AU-rich Element

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Gary Brewer - One of the best experts on this subject based on the ideXlab platform.

  • au rich Element dependent translation repression requires the cooperation of tristetraprolin and rck p54
    Molecular and Cellular Biology, 2012
    Co-Authors: Zhi Zhang Wang, Gary Brewer, Zhuo Zhang, Qin Shao, An Zeng, Chen Wang, Fu Ju Tian, Jun Zou, Yongwen Qin
    Abstract:

    AU-rich Elements (AREs), residing in the 3′ untranslated region (UTR) of many labile mRNAs, are important cis-acting Elements that modulate the stability of these mRNAs by collaborating with trans-acting factors such as tristetraprolin (TTP). AREs also regulate translation, but the underlying mechanism is not fully understood. Here we examined the function and mechanism of TTP in ARE-mRNA translation. Through a luciferase-based reporter system, we used knockdown, overexpression, and tethering assays in 293T cells to demonstrate that TTP represses ARE reporter mRNA translation. Polyribosome fractionation experiments showed that TTP shifts target mRNAs to lighter fractions. In murine RAW264.7 macrophages, knocking down TTP produces significantly more tumor necrosis factor alpha (TNF-α) than the control, while the corresponding mRNA level has a marginal change. Furthermore, knockdown of TTP increases the rate of biosynthesis of TNF-α, suggesting that TTP can exert effects at translational levels. Finally, we demonstrate that the general translational repressor RCK may cooperate with TTP to regulate ARE-mRNA translation. Collectively, our studies reveal a novel function of TTP in repressing ARE-mRNA translation and that RCK is a functional partner of TTP in promoting TTP-mediated translational repression.

  • Chaperone Hsp27 modulates AUF1 proteolysis and AU-rich Element-mediated mRNA degradation.
    Molecular and cellular biology, 2011
    Co-Authors: Anna M. Knapinska, Frances M. Gratacós, Christopher D. Krause, Kristina Hernandez, Amber G. Jensen, Jacquelyn J. Bradley, Sidney Pestka, Gary Brewer
    Abstract:

    AUF1 is an AU-rich Element (ARE)-binding protein that recruits translation initiation factors, molecular chaperones, and mRNA degradation enzymes to the ARE for mRNA destruction. We recently found chaperone Hsp27 to be an AUF1-associated ARE-binding protein required for tumor necrosis factor alpha (TNF-) mRNA degradation in monocytes. Hsp27 is a multifunctional protein that participates in ubiquitination of proteins for their degradation by proteasomes. A variety of extracellular stimuli promote Hsp27 phosphorylation on three serine residues—Ser 15 , Ser 78 , and Ser 82 —by a number of kinases, including the mitogenactivated protein (MAP) pathway kinases p38 and MK2. Activating either kinase stabilizes ARE mRNAs. Likewise, ectopic expression of phosphomimetic mutant forms of Hsp27 stabilizes reporter ARE mRNAs. Here, we continued to examine the contributions of Hsp27 to mRNA degradation. As AUF1 is ubiquitinated and degraded by proteasomes, we addressed the hypothesis that Hsp27 phosphorylation controls AUF1 levels to modulate ARE mRNA degradation. Indeed, selected phosphomimetic mutants of Hsp27 promote proteolysis of AUF1 in a proteasome-dependent fashion and render ARE mRNAs more stable. Our results suggest that the p38 MAP kinase (MAPK)-MK2-Hsp27 signaling axis may target AUF1 destruction by proteasomes, thereby promoting ARE mRNA stabilization.

  • Identification of TINO. A new evolutionarily conserved BCL-2 AU-rich Element RNA-binding protein
    The Journal of biological chemistry, 2004
    Co-Authors: Martino Donnini, Gary Brewer, Andrea Lapucci, Laura Papucci, Ewa Witort, Alain Jacquier, Angelo Nicolin, Sergio Capaccioli, Nicola Schiavone
    Abstract:

    Modulation of mRNA stability by regulatory cis-acting AU-rich Elements (AREs) and ARE-binding proteins is an important posttranscriptional mechanism of gene expression control. We previously demonstrated that the 3′-untranslated region of BCL-2 mRNA contains an ARE that accounts for rapid BCL-2 down-regulation in response to apoptotic stimuli. We also demonstrated that the BCL-2 ARE core interacts with a number of ARE-binding proteins, one of which is AU-rich factor 1/heterogeneous nuclear ribonucleoprotein D, known for its interaction with mRNA Elements of others genes. In an attempt to search for other BCL-2 mRNA-binding proteins, we used the yeast RNA three-hybrid system assay and identified a novel human protein that interacts with BCL-2 ARE. We refer to it as TINO. The predicted protein sequence of TINO reveals two amino-terminal heterogeneous nuclear ribonucleoprotein K homology motifs for nucleic acid binding and a carboxyl-terminal RING domain, endowed with a putative E3 ubiquitin-protein ligase activity. In addition the novel protein is evolutionarily conserved; the two following orthologous proteins have been identified with protein-protein BLAST: posterior end mark-3 (PEM-3) of Ciona savignyi and muscle excess protein-3 (MEX-3) of Caenorhabditis elegans. Upon binding, TINO destabilizes a chimeric reporter construct containing the BCL-2 ARE sequence, revealing a negative regulatory action on BCL-2 gene expression at the posttranscriptional level.

  • Lactate dehydrogenase is an AU-rich Element-binding protein that directly interacts with AUF1.
    The Journal of biological chemistry, 2002
    Co-Authors: Patricia A. Pioli, Gary Brewer, B. Jonell Hamilton, John E. Connolly, William F. C. Rigby
    Abstract:

    Post-transcriptional pathways provide a major means of regulating eukaryotic gene expression. Reiterations of the AU-rich Element (ARE) within the 3'-untranslated region of many cytokine and proto-oncogene mRNAs serve as signals for rapid degradation and translational repression. The identification of this cis-acting stability determinant has fueled the search for ARE-binding proteins (AUBP) that function as trans-acting factors that transduce this function. Previous work identified heterogeneous nuclear ribonucleoprotein (hnRNP) A1 as a major AUBP capable of binding the ARE of granulocyte-macrophage colony stimulating factor (GM-CSF) RNA in the context of a full-length mRNA. We report here that functional studies failed to indicate a role for hnRNP A1 in ARE-dependent mRNA turnover. In an effort to identify other functionally relevant AUBP, the major GM-CSF ARE-specific binding protein in cells lacking hnRNP A1 was purified from CB3 mouse erythroleukemia cells. Microsequencing identified this protein as the glycolytic enzyme lactate dehydrogenase (LDH) M. RNA binding by LDH was shown to occur in the NAD(+)-binding region (Rossmann fold). Polysome gradient analysis demonstrates that LDH is found in the translationally active fraction. Polysomal localization of LDH was dependent on RNA binding. Moreover, polysomal LDH exists in a complex with AUF1 and hsp-70, which has been implicated previously in the regulation of mRNA turnover. The interaction between LDH and AUF1 is direct as it can be demonstrated in vitro with purified proteins. Collectively these data implicate a role for LDH in the post-transcriptional regulation of gene expression.

  • purification characterization and cdna cloning of an au rich Element rna binding protein auf1
    Molecular and Cellular Biology, 1993
    Co-Authors: Wei Zhang, B J Wagner, Karen Ehrenman, A W Schaefer, Christine T Demaria, D Crater, K Dehaven, L Long, Gary Brewer
    Abstract:

    The degradation of some proto-oncogene and lymphokine mRNAs is controlled in part by an AU-rich Element (ARE) in the 3' untranslated region. It was shown previously (G. Brewer, Mol. Cell. Biol. 11:2460-2466, 1991) that two polypeptides (37 and 40 kDa) copurified with fractions of a 130,000 x g postribosomal supernatant (S130) from K562 cells that selectively accelerated degradation of c-myc mRNA in a cell-free decay system. These polypeptides bound specifically to the c-myc and granulocyte-macrophage colony-stimulating factor 3' UTRs, suggesting they are in part responsible for selective mRNA degradation. In the present work, we have purified the RNA-binding component of this mRNA degradation activity, which we refer to as AUF1. Using antisera specific for these polypeptides, we demonstrate that the 37- and 40-kDa polypeptides are immunologically cross-reactive and that both polypeptides are phosphorylated and can be found in a complex(s) with other polypeptides. Immunologically related polypeptides are found in both the nucleus and the cytoplasm. The antibodies were also used to clone a cDNA for the 37-kDa polypeptide. This cDNA contains an open reading frame predicted to produce a protein with several features, including two RNA recognition motifs and domains that potentially mediate protein-protein interactions. These results provide further support for a role of this protein in mediating ARE-directed mRNA degradation.

Gerald M. Wilson - One of the best experts on this subject based on the ideXlab platform.

  • Assembly of Functional Ribonucleoprotein Complexes by AU-rich Element RNA-binding Protein 1 (AUF1) Requires Base-dependent and -independent RNA Contacts
    The Journal of biological chemistry, 2013
    Co-Authors: Beth E. Zucconi, Gerald M. Wilson
    Abstract:

    Abstract AU-rich Element RNA-binding protein 1 (AUF1) regulates the stability and/or translational efficiency of diverse mRNA targets, including many encoding products controlling the cell cycle, apoptosis, and inflammation, by associating with AU-rich Elements (AREs) residing in their 3[prime]-untranslated regions. Previous biochemical studies showed that optimal AUF1 binding requires 33-34 nucleotides with a strong preference for U-rich RNA, despite observations that few AUF1-associated cellular mRNAs contain such extended U-rich domains. Using the smallest AUF1 isoform (p37AUF1) as a model, we employed fluorescence anisotropy-based approaches to define thermodynamic parameters describing AUF1 ribonucleoprotein (RNP) complex formation across a panel of RNA substrates. These data demonstrated that 15 nucleotides of AU-rich sequence were sufficient to nucleate high-affinity p37AUF1 RNP complexes within a larger RNA context. In particular, p37AUF1 binding to short ARE targets was significantly stabilized by interactions with a 3[prime]-purine residue and largely base-independent but non-ionic contacts 5[prime] of the AU-rich site. RNP stabilization by the upstream RNA domain was associated with an enhanced negative change in heat capacity consistent with conformational changes in protein and/or RNA components, and fluorescence resonance energy transfer-based assays demonstrated that these contacts were required for p37AUF1 to remodel local RNA structure. Finally, reporter mRNAs containing minimal high-affinity p37AUF1 target sequences associated with AUF1 and were destabilized in a p37AUF1-dependent manner in cells. These findings provide a mechanistic explanation for the diverse population of AUF1 target mRNAs, but also suggest how AUF1 binding could regulate protein and/or miRNA-binding events at adjacent sites.

  • Alternatively Expressed Domains of AU-rich Element RNA-binding Protein 1 (AUF1) Regulate RNA-binding Affinity, RNA-induced Protein Oligomerization, and the Local Conformation of Bound RNA Ligands
    The Journal of biological chemistry, 2010
    Co-Authors: Beth E. Zucconi, Jeff D. Ballin, Brandy Y. Brewer, Christina R. Ross, Jun Huang, Eric A. Toth, Gerald M. Wilson
    Abstract:

    AU-rich Element RNA-binding protein 1 (AUF1) binding to AU-rich Elements (AREs) in the 3'-untranslated regions of mRNAs encoding many cytokines and other regulatory proteins modulates mRNA stability, thereby influencing protein expression. AUF1-mRNA association is a dynamic paradigm directed by various cellular signals, but many features of its function remain poorly described. There are four isoforms of AUF1 that result from alternative splicing of exons 2 and 7 from a common pre-mRNA. Preliminary evidence suggests that the different isoforms have varied functional characteristics, but no detailed quantitative analysis of the properties of each isoform has been reported despite their differential expression and regulation. Using purified recombinant forms of each AUF1 protein variant, we used chemical cross-linking and gel filtration chromatography to show that each exists as a dimer in solution. We then defined the association mechanisms of each AUF1 isoform for ARE-containing RNA substrates and quantified relevant binding affinities using electrophoretic mobility shift and fluorescence anisotropy assays. Although all AUF1 isoforms generated oligomeric complexes on ARE substrates by sequential dimer association, sequences encoded by exon 2 inhibited RNA-binding affinity. By contrast, the exon 7-encoded domain enhanced RNA-dependent protein oligomerization, even permitting cooperative RNA-binding activity in some contexts. Finally, fluorescence resonance energy transfer-based assays showed that the different AUF1 isoforms remodel bound RNA substrates into divergent structures as a function of protein:RNA stoichiometry. Together, these data describe isoform-specific characteristics among AUF1 ribonucleoprotein complexes, which likely constitute a mechanistic basis for differential functions and regulation among members of this protein family.

  • Alternatively Expressed Domains of AU-rich Element RNA-binding Protein 1 (AUF1) Regulate RNA-binding Affinity, RNA-induced Protein Oligomerization, and the Local
    2010
    Co-Authors: Beth E. Zucconi, Jeff D. Ballin, Brandy Y. Brewer, Christina R. Ross, Jun Huang, Eric A. Toth, Gerald M. Wilson
    Abstract:

    AU-rich Element RNA-binding protein 1 (AUF1) bindingto AU-rich Elements (AREs) in the 3 trolproteinexpressiontorapidlyrespondtoever-changing-untranslated regionsof mRNAs encoding many cytokines and other regulatoryproteins modulates mRNA stability, thereby influencingprotein expression. AUF1-mRNA association is a dynamicparadigm directed by various cellular signals, but many fea-tures of its function remain poorly described. There are fourisoforms of AUF1 that result from alternative splicing ofexons 2 and 7 from a common pre-mRNA. Preliminary evi-dence suggests that the different isoforms have varied func-tional characteristics, but no detailed quantitative analysisof the properties of each isoform has been reported despitetheir differential expression and regulation. Using purifiedrecombinant forms of each AUF1 protein variant, we usedchemical cross-linking and gel filtration chromatography toshow that each exists as a dimer in solution. We then de-fined the association mechanisms of each AUF1 isoform forARE-containing RNA substrates and quantified relevantbinding affinities using electrophoretic mobility shift andfluorescence anisotropy assays. Although all AUF1 isoformsgenerated oligomeric complexes on ARE substrates by se-quential dimer association, sequences encoded by exon 2inhibited RNA-binding affinity. By contrast, the exon 7-en-coded domain enhanced RNA-dependent protein oligomer-ization, even permitting cooperative RNA-binding activityin some contexts. Finally, fluorescence resonance energytransfer-based assays showed that the different AUF1 iso-forms remodel bound RNA substrates into divergent struc-tures as a function of protein:RNA stoichiometry. Together,these data describe isoform-specific characteristics amongAUF1 ribonucleoprotein complexes, which likely constitutea mechanistic basis for differential functions and regulationamong members of this protein family.

Khalid S.a. Khabar - One of the best experts on this subject based on the ideXlab platform.

  • ARED-Plus: an updated and expanded database of AU-rich Element-containing mRNAs and pre-mRNAs
    Nucleic acids research, 2017
    Co-Authors: Tala Bakheet, Edward Hitti, Khalid S.a. Khabar
    Abstract:

    Here we present an updated version of the AU-rich Element Database (ARED-Plus) that is freely available at http://brp.kfshrc.edu.sa/ared. AREs are conserved sequence Elements that were first discovered in the 3'UTR of mammalian transcripts. Over the past years, we compiled a series of ARE databases that revealed the extent and wide distribution of ARE-containing genes. For this update, we adopted an optimized search algorithm with improved specificity and sensitivity in ARE selection. The designation of the different ARE clusters was simplified by directly correlating the number of the ARE cluster to the number of overlapping AUUUA pentamers. Additionally, the new database was expanded to include genes with intronic AREs (pre-mRNAs) and their characteristics since recent observations reported their abundance and biological significance. Several enhancements were incorporated such as customized column view, additional search options and live search functionalities. The new version includes links to AREsite and AREScore, two related ARE assessment algorithms for further evaluation of the ARE characteristics. ARED-Plus now contains an updated repertoire of AREs in the human transcriptome that may be useful in several research fields.

  • Sequence variations affecting AU-rich Element function and disease.
    Frontiers in bioscience (Landmark edition), 2012
    Co-Authors: Edward Hitti, Khalid S.a. Khabar
    Abstract:

    Adenylate-uridylate rich Elements (AREs) in the 3'UTRs of many transiently expressed genes regulate mRNA instability and translation. Such ARE-genes are involved in vital biological processes like cellular growth, differentiation, and immunity. Defects in their expression contribute to a variety of disease conditions like cancer, autoimmune diseases, diabetes, and cardiovascular and chronic inflammatory diseases. Over the past two decades, considerable progress has been made in understanding the mode of regulation of AREs containing mRNAs by RNA-binding proteins, miRNAs, and signaling pathways. This review focuses on the less documented sequence variation affecting ARE functions and its relation to disease. We discuss reports describing genetic polymorphisms, alternative polyadenylation, and alternative splicing that can lead to the loss or gain of function of AREs, often with significant implications to disease.

  • Oncogenic Ras and Transforming Growth Factor-β Synergistically Regulate AU-rich Element–Containing mRNAs during Epithelial to Mesenchymal Transition
    Molecular cancer research : MCR, 2008
    Co-Authors: Cindy L. Kanies, Khalid S.a. Khabar, J. Joshua Smith, Christian Kis, Carl Schmidt, Shawn Levy, Jason D. Morrow, Natasha G. Deane, Dan A. Dixon, R. Daniel Beauchamp
    Abstract:

    Colon cancer progression is characterized by activating mutations in Ras and by the emergence of the tumor-promoting effects of transforming growth factor-beta (TGF-beta) signaling. Ras-inducible rat intestinal epithelial cells (RIE:iRas) undergo a well-described epithelial to mesenchymal transition and invasive phenotype in response to H-RasV12 expression and TGF-beta treatment, modeling tumor progression. We characterized global gene expression profiles accompanying Ras-induced and TGF-beta-induced epithelial to mesenchymal transition in RIE:iRas cells by microarray analysis and found that the regulation of gene expression by the combined activation of Ras and TGF-beta signaling was associated with enrichment of a class of mRNAs containing 3' AU-rich Element (ARE) motifs known to regulate mRNA stability. Regulation of ARE-containing mRNA transcripts was validated at the mRNA level, including genes important for tumor progression. Ras and TGF-beta synergistically increased the expression and mRNA stability of vascular endothelial growth factor (VEGF), a key regulator of tumor angiogenesis, in both RIE:iRas cells and an independent cell culture model (young adult mouse colonocyte). Expression profiling of human colorectal cancers (CRC) further revealed that many of these genes, including VEGF and PAI-1, were differentially expressed in stage IV human colon adenocarcinomas compared with adenomas. Furthermore, genes differentially expressed in CRC are also significantly enriched with ARE-containing transcripts. These studies show that oncogenic Ras and TGF-beta synergistically regulate genes containing AREs in cultured rodent intestinal epithelial cells and suggest that posttranscriptional regulation of gene expression is an important mechanism involved in cellular transformation and CRC tumor progression.

  • ARED Organism: expansion of ARED reveals AU-rich Element cluster variations between human and mouse.
    Nucleic acids research, 2007
    Co-Authors: Anason S Halees, Rashad El-badrawi, Khalid S.a. Khabar
    Abstract:

    ARED Organism represents the expansion of the adenylate uridylate (AU)-rich Element (ARE)-containing human mRNA database into the transcriptomes of mouse and rat. As a result, we performed quantitative assessment of ARE conservation in human, mouse and rat transcripts. We found that a significant proportion ( approximately 25%) of human genes differ in their ARE patterns from mouse and rat transcripts. ARED-Integrated, another updated and expanded version of ARED, is a compilation of ARED versions 1.0 to 3.0 and updated version 4.0 that is devoted to human mRNAs. Thus, ARED-Integrated and ARED-Organism databases, both publicly available at http://brp.kfshrc.edu.sa/ARED, offer scientists a comprehensive view of AREs in the human transcriptome and the ability to study the comparative genomics of AREs in model organisms. This ultimately will help in inferring the biological consequences of ARE variation in these key animal models as opposed to humans, particularly, in relationships to the role of RNA stability in disease.

  • Identification of a set of KSRP target transcripts upregulated by PI3K-AKT signaling.
    BMC molecular biology, 2007
    Co-Authors: Tina Ruggiero, Khalid S.a. Khabar, Ching Yi Chen, Michele Trabucchi, Marco Ponassi, Giorgio Corte, Latifa Al-haj, Paola Briata, Roberto Gherzi
    Abstract:

    Background KSRP is a AU-rich Element (ARE) binding protein that causes decay of select sets of transcripts in different cell types. We have recently described that phosphatidylinositol 3-kinase/AKT (PI3K-AKT) activation induces stabilization and accumulation of the labile β-catenin mRNA through an impairment of KSRP function.

Véronique Kruys - One of the best experts on this subject based on the ideXlab platform.

  • dTIS11 Protein-dependent polysomal deadenylation is the key step in AU-rich Element-mediated mRNA decay in Drosophila cells.
    The Journal of biological chemistry, 2012
    Co-Authors: Caroline Vindry, Véronique Kruys, Aurélien Lauwers, David Hutin, Romuald Soin, Corinne Wauquier, Cyril Gueydan
    Abstract:

    The destabilization of AU-rich Element (ARE)-containing mRNAs mediated by proteins of the TIS11 family is conserved among eukaryotes including Drosophila. Previous studies have demonstrated that Tristetraprolin, a human protein of the TIS11 family, induces the degradation of ARE-containing mRNAs through a large variety of mechanisms including deadenylation, decapping, and P-body targeting. We have previously shown that the degradation of the mRNA encoding the antimicrobial peptide Cecropin A1 (CecA1) is controlled by the TIS11 protein (dTIS11) in Drosophila cells. In this study, we used CecA1 mRNA as a model to investigate the molecular mechanism of dTIS11-mediated mRNA decay. We observed that during the biphasic deadenylation and decay process of this mRNA, dTIS11 enhances deadenylation performed by the CCR4-CAF-NOT complex while the mRNA is still associated with ribosomes. Sequencing of mRNA degradation intermediates revealed that the complete deadenylation of the mRNA triggers its decapping and decay in both the 5′-3′ and the 3′-5′ directions. Contrary to the observations made for its mammalian homologs, overexpression of dTIS11 does not promote the localization of ARE-containing mRNAs in P-bodies but rather decreases the accumulation of CecA1 mRNA in these structures by enhancing the degradation process. Therefore, our results suggest that proteins of the TIS11 family may have acquired additional functions in the course of evolution from invertebrates to mammals.

  • Deadenylation of interferon-beta mRNA is mediated by both the AU-rich Element in the 3'-untranslated region and an instability sequence in the coding region.
    European journal of biochemistry, 2003
    Co-Authors: Muriel Paste, Georges Huez, Véronique Kruys
    Abstract:

    Viral infection of fibroblastic and endothelial cells leads to the transient synthesis of interferon-beta (IFN-beta). The down-regulation of IFN-beta synthesis after infection results both from transcriptional repression of the IFN-beta gene and rapid degradation of mRNA. As with many cytokine mRNAs, IFN-beta mRNA contains an AU-rich Element (ARE) in its 3'-untranslated region (UTR). AREs are known to mediate mRNA deadenylation and destabilization. Depending on the class of ARE, deadenylation was shown to occur through synchronous or asynchronous mechanisms. In this study, we analysed IFN-beta mRNA deadenylation in natural conditions of IFN-beta synthesis, e.g., after viral infection. We show that human IFN-beta mRNA follows an asynchronous deadenylation pathway typical of a mRNA containing a class II ARE. A deletion analysis of the IFN-beta natural transcript demonstrates that poly(A) shortening can be mediated by the ARE but also by a 32 nucleotide-sequence located in the coding region, that was identified previously as an instability determinant. In fact, these Elements are able to act independently as both of them have to be removed to abrogate mRNA deadenylation. Our data also indicate that deadenylation occurs independently of mRNA translation. Moreover, we show that deadenylation of IFN-beta mRNA is not under the control of viral infection as IFN-beta mRNA derived from a constitutively expressed gene cassette is deadenylated in absence of viral infection. Finally, an unidentified nuclear event appears to be a prerequisite for IFN-beta mRNA deadenylation as IFN-beta mRNA introduced directly into the cytoplasm does not undergo deadenylation. In conclusion, our study demonstrates that IFN-beta mRNA poly(A) shortening is under the control of two cis-acting Elements recruiting a deadenylating machinery whose activity is independent of translation and viral infection but might require a nuclear event.

  • AU-rich Element-mediated translational control: complexity and multiple activities of trans-activating factors.
    Biochemical Society Transactions, 2002
    Co-Authors: Tong Zhang, Véronique Kruys, Georges Huez, Cyril Gueydan
    Abstract:

    Tumour necrosis factor (TNF)-alpha mRNA contains an AU-rich Element (ARE) in its 3' untranslated region (3'UTR), which determines its half-life and translational efficiency. In unstimulated macrophages, TNF-alpha mRNA is repressed translationally, and becomes efficiently translated upon cell activation. Gel retardation experiments and screening of a macrophage cDNA expression library with the TNF-alpha ARE allowed the identification of TIA-1-related protein (TIAR), T-cell intracellular antigen-1 (TIA-1) and tristetraprolin (TTP) as TNF-alpha ARE-binding proteins. Whereas TIAR and TIA-1 bind the TNF-alpha ARE independently of the activation state of macrophages, the TTP-ARE complex is detectable upon stimulation with lipopolysaccharide (LPS). Moreover, treatment of LPS-induced macrophage extracts with phosphatase significantly abrogates TTP binding to the TNF-alpha ARE, indicating that TTP phosphorylation is required for ARE binding. Carballo, Lai and Blackshear [(1998) Science 281, 1001-1005] showed that TTP was a TNF-alpha mRNA destabilizer. In contrast, TIA-1, and most probably TIAR, acts as a TNF-alpha mRNA translational silencer. A two-hybrid screening with TIAR and TIA-1 revealed the capacity of these proteins to interact with other RNA-binding proteins. Interestingly, TIAR and TIA-1 are not engaged in the same interaction, indicating for the first time that TIAR and TIA-1 can be functionally distinct. These findings also suggest that ARE-binding proteins interact with RNA as multimeric complexes, which might define their function and their sequence specificity.

  • Regulated control by granulocyte-macrophage colony-stimulating factor AU-rich Element during mouse embryogenesis
    Blood, 2001
    Co-Authors: Laurent Houzet, Georges Huez, Dominique Morello, Patrick Defrance, Pascale Mercier, Véronique Kruys
    Abstract:

    In vitro studies have indicated that the granulocyte-macrophage colony-stimulating factor (GM-CSF) gene expression is regulated at the posttranscriptional level by the AU-rich Element (ARE) sequence present in its 3′ untranslated region (UTR). This study investigated the importance of the ARE in the control of GM-CSF gene expression in vivo. For this purpose, transgenic mice bearing GM-CSF gene constructs containing or lacking the ARE (GM-CSF AU+ or GM-CSF AU−, respectively) were generated. Both transgenes were under the transcriptional control of the immediate early promoter of the cytomegalovirus (CMV) to ensure their early, widespread, and constitutive expression. The regulation imposed by the ARE was revealed by comparing transgene expression at day 14 of embryonic development (E14); only the ARE-deleted but not the ARE-containing construct was expressed. Although GM-CSF AU+ embryos were phenotypically normal, overexpression of GM-CSF in E14 GM-CSF AU− embryos led to severe hematopoietic alterations such as abnormal proliferation of granulocytes and macrophages accompanied by an increased number of peroxidase-expressing cells, their putative progenitor cells. These abnormalities compromise development because no viable GM-CSF AU− transgenic pups could be obtained. Surprisingly, by E18, significant accumulation of transgene messenger RNA was also observed in GM-CSF AU+ embryos leading to similar phenotypic abnormalities. Altogether, these observations reveal that GM-CSF ARE is a developmentally controlled regulatory Element and highlight the consequences of GM-CSF overexpression on myeloid cell proliferation and differentiation.

  • Identification of TIAR as a protein binding to the translational regulatory AU-rich Element of tumor necrosis factor α mRNA
    The Journal of biological chemistry, 1999
    Co-Authors: Cyril Gueydan, Georges Huez, Louis Droogmans, Pascale Chalon, Daniel Caput, Véronique Kruys
    Abstract:

    In monocyte/macrophages, the translation of tumor necrosis factor alpha (TNF-alpha) mRNA is tightly regulated. In unstimulated cells, translation of TNF-alpha mRNA is blocked. Upon stimulation with lipopolysaccharides, this repression is overcome, and the mRNA becomes efficiently translated. The key Element in this regulation is the AU-rich Element (ARE). We have previously reported the binding of two cytosolic protein complexes to the TNF-alpha mRNA ARE. One of these complexes (complex 1) forms with extracts of both unstimulated and lipopolysaccharide-stimulated macrophages and requires a large fragment of the ARE containing clustered AUUUA pentamers. The other complex (complex 2) is only detected after cell activation, binds to a minimal UUAUUUAUU nonamer, and is composed of a 55-kDa protein. Here, we report the identification of the RNA-binding protein TIAR as a protein involved in complex 1. The RNA sequence bound by TIAR and the cytoplasmic localization of this protein in macrophages argue for an involvement of TIAR in TNF mRNA posttranscriptional regulation.

Fumihiro Higashino - One of the best experts on this subject based on the ideXlab platform.

  • Viral-mediated stabilization of AU-rich Element containing mRNA contributes to cell transformation
    Oncogene, 2011
    Co-Authors: Takeshi Kuroshima, Mariko Aoyagi, Motoaki Yasuda, Tetsuya Kitamura, Jumond P. Jehung, Makoto Ishikawa, Yoshimasa Kitagawa, Yasunori Totsuka, Masanobu Shindoh, Fumihiro Higashino
    Abstract:

    E4orf6 is one of the oncogene products of adenovirus, and it also has an important role for transportation of cellular and viral messenger RNA (mRNA) during the late phase of virus infection. We previously revealed that E4orf6 controls the fate of AU-rich Element (ARE) containing mRNA by perturbing the chromosome maintenance region 1-dependent export mechanism. Here, we show that E4orf6 stabilizes ARE–mRNA through the region required for its oncogenic activity and ubiquitin E3 ligase assembly. Cells that failed to stabilize ARE–mRNA after HuR knockdown were unable to produce colonies in soft agar, even when E4orf6 was expressed. Furthermore, the stabilized ARE–mRNA induced the transformation of rodent immortalized cells. These findings indicate that stabilized ARE–mRNA is necessary, if not all, for the oncogenic activity of E4orf6 and has the potential to transform cells, at least under a certain condition.

  • Viral-mediated stabilization of AU-rich Element containing mRNA contributes to cell transformation.
    Oncogene, 2011
    Co-Authors: Takeshi Kuroshima, Mariko Aoyagi, Motoaki Yasuda, Tetsuya Kitamura, Jumond P. Jehung, Makoto Ishikawa, Yoshimasa Kitagawa, Yasunori Totsuka, Masanobu Shindoh, Fumihiro Higashino
    Abstract:

    Viral-mediated stabilization of AU-rich Element containing mRNA contributes to cell transformation

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