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Ageeva T, Rizvanov A, Mukhamedshina Y. NF-κB and JAK/STAT Signaling Pathways as Crucial Regulators of Neuroinflammation and Astrocyte Modulation in Spinal Cord Injury. Cells 2024; 13:581. [PMID: 38607020 PMCID: PMC11011519 DOI: 10.3390/cells13070581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 03/18/2024] [Accepted: 03/26/2024] [Indexed: 04/13/2024] Open
Abstract
Spinal cord injury (SCI) leads to significant functional impairments below the level of the injury, and astrocytes play a crucial role in the pathophysiology of SCI. Astrocytes undergo changes and form a glial scar after SCI, which has traditionally been viewed as a barrier to axonal regeneration and functional recovery. Astrocytes activate intracellular signaling pathways, including nuclear factor κB (NF-κB) and Janus kinase-signal transducers and activators of transcription (JAK/STAT), in response to external stimuli. NF-κB and STAT3 are transcription factors that play a pivotal role in initiating gene expression related to astrogliosis. The JAK/STAT signaling pathway is essential for managing secondary damage and facilitating recovery processes post-SCI: inflammation, glial scar formation, and astrocyte survival. NF-κB activation in astrocytes leads to the production of pro-inflammatory factors by astrocytes. NF-κB and STAT3 signaling pathways are interconnected: NF-κB activation in astrocytes leads to the release of interleukin-6 (IL-6), which interacts with the IL-6 receptor and initiates STAT3 activation. By modulating astrocyte responses, these pathways offer promising avenues for enhancing recovery outcomes, illustrating the crucial need for further investigation into their mechanisms and therapeutic applications in SCI treatment.
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Affiliation(s)
- Tatyana Ageeva
- OpenLab Gene and Cell Technology, Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia; (A.R.)
| | - Albert Rizvanov
- OpenLab Gene and Cell Technology, Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia; (A.R.)
- Division of Medical and Biological Sciences, Tatarstan Academy of Sciences, 420111 Kazan, Russia
| | - Yana Mukhamedshina
- OpenLab Gene and Cell Technology, Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia; (A.R.)
- Department of Histology, Cytology and Embryology, Kazan State Medical University, 420012 Kazan, Russia
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Yang L, Chang Y, Wang Y, Wei J, Ge C, Song J. Identification and functional characterization of TNF receptor associated factor 3 in the sea cucumber Apostichopus japonicus. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2016; 59:128-135. [PMID: 26828393 DOI: 10.1016/j.dci.2016.01.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Revised: 01/22/2016] [Accepted: 01/27/2016] [Indexed: 06/05/2023]
Abstract
TNF receptor associated factors (TRAFs) are a family of proteins primarily involved in both adaptive and innate immunity. In this study, we identified a novel TRAF3 gene in Apostichopus japonicus by transcriptome sequencing and RACE approaches (designated as AjTRAF3). The full-length of AjTRAF3 was of 2796 bp including a 5' untranslated region (UTR) of 83 bp, a 3' UTR of 1066 bp and a putative open reading frame of 1647 bp encoding a polypeptide of 548 amino acid residues. The representative domains such as a RING finger domain (residues 54-96), two TRAF domains with zinc finger structure (residues 141-228), a coiled coil and a meprin and TRAF homology (MATH) domain (residues 396-522) were all detected in the deduced amino acids of AjTRAF3. AjTRAF3 was ubiquitously expressed in all examined tissues with predominant expression in the body wall and slightly weaker in intestine, respiratory tree, tube feet, coelomocytes and longitudinal muscle. Time-course expression analysis in coelomocytes revealed that AjTRAF3 was significantly depressed towards Vibrio splendidus infection with a 0.20-fold decrease at 12 h, compared to control levels. AjTRAF3 silencing could elevate intracellular ROS levels by 2.08-fold and 2.09-fold compared to each control group in vitro and in vivo, respectively. Taken together, all these results suggested that AjTRAF3 may play a crucial role in the processes of anti-bacteria response in sea cucumber through regulating ROS production.
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Affiliation(s)
- Limeng Yang
- Key Laboratory of Mariculture & Stock Enhancement in North China's Sea, Ministry of Agriculture, Dalian Ocean University, Dalian 116023, PR China
| | - Yaqing Chang
- Key Laboratory of Mariculture & Stock Enhancement in North China's Sea, Ministry of Agriculture, Dalian Ocean University, Dalian 116023, PR China.
| | - Yi Wang
- Key Laboratory of Mariculture & Stock Enhancement in North China's Sea, Ministry of Agriculture, Dalian Ocean University, Dalian 116023, PR China
| | - Jing Wei
- Key Laboratory of Mariculture & Stock Enhancement in North China's Sea, Ministry of Agriculture, Dalian Ocean University, Dalian 116023, PR China
| | - Chen Ge
- Key Laboratory of Mariculture & Stock Enhancement in North China's Sea, Ministry of Agriculture, Dalian Ocean University, Dalian 116023, PR China
| | - Jian Song
- Key Laboratory of Mariculture & Stock Enhancement in North China's Sea, Ministry of Agriculture, Dalian Ocean University, Dalian 116023, PR China
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Van Roey K, Davey NE. Motif co-regulation and co-operativity are common mechanisms in transcriptional, post-transcriptional and post-translational regulation. Cell Commun Signal 2015; 13:45. [PMID: 26626130 PMCID: PMC4666095 DOI: 10.1186/s12964-015-0123-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 11/24/2015] [Indexed: 01/01/2023] Open
Abstract
A substantial portion of the regulatory interactions in the higher eukaryotic cell are mediated by simple sequence motifs in the regulatory segments of genes and (pre-)mRNAs, and in the intrinsically disordered regions of proteins. Although these regulatory modules are physicochemically distinct, they share an evolutionary plasticity that has facilitated a rapid growth of their use and resulted in their ubiquity in complex organisms. The ease of motif acquisition simplifies access to basal housekeeping functions, facilitates the co-regulation of multiple biomolecules allowing them to respond in a coordinated manner to changes in the cell state, and supports the integration of multiple signals for combinatorial decision-making. Consequently, motifs are indispensable for temporal, spatial, conditional and basal regulation at the transcriptional, post-transcriptional and post-translational level. In this review, we highlight that many of the key regulatory pathways of the cell are recruited by motifs and that the ease of motif acquisition has resulted in large networks of co-regulated biomolecules. We discuss how co-operativity allows simple static motifs to perform the conditional regulation that underlies decision-making in higher eukaryotic biological systems. We observe that each gene and its products have a unique set of DNA, RNA or protein motifs that encode a regulatory program to define the logical circuitry that guides the life cycle of these biomolecules, from transcription to degradation. Finally, we contrast the regulatory properties of protein motifs and the regulatory elements of DNA and (pre-)mRNAs, advocating that co-regulation, co-operativity, and motif-driven regulatory programs are common mechanisms that emerge from the use of simple, evolutionarily plastic regulatory modules.
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Affiliation(s)
- Kim Van Roey
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117, Heidelberg, Germany.
- Health Services Research Unit, Operational Direction Public Health and Surveillance, Scientific Institute of Public Health (WIV-ISP), 1050, Brussels, Belgium.
| | - Norman E Davey
- Conway Institute of Biomolecular and Biomedical Sciences, University College Dublin, Dublin 4, Ireland.
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Yu XH, Zheng XL, Tang CK. Nuclear Factor-κB Activation as a Pathological Mechanism of Lipid Metabolism and Atherosclerosis. Adv Clin Chem 2015; 70:1-30. [PMID: 26231484 DOI: 10.1016/bs.acc.2015.03.004] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Atherosclerosis is a chronic inflammatory disease of the arterial wall with lipid-laden lesions, involving a complex interaction between multiple different cell types and cytokine networks. Inflammatory responses mark all stages of atherogenesis: from lipid accumulation in the intima to plaque formation and eventual rupture. One of the most important regulators of inflammation is the transcription factor nuclear factor-κB (NF-κB), which is activated through the canonical and noncanonical pathways in response to various stimuli. NF-κB has long been regarded as a proatherogenic factor, because it is implicated in multiple pathological processes during atherogenesis, including foam cell formation, vascular inflammation, proliferation of vascular smooth muscle cells, arterial calcification, and plaque progression. In contrast, inhibition of NF-κB signaling has been shown to protect against atherosclerosis. This chapter aims to discuss recent progress on the roles of NF-κB in lipid metabolism and atherosclerosis and also to highlight its potential therapeutic benefits.
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Affiliation(s)
- Xiao-Hua Yu
- Key Laboratory for Atherosclerology of Hunan Province, Molecular Target New Drug Discovery and Cooperative Innovation Center of Hunan Province, Life Science Research Center, University of South China, Hengyang, PR China
| | - Xi-Long Zheng
- Department of Biochemistry and Molecular Biology, The Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, The University of Calgary, Health Sciences Center, Calgary, Alberta, Canada
| | - Chao-Ke Tang
- Key Laboratory for Atherosclerology of Hunan Province, Molecular Target New Drug Discovery and Cooperative Innovation Center of Hunan Province, Life Science Research Center, University of South China, Hengyang, PR China.
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Jacque E, Schweighoffer E, Visekruna A, Papoutsopoulou S, Janzen J, Zillwood R, Tarlinton DM, Tybulewicz VLJ, Ley SC. IKK-induced NF-κB1 p105 proteolysis is critical for B cell antibody responses to T cell-dependent antigen. ACTA ACUST UNITED AC 2014; 211:2085-101. [PMID: 25225457 PMCID: PMC4172221 DOI: 10.1084/jem.20132019] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Jacque et al. investigate the functions of NF-κB1 p105 and its associated NF-κB–binding partners in B cells, using a mutant mouse strain that carries a form of the NF-κB1 precursor that is resistant to IKK-induced proteolysis. They identify a critical B cell–intrinsic role for this IKK signaling pathway in the antigen-induced survival and differentiation of follicular mature B cells. The importance of IκB kinase (IKK)–induced proteolysis of NF-κB1 p105 in B cells was investigated using Nfkb1SSAA/SSAA mice, in which this NF-κB signaling pathway is blocked. Nfkb1SSAA mutation had no effect on the development and homeostasis of follicular mature (FM) B cells. However, analysis of mixed bone marrow chimeras revealed that Nfkb1SSAA/SSAA FM B cells were completely unable to mediate T cell–dependent antibody responses. Nfkb1SSAA mutation decreased B cell antigen receptor (BCR) activation of NF-κB in FM B cells, which selectively blocked BCR stimulation of cell survival and antigen-induced differentiation into plasmablasts and germinal center B cells due to reduced expression of Bcl-2 family proteins and IRF4, respectively. In contrast, the antigen-presenting function of FM B cells and their BCR-induced migration to the follicle T cell zone border, as well as their growth and proliferation after BCR stimulation, were not affected. All of the inhibitory effects of Nfkb1SSAA mutation on B cell functions were rescued by normalizing NF-κB activation genetically. Our study identifies critical B cell-intrinsic functions for IKK-induced NF-κB1 p105 proteolysis in the antigen-induced survival and differentiation of FM B cells, which are essential for T-dependent antibody responses.
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Affiliation(s)
- Emilie Jacque
- Division of Immune Cell Biology, MRC National Institute for Medical Research, London NW7 1AA, England, UK
| | - Edina Schweighoffer
- Division of Immune Cell Biology, MRC National Institute for Medical Research, London NW7 1AA, England, UK
| | - Alexander Visekruna
- Division of Immune Cell Biology, MRC National Institute for Medical Research, London NW7 1AA, England, UK
| | - Stamatia Papoutsopoulou
- Division of Immune Cell Biology, MRC National Institute for Medical Research, London NW7 1AA, England, UK
| | - Julia Janzen
- Division of Immune Cell Biology, MRC National Institute for Medical Research, London NW7 1AA, England, UK
| | - Rachel Zillwood
- Division of Immune Cell Biology, MRC National Institute for Medical Research, London NW7 1AA, England, UK
| | - David M Tarlinton
- The Walter and Eliza Hall Institute for Medical Research, Parkville, Victoria 3052, Australia
| | - Victor L J Tybulewicz
- Division of Immune Cell Biology, MRC National Institute for Medical Research, London NW7 1AA, England, UK
| | - Steven C Ley
- Division of Immune Cell Biology, MRC National Institute for Medical Research, London NW7 1AA, England, UK
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6
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Lee HN, Kundu JK, Cha YN, Surh YJ. Resolvin D1 stimulates efferocytosis through p50/p50-mediated suppression of tumor necrosis factor-α expression. J Cell Sci 2013; 126:4037-47. [DOI: 10.1242/jcs.131003] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Phagocytosis of apoptotic neutrophils, termed efferocytosis, is essential for the resolution of inflammation as it prevents the exposure of surrounding tissues at the inflamed site to toxic contents of lytic cells. Resolvin D1 (RvD1), endogenously generated from docosahexaenoic acid during resolution of inflammation, is known to stimulate efferocytosis. However, the molecular mechanism underlying RvD1-mediated enhancement of efferocytosis remains largely unresolved. In the present study, murine macrophage-like RAW264.7 cells treated with lipopolysaccharide (LPS) exhibited markedly reduced efferocytic activity, but this was restored by the co-incubation with RvD1. RvD1-induced restoration of the efferocytic activity appears to be mediated by down-regulating the LPS-induced TNF-α expression. The inhibitory effect of RvD1 on LPS-induced TNF-α expression was associated with enhanced nuclear localization of p50/p50 homodimer and concomitant reduction of p65/p50 heterodimer accumulation in the nucleus. RvD1 triggered phosphorylation and proteasomal degradation of nuclear factor κB1 (NF-κB1) p105 to generate p50, which was subsequently translocated to nucleus as p50/p50 homodimer. Knockdown of NF-κB p50 abolished the ability of RvD1 to suppress TNF-α expression and also to restore efferocytosis, suggesting that the replacement of p65/p50 with p50/p50 homodimer in the nucleus is critical for RvD1-mediated stimulation of efferocytosis. In a murine peritonitis model, intraperitoneal administration of RvD1 abrogated the zymosan A-induced TNF-α production, thereby stimulating efferocytosis. Taken together, these findings indicate that RvD1 expedites the resolution of inflammation through induction of efferocytosis by p50/p50 homodimer-mediated repression of TNF-α production.
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Omega-3 docosahexaenoic acid and procyanidins inhibit cyclo-oxygenase activity and attenuate NF-κB activation through a p105/p50 regulatory mechanism in macrophage inflammation. Biochem J 2012; 441:653-63. [PMID: 21954853 DOI: 10.1042/bj20110967] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The inflammatory response has been implicated in the pathogenesis of many chronic diseases. Along these lines, the modulation of inflammation by consuming bioactive food compounds, such as ω-3 fatty acids or procyanidins, is a powerful tool to promote good health. In the present study, the administration of DHA (docosahexaenoic acid) and B1, B2 and C1 procyanidins, alone or in combination, prevented the inflammatory response induced by the LPS (lipopolysaccharide) endotoxin in human macrophages and brought them to the homoeostatic state. DHA and B1 were strong and selective negative regulators of cyclo-oxygenase 1 activity, with IC50 values of 13.5 μM and 8.0 μM respectively. Additionally, B2 and C1 were selective inhibitors of pro-inflammatory cyclo-oxygenase 2 activity, with IC50 values of 9.7 μM and 3.3 μM respectively. Moreover, DHA and procyanidins prevented the activation of the NF-κB (nuclear factor κB) cascade at both early and late stages with shared mechanisms. These included inhibiting IκBα (inhibitor of NF-κB α) phosphorylation, inducing the cytoplasmic retention of pro-inflammatory NF-κB proteins through p105 (NF-κB1) overexpression, favouring the nuclear translocation of the p50-p50 transcriptional repressor homodimer instead of the p50-p65 pro-inflammatory heterodimer, inhibiting binding of NF-κB DNA to κB sites and, finally, decreasing the release of NF-κB-regulated cytokines and prostaglandins. In conclusion, DHA and procyanidins are strong and selective inhibitors of cyclo-oxygenase activity and NF-κB activation through a p105/p50-dependent regulatory mechanism.
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Wei X, Zhang X, Flick LM, Drissi H, Schwarz EM, O'Keefe RJ. Titanium particles stimulate COX-2 expression in synovial fibroblasts through an oxidative stress-induced, calpain-dependent, NF-kappaB pathway. Am J Physiol Cell Physiol 2009; 297:C310-20. [PMID: 19494233 DOI: 10.1152/ajpcell.00597.2008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
In prosthetic loosening, bone resorption is induced by wear debris particles generated from the artificial joint articulation. Our prior work showed that synovial-like fibroblasts respond to titanium particles by producing receptor activator of NF-kappaB ligand (RANKL), a critical activator of osteoclastogenesis. While this effect occurs through a cyclooxygenase-2 (COX-2)-dependent pathway, the mechanism of COX-2 stimulation by titanium particles is not clear. Here we show that titanium particles induce COX-2 gene expression by activating NF-kappaB signaling. Inhibitor of NF-kappaB (IkappaBalpha) is degraded following particle treatment, permitting active NF-kappaB to translocate to the nucleus where it interacts with the COX-2 promoter and drives transcription. NF-kappaB activation is dependent on reactive oxygen species since antioxidants block the NF-kappaB signaling induced by particles. Surprisingly, IkappaBalpha degradation is independent of IKK (IkappaB kinase) and the 26S proteasome. Instead, calpain inhibitor can block the IkappaBalpha degradation induced by particles. Furthermore, the calpain-targeted COOH-terminal PEST sequence of IkappaBalpha is necessary for phosphorylation and degradation, consistent with a proteasome-independent mechanism of catabolism. Altogether, the data demonstrate a signaling pathway by which titanium particles induce oxidative stress, stimulate calpain-mediated NF-kappaB activation, and activate target gene expression, including COX-2. These findings define important targets for osteolysis but may also have importance in other diseases where fibroblasts respond to environmental particles, including pulmonary diseases.
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Affiliation(s)
- Xiaochao Wei
- Center for Musculoskeletal Research, Univ. of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
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9
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Masking of a nuclear signal motif by monoubiquitination leads to mislocalization and degradation of the regulatory enzyme cytidylyltransferase. Mol Cell Biol 2009; 29:3062-75. [PMID: 19332566 DOI: 10.1128/mcb.01824-08] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Monoubiquitination aids in the nuclear export and entrance of proteins into the lysosomal degradative pathway, although the mechanisms are unknown. Cytidylyltransferase (CCTalpha) is a proteolytically sensitive lipogenic enzyme containing an NH(2)-terminal nuclear localization signal (NLS). We show here that CCTalpha is monoubiquitinated at a molecular site (K(57)) juxtaposed near its NLS, resulting in disruption of its interaction with importin-alpha, nuclear exclusion, and subsequent degradation within the lysosome. Cellular expression of a CCTalpha-ubiquitin fusion protein that mimics the monoubiquitinated enzyme resulted in cytoplasmic retention. A CCTalpha K(57R) mutant exhibited an extended half-life, was retained in the nucleus, and displayed proteolytic resistance. Importantly, by using CCTalpha-ubiquitin hybrid constructs that vary in the intermolecular distance between ubiquitin and the NLS, we show that CCTalpha monoubiquitination masks its NLS, resulting in cytoplasmic retention. These results unravel a unique molecular mechanism whereby monoubiquitination governs the trafficking and life span of a critical regulatory enzyme in vivo.
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Kizaki T, Shirato K, Sakurai T, Ogasawara JE, Oh-ishi S, Matsuoka T, Izawa T, Imaizumi K, Haga S, Ohno H. Beta2-adrenergic receptor regulate Toll-like receptor 4-induced late-phase NF-kappaB activation. Mol Immunol 2009; 46:1195-203. [PMID: 19167076 DOI: 10.1016/j.molimm.2008.11.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Revised: 10/15/2008] [Accepted: 11/16/2008] [Indexed: 12/01/2022]
Abstract
Stimulation of Toll-like receptor 4 (TLR4) by lipopolysaccharide (LPS) triggers myeloid differentiation factor 88 (MyD88)-dependent early-phase NF-kappaB activation and Toll/IL-1 receptor domain-containing adaptor-inducing IFN-beta (TRIF)-dependent late-phase NF-kappaB activation. In a previous study, we have shown that beta(2)-adrenergic receptor (beta(2)AR) functions as a negative regulator of NF-kappaB activation through beta-arrestin 2 in the macrophage cell line RAW264 and that down-regulation of beta(2)AR expression in response to LPS is essential for NF-kappaB activation and expression of its target gene, inducible nitric oxide synthase (NOS II). Here, we demonstrate that beta(2)AR plays an important role in TRIF-dependent late-phase NF-kappaB activation. LPS-stimulated down-regulation was induced in MyD88-knockdown cells, but not in TRIF-knockdown cells, suggesting that beta(2)AR expression was down-regulated by the TRIF-dependent pathway. On the other hand, depletion of beta(2)AR or beta-arrestin 2 expression by siRNA decreased cytoplasmic IkappaB alpha and abrogated late-phase IkappaB alpha degradation and NF-kappaB activation in response to LPS. Inducible nitric oxide synthase (NOS II) expression was increased continuously during 24 h of LPS stimulation in control cells, but decreased in beta(2)AR or beta-arrestin 2-knockdown cells after 6 h of LPS stimulation. These findings suggest that beta(2)AR functions not only as a negative regulator of NF-kappaB activation, but also as a stabilizing factor of the NF-kappaB/IkappaB alpha complex through cytoplasmic beta-arrestin 2, and that TRIF-dependent down-regulation of beta(2)AR expression increases the level of cytoplasmic NF-kappaB/IkappaB alpha complex free from beta-arrestin 2, leading to continuous late-phase NF-kappaB activation.
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Affiliation(s)
- Takako Kizaki
- Department of Molecular Predictive Medicine and Sport Science, Kyorin University, School of Medicine, Mitaka 181-8611, Japan.
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Sriskantharajah S, Belich MP, Papoutsopoulou S, Janzen J, Tybulewicz V, Seddon B, Ley SC. Proteolysis of NF-kappaB1 p105 is essential for T cell antigen receptor-induced proliferation. Nat Immunol 2009; 10:38-47. [PMID: 19060899 DOI: 10.1038/ni.1685] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Accepted: 10/29/2008] [Indexed: 12/11/2022]
Abstract
To investigate the importance of proteolysis of NF-kappaB1 p105 induced by the kinase IKK in activation of the transcription factor NF-kappaB, we generated 'Nfkb1(SSAA/SSAA)' mice, in which the IKK-target serine residues of p105 were substituted with alanine. Nfkb1(SSAA/SSAA) mice had far fewer CD4+ regulatory and memory T cells because of cell-autonomous defects. These T cell subtypes require activation of NF-kappaB by the T cell antigen receptor for their generation, and the Nfkb1(SSAA) mutation resulted in less activation of NF-kappaB in CD4+ T cells and proliferation of CD4+ T cells after stimulation of the T cell antigen receptor. The Nfkb1(SSAA) mutation also blocked the ability of CD4+ T cells to provide help to wild-type B cells during a primary antibody response. IKK-induced p105 proteolysis is therefore essential for optimal T cell antigen receptor-induced activation of NF-kappaB and mature CD4+ T cell function.
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12
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Moiseeva EP, Heukers R. Indole-3-carbinol-induced modulation of NF-κB signalling is breast cancer cell-specific and does not correlate with cell death. Breast Cancer Res Treat 2007; 109:451-62. [PMID: 17653853 DOI: 10.1007/s10549-007-9669-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2007] [Accepted: 06/26/2007] [Indexed: 12/13/2022]
Abstract
Indole-3-carbinol (I3C), a dietary chemopreventive compound, induces cell death in human breast cancer cells by modulating activities of Src and epidermal growth factor receptor (EGFR). The effect of I3C on NF-kappaB, constitutively activated in breast cancer cells, was investigated. Nuclear extracts of MDA-MB-468, MDA-MB-231 and HBL100 cells contained all of the Rel proteins with similar expression patterns in the latter two. The level of NF-kappaB-regulated reporter gene expression was in the order HBL100 << MDA-MB-468 << MDA-MB-231. Upstream inhibition, using PI3K, EGFR or IKKbeta inhibitors, resulted in cell-specific effects on expression of the NF-kappaB-regulated reporter gene and endogenous genes Bcl-xL, IkappaBalpha and IL-6, as well as on cell viability. The expression patterns of Rel and several NF-kappaB-regulated genes and the response to LY249002 in MDA-MB-468 cells contrasted with those in other cells. I3C induced NF-kappaB-regulated reporter gene expression at 12 h in MDA-MB-468 cells. Conversely, it was reduced at 24 h in HBL100 cells. I3C treatment for 6 h alone or in combination with TNFalpha induced NF-kappaB-regulated reporter gene expression, detected 5 h later, in MDA-MB-468, but not HBL100 cells. I3C induced NF-kappaB p65/p50 DNA binding at 6.5 h, preceded by association of IKKbeta with the Src/EGFR complex and increased phospho-IkappaBalpha in MDA-MB468 cells. TNFalpha increased I3C-induced apoptosis in MDA-MB-468 and MDA-MB-231 cells. It also induced apoptosis, enhanced by I3C, in HBL100 cells. Hence, regulation of constitutive NF-kappaB was cell-specific. I3C influenced the NF-kappaB pathway in a cell-specific manner, which was not related to apoptosis. However, the combination of I3C and TNFalpha increased apoptosis in all cell lines.
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Affiliation(s)
- Elena P Moiseeva
- Departments of Biochemistry and Cancer Studies, Cancer Biomarkers and Prevention Group, Biocentre, University of Leicester, Leicester, LE1 7RH, UK.
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Gong P, Han J, Reddig K, Li HS. A potential dimerization region of dCAMTA is critical for termination of fly visual response. J Biol Chem 2007; 282:21253-8. [PMID: 17537720 DOI: 10.1074/jbc.m701223200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
CAMTAs are a group of Ca(2+)/calmodulin binding transcription activators that are implicated in brain tumor suppression, cardiac hypertrophy, and plant sensory responses. The sole fly CAMTA, dCAMTA, stimulates expression of an F-box gene, dFbxl4, to potentiate rhodopsin deactivation, which enables rapid termination of fly visual responses. Here we report that a dCAMTA fragment associated with a full-length protein in co-transfected human embryonic kidney 293 cells. The interaction site was mapped to a region within the DNA-binding CG-1 domain. With this potential dimerization site mutated, the full-length dCAMTA had defective nuclear localization. In transgenic flies, this mutant dCAMTA variant failed to stimulate expression of dFbxl4 and rescue the slow termination of light response phenotype of a dCAMTA null mutant fly. Our data suggest that dCAMTA may function as a dimer during fly visual regulation and that the CG-1 domain may mediate dimerization of CAMTA transcription factors.
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Affiliation(s)
- Ping Gong
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
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Basak S, Kim H, Kearns JD, Tergaonkar V, O’Dea E, Werner SL, Benedict CA, Ware CF, Ghosh G, Verma IM, Hoffmann A. A fourth IkappaB protein within the NF-kappaB signaling module. Cell 2007; 128:369-81. [PMID: 17254973 PMCID: PMC1831796 DOI: 10.1016/j.cell.2006.12.033] [Citation(s) in RCA: 297] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2006] [Revised: 07/06/2006] [Accepted: 12/21/2006] [Indexed: 12/15/2022]
Abstract
Inflammatory NF-kappaB/RelA activation is mediated by the three canonical inhibitors, IkappaBalpha, -beta, and -epsilon. We report here the characterization of a fourth inhibitor, nfkappab2/p100, that forms two distinct inhibitory complexes with RelA, one of which mediates developmental NF-kappaB activation. Our genetic evidence confirms that p100 is required and sufficient as a fourth IkappaB protein for noncanonical NF-kappaB signaling downstream of NIK and IKK1. We develop a mathematical model of the four-IkappaB-containing NF-kappaB signaling module to account for NF-kappaB/RelA:p50 activation in response to inflammatory and developmental stimuli and find signaling crosstalk between them that determines gene-expression programs. Further combined computational and experimental studies reveal that mutant cells with altered balances between canonical and noncanonical IkappaB proteins may exhibit inappropriate inflammatory gene expression in response to developmental signals. Our results have important implications for physiological and pathological scenarios in which inflammatory and developmental signals converge.
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Affiliation(s)
- Soumen Basak
- Department of Chemistry and Biochemistry, University of California, San Diego 9500 Gilman Dr La Jolla, CA 92093
- Signaling Systems Laboratory, University of California, San Diego 9500 Gilman Dr La Jolla, CA 92093
| | - Hana Kim
- Department of Chemistry and Biochemistry, University of California, San Diego 9500 Gilman Dr La Jolla, CA 92093
- Signaling Systems Laboratory, University of California, San Diego 9500 Gilman Dr La Jolla, CA 92093
| | - Jeffrey D. Kearns
- Department of Chemistry and Biochemistry, University of California, San Diego 9500 Gilman Dr La Jolla, CA 92093
- Signaling Systems Laboratory, University of California, San Diego 9500 Gilman Dr La Jolla, CA 92093
| | - Vinay Tergaonkar
- Laboratory of Genetics Salk Institute for Biological Studies La Jolla, CA 92037
| | - Ellen O’Dea
- Department of Chemistry and Biochemistry, University of California, San Diego 9500 Gilman Dr La Jolla, CA 92093
- Signaling Systems Laboratory, University of California, San Diego 9500 Gilman Dr La Jolla, CA 92093
| | - Shannon L. Werner
- Department of Chemistry and Biochemistry, University of California, San Diego 9500 Gilman Dr La Jolla, CA 92093
- Signaling Systems Laboratory, University of California, San Diego 9500 Gilman Dr La Jolla, CA 92093
| | - Chris A. Benedict
- Division of Molecular Immunology, La Jolla Institute for Allergy and Immunology, San Diego, California 92121, USA
| | - Carl F. Ware
- Division of Molecular Immunology, La Jolla Institute for Allergy and Immunology, San Diego, California 92121, USA
| | - Gourisankar Ghosh
- Department of Chemistry and Biochemistry, University of California, San Diego 9500 Gilman Dr La Jolla, CA 92093
| | - Inder M. Verma
- Laboratory of Genetics Salk Institute for Biological Studies La Jolla, CA 92037
| | - Alexander Hoffmann
- Department of Chemistry and Biochemistry, University of California, San Diego 9500 Gilman Dr La Jolla, CA 92093
- Signaling Systems Laboratory, University of California, San Diego 9500 Gilman Dr La Jolla, CA 92093
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15
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Parameswaran N, Pao CS, Leonhard KS, Kang DS, Kratz M, Ley SC, Benovic JL. Arrestin-2 and G protein-coupled receptor kinase 5 interact with NFkappaB1 p105 and negatively regulate lipopolysaccharide-stimulated ERK1/2 activation in macrophages. J Biol Chem 2006; 281:34159-70. [PMID: 16980301 DOI: 10.1074/jbc.m605376200] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Toll-like receptors (TLRs) are a recently described receptor class involved in the regulation of innate and adaptive immunity. Here, we demonstrate that arrestin-2 and GRK5 (G protein-coupled receptor kinase 5), proteins that regulate G protein-coupled receptor signaling, play a negative role in TLR4 signaling in Raw264.7 macrophages. We find that lipopolysaccharide (LPS)-induced ERK1/2 phosphorylation is significantly enhanced in arrestin-2 and GRK5 knockdown cells. To elucidate the mechanisms involved, we tested the effect of arrestin-2 and GRK5 knockdown on LPS-stimulated signaling components that are upstream of ERK phosphorylation. Upon LPS stimulation, IkappaB kinase promotes phosphorylation and degradation of NFkappaB1 p105 (p105), which releases TPL2 (a MAP3K), which phosphorylates MEK1/2, which in turn phosphorylates ERK1/2. We demonstrate that knockdown of arrestin-2 leads to enhanced LPS-induced phosphorylation and degradation of p105, enhanced TPL2 release, and enhanced MEK1/2 phosphorylation. GRK5 knockdown also results in enhanced IkappaB kinase-mediated p105 phosphorylation and degradation, whereas GRK2 and GRK6 knockdown have no effect on this pathway. In vitro analysis demonstrates that arrestin-2 directly binds to the COOH-terminal domain of p105, whereas GRK5 binds to and phosphorylates p105. Taken together, these results suggest that p105 phosphorylation by GRK5 and binding of arrestin-2 negatively regulates LPS-stimulated ERK activation. These results reveal that arrestin-2 and GRK5 are important negative regulatory components in TLR4 signaling.
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Affiliation(s)
- Narayanan Parameswaran
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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16
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Liu SF, Malik AB. NF-kappa B activation as a pathological mechanism of septic shock and inflammation. Am J Physiol Lung Cell Mol Physiol 2006; 290:L622-L645. [PMID: 16531564 DOI: 10.1152/ajplung.00477.2005] [Citation(s) in RCA: 564] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The pathophysiology of sepsis and septic shock involves complex cytokine and inflammatory mediator networks. NF-kappaB activation is a central event leading to the activation of these networks. The role of NF-kappaB in septic pathophysiology and the signal transduction pathways leading to NF-kappaB activation during sepsis have been an area of intensive investigation. NF-kappaB is activated by a variety of pathogens known to cause septic shock syndrome. NF-kappaB activity is markedly increased in every organ studied, both in animal models of septic shock and in human subjects with sepsis. Greater levels of NF-kappaB activity are associated with a higher rate of mortality and worse clinical outcome. NF-kappaB mediates the transcription of exceptional large number of genes, the products of which are known to play important roles in septic pathophysiology. Mice deficient in those NF-kappaB-dependent genes are resistant to the development of septic shock and to septic lethality. More importantly, blockade of NF-kappaB pathway corrects septic abnormalities. Inhibition of NF-kappaB activation restores systemic hypotension, ameliorates septic myocardial dysfunction and vascular derangement, inhibits multiple proinflammatory gene expression, diminishes intravascular coagulation, reduces tissue neutrophil influx, and prevents microvascular endothelial leakage. Inhibition of NF-kappaB activation prevents multiple organ injury and improves survival in rodent models of septic shock. Thus NF-kappaB activation plays a central role in the pathophysiology of septic shock.
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Affiliation(s)
- Shu Fang Liu
- Div. of Pulmonary and Critical Care Medicine, Long Island Jewish Medical Center, RM B371, New Hyde Park, NY 11040, USA.
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17
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Moorthy AK, Savinova OV, Ho JQ, Wang VYF, Vu D, Ghosh G. The 20S proteasome processes NF-kappaB1 p105 into p50 in a translation-independent manner. EMBO J 2006; 25:1945-56. [PMID: 16619030 PMCID: PMC1456938 DOI: 10.1038/sj.emboj.7601081] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2005] [Accepted: 03/15/2006] [Indexed: 11/09/2022] Open
Abstract
The NF-kappaB p50 is the N-terminal processed product of the precursor, p105. It has been suggested that p50 is generated not from full-length p105 but cotranslationally from incompletely synthesized molecules by the proteasome. We show that the 20S proteasome endoproteolytically cleaves the fully synthesized p105 and selectively degrades the C-terminus of p105, leading to p50 generation in a ubiquitin-independent manner. As small as 25 residues C-terminus to the site of processing are sufficient to promote processing in vivo. However, any p105 mutant that lacks complete ankyrin repeat domain (ARD) is processed aberrantly, suggesting that native processing must occur from a precursor, which extends beyond the ARD. Remarkably, the mutant p105 that lacks the internal region including the glycine-rich region (GRR) is completely degraded by 20S proteasome in vitro. This suggests that the GRR impedes the complete degradation of the p105 precursor, thus contributing to p50 generation.
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Affiliation(s)
- Anu K Moorthy
- Department of Chemistry and Biochemistry, University of California-San Diego, La Jolla, CA, USA
| | - Olga V Savinova
- Department of Chemistry and Biochemistry, University of California-San Diego, La Jolla, CA, USA
| | - Jessica Q Ho
- Department of Chemistry and Biochemistry, University of California-San Diego, La Jolla, CA, USA
| | - Vivien Ya-Fan Wang
- Department of Chemistry and Biochemistry, University of California-San Diego, La Jolla, CA, USA
| | - Don Vu
- Department of Chemistry and Biochemistry, University of California-San Diego, La Jolla, CA, USA
| | - Gourisankar Ghosh
- Department of Chemistry and Biochemistry, University of California-San Diego, La Jolla, CA, USA
- Department of Chemistry and Biochemistry, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0359, USA. Tel.: +1 858 822 0375; Fax: +1 858 822 1408; E-mail:
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18
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Ngo JCK, Chakrabarti S, Ding JH, Velazquez-Dones A, Nolen B, Aubol BE, Adams JA, Fu XD, Ghosh G. Interplay between SRPK and Clk/Sty Kinases in Phosphorylation of the Splicing Factor ASF/SF2 Is Regulated by a Docking Motif in ASF/SF2. Mol Cell 2005; 20:77-89. [PMID: 16209947 DOI: 10.1016/j.molcel.2005.08.025] [Citation(s) in RCA: 161] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2005] [Revised: 08/12/2005] [Accepted: 08/24/2005] [Indexed: 10/25/2022]
Abstract
The arginine-serine (RS)-rich domain of the SR protein ASF/SF2 is phosphorylated by SR protein kinases (SRPKs) and Clk/Sty kinases. However, the mode of phosphorylation by these kinases and their coordination in the biological regulation of ASF/SF2 is unknown. Here, we report the crystal structure of an active fragment of human SRPK1 bound to a peptide derived from an SR protein. This structure led us to identify a docking motif in ASF/SF2. We find that this docking motif restricts phosphorylation of ASF/SF2 by SRPK1 to the N-terminal part of the RS domain - a property essential for its assembly into nuclear speckles. We further show that Clk/Sty causes release of ASF/SF2 from speckles by phosphorylating the C-terminal part of its RS domain. These results suggest that the docking motif of ASF/SF2 is a key regulatory element for sequential phosphorylation by SRPK1 and Clk/Sty and, thus, is essential for its subcellular localization.
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Affiliation(s)
- Jacky Chi Ki Ngo
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
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19
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Tezel G, Yang X. Comparative gene array analysis of TNF-alpha-induced MAPK and NF-kappaB signaling pathways between retinal ganglion cells and glial cells. Exp Eye Res 2005; 81:207-17. [PMID: 16080915 DOI: 10.1016/j.exer.2005.01.022] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2004] [Revised: 01/07/2005] [Accepted: 01/25/2005] [Indexed: 01/09/2023]
Abstract
TNF-alpha has recently been identified to be a mediator of retinal ganglion cell (RGC) death, while glial cells are relatively protected against this death stimulus. To identify molecular mechanisms that control diverse responses of RGCs and glial cells to TNF-alpha, we studied differential gene expression between primary cultures of RGCs and glial cells exposed to TNF-alpha using cDNA array analysis of MAPK and NF-kappaB signaling pathways. Findings of this comparative analysis demonstrated differential regulation of various genes between RGCs and glial cells exposed to TNF-alpha. RT-PCR confirmed the differential expression of selected genes, and immunocytochemistry demonstrated gene products in cultured cells. Immunolabeling with phosphorylation site-specific antibodies also revealed differential post-translational modifications of selected proteins between cell types. Identification of signaling molecules differentially regulated in RGCs and glial cells can improve our understanding of the diverse cellular responses and provide targets for neuroprotective interventions in several neurodegenerative conditions.
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Affiliation(s)
- Gülgün Tezel
- Department of Ophthalmology and Visual Sciences, Kentucky Lions Eye Center, University of Louisville School of Medicine, Louisville, KY 40202, USA.
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20
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Demarchi F, Bertoli C, Greer PA, Schneider C. Ceramide triggers an NF-kappaB-dependent survival pathway through calpain. Cell Death Differ 2005; 12:512-22. [PMID: 15933726 DOI: 10.1038/sj.cdd.4401592] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
We have shown that C2 ceramide, a cell-permeable analog of this lipid second messenger, triggers an NF-kappaB dependent survival pathway that counteracts cell death. Activation of NF-kappaB and subsequent induction of prosurvival genes relies on calpain activity and is prevented on silencing of the calpain small subunit (Capn4) that is required for the function of ubiquitous calpains. We have demonstrated that p105 (NF-kappaB1) and its proteolytic product p50 can be targets of micro- and milli-calpain in vitro and that a p50 deletion mutant, lacking both the N- and the C-terminal ends, is resistant to calpain-mediated degradation. Capn4 silencing results in stabilization of endogenous p105 and p50 in diverse human cell lines. Furthermore, p105 processing and activation of NF-kappaB survival genes in response to C2 ceramide is impaired in Capn4-/- mouse embryonic fibroblasts defective in calpain activity. Altogether, these data argue for the existence of a ceramide-calpain-NF-kappaB axis with prosurvival functions.
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Affiliation(s)
- F Demarchi
- L.N.C.I.B. Laboratorio Nazionale Consorzio Interuniversitario Biotecnologie AREA Science Park, Padriciano 99, 34012 Trieste, Italy
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21
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Tergaonkar V, Correa RG, Ikawa M, Verma IM. Distinct roles of IκB proteins in regulating constitutive NF-κB activity. Nat Cell Biol 2005; 7:921-3. [PMID: 16136188 DOI: 10.1038/ncb1296] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2005] [Accepted: 07/18/2005] [Indexed: 11/09/2022]
Abstract
The inhibitor of NF-kappaB (IkappaB) family of proteins is believed to regulate NF-kappaB activity by cytoplasmic sequestration. We show that in cells depleted of IkappaBalpha, IkappaBbeta and IkappaBepsilon proteins, a small fraction of p65 binds DNA and leads to constitutive activation of NF-kappaB target genes, even without stimulation, whereas most of the p65 remains cytoplasmic. These results indicate that although IkappaBalpha, IkappaBbeta and IkappaBepsilon proteins could be dispensable for cytoplasmic retention of NF-kappaB, they are essential for preventing NF-kappaB-dependent gene expression in the basal state. We also show that in the absence of IkappaBalpha, IkappaBbeta and IkappaBepsilon proteins, cytoplasmic retention of NF-kappaB by other cellular proteins renders the pathway unresponsive to activation.
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Affiliation(s)
- Vinay Tergaonkar
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
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22
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Fagerlund R, Kinnunen L, Köhler M, Julkunen I, Melén K. NF-{kappa}B is transported into the nucleus by importin {alpha}3 and importin {alpha}4. J Biol Chem 2005; 280:15942-51. [PMID: 15677444 DOI: 10.1074/jbc.m500814200] [Citation(s) in RCA: 229] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
NF-kappaB transcription factors are retained in the cytoplasm in an inactive form until they are activated and rapidly imported into the nucleus. We identified importin alpha3 and importin alpha4 as the main importin alpha isoforms mediating TNF-alpha-stimulated NF-kappaB p50/p65 heterodimer translocation into the nucleus. Importin alpha3 and alpha4 are close relatives in the human importin alpha family. We show that importin alpha3 isoform also mediates nuclear import of NF-kappaB p50 homodimer in nonstimulated cells. Importin alpha3 is shown to directly bind to previously characterized nuclear localization signals (NLSs) of NF-kappaB p50 and p65 proteins. Importin alpha molecules are known to have armadillo repeats that constitute the N-terminal and C-terminal NLS binding sites. We demonstrate by site-directed mutagenesis that NF-kappaB p50 binds to the N-terminal and p65 to the C-terminal NLS binding site of importin alpha3. In vitro competition experiments and analysis of cellular NF-kappaB suggest that NF-kappaB binds to importin alpha only when it is free of IkappaBalpha. The present study demonstrates that the nuclear import of NF-kappaB is a highly regulated process mediated by a subset of importin alpha molecules.
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Affiliation(s)
- Riku Fagerlund
- Departments of Viral Diseases and Immunology and Epidemiology and Health Promotion, National Public Health Institute, FIN-00300, Helsinki, Finland.
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23
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Abstract
Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) or Apo2L is a ligand of the TNF family interacting with five different receptors of the TNF receptor superfamily, including two death receptors. It has attracted wide interest as a potential anticancer therapy because some recombinant soluble forms of TRAIL induce cell death predominantly in transformed cells. The nuclear factor-kappaB (NFkappaB)?Rel family of proteins are composed of a group of dimeric transcription factors that have an outstanding role in the regulation of inflammation and immunity. Control of transcription by NFkappaB proteins can be of relevance to the function of TRAIL in three ways. First, induction of antiapoptotic NFkappaB dependent genes critically determines cellular susceptibility toward apoptosis induction by TRAIL-R1, TRAIL-R2, and other death receptors. Each of the multiple of known NFkappaB inducers therefore has the potential to interfere with TRAIL-induced cell death. Second, TRAIL and some of its receptors are inducible by NFkappaB, disclosing the possibility of autoamplifying TRAIL signaling loops. Third, the TRAIL death receptors can activate the NFkappaB pathway. This chapter summarizes basic knowledge regarding the understanding of the NFkappaB pathway and focuses on its multiple roles in TRAIL signaling.
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Affiliation(s)
- Harald Wajant
- Department of Molecular Internal Medicine Medical Polyclinic, University of Würzburg, D-97070 Würzburg, Germany
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24
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Abstract
An IkappaBalpha-based NF-kappaB super repressor (sr) has been used widely for studying genes regulated by NF-kappaB transcription factors. Repression of NF-kappaB by IkappaBalpha(sr) also facilitates tumor necrosis factor alpha-induced apoptosis in the cell. However, IkappaBalpha primarily targets RelA and c-Rel-containing complexes, leaving other NF-kappaB/Rel protein complexes, such as p50 and p52 homodimers, and RelB heterodimers uninhibited. Because these atypical NF-kappaB complexes also contribute to gene regulation and are activated in pathological conditions, broad inhibition of all NF-kappaB species is of significant pharmacological and clinical interests. We have designed, generated, and tested a p105-based NF-kappaB super repressor. We showed that p105(sr), which no longer generates p50 and undergoes signal-induced degradation, effectively inhibits all NF-kappaB activities. In addition, we also demonstrated that p105(sr) significantly enhances tumor necrosis factor alpha-mediated killing of MT1/2 skin papilloma cells where p50 homodimer activity is elevated. Our results suggest that p105(sr) is a broader range and effective NF-kappaB super repressor and can potentially be used in cells where a noncanonical NF-kappaB activity is dominant or multiple NF-kappaB activities are activated.
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Affiliation(s)
- Dexue Fu
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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