jensenii modulates the Toll-like receptor 4-induced inflammatory response via negative regulation in porcine antigen-presenting cells. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2012; 19:1038-53. [PMID: 22573738 DOI: 10.1128/cvi.00199-12] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Previously, we demonstrated that Lactobacillus jensenii TL2937 attenuates the inflammatory response triggered by activation of Toll-like receptor 4 (TLR-4) in porcine intestinal epithelial cells. In view of the critical importance of antigen-presenting cell (APC) polarization in immunoregulation, the objective of the present study was to examine the effect of strain TL2937 on the activation patterns of APCs from swine Peyer's patches (PPs). We demonstrated that direct exposure of porcine APCs to L. jensenii in the absence of inflammatory signals increased expression of interleukin-10 (IL-10) and transforming growth factor β in CD172a(+) APCs and caused them to display tolerogenic properties. In addition, pretreatment of CD172a(+) APCs with L. jensenii resulted in differential modulation of the production of pro- and anti-inflammatory cytokines in response to TLR4 activation. The immunomodulatory effect of strain TL2937 was not related to a downregulation of TLR4 but was related to an upregulation of the expression of three negative regulators of TLRs: single immunoglobulin IL-1-related receptor (SIGIRR), A20, and interleukin-1 receptor-associated kinase M (IRAK-M). Our results also indicated that TLR2 has an important role in the anti-inflammatory activity of L. jensenii TL2937, since anti-TLR2 antibodies blocked the upregulation of SIGIRR and IRAK-M in CD172a(+) APCs and the production of IL-10 in response to TLR4 activation. We performed, for the first time, a precise functional characterization of porcine APCs from PPs, and we demonstrated that CD172a(+) cells were tolerogenic. Our findings demonstrate that adherent cells and isolated CD172a(+) cells harvested from swine PPs were useful for in vitro study of the inflammatory responses in the porcine gut and the immunomodulatory effects of immunobiotic microorganisms.
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123
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Jensen MH, Krishna S. Inducing phase-locking and chaos in cellular oscillators by modulating the driving stimuli. FEBS Lett 2012; 586:1664-8. [DOI: 10.1016/j.febslet.2012.04.044] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 04/23/2012] [Accepted: 04/23/2012] [Indexed: 01/18/2023]
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124
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Narang V, Decraene J, Wong SY, Aiswarya BS, Wasem AR, Leong SR, Gouaillard A. Systems immunology: a survey of modeling formalisms, applications and simulation tools. Immunol Res 2012; 53:251-65. [PMID: 22528121 DOI: 10.1007/s12026-012-8305-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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125
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Effects of IRF5 lupus risk haplotype on pathways predicted to influence B cell functions. J Biomed Biotechnol 2012; 2012:594056. [PMID: 22500098 PMCID: PMC3304673 DOI: 10.1155/2012/594056] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Revised: 11/04/2011] [Accepted: 11/05/2011] [Indexed: 01/18/2023] Open
Abstract
Both genetic and environmental interactions affect systemic lupus erythematosus (SLE) development and pathogenesis. One known genetic factor associated with lupus is a haplotype of the interferon regulatory factor 5 (IRF5) gene. Analysis of global gene expression microarray data using gene set enrichment analysis identified multiple interferon- and inflammation-related gene sets significantly overrepresented in cells with the risk haplotype. Pathway analysis using expressed genes from the significant gene sets impacted by the IRF5 risk haplotype confirmed significant correlation with the interferon pathway, Toll-like receptor pathway, and the B-cell receptor pathway. SLE patients with the IRF5 risk haplotype have a heightened interferon signature, even in an unstimulated state (P = 0.011), while patients with the IRF5 protective haplotype have a B cell interferon signature similar to that of controls. These results identify multiple genes in functionally significant pathways which are affected by IRF5 genotype. They also establish the IRF5 risk haplotype as a key determinant of not only the interferon response, but also other B-cell pathways involved in SLE.
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126
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Funk SD, Yurdagul A, Albert P, Traylor JG, Jin L, Chen J, Orr AW. EphA2 activation promotes the endothelial cell inflammatory response: a potential role in atherosclerosis. Arterioscler Thromb Vasc Biol 2012; 32:686-95. [PMID: 22247258 DOI: 10.1161/atvbaha.111.242792] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVE Endothelial cell activation results in altered cell-cell interactions with adjacent endothelial cells and with infiltrating leukocytes. Eph receptors and their ephrin ligands regulate cell-cell interactions during tissue remodeling, and multiple proinflammatory mediators induce endothelial EphA receptor and ephrinA ligand expression. Therefore, we sought to elucidate the role of EphA receptors and ephrinA ligands in endothelial cell activation and atherosclerosis. METHODS AND RESULTS Quantitative reverse transcription-polymerase chain reaction screening for EphA/ephrinA expression in atherosclerosis-prone macrovascular endothelium identified EphA2, EphA4, and ephrinA1 as the dominant isoforms. Endothelial activation with oxidized low-density lipoprotein and proinflammatory cytokines induced EphA2 and ephrinA1 expression and sustained EphA2 activation, whereas EphA4 expression was unaffected. Atherosclerotic plaques from mice and humans showed enhanced EphA2 and ephrinA1 expression colocalizing in the endothelial cell layer. EphA2 activation with recombinant Fc-ephrinA1 induced proinflammatory gene expression (eg vascular cell adhesion molecule-1, E-selectin) and stimulated monocyte adhesion, whereas inhibiting EphA2 (small interfering RNA, pharmacological inhibitors) abrogated both ephrinA1-induced and oxidized low-density lipoprotein-induced vascular cell adhesion molecule-1 expression. CONCLUSION The current data suggest that enhanced EphA2 signaling during endothelial cell activation perpetuates proinflammatory gene expression. Coupled with EphA2 expression in mouse and human atherosclerotic plaques, these data implicate EphA2 as a novel proinflammatory mediator and potential regulator of atherosclerotic plaque development.
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Affiliation(s)
- Steven Daniel Funk
- Department of Pathology, Louisiana State University Health Science Center, 1501 King's Hwy, Shreveport, LA 71130, USA
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127
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Gurevich I, Zhang C, Encarnacao PC, Struzynski CP, Livings SE, Aneskievich BJ. PPARγ and NF-κB regulate the gene promoter activity of their shared repressor, TNIP1. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1819:1-15. [PMID: 22001530 PMCID: PMC3249470 DOI: 10.1016/j.bbagrm.2011.09.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Revised: 09/27/2011] [Accepted: 09/30/2011] [Indexed: 11/27/2022]
Abstract
Human TNFAIP3 interacting protein 1 (TNIP1) has diverse functions including support of HIV replication through its interaction with viral Nef and matrix proteins, reduction of TNFα-induced signaling through its interaction with NF-κB pathway proteins, and corepression of agonist-bound retinoic acid receptors and peroxisome proliferator-activated receptors (PPAR). The wide tissue distribution of TNIP1 provides the opportunity to influence numerous cellular responses in these roles and defining control of TNIP1 expression would be central to improved understanding of its impact on cell function. We cloned 6kb of the human TNIP1 promoter and performed predictive and functional analyses to identify regulatory elements. The promoter region proximal to the transcription start site is GC-rich without a recognizable TATA box. In contrast to this proximal ~500bp region, 6kb of the promoter increased reporter construct constitutive activity over five-fold. Throughout the 6kb length, in silico analysis identified several potential binding sites for both constitutive and inducible transcription factors; among the latter were candidate NF-κB binding sequences and peroxisome proliferator response elements (PPREs). We tested NF-κB and PPAR regulation of the endogenous TNIP1 gene and cloned promoter by expression studies, electrophoretic mobility shift assays, and chromatin immunoprecipitations. We validated NF-κB sites in the TNIP1 promoter proximal and distal regions as well as one PPRE in the distal region. The ultimate control of the TNIP1 promoter is likely to be a combination of constitutive transcription factors and those subject to activation such as NF-κB and PPAR.
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Affiliation(s)
- Igor Gurevich
- Graduate Program in Pharmacology & Toxicology, University of Connecticut, Storrs, CT 06269-3092; USA
| | - Carmen Zhang
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT 06269-3092; USA
| | - Priscilla C. Encarnacao
- Graduate Program in Pharmacology & Toxicology, University of Connecticut, Storrs, CT 06269-3092; USA
| | - Charles P. Struzynski
- Doctor of Pharmacy Program, School of Pharmacy, University of Connecticut, Storrs, CT 06269-3092; USA
| | - Sarah E. Livings
- Doctor of Pharmacy Program, School of Pharmacy, University of Connecticut, Storrs, CT 06269-3092; USA
| | - Brian J. Aneskievich
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT 06269-3092; USA
- Center for Regenerative Biology, University of Connecticut, Storrs, CT 06269-3092; USA
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128
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Fiume G, Vecchio E, De Laurentiis A, Trimboli F, Palmieri C, Pisano A, Falcone C, Pontoriero M, Rossi A, Scialdone A, Fasanella Masci F, Scala G, Quinto I. Human immunodeficiency virus-1 Tat activates NF-κB via physical interaction with IκB-α and p65. Nucleic Acids Res 2011; 40:3548-62. [PMID: 22187158 PMCID: PMC3333881 DOI: 10.1093/nar/gkr1224] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Nuclear factor (NF)-κB is a master regulator of pro-inflammatory genes and is upregulated in human immunodeficiency virus 1 (HIV-1) infection. Mechanisms underlying the NF-κB deregulation by HIV-1 are relevant for immune dysfunction in AIDS. We report that in single round HIV-1 infection, or single-pulse PMA stimulation, the HIV-1 Tat transactivator activated NF-κB by hijacking the inhibitor IκB-α and by preventing the repressor binding to the NF-κB complex. Moreover, Tat associated with the p65 subunit of NF-κB and increased the p65 DNA-binding affinity and transcriptional activity. The arginine- and cysteine-rich domains of Tat were required for IκB-α and p65 association, respectively, and for sustaining the NF-κB activity. Among an array of NF-κB-responsive genes, Tat mostly activated the MIP-1α expression in a p65-dependent manner, and bound to the MIP-1α NF-κB enhancer thus promoting the recruitment of p65 with displacement of IκB-α; similar findings were obtained for the NF-κB-responsive genes CSF3, LTA, NFKBIA and TLR2. Our results support a novel mechanism of NF-κB activation via physical interaction of Tat with IκB-α and p65, and may contribute to further insights into the deregulation of the inflammatory response by HIV-1.
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Affiliation(s)
- Giuseppe Fiume
- Department of Experimental and Clinical Medicine, University of Catanzaro Magna Graecia, Viale Europa-Germaneto, 88100 Catanzaro, Italy
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129
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Mahul-Mellier AL, Pazarentzos E, Datler C, Iwasawa R, AbuAli G, Lin B, Grimm S. De-ubiquitinating protease USP2a targets RIP1 and TRAF2 to mediate cell death by TNF. Cell Death Differ 2011; 19:891-9. [PMID: 22179575 DOI: 10.1038/cdd.2011.185] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Components of the TNFR1 complex are subject to dynamic ubiquitination that impacts on their effects as signalling factors. We have found that the ubiquitin-specific protease USP2a has a pivotal role in the decision for cell death or survival by the TNFR1 complex. This enzyme is a novel component of the TNFR1 complex that is recruited upon ligand binding and controls the signalling activity of the TNFR1-interacting protein RIP1 by removing its K63-linked ubiquitin chains. USP2a similarly de-ubiquitinates TRAF2, a ubiquitin-ligase recruited to the TNFR1 complex. During the TNF response the activity of USP2a on RIP1 and TRAF2 is required for the efficient reappearance of IκBα, which is essential to inactivate the anti-apoptotic transcription factor NF-κB. The effects of USP2a culminate in the conversion of the anti-apoptotic TNFR1 complex I into the pro-apoptotic TNFR1 complex II. Consequently, downregulation of USP2a promotes NF-κB activation and protects cells against TNF-induced cell death.
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Affiliation(s)
- A-L Mahul-Mellier
- Imperial College London, Experimental Medicine and Toxicology, Hammersmith Campus, Du Cane Road, Burlington Danes Building, London W12 0NN, UK
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130
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Teraguchi S, Kumagai Y, Vandenbon A, Akira S, Standley DM. Stochastic binary modeling of cells in continuous time as an alternative to biochemical reaction equations. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:062903. [PMID: 22304139 DOI: 10.1103/physreve.84.062903] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Indexed: 05/31/2023]
Abstract
We have developed a coarse-grained formulation for modeling the dynamic behavior of cells quantitatively, based on stochasticity and heterogeneity, rather than on biochemical reactions. We treat each reaction as a continuous-time stochastic process, while reducing each biochemical quantity to a binary value at the level of individual cells. The system can be analytically represented by a finite set of ordinary linear differential equations, which provides a continuous time course prediction of each molecular state. Here we introduce our formalism and demonstrate it with several examples.
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Affiliation(s)
- Shunsuke Teraguchi
- Laboratory of Host Defense, WPI Immunology Frontier Research Center, IFReC, Osaka University, 3-1 Yamada-oka, Suita, Osaka 565-0871, Japan
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131
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Abstract
The tumor necrosis factor-alpha-induced protein 3 (TNFAIP3) gene has been associated with psoriasis, rheumatoid arthritis, type 1 diabetes mellitus, systemic lupus erythematosus, and celiac disease. TNFAIP3 encodes A20, a tumor necrosis factor (TNF)-α-inducible zinc finger protein thought to limit NF-κB-mediated immune responses. In this study, we report association of response of psoriasis to TNF blockers with two TNFAIP3 single-nucleotide polymorphisms (rs2230926 in exon 7 and rs610604 in intron 3) and their haplotypes. Treatment response was self-evaluated using a 0-5 visual analog scale in 433 psoriasis patients who received TNF blockers. Confirmation was sought in 199 psoriasis and psoriatic arthritis patients from Toronto who were followed up prospectively. Response variables were dichotomized separately in the two cohorts, yielding similar proportions of good responses. Whereas significant associations were observed only for the Michigan cohort, fixed-effects meta-analysis retained significant association between dosage of the G allele of rs610604 and good combined response to all TNF blockers (odds ratio (OR) = 1.50, P(corr) = 0.050) and etanercept (OR = 1.64, P(corr) = 0.016). The rs2230926 T-rs610604 G haplotype was similarly associated. By demonstrating an association with therapeutic response, these results provide a clinically relevant functional correlate to the recently described genetic association between psoriasis and TNFAIP3.
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132
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Immunobiotic Lactobacillus jensenii elicits anti-inflammatory activity in porcine intestinal epithelial cells by modulating negative regulators of the Toll-like receptor signaling pathway. Infect Immun 2011; 80:276-88. [PMID: 22083706 DOI: 10.1128/iai.05729-11] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The effect of Lactobacillus jensenii TL2937 on the inflammatory immune response triggered by enterotoxigenic Escherichia coli (ETEC) and lipopolysaccharide (LPS) in a porcine intestinal epitheliocyte cell line (PIE cells) was evaluated. Challenges with ETEC or LPS elicited Toll-like receptor 4 (TLR4)-mediated inflammatory responses in cultured PIE cells, indicating that our cell line may be useful for studying inflammation in the guts of weaning piglets. In addition, we demonstrated that L. jensenii TL2937 attenuated the expression of proinflammatory cytokines and chemokines caused by ETEC or LPS challenge by downregulating TLR4-dependent nuclear factorκB (NF-κB) and mitogen-activated protein kinase (MAPK) activation. Furthermore, we demonstrated that L. jensenii TL2937 stimulation of PIE cells upregulated three negative regulators of TLRs: A20, Bcl-3, and MKP-1, deepening the understanding of an immunobiotic mechanism of action. L. jensenii TL2937-mediated induction of negative regulators of TLRs would have a substantial physiological impact on homeostasis in PIE cells, because excessive TLR inflammatory signaling would be downregulated. These results indicated that PIE cells can be used to study the mechanisms involved in the protective activity of immunobiotics against intestinal inflammatory damage and may provide useful information for the development of new immunologically functional feeds that help to prevent inflammatory intestinal disorders, including weaning-associated intestinal inflammation.
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Hammer GE, Turer EE, Taylor KE, Fang CJ, Advincula R, Oshima S, Barrera J, Huang EJ, Hou B, Malynn BA, Reizis B, DeFranco A, Criswell LA, Nakamura MC, Ma A. Expression of A20 by dendritic cells preserves immune homeostasis and prevents colitis and spondyloarthritis. Nat Immunol 2011; 12:1184-93. [PMID: 22019834 PMCID: PMC3419270 DOI: 10.1038/ni.2135] [Citation(s) in RCA: 200] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Accepted: 09/07/2011] [Indexed: 02/08/2023]
Abstract
Dendritic cells (DCs), which are known to support immune activation during infection, may also regulate immune homeostasis in resting animals. Here we show that mice lacking the ubiquitin-editing molecule A20 specifically in DCs spontaneously showed DC activation and population expansion of activated T cells. Analysis of DC-specific epistasis in compound mice lacking both A20 and the signaling adaptor MyD88 specifically in DCs showed that A20 restricted both MyD88-independent signals, which drive activation of DCs and T cells, and MyD88-dependent signals, which drive population expansion of T cells. In addition, mice lacking A20 specifically in DCs spontaneously developed lymphocyte-dependent colitis, seronegative ankylosing arthritis and enthesitis, conditions stereotypical of human inflammatory bowel disease (IBD). Our findings indicate that DCs need A20 to preserve immune quiescence and suggest that A20-dependent DC functions may underlie IBD and IBD-associated arthritides.
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Affiliation(s)
- Gianna Elena Hammer
- Department of Medicine, University of California at San Francisco, San Francisco, California, USA
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134
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Cheong R, Rhee A, Wang CJ, Nemenman I, Levchenko A. Information transduction capacity of noisy biochemical signaling networks. Science 2011; 334:354-8. [PMID: 21921160 PMCID: PMC3895446 DOI: 10.1126/science.1204553] [Citation(s) in RCA: 331] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Molecular noise restricts the ability of an individual cell to resolve input signals of different strengths and gather information about the external environment. Transmitting information through complex signaling networks with redundancies can overcome this limitation. We developed an integrative theoretical and experimental framework, based on the formalism of information theory, to quantitatively predict and measure the amount of information transduced by molecular and cellular networks. Analyzing tumor necrosis factor (TNF) signaling revealed that individual TNF signaling pathways transduce information sufficient for accurate binary decisions, and an upstream bottleneck limits the information gained via multiple integrated pathways. Negative feedback to this bottleneck could both alleviate and enhance its limiting effect, despite decreasing noise. Bottlenecks likewise constrain information attained by networks signaling through multiple genes or cells.
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Affiliation(s)
- Raymond Cheong
- Department of Biomedical Engineering, Johns Hopkins University, 3400 N. Charles Street, Baltimore MD 21218, USA
| | - Alex Rhee
- Department of Biomedical Engineering, Johns Hopkins University, 3400 N. Charles Street, Baltimore MD 21218, USA
| | - Chiaochun Joanne Wang
- Department of Biomedical Engineering, Johns Hopkins University, 3400 N. Charles Street, Baltimore MD 21218, USA
| | - Ilya Nemenman
- Departments of Physics and Biology, Emory University, 400 Dowman Drive, Atlanta GA 30322, USA
| | - Andre Levchenko
- Department of Biomedical Engineering, Johns Hopkins University, 3400 N. Charles Street, Baltimore MD 21218, USA
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135
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Terry AJ, Chaplain MAJ. Spatio-temporal modelling of the NF-κB intracellular signalling pathway: the roles of diffusion, active transport, and cell geometry. J Theor Biol 2011; 290:7-26. [PMID: 21907212 DOI: 10.1016/j.jtbi.2011.08.036] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Revised: 07/01/2011] [Accepted: 08/27/2011] [Indexed: 11/26/2022]
Abstract
The nuclear factor kappa B (NF-κB) intracellular signalling pathway is central to many stressful, inflammatory, and innate immune responses. NF-κB proteins themselves are transcription factors for hundreds of genes. Experiments have shown that the NF-κB pathway can exhibit oscillatory dynamics-a negative feedback loop causes oscillatory nuclear-cytoplasmic translocation of NF-κB. Given that cell size and shape are known to influence intracellular signal transduction, we consider a spatio-temporal model of partial differential equations for the NF-κB pathway, where we model molecular movement by diffusion and, for several key species including NF-κB, by active transport as well. Through numerical simulations we find values for model parameters such that sustained oscillatory dynamics occur. Our spatial profiles and animations bear a striking resemblance to experimental images and movie clips employing fluorescent fusion proteins. We discover that oscillations in nuclear NF-κB may occur when active transport is across the nuclear membrane only, or when no species are subject to active transport. However, when active transport is across the nuclear membrane and NF-κB is additionally actively transported through the cytoplasm, oscillations are lost. Hence transport mechanisms in a cell will influence its response to activation of its NF-κB pathway. We also demonstrate that sustained oscillations in nuclear NF-κB are somewhat robust to changes in the shape of the cell, or the shape, location, and size of its nucleus, or the location of ribosomes. Yet if the cell is particularly flat or the nucleus sufficiently small, then oscillations are lost. Thus the geometry of a cell may partly determine its response to NF-κB activation. The NF-κB pathway is known to be constitutively active in several human cancers. Our spatially explicit modelling approach will allow us, in future work, to investigate targeted drug therapy of tumours.
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Affiliation(s)
- Alan J Terry
- Division of Mathematics, University of Dundee, Dundee, Scotland, UK.
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136
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Sheppard PW, Sun X, Emery JF, Giffard RG, Khammash M. Quantitative characterization and analysis of the dynamic NF-κB response in microglia. BMC Bioinformatics 2011; 12:276. [PMID: 21729324 PMCID: PMC3158563 DOI: 10.1186/1471-2105-12-276] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Accepted: 07/05/2011] [Indexed: 12/02/2022] Open
Abstract
Background Activation of the NF-κB transcription factor and its associated gene expression in microglia is a key component in the response to brain injury. Its activation is dynamic and is part of a network of biochemical species with multiple feedback regulatory mechanisms. Mathematical modeling, which has been instrumental for understanding the NF-κB response in other cell types, offers a valuable tool to investigate the regulation of NF-κB activation in microglia at a systems level. Results We quantify the dynamic response of NF-κB activation and activation of the upstream kinase IKK using ELISA measurements of a microglial cell line following treatment with the pro-inflammatory cytokine TNFα. A new mathematical model is developed based on these data sets using a modular procedure that exploits the feedback structure of the network. We show that the new model requires previously unmodeled dynamics involved in the stimulus-induced degradation of the inhibitor IκBα in order to properly describe microglial NF-κB activation in a statistically consistent manner. This suggests a more prominent role for the ubiquitin-proteasome system in regulating the activation of NF-κB to inflammatory stimuli. We also find that the introduction of nonlinearities in the kinetics of IKK activation and inactivation is essential for proper characterization of transient IKK activity and corresponds to known biological mechanisms. Numerical analyses of the model highlight key regulators of the microglial NF-κB response, as well as those governing IKK activation. Results illustrate the dynamic regulatory mechanisms and the robust yet fragile nature of the negative feedback regulated network. Conclusions We have developed a new mathematical model that incorporates previously unmodeled dynamics to characterize the dynamic response of the NF-κB signaling network in microglia. This model is the first of its kind for microglia and provides a tool for the quantitative, systems level study the dynamic cellular response to inflammatory stimuli.
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Affiliation(s)
- Patrick W Sheppard
- Department of Mechanical Engineering, University of California, Santa Barbara, Engineering II Bldg,, Santa Barbara, CA 93106-5070, USA
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137
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Koh G, Lee DY. Mathematical modeling and sensitivity analysis of the integrated TNFα-mediated apoptotic pathway for identifying key regulators. Comput Biol Med 2011; 41:512-28. [PMID: 21632045 DOI: 10.1016/j.compbiomed.2011.04.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2010] [Revised: 03/30/2011] [Accepted: 04/28/2011] [Indexed: 12/20/2022]
Abstract
TNFα-mediated apoptosis is one of the complex and tightly regulated cellular processes as it involves the activation of both pro- and anti-apoptotic signaling pathways. Thus, it is important to elucidate the molecular players of this process and their dynamics in order to gain an in-depth understanding of the mechanisms underlying apoptosis. To this end, we proposed an integrated model of TNFα-mediated apoptosis pathway in Type I cells, formulated based on the principles of mass action kinetics. The model includes major apoptotic modules-the extrinsic and intrinsic pathways, the NFκB survival signaling and various regulatory mechanisms. We performed simulations and sensitivity analyses to study the role of NFκB pathway in regulating apoptosis, and identified IAP as one of the more potent regulators of apoptosis.
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Affiliation(s)
- Geoffrey Koh
- Bioprocessing Technology Institute, Agency for Science, Technology and Research (A*STAR), 20 Biopolis Way, #06-01, Centros, Singapore 138668, Singapore.
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138
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Abstract
Under inflammatory situations, endoplasmic reticulum (ER) stress occurs at local sites and modulates inflammatory processes. NF-κB is a key regulator for immune and inflammatory responses, and its activity is influenced by ER stress positively or negatively. Recent investigation suggested that ER stress induces activation of NF-κB in the early phase, whereas in the later phase, consequent unfolded protein response (UPR) inhibits NF-κB. This review summarizes current knowledge on potential mechanisms underlying the biphasic, bidirectional regulation of NF-κB by the UPR and possible roles for ER stress in the regulation of inflammation.
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Affiliation(s)
- Masanori Kitamura
- Department of Molecular Signaling, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, Yamanashi, Japan.
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139
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Tumor necrosis factor induces GSK3 kinase-mediated cross-tolerance to endotoxin in macrophages. Nat Immunol 2011; 12:607-15. [PMID: 21602809 DOI: 10.1038/ni.2043] [Citation(s) in RCA: 133] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Accepted: 04/20/2011] [Indexed: 12/14/2022]
Abstract
Endotoxin tolerance, a key mechanism for suppressing excessive inflammatory cytokine production, is induced by prior exposure of macrophages to Toll-like receptor (TLR) ligands. Induction of cross-tolerance to endotoxin by endogenous cytokines has not been investigated. Here we show that prior exposure to tumor necrosis factor (TNF) induced a tolerant state in macrophages, with less cytokine production after challenge with lipopolysaccharide (LPS) and protection from LPS-induced death. TNF-induced cross-tolerization was mediated by suppression of LPS-induced signaling and chromatin remodeling. TNF-induced cross-tolerance was dependent on the kinase GSK3, which suppressed chromatin accessibility and promoted rapid termination of signaling via the transcription factor NF-κB by augmenting negative feedback by the signaling inhibitors A20 and IκBα. Our results demonstrate an unexpected homeostatic function for TNF and a GSK3-mediated mechanism for the prevention of prolonged and excessive inflammation.
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140
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Hughey JJ, Lee TK, Covert MW. Computational modeling of mammalian signaling networks. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2011; 2:194-209. [PMID: 20836022 DOI: 10.1002/wsbm.52] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
One of the most exciting developments in signal transduction research has been the proliferation of studies in which a biological discovery was initiated by computational modeling. In this study, we review the major efforts that enable such studies. First, we describe the experimental technologies that are generally used to identify the molecular components and interactions in, and dynamic behavior exhibited by, a network of interest. Next, we review the mathematical approaches that are used to model signaling network behavior. Finally, we focus on three specific instances of 'model-driven discovery': cases in which computational modeling of a signaling network has led to new insights that have been verified experimentally.
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Affiliation(s)
- Jacob J Hughey
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Timothy K Lee
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Markus W Covert
- Department of Bioengineering, Stanford University, Stanford, CA, USA
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141
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Kang CC, Chuang YJ, Tung KC, Chao CC, Tang CY, Peng SC, Wong DSH. A genetic algorithm-based Boolean delay model of intracellular signal transduction in inflammation. BMC Bioinformatics 2011; 12 Suppl 1:S17. [PMID: 21342546 PMCID: PMC3044271 DOI: 10.1186/1471-2105-12-s1-s17] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Background Signal transduction is the major mechanism through which cells transmit external stimuli to evoke intracellular biochemical responses. Understanding relationship between external stimuli and corresponding cellular responses, as well as the subsequent effects on downstream genes, is a major challenge in systems biology. Thus, a systematic approach to integrate experimental data and qualitative knowledge to identify the physiological consequences of environmental stimuli is needed. Results In present study, we employed a genetic algorithm-based Boolean model to represent NF-κB signaling pathway. We were able to capture feedback and crosstalk characteristics to enhance our understanding on the acute and chronic inflammatory response. Key network components affecting the response dynamics were identified. Conclusions We designed an effective algorithm to elucidate the process of immune response using comprehensive knowledge about network structure and limited experimental data on dynamic responses. This approach can potentially be implemented for large-scale analysis on cellular processes and organism behaviors.
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Affiliation(s)
- Chu Chun Kang
- Department of Computer Science, National Tsing Hua University, Hsinchu, 30013 Taiwan, ROC.
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142
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Abstract
The molecular mechanisms underlying activation of the IκB kinase (IKK) complex are presumably best understood in the context of tumor necrosis factor (TNF) receptor-1 (TNFR1) signaling. In fact, it seems that most, if not all, proteins relevant for this process have been identified and extensive biochemical and genetic data are available for the role of these factors in TNF-induced IKK activation. There is evidence that protein modification-independent assembly of a core TNFR1 signaling complex containing TNFR1-associated death domain, receptor interacting kinase 1, TNF receptor-associated factor 2 and cellular inhibitor of apoptosis protein 1 and 2 starts a chain of nondegrading ubiquitination events that culminate in the recruitment and activation of IKK complex-stimulating kinases and the IKK complex itself. Here, we sum up the known details of TNFR1-induced IKK activation, address arising contradictions and discuss possible explanations resolving the apparent discrepancies.
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Affiliation(s)
- Harald Wajant
- Division of Molecular Internal Medicine, Department of Internal Medicine II, University Hospital Würzburg, Germany.
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143
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Kelly C, Shields MD, Elborn JS, Schock BC. A20 regulation of nuclear factor-κB: perspectives for inflammatory lung disease. Am J Respir Cell Mol Biol 2011; 44:743-8. [PMID: 21239605 DOI: 10.1165/rcmb.2010-0339tr] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Persistent activation of NF-κB is central to the pathogenesis of many inflammatory lung disorders, including cystic fibrosis, asthma, and chronic obstructive pulmonary disease. A20 is an endogenous negative regulator of NF-κB signaling, which has been widely described in autoimmune and inflammatory disorders, including diabetes and Crohn's disease, but which has received little attention in terms of chronic lung disorders. This review examines the existing body of research on A20 regulation of NF-κB signaling and details the mechanism and regulation of A20 action focusing, where possible, on pulmonary inflammation. A20 and its associated signaling molecules are highlighted as being of potential therapeutic interest for the treatment of inflammatory disorders, and a proposed model of A20 activity in inflammatory lung disease is provided.
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Affiliation(s)
- Catriona Kelly
- Queen’s University Belfast, Respiratory Research Cluster, Centre for Infection and Immunity, Belfast, United Kingdom
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144
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Phosphorylation-dependent association of the G4-1/G5PR regulatory subunit with IKKβ negatively modulates NF-κB activation through recruitment of protein phosphatase 5. Biochem J 2010; 433:187-96. [DOI: 10.1042/bj20100247] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The transcription factor NF-κB (nuclear factor κB) co-ordinates various gene expressions in response to diverse signals and is a critical regulator of inflammation and innate immunity. Several negative regulators of NF-κB have been identified as downstream targets of NF-κB and function as a feedback control of NF-κB activation. A few protein phosphatases have also been shown to inactivate NF-κB activation. However, little is known about how protein phosphatases detect and respond to NF-κB activation. In the present study, we report a regulatory subunit of PP5 (protein phosphatase 5), G4-1, that physically interacts with IKKβ [IκB (inhibitor of NF-κB) kinase β] and negatively regulates NF-κB activation. The association of G4-1 with IKKβ depends on the kinase activity of IKKβ. Mapping of the G4-1-binding domain of IKKβ reveals that the serine-rich domain in the C-terminus of IKKβ is required for G4-1 binding. When seven autophosphorylated serine residues in this domain were mutated to alanine, the mutant form of IKKβ lost its ability to bind G4-1 and was more potent than the wild-type kinase to activate NF-κB. Knockdown of G4-1 enhanced TNFα (tumour necrosis factor α)-induced NF-κB activity, and knockdown of PP5 totally abolished the inhibitory activity of G4-1 on NF-κB activation. The results of the present study suggest that G4-1 functions as an adaptor to recruit PP5 to the phosphorylated C-terminus of activated IKKβ and to down-regulate the activation of IKKβ.
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145
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Abstract
Two distinct nuclear factor κB (NFκB) signaling pathways have been described; the canonical pathway that mediates inflammatory responses, and the non-canonical pathway that is involved in immune cell differentiation and maturation and secondary lymphoid organogenesis. The former is dependent on the IκB kinase adaptor molecule NEMO, the latter is independent of it. Here, we review the molecular mechanisms of regulation in each signaling axis and attempt to relate the apparent regulatory logic to the physiological function. Further, we review the recent evidence for extensive cross-regulation between these two signaling axes and summarize them in a wiring diagram. These observations suggest that NEMO-dependent and -independent signaling should be viewed within the context of a single NFκB signaling system, which mediates signaling from both inflammatory and organogenic stimuli in an integrated manner. As in other regulatory biological systems, a systems approach including mathematical models that include quantitative and kinetic information will be necessary to characterize the network properties that mediate physiological function, and that may break down to cause or contribute to pathology.
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146
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Behar M, Hoffmann A. Understanding the temporal codes of intra-cellular signals. Curr Opin Genet Dev 2010; 20:684-93. [PMID: 20956081 DOI: 10.1016/j.gde.2010.09.007] [Citation(s) in RCA: 144] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Revised: 09/15/2010] [Accepted: 09/15/2010] [Indexed: 01/07/2023]
Abstract
The health of organisms and cells depends on appropriate responses to diverse internal and external cues, stimuli, or challenges, such as changes in hormone or cytokine levels, or exposure to a pathogen. Cellular responses must be tailored to the identity and intensity of the stimulus and therefore intra-cellular signals must carry information about both. However, signaling mediators often form intricate networks that react to multiple stimuli yet manage to produce stimulus-specific responses. The multi-functionality ('functional pleiotropism') of signaling nodes suggests that biological networks have evolved ways of passing physiologically relevant stimulus information through shared channels. Increasing evidence supports the notion that this is achieved in part through temporal regulation of signaling mediators' activities. The present challenge is to identify the features of temporal activity profile that represent information about a given stimulus and understand how cells read the temporal codes to control their responses.
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Affiliation(s)
- Marcelo Behar
- Signaling Systems Laboratory, BioCircuits Institute, and San Diego Center for Systems Biology of Cellular Stress Responses, University of California, San Diego, 9500 Gillman Dr, La Jolla, CA 92093, United States
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147
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Modeling oscillatory control in NF-κB, p53 and Wnt signaling. Curr Opin Genet Dev 2010; 20:656-64. [PMID: 20934871 DOI: 10.1016/j.gde.2010.08.008] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Revised: 08/11/2010] [Accepted: 08/31/2010] [Indexed: 01/22/2023]
Abstract
Oscillations are commonly observed in cellular behavior and span a wide range of timescales, from seconds in calcium signaling to 24 hours in circadian rhythms. In between lie oscillations with time periods of 1-5 hours seen in NF-κB, p53 and Wnt signaling, which play key roles in the immune system, cell growth/death and embryo development, respectively. In the first part of this article, we provide a brief overview of simple deterministic models of oscillations. In particular, we explain the mechanism of saturated degradation that has been used to model oscillations in the NF-κB, p53 and Wnt systems. The second part deals with the potential physiological role of oscillations. We use the simple models described earlier to explore whether oscillatory signals can encode more information than steady-state signals. We then discuss a few simple genetic circuits that could decode information stored in the average, amplitude or frequency of oscillations. The presence of frequency-detector circuit downstream of NF-κB or p53 would be a strong clue that oscillations are important for the physiological response of these signaling systems.
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148
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Plant D, Farragher T, Flynn E, Martin P, Eyre S, Bunn D, Worthington J, Symmons D, Barton A, Thomson W. A genetic marker at the OLIG3/TNFAIP3 locus associates with methotrexate continuation in early inflammatory polyarthritis: results from the Norfolk Arthritis Register. THE PHARMACOGENOMICS JOURNAL 2010; 12:128-33. [DOI: 10.1038/tpj.2010.80] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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149
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O'Dea E, Hoffmann A. The regulatory logic of the NF-kappaB signaling system. Cold Spring Harb Perspect Biol 2010; 2:a000216. [PMID: 20182598 DOI: 10.1101/cshperspect.a000216] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
NF-kappaB refers to multiple dimers of Rel homology domain (RHD) containing polypeptides, which are controlled by a stimulus-responsive signaling system that mediates the physiological responses to inflammatory intercellular cytokines, pathogen exposure, and developmental signals. The NF-kappaB signaling system operates on transient or short timescales, relevant to inflammation and immune responses, and on longer-term timescales relevant to cell differentiation and organ formation. Here, we summarize our current understanding of the kinetic mechanisms that allow for NF-kappaB regulation at these different timescales. We distinguish between the regulation of NF-kappaB dimer formation and the regulation of NF-kappaB activity. Given the number of regulators and reactions involved, the NF-kappaB signaling system is capable of integrating a multitude of signals to tune NF-kappaB activity, signal dose responsiveness, and dynamic control. We discuss the prevailing mechanisms that mediate signaling cross talk.
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Affiliation(s)
- Ellen O'Dea
- Signaling Systems Laboratory, Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA
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150
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Lee TK, Covert MW. High-throughput, single-cell NF-κB dynamics. Curr Opin Genet Dev 2010; 20:677-83. [PMID: 20846851 DOI: 10.1016/j.gde.2010.08.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 07/23/2010] [Accepted: 08/19/2010] [Indexed: 01/08/2023]
Abstract
Single cells in a population often respond differently to perturbations in the environment. Live-cell microscopy has enabled scientists to observe these differences at the single-cell level. Some advantages of live-cell imaging over population-based methods include better time resolution, higher sensitivity, automation, and richer datasets. One specific area where live-cell microscopy has made a significant impact is the field of NF-κB signaling dynamics, and recent efforts have focused on making live-cell imaging of these dynamics more high-throughput. We highlight the major aspects of increasing throughput and describe a current system that can monitor, image and analyze the NF-κB activation of thousands of single cells in parallel.
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Affiliation(s)
- Timothy K Lee
- Department of Bioengineering, Stanford University, 318 Campus Drive, Stanford, CA 94305, United States
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