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Clayer E, Dalseno D, Kueh A, Lacey D, Tsai M, Arvell EH, Wimmer VC, Bouillet P. Severe Impairment of TNF Post-transcriptional Regulation Leads to Embryonic Death. iScience 2020; 23:101726. [PMID: 33210082 PMCID: PMC7658709 DOI: 10.1016/j.isci.2020.101726] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 09/08/2020] [Accepted: 10/20/2020] [Indexed: 02/07/2023] Open
Abstract
Post-transcriptional regulation mechanisms control mRNA stability or translational efficiency via ribosomes, and recent evidence indicates that it is a major determinant of the accurate levels of cytokine mRNAs. Transcriptional regulation of Tnf has been well studied and found to be important for the rapid induction of Tnf mRNA and regulation of the acute phase of inflammation, whereas study of its post-transcriptional regulation has been largely limited to the role of the AU-rich element (ARE), and to a lesser extent, to that of the constitutive decay element (CDE). We have identified another regulatory element (NRE) in the 3' UTR of Tnf and demonstrate that ARE, CDE, and NRE cooperate in vivo to efficiently downregulate Tnf expression and prevent autoimmune inflammatory diseases. We also show that excessive TNF may lead to embryonic death.
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Affiliation(s)
- Elise Clayer
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia,Department of Medical Biology, the University of Melbourne, Melbourne, VIC 3052, Australia
| | - Destiny Dalseno
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia,Department of Medical Biology, the University of Melbourne, Melbourne, VIC 3052, Australia
| | - Andrew Kueh
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia,Department of Medical Biology, the University of Melbourne, Melbourne, VIC 3052, Australia
| | - Derek Lacey
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia,Department of Medical Biology, the University of Melbourne, Melbourne, VIC 3052, Australia
| | - Minhsuang Tsai
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia,Department of Medical Biology, the University of Melbourne, Melbourne, VIC 3052, Australia
| | - Elyas H. Arvell
- Department of Medical Biology, the University of Melbourne, Melbourne, VIC 3052, Australia,The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC 3052, Australia
| | - Verena C. Wimmer
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia,Department of Medical Biology, the University of Melbourne, Melbourne, VIC 3052, Australia
| | - Philippe Bouillet
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia,Department of Medical Biology, the University of Melbourne, Melbourne, VIC 3052, Australia,Corresponding author
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Gein SV, Baeva TA. [Endomorphins: structure, localization, immunoregulatory activity]. ACTA ACUST UNITED AC 2020; 66:78-86. [PMID: 33351316 DOI: 10.14341/probl10364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 12/09/2019] [Accepted: 01/25/2020] [Indexed: 11/06/2022]
Abstract
Endomorphins – endogenous tetrapeptides with the highest affinity for the µ-opioid receptor. Currently, two tetrapeptides that differ in one amino acid residue have been isolated and characterized. The structure of endomorphins differs from the structure of members of three main families of opioid peptides: endorphins, enkephalins, and dynorphins, which contain the same N-terminal sequence. In the central nervous system, endomorphins are distributed everywhere, where they are primarily responsible for antinociception. Distribution of endomorphins in the immune system, similar to that of other opioid peptides, has allowed to suggest their active participation in the processes of immune regulation. This review summarizes modern views on the structure of endomorphins, their localization, possible intracellular mechanisms of signal transmission and their effects on the processes of activation, proliferation and differentiation of cells of innate and adaptive immunity. Endomorphins actively modulate the functions of the cells of the immune system. Peptides predominantly suppress adaptive immunity reactions. There effects on the functions of innate immunity cells (granulocytes, macrophages, monocytes, dendritic cells) depending on the conditions and can have either an inhibitory or stimulating orientation. Thus, endomorphins can be promising compounds that can effectively regulate both nociceptive signals and processes in the immune system.
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Affiliation(s)
- Sergey V Gein
- Institute of ecology and genetics of microorganisms - branch of the Perm Federal Research Center of the Ural Branch of the Russian Academy of Sciences; Perm State University
| | - Tatyana A Baeva
- Institute of ecology and genetics of microorganisms - branch of the Perm Federal Research Center of the Ural Branch of the Russian Academy of Sciences
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Qasem A, Naser SA. TNFα inhibitors exacerbate Mycobacterium paratuberculosis infection in tissue culture: a rationale for poor response of patients with Crohn's disease to current approved therapy. BMJ Open Gastroenterol 2018; 5:e000216. [PMID: 30073091 PMCID: PMC6067372 DOI: 10.1136/bmjgast-2018-000216] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 05/31/2018] [Accepted: 06/11/2018] [Indexed: 02/06/2023] Open
Abstract
Background The role of Mycobacteriumavium subspecies paratuberculosis (MAP) in Crohn’s disease (CD) is increasingly accepted as evident by detection of the bacteria in the blood and intestinal tissue from patients with CD, and by supporting data from several open-label anti-MAP treatment studies. Tumour necrosis factor alpha (TNFα) monoclonal antibodies (anti-TNFα) have been widely used for CD treatment. Despite the short-term benefit of anti-TNFα in controlling CD symptoms, most patients suffer from detrimental adverse effects, including higher susceptibility to mycobacterial infections. Methods We investigated the effect of recombinant cytokines and anti-TNFα therapeutics on macrophages infected with clinical MAP strain isolated from CD patient blood. MAP viability was measured in macrophages pulsed with PEGylated and non-PEGylated anti-TNFα monoclonal antibodies at concentrations 0 to 50 µg/mL and with rTNFα, rIL-6, rIL-12, rIL-23 and IFNγ at a final concentration of 1000 U/mL. Expression of proinflammatory cytokines was measured by RT-PCR following MAP infection. Results Both PEGylated and non-PEGylated forms of anti-TNFα increased MAP viability by nearly 1.5 logs. rIL-6 and rIL-12 induced MAP viability at 5.42±0.25 and 4.79±0.14 log CFU/mL, respectively. In contrast, rTNFα reduced MAP survival in infected macrophages by 2.63 logs. Expression of TNFα, IL-6 and IL-12 was upregulated threefold following MAP or M. tuberculosis infection compared with other bacterial strains (p<0.05), while expression of IL-23 and IFNγ was not significant after MAP infection. Conclusion The data indicate MAP-positive patients with CD receiving anti-TNFα treatment could result in favourable conditions for MAP infection, which explains the poor response of many patients with CD to anti-TNFα therapy.
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Affiliation(s)
- Ahmad Qasem
- Burnett School of Biomedical Sciences, Division of Molecular Microbiology, College of Medicine, University of Central Florida, Orlando, Florida, USA
| | - Saleh A Naser
- Burnett School of Biomedical Sciences, Division of Molecular Microbiology, College of Medicine, University of Central Florida, Orlando, Florida, USA
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Chaurasia MK, Palanisamy R, Harikrishnan R, Arasu MV, Al-Dhabi NA, Arockiaraj J. Molecular profiles and pathogen-induced transcriptional responses of prawn B cell lymphoma-2 related ovarian killer protein (BOK). FISH & SHELLFISH IMMUNOLOGY 2015; 45:598-607. [PMID: 25982403 DOI: 10.1016/j.fsi.2015.04.031] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 04/20/2015] [Accepted: 04/27/2015] [Indexed: 06/04/2023]
Abstract
In this study, we have reported a molecular characterization of the first B cell lymphoma-2 (BCL-2) related ovarian killer protein (BOK) from freshwater prawn Macrobrachium rosenbergii (Mr). BOK is a novel pro-apoptotic protein of the BCL-2 family that entails in mediating apoptosis to remove cancer cells. A cDNA sequence of MrBOK was identified from the prawn cDNA library and its full length was obtained by internal sequencing. The coding region of MrBOK yields a polypeptide of 291 amino acids. The analysis revealed that MrBOK contains a transmembrane helix at V(261)-L(283) and a putative BCL-2 family domain at V(144)-W(245). MrBOK also possessed four putative BCL-2 homology domains including BH1, BH2, BH3 and weak BH4. The BH3 contains 21 binding sites and among them five residues are highly conserved with the aligned BOK proteins. The homology analysis showed that MrBOK shared maximum similarity with the Caligus rogercresseyi BOK A. The topology of the phylogenetic tree was classified into nine sister groups which includes BOK, BAK, BAX, BAD, BCL-2, BCL-XL, NR13 and MCL members. The BOK protein group further sub-grouped into vertebrate and invertebrate BOK, wherein MrBOK located within insect monophyletic clad of invertebrate BOK. The secondary structural analysis showed that MrBOK contains 11 α-helices (52.2%) which are connected over random coils (47.7%). The 3D structure of MrBOK showed three central helices (α6, α7 and α8) which formed the core of the protein and are flanked on one side by α1, α2 and α3, and on the other side by α4, α5 and α11. MrBOK mRNA is expressed most abundantly (P < 0.05) in ovary compared to other tissues taken for analysis. Hence ovary was selected to study the possible roles of MrBOK mRNA regulation upon bacterial (Aeromonas hydrophila and Vibrio harveyi) and viral [white spot syndrome virus (WSSV) and M. rosenbergii nodovirus] infection. During bacterial and viral infection, the highest MrBOK mRNA transcription was varied at different time points. In bacterial infected ovary tissue, the highest mRNA expression was at 24 h post-infection, whereas in viral infection, the expression was highest at 48 h post-infection. Thus we can conclude that MrBOK functions as an apoptotic protein in intracellular programmed cell-death pathway to counteract the anti-apoptotic proteins released by bacterial and viral pathogens at the time of infection. This is the first study that emphasizes the importance of BOK during bacterial and viral infection in crustacean.
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Affiliation(s)
- Mukesh Kumar Chaurasia
- Division of Fisheries Biotechnology & Molecular Biology, Research Department of Biotechnology, Faculty of Science and Humanities, SRM University, Kattankulathur, 603 203, Chennai, Tamil Nadu, India
| | - Rajesh Palanisamy
- Division of Fisheries Biotechnology & Molecular Biology, Research Department of Biotechnology, Faculty of Science and Humanities, SRM University, Kattankulathur, 603 203, Chennai, Tamil Nadu, India
| | - Ramasamy Harikrishnan
- Department of Zoology, Pachaiyappa's College for Men, Kanchipuram, 631 501, Tamil Nadu, India
| | - Mariadhas Valan Arasu
- Department of Botany and Microbiology, Addiriyah Chair for Environmental Studies, College of Science, King Saud University, P. O. Box 2455, Riyadh, 11451, Saudi Arabia
| | - Naif Abdullah Al-Dhabi
- Department of Botany and Microbiology, Addiriyah Chair for Environmental Studies, College of Science, King Saud University, P. O. Box 2455, Riyadh, 11451, Saudi Arabia
| | - Jesu Arockiaraj
- Division of Fisheries Biotechnology & Molecular Biology, Research Department of Biotechnology, Faculty of Science and Humanities, SRM University, Kattankulathur, 603 203, Chennai, Tamil Nadu, India.
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Chan CS, Ming-Lum A, Golds GB, Lee SJ, Anderson RJ, Mui ALF. Interleukin-10 inhibits lipopolysaccharide-induced tumor necrosis factor-α translation through a SHIP1-dependent pathway. J Biol Chem 2012; 287:38020-7. [PMID: 22955274 DOI: 10.1074/jbc.m112.348599] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Production of the proinflammatory cytokine TNFα by activated macrophages is an important component of host defense. However, TNFα production must be tightly controlled to avoid pathological consequences. The anti-inflammatory cytokine IL-10 inhibits TNFα mRNA expression through activation of the STAT3 transcription factor pathway and subsequent expression of STAT3-dependent gene products. We hypothesized that IL-10 must also have more rapid mechanisms of action and show that IL-10 rapidly shifts existing TNFα mRNA from polyribosome-associated polysomes to monosomes. This translation suppression requires the presence of SHIP1 (SH2 domain-containing inositol 5'-phosphatase 1) and involves inhibition of Mnk1 (MAPK signal-integrating kinase 1). Furthermore, activating SHIP1 using a small-molecule agonist mimics the inhibitory effect of IL-10 on Mnk1 phosphorylation and TNFα translation. Our data support the existence of an alternative STAT3-independent pathway through SHIP1 for IL-10 to regulate TNFα translation during the anti-inflammatory response.
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Affiliation(s)
- Catherine S Chan
- Immunity and Infection Research Centre, Vancouver Coastal Health Research Institute, Vancouver, British Columbia, Canada
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Joshi S, Platanias LC. Mnk Kinases in Cytokine Signaling and Regulation of Cytokine Responses. Biomol Concepts 2012; 3:255-266. [PMID: 23710261 DOI: 10.1515/bmc-2011-0057] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The kinases Mnk1 and Mnk2 are activated downstream of the p38 MAPK and MEK/ERK signaling pathways. Extensive work over the years has shown that these kinases control phosphorylation of the eukaryotic initiation factor 4E (eIF4E) and regulate engagement of other effector elements, including hnRNPA1 and PSF. Mnk kinases are ubiquitously expressed and play critical roles in signaling for various cytokine receptors, while there is emerging evidence that they have important functions as mediators of pro-inflammatory cytokine production. In this review the mechanisms of activation of MNK pathways by cytokine receptors are addressed and their roles in diverse cytokine-dependent biological processes are reviewed. The clinical-translational implications of such work and the relevance of future development of specific MNK inhibitors for the treatment of malignancies and auto-immune disorders are discussed.
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Affiliation(s)
- Sonali Joshi
- Robert H. Lurie Comprehensive Cancer Center and Division of Hematology-Oncology, Northwestern University Medical School, and Jesse Brown VA, Medical Center, Chicago, IL ; Department of Molecular and Cellular Oncology, University of Texas MD Anderson Cancer Center, Houston, TX
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Joshi S, Platanias LC. Mnk Kinases in Cytokine Signaling and Regulation of Cytokine Responses. Biomol Concepts 2012. [PMID: 23710261 DOI: 10.1515/bmc-2011-1057] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The kinases Mnk1 and Mnk2 are activated downstream of the p38 MAPK and MEK/ERK signaling pathways. Extensive work over the years has shown that these kinases control phosphorylation of the eukaryotic initiation factor 4E (eIF4E) and regulate engagement of other effector elements, including hnRNPA1 and PSF. Mnk kinases are ubiquitously expressed and play critical roles in signaling for various cytokine receptors, while there is emerging evidence that they have important functions as mediators of pro-inflammatory cytokine production. In this review the mechanisms of activation of MNK pathways by cytokine receptors are addressed and their roles in diverse cytokine-dependent biological processes are reviewed. The clinical-translational implications of such work and the relevance of future development of specific MNK inhibitors for the treatment of malignancies and auto-immune disorders are discussed.
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Affiliation(s)
- Sonali Joshi
- Robert H. Lurie Comprehensive Cancer Center and Division of Hematology-Oncology, Northwestern University Medical School, and Jesse Brown VA, Medical Center, Chicago, IL ; Department of Molecular and Cellular Oncology, University of Texas MD Anderson Cancer Center, Houston, TX
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8
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Stumpo DJ, Lai WS, Blackshear PJ. Inflammation: cytokines and RNA-based regulation. WILEY INTERDISCIPLINARY REVIEWS-RNA 2010; 1:60-80. [PMID: 21956907 DOI: 10.1002/wrna.1] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The outcome of an inflammatory response depends upon the coordinated regulation of a variety of both pro-inflammatory and anti-inflammatory cytokines and other proteins. Regulation of these inflammation mediators can occur at multiple levels, including transcription, mRNA translation, post-translational modifications, and mRNA degradation. Post-transcriptional regulation has been shown to play an important role in controlling the expression of these mediators, allowing for normal initiation and resolution of the inflammatory response. Many inflammatory mediators have unstable mRNAs due, in part, to the presence of AU-rich elements in their 3'-untranslated regions. Increasing numbers of RNA-binding proteins have been identified that can bind to these AU-rich elements and then regulate the stability and/or translation of the mRNA. This review summarizes current knowledge about the role of several RNA-binding proteins that act through AU-rich elements to post-transcriptionally regulate the biosynthesis of proteins involved in inflammation.
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Affiliation(s)
- Deborah J Stumpo
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
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Yun JH, Koo JE, Koh YS. Mitogen-activated protein kinases are involved in tumor necrosis factor alpha production in macrophages infected with Orientia tsutsugamushi. Microbiol Immunol 2009; 53:349-55. [PMID: 19493203 DOI: 10.1111/j.1348-0421.2009.00127.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Orientia tsutsugamushi, an obligatory intracellular bacterium, is the causative agent of scrub typhus. Here the role of MAPK in TNF-alpha production in macrophages after infection with O. tsutsugamushi has been investigated. ERK1/2, JNK, and p38 MAPK became phosphorylated in Orientia-stimulated macrophages. Selective inhibitors of MAPK cascades could all significantly reduce Orientia-stimulated TNF-alpha production. Orientia-stimulated TNF-alpha production via p38 and JNK pathways was regulated by a post-transcriptional mechanism, whereas the ERK pathway mainly controlled the transcriptional step of TNF-alpha gene expression during infection. In conclusion, our data indicate that MAPK signaling is required to induce maximal TNF-alpha production in macrophages during Orientia infection.
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Affiliation(s)
- Ji-Hyun Yun
- Department of Microbiology, School of Medicine, BK21 Program, and Institute of Medical Science, Cheju National University, Jeju 690-756, Republic of Korea
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Yun JH, Koo JE, Koh YS. Mitogen-activated protein kinases and tumor necrosis factor alpha responses of macrophages infected with Orientia tsutsugamushi. World J Microbiol Biotechnol 2009. [DOI: 10.1007/s11274-009-0120-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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De Zoysa M, Jung S, Lee J. First molluscan TNF-alpha homologue of the TNF superfamily in disk abalone: molecular characterization and expression analysis. FISH & SHELLFISH IMMUNOLOGY 2009; 26:625-31. [PMID: 18984056 DOI: 10.1016/j.fsi.2008.10.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Revised: 10/04/2008] [Accepted: 10/07/2008] [Indexed: 05/16/2023]
Abstract
Tumor necrosis factor alpha (TNF-alpha) is considered as a multifunctional immune modulator that plays an important role in the innate and adaptive immune systems in vertebrates. Here, we described the characterization and expression analysis of the first TNF-alpha homologue in mollusk abalone, named as AbTNF-alpha. It has 930-bp full length with a 717-bp open reading frame (ORF), encoding 239 amino acids. The AbTNF-alpha amino acid sequence shows the characteristic TNF family signature, N-terminal transmembrane domain consisting of a hydrophobic amino acid cluster and cell attachment sequence at (155)RGD(157). Phylogenic analysis results showed that AbTNF-alpha is more related to the invertebrate Ciona savignyi TNF superfamily ligand member (CsTL). Quantitative real-time PCR expression results showed that AbTNF-alpha was constitutively expressed in both immune and non-immune tissues in a tissue specific manner. The highest constitutive expression was in the gill tissue with a 1.5-fold compared to hemocytes expression. The AbTNF-alpha mRNA expression in gill tissue was monitored in vivo stimulated by a mixture of pathogenic bacteria (Vibrio alginolyticus, Vibrio parahemolyticus, and Lysteria monocytogenes), viral haemorrhagic septicaemia virus (VHSV) and lipopolysaccharide (LPS). The AbTNF-alpha expression was significantly (p<0.05) induced by bacteria, VHSV and LPS compared to the control animals. Moreover, the highest level expressions of each induction were at 24 h (5.2-fold), 48 h (2.8-fold), and 48 h (3.3-fold) by bacteria mixture, VHSV and LPS, respectively. These results indicate that AbTNF-alpha could respond to pathogenic infection or stimulation and may play an important role in the abalone immune system.
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Affiliation(s)
- Mahanama De Zoysa
- Department of Biotechnology, College of Ocean Science, Cheju National University, Ara-Dong, Jeju 690-756, Republic of Korea
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12
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Yan Z, Lei-Butters D, Engelhardt JF, Leno GH. Indexing TNF-alpha gene expression using a gene-targeted reporter cell line. BMC Biol 2009; 7:8. [PMID: 19220876 PMCID: PMC2657777 DOI: 10.1186/1741-7007-7-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Accepted: 02/16/2009] [Indexed: 11/16/2022] Open
Abstract
Background Current cell-based drug screening technologies utilize randomly integrated reporter genes to index transcriptional activity of an endogenous gene of interest. In this context, reporter expression is controlled by known genetic elements that may only partially capture gene regulation and by unknown features of chromatin specific to the integration site. As an alternative technology, we applied highly efficient gene-targeting with recombinant adeno-associated virus to precisely integrate a luciferase reporter gene into exon 1 of the HeLa cell tumor necrosis factor-alpha (TNF-α) gene. Drugs known to induce TNF-α expression were then used to compare the authenticity of gene-targeted and randomly integrated transcriptional reporters. Results TNF-α-targeted reporter activity reflected endogenous TNF-α mRNA expression, whereas randomly integrated TNF-α reporter lines gave variable expression in response to transcriptional and epigenetic regulators. 5,6-Dimethylxanthenone-4-acetic acid (DMXAA), currently used in cancer clinical trials to induce TNF-α gene transcription, was only effective at inducing reporter expression from TNF-α gene-targeted cells. Conclusion We conclude that gene-targeted reporter cell lines provide predictive indexing of gene transcription for drug discovery.
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Affiliation(s)
- Ziying Yan
- Department of Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA.
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Ordás MC, Costa MM, Roca FJ, López-Castejón G, Mulero V, Meseguer J, Figueras A, Novoa B. Turbot TNFα gene: Molecular characterization and biological activity of the recombinant protein. Mol Immunol 2007; 44:389-400. [PMID: 16616958 DOI: 10.1016/j.molimm.2006.02.028] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2005] [Accepted: 02/27/2006] [Indexed: 11/17/2022]
Abstract
The tumor necrosis factor (TNF) superfamily is composed by several proteins with similar structure and functions. One of the main representatives of this family is TNF-alpha (TNFalpha), a proinflammatory cytokine which is produced by different immune cells and presents a wide variety of activities. Using the RACE technique, we have cloned and sequenced the turbot TNF cDNA. The analysis of its sequence showed several conserved motifs characteristic of members of the TNFalpha family. A phylogenetic tree constructed with different TNFs of fish and mammals grouped our sequence within the fish TNFalpha cluster. Therefore, the turbot TNF here studied was identified as TNFalpha. The complete TNFalpha gene was obtained by gene walking, and, similarly to the other known fish TNFalpha genes, presented three introns and four exons. A PCR was designed to study the turbot TNFalpha expression in vivo using as stimulus the bacteria Vibrio pelagius strain Hq222 and virus VHSV. The expression of the cytokine happened early after injection, and it was dependent on the pathogen injected and organ analyzed. Virus induced a higher TNFalpha expression, but this response was shorter in time than that induced by bacteria. In addition, TNFalpha expression was in general higher in kidney than in liver, as expected since the former is the haematopoietic organ of fish. The turbot recombinant TNFalpha (rTNFalpha) was obtained by IPTG induction of bacteria transformed with the pET15b-TNFalpha construct, and it was purified in native conditions. The recombinant protein was approximately 20 kDa in size, and its biological activity was assessed in vitro. No effect of the rTNFalpha neither alone nor in combination with LPS was observed on the chemiluminescence activity of turbot macrophages at any time tested. However, NO production was enhanced by the recombinant protein alone or with LPS 72 h after the addition of the treatments. Finally, turbot rTNFalpha was able to recruit and activate inflammatory cells when injected in gilthead seabream, although to a lesser extent than gilthead seabream rTNFalpha.
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Affiliation(s)
- M C Ordás
- Instituto de Investigaciones Marinas, Consejo Superior de Investigaciones Científicas (CSIC), Eduardo Cabello, 6, 36208 Vigo, Spain
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Buxadé M, Parra JL, Rousseau S, Shpiro N, Marquez R, Morrice N, Bain J, Espel E, Proud CG. The Mnks are novel components in the control of TNF alpha biosynthesis and phosphorylate and regulate hnRNP A1. Immunity 2005; 23:177-89. [PMID: 16111636 DOI: 10.1016/j.immuni.2005.06.009] [Citation(s) in RCA: 167] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2004] [Revised: 06/08/2005] [Accepted: 06/15/2005] [Indexed: 11/22/2022]
Abstract
Posttranscriptional regulatory mechanisms control TNFalpha expression through AU-rich elements in the 3'UTR of its mRNA. This is mediated through Erk and p38 MAP kinase signaling, although the mechanisms involved remain poorly understood. Here, we show that the MAP kinase signal-integrating kinases (Mnks), which are activated by both these pathways, regulate TNFalpha expression in T cells via the 3'UTR. A selective Mnk inhibitor or siRNA-mediated knockdown of Mnk1 inhibits TNFalpha production in T cells, whereas Mnk1 overexpression enhances expression of a reporter construct containing the TNFalpha 3'UTR. We identify ARE binding proteins that are Mnk substrates, such as hnRNP A1, which they phosphorylate at two sites in vitro. hnRNP A1 is phosphorylated in response to T cell activation, and this is blocked by Mnk inhibition. Moreover, Mnk-mediated phosphorylation decreases binding of hnRNP A1 to TNFalpha-ARE in vitro or TNFalpha-mRNA in vivo. Therefore, Mnks are novel players in cytokine regulation and potential new targets for anti-inflammatory therapy.
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Affiliation(s)
- Maria Buxadé
- Departament de Fisiologia, Universitat de Barcelona, Spain
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15
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Lee JY, Kim NA, Sanford A, Sullivan KE. Histone acetylation and chromatin conformation are regulated separately at the TNF-alpha promoter in monocytes and macrophages. J Leukoc Biol 2003; 73:862-71. [PMID: 12773519 DOI: 10.1189/jlb.1202618] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Tumor necrosis factor alpha (TNF-alpha) is a proinflammatory cytokine, which participates in a wide range of immunoregulatory activities. It is generally produced at highest levels by cells of the myeloid lineage in response to activation of pathogen recognition receptors such as Toll-like receptors. Impaired production predisposes to infection with intracellular organisms, and overproduction results in systemic or organ-specific inflammation. Control of expression is essential to maintain homeostasis, and this control is mediated via multiple strategies. We examined two separate aspects of chromatin accessibility in this study of the human TNF-alpha promoter. We examined the role of histone acetylation and chromatin remodeling in cell lines and primary cells and identified two individual steps associated with activation of TNF-alpha production. Histone H3 and H4 acetylation was found to be strongly dependent on the developmental stage of human monocytes. It did not appear to be regulated by acute stimuli, and instead, chromatin remodeling was found to occur after acute stimuli in a cell line competent to produce TNF-alpha. These data suggest that there is a hierarchy of controls regulating expression of TNF-alpha. Acetylation of histones is a prerequisite but is insufficient on its own for TNF-alpha production.
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Affiliation(s)
- Julia Y Lee
- Department of Pediatrics, Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, PA 19104, USA
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Azuma Y, Ohura K. Endomorphin-2 modulates productions of TNF-alpha, IL-1beta, IL-10, and IL-12, and alters functions related to innate immune of macrophages. Inflammation 2002; 26:223-32. [PMID: 12238565 DOI: 10.1023/a:1019766602138] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We evaluate immunological effects of opioid peptide endomorphin-2 on the production of cytokines related to inflammation and Th1/Th2 balance, and functions related to innate immune of rat peritoneal macrophages. Endomorphin-2 inhibited TNF-alpha, IL-10, and IL-12 productions, but potentiated IL-1beta production by macrophages. Moreover, endomorphin-2 potentiated macrophage adhesion to fibronectin, and the expression of adhesion molecule Mac-1 on macrophages. In contrast, endomorphin-2 suppressed phagocytosis of opsonized E. coli by macrophages, without affecting phagocytosis of non-opsonized E. coli. In addition, endomorphin-2 inhibited macrophage chemotaxis, and the production of superoxide anion by macrophages. These results suggest that endomorphin-2 may alter macrophage functions such as cytokine productions and functions related to innate immune.
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Affiliation(s)
- Yasutaka Azuma
- Department of Pharmacology, Osaka Dental University, Hirakata, Japan.
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17
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Inui Y, Azuma Y, Ohura K. Differential alteration of functions of rat peritoneal macrophages responsive to endogenous opioid peptide endomorphin-1. Int Immunopharmacol 2002; 2:1133-42. [PMID: 12349950 DOI: 10.1016/s1567-5769(02)00065-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Endomorphin-1 is a recently isolated endogenous opioid peptide, and potent and selective high affinity mu-opioid receptor agonist. We evaluate the role of endomorphin-1 on macrophage functions. Endomorphin-1 potentiated macrophage adhesion and the expression of adhesion molecule Mac-1 on macrophages. However, endomorphin-1 did not alter phagocytosis of Escherichia coli by macrophages. Moreover, endomorphin-1 inhibited macrophage chemotaxis and the production of superoxide anion by macrophages. On the contrary, endomorphin-1 inhibited TNF-alpha production by macrophages stimulated with both LPS and PMA, respectively. Similarly, endomorphin-1 suppressed IL-10 and IL-12 productions in response to LPS. In contrast, endomorphin-1 potentiated IL-1beta production by macrophages stimulated with PMA. These results suggest that endomorphin-1 may alter macrophage functions such as cytokine productions and functions related to natural host defense.
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Affiliation(s)
- Yoshiro Inui
- Department of Pharmacology, Osaka Dental University, Hirakata, Japan
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18
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Abstract
The aetiology of systemic, autoimmune, chronic inflammatory diseases--such as rheumatoid arthritis--is not known, and their pathogenesis is complex and multifactorial. However, progress in the characterization of intercellular mediators--proteins that are now known as cytokines--has led to the realization that one cytokine, tumour-necrosis factor (TNF; previously known as TNF-alpha), has an important role in the pathogenesis of rheumatoid arthritis. This discovery heralded a new era of targeted and highly effective therapeutics for rheumatoid arthritis and, subsequently, other chronic inflammatory diseases.
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Affiliation(s)
- Marc Feldmann
- Kennedy Institute, Rheumatology Division, Faculty of Medicine, Imperial College School of Medicine, London, UK.
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19
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Wen X, Wu GD. Evidence for epigenetic mechanisms that silence both basal and immune-stimulated transcription of the IL-8 gene. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 166:7290-9. [PMID: 11390479 DOI: 10.4049/jimmunol.166.12.7290] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
It is becoming increasingly clear that epigenetic silencing of gene transcription plays a critical role in the regulation of gene expression in many biological processes. Tight regulation of immunomodulatory substances that are important for the initiation of the inflammatory cascade, such as chemoattractive cytokines, is essential to prevent initiation of unrestrained immune activation. Using the Caco-2 intestinal cell line as a model, we reveal two distinctly different mechanisms by which the gene for the neutrophil chemoattractive cytokine IL-8 is silenced. Nuclear run-on studies, as well as stably transfected reporter and marked minigene constructs, demonstrate that cellular differentiation inhibits immune-activated transcription of the IL-8 gene, a mechanism that is dependent on histone deacetylase activity. Unexpectedly, this silencing mechanism does not involve previously described regulatory elements in the IL-8 promoter but rather cis-acting regions located at a distance from the IL-8 gene locus. Genomic elements distant to the immediate IL-8 locus are also required to silence aberrant basal transcriptional activity of the IL-8 promoter in the absence of immune activation. However, in this case, silencing occurs in a histone deacetylase-independent fashion. These findings were confirmed in transgenic mice in which, in the absence of these elements, aberrant IL-8 gene activity was present primarily in the intestinal tract. Epigenetic silencing of cytokine gene transcription through distant genomic elements is an important level of gene regulation that may be relevant to the pathogenesis of immunologic disease states.
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Affiliation(s)
- X Wen
- Division of Gastroenterology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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20
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Laing KJ, Wang T, Zou J, Holland J, Hong S, Bols N, Hirono I, Aoki T, Secombes CJ. Cloning and expression analysis of rainbow trout Oncorhynchus mykiss tumour necrosis factor-alpha. EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:1315-22. [PMID: 11231283 DOI: 10.1046/j.1432-1327.2001.01996.x] [Citation(s) in RCA: 163] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A rainbow trout (Oncorhynchus mykiss) gene for tumor necrosis factor (TNF) has been cloned and sequenced. The cDNA contains an open reading frame of 738 nucleotides that translate into a 246 amino-acid putative peptide, with a 5' untranslated region (UTR) of 140 bp and a 3' UTR of 506 bp. Two potential N-linked glycosylation sites exist in the translation. The genomic sequence measures 2007 bp and contains three introns that intercept four coding exons. Expression studies using RT-PCR have shown that the trout TNF gene is constitutively expressed in the gill and kidney of unstimulated fish. Trout TNF expression could be up-regulated by stimulation of isolated head kidney leucocytes with lipopolysaccharide (LPS). Similarly, stimulation of a trout macrophage cell line (RTS11) with LPS resulted in an increased transcript level, as did incubation with recombinant trout interleukin (IL)-1 beta. The optimal timing for induction of TNF expression in trout macrophages was determined using recombinant trout IL-1 beta, where a clear induction was apparent by 2 h and peaked at 4 h. Evidence that this TNF gene is equivalent to mammalian TNF-alpha is discussed.
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Affiliation(s)
- K J Laing
- Department of Zoology, University of Aberdeen, Aberdeen, UK
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21
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Brennan FM. A follow-up to "Anti-cytokine therapy in chronic destructive arthritis" by Wim B van den Berg. ARTHRITIS RESEARCH 2001; 3:211-3; discussion 214-5. [PMID: 11438037 PMCID: PMC128897 DOI: 10.1186/ar302] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 02/08/2001] [Revised: 03/29/2001] [Accepted: 04/03/2001] [Indexed: 11/10/2022]
Abstract
In recent years, the effectiveness of anti-TNF therapy in treating rheumatoid arthritis (RA) has become apparent. While trials of IL-1 receptor antagonist in RA have been encouraging, it clearly is more difficult to target two molecules (IL-1 alpha and beta) than one (TNF-alpha). In his review article, Professor Wim van den Berg argues that both TNF-alpha and IL-1 must be blocked in RA and that although TNF is clearly a potent inflammatory molecule, the dominant cytokine in the subsequent degradation of the joint tissue is IL-1. This commentary discusses his hypothesis in light of animal studies and the limitations of the conclusions that can be drawn from them. More broadly, it discusses the biology of TNF-alpha and IL-1 and suggests explanations of why TNF-alpha is a pivotal cytokine in this disease.
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Affiliation(s)
- F M Brennan
- Kennedy Institute of Rheumatology Division, Imperial College School of Medicine, Hammersmith, London, UK.
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22
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Rodriguez-Pascual F, Hausding M, Ihrig-Biedert I, Furneaux H, Levy AP, Förstermann U, Kleinert H. Complex contribution of the 3'-untranslated region to the expressional regulation of the human inducible nitric-oxide synthase gene. Involvement of the RNA-binding protein HuR. J Biol Chem 2000; 275:26040-9. [PMID: 10859327 DOI: 10.1074/jbc.m910460199] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Cytokine stimulation of human DLD-1 cells resulted in a marked expression of nitric-oxide synthase (NOS) II mRNA and protein accompanied by only a moderate increase in transcriptional activity. Also, there was a basal transcription of the NOS II gene, which did not result in measurable NOS II expression. The 3'-untranslated region (3'-UTR) of the NOS II mRNA contains four AUUUA motifs and one AUUUUA motif, known to destabilize the mRNAs of proto-oncogenes, nuclear transcription factors, and cytokines. Luciferase reporter gene constructs containing the NOS II 3'-UTR showed a significantly reduced luciferase activity. The embryonic lethal abnormal vision (ELAV)-like protein HuR was found to bind with high affinity to the adenylate/uridylate-rich elements of the NOS II 3'-UTR. Inhibition of HuR with antisense constructs reduced the cytokine-induced NOS II mRNA, whereas overexpression of HuR potentiated the cytokine-induced NOS II expression. This provides evidence that NOS II expression is regulated at the transcriptional and post-transcriptional level. Binding of HuR to the 3'-UTR of the NOS II mRNA seems to play an essential role in the stabilization of this mRNA.
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Affiliation(s)
- F Rodriguez-Pascual
- Department of Pharmacology, Johannes Gutenberg University, Obere Zahlbacher Strasse 67, D-55101 Mainz, Germany
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23
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Ndengele MM, Bellone CJ, Lechner AJ, Matuschak GM. Brief hypoxia differentially regulates LPS-induced IL-1beta and TNF-alpha gene transcription in RAW 264.7 cells. Am J Physiol Lung Cell Mol Physiol 2000; 278:L1289-96. [PMID: 10835336 DOI: 10.1152/ajplung.2000.278.6.l1289] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Episodes of tissue hypoxia and reoxygenation frequently occur during gram-negative bacteremia that progresses to septic shock. However, few studies have evaluated modulation by hypoxia and reoxygenation of the proinflammatory cytokine gene expression that is normally induced by gram-negative bacteremia or endotoxemia. In buffer-perfused organs, hypoxia downregulates Escherichia coli-induced expression of tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta in the liver but upregulates these cytokines in the lungs. To identify molecular mechanisms underlying these events, we investigated the effects of brief (1.5-h) hypoxia on TNF-alpha and IL-1beta expression in cultured RAW 264.7 cells during their continuous exposure to lipopolysaccharide (LPS) endotoxin derived from E. coli (serotype 055:B5) for up to 24 h. IL-1beta and TNF-alpha concentrations in cell lysates and culture supernatants were measured by ELISA, and steady-state mRNA was measured by Northern analysis. LPS-induced IL-1beta synthesis was downregulated by hypoxia at both the protein and mRNA levels despite no change in cellular redox status as measured by levels of GSH. In contrast, LPS-induced TNF-alpha production was unaffected by hypoxia as assessed by cell lysate mRNA and lysate and supernatant protein levels. Nuclear runoff analysis showed that downregulation of IL-1beta gene expression by hypoxia occurred transcriptionally. Allopurinol or catalase treatment did not alter modulation of LPS-induced IL-1beta expression by hypoxia, suggesting that this suppression was not caused by reactive oxygen species. Cycloheximide pretreatment suggested that hypoxia-induced downregulation of IL-1beta expression did not require de novo protein synthesis.
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Affiliation(s)
- M M Ndengele
- Department of Internal Medicine, Saint Louis University School of Medicine, MO 63110-0250, USA
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24
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Shurety W, Merino-Trigo A, Brown D, Hume DA, Stow JL. Localization and post-Golgi trafficking of tumor necrosis factor-alpha in macrophages. J Interferon Cytokine Res 2000; 20:427-38. [PMID: 10805378 DOI: 10.1089/107999000312379] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Tumor necrosis factor-alpha (TNF-alpha) is a proinflammatory cytokine secreted by activated macrophages. In this study, we examined the intracellular distribution and trafficking of TNF-alpha. Immunofluorescence and immunogold localization demonstrated that in lipopolysaccharide (LPS)-stimulated RAW264 macrophages, the greatest concentration of TNF-alpha is found in the perinuclear Golgi complex. Staining of the Golgi complex appeared 20 min after activation of cells and persisted for 2-12 h, and TNF-alpha appeared on the cell surface only transiently during this time. The rate of disappearance of Golgi staining correlated with the release of the cleaved, mature TNF-alpha into the medium. Pulse chase labeling and subcellular fractionation studies indicated that both 26-kDa and 17-kDa forms of TNF-alpha may be present at the level of the Golgi complex. Post-Golgi trafficking of TNF-alpha was modulated by agents that disrupt the cytoskeleton. Interferon-gamma (IFN-gamma), which primes macrophages for TNF-alpha-dependent cellular cytotoxicity, potentiated the effect of LPS by sustaining enhanced intracellular pools of TNF-alpha and also promoted redistribution of TNF-alpha into post-Golgi vesicular compartments. We propose that the primary pool of biologically active TNF-alpha in activated macrophages is held in the Golgi complex and that the cytokine is recruited directly from this intracellular pool for release in response to tumor cells or pathogens.
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Affiliation(s)
- W Shurety
- The Centre for Molecular and Cellular Biology, The University of Queensland, Brisbane, Australia
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25
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Hayes AL, Smith C, Foxwell BM, Brennan FM. CD45-induced tumor necrosis factor alpha production in monocytes is phosphatidylinositol 3-kinase-dependent and nuclear factor-kappaB-independent. J Biol Chem 1999; 274:33455-61. [PMID: 10559228 DOI: 10.1074/jbc.274.47.33455] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The pro-inflammatory cytokine tumor necrosis factor (TNF)-alpha plays a pivotal role in the pathogenesis of rheumatoid arthritis. The mechanisms involved in regulating monocyte/macrophage TNFalpha production are not yet fully understood but are thought to involve both soluble factors and cell/cell contact with other cell types. Ligation of certain cell surface receptors, namely CD45, CD44, and CD58, can induce the production of TNFalpha in monocytes. In this paper, we investigate further the signaling pathways utilized by cell surface receptors (specifically CD45) to induce monocyte TNFalpha and compare the common/unique pathways involved with that of lipopolysaccharide. The results indicate that monocyte TNFalpha induced upon CD45 ligation or lipopolysaccharide stimulation is differentially modulated by phosphatidylinositol 3-kinase and nuclear factor-kappaB but similarly regulated by p38 mitogen-activated protein kinase. These results demonstrate that both common and unique signaling pathways are utilized by different stimuli for the induction of TNFalpha. These observations may have a major bearing on approaches to inhibiting TNFalpha production in disease where the cytokine has a pathogenic role.
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Affiliation(s)
- A L Hayes
- Kennedy Institute of Rheumatology, Hammersmith, London W6 8LH, United Kingdom
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26
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Du X, Poltorak A, Silva M, Beutler B. Analysis of Tlr4-mediated LPS signal transduction in macrophages by mutational modification of the receptor. Blood Cells Mol Dis 1999; 25:328-38. [PMID: 10660480 DOI: 10.1006/bcmd.1999.0262] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In mouse macrophages (RAW 264.7 cells), toll-like receptor 4 (Tlr4) is a limiting factor in lipopolysaccharide (LPS) signal transduction. The expression of only 1-2 x 10(4) copies of recombinant Tlr4 per cell enhances sensitivity to LPS, shifting the EC50 by 30-fold to the left. Expression of the Tlr4(Lps-d) isoform of Tlr4 (found in C3H/HeJ mice) shifts the EC50 2600-fold to the right, essentially abolishing LPS responses. A truncated form of Tlr4, lacking a cytoplasmic domain, exerts only a weak inhibitory effect on signal transduction. Similarly, the normal or Tlr4(Lps-d) forms of protein lacking an ectodomain [corrected], cause modest inhibition of LPS signaling. Manipulations of Tlr4 structure and expression cause changes in LPS sensitivity that range over 3 to 4 orders of magnitude. These findings support the view that Tlr4 is an integral component of a solitary pathway for LPS signal transduction in macrophages and permit inferences related to the mechanism of signaling and its blockade.
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Affiliation(s)
- X Du
- Howard Hughes Medical Institute, Dallas, TX 75235-9050, USA
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27
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Seiler-Tuyns A, Dufour N, Spertini F. Human tumor necrosis factor-alpha gene 3' untranslated region confers inducible toxin responsiveness to homologous promoter in monocytic THP-1 cells. J Biol Chem 1999; 274:21714-8. [PMID: 10419483 DOI: 10.1074/jbc.274.31.21714] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To better define the role of 3' untranslated region (3'UTR) on transcriptional regulation of the human tumor necrosis factor (TNF)-alpha gene, monocytic human THP-1 cells were transfected with two TNF-alpha promoter constructs spanning base pairs -1897/-1 and -1214/-1, respectively, and linked to the rabbit beta-globin gene. Quantitative globin gene expression of chimerae was measured by reverse transcription-polymerase chain reaction. A construct linking the chicken beta-actin promoter and a deleted portion of the beta-globin gene was cotransfected and used as internal standard. Unexpectedly, when THP-1 cells were stimulated with lipopolysaccharide or toxic shock syndrome toxin-1, gene regulation was hardly detected. In contrast, endogenous TNF-alpha gene regulation measured by the same reverse transcription-polymerase chain reaction procedure was vigorous. Remarkably, ligation of 3'UTR to chimeric constructs led to a drastic drop in the basal level of chimeric gene expression, resulting in a 15- to 40-fold induction of the reporter gene. Consistently, when the TNF-alpha promoter was replaced by the cytomegalovirus early immediate promoter, gene expression was also uniformly reduced but was no longer up-regulated upon stimulation with lipopolysaccharide and toxic shock syndrome toxin-1. These data provide the first line of evidence that, in addition to its role in TNF-alpha transcript stability and translation, human TNF-alpha 3'UTR also participates in modulating gene expression at the transcriptional level.
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Affiliation(s)
- A Seiler-Tuyns
- Division of Immunology and Allergy, Department of Medicine, Centre Hospitalier Universitaire Vaudois, CH-1011 Lausanne, Switzerland
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28
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Yamada M, Tanimoto A, Ichinowatari G, Yaginuma H, Ohuchi K. Possible participation of intracellular platelet-activating factor in tumor necrosis factor-alpha production by rat peritoneal macrophages. Eur J Pharmacol 1999; 374:341-50. [PMID: 10422778 DOI: 10.1016/s0014-2999(99)00337-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Stimulation of rat peritoneal macrophages by thapsigargin (46.1 nM) increased levels of tumor necrosis factor-alpha and prostaglandin E2 in the conditioned medium. Platelet-activating factor (PAF) was not detected in the conditioned medium, but the level of cell-associated PAF was increased transiently by thapsigargin. The PAF receptor antagonists such as E6123 ((S)-(+)-6-(2-chlorophenyl)-3-cyclopro-panecarbonyl-8,11-dim ethyl-2,3,4,5-tetrahydro-8 H-pyrido[4',3':4,5]thieno [3,2-f][1,2,4]triazolo[4,3-a][1,4]diazepine), L-652,73 1 (2,5-bis(3,4,5-trimethoxyphenyl) tetrahydrofuran) and CV-6209 (2-[N-acetyl-N-(2-methoxy-3-octadecyl-carbamoyloxy propoxycarbonyl)aminomethyl]-1-ethylpyridinium chloride) inhibited thapsigargin-induced production of tumor necrosis factor-alpha. The cyclooxygenase inhibitor indomethacin inhibited prostaglandin E2 production, and further enhanced thapsigargin-induced tumor necrosis factor-alpha production in parallel with further increase in cell-associated PAF production. The enhancement of tumor necrosis factor-alpha production induced by thapsigargin plus indomethacin was also inhibited by E6123, L-652,731 and CV-6209. However, exogenously added PAF up to 100 nM did not stimulate production of tumor necrosis factor-alpha. The level of tumor necrosis factor-alpha mRNA was increased by thapsigargin, but was lowered by the PAF receptor antagonist E6123, suggesting that the inhibition of tumor necrosis factor-alpha production by the PAF receptor antagonist is induced at the level of mRNA for tumor necrosis factor-alpha. These findings suggested that concurrently produced cell-associated PAF in thapsigargin-stimulated macrophages up-regulates production of tumor necrosis factor-alpha by acting as an intracellular signaling molecule and the PAF receptor antagonists might penetrate into the cells and antagonize the action of intracellular PAF.
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Affiliation(s)
- M Yamada
- Department of Pathophysiological Biochemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, Japan
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29
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Rojas M, Olivier M, Gros P, Barrera LF, García LF. TNF-α and IL-10 Modulate the Induction of Apoptosis by Virulent Mycobacterium tuberculosis in Murine Macrophages. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.162.10.6122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
The Bcg/Nramp1 gene controls early resistance and susceptibility of macrophages to mycobacterial infections. We previously reported that Mycobacterium tuberculosis-infected (Mtb) B10R (Bcgr) and B10S (Bcgs) macrophages differentially produce nitric oxide (NO−), leading to macrophage apoptosis. Since TNF-α and IL-10 have opposite effects on many macrophage functions, we determined the number of cells producing TNF-α and IL-10 in Mtb-infected or purified protein derivative-stimulated B10R and B10S macrophages lines, and Nramp1+/+ and Nramp1−/− peritoneal macrophages and correlated them with Mtb-mediated apoptosis. Mtb infection and purified protein derivative treatment induced more TNF-α+Nramp1+/+ and B10R, and more IL-10+Nramp1−/− and B10S cells. Treatment with mannosylated lipoarabinomannan, which rescues macrophages from Mtb-induced apoptosis, augmented the number of IL-10 B10R+ cells. Anti-TNF-α inhibited apoptosis, diminished NO− production, p53, and caspase 1 activation and increased Bcl-2 expression. In contrast, anti-IL-10 increased caspase 1 activation, p53 expression, and apoptosis, although there was no increment in NO− production. Murine rTNF-α induced apoptosis in noninfected B10R and B10S macrophages that was reversed by murine rIL-10 in a dose-dependent manner with concomitant inhibition of NO− production and caspase 1 activation. NO− and caspase 1 seem to be independently activated in that aminoguanidine did not affect caspase 1 activation and the inhibitor of caspase 1, Tyr-Val-Ala-Asp-acylooxymethylketone, did not block NO− production; however, both treatments inhibited apoptosis. These results show that Mtb activates TNF-α- and IL-10-dependent opposite signals in the induction of macrophage apoptosis and suggest that the TNF-α-IL-10 ratio is controlled by the Nramp1 background of resistance/susceptibility and may account for the balance between apoptosis and macrophage survival.
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Affiliation(s)
- Mauricio Rojas
- *Grupo de Inmunología Celular e Inmunogenética, Laboratorio Central de Investigaciones, Centro de Investigaciones Médicas. Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia
- †Laboratoire d’Infectiologie, Centre de Recherche du Centre Hospitalier de l’Université de Québec (Pavillon Centre Hospitalier de l’Université Laval), Université Laval, Ste.-Foy, Québec, Canada; and
| | - Martin Olivier
- †Laboratoire d’Infectiologie, Centre de Recherche du Centre Hospitalier de l’Université de Québec (Pavillon Centre Hospitalier de l’Université Laval), Université Laval, Ste.-Foy, Québec, Canada; and
| | - Philippe Gros
- ‡Department of Biochemistry, McGill University, Montreal, Québec, Canada
| | - Luis F. Barrera
- *Grupo de Inmunología Celular e Inmunogenética, Laboratorio Central de Investigaciones, Centro de Investigaciones Médicas. Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia
| | - Luis F. García
- *Grupo de Inmunología Celular e Inmunogenética, Laboratorio Central de Investigaciones, Centro de Investigaciones Médicas. Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia
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30
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Carballo E, Gilkeson GS, Blackshear PJ. Bone marrow transplantation reproduces the tristetraprolin-deficiency syndrome in recombination activating gene-2 (-/-) mice. Evidence that monocyte/macrophage progenitors may be responsible for TNFalpha overproduction. J Clin Invest 1997; 100:986-95. [PMID: 9276715 PMCID: PMC508273 DOI: 10.1172/jci119649] [Citation(s) in RCA: 120] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Tristetraprolin-deficient [TTP (-/-)] mice exhibit a complex syndrome of myeloid hyperplasia, cachexia, dermatitis, autoimmunity, and erosive arthritis. Virtually the entire syndrome can be prevented by the repeated injection of anti-TNFalpha antibodies (Taylor, G.A., E. Carballo, D.M. Lee, W.S. Lai, M.J. Thompson, D.D. Patel, D.I. Schenkman, G.S. Gilkeson, H.E. Broxmeyer, B.F. Haynes, and P.J. Blackshear. 1996. Immunity. 4:445-454). In the present study, we transplanted bone marrow from TTP (-/-) and (+/+) mice into recombination activating gene-2 (-/-) mice. After a lag period of several months, marrow transplantation from the (-/-) but not the (+/+) mice resulted in the full syndrome associated with TTP deficiency, suggesting that hematopoietic progenitors are responsible for the development of the syndrome. Western blot analysis of supernatants from cultured TTP-deficient macrophages derived from the peritoneal cavity or bone marrow of adult TTP (-/-) mice, or from fetal liver, demonstrated an increased accumulation of TNFalpha after stimulation with LPS compared to control cells, and also increased accumulation of TNFalpha mRNA. This difference was not observed with cultured fibroblasts or T and B lymphocytes. These data suggest that macrophages are among the cells responsible for the effective excess of TNFalpha that leads to the pathology reported in TTP (-/-) animals, and that macrophage progenitors may be involved in the transplantability of this syndrome.
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Affiliation(s)
- E Carballo
- Howard Hughes Medical Institute Laboratory, Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA
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31
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Kubo M, Ransom J, Webb D, Hashimoto Y, Tada T, Nakayama T. T-cell subset-specific expression of the IL-4 gene is regulated by a silencer element and STAT6. EMBO J 1997; 16:4007-20. [PMID: 9233810 PMCID: PMC1170024 DOI: 10.1093/emboj/16.13.4007] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
During development of CD4+ T lymphocytes in the periphery, differential expression of cytokine genes, such as those of interleukin (IL)-2 and IL-4, occurs in distinct T-cell subsets. IL-4 is a cytokine produced by T-helper 2 (Th2) cells, and the IL-4 receptor (IL-4R)-mediated signaling pathway is thought to be required for commitment to the Th2 phenotype. However, the molecular basis for development of the Th subset-specific production of IL-4 remains unclear. We demonstrate here that the IL-4 promoter is functional in Th1 and B cells which do not normally form IL-4 transcripts as well as in IL-4-producing T cells. Based on studies of the effect of several different upstream and downstream regions of the IL-4 gene on IL-4 promoter activity, a Th1-specific IL-4 silencer element was identified in the 3'-untranslated region. The silencer region contained a consensus sequence for a transcriptional factor that is normally regulated by the IL-4 R signaling pathway, STAT6. Nuclear expression of STAT6 protein, which was shown to bind to the silencer region, was observed in Th2 cells but not in Th1 cells. Deletion of the STAT6-binding site from the silencer region and inhibition of STAT6 function resulted in the appearance of silencing function even in Th2 cells. These results provide evidence that the silencer element, and the binding of STAT6 to this element, play a permissive role in determining the commitment into Th2 phenotype.
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Affiliation(s)
- M Kubo
- Division of Immunobiology, Research Institute for Biological Sciences, Science University of Tokyo, Japan.
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32
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Ewulonu UK, Schimenti JC. Function of untranslated regions in the mouse spermatogenesis-specific gene Tcp10 evaluated in transgenic mice. DNA Cell Biol 1997; 16:645-51. [PMID: 9174169 DOI: 10.1089/dna.1997.16.645] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The mouse Tcp10 genes are transcribed exclusively in male germ cells and display multiple 5' and 3' untranslated variations generated by alternative splicing and polyadenylation signal usage. To investigate the possible role of untranslated sequences in the regulation of these genes, chimeric expression constructs with or without endogenous 5' and 3' untranslated sequences were generated and used to make transgenic mice. Analysis of these animals showed that the untranslated sequences have no effect on the transcription or translation of an attached lacZ reporter gene, thereby implying these sequences are dispensible. However, the endogenous pattern of polyadenylation site usage was altered when Tcp10 3' untranslated sequences were linked to lacZ, indicating that internal coding sequence can influence recognition of polyadenylation signals in testis. The characteristics of alternative splicing and polyadenylation signal variability reflects a common theme of promiscuity in testicular gene expression.
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Affiliation(s)
- U K Ewulonu
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
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33
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Sorokin SP, Hoyt RF, McNelly NA. Factors influencing fetal macrophage development: I. Reactions of the tumor necrosis factor-alpha cascade and their inhibitors. Anat Rec (Hoboken) 1996; 246:481-97. [PMID: 8955788 DOI: 10.1002/(sici)1097-0185(199612)246:4<481::aid-ar8>3.0.co;2-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND When fetal rat lungs are explanted to organ culture, precursor angular cells soon convert to nascent macrophages that multiply rapidly as they mature into efficient phagocytes. The present study examines the influence of proinflammatory early cytokines of the tumor necrosis factor-alpha (TNF alpha) cascade on this initial expression of the macrophage phenotype. METHODS Fourteen- and 15-day fetal rat lungs were grown for varying periods on an agar-solidified medium with and without test factors added singly or in combination. Growth of the macrophage population was followed daily by light microscopy and quantified by measuring the area of coronas formed as cells emerged from explants. RESULTS TNF alpha interleukin-1 beta (IL-1 beta) stimulated growth of the macrophage population, as had macrophage- and granulocyte-macrophage colony-stimulating factors (M- and GM-CSFs) in prior studies. Inhibition was obtained by exposure to IL-1 receptor antagonist and antibodies neutralizing the CSFs. Only the effects of TNF alpha were sufficiently delayed to discount possible influence on conversion and growth of nascent macrophages. Two transcription blockers, dexamethasone and pyrrolidine dithiocarbamate (PDTC), an inhibitor of nuclear factor NF-kappa B, both profoundly suppressed macrophage growth without preventing conversion of precursors. Effects of dexamethasone were significantly ameliorated by IL-1 beta alone and combined with GM-CSF; those of PDTC were mitigated by M-CSF and a combination of IL-1 beta and TNF alpha but not by GM-CSF. CONCLUSIONS IL-1 beta, M-CSF, and GM-CSF all promote growth of the young macrophage population. TNF alpha is effective only later on, likely because early-stage cells lack its receptors which normally use intracellular signalling pathways similar to those for IL-1. The severity of PDTC inhibition to population growth indicates that NF-kappa B is important for transmitting proliferative signals in these cells.
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Affiliation(s)
- S P Sorokin
- Department of Anatomy and Neurobiology, Boston, University School of Medicine, MA 02118-2394, USA
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34
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Hel Z, Skamene E, Radzioch D. Two distinct regions in the 3' untranslated region of tumor necrosis factor alpha mRNA form complexes with macrophage proteins. Mol Cell Biol 1996; 16:5579-90. [PMID: 8816470 PMCID: PMC231557 DOI: 10.1128/mcb.16.10.5579] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The production of tumor necrosis factor alpha (TNF-alpha), a key proinflammatory cytokine essential for the function of the immune system, is regulated at both the transcriptional and posttranscriptional levels. In this report, we focus on the interaction of TNF-alpha mRNA with macrophage proteins, likely mediators of its post-transcriptional control. Mapping of murine TNF-alpha mRNA by using a combination of RNase protection and RNA gel shift assays revealed that two distinct sites within the 3' untranslated region (3'-UTR) engage in the formation of four major RNA-protein complexes, while no protein binding to the 5'-UTR or coding sequences was detected. The protein-binding site of three RNA-protein complexes, A, B, and C, is positioned between bases 1291 and 1320 inside the AU-rich sequence, a region previously shown to be crucial for both translational repression and lipopolysaccharide inducibility of TNF-alpha. An additional protein complex (complex D) whose binding to the TNF-alpha 3'-UTR was independent of the presence of AU-rich sequences was identified. At least six protein species with apparent molecular masses of 48, 52, 54, 81, 101, and 150 kDa are in direct contact with TNF-alpha mRNA. The RNA-binding proteins are differentially distributed in the cell: complexes A and D are present predominantly in the cytosol, while complexes B and C are found in the nucleus and associated with particulate cytoplasmic fractions. Cytosolic complex A displays comparatively high specificity for TNF-alpha mRNA, while the binding of complexes B and C to TNF-alpha mRNA is readily competed for by other AU-rich sequence-containing RNAs. In summary, these findings demonstrate that two regions of the TNF-alpha mRNA molecule interact with macrophage RNA-binding protein complexes that differ in their core protein composition, cellular distribution, and affinity to TNF-alpha mRNA.
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Affiliation(s)
- Z Hel
- Centre for the Study of Host Resistance, McGill University, Montreal, General Hospital Research Institute, Quebec, Canada
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35
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Engagement of Tumor Necrosis Factor mRNA by an Endotoxin-Inducible Cytoplasmic Protein. Mol Med 1996. [DOI: 10.1007/bf03401907] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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36
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Gueydan C, Houzet L, Marchant A, Sels A, Huez G, Kruys V. Engagement of tumor necrosis factor mRNA by an endotoxin-inducible cytoplasmic protein. Mol Med 1996; 2:479-88. [PMID: 8827718 PMCID: PMC2230167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Tumor necrosis factor (TNF) production by macrophages plays an important role in the host response to infection. TNF-alpha gene expression in RAW 264.7 macrophages is predominantly regulated at the translational level. A key element in this regulation is an AU-rich (AUR) sequence located in the 3' untranslated region (UTR) of TNF mRNA. In unstimulated macrophages, the translation of TNF mRNA is inhibited via this AUR sequence. Upon stimulation with LPS, this repression is overcome and translation occurs. In this study, we attempted to identify cellular proteins that interact with the AUR sequence and thereby regulate TNF mRNA translation. MATERIALS AND METHODS RNA probes corresponding to portions of TNF mRNA 3' UTR were synthesized. These labeled RNAs were incubated with cytoplasmic extracts of either unstimulated or lipopolysaccharides (LPS)-stimulated RAW 264.7 macrophages. The RNA/protein complexes formed were analyzed by gel retardation. Ultraviolet (UV) cross-linking experiments were performed to determine the molecular weight of the proteins involved in the complexes. RESULTS TNF mRNA AUR sequence formed two complexes (1 and 2) of distinct electrophoretic mobilities. While the formation of complex 1 was independent of the activation state of the macrophages from which the extracts were obtained, complex 2 was detected only using cytoplasmic extracts from LPS-stimulated macrophages. Upon UV cross-linking, two proteins, of 50 and 80 kD, respectively, were capable of binding the UAR sequence. The 50-kD protein is likely to be part of the LPS-inducible complex 2, since its binding ability was enhanced upon LPS stimulation. Interestingly, complex 2 formation was also triggered by Sendaï virus infection, another potent activator of TNF mRNA translation in RAW 264.7 macrophages. In contrast, complex 2 was not detected with cytoplasmic extracts obtained from B and T cell lines which are unable to produce TNF in response to LPS. Protein tyrosine phosphorylation is required for LPS-induced TNF mRNA translation. Remarkably, the protein tyrosine phosphorylation inhibitor herbimycin A abolished LPS-induced complex 2 formation. Complex 2 was already detectable after 0.5 hr of LPS treatment and was triggered by a minimal LPS dose of 10 pg/ml. CONCLUSIONS The tight correlation between TNF production and the formation of an LPS-inducible cytoplasmic complex suggests that this complex plays a role in the translational regulation of TNF mRNA.
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Affiliation(s)
- C Gueydan
- Département de Biologie Moléculaire, Université Libre de Bruxelles, Belgium
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37
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Williams LM, Gibbons DL, Gearing A, Maini RN, Feldmann M, Brennan FM. Paradoxical effects of a synthetic metalloproteinase inhibitor that blocks both p55 and p75 TNF receptor shedding and TNF alpha processing in RA synovial membrane cell cultures. J Clin Invest 1996; 97:2833-41. [PMID: 8675695 PMCID: PMC507377 DOI: 10.1172/jci118739] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
We have previously hypothesized that the pro-inflammatory cytokine TNF alpha has a pivotal role in the pathogenesis of rheumatoid arthritis (RA). It mediates its effects by cross-linking surface p55 TNF receptors (TNF-R), which can be proteolytically cleaved to yield soluble fragments. Upon binding TNF alpha soluble TNF-R (sTNF-R) can inhibit its function. We investigated the enzymatic nature of the proteases involved in TNF-R cleavage, and found that this process is blocked by a synthetic inhibitor of matrix metallo-proteinase activity (MMP), BB-2275. Inhibition of TNF-R cleavage was observed in a number of different cell types, as detected by retention of surface bound TNF receptor and by less sTNF-R released into the cell supernatant. The augmentation of surface TNF-R expression was of biological relevance as TNF alpha-mediated necrosis of human KYM.1D4 rhabdosarcoma cells was enhanced approximately 15-fold in the presence of BB-2275. The addition of BB-2275 to rheumatoid synovial membrane cell cultures totally inhibited MMP activity and also significantly reduced the levels of soluble TNF alpha (P < 0.006), p55 sTNF-R (P < 0.006), and p75 sTNF-R (P < 0.004). Paradoxically, despite the reduction in soluble TNF alpha levels, the production of IL-1 beta, IL-6, and IL-8, cytokines whose production was previously demonstrated to be inhibited by the addition of neutralizing anti-TNF alpha antibody were not down-regulated by BB-2275. These results raise the interesting possibility that a close relationship exits between the enzyme(s) which process membrane-bound TNF alpha, and those involved in surface TNF-R cleavage. Furthermore our observations suggest that hydroxamate inhibitors of MMP activity which block TNF alpha secretion and TNF-R cleavage may not modulate down-stream effects of TNA alpha, and as such suggest that the precise specificity of these compounds will be highly relevant to their clinical efficacy in inflammatory diseases.
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Affiliation(s)
- L M Williams
- Mathilda and Terence Kennedy Institute of Rheumatology, Sunley Division, Hammersmith, London, United Kingdom
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38
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Raingeaud J, Whitmarsh AJ, Barrett T, Dérijard B, Davis RJ. MKK3- and MKK6-regulated gene expression is mediated by the p38 mitogen-activated protein kinase signal transduction pathway. Mol Cell Biol 1996; 16:1247-55. [PMID: 8622669 PMCID: PMC231107 DOI: 10.1128/mcb.16.3.1247] [Citation(s) in RCA: 1060] [Impact Index Per Article: 37.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The p38 mitogen-activated protein (MAP) kinase signal transduction pathway is activated by proinflammatory cytokines and environmental stress. The detection of p38 MAP kinase in the nucleus of activated cells suggests that p38 MAP kinase can mediate signaling to the nucleus. To test this hypothesis, we constructed expression vectors for activated MKK3 and MKK6, two MAP kinase kinases that phosphorylate and activate p38 MAP kinase. Expression of activated MKK3 and MKK6 in cultured cells caused a selective increase in p38 MAP kinase activity. Cotransfection experiments demonstrated that p38 MAP kinase activation causes increased reporter gene expression mediated by the transcription factors ATF2 and Elk-1. These data demonstrate that the nucleus is one target of the p38 MAP kinase signal transduction pathway.
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Affiliation(s)
- J Raingeaud
- Howard Hughes Medical Institute and Program in Molecular Medicine, University of Massachusetts Medical School, Worcester 01605 USA
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39
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Li YP, Chen W, Stashenko P. Characterization of a silencer element in the first exon of the human osteocalcin gene. Nucleic Acids Res 1995; 23:5064-72. [PMID: 8559666 PMCID: PMC307514 DOI: 10.1093/nar/23.24.5064] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Osteocalcin, the major non-collagenous protein in bone, is transcribed in osteoblasts at the onset of extracellular matrix mineralization. In this study it was demonstrated that sequences located in the first exon of the human osteocalcin gene possess a differentiation-related osteocalcin silencer element (OSE). Osteocalcin was rendered transcribable in UMR-106 cells and proliferating normal osteoblasts after deletion of the -3 to +51 region. Site-specific mutagenesis of this region revealed that a 7 bp sequence (TGGCCCT) (+29 to +35) is critical for silencing function. Mobility shift assays demonstrated that a nuclear factor bound to the OSE. The OSE binding protein was present in proliferating normal pre-osteoblasts and in UMR-106 and ROS 17/2.8 osteosarcoma cells, but was absent from post-proliferative normal osteoblasts. The binding protein was inhibited by fragments containing the +29/+35 sequence, but not by other promoter fragments or by the consensus oligomers of unrelated nuclear factors AP-1 and Sp1. DNase 1 footprinting demonstrated that the OSE binding-protein protected the +17 to +36 portion of the first exon, consistent with the results of mapping studies and competitive mobility shift assays. It is hypothesized that this silencer is activated by complexing of the OSE binding protein to the OSE during the osteoblast proliferation stage and that the OSE binding protein is down-regulated at the onset of extracellular matrix mineralization.
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Affiliation(s)
- Y P Li
- Department of Cytokine Biology, Forsyth Dental Center, Boston, MA 02115, USA
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40
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Miyazaki Y, Araki K, Vesin C, Garcia I, Kapanci Y, Whitsett JA, Piguet PF, Vassalli P. Expression of a tumor necrosis factor-alpha transgene in murine lung causes lymphocytic and fibrosing alveolitis. A mouse model of progressive pulmonary fibrosis. J Clin Invest 1995; 96:250-9. [PMID: 7542280 PMCID: PMC185196 DOI: 10.1172/jci118029] [Citation(s) in RCA: 290] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The murine TNF-alpha gene was expressed under the control of the human surfactant protein SP-C promoter in transgenic mice. A number of the SP-C TNF-alpha mice died at birth or after a few weeks with very severe lung lesions. Surviving mice transmitted a pulmonary disease to their offspring, the severity and evolution of which was related to the level of TNF-alpha mRNA in the lung; TNF-alpha RNA was detected in alveolar epithelium, presumably in type II epithelial cells. In a longitudinal study of two independent mouse lines, pulmonary pathology, at 1-2 mo of age, consisted of a leukocytic alveolitis with a predominance of T lymphocytes. Leukocyte infiltration was associated with endothelial changes and increased levels of mRNA for the endothelial adhesion molecule VCAM-1. In the following months, alveolar spaces enlarged in association with thickening of the alveolar walls due to an accumulation of desmin-containing fibroblasts, collagen fibers, and lymphocytes. Alveolar surfaces were lined by regenerating type II epithelial cells, and alveolar spaces contained desquamating epithelial cells in places. Platelet trapping in the damaged alveolar capillaries was observed. Pulmonary pathology in the SP-C TNF-alpha mice bears a striking resemblance to human idiopathic pulmonary fibrosis, in which increased expression of TNF-alpha in type II epithelial cells has also been noted. These mice provide a valuable animal model for understanding the pathogenesis of pulmonary fibrosis and exploring possible therapeutic approaches.
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Affiliation(s)
- Y Miyazaki
- Department of Pathology, University of Geneva, Switzerland
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41
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Lee JC, Laydon JT, McDonnell PC, Gallagher TF, Kumar S, Green D, McNulty D, Blumenthal MJ, Heys JR, Landvatter SW, Strickler JE, McLaughlin MM, Siemens IR, Fisher SM, Livi GP, White JR, Adams JL, Young PR. A protein kinase involved in the regulation of inflammatory cytokine biosynthesis. Nature 1994; 372:739-46. [PMID: 7997261 DOI: 10.1038/372739a0] [Citation(s) in RCA: 2645] [Impact Index Per Article: 88.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Production of interleukin-1 and tumour necrosis factor from stimulated human monocytes is inhibited by a new series of pyridinyl-imidazole compounds. Using radiolabelled and radio-photoaffinity-labelled chemical probes, the target of these compounds was identified as a pair of closely related mitogen-activated protein kinase homologues, termed CSBPs. Binding of the pyridinyl-imidazole compounds inhibited CSBP kinase activity and could be directly correlated with their ability to inhibit cytokine production, suggesting that the CSBPs are critical for cytokine production.
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Affiliation(s)
- J C Lee
- Department of Cellular Biochemistry, SmithKline Beecham Pharmaceuticals, King of Prussia, Pennsylvania 19406
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42
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Savici D, He B, Geist LJ, Monick MM, Hunninghake GW. Silica increases tumor necrosis factor (TNF) production, in part, by upregulating the TNF promoter. Exp Lung Res 1994; 20:613-25. [PMID: 7882909 DOI: 10.3109/01902149409031740] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Silica causes release of tumor necrosis factor (TNF) from mononuclear phagocytes. One hypothesis is that silica increases TNF production, in part, by upregulating the TNF gene. To evaluate this hypothesis, THP-1 cells (a myelomonocytic cell line) were exposed to various amounts of silica and then the TNF gene transcription was evaluated. In this study silica caused a dose-dependent increase in TNF mRNA and the peak response occurred at 3 h following stimulation. A transient transfection assay also showed that silica upregulated expression of a TNF CAT construct in THP-1 cells. Furthermore, a nuclear run-on assay demonstrated that silica particles induce increased TNF gene transcription in exposed cells. THP-1 cells cultured for various periods of time in the presence of silica released TNF into the cell supernatants. These studies show that silica can upregulate the TNF gene, which results in the release of TNF protein from the cells.
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Affiliation(s)
- D Savici
- Department of Medicine, Veterans Affairs Center, Iowa City, Iowa
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43
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Liu T, Clark RK, McDonnell PC, Young PR, White RF, Barone FC, Feuerstein GZ. Tumor necrosis factor-alpha expression in ischemic neurons. Stroke 1994; 25:1481-8. [PMID: 8023366 DOI: 10.1161/01.str.25.7.1481] [Citation(s) in RCA: 614] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
BACKGROUND AND PURPOSE Tumor necrosis factor-alpha (TNF-alpha) is a cytokine with diverse proinflammatory actions, including endothelial leukocyte adhesion molecule expression. Since leukocytes infiltrate into ischemic brain lesions, the present study was conducted to examine whether TNF-alpha messenger RNA (mRNA) and peptide are expressed in the brain after experimental focal stroke and before leukocyte accumulation. METHODS TNF-alpha mRNA and protein expression were monitored in the ischemic and nonischemic cerebral cortex of rats after focal ischemia produced by permanent middle cerebral artery occlusion. The effect of TNF-alpha administered by microinjection into the brain cortex on leukocyte adherence to brain capillaries was also studied. RESULTS Induction of TNF-alpha mRNA, normalized to a standard reference rat macrophage TNF-alpha mRNA, was detected as early as 1 hour after middle cerebral artery occlusion. TNF-alpha mRNA was elevated by 3 hours (29 +/- 6% versus 2 +/- 1% in sham-operated rats) only in the ischemic cortex, with peak expression at 12 hours (104 +/- 8%; P < .01). Five days after middle cerebral artery occlusion, TNF-alpha mRNA levels in ischemic cortex were still significantly elevated (38 +/- 5%; P < .05). Also, TNF-alpha mRNA expression was greater in the ischemic cortex of spontaneously hypertensive rats than in normotensive rats (P < .05). Double-labeling, immunohistochemical studies revealed the presence of TNF-alpha protein localized within nerve fibers in the evolving infarct at 6 and 12 hours after ischemia and further expression in the tissues immediately adjacent to the infarct 24 hours after ischemia. After 5 days, the neuronally localized peptide had diminished greatly, but macrophages located within the infarcted tissues were immunoreactive. Cortical microinjections of TNF-alpha (10 ng in 1 microL) produced a significant neutrophil adherence/accumulation in capillaries and small blood vessels 24 hours later. CONCLUSIONS These results represent the first demonstration that focal cerebral ischemia in rats results in elevated TNF-alpha mRNA and protein in ischemic neurons. The neuronal expression of peptide appears to facilitate the infiltration of inflammatory cells that can further exacerbate tissue damage in cerebral ischemia and might contribute to increased sensitivity and risk in focal stroke.
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Affiliation(s)
- T Liu
- Department of Cardiovascular Pharmacology, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406
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44
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Spirin AS. Storage of messenger RNA in eukaryotes: envelopment with protein, translational barrier at 5' side, or conformational masking by 3' side? Mol Reprod Dev 1994; 38:107-17. [PMID: 7914085 DOI: 10.1002/mrd.1080380117] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Messenger RNA can be stored in the cytoplasm of higher Eukaryotes in the form of masked messenger ribonucleoprotein particles (masked mRNPs, or informosomes). The typical example is the storage of mRNPs in germ cells (oocytes and spermatocytes). The masked mRNPs are inactive in translation, stable, i.e., protected against degradation, and unavailable for poly(A) tail processing, such as cytoplasmic polyadenylation and deadenylation. The major nonspecific mRNA-binding protein forming mRNPs and belonging to a special p50 family of basic, glycine-rich, phosphorylatable proteins seems to be necessary, but not sufficient for the masking. In some cases, mRNA-specific repressor proteins bound to the 5'-untranslated regions (5'-UTR) of mRNAs may be involved. Interactions of the 3'-untranslated regions (3'-UTR) with sequence-specific proteins seem to be of decisive importance for the masking of mRNPs. The hypothesis is proposed that the masking is achieved through a 3'-UTR-induced conformational rearrangement of mRNP; closing into a circle and condensation of mRNP are considered plausible.
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Affiliation(s)
- A S Spirin
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region
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45
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González-Amaro R, García-Monzón C, García-Buey L, Moreno-Otero R, Alonso JL, Yagüe E, Pivel JP, López-Cabrera M, Fernández-Ruiz E, Sánchez-Madrid F. Induction of tumor necrosis factor alpha production by human hepatocytes in chronic viral hepatitis. J Exp Med 1994; 179:841-8. [PMID: 7509363 PMCID: PMC2191405 DOI: 10.1084/jem.179.3.841] [Citation(s) in RCA: 223] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Tumor necrosis factor alpha (TNF-alpha) is a multifunctional cytokine that has an important role in the pathogenesis of inflammation, cachexia, and septic shock. Although TNF-alpha is mainly produced by macrophages, there is evidence regarding TNF-alpha production by cells that are not derived from bone marrow. TNF-alpha production by normal and inflamed human liver was assessed at both mRNA and protein levels. Using a wide panel of novel anti-TNF-alpha monoclonal antibodies and a specific polyclonal antiserum, TNF-alpha immunoreactivity was found in hepatocytes from patients chronically infected with either hepatitis B virus (HBV) or hepatitis C virus. Minimal TNF-alpha immunoreactivity was detected in the mononuclear cell infiltrate and Kupffer cells. In situ hybridization experiments using a TNF-alpha RNA probe showed a significant expression of TNF-alpha mRNA in hepatocytes, Kupffer cells, and some infiltrating mononuclear cells. By contrast, TNF-alpha was detected at low levels in liver biopsies from normal individuals or patients with alcoholic liver disease and low expression of TNF-alpha mRNA was observed in these specimens. Transfection of HepG2 hepatoblastoma cells with either HBV genome or HBV X gene resulted in induction of TNF-alpha expression. Our results demonstrate that viral infection induces, both in vivo and in vitro, TNF-alpha production in hepatocytes, and indicate that the HBV X protein may regulate the expression of this cytokine. These findings suggest that TNF-alpha may have an important role in human liver diseases induced by viruses.
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Affiliation(s)
- R González-Amaro
- Sección de Inmunología, Hospital de la Princesa, Universidad Autónoma de Madrid, Spain
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Kruys V, Thompson P, Beutler B. Extinction of the tumor necrosis factor locus, and of genes encoding the lipopolysaccharide signaling pathway. J Exp Med 1993; 177:1383-90. [PMID: 8478613 PMCID: PMC2190998 DOI: 10.1084/jem.177.5.1383] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The tumor necrosis factor (TNF-alpha or TNF) gene is activated by both lipopolysaccharide (LPS) and cycloheximide in RAW 264.7 macrophages, whereas neither stimulus activates the gene in 3T3 fibroblasts. Moreover, the pattern of CG methylation within the TNF gene is readily distinguishable in DNA derived from cells of these two types. These findings would suggest that the TNF gene has been rendered inaccessible to transcription in the 3T3 cell environment. When RAW 264.7 cells are fused with 3T3 cells, an immortal pentaploid hybrid results. In the hybrid cell, all three TNF genes contributed by the RAW 264.7 cell parent become highly methylated according to the pattern observed in the 3T3 cell parent. Permanently transfected chloramphenicol acetyl transferase (CAT) reporter constructs, bearing 2.2 kb of upstream sequence (including the entire TNF promoter and 5'-untranslated region [UTR]) as well as 1.0 kb of downstream sequence (including the entire TNF 3'-UTR and termination sequence), are accessible in both RAW 264.7 cells and 3T3 cells, but are silenced in transition from the RAW 264.7 cell to the hybrid cell environment. Moreover, the endotoxin signaling pathway is abrogated, as assessed by transient transfection of hybrid cells with LPS-responsive CAT reporter constructs. It would therefore appear that the fusion of 3T3 cells and RAW 264.7 cells activates a system that silences the TNF gene, as well as the LPS signaling pathway. This system may operate to determine TNF gene accessibility and LPS responsiveness in the course of cell differentiation. The DNA sequences targeted within the TNF gene are included in the CAT reporter construct; therefore, the silencing element has been circumscribed to a region of DNA 3.2 kb in length.
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Affiliation(s)
- V Kruys
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas 75235
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47
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Naylor MS, Stamp GW, Foulkes WD, Eccles D, Balkwill FR. Tumor necrosis factor and its receptors in human ovarian cancer. Potential role in disease progression. J Clin Invest 1993; 91:2194-206. [PMID: 8387543 PMCID: PMC288222 DOI: 10.1172/jci116446] [Citation(s) in RCA: 180] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The gene for tumor necrosis factor, TNF, was expressed in 45 out of 63 biopsies of human epithelial ovarian cancer. In serous tumors, there was a positive correlation between level of TNF expression and tumor grade. TNF mRNA was found in epithelial tumor cells and infiltrating macrophages, whereas TNF protein localized primarily to a subpopulation of macrophages within and in close proximity to tumor areas. mRNA and protein for the p55 TNF receptor gene localized to the tumor epithelium and tumor, but not to stromal macrophages. The p75 TNF receptor was confined to infiltrating cells. Cells expressing TNF mRNA were also found in ovarian cancer ascites and TNF protein was detected in some ascitic fluids. In 2 out of 12 biopsies of normal ovary, TNF mRNA was detected in a minority of cells in the thecal layer of the corpus luteum. Serum levels of TNF and its soluble receptor did not correlate with extent of TNF expression in matched biopsies. Northern and Southern analysis revealed no gross abnormality of the TNF gene. The coexpression of TNF and its receptor in ovarian cancer biopsies suggests the capacity for autocrine/paracrine action. TNF antagonists may have therapeutic potential in this malignancy.
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MESH Headings
- Antisense Elements (Genetics)
- Biomarkers, Tumor/analysis
- Biomarkers, Tumor/blood
- DNA, Neoplasm/genetics
- DNA, Neoplasm/isolation & purification
- Female
- Gene Expression
- Humans
- In Situ Hybridization
- Ovarian Neoplasms/genetics
- Ovarian Neoplasms/metabolism
- Ovarian Neoplasms/pathology
- Ovarian Neoplasms/physiopathology
- RNA, Messenger/analysis
- RNA, Messenger/genetics
- RNA, Neoplasm/analysis
- Radioimmunoassay
- Receptors, Cell Surface/analysis
- Receptors, Cell Surface/genetics
- Receptors, Tumor Necrosis Factor
- Tumor Cells, Cultured
- Tumor Necrosis Factor-alpha/analysis
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Affiliation(s)
- M S Naylor
- Biological Therapy Laboratory, Imperial Cancer Research Fund, London, England
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48
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Higuchi Y, Herrera P, Muniesa P, Huarte J, Belin D, Ohashi P, Aichele P, Orci L, Vassalli JD, Vassalli P. Expression of a tumor necrosis factor alpha transgene in murine pancreatic beta cells results in severe and permanent insulitis without evolution towards diabetes. J Exp Med 1992; 176:1719-31. [PMID: 1460428 PMCID: PMC2119473 DOI: 10.1084/jem.176.6.1719] [Citation(s) in RCA: 117] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Mice bearing a tumor necrosis factor (TNF) alpha transgene controlled by an insulin promoter developed an increasingly severe lymphocytic insulitis, apparently resulting from the induction of endothelial changes with features similar to those observed in other places of intense lymphocytic traffic. This was accompanied by dissociation of the endocrine tissue (without marked decrease in its total mass), islet fibrosis, and the development of intraislet ductules containing, by places, beta cells in their walls, suggesting a regenerative capacity. Islet disorganization and fibrosis did not result from lymphocytic infiltration, since they were also observed in SCID mice bearing the transgene. Diabetes never developed, even though a number of potentially inducing conditions were used, including the prolonged perfusion of interferon gamma and the permanent expression of a nontolerogenic viral protein on beta cells (obtained by using mice bearing two transgenes). It is concluded that (a) a slow process of TNF release in pancreatic islets induces insulitis, and may be instrumental in the insulitis resulting from local cell-mediated immune reactions, but (b) that insulitis per se is not diabetogenic, lymphocyte stimulation by cells other than beta cells being necessary to trigger extensive beta cell damage. This provides an explanation for the discrepancy between the occurrence of insulitis and that of clinical disease in autoimmune diabetes.
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Affiliation(s)
- Y Higuchi
- Department of Pathology, University of Geneva, Switzerland
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49
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cis-acting elements involved in the alternative translation initiation process of human basic fibroblast growth factor mRNA. Mol Cell Biol 1992. [PMID: 1406661 DOI: 10.1128/mcb.12.10.4796] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Four forms of basic fibroblast growth factor (bFGF) are synthesized from the same mRNA, resulting from alternative initiations of translation at three CUG start codons and one AUG start codon. The CUG- and AUG-initiated forms have distinct intracellular localizations and can modify cell phenotypes differently, indicating that control of the alternative expression of the different forms of bFGF has an important impact on the cell. In this study, we investigated the roles of the mRNA 5' untranslated region and the alternatively translated region located between the CUG and AUG codons in the regulation of alternative translation of the different forms of bFGF. Deletions and site-directed mutagenesis were carried out in bFGF mRNA leader, and translation was studied in vitro and in vivo. The results enabled us to identify five cis-acting RNA elements (two in the 5' untranslated region and three in the alternatively translated region) involved in the regulation of either global or alternative initiation of translation. Each of these elements had a specific effect on the level of synthesis of the different forms of bFGF. Furthermore, we showed that the 5' untranslated region regulatory elements had different effects on bFGF translation, depending on the translation system used. These results suggest that bFGF translation is modulated by cis-acting elements corresponding to secondary or tertiary RNA structures, which could be the targets of cell-specific trans-acting factors.
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50
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Prats AC, Vagner S, Prats H, Amalric F. cis-acting elements involved in the alternative translation initiation process of human basic fibroblast growth factor mRNA. Mol Cell Biol 1992; 12:4796-805. [PMID: 1406661 PMCID: PMC360406 DOI: 10.1128/mcb.12.10.4796-4805.1992] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Four forms of basic fibroblast growth factor (bFGF) are synthesized from the same mRNA, resulting from alternative initiations of translation at three CUG start codons and one AUG start codon. The CUG- and AUG-initiated forms have distinct intracellular localizations and can modify cell phenotypes differently, indicating that control of the alternative expression of the different forms of bFGF has an important impact on the cell. In this study, we investigated the roles of the mRNA 5' untranslated region and the alternatively translated region located between the CUG and AUG codons in the regulation of alternative translation of the different forms of bFGF. Deletions and site-directed mutagenesis were carried out in bFGF mRNA leader, and translation was studied in vitro and in vivo. The results enabled us to identify five cis-acting RNA elements (two in the 5' untranslated region and three in the alternatively translated region) involved in the regulation of either global or alternative initiation of translation. Each of these elements had a specific effect on the level of synthesis of the different forms of bFGF. Furthermore, we showed that the 5' untranslated region regulatory elements had different effects on bFGF translation, depending on the translation system used. These results suggest that bFGF translation is modulated by cis-acting elements corresponding to secondary or tertiary RNA structures, which could be the targets of cell-specific trans-acting factors.
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Affiliation(s)
- A C Prats
- Laboratoire de Biologie Moléculaire Eucaryote du Centre National de la Recherche Scientifique, Toulouse, France
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