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Suswam EA, Shacka JJ, Walker K, Lu L, Li X, Si Y, Zhang X, Zheng L, Nabors LB, Cao H, King PH. Mutant tristetraprolin: a potent inhibitor of malignant glioma cell growth. J Neurooncol 2013; 113:195-205. [PMID: 23525947 DOI: 10.1007/s11060-013-1112-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Accepted: 03/12/2013] [Indexed: 02/02/2023]
Abstract
Malignant gliomas rely on the production of certain critical growth factors including VEGF, interleukin (IL)-6 and IL-8, to fuel rapid tumor growth, angiogenesis, and treatment resistance. Post-transcriptional regulation through adenine and uridine-rich elements of the 3' untranslated region is one mechanism for upregulating these and other growth factors. In glioma cells, we have shown that the post-transcriptional machinery is optimized for growth factor upregulation secondary to overexpression of the mRNA stabilizer, HuR. The negative regulator, tristetraprolin (TTP), on the other hand, may be suppressed because of extensive phosphorylation. Here we test that possibility by analyzing the phenotypic effects of a mutated form of TTP (mt-TTP) in which 8 phosphoserine residues were converted to alanines. We observed a significantly enhanced negative effect on growth factor expression in glioma cells at the post-transcriptional and transcriptional levels. The protein became stabilized and displayed significantly increased antiproliferative effects compared to wild-type TTP. Macroautophagy was induced with both forms of TTP, but inhibition of autophagy did not affect cell viability. We conclude that glioma cells suppress TTP function through phosphorylation of critical serine residues which in turn contributes to growth factor upregulation and tumor progression.
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Affiliation(s)
- Esther A Suswam
- Department of Neurology, University of Alabama at Birmingham, Birmingham, AL 35294-3300, USA.
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The fate of the messenger is pre-determined: a new model for regulation of gene expression. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:643-53. [PMID: 23337853 DOI: 10.1016/j.bbagrm.2013.01.004] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Revised: 01/07/2013] [Accepted: 01/08/2013] [Indexed: 02/08/2023]
Abstract
Recent years have seen a rise in publications demonstrating coupling between transcription and mRNA decay. This coupling most often accompanies cellular processes that involve transitions in gene expression patterns, for example during mitotic division and cellular differentiation and in response to cellular stress. Transcription can affect the mRNA fate by multiple mechanisms. The most novel finding is the process of co-transcriptional imprinting of mRNAs with proteins, which in turn regulate cytoplasmic mRNA stability. Transcription therefore is not only a catalyst of mRNA synthesis but also provides a platform that enables imprinting, which coordinates between transcription and mRNA decay. Here we present an overview of the literature, which provides the evidence of coupling between transcription and decay, review the mechanisms and regulators by which the two processes are coupled, discuss why such coupling is beneficial and present a new model for regulation of gene expression. This article is part of a Special Issue entitled: RNA Decay mechanisms.
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53
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Chen YL, Jiang YW, Su YL, Lee SC, Chang MS, Chang CJ. Transcriptional regulation of tristetraprolin by NF-κB signaling in LPS-stimulated macrophages. Mol Biol Rep 2012; 40:2867-77. [PMID: 23212617 DOI: 10.1007/s11033-012-2302-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 11/19/2012] [Indexed: 01/11/2023]
Affiliation(s)
- Yu-Ling Chen
- Graduate Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, Taiwan
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54
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Maleki S, Björck HM, Folkersen L, Nilsson R, Renner J, Caidahl K, Franco-Cereceda A, Länne T, Eriksson P. Identification of a novel flow-mediated gene expression signature in patients with bicuspid aortic valve. J Mol Med (Berl) 2012; 91:129-39. [PMID: 22903503 PMCID: PMC3536974 DOI: 10.1007/s00109-012-0942-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Revised: 06/18/2012] [Accepted: 08/02/2012] [Indexed: 12/22/2022]
Abstract
Individuals with bicuspid aortic valve (BAV) are at significantly higher risk of developing serious aortic complications than individuals with tricuspid aortic valves (TAV). Studies have indicated an altered aortic blood flow in patients with BAV; however, the extent to which altered flow influences the pathological state of BAV aorta is unclear. In the present study, we dissected flow-mediated aortic gene expression in patients undergoing elective open heart surgery. A large collection of public microarray data sets were firstly screened for consistent co-expression with five well-characterized flow-regulated genes (query genes). Genes with co-expression probability of >0.5 were selected and further analysed in expression profiles (127 arrays) from ascending aorta of BAV and TAV patients. Forty-four genes satisfied two filtering criteria: a significant correlation with one or more of the query genes (R > 0.40) and differential expression between patients with BAV and TAV. No gene fulfilled the criteria in mammary artery (88 arrays), an artery not in direct contact with the valve. Fifty-five percent of the genes significantly altered between BAV and TAV patients showed differential expression between two identified flow regions in the rat aorta. A large proportion of the identified genes were related to angiogenesis and/or wound healing, with pro-angiogenesis genes downregulated and inhibitory genes upregulated in patients with BAV. Moreover, differential expression of ZFP36, GRP116 and PKD2 was confirmed using immunohistochemistry. Implementing a new strategy, we have demonstrated an angiostatic gene expression signature in patients with BAV, indicating impaired wound healing in these patients, potentially involved in BAV-associated aortopathy.
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Affiliation(s)
- Shohreh Maleki
- Atherosclerosis Research Unit, Center for Molecular Medicine, Department of Medicine, Karolinska Institutet, Stockholm, Sweden.
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55
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Selmi T, Martello A, Vignudelli T, Ferrari E, Grande A, Gemelli C, Salomoni P, Ferrari S, Zanocco-Marani T. ZFP36 expression impairs glioblastoma cell lines viability and invasiveness by targeting multiple signal transduction pathways. Cell Cycle 2012; 11:1977-87. [PMID: 22544323 DOI: 10.4161/cc.20309] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
RNA binding proteins belonging to the TIS11/TTP gene family regulate the stability of multiple targets. Their inactivation or deregulated expression has recently been related to cancer, and it has been suggested that they are capable of displaying tumor suppressor activities. Here we describe three new targets of ZFP36 (PIM-1, PIM-3 and XIAP) and show by different approaches that its ectopic expression is capable of impairing glioblastoma cell lines viability and invasiveness by interfering with different transduction pathways. Moreover, we provide evidence that compounds capable of inducing the expression of TIS11/TTP genes determine a comparable biological effect on the same cell contexts.
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Affiliation(s)
- Tommaso Selmi
- Dipartimento di Scienze Biomediche, Sezione di Chimica Biologica, Università di Modena e Reggio Emilia, Modena, Italy
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Sanduja S, Blanco FF, Dixon DA. The roles of TTP and BRF proteins in regulated mRNA decay. WILEY INTERDISCIPLINARY REVIEWS-RNA 2012; 2:42-57. [PMID: 21278925 DOI: 10.1002/wrna.28] [Citation(s) in RCA: 126] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Adenylate- and uridylate-rich element (ARE) motifs are cis-acting elements present in the 3′ untranslated region of mRNA transcripts that encode many inflammation- and cancer-associated genes. The TIS11 family of RNA-binding proteins, composed of tristetraprolin (TTP) and butyrate response factors 1 and 2 (BRF-1 and -2), plays a critical role in regulating the expression of ARE-containing mRNAs. Through their ability to bind and target ARE-containing mRNAs for rapid degradation, this class of RNA-binding proteins serves a fundamental role in limiting the expression of a number of critical genes, thereby exerting anti-inflammatory and anti-cancer effects. Regulation of TIS11 family members occurs on a number of levels through cellular signaling events to control their transcription, mRNA turnover, phosphorylation status, cellular localization, association with other proteins, and proteosomal degradation, all of which impact TIS11 members' ability to promote ARE-mediated mRNA decay along with decay-independent functions. This review summarizes our current understanding of posttranscriptional regulation of ARE-containing gene expression by TIS11 family members and discusses their role in maintaining normal physiological processes and the pathological consequences in their absence.
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Affiliation(s)
- Sandhya Sanduja
- Department of Biological Sciences and Cancer Research Center, University of South Carolina, Columbia, SC, USA
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57
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Jin WJ, Chen CF, Liao HY, Gong LL, Yuan XH, Zhao BB, Zhang D, Feng X, Liu JJ, Wang Y, Chen GF, Yan HP, He YW. Downregulation of the AU-rich RNA-binding protein ZFP36 in chronic HBV patients: implications for anti-inflammatory therapy. PLoS One 2012; 7:e33356. [PMID: 22428029 PMCID: PMC3302862 DOI: 10.1371/journal.pone.0033356] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Accepted: 02/13/2012] [Indexed: 12/12/2022] Open
Abstract
Inflammation caused by chronic hepatitis B virus (HBV) infection is associated with the development of cirrhosis and hepatocellular carcinoma; however, the mechanisms by which HBV infection induces inflammation and inflammatory cytokine production remain largely unknown. We analyzed the gene expression patterns of lymphocytes from chronic HBV-infected patients and found that the expression of ZFP36, an AU-rich element (ARE)-binding protein, was dramatically reduced in CD4(+) and CD8(+) T lymphocytes from chronic HBV patients. ZFP36 expression was also reduced in CD14(+) monocytes and in total PBMCs from chronic HBV patients. To investigate the functional consequences of reduced ZFP36 expression, we knocked down ZFP36 in PBMCs from healthy donors using siRNA. siRNA-mediated silencing of ZFP36 resulted in dramatically increased expression of multiple inflammatory cytokines, most of which were also increased in the plasma of chronic HBV patients. Furthermore, we found that IL-8 and RANTES induced ZFP36 downregulation, and this effect was mediated through protein kinase C. Importantly, we found that HBsAg stimulated PBMCs to express IL-8 and RANTES, resulting in decreased ZFP36 expression. Our results suggest that an inflammatory feedback loop involving HBsAg, ZFP36, and inflammatory cytokines may play a critical role in the pathogenesis of chronic HBV and further indicate that ZFP36 may be an important target for anti-inflammatory therapy during chronic HBV infection.
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Affiliation(s)
- Wen-Jing Jin
- Key Laboratory of Systems Biology of Pathogens, Ministry of Health, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Dongcheng District, Beijing, China
| | - Cai-Feng Chen
- Key Laboratory of Systems Biology of Pathogens, Ministry of Health, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Dongcheng District, Beijing, China
| | - Hui-Yu Liao
- Center for Infection and Immunity, YouAn Hospital, The Beijing Capital Medical University, Beijing, China
| | - Lu-Lu Gong
- Key Laboratory of Systems Biology of Pathogens, Ministry of Health, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Dongcheng District, Beijing, China
| | - Xiao-Hui Yuan
- Key Laboratory of Systems Biology of Pathogens, Ministry of Health, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Dongcheng District, Beijing, China
| | - Bin-Bin Zhao
- Key Laboratory of Systems Biology of Pathogens, Ministry of Health, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Dongcheng District, Beijing, China
| | - Ding Zhang
- Key Laboratory of Systems Biology of Pathogens, Ministry of Health, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Dongcheng District, Beijing, China
| | - Xia Feng
- Center for Infection and Immunity, YouAn Hospital, The Beijing Capital Medical University, Beijing, China
| | - Jing-Jun Liu
- Key Laboratory of Systems Biology of Pathogens, Ministry of Health, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Dongcheng District, Beijing, China
| | - Yu Wang
- Department of Immunology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Guo-Feng Chen
- Fibrosis Noninvasive Diagnosis and Treatment Center, 302 Hospital, Beijing, China
| | - Hui-Ping Yan
- Center for Infection and Immunity, YouAn Hospital, The Beijing Capital Medical University, Beijing, China
| | - You-Wen He
- Key Laboratory of Systems Biology of Pathogens, Ministry of Health, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Dongcheng District, Beijing, China
- Department of Immunology, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail:
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58
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Ness GC, Edelman JL, Brooks PA. Involvement of tristetraprolin in transcriptional activation of hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase by insulin. Biochem Biophys Res Commun 2012; 420:178-82. [PMID: 22405826 DOI: 10.1016/j.bbrc.2012.02.138] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 02/24/2012] [Indexed: 11/28/2022]
Abstract
Several AU-rich RNA binding element (ARE) proteins were investigated for their possible effects on transcription of hepatic 3-hydroxy-3-methyglutaryl coenzyme A reductase (HMGR) in normal rats. Using in vivo electroporation, four different siRNAs to each ARE protein were introduced together with HMGR promoter (-325 to +20) luciferase construct and compared to saline controls. All four siRNAs to tristetraprolin (TTP) completely eliminated transcription from the HMGR promoter construct. Since insulin acts to rapidly increase hepatic HMGR transcription, the effect of TTP siRNA on induction by insulin was tested. The 3-fold stimulation by insulin was eliminated by this treatment. In comparison, siRNA to AU RNA binding protein/enoyl coenzyme A hydratase (AUH) had no effect. These findings indicate a role for TTP in the insulin-mediated activation of hepatic HMGR transcription.
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Affiliation(s)
- Gene C Ness
- Department of Molecular Medicine, College of Medicine, University of South Florida, Tampa, FL 33612, USA.
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59
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Nicotinic stimulation induces Tristetraprolin over-production and attenuates inflammation in muscle. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:368-78. [DOI: 10.1016/j.bbamcr.2011.11.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Revised: 10/27/2011] [Accepted: 11/02/2011] [Indexed: 01/11/2023]
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Abstract
Although canonical NFκB is frequently critical for cell proliferation, survival, or differentiation, NFκB hyperactivation can cause malignant, inflammatory, or autoimmune disorders. Despite intensive study, mammalian NFκB pathway loss-of-function RNAi analyses have been limited to specific protein classes. We therefore undertook a human genome-wide siRNA screen for novel NFκB activation pathway components. Using an Epstein Barr virus latent membrane protein (LMP1) mutant, the transcriptional effects of which are canonical NFκB-dependent, we identified 155 proteins significantly and substantially important for NFκB activation in HEK293 cells. These proteins included many kinases, phosphatases, ubiquitin ligases, and deubiquinating enzymes not previously known to be important for NFκB activation. Relevance to other canonical NFκB pathways was extended by finding that 118 of the 155 LMP1 NF-κB activation pathway components were similarly important for IL-1β-, and 79 for TNFα-mediated NFκB activation in the same cells. MAP3K8, PIM3, and six other enzymes were uniquely relevant to LMP1-mediated NFκB activation. Most novel pathway components functioned upstream of IκB kinase complex (IKK) activation. Robust siRNA knockdown effects were confirmed for all mRNAs or proteins tested. Although multiple ZC3H-family proteins negatively regulate NFκB, ZC3H13 and ZC3H18 were activation pathway components. ZC3H13 was critical for LMP1, TNFα, and IL-1β NFκB-dependent transcription, but not for IKK activation, whereas ZC3H18 was critical for IKK activation. Down-modulators of LMP1 mediated NFκB activation were also identified. These experiments identify multiple targets to inhibit or stimulate LMP1-, IL-1β-, or TNFα-mediated canonical NFκB activation.
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61
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Brahma PK, Zhang H, Murray BS, Shu FJ, Sidell N, Seli E, Kallen CB. The mRNA-binding protein Zfp36 is upregulated by β-adrenergic stimulation and represses IL-6 production in 3T3-L1 adipocytes. Obesity (Silver Spring) 2012; 20:40-7. [PMID: 21818148 PMCID: PMC4127993 DOI: 10.1038/oby.2011.259] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Obesity produces a chronic inflammatory state that contributes to the development of diabetes and atherosclerosis. In obese humans, fat depot adipocytes and macrophages produce inflammatory cytokines and other factors which exert unfavorable local and systemic immune responses. The expression of many cytokines is modulated at the post-transcriptional level by mRNA-binding proteins which recognize AU-rich elements (AREs) in the 3'-untranslated regions (3'-UTR) of these transcripts. One such protein, zinc finger protein 36 (Zfp36), is known to destabilize target mRNAs leading to decreased cytokine expression. Few regulators of Zfp36 expression in adipocytes have been described and mRNA targets of Zfp36 in adipocytes are largely unknown. We found that macrophage-derived inflammatory stimuli enhanced endogenous Zfp36 expression in 3T3-L1 adipocytes. Furthermore, the β-adrenergic receptor agonist isoproterenol (Iso) and the glucocorticoid dexamethasone (Dex) each enhanced Zfp36 expression in adipocytes, the former most likely via a cyclic adenosine monophosphate (cAMP)-dependent pathway. By contrast, Zfp36 expression in murine macrophages (RAW 264.7) was not enhanced by exposure to Dex but was stimulated by retinoic acid (RA). Zfp36 inhibited basal and lipopolysaccharide (LPS)-stimulated interleukin-6 (IL-6) expression in adipocytes. These data reveal important and cell type-specific modulators of Zfp36 expression in adipocytes and macrophages and identify Zfp36 as a potent repressor of adipocyte-derived IL-6. Furthermore, this work identifies new factors that stimulate adipocyte Zfp36 expression that are neither classically inflammatory nor mitogenic. Upregulating an mRNA-binding protein for therapeutic purposes may provide a novel mechanistic approach with which to treat diverse inflammatory disorders including common conditions associated with obesity.
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Affiliation(s)
- Pavna K. Brahma
- Department of Gynecology and Obstetrics, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Huanchun Zhang
- Department of Gynecology and Obstetrics, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Betsy S. Murray
- Department of Gynecology and Obstetrics, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Feng-jue Shu
- Department of Gynecology and Obstetrics, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Neil Sidell
- Department of Gynecology and Obstetrics, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Emre Seli
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Caleb B. Kallen
- Department of Gynecology and Obstetrics, Emory University School of Medicine, Atlanta, Georgia, USA
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62
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Sanduja S, Blanco FF, Young LE, Kaza V, Dixon DA. The role of tristetraprolin in cancer and inflammation. Front Biosci (Landmark Ed) 2012; 17:174-88. [PMID: 22201737 DOI: 10.2741/3920] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Messenger RNA decay is a critical mechanism to control the expression of many inflammation- and cancer-associated genes. These transcripts are targeted for rapid degradation through AU-rich element (ARE) motifs present in the mRNA 3' untranslated region (3'UTR). Tristetraprolin (TTP) is an RNA-binding protein that plays a significant role in regulating the expression of ARE-containing mRNAs. Through its ability to bind AREs and target the bound mRNA for rapid degradation, TTP can limit the expression of a number of critical genes frequently overexpressed in inflammation and cancer. Regulation of TTP occurs on multiple levels through cellular signaling events to control transcription, mRNA turnover, phosphorylation status, cellular localization, association with other proteins, and proteosomal degradation, all of which impact TTP's ability to promote ARE-mediated mRNA decay along with decay-independent functions of TTP. This review summarizes the current understanding of post-transcriptional regulation of ARE-containing gene expression by TTP and discusses its role in maintaining homeostasis and the pathological consequences of losing TTP expression.
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Affiliation(s)
- Sandhya Sanduja
- Department of Biological Sciences and Cancer Research Center, University of South Carolina, Columbia, SC 29203, USA
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63
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Turner M, Hodson DJ. An emerging role of RNA-binding proteins as multifunctional regulators of lymphocyte development and function. Adv Immunol 2012; 115:161-85. [PMID: 22608259 DOI: 10.1016/b978-0-12-394299-9.00006-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Sequence-specific RNA-binding proteins (RBP) and the regulation of RNA decay have long been recognized as important regulators of the inflammatory response. RBP influence gene expression throughout the lifespan of the mRNA by regulating splicing, polyadenylation, cellular localization, translation, and decay. Increasing evidence now indicates that these proteins, together with the RNA decay machinery that they recruit, also regulate the development and activation of lymphocytes. The activity of RBP is regulated by the same signal transduction pathways that govern lymphocyte development and differentiation in response to antigen and cytokine receptor engagement. Roles for these proteins in regulating the diverse functions of lymphocytes are becoming increasingly apparent.
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Affiliation(s)
- Martin Turner
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Babraham Research Campus, Cambridge, United Kingdom
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64
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Grabiec AM, Korchynskyi O, Tak PP, Reedquist KA. Histone deacetylase inhibitors suppress rheumatoid arthritis fibroblast-like synoviocyte and macrophage IL-6 production by accelerating mRNA decay. Ann Rheum Dis 2011; 71:424-31. [PMID: 21953341 PMCID: PMC3277722 DOI: 10.1136/ard.2011.154211] [Citation(s) in RCA: 145] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Background Histone deacetylase inhibitors (HDACi) display potent therapeutic efficacy in animal models of arthritis and suppress inflammatory cytokine production in rheumatoid arthritis (RA) synovial macrophages and tissue. Objectives To determine the molecular mechanisms contributing to the suppressive effects of HDACi on RA synovial cell activation, using interleukin 6 (IL-6) regulation as a model. Methods RA fibroblast-like synoviocytes (FLS) and healthy donor macrophages were treated with IL-1β, tumour necrosis factor (TNF)α, lipopolysaccharide or polyinosinic:polycytidylic acid (poly(I:C)) in the absence or presence of the HDACi trichostatin A (TSA) or ITF2357 (givinostat). IL-6 production and mRNA expression was measured by ELISA and quantitative PCR (qPCR), respectively. Protein acetylation and the activation of intracellular signalling pathways were assessed by immunoblotting. The DNA-binding activity of nuclear factor κB (NFκB) and activator protein 1 (AP-1) components was measured by ELISA-based assays. Results HDACi (0.25–1.0 μM) suppressed RA FLS IL-6 production induced by IL-1β, TNFα and Toll-like receptor ligands. Phosphorylation of mitogen-activated protein kinases and inhibitor of κBα (IκBα) following IL-1β stimulation were unaffected by HDACi, as were AP-1 composition and binding activity, and c-Jun induction. TSA induced a significant reduction in nuclear retention of NFκB in FLS 24 h after IL-1β stimulation, but this did not reduce NFκB transcriptional activity or correlate temporally with reductions in IL-6 mRNA accumulation. HDACi significantly reduced the stability of IL-6 mRNA in FLS and macrophages. Conclusions Our study identifies a novel, shared molecular mechanism by which HDACi can disrupt inflammatory cytokine production in RA synovial cells, namely the promotion of mRNA decay, and suggests that targeting HDAC activity may be clinically useful in suppressing inflammation in RA.
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Affiliation(s)
- Aleksander M Grabiec
- Division of Clinical Immunology and Rheumatology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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65
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Schichl YM, Resch U, Lemberger CE, Stichlberger D, de Martin R. Novel phosphorylation-dependent ubiquitination of tristetraprolin by mitogen-activated protein kinase/extracellular signal-regulated kinase kinase kinase 1 (MEKK1) and tumor necrosis factor receptor-associated factor 2 (TRAF2). J Biol Chem 2011; 286:38466-38477. [PMID: 21921033 DOI: 10.1074/jbc.m111.254888] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Acute versus chronic inflammation is controlled by the accurate activation and regulation of interdependent signaling cascades. TNF-receptor 1 engagement concomitantly activates NF-κB and JNK signaling. The correctly timed activation of these pathways is the key to account for the balance between NF-κB-mediated cell survival and cell death, the latter fostered by prolonged JNK activation. Tristetraprolin (TTP), initially described as an mRNA destabilizing protein, acts as negative feedback regulator of the inflammatory response: it destabilizes cytokine-mRNAs but also acts as an NF-κB inhibitor by interfering with the p65/RelA nuclear import pathway. Our biochemical studies provide evidence that TTP contributes to the NF-κB/JNK balance. We find that the MAP 3-kinase MEKK1 acts as a novel TTP kinase that, together with the TNF receptor-associated factor 2 (TRAF2), constitutes not only a main determinate of the NF-κB-JNK cross-talk but also facilitates "TTP hypermodification": MEKK1 triggers TTP phosphorylation as prerequisite for its Lys-63-linked, TRAF2-mediated ubiquitination. Consequently, TTP no longer affects NF-κB activity but promotes the activation of JNK. Based on our data, we suggest a model where upon TNFα induction, TTP transits a hypo- to hypermodified state, thereby contributing to the molecular regulation of NF-κB versus JNK signaling cascades.
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Affiliation(s)
- Yvonne M Schichl
- Department of Vascular Biology and Thrombosis Research, Center for Physiology and Pharmacology, Medical University of Vienna, Lazarettgasse 19, 1090 Vienna, Austria.
| | - Ulrike Resch
- Department of Vascular Biology and Thrombosis Research, Center for Physiology and Pharmacology, Medical University of Vienna, Lazarettgasse 19, 1090 Vienna, Austria
| | - Christof E Lemberger
- Department of Vascular Biology and Thrombosis Research, Center for Physiology and Pharmacology, Medical University of Vienna, Lazarettgasse 19, 1090 Vienna, Austria
| | - Dominik Stichlberger
- Department of Vascular Biology and Thrombosis Research, Center for Physiology and Pharmacology, Medical University of Vienna, Lazarettgasse 19, 1090 Vienna, Austria
| | - Rainer de Martin
- Department of Vascular Biology and Thrombosis Research, Center for Physiology and Pharmacology, Medical University of Vienna, Lazarettgasse 19, 1090 Vienna, Austria
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66
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Abstract
Posttranscriptional mechanisms are now widely acknowledged to play a central role in orchestrating gene-regulatory networks in hematopoietic cell growth, differentiation, and tumorigenesis. Although much attention has focused on microRNAs as regulators of mRNA stability/translation, recent data have highlighted the role of several diverse classes of AU-rich RNA-binding protein in the regulation of mRNA decay/stabilization. AU-rich elements are found in the 3'-untranslated region of many mRNAs that encode regulators of cell growth and survival, such as cytokines and onco/tumor-suppressor proteins. These are targeted by a burgeoning number of different RNA-binding proteins. Three distinct types of AU-rich RNA binding protein (ARE poly-U-binding degradation factor-1/AUF1, Hu antigen/HuR/HuA/ELAVL1, and the tristetraprolin/ZFP36 family of proteins) are essential for normal hematopoiesis. Together with 2 further AU-rich RNA-binding proteins, nucleolin and KHSRP/KSRP, the functions of these proteins are intimately associated with pathways that are dysregulated in various hematopoietic malignancies. Significantly, all of these AU-rich RNA-binding proteins function via an interconnected network that is integrated with microRNA functions. Studies of these diverse types of RNA binding protein are providing novel insight into gene-regulatory mechanisms in hematopoiesis in addition to offering new opportunities for developing mechanism-based targeted therapeutics in leukemia and lymphoma.
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67
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Schmitz ML, Weber A, Roxlau T, Gaestel M, Kracht M. Signal integration, crosstalk mechanisms and networks in the function of inflammatory cytokines. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:2165-75. [PMID: 21787809 DOI: 10.1016/j.bbamcr.2011.06.019] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Revised: 05/31/2011] [Accepted: 06/01/2011] [Indexed: 12/20/2022]
Abstract
Infection or cell damage triggers the release of pro-inflammatory cytokines such as interleukin(IL)-1α or β and tumor necrosis factor (TNF)α which are key mediators of the host immune response. Following their identification and the elucidation of central signaling pathways, recent results show a highly complex crosstalk between various cytokines and their signaling effectors. The molecular mechanisms controlling signaling thresholds, signal integration and the function of feed-forward and feedback loops are currently revealed by combining methods from biochemistry, genetics and in silico analysis. Increasing evidence is mounted that defects in information processing circuits or their components can be causative for chronic or overshooting inflammation. As progress in biosciences has always benefitted from the use of well-studied model systems, research on inflammatory cytokines may function as a paradigm to reveal general principles of signal integration, crosstalk mechanisms and signaling networks.
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Affiliation(s)
- M Lienhard Schmitz
- Institute of Biochemistry, Justus-Liebig-University Giessen, Giessen, Germany.
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68
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Qian X, Ning H, Zhang J, Hoft DF, Stumpo DJ, Blackshear PJ, Liu J. Posttranscriptional regulation of IL-23 expression by IFN-gamma through tristetraprolin. THE JOURNAL OF IMMUNOLOGY 2011; 186:6454-64. [PMID: 21515794 DOI: 10.4049/jimmunol.1002672] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
IL-23 plays an essential role in maintenance of IL-17-producing Th17 cells that are involved in the pathogenesis of several autoimmune diseases. Regulation of Th17 cells is tightly controlled by multiple factors such as IL-27 and IFN-γ. However, the detailed mechanisms responsible for IFN-γ-mediated Th17 cell inhibition are still largely unknown. In this study, we demonstrate that IFN-γ differentially regulates IL-12 and IL-23 production in both dendritic cells and macrophages. IFN-γ suppresses IL-23 expression by selectively targeting p19 mRNA stability through its 3'-untranslated region (3'UTR). Furthermore, IFN-γ enhances LPS-induced tristetraprolin (TTP) mRNA expression and protein production. Overexpression of TTP suppresses IL-23 p19 mRNA expression and p19 3'UTR-dependent luciferase activity. Additionally, deletion of TTP completely abolishes IFN-γ-mediated p19 mRNA degradation. We further demonstrate that IFN-γ suppresses LPS-induced p38 phosphorylation, and blockade of p38 MAPK signaling pathway with SB203580 inhibits IFN-γ- and LPS-induced p19 mRNA expression, whereas overexpression of p38 increases p19 mRNA expression via reducing TTP binding to the p19 3'UTR. Finally, inhibition of p38 phosphorylation by IFN-γ leads to TTP dephosphorylation that could result in stronger binding of the TTP to the adenosine/uridine-rich elements in the p19 3'UTR and p19 mRNA degradation. In summary, our results reveal a direct link among TTP, IFN-γ, and IL-23, indicating that IFN-γ-mediated Th17 cell suppression might act through TTP by increasing p19 mRNA degradation and therefore IL-23 inhibition.
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Affiliation(s)
- Xuesong Qian
- Division of Infectious Diseases, Department of Internal Medicine, Saint Louis University School of Medicine, St Louis, MO 63104, USA
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69
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Borghini S, Fiore M, Di Duca M, Caroli F, Finetti M, Santamaria G, Ferlito F, Bua F, Picco P, Obici L, Martini A, Gattorno M, Ceccherini I. Candidate genes in patients with autoinflammatory syndrome resembling tumor necrosis factor receptor-associated periodic syndrome without mutations in the TNFRSF1A gene. J Rheumatol 2011; 38:1378-84. [PMID: 21459945 DOI: 10.3899/jrheum.101260] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
OBJECTIVE Tumor necrosis factor (TNF) receptor-associated periodic syndrome (TRAPS) is an autosomal-dominant multisystemic autoinflammatory condition. Patients display different mutations of the TNF receptor superfamily 1A gene (TNFRSF1A), coding for a nearly ubiquitous TNF receptor (TNFR1). No TNFRSF1A mutation has been identified in a proportion of patients with TRAPS-like phenotype. METHODS We investigated mechanisms downregulating the TNF-induced inflammatory response such as (1) receptor shedding, producing a secreted form acting as a TNF inhibitor; (2) receptor internalization with subsequent induction of apoptosis; and (3) negative regulation of nuclear factor-κB (NF-κB) transcription. We analyzed the sequence of genes known to play a pivotal role in these pathways, in 5 patients with TRAPS symptoms and showing shedding and/or apoptosis defects, but without mutations of the TNFRSF1A gene. RESULTS Sequence analysis of 3 genes involved in TNFR1 shedding (ERAP1, NUCB2, RBMX) and 3 genes involved in negative regulation of NF-κB signaling (TNFAIP3, CARP-2) or NF-κB transcription (ZFP36) revealed only a few unreported variants, apparently neutral. CONCLUSION Our study rules out any involvement in the pathogenesis of TRAPS of some of the genes known to regulate TNFR1 shedding and TNF-induced NF-κB signaling and transcription. Gene(s) responsible for TRAPS-like syndrome remain to be investigated among currently unidentified genes likely involved in these pathways, or by applying the genome-wide function-free sequencing approach.
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Affiliation(s)
- Silvia Borghini
- Laboratorio di Genetica Molecolare, Istituto G. Gaslini, Genova, Italy
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70
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Fan J, Ishmael FT, Fang X, Myers A, Cheadle C, Huang SK, Atasoy U, Gorospe M, Stellato C. Chemokine transcripts as targets of the RNA-binding protein HuR in human airway epithelium. THE JOURNAL OF IMMUNOLOGY 2011; 186:2482-94. [PMID: 21220697 DOI: 10.4049/jimmunol.0903634] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
HuR is a regulator of mRNA turnover or translation of inflammatory genes through binding to adenylate-uridylate-rich elements and related motifs present in the 3'untranslated region (UTR) of mRNAs. We postulate that HuR critically regulates the epithelial response by associating with multiple ARE-bearing, functionally related inflammatory transcripts. We aimed to identify HuR targets in the human airway epithelial cell line BEAS-2B challenged with TNF-α plus IFN-γ, a strong stimulus for inflammatory epithelial responses. Ribonucleoprotein complexes from resting and cytokine-treated cells were immunoprecipitated using anti-HuR and isotype-control Ab, and eluted mRNAs were reverse-transcribed and hybridized to an inflammatory-focused gene array. The chemokines CCL2, CCL8, CXCL1, and CXCL2 ranked highest among 27 signaling and inflammatory genes significantly enriched in the HuR RNP-IP from stimulated cells over the control immunoprecipitation. Among these, 20 displayed published HuR binding motifs. Association of HuR with the four endogenous chemokine mRNAs was validated by single-gene ribonucleoprotein-immunoprecipitation and shown to be 3'UTR-dependent by biotin pull-down assay. Cytokine treatment increased mRNA stability only for CCL2 and CCL8, and transient silencing and overexpression of HuR affected only CCL2 and CCL8 expression in primary and transformed epithelial cells. Cytokine-induced CCL2 mRNA was predominantly cytoplasmic. Conversely, CXCL1 mRNA remained mostly nuclear and unaffected, as CXCL2, by changes in HuR levels. Increase in cytoplasmic HuR and HuR target expression partially relied on the inhibition of AMP-dependent kinase, a negative regulator of HuR nucleocytoplasmic shuttling. HuR-mediated regulation in airway epithelium appears broader than previously appreciated, coordinating numerous inflammatory genes through multiple posttranscriptional mechanisms.
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Affiliation(s)
- Jinshui Fan
- Division of Allergy and Clinical Immunology, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA
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71
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Ishmael FT, Fang X, Houser KR, Pearce K, Abdelmohsen K, Zhan M, Gorospe M, Stellato C. The human glucocorticoid receptor as an RNA-binding protein: global analysis of glucocorticoid receptor-associated transcripts and identification of a target RNA motif. THE JOURNAL OF IMMUNOLOGY 2010; 186:1189-98. [PMID: 21148795 DOI: 10.4049/jimmunol.1001794] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Posttranscriptional regulation is emerging as a key factor in glucocorticoid (GC)-mediated gene regulation. We investigated the role of the human GC receptor (GR) as an RNA-binding protein and its effect on mRNA turnover in human airway epithelial cells. Cell treatment with the potent GC budesonide accelerated the decay of CCL2 mRNA (t(1/2) = 8 ± 1 min versus 62 ± 17 min in DMSO-treated cells) and CCL7 mRNA (t(1/2) = 15 ± 4 min versus 114 ± 37 min), but not that of CCL5 mRNA (t(1/2)=231 ± 8 min versus 266 ± 5 min) in the BEAS-2B cell line. This effect was inhibited by preincubation with an anti-GR Ab, indicating that GR itself plays a role in the turnover of these transcripts. Coimmunoprecipitation and biotin pulldown experiments showed that GR associates with CCL2 and CCL7 mRNAs, but not CCL5 mRNA. These methods confirmed CCL2 mRNA targeting by GR in human primary airway epithelial cells. Association of the GR was localized to the 5' untranslated region of CCL2 mRNA and further mapped to nt 44-60. The collection of transcripts associated with GR, identified by immunoprecipitation of GR-mRNA complexes followed by microarray analysis, revealed 479 transcripts that associated with GR. Computational analysis of the primary sequence and secondary structures of these transcripts yielded a GC-rich motif, which was shown to bind to GR in vitro. This motif was used to predict binding of GR to an additional 7889 transcripts. These results indicate that cytoplasmic GR interacts with a subset of mRNA through specific sequences and can regulate turnover rates, suggesting a novel posttranscriptional role for GR as an RNA-binding protein.
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Affiliation(s)
- Faoud T Ishmael
- Division of Allergy and Clinical Immunology, The Johns Hopkins Asthma and Allergy Center, Baltimore, MD 21224, USA.
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72
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Liang J, Saad Y, Lei T, Wang J, Qi D, Yang Q, Kolattukudy PE, Fu M. MCP-induced protein 1 deubiquitinates TRAF proteins and negatively regulates JNK and NF-kappaB signaling. ACTA ACUST UNITED AC 2010; 207:2959-73. [PMID: 21115689 PMCID: PMC3005225 DOI: 10.1084/jem.20092641] [Citation(s) in RCA: 235] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A previously unappreciated deubiquitinase activity of MCP-induced protein 1 contributes to its role in dampening inflammatory signaling. The intensity and duration of macrophage-mediated inflammatory responses are controlled by proteins that modulate inflammatory signaling pathways. MCPIP1 (monocyte chemotactic protein–induced protein 1), a recently identified CCCH Zn finger–containing protein, plays an essential role in controlling macrophage-mediated inflammatory responses. However, its mechanism of action is poorly understood. In this study, we show that MCPIP1 negatively regulates c-Jun N-terminal kinase (JNK) and NF-κB activity by removing ubiquitin moieties from proteins, including TRAF2, TRAF3, and TRAF6. MCPIP1-deficient mice spontaneously developed fatal inflammatory syndrome. Macrophages and splenocytes from MCPIP1−/− mice showed elevated expression of inflammatory gene expression, increased JNK and IκB kinase activation, and increased polyubiquitination of TNF receptor–associated factors. In vitro assays directly demonstrated the deubiquitinating activity of purified MCPIP1. Sequence analysis together with serial mutagenesis defined a deubiquitinating enzyme domain and a ubiquitin association domain in MCPIP1. Our results indicate that MCPIP1 is a critical modulator of inflammatory signaling.
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Affiliation(s)
- Jian Liang
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32816, USA
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Baker BJ, Park KW, Qin H, Ma X, Benveniste EN. IL-27 inhibits OSM-mediated TNF-alpha and iNOS gene expression in microglia. Glia 2010; 58:1082-93. [PMID: 20468050 DOI: 10.1002/glia.20989] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Elevated levels of Oncostatin M (OSM), an interleukin-6 family cytokine, have been observed in multiple sclerosis (MS), HIV-associated neurocognitive disorder (HAND), and glioblastoma (GBM); however, its effects within the CNS are not well understood. OSM regulates gene expression primarily by activating the JAK/STAT, NF-kappaB, and/or MAPK pathways, in a cell-type specific manner. In our studies, OSM induces the production of the proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) and inducible nitric oxide synthase (iNOS) from microglia in an NF-kappaB-dependent manner. This expression also partially requires the intermediate production of TNF-alpha and subsequent NF-kappaB activation via TNF-R1. We also demonstrate that OSM-induced TNF-alpha production from microglia is neurotoxic. The IL-12 family member, IL-27, suppresses OSM-mediated TNF-alpha and iNOS expression at the transcriptional level by inhibiting activation of the NF-kappaB pathway, and rescues the neurotoxicity induced by OSM-stimulated microglia. These studies are the first to demonstrate the proinflammatory effects of OSM in microglia, and also identify IL-27 as a novel inhibitor of inflammatory processes in these cells.
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Affiliation(s)
- Brandi J Baker
- Department of Cell Biology, University of Alabama at Birmingham, Birmingham, Alabama, USA
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