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Sample records for factor i-a represses

  1. DNA residence time is a regulatory factor of transcription repression.

    Science.gov (United States)

    Clauß, Karen; Popp, Achim P; Schulze, Lena; Hettich, Johannes; Reisser, Matthias; Escoter Torres, Laura; Uhlenhaut, N Henriette; Gebhardt, J Christof M

    2017-08-21

    Transcription comprises a highly regulated sequence of intrinsically stochastic processes, resulting in bursts of transcription intermitted by quiescence. In transcription activation or repression, a transcription factor binds dynamically to DNA, with a residence time unique to each factor. Whether the DNA residence time is important in the transcription process is unclear. Here, we designed a series of transcription repressors differing in their DNA residence time by utilizing the modular DNA binding domain of transcription activator-like effectors (TALEs) and varying the number of nucleotide-recognizing repeat domains. We characterized the DNA residence times of our repressors in living cells using single molecule tracking. The residence times depended non-linearly on the number of repeat domains and differed by more than a factor of six. The factors provoked a residence time-dependent decrease in transcript level of the glucocorticoid receptor-activated gene SGK1. Down regulation of transcription was due to a lower burst frequency in the presence of long binding repressors and is in accordance with a model of competitive inhibition of endogenous activator binding. Our single molecule experiments reveal transcription factor DNA residence time as a regulatory factor controlling transcription repression and establish TALE-DNA binding domains as tools for the temporal dissection of transcription regulation. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  2. Musashi mediates translational repression of the Drosophila hypoxia inducible factor

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    Bertolin, Agustina P.; Katz, Maximiliano J.; Yano, Masato; Pozzi, Berta; Acevedo, Julieta M.; Blanco-Obregón, Dalmiro; Gándara, Lautaro; Sorianello, Eleonora; Kanda, Hiroshi; Okano, Hideyuki; Srebrow, Anabella; Wappner, Pablo

    2016-01-01

    Adaptation to hypoxia depends on a conserved α/β heterodimeric transcription factor called Hypoxia Inducible Factor (HIF), whose α-subunit is regulated by oxygen through different concurrent mechanisms. In this study, we have identified the RNA binding protein dMusashi, as a negative regulator of the fly HIF homologue Sima. Genetic interaction assays suggested that dMusashi participates of the HIF pathway, and molecular studies carried out in Drosophila cell cultures showed that dMusashi recognizes a Musashi Binding Element in the 3′ UTR of the HIFα transcript, thereby mediating its translational repression in normoxia. In hypoxic conditions dMusashi is downregulated, lifting HIFα repression and contributing to trigger HIF-dependent gene expression. Analysis performed in mouse brains revealed that murine Msi1 protein physically interacts with HIF-1α transcript, suggesting that the regulation of HIF by Msi might be conserved in mammalian systems. Thus, Musashi is a novel regulator of HIF that inhibits responses to hypoxia specifically when oxygen is available. PMID:27141964

  3. Systematic repression of transcription factors reveals limited patterns of gene expression changes in ES cells

    Science.gov (United States)

    Nishiyama, Akira; Sharov, Alexei A.; Piao, Yulan; Amano, Misa; Amano, Tomokazu; Hoang, Hien G.; Binder, Bernard Y.; Tapnio, Richard; Bassey, Uwem; Malinou, Justin N.; Correa-Cerro, Lina S.; Yu, Hong; Xin, Li; Meyers, Emily; Zalzman, Michal; Nakatake, Yuhki; Stagg, Carole; Sharova, Lioudmila; Qian, Yong; Dudekula, Dawood; Sheer, Sarah; Cadet, Jean S.; Hirata, Tetsuya; Yang, Hsih-Te; Goldberg, Ilya; Evans, Michele K.; Longo, Dan L.; Schlessinger, David; Ko, Minoru S. H.

    2013-01-01

    Networks of transcription factors (TFs) are thought to determine and maintain the identity of cells. Here we systematically repressed each of 100 TFs with shRNA and carried out global gene expression profiling in mouse embryonic stem (ES) cells. Unexpectedly, only the repression of a handful of TFs significantly affected transcriptomes, which changed in two directions/trajectories: one trajectory by the repression of either Pou5f1 or Sox2; the other trajectory by the repression of either Esrrb, Sall4, Nanog, or Tcfap4. The data suggest that the trajectories of gene expression change are already preconfigured by the gene regulatory network and roughly correspond to extraembryonic and embryonic fates of cell differentiation, respectively. These data also indicate the robustness of the pluripotency gene network, as the transient repression of most TFs did not alter the transcriptomes. PMID:23462645

  4. Plant NAC-type transcription factor proteins contain a NARD domain for repression of transcriptional activation.

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    Hao, Yu-Jun; Song, Qing-Xin; Chen, Hao-Wei; Zou, Hong-Feng; Wei, Wei; Kang, Xu-Sheng; Ma, Biao; Zhang, Wan-Ke; Zhang, Jin-Song; Chen, Shou-Yi

    2010-10-01

    Plant-specific transcription factor NAC proteins play essential roles in many biological processes such as development, senescence, morphogenesis, and stress signal transduction pathways. In the NAC family, some members function as transcription activators while others act as repressors. In the present study we found that though the full-length GmNAC20 from soybean did not have transcriptional activation activity, the carboxy-terminal activation domain of GmNAC20 had high transcriptional activation activity in the yeast assay system. Deletion experiments revealed an active repression domain with 35 amino acids, named NARD (NAC Repression Domain), in the d subdomain of NAC DNA-binding domain. NARD can reduce the transcriptional activation ability of diverse transcription factors when fused to either the amino-terminal or the carboxy-terminal of the transcription factors. NARD-like sequences are also present in other NAC family members and they are functional repression domain when fused to VP16 in plant protoplast assay system. Mutation analysis of conserved amino acid residues in NARD showed that the hydrophobic LVFY motif may partially contribute to the repression function. It is hypothesized that the interactions between the repression domain NARD and the carboxy-terminal activation domain may finally determine the ability of NAC family proteins to regulate downstream gene expressions.

  5. Derangement of a factor upstream of RARalpha triggers the repression of a pleiotropic epigenetic network.

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    Francesca Corlazzoli

    Full Text Available BACKGROUND: Chromatin adapts and responds to extrinsic and intrinsic cues. We hypothesize that inheritable aberrant chromatin states in cancer and aging are caused by genetic/environmental factors. In previous studies we demonstrated that either genetic mutations, or loss, of retinoic acid receptor alpha (RARalpha, can impair the integration of the retinoic acid (RA signal at the chromatin of RA-responsive genes downstream of RARalpha, and can lead to aberrant repressive chromatin states marked by epigenetic modifications. In this study we tested whether the mere interference with the availability of RA signal at RARalpha, in cells with an otherwise functional RARalpha, can also induce epigenetic repression at RA-responsive genes downstream of RARalpha. METHODOLOGY/PRINCIPAL FINDINGS: To hamper the availability of RA at RARalpha in untransformed human mammary epithelial cells, we targeted the cellular RA-binding protein 2 (CRABP2, which transports RA from the cytoplasm onto the nuclear RARs. Stable ectopic expression of a CRABP2 mutant unable to enter the nucleus, as well as stable knock down of endogenous CRABP2, led to the coordinated transcriptional repression of a few RA-responsive genes downstream of RARalpha. The chromatin at these genes acquired an exacerbated repressed state, or state "of no return". This aberrant state is unresponsive to RA, and therefore differs from the physiologically repressed, yet "poised" state, which is responsive to RA. Consistent with development of homozygosis for epigenetically repressed loci, a significant proportion of cells with a defective CRABP2-mediated RA transport developed heritable phenotypes indicative of loss of function. CONCLUSION/SIGNIFICANCE: Derangement/lack of a critical factor necessary for RARalpha function induces epigenetic repression of a RA-regulated gene network downstream of RARalpha, with major pleiotropic biological outcomes.

  6. Pluripotency factors and Polycomb Group proteins repress aryl hydrocarbon receptor expression in murine embryonic stem cells

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    Chia-I Ko

    2014-01-01

    Full Text Available The aryl hydrocarbon receptor (AHR is a transcription factor and environmental sensor that regulates expression of genes involved in drug-metabolism and cell cycle regulation. Chromatin immunoprecipitation analyses, Ahr ablation in mice and studies with orthologous genes in invertebrates suggest that AHR may also play a significant role in embryonic development. To address this hypothesis, we studied the regulation of Ahr expression in mouse embryonic stem cells and their differentiated progeny. In ES cells, interactions between OCT3/4, NANOG, SOX2 and Polycomb Group proteins at the Ahr promoter repress AHR expression, which can also be repressed by ectopic expression of reprogramming factors in hepatoma cells. In ES cells, unproductive RNA polymerase II binds at the Ahr transcription start site and drives the synthesis of short abortive transcripts. Activation of Ahr expression during differentiation follows from reversal of repressive marks in Ahr promoter chromatin, release of pluripotency factors and PcG proteins, binding of Sp factors, establishment of histone marks of open chromatin, and engagement of active RNAPII to drive full-length RNA transcript elongation. Our results suggest that reversible Ahr repression in ES cells holds the gene poised for expression and allows for a quick switch to activation during embryonic development.

  7. Sucrose-induced translational repression of plant bZIP-type transcription factors

    NARCIS (Netherlands)

    Wiese, A.; Elzinga, N.; Wobbes, B.; Smeekens, S.

    2005-01-01

    Sugars as signalling molecules exert control on the transcription of many plant genes. Sugar signals also alter mRNA and protein stability. Increased sucrose concentrations specifically repress translation of the S-class basic region leucine zipper (bZIP) type transcription factor AtbZIP11/ATB2. Thi

  8. Pluripotency factors and Polycomb Group proteins repress aryl hydrocarbon receptor expression in murine embryonic stem cells.

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    Ko, Chia-I; Wang, Qin; Fan, Yunxia; Xia, Ying; Puga, Alvaro

    2014-01-01

    The aryl hydrocarbon receptor (AHR) is a transcription factor and environmental sensor that regulates expression of genes involved in drug-metabolism and cell cycle regulation. Chromatin immunoprecipitation analyses, Ahr ablation in mice and studies with orthologous genes in invertebrates suggest that AHR may also play a significant role in embryonic development. To address this hypothesis, we studied the regulation of Ahr expression in mouse embryonic stem cells and their differentiated progeny. In ES cells, interactions between OCT3/4, NANOG, SOX2 and Polycomb Group proteins at the Ahr promoter repress AHR expression, which can also be repressed by ectopic expression of reprogramming factors in hepatoma cells. In ES cells, unproductive RNA polymerase II binds at the Ahr transcription start site and drives the synthesis of short abortive transcripts. Activation of Ahr expression during differentiation follows from reversal of repressive marks in Ahr promoter chromatin, release of pluripotency factors and PcG proteins, binding of Sp factors, establishment of histone marks of open chromatin, and engagement of active RNAPII to drive full-length RNA transcript elongation. Our results suggest that reversible Ahr repression in ES cells holds the gene poised for expression and allows for a quick switch to activation during embryonic development.

  9. Polycomb complex 2 is required for E-cadherin repression by the Snail1 transcription factor

    DEFF Research Database (Denmark)

    Herranz, Nicolás; Pasini, Diego; Díaz, Víctor M

    2008-01-01

    The transcriptional factor Snail1 is a repressor of E-cadherin gene (CDH1) expression essential for triggering epithelial-mesenchymal transition (EMT). Snail1 represses CDH1 directly binding its promoter and inducing the synthesis of Zeb1 repressor. In this article we show that repression of CDH1...... by Snail1, but not by Zeb1, is dependent on the activity of the Polycomb repressive complex 2 (PRC2). ES cells null for Suz12, one of the components of PRC2, show higher levels of Cdh1 mRNA than control ES cells. In tumour cells, interference of PRC2 activity prevents the ability of Snail1 to down......-regulate CDH1 and partially de-represses CDH1. Chromatin immunoprecipitation assays demonstrated that Snail1 increases the binding of Suz12 to CDH1 promoter and the tri-methylation of lysine 27 in the histone 3. Moreover, Snail1 interacts with Suz12 and Ezh2 as shown by coimmunoprecipitation experiments...

  10. Combinatorial activation and repression by seven transcription factors specify Drosophila odorant receptor expression.

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    Shadi Jafari

    Full Text Available The mechanism that specifies olfactory sensory neurons to express only one odorant receptor (OR from a large repertoire is critical for odor discrimination but poorly understood. Here, we describe the first comprehensive analysis of OR expression regulation in Drosophila. A systematic, RNAi-mediated knock down of most of the predicted transcription factors identified an essential function of acj6, E93, Fer1, onecut, sim, xbp1, and zf30c in the regulation of more than 30 ORs. These regulatory factors are differentially expressed in antennal sensory neuron classes and specifically required for the adult expression of ORs. A systematic analysis reveals not only that combinations of these seven factors are necessary for receptor gene expression but also a prominent role for transcriptional repression in preventing ectopic receptor expression. Such regulation is supported by bioinformatics and OR promoter analyses, which uncovered a common promoter structure with distal repressive and proximal activating regions. Thus, our data provide insight into how combinatorial activation and repression can allow a small number of transcription factors to specify a large repertoire of neuron classes in the olfactory system.

  11. Repression of CIITA by the Epstein-Barr virus transcription factor Zta is independent of its dimerization and DNA binding.

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    Balan, Nicolae; Osborn, Kay; Sinclair, Alison J

    2016-03-01

    Repression of the cellular CIITA gene is part of the immune evasion strategy of the γherpes virus Epstein-Barr virus (EBV) during its lytic replication cycle in B-cells. In part, this is mediated through downregulation of MHC class II gene expression via the targeted repression of CIITA, the cellular master regulator of MHC class II gene expression. This repression is achieved through a reduction in CIITA promoter activity, initiated by the EBV transcription and replication factor, Zta (BZLF1, EB1, ZEBRA). Zta is the earliest gene expressed during the lytic replication cycle. Zta interacts with sequence-specific elements in promoters, enhancers and the replication origin (ZREs), and also modulates gene expression through interaction with cellular transcription factors and co-activators. Here, we explore the requirements for Zta-mediated repression of the CIITA promoter. We find that repression by Zta is specific for the CIITA promoter and can be achieved in the absence of other EBV genes. Surprisingly, we find that the dimerization region of Zta is not required to mediate repression. This contrasts with an obligate requirement of this region to correctly orientate the DNA contact regions of Zta to mediate activation of gene expression through ZREs. Additional support for the model that Zta represses the CIITA promoter without direct DNA binding comes from promoter mapping that shows that repression does not require the presence of a ZRE in the CIITA promoter.

  12. Germ cell nuclear factor directly represses the transcription of peroxisome proliferator-activated receptor delta gene

    Institute of Scientific and Technical Information of China (English)

    Chengqiang He; Naizheng Ding; Jie Kang

    2008-01-01

    Germ cell nuclear factor (GCNF) is a transcription factor that can repress gene transcription and plays an important role during spermatogenesis. Peroxisome proliferator-activated receptor delta (PPARδ) is a nuclear hormone receptor belonging to the steroid receptor superfamily.It can activate the expression of many genes,including those involved in lipid metabolism.In this report,we showed that GCNF specifically interacts with PPARδ promoter.Overexpression of GCNF in African green monkey SV40 transformed kidney fibroblast COS7 cells and mouse embryo fibroblast NIH 3T3 cells represses the activity of PPARδ promoter.The mutation of GCNF response element in PPARδ promoter relieves the repression in NIH 3T3 cells and mouse testis.Moreover,we showed that GCNF in nuclear extracts of mouse testis is able to bind to PPARδ promoter directly.We also found that GCNF and PPARδ mRNA were expressed with different patterns in mouse testis by in situ hybridization.These results suggested that GCNF might be a negative regulator of PPARδ gene expression through its direct interaction with PPARδ promoter in mouse testis.

  13. Dominant Repression by Arabidopsis Transcription Factor MYB44 Causes Oxidative Damage and Hypersensitivity to Abiotic Stress

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    Helene Persak

    2014-02-01

    Full Text Available In any living species, stress adaptation is closely linked with major changes of the gene expression profile. As a substrate protein of the rapidly stress-induced mitogen-activated protein kinase MPK3, Arabidopsis transcription factor MYB44 likely acts at the front line of stress-induced re-programming. We recently characterized MYB44 as phosphorylation-dependent positive regulator of salt stress signaling. Molecular events downstream of MYB44 are largely unknown. Although MYB44 binds to the MBSII element in vitro, it has no discernible effect on MBSII-driven reporter gene expression in plant co-transfection assays. This may suggest limited abundance of a synergistic co-regulator. MYB44 carries a putative transcriptional repression (Ethylene responsive element binding factor-associated Amphiphilic Repression, EAR motif. We employed a dominant repressor strategy to gain insights into MYB44-conferred stress resistance. Overexpression of a MYB44-REP fusion markedly compromised salt and drought stress tolerance—the opposite was seen in MYB44 overexpression lines. MYB44-mediated resistance likely results from induction of tolerance-enhancing, rather than from repression of tolerance-diminishing factors. Salt stress-induced accumulation of destructive reactive oxygen species is efficiently prevented in transgenic MYB44, but accelerated in MYB44-REP lines. Furthermore, heterologous overexpression of MYB44-REP caused tissue collapse in Nicotiana. A mechanistic model of MAPK-MYB-mediated enhancement in the antioxidative capacity and stress tolerance is proposed. Genetic engineering of MYB44 variants with higher trans-activating capacity may be a means to further raise stress resistance in crops.

  14. A general strategy for cellular reprogramming: the importance of transcription factor cross-repression.

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    Crespo, Isaac; Del Sol, Antonio

    2013-10-01

    Transcription factor cross-repression is an important concept in cellular differentiation. A bistable toggle switch constitutes a molecular mechanism that determines cellular commitment and provides stability to transcriptional programs of binary cell fate choices. Experiments support that perturbations of these toggle switches can interconvert these binary cell fate choices, suggesting potential reprogramming strategies. However, more complex types of cellular transitions could involve perturbations of combinations of different types of multistable motifs. Here, we introduce a method that generalizes the concept of transcription factor cross-repression to systematically predict sets of genes, whose perturbations induce cellular transitions between any given pair of cell types. Furthermore, to our knowledge, this is the first method that systematically makes these predictions without prior knowledge of potential candidate genes and pathways involved, providing guidance on systems where little is known. Given the increasing interest of cellular reprogramming in medicine and basic research, our method represents a useful computational methodology to assist researchers in the field in designing experimental strategies.

  15. Yeast genetic analysis reveals the involvement of chromatin reassembly factors in repressing HIV-1 basal transcription.

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    Manuela Vanti

    2009-01-01

    Full Text Available Rebound of HIV viremia after interruption of anti-retroviral therapy is due to the small population of CD4+ T cells that remain latently infected. HIV-1 transcription is the main process controlling post-integration latency. Regulation of HIV-1 transcription takes place at both initiation and elongation levels. Pausing of RNA polymerase II at the 5' end of HIV-1 transcribed region (5'HIV-TR, which is immediately downstream of the transcription start site, plays an important role in the regulation of viral expression. The activation of HIV-1 transcription correlates with the rearrangement of a positioned nucleosome located at this region. These two facts suggest that the 5'HIV-TR contributes to inhibit basal transcription of those HIV-1 proviruses that remain latently inactive. However, little is known about the cell elements mediating the repressive role of the 5'HIV-TR. We performed a genetic analysis of this phenomenon in Saccharomyces cerevisiae after reconstructing a minimal HIV-1 transcriptional system in this yeast. Unexpectedly, we found that the critical role played by the 5'HIV-TR in maintaining low levels of basal transcription in yeast is mediated by FACT, Spt6, and Chd1, proteins so far associated with chromatin assembly and disassembly during ongoing transcription. We confirmed that this group of factors plays a role in HIV-1 postintegration latency in human cells by depleting the corresponding human orthologs with shRNAs, both in HIV latently infected cell populations and in particular single-integration clones, including a latent clone with a provirus integrated in a highly transcribed gene. Our results indicate that chromatin reassembly factors participate in the establishment of the equilibrium between activation and repression of HIV-1 when it integrates into the human genome, and they open the possibility of considering these factors as therapeutic targets of HIV-1 latency.

  16. Wild type p53 transcriptionally represses the SALL2 transcription factor under genotoxic stress.

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    Carlos Farkas

    Full Text Available SALL2- a member of the Spalt gene family- is a poorly characterized transcription factor found deregulated in various cancers, which suggests it plays a role in the disease. We previously identified SALL2 as a novel interacting protein of neurotrophin receptors and showed that it plays a role in neuronal function, which does not necessarily explain why or how SALL2 is deregulated in cancer. Previous evidences indicate that SALL2 gene is regulated by the WT1 and AP4 transcription factors. Here, we identified SALL2 as a novel downstream target of the p53 tumor suppressor protein. Bioinformatic analysis of the SALL2 gene revealed several putative p53 half sites along the promoter region. Either overexpression of wild-type p53 or induction of the endogenous p53 by the genotoxic agent doxorubicin repressed SALL2 promoter activity in various cell lines. However R175H, R249S, and R248W p53 mutants, frequently found in the tumors of cancer patients, were unable to repress SALL2 promoter activity, suggesting that p53 specific binding to DNA is important for the regulation of SALL2. Electrophoretic mobility shift assay demonstrated binding of p53 to one of the identified p53 half sites in the Sall2 promoter, and chromatin immunoprecipitation analysis confirmed in vivo interaction of p53 with the promoter region of Sall2 containing this half site. Importantly, by using a p53ER (TAM knockin model expressing a variant of p53 that is completely dependent on 4-hydroxy-tamoxifen for its activity, we show that p53 activation diminished SALL2 RNA and protein levels during genotoxic cellular stress in primary mouse embryo fibroblasts (MEFs and radiosensitive tissues in vivo. Thus, our finding indicates that p53 represses SALL2 expression in a context-specific manner, adding knowledge to the understanding of SALL2 gene regulation, and to a potential mechanism for its deregulation in cancer.

  17. Three WRKY transcription factors additively repress abscisic acid and gibberellin signaling in aleurone cells.

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    Zhang, Liyuan; Gu, Lingkun; Ringler, Patricia; Smith, Stanley; Rushton, Paul J; Shen, Qingxi J

    2015-07-01

    Members of the WRKY transcription factor superfamily are essential for the regulation of many plant pathways. Functional redundancy due to duplications of WRKY transcription factors, however, complicates genetic analysis by allowing single-mutant plants to maintain wild-type phenotypes. Our analyses indicate that three group I WRKY genes, OsWRKY24, -53, and -70, act in a partially redundant manner. All three showed characteristics of typical WRKY transcription factors: each localized to nuclei and yeast one-hybrid assays indicated that they all bind to W-boxes, including those present in their own promoters. Quantitative real time-PCR (qRT-PCR) analyses indicated that the expression levels of the three WRKY genes varied in the different tissues tested. Particle bombardment-mediated transient expression analyses indicated that all three genes repress the GA and ABA signaling in a dosage-dependent manner. Combination of all three WRKY genes showed additive antagonism of ABA and GA signaling. These results suggest that these WRKY proteins function as negative transcriptional regulators of GA and ABA signaling. However, different combinations of these WRKY genes can lead to varied strengths in suppression of their targets.

  18. Transforming growth factor-β1 signaling represses testicular steroidogenesis through cross-talk with orphan nuclear receptor Nur77.

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    Park, Eunsook; Song, Chin-Hee; Park, Jae-Il; Ahn, Ryun-Sup; Choi, Hueng-Sik; Ko, CheMyong; Lee, Keesook

    2014-01-01

    Transforming growth factor- β1 (TGF-β1) has been reported to inhibit luteinizing hormone (LH) mediated-steroidogenesis in testicular Leydig cells. However, the mechanism by which TGF-β1 controls the steroidogenesis in Leydig cells is not well understood. Here, we investigated the possibility that TGF-β1 represses steroidogenesis through cross-talk with the orphan nuclear receptor Nur77. Nur77, which is induced by LH/cAMP signaling, is one of major transcription factors that regulate the expression of steroidogenic genes in Leydig cells. TGF-β1 signaling inhibited cAMP-induced testosterone production and the expression of steroidogenic genes such as P450c17, StAR and 3β-HSD in mouse Leydig cells. Further, TGF-β1/ALK5 signaling repressed cAMP-induced and Nur77-activated promoter activity of steroidogenic genes. In addition, TGF-β1/ALK5-activated Smad3 repressed Nur77 transactivation of steroidogenic gene promoters by interfering with Nur77 binding to DNA. In primary Leydig cells isolated from Tgfbr2flox/flox Cyp17iCre mice, TGF-β1-mediated repression of cAMP-induced steroidogenic gene expression was significantly less than that in primary Leydig cells from Tgfbr2flox/flox mice. Taken together, these results suggest that TGF-β1/ALK5/Smad3 signaling represses the expression of steroidogenic genes via the suppression of Nur77 transactivation in testicular Leydig cells. These findings may provide a molecular mechanism involved in the TGF-β1-mediated repression of testicular steroidogenesis.

  19. AP-2{alpha} suppresses skeletal myoblast proliferation and represses fibroblast growth factor receptor 1 promoter activity

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    Mitchell, Darrion L. [Department of Cell Biology and Anatomy, Chicago Medical School, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064 (United States); DiMario, Joseph X., E-mail: joseph.dimario@rosalindfranklin.edu [Department of Cell Biology and Anatomy, Chicago Medical School, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064 (United States)

    2010-01-15

    Skeletal muscle development is partly characterized by myoblast proliferation and subsequent differentiation into postmitotic muscle fibers. Developmental regulation of expression of the fibroblast growth factor receptor 1 (FGFR1) gene is required for normal myoblast proliferation and muscle formation. As a result, FGFR1 promoter activity is controlled by multiple transcriptional regulatory proteins during both proliferation and differentiation of myogenic cells. The transcription factor AP-2{alpha} is present in nuclei of skeletal muscle cells and suppresses myoblast proliferation in vitro. Since FGFR1 gene expression is tightly linked to myoblast proliferation versus differentiation, the FGFR1 promoter was examined for candidate AP-2{alpha} binding sites. Mutagenesis studies indicated that a candidate binding site located at - 1035 bp functioned as a repressor cis-regulatory element. Furthermore, mutation of this site alleviated AP-2{alpha}-mediated repression of FGFR1 promoter activity. Chromatin immunoprecipitation studies demonstrated that AP-2{alpha} interacted with the FGFR1 promoter in both proliferating myoblasts and differentiated myotubes. In total, these results indicate that AP-2{alpha} is a transcriptional repressor of FGFR1 gene expression during skeletal myogenesis.

  20. The LBD12-1 Transcription Factor Suppresses Apical Meristem Size by Repressing Argonaute 10 Expression.

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    Ma, Weiwei; Wu, Fuqing; Sheng, Peike; Wang, Xiaole; Zhang, Zhe; Zhou, Kunneng; Zhang, Huan; Hu, Jinlong; Lin, Qibin; Cheng, Zhijun; Wang, Jiulin; Zhu, Shanshan; Zhang, Xin; Guo, Xiuping; Wang, Haiyang; Wu, Chuanyin; Zhai, Huqu; Wan, Jianmin

    2017-01-01

    The shoot apical meristem (SAM) consists of a population of multipotent cells that generates all aerial structures and regenerates itself. SAM maintenance and lateral organ development are regulated by several complex signaling pathways, in which the Argonaute gene-mediated pathway plays a key role. One Argonaute gene, AGO10, functions as a microRNA locker that attenuates miR165/166 activity and positively regulates shoot apical meristem development, but little is known about when and how AGO10 is regulated at the transcriptional level. In this work, we showed that transgenic rice plants overexpressing LBD12-1, an LBD family transcription factor, exhibited stunted growth, twisted leaves, abnormal anthers, and reduced SAM size. Further research revealed that LBD12-1 directly binds to the promoter region and represses the expression of AGO10. Overexpression of AGO10 in an LBD12-1 overexpression background rescued the growth defect phenotype of LBD12-1-overexpressing plants. The expression of LBD12-1 and its binding ability to the AGO10 promoter is induced by stress. lbd12-1 loss-of-function mutants showed similar phenotypes and SAM size to the wild type under normal conditions, but lbd12-1 had a larger SAM under salt stress. Our findings provide novel insights into the regulatory mechanism of AGO10 by which SAM size is controlled under stress conditions. © 2017 American Society of Plant Biologists. All Rights Reserved.

  1. Characterization of an Nmr homolog that modulates GATA factor-mediated nitrogen metabolite repression in Cryptococcus neoformans.

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    I Russel Lee

    Full Text Available Nitrogen source utilization plays a critical role in fungal development, secondary metabolite production and pathogenesis. In both the Ascomycota and Basidiomycota, GATA transcription factors globally activate the expression of catabolic enzyme-encoding genes required to degrade complex nitrogenous compounds. However, in the presence of preferred nitrogen sources such as ammonium, GATA factor activity is inhibited in some species through interaction with co-repressor Nmr proteins. This regulatory phenomenon, nitrogen metabolite repression, enables preferential utilization of readily assimilated nitrogen sources. In the basidiomycete pathogen Cryptococcus neoformans, the GATA factor Gat1/Are1 has been co-opted into regulating multiple key virulence traits in addition to nitrogen catabolism. Here, we further characterize Gat1/Are1 function and investigate the regulatory role of the predicted Nmr homolog Tar1. While GAT1/ARE1 expression is induced during nitrogen limitation, TAR1 transcription is unaffected by nitrogen availability. Deletion of TAR1 leads to inappropriate derepression of non-preferred nitrogen catabolic pathways in the simultaneous presence of favoured sources. In addition to exhibiting its evolutionary conserved role of inhibiting GATA factor activity under repressing conditions, Tar1 also positively regulates GAT1/ARE1 transcription under non-repressing conditions. The molecular mechanism by which Tar1 modulates nitrogen metabolite repression, however, remains open to speculation. Interaction between Tar1 and Gat1/Are1 was undetectable in a yeast two-hybrid assay, consistent with Tar1 and Gat1/Are1 each lacking the conserved C-terminus regions present in ascomycete Nmr proteins and GATA factors that are known to interact with each other. Importantly, both Tar1 and Gat1/Are1 are suppressors of C. neoformans virulence, reiterating and highlighting the paradigm of nitrogen regulation of pathogenesis.

  2. The Epidermal Growth Factor Receptor Responsive miR-125a Represses Mesenchymal Morphology in Ovarian Cancer Cells

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    Karen D. Cowden Dahl

    2009-11-01

    Full Text Available The epithelial-to-mesenchymal transition (EMT that occurs during embryonic development is recapitulated during tumor metastasis. Important regulators of this process include growth factors, transcription factors, and adhesion molecules. New evidence suggests that microRNA (miRNA activity contributes to metastatic progression and EMT; however, the mechanisms leading to altered miRNA expression during cancer progression remain poorly understood. Importantly, overexpression of the epidermal growth factor receptor (EGFR in ovarian cancer correlates with poor disease outcome and induces EMT in ovarian cancer cells. We report that EGFR signaling leads to transcriptional repression of the miRNA miR-125a through the ETS family transcription factor PEA3. Overexpression of miR-125a induces conversion of highly invasive ovarian cancer cells from a mesenchymal to an epithelial morphology, suggesting miR-125a is a negative regulator of EMT. We identify AT-rich interactive domain 3B (ARID3B as a target of miR-125a and demonstrate that ARID3B is overexpressed in human ovarian cancer. Repression of miR-125a through growth factor signaling represents a novel mechanism for regulating ovarian cancer invasive behavior.

  3. Insulin-like growth factor I: a biologic maturation indicator.

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    Ishaq, Ramy Abdul Rahman; Soliman, Sanaa Abou Zeid; Foda, Manal Yehya; Fayed, Mona Mohamed Salah

    2012-11-01

    Determination of the maturation level and the subsequent evaluation of growth potential during preadolescence and adolescence are important for optimal orthodontic treatment planning and timing. This study was undertaken to evaluate the applicability of insulin-like growth factor I (IGF-I) blood level as a maturation indicator by correlating it to the cervical vertebral maturation index. The study was conducted with 120 subjects, equally divided into 60 males (ages, 10-18 years) and 60 females (ages, 8-16 years). A lateral cephalometric radiograph and a blood sample were taken from each subject. For each subject, cervical vertebral maturation and IGF-I serum level were assessed. Mean values of IGF-I in each stage of cervical vertebral maturation were calculated, and the means in each stage were statistically compared with those of the other stages. The IGF-I mean value at each cervical vertebral maturation stage was statistically different from the mean values at the other stages. The highest mean values were observed in stage 4, followed by stage 5 in males and stage 3 in females. IGF-I serum level is a reliable maturation indicator that could be applied in orthodontic diagnosis. Copyright © 2012 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

  4. Repressing sulfate-reducing bacteria growth in the affusion system of oil field by changing ecological factors

    Institute of Scientific and Technical Information of China (English)

    SHAN Dan; MA Fang; WANG Chen; WEI Li; GUO Jing-bo

    2008-01-01

    Aiming at the corrosion issue of oil extraction equipments caused by sulfate-reducing bacteria (SRB) reproducing in oil field affusion system, we studied the dominant strains in the SRB community and the impact of four ecological factors on the growth of the dominant strains: temperature, pH, mineralization degree and concen-tration of PAM (Polyacrylamine). The feasibility of repressing the growth of SRB by changing ecological factors was also discussed. The results indicate that Desulfobacter (one genus of SRB) is the preponderant strains of the system, and the order of the effect of four ecological factors is pH>temperature>the concentrations of PAM>mineralization degree. The optimal pH for the highest growth rate of SRB is 8.0. No growth of SRB was observed when pH 12. The optimal temperature for the growth of SRB is 40 ℃ and the ecological amplitude is 20-50 ℃. The appropriate concentration values of PAM is 400 -800 mg/L, beyond of which the multiplication rate and growth quantity of cell decrease obviously. The effect of mineralization degree of SO42- ,HCO3- and Na+ on the growth of SRB has reached an extremely remarkable level, and the change of three ions' oncentration in water obviously effects SRB. The optimum values on the main ions in the system are Cl- of 200 mg/L, HCO3- of 900 mg/L,SO42- of 400 mg/L, Mg2+ of 60 mg/L and Na+ of 900 mg/L. Our results indicate that it is possible to repress the growth of SRB by changing the ecological factors in oil field affusion system.

  5. Repressive Tolerance

    DEFF Research Database (Denmark)

    Pedersen, Morten Jarlbæk

    2016-01-01

    to an administrative culture of repressive tolerance of organised interests: authorities listen but only reacts in a very limited sense. This bears in it the risk of jeopardising the knowledge transfer from societal actors to administrative ditto thus harming the consultation institutions’ potential for strengthening...

  6. MUC1-C Represses the Crumbs Complex Polarity Factor CRB3 and Downregulates the Hippo Pathway.

    Science.gov (United States)

    Alam, Maroof; Bouillez, Audrey; Tagde, Ashujit; Ahmad, Rehan; Rajabi, Hasan; Maeda, Takahiro; Hiraki, Masayuki; Suzuki, Yozo; Kufe, Donald

    2016-12-01

    Apical-basal polarity and epithelial integrity are maintained in part by the Crumbs (CRB) complex. The C--terminal subunit of MUC1 (MUC1-C) is a transmembrane protein that is expressed at the apical border of normal epithelial cells and aberrantly at high levels over the entire surface of their transformed counterparts. However, it is not known whether MUC1-C contributes to this loss of polarity that is characteristic of carcinoma cells. Here it is demonstrated that MUC1-C downregulates expression of the Crumbs complex CRB3 protein in triple-negative breast cancer (TNBC) cells. MUC1-C associates with ZEB1 on the CRB3 promoter and represses CRB3 transcription. Notably, CRB3 activates the core kinase cassette of the Hippo pathway, which includes LATS1 and LATS2. In this context, targeting MUC1-C was associated with increased phosphorylation of LATS1, consistent with activation of the Hippo pathway, which is critical for regulating cell contact, tissue repair, proliferation, and apoptosis. Also shown is that MUC1-C--mediated suppression of CRB3 and the Hippo pathway is associated with dephosphorylation and activation of the oncogenic YAP protein. In turn, MUC1-C interacts with YAP, promotes formation of YAP/β-catenin complexes, and induces the WNT target gene MYC. These data support a previously unrecognized pathway in which targeting MUC1-C in TNBC cells (i) induces CRB3 expression, (ii) activates the CRB3-driven Hippo pathway, (iii) inactivates YAP, and thereby (iv) suppresses YAP/β-catenin-mediated induction of MYC expression. These findings demonstrate a previously unrecognized role for the MUC1-C oncoprotein in the regulation of polarity and the Hippo pathway in breast cancer. Mol Cancer Res; 14(12); 1266-76. ©2016 AACR. ©2016 American Association for Cancer Research.

  7. Forced FOG1 expression in erythroleukemia cells: Induction of erythroid genes and repression of myelo-lymphoid transcription factor PU.1.

    Science.gov (United States)

    Fujiwara, Tohru; Sasaki, Katsuyuki; Saito, Kei; Hatta, Shunsuke; Ichikawa, Satoshi; Kobayashi, Masahiro; Okitsu, Yoko; Fukuhara, Noriko; Onishi, Yasushi; Harigae, Hideo

    2017-02-16

    The transcription factor GATA-1-interacting protein Friend of GATA-1 (FOG1) is essential for proper transcriptional activation and repression of GATA-1 target genes; yet, the mechanisms by which FOG1 exerts its activating and repressing functions remain unknown. Forced FOG1 expression in human K562 erythroleukemia cells induced the expression of erythroid genes (SLC4A1, globins) but repressed that of GATA-2 and PU.1. A quantitative chromatin immunoprecipitation (ChIP) analysis demonstrated increased GATA-1 chromatin occupancy at both FOG1-activated as well as FOG1-repressed gene loci. However, while TAL1 chromatin occupancy was significantly increased at FOG1-activated gene loci, it was significantly decreased at FOG1-repressed gene loci. When FOG1 was overexpressed in TAL1-knocked down K562 cells, FOG1-mediated activation of HBA, HBG, and SLC4A1 was significantly compromised by TAL1 knockdown, suggesting that FOG1 may require TAL1 to activate GATA-1 target genes. Promoter analysis and quantitative ChIP analysis demonstrated that FOG1-mediated transcriptional repression of PU.1 would be mediated through a GATA-binding element located at its promoter, accompanied by significantly decreased H3 acetylation at lysine 4 and 9 (K4 and K9) as well as H3K4 trimethylation. Our results provide important mechanistic insight into the role of FOG1 in the regulation of GATA-1-regulated genes and suggest that FOG1 has an important role in inducing cells to differentiate toward the erythroid lineage rather than the myelo-lymphoid one by repressing the expression of PU.1.

  8. Pharmacologic doses of ascorbic acid repress specificity protein (Sp) transcription factors and Sp-regulated genes in colon cancer cells.

    Science.gov (United States)

    Pathi, Satya S; Lei, Ping; Sreevalsan, Sandeep; Chadalapaka, Gayathri; Jutooru, Indira; Safe, Stephen

    2011-01-01

    Ascorbic acid (vitamin C) inhibits cancer cell growth, and there is a controversy regarding the cancer chemoprotective effects of pharmacologic doses of this compound that exhibits prooxidant activity. We hypothesized that the anticancer activity of pharmacologic doses of ascorbic acid (colon cancer cell proliferation and induced apoptosis and necrosis, and this was accompanied by downregulation of Sp1, Sp3, and Sp4 proteins. In addition, ascorbic acid decreased expression of several Sp-regulated genes that are involved in cancer cell proliferation [hepatocyte growth factor receptor (c-Met), epidermal growth factor receptor and cyclin D1], survival (survivin and bcl-2), and angiogenesis [vascular endothelial growth factor (VEGF) and its receptors (VEGFR1 and VEGFR2)]. Other prooxidants such as hydrogen peroxide exhibited similar activities in colon cancer cells, and cotreatment with glutathione inhibited these responses. This study demonstrates for the first time that the anticancer activities of ascorbic acid are due, in part, to ROS-dependent repression of Sp transcription factors.

  9. Kruppel-like factor-9 (KLF9) inhibits glioblastoma stemness through global transcription repression and integrin α6 inhibition.

    Science.gov (United States)

    Ying, Mingyao; Tilghman, Jessica; Wei, Yingying; Guerrero-Cazares, Hugo; Quinones-Hinojosa, Alfredo; Ji, Hongkai; Laterra, John

    2014-11-21

    It is increasingly important to understand the molecular basis for the plasticity of neoplastic cells and their capacity to transition between differentiated and stemlike phenotypes. Kruppel-like factor-9 (KLF9), a member of the large KLF transcription factor family, has emerged as a regulator of oncogenesis, cell differentiation, and neural development; however, the molecular basis for the diverse contextual functions of KLF9 remains unclear. This study focused on the functions of KLF9 in human glioblastoma stemlike cells. We established for the first time a genome-wide map of KLF9-regulated targets in human glioblastoma stemlike cells and show that KLF9 functions as a transcriptional repressor and thereby regulates multiple signaling pathways involved in oncogenesis and stem cell regulation. A detailed analysis of one such pathway, integrin signaling, showed that the capacity of KLF9 to inhibit glioblastoma cell stemness and tumorigenicity requires ITGA6 repression. These findings enhance our understanding of the transcriptional networks underlying cancer cell stemness and differentiation and identify KLF9-regulated molecular targets applicable to cancer therapeutics.

  10. Pro-brain-derived neurotrophic factor inhibits GABAergic neurotransmission by activating endocytosis and repression of GABAA receptors.

    Science.gov (United States)

    Riffault, Baptiste; Medina, Igor; Dumon, Camille; Thalman, Carine; Ferrand, Nadine; Friedel, Perrine; Gaiarsa, Jean-Luc; Porcher, Christophe

    2014-10-01

    GABA is the canonical inhibitory neurotransmitter in the CNS. This inhibitory action is largely mediated by GABA type A receptors (GABAARs). Among the many factors controlling GABAergic transmission, brain-derived neurotrophic factor (BDNF) appears to play a major role in regulating synaptic inhibition. Recent findings have demonstrated that BDNF can be released as a precursor (proBDNF). Although the role of mature BDNF on GABAergic synaptogenesis and maintenance has been well studied, an important question still unanswered is whether secreted proBDNF might affect GABAergic neurotransmission. Here, we have used 14 d in vitro primary culture of hippocampal neurons and ex vivo preparations from rats to study the function of proBDNF in regulation of GABAAR trafficking and activity. We demonstrate that proBDNF impairs GABAergic transmission by the activation of two distinct pathways: (1) a RhoA-Rock-PTEN pathway that decreases the phosphorylation levels of GABAAR, thus affecting receptor function and triggering endocytosis and degradation of internalized receptors, and (2) a JAK-STAT-ICER pathway leading to the repression of GABAARs synthesis. These effects lead to the diminution of GABAergic synapses and are correlated with a decrease in GABAergic synaptic currents. These results revealed new functions for proBDNF-p75 neurotrophin receptor signaling pathway in the control of the efficacy of GABAergic synaptic activity by regulating the trafficking and synthesis of GABAARs at inhibitory synapses.

  11. Zebrafish kruppel-like factor 4a represses intestinal cell proliferation and promotes differentiation of intestinal cell lineages.

    Directory of Open Access Journals (Sweden)

    I-Chen Li

    Full Text Available BACKGROUND: Mouse krüppel-like factor 4 (Klf4 is a zinc finger-containing transcription factor required for terminal differentiation of goblet cells in the colon. However, studies using either Klf4(-/- mice or mice with conditionally deleted Klf4 in their gastric epithelia showed different results in the role of Klf4 in epithelial cell proliferation. We used zebrafish as a model organism to gain further understanding of the role of Klf4 in the intestinal cell proliferation and differentiation. METHODOLOGY/PRINCIPAL FINDINGS: We characterized the function of klf4a, a mammalian klf4 homologue by antisense morpholino oligomer knockdown. Zebrafish Klf4a shared high amino acid similarities with human and mouse Klf4. Phylogenetic analysis grouped zebrafish Klf4a together with both human and mouse Klf4 in a branch with high bootstrap value. In zebrafish, we demonstrate that Klf4a represses intestinal cell proliferation based on results of BrdU incorporation, p-Histone 3 immunostaining, and transmission electron microscopy analyses. Decreased PepT1 expression was detected in intestinal bulbs of 80- and 102-hours post fertilization (hpf klf4a morphants. Significant reduction of alcian blue-stained goblet cell number was identified in intestines of 102- and 120-hpf klf4a morphants. Embryos treated with γ-secretase inhibitor showed increased klf4a expression in the intestine, while decreased klf4a expression and reduction in goblet cell number were observed in embryos injected with Notch intracellular domain (NICD mRNA. We were able to detect recovery of goblet cell number in 102-hpf embryos that had been co-injected with both klf4a and Notch 1a NICD mRNA. CONCLUSIONS/SIGNIFICANCE: This study provides in vivo evidence showing that zebrafih Klf4a is essential for the repression of intestinal cell proliferation. Zebrafish Klf4a is required for the differentiation of goblet cells and the terminal differentiation of enterocytes. Moreover, the regulation of

  12. The forkhead transcription factor FOXP1 represses human plasma cell differentiation

    NARCIS (Netherlands)

    M. Van Keimpema (Martine); L.J. Grüneberg (Leonie J.); M. Mokry (Michal); R. Van Boxtel (Ruben); M.C. van Zelm (Menno); P.J. Coffer (Paul); S. Pals; M. Spaargaren

    2015-01-01

    textabstractExpression of the for khead transcription factor FOXP1 is essential for early B-cell development, whereas down regulation ofFOXP1at the germinal center (GC) stage is required for GC B-cell function. Aberrantly high FOXP1 expression is frequently observed in diffuse large B-cell lymphoma

  13. Genotype-dependent activation or repression of HBV enhancer Ⅱ by transcription factor COUP-TF1

    Institute of Scientific and Technical Information of China (English)

    Silke F Fischer; Katja Schmidt; Nicola Fiedler; Dieter Glebe; Christian Schüttler; Jianguang Sun; Wolfram H Gerlich; Reinald Repp; Stephan Schaefer

    2006-01-01

    AIM: To study the expression of HBV enhancer Ⅱ by transcription factor COUP-TF1.METHODS: In order to study the regulation of HBV variants in the vicinity of the NRRE we cloned luciferase constructs containing the HBV enhancer Ⅱ from variants and from HBV genotypes A and D and cotransfected them together with expression vectors for COUP-TF1 into HepG2 cells.RESULTS: Our findings show that enhancer Ⅱ of HBV genotype A is also repressed by COUP-TF1. In contrast,two different enhancer Ⅱ constructs of HBV genotype D were activated by COUP-TF1. The activation was independent of the NRRE because a natural variant with a deletion of nt 1763-1770 was still activated by COUP-TF1.CONCLUSION: Regulation of transcription of the HBV genome seems to differ among HBV genomes derived from different genotypes. These differences in transcriptional control among HBV genotypes may be the molecular basis for differences in the clinical course among HBV genotypes.

  14. A NAC Transcription Factor Represses Putrescine Biosynthesis and Affects Drought Tolerance.

    Science.gov (United States)

    Wu, Hao; Fu, Bing; Sun, Peipei; Xiao, Chang; Liu, Ji-Hong

    2016-11-01

    Arginine decarboxylase (ADC)-mediated putrescine biosynthesis plays an important role in plant stress responses, but the transcriptional regulation of ADC in response to abiotic stress is not well understood. We isolated a NAM, ATAF1/2, and CUC (NAC) domain-containing transcription factor, PtrNAC72, from trifoliate orange (Poncirus trifoliata) by yeast one-hybrid screening. PtrNAC72, localized to the nucleus, binds specifically to the promoter of PtADC and acts as a transcriptional repressor. PtrNAC72 expression was induced by cold, drought, and abscisic acid. ADC messenger RNA abundance and putrescine levels were decreased in transgenic tobacco (Nicotiana nudicaulis) plants overexpressing PtrNAC72 but increased, compared with the wild type, in an Arabidopsis (Arabidopsis thaliana) transfer DNA insertion mutant, nac72 While transgenic tobacco lines overexpressing PtrNAC72 were more sensitive to drought, plants of the Arabidopsis nac72 mutant exhibited enhanced drought tolerance, consistent with the accumulation of reactive oxygen species in the tested genotypes. In addition, exogenous application of putrescine to the overexpression lines restored drought tolerance, while treatment with d-arginine, an ADC inhibitor, compromised the drought tolerance of nac72 Taken together, these results demonstrate that PtrNAC72 is a repressor of putrescine biosynthesis and may negatively regulate the drought stress response, at least in part, via the modulation of putrescine-associated reactive oxygen species homeostasis.

  15. The transcription factor TEAD1 represses smooth muscle-specific gene expression by abolishing myocardin function.

    Science.gov (United States)

    Liu, Fang; Wang, Xiaobo; Hu, Guoqing; Wang, Yong; Zhou, Jiliang

    2014-02-07

    The TEAD (transcriptional enhancer activator domain) proteins share an evolutionarily conserved DNA-binding TEA domain, which binds to the MCAT cis-acting regulatory element. Previous studies have shown that TEAD proteins are involved in regulating the expression of smooth muscle α-actin. However, it remains undetermined whether TEAD proteins play a broader role in regulating expression of other genes in vascular smooth muscle cells. In this study, we show that the expression of TEAD1 is significantly induced during smooth muscle cell phenotypic modulation and negatively correlates with smooth muscle-specific gene expression. We further demonstrate that TEAD1 plays a novel role in suppressing expression of smooth muscle-specific genes, including smooth muscle α-actin, by abolishing the promyogenic function of myocardin, a key mediator of smooth muscle differentiation. Mechanistically, we found that TEAD1 competes with myocardin for binding to serum response factor (SRF), resulting in disruption of myocardin and SRF interactions and thereby attenuating expression of smooth muscle-specific genes. This study provides the first evidence demonstrating that TEAD1 is a novel general repressor of smooth muscle-specific gene expression through interfering with myocardin binding to SRF.

  16. A transcriptional repressive role for epithelial-specific ETS factor ELF3 on oestrogen receptor alpha in breast cancer cells.

    Science.gov (United States)

    Gajulapalli, Vijaya Narasihma Reddy; Samanthapudi, Venkata Subramanyam Kumar; Pulaganti, Madhusudana; Khumukcham, Saratchandra Singh; Malisetty, Vijaya Lakhsmi; Guruprasad, Lalitha; Chitta, Suresh Kumar; Manavathi, Bramanandam

    2016-04-15

    Oestrogen receptor-α (ERα) is a ligand-dependent transcription factor that primarily mediates oestrogen (E2)-dependent gene transcription required for mammary gland development. Coregulators critically regulate ERα transcription functions by directly interacting with it. In the present study, we report that ELF3, an epithelial-specific ETS transcription factor, acts as a transcriptional repressor of ERα. Co-immunoprecipitation (Co-IP) analysis demonstrated that ELF3 strongly binds to ERα in the absence of E2, but ELF3 dissociation occurs upon E2 treatment in a dose- and time-dependent manner suggesting that E2 negatively influences such interaction. Domain mapping studies further revealed that the ETS (E-twenty six) domain of ELF3 interacts with the DNA binding domain of ERα. Accordingly, ELF3 inhibited ERα's DNA binding activity by preventing receptor dimerization, partly explaining the mechanism by which ELF3 represses ERα transcriptional activity. Ectopic expression of ELF3 decreases ERα transcriptional activity as demonstrated by oestrogen response elements (ERE)-luciferase reporter assay or by endogenous ERα target genes. Conversely ELF3 knockdown increases ERα transcriptional activity. Consistent with these results, ELF3 ectopic expression decreases E2-dependent MCF7 cell proliferation whereas ELF3 knockdown increases it. We also found that E2 induces ELF3 expression in MCF7 cells suggesting a negative feedback regulation of ERα signalling in breast cancer cells. A small peptide sequence of ELF3 derived through functional interaction between ERα and ELF3 could inhibit DNA binding activity of ERα and breast cancer cell growth. These findings demonstrate that ELF3 is a novel transcriptional repressor of ERα in breast cancer cells. Peptide interaction studies further represent a novel therapeutic option in breast cancer therapy. © 2016 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

  17. Thiopental inhibits global protein synthesis by repression of eukaryotic elongation factor 2 and protects from hypoxic neuronal cell death.

    Directory of Open Access Journals (Sweden)

    Christian I Schwer

    Full Text Available Ischemic and traumatic brain injury is associated with increased risk for death and disability. The inhibition of penumbral tissue damage has been recognized as a target for therapeutic intervention, because cellular injury evolves progressively upon ATP-depletion and loss of ion homeostasis. In patients, thiopental is used to treat refractory intracranial hypertension by reducing intracranial pressure and cerebral metabolic demands; however, therapeutic benefits of thiopental-treatment are controversially discussed. In the present study we identified fundamental neuroprotective molecular mechanisms mediated by thiopental. Here we show that thiopental inhibits global protein synthesis, which preserves the intracellular energy metabolite content in oxygen-deprived human neuronal SK-N-SH cells or primary mouse cortical neurons and thus ameliorates hypoxic cell damage. Sensitivity to hypoxic damage was restored by pharmacologic repression of eukaryotic elongation factor 2 kinase. Translational inhibition was mediated by calcium influx, activation of the AMP-activated protein kinase, and inhibitory phosphorylation of eukaryotic elongation factor 2. Our results explain the reduction of cerebral metabolic demands during thiopental treatment. Cycloheximide also protected neurons from hypoxic cell death, indicating that translational inhibitors may generally reduce secondary brain injury. In conclusion our study demonstrates that therapeutic inhibition of global protein synthesis protects neurons from hypoxic damage by preserving energy balance in oxygen-deprived cells. Molecular evidence for thiopental-mediated neuroprotection favours a positive clinical evaluation of barbiturate treatment. The chemical structure of thiopental could represent a pharmacologically relevant scaffold for the development of new organ-protective compounds to ameliorate tissue damage when oxygen availability is limited.

  18. TGF-β Signaling Cooperates with AT Motif-Binding Factor-1 for Repression of the α-Fetoprotein Promoter

    Directory of Open Access Journals (Sweden)

    Nobuo Sakata

    2014-01-01

    Full Text Available α-Fetoprotein (AFP is known to be highly produced in fetal liver despite its barely detectable level in normal adult liver. On the other hand, hepatocellular carcinoma often shows high expression of AFP. Thus, AFP seems to be an oncogenic marker. In our present study, we investigated how TGF-β signaling cooperates with AT motif-binding factor-1 (ATBF1 to inhibit AFP transcription. Indeed, the expression of AFP mRNA in HuH-7 cells was negatively regulated by TGF-β signaling. To further understand how TGF-β suppresses the transcription of the AFP gene, we analyzed the activity of the AFP promoter in the presence of TGF-β. We found that the TGF-β signaling and ATBF1 suppressed AFP transcription through two ATBF1 binding elements (AT-motifs. Using a heterologous reporter system, both AT-motifs were required for transcriptional repression upon TGF-β stimulation. Furthermore, Smads were found to interact with ATBF1 at both its N-terminal and C-terminal regions. Since the N-terminal (ATBF1N and C-terminal regions of ATBF1 (ATBF1C lack the ability of DNA binding, both truncated mutants rescued the cooperative inhibitory action by the TGF-β signaling and ATBF1 in a dose-dependent manner. Taken together, these findings indicate that TGF-β signaling can act in concert with ATBF1 to suppress the activity of the AFP promoter through direct interaction of ATBF1 with Smads.

  19. Soybean miR172c Targets the Repressive AP2 Transcription Factor NNC1 to Activate ENOD40 Expression and Regulate Nodule Initiation[C][W

    Science.gov (United States)

    Wang, Youning; Wang, Lixiang; Zou, Yanmin; Chen, Liang; Cai, Zhaoming; Zhang, Senlei; Zhao, Fang; Tian, Yinping; Jiang, Qiong; Ferguson, Brett J.; Gresshoff, Peter M.; Li, Xia

    2014-01-01

    MicroRNAs are noncoding RNAs that act as master regulators to modulate various biological processes by posttranscriptionally repressing their target genes. Repression of their target mRNA(s) can modulate signaling cascades and subsequent cellular events. Recently, a role for miR172 in soybean (Glycine max) nodulation has been described; however, the molecular mechanism through which miR172 acts to regulate nodulation has yet to be explored. Here, we demonstrate that soybean miR172c modulates both rhizobium infection and nodule organogenesis. miR172c was induced in soybean roots inoculated with either compatible Bradyrhizobium japonicum or lipooligosaccharide Nod factor and was highly upregulated during nodule development. Reduced activity and overexpression of miR172c caused dramatic changes in nodule initiation and nodule number. We show that soybean miR172c regulates nodule formation by repressing its target gene, Nodule Number Control1, which encodes a protein that directly targets the promoter of the early nodulin gene, ENOD40. Interestingly, transcriptional levels of miR172c were regulated by both Nod Factor Receptor1α/5α-mediated activation and by autoregulation of nodulation-mediated inhibition. Thus, we established a direct link between miR172c and the Nod factor signaling pathway in addition to adding a new layer to the precise nodulation regulation mechanism of soybean. PMID:25549672

  20. Germ Cell Nuclear Factor (GCNF) Represses Oct4 Expression and Globally Modulates Gene Expression in Human Embryonic Stem (hES) Cells.

    Science.gov (United States)

    Wang, Hongran; Wang, Xiaohong; Xu, Xueping; Kyba, Michael; Cooney, Austin J

    2016-04-15

    Oct4 is considered a key transcription factor for pluripotent stem cell self-renewal. It binds to specific regions within target genes to regulate their expression and is downregulated upon induction of differentiation of pluripotent stem cells; however, the mechanisms that regulate the levels of human Oct4 expression remain poorly understood. Here we show that expression of human Oct4 is directly repressed by germ cell nuclear factor (GCNF), an orphan nuclear receptor, in hES cells. Knockdown of GCNF by siRNA resulted in maintenance of Oct4 expression during RA-induced hES cell differentiation. While overexpression of GCNF promoted repression of Oct4 expression in both undifferentiated and differentiated hES cells. The level of Oct4 repression was dependent on the level of GCNF expression in a dose-dependent manner. mRNA microarray analysis demonstrated that overexpression of GCNF globally regulates gene expression in undifferentiated and differentiated hES cells. Within the group of altered genes, GCNF down-regulated 36% of the genes, and up-regulated 64% in undifferentiated hES cells. In addition, GCNF also showed a regulatory gene pattern that is different from RA treatment during hES cell differentiation. These findings increase our understanding of the mechanisms that maintain hES cell pluripotency and regulate gene expression during the differentiation process.

  1. NF-κB-repressing factor phosphorylation regulates transcription elongation via its interactions with 5'→3' exoribonuclease 2 and negative elongation factor.

    Science.gov (United States)

    Rother, Sascha; Bartels, Myriam; Schweda, Aike Torben; Resch, Klaus; Pallua, Norbert; Nourbakhsh, Mahtab

    2016-01-01

    NF-κB-repressing factor (NKRF) inhibits transcription elongation by binding to specific sequences in target promoters. Stimuli such as IL-1 have been shown to overcome this inhibitory action and enable the resumption of transcription elongation machinery by an unknown mechanism. Using mass spectrometry and in vitro phosphorylation analyses, we demonstrate that NKRF is phosphorylated within 3 different domains in unstimulated HeLa cells. Phosphoamino acid mapping and mutation analysis of NKRF further suggest that only Ser phosphorylation within aa 421-429 is regulated by IL-1 stimulation. In copurification studies, aa 421-429 is required for interactions between NKRF, 5'→3' exoribonuclease 2 (XRN2) and the negative elongation factor (NELF)-E in HeLa cells. Chromatin immunoprecipitation experiments further show that IL-1 stimulation leads to decrease in NKRF aa 421-429 phosphorylation and dissociation of NELF-E and XRN2 by concomitant resumption of transcription elongation of a synthetic reporter or the endogenous NKRF target gene, IL-8. Together, NKRF phosphorylation modulates promoter-proximal transcription elongation of NF-κB/NKRF-regulated genes via direct interactions with elongation complex in response to specific stimuli.

  2. Oncovirus Kaposi sarcoma herpesvirus (KSHV) represses tumor suppressor PDLIM2 to persistently activate nuclear factor κB (NF-κB) and STAT3 transcription factors for tumorigenesis and tumor maintenance.

    Science.gov (United States)

    Sun, Fan; Xiao, Yadong; Qu, Zhaoxia

    2015-03-20

    Kaposi sarcoma herpesvirus (KSHV) is the most common cause of malignancies among AIDS patients. However, how KSHV induces tumorigenesis remains largely unknown. Here, we demonstrate that one important mechanism underlying the tumorigenesis of KSHV is through transcriptional repression of the tumor suppressor gene PDZ-LIM domain-containing protein 2 (PDLIM2). PDLIM2 expression is repressed in KSHV-transformed human umbilical vascular endothelial cells as well as in KSHV-associated cancer cell lines and primary tumors. Importantly, PDLIM2 repression is essential for KSHV-induced persistent activation of nuclear factor κB (NF-κB) and signal transducer and activator of transcription 3 (STAT3) and subsequent tumorigenesis and tumor maintenance. Our mechanistic studies indicate that PDLIM2 repression by KSHV involves DNA methylation. Notably, the epigenetic repression of PDLIM2 can be reversed by 5-aza-2-deoxycytidine and vitamin D to suppress KSHV-associated cancer cell growth. These studies not only improve our understanding of KSHV pathogenesis but also provide immediate therapeutic strategies for KSHV-mediated cancers, particularly those associated with AIDS.

  3. Cell-Autonomous Repression of Shh by Transcription Factor Pax6 Regulates Diencephalic Patterning by Controlling the Central Diencephalic Organizer

    Directory of Open Access Journals (Sweden)

    Isabel Martín Caballero

    2014-09-01

    Full Text Available During development, region-specific patterns of regulatory gene expression are controlled by signaling centers that release morphogens providing positional information to surrounding cells. Regulation of signaling centers themselves is therefore critical. The size and the influence of a Shh-producing forebrain organizer, the zona limitans intrathalamica (ZLI, are limited by Pax6. By studying mouse chimeras, we find that Pax6 acts cell autonomously to block Shh expression in cells around the ZLI. Immunoprecipitation and luciferase assays indicate that Pax6 can bind the Shh promoter and repress its function. An analysis of chimeras suggests that many of the regional gene expression pattern defects that occur in Pax6−/− diencephalic cells result from a non-cell-autonomous position-dependent defect of local intercellular signaling. Blocking Shh signaling in Pax6−/− mutants reverses major diencephalic patterning defects. We conclude that Pax6’s cell-autonomous repression of Shh expression around the ZLI is critical for many aspects of normal diencephalic patterning.

  4. Cell-autonomous repression of Shh by transcription factor Pax6 regulates diencephalic patterning by controlling the central diencephalic organizer.

    Science.gov (United States)

    Caballero, Isabel Martín; Manuel, Martine N; Molinek, Michael; Quintana-Urzainqui, Idoia; Mi, Da; Shimogori, Tomomi; Price, David J

    2014-09-11

    During development, region-specific patterns of regulatory gene expression are controlled by signaling centers that release morphogens providing positional information to surrounding cells. Regulation of signaling centers themselves is therefore critical. The size and the influence of a Shh-producing forebrain organizer, the zona limitans intrathalamica (ZLI), are limited by Pax6. By studying mouse chimeras, we find that Pax6 acts cell autonomously to block Shh expression in cells around the ZLI. Immunoprecipitation and luciferase assays indicate that Pax6 can bind the Shh promoter and repress its function. An analysis of chimeras suggests that many of the regional gene expression pattern defects that occur in Pax6(-/-) diencephalic cells result from a non-cell-autonomous position-dependent defect of local intercellular signaling. Blocking Shh signaling in Pax6(-/-) mutants reverses major diencephalic patterning defects. We conclude that Pax6's cell-autonomous repression of Shh expression around the ZLI is critical for many aspects of normal diencephalic patterning.

  5. NATURAL MUTATION IN THE GENE OF RESPONSE REGULATOR BgrR RESULTING IN REPRESSION OF Bac PROTEIN SYNTHESIS, A PATHOGENICITY FACTOR OF STREPTOCOCCUS AGALACTIAE

    Directory of Open Access Journals (Sweden)

    A. S. Rozhdestvenskaya

    2013-01-01

    Full Text Available Abstract. Streptococcus agalactiae can cause variety of diseases of newborns and adults. For successful colonization of different human tissues and organs as well as for suppression of the host immune system S. agalactiae expresses numerous virulence factors. For coordinated expression of the virulence genes S. agalactiae employs regulatory molecules including regulatory proteins of two-component systems. Results of the present study demonstrated that in S. agalactiae strain A49V the natural mutation in the brgR gene encoding for BgrR regulatory protein, which is component of regulatory system BgrRS, resulted in the repression of Bac protein synthesis, a virulence factor of S. agalactiae. A single nucleotide deletion in the bgrR gene has caused a shift of the reading frame and the changes in the primary, secondary and tertiary structures of the BgrR protein. The loss of functional activity of BgrR protein in A49V strain and repression of Bac protein synthesis have increased virulence of the strain in experimental animal streptococcal infection.

  6. A +220 GATA motif mediates basal but not endotoxin-repressible expression of the von Willebrand factor promoter in Hprt-targeted transgenic mice

    Science.gov (United States)

    LIU, J.; KANKI, Y.; OKADA, Y.; JIN, E.; YANO, K.; SHIH, S.-C.; MINAMI, T.; AIRD, W. C.

    2012-01-01

    Summary Background The von Willebrand factor (VWF) gene is a marker for spatial and temporal heterogeneity of the endothelium. A GATA motif at +220 has been implicated in basal VWF expression in vitro. Other studies have shown that GATA3 and VWF are transcriptionally downregulated in response to inflammatory mediators. Objectives Our goal was to determine the importance of the +220 GATA motif in mediating expression of VWF promoter in vivo, and to elucidate whether the GATA element plays a role in spatial and/or temporal regulation of VWF expression. Methods ChIP and electrophoretic mobility shift assays were carried out in human umbilical vein endothelial cells (HUVEC). Reporter gene constructs containing 3.6 kb of the human VWF promoter with and without amutation of the +220 GATA element were transfected into cultured endothelial cells or targeted to the Hprt locus of mice. The Hprt-targeted mice were subjected to endotoxemia. Results In protein-DNA binding assays, the +220 GATA motif bound GATA-2, -3 and -6. Mutation of the GATA site resulted in reduced basal promoter activity in HUVEC. When targeted to the Hprt locus of mice, the GATA mutation resulted in a significant, proportionate reduction of promoter activity in LacZ expressing vascular beds. Systemic administration of lipopolysaccharide (LPS) resulted in a widespread reduction in VWF mRNA expression and promoter activity. LPS-mediated repression of the VWF promoter was unaffected by the GATA mutation. Conclusions A region of the VWF promoter between −2182 and the end of the first intron contains information for LPS-mediated gene repression. The +220 GATA motif is important for basal, but not LPS-repressible expression of the VWF gene. PMID:19496923

  7. Repression of the transcription factor Bach2 contributes to predisposition of IgG1 memory B cells toward plasma cell differentiation.

    Science.gov (United States)

    Kometani, Kohei; Nakagawa, Rinako; Shinnakasu, Ryo; Kaji, Tomohiro; Rybouchkin, Andrei; Moriyama, Saya; Furukawa, Koji; Koseki, Haruhiko; Takemori, Toshitada; Kurosaki, Tomohiro

    2013-07-25

    Memory B cells are essential for generating rapid and robust secondary antibody responses. It has been thought that the unique cytoplasmic domain of IgG causes the prompt activation of antigen-experienced IgG memory B cells. To assess this model, we have generated a mouse containing IgG1 B cells that have never encountered antigen. We found that, upon challenge, antigen-experienced IgG1 memory B cells rapidly differentiated into plasma cells, whereas nonexperienced IgG1 B cells did not, suggesting the importance of the stimulation history. In addition, our results suggest that repression of the Bach2 transcription factor, which results from antigen experience, contributes to predisposition of IgG1 memory B cells to differentiate into plasma cells.

  8. Angiocrine factors modulate tumor proliferation and motility through EphA2 repression of Slit2 tumor suppressor function in endothelium.

    Science.gov (United States)

    Brantley-Sieders, Dana M; Dunaway, Charlene M; Rao, Meghana; Short, Sarah; Hwang, Yoonha; Gao, Yandong; Li, Deyu; Jiang, Aixiang; Shyr, Yu; Wu, Jane Y; Chen, Jin

    2011-02-01

    It is well known that tumor-derived proangiogenic factors induce neovascularization to facilitate tumor growth and malignant progression. However, the concept of "angiocrine" signaling, in which signals produced by endothelial cells elicit tumor cell responses distinct from vessel function, has been proposed, yet remains underinvestigated. Here, we report that angiocrine factors secreted from endothelium regulate tumor growth and motility. We found that Slit2, which is negatively regulated by endothelial EphA2 receptor, is one such tumor suppressive angiocrine factor. Slit2 activity is elevated in EphA2-deficient endothelium. Blocking Slit activity restored angiocrine-induced tumor growth/motility, whereas elevated Slit2 impaired growth/motility. To translate our findings to human cancer, we analyzed EphA2 and Slit2 expression in human cancer. EphA2 expression inversely correlated with Slit2 in the vasculature of invasive human ductal carcinoma samples. Moreover, analysis of large breast tumor data sets revealed that Slit2 correlated positively with overall and recurrence-free survival, providing clinical validation for the tumor suppressor function for Slit2 in human breast cancer. Together, these data support a novel, clinically relevant mechanism through which EphA2 represses Slit2 expression in endothelium to facilitate angiocrine-mediated tumor growth and motility by blocking a tumor suppressive signal.

  9. A family of insulin-like growth factor II mRNA-binding proteins represses translation in late development

    DEFF Research Database (Denmark)

    Nielsen, J; Christiansen, J; Lykke-Andersen, J;

    1999-01-01

    Insulin-like growth factor II (IGF-II) is a major fetal growth factor. The IGF-II gene generates multiple mRNAs with different 5' untranslated regions (5' UTRs) that are translated in a differential manner during development. We have identified a human family of three IGF-II mRNA-binding proteins.......5 followed by a decline towards birth, and, similar to IGF-II, IMPs are especially expressed in developing epithelia, muscle, and placenta in both mouse and human embryos. The results imply that cytoplasmic 5' UTR-binding proteins control IGF-II biosynthesis during late mammalian development....

  10. Phenomenon of the inner psychological migration as the factor of the national identity preservation in a period of social crises, anomia and repressions in case of the Polish settlement Marchlewsk (Dovbysh

    Directory of Open Access Journals (Sweden)

    Staniszewska Żanna

    2016-04-01

    Full Text Available The article gives a review of the population history of the Polish National Region named after Julian Marchlewski (settlement of Dovbysh, Zhitomir province, Ukraine. The author explores the psychological factors affecting the preservation of culture, religion and identity of the Polish community in the period of the repressions 1920-30 years. The article researches and analyses the phenomenon of internal psychological migration as a factor in preservation of national and personal self-identity.

  11. Cell type specific repression of the varicella zoster virus immediate early gene 62 promoter by the cellular Oct-2 transcription factor.

    Science.gov (United States)

    Patel, Y; Gough, G; Coffin, R S; Thomas, S; Cohen, J I; Latchman, D S

    1998-05-11

    The cellular transcription factor Oct-2.1 has previously been shown to repress the transactivation of the varicella zoster virus (VZV) immediate early gene promoter by viral transactivators but not to inhibit its basal activity. In the case of the related virus herpes simplex virus (HSV), the effect of Oct-2 on the IE promoters has been shown to be cell type specific and to differ between the different alternatively spliced forms of Oct-2. Here we show that as well as Oct-2.1, the Oct-2.4 and 2.5 isoforms which are expressed in neuronal cells can inhibit transactivation of the VZV immediate early promoter regardless of the cell type used. In contrast, all the isoforms of Oct-2 can inhibit basal activity of the VZV promoter in neuronal cells but not in other cell types indicating that this effect is cell type specific. These effects are discussed in terms of the differential regulation of latent infections with HSV or VZV in dorsal root ganglia.

  12. CS5931, a Novel Polypeptide in Ciona savignyi, Represses Angiogenesis via Inhibiting Vascular Endothelial Growth Factor (VEGF and Matrix Metalloproteinases (MMPs

    Directory of Open Access Journals (Sweden)

    Ge Liu

    2014-03-01

    Full Text Available CS5931 is a novel polypeptide from Ciona savignyi with anticancer activities. Previous study in our laboratory has shown that CS5931 can induce cell death via mitochondrial apoptotic pathway. In the present study, we found that the polypeptide could inhibit angiogenesis both in vitro and in vivo. CS5931 inhibited the proliferation, migration and formation of capillary-like structures of HUVECs (Human Umbilical Vein Endothelial Cell in a dose-dependent manner. Additionally, CS5931 repressed spontaneous angiogenesis of the zebrafish vessels. Further studies showed that CS5931 also blocked vascular endothelial growth factor (VEGF production but without any effect on its mRNA expression. Moreover, CS5931 reduced the expression of matrix metalloproteinases (MMP-2 and MMP-9 both on protein and mRNA levels in HUVEC cells. We demonstrated that CS5931 possessed strong anti-angiogenic activity both in vitro and in vivo, possible via VEGF and MMPs. This study indicates that CS5931 has the potential to be developed as a novel therapeutic agent as an inhibitor of angiogenesis for the treatment of cancer.

  13. ZCT1 and ZCT2 transcription factors repress the activity of a gene promoter from the methyl erythritol phosphate pathway in Madagascar periwinkle cells.

    Science.gov (United States)

    Chebbi, Mouadh; Ginis, Olivia; Courdavault, Vincent; Glévarec, Gaëlle; Lanoue, Arnaud; Clastre, Marc; Papon, Nicolas; Gaillard, Cécile; Atanassova, Rossitza; St-Pierre, Benoit; Giglioli-Guivarc'h, Nathalie; Courtois, Martine; Oudin, Audrey

    2014-10-15

    In Catharanthus roseus, accumulating data highlighted the existence of a coordinated transcriptional regulation of structural genes that takes place within the secoiridoid biosynthetic branch, including the methyl erythritol phosphate (MEP) pathway and the following steps leading to secologanin. To identify transcription factors acting in these pathways, we performed a yeast one-hybrid screening using as bait a promoter region of the hydroxymethylbutenyl 4-diphosphate synthase (HDS) gene involved in the responsiveness of C. roseus cells to hormonal signals inducing monoterpene indole alkaloid (MIA) production. We identified that ZCT2, one of the three members of the zinc finger Catharanthus protein (ZCT) family, can bind to a HDS promoter region involved in hormonal responsiveness. By trans-activation assays, we demonstrated that ZCT1 and ZCT2 but not ZCT3 repress the HDS promoter activity. Gene expression analyses in C. roseus cells exposed to methyljasmonate revealed a persistence of induction of ZCT2 gene expression suggesting the existence of feed-back regulatory events acting on HDS gene expression in correlation with the MIA production.

  14. microRNA-155, induced by interleukin-1ß, represses the expression of microphthalmia-associated transcription factor (MITF-M in melanoma cells.

    Directory of Open Access Journals (Sweden)

    Nathalie Arts

    Full Text Available Loss of expression of surface antigens represents a significant problem for cancer immunotherapy. Microphthalmia-associated transcription factor (MITF-M regulates melanocyte fate by driving expression of many differentiation genes, whose protein products can be recognized by cytolytic T lymphocytes. We previously reported that interleukin-1ß (IL-1ß can downregulate MITF-M levels. Here we show that downregulation of MITF-M expression by IL-1ß was paralleled by an upregulation of miR-155 expression in four melanoma lines. We confirmed that miR-155 was able to target endogenous MITF-M in melanoma cells and demonstrated a role for miR-155 in the IL-1ß-induced repression of MITF-M by using an antagomiR. Notably, we also observed a strong negative correlation between MITF-M and miR-155 levels in a mouse model of melanoma. Taken together, our results indicate that MITF-M downregulation by inflammatory stimuli might be partly due to miR-155 upregulation. This could represent a novel mechanism of melanoma immune escape in an inflammatory microenvironment.

  15. RBP-J kappa repression activity is mediated by a co-repressor and antagonized by the Epstein-Barr virus transcription factor EBNA2.

    Science.gov (United States)

    Waltzer, L; Bourillot, P Y; Sergeant, A; Manet, E

    1995-01-01

    The Epstein-Barr virus (EBV) protein EBNA2 is a transcriptional activator that can be targeted to its DNA responsive elements by direct interaction with the cellular protein RBP-J kappa. RBP-J kappa is a ubiquitous factor, highly conserved between man, mouse and Drosophila, whose function in mammalian cells is largely unknown. Here we provide evidence that RBP-J kappa is a transcriptional repressor and, more importantly, that RBP-J kappa repression is mediated by a co-repressor. The function of the co-repressor could be counterbalanced by making a fusion protein (RBP-VP16) between RBP-J kappa and the VP16 activation domain. This RBP-VP16-mediated activation could be strongly increased by an EBNA2 protein deprived of its activation domain, but not by an EBNA2 protein incapable of making physical contact with RBP-J kappa. Our results suggest that EBNA2 activates transcription by both interfering with the function of a co-repressor recruited by RBP-J kappa and providing an activation domain. Images PMID:8559649

  16. Prostate-derived ets factor represses tumorigenesis and modulates epithelial-to-mesenchymal transition in bladder carcinoma cells.

    Science.gov (United States)

    Tsui, Ke-Hung; Lin, Yu-Hsiang; Chung, Li-Chuan; Chuang, Sung-Ting; Feng, Tsui-Hsia; Chiang, Kun-Chun; Chang, Phei-Lang; Yeh, Chi-Ju; Juang, Horng-Heng

    2016-05-28

    Prostate-derived Ets (E-twenty six) factor (PDEF), an epithelium-specific member of the Ets family of transcription factors, has been shown to play a role in suppressing the development of many epithelium-derived cancers such as prostate and breast cancer. It is not clear, however, whether PDEF is involved in the development or progression of bladder cancer. In a comparison between normal urothelium and bladder tumor tissue, we identified significant decreases of PDEF in the tumor tissue. Further, the immunohistochemistry assays indicated a significantly higher immunostaining of PDEF in low-grade bladder tumors. Additionally, the highly differentiated transitional-cell bladder carcinoma RT-4 cells expressed significantly more PDEF levels than the bladder carcinoma HT1376 and the T24 cells. Ectopic overexpression of PDEF attenuated proliferation, invasion, and tumorigenesis of bladder carcinoma cells in vitro and in vivo. PDEF enhanced the expression levels of mammary serine protease inhibitor (MASPIN), N-myc downstream regulated gene 1 (NDRG1), KAI1, and B-cell translocation gene 2 (BTG2). PDEF modulated epithelial-mesenchymal-transition (EMT) by upregulating E-cadherin expression and downregulating the expression of N-cadherin, SNAIL, SLUG, and vimentin, leading to lower migration and invasion abilities of bladder carcinoma cells. Filamentous actin (F-actin) polarization and remodeling were observed in PDEF-knockdown RT-4 cells. Our results suggest that PDEF gene expression is associated with the extent of bladder neoplasia and PDEF modulated the expressions of EMT-related genes. The induction of BTG2, NDRG1, MASPIN, and KAI1 gene expressions by PDEF may explain the inhibitory functions of PDEF on the proliferation, invasion, and tumorigenesis in bladder carcinoma cells.

  17. Insulin-like growth factor I - a novel biomarker of abdominal aortic aneurysms

    DEFF Research Database (Denmark)

    Lindholt, J S; Martin-Ventura, J L; Urbonavicius, S

    2011-01-01

    The study aimed to test the potential role of insulin-like growth factor I (IGF-I) and IGF-II as biomarkers for abdominal aortic aneurysm (AAA).......The study aimed to test the potential role of insulin-like growth factor I (IGF-I) and IGF-II as biomarkers for abdominal aortic aneurysm (AAA)....

  18. AMPK activation represses the human gene promoter of the cardiac isoform of acetyl-CoA carboxylase: Role of nuclear respiratory factor-1

    Energy Technology Data Exchange (ETDEWEB)

    Adam, Tasneem; Opie, Lionel H. [Hatter Cardiovascular Research Institute, Faculty of Health Sciences, University of Cape Town, Observatory 7925 (South Africa); Essop, M. Faadiel, E-mail: mfessop@sun.ac.za [Cardio-Metabolic Research Group (CMRG), Department of Physiological Sciences, Stellenbosch University, Stellenbosch 7600 (South Africa)

    2010-07-30

    Research highlights: {yields} AMPK inhibits acetyl-CoA carboxylase beta gene promoter activity. {yields} Nuclear respiratory factor-1 inhibits acetyl-CoA carboxylase beta promoter activity. {yields} AMPK regulates acetyl-CoA carboxylase beta at transcriptional level. -- Abstract: The cardiac-enriched isoform of acetyl-CoA carboxylase (ACC{beta}) produces malonyl-CoA, a potent inhibitor of carnitine palmitoyltransferase-1. AMPK inhibits ACC{beta} activity, lowering malonyl-CoA levels and promoting mitochondrial fatty acid {beta}-oxidation. Previously, AMPK increased promoter binding of nuclear respiratory factor-1 (NRF-1), a pivotal transcriptional modulator controlling gene expression of mitochondrial proteins. We therefore hypothesized that NRF-1 inhibits myocardial ACC{beta} promoter activity via AMPK activation. A human ACC{beta} promoter-luciferase construct was transiently transfected into neonatal cardiomyocytes {+-} a NRF-1 expression construct. NRF-1 overexpression decreased ACC{beta} gene promoter activity by 71 {+-} 4.6% (p < 0.001 vs. control). Transfections with 5'-end serial promoter deletions revealed that NRF-1-mediated repression of ACC{beta} was abolished with a pPII{beta}-18/+65-Luc deletion construct. AMPK activation dose-dependently reduced ACC{beta} promoter activity, while NRF-1 addition did not further decrease it. We also investigated NRF-1 inhibition in the presence of upstream stimulatory factor 1 (USF1), a known transactivator of the human ACC{beta} gene promoter. Here NRF-1 blunted USF1-dependent induction of ACC{beta} promoter activity by 58 {+-} 7.5% (p < 0.001 vs. control), reversed with a dominant negative NRF-1 construct. NRF-1 also suppressed endogenous USF1 transcriptional activity by 55 {+-} 6.2% (p < 0.001 vs. control). This study demonstrates that NRF-1 is a novel transcriptional inhibitor of the human ACC{beta} gene promoter in the mammalian heart. Our data extends AMPK regulation of ACC{beta} to the transcriptional level.

  19. Racism and Surplus Repression.

    Science.gov (United States)

    Johnson, Howard

    1983-01-01

    Explores the relationship between Herbert Marcuse's theory of "surplus repression" and Freud's theory of the "unconscious" with respect to latent, hidden, covert, or subliminal aspects of racism in the United States. Argues that unconscious racism, manifested in evasion/avoidance, acting out/projection, and attempted justification, perpetuates…

  20. CitI, a Transcription Factor Involved in Regulation of Citrate Metabolism in Lactic Acid Bacteria†

    Science.gov (United States)

    Martin, Mauricio G.; Magni, Christian; de Mendoza, Diego; López, Paloma

    2005-01-01

    A large variety of lactic acid bacteria (LAB) can utilize citrate under fermentative conditions. Although much information concerning the metabolic pathways leading to citrate utilization by LAB has been gathered, the mechanisms regulating these pathways are obscure. In Weissella paramesenteroides (formerly called Leuconostoc paramesenteroides), transcription of the citMDEFCGRP citrate operon and the upstream divergent gene citI is induced by the presence of citrate in the medium. Although genetic experiments have suggested that CitI is a transcriptional activator whose activity can be modulated in response to citrate availability, specific details of the interaction between CitI and DNA remained unknown. In this study, we show that CitI recognizes two A+T-rich operator sites located between citI and citM and that the DNA-binding affinity of CitI is increased by citrate. Subsequently, this citrate signal propagation leads to the activation of the cit operon through an enhanced recruitment of RNA polymerase to its promoters. Our results indicate that the control of CitI by the cellular pools of citrate provides a mechanism for sensing the availability of citrate and adjusting the expression of the cit operon accordingly. In addition, this is the first reported example of a transcription factor directly functioning as a citrate-activated switch allowing the cell to optimize the generation of metabolic energy. PMID:16030208

  1. Financial Liberalization Or Repression?

    OpenAIRE

    Ang, James

    2009-01-01

    While financial liberalization has always been advocated in developing countries, experiences with it do not always produce desirable outcomes. In order to evaluate the costs and benefits associated with financial liberalization and repression, this study highlights that the overall effectiveness of the reform programs depends on the relative strength of each financial sector policy implemented. Using India as a case study, the results indicate that interest rate controls, statutory liquidity...

  2. Recruitment of HDAC4 by transcription factor YY1 represses HOXB13 to affect cell growth in AR-negative prostate cancers

    DEFF Research Database (Denmark)

    Ren, Guoling; Zhang, Guocui; Dong, Zhixiong

    2008-01-01

    HOXB13 is a homeodomain protein implicated to play a role in growth arrest in AR (androgen receptor)-negative prostate cancer cells. Expression of HOXB13 is restricted to the AR-expressing prostate cells. In this report, we demonstrate that the HDAC inhibitor NaB (sodium butyrate) was able to ind...... to induce cell growth arrest and to increase HOXB13 expression in AR-negative prostate cancer cells. We also show that both HDAC4 and YY1 participated in the repression of HOXB13 expression through an epigenetic mechanism involving histone acetylation modification. Specifically, co...... essential for the recruitments of YY1 and HDAC4. Data presented in this report suggest that YY1 and HDAC4 affected cell growth by repressing transcriptional regulation of HOXB13 through an epigenetic modification of histones....

  3. Kinetically-defined component actions in gene repression.

    Directory of Open Access Journals (Sweden)

    Carson C Chow

    2015-03-01

    Full Text Available Gene repression by transcription factors, and glucocorticoid receptors (GR in particular, is a critical, but poorly understood, physiological response. Among the many unresolved questions is the difference between GR regulated induction and repression, and whether transcription cofactor action is the same in both. Because activity classifications based on changes in gene product level are mechanistically uninformative, we present a theory for gene repression in which the mechanisms of factor action are defined kinetically and are consistent for both gene repression and induction. The theory is generally applicable and amenable to predictions if the dose-response curve for gene repression is non-cooperative with a unit Hill coefficient, which is observed for GR-regulated repression of AP1LUC reporter induction by phorbol myristate acetate. The theory predicts the mechanism of GR and cofactors, and where they act with respect to each other, based on how each cofactor alters the plots of various kinetic parameters vs. cofactor. We show that the kinetically-defined mechanism of action of each of four factors (reporter gene, p160 coactivator TIF2, and two pharmaceuticals [NU6027 and phenanthroline] is the same in GR-regulated repression and induction. What differs is the position of GR action. This insight should simplify clinical efforts to differentially modulate factor actions in gene induction vs. gene repression.

  4. Inhibition of miRNA-212/132 improves the reprogramming of fibroblasts into induced pluripotent stem cells by de-repressing important epigenetic remodelling factors

    Directory of Open Access Journals (Sweden)

    Nils Pfaff

    2017-04-01

    Thus, conducting a full library miRNA screen we here describe a miRNA family, which markedly reduces generation of iPSC and upon inhibition in turn enhances reprogramming. These miRNAs, at least in part, exert their functions through repression of the epigenetic modulators p300 and Jarid1a, highlighting these two molecules as an endogenous epigenetic roadblock during iPSC generation.

  5. Alternative splicing of fibroblast growth factor receptor 3 produces a secreted isoform that inhibits fibroblast growth factor-induced proliferation and is repressed in urothelial carcinoma cell lines.

    Science.gov (United States)

    Tomlinson, Darren C; L'Hôte, Corine G; Kennedy, Wendy; Pitt, Eva; Knowles, Margaret A

    2005-11-15

    Fibroblast growth factor receptors (FGFRs) are a family of receptor tyrosine kinases that play key roles in proliferation, differentiation, and tumorigenesis. FGFR3 was identified as the major family member expressed in both normal human urothelium and cultured normal human urothelial (NHU) cells and was expressed as the IIIb isoform. We also identified a splice variant, FGFR3 Delta8-10, lacking exons encoding the COOH-terminal half of immunoglobulin-like domain III and the transmembrane domain. Previous reports have assumed that this is a cancer-specific splice variant. We showed that FGFR3 Delta8-10 is a normal transcript in NHU cells and is translated, N-glycosylated, and secreted. Primary urothelium expressed high levels of FGFR3 transcripts. In culture, levels were reduced in actively proliferating cells but increased at confluence and as cells approached senescence. Cells overexpressing FGFR3 IIIb showed FGF1-induced proliferation, which was inhibited by the addition of FGFR3 Delta8-10. In bladder tumor cell lines derived from aggressive carcinomas, there were significant alterations in the relative expression of isoforms including an overall decrease in the proportion of FGFR3 Delta8-10 and predominant expression of FGFR3 IIIc in some cases. In summary, alternative splicing of FGFR3 IIIb in NHU cells represents a normal mechanism to generate a transcript that regulates proliferation and in bladder cancer, the ratio of FGFR3 isoforms is significantly altered.

  6. A tobacco calcium-dependent protein kinase, CDPK1, regulates the transcription factor REPRESSION OF SHOOT GROWTH in response to gibberellins.

    Science.gov (United States)

    Ishida, Sarahmi; Yuasa, Takashi; Nakata, Masaru; Takahashi, Yohsuke

    2008-12-01

    The homeostasis of gibberellins (GAs) is maintained by negative feedback in plants. REPRESSION OF SHOOT GROWTH (RSG) is a tobacco (Nicotiana tabacum) transcriptional activator that has been suggested to play a role in GA feedback by the regulation of GA biosynthetic enzymes. The 14-3-3 signaling proteins negatively regulate RSG by sequestering it in the cytoplasm in response to GAs. The phosphorylation on Ser-114 of RSG is essential for 14-3-3 binding of RSG. Here, we identified tobacco Ca(2+)-dependent protein kinase (CDPK1) as an RSG kinase that promotes 14-3-3 binding to RSG by phosphorylation of Ser-114 of RSG. CDPK1 interacts with RSG in a Ca(2+)-dependent manner in vivo and in vitro and specifically phosphorylates Ser-114 of RSG. Inhibition of CDPK repressed the GA-induced phosphorylation of Ser-114 of RSG and the GA-induced nuclear export of RSG. Overexpression of CDPK1 inhibited the feedback regulation of a GA 20-oxidase gene and resulted in sensitization to the GA biosynthetic inhibitor. Our results suggest that CDPK1 decodes the Ca(2+) signal produced by GAs and regulates the intracellular localization of RSG.

  7. Financial repression and fiscal policy

    NARCIS (Netherlands)

    Gupta, KL; Lensink, R

    1997-01-01

    This paper develops a simulation model to assess the consequences of government's trying to raise revenues through financial repression in developing countries. The measures of financial repression studied are (1) government borrowing from the banking sector to finance its budget deficit (2) governm

  8. Independent repression of bile acid synthesis and activation of c-Jun N-terminal kinase (JNK) by activated hepatocyte fibroblast growth factor receptor 4 (FGFR4) and bile acids.

    Science.gov (United States)

    Yu, Chundong; Wang, Fen; Jin, Chengliu; Huang, Xinqiang; McKeehan, Wallace L

    2005-05-06

    The fibroblast growth factor (FGF) receptor complex is a regulator of adult organ homeostasis in addition to its central role in embryonic development and wound healing. FGF receptor 4 (FGFR4) is the sole FGFR receptor kinase that is significantly expressed in mature hepatocytes. Previously, we showed that mice lacking mouse FGFR4 (mR4(-/-)) exhibited elevated fecal bile acids, bile acid pool size, and expression of liver cholesterol 7alpha-hydroxylase (CYP7A1), the rate-limiting enzyme for canonical neutral bile acid synthesis. To prove that hepatocyte FGFR4 was a negative regulator of cholesterol metabolism and bile acid synthesis independent of background, we generated transgenic mice overexpressing a constitutively active human FGFR4 (CahR4) in hepatocytes and crossed them with the FGFR4-deficient mice to generate CahR4/mR4(-/-) mice. In mice expressing active FGFR4 in liver, fecal bile acid excretion was 64%, bile acid pool size was 47%, and Cyp7a1 expression was 10-30% of wild-type mice. The repressed level of Cyp7a1 expression was resistant to induction by a high cholesterol diet relative to wild-type mice. Expression of CahR4 in mR4(-/-) mouse livers depressed bile acid synthesis below wild-type levels from the elevated levels observed in mR4(-/-). Levels of phosphorylated c-Jun N-terminal kinase (JNK), which is part of a pathway implicated in bile acid-mediated repression of synthesis, was 30% of wild-type levels in mR4(-/-) livers, whereas CahR4 livers exhibited an average 2-fold increase. However, cholate still strongly induced phospho-JNK in mR4(-/-) livers. These results confirm that hepatocyte FGFR4 regulates bile acid synthesis by repression of Cyp7a1 expression. Hepatocyte FGFR4 may contribute to the repression of bile acid synthesis through JNK signaling but is not required for activation of JNK signaling by bile acids.

  9. Activation of the Wnt/β-catenin pathway represses the transcription of the β-amyloid precursor protein cleaving enzyme (BACE1) via binding of T-cell factor-4 to BACE1 promoter.

    Science.gov (United States)

    Parr, Callum; Mirzaei, Nazanin; Christian, Mark; Sastre, Magdalena

    2015-02-01

    Alterations in the Wnt signaling pathway have been implicated in Alzheimer's disease; however, its role in the processing of the amyloid precursor protein remains unknown. In this study, activation of the Wnt pathway by overexpression of the agonist Wnt3a or β-catenin or by inhibition of glycogen kinase synthase-3 in N2a cells resulted in a reduction in Aβ levels and in the activity and expression of BACE1 (β-APP cleaving enzyme). Conversely, inhibition of the pathway by transfection of the antagonists secreted frizzled receptor protein-1 or dickkopf-1 produced the opposite effects. Chromatin immunoprecipitation analysis demonstrated that β-catenin binds specifically to regions within the promoter of BACE1 containing putative T-cell factor/lymphoid enhancer binding factor-1 (TCF/LEF) motifs, consistent with canonical Wnt target regulation. Furthermore, cells transfected with β-catenin mutants incapable of binding to TCF/LEF increased BACE1 gene promoter activity. Interestingly, TCF4 knockdown reversed the effects of Wnt3a activation on BACE1 transcription. We found that TCF4 binds to the same region on BACE1 promoter following Wnt3a stimulation, indicating that TCF4 functions as a transcriptional repressor of BACE1 gene. In conclusion, Wnt/β-catenin stimulation may repress BACE1 transcription via binding of TCF4 to BACE1 gene, and therefore, activation of the Wnt pathway may hold the key to new treatments of Alzheimer disease.-Parr, C., Mirzaei, N., Christian, M., and Sastre, M. Activation of the Wnt/β-catenin pathway represses the transcription of the β-amyloid precursor protein cleaving enzyme (BACE1) via binding of T-cell factor-4 to BACE1 promoter.

  10. Nuclear AXIN2 represses MYC gene expression

    Energy Technology Data Exchange (ETDEWEB)

    Rennoll, Sherri A.; Konsavage, Wesley M.; Yochum, Gregory S., E-mail: gsy3@psu.edu

    2014-01-03

    Highlights: •AXIN2 localizes to cytoplasmic and nuclear compartments in colorectal cancer cells. •Nuclear AXIN2 represses the activity of Wnt-responsive luciferase reporters. •β-Catenin bridges AXIN2 to TCF transcription factors. •AXIN2 binds the MYC promoter and represses MYC gene expression. -- Abstract: The β-catenin transcriptional coactivator is the key mediator of the canonical Wnt signaling pathway. In the absence of Wnt, β-catenin associates with a cytosolic and multi-protein destruction complex where it is phosphorylated and targeted for proteasomal degradation. In the presence of Wnt, the destruction complex is inactivated and β-catenin translocates into the nucleus. In the nucleus, β-catenin binds T-cell factor (TCF) transcription factors to activate expression of c-MYC (MYC) and Axis inhibition protein 2 (AXIN2). AXIN2 is a member of the destruction complex and, thus, serves in a negative feedback loop to control Wnt/β-catenin signaling. AXIN2 is also present in the nucleus, but its function within this compartment is unknown. Here, we demonstrate that AXIN2 localizes to the nuclei of epithelial cells within normal and colonic tumor tissues as well as colorectal cancer cell lines. In the nucleus, AXIN2 represses expression of Wnt/β-catenin-responsive luciferase reporters and forms a complex with β-catenin and TCF. We demonstrate that AXIN2 co-occupies β-catenin/TCF complexes at the MYC promoter region. When constitutively localized to the nucleus, AXIN2 alters the chromatin structure at the MYC promoter and directly represses MYC gene expression. These findings suggest that nuclear AXIN2 functions as a rheostat to control MYC expression in response to Wnt/β-catenin signaling.

  11. TALENs-directed knockout of the full-length transcription factor Nrf1α that represses malignant behaviour of human hepatocellular carcinoma (HepG2) cells.

    Science.gov (United States)

    Ren, Yonggang; Qiu, Lu; Lü, Fenglin; Ru, Xufang; Li, Shaojun; Xiang, Yuancai; Yu, Siwang; Zhang, Yiguo

    2016-04-11

    The full-length Nrf1α is processed into distinct isoforms, which together regulate genes essential for maintaining cellular homeostasis and organ integrity, and liver-specific loss of Nrf1 in mice results in spontaneous hepatoma. Herein, we report that the human constitutive Nrf1α, rather than smaller Nrf1β/γ, expression is attenuated or abolished in the case of low-differentiated high-metastatic hepatocellular carcinomas. Therefore, Nrf1α is of importance in the physio-pathological origin and development, but its specific pathobiological function(s) remains elusive. To address this, TALENs-directed knockout of Nrf1α, but not Nrf1β/γ, is created in the human hepatocellular carcinoma (HepG2) cells. The resulting Nrf1α(-/-) cells are elongated, with slender spindle-shapes and enlarged gaps between cells observed under scanning electron microscope. When compared with wild-type controls, the invasive and migratory abilities of Nrf1α(-/-) cells are increased significantly, along with the cell-cycle G2-M arrest and S-phase reduction, as accompanied by suppressed apoptosis. Despite a modest increase in the soft-agar colony formation of Nrf1α(-/-) cells, its loss-of-function markedly promotes malgrowth of the subcutaneous carcinoma xenograft in nude mice with hepatic metastasis. Together with molecular expression results, we thus suppose requirement of Nrf1α (and major derivates) for gene regulatory mechanisms repressing cancer cell process (e.g. EMT) and malignant behaviour (e.g. migration).

  12. Translational repression contributes greater noise to gene expression than transcriptional repression.

    Science.gov (United States)

    Komorowski, Michał; Miekisz, Jacek; Kierzek, Andrzej M

    2009-01-01

    Stochastic effects in gene expression may result in different physiological states of individual cells, with consequences for pathogen survival and artificial gene network design. We studied the contributions of a regulatory factor to gene expression noise in four basic mechanisms of negative gene expression control: 1), transcriptional regulation by a protein repressor, 2), translational repression by a protein; 3), transcriptional repression by RNA; and 4), RNA interference with the translation. We investigated a general model of a two-gene network, using the chemical master equation and a moment generating function approach. We compared the expression noise of genes with the same effective transcription and translation initiation rates resulting from the action of different repressors, whereas previous studies compared the noise of genes with the same mean expression level but different initiation rates. Our results show that translational repression results in a higher noise than repression on the promoter level, and that this relationship does not depend on quantitative parameter values. We also show that regulation of protein degradation contributes more noise than regulated degradation of mRNA. These are unexpected results, because previous investigations suggested that translational regulation is more accurate. The relative magnitude of the noise introduced by protein and RNA repressors depends on the protein and mRNA degradation rates, and we derived expressions for the threshold below which the noise introduced by a protein repressor is higher than the noise introduced by an RNA repressor.

  13. Glucose repression in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Kayikci, Omur; Nielsen, Jens

    2015-01-01

    Glucose is the primary source of energy for the budding yeast Saccharomyces cerevisiae. Although yeast cells can utilize a wide range of carbon sources, presence of glucose suppresses molecular activities involved in the use of alternate carbon sources as well as it represses respiration and gluc......Glucose is the primary source of energy for the budding yeast Saccharomyces cerevisiae. Although yeast cells can utilize a wide range of carbon sources, presence of glucose suppresses molecular activities involved in the use of alternate carbon sources as well as it represses respiration...... and gluconeogenesis. This dominant effect of glucose on yeast carbon metabolism is coordinated by several signaling and metabolic interactions that mainly regulate transcriptional activity but are also effective at post-transcriptional and post-translational levels. This review describes effects of glucose repression...

  14. The unified theory of repression.

    Science.gov (United States)

    Erdelyi, Matthew Hugh

    2006-10-01

    Repression has become an empirical fact that is at once obvious and problematic. Fragmented clinical and laboratory traditions and disputed terminology have resulted in a Babel of misunderstandings in which false distinctions are imposed (e.g., between repression and suppression) and necessary distinctions not drawn (e.g., between the mechanism and the use to which it is put, defense being just one). "Repression" was introduced by Herbart to designate the (nondefensive) inhibition of ideas by other ideas in their struggle for consciousness. Freud adapted repression to the defensive inhibition of "unbearable" mental contents. Substantial experimental literatures on attentional biases, thought avoidance, interference, and intentional forgetting exist, the oldest prototype being the work of Ebbinghaus, who showed that intentional avoidance of memories results in their progressive forgetting over time. It has now become clear, as clinicians had claimed, that the inaccessible materials are often available and emerge indirectly (e.g., procedurally, implicitly). It is also now established that the Ebbinghaus retention function can be partly reversed, with resulting increases of conscious memory over time (hypermnesia). Freud's clinical experience revealed early on that exclusion from consciousness was effected not just by simple repression (inhibition) but also by a variety of distorting techniques, some deployed to degrade latent contents (denial), all eventually subsumed under the rubric of defense mechanisms ("repression in the widest sense"). Freudian and Bartlettian distortions are essentially the same, even in name, except for motive (cognitive vs. emotional), and experimentally induced false memories and other "memory illusions" are laboratory analogs of self-induced distortions.

  15. A Simple Grammar Defines Activating and Repressing cis-Regulatory Elements in Photoreceptors

    Directory of Open Access Journals (Sweden)

    Michael A. White

    2016-10-01

    Full Text Available Transcription factors often activate and repress different target genes in the same cell. How activation and repression are encoded by different arrangements of transcription factor binding sites in cis-regulatory elements is poorly understood. We investigated how sites for the transcription factor CRX encode both activation and repression in photoreceptors by assaying thousands of genomic and synthetic cis-regulatory elements in wild-type and Crx−/− retinas. We found that sequences with high affinity for CRX repress transcription, whereas sequences with lower affinity activate. This rule is modified by a cooperative interaction between CRX sites and sites for the transcription factor NRL, which overrides the repressive effect of high affinity for CRX. Our results show how simple rearrangements of transcription factor binding sites encode qualitatively different responses to a single transcription factor and explain how CRX plays multiple cis-regulatory roles in the same cell.

  16. Purification of DNA polymerase II stimulatory factor I, a yeast single-stranded DNA-binding protein.

    OpenAIRE

    1990-01-01

    Incidental to the purification of yeast DNA polymerase II was the observation that various chromatographic fractions contained activities that stimulated synthesis by this polymerase. In this paper we report the purification and initial characterization of one such factor, stimulatory factor I (SFI). SFI, which is associated with an apparent complex of three polypeptides of 66, 37, and 13.5 kDa, binds preferentially to single-stranded DNA, possibly explaining its ability to stimulate DNA poly...

  17. Rule of Repression in Chile.

    Science.gov (United States)

    American Indian Journal, 1979

    1979-01-01

    This report on the current condition of the Mapuche Indians of Chile is edited from a document on the "Situation of Human Rights in Chile" and details the repressive and inhumane treatment of the largest indigenous ethnic minority in the country. (Author/RTS)

  18. The Runx1 Transcription Factor Inhibits the Differentiation of Naive CD4+ T Cells into the Th2 Lineage by Repressing GATA3 Expression

    Science.gov (United States)

    Komine, Okiru; Hayashi, Keitaro; Natsume, Waka; Watanabe, Toshio; Seki, Youichi; Seki, Noriyasu; Yagi, Ryoji; Sukzuki, Wataru; Tamauchi, Hidekazu; Hozumi, Katsuto; Habu, Sonoko; Kubo, Masato; Satake, Masanobu

    2003-01-01

    Differentiation of naive CD4+ T cells into helper T (Th) cells is controlled by a combination of several transcriptional factors. In this study, we examined the functional role of the Runx1 transcription factor in Th cell differentiation. Naive T cells from transgenic mice expressing a dominant interfering form of Runx1 exhibited enhanced interleukin 4 production and efficient Th2 differentiation. In contrast, transduction of Runx1 into wild-type T cells caused a complete attenuation of Th2 differentiation and was accompanied by the cessation of GATA3 expression. Furthermore, endogenous expression of Runx1 in naive T cells declined after T cell receptor stimulation, at the same time that expression of GATA3 increased. We conclude that Runx1 plays a novel role as a negative regulator of GATA3 expression, thereby inhibiting the Th2 cell differentiation. PMID:12835475

  19. The extracellular adherence protein (Eap) of Staphylococcus aureus acts as a proliferation and migration repressing factor that alters the cell morphology of keratinocytes.

    Science.gov (United States)

    Eisenbeis, Janina; Peisker, Henrik; Backes, Christian S; Bur, Stephanie; Hölters, Sebastian; Thewes, Nicolas; Greiner, Markus; Junker, Christian; Schwarz, Eva C; Hoth, Markus; Junker, Kerstin; Preissner, Klaus T; Jacobs, Karin; Herrmann, Mathias; Bischoff, Markus

    2017-02-01

    Staphyloccocus aureus is a major human pathogen and a common cause for superficial and deep seated wound infections. The pathogen is equipped with a large arsenal of virulence factors, which facilitate attachment to various eukaryotic cell structures and modulate the host immune response. One of these factors is the extracellular adherence protein Eap, a member of the "secretable expanded repertoire adhesive molecules" (SERAM) protein family that possesses adhesive and immune modulatory properties. The secreted protein was previously shown to impair wound healing by interfering with host defense and neovascularization. However, its impact on keratinocyte proliferation and migration, two major steps in the re-epithelialization process of wounds, is not known. Here, we report that Eap affects the proliferation and migration capacities of keratinocytes by altering their morphology and adhesive properties. In particular, treatment of non-confluent HaCaT cell cultures with Eap resulted in cell morphology changes as well as a significant reduction in cell proliferation and migration. Eap-treated HaCaT cells changed their appearance from an oblong via a trapezoid to an astral-like shape, accompanied by decreases in cell volume and cell stiffness, and exhibited significantly increased cell adhesion. Eap had a similar influence on endothelial and cancer cells, indicative for a general effect of Eap on eukaryotic cell morphology and functions. Specifically, Eap was found to interfere with growth factor-stimulated activation of the mitogen-activated protein kinase (MAPK) pathway that is known to be responsible for cell shape modulation, induction of proliferation and migration of epithelial cells. Western blot analyses revealed that Eap blocked the phosphorylation of extracellular signal-regulated kinase 1 and 2 (Erk1/2) in keratinocyte growth factor (KGF)-stimulated HaCaT cells. Together, these data add another antagonistic mechanism of Eap in wound healing, whereby the

  20. Prophylactic Administration of Fucoidan Represses Cancer Metastasis by Inhibiting Vascular Endothelial Growth Factor (VEGF and Matrix Metalloproteinases (MMPs in Lewis Tumor-Bearing Mice

    Directory of Open Access Journals (Sweden)

    Tse-Hung Huang

    2015-04-01

    Full Text Available Fucoidan, a heparin-like sulfated polysaccharide, is rich in brown algae. It has a wide assortment of protective activities against cancer, for example, induction of hepatocellular carcinoma senescence, induction of human breast and colon carcinoma apoptosis, and impediment of lung cancer cells migration and invasion. However, the anti-metastatic mechanism that fucoidan exploits remains elusive. In this report, we explored the effects of fucoidan on cachectic symptoms, tumor development, lung carcinoma cell spreading and proliferation, as well as expression of metastasis-associated proteins in the Lewis lung carcinoma (LLC cells-inoculated mice model. We discovered that administration of fucoidan has prophylactic effects on mitigation of cachectic body weight loss and improvement of lung masses in tumor-inoculated mice. These desired effects are attributed to inhibition of LLC spreading and proliferation in lung tissues. Fucoidan also down-regulates expression of matrix metalloproteinases (MMPs, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB and vascular endothelial growth factor (VEGF. Moreover, the tumor-bearing mice supplemented with fucoidan indeed benefit from an ensemble of the chemo-phylacticity. The fact is that fucoidan significantly decreases viability, migration, invasion, and MMPs activities of LLC cells. In summary, fucoidan is suitable to act as a chemo-preventative agent for minimizing cachectic symptoms as well as inhibiting lung carcinoma metastasis through down-regulating metastatic factors VEGF and MMPs.

  1. Prophylactic administration of fucoidan represses cancer metastasis by inhibiting vascular endothelial growth factor (VEGF) and matrix metalloproteinases (MMPs) in Lewis tumor-bearing mice.

    Science.gov (United States)

    Huang, Tse-Hung; Chiu, Yi-Han; Chan, Yi-Lin; Chiu, Ya-Huang; Wang, Hang; Huang, Kuo-Chin; Li, Tsung-Lin; Hsu, Kuang-Hung; Wu, Chang-Jer

    2015-04-03

    Fucoidan, a heparin-like sulfated polysaccharide, is rich in brown algae. It has a wide assortment of protective activities against cancer, for example, induction of hepatocellular carcinoma senescence, induction of human breast and colon carcinoma apoptosis, and impediment of lung cancer cells migration and invasion. However, the anti-metastatic mechanism that fucoidan exploits remains elusive. In this report, we explored the effects of fucoidan on cachectic symptoms, tumor development, lung carcinoma cell spreading and proliferation, as well as expression of metastasis-associated proteins in the Lewis lung carcinoma (LLC) cells-inoculated mice model. We discovered that administration of fucoidan has prophylactic effects on mitigation of cachectic body weight loss and improvement of lung masses in tumor-inoculated mice. These desired effects are attributed to inhibition of LLC spreading and proliferation in lung tissues. Fucoidan also down-regulates expression of matrix metalloproteinases (MMPs), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and vascular endothelial growth factor (VEGF). Moreover, the tumor-bearing mice supplemented with fucoidan indeed benefit from an ensemble of the chemo-phylacticity. The fact is that fucoidan significantly decreases viability, migration, invasion, and MMPs activities of LLC cells. In summary, fucoidan is suitable to act as a chemo-preventative agent for minimizing cachectic symptoms as well as inhibiting lung carcinoma metastasis through down-regulating metastatic factors VEGF and MMPs.

  2. Rice osa-miR171c Mediates Phase Change from Vegetative to Reproductive Development and Shoot Apical Meristem Maintenance by Repressing Four OsHAM Transcription Factors.

    Directory of Open Access Journals (Sweden)

    Tian Fan

    Full Text Available Phase change from vegetative to reproductive development is one of the critical developmental steps in plants, and it is regulated by both environmental and endogenous factors. The maintenance of shoot apical meristem (SAM identity, miRNAs and flowering integrators are involved in this phase change process. Here, we report that the miRNA osa-miR171c targets four GRAS (GAI-RGA-SCR plant-specific transcription factors (OsHAM1, OsHAM2, OsHAM3, and OsHAM4 to control the floral transition and maintenance of SAM indeterminacy in rice (Oryza sativa. We characterized a rice T-DNA insertion delayed heading (dh mutant, where the expression of OsMIR171c gene is up-regulated. This mutant showed pleiotropic phenotypic defects, including especially prolonged vegetative phase, delayed heading date, and bigger shoot apex. Parallel expression analysis showed that osa-miR171c controlled the expression change of four OsHAMs in the shoot apex during floral transition, and responded to light. In the dh mutant, the expression of the juvenile-adult phase change negative regulator osa-miR156 was up-regulated, expression of the flowering integrators Hd3a and RFT1 was inhibited, and expression of FON4 negative regulators involved in the maintenance of SAM indeterminacy was also inhibited. From these data, we propose that the inhibition of osa-miR171c-mediated OsHAM transcription factors regulates the phase transition from vegetative to reproductive development by maintaining SAM indeterminacy and inhibiting flowering integrators.

  3. microRNA-142 is upregulated by tumor necrosis factor-alpha and triggers apoptosis in human gingival epithelial cells by repressing BACH2 expression

    Science.gov (United States)

    Li, Song; Song, Zhongchen; Dong, Jiachen; Shu, Rong

    2017-01-01

    Tumor necrosis factor-alpha (TNF-α) has been shown to cause apoptosis of gingival epithelial cells (GECs) in periodontitis. However, the underlying molecular mechanism is still unclear. In this study, we showed that miR-142 expression was significantly elevated in human GECs after exposure to TNF-α. Such induction was in a time- and concentration-dependent manner. Serum miR-142 levels were positively correlated with serum TNF-α levels in patients with chronic periodontitis (r = 0.314, P = 0.0152). Depletion of miR-142 was found to attenuate TNF-α-induced apoptosis, as determined by TUNEL staining and caspase-3 activity assays. In contrast, overexpression of miR-142 significantly reduced viability and induced apoptosis in GECs. Basic leucine zipper transcription factor 2 (BACH2) was identified to be a functional target of miR-142. Overexpression of miR-142 caused a 3-fold reduction of BACH2 protein in primary GECs. Overexpression of BACH2 significantly reversed miR-142- or TNF-α-induced apoptosis of GECs. Similar to the findings with miR-142 mimic, depletion of BACH2 significantly promoted apoptosis in GECs, which was accompanied by decreased expression of Bcl-2 and Bcl-xL and increased expression of Bax and Bim. Overall, miR-142 mediates TNF-α-induced apoptosis in gingival epithelial cells by targeting BACH2 and may represent a potential therapeutic target for periodontitis. PMID:28123644

  4. Reverse translation of phase I biomarker findings links the activity of angiotensin-(1–7 to repression of hypoxia inducible factor-1α in vascular sarcomas

    Directory of Open Access Journals (Sweden)

    Petty W

    2012-09-01

    Full Text Available Abstract Background In a phase I study of angiotensin-(1–7 [Ang-(1–7], clinical benefit was associated with reduction in plasma placental growth factor (PlGF concentrations. The current study examines Ang-(1–7 induced changes in biomarkers according to cancer type and investigates mechanisms of action engaged in vitro. Methods Plasma biomarkers were measured prior to Ang-(1–7 administration as well as 1, 2, 3, 4, and 6 hours after treatment. Tests for interaction were performed to determine the impact of cancer type on angiogenic hormone levels. If a positive interaction was detected, treatment-induced biomarker changes for individual cancer types were assessed. To investigate mechanisms of action, in vitro growth assays were performed using a murine endothelioma cell line (EOMA. PCR arrays were performed to identify and statistically validate genes that were altered by Ang-(1–7 treatment in these cells. Results Tests for interaction controlled for dose cohort and clinical response indicated a significant impact of cancer type on post-treatment VEGF and PlGF levels. Following treatment, PlGF levels decreased over time in patients with sarcoma (P = .007. Treatment of EOMA cells with increasing doses of Ang-(1–7 led to significant growth suppression at doses as low as 100 nM. PCR arrays identified 18 genes that appeared to have altered expression after Ang-(1–7 treatment. Replicate analyses confirmed significant changes in 8 genes including reduction in PlGF (P = .04 and hypoxia inducible factor 1α (HIF-1α expression (P  Conclusions Ang-(1–7 has clinical and pre-clinical activity for vascular sarcomas that is linked to reduced HIF-1α and PlGF expression.

  5. Mechanism of action of the Escherichia coli phage shock protein PspA in repression of the AAA family transcription factor PspF.

    Science.gov (United States)

    Elderkin, Sarah; Jones, Susan; Schumacher, Jörg; Studholme, David; Buck, Martin

    2002-06-28

    The PspA protein, a negative regulator of the Escherichia coli phage shock psp operon, is produced when virulence factors are exported through secretins in many Gram-negative pathogenic bacteria and its homologue in plants, VIPP1, plays a critical role in thylakoid biogenesis, essential for photosynthesis. Activation of transcription by the enhancer-dependent bacterial sigma(54) containing RNA polymerase occurs through ATP hydrolysis-driven protein conformational changes enabled by activator proteins that belong to the large AAA(+) mechanochemical protein family. We show that PspA directly and specifically acts upon and binds to the AAA(+) domain of the PspF transcription activator. Interactions involving PspF and nucleotide are changed by the action of PspA. These changes and the complexes that form between PspF and PspA can explain how PspA exerts its negative effects upon transcription activated by PspF, and are of significance when considering how activities of other AAA(+) proteins might be controlled.

  6. Human Cortical Neural Stem Cells Expressing Insulin-Like Growth Factor-I: A Novel Cellular Therapy for Alzheimer's Disease.

    Science.gov (United States)

    McGinley, Lisa M; Sims, Erika; Lunn, J Simon; Kashlan, Osama N; Chen, Kevin S; Bruno, Elizabeth S; Pacut, Crystal M; Hazel, Tom; Johe, Karl; Sakowski, Stacey A; Feldman, Eva L

    2016-03-01

    Alzheimer's disease (AD) is the most prevalent age-related neurodegenerative disorder and a leading cause of dementia. Current treatment fails to modify underlying disease pathologies and very little progress has been made to develop effective drug treatments. Cellular therapies impact disease by multiple mechanisms, providing increased efficacy compared with traditional single-target approaches. In amyotrophic lateral sclerosis, we have shown that transplanted spinal neural stem cells (NSCs) integrate into the spinal cord, form synapses with the host, improve inflammation, and reduce disease-associated pathologies. Our current goal is to develop a similar "best in class" cellular therapy for AD. Here, we characterize a novel human cortex-derived NSC line modified to express insulin-like growth factor-I (IGF-I), HK532-IGF-I. Because IGF-I promotes neurogenesis and synaptogenesis in vivo, this enhanced NSC line offers additional environmental enrichment, enhanced neuroprotection, and a multifaceted approach to treating complex AD pathologies. We show that autocrine IGF-I production does not impact the cell secretome or normal cellular functions, including proliferation, migration, or maintenance of progenitor status. However, HK532-IGF-I cells preferentially differentiate into gamma-aminobutyric acid-ergic neurons, a subtype dysregulated in AD; produce increased vascular endothelial growth factor levels; and display an increased neuroprotective capacity in vitro. We also demonstrate that HK532-IGF-I cells survive peri-hippocampal transplantation in a murine AD model and exhibit long-term persistence in targeted brain areas. In conclusion, we believe that harnessing the benefits of cellular and IGF-I therapies together will provide the optimal therapeutic benefit to patients, and our findings support further preclinical development of HK532-IGF-I cells into a disease-modifying intervention for AD. ©AlphaMed Press.

  7. Yes-associated protein/TEA domain family member and hepatocyte nuclear factor 4-alpha (HNF4α) repress reciprocally to regulate hepatocarcinogenesis in rats and mice.

    Science.gov (United States)

    Cai, Wang-Yu; Lin, Ling-Yun; Hao, Han; Zhang, Sai-Man; Ma, Fei; Hong, Xin-Xin; Zhang, Hui; Liu, Qing-Feng; Ye, Guo-Dong; Sun, Guang-Bin; Liu, Yun-Jia; Li, Sheng-Nan; Xie, Yuan-Yuan; Cai, Jian-Chun; Li, Bo-An

    2017-04-01

    Great progress has been achieved in the study of Hippo signaling in regulating tumorigenesis; however, the downstream molecular events that mediate this process have not been completely defined. Moreover, regulation of Hippo signaling during tumorigenesis in hepatocellular carcinoma (HCC) remains largely unknown. In the present study, we systematically investigated the relationship between Yes-associated protein/TEA domain family member (YAP-TEAD) and hepatocyte nuclear factor 4-alpha (HNF4α) in the hepatocarcinogenesis of HCC cells. Our results indicated that HNF4α expression was negatively regulated by YAP1 in HCC cells by a ubiquitin proteasome pathway. By contrast, HNF4α was found to directly associate with TEAD4 to compete with YAP1 for binding to TEAD4, thus inhibiting the transcriptional activity of YAP-TEAD and expression of their target genes. Moreover, overexpression of HNF4α was found to significantly compromise YAP-TEAD-induced HCC cell proliferation and stem cell expansion. Finally, we documented the regulatory mechanism between YAP-TEAD and HNF4α in rat and mouse tumor models, which confirmed our in vitro results. There is a double-negative feedback mechanism that controls TEAD-YAP and HNF4α expression in vitro and in vivo, thereby regulating cellular proliferation and differentiation. Given that YAP acts as a dominant oncogene in HCC and plays a crucial role in stem cell homeostasis and tissue regeneration, manipulating the interaction between YAP, TEADs, and HNF4α may provide a new approach for HCC treatment and regenerative medicine. (Hepatology 2017;65:1206-1221). © 2016 by the American Association for the Study of Liver Diseases.

  8. Regulation of pqs quorum sensing via catabolite repression control in Pseudomonas aeruginosa

    DEFF Research Database (Denmark)

    Zhang, Lianbo; Gao, Qingguo; Chen, Wanying;

    2013-01-01

    that the Pseudomonas aeruginosa catabolite repression control protein regulates the Pseudomonas quinolone signal quorum sensing, which further controls synthesis of virulence factor pyocyanin, biofilm formation and survival during infection models. Our study suggests that deregulation of the catabolite repression by P...

  9. Mechanisms of transcriptional repression by histone lysine methylation

    DEFF Research Database (Denmark)

    Hublitz, Philip; Albert, Mareike; Peters, Antoine H F M

    2009-01-01

    . In this report, we review the recent literature to deduce mechanisms underlying Polycomb and H3K9 methylation mediated repression, and describe the functional interplay with activating H3K4 methylation. We summarize recent data that indicate a close relationship between GC density of promoter sequences......, transcription factor binding and the antagonizing activities of distinct epigenetic regulators such as histone methyltransferases (HMTs) and histone demethylases (HDMs). Subsequently, we compare chromatin signatures associated with different types of transcriptional outcomes from stable repression to highly...... dynamic regulated genes, strongly suggesting that the interplay of different epigenetic pathways is essential in defining specific types of heritable chromatin and associated transcriptional states....

  10. Neuron-restrictive silencer factor (NRSF) represses cocaine- and amphetamine-regulated transcript (CART) transcription and antagonizes cAMP-response element-binding protein signaling through a dual NRSE mechanism.

    Science.gov (United States)

    Zhang, Jing; Wang, Sihan; Yuan, Lin; Yang, Yinxiang; Zhang, Bowen; Liu, Qingbin; Chen, Lin; Yue, Wen; Li, Yanhua; Pei, Xuetao

    2012-12-14

    Cocaine- and amphetamine-regulated transcript (CART) peptide plays a pivotal role in neuroprotection against stroke-related brain injury. However, the regulatory mechanism on CART transcription, especially the repression mechanism, is not fully understood. Here, we show that the transcriptional repressor neuron-restrictive silencer elements (NRSF, also known as REST) represses CART expression through direct binding to two NRSF-binding elements (NRSEs) in the CART promoter and intron 1 (named pNRSE and iNRSE, respectively). EMSA show that NRSF binds to pNRSE and iNRSE directly in vitro. ChIP assays show that NRSF recruits differential co-repressor complexes including CoREST and HDAC1 to these NRSEs. The presence of both NRSEs is required for efficient repression of CART transcription as indicated by reporter gene assays. NRSF overexpression antagonizes forskolin-mediated up-regulation of CART mRNA and protein. Ischemia insult triggered by oxygen-glucose deprivation (OGD) enhances NRSF mRNA levels and then NRSF antagonizes the CREB signaling on CART activation, leading to augmented cell death. Depletion of NRSF in combination with forskolin treatment increases neuronal survival after ischemic insult. These findings reveal a novel dual NRSE mechanism by which NRSF represses CART expression and suggest that NRSF may serve as a therapeutic target for stroke treatment.

  11. PICKLE acts during germination to repress expression of embryonic traits

    Science.gov (United States)

    Li, Hui-Chun; Chuang, King; Henderson, James T.; Rider, Stanley Dean; Bai, Yinglin; Zhang, Heng; Fountain, Matthew; Gerber, Jacob; Ogas, Joe

    2008-01-01

    SUMMARY PICKLE (PKL) codes for a CHD3 chromatin remodeling factor that plays multiple roles in Arabidopsis growth and development. Previous analysis of the expression of genes that exhibit PKL-dependent regulation suggested that PKL acts during germination to repress expression of embryonic traits. In this study, we examined the expression of PKL protein to investigate when and where PKL acts to regulate development. A PKL:eGFP translational fusion is preferentially localized in the nucleus of cells, consistent with the proposed role for PKL as a chromatin remodeling factor. A steroid-inducible version of PKL - a fusion of PKL to the glucocorticoid receptor (PKL:GR) - was used to examine when PKL acts to repress expression of embryonic traits. We found that activation of PKL:GR during germination was sufficient to repress expression of embryonic traits in the primary roots of pkl seedlings whereas activation of PKL:GR after germination had little effect. In contrast, we observed that PKL is required continuously after germination to repress expression of PHERES1, a type I MADS box gene that is normally expressed during early embryogenesis in wild-type plants. Thus PKL acts at multiple points during development to regulate patterns of gene expression in Arabidopsis. PMID:16359393

  12. miRNA-dependent translational repression in the Drosophila ovary.

    Directory of Open Access Journals (Sweden)

    John Reich

    Full Text Available BACKGROUND: The Drosophila ovary is a tissue rich in post-transcriptional regulation of gene expression. Many of the regulatory factors are proteins identified via genetic screens. The more recent discovery of microRNAs, which in other animals and tissues appear to regulate translation of a large fraction of all mRNAs, raised the possibility that they too might act during oogenesis. However, there has been no direct demonstration of microRNA-dependent translational repression in the ovary. METHODOLOGY/PRINCIPAL FINDINGS: Here, quantitative analyses of transcript and protein levels of transgenes with or without synthetic miR-312 binding sites show that the binding sites do confer translational repression. This effect is dependent on the ability of the cells to produce microRNAs. By comparison with microRNA-dependent translational repression in other cell types, the regulated mRNAs and the protein factors that mediate repression were expected to be enriched in sponge bodies, subcellular structures with extensive similarities to the P bodies found in other cells. However, no such enrichment was observed. CONCLUSIONS/SIGNIFICANCE: Our results reveal the variety of post-transcriptional regulatory mechanisms that operate in the Drosophila ovary, and have implications for the mechanisms of miRNA-dependent translational control used in the ovary.

  13. RNAi and heterochromatin repress centromeric meiotic recombination

    DEFF Research Database (Denmark)

    Ellermeier, Chad; Higuchi, Emily C; Phadnis, Naina

    2010-01-01

    to genetic disabilities, including birth defects. The basis by which centromeric meiotic recombination is repressed has been largely unknown. We report here that, in fission yeast, RNAi functions and Clr4-Rik1 (histone H3 lysine 9 methyltransferase) are required for repression of centromeric recombination...

  14. A core erythroid transcriptional network is repressed by a master regulator of myelo-lymphoid differentiation.

    Science.gov (United States)

    Wontakal, Sandeep N; Guo, Xingyi; Smith, Cameron; MacCarthy, Thomas; Bresnick, Emery H; Bergman, Aviv; Snyder, Michael P; Weissman, Sherman M; Zheng, Deyou; Skoultchi, Arthur I

    2012-03-06

    Two mechanisms that play important roles in cell fate decisions are control of a "core transcriptional network" and repression of alternative transcriptional programs by antagonizing transcription factors. Whether these two mechanisms operate together is not known. Here we report that GATA-1, SCL, and Klf1 form an erythroid core transcriptional network by co-occupying >300 genes. Importantly, we find that PU.1, a negative regulator of terminal erythroid differentiation, is a highly integrated component of this network. GATA-1, SCL, and Klf1 act to promote, whereas PU.1 represses expression of many of the core network genes. PU.1 also represses the genes encoding GATA-1, SCL, Klf1, and important GATA-1 cofactors. Conversely, in addition to repressing PU.1 expression, GATA-1 also binds to and represses >100 PU.1 myelo-lymphoid gene targets in erythroid progenitors. Mathematical modeling further supports that this dual mechanism of repressing both the opposing upstream activator and its downstream targets provides a synergistic, robust mechanism for lineage specification. Taken together, these results amalgamate two key developmental principles, namely, regulation of a core transcriptional network and repression of an alternative transcriptional program, thereby enhancing our understanding of the mechanisms that establish cellular identity.

  15. Repressive coping, stigmatization, psychological distress, and quality of life among behavioral weight management participants.

    Science.gov (United States)

    Truong, Erin A K; Olson, KayLoni L; Emery, Charles F

    2016-08-01

    Repressive coping has been associated with elevated risk of disease and negative health outcomes in past studies. Although a prior study of healthy men found that repression was associated with lower body mass index (BMI), no study has examined repressive coping among obese individuals. This study examined the relationship of repressive coping with BMI and obesity-relevant psychosocial factors among 104 overweight and obese participants in a behavioral weight management program. Participants completed questionnaires assessing repressive coping, stigmatization, psychological distress, and quality of life. BMI was objectively measured. Repressors reported lower stigmatization, anxiety, and depression as well as higher emotional and weight-related quality of life. Repressors and non-repressors had equivalent BMI and reported similar impairment in physical quality of life, but stigmatization moderated the relationship between repressive coping and physical quality of life (b=0.31, p=0.039), reflecting better physical quality of life among non-repressors with lower stigmatization. Obese individuals who engage in repressive coping may tend to underreport psychological symptoms, social difficulties, and impairments in quality of life. Higher physical quality of life among non-repressors with lower stigmatization may reflect a combined influence of coping and social processes in physical quality of life among obese individuals.

  16. Glucocorticoid Receptor-Mediated Repression of Pro-Inflammatory Genes in Rheumatoid Arthritis

    Science.gov (United States)

    2015-10-01

    1 AWARD NUMBER: W81XWH-14-1-0314 TITLE: Glucocorticoid Receptor-Mediated Repression of Pro-Inflammatory Genes in Rheumatoid Arthritis ...19 Sep 2015 4. TITLE AND SUBTITLE Glucocorticoid Receptor-Mediated Repression of Pro- Inflammatory Genes in Rheumatoid Arthritis 5a. CONTRACT NUMBER... arthritis (RA) patients rely on glucocorticoids (GCs) at some point during the disease. GCs signal through the GC receptor (GR), a transcription factor that

  17. Translational repression by PUF proteins in vitro.

    Science.gov (United States)

    Chritton, Jacqueline J; Wickens, Marvin

    2010-06-01

    PUF (Pumilio and FBF) proteins provide a paradigm for mRNA regulatory proteins. They interact with specific sequences in the 3' untranslated regions (UTRs) of target mRNAs and cause changes in RNA stability or translational activity. Here we describe an in vitro translation assay that reconstitutes the translational repression activity of canonical PUF proteins. In this system, recombinant PUF proteins were added to yeast cell lysates to repress reporter mRNAs bearing the 3'UTRs of specific target mRNAs. PUF proteins from Saccharomyces cerevisiae and Caenorhabditis elegans were active in the assay and were specific by multiple criteria. Puf5p, a yeast PUF protein, repressed translation of four target RNAs. Repression mediated by the HO 3'UTR was particularly efficient, due to a specific sequence in that 3'UTR. The sequence lies downstream from the PUF binding site and does not affect PUF protein binding. PUF-mediated repression was sensitive to the distance between the ORF and the regulatory elements in the 3'UTR: excessive distance decreased repression activity. Our data demonstrate that PUF proteins function in vitro across species, that different mRNA targets are regulated differentially, and that specific ancillary sequences distinguish one yeast mRNA target from another. We suggest a model in which PUF proteins can control translation termination or elongation.

  18. Antistress effect of red ginseng in brain cells is mediated by TACE repression via PADI4.

    Science.gov (United States)

    Kim, Eun-Hye; Kim, In-Hye; Ha, Jung-Ah; Choi, Kwang-Tae; Pyo, Suhkneung; Rhee, Dong-Kwon

    2013-07-01

    Ginseng is known to have antistress effects. Previously, red ginseng (RG) was shown to repress stress-induced peptidyl arginine deiminase type IV (PADI4) via estrogen receptor β (ERβ) in the brain, thus inhibiting brain cell apoptosis. Moreover, tumor necrosis factor (TNF)-α plays a critical role in immobilization (IMO) stress. However, the signaling pathway of RG-mediated repressesion of inflammation is not completely understood. In this study, we determined how RG modulated gene expression in stressed brain cells. Since secretion of TNF-α is modulated via TNF-α converting enzyme (TACE) and nuclear factor (NF)-κB, we examined the inflammatory pathway in stressed brain cells. Immunohistochemistry revealed that TACE was induced by IMO stress, but RG repressed TACE induction. Moreover, PADI4 siRNA repressed TACE expression compared to the mock transfected control suggesting that PADI4 was required for TACE expression. A reporter assay also revealed that H2O2 oxidative stress induced NF-κB in neuroblastoma SK-N-SH cells, however, RG pretreatment repressed NF-κB induction. These findings were supported by significant induction of nitric oxide and reactive oxygen species (ROS) by oxidative stress, which could be repressed by RG administration. Taken together, RG appeared to repress stress-induced PADI4 via TACE and NF-κB in brain cells thus preventing production of ROS and subsequently protecting brain cells from apoptosis.

  19. Snai1 represses Nanog to promote embryonic stem cell differentiation

    Directory of Open Access Journals (Sweden)

    F. Galvagni

    2015-06-01

    Full Text Available Embryonic stem cell (ESC self-renewal and pluripotency is maintained by an external signaling pathways and intrinsic regulatory networks involving ESC-specific transcriptional complexes (mainly formed by OCT3/4, Sox2 and Nanog proteins, the Polycomb repressive complex 2 (PRC2 and DNA methylation [1–8]. Among these, Nanog represents the more ESC specific factor and its repression correlates with the loss of pluripotency and ESC differentiation [9–11]. During ESC early differentiation, many development-associated genes become upregulated and although, in general, much is known about the pluripotency self-renewal circuitry, the molecular events that lead ESCs to exit from pluripotency and begin differentiation are largely unknown. Snai1 is one the most early induced genes during ESC differentiation in vitro and in vivo [12,13]. Here we show that Snai1 is able to directly repress several stemness-associated genes including Nanog. We use a ESC stable-line expressing a inducible Snai1 protein. We here show microarray analysis of embryonic stem cells (ESC expressing Snail-ER at various time points of induction with 4-OH. Data were deposited in Gene Expression Omnibus (GEO datasets under reference GSE57854 and here: http://epigenetics.hugef-research.org/data.php.

  20. Mitosis-associated repression in development.

    Science.gov (United States)

    Esposito, Emilia; Lim, Bomyi; Guessous, Ghita; Falahati, Hanieh; Levine, Michael

    2016-07-01

    Transcriptional repression is a pervasive feature of animal development. Here, we employ live-imaging methods to visualize the Snail repressor, which establishes the boundary between the presumptive mesoderm and neurogenic ectoderm of early Drosophila embryos. Snail target enhancers were attached to an MS2 reporter gene, permitting detection of nascent transcripts in living embryos. The transgenes exhibit initially broad patterns of transcription but are refined by repression in the mesoderm following mitosis. These observations reveal a correlation between mitotic silencing and Snail repression. We propose that mitosis and other inherent discontinuities in transcription boost the activities of sequence-specific repressors, such as Snail. © 2016 Esposito et al.; Published by Cold Spring Harbor Laboratory Press.

  1. Basic Pentacysteine Proteins Repress Abscisic Acid Insensitive4 Expression via Direct Recruitment of the Polycomb-Repressive Complex 2 in Arabidopsis Root Development.

    Science.gov (United States)

    Mu, Ying; Zou, Meijuan; Sun, Xuwu; He, Baoye; Xu, Xiumei; Liu, Yini; Zhang, Lixin; Chi, Wei

    2017-01-30

    Plant transcription factors generally act in complex regulatory networks that function at multiple levels to govern plant developmental programs. Dissection of the interconnections among different classes of transcription factors can elucidate these regulatory networks and thus improve our understanding of plant development. Here, we investigated the molecular and functional relationships of the transcription factors ABSCISIC ACID INSENSITIVE 4 (ABI4) and members of the BASIC PENTACYSTEINE (BPC) family in lateral root (LR) development of Arabidopsis thaliana Genetic analysis showed that BPCs promote LR development by repressing ABI4 expression. Molecular analysis showed that BPCs bind to the ABI4 promoter and repress ABI4 transcription in roots. BPCs directly recruit the Polycomb Repressive Complex 2 (PRC2) to the ABI4 locus and epigenetically repress ABI4 expression by catalyzing the trimethylation of histone H3 at lysine 27. In addition, BPCs and ABI4 coordinate their activities to fine-tune the levels of PIN-FORMED1, a component of the auxin signaling pathway, and thus modulate LR formation. These results establish a functional relationship between two universal and multiple-role transcription factors and provide insight into the mechanisms of the transcriptional regulatory networks that affect Arabidopsis organogenesis.

  2. Repression-Sensitization and Health Behavior.

    Science.gov (United States)

    Gayton, William F.; And Others

    1978-01-01

    Examined relationship between repression-sensitization (R-S) and visits to prison infirmary for males during a one-year period. Main effect for R-S dimension was significant for total number of visits, number of medically justified visits, and number of medically unjustified visits. Sensitizers had significantly more visits than repressors.…

  3. The great repression: chromatin and cryptic transcription.

    Science.gov (United States)

    Hennig, Bianca P; Fischer, Tamás

    2013-01-01

    The eukaryotic chromatin structure is essential in correctly defining transcription units. Impairing this structure can activate cryptic promoters, and lead to the accumulation of aberrant RNA transcripts. Here we discuss critical pathways that are responsible for the repression of cryptic transcription and the maintenance of genome integrity.

  4. Political Repression in U.S. History

    NARCIS (Netherlands)

    van Minnen, C.A.

    2009-01-01

    The authors of the essays in this book amass considerable historical evidence illustrating various forms of political repression and its relationship with democracy in the United States, from the late-eighteenth century to the present. They discuss efforts, made mostly but not only by government age

  5. Repression-Sensitization and Health Behavior.

    Science.gov (United States)

    Gayton, William F.; And Others

    1978-01-01

    Examined relationship between repression-sensitization (R-S) and visits to prison infirmary for males during a one-year period. Main effect for R-S dimension was significant for total number of visits, number of medically justified visits, and number of medically unjustified visits. Sensitizers had significantly more visits than repressors.…

  6. Cancer, acute stress disorder, and repressive coping

    DEFF Research Database (Denmark)

    Pedersen, Anette Fischer; Zachariae, Robert

    2010-01-01

    Reaction Questionnaire, and repressive coping was assessed by a combination of scores from the Marlowe-Crowne Social Desirability Scale, and the Bendig version of the Taylor Manifest Anxiety Scale. Significantly fewer patients classified as "repressors" were diagnosed with ASD compared to patients...

  7. Repression of proinflammatory gene expression by lipid extract of Nostoc commune var sphaeroides Kützing, a blue-green alga, via inhibition of nuclear factor-kappaB in RAW 264.7 macrophages.

    Science.gov (United States)

    Park, Young-Ki; Rasmussen, Heather E; Ehlers, Sarah J; Blobaum, Kara R; Lu, Fan; Schlegal, Vicki L; Carr, Timothy P; Lee, Ji-Young

    2008-02-01

    We investigated whether lipid extract from a blue-green alga, N commune, modulates proinflammatory gene expression in RAW 264.7 macrophages. The cells were incubated with N commune lipid extract (0-100 microg/mL) and subsequently activated by LPS (100 ng/mL). Quantitative real-time PCR analysis showed that mRNA abundance of proinflammatory mediators, including TNF-alpha, COX-2, IL-1beta, IL-6, and iNOS, was significantly reduced by N commune lipid extract in a dose-dependent manner. Secretion of TNF-alpha and IL-1beta into cell culture medium was also significantly decreased by N commune lipid extract. Thin-layer chromatography-densitometry analysis showed that N commune lipid extract contained approximately 15% of fatty acids. To determine whether the inhibition of proinflammatory mediator production by N commune lipid extract is primarily conferred by fatty acids in the lipid extract, macrophages were incubated with 100 microg/mL of N commune lipid extract or 15 microg/mL of a fatty acid mixture, which was formulated to reflect the fatty acid composition of N commune lipid extract. The fatty acid mixture significantly reduced RNA abundance of TNF-alpha and COX-2, but to a lesser extent than did the N commune lipid extract, suggesting the presence of additional bioactive compounds with an antiinflammatory property in the lipid extract. As NF-kappaB is a major regulator for the proinflammatory gene expression, we measured its DNA-binding activity. DNA-binding activity of NF-kappaB was significantly reduced by N commune lipid extract. In conclusion, our study suggests that N commune lipid extract represses the expression of proinflammatory genes in RAW 264.7 macrophages, at least in part, by inhibiting the activation of NF-kappaB pathway.

  8. Wnt-mediated repression via bipartite DNA recognition by TCF in the Drosophila hematopoietic system.

    Science.gov (United States)

    Zhang, Chen U; Blauwkamp, Timothy A; Burby, Peter E; Cadigan, Ken M

    2014-08-01

    The Wnt/β-catenin signaling pathway plays many important roles in animal development, tissue homeostasis and human disease. Transcription factors of the TCF family mediate many Wnt transcriptional responses, promoting signal-dependent activation or repression of target gene expression. The mechanism of this specificity is poorly understood. Previously, we demonstrated that for activated targets in Drosophila, TCF/Pangolin (the fly TCF) recognizes regulatory DNA through two DNA binding domains, with the High Mobility Group (HMG) domain binding HMG sites and the adjacent C-clamp domain binding Helper sites. Here, we report that TCF/Pangolin utilizes a similar bipartite mechanism to recognize and regulate several Wnt-repressed targets, but through HMG and Helper sites whose sequences are distinct from those found in activated targets. The type of HMG and Helper sites is sufficient to direct activation or repression of Wnt regulated cis-regulatory modules, and protease digestion studies suggest that TCF/Pangolin adopts distinct conformations when bound to either HMG-Helper site pair. This repressive mechanism occurs in the fly lymph gland, the larval hematopoietic organ, where Wnt/β-catenin signaling controls prohemocytic differentiation. Our study provides a paradigm for direct repression of target gene expression by Wnt/β-catenin signaling and allosteric regulation of a transcription factor by DNA.

  9. ATF3 represses PPARγ expression and inhibits adipocyte differentiation

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Min-Kyung; Jung, Myeong Ho, E-mail: jung0603@pusan.ac.kr

    2014-11-07

    Highlights: • ATF3 decrease the expression of PPARγ and its target gene in 3T3-L1 adipocytes. • ATF3 represses the promoter activity of PPARγ2 gene. • ATF/CRE (−1537/−1530) is critical for ATF3-mediated downregulation of PPARγ. • ATF3 binds to the promoter region containing the ATF/CRE. • ER stress inhibits adipocyte differentiation through downregulation of PPARγ by ATF3. - Abstract: Activating transcription factor 3 (ATF3) is a stress-adaptive transcription factor that mediates cellular stress response signaling. We previously reported that ATF3 represses CCAAT/enhancer binding protein α (C/EBPα) expression and inhibits 3T3-L1 adipocyte differentiation. In this study, we explored potential role of ATF3 in negatively regulating peroxisome proliferator activated receptor-γ (PPARγ). ATF3 decreased the expression of PPARγ and its target gene in 3T3-L1 adipocytes. ATF3 also repressed the activity of −2.6 Kb promoter of mouse PPARγ2. Overexpression of PPARγ significantly prevented the ATF3-mediated inhibition of 3T3-L1 differentiation. Transfection studies with 5′ deleted-reporters showed that ATF3 repressed the activity of −2037 bp promoter, whereas it did not affect the activity of −1458 bp promoter, suggesting that ATF3 responsive element is located between the −2037 and −1458. An electrophoretic mobility shift assay and chromatin immunoprecipitation assay demonstrated that ATF3 binds to ATF/CRE site (5′-TGACGTTT-3′) between −1537 and −1530. Mutation of the ATF/CRE site abrogated ATF3-mediated transrepression of the PPARγ2 promoter. Treatment with thapsigargin, endoplasmic reticulum (ER) stress inducer, increased ATF3 expression, whereas it decreased PPARγ expression. ATF3 knockdown significantly blocked the thapsigargin-mediated downregulation of PPARγ expression. Furthermore, overexpression of PPARγ prevented inhibition of 3T3-L1 differentiation by thapsigargin. Collectively, these results suggest that ATF3-mediated

  10. Transthyretin represses neovascularization in diabetic retinopathy

    Science.gov (United States)

    Shao, Jun

    2016-01-01

    Purpose The apoptosis of human umbilical vein endothelial cells has been reportedly induced by the protein transthyretin (TTR). In human ocular tissue, TTR is generally considered to be secreted mainly by retinal pigment epithelial cells (hRPECs); however, whether TTR affects the development of neovascularization in diabetic retinopathy (DR) remains unclear. Methods Natural and simulated DR media were used to culture human retinal microvascular endothelial cells (hRECs). Hyperglycemia was simulated by increasing the glucose concentration from 5.5 mM up to 25 mM, while hypoxia was induced with 200 µM CoCl2. To understand the effects of TTR on hRECs, cell proliferation was investigated under natural and DR conditions. Overexpression of TTR, an in vitro wound-healing assay, and a tube formation assay were employed to study the repression of TTR on hRECs. Real-time fluorescence quantitative PCR (qRT-PCR) was used to study the mRNA levels of DR-related genes, such as Tie2, VEGFR1, VEGFR2, Angpt1, and Angpt2. Results The proliferation of hRECs was significantly decreased in the simulated hyperglycemic and hypoxic DR environments. The cells were further repressed by added exogenous or endogenous TTR only under hyperglycemic conditions. The in vitro migration and tube formation processes of the hRECs were inhibited with TTR; furthermore, in the hyperglycemia and hyperglycemia/hypoxia environments, the levels of Tie2 and Angpt1 mRNA were enhanced with exogenous TTR, while those of VEGFR1, VEGFR2, and Angpt1 were repressed. Conclusions In hyperglycemia, the proliferation, migration, and neovascularization of hRECs were significantly inhibited by TTR. The key genes for DR neovascularization, including Tie2, VEGFR1, VEGFR2, Angpt1, and Angpt2, were regulated by TTR. Under DR conditions, TTR significantly represses neovascularization by inhibiting the proliferation, migration and tube formation of hRECs. PMID:27746673

  11. Polycomb repressive complex 1 controls uterine decidualization

    OpenAIRE

    Fenghua Bian; Fei Gao; Kartashov, Andrey V.; Jegga, Anil G; Artem Barski; Das, Sanjoy K.

    2016-01-01

    Uterine stromal cell decidualization is an essential part of the reproductive process. Decidual tissue development requires a highly regulated control of the extracellular tissue remodeling; however the mechanism of this regulation remains unknown. Through systematic expression studies, we detected that Cbx4/2, Rybp, and Ring1B [components of polycomb repressive complex 1 (PRC1)] are predominantly utilized in antimesometrial decidualization with polyploidy. Immunofluorescence analyses reveale...

  12. Plant stem cell maintenance involves direct transcriptional repression of differentiation program.

    Science.gov (United States)

    Yadav, Ram Kishor; Perales, Mariano; Gruel, Jérémy; Ohno, Carolyn; Heisler, Marcus; Girke, Thomas; Jönsson, Henrik; Reddy, G Venugopala

    2013-01-01

    In animal systems, master regulatory transcription factors (TFs) mediate stem cell maintenance through a direct transcriptional repression of differentiation promoting TFs. Whether similar mechanisms operate in plants is not known. In plants, shoot apical meristems serve as reservoirs of stem cells that provide cells for all above ground organs. WUSCHEL, a homeodomain TF produced in cells of the niche, migrates into adjacent cells where it specifies stem cells. Through high-resolution genomic analysis, we show that WUSCHEL represses a large number of genes that are expressed in differentiating cells including a group of differentiation promoting TFs involved in leaf development. We show that WUS directly binds to the regulatory regions of differentiation promoting TFs; KANADI1, KANADI2, ASYMMETRICLEAVES2 and YABBY3 to repress their expression. Predictions from a computational model, supported by live imaging, reveal that WUS-mediated repression prevents premature differentiation of stem cell progenitors, being part of a minimal regulatory network for meristem maintenance. Our work shows that direct transcriptional repression of differentiation promoting TFs is an evolutionarily conserved logic for stem cell regulation.

  13. Repression of RNA polymerase by the archaeo-viral regulator ORF145/RIP

    DEFF Research Database (Denmark)

    Sheppard, Carol; Blombach, Fabian; Belsom, Adam

    2016-01-01

    initiation, as well as elongation. Both host and viral promoters are subjected to ORF145 repression. Thus, ORF145 has the properties of a global transcription repressor and its overexpression is toxic for Sulfolobus. On the basis of its properties, we have re-named ORF145 RNAP Inhibitory Protein (RIP).......Little is known about how archaeal viruses perturb the transcription machinery of their hosts. Here we provide the first example of an archaeo-viral transcription factor that directly targets the host RNA polymerase (RNAP) and efficiently represses its activity. ORF145 from the temperate Acidianus...

  14. Repression of a lithium pump as a consequence of lithium ingestion by manic-depressive subjects.

    Science.gov (United States)

    Meltzer, H L; Kassir, S; Dunner, D L; Fieve, R R

    1977-10-20

    The lithium pump in human erythrocyte membranes, which is responsible for extrusion of lithium against a concentration gradient, has been found to be reversibly repressed during periods of lithium carbonate administration. The pump activity of patients prior to lithium therapy is not different from controls. The onset of repression may require several days to several weeks and occurs at specific individual threshold levels of lithium carbonate dosage. Reactivation of the lithium pump occurs sometime after the dosage is discontinued. We postulate that repression of the lithium pump results from systemically available factors which alter membrane structure, and suggest that is such changes also occur in the central nervous system, they may provide insight into one means by which lithium produces its psychotropic affects.

  15. REST mediates androgen receptor actions on gene repression and predicts early recurrence of prostate cancer

    DEFF Research Database (Denmark)

    Svensson, Charlotte; Ceder, Jens; Iglesias Gato, Diego

    2014-01-01

    The androgen receptor (AR) is a key regulator of prostate tumorgenesis through actions that are not fully understood. We identified the repressor element (RE)-1 silencing transcription factor (REST) as a mediator of AR actions on gene repression. Chromatin immunoprecipitation showed that AR binds...

  16. Role of Splice Variants of Gtf2i, a Transcription Factor Localizing at Postsynaptic Sites, and Its Relation to Neuropsychiatric Diseases

    Science.gov (United States)

    Shirai, Yoshinori; Li, Weidong; Suzuki, Tatsuo

    2017-01-01

    We previously reported that various mRNAs were associated with postsynaptic density (PSD) purified from rat forebrain. Among the thousands of PSD-associated mRNAs, we highlight the biology of the general transcription factor II-I (Gtf2i) mRNA, focusing on the significance of its versatile splicing for targeting its own mRNA into dendrites, regulation of translation, and the effects of Gtf2i expression level as well as its relationship with neuropsychiatric disorders. PMID:28212274

  17. Conscious worst case definition for risk assessment, part I: a knowledge mapping approach for defining most critical risk factors in integrative risk management of chemicals and nanomaterials.

    Science.gov (United States)

    Sørensen, Peter B; Thomsen, Marianne; Assmuth, Timo; Grieger, Khara D; Baun, Anders

    2010-08-15

    This paper helps bridge the gap between scientists and other stakeholders in the areas of human and environmental risk management of chemicals and engineered nanomaterials. This connection is needed due to the evolution of stakeholder awareness and scientific progress related to human and environmental health which involves complex methodological demands on risk management. At the same time, the available scientific knowledge is also becoming more scattered across multiple scientific disciplines. Hence, the understanding of potentially risky situations is increasingly multifaceted, which again challenges risk assessors in terms of giving the 'right' relative priority to the multitude of contributing risk factors. A critical issue is therefore to develop procedures that can identify and evaluate worst case risk conditions which may be input to risk level predictions. Therefore, this paper suggests a conceptual modelling procedure that is able to define appropriate worst case conditions in complex risk management. The result of the analysis is an assembly of system models, denoted the Worst Case Definition (WCD) model, to set up and evaluate the conditions of multi-dimensional risk identification and risk quantification. The model can help optimize risk assessment planning by initial screening level analyses and guiding quantitative assessment in relation to knowledge needs for better decision support concerning environmental and human health protection or risk reduction. The WCD model facilitates the evaluation of fundamental uncertainty using knowledge mapping principles and techniques in a way that can improve a complete uncertainty analysis. Ultimately, the WCD is applicable for describing risk contributing factors in relation to many different types of risk management problems since it transparently and effectively handles assumptions and definitions and allows the integration of different forms of knowledge, thereby supporting the inclusion of multifaceted risk

  18. EAR motif-mediated transcriptional repression in plants: an underlying mechanism for epigenetic regulation of gene expression.

    Science.gov (United States)

    Kagale, Sateesh; Rozwadowski, Kevin

    2011-02-01

    Ethylene-responsive element binding factor-associated Amphiphilic Repression (EAR) motif-mediated transcriptional repression is emerging as one of the principal mechanisms of plant gene regulation. The EAR motif, defined by the consensus sequence patterns of either LxLxL or DLNxxP, is the most predominant form of transcriptional repression motif so far identified in plants. Additionally, this active repression motif is highly conserved in transcriptional regulators known to function as negative regulators in a broad range of developmental and physiological processes across evolutionarily diverse plant species. Recent discoveries of co-repressors interacting with EAR motifs, such as TOPLESS (TPL) and AtSAP18, have begun to unravel the mechanisms of EAR motif-mediated repression. The demonstration of genetic interaction between mutants of TPL and AtHDA19, co-complex formation between TPL-related 1 (TPR1) and AtHDA19, as well as direct physical interaction between AtSAP18 and AtHDA19 support a model where EAR repressors, via recruitment of chromatin remodeling factors, facilitate epigenetic regulation of gene expression. Here, we discuss the biological significance of EAR-mediated gene regulation in the broader context of plant biology and present literature evidence in support of a model for EAR motif-mediated repression via the recruitment and action of chromatin modifiers. Additionally, we discuss the possible influences of phosphorylation and ubiquitination on the function and turnover of EAR repressors.

  19. Activation and repression functions of an SR splicing regulator depend on exonic versus intronic-binding position.

    Science.gov (United States)

    Shen, Manli; Mattox, William

    2012-01-01

    SR proteins and related factors play widespread roles in alternative pre-mRNA splicing and are known to promote splice site recognition through their Arg-Ser-rich effector domains. However, binding of SR regulators to some targets results in repression of splice sites through a distinct mechanism. Here, we investigate how activated and repressed targets of the Drosophila SR regulator Transformer2 elicit its differing effects on splicing. We find that, like activation, repression affects early steps in the recognition of splice sites and spliceosome assembly. Repositioning of regulatory elements reveals that Tra2 complexes that normally repress splicing from intronic positions activate splicing when located in an exon. Protein tethering experiments demonstrate that this position dependence is an intrinsic property of Tra2 and further show that repression and activation are mediated by separate effector domains of this protein. When other Drosophila SR factors (SF2 and Rbp1) that activate splicing from exonic positions were tethered intronically they failed to either activate or repress splicing. Interestingly, both activities of Tra2 favor the exonic identity of the RNA sequences that encompass its binding sites. This suggests a model in which these two opposite functions act in concert to define both the position and extent of alternatively spliced exons.

  20. Bending the rules of transcriptional repression: tightly looped DNA directly represses T7 RNA polymerase.

    Science.gov (United States)

    Lionberger, Troy A; Meyhöfer, Edgar

    2010-08-09

    From supercoiled DNA to the tight loops of DNA formed by some gene repressors, DNA in cells is often highly bent. Despite evidence that transcription by RNA polymerase (RNAP) is affected in systems where DNA is deformed significantly, the mechanistic details underlying the relationship between polymerase function and mechanically stressed DNA remain unclear. Seeking to gain additional insight into the regulatory consequences of highly bent DNA, we hypothesize that tightly looping DNA is alone sufficient to repress transcription. To test this hypothesis, we have developed an assay to quantify transcription elongation by bacteriophage T7 RNAP on small, circular DNA templates approximately 100 bp in size. From these highly bent transcription templates, we observe that the elongation velocity and processivity can be repressed by at least two orders of magnitude. Further, we show that minicircle templates sustaining variable levels of twist yield only moderate differences in repression efficiency. We therefore conclude that the bending mechanics within the minicircle templates dominate the observed repression. Our results support a model in which RNAP function is highly dependent on the bending mechanics of DNA and are suggestive of a direct, regulatory role played by the template itself in regulatory systems where DNA is known to be highly bent. 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  1. BEND3 mediates transcriptional repression and heterochromatin organization.

    Science.gov (United States)

    Khan, Abid; Prasanth, Supriya G

    2015-01-01

    Transcription repression plays a central role in gene regulation. Transcription repressors utilize diverse strategies to mediate transcriptional repression. We have recently demonstrated that BEND3 (BANP, E5R and Nac1 domain) protein represses rDNA transcription by stabilizing a NoRC component. We discuss the role of BEND3 as a global regulator of gene expression and propose a model whereby BEND3 associates with chromatin remodeling complexes to modulate gene expression and heterochromatin organization.

  2. Mechanism of catabolite repression of tryptophanase synthesis in Escherichia coli.

    Science.gov (United States)

    Isaacs, H; Chao, D; Yanofsky, C; Saier, M H

    1994-08-01

    Repression of tryptophanase (tryptophan indole-lyase) by glucose and its non-metabolizable analogue methyl alpha-glucoside has been studied employing a series of isogenic strains of Escherichia coli lacking cyclic AMP phosphodiesterase and altered for two of the proteins of the phosphoenolpyruvate:sugar phosphotransferase system (PTS), Enzyme I and Enzyme IIAGlc. Basal activity of tryptophanase was depressed mildly by inclusion of glucose in the growth medium, but inducible tryptophanase synthesis was subject to strong glucose repression in the parental strain, which exhibited normal PTS enzyme activities. Methyl alpha-glucoside was without effect in this strain. Loss of Enzyme I decreased sensitivity to repression by glucose but enhanced sensitivity to repression by methyl alpha-glucoside. Loss of Enzyme IIAGlc activity largely abolished repression by methyl alpha-glucoside but had a less severe effect on glucose repression. The repressive effects of both sugars were fully reversed by inclusion of cyclic AMP in the growth medium. Tryptophan uptake under the same conditions was inhibited weakly by glucose and more strongly by methyl alpha-glucoside in the parental strain. Inhibition by both sugars was alleviated by partial loss of Enzyme I. Inhibition by methyl alpha-glucoside appeared to be largely due to energy competition and was not responsible for repression of tryptophanase synthesis. Measurement of net production of cyclic AMP as well as intracellular concentrations of cyclic AMP revealed a good correlation with intensity of repression. The results suggest that while basal tryptophanase synthesis is relatively insensitive to catabolite repression, inducible synthesis is subject to strong repression by two distinct mechanisms, one dependent on enzyme IIAGlc of the PTS and the other independent of this protein. Both mechanisms are attributable to depressed rates of cyclic AMP synthesis. No evidence for a cyclic-AMP-independent mechanism of catabolite

  3. ATRX represses alternative lengthening of telomeres.

    Science.gov (United States)

    Napier, Christine E; Huschtscha, Lily I; Harvey, Adam; Bower, Kylie; Noble, Jane R; Hendrickson, Eric A; Reddel, Roger R

    2015-06-30

    The unlimited proliferation of cancer cells requires a mechanism to prevent telomere shortening. Alternative Lengthening of Telomeres (ALT) is an homologous recombination-mediated mechanism of telomere elongation used in tumors, including osteosarcomas, soft tissue sarcoma subtypes, and glial brain tumors. Mutations in the ATRX/DAXX chromatin remodeling complex have been reported in tumors and cell lines that use the ALT mechanism, suggesting that ATRX may be an ALT repressor. We show here that knockout or knockdown of ATRX in mortal cells or immortal telomerase-positive cells is insufficient to activate ALT. Notably, however, in SV40-transformed mortal fibroblasts ATRX loss results in either a significant increase in the proportion of cell lines activating ALT (instead of telomerase) or in a significant decrease in the time prior to ALT activation. These data indicate that loss of ATRX function cooperates with one or more as-yet unidentified genetic or epigenetic alterations to activate ALT. Moreover, transient ATRX expression in ALT-positive/ATRX-negative cells represses ALT activity. These data provide the first direct, functional evidence that ATRX represses ALT.

  4. Somatic sex determination in Caenorhabditis elegans is modulated by SUP-26 repression of tra-2 translation.

    Science.gov (United States)

    Mapes, James; Chen, Jeng-Ting; Yu, Jau-Song; Xue, Ding

    2010-10-19

    Translational repression mediated by RNA-binding proteins or micro RNAs has emerged as a major regulatory mechanism for fine-tuning important biological processes. In Caenorhabditis elegans, translational repression of the key sex-determination gene tra-2 (tra, transformer) is controlled by a 28-nucleotide repeat element, the TRA-2/GLI element (TGE), located in its 3' untranslated region (UTR). Mutations that disrupt TGE or the germline-specific TGE-binding factor GLD-1 increase TRA-2 protein expression and inhibit sperm production in hermaphrodites. Here we report the characterization of the sup-26 gene, which regulates sex determination in the soma and encodes an RNA recognition motif (RRM)-containing protein. We show that SUP-26 regulates the level of the TRA-2 protein through TGE in vivo and binds directly to TGE in vitro through its RRM domain. Interestingly, SUP-26 associates with poly(A)-binding protein 1 (PAB-1) in vivo and may repress tra-2 expression by inhibiting the translation-stimulating activity of PAB-1. Taken together, our results provide further insight into how mRNA-binding factors repress translation and modulate sexual development in different tissues of C. elegans.

  5. SIRT6 represses LINE1 retrotransposons by ribosylating KAP1 but this repression fails with stress and age

    Science.gov (United States)

    Van Meter, Michael; Kashyap, Mehr; Rezazadeh, Sarallah; Geneva, Anthony J.; Morello, Timothy D.; Seluanov, Andrei; Gorbunova, Vera

    2014-01-01

    L1 retrotransposons are an abundant class of transposable elements which pose a threat to genome stability and may play a role in age-related pathologies such as cancer. Recent evidence indicates that L1s become more active in somatic tissues during the course of aging; the mechanisms underlying this phenomenon remain unknown, however. Here we report that the longevity regulating protein, SIRT6, is a powerful repressor of L1 activity. Specifically, SIRT6 binds to the 5′UTR of L1 loci, where it mono-ADP ribosylates the nuclear corepressor protein, KAP1, and facilitates KAP1 interaction with the heterochromatin factor, HP1α, thereby contributing to the packaging of L1 elements into transcriptionally repressive heterochromatin. During the course of aging, and also in response to DNA damage, however, we find that SIRT6 is depleted from L1 loci, allowing for the activation of these previously silenced retroelements. PMID:25247314

  6. SAGA complex components and acetate repression in Aspergillus nidulans.

    Science.gov (United States)

    Georgakopoulos, Paraskevi; Lockington, Robin A; Kelly, Joan M

    2012-11-01

    Alongside the well-established carbon catabolite repression by glucose and other sugars, acetate causes repression in Aspergillus nidulans. Mutations in creA, encoding the transcriptional repressor involved in glucose repression, also affect acetate repression, but mutations in creB or creC, encoding components of a deubiquitination system, do not. To understand the effects of acetate, we used a mutational screen that was similar to screens that uncovered mutations in creA, creB, and creC, except that glucose was replaced by acetate to identify mutations that were affected for repression by acetate but not by glucose. We uncovered mutations in acdX, homologous to the yeast SAGA component gene SPT8, which in growth tests showed derepression for acetate repression but not for glucose repression. We also made mutations in sptC, homologous to the yeast SAGA component gene SPT3, which showed a similar phenotype. We found that acetate repression is complex, and analysis of facA mutations (lacking acetyl CoA synthetase) indicates that acetate metabolism is required for repression of some systems (proline metabolism) but not for others (acetamide metabolism). Although plate tests indicated that acdX- and sptC-null mutations led to derepressed alcohol dehydrogenase activity, reverse-transcription quantitative real-time polymerase chain reaction showed no derepression of alcA or aldA but rather elevated induced levels. Our results indicate that acetate repression is due to repression via CreA together with metabolic changes rather than due to an independent regulatory control mechanism.

  7. MYCN repression of Lifeguard/FAIM2 enhances neuroblastoma aggressiveness

    Science.gov (United States)

    Planells-Ferrer, L; Urresti, J; Soriano, A; Reix, S; Murphy, D M; Ferreres, J C; Borràs, F; Gallego, S; Stallings, R L; Moubarak, R S; Segura, M F; Comella, J X

    2014-01-01

    Neuroblastoma (NBL) is the most common solid tumor in infants and accounts for 15% of all pediatric cancer deaths. Several risk factors predict NBL outcome: age at the time of diagnosis, stage, chromosome alterations and MYCN (V-Myc Avian Myelocytomatosis Viral Oncogene Neuroblastoma-Derived Homolog) amplification, which characterizes the subset of the most aggressive NBLs with an overall survival below 30%. MYCN-amplified tumors develop exceptional chemoresistance and metastatic capacity. These properties have been linked to defects in the apoptotic machinery, either by silencing components of the extrinsic apoptotic pathway (e.g. caspase-8) or by overexpression of antiapoptotic regulators (e.g. Bcl-2, Mcl-1 or FLIP). Very little is known on the implication of death receptors and their antagonists in NBL. In this work, the expression levels of several death receptor antagonists were analyzed in multiple human NBL data sets. We report that Lifeguard (LFG/FAIM2 (Fas apoptosis inhibitory molecule 2)/NMP35) is downregulated in the most aggressive and undifferentiated tumors. Intringuingly, although LFG has been initially characterized as an antiapoptotic protein, we have found a new association with NBL differentiation. Moreover, LFG repression resulted in reduced cell adhesion, increased sphere growth and enhanced migration, thus conferring a higher metastatic capacity to NBL cells. Furthermore, LFG expression was found to be directly repressed by MYCN at the transcriptional level. Our data, which support a new functional role for a hitherto undiscovered MYCN target, provide a new link between MYCN overexpression and increased NBL metastatic properties. PMID:25188511

  8. Nitrogen Catabolite Repression in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Hofman-Bang, H Jacob Peider

    1999-01-01

    In Saccharomyces cerevisiae the expression of all known nitrogen catabolite pathways are regulated by four regulators known as Gln3, Gat1, Da180, and Deh1. This is known as nitrogen catabolite repression (NCR). They bind to motifs in the promoter region to the consensus sequence S' GATAA 3'. Gln3...... and Gat1 act positively on gene expression whereas :Da180 and Deh1 act negatively. Expression of nitrogen catabolite pathway genes known to be regulated by these four regulators are glutamine, glutamate, proline, urea, arginine, GABA, and allantoine. In addition, the expression of the genes encoding...... thereby providing a nitrogen source to the cell.In this review, all known promoter sequences related to expression of nitrogen catabolite pathways are discussed as well as other regulatory proteins. Overview of metabolic pathways and promoters are presented....

  9. Carbon catabolite repression in Thermoanaerobacterium saccharolyticum

    Directory of Open Access Journals (Sweden)

    Tsakraklides Vasiliki

    2012-11-01

    Full Text Available Abstract Background The thermophilic anaerobe Thermoanaerobacterium saccharolyticum is capable of directly fermenting xylan and the biomass-derived sugars glucose, cellobiose, xylose, mannose, galactose and arabinose. It has been metabolically engineered and developed as a biocatalyst for the production of ethanol. Results We report the initial characterization of the carbon catabolite repression system in this organism. We find that sugar metabolism in T. saccharolyticum is regulated by histidine-containing protein HPr. We describe a mutation in HPr, His15Asp, that leads to derepression of less-favored carbon source utilization. Conclusion Co-utilization of sugars can be achieved by mutation of HPr in T. saccharolyticum. Further manipulation of CCR in this organism will be instrumental in achieving complete and rapid conversion of all available sugars to ethanol.

  10. Polycomb complexes act redundantly to repress genomic repeats and genes

    DEFF Research Database (Denmark)

    Leeb, Martin; Pasini, Diego; Novatchkova, Maria

    2010-01-01

    Polycomb complexes establish chromatin modifications for maintaining gene repression and are essential for embryonic development in mice. Here we use pluripotent embryonic stem (ES) cells to demonstrate an unexpected redundancy between Polycomb-repressive complex 1 (PRC1) and PRC2 during the form...

  11. Nuclear receptor CAR represses TNFalpha-induced cell death by interacting with the anti-apoptotic GADD45B.

    Directory of Open Access Journals (Sweden)

    Yukio Yamamoto

    Full Text Available BACKGROUND: Phenobarbital (PB is the most well-known among numerous non-genotoxic carcinogens that cause the development of hepatocellular carcinoma (HCC. PB activates nuclear xenobiotic receptor Constitutive Active/Androstane Receptor (CAR; NR1I3 and this activation is shown to determine PB promotion of HCC in mice. The molecular mechanism of CAR-mediated tumor promotion, however, remains elusive at the present time. Here we have identified Growth Arrest and DNA Damage-inducible 45beta (GADD45B as a novel CAR target, through which CAR represses cell death. METHODOLOGY/PRINCIPAL FINDINGS: PB activation of nuclear xenobiotic receptor CAR is found to induce the Gadd45b gene in mouse liver throughout the development of HCC as well as in liver tumors. Given the known function of GADD45B as a factor that represses Mitogen-activated protein Kinase Kinase 7 - c-Jun N-terminal Kinase (MKK7-JNK pathway-mediated apoptosis, we have now demonstrated that CAR interacts with GADD45B to repress Tumor Necrosis Factor alpha ( TNFalpha-induced JNK1 phosphorylation as well as cell death. Primary hepatocytes, prepared from Car(+/+, Car(-/-, Gadd45b(+/+ and Gadd45b(-/- mice, were treated with TNFalpha and Actinomycin D to induce phosphorylation of JNK1 and cell death. Co-treatment with the CAR activating ligand TCPOBOP (1,4 bis[2-(3,5-dichloropyridyloxy]benzene has resulted in repression of both phosphorylation and cell death in the primary hepatocytes from Car(+/+ but not Car(-/- mice. Repression by TCPOBOP was not observed in those prepared from Gadd45b(-/- mice. In vitro protein-protein interaction and phosphorylation assays have revealed that CAR interacts with MKK7 and represses the MKK7-mediated phosphorylation of JNK1. CONCLUSIONS/SIGNIFICANCE: CAR can form a protein complex with GADD45B, through which CAR represses MKK7-mediated phosphorylation of JNK1. In addition to activating the Gadd45b gene, CAR may repress death of mouse primary hepatocytes by forming

  12. Nuclear receptors in inflammation control: repression by GR and beyond.

    Science.gov (United States)

    Chinenov, Yurii; Gupte, Rebecca; Rogatsky, Inez

    2013-11-05

    Inflammation is a protective response of organisms to pathogens, irritation or injury. Primary inflammatory sensors activate an array of signaling pathways that ultimately converge upon a few transcription factors such as AP1, NFκB and STATs that in turn stimulate expression of inflammatory genes to ultimately eradicate infection and repair the damage. A disturbed balance between activation and inhibition of inflammatory pathways can set the stage for chronic inflammation which is increasingly recognized as a key pathogenic component of autoimmune, metabolic, cardiovascular and neurodegenerative disorders. Nuclear receptors (NRs) are a large family of transcription factors many of which are known for their potent anti-inflammatory actions. Activated by small lipophilic ligands, NRs interact with a wide range of transcription factors, cofactors and chromatin-modifying enzymes, assembling numerous cell- and tissue-specific DNA-protein transcriptional regulatory complexes with diverse activities. Here we discuss established and emerging roles and mechanisms by which NRs and, in particular, the glucocorticoid receptor (GR) repress genes encoding cytokines, chemokines and other pro-inflammatory mediators.

  13. Gfi1 and gfi1b repress rag transcription in plasmacytoid dendritic cells in vitro.

    Directory of Open Access Journals (Sweden)

    Kwan T Chow

    Full Text Available Growth factor independence genes (Gfi1 and Gfi1b repress recombination activating genes (Rag transcription in developing B lymphocytes. Because all blood lineages originate from hematopoietic stem cells (HSCs and different lineage progenitors have been shown to share transcription factor networks prior to cell fate commitment, we hypothesized that GFI family proteins may also play a role in repressing Rag transcription or a global lymphoid transcriptional program in other blood lineages. We tested the level of Rag transcription in various blood cells when Gfi1 and Gfi1b were deleted, and observed an upregulation of Rag expression in plasmacytoid dendritic cells (pDCs. Using microarray analysis, we observed that Gfi1 and Gfi1b do not regulate a lymphoid or pDC-specific transcriptional program. This study establishes a role for Gfi1 and Gfi1b in Rag regulation in a non-B lineage cell type.

  14. Targeted repression of AXIN2 and MYC gene expression using designer TALEs

    Energy Technology Data Exchange (ETDEWEB)

    Rennoll, Sherri A.; Scott, Samantha A.; Yochum, Gregory S., E-mail: gsy3@psu.edu

    2014-04-18

    Highlights: • We designed TALE–SID fusion proteins to target AXIN2 and MYC. • TALE–SIDs bound the chromosomal AXIN2 and MYC genes and repressed their expression. • TALE–SIDs repress β-catenin{sup S45F}-dependent AXIN2 and MYC transcription. - Abstract: Designer TALEs (dTALEs) are chimeric transcription factors that can be engineered to regulate gene expression in mammalian cells. Whether dTALEs can block gene transcription downstream of signal transduction cascades, however, has yet to be fully explored. Here we tested whether dTALEs can be used to target genes whose expression is controlled by Wnt/β-catenin signaling. TALE DNA binding domains were engineered to recognize sequences adjacent to Wnt responsive enhancer elements (WREs) that control expression of axis inhibition protein 2 (AXIN2) and c-MYC (MYC). These custom DNA binding domains were linked to the mSin3A interaction domain (SID) to generate TALE–SID chimeric repressors. The TALE–SIDs repressed luciferase reporter activity, bound their genomic target sites, and repressed AXIN2 and MYC expression in HEK293 cells. We generated a novel HEK293 cell line to determine whether the TALE–SIDs could function downstream of oncogenic Wnt/β-catenin signaling. Treating these cells with doxycycline and tamoxifen stimulates nuclear accumulation of a stabilized form of β-catenin found in a subset of colorectal cancers. The TALE–SIDs repressed AXIN2 and MYC expression in these cells, which suggests that dTALEs could offer an effective therapeutic strategy for the treatment of colorectal cancer.

  15. Plant stem cell maintenance involves direct transcriptional repression of differentiation program

    OpenAIRE

    Yadav, Ram Kishor; Perales, Mariano; Gruel, Jérémy; Ohno, Carolyn; Heisler, Marcus; Girke, Thomas; Jönsson, Henrik; Reddy, G. Venugopala

    2013-01-01

    In animal systems, master regulatory transcription factors (TFs) mediate stem cell maintenance through a direct transcriptional repression of differentiation promoting TFs. Whether similar mechanisms operate in plants is not known. In plants, shoot apical meristems serve as reservoirs of stem cells that provide cells for all above ground organs. WUSCHEL, a homeodomain TF produced in cells of the niche, migrates into adjacent cells where it specifies stem cells. Through high-resolution genomic...

  16. CUTTING THE HEAD OF THE ROARING MONSTER": HOMOSEXUALITY AND REPRESSION IN AFRICA

    OpenAIRE

    Essien, Kwame; Aderinto, Saheed

    2009-01-01

    This paper examines how a proposed conference of gays and lesbians in 2006 in Ghana created tensions and repercussions from the social, cultural, religious and political factors, which worked to repress same-sex discourse in the country. The new wave of homophobic expression that ensued is partly a product of the new globalization and also a manifestation of the clash between what is considered "African" and "un-African" social and sexual behavior. This study shows that the government of Ghan...

  17. A core erythroid transcriptional network is repressed by a master regulator of myelo-lymphoid differentiation

    OpenAIRE

    Wontakal, Sandeep N.; Guo, Xingyi; Smith, Cameron; MacCarthy, Thomas; Emery H Bresnick; Bergman, Aviv; Snyder, Michael P.; Weissman, Sherman M.; Zheng, Deyou; Skoultchi, Arthur I.

    2012-01-01

    Two mechanisms that play important roles in cell fate decisions are control of a “core transcriptional network” and repression of alternative transcriptional programs by antagonizing transcription factors. Whether these two mechanisms operate together is not known. Here we report that GATA-1, SCL, and Klf1 form an erythroid core transcriptional network by co-occupying >300 genes. Importantly, we find that PU.1, a negative regulator of terminal erythroid differentiation, is a highly integrated...

  18. MAF2 Is Regulated by Temperature-Dependent Splicing and Represses Flowering at Low Temperatures in Parallel with FLM.

    Directory of Open Access Journals (Sweden)

    Chiara A Airoldi

    Full Text Available Plants enter their reproductive phase when the environmental conditions are favourable for the successful production of progeny. The transition from vegetative to reproductive phase is influenced by several environmental factors including ambient temperature. In the model plant Arabidopsis thaliana, SHORT VEGETATIVE PHASE (SVP is critical for this pathway; svp mutants cannot modify their flowering time in response to ambient temperature. SVP encodes a MADS-box transcription factor that directly represses genes that promote flowering. SVP binds DNA in complexes with other MADS-box transcription factors, including FLOWERING LOCUS M (FLM, which acts with SVP to repress the floral transition at low temperatures. Small temperature changes post-transcriptionally regulate FLM through temperature-dependent alternative splicing (TD-AS. As ambient temperature increases, the predominant FLM splice isoform shifts to encode a protein incapable of exerting a repressive effect on flowering. Here we characterize a closely related MADS-box transcription factor, MADS AFFECTING FLOWERING2 (MAF2, which has independently evolved TD-AS. At low temperatures the most abundant MAF2 splice variant encodes a protein that interacts with SVP to repress flowering. At increased temperature the relative abundance of splice isoforms shifts in favour of an intron-retaining variant that introduces a premature termination codon. We show that this isoform encodes a protein that cannot interact with SVP or repress flowering. At lower temperatures MAF2 and SVP repress flowering in parallel with FLM and SVP, providing an additional input to sense ambient temperature for the control of flowering.

  19. Perspective: repression of competition and the evolution of cooperation.

    Science.gov (United States)

    Frank, Steven A

    2003-04-01

    Repression of competition within groups joins kin selection as the second major force in the history of life shaping the evolution of cooperation. When opportunities for competition against neighbors are limited within groups, individuals can increase their own success only by enhancing the efficiency and productivity of their group. Thus, characters that repress competition within groups promote cooperation and enhance group success. Leigh first expressed this idea in the context of fair meiosis, in which each chromosome has an equal chance of transmission via gametes. Randomized success means that each part of the genome can increase its own success only by enhancing the total number of progeny and thus increasing the success of the group. Alexander used this insight about repression of competition in fair meiosis to develop his theories for the evolution of human sociality. Alexander argued that human social structures spread when they repress competition within groups and promote successful group-against-group competition. Buss introduced a new example with his suggestion that metazoan success depended on repression of competition between cellular lineages. Maynard Smith synthesized different lines of thought on repression of competition. In this paper, I develop simple mathematical models to illustrate the main processes by which repression of competition evolves. With the concepts made clear, I then explain the history of the idea. I finish by summarizing many new developments in this subject and the most promising lines for future study.

  20. Kinetic profiling of the c-Myc transcriptome and bioinformatic analysis of repressed gene promoters

    Science.gov (United States)

    Yap, Chui-Sun; Peterson, Abigail L; Castellani, Gastone

    2011-01-01

    Mammalian c-Myc is a member of a small family of three related proto-oncogenic transcription factors. c-Myc has an unusually broad array of regulatory functions, which include roles in cell cycle and apoptosis, a variety of metabolic functions, cell differentiation, senescence and stem cell maintenance. c-Myc modulates the expression of a very large number of genes, but the magnitude of the majority of the regulatory effects is only two-fold or less. c-Myc can both activate and repress the promoters of its target genes. Identification of genes directly regulated by c-Myc has been an enduring question in the field. We report here microarray expression profiling of a high resolution time course of c-Myc induction, using fibroblast cells in which c-Myc activity can be modulated from null to physiological. The c-Myc transcriptome data set presented is the largest reported to date with 4,186 differentially regulated genes (1,826 upregulated, 2,360 downregulated, 1% FDR). The gene expression patterns fit well with the known biological functions of c-Myc. We describe several novel findings and present tools for further data mining. Although the mechanisms of transcriptional activation by c-Myc are well understood, how c-Myc represses an even greater number of genes remains incompletely described. One mechanism involves the binding of c-Myc to other, positively acting transcription factors and interfering with their activities. We identified rapid-response genes likely to be direct c-Myc targets and analyzed the promoters of the repressed genes to identify transcription factors that could be targets of c-Myc repression. PMID:21623162

  1. MYC acts via the PTEN tumor suppressor to elicit autoregulation and genome-wide gene repression by activation of the Ezh2 methyltransferase

    Science.gov (United States)

    Kaur, Mandeep; Cole, Michael D.

    2012-01-01

    The control of normal cell growth is a balance between stimulatory and inhibitory signals. MYC is a pleiotropic transcription factor that both activates and represses a broad range of target genes and is indispensable for cell growth. While much is known about gene activation by MYC, there is no established mechanism for the majority of MYC repressed genes. We report that MYC transcriptionally activates the PTEN tumor suppressor in normal cells to inactivate the PI3K pathway, thus suppressing AKT activation. Suppression of AKT enhances the activity of the EZH2 histone methyltransferase, a subunit of the epigenetic repressor Polycomb Repressive Complex 2 (PRC2), while simultaneously stabilizing the protein. MYC mediated enhancement in EZH2 protein level and activity results in local and genome-wide elevation in the repressive H3K27me3 histone modification, leading to widespread gene repression including feedback autoregulation of the MYC gene itself. Depletion of either PTEN or EZH2 and inhibition of the PI3K/AKT pathway leads to gene derepression. Importantly, expression of a phospho-defective EZH2 mutant is sufficient to recapitulate nearly half of all MYC-mediated gene repression. We present a novel epigenetic model for MYC-mediated gene repression and propose that PTEN and MYC exist in homeostatic balance to control normal growth which is disrupted in cancer cells. PMID:23135913

  2. Polycomb repressive complex 2 regulates MiR-200b in retinal endothelial cells: potential relevance in diabetic retinopathy.

    Directory of Open Access Journals (Sweden)

    Michael Anthony Ruiz

    Full Text Available Glucose-induced augmented vascular endothelial growth factor (VEGF production is a key event in diabetic retinopathy. We have previously demonstrated that downregulation of miR-200b increases VEGF, mediating structural and functional changes in the retina in diabetes. However, mechanisms regulating miR-200b in diabetes are not known. Histone methyltransferase complex, Polycomb Repressive Complex 2 (PRC2, has been shown to repress miRNAs in neoplastic process. We hypothesized that, in diabetes, PRC2 represses miR-200b through its histone H3 lysine-27 trimethylation mark. We show that human retinal microvascular endothelial cells exposed to high levels of glucose regulate miR-200b repression through histone methylation and that inhibition of PRC2 increases miR-200b while reducing VEGF. Furthermore, retinal tissue from animal models of diabetes showed increased expression of major PRC2 components, demonstrating in vivo relevance. This research established a repressive relationship between PRC2 and miR-200b, providing evidence of a novel mechanism of miRNA regulation through histone methylation.

  3. Regional repression of a Drosophila POU box gene in the endoderm involves inductive interactions between germ layers.

    Science.gov (United States)

    Affolter, M; Walldorf, U; Kloter, U; Schier, A F; Gehring, W J

    1993-04-01

    An induction process occurring between the mesodermal and the endodermal germ layers has recently been described in the regulation of the Drosophila homeotic gene labial (lab). We report here that proper spatial regulation of the Drosophila POU box gene pdm-1 products also involves interaction between these two germ layers. pdm-1 transcripts are initially present in both the anterior and the posterior endodermal midgut primordia. Upon fusion of the two primordia, transcripts disappear from two regions in the endoderm, a central domain and an anterior domain. The anterior repression domain of pdm-1 is independent of the expression of known homeotic genes and genes encoding secreted signalling molecules in the visceral mesoderm, both for its positioning and its repression. Repression in the central domain requires both the homeotic gene Ultrabithorax (Ubx) and the decapentaplegic (dpp) gene, which encodes a secreted protein. Both of these genes are also required for lab induction. However, the analysis of pdm-1 expression in various mutant backgrounds indicates that the regulation of lab and pdm-1 across germ layers is controlled by different genetic cascades. Our study indicates that dpp is not the signal that dictates central pdm-1 repression across germ layers and suggests that in the same midgut region, different signalling pathways result in the differential activation or repression of potential transcription factors.

  4. Multiple repressive mechanisms in the hippocampus during memory formation.

    Science.gov (United States)

    Cho, Jun; Yu, Nam-Kyung; Choi, Jun-Hyeok; Sim, Su-Eon; Kang, SukJae Joshua; Kwak, Chuljung; Lee, Seung-Woo; Kim, Ji-il; Choi, Dong Il; Kim, V Narry; Kaang, Bong-Kiun

    2015-10-02

    Memory stabilization after learning requires translational and transcriptional regulations in the brain, yet the temporal molecular changes that occur after learning have not been explored at the genomic scale. We used ribosome profiling and RNA sequencing to quantify the translational status and transcript levels in the mouse hippocampus after contextual fear conditioning. We revealed three types of repressive regulations: translational suppression of ribosomal protein-coding genes in the hippocampus, learning-induced early translational repression of specific genes, and late persistent suppression of a subset of genes via inhibition of estrogen receptor 1 (ESR1/ERα) signaling. In behavioral analyses, overexpressing Nrsn1, one of the newly identified genes undergoing rapid translational repression, or activating ESR1 in the hippocampus impaired memory formation. Collectively, this study unveils the yet-unappreciated importance of gene repression mechanisms for memory formation. Copyright © 2015, American Association for the Advancement of Science.

  5. Targeted Transcriptional Repression in Bacteria Using CRISPR Interference (CRISPRi).

    Science.gov (United States)

    Hawkins, John S; Wong, Spencer; Peters, Jason M; Almeida, Ricardo; Qi, Lei S

    2015-01-01

    Clustered regularly interspersed short palindromic repeats (CRISPR) interference (CRISPRi) is a powerful technology for sequence-specifically repressing gene expression in bacterial cells. CRISPRi requires only a single protein and a custom-designed guide RNA for specific gene targeting. In Escherichia coli, CRISPRi repression efficiency is high (~300-fold), and there are no observable off-target effects. The method can be scaled up as a general strategy for the repression of many genes simultaneously using multiple designed guide RNAs. Here we provide a protocol for efficient guide RNA design, cloning, and assay of the CRISPRi system in E. coli. In principle, this protocol can be used to construct CRISPRi systems for gene repression in other species of bacteria.

  6. Polycomb repressive complex PRC1 spatially constrains the mouse embryonic stem cell genome.

    Science.gov (United States)

    Schoenfelder, Stefan; Sugar, Robert; Dimond, Andrew; Javierre, Biola-Maria; Armstrong, Harry; Mifsud, Borbala; Dimitrova, Emilia; Matheson, Louise; Tavares-Cadete, Filipe; Furlan-Magaril, Mayra; Segonds-Pichon, Anne; Jurkowski, Wiktor; Wingett, Steven W; Tabbada, Kristina; Andrews, Simon; Herman, Bram; LeProust, Emily; Osborne, Cameron S; Koseki, Haruhiko; Fraser, Peter; Luscombe, Nicholas M; Elderkin, Sarah

    2015-10-01

    The Polycomb repressive complexes PRC1 and PRC2 maintain embryonic stem cell (ESC) pluripotency by silencing lineage-specifying developmental regulator genes. Emerging evidence suggests that Polycomb complexes act through controlling spatial genome organization. We show that PRC1 functions as a master regulator of mouse ESC genome architecture by organizing genes in three-dimensional interaction networks. The strongest spatial network is composed of the four Hox gene clusters and early developmental transcription factor genes, the majority of which contact poised enhancers. Removal of Polycomb repression leads to disruption of promoter-promoter contacts in the Hox gene network. In contrast, promoter-enhancer contacts are maintained in the absence of Polycomb repression, with accompanying widespread acquisition of active chromatin signatures at network enhancers and pronounced transcriptional upregulation of network genes. Thus, PRC1 physically constrains developmental transcription factor genes and their enhancers in a silenced but poised spatial network. We propose that the selective release of genes from this spatial network underlies cell fate specification during early embryonic development.

  7. The personality construct of hardiness, III: Relationships with repression, innovativeness, authoritarianism, and performance.

    Science.gov (United States)

    Maddi, Salvatore R; Harvey, Richard H; Khoshaba, Deborah M; Lu, John L; Persico, Michele; Brow, Marnie

    2006-04-01

    Previous research has established hardiness as a dispositional factor in preserving and enhancing performance and health despite stressful circumstances. The present four studies continue this construct-validational process by (a) introducing a shortened version of the hardiness measure and (b) testing hypotheses concerning the relationship between hardiness and repressive coping, right-wing authoritarianism, innovative behavior, and billable hours (a measure of consulting effectiveness). Results of these studies suggest the adequate reliability and validity of the Personal Views Survey III-R, which is the shortened, 18-item measure of hardiness. Further, results support the hypothesis that the relationship of hardiness is negative with repressive coping and right-wing authoritarianism and positive with innovative behavior and billable hours. Hardiness also appears unrelated to socially desirable responding.

  8. Repressive coping and alexithymia in idiopathic environmental intolerance

    DEFF Research Database (Denmark)

    Skovbjerg, Sine; Zachariae, Robert; Rasmussen, Alice;

    2010-01-01

    To examine if the non-expression of negative emotions (i.e., repressive coping) and differences in the ability to process and regulate emotions (i.e., alexithymia) is associated with idiopathic environmental intolerance (IEI).......To examine if the non-expression of negative emotions (i.e., repressive coping) and differences in the ability to process and regulate emotions (i.e., alexithymia) is associated with idiopathic environmental intolerance (IEI)....

  9. GATA4 mediates gene repression in the mature mouse small intestine through interactions with friend of GATA (FOG) cofactors

    NARCIS (Netherlands)

    E. Beuling (Eva); T. Bosse (Tjalling); D.J. Kerk (Daniel); C.M. Piaseckyj (Christina); Y. Fujiwara (Yuko); S.G. Katz (Samuel); S.H. Orkin (Stuart); R.J. Grand (Richard); S.D. Krasinski (Stephen)

    2008-01-01

    textabstractGATA4, a transcription factor expressed in the proximal small intestine but not in the distal ileum, maintains proximal-distal distinctions by multiple processes involving gene repression, gene activation, and cell fate determination. Friend of GATA (FOG) is an evolutionarily conserved f

  10. Expression of a 74-kDa nuclear factor 1 (NF1) protein is induced in mouse mammary gland involution. Involution-enhanced occupation of a twin NF1 binding element in the testosterone-repressed prostate message-2/clusterin promoter.

    Science.gov (United States)

    Furlong, E E; Keon, N K; Thornton, F D; Rein, T; Martin, F

    1996-11-22

    Testosterone repressed prostate message-2 (TRPM-2)/clusterin gene expression is rapidly induced in early involution of the mouse mammary gland, after weaning, and in the rat ventral prostate, after castration. A search for involution-enhanced DNaseI footprints in the proximal mouse TRPM-2/clusterin gene promoter led to the identification and characterization (by DNase I footprinting and EMSA) of a twin nuclear factor 1 (NF1) binding element at -356/-309, relative to the proposed transcription start site; nuclear extracts from 2-day involuting mouse mammary gland showed an enhanced footprint over the proximal NF1 element; extracts from involuting prostate showed enhanced occupancy of both NF1 binding elements. Subsequent EMSA and Western analysis led to the detection of a 74-kDa NF1 protein whose expression is triggered in early involution in the mouse mammary gland; such an induced protein is not found in the involuting rat ventral prostate. This protein was not found in lactation where three other NF1 proteins of 114, 68, and 46 kDa were detected. Reiteration of the epithelial cell apoptosis associated with early mammary gland involution, in vitro, in a primary cell culture system, triggered the appearance of the 74-kDa NF1. Overlaying the cells with laminin-rich extracellular matrix suppressed the apoptosis and the expression of the 74-kDa NF1 and, in the presence of lactogenic hormones, initiated milk protein gene expression and the expression of two of the lactation-associated NF1 proteins (68 and 46 kDa). This study, thus, identifies for the first time the occurrence of a switch in expression of different members of the family of NF1 transcription factors as mammary epithelial cells move from the differentiated to the involution/apoptotic state, and it is likely that the involution-specific 74-kDa NF1 accounts for the enhanced NF1 footprint detected on the TRPM-2/clusterin promoter with extracts of mouse mammary gland.

  11. Organic acid mediated repression of sugar utilization in rhizobia.

    Science.gov (United States)

    Iyer, Bhagya; Rajput, Mahendrapal Singh; Jog, Rahul; Joshi, Ekta; Bharwad, Krishna; Rajkumar, Shalini

    2016-11-01

    Rhizobia are a class of symbiotic diazotrophic bacteria which utilize C4 acids in preference to sugars and the sugar utilization is repressed as long as C4 acids are present. This can be manifested as a diauxie when rhizobia are grown in the presence of a sugar and a C4 acid together. Succinate, a C4 acid is known to repress utilization of sugars, sugar alcohols, hydrocarbons, etc by a mechanism termed as Succinate Mediated Catabolite Repression (SMCR). Mechanism of catabolite repression determines the hierarchy of carbon source utilization in bacteria. Though the mechanism of catabolite repression has been well studied in model organisms like E. coli, B. subtilis and Pseudomonas sp., mechanism of SMCR in rhizobia has not been well elucidated. C4 acid uptake is important for effective symbioses while mutation in the sugar transport and utilization genes does not affect symbioses. Deletion of hpr and sma0113 resulted in the partial relief of SMCR of utilization of galactosides like lactose, raffinose and maltose in the presence of succinate. However, no such regulators governing SMCR of glucoside utilization have been identified till date. Though rhizobia can utilize multitude of sugars, high affinity transporters for many sugars are yet to be identified. Identifying high affinity sugar transporters and studying the mechanism of catabolite repression in rhizobia is important to understand the level of regulation of SMCR and the key regulators involved in SMCR.

  12. Critical role of TCF-1 in repression of the IL-17 gene.

    Directory of Open Access Journals (Sweden)

    Jian Ma

    Full Text Available Overwhelming activation of IL-17, a gene involved in inflammation, leads to exaggerated Th17 responses associated with numerous autoimmune conditions, such as experimental autoimmune encephalomyelitis (EAE. Here we show that TCF-1 is a critical factor to repress IL-17 gene locus by chromatin modifications during T cell development. Deletion of TCF-1 resulted in increased IL-17 gene expression both in thymus and peripheral T cells, which led to enhanced Th17 differentiation. As a result, TCF-1(-/- mice were susceptible to Th17-dependent EAE induction. Rag1(-/- mice reconstituted with TCF-1(-/- T cells were also susceptible to EAE, indicating TCF-1 is intrinsically required to repress IL-17. However, expression of wild-type TCF-1 or dominant negative TCF-1 did not interfere with Th17 differentiation in mature T cells. Furthermore, expression of TCF-1 in TCF-1(-/- T cells could not restore Th17 differentiation to wild-type levels, indicating that TCF-1 cannot affect IL-17 production at the mature T cell stage. This is also supported by the normal up-regulation or activation in mature TCF-1(-/- T cells of factors known to regulate Th17 differentiation, including RORγt and Stat3. We observed hyperacetylation together with trimethylation of Lys-4 at the IL-17 locus in TCF-1(-/- thymocytes, two epigenetic modifications indicating an open active state of the gene. Such epigenetic modifications were preserved even when TCF-1(-/- T cells migrated out of thymus. Therefore, TCF-1 mediates an active process to repress IL-17 gene expression via epigenetic modifications during T cell development. This TCF-1-mediated repression of IL-17 is critical for peripheral T cells to generate balanced immune responses.

  13. Auto-phosphorylation Represses Protein Kinase R Activity

    Science.gov (United States)

    Wang, Die; de Weerd, Nicole A.; Willard, Belinda; Polekhina, Galina; Williams, Bryan R. G.; Sadler, Anthony J.

    2017-01-01

    The central role of protein kinases in controlling disease processes has spurred efforts to develop pharmaceutical regulators of their activity. A rational strategy to achieve this end is to determine intrinsic auto-regulatory processes, then selectively target these different states of kinases to repress their activation. Here we investigate auto-regulation of the innate immune effector protein kinase R, which phosphorylates the eukaryotic initiation factor 2α to inhibit global protein translation. We demonstrate that protein kinase R activity is controlled by auto-inhibition via an intra-molecular interaction. Part of this mechanism of control had previously been reported, but was then controverted. We account for the discrepancy and extend our understanding of the auto-inhibitory mechanism by identifying that auto-inhibition is paradoxically instigated by incipient auto-phosphorylation. Phosphor-residues at the amino-terminus instigate an intra-molecular interaction that enlists both of the N-terminal RNA-binding motifs of the protein with separate surfaces of the C-terminal kinase domain, to co-operatively inhibit kinase activation. These findings identify an innovative mechanism to control kinase activity, providing insight for strategies to better regulate kinase activity. PMID:28281686

  14. Auto-phosphorylation Represses Protein Kinase R Activity.

    Science.gov (United States)

    Wang, Die; de Weerd, Nicole A; Willard, Belinda; Polekhina, Galina; Williams, Bryan R G; Sadler, Anthony J

    2017-03-10

    The central role of protein kinases in controlling disease processes has spurred efforts to develop pharmaceutical regulators of their activity. A rational strategy to achieve this end is to determine intrinsic auto-regulatory processes, then selectively target these different states of kinases to repress their activation. Here we investigate auto-regulation of the innate immune effector protein kinase R, which phosphorylates the eukaryotic initiation factor 2α to inhibit global protein translation. We demonstrate that protein kinase R activity is controlled by auto-inhibition via an intra-molecular interaction. Part of this mechanism of control had previously been reported, but was then controverted. We account for the discrepancy and extend our understanding of the auto-inhibitory mechanism by identifying that auto-inhibition is paradoxically instigated by incipient auto-phosphorylation. Phosphor-residues at the amino-terminus instigate an intra-molecular interaction that enlists both of the N-terminal RNA-binding motifs of the protein with separate surfaces of the C-terminal kinase domain, to co-operatively inhibit kinase activation. These findings identify an innovative mechanism to control kinase activity, providing insight for strategies to better regulate kinase activity.

  15. ZBTB7A suppresses melanoma metastasis by transcriptionally repressing MCAM

    Science.gov (United States)

    Liu, Xue-Song; Genet, Matthew D; Haines, Jenna E; Mehanna, Elie K; Wu, Shaowei; Chen, Hung-I Harry; Chen, Yidong; Qureshi, Abrar A; Han, Jiali; Chen, Xiang; Fisher, David E; Pandolfi, Pier Paolo; Yuan, Zhi-Min

    2015-01-01

    The excessive metastatic propensity of melanoma makes it the most deadly form of skin cancer, yet the underlying mechanism of metastasis remains elusive. Here, mining of cancer genome datasets discovered a frequent loss of chromosome 19p13.3 and associated down-regulation of the zinc finger transcription factor ZBTB7A in metastatic melanoma. Functional assessment of ZBTB7A-regulated genes identified MCAM, which encodes an adhesion protein key to melanoma metastasis. Using an integrated approach, it is demonstrated that ZBTB7A directly binds to the promoter and transcriptionally represses the expression of MCAM, establishing ZBTB7A as a bona fide transcriptional repressor of MCAM. Consistently, down-regulation of ZBTB7A results in marked upregulation of MCAM and enhanced melanoma cell invasion and metastasis. An inverse correlation of ZBTB7A and MCAM expression in association with melanoma metastasis is further validated with data from analysis of human melanoma specimens. Implications Together these results uncover a previously unrecognized role of ZBTB7A in negative regulation of melanoma metastasis and have important clinical implications. PMID:25995384

  16. DELLA proteins interact with FLC to repress flowering transition

    Institute of Scientific and Technical Information of China (English)

    Hongwei Guo

    2016-01-01

    Flowering is a highly orchestrated and extremely critical process in a plant’s life cycle. Previous study has demonstrated that SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1) and FLOWERING LOCUS T (FT) integrate the gibberellic acid (GA) signaling pathway and vernalization pathway in regulating flowering time, but detailed molecular mechanisms remain largely unclear. In GA signaling pathway, DELLA proteins are a group of master transcriptional regulators, while in vernalization pathway FLOWERING LOCUS C (FLC) is a core transcriptional repressor that down-regulates the expression of SOC1 and FT. Here, we report that DELLA proteins interact with FLC in vitro and in vivo, and the LHRI domains of DELLAs and the C-terminus of MADS domain of FLC are required for these interactions. Phenotypic and gene expression analysis showed that mutation of FLC reduces while over-expression of FLC enhances the GA response in the flowering process. Further, DELLA-FLC interactions promote the repression ability of FLC on its target genes. In summary, these findings report that the interaction between MADS box transcription factor FLC and GRAS domain regulator DELLAs may integrate various signaling inputs in flowering time control, and shed new light on the regulatory mechanism both for FLC and DELLAs in regulating gene expression.

  17. Coordinated regulation of transcriptional repression by the RBP2 H3K4 demethylase and Polycomb-Repressive Complex 2

    DEFF Research Database (Denmark)

    Pasini, Diego; Hansen, Klaus H; Christensen, Jesper;

    2008-01-01

    Polycomb group (PcG) proteins regulate important cellular processes such as embryogenesis, cell proliferation, and stem cell self-renewal through the transcriptional repression of genes determining cell fate decisions. The Polycomb-Repressive Complex 2 (PRC2) is highly conserved during evolution......, and its intrinsic histone H3 Lys 27 (K27) trimethylation (me3) activity is essential for PcG-mediated transcriptional repression. Here, we show a functional interplay between the PRC2 complex and the H3K4me3 demethylase Rbp2 (Jarid1a) in mouse embryonic stem (ES) cells. By genome-wide location analysis we...... found that Rbp2 is associated with a large number of PcG target genes in mouse ES cells. We show that the PRC2 complex recruits Rbp2 to its target genes, and that this interaction is required for PRC2-mediated repressive activity during ES cell differentiation. Taken together, these results demonstrate...

  18. De-repression of RaRF-mediated RAR repression by adenovirus E1A in the nucleolus.

    Science.gov (United States)

    Um, Soo-Jong; Youn, Hye Sook; Kim, Eun-Joo

    2014-02-21

    Transcriptional activity of the retinoic acid receptor (RAR) is regulated by diverse binding partners, including classical corepressors and coactivators, in response to its ligand retinoic acid (RA). Recently, we identified a novel corepressor of RAR called the retinoic acid resistance factor (RaRF) (manuscript submitted). Here, we report how adenovirus E1A stimulates RAR activity by associating with RaRF. Based on immunoprecipitation (IP) assays, E1A interacts with RaRF through the conserved region 2 (CR2), which is also responsible for pRb binding. The first coiled-coil domain of RaRF was sufficient for this interaction. An in vitro glutathione-S-transferase (GST) pull-down assay was used to confirm the direct interaction between E1A and RaRF. Further fluorescence microscopy indicated that E1A and RaRF were located in the nucleoplasm and nucleolus, respectively. However, RaRF overexpression promoted nucleolar translocation of E1A from the nucleoplasm. Both the RA-dependent interaction of RAR with RaRF and RAR translocation to the nucleolus were disrupted by E1A. RaRF-mediated RAR repression was impaired by wild-type E1A, but not by the RaRF binding-defective E1A mutant. Taken together, our data suggest that E1A is sequestered to the nucleolus by RaRF through a specific interaction, thereby leaving RAR in the nucleoplasm for transcriptional activation.

  19. Generation of a glucose de-repressed mutant of Trichoderma reesei using disparity mutagenesis.

    Science.gov (United States)

    Iwakuma, Hidekazu; Koyama, Yoshiyuki; Miyachi, Ayako; Nasukawa, Masashi; Matsumoto, Hitoshi; Yano, Shuntaro; Ogihara, Jun; Kasumi, Takafumi

    2016-01-01

    We obtained a novel glucose de-repressed mutant of Trichoderma reesei using disparity mutagenesis. A plasmid containing DNA polymerase δ lacking proofreading activity, and AMAI, an autonomously replicating sequence was introduced into T. reesei ATCC66589. The rate of mutation evaluated with 5-fluoroorotic acid resistance was approximately 30-fold higher than that obtained by UV irradiation. The transformants harboring incompetent DNA polymerase δ were then selected on 2-deoxyglucose agar plates with hygromycin B. The pNP-lactoside hydrolyzing activities of mutants were 2 to 5-fold higher than the parent in liquid medium containing glucose. Notably, the amino acid sequence of cre1, a key gene involved in glucose repression, was identical in the mutant and parent strains, and further, the cre1 expression levels was not abolished in the mutant. Taken together, these results demonstrate that the strains of T. reesei generated by disparity mutagenesis are glucose de-repressed variants that contain mutations in yet-unidentified factors other than cre1.

  20. Repression of hla by rot is dependent on sae in Staphylococcus aureus.

    Science.gov (United States)

    Li, Dongmei; Cheung, Ambrose

    2008-03-01

    The regulatory locus sae is a two-component system in Staphylococcus aureus that regulates many important virulence factors, including alpha-toxin (encoded by hla) at the transcriptional level. The SarA homologs Rot and SarT were previously shown to be repressors of hla in selected S. aureus backgrounds. To delineate the interaction of rot and sae and the contribution of sarT to hla expression, an assortment of rot and sae isogenic single mutants, a rot sae double mutant, and a rot sae sarT markerless triple mutant were constructed from wild-type strain COL. Using Northern blot analysis and transcriptional reporter gene green fluorescent protein, fusion, and phenotypic assays, we found that the repression of hla by rot is dependent on sae. A rot sae sarT triple mutant was not able to rescue the hla defect of the rot sae double mutant. Among the three sae promoters, the distal sae P3 promoter is the strongest in vitro. Interestingly, the sae P3 promoter activities correlate with hla expression in rot, rot sae, and rot sae sarT mutants of COL. Transcriptional study has also shown that rot repressed sae, especially at the sae P3 promoter. Collectively, our data implicated the importance of sae in the rot-mediated repression of hla in S. aureus.

  1. RNAi mediates post-transcriptional repression of gene expression in fission yeast Schizosaccharomyces pombe

    Energy Technology Data Exchange (ETDEWEB)

    Smialowska, Agata, E-mail: smialowskaa@gmail.com [Center for Biosciences, Department of Biosciences and Nutrition, Karolinska Institute, Huddinge 141-83 (Sweden); School of Life Sciences, Södertörn Högskola, Huddinge 141-89 (Sweden); Djupedal, Ingela; Wang, Jingwen [Center for Biosciences, Department of Biosciences and Nutrition, Karolinska Institute, Huddinge 141-83 (Sweden); Kylsten, Per [School of Life Sciences, Södertörn Högskola, Huddinge 141-89 (Sweden); Swoboda, Peter [Center for Biosciences, Department of Biosciences and Nutrition, Karolinska Institute, Huddinge 141-83 (Sweden); Ekwall, Karl, E-mail: Karl.Ekwall@ki.se [Center for Biosciences, Department of Biosciences and Nutrition, Karolinska Institute, Huddinge 141-83 (Sweden); School of Life Sciences, Södertörn Högskola, Huddinge 141-89 (Sweden)

    2014-02-07

    Highlights: • Protein coding genes accumulate anti-sense sRNAs in fission yeast S. pombe. • RNAi represses protein-coding genes in S. pombe. • RNAi-mediated gene repression is post-transcriptional. - Abstract: RNA interference (RNAi) is a gene silencing mechanism conserved from fungi to mammals. Small interfering RNAs are products and mediators of the RNAi pathway and act as specificity factors in recruiting effector complexes. The Schizosaccharomyces pombe genome encodes one of each of the core RNAi proteins, Dicer, Argonaute and RNA-dependent RNA polymerase (dcr1, ago1, rdp1). Even though the function of RNAi in heterochromatin assembly in S. pombe is established, its role in controlling gene expression is elusive. Here, we report the identification of small RNAs mapped anti-sense to protein coding genes in fission yeast. We demonstrate that these genes are up-regulated at the protein level in RNAi mutants, while their mRNA levels are not significantly changed. We show that the repression by RNAi is not a result of heterochromatin formation. Thus, we conclude that RNAi is involved in post-transcriptional gene silencing in S. pombe.

  2. Insomnia symptoms and repressive coping in a sample of older Black and White women

    Directory of Open Access Journals (Sweden)

    Pierre-Louis Jessy

    2007-01-01

    Full Text Available Abstract Background This study examined whether ethnic differences in insomnia symptoms are mediated by differences in repressive coping styles. Methods A total of 1274 women (average age = 59.36 ± 6.53 years participated in the study; 28% were White and 72% were Black. Older women in Brooklyn, NY were recruited using a stratified, cluster-sampling technique. Trained staff conducted face-to-face interviews lasting 1.5 hours acquiring sociodemographic data, health characteristics, and risk factors. A sleep questionnaire was administered and individual repressive coping styles were assessed. Fisher's exact test and Spearman and Pearson analyses were used to analyze the data. Results The rate of insomnia symptoms was greater among White women [74% vs. 46%; χ2 = 87.67, p 1,1272 = 304.75, p s = -0.43, p s = -0.18, p Conclusion Relationships between ethnicity and insomnia symptoms are jointly dependent on the degree of repressive coping, suggesting that Black women may be reporting fewer insomnia symptoms because of a greater ability to route negative emotions from consciousness. It may be that Blacks cope with sleep problems within a positive self-regulatory framework, which allows them to deal more effectively with sleep-interfering psychological processes to stressful life events and to curtail dysfunctional sleep-interpreting processes.

  3. Photoperiodic control of the floral transition through a distinct polycomb repressive complex.

    Science.gov (United States)

    Wang, Yizhong; Gu, Xiaofeng; Yuan, Wenya; Schmitz, Robert J; He, Yuehui

    2014-03-31

    Polycomb group (PcG) complexes such as PRC1 mediate transcriptional repression. Here, we show that the plant-specific EMBRYONIC FLOWER1 (EMF1), LIKE HETEROCHROMATIN PROTEIN1, and a histone H3 lysine-4 demethylase form a distinct PcG complex, termed EMF1c, that plays PRC1-like roles and is crucial for regulation of the florigen gene FLOWERING LOCUS T (FT) in Arabidopsis. Long-day photoperiods promote FT expression activation in leaf veins specifically at dusk through the photoperiod pathway to induce Arabidopsis flowering. We found that before dusk and at night, a vascular EMF1c directly represses FT expression to prevent photoperiod-independent flowering, whereas at dusk EMF1 binding to FT chromatin is disrupted by the photoperiod pathway, leading to proper FT activation. Furthermore, a MADS-domain transcription factor and potent floral repressor binds EMF1 to repress FT expression. Our study reveals that the vascular EMF1c integrates inputs from several flowering-regulatory pathways to synchronize flowering time to environmental cues.

  4. Investigating the Effects of Financial Repression on Private Investment in Agriculture Sector

    Directory of Open Access Journals (Sweden)

    Abdolmajid Jalaee

    2014-09-01

    Full Text Available One of the present phenomena that virtually explain weaknesses in financial systems of different countries is financial repression. Financial repression encompasses the different interferences of governments in financial markets through determining the ceiling interest on bank deposits, high rates of legal reserves, and the government’s interference in distribution of bank credits,which prevents the efficient performance of financial market for better allocating resources and funds. On the other hand, investment in agricultural sector enjoys a significant importance due to the growth of production and employment in this sector and rooting for the same notions in other economic sectors. Regarding the fact that the subject matter of the current paper is of utmost importance, it tries to investigate the impacts of financial repression on investments in agricultural sector. In order to realize this objective, measures such as the size of the government in economy, the measure for financial intermediation of banks, and the ratio of savings to GDP (Gross Domestic Product were utilized as the factors for financial repression. The regression results of ARDL showed that the effects from the measures of government size in economy and financial intermediation of banks had a negative and significant impact on private investment in agricultural sector. This means that the bigger the size of government in economy the less the willingness of the private sector for investing in agriculture. Moreover, regarding the fact that the majority of banks in Iran are governmental, the measure for financial intermediation of banks had a negative and significant impact on private investment of agricultural sector.

  5. CRISPR Technology for Genome Activation and Repression in Mammalian Cells.

    Science.gov (United States)

    Du, Dan; Qi, Lei S

    2016-01-04

    Targeted modulation of transcription is necessary for understanding complex gene networks and has great potential for medical and industrial applications. CRISPR is emerging as a powerful system for targeted genome activation and repression, in addition to its use in genome editing. This protocol describes how to design, construct, and experimentally validate the function of sequence-specific single guide RNAs (sgRNAs) for sequence-specific repression (CRISPRi) or activation (CRISPRa) of transcription in mammalian cells. In this technology, the CRISPR-associated protein Cas9 is catalytically deactivated (dCas9) to provide a general platform for RNA-guided DNA targeting of any locus in the genome. Fusion of dCas9 to effector domains with distinct regulatory functions enables stable and efficient transcriptional repression or activation in mammalian cells. Delivery of multiple sgRNAs further enables activation or repression of multiple genes. By using scaffold RNAs (scRNAs), different effectors can be recruited to different genes for simultaneous activation of some and repression of others. The CRISPRi and CRISPRa methods provide powerful tools for sequence-specific control of gene expression on a genome-wide scale to aid understanding gene functions and for engineering genetic regulatory systems.

  6. Percept-genetic signs of repression in histrionic personality disorder.

    Science.gov (United States)

    Rubino, I A; Saya, A; Pezzarossa, B

    1992-04-01

    Several types of perceptual distortions of two anxiety-arousing visual stimuli are coded as repression in the Defense Mechanism Test, a tachistoscopic, percept-genetic technique. Given the well-established correspondence between hysteria and repression, the study included a clinical validation of these variants of repression against the diagnosis of histrionic personality disorder. 41 subjects with evidence of this disorder on the Millon Clinical Multiaxial Inventory-II were compared with 41 nonhistrionic controls. Significantly more histrionics were coded for the type of repression in which the threatening figure is transformed into a harmless object (code 1:42), while animal- and statue-repressions, when combined (codes 1:1 and 1:2), were significantly more characteristic of the nonhistrionic group. As an unpredicted finding, significantly more histrionic subjects employed defensive strategies, currently coded as reaction formations (code 4:). Histrionic subjects without concomitant compulsive features were coded more frequently for introaggression (code 6:) compared both with nonhistrionic controls and with histrionic-compulsive subjects. The findings are discussed within the context of the available percept-genetic literature. It is suggested that the Defense Mechanism Test may be further employed to objectify and investigate the defense mechanisms of the DSM-III-R disorders.

  7. Ethical issues in the search for repressed memories.

    Science.gov (United States)

    Merskey, H

    1996-01-01

    Currently, concepts of repression and dissociation are in flux. It has been pointed out that there is no scientific evidence for the occurrence of repression and that the whole notion is anecdotal. Dissociation, which is offered as an alternative to repression, cannot logically be held to operate without a motive force, as Freud argued, or a weakness of the organism, as Janet proposed. The concepts have been applied particularly to the idea that early childhood experience could be repressed but recovered many years later. This claim is at variance with established knowledge concerning human memory. Practices of subtle and overt suggestion, employed in recovered-memory treatments, give rise to a false-memory syndrome in which individuals, who have undergone various levels of suggestion, accuse their parents and others of childhood sexual abuse. The common phenomenon of childhood sexual abuse is contaminated by many cases that may be regarded on strong grounds as being false and have been retracted in more than 1,000 instances. Repressed-memory (RM) treatment is also at variance with traditional psychotherapy, which does not encourage confrontation on the basis of uncorroborated information; moreover, many cases of RM therapy seem to result in deterioration. Unlike traditional psychotherapy, some RM practitioners strongly encourage patients to hate individuals in their family circle. The consequences of these developments, the need for informed consent, and the development of legislative initiatives to challenge RM therapy are noted. The impact of these therapies and proposed legislation upon regular psychotherapy and psychiatry is outlined.

  8. Repression of cardiac hypertrophy by KLF15: underlying mechanisms and therapeutic implications.

    Directory of Open Access Journals (Sweden)

    Joost J Leenders

    Full Text Available The Kruppel-like factor (KLF family of transcription factors regulates diverse cell biological processes including proliferation, differentiation, survival and growth. Previous studies have shown that KLF15 inhibits cardiac hypertrophy by repressing the activity of pivotal cardiac transcription factors such as GATA4, MEF2 and myocardin. We set out this study to characterize the interaction of KLF15 with putative other transcription factors. We first show that KLF15 interacts with myocardin-related transcription factors (MRTFs and strongly represses the transcriptional activity of MRTF-A and MRTF-B. Second, we identified a region within the C-terminal zinc fingers of KLF15 that contains the nuclear localization signal. Third, we investigated whether overexpression of KLF15 in the heart would have therapeutic potential. Using recombinant adeno-associated viruses (rAAV we have overexpressed KLF15 specifically in the mouse heart and provide the first evidence that elevation of cardiac KLF15 levels prevents the development of cardiac hypertrophy in a model of Angiotensin II induced hypertrophy.

  9. PPARα Promotes Cancer Cell Glut1 Transcription Repression.

    Science.gov (United States)

    You, Mengli; Jin, Jianhua; Liu, Qian; Xu, QingGang; Shi, Juanjuan; Hou, Yongzhong

    2017-06-01

    Abundant nutrient availability including glucose and amino acids plays an important role in maintaining cancer cell energetic and biosynthetic pathways. As a nuclear receptor, peroxisome-proliferator-activated receptor α (PPARα) regulates inflammation and cancer progression, however, it is still unclear the interaction of PPARα with the cancer cell glucose metabolism. Here we found that PPARα reduced Glut1 (Glucose transporter 1) protein and gene levels in HCT-116, SW480, HeLa, and MCF-7 cancer cell lines. In contrast, silenced PPARα reversed this event. Further analysis shows that PPARα directly targeted the consensus PPRE motif of Glut1 promoter region resulting in Glut1 transcription repression. PPARα-mediated Glut1 transcription repression led to decreased influx of glucose in cancer cells. These findings revealed a novel mechanism of PPARα-mediated cancer cell Glut1 transcription repression. J. Cell. Biochem. 118: 1556-1562, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  10. Suppression and repression: A theoretical discussion illustrated by a movie

    Directory of Open Access Journals (Sweden)

    Maria Lucia de Souza Campos Paiva

    2012-02-01

    Full Text Available The first translations of Freud's work into Portuguese have presented problems because they were not translated from the German language. More than a hundred years after the beginning of Psychoanalysis, there are still many discussions on Freud's metapsychology and a considerable difficulty in obtaining a consensus on the translation of some concepts. This paper refers back to Freud's concepts of primal repression, repression and suppression. In order to discuss such concepts, we have made use of a film, co-produced by Germans and Argentineans, which is named "The Song in me" (Das Lied in mir, released to the public in 2011 and directed by Florian Micoud Cossen. Through this motion picture, the following of Freud's concepts are analyzed, and the differentiation between them is discussed: suppression and repression, as well as the importance of their precise translation.

  11. Political Repressions in USSR (Against Speculations, Perversion and Mystifications)

    OpenAIRE

    2012-01-01

    In the article the great numbers of political repressions, which were exaggerated by authors: R.A. Medvedev, A.I. Solzhenitsyn, O.G. Shatunovskoy, A.V. Antonov-Ovseenko in 80-90s are criticized. The author characterizes figures given in tens and even in hundreds of millions of victims as a statistical charlatanism.After checking up the KGB archives, and documents of division responsible for NKVD-MVD special settlements, the author spills the light on real numbers of political repressions in U...

  12. Chromatin Repressive Complexes in Stem Cells, Development, and Cancer

    DEFF Research Database (Denmark)

    Laugesen, Anne; Helin, Kristian

    2014-01-01

    of the polycomb repressive complexes, PRC1 and PRC2, and the HDAC1- and HDAC2-containing complexes, NuRD, Sin3, and CoREST, in stem cells, development, and cancer, as well as the ongoing efforts to develop therapies targeting these complexes in human cancer. Furthermore, we discuss the role of repressive......The chromatin environment is essential for the correct specification and preservation of cell identity through modulation and maintenance of transcription patterns. Many chromatin regulators are required for development, stem cell maintenance, and differentiation. Here, we review the roles...... complexes in modulating thresholds for gene activation and their importance for specification and maintenance of cell fate....

  13. Nitrogen catabolite repression of asparaginase II in Saccharomyces cerevisiae.

    OpenAIRE

    Dunlop, P C; Meyer, G M; Roon, R J

    1980-01-01

    The biosynthesis of asparaginase II in Saccharomyces cerevisiae is subject to strong catabolite repression by a variety of nitrogen compounds. In the present study, asparaginase II synthesis was examined in a wild-type yeast strain and in strains carrying gdhA, gdhCR, or gdhCS mutations. The following effects were observed: (i) In the wild-type strain, the biosynthesis of asparaginase II was strongly repressed when either 10 mM ammonium sulfate or various amino acids (10 mM) served as the sou...

  14. Extremadura: Behind the material traces of Franco’s repression

    OpenAIRE

    Muñoz Encinar, Laura; Chaves Palacios, Julián

    2014-01-01

    After the failed coup d’état of July 17th, 1936 and after the start of the Spanish Civil War that followed it, rebels carried out a repressive strategy based on the execution of thousands of people as a key tool of social control. The socialization of fear and terror through humiliation, killing and disappearance would become the main strategy employed throughout the war and the post-war period. In this context, perpetrators would exercise repressive practices on victims and their bodies. As ...

  15. TrgI, toluene repressed gene I, a novel gene involved in toluene-tolerance in Pseudomonas putida S12

    NARCIS (Netherlands)

    Volkers, R.J.M.; Ballerstedt, H.; Ruijssenaars, H.; Bont, J.A.M. de; Winde, J.H. de; Wery, J.

    2009-01-01

    Pseudomonas putida S12 is well known for its remarkable solvent tolerance. Transcriptomics analysis of this bacterium grown in toluene-containing chemostats revealed the differential expression of 253 genes. As expected, the genes encoding one of the major solvent tolerance mechanisms, the solvent e

  16. TrgI, toluene repressed gene I, a novel gene involved in toluene-tolerance in Pseudomonas putida S12

    NARCIS (Netherlands)

    Volkers, R.J.M.; Ballerstedt, H.; Ruijssenaars, H.; Bont, J.A.M. de; Winde, J.H. de; Wery, J.

    2009-01-01

    Pseudomonas putida S12 is well known for its remarkable solvent tolerance. Transcriptomics analysis of this bacterium grown in toluene-containing chemostats revealed the differential expression of 253 genes. As expected, the genes encoding one of the major solvent tolerance mechanisms, the solvent e

  17. TrgI, toluene repressed gene I, a novel gene involved in toluene-tolerance in Pseudomonas putida S12

    NARCIS (Netherlands)

    Volkers, R.J.M.; Ballerstedt, H.; Ruijssenaars, H.; De Bont, J.A.M.; De Winde, J.H.; Wery, J.

    2008-01-01

    Pseudomonas putida S12 is well known for its remarkable solvent tolerance. Transcriptomics analysis of this bacterium grown in toluene-containing chemostats revealed the differential expression of 253 genes. As expected, the genes encoding one of the major solvent tolerance mechanisms, the solvent e

  18. SUMO modification of Stra13 is required for repression of cyclin D1 expression and cellular growth arrest.

    Directory of Open Access Journals (Sweden)

    Yaju Wang

    Full Text Available Stra13, a basic helix-loop-helix (bHLH transcription factor is involved in myriad biological functions including cellular growth arrest, differentiation and senescence. However, the mechanisms by which its transcriptional activity and function are regulated remain unclear. In this study, we provide evidence that post-translational modification of Stra13 by Small Ubiquitin-like Modifier (SUMO dramatically potentiates its ability to transcriptionally repress cyclin D1 and mediate G(1 cell cycle arrest in fibroblast cells. Mutation of SUMO acceptor lysines 159 and 279 located in the C-terminal repression domain has no impact on nuclear localization; however, it abrogates association with the co-repressor histone deacetylase 1 (HDAC1, attenuates repression of cyclin D1, and prevents Stra13-mediated growth suppression. HDAC1, which promotes cellular proliferation and cell cycle progression, antagonizes Stra13 sumoylation-dependent growth arrest. Our results uncover an unidentified regulatory axis between Stra13 and HDAC1 in progression through the G(1/S phase of the cell cycle, and provide new mechanistic insights into regulation of Stra13-mediated transcriptional repression by sumoylation.

  19. Expression of bvg-repressed genes in Bordetella pertussis is controlled by RisA through a novel c-di-GMP signaling pathway

    Science.gov (United States)

    The BvgAS two component system of Bordetella pertussis controls virulence factor expression. In addition, BvgAS controls expression of the bvg-repressed genes through the action of the repressor, BvgR. The transcription factor RisA is inhibited by BvgR, and when BvgR is not expressed RisA induces th...

  20. Financial repression, money growth, and seignorage: The Polish experience

    NARCIS (Netherlands)

    Aarle, B. van; Budina, N.

    1997-01-01

    Financial Repression, Money Growth and Seignorage: The Polish Experience. — A small analytical framework is developed to analyze the relation between reserve requirements, base money growth and seignorage revenues. From the analysis, the authors can derive of steady-state seignorage revenues as a

  1. Financial repression, money growth, and seignorage: The Polish experience

    NARCIS (Netherlands)

    Aarle, B. van; Budina, N.

    1997-01-01

    Financial Repression, Money Growth and Seignorage: The Polish Experience. — A small analytical framework is developed to analyze the relation between reserve requirements, base money growth and seignorage revenues. From the analysis, the authors can derive of steady-state seignorage revenues as a fu

  2. Financial repression, money growth, and seignorage: The Polish experience

    NARCIS (Netherlands)

    Aarle, B. van; Budina, N.

    1997-01-01

    Financial Repression, Money Growth and Seignorage: The Polish Experience. — A small analytical framework is developed to analyze the relation between reserve requirements, base money growth and seignorage revenues. From the analysis, the authors can derive of steady-state seignorage revenues as a fu

  3. Intellectual Performance as a Function of Repression and Menstrual Cycle.

    Science.gov (United States)

    Englander-Golden, Paula; And Others

    Performance on complex (Space Relations and Verbal Reasoning) and simple (Digit Symbol) tests was investigated as a function of Byrne's Repression-Sensitization (RS) dimension, phase of menstrual cycle and premenstrual-menstrual (PM) symptomatology in a group of females not taking oral contraceptives. Two control groups, consisting of males and…

  4. Onset of carbon catabolite repression in Aspergillus nidulans

    NARCIS (Netherlands)

    Flipphi, M.; Vondervoort, van de P.J.I.; Ruijter, G.J.G.; Visser, J.; Arst Jr., H.N.; Felenbok, B.

    2003-01-01

    The role of hexose phosphorylating enzymes in the signaling of carbon catabolite repression was investigated in the filamentous fungus Aspergillus nidulans. A D-fructose non-utilizing, hexokinase-deficient (hxkA1, formerly designated frA1) strain was utilized to obtain new mutants lacking either glu

  5. YY1 restrained cell senescence through repressing the transcription of p16.

    Science.gov (United States)

    Wang, Xiuli; Feng, Yunpeng; Xu, Liang; Chen, Yuli; Zhang, Yu; Su, Dongmei; Ren, Guoling; Lu, Jun; Huang, Baiqu

    2008-10-01

    The transcription factor YY1 has been implicated to play a role in cell growth control. In this report, we demonstrate that YY1 was able to suppress NCI-H460 cell senescence through regulating the expression of p16(INK4a), a cyclin-dependent kinase inhibitor. We also show that YY1 participated in the repression of p16(INK4a) expression in 293T cells through an epigenetic mechanism involving histone acetylation modification. Specifically, HDAC3 and HDAC4 inhibited the p16(INK4a) promoter activity. The chromatin immunoprecipitation (ChIP) assays verified that HDAC3 and HDAC4 were recruited to p16(INK4a) promoter by YY1. Moreover, co-immunoprecipitation assays revealed that these three protein factors formed a complex. Furthermore, knockdown of these factors induced cell enlargement and flattened morphology and significantly increased the SA-beta-gal activity, a biochemical marker of cell senescence. Overall, data from this study suggest that YY1, HDAC3 and HDAC4 restrained cell senescence by repressing p16(INK4a) expression through an epigenetic modification of histones.

  6. The doublesex splicing enhancer components Tra2 and Rbp1 also repress splicing through an intronic silencer.

    Science.gov (United States)

    Qi, Junlin; Su, Shihuang; Mattox, William

    2007-01-01

    The activation of sex-specific alternative splice sites in the Drosophila melanogaster doublesex and fruitless pre-mRNAs has been well studied and depends on the serine-arginine-rich (SR) splicing factors Tra, Tra2, and Rbp1. Little is known, however, about how SR factors negatively regulate splice sites in other RNAs. Here we examine how Tra2 blocks splicing of the M1 intron from its own transcript. We identify an intronic splicing silencer (ISS) adjacent to the M1 branch point that is sufficient to confer Tra2-dependent repression on another RNA. The ISS was found to function independently of its position within the intron, arguing against the idea that bound repressors function by simply interfering with branch point accessibility to general splicing factors. Conserved subelements of the silencer include five short repeated sequences that are required for Tra2 binding but differ from repeated binding sites found in Tra2-dependent splicing enhancers. The ISS also contains a consensus binding site for Rbp1, and this protein was found to facilitate repression of M1 splicing both in vitro and in Drosophila larvae. In contrast to the cooperative binding of SR proteins observed on the doublesex splicing enhancer, we found that Rbp1 and Tra2 bind to the ISS independently through distinct sequences. Our results suggest that functionally synergistic interactions of these SR factors can cause either splicing activation or repression.

  7. A WUSCHEL-Independent Stem Cell Specification Pathway Is Repressed by PHB, PHV and CNA in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Chunghee Lee

    Full Text Available The homeostatic maintenance of stem cells that carry out continuous organogenesis at the shoot meristem is crucial for plant development. Key known factors act to signal between the stem cells and an underlying group of cells thought to act as the stem cell niche. In Arabidopsis thaliana the homeodomain transcription factor WUSCHEL (WUS is essential for stem cell initiation and maintenance at shoot and flower meristems. Recent data suggest that the WUS protein may move from the niche cells directly into the stem cells to maintain stem cell identity. Here we provide evidence for a second, previously unknown, pathway for stem cell specification at shoot and flower meristems that bypasses the requirement for WUS. We demonstrate that this novel stem cell specification pathway is normally repressed by the activity of the HD-zip III transcription factors PHABULOSA (PHB, PHAVOLUTA (PHV and CORONA (CNA. When de-repressed, this second stem cell pathway leads to an accumulation of stem cells and an enlargement of the stem cell niche. When de-repressed in a wus mutant background, this second stem cell pathway leads to functional meristems with largely normal cell layering and meristem morphology, activation of WUS cis regulatory elements, and extensive, but not indeterminate, organogenesis. Thus, WUS is largely dispensable for stem cell specification and meristem function, suggesting a set of key stem cell specification factors, competitively regulated by WUS and PHB/PHV/CNA, remain unidentified.

  8. pipetas usadas para I. A.

    Directory of Open Access Journals (Sweden)

    J. Castañeda

    2004-01-01

    Full Text Available La vagina y cerviz de las cerdas son estimuladas físicamente durante la inseminación. Este contacto puede afectar características reproductivas tales como el transporte espermático y el proceso de ovulación. En el presente trabajo se evaluaron desde el punto de vista económico y reproductivo, tres tipos de pipetas utilizadas para I. A. de cerdas de diferente material y forma. Se utilizaron 120 animales multíparos asignados de acuerdo a su orden de entrada al celo, en forma sucesiva a uno de tres grupos experimentales: 1 I. A. mediante pipeta reusable de hule tipo Melrose ( Medata, 2 I. A. con pipeta desechable de punta plástica en espiral y 3 I. A. con pipeta desechable con punta de poliestireno redonda (Medi chimica. No se encontró diferencia (P>0.05 entre los porcentajes de gestación, parición y promedio de lechones nacidos vivos por parto, en el tiempo de aplicación del semen, ni en el volumen del mismo, arrojado por las cerdas en los 10 min. posteriores a la I. A. Los valores promedio fueron de: 91.7%, 86.7%, 10.4 ± 2.8, 7.8 ± 2.6 min. y 10.4 ± 11.3 ml, respectivamente. El análisis de regresión, no mostró significancia en cuanto a paridad en ninguna de las variables estudiadas (P>0.05. Se concluye que las pipetas evaluadas no difieren en su efecto sobre el desarrollo reproductivo de la piara. Sin embargo, la pipeta reusable tipo Melrose ofrece ventaja económica bajo las condiciones del presente estudio

  9. Diverse mechanisms of post-transcriptional repression by the small RNA regulator of glucose-phosphate stress.

    Science.gov (United States)

    Bobrovskyy, Maksym; Vanderpool, Carin K

    2016-01-01

    The Escherichia coli small RNA SgrS controls a metabolic stress response that occurs upon accumulation of certain glycolytic intermediates. SgrS base pairs with and represses translation of ptsG and manXYZ mRNAs, which encode sugar transporters, and activates translation of yigL mRNA, encoding a sugar phosphatase. This study defines four new genes as direct targets of E. coli SgrS. These new targets, asd, adiY, folE and purR, encode transcription factors or enzymes of diverse metabolic pathways, including aspartate semialdehyde dehydrogenase, arginine decarboxylase gene activator, GTP cyclohydrolase I and a repressor of purine biosynthesis, respectively. SgrS represses translation of each of the four target mRNAs via distinct mechanisms. SgrS binding sites overlapping the Shine-Dalgarno sequences of adiY and folE mRNAs suggest that SgrS pairing with these targets directly occludes ribosome binding and prevents translation initiation. SgrS binding within the purR coding sequence recruits the RNA chaperone Hfq to directly repress purR translation. Two separate SgrS binding sites were found on asd mRNA, and both are required for full translational repression. Ectopic overexpression of asd, adiY and folE is specifically detrimental to cells experiencing glucose-phosphate stress, suggesting that SgrS-dependent repression of the metabolic functions encoded by these targets promotes recovery from glucose-phosphate stress.

  10. Acute TNF-induced repression of cell identity genes is mediated by NFκB-directed redistribution of cofactors from super-enhancers.

    Science.gov (United States)

    Schmidt, Søren Fisker; Larsen, Bjørk Ditlev; Loft, Anne; Nielsen, Ronni; Madsen, Jesper Grud Skat; Mandrup, Susanne

    2015-09-01

    The proinflammatory cytokine tumor necrosis factor (TNF) plays a central role in low-grade adipose tissue inflammation and development of insulin resistance during obesity. In this context, nuclear factor κ-light-chain-enhancer of activated B cells (NFκB) is directly involved and required for the acute activation of the inflammatory gene program. Here, we show that the major transactivating subunit of NFκB, v-rel avian reticuloendotheliosis viral oncogene homolog A (RELA), is also required for acute TNF-induced suppression of adipocyte genes. Notably, this repression does not involve RELA binding to the associated enhancers but rather loss of cofactors and enhancer RNA (eRNA) selectively from high-occupancy sites within super-enhancers. Based on these data, we have developed models that, with high accuracy, predict which enhancers and genes are repressed by TNF in adipocytes. We show that these models are applicable to other cell types where TNF represses genes associated with super-enhancers in a highly cell-type-specific manner. Our results propose a novel paradigm for NFκB-mediated repression, whereby NFκB selectively redistributes cofactors from high-occupancy enhancers, thereby specifically repressing super-enhancer-associated cell identity genes.

  11. The interplay of StyR and IHF regulates substrate-dependent induction and carbon catabolite repression of styrene catabolism genes in Pseudomonas fluorescens ST

    Directory of Open Access Journals (Sweden)

    Leoni Livia

    2008-06-01

    promoter conformation would determine a fine modulation of the promoter activity. Since StyR and IHF protein levels do not vary in the different conditions, the key-factor regulating PstyA catabolite repression is likely the kinase activity of the StyR-cognate sensor protein StyS.

  12. ChREBP Mediates Glucose Repression of Peroxisome Proliferator-activated Receptor {alpha} Expression in Pancreatic {beta}-Cells

    DEFF Research Database (Denmark)

    Boergesen, Michael; Poulsen, Lars la Cour; Schmidt, Søren Fisker;

    2011-01-01

    Chronic exposure to elevated levels of glucose and fatty acids leads to dysfunction of pancreatic β-cells by mechanisms that are only partly understood. The transcription factor peroxisome proliferator-activated receptor α (PPARα) is an important regulator of genes involved in fatty acid metaboli...... of glucose repression of PPARα gene expression in pancreatic β-cells, suggesting that ChREBP may be important for glucose suppression of the fatty acid oxidation capacity of β-cells....

  13. Cell type-specific translational repression of Cyclin B during meiosis in males.

    Science.gov (United States)

    Baker, Catherine Craig; Gim, Byung Soo; Fuller, Margaret T

    2015-10-01

    The unique cell cycle dynamics of meiosis are controlled by layers of regulation imposed on core mitotic cell cycle machinery components by the program of germ cell development. Although the mechanisms that regulate Cdk1/Cyclin B activity in meiosis in oocytes have been well studied, little is known about the trans-acting factors responsible for developmental control of these factors in male gametogenesis. During meiotic prophase in Drosophila males, transcript for the core cell cycle protein Cyclin B1 (CycB) is expressed in spermatocytes, but the protein does not accumulate in spermatocytes until just before the meiotic divisions. Here, we show that two interacting proteins, Rbp4 and Fest, expressed at the onset of spermatocyte differentiation under control of the developmental program of male gametogenesis, function to direct cell type- and stage-specific repression of translation of the core G2/M cell cycle component cycB during the specialized cell cycle of male meiosis. Binding of Fest to Rbp4 requires a 31-amino acid region within Rbp4. Rbp4 and Fest are required for translational repression of cycB in immature spermatocytes, with Rbp4 binding sequences in a cell type-specific shortened form of the cycB 3' UTR. Finally, we show that Fest is required for proper execution of meiosis I. © 2015. Published by The Company of Biologists Ltd.

  14. Foxk proteins repress the initiation of starvation-induced atrophy and autophagy programs.

    Science.gov (United States)

    Bowman, Christopher John; Ayer, Donald E; Dynlacht, Brian David

    2014-12-01

    Autophagy is the primary catabolic process triggered in response to starvation. Although autophagic regulation within the cytosolic compartment is well established, it is becoming clear that nuclear events also regulate the induction or repression of autophagy. Nevertheless, a thorough understanding of the mechanisms by which sequence-specific transcription factors modulate expression of genes required for autophagy is lacking. Here, we identify Foxk proteins (Foxk1 and Foxk2) as transcriptional repressors of autophagy in muscle cells and fibroblasts. Interestingly, Foxk1/2 serve to counter-balance another forkhead transcription factor, Foxo3, which induces an overlapping set of autophagic and atrophic targets in muscle. Foxk1/2 specifically recruits Sin3A-HDAC complexes to restrict acetylation of histone H4 and expression of critical autophagy genes. Remarkably, mTOR promotes the transcriptional activity of Foxk1 by facilitating nuclear entry to specifically limit basal levels of autophagy in nutrient-rich conditions. Our study highlights an ancient, conserved mechanism whereby nutritional status is interpreted by mTOR to restrict autophagy by repressing essential autophagy genes through Foxk-Sin3-mediated transcriptional control.

  15. PRDM16 represses the type I interferon response in adipocytes to promote mitochondrial and thermogenic programing.

    Science.gov (United States)

    Kissig, Megan; Ishibashi, Jeff; Harms, Matthew J; Lim, Hee-Woong; Stine, Rachel R; Won, Kyoung-Jae; Seale, Patrick

    2017-06-01

    Brown adipose has the potential to counteract obesity, and thus, identifying signaling pathways that regulate the activity of this tissue is of great clinical interest. PRDM16 is a transcription factor that activates brown fat-specific genes while repressing white fat and muscle-specific genes in adipocytes. Whether PRDM16 also controls other gene programs to regulate adipocyte function was unclear. Here, we identify a novel role for PRDM16 in suppressing type I interferon (IFN)-stimulated genes (ISGs), including Stat1, in adipocytes in vitro and in vivo Ectopic activation of type I IFN signaling in brown adipocytes induces mitochondrial dysfunction and reduces uncoupling protein 1 (UCP1) expression. Prdm16-deficient adipose displays an exaggerated response to type I IFN, including higher STAT1 levels and reduced mitochondrial gene expression. Mechanistically, PRDM16 represses ISGs through binding to promoter regions of these genes and blocking the activating function of IFN regulatory factor 1 (IRF1). Together, these data indicate that PRDM16 diminishes responsiveness to type I IFN in adipose cells to promote thermogenic and mitochondrial function. © 2017 The Authors.

  16. SUMOylation regulates the transcriptional repression activity of FOG-2 and its association with GATA-4.

    Directory of Open Access Journals (Sweden)

    José Perdomo

    Full Text Available Friend of GATA 2 (FOG-2, a co-factor of several GATA transcription factors (GATA-4, -5 and 6, is a critical regulator of coronary vessel formation and heart morphogenesis. Here we demonstrate that FOG-2 is SUMOylated and that this modification modulates its transcriptional activity. FOG-2 SUMOylation occurs at four lysine residues (K324, 471, 915, 955 [corrected]. Three of these residues are part of the characteristic SUMO consensus site (ψKXE, while K955 is found in the less frequent TKXE motif. Absence of SUMOylation did not affect FOG-2's nuclear localization. However, mutation of the FOG-2 SUMOylation sites, or de-SUMOylation, with SENP-1 or SENP-8 resulted in stronger transcriptional repression activity in both heterologous cells and cardiomyocytes. Conversely, increased FOG-2 SUMOylation by overexpression of SUMO-1 or expression of a SUMO-1-FOG-2 fusion protein rendered FOG-2 incapable of repressing GATA-4-mediated activation of the B-type natriuretic peptide (BNP promoter. Moreover, we demonstrate both increased interaction between a FOG-2 SUMO mutant and GATA-4 and enhanced SUMOylation of wild-type FOG-2 by co-expression of GATA-4. These data suggest a new dynamics in which GATA-4 may alter the activity of FOG-2 by influencing its SUMOylation status.

  17. PROBLEM OF CRIMINAL REPRESSION, APPLIED OUTSIDE OF CRIMINAL LIABILITY

    Directory of Open Access Journals (Sweden)

    Vitaly Stepashin

    2017-01-01

    Full Text Available УДК 343.2A new institute of repressive measures applied outside the criminal liability in criminal law (including as a condition for exemption from criminal liability is forming now in Russian legislation. The author concludes that the provisions of the criminal law on monetary compensation and a court fine should be deleted because of the following reasons. 1 By their nature, and monetary compensation and a court fine, not being a formal punishment (and, therefore, a form of realization of criminal responsibility is a monetary penalty, i.e., penalty-punishment. Moreover, the rules of court fine destination identical rules of criminal sentencing. 2 Quantitatively court fine may exceed the minimum limits of criminal punish-ment in the form of fines. The dimensions of monetary compensation in the order of hours. Pt. 2, Art. 76.1 of the Criminal Code and at all close to the maximum values of fine-punishment. 3 Exemption from criminal liability requires states to refrain from prosecuting the person alleged to have committed a crime, which means that the nonuse of criminal repression. Regulatory standards analyzed, on the other hand, require mandatory use of repression, ie, virtually no exemption from criminal liability does not occur at all. 4 The use of a quasi-penalty in the form of monetary compensation and court fines are not an exemption from criminal responsibility, but on the contrary, the use of criminal repression (of responsibility, and in a simplified manner. 5 Contrary to the requirements of the Constitution and the Criminal Code of criminal repression is applied to persons whose guilt has not been established in the commission of a crime. Thus, in criminal law introduced a presumption of guilt. 6 Customization repression (in fact – of criminal responsibility in the application of the judicial penalty is substantially limited, and the application of monetary compensation is excluded at all, contrary to the requirement that the rough

  18. Political Repressions in USSR (Against Speculations, Perversion and Mystifications

    Directory of Open Access Journals (Sweden)

    Viktor N. Zemskov

    2012-12-01

    Full Text Available In the article the great numbers of political repressions, which were exaggerated by authors: R.A. Medvedev, A.I. Solzhenitsyn, O.G. Shatunovskoy, A.V. Antonov-Ovseenko in 80-90s are criticized. The author characterizes figures given in tens and even in hundreds of millions of victims as a statistical charlatanism.After checking up the KGB archives, and documents of division responsible for NKVD-MVD special settlements, the author spills the light on real numbers of political repressions in USSR. In his view, the total number of political victims does not exceed 2, 6 million people. This number implies over 800 thousand of death sentenced for political reasons, around 600 thousand political prisoners who died in labor camps, and about 1, 2 million people died in exile (including ‘Kulak Exile’ and during transportation (deported ethnic groups and others.

  19. An Updated GA Signaling 'Relief of Repression' Regulatory Model

    Institute of Scientific and Technical Information of China (English)

    Xiu-Hua Gao; Sen-Lin Xiao; Qin-Fang Yao; Yu-Juan Wang; Xiang-Dong Fu

    2011-01-01

    Gibberellic acid (GA)regulates many aspects of plant growth and development. The DELLA proteins act to restrain plant growth, and GA relieves this repression by promoting their degradation via the 26S proteasome pathway.The elucidation of the crystalline structure of the GA soluble receptor GID1 protein represents an important breakthrough for understanding the way in which GA is perceived and how it induces the destabilization of the DELLA proteins. Recent advances have revealed that the DELLA proteins are involved in protein-protein interactions within various environmental and hormone signaling pathways. In this review, we highlight our current understanding of the 'relief of repression" model that aims to explain the role of GA and the function of the DELLA proteins, incorporating the many aspects of cross-talk shown to exist in the control of plant development and the response to stress.

  20. Repressive coping and alexithymia in idiopathic environmental intolerance

    Science.gov (United States)

    Zachariae, Robert; Rasmussen, Alice; Johansen, Jeanne Duus; Elberling, Jesper

    2010-01-01

    Objective To examine if the non-expression of negative emotions (i.e., repressive coping) and differences in the ability to process and regulate emotions (i.e., alexithymia) is associated with idiopathic environmental intolerance (IEI). Methods The study included participants who had previously participated in a general population-based study and reported symptoms of environmental intolerance (n = 787) and patients with IEI (n = 237). The participants completed questionnaires assessing IEI, namely, a measure of repressive coping combining scores on the Marlowe–Crowne Social Desirability Scale (MCSDS) and the Taylor Manifest Anxiety Scale (TMAS), the Toronto Alexithymia Scale (TAS-20), and a negative affectivity scale (NAS). Multiple, hierarchical linear regression analyses were conducted using IEI variables as the dependent variables. Results The TMAS and MCSDS scores were independently associated with the IEI variables, but there was no evidence of a role of the repressive coping construct. While the total alexithymia score was unrelated to IEI, the TAS-20 subscale of difficulties identifying feelings (DIF) was independently associated with symptoms attributed to IEI. Negative affectivity was a strong independent predictor of the IEI variables and a mediator of the association between DIF and IEI. Conclusion Our results provide no evidence for a role of repressive coping in IEI, and our hypothesis of an association with alexithymia was only partly supported. In contrast, strong associations between IEI and negative emotional reactions, defensiveness and difficulties identifying feelings were found, suggesting a need for exploring the influence of these emotional reactions in IEI. PMID:21432559

  1. Repression and reactivation of lithium efflux from erythrocytes.

    Science.gov (United States)

    Goodnick, P J; Meltzer, H L; Dunner, D L; Fieve, R R

    1979-10-01

    Efflux of lithium from human erythrocytes was studied in patients before, during, and after discontinuation of administration of lithium carbonate. Onset of lithium-induced repression of efflux took approximately 10 days and was significantly shorter in patients who had had lithium therapy previously. Reactivation took a longer period of time--approximately 2 week--and was found to be related to duration of lithium therapy. Theoretical pathways of lithium flow through membranes are discussed.

  2. Repressive effects of resveratrol on androgen receptor transcriptional activity.

    Directory of Open Access Journals (Sweden)

    Wen-feng Shi

    Full Text Available BACKGROUND: The chemopreventive effects of resveratrol (RSV on prostate cancer have been well established; the androgen receptor (AR plays pivotal roles in prostatic tumorigenesis. However, the exact underlying molecular mechanisms about the effects of RSV on AR have not been fully elucidated. A model system is needed to determine whether and how RSV represses AR transcriptional activity. METHODOLOGY: The AR cDNA was first cloned into the retroviral vector pOZ-N and then integrated into the genome of AR-negative HeLa cells to generate the AR(+ cells. The constitutively expressed AR was characterized by monitoring hormone-stimulated nuclear translocation, DNA binding, and transcriptional activation, with the AR(- cells serving as controls. AR(+ cells were treated with RSV, and both AR protein levels and AR transcriptional activity were measured simultaneously. Chromatin immunoprecipitation (ChIP assays were used to detect the effects of RSV on the recruitment of AR to its cognate element (ARE. RESULTS: AR in the AR (+ stable cell line functions in a manner similar to that of endogenously expressed AR. Using this model system we clearly demonstrated that RSV represses AR transcriptional activity independently of any effects on AR protein levels. However, neither the hormone-mediated nucleus translocation nor the AR/ARE interaction was affected by RSV treatment. CONCLUSION: We demonstrated unambiguously that RSV regulates AR target gene expression, at least in part, by repressing AR transcriptional activity. Repressive effects of RSV on AR activity result from mechanisms other than the affects of AR nuclear translocation or DNA binding.

  3. Epoxide-Mediated CifR Repression of cif Gene Expression Utilizes Two Binding Sites in Pseudomonas aeruginosa

    OpenAIRE

    Ballok, Alicia E.; Bahl, Christopher D.; Dolben, Emily L.; Lindsay, Allia K.; St. Laurent, Jessica D.; Hogan, Deborah A.; Madden, Dean R.; O'Toole, George A.

    2012-01-01

    Pseudomonas aeruginosa secretes an epoxide hydrolase virulence factor that reduces the apical membrane expression of ABC transporters such as the cystic fibrosis transmembrane conductance regulator (CFTR). This virulence factor, named CFTR inhibitory factor (Cif), is regulated by a TetR-family, epoxide-responsive repressor known as CifR via direct binding and repression. We identified two sites of CifR binding in the intergenic space between cifR and morB, the first gene in the operon contain...

  4. Repression and activation by multiprotein complexes that alter chromatin structure.

    Science.gov (United States)

    Kingston, R E; Bunker, C A; Imbalzano, A N

    1996-04-15

    Recent studies have provided strong evidence that macromolecular complexes are used in the cell to remodel chromatin structure during activation and to create an inaccessible structure during repression, Although there is not yet any rigorous demonstration that modification of chromatin structure plays a direct, causal role in either activation or repression, there is sufficient smoke to indicate the presence of a blazing inferno nearby. It is clear that complexes that remodel chromatin are tractable in vitro; hopefully this will allow the establishment of systems that provide a direct analysis of the role that remodeling might play in activation. These studies indicate that establishment of functional systems to corroborate the elegant genetic studies on repression might also be tractable. As the mechanistic effects of these complexes are sorted out, it will become important to understand how the complexes are regulated. In many of the instances discussed above, the genes whose products make up these complexes were identified in genetic screens for effects on developmental processes. This implies a regulation of the activity of these complexes in response to developmental cues and further implies that the work to fully understand these complexes will occupy a generation of scientists.

  5. Transcriptional Repression of Catalase in Mouse Skin Tumor Progression

    Directory of Open Access Journals (Sweden)

    Kevin A. Kwei

    2004-09-01

    Full Text Available Previous studies in our laboratory have shown that the elevation of reactive oxygen species levels and the repression of the antioxidant enzyme, catalase, played a critical role in the in vitro progression of benign papilloma cells to malignant carcinoma cells. Catalase message, protein levels, and activity levels were found to be downregulated in the malignantly progressed cells. The goal of this study is to further characterize the repression of catalase in malignant progression of mouse skin tumors. To validate the in vitro observations, we examined catalase expression in tumor samples generated by the multistep chemical carcinogenesis protocol. Higher levels of catalase mRNA and protein were observed in benign papillomas versus malignant carcinomas. Nuclear run-on analysis showed that catalase repression in the cultured malignant cells was transcription-dependent. Results from luciferase reporter assays indicated that malignant cells have lower catalase promoter activities than benign papilloma cells, in part through the Wilm's tumor suppressor 1 (WT1 binding site within the proximal promoter region. The WTi protein levels were found to be inversely correlated with the observed catalase promoter activities, with higher levels observed in the malignant cells versus the benign cells. These results led us to conclude that WTi is acting as a transcription repressor in catalase gene regulation during tumor progression.

  6. Trans-inactivation: Repression in a wrong place.

    Science.gov (United States)

    Shatskikh, Aleksei S; Abramov, Yuriy A; Lavrov, Sergey A

    2016-08-19

    Trans-inactivation is the repression of genes on a normal chromosome under the influence of a rearranged homologous chromosome demonstrating the position effect variegation (PEV). This phenomenon was studied in detail on the example of brown(Dominant) allele causing the repression of wild-type brown gene on the opposite chromosome. We have investigated another trans-inactivation-inducing chromosome rearrangement, In(2)A4 inversion. In both cases, brown(Dominant) and In(2)A4, the repression seems to be the result of dragging of the euchromatic region of the normal chromosome into the heterochromatic environment. It was found that cis-inactivation (classical PEV) and trans-inactivation show different patterns of distribution along the chromosome and respond differently to PEV modifying genes. It appears that the causative mechanism of trans-inactivation is de novo heterochromatin assembly on euchromatic sequences dragged into the heterochromatic nuclear compartment. Trans-inactivation turns out to be the result of a combination of heterochromatin-induced position effect and the somatic interphase chromosome pairing that is widespread in Diptera.

  7. Nitric oxide participates in plant flowering repression by ascorbate

    Science.gov (United States)

    Senthil Kumar, Rajendran; Shen, Chin-Hui; Wu, Pei-Yin; Suresh Kumar, Subbiah; Hua, Moda Sang; Yeh, Kai-Wun

    2016-01-01

    In Oncidium, redox homeostasis involved in flowering is mainly due to ascorbic acid (AsA). Here, we discovered that Oncidium floral repression is caused by an increase in AsA-mediated NO levels, which is directed by the enzymatic activities of nitrate reductase (NaR) and nitrite reducatase (NiR). Through Solexa transcriptomic analysis of two libraries, ‘pseudobulb with inflorescent bud’ (PIB) and ‘pseudobulb with axillary bud’ (PAB), we identified differentially expressed genes related to NO metabolism. Subsequently, we showed a significant reduction of NaR enzymatic activities and NO levels during bolting and blooming stage, suggesting that NO controlled the phase transition and flowering process. Applying AsA to Oncidium PLB (protocorm-like bodies) significantly elevated the NO content and enzyme activities. Application of sodium nitroprusside (-NO donor) on Arabidopsis vtc1 mutant caused late flowering and expression level of flowering-associated genes (CO, FT and LFY) were reduced, suggesting NO signaling is vital for flowering repression. Conversely, the flowering time of noa1, an Arabidopsis NO-deficient mutant, was not altered after treatment with L-galacturonate, a precursor of AsA, suggesting AsA is required for NO-biosynthesis involved in the NO-mediated flowering-repression pathway. Altogether, Oncidium bolting is tightly regulated by AsA-mediated NO level and downregulation of transcriptional levels of NO metabolism genes. PMID:27731387

  8. Revisiting the Master-Signifier, or, Mandela and Repression.

    Science.gov (United States)

    Hook, Derek; Vanheule, Stijn

    2015-01-01

    The concept of the master-signifier has been subject to a variety of applications in Lacanian forms of political discourse theory and ideology critique. While there is much to be commended in literature of this sort, it often neglects salient issues pertaining to the role of master signifiers in the clinical domain of (individual) psychical economy. The popularity of the concept of the master (or "empty") signifier in political discourse analysis has thus proved a double-edged sword. On the one hand it demonstrates how crucial psychical processes are performed via the operations of the signifier, extending thus the Lacanian thesis that identification is the outcome of linguistic and symbolic as opposed to merely psychological processes. On the other, the use of the master signifier concept within the political realm to track discursive formations tends to distance the term from the dynamics of the unconscious and operation of repression. Accordingly, this paper revisits the master signifier concept, and does so within the socio-political domain, yet while paying particular attention to the functioning of unconscious processes of fantasy and repression. More specifically, it investigates how Nelson Mandela operates as a master signifier in contemporary South Africa, as a vital means of knitting together diverse elements of post-apartheid society, enabling the fantasy of the post-apartheid nation, and holding at bay a whole series of repressed and negated undercurrents.

  9. Revisiting the Master-Signifier, or, Mandela and Repression

    Science.gov (United States)

    Hook, Derek; Vanheule, Stijn

    2016-01-01

    The concept of the master-signifier has been subject to a variety of applications in Lacanian forms of political discourse theory and ideology critique. While there is much to be commended in literature of this sort, it often neglects salient issues pertaining to the role of master signifiers in the clinical domain of (individual) psychical economy. The popularity of the concept of the master (or “empty”) signifier in political discourse analysis has thus proved a double-edged sword. On the one hand it demonstrates how crucial psychical processes are performed via the operations of the signifier, extending thus the Lacanian thesis that identification is the outcome of linguistic and symbolic as opposed to merely psychological processes. On the other, the use of the master signifier concept within the political realm to track discursive formations tends to distance the term from the dynamics of the unconscious and operation of repression. Accordingly, this paper revisits the master signifier concept, and does so within the socio-political domain, yet while paying particular attention to the functioning of unconscious processes of fantasy and repression. More specifically, it investigates how Nelson Mandela operates as a master signifier in contemporary South Africa, as a vital means of knitting together diverse elements of post-apartheid society, enabling the fantasy of the post-apartheid nation, and holding at bay a whole series of repressed and negated undercurrents. PMID:26834664

  10. Ability of a solid state fermentation technique to significantly minimize catabolic repression of. alpha. -amylase production by Bacillus licheniformis M27

    Energy Technology Data Exchange (ETDEWEB)

    Ramesh, M.V.; Lonsane, B.K. (Central Food Technological Research Inst., Mysore (India). Fermentation Technology and Bioengineering Discipline)

    1991-08-01

    The production of {alpha}-amylase by Bacillus licheniformis M27 in submerged fermentation was completely inhibited due to catabolic repression in medium containing 1% glucose. In contrast, the enzyme production in a solid state fermentation system was 19,550 units/ml extract even when the medium contained 15% glucose. The peak in enzyme titre was, however, shifted from 48 to 72 h. The ability of the solid state fermentation system to significantly overcome catabolic repression was not known earlier and is probably conferred by various physico-chemical factors and culture conditions specific to the system. (orig.).

  11. Repression of sulfate assimilation is an adaptive response of yeast to the oxidative stress of zinc deficiency.

    Science.gov (United States)

    Wu, Chang-Yi; Roje, Sanja; Sandoval, Francisco J; Bird, Amanda J; Winge, Dennis R; Eide, David J

    2009-10-02

    The Zap1 transcription factor is a central player in the response of yeast to changes in zinc status. Previous studies identified over 80 genes activated by Zap1 in zinc-limited cells. In this report, we identified 36 genes repressed in a zinc- and Zap1-responsive manner. As a result, we have identified a new mechanism of Zap1-mediated gene repression whereby transcription of the MET3, MET14, and MET16 genes is repressed in zinc-limited cells. These genes encode the first three enzymes of the sulfate assimilation pathway. We found that MET30, encoding a component of the SCF(Met30) ubiquitin ligase, is a direct Zap1 target gene. MET30 expression is increased in zinc-limited cells, and this leads to degradation of Met4, a transcription factor responsible for MET3, MET14, and MET16 expression. Thus, Zap1 is responsible for a decrease in sulfate assimilation in zinc-limited cells. We further show that cells that are unable to down-regulate sulfate assimilation under zinc deficiency experience increased oxidative stress. This increased oxidative stress is associated with an increase in the NADP(+)/NADPH ratio and may result from a decrease in NADPH-dependent antioxidant activities. These studies have led to new insights into how cells adapt to nutrient-limiting growth conditions.

  12. Repression of Smad3 by Stat3 and c-Ski/SnoN induces gefitinib resistance in lung adenocarcinoma.

    Science.gov (United States)

    Makino, Yojiro; Yoon, Jeong-Hwan; Bae, Eunjin; Kato, Mitsuyasu; Miyazawa, Keiji; Ohira, Tatsuo; Ikeda, Norihiko; Kuroda, Masahiko; Mamura, Mizuko

    2017-03-04

    Cancer-associated inflammation develops resistance to the epidermal growth-factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in non-small cell lung cancers (NSCLCs) harboring oncogenic EGFR mutations. Stat3-mediated interleukin (IL)-6 signaling and Smad-mediated transforming growth factor-β (TGF-β) signaling pathways play crucial regulatory roles in cancer-associated inflammation. However, mechanisms how these pathways regulate sensitivity and resistance to EGFR-TKI in NSCLCs remain largely undetermined. Here we show that signal transducer and activator of transcription (Stat)3 represses Smad3 in synergy with the potent negative regulators of TGF-β signaling, c-Ski and SnoN, whereby renders gefitinib-sensitive HCC827 cells resistant. We found that IL-6 signaling via phosphorylated Stat3 induced gefitinib resistance as repressing transcription of Smad3, whereas TGF-β enhanced gefitinib sensitivity as activating transcription of Smad3 in HCC827 cells with gefitinib-sensitizing EGFR mutation. Promoter analyses showed that Stat3 synergized with c-Ski/SnoN to repress Smad2/3/4-induced transcription of the Smad3 gene. Smad3 was found to be an apoptosis inducer, which upregulated pro-apoptotic genes such as caspase-3 and downregulated anti-apoptotic genes such as Bcl-2. Our results suggest that derepression of Smad3 can be a therapeutic strategy to prevent gefitinib-resistance in NSCLCs with gefitinib-sensitizing EGFR mutation.

  13. Ikaros mediates gene silencing in T cells through Polycomb repressive complex 2

    Science.gov (United States)

    Oravecz, Attila; Apostolov, Apostol; Polak, Katarzyna; Jost, Bernard; Le Gras, Stéphanie; Chan, Susan; Kastner, Philippe

    2015-01-01

    T-cell development is accompanied by epigenetic changes that ensure the silencing of stem cell-related genes and the activation of lymphocyte-specific programmes. How transcription factors influence these changes remains unclear. We show that the Ikaros transcription factor forms a complex with Polycomb repressive complex 2 (PRC2) in CD4−CD8− thymocytes and allows its binding to more than 500 developmentally regulated loci, including those normally activated in haematopoietic stem cells and others induced by the Notch pathway. Loss of Ikaros in CD4−CD8− cells leads to reduced histone H3 lysine 27 trimethylation and ectopic gene expression. Furthermore, Ikaros binding triggers PRC2 recruitment and Ikaros interacts with PRC2 independently of the nucleosome remodelling and deacetylation complex. Our results identify Ikaros as a fundamental regulator of PRC2 function in developing T cells. PMID:26549758

  14. Genome editing in butterflies reveals that spalt promotes and Distal-less represses eyespot colour patterns.

    Science.gov (United States)

    Zhang, Linlin; Reed, Robert D

    2016-06-15

    Butterfly eyespot colour patterns are a key example of how a novel trait can appear in association with the co-option of developmental patterning genes. Little is known, however, about how, or even whether, co-opted genes function in eyespot development. Here we use CRISPR/Cas9 genome editing to determine the roles of two co-opted transcription factors that are expressed during early eyespot determination. We found that deletions in a single gene, spalt, are sufficient to reduce or completely delete eyespot colour patterns, thus demonstrating a positive regulatory role for this gene in eyespot determination. Conversely, and contrary to previous predictions, deletions in Distal-less (Dll) result in an increase in the size and number of eyespots, illustrating a repressive role for this gene in eyespot development. Altogether our results show that the presence, absence and shape of butterfly eyespots can be controlled by the activity of two co-opted transcription factors.

  15. La-related protein 1 (LARP1) represses terminal oligopyrimidine (TOP) mRNA translation downstream of mTOR complex 1 (mTORC1)

    DEFF Research Database (Denmark)

    Fonseca, Bruno; Zakaria, Chadi; Jia, J J

    2015-01-01

    to repress TOP mRNA translation; and (iv) LARP1 competes with the eukaryotic initiation factor (eIF) 4G for TOP mRNA binding. Importantly, from a drug resistance standpoint, our data also show that reducing LARP1 protein levels by RNA interference attenuates the inhibitory effect of rapamycin, Torin1...

  16. Cyclic di-GMP regulation of the bvg-repressed genes and the orphan response regulator RisA in Bordetella pertussis

    Science.gov (United States)

    Expression of Bordetella pertussis virulence factors is activated by the BvgAS two-component system. Under modulating growth conditions BvgAS indirectly represses another set of genes through the action of BvgR, a bvg-activated protein. BvgR blocks activation of the response regulator RisA which is ...

  17. PICKLE acts throughout the plant to repress expression of embryonic traits and may play a role in Giberellin-Dependent responses

    NARCIS (Netherlands)

    Henderson, J.; Li, H.C.; Mordhorst, A.P.; Romero-Severson, J.; Cheng, J.C.; Robey, J.; Sung, Z.R.; Vries, de S.C.; Ogas, J.

    2004-01-01

    A seed marks the transition between two developmental states; a plant is an embryo during seed formation, whereas it is a seedling after emergence from the seed. Two factors have been identified in Arabidopsis that play a role in establishment of repression of the embryonic state: PKL (PICKLE), whic

  18. Nonredundant and locus-specific gene repression functions of PRC1 paralog family members in human hematopoietic stem/progenitor cells

    NARCIS (Netherlands)

    van den Boom, Vincent; Rozenveld-Geugien, Marjan; Bonardi, Francesco; Malanga, Donatella; van Gosliga, Djoke; Heyink, Anne Margriet; Viglietto, Giuseppe; Morrone, Giovanni; Fusetti, Fabrizia; Vellenga, Edo; Schuringa, Jan Jacob

    2013-01-01

    The Polycomb group (PcG) protein BMI1 is a key factor in regulating hematopoietic stem cell (HSC) and leukemic stem cell self-renewal and functions in the context of the Polycomb repressive complex 1 (PRC1). In humans, each of the 5 subunits of PRC1 has paralog family members of which many reside in

  19. Functional Analysis of the Nitrogen Metabolite Repression Regulator Gene nmrA in Aspergillus flavus

    Directory of Open Access Journals (Sweden)

    Xiaoyun Han

    2016-11-01

    Full Text Available In Aspergillus nidulans, the nitrogen metabolite repression regulator NmrA plays a major role in regulating the activity of the GATA transcription factor AreA during nitrogen metabolism. However, the function of nmrA in Aspergillus flavus has notbeen previously studied. Here, we report the identification and functional analysis of nmrA in A. flavus. Our work showed that the amino acid sequences of NmrA are highly conserved among Aspergillus species and that A. flavus NmrA protein contains a canonical Rossmann fold motif. Deletion of nmrA slowed the growth of A. flavus but significantly increased conidiation and sclerotia production. Moreover, seed infection experiments indicated that nmrA is required for the invasive virulence of A. flavus. In addition, the ΔnmrA mutant showed increased sensitivity to rapamycin and methyl methanesulfonate, suggesting that nmrA could be responsive to target of rapamycin signaling and DNA damage. Furthermore, quantitative real-time reverse transcription polymerase chain reaction analysis suggested that nmrA might interact with other nitrogen regulatory and catabolic genes. Our study provides a better understanding of nitrogen metabolite repression and the nitrogen metabolism network in fungi.

  20. Cyclic stretch of Embryonic Cardiomyocytes Increases Proliferation, Growth, and Expression While Repressing Tgf-β Signaling

    Science.gov (United States)

    Banerjee, Indroneal; Carrion, Katrina; Serrano, Ricardo; Dyo, Jeffrey; Sasik, Roman; Lund, Sean; Willems, Erik; Aceves, Seema; Meili, Rudolph; Mercola, Mark; Chen, Ju; Zambon, Alexander; Hardiman, Gary; Doherty, Taylor A; Lange, Stephan; del Álamo, Juan C.; Nigam, Vishal

    2014-01-01

    Perturbed biomechanical stimuli are thought to be critical for the pathogenesis of a number of congenital heart defects, including Hypoplastic Left Heart Syndrome (HLHS). While embryonic cardiomyocytes experience biomechanical stretch every heart beat, their molecular responses to biomechanical stimuli during heart development are poorly understood. We hypothesized that biomechanical stimuli activate specific signaling pathways that impact proliferation, gene expression and myocyte contraction. The objective of this study was to expose embryonic mouse cardiomyocytes (EMCM) to cyclic stretch and examine key molecular and phenotypic responses. Analysis of RNA-Sequencing data demonstrated that gene ontology groups associated with myofibril and cardiac development were significantly modulated. Stretch increased EMCM proliferation, size, cardiac gene expression, and myofibril protein levels. Stretch also repressed several components belonging to the Transforming Growth Factor-β (Tgf-β) signaling pathway. EMCMs undergoing cyclic stretch had decreased Tgf-β expression, protein levels, and signaling. Furthermore, treatment of EMCMs with a Tgf-β inhibitor resulted in increased EMCM size. Functionally, Tgf-β signaling repressed EMCM proliferation and contractile function, as assayed via dynamic monolayer force microscopy (DMFM). Taken together, these data support the hypothesis that biomechanical stimuli play a vital role in normal cardiac development and for cardiac pathology, including HLHS. PMID:25446186

  1. Identification of novel secreted fatty acids that regulate nitrogen catabolite repression in fission yeast.

    Science.gov (United States)

    Sun, Xiaoying; Hirai, Go; Ueki, Masashi; Hirota, Hiroshi; Wang, Qianqian; Hongo, Yayoi; Nakamura, Takemichi; Hitora, Yuki; Takahashi, Hidekazu; Sodeoka, Mikiko; Osada, Hiroyuki; Hamamoto, Makiko; Yoshida, Minoru; Yashiroda, Yoko

    2016-02-19

    Uptake of poor nitrogen sources such as branched-chain amino acids is repressed in the presence of high-quality nitrogen sources such as NH4(+) and glutamate (Glu), which is called nitrogen catabolite repression. Amino acid auxotrophic mutants of the fission yeast Schizosaccharomyces pombe were unable to grow on minimal medium containing NH4Cl or Glu even when adequate amounts of required amino acids were supplied. However, growth of these mutant cells was recovered in the vicinity of colonies of the prototrophic strain, suggesting that the prototrophic cells secrete some substances that can restore uptake of amino acids by an unknown mechanism. We identified the novel fatty acids, 10(R)-acetoxy-8(Z)-octadecenoic acid and 10(R)-hydroxy-8(Z)-octadecenoic acid, as secreted active substances, referred to as Nitrogen Signaling Factors (NSFs). Synthetic NSFs were also able to shift nitrogen source utilization from high-quality to poor nitrogen sources to allow adaptive growth of the fission yeast amino acid auxotrophic mutants in the presence of high-quality nitrogen sources. Finally, we demonstrated that the Agp3 amino acid transporter was involved in the adaptive growth. The data highlight a novel intra-species communication system for adaptation to environmental nutritional conditions in fission yeast.

  2. Pax6 represses androgen receptor-mediated transactivation by inhibiting recruitment of the coactivator SPBP.

    Directory of Open Access Journals (Sweden)

    Julianne Elvenes

    Full Text Available The androgen receptor (AR has a central role in development and maintenance of the male reproductive system and in the etiology of prostate cancer. The transcription factor Pax6 has recently been reported to act as a repressor of AR and to be hypermethylated in prostate cancer cells. SPBP is a transcriptional regulator that previously has been shown to enhance the activity of Pax6. In this study we have identified SPBP to act as a transcriptional coactivator of AR. We also show that Pax6 inhibits SPBP-mediated enhancement of AR activity on the AR target gene probasin promoter, a repression that was partly reversed by increased expression of SPBP. Enhanced expression of Pax6 reduced the amount of SPBP associated with the probasin promoter when assayed by ChIP in HeLa cells. We mapped the interaction between both AR and SPBP, and AR and Pax6 to the DNA-binding domains of the involved proteins. Further binding studies revealed that Pax6 and SPBP compete for binding to AR. These results suggest that Pax6 represses AR activity by displacing and/or inhibiting recruitment of coactivators to AR target promoters. Understanding the mechanism for inhibition of AR coactivators can give rise to molecular targeted drugs for treatment of prostate cancer.

  3. Sox9 transcriptionally represses Spp1 to prevent matrix mineralization in maturing heart valves and chondrocytes.

    Directory of Open Access Journals (Sweden)

    Jacqueline D Peacock

    Full Text Available Sox9 is an SRY-related transcription factor required for expression of cartilaginous genes in the developing skeletal system and heart valve structures. In contrast to positively regulating cartilaginous matrix, Sox9 also negatively regulates matrix mineralization associated with bone formation. While the transcriptional activation of Sox9 target genes during chondrogenesis has been characterized, the mechanisms by which Sox9 represses osteogenic processes are not so clear. Using ChIP-on-chip and luciferase assays we show that Sox9 binds and represses transactivation of the osteogenic glycoprotein Spp1. In addition, Sox9 knockdown in post natal mouse heart valve explants and rib chondrocyte cultures promotes Spp1 expression and matrix mineralization, while attenuating expression of cartilage genes Type II Collagen and Cartilage Link Protein. Further, we show that Spp1 is required for matrix mineralization induced by Sox9 knockdown. These studies provide insights into the molecular mechanisms by which Sox9 prevents pathologic matrix mineralization in tissues that must remain cartilaginous.

  4. Proto-oncogene PBF/PTTG1IP regulates thyroid cell growth and represses radioiodide treatment.

    Science.gov (United States)

    Read, Martin L; Lewy, Greg D; Fong, Jim C W; Sharma, Neil; Seed, Robert I; Smith, Vicki E; Gentilin, Erica; Warfield, Adrian; Eggo, Margaret C; Knauf, Jeffrey A; Leadbeater, Wendy E; Watkinson, John C; Franklyn, Jayne A; Boelaert, Kristien; McCabe, Christopher J

    2011-10-01

    Pituitary tumor transforming gene (PTTG)-binding factor (PBF or PTTG1IP) is a little characterized proto-oncogene that has been implicated in the etiology of breast and thyroid tumors. In this study, we created a murine transgenic model to target PBF expression to the thyroid gland (PBF-Tg mice) and found that these mice exhibited normal thyroid function, but a striking enlargement of the thyroid gland associated with hyperplastic and macrofollicular lesions. Expression of the sodium iodide symporter (NIS), a gene essential to the radioiodine ablation of thyroid hyperplasia, neoplasia, and metastasis, was also potently inhibited in PBF-Tg mice. Critically, iodide uptake was repressed in primary thyroid cultures from PBF-Tg mice, which could be rescued by PBF depletion. PBF-Tg thyroids exhibited upregulation of Akt and the TSH receptor (TSHR), each known regulators of thyrocyte proliferation, along with upregulation of the downstream proliferative marker cyclin D1. We extended and confirmed findings from the mouse model by examining PBF expression in human multinodular goiters (MNG), a hyperproliferative thyroid disorder, where PBF and TSHR was strongly upregulated relative to normal thyroid tissue. Furthermore, we showed that depleting PBF in human primary thyrocytes was sufficient to increase radioiodine uptake. Together, our findings indicate that overexpression of PBF causes thyroid cell proliferation, macrofollicular lesions, and hyperplasia, as well as repression of the critical therapeutic route for radioiodide uptake.

  5. Proto-oncogene PBF/PTTG1IP regulates thyroid cell growth and represses radioiodide treatment

    Science.gov (United States)

    Read, Martin L.; Lewy, Greg D.; Fong, Jim C.W.; Sharma, Neil; Seed, Robert I.; Smith, Vicki E.; Gentilin, Erica; Warfield, Adrian; Eggo, Margaret C.; Knauf, Jeffrey A.; Leadbeater, Wendy E.; Watkinson, John C.; Franklyn, Jayne A.; Boelaert, Kristien; McCabe, Christopher J.

    2011-01-01

    PTTG Binding Factor (PBF or PTTG1IP) is a little characterised proto-oncogene that has been implicated in the etiology of breast and thyroid tumors. In this study, we created a murine transgenic model to target PBF expression to the thyroid gland (PBF-Tg mice) and found that these mice exhibited normal thyroid function but a striking enlargement of the thyroid gland associated with hyperplastic and macrofollicular lesions. Expression of the sodium iodide symporter (NIS), a gene essential to the radioiodine ablation of thyroid hyperplasia, neoplasia and metastasis, was also potently inhibited in PBF-Tg mice. Critically, iodide uptake was repressed in primary thyroid cultures from PBF-Tg mice, which could be rescued by PBF depletion. PBF-Tg thyroids exhibited upregulation of Akt and the TSH receptor (TSHR), each known regulators of thyrocyte proliferation, along with upregulation of the downstream proliferative marker cyclin D1. We extended and confirmed findings from the mouse model by examining PBF expression in human multinodular goitres (MNG), a hyperproliferative thyroid disorder, where PBF and TSHR was strongly upregulated relative to normal thyroid tissue. Further, we showed that depleting PBF in human primary thyrocytes was sufficient to increase radioiodine uptake. Together, our findings indicate that overexpression of PBF causes thyroid cell proliferation, macrofollicular lesions and hyperplasia, as well as repression of the critical therapeutic route for radioiodide uptake. PMID:21844185

  6. Repression of Seed Maturation Genes by a Trihelix Transcriptional Repressor in Arabidopsis Seedlings[W

    Science.gov (United States)

    Gao, Ming-Jun; Lydiate, Derek J.; Li, Xiang; Lui, Helen; Gjetvaj, Branimir; Hegedus, Dwayne D.; Rozwadowski, Kevin

    2009-01-01

    The seed maturation program is repressed during germination and seedling development so that embryonic genes are not expressed in vegetative organs. Here, we describe a regulator that represses the expression of embryonic seed maturation genes in vegetative tissues. ASIL1 (for Arabidopsis 6b-interacting protein 1-like 1) was isolated by its interaction with the Arabidopsis thaliana 2S3 promoter. ASIL1 possesses domains conserved in the plant-specific trihelix family of DNA binding proteins and belongs to a subfamily of 6b-interacting protein 1-like factors. The seedlings of asil1 mutants exhibited a global shift in gene expression to a profile resembling late embryogenesis. LEAFY COTYLEDON1 and 2 were markedly derepressed during early germination, as was a large subset of seed maturation genes, such as those encoding seed storage proteins and oleosins, in seedlings of asil1 mutants. Consistent with this, asil1 seedlings accumulated 2S albumin and oil with a fatty acid composition similar to that of seed-derived lipid. Moreover, ASIL1 specifically recognized a GT element that overlaps the G-box and is in close proximity to the RY repeats of the 2S promoters. We suggest that ASIL1 targets GT-box–containing embryonic genes by competing with the binding of transcriptional activators to this promoter region. PMID:19155348

  7. miR-29 Represses the Activities of DNA Methyltransferases and DNA Demethylases

    Directory of Open Access Journals (Sweden)

    Izuho Hatada

    2013-07-01

    Full Text Available Members of the microRNA-29 (miR-29 family directly target the DNA methyltransferases, DNMT3A and DNMT3B. Disturbances in the expression levels of miR-29 have been linked to tumorigenesis and tumor aggressiveness. Members of the miR-29 family are currently thought to repress DNA methylation and suppress tumorigenesis by protecting against de novo methylation. Here, we report that members of the miR-29 family repress the activities of DNA methyltransferases and DNA demethylases, which have opposing roles in control of DNA methylation status. Members of the miR-29 family directly inhibited DNA methyltransferases and two major factors involved in DNA demethylation, namely tet methylcytosine dioxygenase 1 (TET1 and thymine DNA glycosylase (TDG. Overexpression of miR-29 upregulated the global DNA methylation level in some cancer cells and downregulated DNA methylation in other cancer cells, suggesting that miR-29 suppresses tumorigenesis by protecting against changes in the existing DNA methylation status rather than by preventing de novo methylation of DNA.

  8. DEWAX-mediated transcriptional repression of cuticular wax biosynthesis in Arabidopsis thaliana.

    Science.gov (United States)

    Suh, Mi Chung; Go, Young Sam

    2014-06-06

    The aerial parts of plants are covered with a cuticular wax layer, which is the first barrier between a plant and its environment. Although cuticular wax deposition increases more in the light than in the dark, little is known about the molecular mechanisms underlying the regulation of cuticular wax biosynthesis. Recently DEWAX (Decrease Wax Biosynthesis) encoding an AP2/ERF transcription factor was found to be preferentially expressed in the epidermis and induced by darkness. Wax analysis of the dewax knockout mutant, wild type, and DEWAX overexpression lines (OX) indicates that DEWAX is a negative regulator of cuticular wax biosynthesis. DEWAX represses the expression of wax biosynthetic genes CER1, LACS2, ACLA2, and ECR via direct interaction with their promoters. Cuticular wax biosynthesis is negatively regulated twice a day by the expression of DEWAX; throughout the night and another for stomata closing. Taken together, it is evident that DEWAX-mediated negative regulation of the wax biosynthetic genes plays role in determining the total wax loads produced in Arabidopsis during daily dark and light cycles. In addition, significantly higher levels of DEWAX transcripts in leaves than stems suggest that DEWAX-mediated transcriptional repression might be involved in the organ-specific regulation of total wax amounts on plant surfaces.

  9. Position-dependent interactions of Y-box protein 2 (YBX2) with mRNA enable mRNA storage in round spermatids by repressing mRNA translation and blocking translation-dependent mRNA decay.

    Science.gov (United States)

    Kleene, Kenneth C

    2016-03-01

    Many mRNAs encoding proteins needed for the construction of the specialized organelles of spermatozoa are stored as translationally repressed, free messenger ribonucleoproteins in round spermatids, to be actively translated in elongating and elongated spermatids. The factors that repress translation in round spermatids, however, have been elusive. Two lines of evidence implicate the highly abundant and well-known translational repressor, Y-box protein 2 (YBX2), as a critical factor: First, protamine 1 (Prm1) and sperm-mitochondria cysteine-rich protein (Smcp) mRNAs are prematurely recruited onto polysomes in Ybx2-knockout mouse round spermatids. Second, mutations in 3' untranslated region (3'UTR) cis-elements that abrogate YBX2 binding activate translation of Prm1 and Smcp mRNAs in round spermatids of transgenic mice. The abundance of YBX2 and its affinity for variable sequences, however, raise questions of how YBX2 targets specific mRNAs for repression. Mutations to the Prm1 and Smcp mRNAs in transgenic mice reveal that strong repression in round spermatids requires YBX2 binding sites located near the 3' ends of their 3'UTRs as locating the same sites in upstream positions produce negligible repression. This location-dependence implies that the assembly of repressive complexes is nucleated by adjacent cis-elements that enable cooperative interactions of YBX2 with co-factors. The available data suggest that, in vertebrates, YBX2 has the important role of coordinating the storage of translationally repressed mRNAs in round spermatids by inhibiting translational activity and the degradation of transcripts via translation-dependent deadenylation. These insights should facilitiate future experiments designed to unravel how YBX2 targets mRNAs for repression in round spermatids and how mutations in the YBX2 gene cause infertility in humans. Mol. Reprod. Dev. 83: 190-207, 2016. © 2016 Wiley Periodicals, Inc.

  10. ICP0 antagonizes Stat 1-dependent repression of herpes simplex virus: implications for the regulation of viral latency

    Directory of Open Access Journals (Sweden)

    Balliet John W

    2006-06-01

    Full Text Available Abstract Background The herpes simplex virus type 1 (HSV-1 ICP0 protein is an E3 ubiquitin ligase, which is encoded within the HSV-1 latency-associated locus. When ICP0 is not synthesized, the HSV-1 genome is acutely susceptible to cellular repression. Reciprocally, when ICP0 is synthesized, viral replication is efficiently initiated from virions or latent HSV-1 genomes. The current study was initiated to determine if ICP0's putative role as a viral interferon (IFN antagonist may be relevant to the process by which ICP0 influences the balance between productive replication versus cellular repression of HSV-1. Results Wild-type (ICP0+ strains of HSV-1 produced lethal infections in scid or rag2-/- mice. The replication of ICP0- null viruses was rapidly repressed by the innate host response of scid or rag2-/- mice, and the infected animals remained healthy for months. In contrast, rag2-/- mice that lacked the IFN-α/β receptor (rag2-/- ifnar-/- or Stat 1 (rag2-/- stat1-/- failed to repress ICP0- viral replication, resulting in uncontrolled viral spread and death. Thus, the replication of ICP0- viruses is potently repressed in vivo by an innate immune response that is dependent on the IFN-α/β receptor and the downstream transcription factor, Stat 1. Conclusion ICP0's function as a viral IFN antagonist is necessary in vivo to prevent an innate, Stat 1-dependent host response from rapidly repressing productive HSV-1 replication. This antagonistic relationship between ICP0 and the host IFN response may be relevant in regulating whether the HSV-1 genome is expressed, or silenced, in virus-infected cells in vivo. These results may also be clinically relevant. IFN-sensitive ICP0- viruses are avirulent, establish long-term latent infections, and induce an adaptive immune response that is highly protective against lethal challenge with HSV-1. Therefore, ICP0- viruses appear to possess the desired safety and efficacy profile of a live vaccine against

  11. ZEB1 limits adenoviral infectability by transcriptionally repressing the Coxsackie virus and Adenovirus Receptor

    Directory of Open Access Journals (Sweden)

    Lacher Markus D

    2011-07-01

    Full Text Available Abstract Background We have previously reported that RAS-MEK (Cancer Res. 2003 May 1;63(9:2088-95 and TGF-β (Cancer Res. 2006 Feb 1;66(3:1648-57 signaling negatively regulate coxsackie virus and adenovirus receptor (CAR cell-surface expression and adenovirus uptake. In the case of TGF-β, down-regulation of CAR occurred in context of epithelial-to-mesenchymal transition (EMT, a process associated with transcriptional repression of E-cadherin by, for instance, the E2 box-binding factors Snail, Slug, SIP1 or ZEB1. While EMT is crucial in embryonic development, it has been proposed to contribute to the formation of invasive and metastatic carcinomas by reducing cell-cell contacts and increasing cell migration. Results Here, we show that ZEB1 represses CAR expression in both PANC-1 (pancreatic and MDA-MB-231 (breast human cancer cells. We demonstrate that ZEB1 physically associates with at least one of two closely spaced and conserved E2 boxes within the minimal CAR promoter here defined as genomic region -291 to -1 relative to the translational start ATG. In agreement with ZEB1's established role as a negative regulator of the epithelial phenotype, silencing its expression in MDA-MB-231 cells induced a partial Mesenchymal-to-Epithelial Transition (MET characterized by increased levels of E-cadherin and CAR, and decreased expression of fibronectin. Conversely, knockdown of ZEB1 in PANC-1 cells antagonized both the TGF-β-induced down-regulation of E-cadherin and CAR and the reduction of adenovirus uptake. Interestingly, even though ZEB1 clearly contributes to the TGF-β-induced mesenchymal phenotype of PANC-1 cells, TGF-β did not seem to affect ZEB1's protein levels or subcellular localization. These findings suggest that TGF-β may inhibit CAR expression by regulating factor(s that cooperate with ZEB1 to repress the CAR promoter, rather than by regulating ZEB1 expression levels. In addition to the negative E2 box-mediated regulation the minimal

  12. Hypoxic repression of CYP7A1 through a HIF-1α- and SHP-independent mechanism

    OpenAIRE

    Moon, Yunwon; Park, Bongju; Park, Hyunsung

    2016-01-01

    Liver cells experience hypoxic stress when drug-metabolizing enzymes excessively consume O2 for hydroxylation. Hypoxic stress changes the transcription of several genes by activating a heterodimeric transcription factor called hypoxia-inducible factor-1α/β (HIF-1α/β). We found that hypoxic stress (0.1% O2) decreased the expression of cytochrome P450 7A1 (CYP7A1), a rate-limiting enzyme involved in bile acid biosynthesis. Chenodeoxycholic acid (CDCA), a major component of bile acids, represses...

  13. Repression of death consciousness and the psychedelic trip

    Directory of Open Access Journals (Sweden)

    Varsha Dutta

    2012-01-01

    Full Text Available Death is our most repressed consciousness, it inheres our condition as the primordial fear. Perhaps it was necessary that this angst be repressed in man or he would be hurled against the dark forces of nature. Modern ethos was built on this edifice, where the ′denial of death′ while ′embracing one′s symbolic immortality′ would be worshipped, so this ideology simply overturned and repressed looking into the morass of the inevitable when it finally announced itself. Once this slowly pieced its way into all of life, ′death′ would soon become a terminology in medicine too and assert its position, by giving a push to those directly dealing with the dying to shy away from its emotional and spiritual affliction. The need to put off death and prolong one′s life would become ever more urgent. Research using psychedelics on the terminally ill which had begun in the 1950s and 1960s would coerce into another realm and alter the face of medicine; but the aggression with which it forced itself in the 1960s would soon be politically maimed, and what remained would be sporadic outpours that trickled its way from European labs and underground boot camps. Now, with the curtain rising, the question has etched itself again, about the use of psychedelic drugs in medicine, particularly psychedelic psychotherapy with the terminally ill. This study is an attempt to philosophically explore death anxiety from its existential context and how something that is innate in our condition cannot be therapeutically cured. Psychedelic use was immutably linked with ancient cultures and only recently has it seen its scientific revival, from which a scientific culture grew around psychedelic therapy. How much of what was threaded in the ritual and spiritual mores can be extricated and be interpreted in our own mechanized language of medicine is the question that nudges many.

  14. Repression of death consciousness and the psychedelic trip.

    Science.gov (United States)

    Dutta, Varsha

    2012-01-01

    Death is our most repressed consciousness, it inheres our condition as the primordial fear. Perhaps it was necessary that this angst be repressed in man or he would be hurled against the dark forces of nature. Modern ethos was built on this edifice, where the 'denial of death' while 'embracing one's symbolic immortality' would be worshipped, so this ideology simply overturned and repressed looking into the morass of the inevitable when it finally announced itself. Once this slowly pieced its way into all of life, 'death' would soon become a terminology in medicine too and assert its position, by giving a push to those directly dealing with the dying to shy away from its emotional and spiritual affliction. The need to put off death and prolong one's life would become ever more urgent. Research using psychedelics on the terminally ill which had begun in the 1950s and 1960s would coerce into another realm and alter the face of medicine; but the aggression with which it forced itself in the 1960s would soon be politically maimed, and what remained would be sporadic outpours that trickled its way from European labs and underground boot camps. Now, with the curtain rising, the question has etched itself again, about the use of psychedelic drugs in medicine, particularly psychedelic psychotherapy with the terminally ill. This study is an attempt to philosophically explore death anxiety from its existential context and how something that is innate in our condition cannot be therapeutically cured. Psychedelic use was immutably linked with ancient cultures and only recently has it seen its scientific revival, from which a scientific culture grew around psychedelic therapy. How much of what was threaded in the ritual and spiritual mores can be extricated and be interpreted in our own mechanized language of medicine is the question that nudges many.

  15. Blood-Brain Glucose Transfer: Repression in Chronic Hyperglycemia

    Science.gov (United States)

    Gjedde, Albert; Crone, Christian

    1981-10-01

    Diabetic patients with increased plasma glucose concentrations may develop cerebral symptoms of hypoglycemia when their plasma glucose is rapidly lowered to normal concentrations. The symptoms may indicate insufficient transport of glucose from blood to brain. In rats with chronic hyperglycemia the maximum glucose transport capacity of the blood-brain barrier decreased from 400 to 290 micromoles per 100 grams per minute. When plasma glucose was lowered to normal values, the glucose transport rate into brain was 20 percent below normal. This suggests that repressive changes of the glucose transport mechanism occur in brain endothelial cells in response to increased plasma glucose.

  16. The HTLV-1 Tax Oncoprotein Represses Ku80 Gene Expression

    OpenAIRE

    Ducu, Razvan I.; Dayaram, Tajhal; Marriott, Susan J

    2011-01-01

    The HTLV-I oncoprotein Tax interferes with DNA double strand break repair. Since non-homologous end joining (NHEJ) is a major pathway used to repair DNA double strand breaks we examined the effect of Tax on this pathway, with particular interest in the expression and function of Ku80, a critical component of the NHEJ pathway. Tax expression decreased Ku80 mRNA and protein levels, and repressed transcription from the Ku80 promoter. Conversely, Ku80 mRNA increased following siRNA knockdown of T...

  17. Repressive coping and alexithymia in ideopathic environmental intolerance

    DEFF Research Database (Denmark)

    Skovbjerg, Sine; Zachariae, Robert; Rasmussen, Alice

    2010-01-01

    participated in a general population-based study and reported symptoms of environmental intolerance (n = 787) and patients with IEI (n = 237). The participants completed questionnaires assessing IEI, namely, a measure of repressive coping combining scores on the Marlowe–Crowne Social Desirability Scale (MCSDS......) and the Taylor Manifest Anxiety Scale (TMAS), the Toronto Alexithymia Scale (TAS-20), and a negative affectivity scale (NAS). Multiple, hierarchical linear regression analyses were conducted using IEI variables as the dependent variables. Results The TMAS and MCSDS scores were independently associated...

  18. SRSF3 represses the expression of PDCD4 protein by coordinated regulation of alternative splicing, export and translation.

    Science.gov (United States)

    Park, Seung Kuk; Jeong, Sunjoo

    2016-02-05

    Gene expression is regulated at multiple steps, such as transcription, splicing, export, degradation and translation. Considering diverse roles of SR proteins, we determined whether the tumor-related splicing factor SRSF3 regulates the expression of the tumor-suppressor protein, PDCD4, at multiple steps. As we have reported previously, knockdown of SRSF3 increased the PDCD4 protein level in SW480 colon cancer cells. More interestingly, here we showed that the alternative splicing and the nuclear export of minor isoforms of pdcd4 mRNA were repressed by SRSF3, but the translation step was unaffected. In contrast, only the translation step of the major isoform of pdcd4 mRNA was repressed by SRSF3. Therefore, overexpression of SRSF3 might be relevant to the repression of all isoforms of PDCD4 protein levels in most types of cancer cell. We propose that SRSF3 could act as a coordinator of the expression of PDCD4 protein via two mechanisms on two alternatively spliced mRNA isoforms.

  19. SRSF3 represses the expression of PDCD4 protein by coordinated regulation of alternative splicing, export and translation

    Energy Technology Data Exchange (ETDEWEB)

    Park, Seung Kuk; Jeong, Sunjoo, E-mail: sjsj@dankook.ac.kr

    2016-02-05

    Gene expression is regulated at multiple steps, such as transcription, splicing, export, degradation and translation. Considering diverse roles of SR proteins, we determined whether the tumor-related splicing factor SRSF3 regulates the expression of the tumor-suppressor protein, PDCD4, at multiple steps. As we have reported previously, knockdown of SRSF3 increased the PDCD4 protein level in SW480 colon cancer cells. More interestingly, here we showed that the alternative splicing and the nuclear export of minor isoforms of pdcd4 mRNA were repressed by SRSF3, but the translation step was unaffected. In contrast, only the translation step of the major isoform of pdcd4 mRNA was repressed by SRSF3. Therefore, overexpression of SRSF3 might be relevant to the repression of all isoforms of PDCD4 protein levels in most types of cancer cell. We propose that SRSF3 could act as a coordinator of the expression of PDCD4 protein via two mechanisms on two alternatively spliced mRNA isoforms.

  20. GATA3 induces human T-cell commitment by restraining Notch activity and repressing NK-cell fate

    Science.gov (United States)

    Van de Walle, Inge; Dolens, Anne-Catherine; Durinck, Kaat; De Mulder, Katrien; Van Loocke, Wouter; Damle, Sagar; Waegemans, Els; De Medts, Jelle; Velghe, Imke; De Smedt, Magda; Vandekerckhove, Bart; Kerre, Tessa; Plum, Jean; Leclercq, Georges; Rothenberg, Ellen V.; Van Vlierberghe, Pieter; Speleman, Frank; Taghon, Tom

    2016-01-01

    The gradual reprogramming of haematopoietic precursors into the T-cell fate is characterized by at least two sequential developmental stages. Following Notch1-dependent T-cell lineage specification during which the first T-cell lineage genes are expressed and myeloid and dendritic cell potential is lost, T-cell specific transcription factors subsequently induce T-cell commitment by repressing residual natural killer (NK)-cell potential. How these processes are regulated in human is poorly understood, especially since efficient T-cell lineage commitment requires a reduction in Notch signalling activity following T-cell specification. Here, we show that GATA3, in contrast to TCF1, controls human T-cell lineage commitment through direct regulation of three distinct processes: repression of NK-cell fate, upregulation of T-cell lineage genes to promote further differentiation and restraint of Notch activity. Repression of the Notch1 target gene DTX1 hereby is essential to prevent NK-cell differentiation. Thus, GATA3-mediated positive and negative feedback mechanisms control human T-cell lineage commitment. PMID:27048872

  1. pH-Dependent DNA Distortion and Repression of Gene Expression by Pectobacterium atrosepticum PecS.

    Science.gov (United States)

    Deochand, Dinesh K; Meariman, Jacob K; Grove, Anne

    2016-07-15

    Transcriptional activity is exquisitely sensitive to changes in promoter DNA topology. Transcription factors may therefore control gene activity by modulating the relative positioning of -10 and -35 promoter elements. The plant pathogen Pectobacterium atrosepticum, which causes soft rot in potatoes, must alter gene expression patterns to ensure growth in planta. In the related soft-rot enterobacterium Dickeya dadantii, PecS functions as a master regulator of virulence gene expression. Here, we report that P. atrosepticum PecS controls gene activity by altering promoter DNA topology in response to pH. While PecS binds the pecS promoter with high affinity regardless of pH, it induces significant DNA distortion only at neutral pH, the pH at which the pecS promoter is repressed in vivo. At pH ∼8, DNA distortions are attenuated, and PecS no longer represses the pecS promoter. A specific histidine (H142) located in a crevice between the dimerization- and DNA-binding regions is required for pH-dependent changes in DNA distortion and repression of gene activity, and mutation of this histidine renders the mutant protein incapable of repressing the pecS promoter. We propose that protonated PecS induces a DNA conformation at neutral pH in which -10 and -35 promoter elements are suboptimally positioned for RNA polymerase binding; on deprotonation of PecS, binding is no longer associated with significant changes in DNA conformation, allowing gene expression. We suggest that this mode of gene regulation leads to differential expression of the PecS regulon in response to alkalinization of the plant apoplast.

  2. Amino acid 1-209 is essential for PDX-1-mediated repression of human CMV IE promoter activity

    Institute of Scientific and Technical Information of China (English)

    Jing CHEN; Lei CHEN; Ge LI; Lu CHENG; Yin HUANG; Jia-xin ZHANG; Wei-wei FAN; Da-ru LU

    2006-01-01

    Aim: To explore the different roles of pancreatic duodenal homeobox factors-1 (PDX-1) domains in PDX-1 mediated repression of human cytomegalovirus immediately early (CMV IE) promoter. Methods: A series of truncated PDX-1 mutants were constructed. The binding of PDX-1 and CMV IE promoter was identified by electrophoretic mobility shift assay (EMSA). The dual-reporter assay was applied to examine the repression activities of PDX-1 mutants on CMV IE promoter. In addition, RNAi technology was used to specifically knock down the endogenous PDX-1 expression. Results: The reporter assay indicated that compared to the mock controls (pEGFP-N2), overexpression of PDX-1 resulted in a 41% decrease of CMV IE promoter activity in the 293 cells (P<0.05) and 43% decrease in HeLa cells (P<0.05), and the repression levels of various truncated mutants played on CMV IE promoter were different. Specific knock down of the endogenous PDX-1 expression significantly restored the activity of CMV IE promoter. EMS A demonstrated that domain 3 is necessary for nuclear localization and DNA binding activity of PDX-1. However, binding of PDX-1 alone to CMV IE promoter was not sufficient to inhibit its transcriptional activity, and other domains of PDX-1 presented were also required. Conclusion: Our data suggested that the DNA binding activity of PDX-1 domain 3 and the cooperative binding of PDX-1 domain 1/2 with other proteins were required for PDX-1 mediated repression of CMV IE promoter.

  3. How social media matter: Repression and the diffusion of the Occupy Wall Street movement.

    Science.gov (United States)

    Suh, Chan S; Vasi, Ion Bogdan; Chang, Paul Y

    2017-07-01

    This study explores the role played by social media in reshaping the repression-mobilization relationship. Drawing on the case of the Occupy Wall Street movement, we examine the impact of Facebook and Twitter on the spatial diffusion of protests during a period of heightened state repression. Results from event history analyses suggest that the effects of repression on protest diffusion are contingent on the presence of social media accounts supporting the movement. We find that state repression at earlier protest sites encouraged activists to create Facebook and Twitter accounts in their own cities, which then served as important vehicles for the initiation of new Occupy protests. Moreover, results suggest that repression incidents can directly facilitate future protests in cities that already have Occupy Facebook accounts. This study highlights the potential of social media to both mediate and moderate the influence of repression on the diffusion of contemporary movements. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Mapping the transcription repressive domain in the highly conserved human gene hnulp1

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    HNULP1,a new member of the basic helixloop-helix transcription factors,contains a DUF654 domain in its C-terminus and is highly conserved from Drosophilae,yeast,zebrafish to mouse.The function of this motif,however,is currently unknown.In this research,we fused five deletion fragments of the DUF654 domain to the GAL4 DNA-binding domain and then co-transfected with plasmids L8G5-Luc and VP-16.The analysis of the GAL4 luciferase reporter gene indicated that fragments from 228 to 407 amino acids in the DUF654 domain had a strong transcription repression activity.Therefore,this study lays a solid foundation for research on the mechanism of hnulp1 transcriptional regulation and the function of the DUF654 domain.

  5. An X11alpha/FSBP complex represses transcription of the GSK3beta gene promoter.

    LENUS (Irish Health Repository)

    Lau, Kwok-Fai

    2010-08-04

    X11alpha is a neuronal adaptor protein that interacts with the amyloid precursor protein (APP) through a centrally located phosphotyrosine binding domain to inhibit the production of Abeta peptide that is deposited in Alzheimer\\'s disease brains. X11alpha also contains two C-terminal postsynaptic density-95, large discs, zona occludens 1 (PDZ) domains, and we show here that through its PDZ domains, X11alpha interacts with a novel transcription factor, fibrinogen silencer binding protein. Moreover, we show that an X11alpha\\/fibrinogen silencer binding protein complex signals to the nucleus to repress glycogen synthase kinase-3beta promoter activity. Glycogen synthase kinase-3beta is a favoured candidate kinase for phosphorylating tau in Alzheimer\\'s disease. Our findings show a new function for X11alpha that may impact on Alzheimer\\'s disease pathogenesis.

  6. Dopamine signaling leads to loss of Polycomb repression and aberrant gene activation in experimental parkinsonism

    DEFF Research Database (Denmark)

    Södersten, Erik; Feyder, Michael; Lerdrup, Mads

    2014-01-01

    Polycomb group (PcG) proteins bind to and repress genes in embryonic stem cells through lineage commitment to the terminal differentiated state. PcG repressed genes are commonly characterized by the presence of the epigenetic histone mark H3K27me3, catalyzed by the Polycomb repressive complex 2. ...... and thereby contribute to long-term maladaptive responses including the motor complications, or dyskinesia, caused by prolonged administration of L-DOPA in Parkinson's disease....

  7. Arabidopsis Flower and Embryo Developmental Genes are Repressed in Seedlings by Different Combinations of Polycomb Group Proteins in Association with Distinct Sets of Cis-regulatory Elements.

    Science.gov (United States)

    Wang, Hua; Liu, Chunmei; Cheng, Jingfei; Liu, Jian; Zhang, Lei; He, Chongsheng; Shen, Wen-Hui; Jin, Hong; Xu, Lin; Zhang, Yijing

    2016-01-01

    Polycomb repressive complexes (PRCs) play crucial roles in transcriptional repression and developmental regulation in both plants and animals. In plants, depletion of different members of PRCs causes both overlapping and unique phenotypic defects. However, the underlying molecular mechanism determining the target specificity and functional diversity is not sufficiently characterized. Here, we quantitatively compared changes of tri-methylation at H3K27 in Arabidopsis mutants deprived of various key PRC components. We show that CURLY LEAF (CLF), a major catalytic subunit of PRC2, coordinates with different members of PRC1 in suppression of distinct plant developmental programs. We found that expression of flower development genes is repressed in seedlings preferentially via non-redundant role of CLF, which specifically associated with LIKE HETEROCHROMATIN PROTEIN1 (LHP1). In contrast, expression of embryo development genes is repressed by PRC1-catalytic core subunits AtBMI1 and AtRING1 in common with PRC2-catalytic enzymes CLF or SWINGER (SWN). This context-dependent role of CLF corresponds well with the change in H3K27me3 profiles, and is remarkably associated with differential co-occupancy of binding motifs of transcription factors (TFs), including MADS box and ABA-related factors. We propose that different combinations of PRC members distinctively regulate different developmental programs, and their target specificity is modulated by specific TFs.

  8. Arabidopsis Flower and Embryo Developmental Genes are Repressed in Seedlings by Different Combinations of Polycomb Group Proteins in Association with Distinct Sets of Cis-regulatory Elements.

    Directory of Open Access Journals (Sweden)

    Hua Wang

    2016-01-01

    Full Text Available Polycomb repressive complexes (PRCs play crucial roles in transcriptional repression and developmental regulation in both plants and animals. In plants, depletion of different members of PRCs causes both overlapping and unique phenotypic defects. However, the underlying molecular mechanism determining the target specificity and functional diversity is not sufficiently characterized. Here, we quantitatively compared changes of tri-methylation at H3K27 in Arabidopsis mutants deprived of various key PRC components. We show that CURLY LEAF (CLF, a major catalytic subunit of PRC2, coordinates with different members of PRC1 in suppression of distinct plant developmental programs. We found that expression of flower development genes is repressed in seedlings preferentially via non-redundant role of CLF, which specifically associated with LIKE HETEROCHROMATIN PROTEIN1 (LHP1. In contrast, expression of embryo development genes is repressed by PRC1-catalytic core subunits AtBMI1 and AtRING1 in common with PRC2-catalytic enzymes CLF or SWINGER (SWN. This context-dependent role of CLF corresponds well with the change in H3K27me3 profiles, and is remarkably associated with differential co-occupancy of binding motifs of transcription factors (TFs, including MADS box and ABA-related factors. We propose that different combinations of PRC members distinctively regulate different developmental programs, and their target specificity is modulated by specific TFs.

  9. Evidence that regulatory protein MarA of Escherichia coli represses rob by steric hindrance.

    Science.gov (United States)

    McMurry, Laura M; Levy, Stuart B

    2010-08-01

    The MarA protein of Escherichia coli can both activate and repress the initiation of transcription, depending on the position and orientation of its degenerate 20-bp binding site ("marbox") at the promoter. For all three known repressed genes, the marbox overlaps the promoter. It has been reported that MarA represses the rob promoter via an RNA polymerase (RNAP)-DNA-MarA ternary complex. Under similar conditions, we found a ternary complex for the repressed purA promoter also. These findings, together with the backwards orientation of repressed marboxes, suggested a unique interaction of MarA with RNAP in repression. However, no repression-specific residues of MarA could be found among 38 single-alanine replacement mutations previously shown to retain activation function or among mutants from random mutagenesis. Mutations Thr12Ala, Arg36Ala, Thr95Ile, and Pro106Ala were more damaging for activation than for repression, some up to 10-fold, so these residues may play a specific role in activation. We found that nonspecific binding of RNAP to promoterless regions of DNA was presumably responsible for the ternary complexes seen previously. When RNAP binding was promoter specific, MarA reduced RNAP access to the rob promoter; there was little or no ternary complex. These findings strongly implicate steric hindrance as the mechanism of repression of rob by MarA.

  10. SIRT1 deacetylates RFX5 and antagonizes repression of collagen type I (COL1A2) transcription in smooth muscle cells

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Jun [Department of Respiratory Medicine, The First Affiliated Hospital of Nanjing Medical University (China); Department of Respiratory Medicine, Jiangsu Provincial Hospital of Chinese Traditional Medicine (China); Wu, Xiaoyan; Yang, Yuyu; Zhao, Yuhao [Atherosclerosis Research Center, Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Pathophysiology, Nanjing Medical University (China); Fang, Mingming [Jiangsu Jiankang Vocational Institute (China); Xie, Weiping, E-mail: wpxienjmu@gmail.com [Department of Respiratory Medicine, The First Affiliated Hospital of Nanjing Medical University (China); Wang, Hong, E-mail: hwangnjmu@gmail.com [Department of Respiratory Medicine, The First Affiliated Hospital of Nanjing Medical University (China); Xu, Yong [Atherosclerosis Research Center, Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Pathophysiology, Nanjing Medical University (China)

    2012-11-16

    Highlights: Black-Right-Pointing-Pointer SIRT1 interacts with and deacetylates RFX5. Black-Right-Pointing-Pointer SIRT1 activation attenuates whereas SIRT1 inhibition enhances collagen repression by RFX5 in vascular smooth muscle cells. Black-Right-Pointing-Pointer SIRT1 promotes cytoplasmic localization and proteasomal degradation of RFX5 and cripples promoter recruitment of RFX5. Black-Right-Pointing-Pointer IFN-{gamma} represses SIRT1 expression in vascular smooth muscle cells. Black-Right-Pointing-Pointer SIRT1 agonist alleviates collagen repression by IFN-{gamma} in vascular smooth muscle cells. -- Abstract: Decreased expression of collagen by vascular smooth muscle cells (SMCs) within the atherosclerotic plaque contributes to the thinning of the fibrous cap and poses a great threat to plaque rupture. Elucidation of the mechanism underlying repressed collagen type I (COL1A2) gene would potentially provide novel solutions that can prevent rupture-induced complications. We have previously shown that regulatory factor for X-box (RFX5) binds to the COL1A2 transcription start site and represses its transcription. Here we report that SIRT1, an NAD-dependent, class III deacetylase, forms a complex with RFX5. Over-expression of SIRT1 or NAMPT, which synthesizes NAD+ to activate SIRT1, or treatment with the SIRT1 agonist resveratrol decreases RFX5 acetylation and disrupts repression of the COL1A2 promoter activity by RFX5. On the contrary, knockdown of SIRT1 or treatment with SIRT1 inhibitors induces RFX5 acetylation and enhances the repression of collagen transcription. SIRT1 antagonizes RFX5 activity by promoting its nuclear expulsion and proteasomal degradation hence dampening its binding to the COL1A2 promoter. The pro-inflammatory cytokine IFN-{gamma} represses COL1A2 transcription by down-regulating SIRT1 expression in SMCs. Therefore, our data have identified as novel pathway whereby SIRT1 maintains collagen synthesis in SMCs by modulating RFX5 activity.

  11. Prox1 directly interacts with LSD1 and recruits the LSD1/NuRD complex to epigenetically co-repress CYP7A1 transcription.

    Science.gov (United States)

    Ouyang, Huafang; Qin, Yi; Liu, Yanfeng; Xie, Youhua; Liu, Jing

    2013-01-01

    Cholesterol 7α-hydroxylase (CYP7A1) catalyzes the first and rate-limiting step in the classical pathway of bile acids synthesis in liver and is crucial for maintaining lipid homeostasis. Hepatocyte nuclear factor 4α (HNF4α) and α1-fetoprotein transcription factor (FTF) are two major transcription factors driving CYP7A1 promoter activity in hepatocytes. Previous researches have shown that Prospero-related homeobox (Prox1) directly interacts with both HNF4α and FTF and potently co-represses CYP7A1 transcription and bile acid synthesis through unidentified mechanisms. In this work, mechanisms involved in Prox1-mediated co-repression were explored by identifying Prox1-associated proteins using immunoprecipitation followed by mass spectrometry (IP-MS) methodology. Multiple components of the epigenetically repressive lysine-specific demethylase 1 (LSD1)/nucleosome remodeling and histone deacetylase (NuRD) complex, most notably LSD1 and histone deacetylase 2 (HDAC2), were found to be associated with Prox1 and GST pulldown assay demonstrated that Prox1 directly interacts with LSD1. Sequential chromatin immunoprecipitation (ChIP) assays showed that Prox1 co-localizes with HNF4α, LSD1 and HDAC2 on CYP7A1 promoter in HepG2 cells. Furthermore, by using ChIP assay on HepG2 cells with endogenous Prox1 knocked down by RNA interference, Prox1 was shown to recruit LSD1 and HDAC2 onto CYP7A1 promoter and cause increased H3K4 demethylation. Finally, bile acids treatment of HepG2 cells, which significantly repressed CYP7A1 transcription, resulted in increased Prox1 and LSD1/NuRD complex occupancy on CYP7A1 promoter with a concurrent increase in H3K4 demethylation and H3/H4 deacetylation. These results showed that Prox1 interacts with LSD1 to recruit the repressive LSD1/NuRD complex to CYP7A1 promoter and co-represses transcription through epigenetic mechanisms. In addition, such Prox1-mediated epigenetic repression is involved in the physiologically essential negative feedback

  12. Prox1 directly interacts with LSD1 and recruits the LSD1/NuRD complex to epigenetically co-repress CYP7A1 transcription.

    Directory of Open Access Journals (Sweden)

    Huafang Ouyang

    Full Text Available Cholesterol 7α-hydroxylase (CYP7A1 catalyzes the first and rate-limiting step in the classical pathway of bile acids synthesis in liver and is crucial for maintaining lipid homeostasis. Hepatocyte nuclear factor 4α (HNF4α and α1-fetoprotein transcription factor (FTF are two major transcription factors driving CYP7A1 promoter activity in hepatocytes. Previous researches have shown that Prospero-related homeobox (Prox1 directly interacts with both HNF4α and FTF and potently co-represses CYP7A1 transcription and bile acid synthesis through unidentified mechanisms. In this work, mechanisms involved in Prox1-mediated co-repression were explored by identifying Prox1-associated proteins using immunoprecipitation followed by mass spectrometry (IP-MS methodology. Multiple components of the epigenetically repressive lysine-specific demethylase 1 (LSD1/nucleosome remodeling and histone deacetylase (NuRD complex, most notably LSD1 and histone deacetylase 2 (HDAC2, were found to be associated with Prox1 and GST pulldown assay demonstrated that Prox1 directly interacts with LSD1. Sequential chromatin immunoprecipitation (ChIP assays showed that Prox1 co-localizes with HNF4α, LSD1 and HDAC2 on CYP7A1 promoter in HepG2 cells. Furthermore, by using ChIP assay on HepG2 cells with endogenous Prox1 knocked down by RNA interference, Prox1 was shown to recruit LSD1 and HDAC2 onto CYP7A1 promoter and cause increased H3K4 demethylation. Finally, bile acids treatment of HepG2 cells, which significantly repressed CYP7A1 transcription, resulted in increased Prox1 and LSD1/NuRD complex occupancy on CYP7A1 promoter with a concurrent increase in H3K4 demethylation and H3/H4 deacetylation. These results showed that Prox1 interacts with LSD1 to recruit the repressive LSD1/NuRD complex to CYP7A1 promoter and co-represses transcription through epigenetic mechanisms. In addition, such Prox1-mediated epigenetic repression is involved in the physiologically essential negative

  13. Host and bacterial proteins that repress recruitment of LC3 to Shigella early during infection.

    Directory of Open Access Journals (Sweden)

    Leigh A Baxt

    Full Text Available Shigella spp. are intracytosolic gram-negative pathogens that cause disease by invasion and spread through the colonic mucosa, utilizing host cytoskeletal components to form propulsive actin tails. We have previously identified the host factor Toca-1 as being recruited to intracellular S. flexneri and being required for efficient bacterial actin tail formation. We show that at early times during infection (40 min., the type three-secreted effector protein IcsB recruits Toca-1 to intracellular bacteria and that recruitment of Toca-1 is associated with repression of recruitment of LC3, as well as with repression of recruitment of the autophagy marker NDP52, around these intracellular bacteria. LC3 is best characterized as a marker of autophagosomes, but also marks phagosomal membranes in the process LC3-associated phagocytosis. IcsB has previously been demonstrated to be required for S. flexneri evasion of autophagy at late times during infection (4-6 hr by inhibiting binding of the autophagy protein Atg5 to the Shigella surface protein IcsA (VirG. Our results suggest that IcsB and Toca-1 modulation of LC3 recruitment restricts LC3-associated phagocytosis and/or LC3 recruitment to vacuolar membrane remnants. Together with published results, our findings suggest that IcsB inhibits innate immune responses in two distinct ways, first, by inhibiting LC3-associated phagocytosis and/or LC3 recruitment to vacuolar membrane remnants early during infection, and second, by inhibiting autophagy late during infection.

  14. Churchill regulates cell movement and mesoderm specification by repressing Nodal signaling

    Directory of Open Access Journals (Sweden)

    Mentzer Laura

    2007-11-01

    Full Text Available Abstract Background Cell movements are essential to the determination of cell fates during development. The zinc-finger transcription factor, Churchill (ChCh has been proposed to regulate cell fate by regulating cell movements during gastrulation in the chick. However, the mechanism of action of ChCh is not understood. Results We demonstrate that ChCh acts to repress the response to Nodal-related signals in zebrafish. When ChCh function is abrogated the expression of mesodermal markers is enhanced while ectodermal markers are expressed at decreased levels. In cell transplant assays, we observed that ChCh-deficient cells are more motile than wild-type cells. When placed in wild-type hosts, ChCh-deficient cells often leave the epiblast, migrate to the germ ring and are later found in mesodermal structures. We demonstrate that both movement of ChCh-compromised cells to the germ ring and acquisition of mesodermal character depend on the ability of the donor cells to respond to Nodal signals. Blocking Nodal signaling in the donor cells at the levels of Oep, Alk receptors or Fast1 inhibited migration to the germ ring and mesodermal fate change in the donor cells. We also detect additional unusual movements of transplanted ChCh-deficient cells which suggests that movement and acquisition of mesodermal character can be uncoupled. Finally, we demonstrate that ChCh is required to limit the transcriptional response to Nodal. Conclusion These data establish a broad role for ChCh in regulating both cell movement and Nodal signaling during early zebrafish development. We show that chch is required to limit mesodermal gene expression, inhibit Nodal-dependant movement of presumptive ectodermal cells and repress the transcriptional response to Nodal signaling. These findings reveal a dynamic role for chch in regulating cell movement and fate during early development.

  15. The glycosyltransferase LARGE2 is repressed by Snail and ZEB1 in prostate cancer.

    Science.gov (United States)

    Huang, Qin; Miller, Michael R; Schappet, James; Henry, Michael D

    2015-01-01

    Reductions in both expression of the dystroglycan core protein and functional glycosylation of the α-dystroglycan (αDG) subunit have been reported in a number of cancers and may contribute to disease progression. In the case of prostate cancer, one mechanism that contributes to αDG hypoglycosylation is transcriptional down-regulation of LARGE2 (GYLTY1B), a glycosyltransferase that produces the functional (laminin-binding) glycan on αDG, but the mechanism(s) underlying reduction of LARGE2 mRNA remain unclear. Here, we show that αDG hypoglycosylation is associated with epithelial-to-mesenchymal transition (EMT)-like status. We examined immunoreactivity for both functionally-glycosylated αDG and E-cadherin by flow cytometry and the relative expression of ZEB1 mRNA and the αDG glycosyltransferase LARGE2 mRNA in prostate and other cancer cell lines by quantitative RT-PCR. To study the role of ZEB1 and other transcription factors in the regulation of LARGE2, we employed overexpression and knockdown approaches. Snail- or ZEB1-driven EMT caused αDG hypoglycosylation by repressing expression of the LARGE2 mRNA, with both ZEB1-dependent and -independent mechanisms contributing to Snail-mediated LARGE2 repression. To examine the direct regulation of LARGE2 by Snail and ZEB1 we employed luciferase reporter and chromatin immunoprecipitation assays. Snail and ZEB1 were found to bind directly to the LARGE2 promoter, specifically to E/Z-box clusters. Furthermore, analysis of gene expression profiles of clinical samples in The Cancer Genome Atlas reveals negative correlation of LARGE2 and ZEB1 expression in various cancers. Collectively, our results suggest that LARGE2 is negatively regulated by Snail and/or ZEB1, revealing a mechanistic basis for αDG hypoglycosylation during prostate cancer progression and metastasis.

  16. Polycomb repressive complex 2 epigenomic signature defines age-associated hypermethylation and gene expression changes

    Science.gov (United States)

    Dozmorov, Mikhail G

    2015-01-01

    Although age-associated gene expression and methylation changes have been reported throughout the literature, the unifying epigenomic principles of aging remain poorly understood. Recent explosion in availability and resolution of functional/regulatory genome annotation data (epigenomic data), such as that provided by the ENCODE and Roadmap Epigenomics projects, provides an opportunity for the identification of epigenomic mechanisms potentially altered by age-associated differentially methylated regions (aDMRs) and regulatory signatures in the promoters of age-associated genes (aGENs). In this study we found that aDMRs and aGENs identified in multiple independent studies share a common Polycomb Repressive Complex 2 signature marked by EZH2, SUZ12, CTCF binding sites, repressive H3K27me3, and activating H3K4me1 histone modification marks, and a “poised promoter” chromatin state. This signature is depleted in RNA Polymerase II-associated transcription factor binding sites, activating H3K79me2, H3K36me3, H3K27ac marks, and an “active promoter” chromatin state. The PRC2 signature was shown to be generally stable across cell types. When considering the directionality of methylation changes, we found the PRC2 signature to be associated with aDMRs hypermethylated with age, while hypomethylated aDMRs were associated with enhancers. In contrast, aGENs were associated with the PRC2 signature independently of the directionality of gene expression changes. In this study we demonstrate that the PRC2 signature is the common epigenomic context of genomic regions associated with hypermethylation and gene expression changes in aging. PMID:25880792

  17. REST represses a subset of the pancreatic endocrine differentiation program

    DEFF Research Database (Denmark)

    Martin, David; Kim, Yung-Hae; Sever, Dror

    2015-01-01

    To contribute to devise successful beta-cell differentiation strategies for the cure of Type 1 diabetes we sought to uncover barriers that restrict endocrine fate acquisition by studying the role of the transcriptional repressor REST in the developing pancreas. Rest expression is prevented...... in neurons and in endocrine cells, which is necessary for their normal function. During development, REST represses a subset of genes in the neuronal differentiation program and Rest is down-regulated as neurons differentiate. Here, we investigate the role of REST in the differentiation of pancreatic...... endocrine cells, which are molecularly close to neurons. We show that Rest is widely expressed in pancreas progenitors and that it is down-regulated in differentiated endocrine cells. Sustained expression of REST in Pdx1(+) progenitors impairs the differentiation of endocrine-committed Neurog3...

  18. Citizenship or Repression? Coca, Eradication and Development in the Andes

    Directory of Open Access Journals (Sweden)

    Thomas Grisaffi

    2016-03-01

    Full Text Available For over two decades the US has funded repressive forced coca eradication in Peru, Colombia and Bolivia to reduce the illegal cocaine trade. These policies have never met their stated goals and have generated violence and poverty. In 2006 Bolivia definitively broke with the US anti-narcotics model, replacing the militarized eradication of coca crops with a community-based coca control strategy. The program substantially reduced the coca crop while simultaneously respecting human rights and allowing farmers to diversify their livelihoods. This article outlines the elements of the Bolivian initiative that ensure its continued successful functioning. It explores to what extent this model can be translated to other Andean contexts.

  19. Intermediate filament transcription in astrocytes is repressed by proteasome inhibition

    Science.gov (United States)

    Middeldorp, Jinte; Kamphuis, Willem; Sluijs, Jacqueline A.; Achoui, Dalila; Leenaars, Cathalijn H. C.; Feenstra, Matthijs G. P.; van Tijn, Paula; Fischer, David F.; Berkers, Celia; Ovaa, Huib; Quinlan, Roy A.; Hol, Elly M.

    2009-01-01

    Increased expression of the astrocytic intermediate filament protein glial fibrillary acidic protein (GFAP) is a characteristic of astrogliosis. This process occurs in the brain during aging and neurodegeneration and coincides with impairment of the ubiquitin proteasome system. Inhibition of the proteasome impairs protein degradation; therefore, we hypothesized that the increase in GFAP may be the result of impaired proteasomal activity in astrocytes. We investigated the effect of proteasome inhibitors on GFAP expression and other intermediate filament proteins in human astrocytoma cells and in a rat brain model for astrogliosis. Extensive quantitative RT-PCR, immunocytochemistry, and Western blot analysis resulted unexpectedly in a strong decrease of GFAP mRNA to Hol, E. M. Intermediate filament transcription in astrocytes is repressed by proteasome inhibition. PMID:19332645

  20. Retinoid X receptor alpha represses GATA-4-mediated transcription via a retinoid-dependent interaction with the cardiac-enriched repressor FOG-2.

    Science.gov (United States)

    Clabby, Martha L; Robison, Trevor A; Quigley, Heather F; Wilson, David B; Kelly, Daniel P

    2003-02-21

    Dietary vitamin A and its derivatives, retinoids, regulate cardiac growth and development. To delineate mechanisms involved in retinoid-mediated control of cardiac gene expression, the regulatory effects of the retinoid X receptor alpha (RXR alpha) on atrial naturietic factor (ANF) gene transcription was investigated. The transcriptional activity of an ANF promoter-reporter in rat neonatal ventricular myocytes was repressed by RXR alpha in the presence of 9-cis-RA and by the constitutively active mutant RXR alpha F318A indicating that liganded RXR confers the regulatory effect. The RXR alpha-mediated repression mapped to the proximal 147 bp of the rat ANF promoter, a region lacking a consensus retinoid response element but containing several known cardiogenic cis elements including a well characterized GATA response element. Glutathione S-transferase "pull-down" assays revealed that RXR alpha interacts directly with GATA-4, in a ligand-independent manner, via the DNA binding domain of RXR alpha and the second zinc finger of GATA-4. Liganded RXR alpha repressed the activity of a heterologous promoter-reporter construct containing GATA-response element recognition sites in cardiac myocytes but not in several other cell types, suggesting that additional cardiac-enriched factors participate in the repression complex. Co-transfection of liganded RXR alpha and the known cardiac-enriched GATA-4 repressor, FOG-2, resulted in additive repression of GATA-4 activity in ventricular myocytes. In addition, RXR alpha was found to bind FOG-2, in a 9-cis-RA-dependent manner. These data reveal a novel mechanism by which retinoids regulate cardiogenic gene expression through direct interaction with GATA-4 and its co-repressor, FOG-2.

  1. Serum repressing efflux pump CDR1 in Candida albicans

    Directory of Open Access Journals (Sweden)

    Fan Jen-Chung

    2006-07-01

    Full Text Available Abstract Background In the past decades, the prevalence of candidemia has increased significantly and drug resistance has also become a pressing problem. Overexpression of CDR1, an efflux pump, has been proposed as a major mechanism contributing to the drug resistance in Candida albicans. It has been demonstrated that biological fluids such as human serum can have profound effects on antifungal pharmacodynamics. The aim of this study is to understand the effects of serum in drug susceptibility via monitoring the activity of CDR1 promoter of C. albicans. Results The wild-type C. albicans cells (SC5314 but not the cdr1/cdr1 mutant cells became more susceptible to the antifungal drug when the medium contained serum. To understand the regulation of CDR1 in the presence of serum, we have constructed CDR1 promoter-Renilla luciferase (CDR1p-RLUC reporter to monitor the activity of the CDR1 promoter in C. albicans. As expected, the expression of CDR1p-RLUC was induced by miconazole. Surprisingly, it was repressed by serum. Consistently, the level of CDR1 mRNA was also reduced in the presence of serum but not N-acetyl-D-glucosamine, a known inducer for germ tube formation. Conclusion Our finding that the expression of CDR1 is repressed by serum raises the question as to how does CDR1 contribute to the drug resistance in C. albicans causing candidemia. This also suggests that it is important to re-assess the prediction of in vivo therapeutic outcome of candidemia based on the results of standard in vitro antifungal susceptibility testing, conducted in the absence of serum.

  2. Identification of the minimal repression domain of SUPERMAN shows that the DLELRL hexapeptide is both necessary and sufficient for repression of transcription in Arabidopsis.

    Science.gov (United States)

    Hiratsu, Keiichiro; Mitsuda, Nobutaka; Matsui, Kyoko; Ohme-Takagi, Masaru

    2004-08-13

    We reported previously that the carboxy-terminal 30 amino acids of SUPERMAN (SUPRD) function as a repression domain in Arabidopsis. In this study, we identified the peptide sequences in SUPRD that is both necessary and sufficient for repression of transcription. To our surprise, the hexapeptide DLELRL was sufficient, by itself, to confer the ability to repress transcription on a DNA-binding domain. A database search revealed that there are 32 TFIIIA-type zinc finger proteins in the Arabidopsis genome that contain a hexapeptide sequence similar or identical to that of DLELRL. These peptides acted as repression domains, suggesting that these zinc finger proteins might function as active repressors. Further mutational analysis within DLELRL revealed that an amphiphilic motif composed of six amino acids (XLxLXL) with preferences at the first and fifth positions is necessary and sufficient for strong repression. An assay of positional effects suggested that GAL4DB-DLELRL might function as a short-range repressor. A possible mechanism of the DLELRL-mediated repression is discussed.

  3. Overexpression of a Gene Encoding a Catabolite Repression Element in Alternaria citri Causes Severe Symptoms of Black Rot in Citrus Fruit.

    Science.gov (United States)

    Katoh, H; Ohtani, K; Yamamoto, H; Akimitsu, K

    2007-05-01

    ABSTRACT A gene (AcCreA) encoding a catabolite repression element (CreA) with (two zinc fingers of the Cys(2)His(2) type was isolated from the postharvest fungal pathogen Alternaria citri. The AcCreA overexpression mutant AcOEC2 of A. citri showed normal growth on pectin medium and on segments of peel or the juice sac area from citrus fruit. Production of endopolygalacturonase, an essential virulence factor of this pathogen, was similar in AcOEC2 and the wild type in pectin-containing media. However, addition of glucose to the medium showed that carbon catabolite repression of endopolygalacturonase gene (Acpg1) expression, as well as endopolygalacturonase production, was lost in AcOEC2. The wild-type strain of A. citri causes rot mainly in the central axis of citrus fruit without development of rotting in the juice sac area; however, AcOEC2 caused severe black rot symptoms in both the central axis and juice sac areas. These results indicate that AcCreA-mediated catabolite repression controls the virulence or infection of this pathogen, and that the wild-type A. citri does not cause symptoms in the juice sac area due to carbon catabolite repression by sugars in the juice of the juice sac area.

  4. Epigenetic involvement of Alien/ESET complex in thyroid hormone-mediated repression of E2F1 gene expression and cell proliferation

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Wei, E-mail: hongwei@tijmu.edu.cn [Department of Immunology, Tianjin Medical University, 300070 Tianjin (China); College of Basic Medicine, Tianjin Medical University, 300070 Tianjin (China); Li, Jinru; Wang, Bo [College of Basic Medicine, Tianjin Medical University, 300070 Tianjin (China); Chen, Linfeng [Department of Medical Oncology, Harvard Medical School, Dana Farber Cancer Institute, Boston, 02115 MA (United States); Niu, Wenyan; Yao, Zhi [Department of Immunology, Tianjin Medical University, 300070 Tianjin (China); Baniahmad, Aria, E-mail: aban@mti.uni-jena.de [Institute for Human Genetics, Jena University Hospital, 07740 Jena (Germany)

    2011-12-02

    Highlights: Black-Right-Pointing-Pointer Corepressor Alien interacts with histone methyltransferase ESET in vivo. Black-Right-Pointing-Pointer Alien/ESET complex is recruited to nTRE of T3-responsive gene by liganded TR{beta}1. Black-Right-Pointing-Pointer ESET-mediated H3K9 methylation is required for liganded TR{beta}1-repressed transcription. Black-Right-Pointing-Pointer ESET is involved in T3-repressed G1/S phase transition and proliferation. -- Abstract: The ligand-bound thyroid hormone receptor (TR) is known to repress via a negative TRE (nTRE) the expression of E2F1, a key transcription factor that controls the G1/S phase transition. Alien has been identified as a novel interacting factor of E2F1 and acts as a corepressor of E2F1. The detailed molecular mechanism by which Alien inhibits E2F1 gene expression remains unclear. Here, we report that the histone H3 lysine 9 (H3K9) methyltransferase (HMT) ESET is an integral component of the corepressor Alien complex and the Alien/ESET complex is recruited to both sites, the E2F1 and the nTRE site of the E2F1 gene while the recruitment to the negative thyroid hormone response element (nTRE) is induced by the ligand-bound TR{beta}1 within the E2F1 gene promoter. We show that, overexpression of ESET promotes, whereas knockdown of ESET releases, the inhibition of TR{beta}1-regulated gene transcription upon T3 stimulation; and H3K9 methylation is required for TR{beta}1-repressed transcription. Furthermore, depletion of ESET impairs thyroid hormone-repressed proliferation as well as the G1/S transition of the cell cycle. Taken together, our data indicate that ESET is involved in TR{beta}1-mediated transcription repression and provide a molecular basis of thyroid hormone-induced repression of proliferation.

  5. JARID2 regulates binding of the Polycomb repressive complex 2 to target genes in ES cells

    DEFF Research Database (Denmark)

    Pasini, Diego; Cloos, Paul A C; Walfridsson, Julian

    2010-01-01

    The Polycomb group (PcG) proteins have an important role in controlling the expression of genes essential for development, differentiation and maintenance of cell fates. The Polycomb repressive complex 2 (PRC2) is believed to regulate transcriptional repression by catalysing the di- and tri-methy...

  6. Repressive Coping, Emotional Adjustment, and Cognition in People Who Have Lost Loved Ones to Suicide

    Science.gov (United States)

    Parker, Holly A.; McNally, Richard J.

    2008-01-01

    Research indicates that a repressive coping style is psychologically protective against the stress of trauma, yet it is unclear whether this finding generalizes to suicide bereavement. Thus, we assessed cognitive ability and mental health among individuals who lost a loved one to suicide. The results indicate that repressive coping may be…

  7. The crystal structure of the AhRR/ARNT heterodimer reveals the structural basis of the repression of AhR-mediated transcription.

    Science.gov (United States)

    Sakurai, Shunya; Shimizu, Toshiyuki; Ohto, Umeharu

    2017-09-13

    2,3,7,8-Tetrachlorodibenzo-p-dioxin and related compounds (TCDDs) are extraordinarily potent environmental toxic pollutants. Most of the TCDD toxicities are mediated by aryl hydrocarbon receptor (AhR), a ligand-dependent transcription factor belonging to the basic helix-loop-helix-Per-ARNT-Sim (bHLH-PAS) family. Upon ligand binding, AhR forms a heterodimer with AhR nuclear translocator (ARNT) and induces the expression of genes involved in various biological responses. One of the genes induced by AhR encodes AhR repressor (AhRR), which also forms a heterodimer with ARNT and represses the activation of AhR-dependent transcription. The control of AhR activation is critical for managing AhR-mediated diseases, but the mechanisms by which AhRR represses AhR activation remain poorly understood, due to the lack of structural information. Here, we determined the structure of the AhRR/ARNT heterodimer by X-ray crystallography, which revealed an asymmetric intertwined domain organization presenting structural features that are both conserved and distinct among bHLH-PAS family members. The structures of AhRR/ARNT and AhR/ARNT were similar in the bHLH-PAS-A region, while the PAS-B of ARNT in the AhRR/ARNT complex exhibited a different domain arrangement in this family reported so far. The structure clearly disclosed that AhRR competitively represses AhR binding to ARNT and target DNA, and further suggested the existence of an AhRR/ARNT-specific repression mechanism. This study provides a structural basis for understanding the mechanism by which AhRR represses AhR-mediated gene transcription. Copyright © 2017, The American Society for Biochemistry and Molecular Biology.

  8. Extremadura: Behind the material traces of Franco’s repression

    Directory of Open Access Journals (Sweden)

    Muñoz Encinar, Laura

    2014-12-01

    Full Text Available After the failed coup d’état of July 17th, 1936 and after the start of the Spanish Civil War that followed it, rebels carried out a repressive strategy based on the execution of thousands of people as a key tool of social control. The socialization of fear and terror through humiliation, killing and disappearance would become the main strategy employed throughout the war and the post-war period. In this context, perpetrators would exercise repressive practices on victims and their bodies. As a result, countless mass graves were opened in order to hide the bodies of victims. In the region of Extremadura, these mass graves have been investigated through the application of archeology and physical anthropology as disciplines of research and historical knowledge production. The exhumations, have given us a diachronic point of view of the repressive strategies developed, associated with different contexts between 1936 and 1946. Analyses of mass executions linked to rebels’ occupation of territories in this region, systematic rearguard killings in occupied areas, elimination procedures carried out in concentration camps and prisons and the fight against the armed guerrilla during the dictatorship, are the main contributions of this article.Tras el fracaso del golpe de Estado del 17 de julio de 1936 y el inicio de la Guerra Civil en España, se llevó a cabo, por parte de los sublevados, una estrategia represiva basada en la ejecución de miles de personas como principal herramienta de control social. La socialización del miedo y el terror a través de las vejaciones, ejecuciones y desapariciones será la principal estrategia utilizada, donde el uso de las víctimas y los cuerpos formará también parte de las prácticas represivas ideadas por los perpetradores. Como consecuencia, se abrieron incontables fosas comunes con el objetivo de ocultar los cadáveres de los represaliados. Estas fosas han sido investigadas en la Comunidad Autónoma de

  9. Selective de-repression of germ cell-specific genes in mouse embryonic fibroblasts in a permissive epigenetic environment.

    Science.gov (United States)

    Sekinaka, Tamotsu; Hayashi, Yohei; Noce, Toshiaki; Niwa, Hitoshi; Matsui, Yasuhisa

    2016-09-09

    Epigenetic modifications play crucial roles on establishment of tissue-specific transcription profiles and cellular characteristics. Direct conversions of fibroblasts into differentiated tissue cells by over-expression of critical transcription factors have been reported, but the epigenetic mechanisms underlying these conversions are still not fully understood. In addition, conversion of somatic cells into germ cells has not yet been achieved. To understand epigenetic mechanisms that underlie germ cell characteristics, we attempted to use defined epigenetic factors to directly convert mouse embryonic fibroblasts (MEFs) into germ cells. Here, we successfully induced germ cell-specific genes by inhibiting repressive epigenetic modifications via RNAi or small-molecule compounds. Under these conditions, some tissue-specific genes and stimulus-inducible genes were also induced. Meanwhile, the treatments did not result in genome-wide transcriptional activation. These results suggested that a permissive epigenetic environment resulted in selective de-repression of stimulus- and differentiation-inducible genes including germ cell-specific genes in MEFs.

  10. Noncanonical role of Arabidopsis COP1/SPA complex in repressing BIN2-mediated PIF3 phosphorylation and degradation in darkness.

    Science.gov (United States)

    Ling, Jun-Jie; Li, Jian; Zhu, Danmeng; Deng, Xing Wang

    2017-03-28

    The E3 ligase CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) has been known to mediate key signaling factors for degradation via the ubiquitin/26S proteasome pathway in both plants and animals. Here, we report a noncanonical function of Arabidopsis COP1, the central repressor of photomorphogenesis, in the form of a COP1/ SUPPRESSOR of phyA-105 (SPA) complex. We show that the COP1/SPA complex associates with and stabilizes PHYTOCHROME INTERACTING FACTOR 3 (PIF3) to repress photomorphogenesis in the dark. We identify the GSK3-like kinase BRASSINOSTEROID-INSENSITIVE 2 (BIN2) as a kinase of PIF3, which induces PIF3 degradation via 26S proteasome during skotomorphogenesis. Mutations on two typical BIN2 phosphorylation motifs of PIF3 lead to a strong stabilization of the protein in the dark. We further show that the COP1/SPA complex promotes PIF3 stability by repressing BIN2 activity. Intriguingly, without affecting BIN2 expression, the COP1/SPA complex modulates BIN2 activity through interfering with BIN2-PIF3 interaction, thereby inhibiting BIN2-mediated PIF3 phosphorylation and degradation. Taken together, our results suggest another paradigm for COP1/SPA complex action in the precise control of skotomorphogenesis.

  11. Hypoxic repression of CYP7A1 through a HIF-1α- and SHP-independent mechanism.

    Science.gov (United States)

    Moon, Yunwon; Park, Bongju; Park, Hyunsung

    2016-03-01

    Liver cells experience hypoxic stress when drug-metabolizing enzymes excessively consume O2 for hydroxylation. Hypoxic stress changes the transcription of several genes by activating a heterodimeric transcription factor called hypoxia-inducible factor- 1α/β (HIF-1α/β). We found that hypoxic stress (0.1% O2) decreased the expression of cytochrome P450 7A1 (CYP7A1), a rate-limiting enzyme involved in bile acid biosynthesis. Chenodeoxycholic acid (CDCA), a major component of bile acids, represses CYP7A1 by activating a transcriptional repressor named small heterodimer partner (SHP). We observed that hypoxia decreased the levels of both CDCA and SHP, suggesting that hypoxia repressed CYP7A1 without inducing SHP. The finding that overexpression of HIF-1α increased the activity of the CYP7A1 promoter suggested that hypoxia decreased the expression of CYP7A1 in a HIF-1-independent manner. Thus, the results of this study suggested that hypoxia decreased the activity of CYP7A1 by limiting its substrate O2, and by decreasing the transcription of CYP7A1. [BMB Reports 2016; 49(3): 173-178].

  12. Selective de-repression of germ cell-specific genes in mouse embryonic fibroblasts in a permissive epigenetic environment

    Science.gov (United States)

    Sekinaka, Tamotsu; Hayashi, Yohei; Noce, Toshiaki; Niwa, Hitoshi; Matsui, Yasuhisa

    2016-01-01

    Epigenetic modifications play crucial roles on establishment of tissue-specific transcription profiles and cellular characteristics. Direct conversions of fibroblasts into differentiated tissue cells by over-expression of critical transcription factors have been reported, but the epigenetic mechanisms underlying these conversions are still not fully understood. In addition, conversion of somatic cells into germ cells has not yet been achieved. To understand epigenetic mechanisms that underlie germ cell characteristics, we attempted to use defined epigenetic factors to directly convert mouse embryonic fibroblasts (MEFs) into germ cells. Here, we successfully induced germ cell-specific genes by inhibiting repressive epigenetic modifications via RNAi or small-molecule compounds. Under these conditions, some tissue-specific genes and stimulus-inducible genes were also induced. Meanwhile, the treatments did not result in genome-wide transcriptional activation. These results suggested that a permissive epigenetic environment resulted in selective de-repression of stimulus- and differentiation-inducible genes including germ cell-specific genes in MEFs. PMID:27608931

  13. Repressed synthesis of ribosomal proteins generates protein-specific cell cycle and morphological phenotypes.

    Science.gov (United States)

    Thapa, Mamata; Bommakanti, Ananth; Shamsuzzaman, Md; Gregory, Brian; Samsel, Leigh; Zengel, Janice M; Lindahl, Lasse

    2013-12-01

    The biogenesis of ribosomes is coordinated with cell growth and proliferation. Distortion of the coordinated synthesis of ribosomal components affects not only ribosome formation, but also cell fate. However, the connection between ribosome biogenesis and cell fate is not well understood. To establish a model system for inquiries into these processes, we systematically analyzed cell cycle progression, cell morphology, and bud site selection after repression of 54 individual ribosomal protein (r-protein) genes in Saccharomyces cerevisiae. We found that repression of nine 60S r-protein genes results in arrest in the G2/M phase, whereas repression of nine other 60S and 22 40S r-protein genes causes arrest in the G1 phase. Furthermore, bud morphology changes after repression of some r-protein genes. For example, very elongated buds form after repression of seven 60S r-protein genes. These genes overlap with, but are not identical to, those causing the G2/M cell cycle phenotype. Finally, repression of most r-protein genes results in changed sites of bud formation. Strikingly, the r-proteins whose repression generates similar effects on cell cycle progression cluster in the ribosome physical structure, suggesting that different topological areas of the precursor and/or mature ribosome are mechanistically connected to separate aspects of the cell cycle.

  14. Age-associated repression of type 1 inositol 1, 4, 5-triphosphate receptor impairs muscle regeneration

    Science.gov (United States)

    Lee, Bora; Lee, Seung-Min; Bahn, Young Jae; Lee, Kwang-Pyo; Kang, Moonkyung; Kim, Yeon-Soo; Woo, Sun-Hee; Lim, Jae-Young; Kim, Eunhee; Kwon, Ki-Sun

    2016-01-01

    Skeletal muscle mass and power decrease with age, leading to impairment of mobility and metabolism in the elderly. Ca2+ signaling is crucial for myoblast differentiation as well as muscle contraction through activation of transcription factors and Ca2+-dependent kinases and phosphatases. Ca2+ channels, such as dihydropyridine receptor (DHPR), two-pore channel (TPC) and inositol 1,4,5-triphosphate receptor (ITPR), function to maintain Ca2+ homeostasis in myoblasts. Here, we observed a significant decrease in expression of type 1 IP3 receptor (ITPR1), but not types 2 and 3, in aged mice skeletal muscle and isolated myoblasts, compared with those of young mice. ITPR1 knockdown using shRNA-expressing viruses in C2C12 myoblasts and tibialis anterior muscle of mice inhibited myotube formation and muscle regeneration after injury, respectively, a typical phenotype of aged muscle. This aging phenotype was associated with repression of muscle-specific genes and activation of the epidermal growth factor receptor (EGFR)-Ras-extracellular signal-regulated kinase (ERK) pathway. ERK inhibition by U0126 not only induced recovery of myotube formation in old myoblasts but also facilitated muscle regeneration after injury in aged muscle. The conserved decline in ITPR1 expression in aged human skeletal muscle suggests utility as a potential therapeutic target for sarcopenia, which can be treated using ERK inhibition strategies. PMID:27658230

  15. Repression of HNF1α-mediated transcription by amino-terminal enhancer of split (AES)

    Energy Technology Data Exchange (ETDEWEB)

    Han, Eun Hee [Section of Structural Biology, Hormel Institute, University of Minnesota, Austin, MN 55912 (United States); Gorman, Amanda A. [Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY 40536 (United States); Singh, Puja [Section of Structural Biology, Hormel Institute, University of Minnesota, Austin, MN 55912 (United States); Chi, Young-In, E-mail: ychi@hi.umn.edu [Section of Structural Biology, Hormel Institute, University of Minnesota, Austin, MN 55912 (United States)

    2015-12-04

    HNF1α (Hepatocyte Nuclear Factor 1α) is one of the master regulators in pancreatic beta-cell development and function, and the mutations in Hnf1α are the most common monogenic causes of diabetes mellitus. As a member of the POU transcription factor family, HNF1α exerts its gene regulatory function through various molecular interactions; however, there is a paucity of knowledge in their functional complex formation. In this study, we identified the Groucho protein AES (Amino-terminal Enhancer of Split) as a HNF1α-specific physical binding partner and functional repressor of HNF1α-mediated transcription, which has a direct link to glucose-stimulated insulin secretion in beta-cells that is impaired in the HNF1α mutation-driven diabetes. - Highlights: • We identified AES as a transcriptional repressor for HNF1α in pancreatic beta-cell. • AES's repressive activity was HNF1α-specific and was not observed with HNF1β. • AES interacts with the transactivation domain of HNF1α. • Small molecules can be designed or discovered to disrupt this interaction and improve insulin secretion and glucose homeostasis.

  16. L30 binds the nascent RPL30 transcript to repress U2 snRNP recruitment.

    Science.gov (United States)

    Macías, Sara; Bragulat, Mireia; Tardiff, Daniel F; Vilardell, Josep

    2008-06-20

    The mechanisms of pre-mRNA splicing regulation are poorly understood. Here we dissect how the Saccharomyces cerevisiae ribosomal L30 protein blocks splicing of its pre-mRNA upon binding a kink-turn structure including the 5' splice site. We show that L30 binds the nascent RPL30 transcript without preventing recognition of the 5' splice site by U1 snRNP but blocking U2 snRNP association with the branch site. Interaction of the factors BBP and Mud2 with the intron, relevant for U2 snRNP recruitment, is not affected by L30. Furthermore, the functions of neither the DEAD-box protein Sub2 in the incipient spliceosome nor the U2 snRNP factor Cus2 on branch site recognition are required for L30 inhibition. These findings contrast with the effects caused by binding a heterologous protein to the same region, completely blocking intron recognition. Collectively, our data suggest that L30 represses a spliceosomal rearrangement required for U2 snRNP association with the transcript.

  17. Corticosteroid-Induced MKP-1 Represses Pro-Inflammatory Cytokine Secretion by Enhancing Activity of Tristetraprolin (TTP) in ASM Cells.

    Science.gov (United States)

    Prabhala, Pavan; Bunge, Kristin; Ge, Qi; Ammit, Alaina J

    2016-10-01

    Exaggerated cytokine secretion drives pathogenesis of a number of chronic inflammatory diseases, including asthma. Anti-inflammatory pharmacotherapies, including corticosteroids, are front-line therapies and although they have proven clinical utility, the molecular mechanisms responsible for their actions are not fully understood. The corticosteroid-inducible gene, mitogen-activated protein kinase (MAPK) phosphatase 1 (MKP-1, DUSP1) has emerged as a key molecule responsible for the repressive effects of steroids. MKP-1 is known to deactivate p38 MAPK phosphorylation and can control the expression and activity of the mRNA destabilizing protein-tristetraprolin (TTP). But whether corticosteroid-induced MKP-1 acts via p38 MAPK-mediated modulation of TTP function in a pivotal airway cell type, airway smooth muscle (ASM), was unknown. While pretreatment of ASM cells with the corticosteroid dexamethasone (preventative protocol) is known to reduce ASM synthetic function in vitro, the impact of adding dexamethasone after stimulation (therapeutic protocol) had not been explored. Whether dexamethasone modulates TTP in a p38 MAPK-dependent manner in this cell type was also unknown. We address this herein and utilize an in vitro model of asthmatic inflammation where ASM cells were stimulated with the pro-asthmatic cytokine tumor necrosis factor (TNF) and the impact of adding dexamethasone 1 h after stimulation assessed. IL-6 mRNA expression and protein secretion was significantly repressed by dexamethasone acting in a temporally distinct manner to increase MKP-1, deactivate p38 MAPK, and modulate TTP phosphorylation status. In this way, dexamethasone-induced MKP-1 acts via p38 MAPK to switch on the mRNA destabilizing function of TTP to repress pro-inflammatory cytokine secretion from ASM cells. J. Cell. Physiol. 231: 2153-2158, 2016. © 2016 Wiley Periodicals, Inc.

  18. Role of the BAHD1 Chromatin-Repressive Complex in Placental Development and Regulation of Steroid Metabolism

    Science.gov (United States)

    Lakisic, Goran; Wendling, Olivia; Libertini, Emanuele; Radford, Elizabeth J.; Le Guillou, Morwenna; Champy, Marie-France; Wattenhofer-Donzé, Marie; Soubigou, Guillaume; Ait-Si-Ali, Slimane; Feunteun, Jean; Sorg, Tania; Coppée, Jean-Yves; Ferguson-Smith, Anne C.; Cossart, Pascale; Bierne, Hélène

    2016-01-01

    BAHD1 is a vertebrate protein that promotes heterochromatin formation and gene repression in association with several epigenetic regulators. However, its physiological roles remain unknown. Here, we demonstrate that ablation of the Bahd1 gene results in hypocholesterolemia, hypoglycemia and decreased body fat in mice. It also causes placental growth restriction with a drop of trophoblast glycogen cells, a reduction of fetal weight and a high neonatal mortality rate. By intersecting transcriptome data from murine Bahd1 knockout (KO) placentas at stages E16.5 and E18.5 of gestation, Bahd1-KO embryonic fibroblasts, and human cells stably expressing BAHD1, we also show that changes in BAHD1 levels alter expression of steroid/lipid metabolism genes. Biochemical analysis of the BAHD1-associated multiprotein complex identifies MIER proteins as novel partners of BAHD1 and suggests that BAHD1-MIER interaction forms a hub for histone deacetylases and methyltransferases, chromatin readers and transcription factors. We further show that overexpression of BAHD1 leads to an increase of MIER1 enrichment on the inactive X chromosome (Xi). In addition, BAHD1 and MIER1/3 repress expression of the steroid hormone receptor genes ESR1 and PGR, both playing important roles in placental development and energy metabolism. Moreover, modulation of BAHD1 expression in HEK293 cells triggers epigenetic changes at the ESR1 locus. Together, these results identify BAHD1 as a core component of a chromatin-repressive complex regulating placental morphogenesis and body fat storage and suggest that its dysfunction may contribute to several human diseases. PMID:26938916

  19. Tcf3 represses Wnt-β-catenin signaling and maintains neural stem cell population during neocortical development.

    Directory of Open Access Journals (Sweden)

    Atsushi Kuwahara

    Full Text Available During mouse neocortical development, the Wnt-β-catenin signaling pathway plays essential roles in various phenomena including neuronal differentiation and proliferation of neural precursor cells (NPCs. Production of the appropriate number of neurons without depletion of the NPC population requires precise regulation of the balance between differentiation and maintenance of NPCs. However, the mechanism that suppresses Wnt signaling to prevent premature neuronal differentiation of NPCs is poorly understood. We now show that the HMG box transcription factor Tcf3 (also known as Tcf7l1 contributes to this mechanism. Tcf3 is highly expressed in undifferentiated NPCs in the mouse neocortex, and its expression is reduced in intermediate neuronal progenitors (INPs committed to the neuronal fate. We found Tcf3 to be a repressor of Wnt signaling in neocortical NPCs in a reporter gene assay. Tcf3 bound to the promoter of the proneural bHLH gene Neurogenin1 (Neurog1 and repressed its expression. Consistent with this, Tcf3 repressed neuronal differentiation and increased the self-renewal activity of NPCs. We also found that Wnt signal stimulation reduces the level of Tcf3, and increases those of Tcf1 (also known as Tcf7 and Lef1, positive mediators of Wnt signaling, in NPCs. Together, these results suggest that Tcf3 antagonizes Wnt signaling in NPCs, thereby maintaining their undifferentiated state in the neocortex and that Wnt signaling promotes the transition from Tcf3-mediated repression to Tcf1/Lef1-mediated enhancement of Wnt signaling, constituting a positive feedback loop that facilitates neuronal differentiation.

  20. Promoter DNA hypermethylation and gene repression in undifferentiated Arabidopsis cells.

    Directory of Open Access Journals (Sweden)

    María Berdasco

    Full Text Available Maintaining and acquiring the pluripotent cell state in plants is critical to tissue regeneration and vegetative multiplication. Histone-based epigenetic mechanisms are important for regulating this undifferentiated state. Here we report the use of genetic and pharmacological experimental approaches to show that Arabidopsis cell suspensions and calluses specifically repress some genes as a result of promoter DNA hypermethylation. We found that promoters of the MAPK12, GSTU10 and BXL1 genes become hypermethylated in callus cells and that hypermethylation also affects the TTG1, GSTF5, SUVH8, fimbrin and CCD7 genes in cell suspensions. Promoter hypermethylation in undifferentiated cells was associated with histone hypoacetylation and primarily occurred at CpG sites. Accordingly, we found that the process specifically depends on MET1 and DRM2 methyltransferases, as demonstrated with DNA methyltransferase mutants. Our results suggest that promoter DNA methylation may be another important epigenetic mechanism for the establishment and/or maintenance of the undifferentiated state in plant cells.

  1. Rewiring carbon catabolite repression for microbial cell factory

    Directory of Open Access Journals (Sweden)

    Parisutham Vinuselvi

    2012-02-01

    Full Text Available Carbon catabolite repression (CCR is a key regulatory systemfound in most microorganisms that ensures preferential utilizationof energy-efficient carbon sources. CCR helps microorganismsobtain a proper balance between their metaboliccapacity and the maximum sugar uptake capability. It alsoconstrains the deregulated utilization of a preferred cognatesubstrate, enabling microorganisms to survive and dominate innatural environments. On the other side of the same coin liesthe tenacious bottleneck in microbial production of bioproductsthat employs a combination of carbon sources in variedproportion, such as lignocellulose-derived sugar mixtures.Preferential sugar uptake combined with the transcriptionaland/or enzymatic exclusion of less preferred sugars turns outone of the major barriers in increasing the yield and productivityof fermentation process. Accumulation of the unusedsubstrate also complicates the downstream processes used toextract the desired product. To overcome this difficulty and todevelop tailor-made strains for specific metabolic engineeringgoals, quantitative and systemic understanding of the molecularinteraction map behind CCR is a prerequisite. Here wecomparatively review the universal and strain-specific featuresof CCR circuitry and discuss the recent efforts in developingsynthetic cell factories devoid of CCR particularly for lignocellulose-based biorefinery. [BMB reports 2012; 45(2: 59-70

  2. microRNAs-powerful repression comes from small RNAs

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    microRNAs (miRNAs) encode a novel class of small, non-coding RNAs that regulate gene expression post-trancriptionally. miRNAs comprise one of the major non-coding RNA families, whose diverse bio- logical functions and unusual capacity for gene regulation have attracted enormous interests in the RNA world. Over the past 16 years, genetic, biochemical and computational approaches have greatly shaped the growth of the field, leading to the identification of thousands of miRNA genes in nearly all metazoans. The key molecular machinery for miRNA biogenesis and silencing has been identified, yet the precise biochemical and regulatory mechanisms still remain elusive. However, recent findings have shed new light on how miRNAs are generated and how they function to repress gene expression. miRNAs provide a paradigm for endogenous small RNAs that mediate gene silencing at a genome-wide level. The gene silencing mediated by these small RNAs constitutes a major component of gene regu- lation during various developmental and physiological processes. The accumulating knowledge about their biogenesis and gene silencing mechanism will add a new dimension to our understanding about the complex gene regulatory networks.

  3. Possible Roles for Polycomb Repressive Complex 2 in Cereal Endosperm

    Directory of Open Access Journals (Sweden)

    Kaoru eTonosaki

    2015-03-01

    Full Text Available The Polycomb Repressive Complex 2 (PRC2 is an evolutionarily conserved multimeric protein complex in both plants and animals. In contrast to animals, plants have evolved a range of different components of PRC2 and form diverse complexes that act in the control of key regulatory genes at many stages of development during the life cycle. A number of studies, particularly in the model species Arabidopsis thaliana, have highlighted the role of PRC2 and of epigenetic controls via parent-of-origin specific gene expression for endosperm development. However, recent research in cereal plants has revealed that although some components of PRC2 show evolutionary conservation with respect to parent-of-origin specific gene expression patterns, the identity of the imprinted genes encoding PRC2 components is not conserved. This disparity may reflect the facts that cereal plant genomes have undergone different patterns of duplication during evolution compared to Arabidopsis thaliana and that the endosperm development program is not identical in monocots and eudicots. In this context, we focus this review on the expression of imprinted PRC2 genes and their roles in endosperm development in cereals.

  4. microRNAs- powerful repression comes from small RNAs

    Institute of Scientific and Technical Information of China (English)

    MA Cong; LIU YuFei; HE Lin

    2009-01-01

    microRNAs (miRNAs) encode a novel class of small, non-coding RNAs that regulate gene expression post-trancriptionally, miRNAs comprise one of the major non-coding RNA families, whose diverse bio-logical functions and unusual capacity for gene regulation have attracted enormous interests in the RNA world. Over the past 16 years, genetic, biochemical and computational approaches have greatly shaped the growth of the field, leading to the identification of thousands of miRNA genes in nearly all metazoans. The key molecular machinery for miRNA biogenesis and silencing has been identified, yet the precise biochemical and regulatory mechanisms still remain elusive. However, recent findings have shed new light on how miRNAs are generated and how they function to repress gene expression.miRNAs provide a paradigm for endogenous small RNAs that mediate gene silencing at a genome-wide level. The gene silencing mediated by these small RNAs constitutes a major component of gene regu-lation during various developmental and physiological processes. The accumulating knowledge about their biogenesis and gene silencing mechanism will add a now dimension to our understanding about the complex gene regulatory networks.

  5. MarA-mediated transcriptional repression of the rob promoter.

    Science.gov (United States)

    Schneiders, Thamarai; Levy, Stuart B

    2006-04-14

    The Escherichia coli transcriptional regulator MarA affects functions that include antibiotic resistance, persistence, and survival. MarA functions as an activator or repressor of transcription utilizing similar degenerate DNA sequences (marboxes) with three different binding site configurations with respect to the RNA polymerase-binding sites. We demonstrate that MarA down-regulates rob transcripts both in vivo and in vitro via a MarA-binding site within the rob promoter that is positioned between the -10 and -35 hexamers. As for the hdeA and purA promoters, which are repressed by MarA, the rob marbox is also in the "backward" orientation. Protein-DNA interactions show that SoxS and Rob, like MarA, bind the same marbox in the rob promoter. Electrophoretic mobility shift analyses with a MarA-specific antibody demonstrate that MarA and RNA polymerase form a ternary complex with the rob promoter DNA. Transcription experiments in vitro and potassium permanganate footprinting analysis show that MarA affects the RNA polymerase-mediated closed to open complex formation at the rob promoter.

  6. Andrei Sakharov Prize Talk: Supporting Repressed Scientists: Continuing Efforts

    Science.gov (United States)

    Birman, Joseph L.

    2010-02-01

    Some years ago, Max Perutz asked ``By What Right Do We Scientists Invoke Human Rights?" My presentation will start with mentioning actions of the international community which relate to this question. Such action as the creation in 1919 of the International Research Council, and continuing on to the present with the UN sanctioned International Council of Scientific Unions [ICSU], and other Committees such as those formed by APS, CCS, NYAS, AAAS which give support to repressed scientists around the world now. My own work has attempted to combine my individual initiatives with work as a member and officer of these groups. Together with like minded colleagues who are deeply affected when colleagues are discharged from their positions, exiled, imprisoned and subject to brutal treatment, often after mock ``trials", we react. On visits in 1968 to conferences in Budapest, and then in 1969 to Moscow, Tallin and Leningrad I became personally and deeply touched by the lives of colleagues who were seriously constrained by living under dictatorships. I could move freely into and out of their countries,speak openly about my work or any other matter. They could not, under penalty of possibly serious punishment. Yet, I felt these people were like my extended family. If my grandparents had not left Eastern Europe for the USA in the late 189Os our situations could have been reversed. A little later in the 197O's, ``refusenik" and ``dissident" scientists in the USSR needed support. Colleagues like Andrei Sakharov, Naum Meiman, Mark Azbel, Yakov Alpert, Yuri Orlov and others were being punished for exercising their rights under the UN sanctioned international protocals on ``Universality of Science and Free Circulation of Scientists". Their own governments [which signed these agreements] ignored the very protections they had supported. On frequent trips to the USSR during the 7Os,and 8Os I also seized the opportunity for ``individual initiative" to help these colleagues. I asked for

  7. Pronephric tubule morphogenesis in zebrafish depends on Mnx mediated repression of irx1b within the intermediate mesoderm.

    Science.gov (United States)

    Ott, Elisabeth; Wendik, Björn; Srivastava, Monika; Pacho, Frederic; Töchterle, Sonja; Salvenmoser, Willi; Meyer, Dirk

    2016-03-01

    Mutations in the homeobox transcription factor MNX1 are the major cause of dominantly inherited sacral agenesis. Studies in model organisms revealed conserved mnx gene requirements in neuronal and pancreatic development while Mnx activities that could explain the caudal mesoderm specific agenesis phenotype remain elusive. Here we use the zebrafish pronephros as a simple yet genetically conserved model for kidney formation to uncover a novel role of Mnx factors in nephron morphogenesis. Pronephros formation can formally be divided in four stages, the specification of nephric mesoderm from the intermediate mesoderm (IM), growth and epithelialisation, segmentation and formation of the glomerular capillary tuft. Two of the three mnx genes in zebrafish are dynamically transcribed in caudal IM in a time window that proceeds segmentation. We show that expression of one mnx gene, mnx2b, is restricted to the pronephric lineage and that mnx2b knock-down causes proximal pronephric tubule dilation and impaired pronephric excretion. Using expression profiling of embryos transgenic for conditional activation and repression of Mnx regulated genes, we further identified irx1b as a direct target of Mnx factors. Consistent with a repression of irx1b by Mnx factors, the transcripts of irx1b and mnx genes are found in mutual exclusive regions in the IM, and blocking of Mnx functions results in a caudal expansion of the IM-specific irx1b expression. Finally, we find that knock-down of irx1b is sufficient to rescue proximal pronephric tubule dilation and impaired nephron function in mnx-morpholino injected embryos. Our data revealed a first caudal mesoderm specific requirement of Mnx factors in a non-human system and they demonstrate that Mnx-dependent restriction of IM-specific irx1b activation is required for the morphogenesis and function of the zebrafish pronephros.

  8. The contentious fans: the impact of repression, media coverage, grievances and aggressive play on supporters’ violence

    NARCIS (Netherlands)

    Braun, R.; Vliegenthart, R.

    2008-01-01

    This article poses the question of which macro-sociological explanations best predict the level of soccer supporters’ violence. By conceptualizing supporters’ violence as a form of contentious violence, four possible explanations are proposed: repression, media attention, unemployment and aggressive

  9. Pachytene asynapsis drives meiotic sex chromosome inactivation and leads to substantial postmeiotic repression in spermatids.

    Science.gov (United States)

    Turner, James M A; Mahadevaiah, Shantha K; Ellis, Peter J I; Mitchell, Michael J; Burgoyne, Paul S

    2006-04-01

    Transcriptional silencing of the sex chromosomes during male meiosis (MSCI) is conserved among organisms with limited sex chromosome synapsis, including mammals. Since the 1990s the prevailing view has been that MSCI in mammals is transient, with sex chromosome reactivation occurring as cells exit meiosis. Recently, we found that any chromosome region unsynapsed during pachytene of male and female mouse meiosis is subject to transcriptional silencing (MSUC), and we hypothesized that MSCI is an inevitable consequence of this more general meiotic silencing mechanism. Here, we provide direct evidence that asynapsis does indeed drive MSCI. We also show that a substantial degree of transcriptional repression of the sex chromosomes is retained postmeiotically, and we provide evidence that this postmeiotic repression is a downstream consequence of MSCI/MSUC. While this postmeiotic repression occurs after the loss of MSUC-related proteins at the end of prophase, other histone modifications associated with transcriptional repression have by then become established.

  10. The contentious fans: the impact of repression, media coverage, grievances and aggressive play on supporters’ violence

    NARCIS (Netherlands)

    Braun, R.; Vliegenthart, R.

    2008-01-01

    This article poses the question of which macro-sociological explanations best predict the level of soccer supporters’ violence. By conceptualizing supporters’ violence as a form of contentious violence, four possible explanations are proposed: repression, media attention, unemployment and aggressive

  11. c-Myc Transforms Human Mammary Epithelial Cells through Repression of the Wnt Inhibitors DKK1 and SFRP1▿ †

    Science.gov (United States)

    Cowling, Victoria H.; D'Cruz, Celina M.; Chodosh, Lewis A.; Cole, Michael D.

    2007-01-01

    c-myc is frequently amplified in breast cancer; however, the mechanism of myc-induced mammary epithelial cell transformation has not been defined. We show that c-Myc induces a profound morphological transformation in human mammary epithelial cells and anchorage-independent growth. c-Myc suppresses the Wnt inhibitors DKK1 and SFRP1, and derepression of DKK1 or SFRP1 reduces Myc-dependent transforming activity. Myc-dependent repression of DKK1 and SFRP1 is accompanied by Wnt target gene activation and endogenous T-cell factor activity. Myc-induced mouse mammary tumors have repressed SFRP1 and increased expression of Wnt target genes. DKK1 and SFRP1 inhibit the transformed phenotype of breast cancer cell lines, and DKK1 inhibits tumor formation. We propose a positive feedback loop for activation of the c-myc and Wnt pathways in breast cancer. PMID:17485441

  12. Comment on "Multiple repressive mechanisms in the hippocampus during memory formation".

    Science.gov (United States)

    Mathew, Rebecca S; Mullan, Hillary; Blusztajn, Jan Krzysztof; Lehtinen, Maria K

    2016-07-29

    Cho et al. (Reports, 2 October 2015, p. 82) report that gene repression after contextual fear conditioning regulates hippocampal memory formation. We observe low levels of expression for many of the top candidate genes in the hippocampus and robust expression in the choroid plexus, as well as repression at 4 hours after contextual fear conditioning, suggesting the inclusion of choroid plexus messenger RNAs in Cho et al. hippocampal samples.

  13. Repression of insulin gene expression by adenovirus type 5 E1a proteins.

    OpenAIRE

    1987-01-01

    Insulin gene transcription relies on enhancer and promoter elements which are active in pancreatic beta cells. We showed that adenovirus type 5 infection of HIT T-15 cells, a transformed hamster beta cell line, represses insulin gene transcription and mRNA levels. Using expression plasmids transiently introduced into HIT T-15 cells, we showed that adenovirus type 5 E1a transcription regulatory proteins repress insulin enhancer-promoter element activity as assayed with a surrogate xanthine-gua...

  14. What is the function of nitrogen catabolite repression in Saccharomyces cerevisiae?

    OpenAIRE

    Cooper, T. G.; Sumrada, R A

    1983-01-01

    In contrast to the previously held notion that nitrogen catabolite repression is primarily responsible for the ability of yeast cells to use good nitrogen sources in preference to poor ones, we demonstrate that this ability is probably the result of other control mechanisms, such as metabolite compartmentation. We suggest that nitrogen repression is functionally a long-term adaptation to changes in the nutritional environment of yeast cells.

  15. Identification of novel secreted fatty acids that regulate nitrogen catabolite repression in fission yeast

    OpenAIRE

    Xiaoying Sun; Go Hirai; Masashi Ueki; Hiroshi Hirota; Qianqian Wang; Yayoi Hongo; Takemichi Nakamura; Yuki Hitora; Hidekazu Takahashi; Mikiko Sodeoka; Hiroyuki Osada; Makiko Hamamoto; Minoru Yoshida; Yoko Yashiroda

    2016-01-01

    Uptake of poor nitrogen sources such as branched-chain amino acids is repressed in the presence of high-quality nitrogen sources such as NH4 + and glutamate (Glu), which is called nitrogen catabolite repression. Amino acid auxotrophic mutants of the fission yeast Schizosaccharomyces pombe were unable to grow on minimal medium containing NH4Cl or Glu even when adequate amounts of required amino acids were supplied. However, growth of these mutant cells was recovered in the vicinity of colonies...

  16. Mechanisms of repression in dystopian science fiction: Fahrenheit 451 and Neuromancer

    OpenAIRE

    2015-01-01

    Louis Althusser who is a Marxist thinker argues the totalitarian state systems and how they govern the states by using Ideological and Repressive State Apparatuses. Ray Bradbury’s Fahrenheit 451 and William Gibson’s Neuromancer are two dystopian science fiction novels that discuss the oppression and repression of the state in technologically advanced societies. However, the citizens of the novels live in poor conditions and they have to obey the rules of the state and corporations in order...

  17. Symbiotic plasmid is required for NolR to fully repress nodulation genes in Rhizobium leguminosarum A34

    Institute of Scientific and Technical Information of China (English)

    Fengqing Li; Bihe Hou; Guofan Hong

    2008-01-01

    NolR is a reguiator of noduiation genes present in Rhizobium and Sinorhizobium. However, the mechanism by which NolR participates in the inducible transcription ofnoduiation genes remains unclear. To investigate whether there are other factors regulating the function of NoIR, an insertion mutant of NolR in Rhizobium leguminosarum strain 8401, which lacks the symbiotic plasmid, was constructed by homologous recombination. We investigated the effects of NolR inactivation on the expression of nodulation genes. Three inducible nodulation genes (nodA, nodF and nodM) were expressed constitutively in NoiR-mutant, MRl14. Our results suggested that the symbiotic plasmid is required for NolR to fully repress nodulation genes in Rhizobium ieguminosarum A34. In addition, MRl14 has provided a useful tool for further study of molecular interactions between NolR and other factors.

  18. MiR144/451 Expression Is Repressed by RUNX1 During Megakaryopoiesis and Disturbed by RUNX1/ETO.

    Directory of Open Access Journals (Sweden)

    Nicole Kohrs

    2016-03-01

    Full Text Available A network of lineage-specific transcription factors and microRNAs tightly regulates differentiation of hematopoietic stem cells along the distinct lineages. Deregulation of this regulatory network contributes to impaired lineage fidelity and leukemogenesis. We found that the hematopoietic master regulator RUNX1 controls the expression of certain microRNAs, of importance during erythroid/megakaryocytic differentiation. In particular, we show that the erythorid miR144/451 cluster is epigenetically repressed by RUNX1 during megakaryopoiesis. Furthermore, the leukemogenic RUNX1/ETO fusion protein transcriptionally represses the miR144/451 pre-microRNA. Thus RUNX1/ETO contributes to increased expression of miR451 target genes and interferes with normal gene expression during differentiation. Furthermore, we observed that inhibition of RUNX1/ETO in Kasumi1 cells and in RUNX1/ETO positive primary acute myeloid leukemia patient samples leads to up-regulation of miR144/451. RUNX1 thus emerges as a key regulator of a microRNA network, driving differentiation at the megakaryocytic/erythroid branching point. The network is disturbed by the leukemogenic RUNX1/ETO fusion product.

  19. Convergent repression of miR156 by sugar and the CDK8 module of Arabidopsis Mediator.

    Science.gov (United States)

    Buendía-Monreal, Manuel; Gillmor, C Stewart

    2017-03-01

    In Arabidopsis, leaves produced during the juvenile vegetative phase are simple, while adult leaves are morphologically complex. The juvenile to adult transition is regulated by miR156, a microRNA that promotes juvenility by impeding the function of SPL transcription factors, which specify adult leaf traits. Both leaf derived sugars, as well as the Mediator Cyclin Dependent Kinase 8 (CDK8) module genes CENTER CITY (CCT)/MED12 and GRAND CENTRAL (GCT)/MED13, act upstream of miR156 to promote the juvenile to adult transition. However, it is not known whether sugar, CCT and GCT repress miR156 independently, as part of the same pathway, or in a cooperative manner. Here we show that sugar treatment can repress MIR156 expression in the absence of CCT or GCT. Both cct and the photosynthetic mutant chlorina1 (ch1) (which decreases sugar synthesis) exhibit extended juvenile development and increased MIR156A and MIR156C expression. Compared to ch1 and cct single mutants, the ch1 cct double mutant has a stronger effect on juvenile leaf traits, higher MIR156C levels, and a dramatic increase in MIR156A. Our results show that sugar and the CDK8 module are capable of regulating MIR156 independently, but suggest they normally act together in a synergistic manner. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Inorganic arsenic represses interleukin-17A expression in human activated Th17 lymphocytes

    Energy Technology Data Exchange (ETDEWEB)

    Morzadec, Claudie; Macoch, Mélinda; Robineau, Marc; Sparfel, Lydie [UMR INSERM U1085, Institut de Recherche sur la Santé, l' Environnement et le Travail (IRSET), Université de Rennes 1, 2 avenue du Professeur Léon Bernard, 35043 Rennes (France); Fardel, Olivier [UMR INSERM U1085, Institut de Recherche sur la Santé, l' Environnement et le Travail (IRSET), Université de Rennes 1, 2 avenue du Professeur Léon Bernard, 35043 Rennes (France); Pôle Biologie, Centre Hospitalier Universitaire (CHU) Rennes, 2 rue Henri Le Guilloux, 35033 Rennes (France); Vernhet, Laurent, E-mail: laurent.vernhet@univ-rennes1.fr [UMR INSERM U1085, Institut de Recherche sur la Santé, l' Environnement et le Travail (IRSET), Université de Rennes 1, 2 avenue du Professeur Léon Bernard, 35043 Rennes (France)

    2012-08-01

    Trivalent inorganic arsenic [As(III)] is an efficient anticancer agent used to treat patients suffering from acute promyelocytic leukemia. Recently, experimental studies have clearly demonstrated that this metalloid can also cure lymphoproliferative and/or pro-inflammatory syndromes in different murine models of chronic immune-mediated diseases. T helper (Th) 1 and Th17 lymphocytes play a central role in development of these diseases, in mice and humans, especially by secreting the potent pro-inflammatory cytokine interferon-γ and IL-17A, respectively. As(III) impairs basic functions of human T cells but its ability to modulate secretion of pro-inflammatory cytokines by differentiated Th lymphocytes is unknown. In the present study, we demonstrate that As(III), used at concentrations clinically achievable in plasma of patients, has no effect on the secretion of interferon-γ from Th1 cells but almost totally blocks the expression and the release of IL-17A from human Th17 lymphocytes co-stimulated for five days with anti-CD3 and anti-CD28 antibodies, in the presence of differentiating cytokines. In addition, As(III) specifically reduces mRNA levels of the retinoic-related orphan receptor (ROR)C gene which encodes RORγt, a key transcription factor controlling optimal IL-17 expression in fully differentiated Th17 cells. The metalloid also blocks initial expression of IL-17 gene induced by the co-stimulation, probably in part by impairing activation of the JNK/c-Jun pathway. In conclusion, our results demonstrate that As(III) represses expression of the major pro-inflammatory cytokine IL-17A produced by human Th17 lymphocytes, thus strengthening the idea that As(III) may be useful to treat inflammatory immune-mediated diseases in humans. -- Highlights: ► Arsenic inhibits secretion of IL-17A from human naïve and memory Th17 lymphocytes. ► Arsenic represses early expression of IL-17A gene in human activated T lymphocytes. ► Arsenic interferes with activation of

  1. Carboxy terminal tail of polycystin-1 regulates localization of TSC2 to repress mTOR.

    Directory of Open Access Journals (Sweden)

    Ruhee Dere

    Full Text Available Autosomal dominant polycystic kidney disease (ADPKD is a commonly inherited renal disorder caused by defects in the PKD1 or PKD2 genes. ADPKD is associated with significant morbidity, and is a major underlying cause of end-stage renal failure (ESRF. Commonly, treatment options are limited to the management of hypertension, cardiovascular risk factors, dialysis, and transplantation when ESRF develops, although several new pharmacotherapies, including rapamycin, have shown early promise in animal and human studies. Evidence implicates polycystin-1 (PC-1, the gene product of the PKD1 gene, in regulation of the mTOR pathway. Here we demonstrate a mechanism by which the intracellular, carboxy-terminal tail of polycystin-1 (CP1 regulates mTOR signaling by altering the subcellular localization of the tuberous sclerosis complex 2 (TSC2 tumor suppressor, a gatekeeper for mTOR activity. Phosphorylation of TSC2 at S939 by AKT causes partitioning of TSC2 away from the membrane, its GAP target Rheb, and its activating partner TSC1 to the cytosol via 14-3-3 protein binding. We found that TSC2 and a C-terminal polycystin-1 peptide (CP1 directly interact and that a membrane-tethered CP1 protects TSC2 from AKT phosphorylation at S939, retaining TSC2 at the membrane to inhibit the mTOR pathway. CP1 decreased binding of 14-3-3 proteins to TSC2 and increased the interaction between TSC2 and its activating partner TSC1. Interestingly, while membrane tethering of CP1 was required to activate TSC2 and repress mTOR, the ability of CP1 to inhibit mTOR signaling did not require primary cilia and was independent of AMPK activation. These data identify a unique mechanism for modulation of TSC2 repression of mTOR signaling via membrane retention of this tumor suppressor, and identify PC-1 as a regulator of this downstream component of the PI3K signaling cascade.

  2. MicroRNA-125b promotes neuronal differentiation in human cells by repressing multiple targets.

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    Le, Minh T N; Xie, Huangming; Zhou, Beiyan; Chia, Poh Hui; Rizk, Pamela; Um, Moonkyoung; Udolph, Gerald; Yang, Henry; Lim, Bing; Lodish, Harvey F

    2009-10-01

    MicroRNAs (miRNAs) are a class of small noncoding RNAs that regulate gene expression at the posttranscriptional level. Research on miRNAs has highlighted their importance in neural development, but the specific functions of neurally enriched miRNAs remain poorly understood. We report here the expression profile of miRNAs during neuronal differentiation in the human neuroblastoma cell line SH-SY5Y. Six miRNAs were significantly upregulated during differentiation induced by all-trans-retinoic acid and brain-derived neurotrophic factor. We demonstrated that the ectopic expression of either miR-124a or miR-125b increases the percentage of differentiated SH-SY5Y cells with neurite outgrowth. Subsequently, we focused our functional analysis on miR-125b and demonstrated the important role of this miRNA in both the spontaneous and induced differentiations of SH-SH5Y cells. miR-125b is also upregulated during the differentiation of human neural progenitor ReNcell VM cells, and miR-125b ectopic expression significantly promotes the neurite outgrowth of these cells. To identify the targets of miR-125b regulation, we profiled the global changes in gene expression following miR-125b ectopic expression in SH-SY5Y cells. miR-125b represses 164 genes that contain the seed match sequence of the miRNA and/or that are predicted to be direct targets of miR-125b by conventional methods. Pathway analysis suggests that a subset of miR-125b-repressed targets antagonizes neuronal genes in several neurogenic pathways, thereby mediating the positive effect of miR-125b on neuronal differentiation. We have further validated the binding of miR-125b to the miRNA response elements of 10 selected mRNA targets. Together, we report here for the first time the important role of miR-125b in human neuronal differentiation.

  3. Evaluation of sgRNA target sites for CRISPR-mediated repression of TP53.

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    Ingrid E B Lawhorn

    Full Text Available The CRISPR (clustered regularly interspaced short palindromic repeats platform has been developed as a general method to direct proteins of interest to gene targets. While the native CRISPR system delivers a nuclease that cleaves and potentially mutates target genes, researchers have recently employed catalytically inactive CRISPR-associated 9 nuclease (dCas9 in order to target and repress genes without DNA cleavage or mutagenesis. With the intent of improving repression efficiency in mammalian cells, researchers have also fused dCas9 with a KRAB repressor domain. Here, we evaluated different genomic sgRNA targeting sites for repression of TP53. The sites spanned a 200-kb distance, which included the promoter, transcript sequence, and regions flanking the endogenous human TP53 gene. We showed that repression up to 86% can be achieved with dCas9 alone (i.e., without use of the KRAB domain by targeting the complex to sites near the TP53 transcriptional start site. This work demonstrates that efficient transcriptional repression of endogenous human genes can be achieved by the targeted delivery of dCas9. Yet, the efficiency of repression strongly depends on the choice of the sgRNA target site.

  4. Cooperative transcriptional repression by BCL6 and BACH2 in germinal center B-cell differentiation.

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    Huang, Chuanxin; Geng, Huimin; Boss, Isaac; Wang, Ling; Melnick, Ari

    2014-02-13

    The transcriptional repressors BCL6 and BACH2 are crucial regulators of germinal center (GC) B-cell fate, and are known to interact and repress transcription of PRDM1, a key driver of plasma cell differentiation. How these factors cooperate is not fully understood. Herein, we show that GC formation is only minimally impaired in Bcl6(+/-) or Bach2(+/-) mice, although double heterozygous Bcl6(+/-)Bach2(+/-) mice exhibit profound reduction in GC formation. Splenic B cells from Bcl6(+/-) Bach2(+/-) mice display accelerated plasmacytic differentiation and high expression of key plasma cell genes such as Prdm1, Xbp1, and CD138. Chromatin immunoprecipitation sequencing revealed that in B cells, BACH2 is mostly bound to genes together with its heterodimer partner MAFK. The BACH2-MAFK complex binds to sets of genes known to be involved in the GC response, 60% of which are also targets of BCL6. Approximately 30% of BACH2 peaks overlap with BCL6, including cis-regulatory sequences of the PRDM1 gene. BCL6 also modulates BACH2 protein stability and their protein levels are positively correlated in GC B cells. Therefore, BCL6 and BACH2 cooperate to orchestrate gene expression patterning in GC B cells through both transcriptional and biochemical mechanisms, which collectively determine the proper initiation and timing of terminal differentiation.

  5. Network of mutually repressive metastasis regulators can promote cell heterogeneity and metastatic transitions

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    Balazsi, Gabor; Kim, Eun-Jin; Rosner, Marsha

    2014-03-01

    The sources and consequences of nongenetic variability in metastatic progression are largely unknown. To address these questions, we characterize the transcriptional regulatory network around the metastasis suppressor Raf Kinase Inhibitory Protein (RKIP). It was previously shown that RKIP negatively regulates the transcription factor BACH1, which promotes breast cancer metastasis. Here we demonstrate that BACH1 acts in a double negative (overall positive) feedback loop to inhibit RKIP transcription in breast cancer cells. BACH1 also negatively regulates its own transcription. Analysis of the RKIP-BACH1 network reveals the existence of an inverse relationship between BACH1 and RKIP involving both monostable and bistable transitions between ``low BACH1, high RKIP'' and ``high BACH1, low RKIP'' cellular states that can potentially give rise to nongenetic variability. Single cell analysis confirmed the antagonistic relationship between RKIP and BACH1, and showed cell line-dependent signatures consistent with bistable behavior. Together, our results suggest that the mutually repressive relationship between metastatic regulators such as RKIP and BACH1 can play a key role in determining metastatic progression in cancer. This work was supported by NIH/NIGMS grant R01GM106027.

  6. IscR regulates RNase LS activity by repressing rnlA transcription.

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    Otsuka, Yuichi; Miki, Kumiko; Koga, Mitsunori; Katayama, Natsu; Morimoto, Wakako; Takahashi, Yasuhiro; Yonesaki, Tetsuro

    2010-07-01

    The Escherichia coli endoribonuclease LS was originally identified as a potential antagonist of bacteriophage T4. When the T4 dmd gene is defective, RNase LS cleaves T4 mRNAs and antagonizes T4 reproduction. This RNase also plays an important role in RNA metabolisms in E. coli. rnlA is an essential gene for RNase LS activity, but the transcriptional regulation of this gene remains to be elucidated. An Fe-S cluster protein, IscR, acts as a transcription factor and controls the expression of genes that are necessary for Fe-S cluster biogenesis. Here, we report that overexpression of IscR suppressed RNase LS activity, causing the loss of antagonist activity against phage T4. This suppressive effect did not require the ligation of Fe-S cluster into IscR. beta-Galactosidase reporter assays showed that transcription from an rnlA promoter increased in iscR-deleted cells compared to wild-type cells, and gel-mobility shift assays revealed specific binding of IscR to the rnlA promoter region. RT-PCR analysis demonstrated that endogenous rnlA mRNA was reduced by overexpression of IscR and increased by deletion of iscR. From these results, we conclude that IscR negatively regulates transcription of rnlA and represses RNase LS activity.

  7. SIRT7 Represses Myc Activity to Suppress ER Stress and Prevent Fatty Liver Disease

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    Jiyung Shin

    2013-11-01

    Full Text Available Nonalcoholic fatty liver disease is the most common chronic liver disorder in developed countries. Its pathogenesis is poorly understood, and therapeutic options are limited. Here, we show that SIRT7, an NAD+-dependent H3K18Ac deacetylase, functions at chromatin to suppress ER stress and prevent the development of fatty liver disease. SIRT7 is induced upon ER stress and is stabilized at the promoters of ribosomal proteins through its interaction with the transcription factor Myc to silence gene expression and to relieve ER stress. SIRT7-deficient mice develop chronic hepatosteatosis resembling human fatty liver disease. Myc inactivation or pharmacological suppression of ER stress alleviates fatty liver caused by SIRT7 deficiency. Importantly, SIRT7 suppresses ER stress and reverts the fatty liver disease in diet-induced obese mice. Our study identifies SIRT7 as a cofactor of Myc for transcriptional repression and delineates a druggable regulatory branch of the ER stress response that prevents and reverts fatty liver disease.

  8. Structure of the Arabidopsis TOPLESS corepressor provides insight into the evolution of transcriptional repression

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    Martin-Arevalillo, Raquel; Nanao, Max H.; Vinos-Poyo, Thomas; Mast, David; Galvan-Ampudia, Carlos; Brunoud, Géraldine; Dumas, Renaud

    2017-01-01

    Transcriptional repression involves a class of proteins called corepressors that link transcription factors to chromatin remodeling complexes. In plants such as Arabidopsis thaliana, the most prominent corepressor is TOPLESS (TPL), which plays a key role in hormone signaling and development. Here we present the crystallographic structure of the Arabidopsis TPL N-terminal region comprising the LisH and CTLH (C-terminal to LisH) domains and a newly identified third region, which corresponds to a CRA domain. Comparing the structure of TPL with the mammalian TBL1, which shares a similar domain structure and performs a parallel corepressor function, revealed that the plant TPLs have evolved a new tetramerization interface and unique and highly conserved surface for interaction with repressors. Using site-directed mutagenesis, we validated those surfaces in vitro and in vivo and showed that TPL tetramerization and repressor binding are interdependent. Our results illustrate how evolution used a common set of protein domains to create a diversity of corepressors, achieving similar properties with different molecular solutions. PMID:28698367

  9. PADI4 acts as a coactivator of Tal1 by counteracting repressive histone arginine methylation

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    Kolodziej, Stephan; Kuvardina, Olga N.; Oellerich, Thomas; Herglotz, Julia; Backert, Ingo; Kohrs, Nicole; Buscató, Estel. La; Wittmann, Sandra K.; Salinas-Riester, Gabriela; Bonig, Halvard; Karas, Michael; Serve, Hubert; Proschak, Ewgenij; Lausen, Jörn

    2014-05-01

    The transcription factor Tal1 is a critical activator or repressor of gene expression in hematopoiesis and leukaemia. The mechanism by which Tal1 differentially influences transcription of distinct genes is not fully understood. Here we show that Tal1 interacts with the peptidylarginine deiminase IV (PADI4). We demonstrate that PADI4 can act as an epigenetic coactivator through influencing H3R2me2a. At the Tal1/PADI4 target gene IL6ST the repressive H3R2me2a mark triggered by PRMT6 is counteracted by PADI4, which augments the active H3K4me3 mark and thus increases IL6ST expression. In contrast, at the CTCF promoter PADI4 acts as a repressor. We propose that the influence of PADI4 on IL6ST transcription plays a role in the control of IL6ST expression during lineage differentiation of hematopoietic stem/progenitor cells. These results open the possibility to pharmacologically influence Tal1 in leukaemia.

  10. Histone H4 lysine 20 acetylation is associated with gene repression in human cells

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    Kaimori, Jun-Ya; Maehara, Kazumitsu; Hayashi-Takanaka, Yoko; Harada, Akihito; Fukuda, Masafumi; Yamamoto, Satoko; Ichimaru, Naotsugu; Umehara, Takashi; Yokoyama, Shigeyuki; Matsuda, Ryo; Ikura, Tsuyoshi; Nagao, Koji; Obuse, Chikashi; Nozaki, Naohito; Takahara, Shiro; Takao, Toshifumi; Ohkawa, Yasuyuki; Kimura, Hiroshi; Isaka, Yoshitaka

    2016-01-01

    Histone acetylation is generally associated with gene activation and chromatin decondensation. Recent mass spectrometry analysis has revealed that histone H4 lysine 20, a major methylation site, can also be acetylated. To understand the function of H4 lysine 20 acetylation (H4K20ac), we have developed a specific monoclonal antibody and performed ChIP-seq analysis using HeLa-S3 cells. H4K20ac was enriched around the transcription start sites (TSSs) of minimally expressed genes and in the gene body of expressed genes, in contrast to most histone acetylation being enriched around the TSSs of expressed genes. The distribution of H4K20ac showed little correlation with known histone modifications, including histone H3 methylations. A motif search in H4K20ac-enriched sequences, together with transcription factor binding profiles based on ENCODE ChIP-seq data, revealed that most transcription activators are excluded from H4K20ac-enriched genes and a transcription repressor NRSF/REST co-localized with H4K20ac. These results suggest that H4K20ac is a unique acetylation mark associated with gene repression. PMID:27064113

  11. SIRT7 represses Myc activity to suppress ER stress and prevent fatty liver disease.

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    Shin, Jiyung; He, Ming; Liu, Yufei; Paredes, Silvana; Villanova, Lidia; Brown, Katharine; Qiu, Xiaolei; Nabavi, Noushin; Mohrin, Mary; Wojnoonski, Kathleen; Li, Patrick; Cheng, Hwei-Ling; Murphy, Andrew J; Valenzuela, David M; Luo, Hanzhi; Kapahi, Pankaj; Krauss, Ronald; Mostoslavsky, Raul; Yancopoulos, George D; Alt, Frederick W; Chua, Katrin F; Chen, Danica

    2013-11-14

    Nonalcoholic fatty liver disease is the most common chronic liver disorder in developed countries. Its pathogenesis is poorly understood, and therapeutic options are limited. Here, we show that SIRT7, an NAD(+)-dependent H3K18Ac deacetylase, functions at chromatin to suppress ER stress and prevent the development of fatty liver disease. SIRT7 is induced upon ER stress and is stabilized at the promoters of ribosomal proteins through its interaction with the transcription factor Myc to silence gene expression and to relieve ER stress. SIRT7-deficient mice develop chronic hepatosteatosis resembling human fatty liver disease. Myc inactivation or pharmacological suppression of ER stress alleviates fatty liver caused by SIRT7 deficiency. Importantly, SIRT7 suppresses ER stress and reverts the fatty liver disease in diet-induced obese mice. Our study identifies SIRT7 as a cofactor of Myc for transcriptional repression and delineates a druggable regulatory branch of the ER stress response that prevents and reverts fatty liver disease.

  12. Lateral gene expression in Drosophila early embryos is supported by Grainyhead-mediated activation and tiers of dorsally-localized repression.

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    Mayra Garcia

    Full Text Available The general consensus in the field is that limiting amounts of the transcription factor Dorsal establish dorsal boundaries of genes expressed along the dorsal-ventral (DV axis of early Drosophila embryos, while repressors establish ventral boundaries. Yet recent studies have provided evidence that repressors act to specify the dorsal boundary of intermediate neuroblasts defective (ind, a gene expressed in a stripe along the DV axis in lateral regions of the embryo. Here we show that a short 12 base pair sequence ("the A-box" present twice within the ind CRM is both necessary and sufficient to support transcriptional repression in dorsal regions of embryos. To identify binding factors, we conducted affinity chromatography using the A-box element and found a number of DNA-binding proteins and chromatin-associated factors using mass spectroscopy. Only Grainyhead (Grh, a CP2 transcription factor with a unique DNA-binding domain, was found to bind the A-box sequence. Our results suggest that Grh acts as an activator to support expression of ind, which was surprising as we identified this factor using an element that mediates dorsally-localized repression. Grh and Dorsal both contribute to ind transcriptional activation. However, another recent study found that the repressor Capicua (Cic also binds to the A-box sequence. While Cic was not identified through our A-box affinity chromatography, utilization of the same site, the A-box, by both factors Grh (activator and Cic (repressor may also support a "switch-like" response that helps to sharpen the ind dorsal boundary. Furthermore, our results also demonstrate that TGF-β signaling acts to refine ind CRM expression in an A-box independent manner in dorsal-most regions, suggesting that tiers of repression act in dorsal regions of the embryo.

  13. Lateral gene expression in Drosophila early embryos is supported by Grainyhead-mediated activation and tiers of dorsally-localized repression.

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    Garcia, Mayra; Stathopoulos, Angelike

    2011-01-01

    The general consensus in the field is that limiting amounts of the transcription factor Dorsal establish dorsal boundaries of genes expressed along the dorsal-ventral (DV) axis of early Drosophila embryos, while repressors establish ventral boundaries. Yet recent studies have provided evidence that repressors act to specify the dorsal boundary of intermediate neuroblasts defective (ind), a gene expressed in a stripe along the DV axis in lateral regions of the embryo. Here we show that a short 12 base pair sequence ("the A-box") present twice within the ind CRM is both necessary and sufficient to support transcriptional repression in dorsal regions of embryos. To identify binding factors, we conducted affinity chromatography using the A-box element and found a number of DNA-binding proteins and chromatin-associated factors using mass spectroscopy. Only Grainyhead (Grh), a CP2 transcription factor with a unique DNA-binding domain, was found to bind the A-box sequence. Our results suggest that Grh acts as an activator to support expression of ind, which was surprising as we identified this factor using an element that mediates dorsally-localized repression. Grh and Dorsal both contribute to ind transcriptional activation. However, another recent study found that the repressor Capicua (Cic) also binds to the A-box sequence. While Cic was not identified through our A-box affinity chromatography, utilization of the same site, the A-box, by both factors Grh (activator) and Cic (repressor) may also support a "switch-like" response that helps to sharpen the ind dorsal boundary. Furthermore, our results also demonstrate that TGF-β signaling acts to refine ind CRM expression in an A-box independent manner in dorsal-most regions, suggesting that tiers of repression act in dorsal regions of the embryo.

  14. Epoxide-mediated CifR repression of cif gene expression utilizes two binding sites in Pseudomonas aeruginosa.

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    Ballok, Alicia E; Bahl, Christopher D; Dolben, Emily L; Lindsay, Allia K; St Laurent, Jessica D; Hogan, Deborah A; Madden, Dean R; O'Toole, George A

    2012-10-01

    Pseudomonas aeruginosa secretes an epoxide hydrolase virulence factor that reduces the apical membrane expression of ABC transporters such as the cystic fibrosis transmembrane conductance regulator (CFTR). This virulence factor, named CFTR inhibitory factor (Cif), is regulated by a TetR-family, epoxide-responsive repressor known as CifR via direct binding and repression. We identified two sites of CifR binding in the intergenic space between cifR and morB, the first gene in the operon containing the cif gene. We have mapped these binding sites and found they are 27 bp in length, and they overlap the -10 and +1 sites of both the cifR and morB regulatory region and the start of transcription, respectively. In addition, we found that CifR binds to each repression site with differing affinity. Mutagenesis of these binding sites resulted in a loss of DNA binding in vitro, and mutation of one of these sites in vivo resulted in an increase in transcription of both the cif and cifR genes. We characterized cif and cifR gene expression in sputum and found that, whereas cif gene expression varied relative to an in vitro coculture control, cifR gene expression was consistently higher. Analysis of a longitudinal sample of CF isolates from nine patients revealed that Cif protein was expressed over time, although variably, and these changes could not be linked to mutations in the cifR gene or the promoters of these genes. Finally, we tested CifR responsiveness to other epoxides and showed that CifR can respond to multiple epoxides to various degrees.

  15. Natural memory beyond the storage model: Repression, trauma, and the construction of a personal past

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    Nikolai Axmacher

    2010-11-01

    Full Text Available Naturally occurring memory processes show features which are difficult to investigate by conventional cognitive neuroscience paradigms. Distortions of memory for problematic contents are described both by psychoanalysis (internal conflicts and research on post-traumatic stress disorder (external traumata. Typically, declarative memory for these contents is impaired – possibly due to repression in the case of internal conflicts or due to dissociation in the case of external traumata – but they continue to exert an unconscious pathological influence: neurotic symptoms or psychosomatic disorders after repression or flashbacks and intrusions in post-traumatic stress disorder after dissociation. Several experimental paradigms aim at investigating repression in healthy control subjects. We argue that these paradigms do not adequately operationalize the clinical process of repression, because they rely on an intentional inhibition of random stimuli (suppression. Furthermore, these paradigms ignore that memory distortions due to repression or dissociation are most accurately characterized by a lack of self-referential processing, resulting in an impaired integration of these contents into the self. This aspect of repression and dissociation cannot be captured by the concept of memory as a storage device which is usually employed in the cognitive neurosciences. It can only be assessed within the framework of a constructivist memory concept, according to which successful memory involves a reconstruction of experiences such that they fit into a representation of the self. We suggest several experimental paradigms that allow for the investigation of the neural correlates of repressed memories and trauma-induced memory distortions based on a constructivist memory concept.

  16. Genome-wide repression of eRNA and target gene loci by the ETV6-RUNX1 fusion in acute leukemia.

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    Teppo, Susanna; Laukkanen, Saara; Liuksiala, Thomas; Nordlund, Jessica; Oittinen, Mikko; Teittinen, Kaisa; Grönroos, Toni; St-Onge, Pascal; Sinnett, Daniel; Syvänen, Ann-Christine; Nykter, Matti; Viiri, Keijo; Heinäniemi, Merja; Lohi, Olli

    2016-11-01

    Approximately 20%-25% of childhood acute lymphoblastic leukemias carry the ETV6-RUNX1 (E/R) fusion gene, a fusion of two central hematopoietic transcription factors, ETV6 (TEL) and RUNX1 (AML1). Despite its prevalence, the exact genomic targets of E/R have remained elusive. We evaluated gene loci and enhancers targeted by E/R genome-wide in precursor B acute leukemia cells using global run-on sequencing (GRO-seq). We show that expression of the E/R fusion leads to widespread repression of RUNX1 motif-containing enhancers at its target gene loci. Moreover, multiple super-enhancers from the CD19(+)/CD20(+)-lineage were repressed, implicating a role in impediment of lineage commitment. In effect, the expression of several genes involved in B cell signaling and adhesion was down-regulated, and the repression depended on the wild-type DNA-binding Runt domain of RUNX1. We also identified a number of E/R-regulated annotated and de novo noncoding genes. The results provide a comprehensive genome-wide mapping between E/R-regulated key regulatory elements and genes in precursor B cell leukemia that disrupt normal B lymphopoiesis. © 2016 Teppo et al.; Published by Cold Spring Harbor Laboratory Press.

  17. mAM facilitates conversion by ESET of dimethyl to trimethyl lysine 9 of histone H3 to cause transcriptional repression.

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    Wang, Hengbin; An, Woojin; Cao, Ru; Xia, Li; Erdjument-Bromage, Hediye; Chatton, Bruno; Tempst, Paul; Roeder, Robert G; Zhang, Yi

    2003-08-01

    Methylation of histone tails plays an important role in chromatin structure and function. Previously, we reported that ESET/SETDB1 is a histone methyltransferase (HMTase). Here, we show that SETDB1 tightly associates with the human homolog of mAM, a murine ATFa-associated factor. Although recombinant ESET can methylate lysine 9 of histone H3 (H3-K9), its activity is severely compromised when compared to that of the ESET/mAM complex. mAM stimulates ESET enzymatic activity by increasing the Vmax and decreasing the Km. Importantly, mAM facilitates the ESET-dependent conversion of dimethyl H3-K9 to the trimethyl state both in vitro and in vivo. Chromatin-based transcription and ChIP analyses demonstrate that mAM enhances ESET-mediated transcriptional repression in a SAM-dependent manner, and this repression correlates with H3-K9 trimethylation at the promoter. Thus, our studies establish that promoter H3-K9 trimethylation is the cause of transcriptional repression and that mAM/hAM facilitates conversion of H3-K9 dimethyl to trimethyl by ESET/SETDB1.

  18. Retinoic acid represses CYP7A1 expression in human hepatocytes and HepG2 cells by FXR/RXR-dependent and independent mechanisms.

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    Cai, Shi-Ying; He, Hongwei; Nguyen, Trong; Mennone, Albert; Boyer, James L

    2010-08-01

    Cholesterol 7alpha-hydroxylase (CYP7A1) plays a key role in maintaining lipid and bile salt homeostasis as it is the rate-limiting enzyme converting cholesterol to bile acids. Deficiency of CYP7A1 leads to hyperlipidemia in man and mouse. Hyperlipidemia is often seen in patients when treated with high-dose retinoic acid (RA), but the molecular mechanisms remain elusive. Our present study revealed that CYP7A1 mRNA expression is greatly repressed by RA in both human hepatocytes and HepG2 cells where increased fibroblast growth factor 19 (FGF19) and small heterodimer partner (SHP) expressions were also observed, suggesting farnesoid X receptor (FXR) and retinoid X receptor (RXR) were activated. Promoter reporter assays demonstrate that all-trans RA (atRA) specifically activated FXR/RXR. However, detailed molecular analyses indicate that this activation is through RXR, whose ligand is 9-cis RA. Knocking down of FXR or RXRalpha by small interference RNA (siRNA) in human hepatocytes increased CYP7A1 basal expression, but the repressive effect of atRA persisted, suggesting there are also FXR/RXR-independent mechanisms mediating atRA repression of CYP7A1 expression. Chromatin immunoprecipitation (ChIP) assay and cell transfection results indicate that PGC-1alpha plays a role in the FXR/RXR-independent mechanism. Our findings may provide a potential explanation for hyperlipidemic side effects observed in some patients treated with high-dose RA.

  19. Mutations in the GW-repeat protein SUO reveal a developmental function for microRNA-mediated translational repression in Arabidopsis.

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    Yang, Li; Wu, Gang; Poethig, R Scott

    2012-01-03

    Plant microRNAs (miRNAs) typically mediate RNA cleavage, but examples of miRNA-mediated translational repression have also been reported. However, the functional significance of this latter process is unknown. We identified SUO in a screen for Arabidopsis mutations that increase the accumulation of the miR156-regulated gene SPL3. suo has a loss-of-function phenotype characteristic of plants with reduced Argonaute (AGO)1 activity. An analysis of RNA and protein levels in suo mutants demonstrated that this phenotype is a consequence of a defect in miRNA-mediated translational repression; the effect of suo on vegetative phase change is attributable to a reduction in miR156/miR157 activity. SUO encodes a large protein with N-terminal bromo-adjacent homology (BAH) and transcription elongation factor S-II (TFS2N) domains and two C-terminal GW (glycine and tryptophan) repeats. SUO is present in the nucleus, and colocalizes with the processing-body component DCP1 in the cytoplasm. Our results reveal that SOU is a component of the miRNA pathway in Arabidopsis and demonstrate that translational repression is a functionally important aspect of miRNA activity in plants.

  20. Repression of germline RNAi pathways in somatic cells by retinoblastoma pathway chromatin complexes.

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    Xiaoyun Wu

    Full Text Available The retinoblastoma (Rb tumor suppressor acts with a number of chromatin cofactors in a wide range of species to suppress cell proliferation. The Caenorhabditis elegans retinoblastoma gene and many of these cofactors, called synMuv B genes, were identified in genetic screens for cell lineage defects caused by growth factor misexpression. Mutations in many synMuv B genes, including lin-35/Rb, also cause somatic misexpression of the germline RNA processing P granules and enhanced RNAi. We show here that multiple small RNA components, including a set of germline-specific Argonaute genes, are misexpressed in the soma of many synMuv B mutant animals, revealing one node for enhanced RNAi. Distinct classes of synMuv B mutants differ in the subcellular architecture of their misexpressed P granules, their profile of misexpressed small RNA and P granule genes, as well as their enhancement of RNAi and the related silencing of transgenes. These differences define three classes of synMuv B genes, representing three chromatin complexes: a LIN-35/Rb-containing DRM core complex, a SUMO-recruited Mec complex, and a synMuv B heterochromatin complex, suggesting that intersecting chromatin pathways regulate the repression of small RNA and P granule genes in the soma and the potency of RNAi. Consistent with this, the DRM complex and the synMuv B heterochromatin complex were genetically additive and displayed distinct antagonistic interactions with the MES-4 histone methyltransferase and the MRG-1 chromodomain protein, two germline chromatin regulators required for the synMuv phenotype and the somatic misexpression of P granule components. Thus intersecting synMuv B chromatin pathways conspire with synMuv B suppressor chromatin factors to regulate the expression of small RNA pathway genes, which enables heightened RNAi response. Regulation of small RNA pathway genes by human retinoblastoma may also underlie its role as a tumor suppressor gene.

  1. HCV core protein represses the apoptosis and improves the autophagy of human hepatocytes

    Science.gov (United States)

    Liu, Changhong; Qu, Aihua; Han, Xiaochun; Wang, Yiguo

    2015-01-01

    Objectives: This study aims to investigate the influence on human hepatocytes apoptosis and autophagy by the hepatitis C virus (HCV) core protein. Methods: QSG-7701, a human-derived non-neoplastic liver cell line, was transfected with PIRES-core vector that was a eukaryotic vector to express HCV core protein. Fluorescence microscope was used to observe the changes of nuclei in apoptosis cells by Annex in V-FITC/PI double staining. Flow cytometry was applied to detect the rate of cell apoptosis. Western blotting was used to detect the expression of HCV core protein, transcription factor nuclear factor-kappa B (NF-κB), autophagic biomarker microtubule associated protein 1 light chain 3 (LC3), and Beclin-1. Results: The apoptosis rate was significantly lower (P < 0.05) in QSG7701/core group (transfected with PIRES-core vector, (1.34±0.07)%) than in QSG7701 group (no transfection, (2.35±0.11)%) and in QSG7701 QSG7701/pcDNA3.1 group (transfected with pcDNA3.1 vector, (2.58±0.1)%). NF-κB expression was up-expressed in QSG7701/core group than in QSG7701/pcDNA3.1 group and QSG7701 group (P < 0.05). LC3-II expression and Beclin-1 expression was significant higher in QSG7701/core group than in the QSG7701/pcDNA3.1 group and QSG7701 group (P < 0.05). Conclusion: HCV core protein can repress the apoptosis and improve the autophagy of QSG7701 through up-regulating NF-κB and Beclin-1 expression. PMID:26629077

  2. Deletion of fucose residues in plant N-glycans by repression of the GDP-mannose 4,6-dehydratase gene using virus-induced gene silencing and RNA interference.

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    Matsuo, Kouki; Matsumura, Takeshi

    2011-02-01

    Production of pharmaceutical glycoproteins in plants has many advantages in terms of safety and reduced costs. However, plant-produced glycoproteins have N-glycans with plant-specific sugar residues (core β-1,2-xylose and α-1,3-fucose) and a Lewis a (Le(a) ) epitope, i.e., Galβ(1-3)[Fucα(1-4)]GlcNAc. Because these sugar residues and glycan structures seemed to be immunogenic, several attempts have been made to delete them by repressing their respective glycosyltransferase genes. However, until date, such deletions have not been successful in completely eliminating the fucose residues. In this study, we simultaneously reduced the plant-specific core α-1,3-fucose and α-1,4-fucose residues in the Le(a) epitopes by repressing the Guanosine 5'-diphosphate (GDP)-D-mannose 4,6-dehydratase (GMD) gene, which is associated with GDP-L-fucose biosynthesis, in Nicotiana benthamiana plants. Repression of GMD was achieved using virus-induced gene silencing (VIGS) and RNA interference (RNAi). The proportion of fucose-free N-glycans found in total soluble protein from GMD gene-repressed plants increased by 80% and 95% following VIGS and RNAi, respectively, compared to wild-type plants. A small amount of putative galactose substitution in N-glycans from the NbGMD gene-repressed plants was observed, similar to what has been previously reported GMD-knockout Arabidopsis mutant. On the other hand, the recombinant mouse granulocyte-macrophage colony-stimulating factor (GM-CSF) with fucose-deleted N-glycans was successfully produced in NbGMD-RNAi transgenic N. benthamiana plants. Thus, repression of the GMD gene is thus very useful for deleting immunogenic total fucose residues and facilitating the production of pharmaceutical glycoproteins in plants.

  3. Ligand-dependent regulation of the activity of the orphan nuclear receptor, small heterodimer partner (SHP), in the repression of bile acid biosynthetic CYP7A1 and CYP8B1 genes.

    Science.gov (United States)

    Miao, Ji; Choi, Sung-E; Seok, Sun Mi; Yang, Linda; Zuercher, William J; Xu, Yong; Willson, Timothy M; Xu, H Eric; Kemper, Jongsook Kim

    2011-07-01

    Small heterodimer partner (SHP) plays important roles in diverse biological processes by directly interacting with transcription factors and inhibiting their activities. SHP has been designated an orphan nuclear receptor, but whether its activity can be modulated by ligands has been a long-standing question. Recently, retinoid-related molecules, including 4-[3-(1-adamantyl)-4-hydroxyphenyl]-3-chlorocinnamic acid (3Cl-AHPC), were shown to bind to SHP and enhance apoptosis. We have examined whether 3Cl-AHPC acts as an agonist and increases SHP activity in the repression of bile acid biosynthetic CYP7A1 and CYP8B1 genes and delineated the underlying mechanisms. Contrary to this expectation, micromolar concentrations of 3Cl-AHPC increased CYP7A1 expression but indirectly via p38 kinase signaling. Nanomolar concentrations, however, repressed CYP7A1 expression and decreased bile acid levels in HepG2 cells, and little repression was observed when SHP was down-regulated by small hairpin RNA. Mechanistic studies revealed that 3Cl-AHPC bound to SHP, increased the interaction of SHP with liver receptor homologue (LRH)-1, a hepatic activator for CYP7A1 and CYP8B1 genes, and with repressive cofactors, Brahma, mammalian Sin3a, and histone deacetylase-1, and, subsequently, increased the occupancy of SHP and these cofactors at the promoters. Mutation of Leu-100, predicted to contact 3Cl-AHPC within the SHP ligand binding pocket by molecular modeling, severely impaired the increased interaction with LRH-1, and repression of LRH-1 activity mediated by 3Cl-AHPC. 3Cl-AHPC repressed SHP metabolic target genes in a gene-specific manner in human primary hepatocytes and HepG2 cells. These data suggest that SHP may act as a ligand-regulated receptor in metabolic pathways. Modulation of SHP activity by synthetic ligands may be a useful therapeutic strategy.

  4. The MOX promoter in Hansenula polymorpha is ultrasensitive to glucose-mediated carbon catabolite repression.

    Science.gov (United States)

    Dusny, Christian; Schmid, Andreas

    2016-09-01

    Redesigning biology towards specific purposes requires a functional understanding of genetic circuits. We present a quantitative in-depth study on the regulation of the methanol-specific MOX promoter system (PMOX) at the single-cell level. We investigated PMOX regulation in the methylotrophic yeast Hansenula (Ogataea) polymorpha with respect to glucose-mediated carbon catabolite repression. This promoter system is particularly delicate as the glucose as carbon and energy source in turn represses MOX promoter activity. Decoupling single cells from population activity revealed a hitherto underrated ultrasensitivity of the MOX promoter to glucose repression. Environmental control with single-cell technologies enabled quantitative insights into the balance between activation and repression of PMOX with respect to extracellular glucose concentrations. While population-based studies suggested full MOX promoter derepression at extracellular glucose concentrations of ∼1 g L(-1), we showed that glucose-mediated catabolite repression already occurs at concentrations as low as 5 × 10(-4) g L(-1) These findings demonstrate the importance of uncoupling single cells from populations for understanding the mechanisms of promoter regulation in a quantitative manner.

  5. Lactose-mediated carbon catabolite repression of putrescine production in dairy Lactococcus lactis is strain dependent.

    Science.gov (United States)

    del Rio, Beatriz; Ladero, Victor; Redruello, Begoña; Linares, Daniel M; Fernández, Maria; Martín, Maria Cruz; Alvarez, Miguel A

    2015-06-01

    Lactococcus lactis is the lactic acid bacterial (LAB) species most widely used as a primary starter in the dairy industry. However, several strains of L. lactis produce the biogenic amine putrescine via the agmatine deiminase (AGDI) pathway. We previously reported the putrescine biosynthesis pathway in L. lactis subsp. cremoris GE2-14 to be regulated by carbon catabolic repression (CCR) via glucose but not lactose (Linares et al., 2013). The present study shows that both these sugars repress putrescine biosynthesis in L. lactis subsp. lactis T3/33, a strain isolated from a Spanish artisanal cheese. Furthermore, we demonstrated that both glucose and lactose repressed the transcriptional activity of the aguBDAC catabolic genes of the AGDI route. Finally, a screening performed in putrescine-producing dairy L. lactis strains determined that putrescine biosynthesis was repressed by lactose in all the L. lactis subsp. lactis strains tested, but in only one L. lactis subsp. cremoris strain. Given the obvious importance of the lactose-repression in cheese putrescine accumulation, it is advisable to consider the diversity of L. lactis in this sense and characterize consequently the starter cultures to select the safest strains.

  6. Obacunone Represses Salmonella Pathogenicity Islands 1 and 2 in an envZ-Dependent Fashion

    Science.gov (United States)

    Vikram, Amit; Jayaprakasha, Guddadarangavvanahally K.; Jesudhasan, Palmy R.

    2012-01-01

    Obacunone belongs to a class of unique triterpenoids called limonoids, present in Citrus species. Previous studies from our laboratory suggested that obacunone possesses antivirulence activity and demonstrates inhibition of cell-cell signaling in Vibrio harveyi and Escherichia coli O157:H7. The present work sought to determine the effect of obacunone on the food-borne pathogen Salmonella enterica serovar Typhimurium LT2 by using a cDNA microarray. Transcriptomic studies indicated that obacunone represses Salmonella pathogenicity island 1 (SPI1), the maltose transporter, and the hydrogenase operon. Furthermore, phenotypic data for the Caco-2 infection assay and maltose utilization were in agreement with microarray data suggesting repression of SPI1 and maltose transport. Further studies demonstrated that repression of SPI1 was plausibly mediated through hilA. Additionally, obacunone seems to repress SPI2 under SPI2-inducing conditions as well as in Caco-2 infection models. Furthermore, obacunone seems to repress hilA in an EnvZ-dependent fashion. Altogether, the results of the study seems to suggest that obacunone exerts an antivirulence effect on S. Typhimurium and may serve as a lead compound for development of antivirulence strategies for S. Typhimurium. PMID:22843534

  7. Stability of XIST repression in relation to genomic imprinting following global genome demethylation in a human cell line

    OpenAIRE

    E.S.S. de Araújo; Vasques, L.R.; Stabellini,R.; A.C.V. Krepischi; Pereira, L.V.

    2014-01-01

    DNA methylation is essential in X chromosome inactivation and genomic imprinting, maintaining repression of XIST in the active X chromosome and monoallelic repression of imprinted genes. Disruption of the DNA methyltransferase genes DNMT1 and DNMT3B in the HCT116 cell line (DKO cells) leads to global DNA hypomethylation and biallelic expression of the imprinted gene IGF2 but does not lead to reactivation of XIST expression, suggesting thatXIST repression is due to a more stable epigenetic mar...

  8. Molecular analysis of the interaction between the hematopoietic master transcription factors GATA-1 and PU.1

    DEFF Research Database (Denmark)

    Liew, Chu Wai; Rand, Kasper Dyrberg; Simpson, Raina J Y

    2006-01-01

    GATA-1 and PU.1 are transcription factors that control erythroid and myeloid development, respectively. The two proteins have been shown to function in an antagonistic fashion, with GATA-1 repressing PU.1 activity during erythropoiesis and PU.1 repressing GATA-1 function during myelopoiesis. It h...

  9. Fasting-Induced FGF21 Is Repressed by LXR Activation via Recruitment of an HDAC3 Corepressor Complex in Mice

    Science.gov (United States)

    Archer, Amena; Venteclef, Nicolas; Mode, Agneta; Pedrelli, Matteo; Gabbi, Chiara; Clément, Karine; Parini, Paolo; Gustafsson, Jan-Åke

    2012-01-01

    The liver plays a pivotal role in the physiological adaptation to fasting and a better understanding of the metabolic adaptive responses may give hints on new therapeutic strategies to control the metabolic diseases. The liver X receptors (LXRs) are well-established regulators of lipid and glucose metabolism. More recently fibroblast growth factor 21 (FGF21) has emerged as an important regulator of energy homeostasis. We hypothesized that the LXR transcription factors could influence Fgf21 expression, which is induced in response to fasting. Wild-type, LXRα−/−, and LXRβ−/− mice were treated for 3 d with vehicle or the LXR agonist GW3965 and fasted for 12 h prior to the killing of the animals. Interestingly, serum FGF21 levels were induced after fasting, but this increase was blunted when the mice were treated with GW3965 independently of genotypes. Compared with wild-type mice, GW3965-treated LXRα−/− and LXRβ−/− mice showed improved insulin sensitivity and enhanced ketogenic response at fasting. Of note is that during fasting, GW3965 treatment tended to reduce liver triglycerides as opposed to the effect of the agonist in the fed state. The LXR-dependent repression of Fgf21 seems to be mainly mediated by the recruitment of LXRβ onto the Fgf21 promoter upon GW3965 treatment. This repression by LXRβ occurs through the recruitment and stabilization of the repressor complex composed of retinoid-related orphan receptor-α/Rev-Erbα/histone deacetylase 3 onto the Fgf21 promoter. Our data clearly demonstrate that there is a cross talk between the LXR and FGF21 signaling pathways in the adaptive response to fasting. PMID:23073827

  10. Repression of a potassium channel by nuclear hormone receptor and TGF-β signaling modulates insulin signaling in Caenorhabditis elegans.

    Directory of Open Access Journals (Sweden)

    Donha Park

    Full Text Available Transforming growth factor β (TGF-β signaling acts through Smad proteins to play fundamental roles in cell proliferation, differentiation, apoptosis, and metabolism. The Receptor associated Smads (R-Smads interact with DNA and other nuclear proteins to regulate target gene transcription. Here, we demonstrate that the Caenorhabditis elegans R-Smad DAF-8 partners with the nuclear hormone receptor NHR-69, a C. elegans ortholog of mammalian hepatocyte nuclear factor 4α HNF4α, to repress the exp-2 potassium channel gene and increase insulin secretion. We find that NHR-69 associates with DAF-8 both in vivo and in vitro. Functionally, daf-8 nhr-69 double mutants show defects in neuropeptide secretion and phenotypes consistent with reduced insulin signaling such as increased expression of the sod-3 and gst-10 genes and a longer life span. Expression of the exp-2 gene, encoding a voltage-gated potassium channel, is synergistically increased in daf-8 nhr-69 mutants compared to single mutants and wild-type worms. In turn, exp-2 acts selectively in the ASI neurons to repress the secretion of the insulin-like peptide DAF-28. Importantly, exp-2 mutation shortens the long life span of daf-8 nhr-69 double mutants, demonstrating that exp-2 is required downstream of DAF-8 and NHR-69. Finally, animals over-expressing NHR-69 specifically in DAF-28-secreting ASI neurons exhibit a lethargic, hypoglycemic phenotype that is rescued by exogenous glucose. We propose a model whereby DAF-8/R-Smad and NHR-69 negatively regulate the transcription of exp-2 to promote neuronal DAF-28 secretion, thus demonstrating a physiological crosstalk between TGF-β and HNF4α-like signaling in C. elegans. NHR-69 and DAF-8 dependent regulation of exp-2 and DAF-28 also provides a novel molecular mechanism that contributes to the previously recognized link between insulin and TGF-β signaling in C. elegans.

  11. In Vitro Repression of Transcription of the Trytophan Operon by trp Repressor

    Science.gov (United States)

    Shimizu, Yoshiko; Shimizu, Nobuyoshi; Hayashi, Masaki

    1973-01-01

    The in vitro repression of transcription of the tryptophan operon by the trp repressor from Escherichia coli was studied. By measuring the inhibitory effect for trp-specific RNA synthesis in an in vitro transcription system directed by DNA of trp-transducing phage, we have detected and concentrated a trp repressor in an eluate of a Φ80 ptED native DNA-cellulose column. The repression of transcription of trp operon required the addition of L-tryptophan in the system, and when several tryptophan analogues were added, the repression or derepression was similar to that observed in vivo. The repressor fraction was separated from the majority of tryptophanyl-tRNA synthetase activity by Bio-gel P60 column chromatography. PMID:4579009

  12. Alleviation of glucose repression of maltose metabolism by MIG1 disruption in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Klein, Christopher; Olsson, Lisbeth; Rønnow, B.

    1996-01-01

    The MIG1 gene was disrupted in a haploid laboratory strain (B224) and in an industrial polyploid strain (DGI 342) of Saccharomyces cerevisiae. The alleviation of glucose repression of the expression of MAL genes and alleviation of glucose control of maltose metabolism were investigated in batch...... cultivations on glucose-maltose mixtures. In the MIG1-disrupted haploid strain, glucose repression was partly alleviated; i.e., maltose metabolism was initiated at higher glucose concentrations than in the corresponding wild-type strain. In contrast, the polyploid Delta mig1 strain exhibited an even more...... of glucose repression of the SUC genes. The disruption of MIG1 was shown to bring about pleiotropic effects, manifested in changes in the pattern of secreted metabolites and in the specific growth rate....

  13. A transient reversal of miRNA-mediated repression controls macrophage activation.

    Science.gov (United States)

    Mazumder, Anup; Bose, Mainak; Chakraborty, Abhijit; Chakrabarti, Saikat; Bhattacharyya, Suvendra N

    2013-11-01

    In mammalian macrophages, the expression of a number of cytokines is regulated by miRNAs. Upon macrophage activation, proinflammatory cytokine mRNAs are translated, although the expression of miRNAs targeting these mRNAs remains largely unaltered. We show that there is a transient reversal of miRNA-mediated repression during the early phase of the inflammatory response in macrophages, which leads to the protection of cytokine mRNAs from miRNA-mediated repression. This derepression occurs through Ago2 phosphorylation, which results in its impaired binding to miRNAs and to the corresponding target mRNAs. Macrophages expressing a mutant, non-phosphorylatable AGO2--which remains bound to miRNAs during macrophage activation--have a weakened inflammatory response and fail to prevent parasite invasion. These findings highlight the relevance of the transient relief of miRNA repression for macrophage function.

  14. Overcome of Carbon Catabolite Repression of Bioinsecticides Production by Sporeless Bacillus thuringiensis through Adequate Fermentation Technology.

    Science.gov (United States)

    Ben Khedher, Saoussen; Jaoua, Samir; Zouari, Nabil

    2014-01-01

    The overcoming of catabolite repression, in bioinsecticides production by sporeless Bacillus thuringiensis strain S22 was investigated into fully controlled 3 L fermenter, using glucose based medium. When applying adequate oxygen profile throughout the fermentation period (75% oxygen saturation), it was possible to partially overcome the catabolite repression, normally occurring at high initial glucose concentrations (30 and 40 g/L glucose). Moreover, toxin production yield by sporeless strain S22 was markedly improved by the adoption of the fed-batch intermittent cultures technology. With 22.5 g/L glucose used into culture medium, toxin production was improved by about 36% when applying fed-batch culture compared to one batch. Consequently, the proposed fed-batch strategy was efficient for the overcome of the carbon catabolite repression. So, it was possible to overproduce insecticidal crystal proteins into highly concentrated medium.

  15. Overcome of Carbon Catabolite Repression of Bioinsecticides Production by Sporeless Bacillus thuringiensis through Adequate Fermentation Technology

    Directory of Open Access Journals (Sweden)

    Saoussen Ben Khedher

    2014-01-01

    Full Text Available The overcoming of catabolite repression, in bioinsecticides production by sporeless Bacillus thuringiensis strain S22 was investigated into fully controlled 3 L fermenter, using glucose based medium. When applying adequate oxygen profile throughout the fermentation period (75% oxygen saturation, it was possible to partially overcome the catabolite repression, normally occurring at high initial glucose concentrations (30 and 40 g/L glucose. Moreover, toxin production yield by sporeless strain S22 was markedly improved by the adoption of the fed-batch intermittent cultures technology. With 22.5 g/L glucose used into culture medium, toxin production was improved by about 36% when applying fed-batch culture compared to one batch. Consequently, the proposed fed-batch strategy was efficient for the overcome of the carbon catabolite repression. So, it was possible to overproduce insecticidal crystal proteins into highly concentrated medium.

  16. An Introduction to CRISPR Technology for Genome Activation and Repression in Mammalian Cells.

    Science.gov (United States)

    Du, Dan; Qi, Lei S

    2016-01-04

    CRISPR interference/activation (CRISPRi/a) technology provides a simple and efficient approach for targeted repression or activation of gene expression in the mammalian genome. It is highly flexible and programmable, using an RNA-guided nuclease-deficient Cas9 (dCas9) protein fused with transcriptional regulators for targeting specific genes to effect their regulation. Multiple studies have shown how this method is an effective way to achieve efficient and specific transcriptional repression or activation of single or multiple genes. Sustained transcriptional modulation can be obtained by stable expression of CRISPR components, which enables directed reprogramming of cell fate. Here, we introduce the basics of CRISPRi/a technology for genome repression or activation.

  17. Dopamine signaling leads to loss of Polycomb repression and aberrant gene activation in experimental parkinsonism.

    Directory of Open Access Journals (Sweden)

    Erik Södersten

    2014-09-01

    Full Text Available Polycomb group (PcG proteins bind to and repress genes in embryonic stem cells through lineage commitment to the terminal differentiated state. PcG repressed genes are commonly characterized by the presence of the epigenetic histone mark H3K27me3, catalyzed by the Polycomb repressive complex 2. Here, we present in vivo evidence for a previously unrecognized plasticity of PcG-repressed genes in terminally differentiated brain neurons of parkisonian mice. We show that acute administration of the dopamine precursor, L-DOPA, induces a remarkable increase in H3K27me3S28 phosphorylation. The induction of the H3K27me3S28p histone mark specifically occurs in medium spiny neurons expressing dopamine D1 receptors and is dependent on Msk1 kinase activity and DARPP-32-mediated inhibition of protein phosphatase-1. Chromatin immunoprecipitation (ChIP experiments showed that increased H3K27me3S28p was accompanied by reduced PcG binding to regulatory regions of genes. An analysis of the genome wide distribution of L-DOPA-induced H3K27me3S28 phosphorylation by ChIP sequencing (ChIP-seq in combination with expression analysis by RNA-sequencing (RNA-seq showed that the induction of H3K27me3S28p correlated with increased expression of a subset of PcG repressed genes. We found that induction of H3K27me3S28p persisted during chronic L-DOPA administration to parkisonian mice and correlated with aberrant gene expression. We propose that dopaminergic transmission can activate PcG repressed genes in the adult brain and thereby contribute to long-term maladaptive responses including the motor complications, or dyskinesia, caused by prolonged administration of L-DOPA in Parkinson's disease.

  18. Tumstatin transfected into human glioma cell line U251 represses tumor growth by inhibiting angiogenesis

    Institute of Scientific and Technical Information of China (English)

    YE Hong-xing; YAO Yu; JIANG Xin-jun; YUAN Xian-rui

    2013-01-01

    Background Angiogenesis is a prerequisite for tumor growth and plays an important role in rapidly growing tumors,such as malignant gliomas.A variety of factors controlling the angiogenic balance have been described,and among these,the endogenous inhibitor of angiogenesis,tumstatin,has drawn considerable attention.The current study investigated whether expression of tumstatin by glioma cells could alter this balance and prevent tumor formation.Methods We engineered stable transfectants from human glioma cell line U251 to constitutively secrete a human tumstatin protein with c-myc and polyhistidine tags.Production and secretion of the tumstatin-c-myc-His fusion protein by tumstatin-transfected cells were confirmed by Western blotting analysis.In the present study,we identify the anti-angiogenic capacity of tumstatin using several in vitro and in vivo assays.Student's t-test and one-way analysis of variance (ANOVA) test were used to determine the statistical significance in this study.Results The tumstatin transfectants and control transfectants (stably transfected with a control plasmid) had similar in vitro growth rates compared to their parental cell lines.However,the conditioned medium from the tumstatin transfected tumor cells significantly inhibits proliferation and causes apoptosis of endothelial cells.It also inhibits tube formation of endothelial cells on Matrigel.Examination of armpit tumors arising from cells overexpressing tumstatin repress the growth of tumor,accompanying the decreased density of CD31 positive vessels in tumors ((5.62±1.32)/HP),compared to the control-transfectants group ((23.84+1.71)/HP) and wild type U251 glioma cells group ((29.33+4.45)/HP).Conclusion Anti-angiogenic gene therapy using human tumstatin gene may be an effective strategy for the treatment of glioma.

  19. Ribbon regulates morphogenesis of the Drosophila embryonic salivary gland through transcriptional activation and repression.

    Science.gov (United States)

    Loganathan, Rajprasad; Lee, Joslynn S; Wells, Michael B; Grevengoed, Elizabeth; Slattery, Matthew; Andrew, Deborah J

    2016-01-01

    Transcription factors affect spatiotemporal patterns of gene expression often regulating multiple aspects of tissue morphogenesis, including cell-type specification, cell proliferation, cell death, cell polarity, cell shape, cell arrangement and cell migration. In this work, we describe a distinct role for Ribbon (Rib) in controlling cell shape/volume increases during elongation of the Drosophila salivary gland (SG). Notably, the morphogenetic changes in rib mutants occurred without effects on general SG cell attributes such as specification, proliferation and apoptosis. Moreover, the changes in cell shape/volume in rib mutants occurred without compromising epithelial-specific morphological attributes such as apicobasal polarity and junctional integrity. To identify the genes regulated by Rib, we performed ChIP-seq analysis in embryos driving expression of GFP-tagged Rib specifically in the SGs. To learn if the Rib binding sites identified in the ChIP-seq analysis were linked to changes in gene expression, we performed microarray analysis comparing RNA samples from age-matched wild-type and rib null embryos. From the superposed ChIP-seq and microarray gene expression data, we identified 60 genomic sites bound by Rib likely to regulate SG-specific gene expression. We confirmed several of the identified Rib targets by qRT-pCR and/or in situ hybridization. Our results indicate that Rib regulates cell growth and tissue shape in the Drosophila salivary gland via a diverse array of targets through both transcriptional activation and repression. Furthermore, our results suggest that autoregulation of rib expression may be a key component of the SG morphogenetic gene network.

  20. PINCH1 is transcriptional regulator in podocytes that interacts with WT1 and represses podocalyxin expression.

    Directory of Open Access Journals (Sweden)

    Dan Wang

    Full Text Available BACKGROUND: PINCH1, an adaptor protein containing five LIM domains, plays an important role in regulating the integrin-mediated cell adhesion, migration and epithelial-mesenchymal transition. PINCH1 is induced in the fibrotic kidney after injury, and it primarily localizes at the sites of focal adhesion. Whether it can translocate to the nucleus and directly participate in gene regulation is completely unknown. METHODOLOGY/PRINCIPAL FINDINGS: Using cultured glomerular podocytes as a model system, we show that PINCH1 expression was induced by TGF-β1, a fibrogenic cytokine that promotes podocyte dysfunction. Interestingly, increased PINCH1 not only localized at the sites of focal adhesions, but also underwent nuclear translocation after TGF-β1 stimulation. This nuclear translocation of PINCH1 was apparently dependent on the putative nuclear export/localization signals (NES/NLS at its C-terminus, as deletion or site-directed mutations abolished its nuclear shuttling. Co-immunoprecipitation and pull-down experiments revealed that PINCH1 interacted with Wilms tumor 1 protein (WT1, a nuclear transcription factor that is essential for regulating podocyte-specific gene expression in adult kidney. Interaction of PINCH1 and WT1 was mediated by the LIM1 domain of PINCH1 and C-terminal zinc-finger domain of WT1, which led to the suppression of the WT1-mediated podocalyxin expression in podocytes. PINCH1 also repressed podocalyxin gene transcription in a promoter-luciferase reporter assay. CONCLUSION/SIGNIFICANCE: These results indicate that PINCH1 can shuttle into the nucleus from cytoplasm in podocytes, wherein it interacts with WT1 and suppresses podocyte-specific gene expression. Our studies reveal a previously unrecognized, novel function of PINCH1, in which it acts as a transcriptional regulator through controlling specific gene expression.

  1. Salidroside alleviates paraquat-induced rat acute lung injury by repressing TGF-β1 expression

    Science.gov (United States)

    Zhang, Zhuoyi; Ding, Limin; Wu, Liqun; Xu, Liying; Zheng, Lanzhi; Huang, Xiaomin

    2014-01-01

    Objective: This study was designed to investigate the protective effects of salidroside (SDS) via suppressing the expression of transforming growth factor-β1 (TGF-β1) in rat acute lung injury (ALI) induced by paraquat (PQ) and to explore the potential molecular mechanisms. Methods: A total of 90 male rats (190-210 g) were randomly and evenly divided into 9 groups: control group, PQ groups (4 groups), and PQ + SDS groups (4 groups). The rats in control group were treated with equal volume of saline intraperitoneally. The rats in PQ groups were exposed to PQ solution (20 mg/kg) by gastric gavage for 1, 6, 24, and 72 hours, respectively. The rats in PQ + SDS groups were intraperitoneally injected once with SDS (10 mg/kg) every 12 hours after PQ perfusion. Pulmonary pathological changes were observed by hematoxylin and eosin (HE) staining. The expression of TGF-β1 and the mRNA were evaluated by immunohistochemical (IHC) scoring and real time quantitative reverse transcription polymerase chain reaction (real-time qRT-PCR), respectively. Results: SDS alleviated the symptoms of PQ induced ALI. Moreover, SDS reduced the expression of the inflammatory cytokine TGF-β1 including TGF-β1 IHC scores (at each time point from 6 to 72 hours after PQ perfusion) and mRNA level (at each time point from 1 to 72 hours after PQ perfusion) compared with PQ groups (P < 0.05). Conclusion: SDS alleviated the pulmonary symptoms of PQ-induced ALI, at least partially, by repressing inflammatory cell infiltration and the expression of TGF-β1 resulting in delayed lung fibrosis. PMID:25674253

  2. Bisbenzamidine derivative, pentamidine represses DNA damage response through inhibition of histone H2A acetylation

    Directory of Open Access Journals (Sweden)

    Ohba Reiko

    2010-02-01

    Full Text Available Abstract Background MRE11 is an important nuclease which functions in the end-resection step of homologous recombination (HR repair of DNA double-strand breaks (DSBs. As MRE11-deficient ATLD cells exhibit hyper radio-sensitivity and impaired DSB repair, MRE11 inhibitors could possibly function as potent radio-sensitizers. Therefore, we investigated whether a bisbenzamidine derivative, pentamidine, which can inhibit endoexonuclease activity, might influence DSB-induced damage responses via inhibition of MRE11. Results We first clarified that pentamidine inhibited MRE11 nuclease activity and also reduced ATM kinase activity in vitro. Pentamidine increased the radio-sensitivity of HeLa cells, suggesting that this compound could possibly influence DNA damage response factors in vivo. Indeed, we found that pentamidine reduced the accumulation of γ-H2AX, NBS1 and phospho-ATM at the sites of DSBs. Furthermore, pentamidine decreased HR activity in vivo. Pentamidine was found to inhibit the acetylation of histone H2A which could contribute both to inhibition of IR-induced focus formation and HR repair. These results suggest that pentamidine might exert its effects by inhibiting histone acetyltransferases. We found that pentamidine repressed the activity of Tip60 acetyltransferase which is known to acetylate histone H2A and that knockdown of Tip60 by siRNA reduced HR activity. Conclusion These results indicate that inhibition of Tip60 as well as hMRE11 nuclease by pentamidine underlies the radiosensitizing effects of this compound making it an excellent sensitizer for radiotherapy or chemotherapy.

  3. Repressive BMP2 gene regulatory elements near the BMP2 promoter

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Shan [Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry (UMDNJ), New Jersey Medical School (NJMS), Newark, NJ (United States); Chandler, Ronald L. [Department of Molecular Physiology and Biophysics, Center for Human Genetics Research, Vanderbilt University School of Medicine, Nashville, TN (United States); Fritz, David T. [Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry (UMDNJ), New Jersey Medical School (NJMS), Newark, NJ (United States); Mortlock, Douglas P. [Department of Molecular Physiology and Biophysics, Center for Human Genetics Research, Vanderbilt University School of Medicine, Nashville, TN (United States); Rogers, Melissa B., E-mail: rogersmb@umdnj.edu [Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry (UMDNJ), New Jersey Medical School (NJMS), Newark, NJ (United States)

    2010-02-05

    The level of bone morphogenetic protein 2 (BMP2) profoundly influences essential cell behaviors such as proliferation, differentiation, apoptosis, and migration. The spatial and temporal pattern of BMP2 synthesis, particular in diverse embryonic cells, is highly varied and dynamic. We have identified GC-rich sequences within the BMP2 promoter region that strongly repress gene expression. These elements block the activity of a highly conserved, osteoblast enhancer in response to FGF2 treatment. Both positive and negative gene regulatory elements control BMP2 synthesis. Detecting and mapping the repressive motifs is essential because they impede the identification of developmentally regulated enhancers necessary for normal BMP2 patterns and concentration.

  4. The Dialectic of Repression. Michel Foucault and the Birth of Penal Institutions

    Directory of Open Access Journals (Sweden)

    Alessandro Pandolfi

    2016-12-01

    Full Text Available The essay aims to highlight the role of the repression in the course taught by Michel Foucault at the Collège de France Théories et institutions pénales of 1971-1972 and in the texts in which, during the same years, Foucault elaborates the genealogy of the modern penal system. During the 1971-72 course Foucault represents repression as a political device that beside the use of violence, simultaneously brings into play new tactics, new relationships, new balance of power, and above all, anticipates the institutions and the fundamental practices criminal law of modernity.

  5. Small RNAs Repress Expression of Polysaccharide Utilization Loci of Gut Bacteroides Species.

    Science.gov (United States)

    Comstock, Laurie E

    2016-09-15

    Bacteroides species can metabolize numerous plant polysaccharides and host glycans present in the mammalian gut. The regulatory systems governing the induction of particular polysaccharide utilization loci when the cognate glycan is present are known, but how expression is repressed when a higher-priority glycan is present is largely unknown. In this issue of the Journal of Bacteriology, Cao et al. (J. Bacteriol. 198:2410-2418, 2016, http://dx.doi.org/10.1128/JB.00381-16) reveal a conserved mechanism in Bacteroides whereby antisense small RNAs (sRNA) repress expression of genes involved in utilization of host glycans. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  6. Engineering of carbon catabolite repression in recombinant xylose fermenting Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Roca, Christophe Francois Aime; Haack, Martin Brian; Olsson, Lisbeth

    2004-01-01

    Two xylose-fermenting glucose-derepressed Saccharomyces cerevisiae strains were constructed in order to investigate the influence of carbon catabolite repression on xylose metabolism. S. cerevisiae CPB.CR2 (Deltamig1, XYL1, XYL2, XKS1) and CPB.MBH2 (Deltamig1, Deltamig2, XYL1, XYL2, XKS1) were...... of CPB.CR2, where the cells are assumed to grow under non-repressive conditions as they sense almost no glucose, invertase activity was lower during growth on xylose and glucose than on glucose only. The 3-fold reduction in invertase activity could only be attributed to the presence of xylose, suggesting...

  7. The proto-oncoprotein KR-POK represses transcriptional activation of CDKN1A by MIZ-1 through competitive binding.

    Science.gov (United States)

    Lee, K M; Choi, W I; Koh, D I; Kim, Y J; Jeon, B N; Yoon, J H; Lee, C E; Kim, S H; Oh, J; Hur, M W

    2012-03-15

    The BTB/POZ family of proteins has been implicated in multiple biological processes, including tumourigenesis, DNA damage responses and cell cycle progression and development. MIZ-1 (Myc-interacting zinc-finger protein 1) is known to activate transcription of CDKN1A. We recently found that a kidney cancer-related POK transcription factor, KR-POK, is highly expressed in kidney, brain and bone marrow cancer tissues and is a potential proto-oncoprotein. Mouse Kr-pok represses transcription of the CDKN1A by acting on the proximal promoter. The BiFC/FRET assay, co-immunoprecipitation and glutathione S-transferase-fusion protein pull-down assay indicate that MIZ-1 and Kr-pok interact via their POZ domains. Oligoucleotide pull-down assays and chromatin immunoprecipitation assays revealed that MIZ-1 binds to the proximal GC-box#3 (bp, -55 to -63) and the MIZ-1-binding elements, MRE-A (bp, -90 to -64) and MRE-B (bp, -27 to -17). Interestingly, MIZ-1 also binds to the distal p53-binding elements. Kr-pok binds to the proximal GC-box#1 (bp, -95 to -100) and #3 (bp, -55 to -63) relatively strongly. It also shows weak binding to the MREs and the distal p53-binding elements. Kr-pok competes with MIZ-1 in binding to these elements and represses transcription by inhibiting MIZ-1/p300 recruitment, which decreases the acetylation of histones H3 and H4. Our data indicate that Kr-pok stimulates cell proliferation by interfering with the function of MIZ-1 in CDKN1A gene transcription using a mechanism that is radically different from other MIZ-1-interacting proteins, such as B-cell lymphoma 6, c-Myc and Gfi-1.

  8. Downregulation of protein tyrosine phosphatase PTP-BL represses adipogenesis.

    NARCIS (Netherlands)

    Glondu-Lassis, M.; Dromard, M.; Chavey, C.; Puech, C.; Fajas, L.; Hendriks, W.J.A.J.; Freiss, G.

    2009-01-01

    The insulin/insulin-like growth factor 1 (IGF-1) signaling pathway is a major regulator of adipose tissue growth and differentiation. We recently demonstrated that human protein tyrosine phosphatase (PTP) L1, a large cytoplasmic phosphatase also known as PTP-BAS/PTPN13/PTP-1E, is a negative

  9. Life in the cold: a proteomic study of cold-repressed proteins in the antarctic bacterium pseudoalteromonas haloplanktis TAC125.

    Science.gov (United States)

    Piette, Florence; D'Amico, Salvino; Mazzucchelli, Gabriel; Danchin, Antoine; Leprince, Pierre; Feller, Georges

    2011-06-01

    The proteomes expressed at 4°C and 18°C by the psychrophilic Antarctic bacterium Pseudoalteromonas haloplanktis were compared using two-dimensional differential in-gel electrophoresis with special reference to proteins repressed by low temperatures. Remarkably, the major cold-repressed proteins, almost undetectable at 4°C, were heat shock proteins involved in folding assistance.

  10. Associations between repression, general maladjustment, body weight, and body shape in older males : The normative aging study

    NARCIS (Netherlands)

    Niaura, RS; Stroud, LR; Todaro, J; Ward, KD; Spiro, A; Aldwin, C; Landsberg, L; Weiss, ST

    2003-01-01

    We examined relationships between repression, general maladjustment, body mass index (BMI), and waist-to-hip ratio (WHR). The participants were 1,081 healthy older men from the Normative Aging Study. Repression and General Maladjustment Scales of the Minnesota Multiphasic Personality Inventory were

  11. Trichostatin A enhances estrogen receptor-alpha repression in MCF-7 breast cancer cells under hypoxia

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Hyunggyun; Park, Joonwoo; Shim, Myeongguk; Lee, YoungJoo, E-mail: yjlee@sejong.ac.kr

    2016-02-12

    Estrogen receptor (ER) is a crucial determinant of resistance to endocrine therapy, which may change during the progression of breast cancer. We previously showed that hypoxia induces ESR1 gene repression and ERα protein degradation via proteasome-mediated pathway in breast cancer cells. HDAC plays important roles in the regulation of histone and non-histone protein post-translational modification. HDAC inhibitors can induce epigenetic changes and have therapeutic potential for targeting various cancers. Trichostatin A exerts potent antitumor activities against breast cancer cells in vitro and in vivo. In this report, we show that TSA augments ESR1 gene repression at the transcriptional level and downregulates ERα protein expression under hypoxic conditions through a proteasome-mediated pathway. TSA-induced estrogen response element-driven reporter activity in the absence of estrogen was synergistically enhanced under hypoxia; however, TSA inhibited cell proliferation under both normoxia and hypoxia. Our data show that the hypoxia-induced repression of ESR1 and degradation of ERα are enhanced by concomitant treatment with TSA. These findings expand our understanding of hormone responsiveness in the tumor microenvironment; however, additional in-depth studies are required to elucidate the detailed mechanisms of TSA-induced ERα regulation under hypoxia. - Highlights: • TSA augments ESR1 gene repression at the transcriptional level under hypoxia. • TSA downregulates ERα protein expression under hypoxia. • TSA-induced ERα regulation under hypoxia is essential for understanding the behavior and progression of breast cancer.

  12. Financial Repression as a Policy Choice: The Case of Ukraine, 1992—2000

    Directory of Open Access Journals (Sweden)

    Robert S. Kravchuk

    2004-10-01

    Full Text Available By their nature, instruments of financial repression distort interest rates, foreign exchange rates, patterns of investment, and the economic incentives of both borrowers and lenders. In order to deal with the economic pathologies introduced by the government’s own credit and financial policies, governments inevitably find that they must intervene further, to ration credit and impose controls, generally on prices, wages, interest rates, foreign exchange rates and other transactions. Not only did Ukraine exhibit all of the symptoms of financial repression in the 1990s, but the basic policy instruments of financial repression also became too familiar in Ukraine. In fact, to one extent or another, in the 1990s Ukraine employed several of these measures (often in combination as means to suppress the effects of excessive amounts of state consumption, the resultant inflation, and its own credit policies. In the long run, economic growth will suffer, however, because repression reduces the capacity of the financial system to respond to the needs of firms and households in the real economy.

  13. Gene Silencing Triggers Polycomb Repressive Complex 2 Recruitment to CpG Islands Genome Wide

    DEFF Research Database (Denmark)

    Riising, Eva Madi; Vacher-Comet, Itys; Leblanc, Benjamin Olivier;

    2014-01-01

    Polycomb group (PcG) proteins are required for normal differentiation and development and are frequently deregulated in cancer. PcG proteins are involved in gene silencing; however, their role in initiation and maintenance of transcriptional repression is not well defined. Here, we show that knoc...

  14. I-mfa domain proteins specifically interact with HTLV-1 Tax and repress its transactivating functions

    Energy Technology Data Exchange (ETDEWEB)

    Kusano, Shuichi, E-mail: skusano@m2.kufm.kagoshima-u.ac.jp [Division of Persistent and Oncogenic Viruses, Center for Chronic Viral Diseases, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima 890-8544 (Japan); Yoshimitsu, Makoto; Hachiman, Miho [Division of Hematology and Immunology, Center for Chronic Viral Diseases, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima 890-8544 (Japan); Ikeda, Masanori [Division of Persistent and Oncogenic Viruses, Center for Chronic Viral Diseases, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima 890-8544 (Japan)

    2015-12-15

    The I-mfa domain proteins HIC (also known as MDFIC) and I-mfa (also known as MDFI) are candidate tumor suppressor genes that are involved in cellular and viral transcriptional regulation. Here, we show that HIC and I-mfa directly interact with human T-cell leukemia virus type-1 (HTLV-1) Tax protein in vitro. In addition, HIC and I-mfa repress Tax-dependent transactivation of an HTLV-1 long terminal repeat (LTR) reporter construct in COS-1, Jurkat and high-Tax-producing HTLV-1-infected T cells. HIC also interacts with Tax through its I-mfa domain in vivo and represses Tax-dependent transactivation of HTLV-1 LTR and NF-κB reporter constructs in an interaction-dependent manner. Furthermore, we show that HIC decreases the nuclear distribution and stimulates the proteasomal degradation of Tax. These data reveal that HIC specifically interacts with HTLV-1 Tax and negatively regulates Tax transactivational activity by altering its subcellular distribution and stability. - Highlights: • I-mfa domain proteins, HIC and I-mfa, specifically interact with HTLV-1 Tax. • HIC and I-mfa repress the Tax-dependent transactivation of HTLV-1 LTR. • HIC represses the Tax-dependent transactivation of NF-κΒ. • HIC decreases the nuclear distribution of Tax. • HIC stimulates the proteasomal degradation of Tax.

  15. The natural product peiminine represses colorectal carcinoma tumor growth by inducing autophagic cell death

    Energy Technology Data Exchange (ETDEWEB)

    Lyu, Qing [School of Life Sciences, Tsinghua University, Beijing, 100084 (China); Key Lab in Healthy Science and Technology, Division of Life Science, Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055 (China); Tou, Fangfang [Jiangxi Provincial Key Lab of Oncology Translation Medicine, Jiangxi Cancer Hospital, Nanchang, 330029 (China); Su, Hong; Wu, Xiaoyong [First Affiliated Hospital, Guiyang College of Traditional Chinese Medicine, Guiyang, 550002 (China); Chen, Xinyi [Department of Hematology and Oncology, Beijing University of Chinese Medicine, Beijing, 100029 (China); Zheng, Zhi, E-mail: zheng_sheva@hotmail.com [Jiangxi Provincial Key Lab of Oncology Translation Medicine, Jiangxi Cancer Hospital, Nanchang, 330029 (China)

    2015-06-19

    Autophagy is evolutionarily conservative in eukaryotic cells that engulf cellular long-lived proteins and organelles, and it degrades the contents through fusion with lysosomes, via which the cell acquires recycled building blocks for the synthesis of new molecules. In this study, we revealed that peiminine induces cell death and enhances autophagic flux in colorectal carcinoma HCT-116 cells. We determined that peiminine enhances the autophagic flux by repressing the phosphorylation of mTOR through inhibiting upstream signals. Knocking down ATG5 greatly reduced the peiminine-induced cell death in wild-type HCT-116 cells, while treating Bax/Bak-deficient cells with peiminine resulted in significant cell death. In summary, our discoveries demonstrated that peiminine represses colorectal carcinoma cell proliferation and cell growth by inducing autophagic cell death. - Highlights: • Peiminine induces autophagy and upregulates autophagic flux. • Peiminine represses colorectal carcinoma tumor growth. • Peiminine induces autophagic cell death. • Peiminine represses mTOR phosphorylation by influencing PI3K/Akt and AMPK pathway.

  16. Sleep paralysis in adults reporting repressed, recovered, or continuous memories of childhood sexual abuse.

    Science.gov (United States)

    McNally, Richard J; Clancy, Susan A

    2005-01-01

    Sleep paralysis typically occurs as individuals awaken from rapid eye movement sleep before motor paralysis wanes. Many episodes are accompanied by tactile and visual hallucinations, often of threatening intruders in the bedroom. Pendergrast [Victims of Memory: Incest Accusations and Shattered Lives, HarperCollins, London, 1996] proposed that individuals who report repressed or recovered memories of childhood sexual abuse (CSA) may misinterpret episodes of sleep paralysis as reemerging fragments of dissociated ("repressed") memories of CSA. To investigate this issue, we administered a sleep paralysis questionnaire to people reporting either repressed (n = 18), recovered (n = 14), or continuous (n = 36) memories of CSA, or to a control group reporting no history of CSA (n = 16). The prevalence of sleep paralysis was: repressed memory group (44%), recovered memory group (43%), continuous memory group (47%), and control group (13%). Among the six individuals in the recovered memory group who had experienced sleep paralysis, one interpreted it as related to sexual abuse (i.e., a rate of 17%). All other participants who had reported sleep paralysis embraced other interpretations (e.g., saw a ghost). Dissociation and depressive symptoms were more common among those who had experienced sleep paralysis than among those who denied having experienced it.

  17. Personality and Psychopathology in African Unaccompanied Refugee Minors: Repression, Resilience and Vulnerability

    Science.gov (United States)

    Huemer, Julia; Volkl-Kernstock, Sabine; Karnik, Niranjan; Denny, Katherine G.; Granditsch, Elisabeth; Mitterer, Michaela; Humphreys, Keith; Plattner, Belinda; Friedrich, Max; Shaw, Richard J.; Steiner, Hans

    2013-01-01

    Examining personality and psychopathological symptoms among unaccompanied refugee minors (URMs), we measured intra-individual dimensions (repression and correlates thereof) usually associated with resilience. Forty-one URMs completed the Weinberger Adjustment Inventory (WAI), assessing personality, and the Youth Self-Report (YSR), describing…

  18. Bullying the media : Cultural and climato-economic readings of press repression versus press freedom

    NARCIS (Netherlands)

    Van de Vliert, E.

    Journalists and media assistants in many places are murdered, imprisoned, censored, threatened, and similarly harrassed. Here I document that, and explain why, there are three climato-economic niches of press repression versus press freedom as part of broader syndromes of national culture. A

  19. Repressive Adaptive Style and Self-Reported Psychological Functioning in Adolescent Cancer Survivors

    Science.gov (United States)

    Erickson, Sarah J.; Gerstle, Melissa; Montague, Erica Q.

    2008-01-01

    Low levels of posttraumatic stress disorder (PTSD), posttraumatic stress symptoms (PTSS), and psychosocial distress have been reported in pediatric cancer survivors. One explanation is the relatively high prevalence of the repressive adaptive style (low distress, high restraint) in this population. We investigated the relationship between this…

  20. The tumor suppressor, parafibromin, mediates histone H3 K9 methylation for cyclin D1 repression.

    Science.gov (United States)

    Yang, Yong-Jin; Han, Jeung-Whan; Youn, Hong-Duk; Cho, Eun-Jung

    2010-01-01

    Parafibromin, a component of the RNA polymerase II-associated PAF1 complex, is a tumor suppressor linked to hyperparathyroidism-jaw tumor syndrome and sporadic parathyroid carcinoma. Parafibromin induces cell cycle arrest by repressing cyclin D1 via an unknown mechanism. Here, we show that parafibromin interacts with the histone methyltransferase, SUV39H1, and functions as a transcriptional repressor. The central region (128-227 amino acids) of parafibromin is important for both the interaction with SUV39H1 and transcriptional repression. Parafibromin associated with the promoter and coding regions of cyclin D1 and was required for the recruitment of SUV39H1 and the induction of H3 K9 methylation but not H3 K4 methylation. RNA interference analysis showed that SUV39H1 was critical for cyclin D1 repression. These data suggest that parafibromin plays an unexpected role as a repressor in addition to its widely known activity associated with transcriptional activation. Parafibromin as a part of the PAF1 complex might downregulate cyclin D1 expression by integrating repressive H3 K9 methylation during transcription.

  1. Functional conservation of a glucose-repressible amylase gene promoter from Drosophila virilis in Drosophila melanogaster.

    Science.gov (United States)

    Magoulas, C; Loverre-Chyurlia, A; Abukashawa, S; Bally-Cuif, L; Hickey, D A

    1993-03-01

    Previous studies have demonstrated that the expression of the alpha-amylase gene is repressed by dietary glucose in Drosophila melanogaster. Here, we show that the alpha-amylase gene of a distantly related species, D. virilis, is also subject to glucose repression. Moreover, the cloned amylase gene of D. virilis is shown to be glucose repressible when it is transiently expressed in D. melanogaster larvae. This cross-species, functional conservation is mediated by a 330-bp promoter region of the D. virilis amylase gene. These results indicate that the promoter elements required for glucose repression are conserved between distantly related Drosophila species. A sequence comparison between the amylase genes of D. virilis and D. melanogaster shows that the promoter sequences diverge to a much greater degree than the coding sequences. The amylase promoters of the two species do, however, share small clusters of sequence similarity, suggesting that these conserved cis-acting elements are sufficient to control the glucose-regulated expression of the amylase gene in the genus Drosophila.

  2. Epigenetic repression of male gametophyte-specific genes in the Arabidopsis sporophyte

    DEFF Research Database (Denmark)

    Hoffmann, Robert D; Palmgren, Michael Broberg

    2013-01-01

    -regulated in the sporophyte has yet to be established. In this study, we have performed a bioinformatics analysis of publicly available genome-wide epigenetics data of several sporophytic tissues. By combining this analysis with DNase I footprinting data, we assessed means by which the repression of pollen-specific genes...

  3. Direct Repression of Evening Genes by CIRCADIAN CLOCK-ASSOCIATED1 in the Arabidopsis Circadian Clock.

    Science.gov (United States)

    Kamioka, Mari; Takao, Saori; Suzuki, Takamasa; Taki, Kyomi; Higashiyama, Tetsuya; Kinoshita, Toshinori; Nakamichi, Norihito

    2016-03-01

    The circadian clock is a biological timekeeping system that provides organisms with the ability to adapt to day-night cycles. Timing of the expression of four members of the Arabidopsis thaliana PSEUDO-RESPONSE REGULATOR(PRR) family is crucial for proper clock function, and transcriptional control of PRRs remains incompletely defined. Here, we demonstrate that direct regulation of PRR5 by CIRCADIAN CLOCK-ASSOCIATED1 (CCA1) determines the repression state of PRR5 in the morning. Chromatin immunoprecipitation followed by deep sequencing (ChIP-seq) analyses indicated that CCA1 associates with three separate regions upstream of PRR5 CCA1 and its homolog LATE ELONGATED HYPOCOTYL (LHY) suppressed PRR5 promoter activity in a transient assay. The regions bound by CCA1 in the PRR5 promoter gave rhythmic patterns with troughs in the morning, when CCA1 and LHY are at high levels. Furthermore,ChIP-seq revealed that CCA1 associates with at least 449 loci with 863 adjacent genes. Importantly, this gene set contains genes that are repressed but upregulated incca1 lhy double mutants in the morning. This study shows that direct binding by CCA1 in the morning provides strong repression of PRR5, and repression by CCA1 also temporally regulates an evening-expressed gene set that includes PRR5. © 2016 American Society of Plant Biologists. All rights reserved.

  4. Clinical Characteristics of Adults Reporting Repressed, Recovered, or Continuous Memories of Childhood Sexual Abuse

    Science.gov (United States)

    McNally, Richard J.; Perlman, Carol A.; Ristuccia, Carel S.; Clancy, Susan A.

    2006-01-01

    The authors assessed women and men who either reported continuous memories of their childhood sexual abuse (CSA, n = 92), reported recovering memories of CSA (n = 38), reported believing they harbored repressed memories of CSA (n = 42), or reported never having been sexually abused (n = 36). Men and women were indistinguishable on all clinical and…

  5. The neuronal repellent SLIT2 is a target for repression by EZH2 in prostate cancer.

    Science.gov (United States)

    Yu, J; Cao, Q; Yu, J; Wu, L; Dallol, A; Li, J; Chen, G; Grasso, C; Cao, X; Lonigro, R J; Varambally, S; Mehra, R; Palanisamy, N; Wu, J Y; Latif, F; Chinnaiyan, A M

    2010-09-30

    The neuronal repellent SLIT2 is repressed in a number of cancer types primarily through promoter hypermethylation. SLIT2, however, has not been studied in prostate cancer. Through genome-wide location analysis we identified SLIT2 as a target of polycomb group (PcG) protein EZH2. The EZH2-containing polycomb repressive complexes bound to the SLIT2 promoter inhibiting its expression. SLIT2 was downregulated in a majority of metastatic prostate tumors, showing a negative correlation with EZH2. This repressed expression could be restored by methylation inhibitors or EZH2-suppressing compounds. In addition, a low level of SLIT2 expression was associated with aggressive prostate, breast and lung cancers. Functional assays showed that SLIT2 inhibited prostate cancer cell proliferation and invasion. Thus, this study showed for the first time the epigenetic silencing of SLIT2 in prostate tumors, and supported SLIT2 as a potential biomarker for aggressive solid tumors. Importantly, PcG-mediated repression may serve as a precursor for the silencing of SLIT2 by DNA methylation in cancer.

  6. Epigenetic repression of male gametophyte-specific genes in the Arabidopsis sporophyte

    DEFF Research Database (Denmark)

    Hoffmann, Robert D; Palmgren, Michael Broberg

    2013-01-01

    -regulated in the sporophyte has yet to be established. In this study, we have performed a bioinformatics analysis of publicly available genome-wide epigenetics data of several sporophytic tissues. By combining this analysis with DNase I footprinting data, we assessed means by which the repression of pollen-specific genes...

  7. Repression of mesodermal fate by foxa, a key endoderm regulator of the sea urchin embryo.

    Science.gov (United States)

    Oliveri, Paola; Walton, Katherine D; Davidson, Eric H; McClay, David R

    2006-11-01

    The foxa gene is an integral component of the endoderm specification subcircuit of the endomesoderm gene regulatory network in the Strongylocentrotus purpuratus embryo. Its transcripts become confined to veg2, then veg1 endodermal territories, and, following gastrulation, throughout the gut. It is also expressed in the stomodeal ectoderm. gatae and otx genes provide input into the pregastrular regulatory system of foxa, and Foxa represses its own transcription, resulting in an oscillatory temporal expression profile. Here, we report three separate essential functions of the foxa gene: it represses mesodermal fate in the veg2 endomesoderm; it is required in postgastrular development for the expression of gut-specific genes; and it is necessary for stomodaeum formation. If its expression is reduced by a morpholino, more endomesoderm cells become pigment and other mesenchymal cell types, less gut is specified, and the larva has no mouth. Experiments in which blastomere transplantation is combined with foxa MASO treatment demonstrate that, in the normal endoderm, a crucial role of Foxa is to repress gcm expression in response to a Notch signal, and hence to repress mesodermal fate. Chimeric recombination experiments in which veg2, veg1 or ectoderm cells contained foxa MASO show which region of foxa expression controls each of the three functions. These experiments show that the foxa gene is a component of three distinct embryonic gene regulatory networks.

  8. Decitabine represses osteoclastogenesis through inhibition of RANK and NF-κB.

    Science.gov (United States)

    Guan, Hanfeng; Mi, Baoguo; Li, Yong; Wu, Wei; Tan, Peng; Fang, Zhong; Li, Jing; Zhang, Yong; Li, Feng

    2015-05-01

    DNA methylation is essential for maintenance of stable repression of gene transcription during differentiation and tumorigenesis. Demethylating reagents including decitabine could release the repression, leading to perturbed transcription program. Recently others and we showed that, in B cell lymphomas, decitabine repressed B cell specific gene transcription and activated NF-κB signaling, causing decreased expression of translocated oncogenes including MYC and attenuated tumor cell proliferation. During osteoclastogenesis, changes in DNA methylation occurred in numerous genes, implicating important roles for DNA methylation in osteoclastogenesis. In the present study, we found that decitabine inhibited osteoclastogenesis. The inhibitory effect could be at least partially attributed to reduced expression of multiple osteoclast specific genes including RANK by decitabine. Moreover, decitabine inhibited activity of NF-κB, AP-1 and extracellular signal-regulated kinase (ERK), but not PI3K/Akt pathway. In vivo, using ovariectomized mouse as a model, we observed that decitabine reduced the osteoclast activity and bone loss. In conclusion, our findings demonstrated that decitabine was an inhibitor of osteoclastogenesis by repression of osteoclast specific transcription program including the RANK, NF-κB and AP-1 pathways. DNA methylation might be indispensable for osteoclastogenesis. The use of decitabine could represent a novel strategy in treatment of diseases associated with increased osteoclast activity.

  9. Osterix represses adipogenesis by negatively regulating PPARγ transcriptional activity

    OpenAIRE

    Younho Han; Chae Yul Kim; Heesun Cheong; Kwang Youl Lee

    2016-01-01

    Osterix is a novel bone-related transcription factor involved in osteoblast differentiation, and bone maturation. Because a reciprocal relationship exists between adipocyte and osteoblast differentiation of bone marrow derived mesenchymal stem cells, we hypothesized that Osterix might have a role in adipogenesis. Ablation of Osterix enhanced adipogenesis in 3T3-L1 cells, whereas overexpression suppressed this process and inhibited the expression of adipogenic markers including CCAAT/enhancer-...

  10. From classical psychodynamics to evidence synthesis: the motif of repression and a contemporary understanding of a key mediatory mechanism in psychosis.

    Science.gov (United States)

    Fleming, Mick P; Martin, Colin R

    2012-06-01

    The stress vulnerability model has proven to be a politically important model for two reasons. It has provided the framework that defines a temporal and dynamic process whereby a person's uniquely determined biopsychosocial vulnerability to schizophrenia symptoms interacts with his or her capacity to manage stress and the amount and type of stress experienced in such a way that the person experiences schizophrenia symptoms. Second, the development of this framework promoted the notion of inherited and acquired vulnerability. Implicit was that vulnerability was individually determined and that there was a role for psychosocial factors in the development/maintenance of schizophrenia symptoms. This proved to be a catalyst for the development of studies implicating psychosocial factors in the etiology of schizophrenia symptoms. Studies derived from cognitive-behavioral theories have proven the most successful in identifying thinking patterns, emotional disturbances, and neurocognitive and defensive vulnerability factors inherent in the development of schizophrenia symptoms. Historically, within the psychoanalytic school there has been debate regarding the role of repressive coping mechanisms in schizophrenia development. Psychoanalytic theories have always appeared incapable of providing etiologic explanations of schizophrenia symptoms, with the possible exception of Melanie Klein, than other more salient psychosocial schools. Mechanisms within the process of repressive coping are consistent with evidence and mechanisms supporting the stress vulnerability models and existing cognitive-behavioral theories regarding development of paranoid delusions. These mechanisms are less consistent with social cognitive explanations of schizophrenia symptoms.

  11. Resveratrol Protects against TNF-α-Induced Injury in Human Umbilical Endothelial Cells through Promoting Sirtuin-1-Induced Repression of NF-KB and p38 MAPK.

    Directory of Open Access Journals (Sweden)

    Wei Pan

    Full Text Available Inflammation and reactive oxygen species (ROS play important roles in the pathogenesis of atherosclerosis. Resveratrol has been shown to possess anti-inflammatory and antioxidative stress activities, but the underlying mechanisms are not fully understood. In the present study, we investigated the molecular basis associated with the protective effects of resveratrol on tumor necrosis factor-alpha (TNF-α-induced injury in human umbilical endothelial cells (HUVECs using a variety of approaches including a cell viability assay, reverse transcription and quantitative polymerase chain reaction, western blot, and immunofluorescence staining. We showed that TNF-α induced CD40 expression and ROS production in cultured HUVECs, which were attenuated by resveratrol treatment. Also, resveratrol increased the expression of sirtuin 1 (SIRT1; and repression of SIRT1 by small-interfering RNA (siRNA and the SIRT1 inhibitor Ex527 reduced the inhibitory effects of resveratrol on CD40 expression and ROS generation. In addition, resveratrol downregulated the levels of p65 and phospho-p38 MAPK, but this inhibitory effect was attenuated by the suppression of SIRT1 activity. Moreover, the p38 MAPK inhibitor SD203580 and the nuclear factor (NF-κB inhibitor pyrrolidine dithiocarbamate (PDTC achieved similar repressive effects as resveratrol on TNF-α-induced ROS generation and CD40 expression. Thus, our study provides a mechanistic link between resveratrol and the activation of SIRT1, the latter of which is involved in resveratrol-mediated repression of the p38 MAPK/NF-κB pathway and ROS production in TNF-α-treated HUVECs.

  12. Induced ATF-2 represses CDK4 transcription through dimerization with JunD inhibiting intestinal epithelial cell growth after polyamine depletion.

    Science.gov (United States)

    Xiao, Lan; Rao, Jaladanki N; Zou, Tongtong; Liu, Lan; Yu, Ting-Xi; Zhu, Xiao-Yu; Donahue, James M; Wang, Jian-Ying

    2010-05-01

    Intestinal epithelium is a rapidly self-renewing tissue in the body, and its homeostasis is tightly regulated by numerous factors including polyamines. Decreased levels of cellular polyamines increase activating transcription factor (ATF)-2, but the exact role and mechanism of induced ATF-2 in the regulation of intestinal epithelial cell (IEC) growth remain elusive. Cyclin-dependent kinase (CDK) 4 is necessary for the G1-to-S phase transition during the cell cycle, and its expression is predominantly controlled at the transcription level. Here, we reported that induced ATF-2 following polyamine depletion repressed CDK4 gene transcription in IECs by increasing formation of the ATF-2/JunD heterodimers. ATF-2 formed complexes with JunD as measured by immunoprecipitation using the ATF-2 and JunD antibodies and by glutathione S-transferase (GST) pull-down assays using GST-ATF-2 fusion proteins. Studies using various mutants of GST-ATF-2 revealed that formation of the ATF-2/JunD dimers depended on the COOH-terminal basic region-leucine zipper domain of ATF-2. Polyamine depletion increased ATF-2/JunD complex and inhibited CDK4 transcription as indicated by a decrease in the levels of CDK4-promoter activity and its mRNA. ATF-2 silencing not only prevented inhibition of CDK4 transcription in polyamine-deficient cells but also abolished repression of CDK4 expression induced by ectopic JunD overexpression. ATF-2 silencing also promoted IEC growth in polyamine-depleted cells. These results indicate that induced ATF-2/JunD association following polyamine depletion represses CDK4 transcription, thus contributing to the inhibition of IEC growth.

  13. ArgR-dependent repression of arginine and histidine transport genes in Escherichia coli K-12.

    Science.gov (United States)

    Caldara, Marina; Minh, Phu Nguyen Le; Bostoen, Sophie; Massant, Jan; Charlier, Daniel

    2007-10-19

    In Escherichia coli L-arginine is taken up by three periplasmic binding protein-dependent transport systems that are encoded by two genetic loci: the artPIQM-artJ and argT-hisJQMP gene clusters. The transcription of the artJ, artPIQM and hisJQMP genes and operons is repressed by liganded ArgR, whereas argT, encoding the LAO (lysine, arginine, ornithine) periplasmic binding protein, is insensitive to the repressor. Here we characterize the repressible Esigma70 P artJ, P artP and P hisJ promoters and demonstrate that the cognate operators consist of two 18 bp ARG boxes separated by 3 bp. Determination of the energy landscape of the ArgR-operator contacts by missing contact probing and mutant studies indicated that each box of a pair contributes to complex formation in vitro and to the repressibility in vivo, but to a different extent. The organization of the ARG boxes and promoter elements in the control regions of the uptake genes is distinct from that of the arginine biosynthetic genes. The hisJQMP operon is the first member of the E. coli ArgR regulon, directly repressed by liganded ArgR, where none of the core promoter elements overlaps the ARG boxes. Single round in vitro transcription assays and DNase I footprinting experiments indicate that liganded ArgR inhibits P artJ and P artP promoter activity by steric exclusion of the RNA polymerase. In contrast, ArgR-mediated repression of P hisJ by inhibition of RNA polymerase binding appears to occur through topological changes of the promoter region.

  14. Transcriptional repression in normal human keratinocytes by wild-type and mutant p53.

    Science.gov (United States)

    Alvarez-Salas, L M; Velazquez, A; Lopez-Bayghen, E; Woodworth, C D; Garrido, E; Gariglio, P; DiPaolo, J A

    1995-05-01

    Wild-type p53 is a nuclear phosphoprotein that inhibits cell proliferation and represses transcriptionally most TATA box-containing promoters in transformed or tumor-derived cell lines. This study demonstrates that p53 alters transcription of the long control region (LCR) of human papillomavirus type 18 (HPV-18). Wild-type and mutant p53 143Val to Ala repressed the HPV-18 LCR promoter in normal human keratinocytes, the natural host cell for HPV infections. Repression by wild-type p53 was also observed in C-33A cells and in an HPV-16-immortalized cell line with an inducible wild-type p53. However, when C-33A cells were cotransfected with the HPV-18 LCR and mutant 143Val to Ala, repression did not occur. Mutant p53 135Cys to Ser did not induce repression in either normal human keratinocytes or in the C-33A line; although like 143Val to Ala, it is thought to affect the DNA binding activity of the wild-type protein. The ability of mutant p53 143Val to Ala to inactivate the HPV early promoter in normal cells (by approximately 60% reduction) suggests that this mutant may be able to associate with wild-type p53 and interact with TATA box-binding proteins. Therefore, these results demonstrate that the transcriptional activities of p53 mutants may be dependent upon the cell type assayed and the form of its endogenous p53. Furthermore, normal human keratinocytes represent an alternative model for determining the activities of p53 mutants.

  15. Isorhamnetin represses adipogenesis in 3T3-L1 cells.

    Science.gov (United States)

    Lee, Jongsung; Jung, Eunsun; Lee, Jienny; Kim, Saebom; Huh, Sungran; Kim, Youngsoo; Kim, Yongwoo; Byun, Sang Yo; Kim, Yeong-Shik; Park, Deokhoon

    2009-02-01

    Adipocyte dysfunction is strongly associated with the development of obesity, which is a major risk factor for many disorders including diabetes, hypertension, and heart disease. It is generally accepted that the regulation of adipogenesis or adipokines expression prevents obesity. In this study, we show that isorhamnetin inhibits adipocyte differentiation, as evidenced by reduced triglyceride (TG) accumulation and glycerol-3-phosphate dehydrogenase (GPDH) activity. At the molecular level, the mRNA expression levels of peroxidase proliferator-activated receptor-gamma (PPAR-gamma) and CCAAT/enhancer-binding protein-alpha (C/EBP-alpha), which are the major adipogenic transcription factors, were markedly reduced by isorhamnetin. However, the mRNA levels of C/EBP-beta and -delta, the upstream regulators of PPAR-gamma and C/EBP-alpha, were not reduced by isorhamnetin. Moreover, the mRNA levels of PPAR-gamma target genes such as lipoprotein lipase (LPL), CD36, aP2, and liver X receptor-alpha (LXR-alpha) were downregulated by isorhamnetin. We also showed that isorhamnetin inhibits the expression and secretion of adiponectin, and the results of adiponectin promoter assays suggest the inhibition of PPAR-gamma expression as a possible mechanism underlying the isorhamnetin-mediated effects. Taken together, these results indicate that isorhamnetin inhibits adipogenesis through downregulation of PPAR-gamma and C/EBP-alpha.

  16. Glucose repression of lactose/galactose metabolism in Kluyveromyces lactis is determined by the concentration of the transcriptional activator LAC9 (K1GAL4) [corrected

    OpenAIRE

    Zachariae, W; Kuger, P; Breunig, K D

    1993-01-01

    In the budding yeast Kluyveromyces lactis glucose repression of genes involved in lactose and galactose metabolism is primarily mediated by LAC9 (or K1GAL4) the homologue of the well-known Saccharomyces cerevisiae transcriptional activator GAL4. Phenotypic difference in glucose repression existing between natural strains are due to differences in the LAC9 gene (Breunig, 1989, Mol.Gen.Genet. 261, 422-427). Comparison between the LAC9 alleles of repressible and non-repressible strains revealed ...

  17. High Glucose Represses hERG K+ Channel Expression through Trafficking Inhibition

    Directory of Open Access Journals (Sweden)

    Yuan-Qi Shi

    2015-08-01

    Full Text Available Background/Aims: Abnormal QT prolongation is the most prominent cardiac electrical disturbance in patients with diabetes mellitus (DM. It is well known that the human ether-ago-go-related gene (hERG controls the rapid delayed rectifier K+ current (IKr in cardiac cells. The expression of the hERG channel is severely down-regulated in diabetic hearts, and this down-regulation is a critical contributor to the slowing of repolarization and QT prolongation. However, the intracellular mechanisms underlying the diabetes-induced hERG deficiency remain unknown. Methods: The expression of the hERG channel was assessed via western blot analysis, and the hERG current was detected with a patch-clamp technique. Results: The results of our study revealed that the expression of the hERG protein and the hERG current were substantially decreased in high-glucose-treated hERG-HEK cells. Moreover, we demonstrated that the high-glucose-mediated damage to the hERG channel depended on the down-regulation of protein levels but not the alteration of channel kinetics. These discoveries indicated that high glucose likely disrupted hERG channel trafficking. From the western blot and immunoprecipitation analyses, we found that high glucose induced trafficking inhibition through an effect on the expression of Hsp90 and its interaction with hERG. Furthermore, the high-glucose-induced inhibition of hERG channel trafficking could activate the unfolded protein response (UPR by up-regulating the expression levels of activating transcription factor-6 (ATF-6 and the ER chaperone protein calnexin. In addition, we demonstrated that 100 nM insulin up-regulated the expression of the hERG channel and rescued the hERG channel repression caused by high glucose. Conclusion: The results of our study provide the first evidence of a high-glucose-induced hERG channel deficiency resulting from the inhibition of channel trafficking. Furthermore, insulin promotes the expression of the hERG channel

  18. Repression/depression of conjugative plasmids and their influence on the mutation-selection balance in static environments.

    Science.gov (United States)

    Atsmon-Raz, Yoav; Raz, Yoav; Tannenbaum, Emmanuel David

    2014-01-01

    We study the effect that conjugation-mediated Horizontal Gene Transfer (HGT) has on the mutation-selection balance of a population in a static environment. We consider a model whereby a population of unicellular organisms, capable of conjugation, comes to mutation-selection balance in the presence of an antibiotic, which induces a first-order death rate constant [Formula: see text] for genomes that are not resistant. We explicitly take into consideration the repression/de-repression dynamics of the conjugative plasmid, and assume that a de-repressed plasmid remains temporarily de-repressed after copying itself into another cell. We assume that both repression and de-repression are characterized by first-order rate constants [Formula: see text]and [Formula: see text], respectively. We find that conjugation has a deleterious effect on the mean fitness of the population, suggesting that HGT does not provide a selective advantage in a static environment, but is rather only useful for adapting to new environments. This effect can be ameliorated by repression, suggesting that while HGT is not necessarily advantageous for a population in a static environment, its deleterious effect on the mean fitness can be negated via repression. Therefore, it is likely that HGT is much more advantageous in a dynamic landscape. Furthermore, in the limiting case of a vanishing spontaneous de-repression rate constant, we find that the fraction of conjugators in the population undergoes a phase transition as a function of population density. Below a critical population density, the fraction of conjugators is zero, while above this critical population density the fraction of conjugators rises continuously to one. Our model for conjugation-mediated HGT is related to models of infectious disease dynamics, where the conjugators play the role of the infected (I) class, and the non-conjugators play the role of the susceptible (S) class.

  19. Repression/depression of conjugative plasmids and their influence on the mutation-selection balance in static environments.

    Directory of Open Access Journals (Sweden)

    Yoav Atsmon-Raz

    Full Text Available We study the effect that conjugation-mediated Horizontal Gene Transfer (HGT has on the mutation-selection balance of a population in a static environment. We consider a model whereby a population of unicellular organisms, capable of conjugation, comes to mutation-selection balance in the presence of an antibiotic, which induces a first-order death rate constant [Formula: see text] for genomes that are not resistant. We explicitly take into consideration the repression/de-repression dynamics of the conjugative plasmid, and assume that a de-repressed plasmid remains temporarily de-repressed after copying itself into another cell. We assume that both repression and de-repression are characterized by first-order rate constants [Formula: see text]and [Formula: see text], respectively. We find that conjugation has a deleterious effect on the mean fitness of the population, suggesting that HGT does not provide a selective advantage in a static environment, but is rather only useful for adapting to new environments. This effect can be ameliorated by repression, suggesting that while HGT is not necessarily advantageous for a population in a static environment, its deleterious effect on the mean fitness can be negated via repression. Therefore, it is likely that HGT is much more advantageous in a dynamic landscape. Furthermore, in the limiting case of a vanishing spontaneous de-repression rate constant, we find that the fraction of conjugators in the population undergoes a phase transition as a function of population density. Below a critical population density, the fraction of conjugators is zero, while above this critical population density the fraction of conjugators rises continuously to one. Our model for conjugation-mediated HGT is related to models of infectious disease dynamics, where the conjugators play the role of the infected (I class, and the non-conjugators play the role of the susceptible (S class.

  20. A Looping-Based Model for Quenching Repression.

    Directory of Open Access Journals (Sweden)

    Yaroslav Pollak

    2017-01-01

    Full Text Available We model the regulatory role of proteins bound to looped DNA using a simulation in which dsDNA is represented as a self-avoiding chain, and proteins as spherical protrusions. We simulate long self-avoiding chains using a sequential importance sampling Monte-Carlo algorithm, and compute the probabilities for chain looping with and without a protrusion. We find that a protrusion near one of the chain's termini reduces the probability of looping, even for chains much longer than the protrusion-chain-terminus distance. This effect increases with protrusion size, and decreases with protrusion-terminus distance. The reduced probability of looping can be explained via an eclipse-like model, which provides a novel inhibitory mechanism. We test the eclipse model on two possible transcription-factor occupancy states of the D. melanogaster eve 3/7 enhancer, and show that it provides a possible explanation for the experimentally-observed eve stripe 3 and 7 expression patterns.

  1. Epigenetic repression of ROR2 has a Wnt-mediated, pro-tumourigenic role in colon cancer

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    López-Otín Carlos

    2010-06-01

    Full Text Available Abstract Background Wnt factors control cell differentiation through semi-independent molecular cascades known as the β-catenin-dependent (canonical and -independent (non-canonical Wnt signalling pathways. Genetic and epigenetic alteration of components of the canonical Wnt signalling pathway is one of the primary mechanisms underlying colon cancer. Despite increasing evidence of the role of the non-canonical pathways in tumourigenesis, however, the underlying molecular mechanisms are poorly understood. Results Here we report that the receptor tyrosine kinase-like orphan receptor 2 (ROR2, a transmembrane receptor for Wnt factors that activates non-canonical pathways, is frequently repressed by aberrant promoter hypermethylation in human colon cancer cell lines and primary tumours. By restoring ROR2 activity in colon cancer cells harbouring ROR2 promoter hypermethylation, we show that the role of ROR2 in colon cancer cells is mediated, at least in part, by canonical Wnt and that its epigenetic-dependent loss can be pro-tumourigenic. Conclusions Our data show the importance of epigenetic alterations of ROR2 in colon cancer, highlighting the close interconnection between canonical and non-canonical Wnt signalling pathways in this type of tumour.

  2. Generation and functional characterization of a BCL10-inhibitory peptide that represses NF-kappaB activation.

    Science.gov (United States)

    Marasco, Daniela; Stilo, Romania; Sandomenico, Annamaria; Monti, Simona Maria; Tizzano, Barbara; de Capua, Antonia; Varricchio, Ettore; Liguoro, Domenico; Zotti, Tiziana; Formisano, Silvestro; Ruvo, Menotti; Vito, Pasquale

    2009-08-27

    The molecular complex containing BCL10 and CARMA [CARD (caspase recruitment domain)-containing MAGUK (membrane-associated guanylate kinase)] proteins has recently been identified as a key component in the signal transduction pathways that regulate activation of the transcription factor NF-kappaB (nuclear factor kappaB) in lymphoid and non-lymphoid cells. Assembly of complexes containing BCL10 and CARMA proteins relies on homophilic interactions established between the CARDs of these proteins. In order to identify BCL10-inhibitory peptides, we have established a method of assaying peptides derived from the CARD of BCL10 in binding competition assays of CARD-CARD self-association. By this procedure, a short peptide corresponding to amino acid residues 91-98 of BCL10 has been selected as an effective inhibitor of protein self-association. When tested in cell assays for its capacity to block NF-kappaB activation, this peptide represses activation of NF-kappaB mediated by BCL10, CARMA3 and PMA/ionomycin stimulation. Collectively, these results indicate that residues 91-98 of BCL10 are involved in BCL10 self-association and also participate in the interaction with external partners. We also show that blocking of the CARD of BCL10 may potentially be used for the treatment of pathological conditions associated with inappropriate NF-kappaB activation.

  3. Control of translation and miRNA-dependent repression by a novel poly(A binding protein, hnRNP-Q.

    Directory of Open Access Journals (Sweden)

    Yuri V Svitkin

    Full Text Available Translation control often operates via remodeling of messenger ribonucleoprotein particles. The poly(A binding protein (PABP simultaneously interacts with the 3' poly(A tail of the mRNA and the eukaryotic translation initiation factor 4G (eIF4G to stimulate translation. PABP also promotes miRNA-dependent deadenylation and translational repression of target mRNAs. We demonstrate that isoform 2 of the mouse heterogeneous nuclear protein Q (hnRNP-Q2/SYNCRIP binds poly(A by default when PABP binding is inhibited. In addition, hnRNP-Q2 competes with PABP for binding to poly(A in vitro. Depleting hnRNP-Q2 from translation extracts stimulates cap-dependent and IRES-mediated translation that is dependent on the PABP/poly(A complex. Adding recombinant hnRNP-Q2 to the extracts inhibited translation in a poly(A tail-dependent manner. The displacement of PABP from the poly(A tail by hnRNP-Q2 impaired the association of eIF4E with the 5' m(7G cap structure of mRNA, resulting in the inhibition of 48S and 80S ribosome initiation complex formation. In mouse fibroblasts, silencing of hnRNP-Q2 stimulated translation. In addition, hnRNP-Q2 impeded let-7a miRNA-mediated deadenylation and repression of target mRNAs, which require PABP. Thus, by competing with PABP, hnRNP-Q2 plays important roles in the regulation of global translation and miRNA-mediated repression of specific mRNAs.

  4. Ditadura, repressão e música no Chile

    Directory of Open Access Journals (Sweden)

    Camargo, Cássio Michel dos Santos

    2011-01-01

    Full Text Available Este trabalho tem como objetivo analisar o processo de constituição da ditadura Pinochet, a repressão e o combate às representações culturais oriundas do Movimento da Nova Canção Chilena, especificamente a música. Também analisa o conceito de ditadura fazendo um pequeno panorama histórico da América e o período de crise institucional do governo Allende. A imposição do golpe militar por Pinochet; salienta os motivos da constituição do Movimento Nova Canção; destaca o processo de institucionalização da repressão pelo governo e, por fim, analisa condição clandestina da produção musical no Chile frente às perseguições do regime ditatorial

  5. EVEN-SKIPPED HOMEOBOX 1 controls human ES cell differentiation by directly repressing GOOSECOID expression

    DEFF Research Database (Denmark)

    Kalisz, Mark; Winzi, Maria Karin; Bisgaard, Hanne Cathrine;

    2012-01-01

    TGFß signaling patterns the primitive streak, yet little is known about transcriptional effectors that mediate the cell fate choices during streak-like development in mammalian embryos and in embryonic stem (ES) cells. Here we demonstrate that cross-antagonistic actions of EVEN-SKIPPED HOMEOBOX 1...... (EVX1) and GOOSECOID (GSC) regulate cell fate decisions in streak-like progenitors derived from human ES cells exposed to BMP4 and/or activin. We found that EVX1 repressed GSC expression and promoted formation of posterior streak-like progeny in response to BMP4, and conversely that GSC repressed EVX1...... expression and was required for development of anterior streak-like progeny in response to activin. Chromatin immunoprecipitation assays showed that EVX1 bound to the GSC 5'-flanking region in BMP4 treated human ES cells, and band shift assays identified two EVX1 binding sites in the GSC 5'-region...

  6. Reversible and rapid transfer-RNA deactivation as a mechanism of translational repression in stress.

    Science.gov (United States)

    Czech, Andreas; Wende, Sandra; Mörl, Mario; Pan, Tao; Ignatova, Zoya

    2013-08-01

    Stress-induced changes of gene expression are crucial for survival of eukaryotic cells. Regulation at the level of translation provides the necessary plasticity for immediate changes of cellular activities and protein levels. In this study, we demonstrate that exposure to oxidative stress results in a quick repression of translation by deactivation of the aminoacyl-ends of all transfer-RNA (tRNA). An oxidative-stress activated nuclease, angiogenin, cleaves first within the conserved single-stranded 3'-CCA termini of all tRNAs, thereby blocking their use in translation. This CCA deactivation is reversible and quickly repairable by the CCA-adding enzyme [ATP(CTP):tRNA nucleotidyltransferase]. Through this mechanism the eukaryotic cell dynamically represses and reactivates translation at low metabolic costs.

  7. Reversible and rapid transfer-RNA deactivation as a mechanism of translational repression in stress.

    Directory of Open Access Journals (Sweden)

    Andreas Czech

    2013-08-01

    Full Text Available Stress-induced changes of gene expression are crucial for survival of eukaryotic cells. Regulation at the level of translation provides the necessary plasticity for immediate changes of cellular activities and protein levels. In this study, we demonstrate that exposure to oxidative stress results in a quick repression of translation by deactivation of the aminoacyl-ends of all transfer-RNA (tRNA. An oxidative-stress activated nuclease, angiogenin, cleaves first within the conserved single-stranded 3'-CCA termini of all tRNAs, thereby blocking their use in translation. This CCA deactivation is reversible and quickly repairable by the CCA-adding enzyme [ATP(CTP:tRNA nucleotidyltransferase]. Through this mechanism the eukaryotic cell dynamically represses and reactivates translation at low metabolic costs.

  8. Cinema e contraluz: limiares da repressão na cultura midiática argentina

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    Márcio Serelle

    2014-12-01

    Full Text Available This paper examines the backlighting technique used in Argentine movies (mainly Valentín, Kamchatka, and The Secret in Their Eyes, seen as a kind of narrative composition in which events related to dictatorships and other forms of repression operate in the dark, but strongly affect the fate of the characters. Starting from a brief overview of the internationalization of the Argentine film industry, which, as early as the mid-1980s, had already articulated conventional dramatic structures and political denunciation, this study analyzes how part of the cinema of this century represents the violence of authoritarian states. Be it through imaginative investment, metalanguage, or allegory, these narratives renounce graphic images of the violence of repressive apparatuses and create dramaturgical compositions of highly effective communication. Thus, this work discusses the reflective capacity of these films as it pertains to the relationship between the fictional, mediatic and social contexts.

  9. Terrorism and state repression: strategy and norms in France and the UK

    Directory of Open Access Journals (Sweden)

    Frank Foley

    2016-04-01

    Full Text Available This article approaches the question of whether terrorism “works” and argues that an examination of some of terrorism’s more “modest” effects can contribute to the way we analyse its overall effectiveness and strategic impact. The article looks at whether terrorist violence has brought “disorientation” to European societies and led states to launch repressive counterterrorist operations. Its main empirical focus is a comparison of Britain’s and France’s responses to contemporary jihadist terrorism. It examines the extent to which we can understand these cases from a rational choice perspective, before going on to argue that a state’s responses to terrorism are filtered through certain domestic societal norms in each country that determine whether or not terrorist violence leads to a repressive response from governments. This has implications for the way we analyse the interaction between terrorists and the state, as well as the effectiveness of terrorism itself.

  10. Repression and solidary cultures of resistance: Irish political prisoners on protest.

    Science.gov (United States)

    O'Hearn, Denis

    2009-09-01

    Social activists and especially insurgents have created solidary cultures of resistance in conditions of high risk and repression. One such instance is an episode of contention by Irish political prisoners in the late 1970s. The "blanketmen" appropriated and then built a solidary culture within spaces that had been under official control. Their ability to maintain such a collective response was enhanced by an intensifying cycle of protest and violent reprisal, including extreme stripping of their material environment, in which the prisoners gained considerable initiative. This study uses interviews and contemporary writings by prisoners, prison authorities, visitors, and movement activists to examine how the dynamic of protest and repression transformed insurgent prison culture--through material, emotional, and perceptive changes--and the importance of leadership in the transformation. Special attention is given to prisoner activities in appropriated spaces that reinforced the culture of resistance: promoting the Irish language, cultural production, and the production of propaganda.

  11. Targeted transcriptional repression using a chimeric TALE-SRDX repressor protein

    KAUST Repository

    Mahfouz, Magdy M.

    2011-12-14

    Transcriptional activator-like effectors (TALEs) are proteins secreted by Xanthomonas bacteria when they infect plants. TALEs contain a modular DNA binding domain that can be easily engineered to bind any sequence of interest, and have been used to provide user-selected DNA-binding modules to generate chimeric nucleases and transcriptional activators in mammalian cells and plants. Here we report the use of TALEs to generate chimeric sequence-specific transcriptional repressors. The dHax3 TALE was used as a scaffold to provide a DNA-binding module fused to the EAR-repression domain (SRDX) to generate a chimeric repressor that targets the RD29A promoter. The dHax3. SRDX protein efficiently repressed the transcription of the RD29A

  12. MYC Association with Cancer Risk and a New Model of MYC-Mediated Repression

    Science.gov (United States)

    Cole, Michael D.

    2014-01-01

    MYC is one of the most frequently mutated and overexpressed genes in human cancer but the regulation of MYC expression and the ability of MYC protein to repress cellular genes (including itself) have remained mysterious. Recent genome-wide association studies show that many genetic polymorphisms associated with disease risk map to distal regulatory elements that regulate the MYC promoter through large chromatin loops. Cancer risk-associated single-nucleotide polymorphisms (SNPs) contain more potent enhancer activity, promoting higher MYC levels and a greater risk of disease. The MYC promoter is also subject to complex regulatory circuits and limits its own expression by a feedback loop. A model for MYC autoregulation is discussed which involves a signaling pathway between the PTEN (phosphatase and tensin homolog) tumor suppressor and repressive histone modifications laid down by the EZH2 methyltransferase. PMID:24985129

  13. Secularization versus religious revival in Eastern Europe: Church institutional resilience, state repression and divergent paths.

    Science.gov (United States)

    Northmore-Ball, Ksenia; Evans, Geoffrey

    2016-05-01

    Despite continuing for over two decades, the debate about the nature of the trends in religiosity in post-Communist Eastern Europe remains unresolved: some arguing that these countries are undergoing the same process of secularization as the West, while others insist that the entire region is experiencing a religious revival. Using national sample surveys from the early 1990s to 2007 to examine the change in demographic predictors of religiosity, we show that Catholic and Orthodox countries are experiencing different trends, the first group displaying evidence of secularization and the second of revival, and that these two different trends are likely to derive from the legacies of state repression and the differing abilities of the churches to resist such repression. We argue that the current literature has thus taken a mistakenly general approach, and that the post-Communist region consists of at least two distinct groups of societies with different trends in religiosity. Copyright © 2016. Published by Elsevier Inc.

  14. Substrate uptake, phosphorus repression, and effect of seed culture on glycopeptide antibiotic production

    DEFF Research Database (Denmark)

    Maiti, Soumen K.; Singh, Kamaleshwar P.; Eliasson Lantz, Anna

    2010-01-01

    Actinomycetes, the soil borne bacteria which exhibit filamentous growth, are known for their ability to produce a variety of secondary metabolites including antibiotics. Industrial scale production of such antibiotics is typically carried out in a multi-substrate medium where the product formation...... may experience catabolite repression by one or more of the substrates. Availability of reliable process models is a key bottleneck in optimization of such processes. Here we present a structured kinetic model to describe the growth, substrate uptake and product formation for the glycopeptide...... antibiotic producer strain Amycolatopsis balhimycina DSM5908. The model is based on the premise that the organism is an optimal strategist and that the various metabolic pathways are regulated via key rate limiting enzymes. Further, the model accounts for substrate inhibition and catabolite repression...

  15. Reality monitoring in adults reporting repressed, recovered, or continuous memories of childhood sexual abuse.

    Science.gov (United States)

    McNally, Richard J; Clancy, Susan A; Barrett, Heidi M; Parker, Holly A

    2005-02-01

    People who report either repressed or recovered memories of childhood sexual abuse (CSA) may have deficits in reality monitoring--the process whereby one discriminates memories of percepts from memories of images. Using signal detection methods, the authors found that adults reporting either repressed or recovered memories of CSA were less able to discriminate between words they had seen from words they had imagined seeing than were adults reporting either never having forgotten their CSA or adults reporting no history of CSA. Relative deficits in the ability to discriminate percepts from images (i.e., low d') were apparent on only some tests. The groups did not differ in their criterion--response bias--for affirming having seen versus imagined stimuli. Copyright (c) 2005 APA, all rights reserved.

  16. Military westernization and state repression in the post-Cold War era.

    Science.gov (United States)

    Swed, Ori; Weinreb, Alexander

    2015-09-01

    The waves of unrest that have shaken the Arab world since December 2010 have highlighted significant differences in the readiness of the military to intervene in political unrest by forcefully suppressing dissent. We suggest that in the post-Cold War period, this readiness is inversely associated with the level of military westernization, which is a product of the acquisition of arms from western countries. We identify two mechanisms linking the acquisition of arms from western countries to less repressive responses: dependence and conditionality; and a longer-term diffusion of ideologies regarding the proper form of civil-military relations. Empirical support for our hypothesis is found in an analysis of 2523 cases of government response to political unrest in 138 countries in the 1996-2005 period. We find that military westernization mitigates state repression in general, with more pronounced effects in the poorest countries. However, we also identify substantial differences between the pre- and post-9/11 periods.

  17. Phosphoribulokinase mediates nitrogenase-induced carbon dioxide fixation gene repression in Rhodobacter sphaeroides

    Science.gov (United States)

    Farmer, Ryan M.

    2015-01-01

    In many organisms there is a balance between carbon and nitrogen metabolism. These observations extend to the nitrogen-fixing, nonsulfur purple bacteria, which have the classic family of P(II) regulators that coordinate signals of carbon and nitrogen status to regulate nitrogen metabolism. Curiously, these organisms also possess a reverse mechanism to regulate carbon metabolism based on cellular nitrogen status. In this work, studies in Rhodobacter sphaeroides firmly established that the activity of the enzyme that catalyses nitrogen fixation, nitrogenase, induces a signal that leads to repression of genes encoding enzymes of the Calvin–Benson–Bassham (CBB) CO2 fixation pathway. Additionally, genetic and metabolomic experiments revealed that NADH-activated phosphoribulokinase is an intermediate in the signalling pathway. Thus, nitrogenase activity appears to be linked to cbb gene repression through phosphoribulokinase. PMID:26306848

  18. Multi-Faceted Characterization of a Novel LuxR-Repressible Promoter Library for Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Susanna Zucca

    Full Text Available The genetic elements regulating the natural quorum sensing (QS networks of several microorganisms are widely used in synthetic biology to control the behaviour of single cells and engineered bacterial populations via ad-hoc constructed synthetic circuits. A number of novel engineering-inspired biological functions have been implemented and model systems have also been constructed to improve the knowledge on natural QS systems. Synthetic QS-based parts, such as promoters, have been reported in literature, to provide biological components with functions that are not present in nature, like modified induction logic or activation/repression by additional molecules. In this work, a library of promoters that can be repressed by the LuxR protein in presence of the QS autoinducer N-3-oxohexanoyl-L-homoserine lactone (AHL was reported for Escherichia coli, to expand the toolkit of genetic parts that can be used to engineer novel synthetic QS-based systems. The library was constructed via polymerase chain reaction with highly constrained degenerate oligonucleotides, designed according to the consensus -35 and -10 sequences of a previously reported constitutive promoter library of graded strength, to maximize the probability of obtaining functional clones. All the promoters have a lux box between the -35 and -10 regions, to implement a LuxR-repressible behaviour. Twelve unique library members of graded strength (about 100-fold activity range were selected to form the final library and they were characterized in several genetic contexts, such as in different plasmids, via different reporter genes, in presence of a LuxR expression cassette in different positions and in response to different AHL concentrations. The new obtained regulatory parts and corresponding data can be exploited by synthetic biologists to implement an artificial AHL-dependent repression of transcription in genetic circuits. The target transcriptional activity can be selected among the

  19. From Sensorimotor Inhibition to Freudian Repression: Insights from Psychosis Applied to Neurosis

    Science.gov (United States)

    Bazan, Ariane

    2012-01-01

    First, three case studies are presented of psychotic patients having in common an inability to hold something down or out. In line with other theories on psychosis, we propose that a key change is at the efference copy system. Going back to Freud’s mental apparatus, we propose that the messages of discharge of the motor neurons, mobilized to direct perception, also called “indications of reality,” are equivalent to the modern efference copies. With this key, the reading of the cases is coherent with the psychodynamic understanding of psychosis, being a downplay of secondary processes, and consequently, a dominance of primary processes. Moreover, putting together the sensorimotor idea of a failure of efference copy-mediated inhibition with the psychoanalytic idea of a failing repression in psychosis, the hypothesis emerges that the attenuation enabled by the efference copy dynamics is, in some instances, the physiological instantiation of repression. Second, we applied this idea to the mental organization in neurosis. Indeed, the efference copy-mediated attenuation is thought to be the mechanism through which sustained activation of an intention, without reaching it – i.e., inhibition of an action – gives rise to mental imagery. Therefore, as inhibition is needed for any targeted action or for normal language understanding, acting in the world, or processing language, structurally induces mental imagery, constituting a subjective unconscious mental reality. Repression is a special instance of inhibition for emotionally threatening stimuli. These stimuli require stronger inhibition, leaving (the attenuation of) the motor intentions totally unanswered, in order to radically prevent execution which would lead to development of excess affect. This inhibition, then, yields a specific type of motor imagery, called “phantoms,” which induce mental preoccupation, as well as symptoms which, especially through their form, refer to the repressed motor fragments

  20. From sensorimotor inhibition to freudian repression: insights from psychosis applied to neurosis.

    Science.gov (United States)

    Bazan, Ariane

    2012-01-01

    First, three case studies are presented of psychotic patients having in common an inability to hold something down or out. In line with other theories on psychosis, we propose that a key change is at the efference copy system. Going back to Freud's mental apparatus, we propose that the messages of discharge of the motor neurons, mobilized to direct perception, also called "indications of reality," are equivalent to the modern efference copies. With this key, the reading of the cases is coherent with the psychodynamic understanding of psychosis, being a downplay of secondary processes, and consequently, a dominance of primary processes. Moreover, putting together the sensorimotor idea of a failure of efference copy-mediated inhibition with the psychoanalytic idea of a failing repression in psychosis, the hypothesis emerges that the attenuation enabled by the efference copy dynamics is, in some instances, the physiological instantiation of repression. Second, we applied this idea to the mental organization in neurosis. Indeed, the efference copy-mediated attenuation is thought to be the mechanism through which sustained activation of an intention, without reaching it - i.e., inhibition of an action - gives rise to mental imagery. Therefore, as inhibition is needed for any targeted action or for normal language understanding, acting in the world, or processing language, structurally induces mental imagery, constituting a subjective unconscious mental reality. Repression is a special instance of inhibition for emotionally threatening stimuli. These stimuli require stronger inhibition, leaving (the attenuation of) the motor intentions totally unanswered, in order to radically prevent execution which would lead to development of excess affect. This inhibition, then, yields a specific type of motor imagery, called "phantoms," which induce mental preoccupation, as well as symptoms which, especially through their form, refer to the repressed motor fragments.

  1. Inducing Alignment: The Dynamic Impact of Repression and Mobilizing Structures on Population Support

    Science.gov (United States)

    2009-12-01

    Sociological Theory, 21(1), 44–68. Retrieved January 25, 2009, from JSTOR database , http://www.jstor.org/sTable/3108608 Eisenstadt, M., & White, J. (2005...Retrieved January 24, 2009, from JSTOR database , http://www.jstor.org/sTable/174207 Hess, D., & Martin, B. (2006). Repression, backfire, and the...once-deadliest region. The Christian Science Monitor, 1. Retrieved September 27, 2008, from ProQuest National Newspapers Core database . (Document ID

  2. Nationalist To Transnational Insurgency: State Repression And Violent Extremist Scale Shift

    Science.gov (United States)

    2016-05-26

    Dudayev’s takeover , Russia’s televised announcement of a state of emergency in Chechnya on 08 November 1991 and the threat of Russian repression...Almost half (42%) of the BIF budget supported operations in Chechnya.66 BIF provided recruits, doctors, medicine, money, an X-ray machine, “ anti ...expert advice, military items including NBC protective masks, night vision devices , and global position systems, currency, “monetary instruments

  3. The purge of spanish education during franquism (1936-1975. The institutionalization of a repression

    Directory of Open Access Journals (Sweden)

    Carlos de Pablo Lobo

    2007-09-01

    Full Text Available Work on the trial against Spanish teaching profession because of politic reasons, from the beginning of the Spanish Civil War (1936-1939 to the end of the General Francisco Franco dictatorship (1939-1975. It includes a legislation research and it also studies the reasons, institutions and the different periods in which the course is going through. Key words: Repression, Purge, Spanish teaching, Civil War, Elementary education, Franquism, Education methods. 

  4. Active repression by RARγ signaling is required for vertebrate axial elongation.

    Science.gov (United States)

    Janesick, Amanda; Nguyen, Tuyen T L; Aisaki, Ken-ichi; Igarashi, Katsuhide; Kitajima, Satoshi; Chandraratna, Roshantha A S; Kanno, Jun; Blumberg, Bruce

    2014-06-01

    Retinoic acid receptor gamma 2 (RARγ2) is the major RAR isoform expressed throughout the caudal axial progenitor domain in vertebrates. During a microarray screen to identify RAR targets, we identified a subset of genes that pattern caudal structures or promote axial elongation and are upregulated by increased RAR-mediated repression. Previous studies have suggested that RAR is present in the caudal domain, but is quiescent until its activation in late stage embryos terminates axial elongation. By contrast, we show here that RARγ2 is engaged in all stages of axial elongation, not solely as a terminator of axial growth. In the absence of RA, RARγ2 represses transcriptional activity in vivo and maintains the pool of caudal progenitor cells and presomitic mesoderm. In the presence of RA, RARγ2 serves as an activator, facilitating somite differentiation. Treatment with an RARγ-selective inverse agonist (NRX205099) or overexpression of dominant-negative RARγ increases the expression of posterior Hox genes and that of marker genes for presomitic mesoderm and the chordoneural hinge. Conversely, when RAR-mediated repression is reduced by overexpressing a dominant-negative co-repressor (c-SMRT), a constitutively active RAR (VP16-RARγ2), or by treatment with an RARγ-selective agonist (NRX204647), expression of caudal genes is diminished and extension of the body axis is prematurely terminated. Hence, gene repression mediated by the unliganded RARγ2-co-repressor complex constitutes a novel mechanism to regulate and facilitate the correct expression levels and spatial restriction of key genes that maintain the caudal progenitor pool during axial elongation in Xenopus embryos.

  5. The B-type lamin is required for somatic repression of testis-specific gene clusters

    Science.gov (United States)

    Shevelyov, Y. Y.; Lavrov, S. A.; Mikhaylova, L. M.; Nurminsky, I. D.; Kulathinal, R. J.; Egorova, K. S.; Rozovsky, Y. M.; Nurminsky, D. I.

    2009-01-01

    Large clusters of coexpressed tissue-specific genes are abundant on chromosomes of diverse species. The genes coordinately misexpressed in diverse diseases are also found in similar clusters, suggesting that evolutionarily conserved mechanisms regulate expression of large multigenic regions both in normal development and in its pathological disruptions. Studies on individual loci suggest that silent clusters of coregulated genes are embedded in repressed chromatin domains, often localized to the nuclear periphery. To test this model at the genome-wide scale, we studied transcriptional regulation of large testis-specific gene clusters in somatic tissues of Drosophila. These gene clusters showed a drastic paucity of known expressed transgene insertions, indicating that they indeed are embedded in repressed chromatin. Bioinformatics analysis suggested the major role for the B-type lamin, LamDmo, in repression of large testis-specific gene clusters, showing that in somatic cells as many as three-quarters of these clusters interact with LamDmo. Ablation of LamDmo by using mutants and RNAi led to detachment of testis-specific clusters from nuclear envelope and to their selective transcriptional up-regulation in somatic cells, thus providing the first direct evidence for involvement of the B-type lamin in tissue-specific gene repression. Finally, we found that transcriptional activation of the lamina-bound testis-specific gene cluster in male germ line is coupled with its translocation away from the nuclear envelope. Our studies, which directly link nuclear architecture with coordinated regulation of tissue-specific genes, advance understanding of the mechanisms underlying both normal cell differentiation and developmental disorders caused by lesions in the B-type lamins and interacting proteins. PMID:19218438

  6. From sensorimotor inhibition to Freudian repression: insights from psychosis applied to neurosis

    Directory of Open Access Journals (Sweden)

    Ariane eBazan

    2012-11-01

    Full Text Available First, three case studies are presented of psychotic patients having in common an inability to hold something down or out. In line with other theories on psychosis, we propose that a key change is at the efference copy system. Going back to Freud’s mental apparatus, we propose that the messages of discharge of the motor neurones, mobilised to direct perception, also called indications of reality, are equivalent to the modern efference copies. With this key, the reading of the cases is coherent with the psychodynamic understanding of psychosis, being a downplay of secondary processes, and consequently, a dominance of primary processes. Moreover, putting together the sensorimotor idea of a failure of efference copy-mediated inhibition with the psychoanalytic idea of a failing repression in psychosis, the hypothesis emerges that the attenuation enabled by the efference copy dynamics is, in some instances, the physiological instantiation of repression. Second, we applied this idea to the mental organisation in neurosis. Indeed, the efference copy-mediated attenuation is thought to be the mechanism through which sustained activation of an intention, without reaching it – i.e. inhibition of an action – gives rise to mental imagery. Therefore, as inhibition is needed for any targeted action or for normal language understanding, acting in the world or processing language structurally induces mental imagery, constituting a subjective unconscious mental reality. Repression is a special instance of inhibition for emotionally threatening stimuli. These stimuli require stronger inhibition, leaving (the attenuation of the motor intentions totally unanswered, in order to radically prevent execution which would lead to development of excess affect. This inhibition, then, yields a specific type of motor imagery, called phantoms, which induce mental preoccupation, as well as symptoms which, especially through their form, refer to the repressed motor

  7. Fate of the H-NS-repressed bgl operon in evolution of Escherichia coli.

    Directory of Open Access Journals (Sweden)

    T Sabari Sankar

    2009-03-01

    Full Text Available In the enterobacterial species Escherichia coli and Salmonella enterica, expression of horizontally acquired genes with a higher than average AT content is repressed by the nucleoid-associated protein H-NS. A classical example of an H-NS-repressed locus is the bgl (aryl-beta,D-glucoside operon of E. coli. This locus is "cryptic," as no laboratory growth conditions are known to relieve repression of bgl by H-NS in E. coli K12. However, repression can be relieved by spontaneous mutations. Here, we investigated the phylogeny of the bgl operon. Typing of bgl in a representative collection of E. coli demonstrated that it evolved clonally and that it is present in strains of the phylogenetic groups A, B1, and B2, while it is presumably replaced by a cluster of ORFans in the phylogenetic group D. Interestingly, the bgl operon is mutated in 20% of the strains of phylogenetic groups A and B1, suggesting erosion of bgl in these groups. However, bgl is functional in almost all B2 isolates and, in approximately 50% of them, it is weakly expressed at laboratory growth conditions. Homologs of bgl genes exist in Klebsiella, Enterobacter, and Erwinia species and also in low GC-content Gram-positive bacteria, while absent in E. albertii and Salmonella sp. This suggests horizontal transfer of bgl genes to an ancestral Enterobacterium. Conservation and weak expression of bgl in isolates of phylogenetic group B2 may indicate a functional role of bgl in extraintestinal pathogenic E. coli.

  8. Histone H3K9 methyltransferase G9a represses PPARγ expression and adipogenesis

    OpenAIRE

    Wang, Lifeng; Xu, Shiliyang; Lee, Ji-Eun; Baldridge, Anne; Grullon, Sean; Peng, Weiqun; Ge, Kai

    2012-01-01

    PPARγ promotes adipogenesis while Wnt proteins inhibit adipogenesis. However, the mechanisms that control expression of these positive and negative master regulators of adipogenesis remain incompletely understood. By genome-wide histone methylation profiling in preadipocytes, we find that among gene loci encoding adipogenesis regulators, histone methyltransferase (HMT) G9a-mediated repressive epigenetic mark H3K9me2 is selectively enriched on the entire PPARγ locus. H3K9me2 and G9a levels dec...

  9. H3K4 demethylase activities repress proliferative and postmitotic aging

    Science.gov (United States)

    Alvares, Stacy M; Mayberry, Gaea A; Joyner, Ebony Y; Lakowski, Bernard; Ahmed, Shawn

    2014-01-01

    Homeostasis of postmitotic and proliferating cells is maintained by pathways that repress stress. We found that the Caenorhabditis elegans histone 3 lysine 4 (H3K4) demethylases RBR-2 and SPR-5 promoted postmitotic longevity of stress-resistant daf-2 adults, altered pools of methylated H3K4, and promoted silencing of some daf-2 target genes. In addition, RBR-2 and SPR-5 were required for germ cell immortality at a high temperature. Transgenerational proliferative aging was enhanced for spr-5; rbr-2 double mutants, suggesting that these histone demethylases may function sequentially to promote germ cell immortality by targeting distinct H3K4 methyl marks. RBR-2 did not play a comparable role in the maintenance of quiescent germ cells in dauer larvae, implying that it represses stress that occurs as a consequence of germ cell proliferation, rather than stress that accumulates in nondividing cells. We propose that H3K4 demethylase activities promote the maintenance of chromatin states during stressful growth conditions, thereby repressing postmitotic aging of somatic cells as well as proliferative aging of germ cells. PMID:24134677

  10. sRNA Antitoxins: More than One Way to Repress a Toxin

    Directory of Open Access Journals (Sweden)

    Jia Wen

    2014-08-01

    Full Text Available Bacterial toxin-antitoxin loci consist of two genes: one encodes a potentially toxic protein, and the second, an antitoxin to repress its function or expression. The antitoxin can either be an RNA or a protein. For type I and type III loci, the antitoxins are RNAs; however, they have very different modes of action. Type I antitoxins repress toxin protein expression through interacting with the toxin mRNA, thereby targeting the mRNA for degradation or preventing its translation or both; type III antitoxins directly bind to the toxin protein, sequestering it. Along with these two very different modes of action for the antitoxin, there are differences in the functions of the toxin proteins and the mobility of these loci between species. Within this review, we discuss the major differences as to how the RNAs repress toxin activity, the potential consequences for utilizing different regulatory strategies, as well as the confirmed and potential biological roles for these loci across bacterial species.

  11. Reconstruction and logical modeling of glucose repression signaling pathways in Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    Oliveira Ana

    2009-01-01

    Full Text Available Abstract Background In the yeast Saccharomyces cerevisiae, the presence of high levels of glucose leads to an array of down-regulatory effects known as glucose repression. This process is complex due to the presence of feedback loops and crosstalk between different pathways, complicating the use of intuitive approaches to analyze the system. Results We established a logical model of yeast glucose repression, formalized as a hypergraph. The model was constructed based on verified regulatory interactions and it includes 50 gene transcripts, 22 proteins, 5 metabolites and 118 hyperedges. We computed the logical steady states of all nodes in the network in order to simulate wildtype and deletion mutant responses to different sugar availabilities. Evaluation of the model predictive power was achieved by comparing changes in the logical state of gene nodes with transcriptome data. Overall, we observed 71% true predictions, and analyzed sources of errors and discrepancies for the remaining. Conclusion Though the binary nature of logical (Boolean models entails inherent limitations, our model constitutes a primary tool for storing regulatory knowledge, searching for incoherencies in hypotheses and evaluating the effect of deleting regulatory elements involved in glucose repression.

  12. Quorum regulatory small RNAs repress type VI secretion in Vibrio cholerae.

    Science.gov (United States)

    Shao, Yi; Bassler, Bonnie L

    2014-06-01

    Type VI secretion is critical for Vibrio cholerae to successfully combat phagocytic eukaryotes and to survive in the presence of competing bacterial species. V. cholerae type VI secretion system genes are encoded in one large and two small clusters. In V. cholerae, type VI secretion is controlled by quorum sensing, the cell-cell communication process that enables bacteria to orchestrate group behaviours. The quorum-sensing response regulator LuxO represses type VI secretion genes at low cell density and the quorum-sensing regulator HapR activates type VI secretion genes at high cell density. We demonstrate that the quorum regulatory small RNAs (Qrr sRNAs) that function between LuxO and HapR in the quorum-sensing cascade are required for these regulatory effects. The Qrr sRNAs control type VI secretion via two mechanisms: they repress expression of the large type VI secretion system cluster through base pairing and they repress HapR, the activator of the two small type VI secretion clusters. This regulatory arrangement ensures that the large cluster encoding many components of the secretory machine is expressed prior to the two small clusters that encode the secreted effectors. Qrr sRNA-dependent regulation of the type VI secretion system is conserved in pandemic and non-pandemic V. cholerae strains.

  13. KLF4 regulates adult lung tumor-initiating cells and represses K-Ras-mediated lung cancer.

    Science.gov (United States)

    Yu, T; Chen, X; Zhang, W; Liu, J; Avdiushko, R; Napier, D L; Liu, A X; Neltner, J M; Wang, C; Cohen, D; Liu, C

    2016-02-01

    Lung cancer is the leading cause of cancer-related mortality in both men and women worldwide. To identify novel factors that contribute to lung cancer pathogenesis, we analyzed a lung cancer database from The Cancer Genome Atlas and found that Krüppel-like Factor 4 (KLF4) expression is significantly lower in patients' lung cancer tissue than in normal lung tissue. In addition, we identified seven missense mutations in the KLF4 gene. KLF4 is a transcription factor that regulates cell proliferation and differentiation as well as the self-renewal of stem cells. To understand the role of KLF4 in the lung, we generated a tamoxifen-induced Klf4 knockout mouse model. We found that KLF4 inhibits lung cancer cell growth and that depletion of Klf4 altered the differentiation pattern in the developing lung. To understand how KLF4 functions during lung tumorigenesis, we generated the K-ras(LSL-G12D/+);Klf4(fl/fl) mouse model, and we used adenovirus-expressed Cre to induce K-ras activation and Klf4 depletion in the lung. Although Klf4 deletion alone or K-ras mutation alone can trigger lung tumor formation, Klf4 deletion combined with K-ras mutation significantly enhanced lung tumor formation. We also found that Klf4 deletion in conjunction with K-ras activation caused lung inflammation. To understand the mechanism whereby KLF4 is regulated during lung tumorigenesis, we analyzed KLF4 promoter methylation and the profiles of epigenetic factors. We found that Class I histone deacetylases (HDACs) are overexpressed in lung cancer and that HDAC inhibitors induced expression of KLF4 and inhibited proliferation of lung cancer cells, suggesting that KLF4 is probably repressed by histone acetylation and that HDACs are valuable drug targets for lung cancer treatment.

  14. Mir-29 repression in bladder outlet obstruction contributes to matrix remodeling and altered stiffness.

    Science.gov (United States)

    Ekman, Mari; Bhattachariya, Anirban; Dahan, Diana; Uvelius, Bengt; Albinsson, Sebastian; Swärd, Karl

    2013-01-01

    Recent work has uncovered a role of the microRNA (miRNA) miR-29 in remodeling of the extracellular matrix. Partial bladder outlet obstruction is a prevalent condition in older men with prostate enlargement that leads to matrix synthesis in the lower urinary tract and increases bladder stiffness. Here we tested the hypothesis that miR-29 is repressed in the bladder in outlet obstruction and that this has an impact on protein synthesis and matrix remodeling leading to increased bladder stiffness. c-Myc, NF-κB and SMAD3, all of which repress miR-29, were activated in the rat detrusor following partial bladder outlet obstruction but at different times. c-Myc and NF-κB activation occurred early after obstruction, and SMAD3 phosphorylation increased later, with a significant elevation at 6 weeks. c-Myc, NF-κB and SMAD3 activation, respectively, correlated with repression of miR-29b and miR-29c at 10 days of obstruction and with repression of miR-29c at 6 weeks. An mRNA microarray analysis showed that the reduction of miR-29 following outlet obstruction was associated with increased levels of miR-29 target mRNAs, including mRNAs for tropoelastin, the matricellular protein Sparc and collagen IV. Outlet obstruction increased protein levels of eight out of eight examined miR-29 targets, including tropoelastin and Sparc. Transfection of human bladder smooth muscle cells with antimiR-29c and miR-29c mimic caused reciprocal changes in target protein levels in vitro. Tamoxifen inducible and smooth muscle-specific deletion of Dicer in mice reduced miR-29 expression and increased tropoelastin and the thickness of the basal lamina surrounding smooth muscle cells in the bladder. It also increased detrusor stiffness independent of outlet obstruction. Taken together, our study supports a model where the combined repressive influences of c-Myc, NF-κB and SMAD3 reduce miR-29 in bladder outlet obstruction, and where the resulting drop in miR-29 contributes to matrix remodeling and

  15. Mir-29 repression in bladder outlet obstruction contributes to matrix remodeling and altered stiffness.

    Directory of Open Access Journals (Sweden)

    Mari Ekman

    Full Text Available Recent work has uncovered a role of the microRNA (miRNA miR-29 in remodeling of the extracellular matrix. Partial bladder outlet obstruction is a prevalent condition in older men with prostate enlargement that leads to matrix synthesis in the lower urinary tract and increases bladder stiffness. Here we tested the hypothesis that miR-29 is repressed in the bladder in outlet obstruction and that this has an impact on protein synthesis and matrix remodeling leading to increased bladder stiffness. c-Myc, NF-κB and SMAD3, all of which repress miR-29, were activated in the rat detrusor following partial bladder outlet obstruction but at different times. c-Myc and NF-κB activation occurred early after obstruction, and SMAD3 phosphorylation increased later, with a significant elevation at 6 weeks. c-Myc, NF-κB and SMAD3 activation, respectively, correlated with repression of miR-29b and miR-29c at 10 days of obstruction and with repression of miR-29c at 6 weeks. An mRNA microarray analysis showed that the reduction of miR-29 following outlet obstruction was associated with increased levels of miR-29 target mRNAs, including mRNAs for tropoelastin, the matricellular protein Sparc and collagen IV. Outlet obstruction increased protein levels of eight out of eight examined miR-29 targets, including tropoelastin and Sparc. Transfection of human bladder smooth muscle cells with antimiR-29c and miR-29c mimic caused reciprocal changes in target protein levels in vitro. Tamoxifen inducible and smooth muscle-specific deletion of Dicer in mice reduced miR-29 expression and increased tropoelastin and the thickness of the basal lamina surrounding smooth muscle cells in the bladder. It also increased detrusor stiffness independent of outlet obstruction. Taken together, our study supports a model where the combined repressive influences of c-Myc, NF-κB and SMAD3 reduce miR-29 in bladder outlet obstruction, and where the resulting drop in miR-29 contributes to

  16. Cas9 Nickase-Assisted RNA Repression Enables Stable and Efficient Manipulation of Essential Metabolic Genes in Clostridium cellulolyticum

    Directory of Open Access Journals (Sweden)

    Tao Xu

    2017-09-01

    Full Text Available Essential gene functions remain largely underexplored in bacteria. Clostridium cellulolyticum is a promising candidate for consolidated bioprocessing; however, its genetic manipulation to reduce the formation of less-valuable acetate is technically challenging due to the essentiality of acetate-producing genes. Here we developed a Cas9 nickase-assisted chromosome-based RNA repression to stably manipulate essential genes in C. cellulolyticum. Our plasmid-based expression of antisense RNA (asRNA molecules targeting the phosphotransacetylase (pta gene successfully reduced the enzymatic activity by 35% in cellobiose-grown cells, metabolically decreased the acetate titer by 15 and 52% in wildtype transformants on cellulose and xylan, respectively. To control both acetate and lactate simultaneously, we transformed the repression plasmid into lactate production-deficient mutant and found the plasmid delivery reduced acetate titer by more than 33%, concomitant with negligible lactate formation. The strains with pta gene repression generally diverted more carbon into ethanol. However, further testing on chromosomal integrants that were created by double-crossover recombination exhibited only very weak repression because DNA integration dramatically lessened gene dosage. With the design of a tandem repetitive promoter-driven asRNA module and the use of a new Cas9 nickase genome editing tool, a chromosomal integrant (LM3P was generated in a single step and successfully enhanced RNA repression, with a 27% decrease in acetate titer on cellulose in antibiotic-free medium. These results indicate the effectiveness of tandem promoter-driven RNA repression modules in promoting gene repression in chromosomal integrants. Our combinatorial method using a Cas9 nickase genome editing tool to integrate the gene repression module demonstrates easy-to-use and high-efficiency advantages, paving the way for stably manipulating genes, even essential ones, for functional

  17. Political Repressions by Senior Offices of Transbaikal Military District Case of Tank Squadron Commander M.M. Zakharov

    Directory of Open Access Journals (Sweden)

    Vladimir S. Milbakh

    2012-12-01

    Full Text Available The article features one of the dark pages in Russian History – Mass Political Repressions in the country and in the army in 1937–1938. The starting point of repressions against the senior officers is shown on the example of Transbaikal Millitary District. The statistical data on political prisoners (chief officers, commanders, poorly disguised political cases by NKVD officers are shown. New archival files have been uncovered.

  18. Bovine Herpesvirus 1 Protein bICP0 Represses the Transcription of bISG15 in Fetal Bovine Lung Cells

    Institute of Scientific and Technical Information of China (English)

    Chang Liu; Xiao-hong Kong; Wen-tao Qiao; Yun-qi Geng

    2011-01-01

    The ubiquitin-like modifier bISG15 is an antiviral protein found in fetal bovine lung (FBL) cells.Bovine Herpesvirus 1(BHV-1),which is a viral pathogen of cattle,can infect FBL cells and induce cytopathic effects.Real-time PCR assays showed that BHV- 1 's infection could repress the basal or inducible transcription of bISG15 in FBL cells.It demonstrates that this repression effect depends on BHV-1 viral infection and new protein synthesis.Our previous work showed that bIRF-3 was the key factor in the stimulation of bISG 15 in FBL cells,so the effect of BHV-1 viral protein on bIRF-3 activating the promoter of bISG15 was confirmed.The luciferase assay showed the BHV-1 viral protein bICP0 inhibited the activation of bISG15 promoter stimulated by bIRF-3.Taken together,our work suggested that BHV-I had some molecular mechanism to resist the cellular bISG15'santiviral functions.

  19. Transcriptional repression of Caveolin-1 (CAV1) gene expression by GATA-6 in bladder smooth muscle hypertrophy in mice and human beings.

    Science.gov (United States)

    Boopathi, Ettickan; Gomes, Cristiano Mendes; Goldfarb, Robert; John, Mary; Srinivasan, Vittala Gopal; Alanzi, Jaber; Malkowicz, S Bruce; Kathuria, Hasmeena; Zderic, Stephen A; Wein, Alan J; Chacko, Samuel

    2011-05-01

    Hypertrophy occurs in urinary bladder wall smooth muscle (BSM) in men with partial bladder outlet obstruction (PBOO) caused by benign prostatic hyperplasia (BPH) and in animal models of PBOO. Hypertrophied BSM from the rabbit model exhibits down-regulation of caveolin-1, a structural and functional protein of caveolae that function as signaling platforms to mediate interaction between receptor proteins and adaptor and effector molecules to regulate signal generation, amplification, and diversification. Caveolin-1 expression is diminished in PBOO-induced BSM hypertrophy in mice and in men with BPH. The proximal promoter of the human and mouse caveolin-1 (CAV1) gene was characterized, and it was observed that the transcription factor GATA-6 binds this promoter, causing reduced expression of caveolin-1. Furthermore, caveolin-1 expression levels inversely correlate with the abundance of GATA-6 in BSM hypertrophy in mice and human beings. Silencing of GATA6 gene expression up-regulates caveolin-1 expression, whereas overexpression of GATA-6 protein sustains the transcriptional repression of caveolin-1 in bladder smooth muscle cells. Together, these data suggest that GATA-6 acts as a transcriptional repressor of CAV1 gene expression in PBOO-induced BSM hypertrophy in men and mice. GATA-6-induced transcriptional repression represents a new regulatory mechanism of CAV1 gene expression in pathologic BSM, and may serve as a target for new therapy for BPH-induced bladder dysfunction in aging men.

  20. Two-component signal transduction system CBO0787/CBO0786 represses transcription from botulinum neurotoxin promoters in Clostridium botulinum ATCC 3502.

    Science.gov (United States)

    Zhang, Zhen; Korkeala, Hannu; Dahlsten, Elias; Sahala, Elina; Heap, John T; Minton, Nigel P; Lindström, Miia

    2013-03-01

    Blocking neurotransmission, botulinum neurotoxin is the most poisonous biological substance known to mankind. Despite its infamy as the scourge of the food industry, the neurotoxin is increasingly used as a pharmaceutical to treat an expanding range of muscle disorders. Whilst neurotoxin expression by the spore-forming bacterium Clostridium botulinum appears tightly regulated, to date only positive regulatory elements, such as the alternative sigma factor BotR, have been implicated in this control. The identification of negative regulators has proven to be elusive. Here, we show that the two-component signal transduction system CBO0787/CBO0786 negatively regulates botulinum neurotoxin expression. Single insertional inactivation of cbo0787 encoding a sensor histidine kinase, or of cbo0786 encoding a response regulator, resulted in significantly elevated neurotoxin gene expression levels and increased neurotoxin production. Recombinant CBO0786 regulator was shown to bind to the conserved -10 site of the core promoters of the ha and ntnh-botA operons, which encode the toxin structural and accessory proteins. Increasing concentration of CBO0786 inhibited BotR-directed transcription from the ha and ntnh-botA promoters, demonstrating direct transcriptional repression of the ha and ntnh-botA operons by CBO0786. Thus, we propose that CBO0786 represses neurotoxin gene expression by blocking BotR-directed transcription from the neurotoxin promoters. This is the first evidence of a negative regulator controlling botulinum neurotoxin production. Understanding the neurotoxin regulatory mechanisms is a major target of the food and pharmaceutical industries alike.

  1. Multiple defects in the respiratory chain lead to the repression of genes encoding components of the respiratory chain and TCA cycle enzymes.

    Science.gov (United States)

    Bourges, Ingrid; Mucchielli, Marie-Helene; Herbert, Christopher J; Guiard, Bernard; Dujardin, Geneviève; Meunier, Brigitte

    2009-04-17

    Respiratory complexes III, IV and V are formed by components of both nuclear and mitochondrial origin and are embedded in the inner mitochondrial membrane. Their assembly requires the auxiliary factor Oxa1, and the absence of this protein has severe consequences on these three major respiratory chain enzymes. We have studied, in the yeast Saccharomyces cerevisiae, the effect of the loss of Oxa1 function and of other respiratory defects on the expression of nuclear genes encoding components of the respiratory complexes and tricarboxylic acid cycle enzymes. We observed that the concomitant decrease in the level of two respiratory enzymes, complexes III and IV, led to their repression. These genes are known targets of the transcriptional activator complex Hap2/3/4/5 that plays a central role in the reprogramming of yeast metabolism when cells switch from a fermenting, glucose-repressed state to a respiring, derepressed state. We found that the Hap4 protein, the regulatory subunit of the transcriptional complex, was present at a lower level in the oxa1 mutants whereas no change in HAP4 transcript level was observed, suggesting a posttranscriptional modulation. In addition, an altered mitochondrial morphology was observed in mutants with decreased expression of Hap2/3/4/5 target genes. We suggest that the aberrant mitochondrial morphology, presumably caused by the severely decreased level of at least two respiratory enzymes, might be part of the signalling pathway linking the mitochondrial defect and Hap2/3/4/5.

  2. Pregnane X receptor (PXR-mediated gene repression and cross-talk of PXR with other nuclear receptors via coactivator interactions

    Directory of Open Access Journals (Sweden)

    Petr Pavek

    2016-11-01

    Full Text Available Pregnane X receptor is a ligand-activated nuclear receptor that mainly controls inducible expression of xenobiotics handling genes including biotransformation enzymes and drug transporters. Nowadays it is clear that PXR is also involved in regulation of intermediate metabolism through trans-activation and trans-repression of genes controlling glucose, lipid, cholesterol, bile acid and bilirubin homeostasis. In these processes PXR cross-talks with other nuclear receptors. Accumulating evidence suggests that the cross-talk is often mediated by competing for common coactivators or by disruption of coactivation and activity of other transcription factors by the ligand-activated PXR. In this respect mainly PXR-CAR and PXR-HNF4α interference have been reported and several cytochrome P450 enzymes (such as CYP7A1 and CYP8B1, phase II enzymes (SULT1E1, Gsta2, Ugt1a1, drug and endobiotic transporters (OCT1, Mrp2, Mrp3, Oatp1a and Oatp4 as well as intermediate metabolism enzymes (PEPCK1 and G6Pase have been shown as down-regulated genes after PXR activation. In this review, I summarize our current knowledge of PXR-mediated repression and coactivation interference in PXR-controlled gene expression regulation.

  3. Pregnane X Receptor (PXR)-Mediated Gene Repression and Cross-Talk of PXR with Other Nuclear Receptors via Coactivator Interactions

    Science.gov (United States)

    Pavek, Petr

    2016-01-01

    Pregnane X receptor is a ligand-activated nuclear receptor (NR) that mainly controls inducible expression of xenobiotics handling genes including biotransformation enzymes and drug transporters. Nowadays it is clear that PXR is also involved in regulation of intermediate metabolism through trans-activation and trans-repression of genes controlling glucose, lipid, cholesterol, bile acid, and bilirubin homeostasis. In these processes PXR cross-talks with other NRs. Accumulating evidence suggests that the cross-talk is often mediated by competing for common coactivators or by disruption of coactivation and activity of other transcription factors by the ligand-activated PXR. In this respect mainly PXR-CAR and PXR-HNF4α interference have been reported and several cytochrome P450 enzymes (such as CYP7A1 and CYP8B1), phase II enzymes (SULT1E1, Gsta2, Ugt1a1), drug and endobiotic transporters (OCT1, Mrp2, Mrp3, Oatp1a, and Oatp4) as well as intermediate metabolism enzymes (PEPCK1 and G6Pase) have been shown as down-regulated genes after PXR activation. In this review, I summarize our current knowledge of PXR-mediated repression and coactivation interference in PXR-controlled gene expression regulation. PMID:27932985

  4. Signaling from the embryo conditions Vp1-mediated repression of alpha-amylase genes in the aleurone of developing maize seeds.

    Science.gov (United States)

    Hoecker, U; Vasil, I K; McCarty, D R

    1999-08-01

    The VP1 transcription factor functions as both a repressor and an activator of gene expression in the developing aleurone. Vp1 activation of the anthocyanin pathway exhibits strict cell autonomy in aleurone. In contrast, Vp1-mediated repression of hydrolase genes in aleurone cells during seed development is determined by a combination of cell autonomous and cell non-autonomous signals. To analyze signaling between the embryo and aleurone during seed development, a T-B3La chromosome translocation was used to create seed that has non-concordant embryo and endosperm genotypes. We show that de-repression of an Amy-GUS reporter gene in developing vp1 mutant aleurone cells strongly depends on the presence of a viviparous embryo. Genetic ablation of the developing embryo in vp1 mutant and Vp1 seeds through the introduction of an early embryo mutation caused a similar enhancement of Amy-GUS expression in the aleurone, suggesting that the quiescent embryo present in normal seed is a critical source of inhibitory signals. Analysis of an ABA deficient vp1 vp5 double mutant indicates that ABA synthesized in the embyro interacts additively with Vp1 to prevent precocious induction of alpha-amylase genes in the aleurone of the developing seed. A lack of ABA synthesis, however, does not account for the strongly synergistic interaction between a viviparous vp1 embryo and mutant aleurone suggesting that a quiescent embyro is a source of other inhibitory signals.

  5. UTX inhibits EMT-induced breast CSC properties by epigenetic repression of EMT genes in cooperation with LSD1 and HDAC1.

    Science.gov (United States)

    Choi, Hee-Joo; Park, Ji-Hye; Park, Mikyung; Won, Hee-Young; Joo, Hyeong-Seok; Lee, Chang Hoon; Lee, Jeong-Yeon; Kong, Gu

    2015-10-01

    The histone H3K27 demethylase, UTX, is a known component of the H3K4 methyltransferase MLL complex, but its functional association with H3K4 methylation in human cancers remains largely unknown. Here we demonstrate that UTX loss induces epithelial-mesenchymal transition (EMT)-mediated breast cancer stem cell (CSC) properties by increasing the expression of the SNAIL, ZEB1 and ZEB2 EMT transcription factors (EMT-TFs) and of the transcriptional repressor CDH1. UTX facilitates the epigenetic silencing of EMT-TFs by inducing competition between MLL4 and the H3K4 demethylase LSD1. EMT-TF promoters are occupied by c-Myc and MLL4, and UTX recognizes these proteins, interrupting their transcriptional activation function. UTX decreases H3K4me2 and H3 acetylation at these promoters by forming a transcriptional repressive complex with LSD1, HDAC1 and DNMT1. Taken together, our findings indicate that UTX is a prominent tumour suppressor that functions as a negative regulator of EMT-induced CSC-like properties by epigenetically repressing EMT-TFs. © 2015 The Authors.

  6. Gene Repression in Haloarchaea Using the CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)-Cas I-B System*

    Science.gov (United States)

    Stachler, Aris-Edda; Marchfelder, Anita

    2016-01-01

    The clustered regularly interspaced short palindromic repeats (CRISPR)-Cas system is used by bacteria and archaea to fend off foreign genetic elements. Since its discovery it has been developed into numerous applications like genome editing and regulation of transcription in eukaryotes and bacteria. For archaea currently no tools for transcriptional repression exist. Because molecular biology analyses in archaea become more and more widespread such a tool is vital for investigating the biological function of essential genes in archaea. Here we use the model archaeon Haloferax volcanii to demonstrate that its endogenous CRISPR-Cas system I-B can be harnessed to repress gene expression in archaea. Deletion of cas3 and cas6b genes results in efficient repression of transcription. crRNAs targeting the promoter region reduced transcript levels down to 8%. crRNAs targeting the reading frame have only slight impact on transcription. crRNAs that target the coding strand repress expression only down to 88%, whereas crRNAs targeting the template strand repress expression down to 8%. Repression of an essential gene results in reduction of transcription levels down to 22%. Targeting efficiencies can be enhanced by expressing a catalytically inactive Cas3 mutant. Genes can be targeted on plasmids or on the chromosome, they can be monocistronic or part of a polycistronic operon. PMID:27226589

  7. Gene Repression in Haloarchaea Using the CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)-Cas I-B System.

    Science.gov (United States)

    Stachler, Aris-Edda; Marchfelder, Anita

    2016-07-15

    The clustered regularly interspaced short palindromic repeats (CRISPR)-Cas system is used by bacteria and archaea to fend off foreign genetic elements. Since its discovery it has been developed into numerous applications like genome editing and regulation of transcription in eukaryotes and bacteria. For archaea currently no tools for transcriptional repression exist. Because molecular biology analyses in archaea become more and more widespread such a tool is vital for investigating the biological function of essential genes in archaea. Here we use the model archaeon Haloferax volcanii to demonstrate that its endogenous CRISPR-Cas system I-B can be harnessed to repress gene expression in archaea. Deletion of cas3 and cas6b genes results in efficient repression of transcription. crRNAs targeting the promoter region reduced transcript levels down to 8%. crRNAs targeting the reading frame have only slight impact on transcription. crRNAs that target the coding strand repress expression only down to 88%, whereas crRNAs targeting the template strand repress expression down to 8%. Repression of an essential gene results in reduction of transcription levels down to 22%. Targeting efficiencies can be enhanced by expressing a catalytically inactive Cas3 mutant. Genes can be targeted on plasmids or on the chromosome, they can be monocistronic or part of a polycistronic operon. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  8. Stability of XIST repression in relation to genomic imprinting following global genome demethylation in a human cell line

    Energy Technology Data Exchange (ETDEWEB)

    Araújo, E.S.S. de [Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP (Brazil); Centro Internacional de Pesquisa, A.C. Camargo Cancer Center, São Paulo, SP (Brazil); Vasques, L.R. [Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP (Brazil); Stabellini, R.; Krepischi, A.C.V. [Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP (Brazil); Centro Internacional de Pesquisa, A.C. Camargo Cancer Center, São Paulo, SP (Brazil); Pereira, L.V. [Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP (Brazil)

    2014-10-17

    DNA methylation is essential in X chromosome inactivation and genomic imprinting, maintaining repression of XIST in the active X chromosome and monoallelic repression of imprinted genes. Disruption of the DNA methyltransferase genes DNMT1 and DNMT3B in the HCT116 cell line (DKO cells) leads to global DNA hypomethylation and biallelic expression of the imprinted gene IGF2 but does not lead to reactivation of XIST expression, suggesting that XIST repression is due to a more stable epigenetic mark than imprinting. To test this hypothesis, we induced acute hypomethylation in HCT116 cells by 5-aza-2′-deoxycytidine (5-aza-CdR) treatment (HCT116-5-aza-CdR) and compared that to DKO cells, evaluating DNA methylation by microarray and monitoring the expression of XIST and imprinted genes IGF2, H19, and PEG10. Whereas imprinted genes showed biallelic expression in HCT116-5-aza-CdR and DKO cells, the XIST locus was hypomethylated and weakly expressed only under acute hypomethylation conditions, indicating the importance of XIST repression in the active X to cell survival. Given that DNMT3A is the only active DNMT in DKO cells, it may be responsible for ensuring the repression of XIST in those cells. Taken together, our data suggest that XIST repression is more tightly controlled than genomic imprinting and, at least in part, is due to DNMT3A.

  9. let-7 Modulates Chromatin Configuration and Target Gene Repression through Regulation of the ARID3B Complex

    Directory of Open Access Journals (Sweden)

    Tsai-Tsen Liao

    2016-01-01

    Full Text Available Let-7 is crucial for both stem cell differentiation and tumor suppression. Here, we demonstrate a chromatin-dependent mechanism of let-7 in regulating target gene expression in cancer cells. Let-7 directly represses the expression of AT-rich interacting domain 3B (ARID3B, ARID3A, and importin-9. In the absence of let-7, importin-9 facilitates the nuclear import of ARID3A, which then forms a complex with ARID3B. The nuclear ARID3B complex recruits histone demethylase 4C to reduce histone 3 lysine 9 trimethylation and promotes the transcription of stemness factors. Functionally, expression of ARID3B is critical for the tumor initiation in let-7-depleted cancer cells. An inverse association between let-7 and ARID3A/ARID3B and prognostic significance is demonstrated in head and neck cancer patients. These results highlight a chromatin-dependent mechanism where let-7 regulates cancer stemness through ARID3B.

  10. Bar represses dPax2 and decapentaplegic to regulate cell fate and morphogenetic cell death in Drosophila eye.

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    Jongkyun Kang

    Full Text Available The coordinated regulation of cell fate and cell survival is crucial for normal pattern formation in developing organisms. In Drosophila compound eye development, crystalline arrays of hexagonal ommatidia are established by precise assembly of diverse cell types, including the photoreceptor cells, cone cells and interommatidial (IOM pigment cells. The molecular basis for controlling the number of cone and IOM pigment cells during ommatidial pattern formation is not well understood. Here we present evidence that BarH1 and BarH2 homeobox genes are essential for eye patterning by inhibiting excess cone cell differentiation and promoting programmed death of IOM cells. Specifically, we show that loss of Bar from the undifferentiated retinal precursor cells leads to ectopic expression of Prospero and dPax2, two transcription factors essential for cone cell specification, resulting in excess cone cell differentiation. We also show that loss of Bar causes ectopic expression of the TGFβ homolog Decapentaplegic (Dpp posterior to the morphogenetic furrow in the larval eye imaginal disc. The ectopic Dpp expression is not responsible for the formation of excess cone cells in Bar loss-of-function mutant eyes. Instead, it causes reduction in IOM cell death in the pupal stage by antagonizing the function of pro-apoptotic gene reaper. Taken together, this study suggests a novel regulatory mechanism in the control of developmental cell death in which the repression of Dpp by Bar in larval eye disc is essential for IOM cell death in pupal retina.

  11. Kinetic and Energetic Parameters of Carob Wastes Fermentation by Saccharomyces cerevisiae: Crabtree Effect, Ethanol Toxicity, and Invertase Repression.

    Science.gov (United States)

    Rodrigues, B; Peinado, J M; Raposo, S; Constantino, A; Quintas, C; Lima-Costa, M E

    2015-06-01

    Carob waste is a useful raw material for the second-generation ethanol because 50% of its dry weight is sucrose, glucose, and fructose. To optimize the process, we have studied the influence of the initial concentration of sugars on the fermentation performance of Saccharomyces cerevisiae. With initial sugar concentrations (S0) of 20 g/l, the yeasts were derepressed and the ethanol produced during the exponential phase was consumed in a diauxic phase. The rate of ethanol consumption decreased with increasing S0 and disappeared at 250 g/l when the Crabtree effect was complete and almost all the sugar consumed was transformed into ethanol with a yield factor of 0.42 g/g. Sucrose hydrolysis was delayed at high S0 because of glucose repression of invertase synthesis, which was triggered at concentrations above 40 g/l. At S0 higher than 250 g/l, even when glucose had been exhausted, sucrose was hydrolyzed very slowly, probably due to an inhibition at this low water activity. Although with lower metabolic rates and longer times of fermentation, 250 g/l is considered the optimal initial concentration because it avoids the diauxic consumption of ethanol and maintains enough invertase activity to consume all the sucrose, and also avoids the inhibitions due to lower water activities at higher S0.

  12. Tbx2 terminates shh/fgf signaling in the developing mouse limb bud by direct repression of gremlin1.

    Science.gov (United States)

    Farin, Henner F; Lüdtke, Timo H-W; Schmidt, Martina K; Placzko, Susann; Schuster-Gossler, Karin; Petry, Marianne; Christoffels, Vincent M; Kispert, Andreas

    2013-01-01

    Vertebrate limb outgrowth is driven by a positive feedback loop that involves Sonic hedgehog (Shh) and Gremlin1 (Grem1) in the posterior limb bud mesenchyme and Fibroblast growth factors (Fgfs) in the overlying epithelium. Proper spatio-temporal control of these signaling activities is required to avoid limb malformations such as polydactyly. Here we show that, in Tbx2-deficient hindlimbs, Shh/Fgf4 signaling is prolonged, resulting in increased limb bud size and duplication of digit 4. In turn, limb-specific Tbx2 overexpression leads to premature termination of this signaling loop with smaller limbs and reduced digit number as phenotypic manifestation. We show that Tbx2 directly represses Grem1 in distal regions of the posterior limb mesenchyme allowing Bone morphogenetic protein (Bmp) signaling to abrogate Fgf4/9/17 expression in the overlying epithelium. Since Tbx2 itself is a target of Bmp signaling, our data identify a growth-inhibiting positive feedback loop (Bmp/Tbx2/Grem1). We propose that proliferative expansion of Tbx2-expressing cells mediates self-termination of limb bud outgrowth due to their refractoriness to Grem1 induction.

  13. AATF/Che-1 acts as a phosphorylation-dependent molecular modulator to repress p53-driven apoptosis.

    Science.gov (United States)

    Höpker, Katja; Hagmann, Henning; Khurshid, Safiya; Chen, Shuhua; Hasskamp, Pia; Seeger-Nukpezah, Tamina; Schilberg, Katharina; Heukamp, Lukas; Lamkemeyer, Tobias; Sos, Martin L; Thomas, Roman K; Lowery, Drew; Roels, Frederik; Fischer, Matthias; Liebau, Max C; Resch, Ulrike; Kisner, Tülay; Röther, Fabian; Bartram, Malte P; Müller, Roman Ulrich; Fabretti, Francesca; Kurschat, Peter; Schumacher, Björn; Gaestel, Matthias; Medema, René H; Yaffe, Michael B; Schermer, Bernhard; Reinhardt, H Christian; Benzing, Thomas

    2012-10-17

    Following genotoxic stress, cells activate a complex signalling network to arrest the cell cycle and initiate DNA repair or apoptosis. The tumour suppressor p53 lies at the heart of this DNA damage response. However, it remains incompletely understood, which signalling molecules dictate the choice between these different cellular outcomes. Here, we identify the transcriptional regulator apoptosis-antagonizing transcription factor (AATF)/Che-1 as a critical regulator of the cellular outcome of the p53 response. Upon genotoxic stress, AATF is phosphorylated by the checkpoint kinase MK2. Phosphorylation results in the release of AATF from cytoplasmic MRLC3 and subsequent nuclear translocation where AATF binds to the PUMA, BAX and BAK promoter regions to repress p53-driven expression of these pro-apoptotic genes. In xenograft experiments, mice exhibit a dramatically enhanced response of AATF-depleted tumours following genotoxic chemotherapy with adriamycin. The exogenous expression of a phospho-mimicking AATF point mutant results in marked adriamycin resistance in vivo. Nuclear AATF enrichment appears to be selected for in p53-proficient endometrial cancers. Furthermore, focal copy number gains at the AATF locus in neuroblastoma, which is known to be almost exclusively p53-proficient, correlate with an adverse prognosis and reduced overall survival. These data identify the p38/MK2/AATF signalling module as a critical repressor of p53-driven apoptosis and commend this pathway as a target for DNA damage-sensitizing therapeutic regimens.

  14. QapR (PA5506) represses an operon that negatively affects the Pseudomonas quinolone signal in Pseudomonas aeruginosa.

    Science.gov (United States)

    Tipton, Kyle A; Coleman, James P; Pesci, Everett C

    2013-08-01

    Pseudomonas aeruginosa is a Gram-negative, opportunistic pathogen that can cause disease in varied sites within the human body and is a significant source of morbidity and mortality in those afflicted with cystic fibrosis. P. aeruginosa is able to coordinate group behaviors, such as virulence factor production, through the process of cell-to-cell signaling. There are three intercellular signaling systems employed by P. aeruginosa, and one of these systems utilizes the small molecule 2-heptyl-3-hydroxy-4-quinolone (Pseudomonas quinolone signal [PQS]). PQS is required for virulence in multiple infection models and has been found in the lungs of cystic fibrosis patients colonized by P. aeruginosa. In this study, we have identified an RpiR family transcriptional regulator, QapR, which is an autoregulatory repressor. We found that mutation of qapR caused overexpression of the qapR operon. We characterized the qapR operon to show that it contains genes qapR, PA5507, PA5508, and PA5509 and that QapR directly controls the transcription of these genes in a negative manner. We also show that derepression of this operon greatly reduces PQS concentration in P. aeruginosa. Our results suggest that qapR affects PQS concentration by repressing an enzymatic pathway that acts on PQS or a PQS precursor to lower the PQS concentration. We believe that this operon comprises a novel mechanism to regulate PQS concentration in P. aeruginosa.

  15. Using phenotype microarrays to determine culture conditions that induce or repress toxin production by Clostridium difficile and other microorganisms.

    Directory of Open Access Journals (Sweden)

    Xiang-He Lei

    Full Text Available Toxin production is a central issue in the pathogenesis of Clostridium difficile and many other pathogenic microorganisms. Toxin synthesis is influenced by a variety of known and unknown factors of genetics, physiology, and environment. To facilitate the study of toxin production by C. difficile, we have developed a new, reliable, quantitative, and robust cell-based cytotoxicity assay. Then we combined this new assay with Phenotype MicroArrays (PM technology which provides high throughput testing of culture conditions. This allowed us to quantitatively measure toxin production by C. difficile type strain ATCC 9689 under 768 culture conditions. The culture conditions include different carbon, nitrogen, phosphorus, and sulfur sources. Among these, 89 conditions produced strong toxin induction and 31 produced strong toxin repression. Strong toxin inducers included adenine, guanosine, arginine dipeptides, γ-D-Glu-Gly, methylamine, and others. Some leucine dipeptides and the triple-leucine tripeptide were among the strongest toxin repressors. While some results are consistent with previous observations, others are new observations that provide insights into toxin regulation and pathogenesis of C. difficile. Additionally, we have demonstrated that this combined assay technology can be applied broadly to a wide range of toxin producing microorganisms. This study is the first demonstration of simultaneous assessment of a large number of culture conditions influencing bacterial toxin production. The new functional cytotoxin quantitation method developed provides a valuable tool for studying toxigenic microorganisms and may also find applications in clinical and epidemiological research.

  16. The Polyphenol Fisetin Protects Bone by Repressing NF-κB and MKP-1-Dependent Signaling Pathways in Osteoclasts

    Science.gov (United States)

    Léotoing, Laurent; Wauquier, Fabien; Guicheux, Jérôme; Miot-Noirault, Elisabeth; Wittrant, Yohann; Coxam, Véronique

    2013-01-01

    Osteoporosis is a bone pathology leading to increase fractures risk and challenging quality of life. Since current treatments could exhibit deleterious side effects, the use of food compounds derived from plants represents a promising innovative alternative due to their potential therapeutic and preventive activities against human diseases. In this study, we investigated the ability of the polyphenol fisetin to counter osteoporosis and analyzed the cellular and molecular mechanisms involved. In vivo, fisetin consumption significantly prevented bone loss in estrogen deficiency and inflammation mice osteoporosis models. Indeed, bone mineral density, micro-architecture parameters and bone markers were positively modulated by fisetin. Consistent with in vivo results, we showed that fisetin represses RANKL-induced osteoclast differentiation and activity as demonstrated by an inhibition of multinucleated cells formation, TRAP activity and differentiation genes expression. The signaling pathways NF-κB, p38 MAPK, JNK and the key transcription factors c-Fos and NFATc1 expressions induced by RANKL, were negatively regulated by fisetin. We further showed that fisetin inhibits the constitutive proteasomal degradation of MKP-1, the phosphatase that deactivates p38 and JNK. Consistently, using shRNA stable cell lines, we demonstrated that impairment of MKP-1 decreases fisetin potency. Taken together, these results strongly support that fisetin should be further considered as a bone protective agent. PMID:23861901

  17. The polyphenol fisetin protects bone by repressing NF-κB and MKP-1-dependent signaling pathways in osteoclasts.

    Directory of Open Access Journals (Sweden)

    Laurent Léotoing

    Full Text Available Osteoporosis is a bone pathology leading to increase fractures risk and challenging quality of life. Since current treatments could exhibit deleterious side effects, the use of food compounds derived from plants represents a promising innovative alternative due to their potential therapeutic and preventive activities against human diseases. In this study, we investigated the ability of the polyphenol fisetin to counter osteoporosis and analyzed the cellular and molecular mechanisms involved. In vivo, fisetin consumption significantly prevented bone loss in estrogen deficiency and inflammation mice osteoporosis models. Indeed, bone mineral density, micro-architecture parameters and bone markers were positively modulated by fisetin. Consistent with in vivo results, we showed that fisetin represses RANKL-induced osteoclast differentiation and activity as demonstrated by an inhibition of multinucleated cells formation, TRAP activity and differentiation genes expression. The signaling pathways NF-κB, p38 MAPK, JNK and the key transcription factors c-Fos and NFATc1 expressions induced by RANKL, were negatively regulated by fisetin. We further showed that fisetin inhibits the constitutive proteasomal degradation of MKP-1, the phosphatase that deactivates p38 and JNK. Consistently, using shRNA stable cell lines, we demonstrated that impairment of MKP-1 decreases fisetin potency. Taken together, these results strongly support that fisetin should be further considered as a bone protective agent.

  18. Telomeric associated sequences of Drosophila recruit polycomb-group proteins in vivo and can induce pairing-sensitive repression.

    Science.gov (United States)

    Boivin, Antoine; Gally, Christelle; Netter, Sophie; Anxolabéhère, Dominique; Ronsseray, Stéphane

    2003-05-01

    In Drosophila, relocation of a euchromatic gene near centromeric or telomeric heterochromatin often leads to its mosaic silencing. Nevertheless, modifiers of centromeric silencing do not affect telomeric silencing, suggesting that each location requires specific factors. Previous studies suggest that a subset of Polycomb-group (PcG) proteins could be responsible for telomeric silencing. Here, we present the effect on telomeric silencing of 50 mutant alleles of the PcG genes and of their counteracting trithorax-group genes. Several combinations of two mutated PcG genes impair telomeric silencing synergistically, revealing that some of these genes are required for telomeric silencing. In situ hybridization and immunostaining experiments on polytene chromosomes revealed a strict correlation between the presence of PcG proteins and that of heterochromatic telomeric associated sequences (TASs), suggesting that TASs and PcG complexes could be associated at telomeres. Furthermore, lines harboring a transgene containing an X-linked TAS subunit and the mini-white reporter gene can exhibit pairing-sensitive repression of the white gene in an orientation-dependent manner. Finally, an additional binding site for PcG proteins was detected at the insertion site of this type of transgene. Taken together, these results demonstrate that PcG proteins bind TASs in vivo and may be major players in Drosophila telomeric position effect (TPE).

  19. The polyphenol fisetin protects bone by repressing NF-κB and MKP-1-dependent signaling pathways in osteoclasts.

    Science.gov (United States)

    Léotoing, Laurent; Wauquier, Fabien; Guicheux, Jérôme; Miot-Noirault, Elisabeth; Wittrant, Yohann; Coxam, Véronique

    2013-01-01

    Osteoporosis is a bone pathology leading to increase fractures risk and challenging quality of life. Since current treatments could exhibit deleterious side effects, the use of food compounds derived from plants represents a promising innovative alternative due to their potential therapeutic and preventive activities against human diseases. In this study, we investigated the ability of the polyphenol fisetin to counter osteoporosis and analyzed the cellular and molecular mechanisms involved. In vivo, fisetin consumption significantly prevented bone loss in estrogen deficiency and inflammation mice osteoporosis models. Indeed, bone mineral density, micro-architecture parameters and bone markers were positively modulated by fisetin. Consistent with in vivo results, we showed that fisetin represses RANKL-induced osteoclast differentiation and activity as demonstrated by an inhibition of multinucleated cells formation, TRAP activity and differentiation genes expression. The signaling pathways NF-κB, p38 MAPK, JNK and the key transcription factors c-Fos and NFATc1 expressions induced by RANKL, were negatively regulated by fisetin. We further showed that fisetin inhibits the constitutive proteasomal degradation of MKP-1, the phosphatase that deactivates p38 and JNK. Consistently, using shRNA stable cell lines, we demonstrated that impairment of MKP-1 decreases fisetin potency. Taken together, these results strongly support that fisetin should be further considered as a bone protective agent.

  20. Pax4 is not essential for beta-cell differentiation in zebrafish embryos but modulates alpha-cell generation by repressing arx gene expression.

    Science.gov (United States)

    Djiotsa, Joachim; Verbruggen, Vincianne; Giacomotto, Jean; Ishibashi, Minaka; Manning, Elisabeth; Rinkwitz, Silke; Manfroid, Isabelle; Voz, Marianne L; Peers, Bernard

    2012-12-17

    Genetic studies in mouse have demonstrated the crucial function of PAX4 in pancreatic cell differentiation. This transcription factor specifies β- and δ-cell fate at the expense of α-cell identity by repressing Arx gene expression and ectopic expression of PAX4 in α-cells is sufficient to convert them into β-cells. Surprisingly, no Pax4 orthologous gene can be found in chicken and Xenopus tropicalis raising the question of the function of pax4 gene in lower vertebrates such as in fish. In the present study, we have analyzed the expression and the function of the orthologous pax4 gene in zebrafish. pax4 gene is transiently expressed in the pancreas of zebrafish embryos and is mostly restricted to endocrine precursors as well as to some differentiating δ- and ε-cells but was not detected in differentiating β-cells. pax4 knock-down in zebrafish embryos caused a significant increase in α-cells number while having no apparent effect on β- and δ-cell differentiation. This rise of α-cells is due to an up-regulation of the Arx transcription factor. Conversely, knock-down of arx caused to a complete loss of α-cells and a concomitant increase of pax4 expression but had no effect on the number of β- and δ-cells. In addition to the mutual repression between Arx and Pax4, these two transcription factors negatively regulate the transcription of their own gene. Interestingly, disruption of pax4 RNA splicing or of arx RNA splicing by morpholinos targeting exon-intron junction sites caused a blockage of the altered transcripts in cell nuclei allowing an easy characterization of the arx- and pax4-deficient cells. Such analyses demonstrated that arx knock-down in zebrafish does not lead to a switch of cell fate, as reported in mouse, but rather blocks the cells in their differentiation process towards α-cells. In zebrafish, pax4 is not required for the generation of the first β- and δ-cells deriving from the dorsal pancreatic bud, unlike its crucial role in the

  1. The varicella-zoster virus-mediated delayed host shutoff: open reading frame 17 has no major function, whereas immediate-early 63 protein represses heterologous gene expression.

    Science.gov (United States)

    Desloges, Nathalie; Rahaus, Markus; Wolff, Manfred H

    2005-12-01

    We reported that varicella-zoster virus (VZV) causes a delayed host shutoff during its replicative cycle. VZV open reading frame 17 (ORF17) is the homologue of the herpes simplex virus (HSV) UL41 gene encoding the virion host shutoff (vhs) protein which is responsible for the shutoff effect observed in HSV-infected cells. In the present study, we demonstrated that ORF17 is expressed as a late protein during the VZV replicative cycle in different infected permissive cell lines which showed a delayed shutoff of cellular RNA. A cell line with stable expression of VZV ORF17 was infected with VZV. In these cells, VZV replication and delayed host shutoff remained unchanged when compared to normal infected cells. ORF17 was not capable of repressing the expression of the beta-gal reporter gene under the control of the human cytomegalovirus immediate-early gene promoter or to inhibit the expression of a CAT reporter gene under the control of the human GAPDH promoter, indicating that ORF17 has no major function in the VZV-mediated delayed host shutoff. To determine whether other viral factors are involved in the host shutoff, a series of cotransfection assays was performed. We found that the immediate-early 63 protein (IE63) was able to downregulate the expression of reporter genes under the control of the two heterologous promoters, indicating that this viral factor can be involved in the VZV-mediated delayed host shutoff. Other factors can be also implicated to modulate the repressing action of IE63 to achieve a precise balance between the viral and cellular gene expression.

  2. Synergy between the RE-1 silencer of transcription and NFkappaB in the repression of the neurotransmitter gene TAC1 in human mesenchymal stem cells.

    Science.gov (United States)

    Greco, Steven J; Smirnov, Sergey V; Murthy, Raghav G; Rameshwar, Pranela

    2007-10-12

    The RE-1 silencer of transcription (REST) is a transcriptional regulator that represses neuron-specific genes in non-neuronal tissues by remodeling chromatin structure. We have utilized human mesenchymal stem cells (MSCs) as a research tool to understand the molecular mechanisms that regulate a neurogenic program of differentiation in non-neuronal tissue. MSCs are mesoderm-derived cells that generate specialized cells such as stroma, fat, bone, and cartilage. We have reported previously the transdifferentiation of MSCs into functional neuronal cells (Cho, K. J., Trzaska, K. A., Greco, S. J., McArdle, J., Wang, F. S., Ye, J.-H., and Rameshwar, P. (2005) Stem Cells 23, 383-391). Expression of the neurotransmitter gene TAC1 was detected only in neuronal cells and thus served as a model to study transcriptional regulation of neuron-specific genes in undifferentiated MSCs. Bone marrow stromal cells are known to transiently express TAC1 following stimulation with the microenvironmental factor interleukin-1alpha. We thus compared the effects of interleukin-1alpha stimulation and neuronal induction of MSCs on TAC1 regulation. Transcription factor mapping of the 5'-flanking region of the TAC1 promoter predicted two REST-binding sites adjacent to one NFkappaB site within exon 1. Chromatin immunoprecipitation, mutagenesis, and loss-of-function studies showed that both transcription factors synergistically mediated repression of TAC1 in the neurogenic and microenvironmental models. Together, the results support the novel finding of synergism between REST and NFkappaB in the suppression of TAC1 in non-neuronal cells.

  3. VIB1, a link between glucose signaling and carbon catabolite repression, is essential for plant cell wall degradation by Neurospora crassa.

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    Yi Xiong

    2014-08-01

    Full Text Available Filamentous fungi that thrive on plant biomass are the major producers of hydrolytic enzymes used to decompose lignocellulose for biofuel production. Although induction of cellulases is regulated at the transcriptional level, how filamentous fungi sense and signal carbon-limited conditions to coordinate cell metabolism and regulate cellulolytic enzyme production is not well characterized. By screening a transcription factor deletion set in the filamentous fungus Neurospora crassa for mutants unable to grow on cellulosic materials, we identified a role for the transcription factor, VIB1, as essential for cellulose utilization. VIB1 does not directly regulate hydrolytic enzyme gene expression or function in cellulosic inducer signaling/processing, but affects the expression level of an essential regulator of hydrolytic enzyme genes, CLR2. Transcriptional profiling of a Δvib-1 mutant suggests that it has an improper expression of genes functioning in metabolism and energy and a deregulation of carbon catabolite repression (CCR. By characterizing new genes, we demonstrate that the transcription factor, COL26, is critical for intracellular glucose sensing/metabolism and plays a role in CCR by negatively regulating cre-1 expression. Deletion of the major player in CCR, cre-1, or a deletion of col-26, did not rescue the growth of Δvib-1 on cellulose. However, the synergistic effect of the Δcre-1; Δcol-26 mutations circumvented the requirement of VIB1 for cellulase gene expression, enzyme secretion and cellulose deconstruction. Our findings support a function of VIB1 in repressing both glucose signaling and CCR under carbon-limited conditions, thus enabling a proper cellular response for plant biomass deconstruction and utilization.

  4. SUMOylation of the KRAB zinc-finger transcription factor PARIS/ZNF746 regulates its transcriptional activity

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    Nishida, Tamotsu, E-mail: nishida@gene.mie-u.ac.jp; Yamada, Yoshiji

    2016-05-13

    Parkin-interacting substrate (PARIS), a member of the family of Krüppel-associated box (KRAB)-containing zinc-finger transcription factors, is a substrate of the ubiquitin E3 ligase parkin. PARIS represses the expression of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), although the underlying mechanisms remain largely unknown. In the present study, we demonstrate that PARIS can be SUMOylated, and its SUMOylation plays a role in the repression of PGC-1a promoter activity. Protein inhibitor of activated STAT y (PIASy) was identified as an interacting protein of PARIS and shown to enhance its SUMOylation. PIASy repressed PGC-1a promoter activity, and this effect was attenuated by PARIS in a manner dependent on its SUMOylation status. Co-expression of SUMO-1 with PIASy completely repressed PGC-1a promoter activity independently of PARIS expression. PARIS-mediated PGC-1a promoter repression depended on the activity of histone deacetylases (HDAC), whereas PIASy repressed the PGC-1a promoter in an HDAC-independent manner. Taken together, these results suggest that PARIS and PIASy modulate PGC-1a gene transcription through distinct molecular mechanisms. -- Highlights: •PARIS can be SUMOylated in vivo and in vitro. •SUMOylation of PARIS functions in the repression of PGC-1a promoter activity. •PIASy interacts with PARIS and enhances its SUMOylation. •PIASy influences PARIS-mediated repression of PGC-1a promoter activity.

  5. Repression of androgen receptor transcription through the E2F1/DNMT1 axis.

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    Conrad David Valdez

    Full Text Available Although androgen receptor (AR function has been extensively studied, regulation of the AR gene itself has been much less characterized. In this study, we observed a dramatic reduction in the expression of androgen receptor mRNA and protein in hyperproliferative prostate epithelium of keratin 5 promoter driven E2F1 transgenic mice. To confirm an inhibitory function for E2F1 on AR transcription, we showed that E2F1 inhibited the transcription of endogenous AR mRNA, subsequent AR protein, and AR promoter activity in both human and mouse epithelial cells. E2F1 also inhibited androgen-stimulated activation of two AR target gene promoters. To elucidate the molecular mechanism of E2F-mediated inhibition of AR, we evaluated the effects of two functional E2F1 mutants on AR promoter activity and found that the transactivation domain appears to mediate E2F1 repression of the AR promoter. Because DNMT1 is a functional intermediate of E2F1 we examined DNMT1 function in AR repression. Repression of endogenous AR in normal human prostate epithelial cells was relieved by DNMT1 shRNA knock down. DNMT1 was shown to be physically associated within the AR minimal promoter located 22 bps from the transcription start site; however, methylation remained unchanged at the promoter regardless of DNMT1 expression. Taken together, our results suggest that DNMT1 operates either as a functional intermediary or in cooperation with E2F1 inhibiting AR gene expression in a methylation independent manner.

  6. Nrf2-dependent repression of interleukin-12 expression in human dendritic cells exposed to inorganic arsenic.

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    Macoch, Mélinda; Morzadec, Claudie; Génard, Romain; Pallardy, Marc; Kerdine-Römer, Saadia; Fardel, Olivier; Vernhet, Laurent

    2015-11-01

    Inorganic arsenic, a well-known Nrf2 inducer, exerts immunosuppressive properties. In this context, we recently reported that the differentiation of human blood monocytes into immature dendritic cells (DCs), in the presence of low and noncytotoxic concentrations of arsenic, represses the ability of DCs to release key cytokines in response to different stimulating agents. Particularly, arsenic inhibits the expression of human interleukin-12 (IL-12, also named IL-12p70), a major proinflammatory cytokine that controls the differentiation of Th1 lymphocytes. In the present study, we determined if Nrf2 could contribute to these arsenic immunotoxic effects. To this goal, human monocyte-derived DCs were first differentiated in the absence of metalloid and then pretreated with arsenic just before DC stimulation with lipopolysaccharide (LPS). Under these experimental conditions, arsenic rapidly and stably activates Nrf2 and increases the expression of Nrf2 target genes. It also significantly inhibits IL-12 expression in activated DCs, at both mRNA and protein levels. Particularly, arsenic reduces mRNA levels of IL12A and IL12B genes which encodes the p35 and p40 subunits of IL-12p70, respectively. tert-Butylhydroquinone (tBHQ), a reference Nrf2 inducer, mimics arsenic effects and potently inhibits IL-12 expression. Genetic inhibition of Nrf2 expression markedly prevents the repression of both IL12 mRNA and IL-12 protein levels triggered by arsenic and tBHQ in human LPS-stimulated DCs. In addition, arsenic significantly reduces IL-12 mRNA levels in LPS-activated bone marrow-derived DCs from Nrf2+/+ mice but not in DCs from Nrf2-/- mice. Finally, we show that, besides IL-12, arsenic significantly reduces the expression of IL-23, another heterodimer containing the p40 subunit. In conclusion, our study demonstrated that arsenic represses IL-12 expression in human-activated DCs by specifically stimulating Nrf2 activity.

  7. Role of ND10 nuclear bodies in the chromatin repression of HSV-1.

    Science.gov (United States)

    Gu, Haidong; Zheng, Yi

    2016-04-05

    Herpes simplex virus (HSV) is a neurotropic virus that establishes lifelong latent infection in human ganglion sensory neurons. This unique life cycle necessitates an intimate relation between the host defenses and virus counteractions over the long course of infection. Two important aspects of host anti-viral defense, nuclear substructure restriction and epigenetic chromatin regulation, have been intensively studied in the recent years. Upon viral DNA entering the nucleus, components of discrete nuclear bodies termed nuclear domain 10 (ND10), converge at viral DNA and place restrictions on viral gene expression. Meanwhile the infected cell mobilizes its histones and histone-associated repressors to force the viral DNA into nucleosome-like structures and also represses viral transcription. Both anti-viral strategies are negated by various HSV countermeasures. One HSV gene transactivator, infected cell protein 0 (ICP0), is a key player in antagonizing both the ND10 restriction and chromatin repression. On one hand, ICP0 uses its E3 ubiquitin ligase activity to target major ND10 components for proteasome-dependent degradation and thereafter disrupts the ND10 nuclear bodies. On the other hand, ICP0 participates in de-repressing the HSV chromatin by changing histone composition or modification and therefore activates viral transcription. Involvement of a single viral protein in two seemingly different pathways suggests that there is coordination in host anti-viral defense mechanisms and also cooperation in viral counteraction strategies. In this review, we summarize recent advances in understanding the role of chromatin regulation and ND10 dynamics in both lytic and latent HSV infection. We focus on the new observations showing that ND10 nuclear bodies play a critical role in cellular chromatin regulation. We intend to find the connections between the two major anti-viral defense pathways, chromatin remodeling and ND10 structure, in order to achieve a better

  8. Cyclin D1 represses gluconeogenesis via inhibition of the transcriptional coactivator PGC1α.

    Science.gov (United States)

    Bhalla, Kavita; Liu, Wan-Ju; Thompson, Keyata; Anders, Lars; Devarakonda, Srikripa; Dewi, Ruby; Buckley, Stephanie; Hwang, Bor-Jang; Polster, Brian; Dorsey, Susan G; Sun, Yezhou; Sicinski, Piotr; Girnun, Geoffrey D

    2014-10-01

    Hepatic gluconeogenesis is crucial to maintain normal blood glucose during periods of nutrient deprivation. Gluconeogenesis is controlled at multiple levels by a variety of signal transduction and transcriptional pathways. However, dysregulation of these pathways leads to hyperglycemia and type 2 diabetes. While the effects of various signaling pathways on gluconeogenesis are well established, the downstream signaling events repressing gluconeogenic gene expression are not as well understood. The cell-cycle regulator cyclin D1 is expressed in the liver, despite the liver being a quiescent tissue. The most well-studied function of cyclin D1 is activation of cyclin-dependent kinase 4 (CDK4), promoting progression of the cell cycle. We show here a novel role for cyclin D1 as a regulator of gluconeogenic and oxidative phosphorylation (OxPhos) gene expression. In mice, fasting decreases liver cyclin D1 expression, while refeeding induces cyclin D1 expression. Inhibition of CDK4 enhances the gluconeogenic gene expression, whereas cyclin D1-mediated activation of CDK4 represses the gluconeogenic gene-expression program in vitro and in vivo. Importantly, we show that cyclin D1 represses gluconeogenesis and OxPhos in part via inhibition of peroxisome proliferator-activated receptor γ coactivator-1α (PGC1α) activity in a CDK4-dependent manner. Indeed, we demonstrate that PGC1α is novel cyclin D1/CDK4 substrate. These studies reveal a novel role for cyclin D1 on metabolism via PGC1α and reveal a potential link between cell-cycle regulation and metabolic control of glucose homeostasis.

  9. MicroRNA-22 promotes cell survival upon UV radiation by repressing PTEN

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Guangyun [Department of Pathology and Laboratory Medicine, University of Tennessee Health Science Center, Memphis, TN (United States); Center for Adult Cancer Research, University of Tennessee Health Science Center, Memphis, TN (United States); Jilin Province Key Laboratory of Animal Embryo Engineering, Jilin University, Changchun (China); Shi, Yuling [Department of Pathology and Laboratory Medicine, University of Tennessee Health Science Center, Memphis, TN (United States); Center for Adult Cancer Research, University of Tennessee Health Science Center, Memphis, TN (United States); Wu, Zhao-Hui, E-mail: zwu6@uthsc.edu [Department of Pathology and Laboratory Medicine, University of Tennessee Health Science Center, Memphis, TN (United States); Center for Adult Cancer Research, University of Tennessee Health Science Center, Memphis, TN (United States)

    2012-01-06

    Highlights: Black-Right-Pointing-Pointer miR-22 is induced in cells treated with UV radiation. Black-Right-Pointing-Pointer ATM is required for miR-22 induction in response to UV. Black-Right-Pointing-Pointer miR-22 targets 3 Prime -UTR of PTEN to repress its expression in UV-treated cells. Black-Right-Pointing-Pointer Upregulated miR-22 inhibits apoptosis in cells exposed to UV. -- Abstract: DNA damage response upon UV radiation involves a complex network of cellular events required for maintaining the homeostasis and restoring genomic stability of the cells. As a new class of players involved in DNA damage response, the regulation and function of microRNAs in response to UV remain poorly understood. Here we show that UV radiation induces a significant increase of miR-22 expression, which appears to be dependent on the activation of DNA damage responding kinase ATM (ataxia telangiectasia mutated). Increased miR-22 expression may result from enhanced miR-22 maturation in cells exposed to UV. We further found that tumor suppressor gene phosphatase and tensin homolog (PTEN) expression was inversely correlated with miR-22 induction and UV-induced PTEN repression was attenuated by overexpression of a miR-22 inhibitor. Moreover, increased miR-22 expression significantly inhibited the activation of caspase signaling cascade, leading to enhanced cell survival upon UV radiation. Collectively, these results indicate that miR-22 is an important player in the cellular stress response upon UV radiation, which may promote cell survival via the repression of PTEN expression.

  10. I-mfa domain proteins specifically interact with SERTA domain proteins and repress their transactivating functions.

    Science.gov (United States)

    Kusano, Shuichi; Shiimura, Yuki; Eizuru, Yoshito

    2011-09-01

    The I-mfa domain proteins I-mfa and HIC are considered to be candidate tumor suppressor genes and have been shown to be involved in transcriptional regulation. We show here that I-mfa and HIC specifically interact with SEI-1 through their C-terminal I-mfa domains in vivo. This interaction affects the intracellular localization of I-mfa and requires the region of SEI-1 between 30 and 90 amino acids, which includes its SERTA domain, and results in repression of its intrinsic transcriptional activity. I-mfa also decreases the levels of the SEI-1·DP-1 complex and endogenous Fbxw7 mRNA, the expression of which is coregulated by E2F·DP-1 and SEI-1 in an interaction-dependent manner in vitro. In addition, I-mfa also specifically interacts with other SERTA domain-containing proteins, including SEI-2, SEI-3, SERTAD3 and SERTAD4, through its I-mfa domain in vivo. This interaction also affects the intracellular localization of I-mfa and represses the intrinsic transcriptional activities of SEI-2 and SERTAD3, which are also involved in the E2F-dependent transcription. These data reveal for the first time that I-mfa domain proteins interact with SERTA domain proteins and negatively regulate their transcriptional activity. Because SEI-1, SEI-2 and SERTAD3, whose intrinsic transcriptional activities are repressed by I-mfa, are suggested to be oncogenes, I-mfa domain proteins may be involved in their oncogenic functions by negatively regulating their transcriptional activities.

  11. Influence of repressive coping style on cortical activation during encoding of angry faces.

    Directory of Open Access Journals (Sweden)

    Astrid Veronika Rauch

    Full Text Available BACKGROUND: Coping plays an important role for emotion regulation in threatening situations. The model of coping modes designates repression and sensitization as two independent coping styles. Repression consists of strategies that shield the individual from arousal. Sensitization indicates increased analysis of the environment in order to reduce uncertainty. According to the discontinuity hypothesis, repressors are sensitive to threat in the early stages of information processing. While repressors do not exhibit memory disturbances early on, they manifest weak memory for these stimuli later. This study investigates the discontinuity hypothesis using functional magnetic resonance imaging (fMRI. METHODS: Healthy volunteers (20 repressors and 20 sensitizers were selected from a sample of 150 students on the basis of the Mainz Coping Inventory. During the fMRI experiment, subjects evaluated and memorized emotional and neutral faces. Subjects performed two sessions of face recognition: immediately after the fMRI session and three days later. RESULTS: Repressors exhibited greater activation of frontal, parietal and temporal areas during encoding of angry faces compared to sensitizers. There were no differences in recognition of facial emotions between groups neither immediately after exposure nor after three days. CONCLUSIONS: The fMRI findings suggest that repressors manifest an enhanced neural processing of directly threatening facial expression which confirms the assumption of hyper-responsivity to threatening information in repression in an early processing stage. A discrepancy was observed between high neural activation in encoding-relevant brain areas in response to angry faces in repressors and no advantage in subsequent memory for these faces compared to sensitizers.

  12. Endocytosis of a maltose permease is induced when amylolytic enzyme production is repressed in Aspergillus oryzae.

    Science.gov (United States)

    Hiramoto, Tetsuya; Tanaka, Mizuki; Ichikawa, Takanori; Matsuura, Yuka; Hasegawa-Shiro, Sachiko; Shintani, Takahiro; Gomi, Katsuya

    2015-09-01

    In the filamentous fungus Aspergillus oryzae, amylolytic enzyme production is induced by the presence of maltose. Previously, we identified a putative maltose permease (MalP) gene in the maltose-utilizing cluster of A. oryzae. malP disruption causes a significant decrease in α-amylase activity and maltose consumption, indicating that MalP is a maltose transporter required for amylolytic enzyme production in A. oryzae. Although the expression of amylase genes and malP is repressed by the presence of glucose, the effect of glucose on the abundance of functional MalP is unknown. In this study, we examined the effect of glucose and other carbon sources on the subcellular localization of green fluorescence protein (GFP)-tagged MalP. After glucose addition, GFP-MalP at the plasma membrane was internalized and delivered to the vacuole. This glucose-induced internalization of GFP-MalP was inhibited by treatment with latrunculin B, an inhibitor of actin polymerization. Furthermore, GFP-MalP internalization was inhibited by repressing the HECT ubiquitin ligase HulA (ortholog of yeast Rsp5). These results suggest that MalP is transported to the vacuole by endocytosis in the presence of glucose. Besides glucose, mannose and 2-deoxyglucose also induced the endocytosis of GFP-MalP and amylolytic enzyme production was inhibited by the addition of these sugars. However, neither the subcellular localization of GFP-MalP nor amylolytic enzyme production was influenced by the addition of xylose or 3-O-methylglucose. These results imply that MalP endocytosis is induced when amylolytic enzyme production is repressed.

  13. Rapamycin reveals an mTOR-independent repression of Kv1.1 expression during epileptogenesis.

    Science.gov (United States)

    Sosanya, Natasha M; Brager, Darrin H; Wolfe, Sarah; Niere, Farr; Raab-Graham, Kimberly F

    2015-01-01

    Changes in ion channel expression are implicated in the etiology of epilepsy. However, the molecular leading to long-term aberrant expression of ion channels are not well understood. The mechanistic/mammalian target of rapamycin (mTOR) is a serine/threonine protein kinase that mediates activity-dependent protein synthesis in neurons. mTOR is overactive in epilepsy, suggesting that excessive protein synthesis may contribute to the neuronal pathology. In contrast, we found that mTOR activity and the microRNA miR-129-5p reduce the expression of the voltage-gated potassium channel Kv1.1 in an animal model of temporal lobe epilepsy (TLE). When mTOR activity is low, Kv1.1 expression is high and the frequency of behavioral seizures is low. However, as behavioral seizure activity rises, mTOR activity increases and Kv1.1 protein levels drop. In CA1 pyramidal neurons, the reduction in Kv1.1 lowers the threshold for action potential firing. Interestingly, blocking mTOR activity with rapamycin reduces behavioral seizures and temporarily keeps Kv1.1 levels elevated. Overtime, seizure activity increases and Kv1.1 protein decreases in all animals, even those treated with rapamycin. Notably, the concentration of miR-129-5p, the negative regulator of Kv1.1 mRNA translation, increases by 21days post-status epilepticus (SE), sustaining Kv1.1 mRNA translational repression. Our results suggest that following kainic-acid induced status epilepticus there are two phases of Kv1.1 repression: (1) an initial mTOR-dependent repression of Kv1.1 that is followed by (2) a miR-129-5p persistent reduction of Kv1.1.

  14. Different levels of catabolite repression optimize growth in stable and variable environments.

    Directory of Open Access Journals (Sweden)

    Aaron M New

    2014-01-01

    Full Text Available Organisms respond to environmental changes by adapting the expression of key genes. However, such transcriptional reprogramming requires time and energy, and may also leave the organism ill-adapted when the original environment returns. Here, we study the dynamics of transcriptional reprogramming and fitness in the model eukaryote Saccharomyces cerevisiae in response to changing carbon environments. Population and single-cell analyses reveal that some wild yeast strains rapidly and uniformly adapt gene expression and growth to changing carbon sources, whereas other strains respond more slowly, resulting in long periods of slow growth (the so-called "lag phase" and large differences between individual cells within the population. We exploit this natural heterogeneity to evolve a set of mutants that demonstrate how the frequency and duration of changes in carbon source can favor different carbon catabolite repression strategies. At one end of this spectrum are "specialist" strategies that display high rates of growth in stable environments, with more stringent catabolite repression and slower transcriptional reprogramming. The other mutants display less stringent catabolite repression, resulting in leaky expression of genes that are not required for growth in glucose. This "generalist" strategy reduces fitness in glucose, but allows faster transcriptional reprogramming and shorter lag phases when the cells need to shift to alternative carbon sources. Whole-genome sequencing of these mutants reveals that mutations in key regulatory genes such as HXK2 and STD1 adjust the regulation and transcriptional noise of metabolic genes, with some mutations leading to alternative gene regulatory strategies that allow "stochastic sensing" of the environment. Together, our study unmasks how variable and stable environments favor distinct strategies of transcriptional reprogramming and growth.

  15. Bile Acids Function Synergistically To Repress Invasion Gene Expression in Salmonella by Destabilizing the Invasion Regulator HilD.

    Science.gov (United States)

    Eade, Colleen R; Hung, Chien-Che; Bullard, Brian; Gonzalez-Escobedo, Geoffrey; Gunn, John S; Altier, Craig

    2016-08-01

    Salmonella spp. are carried by and can acutely infect agricultural animals and humans. After ingestion, salmonellae traverse the upper digestive tract and initiate tissue invasion of the distal ileum, a virulence process carried out by the type III secretion system encoded within Salmonella pathogenicity island 1 (SPI-1). Salmonellae coordinate SPI-1 expression with anatomical location via environmental cues, one of which is bile, a complex digestive fluid that causes potent repression of SPI-1 genes. The individual components of bile responsible for SPI-1 repression have not been previously characterized, nor have the bacterial signaling processes that modulate their effects been determined. Here, we characterize the mechanism by which bile represses SPI-1 expression. Individual bile acids exhibit repressive activity on SPI-1-regulated genes that requires neither passive diffusion nor OmpF-mediated entry. By using genetic methods, the effects of bile and bile acids were shown to require the invasion gene transcriptional activator hilD and to function independently of known upstream signaling pathways. Protein analysis techniques showed that SPI-1 repression by bile acids is mediated by posttranslational destabilization of HilD. Finally, we found that bile acids function synergistically to achieve the overall repressive activity of bile. These studies demonstrate a common mechanism by which diverse environmental cues (e.g., certain short-chain fatty acids and bile acids) inhibit SPI-1 expression. These data provide information relevant to Salmonella pathogenesis during acute infection in the intestine and during chronic infection of the gallbladder and inform the basis for development of therapeutics to inhibit invasion as a means of repressing Salmonella pathogenicity.

  16. Bureau-repression: Administrative Sanction and Social Control in Modern Spain

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    Pedro Oliver Olmo

    2015-12-01

    Full Text Available This paper explains the creation of an intelligible suggestion for better understanding the administrative sanction in many disciplines in social sciences: the bureau-repression. The coining of this concept is due especially to the repression to which social protestors and demonstrators have been subject since the birth of the 15-M movement in Spain. However, bureau-repression had already begun being exercised in the years following the Transition, and it has developed in parallel to the stage of Security State that characterizes the state system of social control. A detailed analysis of the administrative sanction is performed for many benefits which such sanction provides for those in power, who use it both to silence voices from the street and to dispose of elements which are harmful for the neoliberal system (disadvantaged groups or immigrants. In short, the reader will find the underlying political and repressive background which, at first glance, is usually a monetary fine, and will discover that there are ways to avoid this dense surveillance exercised over the governed people (bureau-resistance. Este artículo explica la creación de una sugerencia inteligible para una mejor comprensión de la sanción administrativa en muchas disciplinas de las ciencias sociales: la burorrepresión. Este término nació especialmente a raíz de la represión que han sufrido los manifestantes de las protestas sociales desde el nacimiento del movimiento 15-M en España. Sin embargo, la burorrepresión ya había comenzado a ejercerse en los años que siguieron a la Transición, y se ha desarrollado de forma paralela al estado de seguridad que caracteriza el sistema estatal de control social. Se realiza un análisis detallado de la sanción administrativa, desarrollada en beneficio de los que están en el poder, quienes la usan tanto para silenciar las voces de la calle como para deshacerse de elementos que sean perjudiciales para el sistema neoliberal

  17. Repression of telomere-associated genes by microglia activation in neuropsychiatric disease.

    Science.gov (United States)

    Kronenberg, Golo; Uhlemann, Ria; Schöner, Johanna; Wegner, Stephanie; Boujon, Valérie; Deigendesch, Nikolas; Endres, Matthias; Gertz, Karen

    2016-11-28

    Microglia senescence may promote neuropsychiatric disease. This prompted us to examine the relationship between microglia activation states and telomere biology. A panel of candidate genes associated with telomere maintenance, mitochondrial biogenesis, and cell-cycle regulation were investigated in M1- and M2-polarized microglia in vitro as well as in MACS-purified CD11b+ microglia/brain macrophages from models of stroke, Alzheimer's disease, and chronic stress. M1 polarization, ischemia, and Alzheimer pathology elicited a strikingly similar transcriptomic profile with, in particular, reduced expression of murine Tert. Our results link classical microglia activation with repression of telomere-associated genes, suggesting a new mechanism underlying microglia dysfunction.

  18. Requirement for sex comb on midleg protein interactions in Drosophila polycomb group repression.

    OpenAIRE

    Aidan J Peterson; Mallin, Daniel R.; Francis, Nicole J.; Ketel, Carrie S.; Stamm, Joyce; Voeller, Rochus K.; Kingston, Robert E.; Jeffrey A Simon

    2004-01-01

    The Drosophila Sex Comb on Midleg (SCM) protein is a transcriptional repressor of the Polycomb group (PcG). Although genetic studies establish SCM as a crucial PcG member, its molecular role is not known. To investigate how SCM might link to PcG complexes, we analyzed the in vivo role of a conserved protein interaction module, the SPM domain. This domain is found in SCM and in another PcG protein, Polyhomeotic (PH), which is a core component of Polycomb repressive complex 1 (PRC1). SCM-PH int...

  19. Greves, sindicatos e repressão policial no Rio de Janeiro (1954-1964)

    OpenAIRE

    Marcelo Badaró Mattos

    2004-01-01

    Este artigo apresenta parte dos resultados de uma pesquisa sobre as greves e a repressão aos sindicatos no Rio de Janeiro entre 1954 e 1964. Seu objetivo central é rediscutir a relação entre Estado, empresários e trabalhadores organizados no período em questão a partir da dimensão de conflito explicitada nos momentos de greve. Pretendeu-se também apresentar dados mais completos que os anteriormente disponíveis sobre o total e as características das greves, bem como explorar o potencial da doc...

  20. Molecular Determinants for PspA-Mediated Repression of the AAA Transcriptional Activator PspF

    OpenAIRE

    Elderkin, Sarah; Bordes, Patricia; Jones, Susan; Rappas, Mathieu; Buck, Martin

    2005-01-01

    The Escherichia coli phage shock protein system (pspABCDE operon and pspG gene) is induced by numerous stresses related to the membrane integrity state. Transcription of the psp genes requires the RNA polymerase containing the σ54 subunit and the AAA transcriptional activator PspF. PspF belongs to an atypical class of σ54 AAA activators in that it lacks an N-terminal regulatory domain and is instead negatively regulated by another regulatory protein, PspA. PspA therefore represses its own exp...

  1. [Breeding and characterization of laccase-producing Phanerochaete chrysosporium mutant resistant to nutritional repression].

    Science.gov (United States)

    Qiu, Ailian; Li, Wenyan; Zheng, Yaotong; Fan, Xiaojing; Ye, Youxian; Meng, Yan

    2011-03-01

    To screen Phanerochaete chrysosporium mutants resisting nutritional repression and to characterize laccase produced by the mutants. We used repeated UV mutagenesis and screened the mutant strains by using the guaiacol nitrogen sufficient differential medium. We characterized enzymes production mechanism of the nutritional regulation through comparing the differences of cell growth and enzyme-production kinetics under different nutritional conditions; We validated production of laccase by Phanerochaete chrysosporium through measurements of the heat treatment, removal of manganese ion and addition of the catalase. Three different methods were validated that both strains of pcR5305 and pcR5324 can produce laccase under the nitrogen limitation (N-L) and nitrogen sufficient (N-S) conditions. Under the N-L conditions, pcR5305 can produce 203.5 U/L laccase and pcR5324 can produce 187.6 U/L laccase; Under the N-S conditions, pcR5305 can produce 220.6 U/L laccase and pcR5324 can produce 183.9 U/L laccase. The original strain pc530 only can produce very little laccase under either conditions. The laccase-production regulation mechanisms of the two strains are different: Production of laccase and the cell growth by pcR5305 are in synchronism. However production of the laccase by pcR5324 is repressed by nutrition. Both strains have the capacity of resisting nutritional repression and produce lignin peroxidase and manganese peroxidase with high yield. (LiP 1343.2, MnP 252.2 U/L and LiP 1169.5, MnP 172.4 U/L respectively). The mutants of Phanerochaete chrysosporium can produce laccase. At same time they showed the capacity of resisting nutritional repression and production of laccase, lignin peroxidase and manganese peroxidase. Our results possess high value for production, application and fundamental research. We provided new strains and established a very good foundation for the further research of metabolic regulation of ligninolytic enzymes production.

  2. A grande repressão de 1932 em São Paulo.

    Directory of Open Access Journals (Sweden)

    Marcos Tarcisio Florindo

    2015-06-01

    Full Text Available O presente artigo analisa a grande repressão política e social que acompanhou o desenrolar da revolução constitucionalista de 1932 na cidade de São Paulo e avalia o impacto das práticas de contenção nas organizações atingidas, sobretudo os sindicatos e partidos dirigidos por militantes da revolução social. As fontes principais para a elaboração do texto são os documentos produzidos pelo DEOPS/SP.

  3. HP1a, Su(var)3-9, SETDB1 and POF stimulate or repress gene expression depending on genomic position, gene length and expression pattern in Drosophila melanogaster.

    Science.gov (United States)

    Lundberg, Lina E; Stenberg, Per; Larsson, Jan

    2013-04-01

    Heterochromatin protein 1a (HP1a) is a chromatin-associated protein important for the formation and maintenance of heterochromatin. In Drosophila, the two histone methyltransferases SETDB1 and Su(var)3-9 mediate H3K9 methylation marks that initiates the establishment and spreading of HP1a-enriched chromatin. Although HP1a is generally regarded as a factor that represses gene transcription, several reports have linked HP1a binding to active genes, and in some cases, it has been shown to stimulate transcriptional activity. To clarify the function of HP1a in transcription regulation and its association with Su(var)3-9, SETDB1 and the chromosome 4-specific protein POF, we conducted genome-wide expression studies and combined the results with available binding data in Drosophila melanogaster. The results suggest that HP1a, SETDB1 and Su(var)3-9 repress genes on chromosome 4, where non-ubiquitously expressed genes are preferentially targeted, and stimulate genes in pericentromeric regions. Further, we showed that on chromosome 4, Su(var)3-9, SETDB1 and HP1a target the same genes. In addition, we found that transposons are repressed by HP1a and Su(var)3-9 and that the binding level and expression effects of HP1a are affected by gene length. Our results indicate that genes have adapted to be properly expressed in their local chromatin environment.

  4. Dact2 represses PITX2 transcriptional activation and cell proliferation through Wnt/beta-catenin signaling during odontogenesis.

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    Xiao Li

    Full Text Available Dact proteins belong to the Dapper/Frodo protein family and function as cytoplasmic attenuators in Wnt and TGFβ signaling. Previous studies show that Dact1 is a potent Wnt signaling inhibitor by promoting degradation of β-catenin. We report a new mechanism for Dact2 function as an inhibitor of the canonical Wnt signaling pathway by interacting with PITX2. PITX2 is a downstream transcription factor in Wnt/β-catenin signaling, and PITX2 synergizes with Lef-1 to activate downstream genes. Immunohistochemistry verified the expression of Dact2 in the tooth epithelium, which correlated with Pitx2 epithelial expression. Dact2 loss of function and PITX2 gain of function studies reveal a feedback mechanism for controlling Dact2 expression. Pitx2 endogenously activates Dact2 expression and Dact2 feeds back to repress Pitx2 transcriptional activity. A Topflash reporter system was employed showing PITX2 activation of Wnt signaling, which is attenuated by Dact2. Transient transfections demonstrate the inhibitory effect of Dact2 on critical dental epithelial differentiation factors during tooth development. Dact2 significantly inhibits PITX2 activation of the Dlx2 and amelogenin promoters. Multiple lines of evidence conclude the inhibition is achieved by the physical interaction between Dact2 and Pitx2 proteins. The loss of function of Dact2 also reveals increased cell proliferation due to up-regulated Wnt downstream genes, cyclinD1 and cyclinD2. In summary, we have identified a novel role for Dact2 as an inhibitor of the canonical Wnt pathway in embryonic tooth development through its regulation of cell proliferation and differentiation.

  5. Dact2 represses PITX2 transcriptional activation and cell proliferation through Wnt/beta-catenin signaling during odontogenesis.

    Science.gov (United States)

    Li, Xiao; Florez, Sergio; Wang, Jianbo; Cao, Huojun; Amendt, Brad A

    2013-01-01

    Dact proteins belong to the Dapper/Frodo protein family and function as cytoplasmic attenuators in Wnt and TGFβ signaling. Previous studies show that Dact1 is a potent Wnt signaling inhibitor by promoting degradation of β-catenin. We report a new mechanism for Dact2 function as an inhibitor of the canonical Wnt signaling pathway by interacting with PITX2. PITX2 is a downstream transcription factor in Wnt/β-catenin signaling, and PITX2 synergizes with Lef-1 to activate downstream genes. Immunohistochemistry verified the expression of Dact2 in the tooth epithelium, which correlated with Pitx2 epithelial expression. Dact2 loss of function and PITX2 gain of function studies reveal a feedback mechanism for controlling Dact2 expression. Pitx2 endogenously activates Dact2 expression and Dact2 feeds back to repress Pitx2 transcriptional activity. A Topflash reporter system was employed showing PITX2 activation of Wnt signaling, which is attenuated by Dact2. Transient transfections demonstrate the inhibitory effect of Dact2 on critical dental epithelial differentiation factors during tooth development. Dact2 significantly inhibits PITX2 activation of the Dlx2 and amelogenin promoters. Multiple lines of evidence conclude the inhibition is achieved by the physical interaction between Dact2 and Pitx2 proteins. The loss of function of Dact2 also reveals increased cell proliferation due to up-regulated Wnt downstream genes, cyclinD1 and cyclinD2. In summary, we have identified a novel role for Dact2 as an inhibitor of the canonical Wnt pathway in embryonic tooth development through its regulation of cell proliferation and differentiation.

  6. Deletion of plant-specific sugar residues in plant N-glycans by repression of GDP-D-mannose 4,6-dehydratase and β-1,2-xylosyltransferase genes.

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    Matsuo, Kouki; Kagaya, Uiko; Itchoda, Noriko; Tabayashi, Noriko; Matsumura, Takeshi

    2014-10-01

    Production of pharmaceutical glycoproteins, such as therapeutic antibodies and cytokines, in plants has many advantages in safety and reduced costs. However, plant-made glycoproteins have N-glycans with plant-specific sugar residues (core β-1,2-xylose and α-1,3-fucose) and a Lewis a (Le(a)) epitope, Galβ(1-3)[Fucα(1-4)]GlcNAc. Because it is likely that these sugar residues and glycan structures are immunogenic, many attempts have been made to delete them. Previously, we reported the simultaneous deletion of the plant-specific core α-1,3-fucose and α-1,4-fucose residues in Le(a) epitopes by repressing the GDP-D-mannose 4,6-dehydratase (GMD) gene, which is associated with GDP-L-fucose biosynthesis, in Nicotiana benthamiana plants (rGMD plants, renamed to ΔGMD plants) (Matsuo and Matsumura, Plant Biotechnol. J., 9, 264-281, 2011). In the present study, we generated a core β-1,2-xylose residue-repressed transgenic N. benthamiana plant by co-suppression of β-1,2-xylosyltransferase (ΔXylT plant). By crossing ΔGMD and ΔXylT plants, we successfully generated plants in which plant-specific sugar residues were repressed (ΔGMDΔXylT plants). The proportion of N-glycans with deleted plant-specific sugar residues found in total soluble protein from ΔGMDΔXylT plants increased by 82.41%. Recombinant mouse granulocyte/macrophage-colony stimulating factor (mGM-CSF) and human monoclonal immunoglobulin G (hIgG) harboring N-glycans with deleted plant-specific sugar residues were successfully produced in ΔGMDΔXylT plants. Simultaneous repression of the GMD and XylT genes in N. benthamiana is thus very useful for deleting plant-specific sugar residues.

  7. Sodium arsenite represses the expression of myogenin in C2C12 mouse myoblast cells through histone modifications and altered expression of Ezh2, Glp, and Igf-1

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    Hong, Gia-Ming [Environmental Toxicology Graduate Program, Clemson University, 132 Long Hall, Clemson, SC 29634 (United States); Present address: The University of Chicago, Section of Hematology/Oncology, 900 E. 57th Street, Room 7134, Chicago, IL 60637 (United States); Bain, Lisa J., E-mail: lbain@clemson.edu [Environmental Toxicology Graduate Program, Clemson University, 132 Long Hall, Clemson, SC 29634 (United States); Department of Biological Sciences, Clemson University, 132 Long Hall, Clemson, SC 29634 (United States)

    2012-05-01

    Arsenic is a toxicant commonly found in water systems and chronic exposure can result in adverse developmental effects including increased neonatal death, stillbirths, and miscarriages, low birth weight, and altered locomotor activity. Previous studies indicate that 20 nM sodium arsenite exposure to C2C12 mouse myocyte cells delayed myoblast differentiation due to reduced myogenin expression, the transcription factor that differentiates myoblasts into myotubes. In this study, several mechanisms by which arsenic could alter myogenin expression were examined. Exposing differentiating C2C12 cells to 20 nM arsenic increased H3K9 dimethylation (H3K9me2) and H3K9 trimethylation (H3K9me3) by 3-fold near the transcription start site of myogenin, which is indicative of increased repressive marks, and reduced H3K9 acetylation (H3K9Ac) by 0.5-fold, indicative of reduced permissive marks. Protein expression of Glp or Ehmt1, a H3-K9 methyltransferase, was also increased by 1.6-fold in arsenic-exposed cells. In addition to the altered histone remodeling status on the myogenin promoter, protein and mRNA levels of Igf-1, a myogenic growth factor, were significantly repressed by arsenic exposure. Moreover, a 2-fold induction of Ezh2 expression, and an increased recruitment of Ezh2 (3.3-fold) and Dnmt3a (∼ 2-fold) to the myogenin promoter at the transcription start site (− 40 to + 42), were detected in the arsenic-treated cells. Together, we conclude that the repressed myogenin expression in arsenic-exposed C2C12 cells was likely due to a combination of reduced expression of Igf-1, enhanced nuclear expression and promoter recruitment of Ezh2, and altered histone remodeling status on myogenin promoter (− 40 to + 42). -- Highlights: ► Igf-1 expression is decreased in C2C12 cells after 20 nM arsenite exposure. ► Arsenic exposure alters histone remodeling on the myogenin promoter. ► Glp expression, a H3–K9 methyltransferase, was increased in arsenic-exposed cells. ► Ezh2

  8. Elf5 inhibits the epithelial-mesenchymal transition in mammary gland development and breast cancer metastasis by transcriptionally repressing Snail2.

    Science.gov (United States)

    Chakrabarti, Rumela; Hwang, Julie; Andres Blanco, Mario; Wei, Yong; Lukačišin, Martin; Romano, Rose-Anne; Smalley, Kirsten; Liu, Song; Yang, Qifeng; Ibrahim, Toni; Mercatali, Laura; Amadori, Dino; Haffty, Bruce G; Sinha, Satrajit; Kang, Yibin

    2012-11-01

    The epithelial-mesenchymal transition (EMT) is a complex process that occurs during organogenesis and in cancer metastasis. Despite recent progress, the molecular pathways connecting the physiological and pathological functions of EMT need to be better defined. Here we show that the transcription factor Elf5, a key regulator of mammary gland alveologenesis, controls EMT in both mammary gland development and metastasis. We uncovered this role for Elf5 through analyses of Elf5 conditional knockout animals, various in vitro and in vivo models of EMT and metastasis, an MMTV-neu transgenic model of mammary tumour progression and clinical breast cancer samples. Furthermore, we demonstrate that Elf5 suppresses EMT by directly repressing the transcription of Snail2, a master regulator of mammary stem cells and a known inducer of EMT. These findings establish Elf5 not only as a key cell lineage regulator during normal mammary gland development, but also as a suppressor of EMT and metastasis in breast cancer.

  9. [The "return of the repressed": the role of sexuality in the reception of psychoanalysis in Chilean medical circles, 1910-1940].

    Science.gov (United States)

    Honorato, Mariano Ruperthuz

    2015-12-01

    This article discusses the reception of psychoanalysis in Chilean medical circles from the decade of 1910 onwards. The findings make it possible to reconstruct how Freudianism was initially rejected by the incipient local psychiatric milieu, accusing it of being pansexualist. In the 1930s, this situation changed, and a reassessment of psychoanalysis was made at a local level, describing it precisely as a branch of knowledge specialized in sexuality. The highlighting of the "sublimation" mechanism, esteemed for its ability to transmute the danger of the "id" into culturally accepted products, is a milestone that marked this "return of the repressed" of the sexual factor of psychoanalysis in Chile. The possible social, political and economic variables that influenced this phenomenon are duly discussed.

  10. The Transcriptional Repressive Activity of KRAB Zinc Finger Proteins Does Not Correlate with Their Ability to Recruit TRIM28

    Science.gov (United States)

    Murphy, Kristin E.; Shylo, Natalia A.; Alexander, Katherine A.; Churchill, Angela J.; Copperman, Cecilia; García-García, María J.

    2016-01-01

    KRAB domain Zinc finger proteins are one of the most abundant families of transcriptional regulators in higher vertebrates. The prevailing view is that KRAB domain proteins function as potent transcriptional repressors by recruiting TRIM28 and promoting heterochromatin spreading. However, the extent to which all KRAB domain proteins are TRIM28-dependent transcriptional repressors is currently unclear. Our studies on mouse ZFP568 revealed that TRIM28 recruitment by KRAB domain proteins is not sufficient to warrant transcriptional repressive activity. By using luciferase reporter assays and yeast two-hybrid experiments, we tested the ability of ZFP568 and other mouse KRAB domain proteins to repress transcription and bind TRIM28. We found that some mouse KRAB domain proteins are poor transcriptional repressors despite their ability to recruit TRIM28, while others showed strong KRAB-dependent transcriptional repression, but no TRIM28 binding. Together, our results show that the transcriptional repressive activity of KRAB-ZNF proteins does not correlate with their ability to recruit TRIM28, and provide evidence that KRAB domains can regulate transcription in a TRIM28-independent fashion. Our findings challenge the current understanding of the molecular mechanisms used by KRAB domain proteins to control gene expression and highlight that a high percentage of KRAB domain proteins in the mouse genome differ from the consensus KRAB sequence at amino acid residues that are critical for TRIM28 binding and/or repressive activity. PMID:27658112

  11. Norepinephrine causes epigenetic repression of PKCε gene in rodent hearts by activating Nox1-dependent reactive oxygen species production.

    Science.gov (United States)

    Xiong, Fuxia; Xiao, Daliao; Zhang, Lubo

    2012-07-01

    Heart disease is the leading cause of death in the United States. Recent studies demonstrate that fetal programming of PKCε gene repression results in ischemia-sensitive phenotype in the heart. The present study tests the hypothesis that increased norepinephrine causes epigenetic repression of PKCε gene in the heart via Nox1-dependent reactive oxygen species (ROS) production. Prolonged norepinephrine treatment increased ROS production in fetal rat hearts and embryonic ventricular myocyte H9c2 cells via a selective increase in Nox1 expression. Norepinephrine-induced ROS resulted in an increase in PKCε promoter methylation at Egr-1 and Sp-1 binding sites, leading to PKCε gene repression. N-acetylcysteine, diphenyleneiodonium, and apocynin blocked norepinephrine-induced ROS production and the promoter methylation, and also restored PKCε mRNA and protein to control levels in vivo in fetal hearts and in vitro in embryonic myocyte cells. Accordingly, norepinephrine-induced ROS production, promoter methylation, and PKCε gene repression were completely abrogated by knockdown of Nox1 in cardiomyocytes. These findings provide evidence of a novel interaction between elevated norepinephrine and epigenetic repression of PKCε gene in the heart mediated by Nox1-dependent oxidative stress and suggest new insights of molecular mechanisms linking the heightened sympathetic activity to aberrant cardioprotection and increased ischemic vulnerability in the heart.

  12. Repression of class I transcription by cadmium is mediated by the protein phosphatase 2A

    Science.gov (United States)

    Zhou, Lei; Le Roux, Gwenaëlle; Ducrot, Cécile; Chédin, Stéphane; Labarre, Jean; Riva, Michel; Carles, Christophe

    2013-01-01

    Toxic metals are part of our environment, and undue exposure to them leads to a variety of pathologies. In response, most organisms adapt their metabolism and have evolved systems to limit this toxicity and to acquire tolerance. Ribosome biosynthesis being central for protein synthesis, we analyzed in yeast the effects of a moderate concentration of cadmium (Cd2+) on Pol I transcription that represents >60% of the transcriptional activity of the cells. We show that Cd2+ rapidly and drastically shuts down the expression of the 35S rRNA. Repression does not result from a poisoning of any of the components of the class I transcriptional machinery by Cd2+, but rather involves a protein phosphatase 2A (PP2A)-dependent cellular signaling pathway that targets the formation/dissociation of the Pol I–Rrn3 complex. We also show that Pol I transcription is repressed by other toxic metals, such as Ag+ and Hg2+, which likewise perturb the Pol I–Rrn3 complex, but through PP2A-independent mechanisms. Taken together, our results point to a central role for the Pol I–Rrn3 complex as molecular switch for regulating Pol I transcription in response to toxic metals. PMID:23640330

  13. Greves, sindicatos e repressão policial no Rio de Janeiro (1954-1964

    Directory of Open Access Journals (Sweden)

    Marcelo Badaró Mattos

    2004-01-01

    Full Text Available Este artigo apresenta parte dos resultados de uma pesquisa sobre as greves e a repressão aos sindicatos no Rio de Janeiro entre 1954 e 1964. Seu objetivo central é rediscutir a relação entre Estado, empresários e trabalhadores organizados no período em questão a partir da dimensão de conflito explicitada nos momentos de greve. Pretendeu-se também apresentar dados mais completos que os anteriormente disponíveis sobre o total e as características das greves, bem como explorar o potencial da documentação policial, aberta à consulta nos últimos anos.This article presents some conclusions on strikes and police repression to trade unions in Rio de Janeiro. The central question is the relation between State, capitalists and organized workers in that moment, with special attention to the conflict dimension expressed by strikes. The article tries to show more complete data about strike numbers and characteristics, as well as to explore the recently opened police documents.

  14. EBV reactivation as a target of luteolin to repress NPC tumorigenesis.

    Science.gov (United States)

    Wu, Chung-Chun; Fang, Chih-Yeu; Hsu, Hui-Yu; Chuang, Hsin-Ying; Cheng, Yu-Jhen; Chen, Yen-Ju; Chou, Sheng-Ping; Huang, Sheng-Yen; Lin, Su-Fang; Chang, Yao; Tsai, Ching-Hwa; Chen, Jen-Yang

    2016-04-05

    Nasopharyngeal carcinoma (NPC) is a malignancy derived from the epithelial cells of the nasopharynx. Although a combination of radiotherapy with chemotherapy is effective for therapy, relapse and metastasis after remission remain major causes of mortality. Epstein-Barr virus (EBV) is believed to be one of causes of NPC development. We demonstrated previously that EBV reactivation is important for the carcinogenesis of NPC. We sought, therefore, to determine whether EBV reactivation can be a target for retardation of relapse of NPC. After screening, we found luteolin is able to inhibit EBV reactivation. It inhibited EBV lytic protein expression and repressed the promoter activities of two major immediate-early genes, Zta and Rta. Furthermore, luteolin was shown to reduce genomic instability induced by recurrent EBV reactivation in NPC cells. EBV reactivation-induced NPC cell proliferation and migration, as well as matrigel invasiveness, were also repressed by luteolin treatment. Tumorigenicity in mice, induced by EBV reactivation, was decreased profoundly following luteolin administration. Together, these results suggest that inhibition of EBV reactivation is a novel approach to prevent the relapse of NPC.

  15. Yeast nitrogen catabolite repression is sustained by signals distinct from glutamine and glutamate reservoirs.

    Science.gov (United States)

    Fayyad-Kazan, Mohammad; Feller, A; Bodo, E; Boeckstaens, M; Marini, A M; Dubois, E; Georis, I

    2016-01-01

    Nitrogen catabolite repression (NCR) is a wide transcriptional regulation program enabling baker's yeast to downregulate genes involved in the utilization of poor nitrogen sources when preferred ones are available. Nowadays, glutamine and glutamate, the major nitrogen donors for biosyntheses, are assumed to be key metabolic signals regulating NCR. NCR is controlled by the conserved TORC1 complex, which integrates nitrogen signals among others to regulate cell growth. However, accumulating evidence indicate that the TORC1-mediated control of NCR is only partial, arguing for the existence of supplementary regulatory processes to be discovered. In this work, we developed a genetic screen to search for new players involved in NCR signaling. Our data reveal that the NADP-glutamate dehydrogenase activity of Gdh1 negatively regulates NCR-sensitive gene transcription. By determining the total, cytoplasmic and vacuolar pools of amino acids, we show that there is no positive correlation between glutamine/glutamate reservoirs and the extent of NCR. While our data indicate that glutamine could serve as initial trigger of NCR, they show that it is not a sufficient signal to sustain repression and point to the existence of yet unknown signals. Providing additional evidence uncoupling TORC1 activity and NCR, our work revisits the dogmas underlying NCR regulation.

  16. IMP2, a gene involved in the expression of glucose-repressible genes in Saccharomyces cerevisiae.

    Science.gov (United States)

    Lodi, T; Goffrini, P; Ferrero, I; Donnini, C

    1995-09-01

    Two mutants carrying different deletions of the IMP2 coding sequence of Saccharomyces cerevisiae, delta T1, which encodes a protein lacking the last 26 C-terminal amino acids, and delta T2, which completely lacks the coding region, were analysed for derepression of glucose-repressible maltose, galactose, raffinose and ethanol utilization pathways in response to glucose limitation. The role of the IMP2 gene product in the regulation of carbon catabolite repressible enzymes maltase, invertase, alcohol dehydrogenase, NAD-dependent glutamate dehydrogenase (NAD-GDH) and L-lactate:ferricytochrome-c oxidoreductase (L-LCR) was also analysed. The IMP2 gene product is required for the rapid glucose derepression of all above-mentioned carbon source utilization pathways and of all the enzymes except for L-LCR. NAD-GDH is regulated by IMP2 in the opposite way and, in fact, this enzyme was released at higher levels in both imp2 mutants than in the wild-type strain. Therefore, the product of IMP2 appears to be involved in positive and negative regulation. Both deletions result in growth and catalytic defects; in some cases partial modification of the gene product yielded more dramatic effects than its complete absence. Moreover, evidence is provided that the IMP2 gene product regulates galactose- and maltose-inducible genes at the transcriptional level and is a positive regulator of maltase, maltose permease and galactose permease gene expression.

  17. Repression of protein translation and mTOR signaling by proteasome inhibitor in colon cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Wu, William Ka Kei, E-mail: wukakei@cuhk.edu.hk [Institute of Digestive Diseases, Faculty of Medicine, The Chinese University of Hong Kong (Hong Kong); Department of Medicine and Therapeutics, Faculty of Medicine, The Chinese University of Hong Kong (Hong Kong); Department of Pharmacology, Faculty of Medicine, The Chinese University of Hong Kong (Hong Kong); Volta, Viviana [Molecular Histology and Cellular Growth Unit, DiBiT-San Raffaele Scientific Institute (Italy); Dipartimento di Scienze dell' Ambiente e della Vita (DiSAV), University of Eastern Piedmont (Italy); Cho, Chi Hin, E-mail: chcho@cuhk.edu.hk [Institute of Digestive Diseases, Faculty of Medicine, The Chinese University of Hong Kong (Hong Kong); Department of Pharmacology, Faculty of Medicine, The Chinese University of Hong Kong (Hong Kong); Wu, Ya Chun; Li, Hai Tao [Department of Pharmacology, Faculty of Medicine, The Chinese University of Hong Kong (Hong Kong); Yu, Le [Institute of Digestive Diseases, Faculty of Medicine, The Chinese University of Hong Kong (Hong Kong); Department of Pharmacology, Faculty of Medicine, The Chinese University of Hong Kong (Hong Kong); Li, Zhi Jie [Department of Pharmacology, Faculty of Medicine, The Chinese University of Hong Kong (Hong Kong); Sung, Joseph Jao Yiu, E-mail: joesung@cuhk.edu.hk [Institute of Digestive Diseases, Faculty of Medicine, The Chinese University of Hong Kong (Hong Kong); Department of Medicine and Therapeutics, Faculty of Medicine, The Chinese University of Hong Kong (Hong Kong)

    2009-09-04

    Protein homeostasis relies on a balance between protein synthesis and protein degradation. The ubiquitin-proteasome system is a major catabolic pathway for protein degradation. In this respect, proteasome inhibition has been used therapeutically for the treatment of cancer. Whether inhibition of protein degradation by proteasome inhibitor can repress protein translation via a negative feedback mechanism, however, is unknown. In this study, proteasome inhibitor MG-132 lowered the proliferation of colon cancer cells HT-29 and SW1116. In this connection, MG-132 reduced the phosphorylation of mammalian target of rapamycin (mTOR) at Ser2448 and Ser2481 and the phosphorylation of its downstream targets 4E-BP1 and p70/p85 S6 kinases. Further analysis revealed that MG-132 inhibited protein translation as evidenced by the reductions of {sup 35}S-methionine incorporation and polysomes/80S ratio. Knockdown of raptor, a structural component of mTOR complex 1, mimicked the anti-proliferative effect of MG-132. To conclude, we demonstrate that the inhibition of protein degradation by proteasome inhibitor represses mTOR signaling and protein translation in colon cancer cells.

  18. p53 represses human papillomavirus type 16 DNA replication via the viral E2 protein

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    Morgan Iain M

    2008-01-01

    Full Text Available Abstract Background Human papillomavirus (HPV DNA replication can be inhibited by the cellular tumour suppressor protein p53. However, the mechanism through which p53 inhibits viral replication and the role that this might play in the HPV life cycle are not known. The papillomavirus E2 protein is required for efficient HPV DNA replication and also regulates viral gene expression. E2 represses transcription of the HPV E6 and E7 oncogenes and can thereby modulate indirectly host cell proliferation and survival. In addition, the E2 protein from HPV 16 has been shown to bind p53 and to be capable of inducing apoptosis independently of E6 and E7. Results Here we use a panel of E2 mutants to confirm that mutations which block the induction of apoptosis via this E6/E7-independent pathway, have little or no effect on the induction of apoptosis by the E6/E7-dependent pathway. Although these mutations in E2 do not affect the ability of the protein to mediate HPV DNA replication, they do abrogate the repressive effects of p53 on the transcriptional activity of E2 and prevent the inhibition of E2-dependent HPV DNA replication by p53. Conclusion These data suggest that p53 down-regulates HPV 16 DNA replication via the E2 protein.

  19. MTF-1-mediated repression of the zinc transporter Zip10 is alleviated by zinc restriction.

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    Louis A Lichten

    Full Text Available The regulation of cellular zinc uptake is a key process in the overall mechanism governing mammalian zinc homeostasis and how zinc participates in cellular functions. We analyzed the zinc transporters of the Zip family in both the brain and liver of zinc-deficient animals and found a large, significant increase in Zip10 expression. Additionally, Zip10 expression decreased in response to zinc repletion. Moreover, isolated mouse hepatocytes, AML12 hepatocytes, and Neuro 2A cells also respond differentially to zinc availability in vitro. Measurement of Zip10 hnRNA and actinomycin D inhibition studies indicate that Zip10 was transcriptionally regulated by zinc deficiency. Through luciferase promoter constructs and ChIP analysis, binding of MTF-1 to a metal response element located 17 bp downstream of the transcription start site was shown to be necessary for zinc-induced repression of Zip10. Furthermore, zinc-activated MTF-1 causes down-regulation of Zip10 transcription by physically blocking Pol II movement through the gene. Lastly, ZIP10 is localized to the plasma membrane of hepatocytes and neuro 2A cells. Collectively, these results reveal a novel repressive role for MTF-1 in the regulation of the Zip10 zinc transporter expression by pausing Pol II transcription. ZIP10 may have roles in control of zinc homeostasis in specific sites particularly those of the brain and liver. Within that context ZIP10 may act as an important survival mechanism during periods of zinc inadequacy.

  20. Manipulating the sensitivity of signal-induced repression: quantification and consequences of altered brinker gradients.

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    Lucia Gafner

    Full Text Available Traditionally, the analysis of gene regulatory regions suffered from the caveat that it was restricted to artificial contexts (e.g. reporter constructs of limited size. With the advent of the BAC recombineering technique, genomic constructs can now be generated to test regulatory elements in their endogenous environment. The expression of the transcriptional repressor brinker (brk is negatively regulated by Dpp signaling. Repression is mediated by small sequence motifs, the silencer elements (SEs, that are present in multiple copies in the regulatory region of brk. In this work, we manipulated the SEs in the brk locus. We precisely quantified the effects of the individual SEs on the Brk gradient in the wing disc by employing a 1D data extraction method, followed by the quantification of the data with reference to an internal control. We found that mutating the SEs results in an expansion of the brk expression domain. However, even after mutating all predicted SEs, repression could still be observed in regions of maximal Dpp levels. Thus, our data point to the presence of additional, low affinity binding sites in the brk locus.

  1. I-mfa domain proteins specifically interact with HTLV-1 Tax and repress its transactivating functions.

    Science.gov (United States)

    Kusano, Shuichi; Yoshimitsu, Makoto; Hachiman, Miho; Ikeda, Masanori

    2015-12-01

    The I-mfa domain proteins HIC (also known as MDFIC) and I-mfa (also known as MDFI) are candidate tumor suppressor genes that are involved in cellular and viral transcriptional regulation. Here, we show that HIC and I-mfa directly interact with human T-cell leukemia virus type-1 (HTLV-1) Tax protein in vitro. In addition, HIC and I-mfa repress Tax-dependent transactivation of an HTLV-1 long terminal repeat (LTR) reporter construct in COS-1, Jurkat and high-Tax-producing HTLV-1-infected T cells. HIC also interacts with Tax through its I-mfa domain in vivo and represses Tax-dependent transactivation of HTLV-1 LTR and NF-κB reporter constructs in an interaction-dependent manner. Furthermore, we show that HIC decreases the nuclear distribution and stimulates the proteasomal degradation of Tax. These data reveal that HIC specifically interacts with HTLV-1 Tax and negatively regulates Tax transactivational activity by altering its subcellular distribution and stability.

  2. Soviet Government and Repressions against Priests in Vladikavkaz (1920-1930s

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    Svetlana A. Khabulova

    2012-12-01

    Full Text Available The article deals with a repressive character of interrelations between the Soviet Government and Priesthood in Vladikavkaz in 1920-30s. The Church and the Believers experienced the most tragic time when the totalitarian regime came into being in the country in 1920-1930s. The author has proved that the clergy and believers considered by Authorities as a hotbed of opposition and dissidence were subjected to prosecutions. The prosecutions against the Church paved the way for a new political regime, bringing about fear, snitching and spy mania. The human values were replaced by new regime values, the national identity was destroyed and thousands of believers were eliminated.As a result, a good number of cultural values was destroyed. The major part of Russian Intelligentsia was kicked out of the country and deprived of their rights to vote. However, people have managed to preserve religion despite the anti-Church prosecutions of 1920–1930s.It is concluded that that the Soviet Authorities tried to influence on the Church through juridical regulations. Besides, the history of repressions towards the religious communities in Vladikavkaz has been traced.

  3. Gene induction and repression during terminal erythropoiesis are mediated by distinct epigenetic changes.

    Science.gov (United States)

    Wong, Piu; Hattangadi, Shilpa M; Cheng, Albert W; Frampton, Garrett M; Young, Richard A; Lodish, Harvey F

    2011-10-20

    It is unclear how epigenetic changes regulate the induction of erythroid-specific genes during terminal erythropoiesis. Here we use global mRNA sequencing (mRNA-seq) and chromatin immunoprecipitation coupled to high-throughput sequencing (CHIP-seq) to investigate the changes that occur in mRNA levels, RNA polymerase II (Pol II) occupancy, and multiple posttranslational histone modifications when erythroid progenitors differentiate into late erythroblasts. Among genes induced during this developmental transition, there was an increase in the occupancy of Pol II, the activation marks H3K4me2, H3K4me3, H3K9Ac, and H4K16Ac, and the elongation methylation mark H3K79me2. In contrast, genes that were repressed during differentiation showed relative decreases in H3K79me2 levels yet had levels of Pol II binding and active histone marks similar to those in erythroid progenitors. We also found that relative changes in histone modification levels, in particular, H3K79me2 and H4K16ac, were most predictive of gene expression patterns. Our results suggest that in terminal erythropoiesis both promoter and elongation-associated marks contribute to the induction of erythroid genes, whereas gene repression is marked by changes in histone modifications mediating Pol II elongation. Our data map the epigenetic landscape of terminal erythropoiesis and suggest that control of transcription elongation regulates gene expression during terminal erythroid differentiation.

  4. MOF-associated complexes ensure stem cell identity and Xist repression

    Science.gov (United States)

    Chelmicki, Tomasz; Dündar, Friederike; Ramírez, Fidel; Gendrel, Anne-Valerie; Wright, Patrick Rudolf; Videm, Pavankumar; Backofen, Rolf; Heard, Edith; Manke, Thomas; Akhtar, Asifa

    2014-01-01

    Histone acetyl transferases (HATs) play distinct roles in many cellular processes and are frequently misregulated in cancers. Here, we study the regulatory potential of MYST1-(MOF)-containing MSL and NSL complexes in mouse embryonic stem cells (ESCs) and neuronal progenitors. We find that both complexes influence transcription by targeting promoters and TSS-distal enhancers. In contrast to flies, the MSL complex is not exclusively enriched on the X chromosome, yet it is crucial for mammalian X chromosome regulation as it specifically regulates Tsix, the major repressor of Xist lncRNA. MSL depletion leads to decreased Tsix expression, reduced REX1 recruitment, and consequently, enhanced accumulation of Xist and variable numbers of inactivated X chromosomes during early differentiation. The NSL complex provides additional, Tsix-independent repression of Xist by maintaining pluripotency. MSL and NSL complexes therefore act synergistically by using distinct pathways to ensure a fail-safe mechanism for the repression of X inactivation in ESCs. DOI: http://dx.doi.org/10.7554/eLife.02024.001 PMID:24842875

  5. Translational repression determines a neuronal potential in Drosophila asymmetric cell division.

    Science.gov (United States)

    Okabe, M; Imai, T; Kurusu, M; Hiromi, Y; Okano, H

    2001-05-01

    Asymmetric cell division is a fundamental strategy for generating cellular diversity during animal development. Daughter cells manifest asymmetry in their differential gene expression. Transcriptional regulation of this process has been the focus of many studies, whereas cell-type-specific 'translational' regulation has been considered to have a more minor role. During sensory organ development in Drosophila, Notch signalling directs the asymmetry between neuronal and non-neuronal lineages, and a zinc-finger transcriptional repressor Tramtrack69 (TTK69) acts downstream of Notch as a determinant of non-neuronal identity. Here we show that repression of TTK69 protein expression in the neuronal lineage occurs translationally rather than transcriptionally. This translational repression is achieved by a direct interaction between cis-acting sequences in the 3' untranslated region of ttk69 messenger RNA and its trans-acting repressor, the RNA-binding protein Musashi (MSI). Although msi can act downstream of Notch, Notch signalling does not affect MSI expression. Thus, Notch signalling is likely to regulate MSI activity rather than its expression. Our results define cell-type-specific translational control of ttk69 by MSI as a downstream event of Notch signalling in asymmetric cell division.

  6. Nitric oxide inhibits larval settlement in Amphibalanus amphitrite cyprids by repressing muscle locomotion and molting

    KAUST Repository

    Zhang, Gen

    2015-08-28

    Nitric oxide (NO) is a universal signaling molecule and plays a negative role in the metamorphosis of many biphasic organisms. Recently, the NO/NO (cyclic guanosine monophosphate) signaling pathway was reported to repress larval settlement in the barnacle Amphibalanus amphitrite. To understand the underlying molecular mechanism, we analyzed changes in the proteome of A. amphitrite cyprids in response to different concentrations of the NO donor sodium nitroprusside (SNP; 62.5, 250 and 1000 μM) using a label-free proteomics method. Compared with the control, the expression of 106 proteins differed in all three treatments. These differentially expressed proteins were assigned to 13 pathways based on KEGG pathway enrichment analysis. SNP treatment stimulated the expression of heat shock proteins and arginine kinase, which are functionally related to NO synthases, increased the expression levels of glutathione transferases for detoxification, and activated the iron-mediated fatty acid degradation pathway and the citrate cycle through ferritin. Moreover, NO repressed the level of myosins and cuticular proteins, which indicated that NO might inhibit larval settlement in A. amphitrite by modulating the process of muscle locomotion and molting.

  7. The mechanism underlying Ler-mediated alleviation of gene repression by H-NS.

    Science.gov (United States)

    Shin, Minsang

    2017-01-29

    Secretion of effector proteins in Enteropathogeneic Escherichia coli (EPEC) and Enterohemorrhagic Escherichia coli (EHEC) is mediated by a specialized type III secretion system, components of which are encoded in the LEE operons 1 to 5. H-NS, a global repressor in E. coli, silences the expression of LEE operons. Ler, a master regulator in LEE operons, shares 24% amnio acid identity and 44% amino acid similarity to H-NS. Interestingly, rather than a gene silencer, its main role has been characterized as an antagonizing protein that relieves H-NS-mediated transcriptional silencing. In the previous study we reported molecular mechanism for the repression of LEE5 promoter in EPEC and EHEC by H-NS as a protein interaction between upstream DNA-bound H-NS and the αCTD of promoter-bound RNA polymerase. The mechanism underlying Ler-mediated alleviation of the genes repression by H-NS is largely unknown. We examined regulatory effect of these proteins on LEE5p activity using various in vitro tools. Our results revealed that binding affinity of Ler to the LEE5p DNA is about 40 folds greater than that of H-NS as determined by surface plasmon resonance. We verified that Ler binding removed H-NS bound to the same stretch of DNA on LEE5 promoter resulting in a derepression. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. RNA-binding protein RBM20 represses splicing to orchestrate cardiac pre-mRNA processing

    Science.gov (United States)

    Maatz, Henrike; Jens, Marvin; Liss, Martin; Schafer, Sebastian; Heinig, Matthias; Kirchner, Marieluise; Adami, Eleonora; Rintisch, Carola; Dauksaite, Vita; Radke, Michael H.; Selbach, Matthias; Barton, Paul J.R.; Cook, Stuart A.; Rajewsky, Nikolaus; Gotthardt, Michael; Landthaler, Markus; Hubner, Norbert

    2014-01-01

    Mutations in the gene encoding the RNA-binding protein RBM20 have been implicated in dilated cardiomyopathy (DCM), a major cause of chronic heart failure, presumably through altering cardiac RNA splicing. Here, we combined transcriptome-wide crosslinking immunoprecipitation (CLIP-seq), RNA-seq, and quantitative proteomics in cell culture and rat and human hearts to examine how RBM20 regulates alternative splicing in the heart. Our analyses revealed the presence of a distinct RBM20 RNA-recognition element that is predominantly found within intronic binding sites and linked to repression of exon splicing with RBM20 binding near 3′ and 5′ splice sites. Proteomic analysis determined that RBM20 interacts with both U1 and U2 small nuclear ribonucleic particles (snRNPs) and suggested that RBM20-dependent splicing repression occurs through spliceosome stalling at complex A. Direct RBM20 targets included several genes previously shown to be involved in DCM as well as genes not typically associated with this disease. In failing human hearts, reduced expression of RBM20 affected alternative splicing of several direct targets, indicating that differences in RBM20 expression may affect cardiac function. Together, these findings identify RBM20-regulated targets and provide insight into the pathogenesis of human heart failure. PMID:24960161

  9. Authoritarianism, control and vigilance: Jacob Gorender on the aim of the repression (1940-1980

    Directory of Open Access Journals (Sweden)

    Lucileide Costa Cardoso

    2013-12-01

    Full Text Available The purpose of the article is to demonstrate through analysis of documents of repressive nature, the elements highlighted by the Military Justice to establish the trace of persecution of the intellectuals among other social sectors which dared to challenge the Dictatorship. The complete mapping, involving the combat strategies against the “communism”, including the knowledge of the political parties and their military staff, was accumulated by police and military sectors along the 20th century. We intended to follow, through these records, the political trajectory of the intellectual Jacob Gorender. As a journalist, he got involved in the discussion about the Brazilian participation in the World War II, joined the FEB in 1943. Before that, however, Gorender became a communist, recruited by Mario Alves in 1942. In the early 60’s, he acted as a militant and coordinator of PCB, when he decided to join PCBR, founded in 1968. The historian, in the beginning of the 1964 Strike, with his life already devastated by the Information and Security Community, experienced marginalization, imprisonment, torture and censorship of his writings among other abuses that also reached his closest friends, political companions and family members. The crossing of this amount of information with the memorial documents helps to understand the political repression tricks and the different Revolutionary projects in course.

  10. Citrullination of histone H3 interferes with HP1-mediated transcriptional repression.

    Directory of Open Access Journals (Sweden)

    Priyanka Sharma

    2012-09-01

    Full Text Available Multiple Sclerosis (MS is an autoimmune disease associated with abnormal expression of a subset of cytokines, resulting in inappropriate T-lymphocyte activation and uncontrolled immune response. A key issue in the field is the need to understand why these cytokines are transcriptionally activated in the patients. Here, we have examined several transcription units subject to pathological reactivation in MS, including the TNFα and IL8 cytokine genes and also several Human Endogenous RetroViruses (HERVs. We find that both the immune genes and the HERVs require the heterochromatin protein HP1α for their transcriptional repression. We further show that the Peptidylarginine Deiminase 4 (PADI4, an enzyme with a suspected role in MS, weakens the binding of HP1α to tri-methylated histone H3 lysine 9 by citrullinating histone H3 arginine 8. The resulting de-repression of both cytokines and HERVs can be reversed with the PADI-inhibitor Cl-amidine. Finally, we show that in peripheral blood mononuclear cells (PBMCs from MS patients, the promoters of TNFα, and several HERVs share a deficit in HP1α recruitment and an augmented accumulation of histone H3 with a double citrulline 8 tri-methyl lysine 9 modifications. Thus, our study provides compelling evidence that HP1α and PADI4 are regulators of both immune genes and HERVs, and that multiple events of transcriptional reactivation in MS patients can be explained by the deficiency of a single mechanism of gene silencing.

  11. A cell-autonomous molecular cascade initiated by AMP-activated protein kinase represses steroidogenesis.

    Science.gov (United States)

    Abdou, Houssein S; Bergeron, Francis; Tremblay, Jacques J

    2014-12-01

    Steroid hormones regulate essential physiological processes, and inadequate levels are associated with various pathological conditions. In testosterone-producing Leydig cells, steroidogenesis is strongly stimulated by luteinizing hormone (LH) via its receptor leading to increased cyclic AMP (cAMP) production and expression of the steroidogenic acute regulatory (STAR) protein, which is essential for the initiation of steroidogenesis. Steroidogenesis then passively decreases with the degradation of cAMP into AMP by phosphodiesterases. In this study, we show that AMP-activated protein kinase (AMPK) is activated following cAMP-to-AMP breakdown in MA-10 and MLTC-1 Leydig cells. Activated AMPK then actively inhibits cAMP-induced steroidogenesis by repressing the expression of key regulators of steroidogenesis, including Star and Nr4a1. Similar results were obtained in Y-1 adrenal cells and in the constitutively steroidogenic R2C cells. We have also determined that maximum AMPK activation following stimulation of steroidogenesis in MA-10 Leydig cells occurs when steroid hormone production has reached a plateau. Our data identify AMPK as a molecular rheostat that actively represses steroid hormone biosynthesis to preserve cellular energy homeostasis and prevent excess steroid production.

  12. Pectin lyase overproduction by Penicillium griseoroseum mutants resistant to catabolite repression.

    Science.gov (United States)

    Lima, Juliana Oliveira; Pereira, Jorge Fernando; Araújo, Elza Fernandes de; Queiroz, Marisa Vieira de

    2017-02-09

    Expression of pectinolytic genes is regulated by catabolic repression limiting the production of pectin lyase (PL) if the natural inducer, pectin, is missing from the growth medium. Here, we report the isolation of Penicillium griseoroseum mutants resistant to 2-deoxy-d-glucose (DG) that show resistance to catabolite repression and overproduce PL. Three spontaneous and nine UV-induced mutants were obtained. Some mutants produced sectors (segments morphologically different) that were also studied. The mutants were analyzed for pectinases production on pectinase-agar plates and five mutants and two sectors showing larger clearing zones than the wild type were selected for quantitative assay. Although PL production higher than the wild type has been found, phenotype instability was observed for most of the mutants and, after transfers to nonselective medium, the DG resistance was no longer present. Only mutants M03 and M04 were stable maintaining the DG-resistance phenotype. When growing for 120h in liquid medium containing glucose with or without pectin, both mutants showed higher PL production. In the presence of glucose as sole carbon source, the mutant M03 produced 7.8-fold more PL than the wild type. Due its phenotypic stability and PL overproduction, the mutant M03 presents potential for industrial applications.

  13. A common bacterial metabolite elicits prion-based bypass of glucose repression

    Science.gov (United States)

    Garcia, David M; Dietrich, David; Clardy, Jon; Jarosz, Daniel F

    2016-01-01

    Robust preference for fermentative glucose metabolism has motivated domestication of the budding yeast Saccharomyces cerevisiae. This program can be circumvented by a protein-based genetic element, the [GAR+] prion, permitting simultaneous metabolism of glucose and other carbon sources. Diverse bacteria can elicit yeast cells to acquire [GAR+], although the molecular details of this interaction remain unknown. Here we identify the common bacterial metabolite lactic acid as a strong [GAR+] inducer. Transient exposure to lactic acid caused yeast cells to heritably circumvent glucose repression. This trait had the defining genetic properties of [GAR+], and did not require utilization of lactic acid as a carbon source. Lactic acid also induced [GAR+]-like epigenetic states in fungi that diverged from S. cerevisiae ~200 million years ago, and in which glucose repression evolved independently. To our knowledge, this is the first study to uncover a bacterial metabolite with the capacity to potently induce a prion. DOI: http://dx.doi.org/10.7554/eLife.17978.001 PMID:27906649

  14. Multiple mechanisms repress N-Bak mRNA translation in the healthy and apoptotic neurons.

    Science.gov (United States)

    Jakobson, M; Jakobson, M; Llano, O; Palgi, J; Arumäe, U

    2013-08-22

    N-Bak is a neuron-specific BH