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Sample records for arsr repressor mediates

  1. Repressor-mediated tissue-specific gene expression in plants

    Science.gov (United States)

    Meagher, Richard B [Athens, GA; Balish, Rebecca S [Oxford, OH; Tehryung, Kim [Athens, GA; McKinney, Elizabeth C [Athens, GA

    2009-02-17

    Plant tissue specific gene expression by way of repressor-operator complexes, has enabled outcomes including, without limitation, male sterility and engineered plants having root-specific gene expression of relevant proteins to clean environmental pollutants from soil and water. A mercury hyperaccumulation strategy requires that mercuric ion reductase coding sequence is strongly expressed. The actin promoter vector, A2pot, engineered to contain bacterial lac operator sequences, directed strong expression in all plant vegetative organs and tissues. In contrast, the expression from the A2pot construct was restricted primarily to root tissues when a modified bacterial repressor (LacIn) was coexpressed from the light-regulated rubisco small subunit promoter in above-ground tissues. Also provided are analogous repressor operator complexes for selective expression in other plant tissues, for example, to produce male sterile plants.

  2. RecA-mediated cleavage reaction of Lambda repressor and DNA ...

    African Journals Online (AJOL)

    PRECIOUS

    2010-01-11

    Jan 11, 2010 ... hydrolyze ATP at all, but fulfills RecA functions such as cleavage of Lambda repressor and strand .... DNA binding properties of RecA and may result in an in- .... AMP-PNP there is no cleavage of Lambda repressor (Figure.

  3. Gli2 activator function in preosteoblasts is sufficient to mediate Ihh-dependent osteoblast differentiation, whereas the repressor function of Gli2 is dispensable for endochondral ossification.

    Science.gov (United States)

    Kesper, Dörthe Andrea; Didt-Koziel, Lydia; Vortkamp, Andrea

    2010-06-01

    Signaling of Indian hedgehog (Ihh), one of the key regulators of endochondral ossification is mediated by transcription factors of the Gli family, Gli1, Gli2, and Gli3. Gli3 and to a lesser extent Gli2 can be proteolytically processed into short repressor proteins. Upon Ihh signaling, processing is inhibited and the full-length proteins function as activators of transcription. Gli3 has been shown to mainly act as a repressor of Ihh target genes in chondrocytes, but the role of other Gli isoforms is less clear. Analyzing mouse mutants deficient for Ihh;Gli2 or Gli3;Gli2, we show here that the Gli2 repressor has no detectable function in chondrocyte or osteoblast differentiation. Instead, Gli2 seems to act as an activator to fully induce the expression of Ihh target genes in skeletal tissues. Furthermore, we show that, in the absence of Gli3, the activator function of Gli2 is sufficient to induce Ihh-dependent osteoblast differentiation.

  4. Assessing the Role of ETHYLENE RESPONSE FACTOR Transcriptional Repressors in Salicylic Acid-Mediated Suppression of Jasmonic Acid-Responsive Genes.

    Science.gov (United States)

    Caarls, Lotte; Van der Does, Dieuwertje; Hickman, Richard; Jansen, Wouter; Verk, Marcel C Van; Proietti, Silvia; Lorenzo, Oscar; Solano, Roberto; Pieterse, Corné M J; Van Wees, Saskia C M

    2017-02-01

    Salicylic acid (SA) and jasmonic acid (JA) cross-communicate in the plant immune signaling network to finely regulate induced defenses. In Arabidopsis, SA antagonizes many JA-responsive genes, partly by targeting the ETHYLENE RESPONSE FACTOR (ERF)-type transcriptional activator ORA59. Members of the ERF transcription factor family typically bind to GCC-box motifs in the promoters of JA- and ethylene-responsive genes, thereby positively or negatively regulating their expression. The GCC-box motif is sufficient for SA-mediated suppression of JA-responsive gene expression. Here, we investigated whether SA-induced ERF-type transcriptional repressors, which may compete with JA-induced ERF-type activators for binding at the GCC-box, play a role in SA/JA antagonism. We selected ERFs that are transcriptionally induced by SA and/or possess an EAR transcriptional repressor motif. Several of the 16 ERFs tested suppressed JA-dependent gene expression, as revealed by enhanced JA-induced PDF1.2 or VSP2 expression levels in the corresponding erf mutants, while others were involved in activation of these genes. However, SA could antagonize JA-induced PDF1.2 or VSP2 in all erf mutants, suggesting that the tested ERF transcriptional repressors are not required for SA/JA cross-talk. Moreover, a mutant in the co-repressor TOPLESS, that showed reduction in repression of JA signaling, still displayed SA-mediated antagonism of PDF1.2 and VSP2. Collectively, these results suggest that SA-regulated ERF transcriptional repressors are not essential for antagonism of JA-responsive gene expression by SA. We further show that de novo SA-induced protein synthesis is required for suppression of JA-induced PDF1.2, pointing to SA-stimulated production of an as yet unknown protein that suppresses JA-induced transcription. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  5. E-cadherin is transcriptionally activated via suppression of ZEB1 transcriptional repressor by small RNA-mediated gene silencing.

    Directory of Open Access Journals (Sweden)

    Minami Mazda

    Full Text Available RNA activation has been reported to be induced by small interfering RNAs (siRNAs that act on the promoters of several genes containing E-cadherin. In this study, we present an alternative mechanism of E-cadherin activation in human PC-3 cells by siRNAs previously reported to possess perfect-complementary sequences to E-cadherin promoter. We found that activation of E-cadherin can be also induced via suppression of ZEB1, which is a transcriptional repressor of E-cadherin, by seed-dependent silencing mechanism of these siRNAs. The functional seed-complementary sites of the siRNAs were found in the coding region in addition to the 3' untranslated region of ZEB1 mRNA. Promoter analyses indicated that E-boxes, which are ZEB1-binding sites, in the upstream promoter region are indispensable for E-cadherin transcription by the siRNAs. Thus, the results caution against ignoring siRNA seed-dependent silencing effects in genome-wide transcriptional regulation. In addition, members of miR-302/372/373/520 family, which have the same seed sequences with one of the siRNAs containing perfect-complementarity to E-cadherin promoter, are also found to activate E-cadherin transcription. Thus, E-cadherin could be upregulated by the suppression of ZEB1 transcriptional repressor by miRNAs in vivo.

  6. Wnt-mediated down-regulation of Sp1 target genes by a transcriptional repressor Sp5

    Czech Academy of Sciences Publication Activity Database

    Fujimura, Naoko; Vacík, Tomáš; Machoň, Ondřej; Vlček, Čestmír; Scalabrin, S.; Speth, M.; Diep, D.; Krauss, S.; Kozmik, Zbyněk

    2007-01-01

    Roč. 282, č. 2 (2007), s. 1225-1237 ISSN 0021-9258 Institutional research plan: CEZ:AV0Z50520514 Keywords : Wnt -mediated signaling * Sp5 transcription factor * Sp1 target genes Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 5.581, year: 2007

  7. REPRESSOR OF ULTRAVIOLET-B PHOTOMORPHOGENESIS function allows efficient phototropin mediated ultraviolet-B phototropism in etiolated seedlings.

    Science.gov (United States)

    Vanhaelewyn, Lucas; Schumacher, Paolo; Poelman, Dirk; Fankhauser, Christian; Van Der Straeten, Dominique; Vandenbussche, Filip

    2016-11-01

    Ultraviolet B (UV-B) light is a part of the solar radiation which has significant effects on plant morphology, even at low doses. In Arabidopsis, many of these morphological changes have been attributed to a specific UV-B receptor, UV resistance locus 8 (UVR8). Recent findings showed that next to phototropin regulated phototropism, UVR8 mediated signaling is able of inducing directional bending towards UV-B light in etiolated seedlings of Arabidopsis, in a phototropin independent manner. In this study, kinetic analysis of phototropic bending was used to evaluate the relative contribution of each of these pathways in UV-B mediated phototropism. Diminishing UV-B light intensity favors the importance of phototropins. Molecular and genetic analyses suggest that UV-B is capable of inducing phototropin signaling relying on phototropin kinase activity and regulation of NPH3. Moreover, enhanced UVR8 responses in the UV-B hypersensitive rup1rup2 mutants interferes with the fast phototropin mediated phototropism. Together the data suggest that phototropins are the most important receptors for UV-B induced phototropism in etiolated seedlings, and a RUP mediated negative feedback pathway prevents UVR8 signaling to interfere with the phototropin dependent response. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  8. 1H, 13C and 15N backbone resonance assignment of the arsenate reductase from Staphylococcus aureus in its reduced state

    NARCIS (Netherlands)

    Jacobs, D.M.; Messens, J.; Wechselberger, R.W.|info:eu-repo/dai/nl/304829005; Brosens, E.; Willem, R.; Wyns, L.; Martins, J.C.

    2001-01-01

    In S. aureus, resistance to the metal(III)oxyanions arsenite As(III)O− 2 and antimonite Sb(III)O− 2 is mediated by two proteins, ArsB and ArsR, encoded in the ars operon of plasmid pI258 (Silver, 1999). ArsR acts as the transcription repressor, which is de-repressed in the presence of intracellular

  9. TBLR1 regulates the expression of nuclear hormone receptor co-repressors

    Directory of Open Access Journals (Sweden)

    Brown Stuart

    2006-08-01

    Full Text Available Abstract Background Transcription is regulated by a complex interaction of activators and repressors. The effectors of repression are large multimeric complexes which contain both the repressor proteins that bind to transcription factors and a number of co-repressors that actually mediate transcriptional silencing either by inhibiting the basal transcription machinery or by recruiting chromatin-modifying enzymes. Results TBLR1 [GenBank: NM024665] is a co-repressor of nuclear hormone transcription factors. A single highly conserved gene encodes a small family of protein molecules. Different isoforms are produced by differential exon utilization. Although the ORF of the predominant form contains only 1545 bp, the human gene occupies ~200 kb of genomic DNA on chromosome 3q and contains 16 exons. The genomic sequence overlaps with the putative DC42 [GenBank: NM030921] locus. The murine homologue is structurally similar and is also located on Chromosome 3. TBLR1 is closely related (79% homology at the mRNA level to TBL1X and TBL1Y, which are located on Chromosomes X and Y. The expression of TBLR1 overlaps but is distinct from that of TBL1. An alternatively spliced form of TBLR1 has been demonstrated in human material and it too has an unique pattern of expression. TBLR1 and the homologous genes interact with proteins that regulate the nuclear hormone receptor family of transcription factors. In resting cells TBLR1 is primarily cytoplasmic but after perturbation the protein translocates to the nucleus. TBLR1 co-precipitates with SMRT, a co-repressor of nuclear hormone receptors, and co-precipitates in complexes immunoprecipitated by antiserum to HDAC3. Cells engineered to over express either TBLR1 or N- and C-terminal deletion variants, have elevated levels of endogenous N-CoR. Co-transfection of TBLR1 and SMRT results in increased expression of SMRT. This co-repressor undergoes ubiquitin-mediated degradation and we suggest that the stabilization of

  10. Regulation of crp gene expression by the catabolite repressor/activator, Cra, in Escherichia coli.

    Science.gov (United States)

    Zhang, Zhongge; Aboulwafa, Mohammad; Saier, Milton H

    2014-01-01

    Growth of E. coli on several carbon sources is dependent on the catabolite repressor/activator (Cra) protein although a Cra consensus DNA-binding site is not present in the control regions of the relevant catabolic operons. We show that Cra regulates growth by activating expression of the crp gene. It thereby mediates catabolite repression of catabolic operons by an indirect mechanism. © 2014 S. Karger AG, Basel.

  11. Mouse Hobit is a homolog of the transcriptional repressor Blimp-1 that regulates NKT cell effector differentiation

    NARCIS (Netherlands)

    van Gisbergen, Klaas P. J. M.; Kragten, Natasja A. M.; Hertoghs, Kirsten M. L.; Wensveen, Felix M.; Jonjic, Stipan; Hamann, Jörg; Nolte, Martijn A.; van Lier, Rene A. W.

    2012-01-01

    The transcriptional repressor Blimp-1 mediates the terminal differentiation of many cell types, including T cells. Here we identified Hobit (Znf683) as a previously unrecognized homolog of Blimp-1 that was specifically expressed in mouse natural killer T cells (NKT cells). Through studies of

  12. DWARF 53 acts as a repressor of strigolactone signalling in rice

    Science.gov (United States)

    Jiang, Liang; Liu, Xue; Xiong, Guosheng; Liu, Huihui; Chen, Fulu; Wang, Lei; Meng, Xiangbing; Liu, Guifu; Yu, Hong; Yuan, Yundong; Yi, Wei; Zhao, Lihua; Ma, Honglei; He, Yuanzheng; Wu, Zhongshan; Melcher, Karsten; Qian, Qian; Xu, H. Eric; Wang, Yonghong; Li, Jiayang

    2013-12-01

    Strigolactones (SLs) are a group of newly identified plant hormones that control plant shoot branching. SL signalling requires the hormone-dependent interaction of DWARF 14 (D14), a probable candidate SL receptor, with DWARF 3 (D3), an F-box component of the Skp-Cullin-F-box (SCF) E3 ubiquitin ligase complex. Here we report the characterization of a dominant SL-insensitive rice (Oryza sativa) mutant dwarf 53 (d53) and the cloning of D53, which encodes a substrate of the SCFD3 ubiquitination complex and functions as a repressor of SL signalling. Treatments with GR24, a synthetic SL analogue, cause D53 degradation via the proteasome in a manner that requires D14 and the SCFD3 ubiquitin ligase, whereas the dominant form of D53 is resistant to SL-mediated degradation. Moreover, D53 can interact with transcriptional co-repressors known as TOPLESS-RELATED PROTEINS. Our results suggest a model of SL signalling that involves SL-dependent degradation of the D53 repressor mediated by the D14-D3 complex.

  13. An Unusual Phage Repressor Encoded by Mycobacteriophage BPs.

    Directory of Open Access Journals (Sweden)

    Valerie M Villanueva

    Full Text Available Temperate bacteriophages express transcription repressors that maintain lysogeny by down-regulating lytic promoters and confer superinfection immunity. Repressor regulation is critical to the outcome of infection-lysogenic or lytic growth-as well as prophage induction into lytic replication. Mycobacteriophage BPs and its relatives use an unusual integration-dependent immunity system in which the phage attachment site (attP is located within the repressor gene (33 such that site-specific integration leads to synthesis of a prophage-encoded product (gp33103 that is 33 residues shorter at its C-terminus than the virally-encoded protein (gp33136. However, the shorter form of the repressor (gp33103 is stable and active in repression of the early lytic promoter PR, whereas the longer virally-encoded form (gp33136 is inactive due to targeted degradation via a C-terminal ssrA-like tag. We show here that both forms of the repressor bind similarly to the 33-34 intergenic regulatory region, and that BPs gp33103 is a tetramer in solution. The BPs gp33103 repressor binds to five regulatory regions spanning the BPs genome, and regulates four promoters including the early lytic promoter, PR. BPs gp33103 has a complex pattern of DNA recognition in which a full operator binding site contains two half sites separated by a variable spacer, and BPs gp33103 induces a DNA bend at the full operator site but not a half site. The operator site structure is unusual in that one half site corresponds to a 12 bp palindrome identified previously, but the other half site is a highly variable variant of the palindrome.

  14. The biotin repressor: modulation of allostery by corepressor analogs.

    Science.gov (United States)

    Brown, Patrick H; Cronan, John E; Grøtli, Morten; Beckett, Dorothy

    2004-04-02

    The Escherichia coli biotin repressor functions in biotin retention and regulation of biotin biosynthesis. Biotin retention is accomplished via the two-step biotinylation of the biotin-dependent enzyme, acetyl-CoA carboxylase. In the first step of this reaction the substrates biotin and ATP are utilized in synthesis of the activated biotin, biotinyl-5'-AMP, while in the second step this activated biotin is transferred to a unique lysine residue of the biotin carboxyl carrier protein subunit of the carboxylase. Regulation of biotin biosynthesis is accomplished through binding of the repressor to the transcription control region of the biotin biosynthetic operon. The adenylated or activated biotin functions as the corepressor in this DNA binding process. The activated biotin is a mixed anhydride and thus labile. In efforts to develop tools for structural and thermodynamic studies of the biotin regulatory interactions, two analogs of the adenylate, a sulfamoyl derivative and an ester derivative, have been synthesized and functionally characterized. Results of fluorescence measurements indicate that both analogs bind with high affinity to the repressor and that both are inactive in biotin transfer to the acceptor protein. Functional studies of their corepressor properties indicate that while the sulfamoyl is a weak allosteric activator, the ester closely mimics the physiological corepressor in activation of assembly of the transcription repression complex. Results of these studies also provide further insight into the allosteric mechanism of the biotin repressor.

  15. Crystal Structure of the CLOCK Transactivation Domain Exon19 in Complex with a Repressor

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Zhiqiang; Su, Lijing; Pei, Jimin; Grishin, Nick V.; Zhang, Hong (UTSMC)

    2017-08-01

    In the canonical clock model, CLOCK:BMAL1-mediated transcriptional activation is feedback regulated by its repressors CRY and PER and, in association with other coregulators, ultimately generates oscillatory gene expression patterns. How CLOCK:BMAL1 interacts with coregulator(s) is not well understood. Here we report the crystal structures of the mouse CLOCK transactivating domain Exon19 in complex with CIPC, a potent circadian repressor that functions independently of CRY and PER. The Exon19:CIPC complex adopts a three-helical coiled-coil bundle conformation containing two Exon19 helices and one CIPC. Unique to Exon19:CIPC, three highly conserved polar residues, Asn341 of CIPC and Gln544 of the two Exon19 helices, are located at the mid-section of the coiled-coil bundle interior and form hydrogen bonds with each other. Combining results from protein database search, sequence analysis, and mutagenesis studies, we discovered for the first time that CLOCK Exon19:CIPC interaction is a conserved transcription regulatory mechanism among mammals, fish, flies, and other invertebrates.

  16. FOXP3 is a novel transcriptional repressor for the breast cancer oncogene SKP2.

    Science.gov (United States)

    Zuo, Tao; Liu, Runhua; Zhang, Huiming; Chang, Xing; Liu, Yan; Wang, Lizhong; Zheng, Pan; Liu, Yang

    2007-12-01

    S-phase kinase-associated protein 2 (SKP2) is a component of the E3 ubiquitin ligase SKP1-Cul1-Fbox complex. Overexpression of SKP2 results in cell cycle dysregulation and carcinogenesis; however, the genetic lesions that cause this upregulation are poorly understood. We recently demonstrated that forkhead box P3 (FOXP3) is an X-linked breast cancer suppressor and an important repressor of the oncogene ERBB2/HER2. Since FOXP3 suppresses tumor growth regardless of whether the tumors overexpress ERBB2/HER2, additional FOXP3 targets may be involved in its tumor suppressor activity. Here, we show that mammary carcinomas from mice heterozygous for a Foxp3 mutation exhibited increased Skp2 expression. Ectopic expression of FOXP3 in mouse mammary cancer cells repressed SKP2 expression with a corresponding increase in p27 and polyploidy. Conversely, siRNA silencing of the FOXP3 gene in human mammary epithelial cells increased SKP2 expression. We also show that Foxp3 directly interacted with and repressed the Skp2 promoter. Moreover, the analysis of over 200 primary breast cancer samples revealed an inverse correlation between FOXP3 and SKP2 levels. Finally, we demonstrated that downregulation of SKP2 was critical for FOXP3-mediated growth inhibition in breast cancer cells that do not overexpress ERBB2/HER2. Our data provide genetic, biochemical, and functional evidence that FOXP3 is a novel transcriptional repressor for the oncogene SKP2.

  17. Chemical modification of arginine residues in the lactose repressor

    International Nuclear Information System (INIS)

    Whitson, P.A.; Matthews, K.S.

    1987-01-01

    The lactose repressor protein was chemically modified with 2,3-butanedione and phenylglyoxal. Arginine reaction was quantitated by either amino aced analysis or incorporation of 14 C-labeled phenylglyoxal. Inducer binding activity was unaffected by the modification of arginine residues, while both operator and nonspecific DNA binding activities were diminished, although to differing degrees. The correlation of the decrease in DNA binding activities with the modification of ∼ 1-2 equiv of arginine per monomer suggests increased reactivity of a functionally essential residue(s). For both reagents, operator DNA binding activity was protected by the presence of calf thymus DNA, and the extent of reaction with phenylglyoxal was simultaneously diminished. This protection presumably results from steric restriction of reagent access to an arginine(s) that is (are) essential for DNA binding interactions. These experiments suggest that there is (are) an essential reactive arginine(s) critical for repressor binding to DNA

  18. Mediatization

    DEFF Research Database (Denmark)

    Hjarvard, Stig

    2017-01-01

    Mediatization research shares media effects studies' ambition of answering the difficult questions with regard to whether and how media matter and influence contemporary culture and society. The two approaches nevertheless differ fundamentally in that mediatization research seeks answers...... to these general questions by distinguishing between two concepts: mediation and mediatization. The media effects tradition generally considers the effects of the media to be a result of individuals being exposed to media content, i.e. effects are seen as an outcome of mediated communication. Mediatization...... research is concerned with long-term structural changes involving media, culture, and society, i.e. the influences of the media are understood in relation to how media are implicated in social and cultural changes and how these processes come to create new conditions for human communication and interaction...

  19. Regulator of G-protein signaling - 5 (RGS5 is a novel repressor of hedgehog signaling.

    Directory of Open Access Journals (Sweden)

    William M Mahoney

    Full Text Available Hedgehog (Hh signaling plays fundamental roles in morphogenesis, tissue repair, and human disease. Initiation of Hh signaling is controlled by the interaction of two multipass membrane proteins, patched (Ptc and smoothened (Smo. Recent studies identify Smo as a G-protein coupled receptor (GPCR-like protein that signals through large G-protein complexes which contain the Gαi subunit. We hypothesize Regulator of G-Protein Signaling (RGS proteins, and specifically RGS5, are endogenous repressors of Hh signaling via their ability to act as GTPase activating proteins (GAPs for GTP-bound Gαi, downstream of Smo. In support of this hypothesis, we demonstrate that RGS5 over-expression inhibits sonic hedgehog (Shh-mediated signaling and osteogenesis in C3H10T1/2 cells. Conversely, signaling is potentiated by siRNA-mediated knock-down of RGS5 expression, but not RGS4 expression. Furthermore, using immuohistochemical analysis and co-immunoprecipitation (Co-IP, we demonstrate that RGS5 is present with Smo in primary cilia. This organelle is required for canonical Hh signaling in mammalian cells, and RGS5 is found in a physical complex with Smo in these cells. We therefore conclude that RGS5 is an endogenous regulator of Hh-mediated signaling and that RGS proteins are potential targets for novel therapeutics in Hh-mediated diseases.

  20. Inducible cAMP early repressor acts as a negative regulator for kindling epileptogenesis and long-term fear memory.

    Science.gov (United States)

    Kojima, Nobuhiko; Borlikova, Gilyana; Sakamoto, Toshiro; Yamada, Kazuyuki; Ikeda, Toshio; Itohara, Shigeyoshi; Niki, Hiroaki; Endo, Shogo

    2008-06-18

    Long-lasting neuronal plasticity as well as long-term memory (LTM) requires de novo synthesis of proteins through dynamic regulation of gene expression. cAMP-responsive element (CRE)-mediated gene transcription occurs in an activity-dependent manner and plays a pivotal role in neuronal plasticity and LTM in a variety of species. To study the physiological role of inducible cAMP early repressor (ICER), a CRE-mediated gene transcription repressor, in neuronal plasticity and LTM, we generated two types of ICER mutant mice: ICER-overexpressing (OE) mice and ICER-specific knock-out (KO) mice. Both ICER-OE and ICER-KO mice show no apparent abnormalities in their development and reproduction. A comprehensive battery of behavioral tests revealed no robust changes in locomotor activity, sensory and motor functions, and emotional responses in the mutant mice. However, long-term conditioned fear memory was attenuated in ICER-OE mice and enhanced in ICER-KO mice without concurrent changes in short-term fear memory. Furthermore, ICER-OE mice exhibited retardation of kindling development, whereas ICER-KO mice exhibited acceleration of kindling. These results strongly suggest that ICER negatively regulates the neuronal processes required for long-term fear memory and neuronal plasticity underlying kindling epileptogenesis, possibly through suppression of CRE-mediated gene transcription.

  1. Radiation-induced tetramer-to-dimer transition of Escherichia coli lactose repressor

    International Nuclear Information System (INIS)

    Goffinont, S.; Davidkova, M.; Spotheim-Maurizot, M.

    2009-01-01

    The wild type lactose repressor of Escherichia coli is a tetrameric protein formed by two identical dimers. They are associated via a C-terminal 4-helix bundle (called tetramerization domain) whose stability is ensured by the interaction of leucine zipper motifs. Upon in vitro γ-irradiation the repressor losses its ability to bind the operator DNA sequence due to damage of its DNA-binding domains. Using an engineered dimeric repressor for comparison, we show here that irradiation induces also the change of repressor oligomerisation state from tetramer to dimer. The splitting of the tetramer into dimers can result from the oxidation of the leucine residues of the tetramerization domain.

  2. Conscious and Unconscious Emotions in Alexithymics and Repressors

    Directory of Open Access Journals (Sweden)

    Tsvetelina Slavchova Hadzhieva

    2017-04-01

    Full Text Available In this article, the nature, evolution and characteristics of conscious and unconscious emotions which determine the internal regulation of behavior are traced. Definitions of the nature of emotions and feelings of other authors are presented, and studies which reflect the cognitive relationship of emotional processes are cited. A classification of two different personality types has been considered (alexithymic and repressor, who differently express their emotions, because of their cognitive peculiarities. The main idea of ​​the article is based on tracing the specifics of emotional expression and intensity.

  3. O-GlcNAcylation of master growth repressor DELLA by SECRET AGENT modulates multiple signaling pathways in Arabidopsis.

    Science.gov (United States)

    Zentella, Rodolfo; Hu, Jianhong; Hsieh, Wen-Ping; Matsumoto, Peter A; Dawdy, Andrew; Barnhill, Benjamin; Oldenhof, Harriëtte; Hartweck, Lynn M; Maitra, Sushmit; Thomas, Stephen G; Cockrell, Shelley; Boyce, Michael; Shabanowitz, Jeffrey; Hunt, Donald F; Olszewski, Neil E; Sun, Tai-Ping

    2016-01-15

    The DELLA family of transcription regulators functions as master growth repressors in plants by inhibiting phytohormone gibberellin (GA) signaling in response to developmental and environmental cues. DELLAs also play a central role in mediating cross-talk between GA and other signaling pathways via antagonistic direct interactions with key transcription factors. However, how these crucial protein-protein interactions can be dynamically regulated during plant development remains unclear. Here, we show that DELLAs are modified by the O-linked N-acetylglucosamine (O-GlcNAc) transferase (OGT) SECRET AGENT (SEC) in Arabidopsis. O-GlcNAcylation of the DELLA protein REPRESSOR OF ga1-3 (RGA) inhibits RGA binding to four of its interactors-PHYTOCHROME-INTERACTING FACTOR3 (PIF3), PIF4, JASMONATE-ZIM DOMAIN1, and BRASSINAZOLE-RESISTANT1 (BZR1)-that are key regulators in light, jasmonate, and brassinosteroid signaling pathways, respectively. Consistent with this, the sec-null mutant displayed reduced responses to GA and brassinosteroid and showed decreased expression of several common target genes of DELLAs, BZR1, and PIFs. Our results reveal a direct role of OGT in repressing DELLA activity and indicate that O-GlcNAcylation of DELLAs provides a fine-tuning mechanism in coordinating multiple signaling activities during plant development. © 2016 Zentella et al.; Published by Cold Spring Harbor Laboratory Press.

  4. A-type nuclear lamins act as transcriptional repressors when targeted to promoters

    International Nuclear Information System (INIS)

    Lee, Damian C.; Welton, K. Linnea; Smith, Erica D.; Kennedy, Brian K.

    2009-01-01

    Regions of heterochromatin are often found at the periphery of the mammalian nucleus, juxtaposed to the nuclear lamina. Genes in these regions are likely maintained in a transcriptionally silent state, although other locations at the nuclear periphery associated with nuclear pores are sites of active transcription. As primary components of the nuclear lamina, A- and B-type nuclear lamins are intermediate filament proteins that interact with DNA, histones and known transcriptional repressors, leading to speculation that they may promote establishment of repressive domains. However, no direct evidence of a role for nuclear lamins in transcriptional repression has been reported. Here we find that human lamin A, when expressed in yeast and cultured human cells as a fusion protein to the Gal4 DNA-binding domain (DBD), can mediate robust transcriptional repression of promoters with Gal4 binding sites. Full repression by lamin A requires both the coiled-coil rod domain and the C-terminal tail domain. In human cells, other intermediate filament proteins such as lamin B and vimentin are unable to confer robust repression as Gal4-DBD fusions, indicating that this property is specific to A-type nuclear lamins. These findings indicate that A-type lamins can promote transcriptional repression when in proximity of a promoter

  5. PML-associated repressor of transcription (PAROT), a novel KRAB-zinc finger repressor, is regulated through association with PML nuclear bodies

    International Nuclear Information System (INIS)

    Fleischer, Sandra; Wiemann, Stefan; Will, Hans; Hofmann, Thomas G.

    2006-01-01

    Promyelocytic leukemia nuclear bodies (PML-NBs) are implicated in transcriptional regulation. Here we identify a novel transcriptional repressor, PML-associated repressor of transcription (PAROT), which is regulated in its repressor activity through recruitment to PML-NBs. PAROT is a Krueppel-associated box ( KRAB) zinc-finger (ZNF) protein, which comprises an amino terminal KRAB-A and KRAB-B box, a linker domain and 8 tandemly repeated C 2 H 2 -ZNF motifs at its carboxy terminus. Consistent with its domain structure, when tethered to DNA, PAROT represses transcription, and this is partially released by the HDAC inhibitor trichostatin A. PAROT colocalizes with members of the heterochromatin protein 1 (HP1) family and with transcriptional intermediary factor-1β/KRAB-associated protein 1 (TIF-1β/KAP1), a transcriptional corepressor for the KRAB-ZNF family. Interestingly, PML isoform IV, in contrast to PML-III, efficiently recruits PAROT and TIF-1β from heterochromatin to PML-NBs. PML-NB recruitment of PAROT partially releases its transcriptional repressor activity, indicating that PAROT can be regulated through subnuclear compartmentalization. Taken together, our data identify a novel transcriptional repressor and provide evidence for its regulation through association with PML-NBs

  6. BTG2 is an LXXLL-dependent co-repressor for androgen receptor transcriptional activity

    International Nuclear Information System (INIS)

    Hu, Xu-Dong; Meng, Qing-Hui; Xu, Jia-Ying; Jiao, Yang; Ge, Chun-Min; Jacob, Asha; Wang, Ping; Rosen, Eliot M; Fan, Saijun

    2011-01-01

    Research highlights: → BTG2 associates with AR, androgen causes an increase of the interaction. → BTG2 as a co-repressor inhibits the AR-mediated transcription activity. → BTG2 inhibits the transcription activity and expression of PSA. → An intact 92 LxxLL 96 motif is essential and necessary for these activities of BTG2, while the 20 LxxLL 24 motif is not required. → Ectopic expression of BTG2 reduces proliferation of prostate cancer cells. -- Abstract: The tumor suppressor gene, BTG2 has been down-regulated in prostate cancer and the ectopic expression of this gene has been shown to inhibit prostate cancer cell growth. Sequence analysis revealed that the BTG2 protein contains two leucine-rich motifs ( 20 LxxLL 24 and 92 LxxLL 96 ), which are usually found in nuclear receptor co-factors. Based on this, we postulated that there will be an association between BTG2 and AR. In this study, we discovered that BTG2 directly bound to the androgen receptor (AR) in the absence of 5α-dihydrotestosterone (DHT), and in the presence of the androgen, this interaction was increased. BTG2 bearing the mutant 20 LxxLL 24 motif bound to AR equally efficient as the wild-type BTG2, while BTG2 bearing the mutant 92 LxxLL 96 motif failed to interact with AR. Functional studies indicated that ectopic expression of BTG2 caused a significant inhibition of AR-mediated transcriptional activity and a decreased growth of prostate cancer cells. Androgen-induced promoter activation and expression of prostate-specific antigen (PSA) are significantly attenuated by BTG2. The intact 92 LxxLL 96 motif is required for these activities. These findings, for the first time, demonstrate that BTG2 complexes with AR via an LxxLL-dependent mechanism and may play a role in prostate cancer via modulating the AR signaling pathway.

  7. Fur is a repressor of biofilm formation in Yersinia pestis.

    Directory of Open Access Journals (Sweden)

    Fengjun Sun

    Full Text Available BACKGROUND: Yersinia pestis synthesizes the attached biofilms in the flea proventriculus, which is important for the transmission of this pathogen by fleas. The hmsHFRS operons is responsible for the synthesis of exopolysaccharide (the major component of biofilm matrix, which is activated by the signaling molecule 3', 5'-cyclic diguanylic acid (c-di-GMP synthesized by the only two diguanylate cyclases HmsT, and YPO0449 (located in a putative operonYPO0450-0448. METHODOLOGY/PRINCIPAL FINDINGS: The phenotypic assays indicated that the transcriptional regulator Fur inhibited the Y. pestis biofilm production in vitro and on nematode. Two distinct Fur box-like sequences were predicted within the promoter-proximal region of hmsT, suggesting that hmsT might be a direct Fur target. The subsequent primer extension, LacZ fusion, electrophoretic mobility shift, and DNase I footprinting assays disclosed that Fur specifically bound to the hmsT promoter-proximal region for repressing the hmsT transcription. In contrast, Fur had no regulatory effect on hmsHFRS and YPO0450-0448 at the transcriptional level. The detection of intracellular c-di-GMP levels revealed that Fur inhibited the c-di-GMP production. CONCLUSIONS/SIGNIFICANCE: Y. pestis Fur inhibits the c-di-GMP production through directly repressing the transcription of hmsT, and thus it acts as a repressor of biofilm formation. Since the relevant genetic contents for fur, hmsT, hmsHFRS, and YPO0450-0448 are extremely conserved between Y. pestis and typical Y. pseudotuberculosis, the above regulatory mechanisms can be applied to Y. pseudotuberculosis.

  8. TcNPR3 from Theobroma cacao functions as a repressor of the pathogen defense response.

    Science.gov (United States)

    Shi, Zi; Zhang, Yufan; Maximova, Siela N; Guiltinan, Mark J

    2013-12-06

    Arabidopsis thaliana (Arabidopsis) NON-EXPRESSOR OF PR1 (NPR1) is a transcription coactivator that plays a central role in regulating the transcriptional response to plant pathogens. Developing flowers of homozygous npr3 mutants are dramatically more resistant to infection by the pathogenic bacterium Pseudomonas syringae, suggesting a role of NPR3 as a repressor of NPR1-mediated defense response with a novel role in flower development. We report here the characterization of a putative NPR3 gene from the tropical tree species Theobroma cacao (TcNPR3). Like in Arabidopsis, TcNPR3 was constitutively expressed across a wide range of tissue types and developmental stages but with some differences in relative levels compared to Arabidopsis. To test the function of TcNPR3, we performed transgenic complementation analysis by introducing a constitutively expressing putative TcNPR3 transgene into an Arabidopsis npr3 mutant. TcNPR3 expressing Arabidopsis plants were partially restored to the WT pathogen phenotype (immature flowers susceptible to bacterial infection). To test TcNPR3 function directly in cacao tissues, a synthetic microRNA targeting TcNPR3 mRNA was transiently expressed in cacao leaves using an Agrobacterium-infiltration method. TcNPR3 knock down leaf tissues were dramatically more resistance to infection with Phytophthora capsici in a leaf bioassay, showing smaller lesion sizes and reduced pathogen replication. We conclude that TcNPR3 functions similar to the Arabidopsis NPR3 gene in the regulation of the cacao defense response. Since TcNPR3 did not show a perfect complementation of the Arabidopsis NPR3 mutation, the possibility remains that other functions of TcNPR3 remain to be found. This novel knowledge can contribute to the breeding of resistant cacao varieties against pathogens through molecular markers based approaches or biotechnological strategies.

  9. Sp1 is a transcription repressor to stanniocalcin-1 expression in TSA-treated human colon cancer cells, HT29.

    Science.gov (United States)

    Law, Alice Y S; Yeung, B H Y; Ching, L Y; Wong, Chris K C

    2011-08-01

    Our previous study demonstrated that, stanniocalcin-1 (STC1) was a target of histone deacetylase (HDAC) inhibitors and was involved in trichostatin A (TSA) induced apoptosis in the human colon cancer cells, HT29. In this study, we reported that the transcriptional factor, specificity protein 1 (Sp1) in association with retinoblastoma (Rb) repressed STC1 gene transcription in TSA-treated HT29 cells. Our data demonstrated that, a co-treatment of the cells with TSA and Sp1 inhibitor, mithramycin A (MTM) led to a marked synergistic induction of STC1 transcript levels, STC1 promoter (1 kb)-driven luciferase activity and an increase of apoptotic cell population. The knockdown of Sp1 gene expression in TSA treated cells, revealed the repressor role of Sp1 in STC1 transcription. Using a protein phosphatase inhibitor okadaic acid (OKA), an increase of Sp1 hyperphosphorylation and so a reduction of its transcriptional activity, led to a significant induction of STC1 gene expression. Chromatin immunoprecipitation (ChIP) assay revealed that Sp1 binding on STC1 proximal promoter in TSA treated cells. The binding of Sp1 to STC1 promoter was abolished by the co-treatment of MTM or OKA in TSA-treated cells. Re-ChIP assay illustrated that Sp1-mediated inhibition of STC1 transcription was associated with the recruitment of another repressor molecule, Rb. Collectively our findings identify STC1 is a downstream target of Sp1. Copyright © 2011 Wiley-Liss, Inc.

  10. Lactose repressor protein modified with dansyl chloride: activity effects and fluorescence properties

    International Nuclear Information System (INIS)

    Hsieh, W.T.; Matthews, K.S.

    1985-01-01

    Chemical modification using 5-(dimethylamino)naphthalene-1-sulfonyl chloride (dansyl chloride) has been used to explore the importance of lysine residues involved in the binding activities of the lactose repressor and to introduce a fluorescent probe into the protein. Dansyl chloride modification of lac repressor resulted in loss of operator DNA binding at low molar ratios of reagent/monomer. Loss of nonspecific DNA binding was observed only at higher molar ratios, while isopropyl beta-D-thiogalactoside binding was not affected at any of the reagent levels studied. Lysine residues were the only modified amino acids detected. Protection of lysines-33 and -37 from modification by the presence of nonspecific DNA correlated with maintenance of operator DNA binding activity, and reaction of lysine-37 paralleled operator binding activity loss. Energy transfer between dansyl incorporated in the core region of the repressor protein and tryptophan-201 was observed, with an approximate distance of 23 A calculated between these two moieties

  11. BTG2 is an LXXLL-dependent co-repressor for androgen receptor transcriptional activity

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Xu-Dong [School of Radiation Medicine and Public Health, Medical College of Soochow University, Suzhou 215123 (China); Meng, Qing-Hui [Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057 (United States); Xu, Jia-Ying; Jiao, Yang [School of Radiation Medicine and Public Health, Medical College of Soochow University, Suzhou 215123 (China); Ge, Chun-Min [Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057 (United States); Jacob, Asha; Wang, Ping [North Shore University Hospital-Long Island Jewish Medical Center and The Feinstein Institute for Medical Research, Manhasset, NY 11030 (United States); Rosen, Eliot M [Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057 (United States); Fan, Saijun, E-mail: sjfan@suda.edu.cn [School of Radiation Medicine and Public Health, Medical College of Soochow University, Suzhou 215123 (China)

    2011-01-28

    Research highlights: {yields} BTG2 associates with AR, androgen causes an increase of the interaction. {yields} BTG2 as a co-repressor inhibits the AR-mediated transcription activity. {yields} BTG2 inhibits the transcription activity and expression of PSA. {yields} An intact {sup 92}LxxLL{sup 96} motif is essential and necessary for these activities of BTG2, while the {sup 20}LxxLL{sup 24} motif is not required. {yields} Ectopic expression of BTG2 reduces proliferation of prostate cancer cells. -- Abstract: The tumor suppressor gene, BTG2 has been down-regulated in prostate cancer and the ectopic expression of this gene has been shown to inhibit prostate cancer cell growth. Sequence analysis revealed that the BTG2 protein contains two leucine-rich motifs ({sup 20}LxxLL{sup 24} and {sup 92}LxxLL{sup 96}), which are usually found in nuclear receptor co-factors. Based on this, we postulated that there will be an association between BTG2 and AR. In this study, we discovered that BTG2 directly bound to the androgen receptor (AR) in the absence of 5{alpha}-dihydrotestosterone (DHT), and in the presence of the androgen, this interaction was increased. BTG2 bearing the mutant {sup 20}LxxLL{sup 24} motif bound to AR equally efficient as the wild-type BTG2, while BTG2 bearing the mutant {sup 92}LxxLL{sup 96} motif failed to interact with AR. Functional studies indicated that ectopic expression of BTG2 caused a significant inhibition of AR-mediated transcriptional activity and a decreased growth of prostate cancer cells. Androgen-induced promoter activation and expression of prostate-specific antigen (PSA) are significantly attenuated by BTG2. The intact {sup 92}LxxLL{sup 96} motif is required for these activities. These findings, for the first time, demonstrate that BTG2 complexes with AR via an LxxLL-dependent mechanism and may play a role in prostate cancer via modulating the AR signaling pathway.

  12. Lysogenic induction in Lex Al Escherichia coli mutants: characterization of the induction and prophage repressor influence

    International Nuclear Information System (INIS)

    Carvalho, R.E.S.

    1982-01-01

    SOS functions require new synthesis of protein and have been described as dependent on both the rec A and lex A genes. The induction of prophage was studied in bacterial strains lysogenic for a series of phages which synthesize different levels of repressor (λ, λ i m m 4 3 4 J and λ i m m 4 3 4 T ) and was compared to W-reactivation. Prophage induction was detected in lex Al mutants although at a slightly lower level and requiring two times longer when compared with wild-type. The optimum UV-dose for induction differed for each lysogenic strain and correlated with the level of repressor

  13. Identification of Quaternary Structure and Functional Domains of the CI Repressor from Bacteriophage TP901-1

    DEFF Research Database (Denmark)

    Pedersen, Margit; Lo Leggio, Leila; Grossmann, J. Günter

    2008-01-01

    is involved in the interaction with host proteins. By using small-angle X-ray scattering, we show for the first time the overall solution structure of a full-length wild-type bacteriophage repressor at low resolution revealing that the TP901-1 repressor forms a flat oligomer, most probably a trimer of dimers....

  14. REST-mediated recruitment of polycomb repressor complexes in mammalian cells

    DEFF Research Database (Denmark)

    Dietrich, Nikolaj; Lerdrup, Mads; Landt, Eskild

    2012-01-01

    Polycomb Repressive Complex (PRC) 1 and PRC2 regulate genes involved in differentiation and development. However, the mechanism for how PRC1 and PRC2 are recruited to genes in mammalian cells is unclear. Here we present evidence for an interaction between the transcription factor REST, PRC1......, and increased gene expression. Genome-wide analysis of Polycomb binding in Rest¿/¿ and Eed¿/¿ mouse embryonic stem (mES) cells showed that Rest was required for PRC1 recruitment to a subset of Polycomb regulated neuronal genes. Furthermore, we found that PRC1 can be recruited to Rest binding sites independently...... of CpG islands and the H3K27Me3 mark. Surprisingly, PRC2 was frequently increased around Rest binding sites located in CpG-rich regions in the Rest¿/¿ mES cells, indicating a more complex interplay where Rest also can limit PRC2 recruitment. Therefore, we propose that Rest has context...

  15. Processing bias in anxious subjects and repressors, measured by emotional Stroop interference and attentional allocation.

    NARCIS (Netherlands)

    Brosschot, J.F.; de Ruiter, C.; Kindt, M.

    1999-01-01

    Hypothesized that repressors (Ss high in defensiveness with low trait anxiety) would show cognitive avoidance of threatening information in an attention deployment task, but an attentional bias for the same information in an emotional interference task, while Ss high in anxiety would show a

  16. Whi7 is an unstable cell-cycle repressor of the Start transcriptional program.

    Science.gov (United States)

    Gomar-Alba, Mercè; Méndez, Ester; Quilis, Inma; Bañó, M Carmen; Igual, J Carlos

    2017-08-24

    Start is the main decision point in eukaryotic cell cycle in which cells commit to a new round of cell division. It involves the irreversible activation of a transcriptional program by G1 CDK-cyclin complexes through the inactivation of Start transcriptional repressors, Whi5 in yeast or Rb in mammals. Here we provide novel keys of how Whi7, a protein related at sequence level to Whi5, represses Start. Whi7 is an unstable protein, degraded by the SCF Grr1 ubiquitin-ligase, whose stability is cell cycle regulated by CDK1 phosphorylation. Importantly, Whi7 associates to G1/S gene promoters in late G1 acting as a repressor of SBF-dependent transcription. Our results demonstrate that Whi7 is a genuine paralog of Whi5. In fact, both proteins collaborate in Start repression bringing to light that yeast cells, as occurs in mammalian cells, rely on the combined action of multiple transcriptional repressors to block Start transition.The commitment of cells to a new cycle of division involves inactivation of the Start transcriptional repressor Whi5. Here the authors show that the sequence related protein Whi7 associates to G1/S gene promoters in late G1 and collaborates with Whi5 in Start repression.

  17. In vitro transcription accurately predicts lac repressor phenotype in vivo in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Matthew Almond Sochor

    2014-07-01

    Full Text Available A multitude of studies have looked at the in vivo and in vitro behavior of the lac repressor binding to DNA and effector molecules in order to study transcriptional repression, however these studies are not always reconcilable. Here we use in vitro transcription to directly mimic the in vivo system in order to build a self consistent set of experiments to directly compare in vivo and in vitro genetic repression. A thermodynamic model of the lac repressor binding to operator DNA and effector is used to link DNA occupancy to either normalized in vitro mRNA product or normalized in vivo fluorescence of a regulated gene, YFP. An accurate measurement of repressor, DNA and effector concentrations were made both in vivo and in vitro allowing for direct modeling of the entire thermodynamic equilibrium. In vivo repression profiles are accurately predicted from the given in vitro parameters when molecular crowding is considered. Interestingly, our measured repressor–operator DNA affinity differs significantly from previous in vitro measurements. The literature values are unable to replicate in vivo binding data. We therefore conclude that the repressor-DNA affinity is much weaker than previously thought. This finding would suggest that in vitro techniques that are specifically designed to mimic the in vivo process may be necessary to replicate the native system.

  18. Radiation-induced oxidative damage to the DNA-binding domain of the lactose repressor

    Czech Academy of Sciences Publication Activity Database

    Gillard, N.; Goffinont, S.; Buré, C.; Davídková, Marie; Maurizot, J. C.; Cadene, M.; Spotheim-Maurizot, M.

    2007-01-01

    Roč. 403, part 3 (2007), s. 463-472 ISSN 0264-6021 R&D Projects: GA MŠk 1P05OC085 Institutional research plan: CEZ:AV0Z10480505 Keywords : ionizing radiation * oxidative damage * DNA binding domain * lac repressor Subject RIV: CE - Biochemistry Impact factor: 4.009, year: 2007

  19. Radiation-induced tetramer-to-dimer transition of Esterichia coli lactose repressor

    Czech Academy of Sciences Publication Activity Database

    Goffinont, S.; Davídková, Marie; Spotheim-Maurizot, M.

    2009-01-01

    Roč. 386, č. 2 (2009), s. 300-304 ISSN 0006-291X R&D Projects: GA MŠk OC09012 Institutional research plan: CEZ:AV0Z10480505 Keywords : protein * DNA * radiation * oxidation * tetramer * dimer * lactose repressor Subject RIV: BO - Biophysics Impact factor: 2.548, year: 2009

  20. Mechanism of Metal Ion Activation of the Diphtheria Toxin Repressor DtxR

    Energy Technology Data Exchange (ETDEWEB)

    D' Aquino,J.; Tetenbaum-Novatt, J.; White, A.; Berkovitch, F.; Ringe, D.

    2005-01-01

    The diphtheria toxin repressor (DtxR) is a metal ion-activated transcriptional regulator that has been linked to the virulence of Corynebacterium diphtheriae. Structure determination has shown that there are two metal ion binding sites per repressor monomer, and site-directed mutagenesis has demonstrated that binding site 2 (primary) is essential for recognition of the target DNA repressor, leaving the role of binding site 1 (ancillary) unclear. Calorimetric techniques have demonstrated that although binding site 1 (ancillary) has high affinity for metal ion with a binding constant of 2 x 10{sup -7}, binding site 2 (primary) is a low-affinity binding site with a binding constant of 6.3 x 10{sup -4}. These two binding sites act in an independent fashion, and their contribution can be easily dissected by traditional mutational analysis. Our results clearly demonstrate that binding site 1 (ancillary) is the first one to be occupied during metal ion activation, playing a critical role in stabilization of the repressor. In addition, structural data obtained for the mutants Ni-DtxR(H79A, C102D), reported here, and the previously reported DtxR(H79A) have allowed us to propose a mechanism of metal activation for DtxR.

  1. FILAMENTOUS FLOWER controls lateral organ development by acting as both an activator and a repressor

    Directory of Open Access Journals (Sweden)

    Bonaccorso Oliver

    2012-10-01

    Full Text Available Abstract Background The YABBY (YAB family of transcription factors participate in a diverse range of processes that include leaf and floral patterning, organ growth, and the control of shoot apical meristem organisation and activity. How these disparate functions are regulated is not clear, but based on interactions with the LEUNIG-class of co-repressors, it has been proposed that YABs act as transcriptional repressors. In the light of recent work showing that DNA-binding proteins associated with the yeast co-repressor TUP1 can also function as activators, we have examined the transcriptional activity of the YABs. Results Of the four Arabidopsis YABs tested in yeast, only FILAMENTOUS FLOWER (FIL activated reporter gene expression. Similar analysis with Antirrhinum YABs identified the FIL ortholog GRAMINIFOLIA as an activator. Plant-based transactivation assays not only confirmed the potential of FIL to activate transcription, but also extended this property to the FIL paralog YABBY3 (YAB3. Subsequent transcriptomic analysis of lines expressing a steroid-inducible FIL protein revealed groups of genes that responded either positively or negatively to YAB induction. Included in the positively regulated group of genes were the polarity regulators KANADI1 (KAN1, AUXIN RESPONSE FACTOR 4 (ARF4 and ASYMMETRIC LEAVES1 (AS1. We also show that modifying FIL to function as an obligate repressor causes strong yab loss-of-function phenotypes. Conclusions Collectively these data show that FIL functions as a transcriptional activator in plants and that this activity is involved in leaf patterning. Interestingly, our study also supports the idea that FIL can act as a repressor, as transcriptomic analysis identified negatively regulated FIL-response genes. To reconcile these observations, we propose that YABs are bifunctional transcription factors that participate in both positive and negative regulation. These findings fit a model of leaf development in which

  2. Elk-3 is a transcriptional repressor of nitric-oxide synthase 2.

    Science.gov (United States)

    Chen, Yen-Hsu; Layne, Matthew D; Chung, Su Wol; Ejima, Kuniaki; Baron, Rebecca M; Yet, Shaw-Fang; Perrella, Mark A

    2003-10-10

    The inducible isoform of nitric-oxide synthase (NOS2), a key enzyme catalyzing the dramatic increase in nitric oxide by lipopolysaccharide (LPS), plays an important role in the pathophysiology of endotoxemia and sepsis. Recent evidence suggests that Ets transcription factors may contribute to NOS2 induction by inflammatory stimuli. In this study, we investigated the role of Ets transcription factors in the regulation of NOS2 by LPS and transforming growth factor (TGF)-beta 1. Transient transfection assays in macrophages showed that Ets-2 produced an increase in NOS2 promoter activity, whereas the induction by Ets-1 was modest and NERF2 had no effect. Elk-3 (Net/Erp/Sap-2a) markedly repressed NOS2 promoter activity in a dose-dependent fashion, and overexpression of Elk-3 blunted the induction of endogenous NOS2 message. Mutation of the Net inhibitory domain of Elk-3, but not the C-terminal-binding protein interaction domain, partially alleviated this repressive effect. We also found that deletion of the Ets domain of Elk-3 completely abolished its repressive effect on the NOS2 promoter. LPS administration to macrophages led to a dose-dependent decrease in endogenous Elk-3 mRNA levels, and this decrease in Elk-3 preceded the induction of NOS2 mRNA. In a mouse model of endotoxemia, the expression of Elk-3 in kidney, lung, and heart was significantly down-regulated after systemic administration of LPS, and this down-regulation also preceded NOS2 induction. Moreover, TGF-beta 1 significantly increased endogenous Elk-3 mRNA levels that had been down-regulated by LPS in macrophages. This increase in Elk-3 correlated with a TGF-beta 1-induced down-regulation of NOS2. Taken together, our data suggest that Elk-3 is a strong repressor of NOS2 promoter activity and mRNA levels and that endogenous expression of Elk-3 inversely correlates with NOS2. Thus, Elk-3 may serve as an important mediator of NOS2 gene expression.

  3. An Autocrine Proliferation Repressor Regulates Dictyostelium discoideum Proliferation and Chemorepulsion Using the G Protein-Coupled Receptor GrlH

    Directory of Open Access Journals (Sweden)

    Yu Tang

    2018-02-01

    Full Text Available In eukaryotic microbes, little is known about signals that inhibit the proliferation of the cells that secrete the signal, and little is known about signals (chemorepellents that cause cells to move away from the source of the signal. Autocrine proliferation repressor protein A (AprA is a protein secreted by the eukaryotic microbe Dictyostelium discoideum. AprA is a chemorepellent for and inhibits the proliferation of D. discoideum. We previously found that cells sense AprA using G proteins, suggesting the existence of a G protein-coupled AprA receptor. To identify the AprA receptor, we screened mutants lacking putative G protein-coupled receptors. We found that, compared to the wild-type strain, cells lacking putative receptor GrlH (grlH{macron} cells show rapid proliferation, do not have large numbers of cells moving away from the edges of colonies, are insensitive to AprA-induced proliferation inhibition and chemorepulsion, and have decreased AprA binding. Expression of GrlH in grlH{macron} cells (grlH{macron}/grlHOE rescues the phenotypes described above. These data indicate that AprA signaling may be mediated by GrlH in D. discoideum.

  4. High-throughput cell-based screening reveals a role for ZNF131 as a repressor of ERalpha signaling

    Directory of Open Access Journals (Sweden)

    Du Peige

    2008-10-01

    Full Text Available Abstract Background Estrogen receptor α (ERα is a transcription factor whose activity is affected by multiple regulatory cofactors. In an effort to identify the human genes involved in the regulation of ERα, we constructed a high-throughput, cell-based, functional screening platform by linking a response element (ERE with a reporter gene. This allowed the cellular activity of ERα, in cells cotransfected with the candidate gene, to be quantified in the presence or absence of its cognate ligand E2. Results From a library of 570 human cDNA clones, we identified zinc finger protein 131 (ZNF131 as a repressor of ERα mediated transactivation. ZNF131 is a typical member of the BTB/POZ family of transcription factors, and shows both ubiquitous expression and a high degree of sequence conservation. The luciferase reporter gene assay revealed that ZNF131 inhibits ligand-dependent transactivation by ERα in a dose-dependent manner. Electrophoretic mobility shift assay clearly demonstrated that the interaction between ZNF131 and ERα interrupts or prevents ERα binding to the estrogen response element (ERE. In addition, ZNF131 was able to suppress the expression of pS2, an ERα target gene. Conclusion We suggest that the functional screening platform we constructed can be applied for high-throughput genomic screening candidate ERα-related genes. This in turn may provide new insights into the underlying molecular mechanisms of ERα regulation in mammalian cells.

  5. Cloning and characterization of GETS-1, a goldfish Ets family member that functions as a transcriptional repressor in muscle.

    Science.gov (United States)

    Goldman, D; Sapru, M K; Stewart, S; Plotkin, J; Libermann, T A; Wasylyk, B; Guan, K

    1998-10-15

    An Ets transcription factor family member, GETS-1, was cloned from a goldfish retina cDNA library. GETS-1 contains a conserved Ets DNA-binding domain at its N-terminus and is most similar to ternary complex factor (TCF) serum-response-factor protein-1a (SAP-1a). GETS-1 is expressed in many tissues, but is enriched in retina and brain. As with the TCFs SAP-1a and ets-related protein (ERP), overexpression of the GETS-1 promoter suppresses nicotinic acetylcholine receptor epsilon-subunit gene expression in cultured muscle cells. A consensus Ets binding site sequence in the promoter of the epsilon-subunit gene is required for GETS-1-mediated repression. GETS-1 repressor activity is abrogated by overexpression of an activated Ras/mitogen-activated protein kinase (MAP kinase) or by mutation of Ser-405, a MAP kinase phosphorylation site in GETS-1. Fusion proteins created between GETS-1 and the Gal4 DNA-binding domain show that, like other TCFs, GETS-1 contains a C-terminal activation domain that is activated by a Ras/MAP kinase signalling cascade. Interestingly, mutation of Ser-405 located within this activation domain abrogated transcriptional activation of the fusion protein.

  6. Rce1, a novel transcriptional repressor, regulates cellulase gene expression by antagonizing the transactivator Xyr1 in Trichoderma reesei.

    Science.gov (United States)

    Cao, Yanli; Zheng, Fanglin; Wang, Lei; Zhao, Guolei; Chen, Guanjun; Zhang, Weixin; Liu, Weifeng

    2017-07-01

    Cellulase gene expression in the model cellulolytic fungus Trichoderma reesei is supposed to be controlled by an intricate regulatory network involving multiple transcription factors. Here, we identified a novel transcriptional repressor of cellulase gene expression, Rce1. Disruption of the rce1 gene not only facilitated the induced expression of cellulase genes but also led to a significant delay in terminating the induction process. However, Rce1 did not participate in Cre1-mediated catabolite repression. Electrophoretic mobility shift (EMSA) and DNase I footprinting assays in combination with chromatin immunoprecipitation (ChIP) demonstrated that Rce1 could bind directly to a cbh1 (cellobiohydrolase 1-encoding) gene promoter region containing a cluster of Xyr1 binding sites. Furthermore, competitive binding assays revealed that Rce1 antagonized Xyr1 from binding to the cbh1 promoter. These results indicate that intricate interactions exist between a variety of transcription factors to ensure tight and energy-efficient regulation of cellulase gene expression in T. reesei. This study also provides important clues regarding increased cellulase production in T. reesei. © 2017 John Wiley & Sons Ltd.

  7. MDM2 Associates with Polycomb Repressor Complex 2 and Enhances Stemness-Promoting Chromatin Modifications Independent of p53.

    Science.gov (United States)

    Wienken, Magdalena; Dickmanns, Antje; Nemajerova, Alice; Kramer, Daniela; Najafova, Zeynab; Weiss, Miriam; Karpiuk, Oleksandra; Kassem, Moustapha; Zhang, Yanping; Lozano, Guillermina; Johnsen, Steven A; Moll, Ute M; Zhang, Xin; Dobbelstein, Matthias

    2016-01-07

    The MDM2 oncoprotein ubiquitinates and antagonizes p53 but may also carry out p53-independent functions. Here we report that MDM2 is required for the efficient generation of induced pluripotent stem cells (iPSCs) from murine embryonic fibroblasts, in the absence of p53. Similarly, MDM2 depletion in the context of p53 deficiency also promoted the differentiation of human mesenchymal stem cells and diminished clonogenic survival of cancer cells. Most of the MDM2-controlled genes also responded to the inactivation of the Polycomb Repressor Complex 2 (PRC2) and its catalytic component EZH2. MDM2 physically associated with EZH2 on chromatin, enhancing the trimethylation of histone 3 at lysine 27 and the ubiquitination of histone 2A at lysine 119 (H2AK119) at its target genes. Removing MDM2 simultaneously with the H2AK119 E3 ligase Ring1B/RNF2 further induced these genes and synthetically arrested cell proliferation. In conclusion, MDM2 supports the Polycomb-mediated repression of lineage-specific genes, independent of p53. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Drosophila melanogaster cellular repressor of E1A-stimulated genes is a lysosomal protein essential for fly development.

    Science.gov (United States)

    Kowalewski-Nimmerfall, Elisabeth; Schähs, Philipp; Maresch, Daniel; Rendic, Dubravko; Krämer, Helmut; Mach, Lukas

    2014-12-01

    Mammalian cellular repressor of E1A-stimulated genes is a lysosomal glycoprotein implicated in cellular growth and differentiation. The genome of the fruit fly Drosophila melanogaster encodes a putative orthologue (dCREG), suggesting evolutionarily conserved physiological functions of this protein. In D. melanogaster S2 cells, dCREG was found to localize in lysosomes. Further studies revealed that intracellular dCREG is subject of proteolytic maturation. Processing and turnover could be substantially reduced by RNAi-mediated silencing of cathepsin L. In contrast to mammalian cells, lysosomal delivery of dCREG does not depend on its carbohydrate moiety. Furthermore, depletion of the putative D. melanogaster lysosomal sorting receptor lysosomal enzyme receptor protein did not compromise cellular retention of dCREG. We also investigated the developmental consequences of dCREG ablation in whole D. melanogaster flies. Ubiquitous depletion of dCREG proved lethal at the late pupal stage once a knock-down efficiency of >95% was achieved. These results demonstrate that dCREG is essential for proper completion of fly development. Copyright © 2014. Published by Elsevier B.V.

  9. Chick Hairy1 protein interacts with Sap18, a component of the Sin3/HDAC transcriptional repressor complex

    Directory of Open Access Journals (Sweden)

    Andrade Raquel P

    2007-07-01

    Full Text Available Abstract Background The vertebrate adult axial skeleton, trunk and limb skeletal muscles and dermis of the back all arise from early embryonic structures called somites. Somites are symmetrically positioned flanking the embryo axial structures (neural tube and notochord and are periodically formed in a anterior-posterior direction from the presomitic mesoderm. The time required to form a somite pair is constant and species-specific. This extraordinary periodicity is proposed to depend on an underlying somitogenesis molecular clock, firstly evidenced by the cyclic expression of the chick hairy1 gene in the unsegmented presomitic mesoderm with a 90 min periodicity, corresponding to the time required to form a somite pair in the chick embryo. The number of hairy1 oscillations at any given moment is proposed to provide the cell with both temporal and positional information along the embryo's anterior-posterior axis. Nevertheless, how this is accomplished and what biological processes are involved is still unknown. Aiming at understanding the molecular events triggered by the somitogenesis clock Hairy1 protein, we have employed the yeast two-hybrid system to identify Hairy1 interaction partners. Results Sap18, an adaptor molecule of the Sin3/HDAC transcriptional repressor complex, was found to interact with the C-terminal portion of the Hairy1 protein in a yeast two-hybrid assay and the Hairy1/Sap18 interaction was independently confirmed by co-immunoprecipitation experiments. We have characterized the expression patterns of both sap18 and sin3a genes during chick embryo development, using in situ hybridization experiments. We found that both sap18 and sin3a expression patterns co-localize in vivo with hairy1 expression domains in chick rostral presomitic mesoderm and caudal region of somites. Conclusion Hairy1 belongs to the hairy-enhancer-of-split family of transcriptional repressor proteins. Our results indicate that during chick somitogenesis

  10. The transcriptional repressor DREAM is involved in thyroid gene expression

    International Nuclear Information System (INIS)

    D'Andrea, Barbara; Di Palma, Tina; Mascia, Anna; Motti, Maria Letizia; Viglietto, Giuseppe; Nitsch, Lucio; Zannini, Mariastella

    2005-01-01

    Downstream regulatory element antagonistic modulator (DREAM) was originally identified in neuroendocrine cells as a calcium-binding protein that specifically binds to downstream regulatory elements (DRE) on DNA, and represses transcription of its target genes. To explore the possibility that DREAM may regulate the endocrine activity of the thyroid gland, we analyzed its mRNA expression in undifferentiated and differentiated thyroid cells. We demonstrated that DREAM is expressed in the normal thyroid tissue as well as in differentiated thyroid cells in culture while it is absent in FRT poorly differentiated cells. In the present work, we also show that DREAM specifically binds to DRE sites identified in the 5' untranslated region (UTR) of the thyroid-specific transcription factors Pax8 and TTF-2/FoxE1 in a calcium-dependent manner. By gel retardation assays we demonstrated that thapsigargin treatment increases the binding of DREAM to the DRE sequences present in Pax8 and TTF-2/Foxe1 5' UTRs, and this correlates with a significant reduction of the expression of these genes. Interestingly, in poorly differentiated thyroid cells overexpression of exogenous DREAM strongly inhibits Pax8 expression. Moreover, we provide evidence that a mutated form of DREAM unable to bind Ca 2+ interferes with thyroid cell proliferation. Therefore, we propose that in thyroid cells DREAM is a mediator of the calcium-signaling pathway and it is involved in the regulation of thyroid cell function

  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. Lac repressor: Crystallization of intact tetramer and its complexes with inducer and operator DNA

    International Nuclear Information System (INIS)

    Pace, H.C.; Lu, P.; Lewis, M.

    1990-01-01

    The intact lac repressor tetramer, which regulates expression of the lac operon in Escherichia coli, has been crystallized in the native form, with an inducer, and in a ternary complex with operator DNA and an anti-inducer. The crystals without DNA diffract to better than 3.5 angstrom. They belong to the monoclinic space group C2 and have cell dimensions a = 164.7 angstrom, b = 75.6 angstrom, and c = 161.2 angstrom, with α = γ = 90 degree and β = 125.5 degree. Cocrystals have been obtained with a number of different lac operator-related DNA fragments. The complex with a blunt-ended 16-base-pair strand yielded tetragonal bipyramids that diffract to 6.5 angstrom. These protein-DNA cocrystals crack upon exposure to the gratuitous inducer isopropyl β-D-thiogalactoside, suggesting a conformational change in the repressor-operator complex

  13. Targeted transcriptional repression using a chimeric TALE-SRDX repressor protein

    KAUST Repository

    Mahfouz, Magdy M.; Li, Lixin; Piatek, Marek J.; Fang, Xiaoyun; Mansour, Hicham; Bangarusamy, Dhinoth K.; Zhu, Jian-Kang

    2011-01-01

    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

  14. Situational Discrimination in Repressor-type and Sensitizer-type Approval Seekers and the Birth Order by Subject Sex Interaction

    Science.gov (United States)

    Becker, Gilbert

    1970-01-01

    Five experiments are reported. One conclusion in that repressor-type high need-for-approval subjects made the discrimination and permitted less favorable self-description, but sensitizer-type high need-for-approval subjects did not. (DB)

  15. An Autocrine Proliferation Repressor Regulates Dictyostelium discoideum Proliferation and Chemorepulsion Using the G Protein-Coupled Receptor GrlH.

    Science.gov (United States)

    Tang, Yu; Wu, Yuantai; Herlihy, Sarah E; Brito-Aleman, Francisco J; Ting, Jose H; Janetopoulos, Chris; Gomer, Richard H

    2018-02-13

    In eukaryotic microbes, little is known about signals that inhibit the proliferation of the cells that secrete the signal, and little is known about signals (chemorepellents) that cause cells to move away from the source of the signal. Autocrine proliferation repressor protein A (AprA) is a protein secreted by the eukaryotic microbe Dictyostelium discoideum AprA is a chemorepellent for and inhibits the proliferation of D. discoideum We previously found that cells sense AprA using G proteins, suggesting the existence of a G protein-coupled AprA receptor. To identify the AprA receptor, we screened mutants lacking putative G protein-coupled receptors. We found that, compared to the wild-type strain, cells lacking putative receptor GrlH ( grlH¯ cells) show rapid proliferation, do not have large numbers of cells moving away from the edges of colonies, are insensitive to AprA-induced proliferation inhibition and chemorepulsion, and have decreased AprA binding. Expression of GrlH in grlH¯ cells ( grlH¯/grlH OE ) rescues the phenotypes described above. These data indicate that AprA signaling may be mediated by GrlH in D. discoideum IMPORTANCE Little is known about how eukaryotic cells can count themselves and thus regulate the size of a tissue or density of cells. In addition, little is known about how eukaryotic cells can sense a repellant signal and move away from the source of the repellant, for instance, to organize the movement of cells in a developing embryo or to move immune cells out of a tissue. In this study, we found that a eukaryotic microbe uses G protein-coupled receptors to mediate both cell density sensing and chemorepulsion. Copyright © 2018 Tang et al.

  16. Dissociation of SERPINE1 mRNA from the translational repressor proteins Ago2 and TIA-1 upon platelet activation.

    Science.gov (United States)

    Corduan, Aurélie; Plé, Hélène; Laffont, Benoit; Wallon, Thérèse; Plante, Isabelle; Landry, Patricia; Provost, Patrick

    2015-05-01

    Platelets play an important role in haemostasis, as well as in thrombosis and coagulation processes. They harbour a wide variety of messenger RNAs (mRNAs), that can template de novo protein synthesis, and an abundant array of microRNAs, which are known to mediate mRNA translational repression through proteins of the Argonaute (Ago) family. The relationship between platelet microRNAs and proteins capable of mediating translational repression, however, remains unclear. Here, we report that half of platelet microRNAs is associated to mRNA-regulatory Ago2 protein complexes, in various proportions. Associated to these Ago2 complexes are platelet mRNAs known to support de novo protein synthesis. Reporter gene activity assays confirmed the capacity of the platelet microRNAs, found to be associated to Ago2 complexes, to regulate translation of these platelet mRNAs through their 3'UTR. Neither the microRNA repertoire nor the microRNA composition of Ago2 complexes of human platelets changed upon activation with thrombin. However, under conditions favoring de novo synthesis of Plasminogen Activator Inhibitor-1 (PAI-1) protein, we documented a rapid dissociation of the encoding platelet SERPINE1 mRNA from Ago2 protein complexes as well as from the translational repressor protein T-cell-restricted intracellular antigen-1 (TIA-1). These findings are consistent with a scenario by which lifting of the repressive effects of Ago2 and TIA-1 protein complexes, involving a rearrangement of proteinmRNA complexes rather than disassembly of Ago2microRNA complexes, would allow translation of SERPINE1 mRNA into PAI-1 in response to platelet activation.

  17. The role of the leukemia-associated ETO homologue repressors in hematopoiesis

    OpenAIRE

    Olsson, André

    2006-01-01

    The fusion protein AML1-ETO is observed in acute myeloid patients with the chromosomal translocation t(8;21). Cells with this chimeric protein have impaired granulocytic and erythroid differentiation with accumulation of myeloblasts. The transcriptional co-repressor ETO (Eight Twenty One) was identified from the cloning of AML1-ETO. Subsequently, MTGR1 (Myeloid Translocation Gene-Related protein 1) and MTG16 (Myeloid Translocation Gene on chromosome 16) were found to be homologues to ETO, all...

  18. Loss of the RNA polymerase III repressor MAF1 confers obesity resistance.

    OpenAIRE

    Bonhoure, N.; Byrnes, A.; Moir, R.D.; Hodroj, W.; Preitner, F.; Praz, V.; Marcelin, G.; Chua, S.C.; Martinez-Lopez, N.; Singh, R.; Moullan, N.; Auwerx, J.; Willemin, G.; Shah, H.; Hartil, K.

    2015-01-01

    MAF1 is a global repressor of RNA polymerase III transcription that regulates the expression of highly abundant noncoding RNAs in response to nutrient availability and cellular stress. Thus, MAF1 function is thought to be important for metabolic economy. Here we show that a whole-body knockout of Maf1 in mice confers resistance to diet-induced obesity and nonalcoholic fatty liver disease by reducing food intake and increasing metabolic inefficiency. Energy expenditure in Maf1(-/-) mice is inc...

  19. Histone deacetylase inhibitor trichostatin A enhances myogenesis by coordinating muscle regulatory factors and myogenic repressors

    International Nuclear Information System (INIS)

    Hagiwara, Hiroki; Saito, Fumiaki; Masaki, Toshihiro; Ikeda, Miki; Nakamura-Ohkuma, Ayami; Shimizu, Teruo; Matsumura, Kiichiro

    2011-01-01

    Highlights: ► We investigated the effect of TSA, one of most potent HDACIs, on myogenesis using the C2C12 skeletal muscle cell line. ► TSA enhances the expression of myosin heavy chain without affecting DAPC expression. ► TSA enhances the expression of the early MRFs, Myf5 and MEF2, and suppresses the late MRF, myogenin, after 24 h treatment. ► TSA enhances the expression of the myogenic repressors, Ids, which inhibit myogenic differentiation. ► TSA promotes myogenesis by coordinating the expression of MRFs and myogenic repressors. -- Abstract: Histone deacetylase inhibitors (HDACIs) are known to promote skeletal muscle formation. However, their mechanisms that include effects on the expression of major muscle components such as the dystrophin-associated proteins complex (DAPC) or myogenic regulatory factors (MRFs) remain unknown. In this study, we investigated the effects of HDACIs on skeletal muscle formation using the C2C12 cell culture system. C2C12 myoblasts were exposed to trichostatin A (TSA), one of the most potent HDACIs, and differentiation was subsequently induced. We found that TSA enhances the expression of myosin heavy chain without affecting DAPC expression. In addition, TSA increases the expression of the early MRFs, Myf5 and MEF2, whereas it suppresses the expression of the late MRF, myogenin. Interestingly, TSA also enhances the expression of Id1, Id2, and Id3 (Ids). Ids are myogenic repressors that inhibit myogenic differentiation. These findings suggest that TSA promotes gene expression in proliferation and suppresses it in the differentiation stage of muscle formation. Taken together, our data demonstrate that TSA enhances myogenesis by coordinating the expression of MRFs and myogenic repressors.

  20. Regulation of gene expression by manipulating transcriptional repressor activity using a novel CoSRI technology.

    Science.gov (United States)

    Xu, Yue; Li, Song Feng; Parish, Roger W

    2017-07-01

    Targeted gene manipulation is a central strategy for studying gene function and identifying related biological processes. However, a methodology for manipulating the regulatory motifs of transcription factors is lacking as these factors commonly possess multiple motifs (e.g. repression and activation motifs) which collaborate with each other to regulate multiple biological processes. We describe a novel approach designated conserved sequence-guided repressor inhibition (CoSRI) that can specifically reduce or abolish the repressive activities of transcription factors in vivo. The technology was evaluated using the chimeric MYB80-EAR transcription factor and subsequently the endogenous WUS transcription factor. The technology was employed to develop a reversible male sterility system applicable to hybrid seed production. In order to determine the capacity of the technology to regulate the activity of endogenous transcription factors, the WUS repressor was chosen. The WUS repression motif could be inhibited in vivo and the transformed plants exhibited the wus-1 phenotype. Consequently, the technology can be used to manipulate the activities of transcriptional repressor motifs regulating beneficial traits in crop plants and other eukaryotic organisms. © 2016 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

  1. Evaluation of novel inducible promoter/repressor systems for recombinant protein expression in Lactobacillus plantarum.

    Science.gov (United States)

    Heiss, Silvia; Hörmann, Angelika; Tauer, Christopher; Sonnleitner, Margot; Egger, Esther; Grabherr, Reingard; Heinl, Stefan

    2016-03-10

    Engineering lactic acid bacteria (LAB) is of growing importance for food and feed industry as well as for in vivo vaccination or the production of recombinant proteins in food grade organisms. Often, expression of a transgene is only desired at a certain time point or period, e.g. to minimize the metabolic burden for the host cell or to control the expression time span. For this purpose, inducible expression systems are preferred, though cost and availability of the inducing agent must be feasible. We selected the plasmid free strain Lactobacillus plantarum 3NSH for testing and characterization of novel inducible promoters/repressor systems. Their feasibility in recombinant protein production was evaluated. Expression of the reporter protein mCherry was monitored with the BioLector(®) micro-fermentation system. Reporter gene mCherry expression was compared under the control of different promoter/repressor systems: PlacA (an endogenous promoter/repressor system derived from L. plantarum 3NSH), PxylA (a promoter/repressor system derived from Bacillus megaterium DSMZ 319) and PlacSynth (synthetic promoter and codon-optimized repressor gene based on the Escherichia coli lac operon). We observed that PlacA was inducible solely by lactose, but not by non-metabolizable allolactose analoga. PxylA was inducible by xylose, yet showed basal expression under non-induced conditions. Growth on galactose (as compared to exponential growth phase on glucose) reduced basal mCherry expression at non-induced conditions. PlacSynth was inducible with TMG (methyl β-D-thiogalactopyranoside) and IPTG (isopropyl β-D-1-thiogalactopyranoside), but also showed basal expression without inducer. The promoter PlacSynth was used for establishment of a dual plasmid expression system, based on T7 RNA polymerase driven expression in L. plantarum. Comparative Western blot supported BioLector(®) micro-fermentation measurements. Conclusively, overall expression levels were moderate (compared to a

  2. The N-terminal domain of the repressor of Staphylococcus aureus phage Φ11 possesses an unusual dimerization ability and DNA binding affinity.

    Directory of Open Access Journals (Sweden)

    Anindya Biswas

    Full Text Available Bacteriophage Φ11 uses Staphylococcus aureus as its host and, like lambdoid phages, harbors three homologous operators in between its two divergently oriented repressor genes. None of the repressors of Φ11, however, showed binding to all three operators, even at high concentrations. To understand why the DNA binding mechanism of Φ11 repressors does not match that of lambdoid phage repressors, we studied the N-terminal domain of the Φ11 lysogenic repressor, as it harbors a putative helix-turn-helix motif. Our data revealed that the secondary and tertiary structures of the N-terminal domain were different from those of the full-length repressor. Nonetheless, the N-terminal domain was able to dimerize and bind to the operators similar to the intact repressor. In addition, the operator base specificity, binding stoichiometry, and binding mechanism of this domain were nearly identical to those of the whole repressor. The binding affinities of the repressor and its N-terminal domain were reduced to a similar extent when the temperature was increased to 42°C. Both proteins also adequately dislodged a RNA polymerase from a Φ11 DNA fragment carrying two operators and a promoter. Unlike the intact repressor, the binding of the N-terminal domain to two adjacent operator sites was not cooperative in nature. Taken together, we suggest that the dimerization and DNA binding abilities of the N-terminal domain of the Φ11 repressor are distinct from those of the DNA binding domains of other phage repressors.

  3. The switch from fermentation to respiration in Saccharomyces cerevisiae is regulated by the Ert1 transcriptional activator/repressor.

    Science.gov (United States)

    Gasmi, Najla; Jacques, Pierre-Etienne; Klimova, Natalia; Guo, Xiao; Ricciardi, Alessandra; Robert, François; Turcotte, Bernard

    2014-10-01

    In the yeast Saccharomyces cerevisiae, fermentation is the major pathway for energy production, even under aerobic conditions. However, when glucose becomes scarce, ethanol produced during fermentation is used as a carbon source, requiring a shift to respiration. This adaptation results in massive reprogramming of gene expression. Increased expression of genes for gluconeogenesis and the glyoxylate cycle is observed upon a shift to ethanol and, conversely, expression of some fermentation genes is reduced. The zinc cluster proteins Cat8, Sip4, and Rds2, as well as Adr1, have been shown to mediate this reprogramming of gene expression. In this study, we have characterized the gene YBR239C encoding a putative zinc cluster protein and it was named ERT1 (ethanol regulated transcription factor 1). ChIP-chip analysis showed that Ert1 binds to a limited number of targets in the presence of glucose. The strongest enrichment was observed at the promoter of PCK1 encoding an important gluconeogenic enzyme. With ethanol as the carbon source, enrichment was observed with many additional genes involved in gluconeogenesis and mitochondrial function. Use of lacZ reporters and quantitative RT-PCR analyses demonstrated that Ert1 regulates expression of its target genes in a manner that is highly redundant with other regulators of gluconeogenesis. Interestingly, in the presence of ethanol, Ert1 is a repressor of PDC1 encoding an important enzyme for fermentation. We also show that Ert1 binds directly to the PCK1 and PDC1 promoters. In summary, Ert1 is a novel factor involved in the regulation of gluconeogenesis as well as a key fermentation gene. Copyright © 2014 by the Genetics Society of America.

  4. Regulation of nif expression in Methanococcus maripaludis: roles of the euryarchaeal repressor NrpR, 2-oxoglutarate, and two operators.

    Science.gov (United States)

    Lie, Thomas J; Wood, Gwendolyn E; Leigh, John A

    2005-02-18

    The methanogenic archaean Methanococcus maripaludis can use ammonia, alanine, or dinitrogen as a nitrogen source for growth. The euryarchaeal nitrogen repressor NrpR controls the expression of the nif (nitrogen fixation) operon, resulting in full repression with ammonia, intermediate repression with alanine, and derepression with dinitrogen. NrpR binds to two tandem operators in the nif promoter region, nifOR(1) and nifOR(2). Here we have undertaken both in vivo and in vitro approaches to study the way in which NrpR, nifOR(1), nifOR(2), and the effector 2-oxoglutarate (2OG) combine to regulate nif expression, leading to a comprehensive understanding of this archaeal regulatory system. We show that NrpR binds as a dimer to nifOR(1) and cooperatively as two dimers to both operators. Cooperative binding occurs only with both operators present. nifOR(1) has stronger binding and by itself can mediate the repression of nif transcription during growth on ammonia, unlike the weakly binding nifOR(2). However, nifOR(2) in combination with nifOR(1) is critical for intermediate repression during growth on alanine. Accordingly, NrpR binds to both operators together with higher affinity than to nifOR(1) alone. NrpR responds directly to 2OG, which weakens its binding to the operators. Hence, 2OG is an intracellular indicator of nitrogen deficiency and acts as an inducer of nif transcription via NrpR. This model is upheld by the recent finding (J. A. Dodsworth and J. A. Leigh, submitted for publication) in our laboratory that 2OG levels in M. maripaludis vary with growth on different nitrogen sources.

  5. Functional regulation of Q by microRNA172 and transcriptional co-repressor TOPLESS in controlling bread wheat spikelet density.

    Science.gov (United States)

    Liu, Pan; Liu, Jie; Dong, Huixue; Sun, Jiaqiang

    2018-02-01

    Bread wheat (Triticum aestivum) spike architecture is an important agronomic trait. The Q gene plays a key role in the domestication of bread wheat spike architecture. However, the regulatory mechanisms of Q expression and transcriptional activity remain largely unknown. In this study, we show that overexpression of bread wheat tae-miR172 caused a speltoid-like spike phenotype, reminiscent of that in wheat plants with the q gene. The reduction in Q transcript levels in the tae-miR172 overexpression transgenic bread wheat lines suggests that the Q expression can be suppressed by tae-miR172 in bread wheat. Indeed, our RACE analyses confirmed that the Q mRNA is targeted by tae-miR172 for cleavage. According to our analyses, the Q protein is localized in nucleus and confers transcriptional repression activity. Meanwhile, the Q protein could physically interact with the bread wheat transcriptional co-repressor TOPLESS (TaTPL). Specifically, the N-terminal ethylene-responsive element binding factor-associated amphiphilic repression (EAR) (LDLNVE) motif but not the C-terminal EAR (LDLDLR) motif of Q protein mediates its interaction with the CTLH motif of TaTPL. Moreover, we show that the N-terminal EAR motif of Q protein is also essentially required for the transcriptional repression activity of Q protein. Taken together, we reveal the functional regulation of Q protein by tae-miR172 and transcriptional co-repressor TaTPL in controlling the bread wheat spike architecture. © 2017 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

  6. Disruption of a Transcriptional Repressor by an Insertion Sequence Element Integration Leads to Activation of a Novel Silent Cellobiose Transporter in Lactococcus lactis MG1363.

    Science.gov (United States)

    Solopova, Ana; Kok, Jan; Kuipers, Oscar P

    2017-12-01

    Lactococcus lactis subsp. cremoris strains typically carry many dairy niche-specific adaptations. During adaptation to the milk environment these former plant strains have acquired various pseudogenes and insertion sequence elements indicative of ongoing genome decay and frequent transposition events in their genomes. Here we describe the reactivation of a silenced plant sugar utilization cluster in an L. lactis MG1363 derivative lacking the two main cellobiose transporters, PtcBA-CelB and PtcBAC, upon applying selection pressure to utilize cellobiose. A disruption of the transcriptional repressor gene llmg_1239 by an insertion sequence (IS) element allows expression of the otherwise silent novel cellobiose transporter Llmg_1244 and leads to growth of mutant strains on cellobiose. Llmg_1239 was labeled CclR, for c ellobiose cl uster r epressor. IMPORTANCE Insertion sequences (ISs) play an important role in the evolution of lactococci and other bacteria. They facilitate DNA rearrangements and are responsible for creation of new genetic variants with selective advantages under certain environmental conditions. L. lactis MG1363 possesses 71 copies in a total of 11 different types of IS elements. This study describes yet another example of an IS-mediated adaptive evolution. An integration of IS 981 or IS 905 into a gene coding for a transcriptional repressor led to activation of the repressed gene cluster coding for a plant sugar utilization pathway. The expression of the gene cluster allowed assembly of a novel cellobiose-specific transporter and led to cell growth on cellobiose. Copyright © 2017 American Society for Microbiology.

  7. The B-subdomain of the Xenopus laevis XFIN KRAB-AB domain is responsible for its weaker transcriptional repressor activity compared to human ZNF10/Kox1.

    Science.gov (United States)

    Born, Nadine; Thiesen, Hans-Jürgen; Lorenz, Peter

    2014-01-01

    The Krüppel-associated box (KRAB) domain interacts with the nuclear hub protein TRIM28 to initiate or mediate chromatin-dependent processes like transcriptional repression, imprinting or suppression of endogenous retroviruses. The prototype KRAB domain initially identified in ZNF10/KOX1 encompasses two subdomains A and B that are found in hundreds of zinc finger transcription factors studied in human and murine genomes. Here we demonstrate for the first time transcriptional repressor activity of an amphibian KRAB domain. After sequence correction, the updated KRAB-AB domain of zinc finger protein XFIN from the frog Xenopus laevis was found to confer transcriptional repression in reporter assays in Xenopus laevis A6 kidney cells as well as in human HeLa, but not in the minnow Pimephales promelas fish cell line EPC. Binding of the XFIN KRAB-AB domain to human TRIM28 was demonstrated in a classical co-immunoprecipitation approach and visualized in a single-cell compartmentalization assay. XFIN-AB displayed reduced potency in repression as well as lower strength of interaction with TRIM28 compared to ZNF10 KRAB-AB. KRAB-B subdomain swapping between the two KRAB domains indicated that it was mainly the KRAB-B subdomain of XFIN that was responsible for its lower capacity in repression and binding to human TRIM28. In EPC fish cells, ZNF10 and XFIN KRAB repressor activity could be partially restored to low levels by adding exogenous human TRIM28. In contrast to XFIN, we did not find any transcriptional repression activity for the KRAB-like domain of human PRDM9 in HeLa cells. PRDM9 is thought to harbor an evolutionary older domain related to KRAB whose homologs even occur in invertebrates. Our results support the notion that functional bona fide KRAB domains which confer transcriptional repression and interact with TRIM28 most likely co-evolved together with TRIM28 at the beginning of tetrapode evolution.

  8. FOXP3 is a novel transcriptional repressor for the breast cancer oncogene SKP2

    OpenAIRE

    Zuo, Tao; Liu, Runhua; Zhang, Huiming; Chang, Xing; Liu, Yan; Wang, Lizhong; Zheng, Pan; Liu, Yang

    2007-01-01

    S-phase kinase-associated protein 2 (SKP2) is a component of the E3 ubiquitin ligase SKP1-Cul1-Fbox complex. Overexpression of SKP2 results in cell cycle dysregulation and carcinogenesis; however, the genetic lesions that cause this upregulation are poorly understood. We recently demonstrated that forkhead box P3 (FOXP3) is an X-linked breast cancer suppressor and an important repressor of the oncogene ERBB2/HER2. Since FOXP3 suppresses tumor growth regardless of whether the tumors overexpres...

  9. The metazoan Mediator co-activator complex as an integrative hub for transcriptional regulation

    OpenAIRE

    Malik, Sohail; Roeder, Robert G.

    2010-01-01

    The Mediator is an evolutionarily conserved, multiprotein complex that is a key regulator of protein-coding genes. In metazoan cells, multiple pathways that are responsible for homeostasis, cell growth and differentiation converge on the Mediator through transcriptional activators and repressors that target one or more of the almost 30 subunits of this complex. Besides interacting directly with RNA polymerase II, Mediator has multiple functions and can interact with and coordinate the action ...

  10. Animal-specific C-terminal domain links myeloblastosis oncoprotein (Myb) to an ancient repressor complex

    Science.gov (United States)

    Andrejka, Laura; Wen, Hong; Ashton, Jonathan; Grant, Megan; Iori, Kevin; Wang, Amy; Manak, J. Robert; Lipsick, Joseph S.

    2011-01-01

    Members of the Myb oncoprotein and E2F-Rb tumor suppressor protein families are present within the same highly conserved multiprotein transcriptional repressor complex, named either as Myb and synthetic multivuval class B (Myb-MuvB) or as Drosophila Rb E2F and Myb-interacting proteins (dREAM). We now report that the animal-specific C terminus of Drosophila Myb but not the more highly conserved N-terminal DNA-binding domain is necessary and sufficient for (i) adult viability, (ii) proper localization to chromosomes in vivo, (iii) regulation of gene expression in vivo, and (iv) interaction with the highly conserved core of the MuvB/dREAM transcriptional repressor complex. In addition, we have identified a conserved peptide motif that is required for this interaction. Our results imply that an ancient function of Myb in regulating G2/M genes in both plants and animals appears to have been transferred from the DNA-binding domain to the animal-specific C-terminal domain. Increased expression of B-MYB/MYBL2, the human ortholog of Drosophila Myb, correlates with poor prognosis in human patients with breast cancer. Therefore, our results imply that the specific interaction of the C terminus of Myb with the MuvB/dREAM core complex may provide an attractive target for the development of cancer therapeutics. PMID:21969598

  11. DAX1 suppresses FXR transactivity as a novel co-repressor

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jin; Lu, Yan; Liu, Ruya; Xiong, Xuelian; Zhang, Zhijian; Zhang, Xianfeng [Shanghai Clinical Center for Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Department of Endocrinology and Metabolism, Rui-Jin Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai 200025 (China); Ning, Guang, E-mail: guangning@gmail.com.cn [Shanghai Clinical Center for Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Department of Endocrinology and Metabolism, Rui-Jin Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai 200025 (China); The Key Laboratory of Endocrine Tumors and The Division of Endocrine and Metabolic Diseases, E-Institute of Shanghai Universities, Shanghai 200025 (China); Li, Xiaoying, E-mail: lixy@sibs.ac.cn [Shanghai Clinical Center for Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Department of Endocrinology and Metabolism, Rui-Jin Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai 200025 (China); The Key Laboratory of Endocrine Tumors and The Division of Endocrine and Metabolic Diseases, E-Institute of Shanghai Universities, Shanghai 200025 (China)

    2011-09-09

    Highlights: {yields} DAX1 is co-localized with FXR and interacts with FXR. {yields} DAX1 acts as a negative regulator of FXR. {yields} Three LXXLL motifs in the N-terminus of DAX1 were required. {yields} DAX1 suppresses FXR transactivation by competing with co-activators. -- Abstract: Bile acid receptor FXR (farnesoid X receptor) is a key regulator of hepatic bile acid, glucose and lipid homeostasis through regulation of numerous genes involved in the process of bile acid, triglyceride and glucose metabolism. DAX1 (dosage-sensitive sex reversal adrenal hypoplasia congenital critical region on X chromosome, gene 1) is an atypical member of the nuclear receptor family due to lack of classical DNA-binding domains and acts primarily as a co-repressor of many nuclear receptors. Here, we demonstrated that DAX1 is co-localized with FXR in the nucleus and acted as a negative regulator of FXR through a physical interaction with FXR. Our study showed that over-expression of DAX1 down-regulated the expression of FXR target genes, whereas knockdown of DAX1 led to their up-regulation. Furthermore, three LXXLL motifs in the N-terminus of DAX1 were required for the full repression of FXR transactivation. In addition, our study characterized that DAX1 suppresses FXR transactivation via competing with co-activators such as SRC-1 and PGC-1{alpha}. In conclusion, DAX1 acts as a co-repressor to negatively modulate FXR transactivity.

  12. DAX1 suppresses FXR transactivity as a novel co-repressor

    International Nuclear Information System (INIS)

    Li, Jin; Lu, Yan; Liu, Ruya; Xiong, Xuelian; Zhang, Zhijian; Zhang, Xianfeng; Ning, Guang; Li, Xiaoying

    2011-01-01

    Highlights: → DAX1 is co-localized with FXR and interacts with FXR. → DAX1 acts as a negative regulator of FXR. → Three LXXLL motifs in the N-terminus of DAX1 were required. → DAX1 suppresses FXR transactivation by competing with co-activators. -- Abstract: Bile acid receptor FXR (farnesoid X receptor) is a key regulator of hepatic bile acid, glucose and lipid homeostasis through regulation of numerous genes involved in the process of bile acid, triglyceride and glucose metabolism. DAX1 (dosage-sensitive sex reversal adrenal hypoplasia congenital critical region on X chromosome, gene 1) is an atypical member of the nuclear receptor family due to lack of classical DNA-binding domains and acts primarily as a co-repressor of many nuclear receptors. Here, we demonstrated that DAX1 is co-localized with FXR in the nucleus and acted as a negative regulator of FXR through a physical interaction with FXR. Our study showed that over-expression of DAX1 down-regulated the expression of FXR target genes, whereas knockdown of DAX1 led to their up-regulation. Furthermore, three LXXLL motifs in the N-terminus of DAX1 were required for the full repression of FXR transactivation. In addition, our study characterized that DAX1 suppresses FXR transactivation via competing with co-activators such as SRC-1 and PGC-1α. In conclusion, DAX1 acts as a co-repressor to negatively modulate FXR transactivity.

  13. Solution NMR investigation of the response of the lactose repressor core domain dimer to hydrostatic pressure.

    Science.gov (United States)

    Fuglestad, Brian; Stetz, Matthew A; Belnavis, Zachary; Wand, A Joshua

    2017-12-01

    Previous investigations of the sensitivity of the lac repressor to high-hydrostatic pressure have led to varying conclusions. Here high-pressure solution NMR spectroscopy is used to provide an atomic level view of the pressure induced structural transition of the lactose repressor regulatory domain (LacI* RD) bound to the ligand IPTG. As the pressure is raised from ambient to 3kbar the native state of the protein is converted to a partially unfolded form. Estimates of rotational correlation times using transverse optimized relaxation indicates that a monomeric state is never reached and that the predominate form of the LacI* RD is dimeric throughout this pressure change. Spectral analysis suggests that the pressure-induced transition is localized and is associated with a volume change of approximately -115mlmol -1 and an average pressure dependent change in compressibility of approximately 30mlmol -1 kbar -1 . In addition, a subset of resonances emerge at high-pressures indicating the presence of a non-native but folded alternate state. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Safety mechanism assisted by the repressor of tetracycline (SMART) vaccinia virus vectors for vaccines and therapeutics.

    Science.gov (United States)

    Grigg, Patricia; Titong, Allison; Jones, Leslie A; Yilma, Tilahun D; Verardi, Paulo H

    2013-09-17

    Replication-competent viruses, such as Vaccinia virus (VACV), are powerful tools for the development of oncolytic viral therapies and elicit superior immune responses when used as vaccine and immunotherapeutic vectors. However, severe complications from uncontrolled viral replication can occur, particularly in immunocompromised individuals or in those with other predisposing conditions. VACVs constitutively expressing interferon-γ (IFN-γ) replicate in cell culture indistinguishably from control viruses; however, they replicate in vivo to low or undetectable levels, and are rapidly cleared even in immunodeficient animals. In an effort to develop safe and highly effective replication-competent VACV vectors, we established a system to inducibly express IFN-γ. Our SMART (safety mechanism assisted by the repressor of tetracycline) vectors are designed to express the tetracycline repressor under a constitutive VACV promoter and IFN-γ under engineered tetracycline-inducible promoters. Immunodeficient SCID mice inoculated with VACVs not expressing IFN-γ demonstrated severe weight loss, whereas those given VACVs expressing IFN-γ under constitutive VACV promoters showed no signs of infection. Most importantly, mice inoculated with a VACV expressing the IFN-γ gene under an inducible promoter remained healthy in the presence of doxycycline, but exhibited severe weight loss in the absence of doxycycline. In this study, we developed a safety mechanism for VACV based on the conditional expression of IFN-γ under a tightly controlled tetracycline-inducible VACV promoter for use in vaccines and oncolytic cancer therapies.

  15. Drosophila brakeless interacts with atrophin and is required for tailless-mediated transcriptional repression in early embryos.

    Science.gov (United States)

    Haecker, Achim; Qi, Dai; Lilja, Tobias; Moussian, Bernard; Andrioli, Luiz Paulo; Luschnig, Stefan; Mannervik, Mattias

    2007-06-01

    Complex gene expression patterns in animal development are generated by the interplay of transcriptional activators and repressors at cis-regulatory DNA modules (CRMs). How repressors work is not well understood, but often involves interactions with co-repressors. We isolated mutations in the brakeless gene in a screen for maternal factors affecting segmentation of the Drosophila embryo. Brakeless, also known as Scribbler, or Master of thickveins, is a nuclear protein of unknown function. In brakeless embryos, we noted an expanded expression pattern of the Krüppel (Kr) and knirps (kni) genes. We found that Tailless-mediated repression of kni expression is impaired in brakeless mutants. Tailless and Brakeless bind each other in vitro and interact genetically. Brakeless is recruited to the Kr and kni CRMs, and represses transcription when tethered to DNA. This suggests that Brakeless is a novel co-repressor. Orphan nuclear receptors of the Tailless type also interact with Atrophin co-repressors. We show that both Drosophila and human Brakeless and Atrophin interact in vitro, and propose that they act together as a co-repressor complex in many developmental contexts. We discuss the possibility that human Brakeless homologs may influence the toxicity of polyglutamine-expanded Atrophin-1, which causes the human neurodegenerative disease dentatorubral-pallidoluysian atrophy (DRPLA).

  16. SirR, a Novel Iron-Dependent Repressor in Staphylococcus epidermidis

    Science.gov (United States)

    Hill, Philip J.; Cockayne, Alan; Landers, Patrick; Morrissey, Julie A.; Sims, Catriona M.; Williams, Paul

    1998-01-01

    In Staphylococcus epidermidis and Staphylococcus aureus, a number of cell wall- and cytoplasmic membrane-associated lipoproteins are induced in response to iron starvation. To gain insights into the molecular basis of iron-dependent gene regulation in the staphylococci, we sequenced the DNA upstream of the 3-kb S. epidermidis sitABC operon, which Northern blot analysis indicates is transcriptionally regulated by the growth medium iron content. We identified two DNA sequences which are homologous to elements of the Corynebacterium diphtheriae DtxR regulon, which controls, in response to iron stress, for example, production of diphtheria toxin, siderophore, and a heme oxygenase. Upstream of the sitABC operon and divergently transcribed lies a 645-bp open reading frame (ORF), which codes for a polypeptide of approximately 25 kDa with homology to the DtxR family of metal-dependent repressor proteins. This ORF has been designated SirR (staphylococcal iron regulator repressor). Within the sitABC promoter/operator region, we also located a region of dyad symmetry overlapping the transcriptional start of sitABC which shows high homology to the DtxR operator consensus sequence, suggesting that this region, termed the Sir box, is the SirR-binding site. The SirR protein was overexpressed, purified, and used in DNA mobility shift assays; SirR retarded the migration of a synthetic oligonucleotide based on the Sir box in a metal (Fe2+ or Mn2+)-dependent manner, providing confirmatory evidence that this motif is the SirR-binding site. Furthermore, Southern blot analysis of staphylococcal chromosomal DNA with the synthetic Sir box as a probe confirmed that there are at least five Sir boxes in the S. epidermidis genome and at least three in the genome of S. aureus, suggesting that SirR controls the expression of multiple target genes. Using a monospecific polyclonal antibody raised against SirR to probe Western blots of whole-cell lysates of S. aureus, S. carnosus, S. epidermidis

  17. Identification of PNG kinase substrates uncovers interactions with the translational repressor TRAL in the oocyte-to-embryo transition.

    Science.gov (United States)

    Hara, Masatoshi; Lourido, Sebastian; Petrova, Boryana; Lou, Hua Jane; Von Stetina, Jessica R; Kashevsky, Helena; Turk, Benjamin E; Orr-Weaver, Terry L

    2018-02-26

    The Drosophila Pan Gu (PNG) kinase complex regulates hundreds of maternal mRNAs that become translationally repressed or activated as the oocyte transitions to an embryo. In a previous paper (Hara et al., 2017), we demonstrated PNG activity is under tight developmental control and restricted to this transition. Here, examination of PNG specificity showed it to be a Thr-kinase yet lacking a clear phosphorylation site consensus sequence. An unbiased biochemical screen for PNG substrates identified the conserved translational repressor Trailer Hitch (TRAL). Phosphomimetic mutation of the PNG phospho-sites in TRAL reduced its ability to inhibit translation in vitro. In vivo, mutation of tral dominantly suppressed png mutants and restored Cyclin B protein levels. The repressor Pumilio (PUM) has the same relationship with PNG, and we also show that PUM is a PNG substrate. Furthermore, PNG can phosphorylate BICC and ME31B, repressors that bind TRAL in cytoplasmic RNPs. Therefore, PNG likely promotes translation at the oocyte-to-embryo transition by phosphorylating and inactivating translational repressors. © 2018, Hara et al.

  18. Structure of the effector-binding domain of the arabinose repressor AraR from Bacillus subtilis

    Czech Academy of Sciences Publication Activity Database

    Procházková, Kateřina; Čermáková, Kateřina; Pachl, Petr; Sieglová, Irena; Fábry, Milan; Otwinowski, Z.; Řezáčová, Pavlína

    2012-01-01

    Roč. 68, č. 2 (2012), s. 176-185 ISSN 0907-4449 R&D Projects: GA MŠk ME08016 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z50520514 Keywords : repressor * dimerization * effector binding * isothermal titration calorimetry Subject RIV: CE - Biochemistry Impact factor: 14.103, year: 2012

  19. Identification of operator sites of the CI repressor of phage TP901-1: evolutionary link to other phages

    International Nuclear Information System (INIS)

    Johansen, Annette H.; Broendsted, Lone; Hammer, Karin

    2003-01-01

    The repressor encoded by the cI gene of the temperate Lactococcus lactis subsp. cremoris bacteriophage TP901-1 has been purified. Gel-retardation and footprinting analyses identified three palindromic operator sites (O R , O L , and O D ). The operator site O R is located between the two divergent early promoters P R and P L , O L overlaps the transcriptional start of the lytic P L promoter, and O D is located downstream of the mor gene, the first gene in the lytic gene cluster. The function of O L was verified by mutational analysis. Binding was found to be specific and cooperative. Multimeric forms of the repressor were observed, thus indicating that the repressor may bind simultaneously to all three operator sites. Inverted repeats with homology to the operator sites of TP901-1 were identified in phage genomes encoding repressors homologous to CI of TP901-1. Interestingly, the locations of these repeats on the phage genomes correspond to those found in TP901-1, indicating that the same system of cooperative repression of early phage promoters has been inherited by modular evolution

  20. A homozygous mutation in HESX1 is associated with evolving hypopituitarism due to impaired repressor-corepressor interaction

    DEFF Research Database (Denmark)

    Carvalho, Luciani R; Woods, Kathryn S; Mendonca, Berenice B

    2003-01-01

    repressor domain (eh1) of HESX1, the first, to our knowledge, to be described in humans, in a girl with evolving combined pituitary hormone deficiency born to consanguineous parents. Neuroimaging revealed a thin pituitary stalk with anterior pituitary hypoplasia and an ectopic posterior pituitary...

  1. Female Infertility Caused by Mutations in the Oocyte-Specific Translational Repressor PATL2

    KAUST Repository

    Maddirevula, Sateesh

    2017-09-29

    Infertility is a relatively common disorder of the reproductive system and remains unexplained in many cases. In vitro fertilization techniques have uncovered previously unrecognized infertility phenotypes, including oocyte maturation arrest, the molecular etiology of which remains largely unknown. We report two families affected by female-limited infertility caused by oocyte maturation failure. Positional mapping and whole-exome sequencing revealed two homozygous, likely deleterious variants in PATL2, each of which fully segregates with the phenotype within the respective family. PATL2 encodes a highly conserved oocyte-specific mRNP repressor of translation. Previous data have shown the strict requirement for PATL2 in oocyte-maturation in model organisms. Data gathered from the families in this study suggest that the role of PATL2 is conserved in humans and expand our knowledge of the factors that are necessary for female meiosis.

  2. Comprehensive Interrogation of Natural TALE DNA Binding Modules and Transcriptional Repressor Domains

    Science.gov (United States)

    Cong, Le; Zhou, Ruhong; Kuo, Yu-chi; Cunniff, Margaret; Zhang, Feng

    2012-01-01

    Transcription activator-like effectors (TALE) are sequence-specific DNA binding proteins that harbor modular, repetitive DNA binding domains. TALEs have enabled the creation of customizable designer transcriptional factors and sequence-specific nucleases for genome engineering. Here we report two improvements of the TALE toolbox for achieving efficient activation and repression of endogenous gene expression in mammalian cells. We show that the naturally occurring repeat variable diresidue (RVD) Asn-His (NH) has high biological activity and specificity for guanine, a highly prevalent base in mammalian genomes. We also report an effective TALE transcriptional repressor architecture for targeted inhibition of transcription in mammalian cells. These findings will improve the precision and effectiveness of genome engineering that can be achieved using TALEs. PMID:22828628

  3. Plastic downregulation of the transcriptional repressor BCL6 during maturation of human dendritic cells

    International Nuclear Information System (INIS)

    Pantano, Serafino; Jarrossay, David; Saccani, Simona; Bosisio, Daniela; Natoli, Gioacchino

    2006-01-01

    Dendritic cell (DC) maturation links peripheral events initiated by the encounter with pathogens to the activation and expansion of antigen-specific T lymphocytes in secondary lymphoid organs. Here, we describe an as yet unrecognized modulator of human DC maturation, the transcriptional repressor BCL6. We found that both myeloid and plasmacytoid DCs constitutively express BCL6, which is rapidly downregulated following maturation triggered by selected stimuli. Both in unstimulated and maturing DCs, control of BCL6 protein levels reflects the convergence of several mechanisms regulating BCL6 stability, mRNA transcription and nuclear export. By regulating the induction of several genes implicated in the immune response, including inflammatory cytokines, chemokines and survival genes, BCL6 may represent a pivotal modulator of the afferent branch of the immune response

  4. Drosophila arginine methyltransferase 1 (DART1) is an ecdysone receptor co-repressor

    International Nuclear Information System (INIS)

    Kimura, Shuhei; Sawatsubashi, Shun; Ito, Saya; Kouzmenko, Alexander; Suzuki, Eriko; Zhao, Yue; Yamagata, Kaoru; Tanabe, Masahiko; Ueda, Takashi; Fujiyama, Sari; Murata, Takuya; Matsukawa, Hiroyuki; Takeyama, Ken-ichi; Yaegashi, Nobuo

    2008-01-01

    Histone arginine methylation is an epigenetic marker that regulates gene expression by defining the chromatin state. Arginine methyltransferases, therefore, serve as transcriptional co-regulators. However, unlike other transcriptional co-regulators, the physiological roles of arginine methyltransferases are poorly understood. Drosophila arginine methyltransferase 1 (DART1), the mammalian PRMT1 homologue, methylates the arginine residue of histone H4 (H4R3me2). Disruption of DART1 in Drosophila by imprecise P-element excision resulted in low viability during metamorphosis in the pupal stages. In the pupal stage, an ecdysone hormone signal is critical for developmental progression. DART1 interacted with the nuclear ecdysone receptor (EcR) in a ligand-dependent manner, and co-repressed EcR in intact flies. These findings suggest that DART1, a histone arginine methyltransferase, is a co-repressor of EcR that is indispensable for normal pupal development in the intact fly

  5. Brain REST/NRSF Is Not Only a Silent Repressor but Also an Active Protector.

    Science.gov (United States)

    Zhao, Yangang; Zhu, Min; Yu, Yanlan; Qiu, Linli; Zhang, Yuanyuan; He, Li; Zhang, Jiqiang

    2017-01-01

    During neurogenesis, specific transcription factors are needed to repress neuronal genes in nonneuronal cells to ensure precise development. Repressor element-1 binding transcription factor (REST), or neuron-restrictive silencer factor (NRSF), has been shown to be an important regulator for the establishment of neuronal specificity. It restricts the expression of neuronal genes by binding to the neuron-restrictive silencer element (NRSE/RE1) domain in neuron-specific genes. REST/NRSF regulates many target genes in stem cells, nonneural cells, and neurons, which are involved in neuronal differentiation, axonal growth, vesicular transport, and release as well as ionic conductance. However, it is also regulated by some cytokines/regulators such as epigenetic factors (microRNAs) and even its truncated isoform. REST/NRSF is widely detected in brain regions and has been shown to be highly expressed in nonneuronal cells, but current findings also reveal that, at least in the human brain, it is also highly expressed in neurons and increases with ageing. However, its loss in expression and cytoplasmic translocation seems to play a pivotal role in several human dementias. Additionally, REST/NRSF knockdown leads to malformations in nerve and nonneural tissues and embryonic lethality. Altered REST/NRSF expression has been not only related to deficient brain functions such as neurodegenerative diseases, mental disorders, brain tumors, and neurobehavioral disorders but also highly correlated to brain injuries such as alcoholism and stroke. Encouragingly, several compounds such as valproic acid and X5050 that target REST/NRSF have been shown to be clinically effective at rescuing seizures or Niemann-Pick type C disease. Surprisingly, studies have also shown that REST/NRSF can function as an activator to induce neuronal differentiation. These findings strongly indicate that REST/NRSF is not only a classical repressor to maintain normal neurogenesis, but it is also a fine

  6. The metazoan Mediator co-activator complex as an integrative hub for transcriptional regulation.

    Science.gov (United States)

    Malik, Sohail; Roeder, Robert G

    2010-11-01

    The Mediator is an evolutionarily conserved, multiprotein complex that is a key regulator of protein-coding genes. In metazoan cells, multiple pathways that are responsible for homeostasis, cell growth and differentiation converge on the Mediator through transcriptional activators and repressors that target one or more of the almost 30 subunits of this complex. Besides interacting directly with RNA polymerase II, Mediator has multiple functions and can interact with and coordinate the action of numerous other co-activators and co-repressors, including those acting at the level of chromatin. These interactions ultimately allow the Mediator to deliver outputs that range from maximal activation of genes to modulation of basal transcription to long-term epigenetic silencing.

  7. KAP1 regulates type I interferon/STAT1-mediated IRF-1 gene expression

    International Nuclear Information System (INIS)

    Kamitani, Shinya; Ohbayashi, Norihiko; Ikeda, Osamu; Togi, Sumihito; Muromoto, Ryuta; Sekine, Yuichi; Ohta, Kazuhide; Ishiyama, Hironobu; Matsuda, Tadashi

    2008-01-01

    Signal transducers and activators of transcription (STATs) mediate cell proliferation, differentiation, and survival in immune responses, hematopoiesis, neurogenesis, and other biological processes. Recently, we showed that KAP1 is a novel STAT-binding partner that regulates STAT3-mediated transactivation. KAP1 is a universal co-repressor protein for the KRAB zinc finger protein superfamily of transcriptional repressors. In this study, we found KAP1-dependent repression of interferon (IFN)/STAT1-mediated signaling. We also demonstrated that endogenous KAP1 associates with endogenous STAT1 in vivo. Importantly, a small-interfering RNA-mediated reduction in KAP1 expression enhanced IFN-induced STAT1-dependent IRF-1 gene expression. These results indicate that KAP1 may act as an endogenous regulator of the IFN/STAT1 signaling pathway

  8. MC EMiNEM maps the interaction landscape of the Mediator

    OpenAIRE

    Niederberger, Theresa; Etzold, Stefanie; Lidschreiber, Michael; Maier, Kerstin C.; Martin, Dietmar E.; Fröhlich, Holger; Cramer, Patrick; Tresch, Achim

    2012-01-01

    The Mediator is a highly conserved, large multiprotein complex that is involved essentially in the regulation of eukaryotic mRNA transcription. It acts as a general transcription factor by integrating regulatory signals from gene-specific activators or repressors to the RNA Polymerase II. The internal network of interactions between Mediator subunits that conveys these signals is largely unknown. Here, we introduce MC EMiNEM, a novel method for the retrieval of functional dependencies between...

  9. SCF Ubiquitin Ligase F-box Protein Fbx15 Controls Nuclear Co-repressor Localization, Stress Response and Virulence of the Human Pathogen Aspergillus fumigatus.

    Directory of Open Access Journals (Sweden)

    Bastian Jöhnk

    2016-09-01

    Full Text Available F-box proteins share the F-box domain to connect substrates of E3 SCF ubiquitin RING ligases through the adaptor Skp1/A to Cul1/A scaffolds. F-box protein Fbx15 is part of the general stress response of the human pathogenic mold Aspergillus fumigatus. Oxidative stress induces a transient peak of fbx15 expression, resulting in 3x elevated Fbx15 protein levels. During non-stress conditions Fbx15 is phosphorylated and F-box mediated interaction with SkpA preferentially happens in smaller subpopulations in the cytoplasm. The F-box of Fbx15 is required for an appropriate oxidative stress response, which results in rapid dephosphorylation of Fbx15 and a shift of the cellular interaction with SkpA to the nucleus. Fbx15 binds SsnF/Ssn6 as part of the RcoA/Tup1-SsnF/Ssn6 co-repressor and is required for its correct nuclear localization. Dephosphorylated Fbx15 prevents SsnF/Ssn6 nuclear localization and results in the derepression of gliotoxin gene expression. fbx15 deletion mutants are unable to infect immunocompromised mice in a model for invasive aspergillosis. Fbx15 has a novel dual molecular function by controlling transcriptional repression and being part of SCF E3 ubiquitin ligases, which is essential for stress response, gliotoxin production and virulence in the opportunistic human pathogen A. fumigatus.

  10. A genetic link between epigenetic repressor AS1-AS2 and a putative small subunit processome in leaf polarity establishment of Arabidopsis

    Directory of Open Access Journals (Sweden)

    Yoko Matsumura

    2016-07-01

    Full Text Available Although the DEAD-box RNA helicase family is ubiquitous in eukaryotes, its developmental role remains unelucidated. Here, we report that cooperative action between the Arabidopsis nucleolar protein RH10, an ortholog of human DEAD-box RNA helicase DDX47, and the epigenetic repressor complex of ASYMMETRIC-LEAVES1 (AS1 and AS2 (AS1-AS2 is critical to repress abaxial (ventral genes ETT/ARF3 and ARF4, which leads to adaxial (dorsal development in leaf primordia at shoot apices. Double mutations of rh10-1 and as2 (or as1 synergistically up-regulated the abaxial genes, which generated abaxialized filamentous leaves with loss of the adaxial domain. DDX47 is part of the small subunit processome (SSUP that mediates rRNA biogenesis. In rh10-1 we found various defects in SSUP-related events, such as: accumulation of 35S/33S rRNA precursors; reduction in the 18S/25S ratio; and nucleolar hypertrophy. Double mutants of as2 with mutations of genes that encode other candidate SSUP-related components such as nucleolin and putative rRNA methyltransferase exhibited similar synergistic defects caused by up-regulation of ETT/ARF3 and ARF4. These results suggest a tight link between putative SSUP and AS1-AS2 in repression of the abaxial-determining genes for cell fate decisions for adaxial development.

  11. recA+-dependent inactivation of the lambda repressor in Escherichia coli lysogens by γ-radiation and by tif expression

    International Nuclear Information System (INIS)

    West, S.C.; Powell, K.A.; Emmerson, P.T.

    1975-01-01

    When lambda lysogens of E. coli are induced by γ-radiation the lambda repressor, as measured by its specific binding to lambda DNA, is rapidly inactivated by a recA + -dependent process which does not require new protein synthesis. This rapid inactivation is similar to inactivation of repressor by expression of the temperature sensitive E. coli mutation tif. In contrast, induction by UV irradiation or mitomycin C treatment requires new protein synthesis and there is a lag before the repressor is inactivated (Tomizawa and Ogawa, 1967; Shinagawa and Itoh, 1973). (orig.) [de

  12. Multi-domain CGFS-type glutaredoxin Grx4 regulates iron homeostasis via direct interaction with a repressor Fep1 in fission yeast

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyoung-Dong; Kim, Hyo-Jin; Lee, Kyung-Chang [Laboratory of Molecular Microbiology, School of Biological Sciences and Institute of Microbiology, Seoul National University, Seoul 151-742 (Korea, Republic of); Roe, Jung-Hye, E-mail: jhroe@snu.ac.kr [Laboratory of Molecular Microbiology, School of Biological Sciences and Institute of Microbiology, Seoul National University, Seoul 151-742 (Korea, Republic of)

    2011-05-20

    Research highlights: {yields} Monothiol glutaredoxin Grx4 allows Fep1-mediated de-repression of iron uptake genes at low iron. {yields} Grx4 directly interacts with Fep1 in vivo and in vitro. {yields} The Cys172 in the CGFS motif of Grx4 is necessary for cell proliferation and iron regulation. {yields} The Cys172 of Grx4 is required for normal interaction with Fep1. -- Abstract: The fission yeast Schizosaccharomyces pombe contains two CGFS-type monothiol glutaredoxins, Grx4 and Grx5, which are localized primarily in the nucleus and mitochondria, respectively. We observed involvement of Grx4 in regulating iron-responsive gene expression, which is modulated by a repressor Fep1. Lack of Grx4 caused defects not only in growth but also in the expression of both iron-uptake and iron-utilizing genes regardless of iron availability. In order to unravel how Grx4 is involved in Fep1-mediated regulation, interaction between them was investigated. Co-immunoprecipitation and bimolecular fluorescence complementation (BiFC) revealed that Grx4 physically interacts with Fep1 in vivo. BiFC revealed localized nuclear dots produced by interaction of Grx4 with Fep1. Mutation of cysteine-172 in the CGFS motif to serine (C172S) produced effects similarly observed under Grx4 depletion, such as the loss of iron-dependent gene regulation and the absence of nuclear dots in BiFC analysis. These results suggest that the ability of Grx4 to bind iron, most likely Fe-S cofactor, could be critical in interacting with and modulating the activity of Fep1.

  13. The global repressor FliZ antagonizes gene expression by σS-containing RNA polymerase due to overlapping DNA binding specificity.

    Science.gov (United States)

    Pesavento, Christina; Hengge, Regine

    2012-06-01

    FliZ, a global regulatory protein under the control of the flagellar master regulator FlhDC, was shown to antagonize σ(S)-dependent gene expression in Escherichia coli. Thereby it plays a pivotal role in the decision between alternative life-styles, i.e. FlhDC-controlled flagellum-based motility or σ(S)-dependent curli fimbriae-mediated adhesion and biofilm formation. Here, we show that FliZ is an abundant DNA-binding protein that inhibits gene expression mediated by σ(S) by recognizing operator sequences that resemble the -10 region of σ(S)-dependent promoters. FliZ does so with a structural element that is similar to region 3.0 of σ(S). Within this element, R108 in FliZ corresponds to K173 in σ(S), which contacts a conserved cytosine at the -13 promoter position that is specific for σ(S)-dependent promoters. R108 as well as C(-13) are also crucial for DNA binding by FliZ. However, while a number of FliZ binding sites correspond to known σ(S)-dependent promoters, promoter activity is not a prerequisite for FliZ binding and repressor function. Thus, we demonstrate that FliZ also feedback-controls flagellar gene expression by binding to a site in the flhDC control region that shows similarity only to a -10 element of a σ(S)-dependent promoter, but does not function as a promoter.

  14. Downregulation of the Repressor Element 1-Silencing Transcription Factor (REST Is Associated with Akt-mTOR and Wnt-β-Catenin Signaling in Prion Diseases Models

    Directory of Open Access Journals (Sweden)

    Zhiqi Song

    2017-05-01

    Full Text Available Prion diseases are a group of infectious diseases characterized by multiple neuropathological changes, yet the mechanisms that preserve function and protect against prion-associated neurodegeneration are still unclear. We previously reported that the repressor element 1-silencing transcription factor (REST alleviates neurotoxic prion peptide (PrP106-126-induced toxicity in primary neurons. Here we confirmed the findings of the in vitro model in 263K infected hamsters, an in vivo model of prion diseases and further showed the relationships between REST and related signaling pathways. REST was depleted from the nucleus in prion infected brains and taken up by autophagosomes in the cytoplasm, co-localizing with LC3-II. Importantly, downregulation of the Akt–mTOR and at least partially inactivation of LRP6-Wnt-β-catenin signaling pathways correlated with the decreased levels of REST in vivo in the brain of 263K-infected hamsters and in vitro in PrP106-126-treated primary neurons. Overexpression of REST in primary cortical neurons alleviated PrP106-126 peptide-induced neuronal oxidative stress, mitochondrial damage and partly inhibition of the LRP6-Wnt-β-catenin and Akt–mTOR signaling. Based on our findings, a model of REST-mediated neuroprotection in prion infected animals is proposed, with Akt–mTOR and Wnt-β-catenin signaling as the key pathways. REST-mediated neuronal survival signaling could be explored as a viable therapeutic target for prion diseases and related neurodegenerative diseases.

  15. P22 Arc repressor: enhanced expression of unstable mutants by addition of polar C-terminal sequences.

    OpenAIRE

    Milla, M. E.; Brown, B. M.; Sauer, R. T.

    1993-01-01

    Many mutant variants of the P22 Arc repressor are subject to intracellular proteolysis in Escherichia coli, which precludes their expression at levels sufficient for purification and subsequent biochemical characterization. Here we examine the effects of several different C-terminal extension sequences on the expression and activity of a set of Arc mutants. We show that two tail sequences, KNQHE (st5) and H6KNQHE (st11), increase the expression levels of most mutants from 10- to 20-fold and, ...

  16. Human Freud-2/CC2D1B: a novel repressor of postsynaptic serotonin-1A receptor expression.

    Science.gov (United States)

    Hadjighassem, Mahmoud R; Austin, Mark C; Szewczyk, Bernadeta; Daigle, Mireille; Stockmeier, Craig A; Albert, Paul R

    2009-08-01

    Altered expression of serotonin-1A (5-HT1A) receptors, both presynaptic in the raphe nuclei and post-synaptic in limbic and cortical target areas, has been implicated in mood disorders such as major depression and anxiety. Within the 5-HT1A receptor gene, a powerful dual repressor element (DRE) is regulated by two protein complexes: Freud-1/CC2D1A and a second, unknown repressor. Here we identify human Freud-2/CC2D1B, a Freud-1 homologue, as the second repressor. Freud-2 distribution was examined with Northern and Western blot, reverse transcriptase polymerase chain reaction, and immunohistochemistry/immunofluorescence; Freud-2 function was examined by electrophoretic mobility shift, reporter assay, and Western blot. Freud-2 RNA was widely distributed in brain and peripheral tissues. Freud-2 protein was enriched in the nuclear fraction of human prefrontal cortex and hippocampus but was weakly expressed in the dorsal raphe nucleus. Freud-2 immunostaining was co-localized with 5-HT1A receptors, neuronal and glial markers. In prefrontal cortex, Freud-2 was expressed at similar levels in control and depressed male subjects. Recombinant hFreud-2 protein bound specifically to 5' or 3' human DRE adjacent to the Freud-1 site. Human Freud-2 showed strong repressor activity at the human 5-HT1A or heterologous promoter in human HEK-293 5-HT1A-negative cells and neuronal SK-N-SH cells, a model of postsynaptic 5-HT1A receptor-positive cells. Furthermore, small interfering RNA knockdown of endogenous hFreud-2 expression de-repressed 5-HT1A promoter activity and increased levels of 5-HT1A receptor protein in SK-N-SH cells. Human Freud-2 binds to the 5-HT1A DRE and represses the human 5-HT1A receptor gene to regulate its expression in non-serotonergic cells and neurons.

  17. Drosophila melanogaster cellular repressor of E1A-stimulated genes is a lysosomal protein essential for fly development

    OpenAIRE

    Kowalewski-Nimmerfall, Elisabeth; Sch?hs, Philipp; Maresch, Daniel; Rendic, Dubravko; Kr?mer, Helmut; Mach, Lukas

    2014-01-01

    Mammalian cellular repressor of E1A-stimulated genes is a lysosomal glycoprotein implicated in cellular growth and differentiation. The genome of the fruit fly Drosophila melanogaster encodes a putative orthologue (dCREG), suggesting evolutionarily conserved physiological functions of this protein. In D. melanogaster S2 cells, dCREG was found to localize in lysosomes. Further studies revealed that intracellular dCREG is subject of proteolytic maturation. Processing and turnover could be subst...

  18. Zic-Proteins Are Repressors of Dopaminergic Forebrain Fate in Mice and C. elegans.

    Science.gov (United States)

    Tiveron, Marie-Catherine; Beclin, Christophe; Murgan, Sabrina; Wild, Stefan; Angelova, Alexandra; Marc, Julie; Coré, Nathalie; de Chevigny, Antoine; Herrera, Eloisa; Bosio, Andreas; Bertrand, Vincent; Cremer, Harold

    2017-11-01

    In the postnatal forebrain regionalized neural stem cells along the ventricular walls produce olfactory bulb (OB) interneurons with varying neurotransmitter phenotypes and positions. To understand the molecular basis of this region-specific variability we analyzed gene expression in the postnatal dorsal and lateral lineages in mice of both sexes from stem cells to neurons. We show that both lineages maintain transcription factor signatures of their embryonic site of origin, the pallium and subpallium. However, additional factors, including Zic1 and Zic2, are postnatally expressed in the dorsal stem cell compartment and maintained in the lineage that generates calretinin-positive GABAergic neurons for the OB. Functionally, we show that Zic1 and Zic2 induce the generation of calretinin-positive neurons while suppressing dopaminergic fate in the postnatal dorsal lineage. We investigated the evolutionary conservation of the dopaminergic repressor function of Zic proteins and show that it is already present in C. elegans SIGNIFICANCE STATEMENT The vertebrate brain generates thousands of different neuron types. In this work we investigate the molecular mechanisms underlying this variability. Using a genomics approach we identify the transcription factor signatures of defined neural stem cells and neuron populations. Based thereon we show that two related transcription factors, Zic1 and Zic2, are essential to control the balance between two defined neuron types in the postnatal brain. We show that this mechanism is conserved in evolutionary very distant species. Copyright © 2017 the authors 0270-6474/17/3710611-13$15.00/0.

  19. Activation of pur Gene Expression by a Homologue of the Bacillus subtilis PurR repressor:

    DEFF Research Database (Denmark)

    Kilstrup, Mogens; Martinussen, Jan

    1998-01-01

    R encoded repressor from Bacillus subtilis. The wildtype purR gene complements the purine auxotrophy of a purR::Iss1mutant, and it was shown that the purR::Iss1 mutation lowers transcription from the purine regulated L. lactis purD promoter. In a parallel study on the regulation of purC and purD expression....... We have identified a PurBox sequence overlapping the -35 region of the L. lactis purR promoter and found, by studies of a purR-lacLM fusion plasmid, that purR is autoregulated. Because of the high similarity of the PurR proteins from B. subtilis and L. lactis, we looked for PurBox sequences...... in the promoter regions of the PurR regulated genes in B. subtilis, and identified a perfectly matching PurBox in the purA promoter region, and slightly degenerate PurBox like sequences in the promoter regions for the pur operon and the purR gene....

  20. Loss of the RNA polymerase III repressor MAF1 confers obesity resistance.

    Science.gov (United States)

    Bonhoure, Nicolas; Byrnes, Ashlee; Moir, Robyn D; Hodroj, Wassim; Preitner, Frédéric; Praz, Viviane; Marcelin, Genevieve; Chua, Streamson C; Martinez-Lopez, Nuria; Singh, Rajat; Moullan, Norman; Auwerx, Johan; Willemin, Gilles; Shah, Hardik; Hartil, Kirsten; Vaitheesvaran, Bhavapriya; Kurland, Irwin; Hernandez, Nouria; Willis, Ian M

    2015-05-01

    MAF1 is a global repressor of RNA polymerase III transcription that regulates the expression of highly abundant noncoding RNAs in response to nutrient availability and cellular stress. Thus, MAF1 function is thought to be important for metabolic economy. Here we show that a whole-body knockout of Maf1 in mice confers resistance to diet-induced obesity and nonalcoholic fatty liver disease by reducing food intake and increasing metabolic inefficiency. Energy expenditure in Maf1(-/-) mice is increased by several mechanisms. Precursor tRNA synthesis was increased in multiple tissues without significant effects on mature tRNA levels, implying increased turnover in a futile tRNA cycle. Elevated futile cycling of hepatic lipids was also observed. Metabolite profiling of the liver and skeletal muscle revealed elevated levels of many amino acids and spermidine, which links the induction of autophagy in Maf1(-/-) mice with their extended life span. The increase in spermidine was accompanied by reduced levels of nicotinamide N-methyltransferase, which promotes polyamine synthesis, enables nicotinamide salvage to regenerate NAD(+), and is associated with obesity resistance. Consistent with this, NAD(+) levels were increased in muscle. The importance of MAF1 for metabolic economy reveals the potential for MAF1 modulators to protect against obesity and its harmful consequences. © 2015 Bonhoure et al.; Published by Cold Spring Harbor Laboratory Press.

  1. A GntR-type transcriptional repressor controls sialic acid utilization in Bifidobacterium breve UCC2003.

    Science.gov (United States)

    Egan, Muireann; O'Connell Motherway, Mary; van Sinderen, Douwe

    2015-02-01

    Bifidobacterium breve strains are numerically prevalent among the gut microbiota of healthy, breast-fed infants. The metabolism of sialic acid, a ubiquitous monosaccharide in the infant and adult gut, by B. breve UCC2003 is dependent on a large gene cluster, designated the nan/nag cluster. This study describes the transcriptional regulation of the nan/nag cluster and thus sialic acid metabolism in B. breve UCC2003. Insertion mutagenesis and transcriptome analysis revealed that the nan/nag cluster is regulated by a GntR family transcriptional repressor, designated NanR. Crude cell extract of Escherichia coli EC101 in which the nanR gene had been cloned and overexpressed was shown to bind to two promoter regions within this cluster, each of which containing an imperfect inverted repeat that is believed to act as the NanR operator sequence. Formation of the DNA-NanR complex is prevented in the presence of sialic acid, which we had previously shown to induce transcription of this gene cluster. © FEMS 2014. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  2. Recognition of AT-Rich DNA Binding Sites by the MogR Repressor

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Aimee; Higgins, Darren E.; Panne, Daniel; (Harvard-Med); (EMBL)

    2009-07-22

    The MogR transcriptional repressor of the intracellular pathogen Listeria monocytogenes recognizes AT-rich binding sites in promoters of flagellar genes to downregulate flagellar gene expression during infection. We describe here the 1.8 A resolution crystal structure of MogR bound to the recognition sequence 5' ATTTTTTAAAAAAAT 3' present within the flaA promoter region. Our structure shows that MogR binds as a dimer. Each half-site is recognized in the major groove by a helix-turn-helix motif and in the minor groove by a loop from the symmetry-related molecule, resulting in a 'crossover' binding mode. This oversampling through minor groove interactions is important for specificity. The MogR binding site has structural features of A-tract DNA and is bent by approximately 52 degrees away from the dimer. The structure explains how MogR achieves binding specificity in the AT-rich genome of L. monocytogenes and explains the evolutionary conservation of A-tract sequence elements within promoter regions of MogR-regulated flagellar genes.

  3. Crystal Structure and Regulation of the Citrus Pol III Repressor MAF1 by Auxin and Phosphorylation.

    Science.gov (United States)

    Soprano, Adriana Santos; Giuseppe, Priscila Oliveira de; Shimo, Hugo Massayoshi; Lima, Tatiani Brenelli; Batista, Fernanda Aparecida Heleno; Righetto, Germanna Lima; Pereira, José Geraldo de Carvalho; Granato, Daniela Campos; Nascimento, Andrey Fabricio Ziem; Gozzo, Fabio Cesar; de Oliveira, Paulo Sérgio Lopes; Figueira, Ana Carolina Migliorini; Smetana, Juliana Helena Costa; Paes Leme, Adriana Franco; Murakami, Mario Tyago; Benedetti, Celso Eduardo

    2017-09-05

    MAF1 is the main RNA polymerase (Pol) III repressor that controls cell growth in eukaryotes. The Citrus ortholog, CsMAF1, was shown to restrict cell growth in citrus canker disease but its role in plant development and disease is still unclear. We solved the crystal structure of the globular core of CsMAF1, which reveals additional structural elements compared with the previously available structure of hMAF1, and explored the dynamics of its flexible regions not present in the structure. CsMAF1 accumulated in the nucleolus upon leaf excision, and this translocation was inhibited by auxin and by mutation of the PKA phosphorylation site, S45, to aspartate. Additionally, mTOR phosphorylated recombinant CsMAF1 and the mTOR inhibitor AZD8055 blocked canker formation in normal but not CsMAF1-silenced plants. These results indicate that the role of TOR on cell growth induced by Xanthomonas citri depends on CsMAF1 and that auxin controls CsMAF1 interaction with Pol III in citrus. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Genetic separation of Escherichia coli recA functions for SOS mutagenesis and repressor cleavage

    International Nuclear Information System (INIS)

    Ennis, D.G.; Ossanna, N.; Mount, D.W.

    1989-01-01

    Evidence is presented that recA functions which promote the SOS functions of mutagenesis, LexA protein proteolysis, and lambda cI repressor proteolysis are each genetically separable from the others. This separation was observed in recombination-proficient recA mutants and rec+ (F' recA56) heterodiploids. recA430, recA433, and recA435 mutants and recA+ (F' recA56) heterodiploids were inducible for only one or two of the three functions and defective for mutagenesis. recA80 and recA432 mutants were constitutively activated for two of the three functions in that these mutants did not have to be induced to express the functions. We propose that binding of RecA protein to damaged DNA and subsequent interaction with small inducer molecules gives rise to conformational changes in RecA protein. These changes promote surface-surface interactions with other target proteins, such as cI and LexA proteins. By this model, the recA mutants are likely to have incorrect amino acids substituted as sites in the RecA protein structure which affect surface regions required for protein-protein interactions. The constitutively activated mutants could likewise insert altered amino acids at sites in RecA which are involved in the activation of RecA protein by binding small molecules or polynucleotides which metabolically regulate RecA protein

  5. The Mycobacterium tuberculosis transcriptional repressor EthR is negatively regulated by Serine/Threonine phosphorylation.

    Science.gov (United States)

    Leiba, Jade; Carrère-Kremer, Séverine; Blondiaux, Nicolas; Dimala, Martin Moune; Wohlkönig, Alexandre; Baulard, Alain; Kremer, Laurent; Molle, Virginie

    2014-04-18

    Recent efforts have underlined the role of Serine/Threonine Protein Kinases (STPKs) in growth, pathogenesis and cell wall metabolism in mycobacteria. Herein, we demonstrated that the Mycobacterium tuberculosis EthR, a transcriptional repressor that regulates the activation process of the antitubercular drug ethionamide (ETH) is a specific substrate of the mycobacterial kinase PknF. ETH is a prodrug that must undergo bioactivation by the monooxygenease EthA to exert its antimycobacterial activity and previous studies reported that EthR represses transcription of ethA by binding to the ethA-ethR intergenic region. Mass spectrometry analyses and site-directed mutagenesis identified a set of four phosphoacceptors, namely Thr2, Thr3, Ser4 and Ser7. This was further supported by the complete loss of PknF-dependent phosphorylation of a phosphoablative EthR mutant protein. Importantly, a phosphomimetic version of EthR, in which all phosphosites were replaced by Asp residues, exhibited markedly decreased DNA-binding activity compared with the wild-type protein. Together, these findings are the first demonstration of EthR phosphorylation and indicate that phosphorylation negatively affects its DNA-binding activity, which may impact ETH resistance levels in M. tb. Copyright © 2014 Elsevier Inc. All rights reserved.

  6. Investigation of arc repressor DNA-binding specificity by comparative molecular dynamics simulations.

    Science.gov (United States)

    Song, Wei; Guo, Jun-Tao

    2015-01-01

    Transcription factors regulate gene expression through binding to specific DNA sequences. How transcription factors achieve high binding specificity is still not well understood. In this paper, we investigated the role of protein flexibility in protein-DNA-binding specificity by comparative molecular dynamics (MD) simulations. Protein flexibility has been considered as a key factor in molecular recognition, which is intrinsically a dynamic process involving fine structural fitting between binding components. In this study, we performed comparative MD simulations on wild-type and F10V mutant P22 Arc repressor in both free and complex conformations. The F10V mutant has lower DNA-binding specificity though both the bound and unbound main-chain structures between the wild-type and F10V mutant Arc are highly similar. We found that the DNA-binding motif of wild-type Arc is structurally more flexible than the F10V mutant in the unbound state, especially for the six DNA base-contacting residues in each dimer. We demonstrated that the flexible side chains of wild-type Arc lead to a higher DNA-binding specificity through forming more hydrogen bonds with DNA bases upon binding. Our simulations also showed a possible conformational selection mechanism for Arc-DNA binding. These results indicate the important roles of protein flexibility and dynamic properties in protein-DNA-binding specificity.

  7. NMR assignments for the amino-terminal residues of trp repressor and their role in DNA binding

    International Nuclear Information System (INIS)

    Arrowsmith, C.H.; Carey, J.; Treat-Clemons, L.; Jardetzky, O.

    1989-01-01

    The trp repressor of Escherichia coli specifically binds to operator DNAs in three operons involved in tryptophan metabolism. The NMR spectra of repressor and a chymotryptic fragment lacking the six amino-terminal residues are compared. Two-dimensional J-correlated spectra of the two forms of the protein are superimposable except for cross-peaks that are associated with the N-terminal region. The chemical shifts and relaxation behavior of the N-terminal resonances suggest mobile arms. Spin-echo experiments on a ternary complex of repressor with L-tryptophan and operator DNA indicate that the termini are also disordered in the complex, although removal of the arms reduces the DNA binding energy. Relaxation measurements on the armless protein show increased mobility for several residues, probably due to helix fraying in the newly exposed N-terminal region. DNA binding by the armless protein does not reduce the mobility of these residues. Thus, it appears that the arms serve to stabilize the N-terminal helix but that this structural role does not explain their contribution to the DNA binding energy. These results suggest that the promiscuous DNA binding by the arms seen in the X-ray crystal structure is found in solution as well

  8. JAZ repressors: Possible Involvement in Nutrients Deficiency Response in Rice and Chickpea

    Directory of Open Access Journals (Sweden)

    Ajit P. Singh

    2015-11-01

    Full Text Available Jasmonates (JA are well-known phytohormones which play important roles in plant development and defence against pathogens. Jasmonate ZIM domain (JAZ proteins are plant-specific proteins and act as transcriptional repressors of JA-responsive genes. JA regulates both biotic and abiotic stress responses in plants; however, its role in nutrient deficiency responses is very elusive. Although, JA is well-known for root growth inhibition, little is known about behaviour of JAZ genes in response to nutrient deficiencies, under which root architectural alteration is an important adaptation. Using protein sequence homology and a conserved-domains approach, here we identify ten novel JAZ genes from the recently sequenced Chickpea genome, which is one of the most nutrient efficient crops. Both rice and chickpea JAZ genes express in tissue- and stimuli-specific manners. Many of which are preferentially expressed in root. Our analysis further showed differential expression of JAZ genes under macro (NPK and micronutrients (Zn, Fe deficiency in rice and chickpea roots. While both rice and chickpea JAZ genes showed a certain level of specificity towards type of nutrient deficiency, generally majority of them showed induction under K deficiency. Generally, JAZ genes showed an induction at early stages of stress and expression declined at later stages of macro-nutrient deficiency. Our results suggest that JAZ genes might play a role in early nutrient deficiency response both in monocot and dicot roots, and information generated here can be further used for understanding the possible roles of JA in root architectural alterations for nutrient deficiency adaptations

  9. NF-Y recruits both transcription activator and repressor to modulate tissue- and developmental stage-specific expression of human γ-globin gene.

    Directory of Open Access Journals (Sweden)

    Xingguo Zhu

    Full Text Available The human embryonic, fetal and adult β-like globin genes provide a paradigm for tissue- and developmental stage-specific gene regulation. The fetal γ-globin gene is expressed in fetal erythroid cells but is repressed in adult erythroid cells. The molecular mechanism underlying this transcriptional switch during erythroid development is not completely understood. Here, we used a combination of in vitro and in vivo assays to dissect the molecular assemblies of the active and the repressed proximal γ-globin promoter complexes in K562 human erythroleukemia cell line and primary human fetal and adult erythroid cells. We found that the proximal γ-globin promoter complex is assembled by a developmentally regulated, general transcription activator NF-Y bound strongly at the tandem CCAAT motifs near the TATA box. NF-Y recruits to neighboring DNA motifs the developmentally regulated, erythroid transcription activator GATA-2 and general repressor BCL11A, which in turn recruit erythroid repressor GATA-1 and general repressor COUP-TFII to form respectively the NF-Y/GATA-2 transcription activator hub and the BCL11A/COUP-TFII/GATA-1 transcription repressor hub. Both the activator and the repressor hubs are present in both the active and the repressed γ-globin promoter complexes in fetal and adult erythroid cells. Through changes in their levels and respective interactions with the co-activators and co-repressors during erythroid development, the activator and the repressor hubs modulate erythroid- and developmental stage-specific transcription of γ-globin gene.

  10. MicroRNA-31 controls phenotypic modulation of human vascular smooth muscle cells by regulating its target gene cellular repressor of E1A-stimulated genes

    International Nuclear Information System (INIS)

    Wang, Jie; Yan, Cheng-Hui; Li, Yang; Xu, Kai; Tian, Xiao-Xiang; Peng, Cheng-Fei; Tao, Jie; Sun, Ming-Yu; Han, Ya-Ling

    2013-01-01

    Phenotypic modulation of vascular smooth muscle cells (VSMCs) plays a critical role in the pathogenesis of a variety of proliferative vascular diseases. The cellular repressor of E1A-stimulated genes (CREG) has been shown to play an important role in phenotypic modulation of VSMCs. However, the mechanism regulating CREG upstream signaling remains unclear. MicroRNAs (miRNAs) have recently been found to play a critical role in cell differentiation via target-gene regulation. This study aimed to identify a miRNA that binds directly to CREG, and may thus be involved in CREG-mediated VSMC phenotypic modulation. Computational analysis indicated that miR-31 bound to the CREG mRNA 3′ untranslated region (3′-UTR). miR-31 was upregulated in quiescent differentiated VSMCs and downregulated in proliferative cells stimulated by platelet-derived growth factor and serum starvation, demonstrating a negative relationship with the VSMC differentiation marker genes, smooth muscle α-actin, calponin and CREG. Using gain-of-function and loss-of-function approaches, CREG and VSMC differentiation marker gene expression levels were shown to be suppressed by a miR-31 mimic, but increased by a miR-31 inhibitor at both protein and mRNA levels. Notably, miR-31 overexpression or inhibition affected luciferase expression driven by the CREG 3′-UTR containing the miR-31 binding site. Furthermore, miR-31-mediated VSMC phenotypic modulation was inhibited in CREG-knockdown human VSMCs. We also determined miR-31 levels in the serum of patients with coronary artery disease (CAD), with or without in stent restenosis and in healthy controls. miR-31 levels were higher in the serum of CAD patients with restenosis compared to CAD patients without restenosis and in healthy controls. In summary, these data demonstrate that miR-31 not only directly binds to its target gene CREG and modulates the VSMC phenotype through this interaction, but also can be an important biomarker in diseases involving VSMC

  11. Complex Binding of the FabR Repressor of Bacterial Unsaturated Fatty Acid Biosynthesis to its Cognate Promoters

    OpenAIRE

    Feng, Youjun; Cronan, John E.

    2011-01-01

    Two transcriptional regulators, the FadR activator and the FabR repressor control biosynthesis of unsaturated fatty acids in Escherichia coli. FabR represses expression of the two genes, fabA and fabB, required for unsaturated fatty acid synthesis and has been reported to require the presence of an unsaturated thioester (of either acyl carrier protein or CoA) in order to bind the fabA and fabB promoters in vitro. We report in vivo experiments in which unsaturated fatty acid synthesis was bloc...

  12. An Autocrine Proliferation Repressor Regulates Dictyostelium discoideum Proliferation and Chemorepulsion Using the G Protein-Coupled Receptor GrlH

    OpenAIRE

    Yu Tang; Yuantai Wu; Sarah E. Herlihy; Francisco J. Brito-Aleman; Jose H. Ting; Chris Janetopoulos; Richard H. Gomer; Scott D. Emr

    2018-01-01

    In eukaryotic microbes, little is known about signals that inhibit the proliferation of the cells that secrete the signal, and little is known about signals (chemorepellents) that cause cells to move away from the source of the signal. Autocrine proliferation repressor protein A (AprA) is a protein secreted by the eukaryotic microbe Dictyostelium discoideum. AprA is a chemorepellent for and inhibits the proliferation of D. discoideum. We previously found that cells sense AprA using G proteins...

  13. Small Ubiquitin-like Modifier (SUMO) Conjugation Impedes Transcriptional Silencing by the Polycomb Group Repressor Sex Comb on Midleg*

    OpenAIRE

    Smith, Matthew; Mallin, Daniel R.; Simon, Jeffrey A.; Courey, Albert J.

    2011-01-01

    The Drosophila protein Sex Comb on Midleg (Scm) is a member of the Polycomb group (PcG), a set of transcriptional repressors that maintain silencing of homeotic genes during development. Recent findings have identified PcG proteins both as targets for modification by the small ubiquitin-like modifier (SUMO) protein and as catalytic components of the SUMO conjugation pathway. We have found that the SUMO-conjugating enzyme Ubc9 binds to Scm and that this interaction, which requires the Scm C-te...

  14. Conservation of the LexA repressor binding site in Deinococcus radiodurans

    Directory of Open Access Journals (Sweden)

    Khan Feroz

    2008-03-01

    Full Text Available The LexA protein is a transcriptional repressor of the bacterial SOS DNA repair system, which comprises a set of DNA repair and cellular survival genes that are induced in response to DNA damage. Its varied DNA binding motifs have been characterized and reported in the Escherichia coli, Bacillus subtilis, rhizobia family members, marine magnetotactic bacterium, Salmonella typhimurium and recently in Mycobacterium tuberculosis and this motifs information has been used in our theoretical analysis to detect its novel regulated genes in radio-resistant Deinococcus radiodurans genome. This bacterium showed presence of SOS-box like consensus sequence in the upstream sequences of 3166 genes with >60% motif score similarity percentage (MSSP on both strands. Attempts to identify LexA-binding sites and the composition of the putative SOS regulon in D. radiodurans have been unsuccessful so far. To resolve the problem we performed theoretical analysis with modifications on reported data set of genes related to DNA repair (61 genes, stress response (145 genes and some unusual predicted operons (21 clusters. Expression of some of the predicted SOS-box regulated operon members then was examined through the previously reported microarray data which confirm the expression of only single predicted operon i.e. DRB0143 (AAA superfamily NTPase related to 5-methylcytosine specific restriction enzyme subunit McrB and DRB0144 (homolog of the McrC subunit of the McrBC restriction modification system. The methodology involved weight matrix construction through CONSENSUS algorithm using information of conserved upstream sequences of eight known genes including dinB, tagC, lexA, recA, uvrB, yneA of B. subtilis while lexA and recA of D. radiodurans through phylogenetic footprinting method and later detection of similar conserved SOS-box like LexA binding motifs through both RSAT & PoSSuMsearch programs. The resultant DNA consensus sequence had highly conserved 14 bp SOS

  15. KPNB1 mediates PER/CRY nuclear translocation and circadian clock function.

    Science.gov (United States)

    Lee, Yool; Jang, A Reum; Francey, Lauren J; Sehgal, Amita; Hogenesch, John B

    2015-08-29

    Regulated nuclear translocation of the PER/CRY repressor complex is critical for negative feedback regulation of the circadian clock of mammals. However, the precise molecular mechanism is not fully understood. Here, we report that KPNB1, an importin β component of the ncRNA repressor of nuclear factor of activated T cells (NRON) ribonucleoprotein complex, mediates nuclear translocation and repressor function of the PER/CRY complex. RNAi depletion of KPNB1 traps the PER/CRY complex in the cytoplasm by blocking nuclear entry of PER proteins in human cells. KPNB1 interacts mainly with PER proteins and directs PER/CRY nuclear transport in a circadian fashion. Interestingly, KPNB1 regulates the PER/CRY nuclear entry and repressor function, independently of importin α, its classical partner. Moreover, inducible inhibition of the conserved Drosophila importin β in lateral neurons abolishes behavioral rhythms in flies. Collectively, these data show that KPNB1 is required for timely nuclear import of PER/CRY in the negative feedback regulation of the circadian clock.

  16. Transcriptional repressor role of PocR on the 1,3-propanediol biosynthetic pathway by Lactobacillus panis PM1.

    Science.gov (United States)

    Kang, Tae Sun; Korber, Darren R; Tanaka, Takuji

    2014-06-01

    The regulatory role of a transcriptional regulator (PocR) in the 1,3-propanediol biosynthetic pathway of Lactobacillus panis PM1 contributes to the optimization of 1,3-propanediol production by this strain, which potentially will lead to 1,3-propanediol manufacturing efficiencies. Lactobacillus panis PM1 can utilize a 1,3-propanediol (1,3-PDO) biosynthetic pathway, consisting of diol dehydratase (PduCDE) and 1,3-PDO dehydrogenase, as a NADH recycling system, to survive under various environmental conditions. In this study, we identified a key transcriptional repressor (PocR) which was annotated as a transcriptional factor of AraC family as part of the 1,3-PDO biosynthetic pathway of L. panis PM1. The over-expression of the PocR gene resulted in the significant repression (81 %) of pduC (PduCDE large subunit) transcription, and subsequently, the decreased activity of PduCDE by 22 %. As a result of the regulation of PduCDE, production of both 3-hydroxypropionaldehyde and 1,3-PDO in the PocR over-expressing strain were significantly decreased by 40 % relative to the control strain. These results clearly demonstrate the transcriptional repressor role of PocR in the 1,3-PDO biosynthetic pathway.

  17. Structural and dynamics studies of a truncated variant of CI repressor from bacteriophage TP901-1

    DEFF Research Database (Denmark)

    Rasmussen, Kim Krighaar; Frandsen, Kristian E. H.; Erba, Elisabetta Boeri

    2016-01-01

    The CI repressor from the temperate bacteriophage TP901-1 consists of two folded domains, an N-terminal helix-turn-helix DNA-binding domain (NTD) and a C-terminal oligomerization domain (CTD), which we here suggest to be further divided into CTD1 and CTD2. Full-length CI is a hexameric protein......, whereas a truncated version, CIΔ58, forms dimers. We identify the dimerization region of CIΔ58 as CTD1 and determine its secondary structure to be helical both within the context of CIΔ58 and in isolation. To our knowledge this is the first time that a helical dimerization domain has been found in a phage...... repressor. We also precisely determine the length of the flexible linker connecting the NTD to the CTD. Using electrophoretic mobility shift assays and native mass spectrometry, we show that CIΔ58 interacts with the O-L operator site as one dimer bound to both half-sites, and with much higher affinity than...

  18. Structure of the effector-binding domain of the arabinose repressor AraR from Bacillus subtilis

    Energy Technology Data Exchange (ETDEWEB)

    Procházková, Kateřina; Čermáková, Kateřina [Academy of Sciences of the Czech Republic, Flemingovo nam. 2, Prague 6 (Czech Republic); Pachl, Petr; Sieglová, Irena [Academy of Sciences of the Czech Republic, Flemingovo nam. 2, Prague 6 (Czech Republic); Academy of Sciences of the Czech Republic, Videnska 1083, Prague 4 (Czech Republic); Fábry, Milan [Academy of Sciences of the Czech Republic, Videnska 1083, Prague 4 (Czech Republic); Otwinowski, Zbyszek [UT Southwestern Medical Center, Dallas, Texas (United States); Řezáčová, Pavlína, E-mail: rezacova@uochb.cas.cz [Academy of Sciences of the Czech Republic, Flemingovo nam. 2, Prague 6 (Czech Republic); Academy of Sciences of the Czech Republic, Videnska 1083, Prague 4 (Czech Republic)

    2012-02-01

    The crystal structure of the effector-binding domain of the transcriptional repressor AraR from B. subtilis in complex with the effector molecule (l-arabinose) was determined at 2.2 Å resolution. A detailed analysis of the crystal identified a dimer organization that is distinctive from that of other members of the GalR/LacI family. In Bacillus subtilis, the arabinose repressor AraR negatively controls the expression of genes in the metabolic pathway of arabinose-containing polysaccharides. The protein is composed of two domains of different phylogenetic origin and function: an N-terminal DNA-binding domain belonging to the GntR family and a C-terminal effector-binding domain that shows similarity to members of the GalR/LacI family. The crystal structure of the C-terminal effector-binding domain of AraR in complex with the effector l-arabinose has been determined at 2.2 Å resolution. The l-arabinose binding affinity was characterized by isothermal titration calorimetry and differential scanning fluorimetry; the K{sub d} value was 8.4 ± 0.4 µM. The effect of l-arabinose on the protein oligomeric state was investigated in solution and detailed analysis of the crystal identified a dimer organization which is distinctive from that of other members of the GalR/LacI family.

  19. Transcriptional repressor domain of MBD1 is intrinsically disordered and interacts with its binding partners in a selective manner.

    KAUST Repository

    Hameed, Umar Farook Shahul

    2014-05-09

    Methylation of DNA CpG sites is a major mechanism of epigenetic gene silencing and plays important roles in cell division, development and carcinogenesis. One of its regulators is the 64-residue C-terminal Transcriptional Repressor Domain (the TRD) of MBD1, which recruits several repressor proteins such as MCAF1, HDAC3 and MPG that are essential for the gene silencing. Using NMR spectroscopy, we have characterized the solution structure of the C-terminus of MBD1 (MBD1-c, residues D507 to Q605), which included the TRD (A529 to P592). Surprisingly, the MBD1-c is intrinsically disordered. Despite its lack of a tertiary folding, MBD1-c could still bind to different partner proteins in a selective manner. MPG and MCAF1Δ8 showed binding to both the N-terminal and C-terminal residues of MBD1-c but HDAC3 preferably bound to the C-terminal region. This study reveals how MBD1-c discriminates different binding partners, and thus, expands our understanding of the mechanisms of gene regulation by MBD1.

  20. The CsoR-like sulfurtransferase repressor (CstR) is a persulfide sensor in Staphylococcus aureus.

    Science.gov (United States)

    Luebke, Justin L; Shen, Jiangchuan; Bruce, Kevin E; Kehl-Fie, Thomas E; Peng, Hui; Skaar, Eric P; Giedroc, David P

    2014-12-01

    How cells regulate the bioavailability of utilizable sulfur while mitigating the effects of hydrogen sulfide toxicity is poorly understood. CstR [Copper-sensing operon repressor (CsoR)-like sulfurtransferase repressor] represses the expression of the cst operon encoding a putative sulfide oxidation system in Staphylococcus aureus. Here, we show that the cst operon is strongly and transiently induced by cellular sulfide stress in an acute phase and specific response and that cst-encoded genes are necessary to mitigate the effects of sulfide toxicity. Growth defects are most pronounced when S. aureus is cultured in chemically defined media with thiosulfate (TS) as a sole sulfur source, but are also apparent when cystine is used or in rich media. Under TS growth conditions, cells fail to grow as a result of either unregulated expression of the cst operon in a ΔcstR strain or transformation with a non-inducible C31A/C60A CstR that blocks cst induction. This suggests that the cst operon contributes to cellular sulfide homeostasis. Tandem high-resolution mass spectrometry reveals derivatization of CstR by both inorganic tetrasulfide and an organic persulfide, glutathione persulfide, to yield a mixture of Cys31-Cys60' interprotomer cross-links, including di-, tri- and tetrasulfide bonds, which allosterically inhibit cst operator DNA binding by CstR. © 2014 John Wiley & Sons Ltd.

  1. Silencing the Transcriptional Repressor, ZCT1, Illustrates the Tight Regulation of Terpenoid Indole Alkaloid Biosynthesis in Catharanthus roseus Hairy Roots.

    Directory of Open Access Journals (Sweden)

    Noreen F Rizvi

    Full Text Available The Catharanthus roseus plant is the source of many valuable terpenoid indole alkaloids (TIAs, including the anticancer compounds vinblastine and vincristine. Transcription factors (TFs are promising metabolic engineering targets due to their ability to regulate multiple biosynthetic pathway genes. To increase TIA biosynthesis, we elicited the TIA transcriptional activators (ORCAs and other unidentified TFs with the plant hormone, methyl jasmonate (MJ, while simultaneously silencing the expression of the transcriptional repressor ZCT1. To silence ZCT1, we developed transgenic hairy root cultures of C. roseus that expressed an estrogen-inducible Zct1 hairpin for activating RNA interference. The presence of 17β-estradiol (5μM effectively depleted Zct1 in hairy root cultures elicited with MJ dosages that either optimize or inhibit TIA production (250 or 1000μM. However, silencing Zct1 was not sufficient to increase TIA production or the expression of the TIA biosynthetic genes (G10h, Tdc, and Str, illustrating the tight regulation of TIA biosynthesis. The repression of the TIA biosynthetic genes at the inhibitory MJ dosage does not appear to be solely regulated by ZCT1. For instance, while Zct1 and Zct2 levels decreased through activating the Zct1 hairpin, Zct3 levels remained elevated. Since ZCT repressors have redundant yet distinct functions, silencing all three ZCTs may be necessary to relieve their repression of alkaloid biosynthesis.

  2. A chimeric repressor of petunia PH4 R2R3-MYB family transcription factor generates margined flowers in torenia.

    Science.gov (United States)

    Kasajima, Ichiro; Sasaki, Katsutomo

    2016-05-03

    The development of new phenotypes is key to the commercial development of the main floricultural species and cultivars. Important new phenotypes include features such as multiple-flowers, color variations, increased flower size, new petal shapes, variegation and distinctive petal margin colourations. Although their commercial use is not yet common, the transgenic technologies provide a potentially rapid means of generating interesting new phenotypes. In this report, we construct 5 vectors which we expected to change the color of the flower anthocyanins, from purple to blue, regulating vacuolar pH. When these constructs were transformed into purple torenia, we unexpectedly recovered some genotypes having slightly margined petals. These transgenic lines expressed a chimeric repressor of the petunia PhPH4 gene under the control of Cauliflower mosaic virus 35 S RNA promoter. PhPH4 is an R2R3-type MYB transcription factor. The transgenic lines lacked pigmentation in the petal margin cells both on the adaxial and abaxial surfaces. Expressions of Flavanone 3-hydroxylase (F3H), Flavonoid 3'-hydroxylase (F3'H) and Flavonoid 3'5'-hydroxylase (F3'5'H) genes were reduced in the margins of these transgenic lines, suggesting an inhibitory effect of PhPH4 repressor on anthocyanin synthesis.

  3. Transcriptional repressor domain of MBD1 is intrinsically disordered and interacts with its binding partners in a selective manner.

    KAUST Repository

    Hameed, Umar Farook Shahul; Lim, Jackwee; Zhang, Qian; Wasik, Mariusz A; Yang, Daiwen; Swaminathan, Kunchithapadam

    2014-01-01

    Methylation of DNA CpG sites is a major mechanism of epigenetic gene silencing and plays important roles in cell division, development and carcinogenesis. One of its regulators is the 64-residue C-terminal Transcriptional Repressor Domain (the TRD) of MBD1, which recruits several repressor proteins such as MCAF1, HDAC3 and MPG that are essential for the gene silencing. Using NMR spectroscopy, we have characterized the solution structure of the C-terminus of MBD1 (MBD1-c, residues D507 to Q605), which included the TRD (A529 to P592). Surprisingly, the MBD1-c is intrinsically disordered. Despite its lack of a tertiary folding, MBD1-c could still bind to different partner proteins in a selective manner. MPG and MCAF1Δ8 showed binding to both the N-terminal and C-terminal residues of MBD1-c but HDAC3 preferably bound to the C-terminal region. This study reveals how MBD1-c discriminates different binding partners, and thus, expands our understanding of the mechanisms of gene regulation by MBD1.

  4. Loss of the Caenorhabditis elegans pocket protein LIN-35 reveals MuvB's innate function as the repressor of DREAM target genes.

    Directory of Open Access Journals (Sweden)

    Paul D Goetsch

    2017-11-01

    Full Text Available The DREAM (Dp/Retinoblastoma(Rb-like/E2F/MuvB transcriptional repressor complex acts as a gatekeeper of the mammalian cell cycle by establishing and maintaining cellular quiescence. How DREAM's three functional components, the E2F-DP heterodimer, the Rb-like pocket protein, and the MuvB subcomplex, form and function at target gene promoters remains unknown. The current model invokes that the pocket protein links E2F-DP and MuvB and is essential for gene repression. We tested this model by assessing how the conserved yet less redundant DREAM system in Caenorhabditis elegans is affected by absence of the sole C. elegans pocket protein LIN-35. Using a LIN-35 protein null mutant, we analyzed the assembly of E2F-DP and MuvB at promoters that are bound by DREAM and the level of expression of those "DREAM target genes" in embryos. We report that LIN-35 indeed mediates the association of E2F-DP and MuvB, a function that stabilizes DREAM subunit occupancy at target genes. In the absence of LIN-35, the occupancy of E2F-DP and MuvB at most DREAM target genes decreases dramatically and many of those genes become upregulated. The retention of E2F-DP and MuvB at some target gene promoters in lin-35 null embryos allowed us to test their contribution to DREAM target gene repression. Depletion of MuvB, but not E2F-DP, in the sensitized lin-35 null background caused further upregulation of DREAM target genes. We conclude that the pocket protein functions primarily to support MuvB-mediated repression of DREAM targets and that transcriptional repression is the innate function of the evolutionarily conserved MuvB complex. Our findings provide important insights into how mammalian DREAM assembly and disassembly may regulate gene expression and the cell cycle.

  5. Strategies to regulate transcription factor-mediated gene positioning and interchromosomal clustering at the nuclear periphery.

    Science.gov (United States)

    Randise-Hinchliff, Carlo; Coukos, Robert; Sood, Varun; Sumner, Michael Chas; Zdraljevic, Stefan; Meldi Sholl, Lauren; Garvey Brickner, Donna; Ahmed, Sara; Watchmaker, Lauren; Brickner, Jason H

    2016-03-14

    In budding yeast, targeting of active genes to the nuclear pore complex (NPC) and interchromosomal clustering is mediated by transcription factor (TF) binding sites in the gene promoters. For example, the binding sites for the TFs Put3, Ste12, and Gcn4 are necessary and sufficient to promote positioning at the nuclear periphery and interchromosomal clustering. However, in all three cases, gene positioning and interchromosomal clustering are regulated. Under uninducing conditions, local recruitment of the Rpd3(L) histone deacetylase by transcriptional repressors blocks Put3 DNA binding. This is a general function of yeast repressors: 16 of 21 repressors blocked Put3-mediated subnuclear positioning; 11 of these required Rpd3. In contrast, Ste12-mediated gene positioning is regulated independently of DNA binding by mitogen-activated protein kinase phosphorylation of the Dig2 inhibitor, and Gcn4-dependent targeting is up-regulated by increasing Gcn4 protein levels. These different regulatory strategies provide either qualitative switch-like control or quantitative control of gene positioning over different time scales. © 2016 Randise-Hinchliff et al.

  6. Auxin-dependent compositional change in Mediator in ARF7- and ARF19-mediated transcription.

    Science.gov (United States)

    Ito, Jun; Fukaki, Hidehiro; Onoda, Makoto; Li, Lin; Li, Chuanyou; Tasaka, Masao; Furutani, Masahiko

    2016-06-07

    Mediator is a multiprotein complex that integrates the signals from transcription factors binding to the promoter and transmits them to achieve gene transcription. The subunits of Mediator complex reside in four modules: the head, middle, tail, and dissociable CDK8 kinase module (CKM). The head, middle, and tail modules form the core Mediator complex, and the association of CKM can modify the function of Mediator in transcription. Here, we show genetic and biochemical evidence that CKM-associated Mediator transmits auxin-dependent transcriptional repression in lateral root (LR) formation. The AUXIN/INDOLE 3-ACETIC ACID 14 (Aux/IAA14) transcriptional repressor inhibits the transcriptional activity of its binding partners AUXIN RESPONSE FACTOR 7 (ARF7) and ARF19 by making a complex with the CKM-associated Mediator. In addition, TOPLESS (TPL), a transcriptional corepressor, forms a bridge between IAA14 and the CKM component MED13 through the physical interaction. ChIP assays show that auxin induces the dissociation of MED13 but not the tail module component MED25 from the ARF7 binding region upstream of its target gene. These findings indicate that auxin-induced degradation of IAA14 changes the module composition of Mediator interacting with ARF7 and ARF19 in the upstream region of their target genes involved in LR formation. We suggest that this regulation leads to a quick switch of signal transmission from ARFs to target gene expression in response to auxin.

  7. Haploinsufficiency of MeCP2-interacting transcriptional co-repressor SIN3A causes mild intellectual disability by affecting the development of cortical integrity

    NARCIS (Netherlands)

    Witteveen, Josefine S.; Willemsen, Marjolein H.; Dombroski, Thais C. D.; van Bakel, Nick H. M.; Nillesen, Willy M.; van Hulten, Josephus A.; Jansen, Eric J. R.; Verkaik, Dave; Veenstra-Knol, Hermine E.; van Ravenswaaij-Arts, Conny M. A.; Wassink-Ruiter, Jolien S. Klein; Vincent, Marie; David, Albert; Le Caignec, Cedric; Schieving, Jolanda; Gilissen, Christian; Foulds, Nicola; Rump, Patrick; Strom, Tim; Cremer, Kirsten; Zink, Alexander M.; Engels, Hartmut; de Munnik, Sonja A.; Visser, Jasper E.; Brunner, Han G.; Martens, Gerard J. M.; Pfundt, Rolph; Kleefstra, Tjitske; Kolk, Sharon M.

    Numerous genes are associated with neurodevelopmental disorders such as intellectual disability and autism spectrum disorder ( ASD), but their dysfunction is often poorly characterized. Here we identified dominant mutations in the gene encoding the transcriptional repressor and MeCP2 interactor

  8. Haploinsufficiency of MeCP2-interacting transcriptional co-repressor SIN3A causes mild intellectual disability by affecting the development of cortical integrity

    NARCIS (Netherlands)

    Witteveen, J.S.; Willemsen, M.H.; Dombroski, T.C.; Bakel, N.H. van; Nillesen, W.M.; Hulten, J.A. van; Jansen, E.J.; Verkaik, D.; Veenstra-Knol, H.E.; Ravenswaaij-Arts, C.M.A. van; Wassink-Ruiter, J.S.; Vincent, M.; David, A.; Le Caignec, C.; Schieving, J.; Gilissen, C.; Foulds, N.; Rump, P.; Strom, T.; Cremer, K.; Zink, A.M.; Engels, H.; Munnik, S.A. de; Visser, J.E.; Brunner, H.G.; Martens, G.J.; Pfundt, R.P.; Kleefstra, T.; Kolk, S.M.

    2016-01-01

    Numerous genes are associated with neurodevelopmental disorders such as intellectual disability and autism spectrum disorder (ASD), but their dysfunction is often poorly characterized. Here we identified dominant mutations in the gene encoding the transcriptional repressor and MeCP2 interactor

  9. The CytR repressor antagonizes cyclic AMP-cyclic AMP receptor protein activation of the deoCp2 promoter of Escherichia coli K-12

    DEFF Research Database (Denmark)

    Søgaard-Andersen, L; Martinussen, J; Møllegaard, N E

    1990-01-01

    We have investigated the regulation of the Escherichia coli deoCp2 promoter by the CytR repressor and the cyclic AMP (cAMP) receptor protein (CRP) complexed to cAMP. Promoter regions controlled by these two proteins characteristically contain tandem cAMP-CRP binding sites. Here we show that (i) Cyt...

  10. The basic helix-loop-helix region of the transcriptional repressor hairy and enhancer of split 1 is preorganized to bind DNA

    NARCIS (Netherlands)

    Popovic, Matija; Wienk, Hans; Coglievina, Maristella; Boelens, Rolf; Pongor, Sándor; Pintar, Alessandro

    2014-01-01

    Hairy and enhancer of split 1, one of the main downstream effectors in Notch signaling, is a transcriptional repressor of the basic helix-loop-helix (bHLH) family. Using nuclear magnetic resonance methods, we have determined the structure and dynamics of a recombinant protein, H1H, which includes an

  11. The Nuclear Factor of Activated T Cells (Nfat) Transcription Factor Nfatp (Nfatc2) Is a Repressor of Chondrogenesis

    Science.gov (United States)

    Ranger, Ann M.; Gerstenfeld, Louis C.; Wang, Jinxi; Kon, Tamiyo; Bae, Hyunsu; Gravallese, Ellen M.; Glimcher, Melvin J.; Glimcher, Laurie H.

    2000-01-01

    Nuclear factor of activated T cells (NFAT) transcription factors regulate gene expression in lymphocytes and control cardiac valve formation. Here, we report that NFATp regulates chondrogenesis in the adult animal. In mice lacking NFATp, resident cells in the extraarticular connective tissues spontaneously differentiate to cartilage. These cartilage cells progressively differentiate and the tissue undergoes endochondral ossification, recapitulating the development of endochondral bone. Proliferation of already existing articular cartilage cells also occurs in some older animals. At both sites, neoplastic changes in the cartilage cells occur. Consistent with these data, NFATp expression is regulated in mesenchymal stem cells induced to differentiate along a chondrogenic pathway. Lack of NFATp in articular cartilage cells results in increased expression of cartilage markers, whereas overexpression of NFATp in cartilage cell lines extinguishes the cartilage phenotype. Thus, NFATp is a repressor of cartilage cell growth and differentiation and also has the properties of a tumor suppressor. PMID:10620601

  12. Intercultural Mediation

    OpenAIRE

    Dragos Marian Radulescu; Denisa Mitrut

    2012-01-01

    The Intercultural Mediator facilitates exchanges between people of different socio-cultural backgrounds and acts as a bridge between immigrants and national and local associations, health organizations, services and offices in order to foster integration of every single individual. As the use mediation increases, mediators are more likely to be involved in cross-cultural mediation, but only the best mediators have the opportunity to mediate cross border business disputes or international poli...

  13. The general transcriptional repressor Tup1 is required for dimorphism and virulence in a fungal plant pathogen.

    Directory of Open Access Journals (Sweden)

    Alberto Elías-Villalobos

    2011-09-01

    Full Text Available A critical step in the life cycle of many fungal pathogens is the transition between yeast-like growth and the formation of filamentous structures, a process known as dimorphism. This morphological shift, typically triggered by multiple environmental signals, is tightly controlled by complex genetic pathways to ensure successful pathogenic development. In animal pathogenic fungi, one of the best known regulators of dimorphism is the general transcriptional repressor, Tup1. However, the role of Tup1 in fungal dimorphism is completely unknown in plant pathogens. Here we show that Tup1 plays a key role in orchestrating the yeast to hypha transition in the maize pathogen Ustilago maydis. Deletion of the tup1 gene causes a drastic reduction in the mating and filamentation capacity of the fungus, in turn leading to a reduced virulence phenotype. In U. maydis, these processes are controlled by the a and b mating-type loci, whose expression depends on the Prf1 transcription factor. Interestingly, Δtup1 strains show a critical reduction in the expression of prf1 and that of Prf1 target genes at both loci. Moreover, we observed that Tup1 appears to regulate Prf1 activity by controlling the expression of the prf1 transcriptional activators, rop1 and hap2. Additionally, we describe a putative novel prf1 repressor, named Pac2, which seems to be an important target of Tup1 in the control of dimorphism and virulence. Furthermore, we show that Tup1 is required for full pathogenic development since tup1 deletion mutants are unable to complete the sexual cycle. Our findings establish Tup1 as a key factor coordinating dimorphism in the phytopathogen U. maydis and support a conserved role for Tup1 in the control of hypha-specific genes among animal and plant fungal pathogens.

  14. Non-equilibrium repressor binding kinetics link DNA damage dose to transcriptional timing within the SOS gene network.

    Science.gov (United States)

    Culyba, Matthew J; Kubiak, Jeffrey M; Mo, Charlie Y; Goulian, Mark; Kohli, Rahul M

    2018-06-01

    Biochemical pathways are often genetically encoded as simple transcription regulation networks, where one transcription factor regulates the expression of multiple genes in a pathway. The relative timing of each promoter's activation and shut-off within the network can impact physiology. In the DNA damage repair pathway (known as the SOS response) of Escherichia coli, approximately 40 genes are regulated by the LexA repressor. After a DNA damaging event, LexA degradation triggers SOS gene transcription, which is temporally separated into subsets of 'early', 'middle', and 'late' genes. Although this feature plays an important role in regulating the SOS response, both the range of this separation and its underlying mechanism are not experimentally defined. Here we show that, at low doses of DNA damage, the timing of promoter activities is not separated. Instead, timing differences only emerge at higher levels of DNA damage and increase as a function of DNA damage dose. To understand mechanism, we derived a series of synthetic SOS gene promoters which vary in LexA-operator binding kinetics, but are otherwise identical, and then studied their activity over a large dose-range of DNA damage. In distinction to established models based on rapid equilibrium assumptions, the data best fit a kinetic model of repressor occupancy at promoters, where the drop in cellular LexA levels associated with higher doses of DNA damage leads to non-equilibrium binding kinetics of LexA at operators. Operators with slow LexA binding kinetics achieve their minimal occupancy state at later times than operators with fast binding kinetics, resulting in a time separation of peak promoter activity between genes. These data provide insight into this remarkable feature of the SOS pathway by demonstrating how a single transcription factor can be employed to control the relative timing of each gene's transcription as a function of stimulus dose.

  15. Expression, crystallization and preliminary diffraction studies of the Pseudomonas putida cytochrome P450cam operon repressor CamR

    International Nuclear Information System (INIS)

    Maenaka, Katsumi; Fukushi, Kouji; Aramaki, Hironori; Shirakihara, Yasuo

    2005-01-01

    The P. putida cytochrome P450cam operon repressor CamR has been expressed in E. coli and crystallized in space group P2 1 2 1 2. The Pseudomonas putida cam repressor (CamR) is a homodimeric protein that binds to the camO DNA operator to inhibit the transcription of the cytochrome P450cam operon camDCAB. CamR has two functional domains: a regulatory domain and a DNA-binding domain. The binding of the inducer d-camphor to the regulatory domain renders the DNA-binding domain unable to bind camO. Native CamR and its selenomethionyl derivative have been overproduced in Escherichia coli and purified. Native CamR was crystallized under the following conditions: (i) 12–14% PEG 4000, 50 mM Na PIPES, 0.1 M KCl, 1% glycerol pH 7.3 at 288 K with and without camphor and (ii) 1.6 M P i , 50 mM Na PIPES, 2 mM camphor pH 6.7 at 278 K. The selenomethionyl derivative CamR did not crystallize under either of these conditions, but did crystallize using 12.5% PEG MME 550, 25 mM Na PIPES, 2.5 mM MgCl 2 pH 7.3 at 298 K. Preliminary X-ray diffraction studies revealed the space group to be orthorhombic (P2 1 2 1 2), with unit-cell parameters a = 48.0, b = 73.3, c = 105.7 Å. Native and selenomethionyl derivative data sets were collected to 3 Å resolution at SPring-8 and the Photon Factory

  16. Genome-wide RIP-Chip analysis of translational repressor-bound mRNAs in the Plasmodium gametocyte

    KAUST Repository

    Guerreiro, Ana

    2014-11-03

    Background Following fertilization, the early proteomes of metazoans are defined by the translation of stored but repressed transcripts; further embryonic development relies on de novo transcription of the zygotic genome. During sexual development of Plasmodium berghei, a rodent model for human malaria species including P. falciparum, the stability of repressed mRNAs requires the translational repressors DOZI and CITH. When these repressors are absent, Plasmodium zygote development and transmission to the mosquito vector is halted, as hundreds of transcripts become destabilized. However, which mRNAs are direct targets of these RNA binding proteins, and thus subject to translational repression, is unknown. Results We identify the maternal mRNA contribution to post-fertilization development of P. berghei using RNA immunoprecipitation and microarray analysis. We find that 731 mRNAs, approximately 50% of the transcriptome, are associated with DOZI and CITH, allowing zygote development to proceed in the absence of RNA polymerase II transcription. Using GFP-tagging, we validate the repression phenotype of selected genes and identify mRNAs relying on the 5′ untranslated region for translational control. Gene deletion reveals a novel protein located in the ookinete crystalloid with an essential function for sporozoite development. Conclusions Our study details for the first time the P. berghei maternal repressome. This mRNA population provides the developing ookinete with coding potential for key molecules required for life-cycle progression, and that are likely to be critical for the transmission of the malaria parasite from the rodent and the human host to the mosquito vector.

  17. Emerging functions of multi-protein complex Mediator with special emphasis on plants.

    Science.gov (United States)

    Malik, Naveen; Agarwal, Pinky; Tyagi, Akhilesh

    2017-10-01

    Mediator is a multi-subunit protein complex which is involved in transcriptional regulation in yeast and other eukaryotes. As a co-activator, it connects information from transcriptional activators/repressors to transcriptional machinery including RNA polymerase II and general transcription factors. It is not only involved in transcription initiation but also has important roles to play in transcription elongation and termination. Functional attributes of different Mediator subunits have been largely defined in yeast and mammalian systems earlier, while such studies in plants have gained momentum recently. Mediator regulates various processes related to plant development and is also involved in biotic and abiotic stress response. Thus, plant Mediator, like yeast and mammalian Mediator complex, is indispensable for plant growth and survival. Interaction of its multiple subunits with other regulatory proteins and their ectopic expression or knockdown in model plant like Arabidopsis and certain crop plants are paving the way to biochemical analysis and unravel molecular mechanisms of action of Mediator in plants.

  18. Alteration of light-dependent gene regulation by the absence of the RCO-1/RCM-1 repressor complex in the fungus Neurospora crassa.

    Directory of Open Access Journals (Sweden)

    Carmen Ruger-Herreros

    Full Text Available The activation of transcription by light in the fungus Neurospora crassa requires the White Collar Complex (WCC, a photoreceptor and transcription factor complex. After light reception two WCCs interact and bind the promoters of light-regulated genes to activate transcription. This process is regulated by VVD, a small photoreceptor that disrupts the interaction between WCCs and leads to a reduction in transcription after long exposures to light. The N. crassa RCO-1/RCM-1 repressor complex is the homolog of the Tup1-Ssn6 repressor complex in yeast, and its absence modifies photoadaptation. We show that the absence of the RCO-1/RCM-1 repressor complex leads to several alterations in transcription that are gene-specific: an increase in the accumulation of mRNAs in the dark, a repression of transcription, and a derepression of transcription after long exposures to light. The absence of the RCO-1/RCM-1 repressor complex leads to lower VVD levels that are available for the regulation of the activity of the WCC. The reduction in the amount of VVD results in increased WCC binding to the promoters of light-regulated genes in the dark and after long exposures to light, leading to the modification of photoadaptation that has been observed in rco-1 and rcm-1 mutants. Our results show that the photoadaptation phenotype of mutants in the RCO-1/RCM-1 repressor complex is, at least in part, an indirect consequence of the reduction of vvd transcription, and the resulting modification in the regulation of transcription by the WCC.

  19. Effects of transgenic sterilization constructs and their repressor compounds on hatch, developmental rate and early survival of electroporated channel catfish embryos and fry.

    Science.gov (United States)

    Su, Baofeng; Shang, Mei; Li, Chao; Perera, Dayan A; Pinkert, Carl A; Irwin, Michael H; Peatman, Eric; Grewe, Peter; Patil, Jawahar G; Dunham, Rex A

    2015-04-01

    Channel catfish (Ictalurus punctatus) embryos were electroporated with sterilization constructs targeting primordial germ cell proteins or with buffer. Some embryos then were treated with repressor compounds, cadmium chloride, copper sulfate, sodium chloride or doxycycline, to prevent expression of the transgene constructs. Promoters included channel catfish nanos and vasa, salmon transferrin (TF), modified yeast Saccharomyces cerevisiae copper transport protein (MCTR) and zebrafish racemase (RM). Knock-down systems were the Tet-off (nanos and vasa constructs), MCTR, RM and TF systems. Knock-down genes included shRNAi targeting 5' nanos (N1), 3' nanos (N2) or dead end (DND), or double-stranded nanos RNA (dsRNA) for overexpression of nanos mRNA. These constructs previously were demonstrated to knock down nanos, vasa and dead end, with the repressors having variable success. Exogenous DNA affected percentage hatch (% hatch), as all 14 constructs, except for the TF dsRNA, TF N1 (T), RM DND (C), vasa DND (C), vasa N1 (C) and vasa N2 (C), had lower % hatch than the control electroporated with buffer. The MCTR and RM DND (T) constructs resulted in delayed hatch, and the vasa and nanos constructs had minimal effects on time of hatch (P nanos constructs, doxycycline greatly delayed hatch (P < 0.05). Adverse effects of the transgenes and repressors continued for several treatments for the first 6 days after hatch, but only in a few treatments during the next 10 days. Repressors and gene expression impacted the yield of putative transgenic channel catfish fry, and need to be considered and accounted for in the hatchery phase of producing transgenically sterilized catfish fry and their fertile counterparts. This fry output should be considered to ensure that sufficient numbers of transgenic fish are produced for future applications and for defining repressor systems that are the most successful.

  20. FACT, the Bur kinase pathway, and the histone co-repressor HirC have overlapping nucleosome-related roles in yeast transcription elongation.

    Directory of Open Access Journals (Sweden)

    Jennifer R Stevens

    Full Text Available Gene transcription is constrained by the nucleosomal nature of chromosomal DNA. This nucleosomal barrier is modulated by FACT, a conserved histone-binding heterodimer. FACT mediates transcription-linked nucleosome disassembly and also nucleosome reassembly in the wake of the RNA polymerase II transcription complex, and in this way maintains the repression of 'cryptic' promoters found within some genes. Here we focus on a novel mutant version of the yeast FACT subunit Spt16 that supplies essential Spt16 activities but impairs transcription-linked nucleosome reassembly in dominant fashion. This Spt16 mutant protein also has genetic effects that are recessive, which we used to show that certain Spt16 activities collaborate with histone acetylation and the activities of a Bur-kinase/Spt4-Spt5/Paf1C pathway that facilitate transcription elongation. These collaborating activities were opposed by the actions of Rpd3S, a histone deacetylase that restores a repressive chromatin environment in a transcription-linked manner. Spt16 activity paralleling that of HirC, a co-repressor of histone gene expression, was also found to be opposed by Rpd3S. Our findings suggest that Spt16, the Bur/Spt4-Spt5/Paf1C pathway, and normal histone abundance and/or stoichiometry, in mutually cooperative fashion, facilitate nucleosome disassembly during transcription elongation. The recessive nature of these effects of the mutant Spt16 protein on transcription-linked nucleosome disassembly, contrasted to its dominant negative effect on transcription-linked nucleosome reassembly, indicate that mutant FACT harbouring the mutant Spt16 protein competes poorly with normal FACT at the stage of transcription-linked nucleosome disassembly, but effectively with normal FACT for transcription-linked nucleosome reassembly. This functional difference is consistent with the idea that FACT association with the transcription elongation complex depends on nucleosome disassembly, and that the

  1. The translational repressor T-cell intracellular antigen-1 (TIA-1) is a key modulator of Th2 and Th17 responses driving pulmonary inflammation induced by exposure to house dust mite.

    Science.gov (United States)

    Simarro, Maria; Giannattasio, Giorgio; Xing, Wei; Lundequist, Emma-Maria; Stewart, Samantha; Stevens, Richard L; Orduña, Antonio; Boyce, Joshua A; Anderson, Paul J

    2012-08-30

    T-cell intracellular antigen-1 (TIA-1) is a translational repressor that dampens the production of proinflammatory cytokines and enzymes. In this study we investigated the role of TIA-1 in a mouse model of pulmonary inflammation induced by exposure to the allergenic extract (Df) of the house dust mite Dermatophagoides farinae. When intranasally challenged with a low dose of Df, mice lacking TIA-1 protein (Tia-1(-/-)) showed more severe airway and tissue eosinophilia, infiltration of lung bronchovascular bundles, and goblet cell metaplasia than wild-type littermates. Tia-1(-/-) mice also had higher levels of Df-specific IgE and IgG(1) in serum and ex vivo restimulated Tia-1(-/-) lymph node cells and splenocytes transcribed and released more Th2/Th17 cytokines. To evaluate the site of action of TIA-1, we studied the response to Df in bone marrow chimeras. These experiments revealed that TIA-1 acts on both hematopoietic and non-hematopoietic cells to dampen pulmonary inflammation. Our results identify TIA-1 as a negative regulator of allergen-mediated pulmonary inflammation in vivo. Thus, TIA-1 might be an important player in the pathogenesis of bronchial asthma. Copyright © 2012 Elsevier B.V. All rights reserved.

  2. Sorghum phytochrome B inhibits flowering in long days by activating expression of SbPRR37 and SbGHD7, repressors of SbEHD1, SbCN8 and SbCN12.

    Directory of Open Access Journals (Sweden)

    Shanshan Yang

    Full Text Available Light signaling by phytochrome B in long days inhibits flowering in sorghum by increasing expression of the long day floral repressors PSEUDORESPONSE REGULATOR PROTEIN (SbPRR37, Ma1 and GRAIN NUMBER, PLANT HEIGHT AND HEADING DATE 7 (SbGHD7, Ma6. SbPRR37 and SbGHD7 RNA abundance peaks in the morning and in the evening of long days through coordinate regulation by light and output from the circadian clock. 58 M, a phytochrome B deficient (phyB-1, ma3R genotype, flowered ∼60 days earlier than 100 M (PHYB, Ma3 in long days and ∼11 days earlier in short days. Populations derived from 58 M (Ma1, ma3R, Ma5, ma6 and R.07007 (Ma1, Ma3, ma5, Ma6 varied in flowering time due to QTL aligned to PHYB/phyB-1 (Ma3, Ma5, and GHD7/ghd7-1 (Ma6. PHYC was proposed as a candidate gene for Ma5 based on alignment and allelic variation. PHYB and Ma5 (PHYC were epistatic to Ma1 and Ma6 and progeny recessive for either gene flowered early in long days. Light signaling mediated by PhyB was required for high expression of the floral repressors SbPRR37 and SbGHD7 during the evening of long days. In 100 M (PHYB the floral activators SbEHD1, SbCN8 and SbCN12 were repressed in long days and de-repressed in short days. In 58 M (phyB-1 these genes were highly expressed in long and short days. Furthermore, SbCN15, the ortholog of rice Hd3a (FT, is expressed at low levels in 100 M but at high levels in 58 M (phyB-1 regardless of day length, indicating that PhyB regulation of SbCN15 expression may modify flowering time in a photoperiod-insensitive manner.

  3. Genome-wide association of mediator and RNA polymerase II in wild-type and mediator mutant yeast.

    Science.gov (United States)

    Paul, Emily; Zhu, Z Iris; Landsman, David; Morse, Randall H

    2015-01-01

    Mediator is a large, multisubunit complex that is required for essentially all mRNA transcription in eukaryotes. In spite of the importance of Mediator, the range of its targets and how it is recruited to these is not well understood. Previous work showed that in Saccharomyces cerevisiae, Mediator contributes to transcriptional activation by two distinct mechanisms, one depending on the tail module triad and favoring SAGA-regulated genes, and the second occurring independently of the tail module and favoring TFIID-regulated genes. Here, we use chromatin immunoprecipitation sequencing (ChIP-seq) to show that dependence on tail module subunits for Mediator recruitment and polymerase II (Pol II) association occurs preferentially at SAGA-regulated over TFIID-regulated genes on a genome-wide scale. We also show that recruitment of tail module subunits to active gene promoters continues genome-wide when Mediator integrity is compromised in med17 temperature-sensitive (ts) yeast, demonstrating the modular nature of the Mediator complex in vivo. In addition, our data indicate that promoters exhibiting strong and stable occupancy by Mediator have a wide range of activity and are enriched for targets of the Tup1-Cyc8 repressor complex. We also identify a number of strong Mediator occupancy peaks that overlap dubious open reading frames (ORFs) and are likely to include previously unrecognized upstream activator sequences. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  4. Mediation Analysis with Multiple Mediators.

    Science.gov (United States)

    VanderWeele, T J; Vansteelandt, S

    2014-01-01

    Recent advances in the causal inference literature on mediation have extended traditional approaches to direct and indirect effects to settings that allow for interactions and non-linearities. In this paper, these approaches from causal inference are further extended to settings in which multiple mediators may be of interest. Two analytic approaches, one based on regression and one based on weighting are proposed to estimate the effect mediated through multiple mediators and the effects through other pathways. The approaches proposed here accommodate exposure-mediator interactions and, to a certain extent, mediator-mediator interactions as well. The methods handle binary or continuous mediators and binary, continuous or count outcomes. When the mediators affect one another, the strategy of trying to assess direct and indirect effects one mediator at a time will in general fail; the approach given in this paper can still be used. A characterization is moreover given as to when the sum of the mediated effects for multiple mediators considered separately will be equal to the mediated effect of all of the mediators considered jointly. The approach proposed in this paper is robust to unmeasured common causes of two or more mediators.

  5. Transcriptional Repressor HIC1 Contributes to Suppressive Function of Human Induced Regulatory T Cells

    Directory of Open Access Journals (Sweden)

    Ubaid Ullah

    2018-02-01

    Full Text Available Regulatory T (Treg cells are critical in regulating the immune response. In vitro induced Treg (iTreg cells have significant potential in clinical medicine. However, applying iTreg cells as therapeutics is complicated by the poor stability of human iTreg cells and their variable suppressive activity. Therefore, it is important to understand the molecular mechanisms of human iTreg cell specification. We identified hypermethylated in cancer 1 (HIC1 as a transcription factor upregulated early during the differentiation of human iTreg cells. Although FOXP3 expression was unaffected, HIC1 deficiency led to a considerable loss of suppression by iTreg cells with a concomitant increase in the expression of effector T cell associated genes. SNPs linked to several immune-mediated disorders were enriched around HIC1 binding sites, and in vitro binding assays indicated that these SNPs may alter the binding of HIC1. Our results suggest that HIC1 is an important contributor to iTreg cell development and function.

  6. Chromosomal instability in mouse embryonic fibroblasts null for the transcriptional co-repressor Ski.

    Science.gov (United States)

    Marcelain, Katherine; Armisen, Ricardo; Aguirre, Adam; Ueki, Nobuhide; Toro, Jessica; Colmenares, Clemencia; Hayman, Michael J

    2012-01-01

    Ski is a transcriptional regulator that has been considered an oncoprotein given its ability to induce oncogenic transformation in avian model systems. However, studies in mouse and in some human tumor cells have also indicated a tumor suppressor activity for this protein. We found that Ski-/- mouse embryo fibroblasts exhibit high levels of genome instability, namely aneuploidy, consistent with a tumor suppressor function for Ski. Time-lapse microscopy revealed lagging chromosomes and chromatin/chromosome bridges as the major cause of micronuclei (MN) formation and the subsequent aneuploidy. Although these cells arrested in mitosis after treatment with spindle disrupting drugs and exhibited a delayed metaphase/anaphase transition, spindle assembly checkpoint (SAC) was not sufficient to prevent chromosome missegregation, consistent with a weakened SAC. Our in vivo analysis also showed dynamic metaphase plate rearrangements with switches in polarity in cells arrested in metaphase. Importantly, after ectopic expression of Ski the cells that displayed this metaphase arrest died directly during metaphase or after aberrant cell division, relating SAC activation and mitotic cell death. This increased susceptibility to undergo mitosis-associated cell death reduced the number of MN-containing cells. The presented data support a new role for Ski in the mitotic process and in maintenance of genetic stability, providing insights into the mechanism of tumor suppression mediated by this protein. Copyright © 2011 Wiley Periodicals, Inc.

  7. Involvement of co-repressor LUH and the adapter proteins SLK1 and SLK2 in the regulation of abiotic stress response genes in Arabidopsis.

    Science.gov (United States)

    Shrestha, Barsha; Guragain, Bhuwan; Sridhar, Vaniyambadi V

    2014-02-24

    During abiotic stress many genes that are important for growth and adaptation to stress are expressed at elevated levels. However, the mechanisms that keep the stress responsive genes from expressing under non stress conditions remain elusive. Recent genetic characterization of the co-repressor LEUNIG_HOMOLOG (LUH) and transcriptional adaptor proteins SEUSS-LIKE1 (SLK1) and SLK2 have been proposed to function redundantly in diverse developmental processes; however their function in the abiotic stress response is unknown. Moreover, the molecular functions of LUH, SLK1 and SLK2 remain obscure. Here, we show the molecular function of LUH, SLK1 and SLK2 and the role of this complex in the abiotic stress response. The luh, slk1 and slk2 mutant plants shows enhanced tolerance to salt and osmotic stress conditions. SLK1 and SLK2 interact physically with the LUFS domain in LUH forming SLK1-LUH and SLK2-LUH co-repressor complexes to inhibit the transcription. LUH has repressor activity, whereas SLK1 and SLK2 function as adaptors to recruit LUH, which in turn recruits histone deacetylase to the target sequences to repress transcription. The stress response genes RD20, MYB2 and NAC019 are expressed at elevated levels in the luh, slk1 and slk2 mutant plants. Furthermore, these stress response genes are associated with decreased nucleosome density and increased acetylation levels at H3K9 and H3K14 in the luh, slk1 and slk2 mutant plants. Our results indicate that SLK1, SLK2 and LUH form a co-repressor complex. LUH represses by means of an epigenetic process involving histone modification to facilitate the condensation of chromatin thus preventing transcription at the target genes.

  8. A phospho-sugar binding domain homologous to NagB enzymes regulates the activity of the central glycolytic genes repressor.

    Science.gov (United States)

    Doan, Thierry; Martin, Laetitia; Zorrilla, Silvia; Chaix, Denis; Aymerich, Stéphane; Labesse, Gilles; Declerck, Nathalie

    2008-06-01

    CggR belongs to the SorC family of bacterial transcriptional regulators which control the expression of genes and operons involved in carbohydrate catabolism. CggR was first identified in Bacillus subtilis where it represses the gapA operon encoding the five enzymes that catalyze the central part of glycolysis. Here we present a structure/function study demonstrating that the C-terminal region of CggR regulates the DNA binding activity of this repressor in response to binding of a phosphorylated sugar. Molecular modeling of CggR revealed a winged-helix DNA-binding motif followed by a C-terminal domain presenting weak but significant homology with glucosamine-6-phosphate deaminases from the NagB family. In silico ligand screening suggested that the CggR C-terminal domain would bind preferentially bi-phosphorylated compounds, in agreement with previous studies that proposed fructuose-1,6-biphosphate (FBP) as the inducer metabolite. In vitro, FBP was the only sugar compound capable of interfering with CggR cooperative binding to DNA. FBP was also found to protect CggR against trypsin degradation at two arginine residues predicted to reside in a mobile loop forming the active site lid of the NagB enzymes. Replacement of residues predicted to interact with FBP led to mutant CggR with altered repressor activity in vivo but retaining their structural integrity and DNA binding activity in vitro. Interestingly, some of the mutant repressors responded with different specificity towards mono- and di-phospho-fructosides. Based on these results, we propose that the activity of the CggR-like repressors is controlled by a phospho-sugar binding (PSB) domain presenting structural and functional homology with NagB enzymes. (c) 2008 Wiley-Liss, Inc.

  9. Regulatory T cells with reduced repressor capacities are extensively amplified in pulmonary sarcoid lesions and sustain granuloma formation.

    Science.gov (United States)

    Rappl, Gunter; Pabst, Stefan; Riemann, Dagmar; Schmidt, Annette; Wickenhauser, Claudia; Schütte, Wolfgang; Hombach, Andreas A; Seliger, Barbara; Grohé, Christian; Abken, Hinrich

    2011-07-01

    Sarcoidosis can evolve into a chronic disease with persistent granulomas accompanied by progressive fibrosis. While an unlimited inflammatory response suggests an impaired immune control in sarcoid lesions, it stands in contrast to the massive infiltration with CD4(+)CD25(high)FoxP3(+) regulatory T cells. We here revealed that those Treg cells in affected lung lesions were mainly derived from activated natural Treg cells with GARP (LRRC32)-positive phenotype but exhibited reduced repressor capacities despite high IL-10 and TGF-beta 1 levels. The repressive capacity of blood Treg cells, in contrast, was not impaired compared to age-matched healthy donors. Treg derived cells in granuloma lesions have undergone extensive rounds of amplifications indicated by shortened telomeres compared to blood Treg cells of the same patient. Lesional Treg derived cells moreover secreted pro-inflammatory cytokines including IL-4 which sustains granuloma formation through fibroblast amplification and the activation of mast cells, the latter indicated by the expression of membrane-bound oncostatin M. Copyright © 2011 Elsevier Inc. All rights reserved.

  10. Overexpression of a repressor MdMYB15L negatively regulates anthocyanin and cold tolerance in red-fleshed callus.

    Science.gov (United States)

    Xu, Haifeng; Yang, Guanxian; Zhang, Jing; Wang, Yicheng; Zhang, Tianliang; Wang, Nan; Jiang, Shenghui; Zhang, Zongying; Chen, Xuesen

    2018-04-14

    The cold-induced metabolic pathway and anthocyanin biosynthesis play important roles in plant growth. In this study, we identified a bHLH binding motif in the MdMYB15L protein using protein sequence analyses. Yeast two-hybrid and pull-down assays showed that MdMYB15L could interact with MdbHLH33. Overexpressing MdMYB15L in red-fleshed callus inhibited the expression of MdCBF2 and resulted in reduced cold tolerance but did not affect anthocyanin levels. Chip-PCR and EMSA analysis showed that MdMYB15L could bind the type II cis-acting element found in the MdCBF2 promoter. Overexpressing MdMYB15L in red-fleshed callus overexpressing MdbHLH33 also reduced cold tolerance and reduced MdbHLH33-induced anthocyanin biosynthesis. Knocking out the bHLH binding sequence of MdMYB15L (LBSMdMYB15L) prevented LBSMdMYB15L from interacting with MdbHLH33. Overexpressing LBSMdMYB15L in red-fleshed callus overexpressing MdbHLH33 also reduced cold tolerance and reduced MdbHLH33-induced anthocyanin biosynthesis. Together, these results suggested that an apple repressor MdMYB15L might play a key role in the cold signaling and anthocyanin metabolic pathways. Copyright © 2018 Elsevier Inc. All rights reserved.

  11. The Transcriptional Repressor MYB2 Regulates Both Spatial and Temporal Patterns of Proanthocyandin and Anthocyanin Pigmentation in Medicago truncatula.

    Science.gov (United States)

    Jun, Ji Hyung; Liu, Chenggang; Xiao, Xirong; Dixon, Richard A

    2015-10-01

    Accumulation of anthocyanins and proanthocyanidins (PAs) is limited to specific cell types and developmental stages, but little is known about how antagonistically acting transcriptional regulators work together to determine temporal and spatial patterning of pigmentation at the cellular level, especially for PAs. Here, we characterize MYB2, a transcriptional repressor regulating both anthocyanin and PA biosynthesis in the model legume Medicago truncatula. MYB2 was strongly upregulated by MYB5, a major regulator of PA biosynthesis in M. truncatula and a component of MYB-basic helix loop helix-WD40 (MBW) activator complexes. Overexpression of MYB2 abolished anthocyanin and PA accumulation in M. truncatula hairy roots and Arabidopsis thaliana seeds, respectively. Anthocyanin deposition was expanded in myb2 mutant seedlings and flowers accompanied by increased anthocyanin content. PA mainly accumulated in the epidermal layer derived from the outer integument in the M. truncatula seed coat, starting from the hilum area. The area of PA accumulation and ANTHOCYANIDIN REDUCTASE expression was expanded into the seed body at the early stage of seed development in the myb2 mutant. Genetic, biochemical, and cell biological evidence suggests that MYB2 functions as part of a multidimensional regulatory network to define the temporal and spatial pattern of anthocyanin and PA accumulation linked to developmental processes. © 2015 American Society of Plant Biologists. All rights reserved.

  12. The transcriptional repressor protein NsrR senses nitric oxide directly via a [2Fe-2S] cluster.

    Directory of Open Access Journals (Sweden)

    Nicholas P Tucker

    Full Text Available The regulatory protein NsrR, a member of the Rrf2 family of transcription repressors, is specifically dedicated to sensing nitric oxide (NO in a variety of pathogenic and non-pathogenic bacteria. It has been proposed that NO directly modulates NsrR activity by interacting with a predicted [Fe-S] cluster in the NsrR protein, but no experimental evidence has been published to support this hypothesis. Here we report the purification of NsrR from the obligate aerobe Streptomyces coelicolor. We demonstrate using UV-visible, near UV CD and EPR spectroscopy that the protein contains an NO-sensitive [2Fe-2S] cluster when purified from E. coli. Upon exposure of NsrR to NO, the cluster is nitrosylated, which results in the loss of DNA binding activity as detected by bandshift assays. Removal of the [2Fe-2S] cluster to generate apo-NsrR also resulted in loss of DNA binding activity. This is the first demonstration that NsrR contains an NO-sensitive [2Fe-2S] cluster that is required for DNA binding activity.

  13. The Response Regulator YycF Inhibits Expression of the Fatty Acid Biosynthesis Repressor FabT in Streptococcus pneumoniae

    Science.gov (United States)

    Mohedano, Maria L.; Amblar, Mónica; de la Fuente, Alicia; Wells, Jerry M.; López, Paloma

    2016-01-01

    The YycFG (also known as WalRK, VicRK, MicAB, or TCS02) two-component system (TCS) is highly conserved among Gram-positive bacteria with a low G+C content. In Streptococcus pneumoniae the YycF response regulator has been reported to be essential due to its control of pcsB gene expression. Previously we showed that overexpression of yycF in S. pneumoniae TIGR4 altered the transcription of genes involved in cell wall metabolism and fatty acid biosynthesis, giving rise to anomalous cell division and increased chain length of membrane fatty acids. Here, we have overexpressed the yycFG system in TIGR4 wild-type strain and yycF in a TIGR4 mutant depleted of YycG, and analyzed their effects on expression of proteins involved in fatty acid biosynthesis during activation of the TCS. We demonstrate that transcription of the fab genes and levels of their products were only altered in the YycF overexpressing strain, indicating that the unphosphorylated form of YycF is involved in the regulation of fatty acid biosynthesis. In addition, DNA-binding assays and in vitro transcription experiments with purified YycF and the promoter region of the FabTH-acp operon support a direct inhibition of transcription of the FabT repressor by YycF, thus confirming the role of the unphosphorylated form in transcriptional regulation. PMID:27610104

  14. MDM2 Associates with Polycomb Repressor Complex 2 and Enhances Stemness-Promoting Chromatin Modifications Independent of p53

    DEFF Research Database (Denmark)

    Wienken, Magdalena; Dickmanns, Antje; Nemajerova, Alice

    2016-01-01

    The MDM2 oncoprotein ubiquitinates and antagonizes p53 but may also carry out p53-independent functions. Here we report that MDM2 is required for the efficient generation of induced pluripotent stem cells (iPSCs) from murine embryonic fibroblasts, in the absence of p53. Similarly, MDM2 depletion...... in the context of p53 deficiency also promoted the differentiation of human mesenchymal stem cells and diminished clonogenic survival of cancer cells. Most of the MDM2-controlled genes also responded to the inactivation of the Polycomb Repressor Complex 2 (PRC2) and its catalytic component EZH2. MDM2 physically...... associated with EZH2 on chromatin, enhancing the trimethylation of histone 3 at lysine 27 and the ubiquitination of histone 2A at lysine 119 (H2AK119) at its target genes. Removing MDM2 simultaneously with the H2AK119 E3 ligase Ring1B/RNF2 further induced these genes and synthetically arrested cell...

  15. Quaternary re-arrangement analysed by spectral enhancement: the interaction of a sporulation repressor with its antagonist.

    Science.gov (United States)

    Scott, D J; Leejeerajumnean, S; Brannigan, J A; Lewis, R J; Wilkinson, A J; Hoggett, J G

    1999-11-12

    The protein/protein interaction between SinI and SinR has been studied by analytical ultracentrifugation and gel electrophoresis in an attempt to understand how these proteins contribute to developmental control of sporulation in Bacillus subtilis. SinR was found to be tetrameric, while SinI was found to exist as monomers and dimers in a rapidly reversible equilibrium. Labelling of SinR by incorporating the tryptophan analogue 7-azatryptophan (7AW) into the protein in place of tryptophan shifts the UV absorbance spectrum, thus allowing selective monitoring of 7AWSinR at 315 nm using the UV absorption optics of the analytical ultracentrifuge. Selective monitoring of SinR in mixtures of SinR and SinI enables the binding and stoichiometry of the interaction to be investigated quantitatively and unambiguously. We demonstrate that the oligomeric forms of SinR and SinI re-arrange to form a tight 1:1 SinR:SinI complex, with no stable intermediate species. A fragment of SinR, SinR(1-69), which contains only the DNA-binding domain, was found to be monomeric, showing that the protein appears not to oligomerise in a similar manner to the Cro repressor, a protein with which it shares a marked structural similarity. Copyright 1999 Academic Press.

  16. Functional analysis of the global repressor Tup1 for maltose metabolism in Saccharomyces cerevisiae: different roles of the functional domains.

    Science.gov (United States)

    Lin, Xue; Yu, Ai-Qun; Zhang, Cui-Ying; Pi, Li; Bai, Xiao-Wen; Xiao, Dong-Guang

    2017-11-09

    Tup1 is a general transcriptional repressor of diverse gene families coordinately controlled by glucose repression, mating type, and other mechanisms in Saccharomyces cerevisiae. Several functional domains of Tup1 have been identified, each of which has differing effects on transcriptional repression. In this study, we aim to investigate the role of Tup1 and its domains in maltose metabolism of industrial baker's yeast. To this end, a battery of in-frame truncations in the TUP1 gene coding region were performed in the industrial baker's yeasts with different genetic background, and the maltose metabolism, leavening ability, MAL gene expression levels, and growth characteristics were investigated. The results suggest that the TUP1 gene is essential to maltose metabolism in industrial baker's yeast. Importantly, different domains of Tup1 play different roles in glucose repression and maltose metabolism of industrial baker's yeast cells. The Ssn6 interaction, N-terminal repression and C-terminal repression domains might play roles in the regulation of MAL transcription by Tup1 for maltose metabolism of baker's yeast. The WD region lacking the first repeat could influence the regulation of maltose metabolism directly, rather than indirectly through glucose repression. These findings lay a foundation for the optimization of industrial baker's yeast strains for accelerated maltose metabolism and facilitate future research on glucose repression in other sugar metabolism.

  17. Enhancing succinic acid biosynthesis in Escherichia coli by engineering its global transcription factor, catabolite repressor/activator (Cra).

    Science.gov (United States)

    Zhu, Li-Wen; Xia, Shi-Tao; Wei, Li-Na; Li, Hong-Mei; Yuan, Zhan-Peng; Tang, Ya-Jie

    2016-11-04

    This study was initiated to improve E. coli succinate production by engineering the E. coli global transcription factor, Cra (catabolite repressor/activator). Random mutagenesis libraries were generated through error-prone PCR of cra. After re-screening and mutation site integration, the best mutant strain was Tang1541, which provided a final succinate concentration of 79.8 ± 3.1 g/L: i.e., 22.8% greater than that obtained using an empty vector control. The genes and enzymes involved in phosphoenolpyruvate (PEP) carboxylation and the glyoxylate pathway were activated, either directly or indirectly, through the mutation of Cra. The parameters for interaction of Cra and DNA indicated that the Cra mutant was bound to aceBAK, thereby activating the genes involved in glyoxylate pathway and further improving succinate production even in the presence of its effector fructose-1,6-bisphosphate (FBP). It suggested that some of the negative effect of FBP on Cra might have been counteracted through the enhanced binding affinity of the Cra mutant for FBP or the change of Cra structure. This work provides useful information about understanding the transcriptional regulation of succinate biosynthesis.

  18. The MogR Transcriptional Repressor Regulates Nonhierarchal Expression of Flagellar Motility Genes and Virulence in Listeria monocytogenes.

    Directory of Open Access Journals (Sweden)

    2006-04-01

    Full Text Available Flagella are surface structures critical for motility and virulence of many bacterial species. In Listeria monocytogenes, MogR tightly represses expression of flagellin (FlaA during extracellular growth at 37 degrees C and during intracellular infection. MogR is also required for full virulence in a murine model of infection. Using in vitro and in vivo infection models, we determined that the severe virulence defect of MogR-negative bacteria is due to overexpression of FlaA. Specifically, overproduction of FlaA in MogR-negative bacteria caused pleiotropic defects in bacterial division (chaining phenotype, intracellular spread, and virulence in mice. DNA binding and microarray analyses revealed that MogR represses transcription of all known flagellar motility genes by binding directly to a minimum of two TTTT-N(5-AAAA recognition sites positioned within promoter regions such that RNA polymerase binding is occluded. Analysis of MogR protein levels demonstrated that modulation of MogR repression activity confers the temperature-specificity to flagellar motility gene expression. Epistasis analysis revealed that MogR repression of transcription is antagonized in a temperature-dependent manner by the DegU response regulator and that DegU further regulates FlaA levels through a posttranscriptional mechanism. These studies provide the first known example to our knowledge of a transcriptional repressor functioning as a master regulator controlling nonhierarchal expression of flagellar motility genes.

  19. Second-hit mosaic mutation in mTORC1 repressor DEPDC5 causes focal cortical dysplasia-associated epilepsy.

    Science.gov (United States)

    Ribierre, Théo; Deleuze, Charlotte; Bacq, Alexandre; Baldassari, Sara; Marsan, Elise; Chipaux, Mathilde; Muraca, Giuseppe; Roussel, Delphine; Navarro, Vincent; Leguern, Eric; Miles, Richard; Baulac, Stéphanie

    2018-04-30

    DEP domain-containing 5 protein (DEPDC5) is a repressor of the recently recognized amino acid-sensing branch of the mTORC1 pathway. So far, its function in the brain remains largely unknown. Germline loss-of-function mutations in DEPDC5 have emerged as a major cause of familial refractory focal epilepsies, with case reports of sudden unexpected death in epilepsy (SUDEP). Remarkably, a fraction of patients also develop focal cortical dysplasia (FCD), a neurodevelopmental cortical malformation. We therefore hypothesized that a somatic second-hit mutation arising during brain development may support the focal nature of the dysplasia. Here, using postoperative human tissue, we provide the proof of concept that a biallelic 2-hit - brain somatic and germline - mutational mechanism in DEPDC5 causes focal epilepsy with FCD. We discovered a mutation gradient with a higher rate of mosaicism in the seizure-onset zone than in the surrounding epileptogenic zone. Furthermore, we demonstrate the causality of a Depdc5 brain mosaic inactivation using CRISPR-Cas9 editing and in utero electroporation in a mouse model recapitulating focal epilepsy with FCD and SUDEP-like events. We further unveil a key role of Depdc5 in shaping dendrite and spine morphology of excitatory neurons. This study reveals promising therapeutic avenues for treating drug-resistant focal epilepsies with mTORC1-targeting molecules.

  20. Small ubiquitin-like modifier (SUMO) conjugation impedes transcriptional silencing by the polycomb group repressor Sex Comb on Midleg.

    Science.gov (United States)

    Smith, Matthew; Mallin, Daniel R; Simon, Jeffrey A; Courey, Albert J

    2011-04-01

    The Drosophila protein Sex Comb on Midleg (Scm) is a member of the Polycomb group (PcG), a set of transcriptional repressors that maintain silencing of homeotic genes during development. Recent findings have identified PcG proteins both as targets for modification by the small ubiquitin-like modifier (SUMO) protein and as catalytic components of the SUMO conjugation pathway. We have found that the SUMO-conjugating enzyme Ubc9 binds to Scm and that this interaction, which requires the Scm C-terminal sterile α motif (SAM) domain, is crucial for the efficient sumoylation of Scm. Scm is associated with the major Polycomb response element (PRE) of the homeotic gene Ultrabithorax (Ubx), and efficient PRE recruitment requires an intact Scm SAM domain. Global reduction of sumoylation augments binding of Scm to the PRE. This is likely to be a direct effect of Scm sumoylation because mutations in the SUMO acceptor sites in Scm enhance its recruitment to the PRE, whereas translational fusion of SUMO to the Scm N terminus interferes with this recruitment. In the metathorax, Ubx expression promotes haltere formation and suppresses wing development. When SUMO levels are reduced, we observe decreased expression of Ubx and partial haltere-to-wing transformation phenotypes. These observations suggest that SUMO negatively regulates Scm function by impeding its recruitment to the Ubx major PRE.

  1. Small Ubiquitin-like Modifier (SUMO) Conjugation Impedes Transcriptional Silencing by the Polycomb Group Repressor Sex Comb on Midleg*

    Science.gov (United States)

    Smith, Matthew; Mallin, Daniel R.; Simon, Jeffrey A.; Courey, Albert J.

    2011-01-01

    The Drosophila protein Sex Comb on Midleg (Scm) is a member of the Polycomb group (PcG), a set of transcriptional repressors that maintain silencing of homeotic genes during development. Recent findings have identified PcG proteins both as targets for modification by the small ubiquitin-like modifier (SUMO) protein and as catalytic components of the SUMO conjugation pathway. We have found that the SUMO-conjugating enzyme Ubc9 binds to Scm and that this interaction, which requires the Scm C-terminal sterile α motif (SAM) domain, is crucial for the efficient sumoylation of Scm. Scm is associated with the major Polycomb response element (PRE) of the homeotic gene Ultrabithorax (Ubx), and efficient PRE recruitment requires an intact Scm SAM domain. Global reduction of sumoylation augments binding of Scm to the PRE. This is likely to be a direct effect of Scm sumoylation because mutations in the SUMO acceptor sites in Scm enhance its recruitment to the PRE, whereas translational fusion of SUMO to the Scm N terminus interferes with this recruitment. In the metathorax, Ubx expression promotes haltere formation and suppresses wing development. When SUMO levels are reduced, we observe decreased expression of Ubx and partial haltere-to-wing transformation phenotypes. These observations suggest that SUMO negatively regulates Scm function by impeding its recruitment to the Ubx major PRE. PMID:21278366

  2. Loss of the co-repressor GPS2 sensitizes macrophage activation upon metabolic stress induced by obesity and type 2 diabetes.

    Science.gov (United States)

    Fan, Rongrong; Toubal, Amine; Goñi, Saioa; Drareni, Karima; Huang, Zhiqiang; Alzaid, Fawaz; Ballaire, Raphaelle; Ancel, Patricia; Liang, Ning; Damdimopoulos, Anastasios; Hainault, Isabelle; Soprani, Antoine; Aron-Wisnewsky, Judith; Foufelle, Fabienne; Lawrence, Toby; Gautier, Jean-Francois; Venteclef, Nicolas; Treuter, Eckardt

    2016-07-01

    Humans with obesity differ in their susceptibility to developing insulin resistance and type 2 diabetes (T2D). This variation may relate to the extent of adipose tissue (AT) inflammation that develops as their obesity progresses. The state of macrophage activation has a central role in determining the degree of AT inflammation and thus its dysfunction, and these states are driven by epigenomic alterations linked to gene expression. The underlying mechanisms that regulate these alterations, however, are poorly defined. Here we demonstrate that a co-repressor complex containing G protein pathway suppressor 2 (GPS2) crucially controls the macrophage epigenome during activation by metabolic stress. The study of AT from humans with and without obesity revealed correlations between reduced GPS2 expression in macrophages, elevated systemic and AT inflammation, and diabetic status. The causality of this relationship was confirmed by using macrophage-specific Gps2-knockout (KO) mice, in which inappropriate co-repressor complex function caused enhancer activation, pro-inflammatory gene expression and hypersensitivity toward metabolic-stress signals. By contrast, transplantation of GPS2-overexpressing bone marrow into two mouse models of obesity (ob/ob and diet-induced obesity) reduced inflammation and improved insulin sensitivity. Thus, our data reveal a potentially reversible disease mechanism that links co-repressor-dependent epigenomic alterations in macrophages to AT inflammation and the development of T2D.

  3. Negative regulators of brown adipose tissue (BAT)-mediated thermogenesis.

    Science.gov (United States)

    Sharma, Bal Krishan; Patil, Mallikarjun; Satyanarayana, Ande

    2014-12-01

    Brown adipose tissue (BAT) is specialized for energy expenditure, a process called adaptive thermogenesis. PET-CT scans recently demonstrated the existence of metabolically active BAT in adult humans, which revitalized our interest in BAT. Increasing the amount and/or activity of BAT holds tremendous promise for the treatment of obesity and its associated diseases. PGC1α is the master regulator of UCP1-mediated thermogenesis in BAT. A number of proteins have been identified to influence thermogenesis either positively or negatively through regulating the expression or transcriptional activity of PGC1α. Therefore, BAT activation can be achieved by either inducing the expression of positive regulators of PGC1α or by inhibiting the repressors of the PGC1α/UCP1 pathway. Here, we review the most important negative regulators of PGC1α/UCP1 signaling and their mechanism of action in BAT-mediated thermogenesis. © 2014 Wiley Periodicals, Inc.

  4. Mediation Analysis with Multiple Mediators

    OpenAIRE

    VanderWeele, T.J.; Vansteelandt, S.

    2014-01-01

    Recent advances in the causal inference literature on mediation have extended traditional approaches to direct and indirect effects to settings that allow for interactions and non-linearities. In this paper, these approaches from causal inference are further extended to settings in which multiple mediators may be of interest. Two analytic approaches, one based on regression and one based on weighting are proposed to estimate the effect mediated through multiple mediators and the effects throu...

  5. The Bacterial Effector HopX1 Targets JAZ Transcriptional Repressors to Activate Jasmonate Signaling and Promote Infection in Arabidopsis

    Science.gov (United States)

    Gimenez-Ibanez, Selena; Boter, Marta; Fernández-Barbero, Gemma; Chini, Andrea; Rathjen, John P.; Solano, Roberto

    2014-01-01

    Pathogenicity of Pseudomonas syringae is dependent on a type III secretion system, which secretes a suite of virulence effector proteins into the host cytoplasm, and the production of a number of toxins such as coronatine (COR), which is a mimic of the plant hormone jasmonate-isoleuce (JA-Ile). Inside the plant cell, effectors target host molecules to subvert the host cell physiology and disrupt defenses. However, despite the fact that elucidating effector action is essential to understanding bacterial pathogenesis, the molecular function and host targets of the vast majority of effectors remain largely unknown. Here, we found that effector HopX1 from Pseudomonas syringae pv. tabaci (Pta) 11528, a strain that does not produce COR, interacts with and promotes the degradation of JAZ proteins, a key family of JA-repressors. We show that hopX1 encodes a cysteine protease, activity that is required for degradation of JAZs by HopX1. HopX1 associates with JAZ proteins through its central ZIM domain and degradation occurs in a COI1-independent manner. Moreover, ectopic expression of HopX1 in Arabidopsis induces the expression of JA-dependent genes, represses salicylic acid (SA)-induced markers, and complements the growth of a COR-deficient P. syringae pv. tomato (Pto) DC3000 strain during natural bacterial infections. Furthermore, HopX1 promoted susceptibility when delivered by the natural type III secretion system, to a similar extent as the addition of COR, and this effect was dependent on its catalytic activity. Altogether, our results indicate that JAZ proteins are direct targets of bacterial effectors to promote activation of JA-induced defenses and susceptibility in Arabidopsis. HopX1 illustrates a paradigm of an alternative evolutionary solution to COR with similar physiological outcome. PMID:24558350

  6. Gli3 acts as a repressor downstream of Ihh in regulating two distinct steps of chondrocyte differentiation.

    Science.gov (United States)

    Koziel, Lydia; Wuelling, Manuela; Schneider, Sabine; Vortkamp, Andrea

    2005-12-01

    During endochondral ossification, the secreted growth factor Indian hedgehog (Ihh) regulates several differentiation steps. It interacts with a second secreted factor, parathyroid hormone-related protein (PTHrP), to regulate the onset of hypertrophic differentiation, and it regulates chondrocyte proliferation and ossification of the perichondrium independently of PTHrP. To investigate how the Ihh signal is translated in the different target tissues, we analyzed the role of the zinc-finger transcription factor Gli3, which acts downstream of hedgehog signals in other organs. Loss of Gli3 in Ihh mutants restores chondrocyte proliferation and delays the accelerated onset of hypertrophic differentiation observed in Ihh-/- mutants. Furthermore the expression of the Ihh target genes patched (Ptch) and PTHrP is reactivated in Ihh-/-;Gli3-/- mutants. Gli3 seems thus to act as a strong repressor of Ihh signals in regulating chondrocyte differentiation. In addition, loss of Gli3 in mice that overexpress Ihh in chondrocytes accelerates the onset of hypertrophic differentiation by reducing the domain and possibly the level of PTHrP expression. Careful analysis of chondrocyte differentiation in Gli3-/- mutants revealed that Gli3 negatively regulates the differentiation of distal, low proliferating chondrocytes into columnar, high proliferating cells. Our results suggest a model in which the Ihh/Gli3 system regulates two distinct steps of chondrocyte differentiation: (1) the switch from distal into columnar chondrocytes is repressed by Gli3 in a PTHrP-independent mechanism; (2) the transition from proliferating into hypertrophic chondrocytes is regulated by Gli3-dependent expression of PTHrP. Furthermore, by regulating distal chondrocyte differentiation, Gli3 seems to position the domain of PTHrP expression.

  7. Sequence of ligand binding and structure change in the diphtheria toxin repressor upon activation by divalent transition metals.

    Science.gov (United States)

    Rangachari, Vijayaraghavan; Marin, Vedrana; Bienkiewicz, Ewa A; Semavina, Maria; Guerrero, Luis; Love, John F; Murphy, John R; Logan, Timothy M

    2005-04-19

    The diphtheria toxin repressor (DtxR) is an Fe(II)-activated transcriptional regulator of iron homeostatic and virulence genes in Corynebacterium diphtheriae. DtxR is a two-domain protein that contains two structurally and functionally distinct metal binding sites. Here, we investigate the molecular steps associated with activation by Ni(II)Cl(2) and Cd(II)Cl(2). Equilibrium binding energetics for Ni(II) were obtained from isothermal titration calorimetry, indicating apparent metal dissociation constants of 0.2 and 1.7 microM for two independent sites. The binding isotherms for Ni(II) and Cd(II) exhibited a characteristic exothermic-endothermic pattern that was used to infer the metal binding sequence by comparing the wild-type isotherm with those of several binding site mutants. These data were complemented by measuring the distance between specific backbone amide nitrogens and the first equivalent of metal through heteronuclear NMR relaxation measurements. Previous studies indicated that metal binding affects a disordered to ordered transition in the metal binding domain. The coupling between metal binding and structure change was investigated using near-UV circular dichroism spectroscopy. Together, the data show that the first equivalent of metal is bound by the primary metal binding site. This binding orients the DNA binding helices and begins to fold the N-terminal domain. Subsequent binding at the ancillary site completes the folding of this domain and formation of the dimer interface. This model is used to explain the behavior of several mutants.

  8. Structure-guided approach to site-specific fluorophore labeling of the lac repressor LacI.

    Directory of Open Access Journals (Sweden)

    Kalle Kipper

    Full Text Available The lactose operon repressor protein LacI has long served as a paradigm of the bacterial transcription factors. However, the mechanisms whereby LacI rapidly locates its cognate binding site on the bacterial chromosome are still elusive. Single-molecule fluorescence imaging approaches are well suited for the study of these mechanisms but rely on a functionally compatible fluorescence labeling of LacI. Particularly attractive for protein fluorescence labeling are synthetic fluorophores due to their small size and favorable photophysical characteristics. Synthetic fluorophores are often conjugated to natively occurring cysteine residues using maleimide chemistry. For a site-specific and functionally compatible labeling with maleimide fluorophores, the target protein often needs to be redesigned to remove unwanted native cysteines and to introduce cysteines at locations better suited for fluorophore attachment. Biochemical screens can then be employed to probe for the functional activity of the redesigned protein both before and after dye labeling. Here, we report a mutagenesis-based redesign of LacI to enable a functionally compatible labeling with maleimide fluorophores. To provide an easily accessible labeling site in LacI, we introduced a single cysteine residue at position 28 in the DNA-binding headpiece of LacI and replaced two native cysteines with alanines where derivatization with bulky substituents is known to compromise the protein's activity. We find that the redesigned LacI retains a robust activity in vitro and in vivo, provided that the third native cysteine at position 281 is retained in LacI. In a total internal reflection microscopy assay, we observed individual Cy3-labeled LacI molecules bound to immobilized DNA harboring the cognate O1 operator sequence, indicating that the dye-labeled LacI is functionally active. We have thus been able to generate a functional fluorescently labeled LacI that can be used to unravel mechanistic

  9. The translational repressor Crc controls the Pseudomonas putida benzoate and alkane catabolic pathways using a multi-tier regulation strategy.

    Science.gov (United States)

    Hernández-Arranz, Sofía; Moreno, Renata; Rojo, Fernando

    2013-01-01

    Metabolically versatile bacteria usually perceive aromatic compounds and hydrocarbons as non-preferred carbon sources, and their assimilation is inhibited if more preferable substrates are available. This is achieved via catabolite repression. In Pseudomonas putida, the expression of the genes allowing the assimilation of benzoate and n-alkanes is strongly inhibited by catabolite repression, a process controlled by the translational repressor Crc. Crc binds to and inhibits the translation of benR and alkS mRNAs, which encode the transcriptional activators that induce the expression of the benzoate and alkane degradation genes respectively. However, sequences similar to those recognized by Crc in benR and alkS mRNAs exist as well in the translation initiation regions of the mRNA of several structural genes of the benzoate and alkane pathways, which suggests that Crc may also regulate their translation. The present results show that some of these sites are functional, and that Crc inhibits the induction of both pathways by limiting not only the translation of their transcriptional activators, but also that of genes coding for the first enzyme in each pathway. Crc may also inhibit the translation of a gene involved in benzoate uptake. This multi-tier approach probably ensures the rapid regulation of pathway genes, minimizing the assimilation of non-preferred substrates when better options are available. A survey of possible Crc sites in the mRNAs of genes associated with other catabolic pathways suggested that targeting substrate uptake, pathway induction and/or pathway enzymes may be a common strategy to control the assimilation of non-preferred compounds. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

  10. Isolation and Functional Characterization of a Floral Repressor, BcMAF1, From Pak-choi (Brassica rapa ssp. Chinensis).

    Science.gov (United States)

    Huang, Feiyi; Liu, Tongkun; Hou, Xilin

    2018-01-01

    MADS-box genes form a large gene family in plants and are involved in multiple biological processes, such as flowering. However, the regulation mechanism of MADS-box genes in flowering remains unresolved, especially under short-term cold conditions. In the present study, we isolated BcMAF1 , a Pak-choi ( Brassica rapa ssp. Chinensis ) MADS AFFECTING FLOWERING ( MAF ), as a floral repressor and functionally characterized BcMAF1 in Arabidopsis and Pak-choi. Subcellular localization and sequence analysis indicated that BcMAF1 was a nuclear protein and contained a conserved MADS-box domain. Expression analysis revealed that BcMAF1 had higher expression levels in leaves, stems, and petals, and could be induced by short-term cold conditions in Pak-choi. Overexpressing BcMAF1 in Arabidopsis showed that BcMAF1 had a negative function in regulating flowering, which was further confirmed by silencing endogenous BcMAF1 in Pak-choi. In addition, qPCR results showed that AtAP3 expression was reduced and AtMAF2 expression was induced in BcMAF1 -overexpressing Arabidopsis . Meanwhile, BcAP3 transcript was up-regulated and BcMAF2 transcript was down-regulated in BcMAF1 -silencing Pak-choi. Yeast one-hybrid and dual luciferase transient assays showed that BcMAF1 could bind to the promoters of BcAP3 and BcMAF2 . These results indicated that BcAP3 and BcMAF2 might be the targets of BcMAF1. Taken together, our results suggested that BcMAF1 could negatively regulate flowering by directly activating BcMAF2 and repressing BcAP3 .

  11. Acid-responsive gene induction of ammonia-producing enzymes in Helicobacter pylori is mediated via a metal-responsive repressor cascade

    NARCIS (Netherlands)

    A.H.M. van Vliet (Arnoud); E.J. Kuipers (Ernst); J. Stoof (Jeroen); S.W. Poppelaars (Sophie); J.G. Kusters (Johannes)

    2004-01-01

    textabstractAlthough the adaptive mechanisms allowing the gastric pathogen Helicobacter pylori to survive acid shocks have been well documented, the mechanisms allowing growth at mildly acidic conditions (pH approximately 5.5) are still poorly understood. Here we demonstrate that

  12. PTB-associated splicing factor (PSF) functions as a repressor of STAT6-mediated IG{epsilon} gene transcription by recruitment of HDAC1

    DEFF Research Database (Denmark)

    Dong, Lijie; Zhang, Xinyu; Fu, Xiao

    2010-01-01

    understood. Here we identified by proteomic approach that PTB-associated splicing factor (PSF) interacts with STAT6. In cells the interaction required IL-4 stimulation and was observed both with endogenous and ectopically expressed proteins. The ligand dependency of the interaction suggested involvement...

  13. Assessing the Role of ETHYLENE RESPONSE FACTOR Transcriptional Repressors in Salicylic Acid-Mediated Suppression of Jasmonic Acid-Responsive Genes

    NARCIS (Netherlands)

    Caarls, Lotte; van der Does, Adriana; Hickman, Richard; Jansen, Wouter; van Verk, Marcel; Proietti, Silvia; Lorenzo, Oscar; Solano, Roberto; Pieterse, Corné M J; Van Wees, Saskia C M

    2017-01-01

    Salicylic acid (SA) and jasmonic acid (JA) cross-communicate in the plant immune signaling network to finely regulate induced defenses. In Arabidopsis, SA antagonizes many JA-responsive genes, partly by targeting the ETHYLENE RESPONSE FACTOR (ERF)-type transcriptional activator ORA59. Members of the

  14. Complex Mediation

    DEFF Research Database (Denmark)

    Bødker, Susanne; Andersen, Peter Bøgh

    2005-01-01

    This article has its starting point in a large number of empirical findings regarding computer-mediated work. These empirical findings have challenged our understanding of the role of mediation in such work; on the one hand as an aspect of communication and cooperation at work and on the other hand...... as an aspect of human engagement with instruments of work. On the basis of previous work in activity-theoretical and semiotic human—computer interaction, we propose a model to encompass both of these aspects. In a dialogue with our empirical findings we move on to propose a number of types of mediation...... that have helped to enrich our understanding of mediated work and the design of computer mediation for such work....

  15. The Phenylpropanoid Pathway Is Controlled at Different Branches by a Set of R2R3-MYB C2 Repressors in Grapevine1

    Science.gov (United States)

    Cavallini, Erika; Matus, José Tomás; Finezzo, Laura; Zenoni, Sara; Loyola, Rodrigo; Guzzo, Flavia; Schlechter, Rudolf; Ageorges, Agnès; Arce-Johnson, Patricio

    2015-01-01

    Because of the vast range of functions that phenylpropanoids possess, their synthesis requires precise spatiotemporal coordination throughout plant development and in response to the environment. The accumulation of these secondary metabolites is transcriptionally controlled by positive and negative regulators from the MYB and basic helix-loop-helix protein families. We characterized four grapevine (Vitis vinifera) R2R3-MYB proteins from the C2 repressor motif clade, all of which harbor the ethylene response factor-associated amphiphilic repression domain but differ in the presence of an additional TLLLFR repression motif found in the strong flavonoid repressor Arabidopsis (Arabidopsis thaliana) AtMYBL2. Constitutive expression of VvMYB4a and VvMYB4b in petunia (Petunia hybrida) repressed general phenylpropanoid biosynthetic genes and selectively reduced the amount of small-weight phenolic compounds. Conversely, transgenic petunia lines expressing VvMYBC2-L1 and VvMYBC2-L3 showed a severe reduction in petal anthocyanins and seed proanthocyanidins together with a higher pH of crude petal extracts. The distinct function of these regulators was further confirmed by transient expression in tobacco (Nicotiana benthamiana) leaves and grapevine plantlets. Finally, VvMYBC2-L3 was ectopically expressed in grapevine hairy roots, showing a reduction in proanthocyanidin content together with the down-regulation of structural and regulatory genes of the flavonoid pathway as revealed by a transcriptomic analysis. The physiological role of these repressors was inferred by combining the results of the functional analyses and their expression patterns in grapevine during development and in response to ultraviolet B radiation. Our results indicate that VvMYB4a and VvMYB4b may play a key role in negatively regulating the synthesis of small-weight phenolic compounds, whereas VvMYBC2-L1 and VvMYBC2-L3 may additionally fine tune flavonoid levels, balancing the inductive effects of

  16. The Transcriptional Repressor TupA in Aspergillus niger Is Involved in Controlling Gene Expression Related to Cell Wall Biosynthesis, Development, and Nitrogen Source Availability

    DEFF Research Database (Denmark)

    Schachtschabel, Doreen; Arentshorst, Mark; Nitsche, Benjamin M

    2013-01-01

    The Tup1-Cyc8 (Ssn6) complex is a well characterized and conserved general transcriptional repressor complex in eukaryotic cells. Here, we report the identification of the Tup1 (TupA) homolog in the filamentous fungus Aspergillus niger in a genetic screen for mutants with a constitutive expression...... of the agsA gene. The agsA gene encodes a putative alpha-glucan synthase, which is induced in response to cell wall stress in A. niger. Apart from the constitutive expression of agsA, the selected mutant was also found to produce an unknown pigment at high temperatures. Complementation analysis...

  17. Comparative Analysis of Chromatin Binding by Sex Comb on Midleg (SCM) and Other Polycomb Group Repressors at a Drosophila Hox Gene▿

    OpenAIRE

    Wang, Liangjun; Jahren, Neal; Miller, Ellen L.; Ketel, Carrie S.; Mallin, Daniel R.; Simon, Jeffrey A.

    2010-01-01

    Sex Comb on Midleg (SCM) is a transcriptional repressor in the Polycomb group (PcG), but its molecular role in PcG silencing is not known. Although SCM can interact with Polycomb repressive complex 1 (PRC1) in vitro, biochemical studies have indicated that SCM is not a core constituent of PRC1 or PRC2. Nevertheless, SCM is just as critical for Drosophila Hox gene silencing as canonical subunits of these well-characterized PcG complexes. To address functional relationships between SCM and othe...

  18. Prediction of DtxR regulon: Identification of binding sites and operons controlled by Diphtheria toxin repressor in Corynebacterium diphtheriae

    Directory of Open Access Journals (Sweden)

    Hasnain Seyed

    2004-09-01

    Full Text Available Abstract Background The diphtheria toxin repressor, DtxR, of Corynebacterium diphtheriae has been shown to be an iron-activated transcription regulator that controls not only the expression of diphtheria toxin but also of iron uptake genes. This study aims to identify putative binding sites and operons controlled by DtxR to understand the role of DtxR in patho-physiology of Corynebacterium diphtheriae. Result Positional Shannon relative entropy method was used to build the DtxR-binding site recognition profile and the later was used to identify putative regulatory sites of DtxR within C. diphtheriae genome. In addition, DtxR-regulated operons were also identified taking into account the predicted DtxR regulatory sites and genome annotation. Few of the predicted motifs were experimentally validated by electrophoretic mobility shift assay. The analysis identifies motifs upstream to the novel iron-regulated genes that code for Formamidopyrimidine-DNA glycosylase (FpG, an enzyme involved in DNA-repair and starvation inducible DNA-binding protein (Dps which is involved in iron storage and oxidative stress defense. In addition, we have found the DtxR motifs upstream to the genes that code for sortase which catalyzes anchoring of host-interacting proteins to the cell wall of pathogenic bacteria and the proteins of secretory system which could be involved in translocation of various iron-regulated virulence factors including diphtheria toxin. Conclusions We have used an in silico approach to identify the putative binding sites and genes controlled by DtxR in Corynebacterium diphtheriae. Our analysis shows that DtxR could provide a molecular link between Fe+2-induced Fenton's reaction and protection of DNA from oxidative damage. DtxR-regulated Dps prevents lethal combination of Fe+2 and H2O2 and also protects DNA by nonspecific DNA-binding. In addition DtxR could play an important role in host interaction and virulence by regulating the levels of sortase

  19. bHLH003, bHLH013 and bHLH017 are new targets of JAZ repressors negatively regulating JA responses.

    Directory of Open Access Journals (Sweden)

    Sandra Fonseca

    Full Text Available Cell reprogramming in response to jasmonates requires a tight control of transcription that is achieved by the activity of JA-related transcription factors (TFs. Among them, MYC2, MYC3 and MYC4 have been described as activators of JA responses. Here we characterized the function of bHLH003, bHLH013 and bHLH017 that conform a phylogenetic clade closely related to MYC2, MYC3 and MYC4. We found that these bHLHs form homo- and heterodimers and also interact with JAZ repressors in vitro and in vivo. Phenotypic analysis of JA-regulated processes, including root and rosette growth, anthocyanin accumulation, chlorophyll loss and resistance to Pseudomonas syringae, on mutants and overexpression lines, suggested that these bHLHs are repressors of JA responses. bHLH003, bHLH013 and bHLH017 are mainly nuclear proteins and bind DNA with similar specificity to that of MYC2, MYC3 and MYC4, but lack a conserved activation domain, suggesting that repression is achieved by competition for the same cis-regulatory elements. Moreover, expression of bHLH017 is induced by JA and depends on MYC2, suggesting a negative feed-back regulation of the activity of positive JA-related TFs. Our results suggest that the competition between positive and negative TFs determines the output of JA-dependent transcriptional activation.

  20. Cloning and characterization of the c1 repressor of Pseudomonas aeruginosa bacteriophage D3: a functional analog of phage lambda cI protein

    Energy Technology Data Exchange (ETDEWEB)

    Miller, R.V.; Kokjohn, T.A.

    1987-05-01

    We cloned the gene (c1) which encodes the repressor of vegetative function of Pseudomonas aeruginosa bacteriophage D3. The cloned gene was shown to inhibit plating of D3 and the induction of D3 lysogens by UV irradiation. The efficiency of plating and prophage induction of the heteroimmune P. aeruginosa phage F116L were not affected by the presence of the cloned c1 gene of D3. When the D3 DNA fragment containing c1 was subcloned into pBR322 and introduced into Escherichia coli, it was shown to specifically inhibit the plating of phage lambda and the induction of the lambda prophage by mitomycin C. The plating of lambda imm434 phage was not affected. Analysis in minicells indicated that these effects correspond to the presence of a plasmid-encoded protein of 36,000 molecular weight. These data suggest the possibility that coliphage lambda and the P. aeruginosa phage D3 evolved from a common ancestor. The conservation of the functional similarities of their repressors may have occurred because of the advantage to these temperate phages of capitalizing on the potential of the evolutionarily conserved RecA protein to monitor the level of damage to the host genome.

  1. Bacillus subtilis IolQ (DegA) is a transcriptional repressor of iolX encoding NAD+-dependent scyllo-inositol dehydrogenase.

    Science.gov (United States)

    Kang, Dong-Min; Michon, Christophe; Morinaga, Tetsuro; Tanaka, Kosei; Takenaka, Shinji; Ishikawa, Shu; Yoshida, Ken-Ichi

    2017-07-11

    Bacillus subtilis is able to utilize at least three inositol stereoisomers as carbon sources, myo-, scyllo-, and D-chiro-inositol (MI, SI, and DCI, respectively). NAD + -dependent SI dehydrogenase responsible for SI catabolism is encoded by iolX. Even in the absence of functional iolX, the presence of SI or MI in the growth medium was found to induce the transcription of iolX through an unknown mechanism. Immediately upstream of iolX, there is an operon that encodes two genes, yisR and iolQ (formerly known as degA), each of which could encode a transcriptional regulator. Here we performed an inactivation analysis of yisR and iolQ and found that iolQ encodes a repressor of the iolX transcription. The coding sequence of iolQ was expressed in Escherichia coli and the gene product was purified as a His-tagged fusion protein, which bound to two sites within the iolX promoter region in vitro. IolQ is a transcriptional repressor of iolX. Genetic evidences allowed us to speculate that SI and MI might possibly be the intracellular inducers, however they failed to antagonize DNA binding of IolQ in in vitro experiments.

  2. Cloning, expression, crystallization and preliminary X-ray analysis of a putative multiple antibiotic resistance repressor protein (MarR) from Xanthomonas campestris

    International Nuclear Information System (INIS)

    Tu, Zhi-Le; Li, Juo-Ning; Chin, Ko-Hsin; Chou, Chia-Cheng; Lee, Cheng-Chung; Shr, Hui-Lin; Lyu, Ping-Chiang; Gao, Fei Philip; Wang, Andrew H.-J.; Chou, Shan-Ho

    2005-01-01

    A putative repressor for the multiple antibiotic resistance operon from a plant pathogen X. campestris pv. campestris has been overexpressed in E. coli, purified and crystallized. The crystals diffracted to 2.3 Å with good quality. The multiple antibiotic resistance operon (marRAB) is a member of the multidrug-resistance system. When induced, this operon enhances resistance of bacteria to a variety of medically important antibiotics, causing a serious global health problem. MarR is a marR-encoded protein that represses the transcription of the marRAB operon. Through binding with salicylate and certain antibiotics, however, MarR can derepress and activate the marRAB operon. In this report, the cloning, expression, crystallization and preliminary X-ray analysis of XC1739, a putative MarR repressor protein present in the Xanthomonas campestris pv. campestris, a Gram-negative bacterium causing major worldwide disease of cruciferous crops, are described. The XC1739 crystals diffracted to a resolution of at least 1.8 Å. They are orthorhombic and belong to space group P2 1 2 1 2 1 , with unit-cell parameters a = 39.5, b = 54.2 and c = 139.5 Å, respectively. They contain two molecules in the asymmetric unit from calculation of the self-rotation function

  3. The co-repressor SMRT delays DNA damage-induced caspase activation by repressing pro-apoptotic genes and modulating the dynamics of checkpoint kinase 2 activation.

    Directory of Open Access Journals (Sweden)

    Claudio Scafoglio

    Full Text Available Checkpoint kinase 2 (Chk2 is a major regulator of DNA damage response and can induce alternative cellular responses: cell cycle arrest and DNA repair or programmed cell death. Here, we report the identification of a new role of Chk2 in transcriptional regulation that also contributes to modulating the balance between survival and apoptosis following DNA damage. We found that Chk2 interacts with members of the NCoR/SMRT transcriptional co-regulator complexes and serves as a functional component of the repressor complex, being required for recruitment of SMRT on the promoter of pro-apoptotic genes upon DNA damage. Thus, the co-repressor SMRT exerts a critical protective action against genotoxic stress-induced caspase activation, repressing a functionally important cohort of pro-apoptotic genes. Amongst them, SMRT is responsible for basal repression of Wip1, a phosphatase that de-phosphorylates and inactivates Chk2, thus affecting a feedback loop responsible for licensing the correct timing of Chk2 activation and the proper execution of the DNA repair process.

  4. Cloning and characterization of the c1 repressor of Pseudomonas aeruginosa bacteriophage D3: a functional analog of phage lambda cI protein

    International Nuclear Information System (INIS)

    Miller, R.V.; Kokjohn, T.A.

    1987-01-01

    We cloned the gene (c1) which encodes the repressor of vegetative function of Pseudomonas aeruginosa bacteriophage D3. The cloned gene was shown to inhibit plating of D3 and the induction of D3 lysogens by UV irradiation. The efficiency of plating and prophage induction of the heteroimmune P. aeruginosa phage F116L were not affected by the presence of the cloned c1 gene of D3. When the D3 DNA fragment containing c1 was subcloned into pBR322 and introduced into Escherichia coli, it was shown to specifically inhibit the plating of phage lambda and the induction of the lambda prophage by mitomycin C. The plating of lambda imm434 phage was not affected. Analysis in minicells indicated that these effects correspond to the presence of a plasmid-encoded protein of 36,000 molecular weight. These data suggest the possibility that coliphage lambda and the P. aeruginosa phage D3 evolved from a common ancestor. The conservation of the functional similarities of their repressors may have occurred because of the advantage to these temperate phages of capitalizing on the potential of the evolutionarily conserved RecA protein to monitor the level of damage to the host genome

  5. ATF3 mediates inhibitory effects of ethanol on hepatic gluconeogenesis.

    Science.gov (United States)

    Tsai, Wen-Wei; Matsumura, Shigenobu; Liu, Weiyi; Phillips, Naomi G; Sonntag, Tim; Hao, Ergeng; Lee, Soon; Hai, Tsonwin; Montminy, Marc

    2015-03-03

    Increases in circulating glucagon during fasting maintain glucose balance by stimulating hepatic gluconeogenesis. Acute ethanol intoxication promotes fasting hypoglycemia through an increase in hepatic NADH, which inhibits hepatic gluconeogenesis by reducing the conversion of lactate to pyruvate. Here we show that acute ethanol exposure also lowers fasting blood glucose concentrations by inhibiting the CREB-mediated activation of the gluconeogenic program in response to glucagon. Ethanol exposure blocked the recruitment of CREB and its coactivator CRTC2 to gluconeogenic promoters by up-regulating ATF3, a transcriptional repressor that also binds to cAMP-responsive elements and thereby down-regulates gluconeogenic genes. Targeted disruption of ATF3 decreased the effects of ethanol in fasted mice and in cultured hepatocytes. These results illustrate how the induction of transcription factors with overlapping specificity can lead to cross-coupling between stress and hormone-sensitive pathways.

  6. TALE-mediated modulation of transcriptional enhancers in vivo.

    Science.gov (United States)

    Crocker, Justin; Stern, David L

    2013-08-01

    We tested whether transcription activator-like effectors (TALEs) could mediate repression and activation of endogenous enhancers in the Drosophila genome. TALE repressors (TALERs) targeting each of the five even-skipped (eve) stripe enhancers generated repression specifically of the focal stripes. TALE activators (TALEAs) targeting the eve promoter or enhancers caused increased expression primarily in cells normally activated by the promoter or targeted enhancer, respectively. This effect supports the view that repression acts in a dominant fashion on transcriptional activators and that the activity state of an enhancer influences TALE binding or the ability of the VP16 domain to enhance transcription. In these assays, the Hairy repression domain did not exhibit previously described long-range transcriptional repression activity. The phenotypic effects of TALER and TALEA expression in larvae and adults are consistent with the observed modulations of eve expression. TALEs thus provide a novel tool for detection and functional modulation of transcriptional enhancers in their native genomic context.

  7. Mediatized play

    DEFF Research Database (Denmark)

    Johansen, Stine Liv

    Children’s play must nowadays be understood as a mediatized field in society and culture. Media – understood in a very broad sense - holds severe explanatory power in describing and understanding the practice of play, since play happens both with, through and inspired by media of different sorts........ In this presentation the case of ‘playing soccer’ will be outlined through its different mediated manifestations, including soccer games and programs on TV, computer games, magazines, books, YouTube videos and soccer trading cards....

  8. Mediating Business

    DEFF Research Database (Denmark)

    "Mediating Business" is a study of the expansion of business journalism. Building on evidence from Denmark, Finland, Norway and Sweden, "Mediating Business" is a comparative and multidisciplinary study of one of the major transformations of the mass media and the realm of business - nationally...... and globally. The book explores the history of key innovations and innovators in the business press. It analyzes changes in the discourse of business journalism associated with the growth in business news and the development of new ways of framing business issues and events. Finally, it examines...... the organizational implications of the increased media visibility of business and, in particular, the development of corporate governance and media relations....

  9. TRIM45 negatively regulates NF-κB-mediated transcription and suppresses cell proliferation

    International Nuclear Information System (INIS)

    Shibata, Mio; Sato, Tomonobu; Nukiwa, Ryota; Ariga, Tadashi; Hatakeyama, Shigetsugu

    2012-01-01

    Highlights: ► NF-κB plays an important role in cell survival and carcinogenesis. ► TRIM45 negatively regulates TNFα-induced NF-κB-mediated transcription. ► TRIM45 overexpression suppresses cell growth. ► TRIM45 acts as a repressor for the NF-κB signal and regulates cell growth. -- Abstract: The NF-κB signaling pathway plays an important role in cell survival, immunity, inflammation, carcinogenesis, and organogenesis. Activation of NF-κB is regulated by several posttranslational modifications including phosphorylation, neddylation and ubiquitination. The NF-κB signaling pathway is activated by two distinct signaling mechanisms and is strictly modulated by the ubiquitin–proteasome system. It has been reported that overexpression of TRIM45, one of the TRIM family ubiquitin ligases, suppresses transcriptional activities of Elk-1 and AP-1, which are targets of the MAPK signaling pathway. In this study, we showed that TRIM45 also negatively regulates TNFα-induced NF-κB-mediated transcription by a luciferase reporter assay and that TRIM45 lacking a RING domain also has an activity to inhibit the NF-κB signal. Moreover, we found that TRIM45 overexpression suppresses cell growth. These findings suggest that TRIM45 acts as a repressor for the NF-κB signal and regulates cell growth.

  10. Binding of the N-Terminal Domain of the Lactococcal Bacteriophage TP901-1 CI Repressor to Its Target DNA: A Crystallography, Small Angle Scattering, and Nuclear Magnetic Resonance Study

    DEFF Research Database (Denmark)

    Frandsen, Kristian Erik Høpfner; Rasmussen, Kim K.; Jensen, Malene Ringkjøbing

    2013-01-01

    In most temperate bacteriophages, regulation of the choice of lysogenic or lytic life cycle is controlled by a CI repressor protein. Inhibition of transcription is dependent on a helix–turn–helix motif, often located in the N-terminal domain (NTD), which binds to specific DNA sequences (operator ...

  11. Crystallization and preliminary X-ray analysis of BigR, a transcription repressor from Xylella fastidiosa involved in biofilm formation

    International Nuclear Information System (INIS)

    Barbosa, Rosicler Lázaro; Rinaldi, Fábio Cupri; Guimarães, Beatriz Gomes; Benedetti, Celso Eduardo

    2007-01-01

    In order to gain new insights into the protein structure and its possible interaction with a metal ion or effector ligand, BigR from X. fastidiosa was crystallized in native and selenomethionine (SeMet) labelled forms using the hanging-drop vapour-diffusion method. BigR (biofilm growth-associated repressor) is a novel repressor protein that regulates the transcription of an operon implicated in biofilm growth in both Xylella fastidiosa and Agrobacterium tumefaciens. This protein binds to a palindromic TA-rich element located in the promoter of the BigR operon and strongly represses transcription of the operon. BigR contains a helix–turn–helix (HTH) domain that is found in some members of the ArsR/SmtB family of metal sensors, which control metal resistance in bacteria. Although functional studies have suggested that BigR does not act as a metal sensor, the presence of two cysteines and a methionine in its primary structure raised the possibility of BigR being a metal-ligand protein. In order to gain new insights into the protein structure and its possible interaction with a metal ion or effector ligand, BigR from X. fastidiosa was crystallized in native and selenomethionine (SeMet) labelled forms using the hanging-drop vapour-diffusion method. X-ray diffraction data were collected from native and SeMet crystals to resolutions of 1.95 and 2.2 Å, respectively. Both crystals belong to space group P321 and contain one molecule per asymmetric unit

  12. Functional characterization of a cadmium resistance operon in Staphylococcus aureus ATCC12600: CadC does not function as a repressor.

    Science.gov (United States)

    Hoogewerf, Arlene J; Dyk, Lisa A Van; Buit, Tyler S; Roukema, David; Resseguie, Emily; Plaisier, Christina; Le, Nga; Heeringa, Lee; Griend, Douglas A Vander

    2015-02-01

    Sequencing of a cadmium resistance operon from a Staphylococcus aureus ATCC12600 plasmid revealed that it is identical to a cadCA operon found in MRSA strains. Compared to plasmid-cured and cadC-mutant strains, cadC-positive ATCC12600 cells had increased resistance to cadmium (1 mg ml(-1) cadmium sulfate) and zinc (4 mg ml(-1) zinc sulfate), but not to other metal ions. After growth in media containing 20 µg ml(-1) cadmium sulfate, cadC-mutant cells contained more intracellular cadmium than cadC-positive ATCC12600 cells, suggesting that cadC absence results in impaired cadmium efflux. Electrophoretic mobility shift assays were performed with CadC proteins encoded by the S. aureus ATCC12600 plasmid and by the cadC gene of pI258, which is known to act as a transcriptional repressor and shares only 47% protein sequence identity with ATCC12600 CadC. Mobility shifts occurred when pI258 CadC protein was incubated with the promoter DNA-regions from the pI258 and S. aureus ATCC12600 cadCA operons, but did not occur with S. aureus ATCC12600 CadC protein, indicating that the ATCC12600 CadC protein does not interact with promoter region DNA. This cadCA operon, found in MRSA strains and previously functionally uncharacterized, increases resistance to cadmium and zinc by an efflux mechanism, and CadC does not function as a transcriptional repressor. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Sequence-specific 1H NMR assignments and secondary structure of the Arc repressor of bacteriophage P22, as determined by two-dimensional 1H NMR spectroscopy

    International Nuclear Information System (INIS)

    Breg, J.N.; Boelens, R.; George, A.V.E.; Kaptein, R.

    1989-01-01

    The Arc repressor of bacteriophage P22 is a DNA binding protein that does not belong to any of the known classes of such proteins. The authors have undertaken a 1 H NMR study of the protein with the aim of elucidating its three-dimensional structure in solution and its mode of binding of operator DNA. Here the authors present the 1 H nuclear magnetic resonance (NMR) assignments of all backbone protons an most of the side-chain protons of Arc repressor. Elements of secondary structure have been identified on the basis of networks of characteristics sequential and medium-range nuclear Overhauser enhancements (NOEs). Two α-helical regions have been found in the peptide regions 16-29 and 35-45. The ends of the helices could not yet be firmly established and could extend to residue 31 for the first helix and to residue 49 for the second. Immediately before the first helix, between residues 8 and 14, a region is present with β-sheet characteristics dominated by a close proximity of the α-protons of residues 9 and 13. Because of the dimeric nature of the protein there are still two possible ways in which the NOEs in the β-sheet region can be interpreted. While the data presently do not allow an unambiguous choice between these two possibilities, some evidence is discussed that favors the latter (β-sheet between monomers). Since the N-terminal region of Arc is responsible for the sequence-specific recognition of its operator, the findings suggest the existence of a DNA binding motif in which a β-sheet region is present

  14. Crystallization and preliminary X-ray analysis of BigR, a transcription repressor from Xylella fastidiosa involved in biofilm formation

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Rosicler Lázaro; Rinaldi, Fábio Cupri; Guimarães, Beatriz Gomes, E-mail: beatriz@lnls.br; Benedetti, Celso Eduardo, E-mail: beatriz@lnls.br [Center for Molecular and Structural Biology, Brazilian Synchrotron Light Laboratory, Campinas, SP, CP 6192, CEP 13083-970 (Brazil)

    2007-07-01

    In order to gain new insights into the protein structure and its possible interaction with a metal ion or effector ligand, BigR from X. fastidiosa was crystallized in native and selenomethionine (SeMet) labelled forms using the hanging-drop vapour-diffusion method. BigR (biofilm growth-associated repressor) is a novel repressor protein that regulates the transcription of an operon implicated in biofilm growth in both Xylella fastidiosa and Agrobacterium tumefaciens. This protein binds to a palindromic TA-rich element located in the promoter of the BigR operon and strongly represses transcription of the operon. BigR contains a helix–turn–helix (HTH) domain that is found in some members of the ArsR/SmtB family of metal sensors, which control metal resistance in bacteria. Although functional studies have suggested that BigR does not act as a metal sensor, the presence of two cysteines and a methionine in its primary structure raised the possibility of BigR being a metal-ligand protein. In order to gain new insights into the protein structure and its possible interaction with a metal ion or effector ligand, BigR from X. fastidiosa was crystallized in native and selenomethionine (SeMet) labelled forms using the hanging-drop vapour-diffusion method. X-ray diffraction data were collected from native and SeMet crystals to resolutions of 1.95 and 2.2 Å, respectively. Both crystals belong to space group P321 and contain one molecule per asymmetric unit.

  15. THAP5 is a DNA-binding transcriptional repressor that is regulated in melanoma cells during DNA damage-induced cell death

    Energy Technology Data Exchange (ETDEWEB)

    Balakrishnan, Meenakshi P.; Cilenti, Lucia; Ambivero, Camilla [Biomolecular Science Center, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL (United States); Goto, Yamafumi [Department of Dermatology, Shinshu University School of Medicine, Matsumoto (Japan); Takata, Minoru [Department of Dermatology, Okayama University Graduate School of Medical Dentistry and Pharmaceutical Sciences, Okayama (Japan); Turkson, James; Li, Xiaoman Shawn [Biomolecular Science Center, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL (United States); Zervos, Antonis S., E-mail: azervos@mail.ucf.edu [Biomolecular Science Center, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL (United States)

    2011-01-07

    Research highlights: {yields} THAP5 is a DNA-binding protein and a transcriptional repressor. {yields} THAP5 is induced in melanoma cells upon exposure to UV or treatment with cisplatin. {yields} THAP5 induction correlates with the degree of apoptosis in melanoma cell population. {yields} THAP5 is a pro-apoptotic protein involved in melanoma cell death. -- Abstract: THAP5 was originally isolated as a specific interactor and substrate of the mitochondrial pro-apoptotic Omi/HtrA2 protease. It is a human zinc finger protein characterized by a restricted pattern of expression and the lack of orthologs in mouse and rat. The biological function of THAP5 is unknown but our previous studies suggest it could regulate G2/M transition in kidney cells and could be involved in human cardiomyocyte cell death associated with coronary artery disease (CAD). In this report, we expanded our studies on the properties and function of THAP5 in human melanoma cells. THAP5 was expressed in primary human melanocytes as well as in all melanoma cell lines that were tested. THAP5 protein level was significantly induced by UV irradiation or cisplatin treatment, conditions known to cause DNA damage. The induction of THAP5 correlated with a significant increase in apoptotic cell death. In addition, we show that THAP5 is a nuclear protein that could recognize and bind a specific DNA motif. THAP5 could also repress the transcription of a reporter gene in a heterologous system. Our work suggests that THAP5 is a DNA-binding protein and a transcriptional repressor. Furthermore, THAP5 has a pro-apoptotic function and it was induced in melanoma cells under conditions that promoted cell death.

  16. Overexpression of the novel MATE fluoroquinolone efflux pump FepA in Listeria monocytogenes is driven by inactivation of its local repressor FepR.

    Directory of Open Access Journals (Sweden)

    François Guérin

    Full Text Available Whereas fluoroquinolone resistance mainly results from target modifications in gram-positive bacteria, it is primarily due to active efflux in Listeria monocytogenes. The aim of this study was to dissect a novel molecular mechanism of fluoroquinolone resistance in this important human pathogen. Isogenic L. monocytogenes clinical isolates BM4715 and BM4716, respectively susceptible and resistant to fluoroquinolones, were studied. MICs of norfloxacin and ciprofloxacin were determined in the presence or in the absence of reserpine (10 mg/L. Strain BM4715 was susceptible to norfloxacin (MIC, 4 mg/L and ciprofloxacin (MIC, 0.5 mg/L whereas BM4716 was highly resistant to both drugs (MICs 128 and 32 mg/L, respectively. Reserpine was responsible for a 16-fold decrease in both norfloxacin and ciprofloxacin MICs against BM4716 suggesting efflux associated resistance. Whole-genome sequencing of the strains followed by comparative genomic analysis revealed a single point mutation in the gene for a transcriptional regulator, designated fepR (for fluoroquinolone efflux protein regulator belonging to the TetR family. The frame-shift mutation was responsible for the introduction of a premature stop codon resulting in an inactive truncated protein. Just downstream from fepR, the structural gene for an efflux pump of the MATE family (named FepA was identified. Gene expression was quantified by qRT-PCR and demonstrated that fepA expression was more than 64-fold higher in BM4716 than in BM4715. The clean deletion of the fepR gene from BM4715 was responsible for an overexpression of fepA with resistance to norfloxacin and ciprofloxacin, confirming the role of FepR as a local repressor of fepA. In conclusion, we demonstrated that overexpression of the new MATE efflux pump FepA is responsible for fluoroquinolone resistance in L. monocytogenes and secondary to inactivation of the FepR repressor.

  17. THAP5 is a DNA-binding transcriptional repressor that is regulated in melanoma cells during DNA damage-induced cell death

    International Nuclear Information System (INIS)

    Balakrishnan, Meenakshi P.; Cilenti, Lucia; Ambivero, Camilla; Goto, Yamafumi; Takata, Minoru; Turkson, James; Li, Xiaoman Shawn; Zervos, Antonis S.

    2011-01-01

    Research highlights: → THAP5 is a DNA-binding protein and a transcriptional repressor. → THAP5 is induced in melanoma cells upon exposure to UV or treatment with cisplatin. → THAP5 induction correlates with the degree of apoptosis in melanoma cell population. → THAP5 is a pro-apoptotic protein involved in melanoma cell death. -- Abstract: THAP5 was originally isolated as a specific interactor and substrate of the mitochondrial pro-apoptotic Omi/HtrA2 protease. It is a human zinc finger protein characterized by a restricted pattern of expression and the lack of orthologs in mouse and rat. The biological function of THAP5 is unknown but our previous studies suggest it could regulate G2/M transition in kidney cells and could be involved in human cardiomyocyte cell death associated with coronary artery disease (CAD). In this report, we expanded our studies on the properties and function of THAP5 in human melanoma cells. THAP5 was expressed in primary human melanocytes as well as in all melanoma cell lines that were tested. THAP5 protein level was significantly induced by UV irradiation or cisplatin treatment, conditions known to cause DNA damage. The induction of THAP5 correlated with a significant increase in apoptotic cell death. In addition, we show that THAP5 is a nuclear protein that could recognize and bind a specific DNA motif. THAP5 could also repress the transcription of a reporter gene in a heterologous system. Our work suggests that THAP5 is a DNA-binding protein and a transcriptional repressor. Furthermore, THAP5 has a pro-apoptotic function and it was induced in melanoma cells under conditions that promoted cell death.

  18. Heme-dependent up-regulation of the α-globin gene expression by transcriptional repressor Bach1 in erythroid cells

    International Nuclear Information System (INIS)

    Tahara, Tsuyoshi; Sun Jiying; Igarashi, Kazuhiko; Taketani, Shigeru

    2004-01-01

    The transcriptional factor Bach1 forms a heterodimer with small Maf family, and functions as a repressor of the Maf recognition element (MARE) in vivo. To investigate the involvement of Bach1 in the heme-dependent regulation of the expression of the α-globin gene, human erythroleukemia K562 cells were cultured with succinylacetone (SA), a heme biosynthetic inhibitor, and the level of α-globin mRNA was examined. A decrease of α-globin mRNA was observed in SA-treated cells, which was restored by the addition of hemin. The heme-dependent expression of α-globin occurred at the transcriptional level since the expression of human α-globin gene promoter-reporter gene containing hypersensitive site-40 (HS-40) was decreased when K562 cells were cultured with SA. Hemin treatment restored the decrease of the promoter activity by SA. The regulation of the HS-40 activity by heme was dependent on the NF-E2/AP-1 (NA) site, which is similar to MARE. The NA site-binding activity of Bach1 in K562 increased upon SA-treatment, and the increase was diminished by the addition of hemin. The transient expression of Bach1 and mutated Bach1 lacking CP motifs suppressed the HS-40 activity, and cancellation of the repressor activity by hemin was observed when wild-type Bach1 was expressed. The expression of NF-E2 strengthened the restoration of the Bach1-effect by hemin. Interestingly, nuclear localization of Bach1 increased when cells were treated with SA, while hemin induced the nuclear export of Bach1. These results indicated that heme plays an important role in the induction of α-globin gene expression through disrupting the interaction of Bach1 and the NA site in HS-40 enhancer in erythroid cells

  19. Complementary Gli activity mediates early patterning of the mouse visual system.

    Science.gov (United States)

    Furimsky, Marosh; Wallace, Valerie A

    2006-03-01

    The Sonic hedgehog (Shh) signaling pathway plays a key role in the development of the vertebrate central nervous system, including the eye. This pathway is mediated by the Gli transcription factors (Gli1, Gli2, and Gli3) that differentially activate and repress the expression of specific downstream target genes. In this study, we investigated the roles of the three vertebrate Glis in mediating midline Shh signaling in early ocular development. We examined the ocular phenotypes of Shh and Gli combination mutant mouse embryos and monitored proximodistal and dorsoventral patterning by the expression of specific eye development regulatory genes using in situ hybridization. We show that midline Shh signaling relieves the repressor activity of Gli3 adjacent to the midline and then promotes eye pattern formation through the nonredundant activities of all three Gli proteins. Gli3, in particular, is required to specify the dorsal optic stalk and to define the boundary between the optic stalk and the optic cup.

  20. Prophage Rs551 and Its Repressor Gene orf14 Reduce Virulence and Increase Competitive Fitness of Its Ralstonia solanacearum Carrier Strain UW551.

    Science.gov (United States)

    Ahmad, Abdelmonim Ali; Stulberg, Michael J; Huang, Qi

    2017-01-01

    We previously characterized a filamentous lysogenic bacteriophage, ϕRs551, isolated directly from the race 3 biovar 2 phylotype IIB sequevar 1 strain UW551 of Ralstonia solanacearum grown under normal culture conditions. The genome of ϕRs551 was identified with 100% identity in the deposited genomes of 11 race 3 biovar 2 phylotype IIB sequevar 1 strains of R. solanacearum , indicating evolutionary and biological importance, and ORF14 of ϕRs551 was annotated as a putative type-2 repressor. In this study, we determined the effect of the prophage and its ORF14 on the virulence and competitive fitness of its carrier strain UW551 by deleting the orf14 gene only (the UW551 orf14 mutant), and nine of the prophage's 14 genes including orf14 and six out of seven structural genes (the UW551 prophage mutant), respectively, from the genome of UW551. The two mutants were increased in extracellular polysaccharide production, twitching motility, expression of targeted virulence and virulence regulatory genes ( pilT, egl, pehC, hrPB, and phcA ), and virulence, suggesting that the virulence of UW551 was negatively regulated by ϕRs551, at least partially through ORF14. Interestingly, we found that the wt ϕRs551-carrying strain UW551 of R. solanacearum significantly outcompeted the wt strain RUN302 which lacks the prophage in tomato plants co-inoculated with the two strains. When each of the two mutant strains was co-inoculated with RUN302, however, the mutants were significantly out-competed by RUN302 for the same colonization site. Our results suggest that ecologically, ϕRs551 may play an important role by regulating the virulence of and offering a competitive fitness advantage to its carrier bacterial strain for persistence of the bacterium in the environment, which in turn prolongs the symbiotic relationship between the phage ϕRs551 and the R. solanacearum strain UW551. Our study is the first toward a better understanding of the co-existence between a lysogenic phage and

  1. Prophage Rs551 and Its Repressor Gene orf14 Reduce Virulence and Increase Competitive Fitness of Its Ralstonia solanacearum Carrier Strain UW551

    Directory of Open Access Journals (Sweden)

    Abdelmonim Ali Ahmad

    2017-12-01

    Full Text Available We previously characterized a filamentous lysogenic bacteriophage, ϕRs551, isolated directly from the race 3 biovar 2 phylotype IIB sequevar 1 strain UW551 of Ralstonia solanacearum grown under normal culture conditions. The genome of ϕRs551 was identified with 100% identity in the deposited genomes of 11 race 3 biovar 2 phylotype IIB sequevar 1 strains of R. solanacearum, indicating evolutionary and biological importance, and ORF14 of ϕRs551 was annotated as a putative type-2 repressor. In this study, we determined the effect of the prophage and its ORF14 on the virulence and competitive fitness of its carrier strain UW551 by deleting the orf14 gene only (the UW551 orf14 mutant, and nine of the prophage’s 14 genes including orf14 and six out of seven structural genes (the UW551 prophage mutant, respectively, from the genome of UW551. The two mutants were increased in extracellular polysaccharide production, twitching motility, expression of targeted virulence and virulence regulatory genes (pilT, egl, pehC, hrPB, and phcA, and virulence, suggesting that the virulence of UW551 was negatively regulated by ϕRs551, at least partially through ORF14. Interestingly, we found that the wt ϕRs551-carrying strain UW551 of R. solanacearum significantly outcompeted the wt strain RUN302 which lacks the prophage in tomato plants co-inoculated with the two strains. When each of the two mutant strains was co-inoculated with RUN302, however, the mutants were significantly out-competed by RUN302 for the same colonization site. Our results suggest that ecologically, ϕRs551 may play an important role by regulating the virulence of and offering a competitive fitness advantage to its carrier bacterial strain for persistence of the bacterium in the environment, which in turn prolongs the symbiotic relationship between the phage ϕRs551 and the R. solanacearum strain UW551. Our study is the first toward a better understanding of the co-existence between a

  2. Prophage Rs551 and Its Repressor Gene orf14 Reduce Virulence and Increase Competitive Fitness of Its Ralstonia solanacearum Carrier Strain UW551

    Science.gov (United States)

    Ahmad, Abdelmonim Ali; Stulberg, Michael J.; Huang, Qi

    2017-01-01

    We previously characterized a filamentous lysogenic bacteriophage, ϕRs551, isolated directly from the race 3 biovar 2 phylotype IIB sequevar 1 strain UW551 of Ralstonia solanacearum grown under normal culture conditions. The genome of ϕRs551 was identified with 100% identity in the deposited genomes of 11 race 3 biovar 2 phylotype IIB sequevar 1 strains of R. solanacearum, indicating evolutionary and biological importance, and ORF14 of ϕRs551 was annotated as a putative type-2 repressor. In this study, we determined the effect of the prophage and its ORF14 on the virulence and competitive fitness of its carrier strain UW551 by deleting the orf14 gene only (the UW551 orf14 mutant), and nine of the prophage’s 14 genes including orf14 and six out of seven structural genes (the UW551 prophage mutant), respectively, from the genome of UW551. The two mutants were increased in extracellular polysaccharide production, twitching motility, expression of targeted virulence and virulence regulatory genes (pilT, egl, pehC, hrPB, and phcA), and virulence, suggesting that the virulence of UW551 was negatively regulated by ϕRs551, at least partially through ORF14. Interestingly, we found that the wt ϕRs551-carrying strain UW551 of R. solanacearum significantly outcompeted the wt strain RUN302 which lacks the prophage in tomato plants co-inoculated with the two strains. When each of the two mutant strains was co-inoculated with RUN302, however, the mutants were significantly out-competed by RUN302 for the same colonization site. Our results suggest that ecologically, ϕRs551 may play an important role by regulating the virulence of and offering a competitive fitness advantage to its carrier bacterial strain for persistence of the bacterium in the environment, which in turn prolongs the symbiotic relationship between the phage ϕRs551 and the R. solanacearum strain UW551. Our study is the first toward a better understanding of the co-existence between a lysogenic phage and

  3. 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.

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

    International Nuclear Information System (INIS)

    Han, Eun Hee; Gorman, Amanda A.; Singh, Puja; Chi, Young-In

    2015-01-01

    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.

  5. GLI1, a crucial mediator of sonic hedgehog signaling in prostate cancer, functions as a negative modulator for androgen receptor

    International Nuclear Information System (INIS)

    Chen, Guangchun; Goto, Yutaka; Sakamoto, Ryuichi; Tanaka, Kimitaka; Matsubara, Eri; Nakamura, Masafumi; Zheng, Hong; Lu, Jian; Takayanagi, Ryoichi; Nomura, Masatoshi

    2011-01-01

    Research highlights: → GLI1, which play a central role in sonic hedgehog signaling in prostate cancer, can act as a co-repressor to substantially block androgen receptor-mediated transactivation. → GLI1 directly interacts with AR. → SHH-GLI pathway might be one of determinants governing the transition of prostate cancer from an androgen-dependent to an androgen-independent state. -- Abstract: Sonic hedgehog (SHH) signaling, acting in a combinatorial manner with androgen signaling, is essential for prostate patterning and development. Recently, elevated activation of SHH signaling has been shown to play important roles in proliferation, progression and metastasis of prostate cancer. In this report, we demonstrate for the first time, that GLI1, which has been shown to play a central role in SHH signaling in prostate cancer, can act as a co-repressor to substantially block androgen receptor (AR)-mediated transactivation, at least in part, by directly interacting with AR. Our observations suggest that the SHH-GLI pathway might be one of determinants governing the transition of prostate cancer from an androgen-dependent to an androgen-independent state by compensating, or even superseding androgen signaling.

  6. Osteogenic differentiation of mouse mesenchymal progenitor cell, Kusa-A1 is promoted by mammalian transcriptional repressor Rbpj

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shengchao [Department of Preventive Dentistry, School of Stomatology, The Fourth Military Medical University, 145 West Changle Road, 710032 Xi' an (China); Kawashima, Nobuyuki, E-mail: kawashima.n.endo@tmd.ac.jp [Department of Pulp Biology and Endodontics, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549 (Japan); Sakamoto, Kei; Katsube, Ken-ichi [Department of Oral Pathology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549 (Japan); Umezawa, Akihiro [Department of Reproductive Biology and Pathology, National Institute for Child Health and Development, 2-10-4 Ohkura, Setagaya-ku, Tokyo 157-8535 (Japan); Suda, Hideaki [Department of Pulp Biology and Endodontics, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549 (Japan); GCOE Program, International Research Center for Molecular Science in Tooth and Bone Diseases, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549 (Japan)

    2010-09-10

    Research highlights: {yields} High Rbpj mRNA expression was observed in mesenchymal cells surrounding the bone of mouse embryos. {yields} Overexpression of Rbpj depressed Notch-Hes1/Hey1 signaling. {yields} Rbpj upregulated promoter activities of Runx2 and Ose2. {yields} Rbpj promoted osteoblastic differentiation/maturation in Kusa-A1 cells. -- Abstract: Pluripotent mesenchymal stem cells possess the ability to differentiate into many cell types, but the precise mechanisms of differentiation are still unclear. Here, we provide evidence that Rbpj (recombination signal-binding protein for immunoglobulin kappa j region) protein, the primary nuclear mediator of Notch, is involved in osteogenesis. Overexpression of Rbpj promoted osteogenic differentiation of mouse Kusa-A1 cells in vitro and in vivo. Transient transfection of an Rbpj expression vector into Kusa-A1 cells upregulated promoter activities of Runx2 and Ose2. Enhanced osteogenic potentials including high alkaline phosphatase activity, rapid calcium deposition, and increased calcified nodule formation, were observed in established stable Rbpj-overexpressing Kusa-A1 (Kusa-A1/Rbpj) cell line. In vivo mineralization by Kusa-A1/Rbpj was promoted compared to that by Kusa-A1 host cells. Histological findings revealed that expression of Rbpj was primarily observed in osteoblasts. These results suggest that Rbpj may play essential roles in osteoblast differentiation.

  7. Osteogenic differentiation of mouse mesenchymal progenitor cell, Kusa-A1 is promoted by mammalian transcriptional repressor Rbpj

    International Nuclear Information System (INIS)

    Wang, Shengchao; Kawashima, Nobuyuki; Sakamoto, Kei; Katsube, Ken-ichi; Umezawa, Akihiro; Suda, Hideaki

    2010-01-01

    Research highlights: → High Rbpj mRNA expression was observed in mesenchymal cells surrounding the bone of mouse embryos. → Overexpression of Rbpj depressed Notch-Hes1/Hey1 signaling. → Rbpj upregulated promoter activities of Runx2 and Ose2. → Rbpj promoted osteoblastic differentiation/maturation in Kusa-A1 cells. -- Abstract: Pluripotent mesenchymal stem cells possess the ability to differentiate into many cell types, but the precise mechanisms of differentiation are still unclear. Here, we provide evidence that Rbpj (recombination signal-binding protein for immunoglobulin kappa j region) protein, the primary nuclear mediator of Notch, is involved in osteogenesis. Overexpression of Rbpj promoted osteogenic differentiation of mouse Kusa-A1 cells in vitro and in vivo. Transient transfection of an Rbpj expression vector into Kusa-A1 cells upregulated promoter activities of Runx2 and Ose2. Enhanced osteogenic potentials including high alkaline phosphatase activity, rapid calcium deposition, and increased calcified nodule formation, were observed in established stable Rbpj-overexpressing Kusa-A1 (Kusa-A1/Rbpj) cell line. In vivo mineralization by Kusa-A1/Rbpj was promoted compared to that by Kusa-A1 host cells. Histological findings revealed that expression of Rbpj was primarily observed in osteoblasts. These results suggest that Rbpj may play essential roles in osteoblast differentiation.

  8. Crystal structures of the transcriptional repressor RolR reveals a novel recognition mechanism between inducer and regulator.

    Directory of Open Access Journals (Sweden)

    De-Feng Li

    Full Text Available Many members of the TetR family control the transcription of genes involved in multidrug resistance and pathogenicity. RolR (ResorcinolRegulator, the recently reported TetR-type regulator for aromatic catabolism from Corynebacterium glutamicum, distinguishes itself by low sequence similarities and different regulation from the previously known members of the TetR family. Here we report the crystal structures of RolR in its effector-bound (with resorcinol and aop- forms at 2.5 Å and 3.6 Å, respectively. The structure of resorcinol-RolR complex reveal that the hydrogen-bonded network mediated by the four-residue motif (Asp94- Arg145- Arg148- Asp149 with two water molecules and the hydrophobic interaction via five residues (Phe107, Leu111, Leu114, Leu142, and Phe172 are the key factors for the recognition and binding between the resorcinol and RolR molecules. The center-to-center separation of the recognition helices h3-h3' is decreased upon effector-binding from 34.9 Å to 30.4 Å. This structural change results in that RolR was unsuitable for DNA binding. Those observations are distinct from that in other TetR members. Structure-based mutagenesis on RolR was carried out and the results confirmed the critical roles of the above mentioned residues for effector-binding specificity and affinity. Similar sequence searches and sequence alignments identified 29 RolR homologues from GenBank, and all the above mentioned residues are highly conserved in the homologues. Based on these structural and other functional investigations, it is proposed that RolR may represent a new subfamily of TetR proteins that are invovled in aromatic degradation and sharing common recognition mode as for RolR.

  9. The Transcriptional Repressor MYB2 Regulates Both Spatial and Temporal Patterns of Proanthocyandin and Anthocyanin Pigmentation in Medicago truncatula[OPEN

    Science.gov (United States)

    2015-01-01

    Accumulation of anthocyanins and proanthocyanidins (PAs) is limited to specific cell types and developmental stages, but little is known about how antagonistically acting transcriptional regulators work together to determine temporal and spatial patterning of pigmentation at the cellular level, especially for PAs. Here, we characterize MYB2, a transcriptional repressor regulating both anthocyanin and PA biosynthesis in the model legume Medicago truncatula. MYB2 was strongly upregulated by MYB5, a major regulator of PA biosynthesis in M. truncatula and a component of MYB-basic helix loop helix-WD40 (MBW) activator complexes. Overexpression of MYB2 abolished anthocyanin and PA accumulation in M. truncatula hairy roots and Arabidopsis thaliana seeds, respectively. Anthocyanin deposition was expanded in myb2 mutant seedlings and flowers accompanied by increased anthocyanin content. PA mainly accumulated in the epidermal layer derived from the outer integument in the M. truncatula seed coat, starting from the hilum area. The area of PA accumulation and ANTHOCYANIDIN REDUCTASE expression was expanded into the seed body at the early stage of seed development in the myb2 mutant. Genetic, biochemical, and cell biological evidence suggests that MYB2 functions as part of a multidimensional regulatory network to define the temporal and spatial pattern of anthocyanin and PA accumulation linked to developmental processes. PMID:26410301

  10. Sestrin-2, a repressor of PDGFRβ signalling, promotes cigarette-smoke-induced pulmonary emphysema in mice and is upregulated in individuals with COPD

    Science.gov (United States)

    Heidler, Juliana; Fysikopoulos, Athanasios; Wempe, Frank; Seimetz, Michael; Bangsow, Thorsten; Tomasovic, Ana; Veit, Florian; Scheibe, Susan; Pichl, Alexandra; Weisel, Friederike; Lloyd, K. C. Kent; Jaksch, Peter; Klepetko, Walter; Weissmann, Norbert; von Melchner, Harald

    2013-01-01

    SUMMARY Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide. COPD is caused by chronic exposure to cigarette smoke and/or other environmental pollutants that are believed to induce reactive oxygen species (ROS) that gradually disrupt signalling pathways responsible for maintaining lung integrity. Here we identify the antioxidant protein sestrin-2 (SESN2) as a repressor of PDGFRβ signalling, and PDGFRβ signalling as an upstream regulator of alveolar maintenance programmes. In mice, the mutational inactivation of Sesn2 prevents the development of cigarette-smoke-induced pulmonary emphysema by upregulating PDGFRβ expression via a selective accumulation of intracellular superoxide anions (O2−). We also show that SESN2 is overexpressed and PDGFRβ downregulated in the emphysematous lungs of individuals with COPD and to a lesser extent in human lungs of habitual smokers without COPD, implicating a negative SESN2-PDGFRβ interrelationship in the pathogenesis of COPD. Taken together, our results imply that SESN2 could serve as both a biomarker and as a drug target in the clinical management of COPD. PMID:24046361

  11. Haploinsufficiency of MeCP2-interacting transcriptional co-repressor SIN3A causes mild intellectual disability by affecting the development of cortical integrity.

    Science.gov (United States)

    Witteveen, Josefine S; Willemsen, Marjolein H; Dombroski, Thaís C D; van Bakel, Nick H M; Nillesen, Willy M; van Hulten, Josephus A; Jansen, Eric J R; Verkaik, Dave; Veenstra-Knol, Hermine E; van Ravenswaaij-Arts, Conny M A; Wassink-Ruiter, Jolien S Klein; Vincent, Marie; David, Albert; Le Caignec, Cedric; Schieving, Jolanda; Gilissen, Christian; Foulds, Nicola; Rump, Patrick; Strom, Tim; Cremer, Kirsten; Zink, Alexander M; Engels, Hartmut; de Munnik, Sonja A; Visser, Jasper E; Brunner, Han G; Martens, Gerard J M; Pfundt, Rolph; Kleefstra, Tjitske; Kolk, Sharon M

    2016-08-01

    Numerous genes are associated with neurodevelopmental disorders such as intellectual disability and autism spectrum disorder (ASD), but their dysfunction is often poorly characterized. Here we identified dominant mutations in the gene encoding the transcriptional repressor and MeCP2 interactor switch-insensitive 3 family member A (SIN3A; chromosome 15q24.2) in individuals who, in addition to mild intellectual disability and ASD, share striking features, including facial dysmorphisms, microcephaly and short stature. This phenotype is highly related to that of individuals with atypical 15q24 microdeletions, linking SIN3A to this microdeletion syndrome. Brain magnetic resonance imaging showed subtle abnormalities, including corpus callosum hypoplasia and ventriculomegaly. Intriguingly, in vivo functional knockdown of Sin3a led to reduced cortical neurogenesis, altered neuronal identity and aberrant corticocortical projections in the developing mouse brain. Together, our data establish that haploinsufficiency of SIN3A is associated with mild syndromic intellectual disability and that SIN3A can be considered to be a key transcriptional regulator of cortical brain development.

  12. Lymphoid Progenitor Cells from Childhood Acute Lymphoblastic Leukemia Are Functionally Deficient and Express High Levels of the Transcriptional Repressor Gfi-1

    Directory of Open Access Journals (Sweden)

    Jessica Purizaca

    2013-01-01

    Full Text Available Acute lymphoblastic leukemia (ALL is the most frequent malignancy of childhood. Substantial progress on understanding the cell hierarchy within ALL bone marrow (BM has been recorded in the last few years, suggesting that both primitive cell fractions and committed lymphoid blasts with immature stem cell-like properties contain leukemia-initiating cells. Nevertheless, the biology of the early progenitors that initiate the lymphoid program remains elusive. The aim of the present study was to investigate the ability of lymphoid progenitors from B-cell precursor ALL BM to proliferate and undergo multilineage differentiation. By phenotype analyses, in vitro proliferation assays, and controlled culture systems, the lymphoid differentiation potentials were evaluated in BM primitive populations from B-cell precursor ALL pediatric patients. When compared to their normal counterparts, functional stem and progenitor cell contents were substantially reduced in ALL BM. Moreover, neither B nor NK or dendritic lymphoid-cell populations developed recurrently from highly purified ALL-lymphoid progenitors, and their proliferation and cell cycle status revealed limited proliferative capacity. Interestingly, a number of quiescence-associated transcription factors were elevated, including the transcriptional repressor Gfi-1, which was highly expressed in primitive CD34+ cells. Together, our findings reveal major functional defects in the primitive hematopoietic component of ALL BM. A possible contribution of high levels of Gfi-1 expression in the regulation of the stem/progenitor cell biology is suggested.

  13. Regulation of MntH by a dual Mn(II- and Fe(II-dependent transcriptional repressor (DR2539 in Deinococcus radiodurans.

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    Hongxing Sun

    Full Text Available The high intracellular Mn/Fe ratio observed within the bacteria Deinococcus radiodurans may contribute to its remarkable resistance to environmental stresses. We isolated DR2539, a novel regulator of intracellular Mn/Fe homeostasis in D. radiodurans. Electrophoretic gel mobility shift assays (EMSAs revealed that DR2539 binds specifically to the promoter of the manganese acquisition transporter (MntH gene, and that DR0865, the only Fur homologue in D. radiodurans, cannot bind to the promoter of mntH, but it can bind to the promoter of another manganese acquisition transporter, MntABC. β-galactosidase expression analysis indicated that DR2539 acts as a manganese- and iron-dependent transcriptional repressor. Further sequence alignment analysis revealed that DR2539 has evolved some special characteristics. Site-directed mutagenesis suggested that His98 plays an important role in the activities of DR2539, and further protein-DNA binding activity assays showed that the activity of H98Y mutants decreased dramatically relative to wild type DR2539. Our study suggests that D. radiodurans has evolved a very efficient manganese regulation mechanism that involves its high intracellular Mn/Fe ratio and permits resistance to extreme conditions.

  14. Comparative analysis of chromatin binding by Sex Comb on Midleg (SCM) and other polycomb group repressors at a Drosophila Hox gene.

    Science.gov (United States)

    Wang, Liangjun; Jahren, Neal; Miller, Ellen L; Ketel, Carrie S; Mallin, Daniel R; Simon, Jeffrey A

    2010-06-01

    Sex Comb on Midleg (SCM) is a transcriptional repressor in the Polycomb group (PcG), but its molecular role in PcG silencing is not known. Although SCM can interact with Polycomb repressive complex 1 (PRC1) in vitro, biochemical studies have indicated that SCM is not a core constituent of PRC1 or PRC2. Nevertheless, SCM is just as critical for Drosophila Hox gene silencing as canonical subunits of these well-characterized PcG complexes. To address functional relationships between SCM and other PcG components, we have performed chromatin immunoprecipitation studies using cultured Drosophila Schneider line 2 (S2) cells and larval imaginal discs. We find that SCM associates with a Polycomb response element (PRE) upstream of the Ubx gene which also binds PRC1, PRC2, and the DNA-binding PcG protein Pleiohomeotic (PHO). However, SCM is retained at this Ubx PRE despite genetic disruption or knockdown of PHO, PRC1, or PRC2, suggesting that SCM chromatin targeting does not require prior association of these other PcG components. Chromatin immunoprecipitations (IPs) to test the consequences of SCM genetic disruption or knockdown revealed that PHO association is unaffected, but reduced levels of PRE-bound PRC2 and PRC1 were observed. We discuss these results in light of current models for recruitment of PcG complexes to chromatin targets.

  15. Comparative Analysis of Chromatin Binding by Sex Comb on Midleg (SCM) and Other Polycomb Group Repressors at a Drosophila Hox Gene▿

    Science.gov (United States)

    Wang, Liangjun; Jahren, Neal; Miller, Ellen L.; Ketel, Carrie S.; Mallin, Daniel R.; Simon, Jeffrey A.

    2010-01-01

    Sex Comb on Midleg (SCM) is a transcriptional repressor in the Polycomb group (PcG), but its molecular role in PcG silencing is not known. Although SCM can interact with Polycomb repressive complex 1 (PRC1) in vitro, biochemical studies have indicated that SCM is not a core constituent of PRC1 or PRC2. Nevertheless, SCM is just as critical for Drosophila Hox gene silencing as canonical subunits of these well-characterized PcG complexes. To address functional relationships between SCM and other PcG components, we have performed chromatin immunoprecipitation studies using cultured Drosophila Schneider line 2 (S2) cells and larval imaginal discs. We find that SCM associates with a Polycomb response element (PRE) upstream of the Ubx gene which also binds PRC1, PRC2, and the DNA-binding PcG protein Pleiohomeotic (PHO). However, SCM is retained at this Ubx PRE despite genetic disruption or knockdown of PHO, PRC1, or PRC2, suggesting that SCM chromatin targeting does not require prior association of these other PcG components. Chromatin immunoprecipitations (IPs) to test the consequences of SCM genetic disruption or knockdown revealed that PHO association is unaffected, but reduced levels of PRE-bound PRC2 and PRC1 were observed. We discuss these results in light of current models for recruitment of PcG complexes to chromatin targets. PMID:20351181

  16. In vivo estradiol-dependent dephosphorylation of the repressor MDBP-2-H1 correlates with the loss of in vitro preferential binding to methylated DNA.

    Science.gov (United States)

    Bruhat, A; Jost, J P

    1995-01-01

    We have previously shown that estradiol treatment of roosters resulted in a rapid loss of binding activity of the repressor MDBP-2-H1 (a member of the histone H1 family) to methylated DNA that was not due to a decrease in MDBP-2-H1 concentration. Here we demonstrate that MDBP-2-H1 from rooster liver nuclear extracts is a phosphoprotein. Phosphoamino acid analysis reveals that the phosphorylation occurs exclusively on serine residues. Two-dimensional gel electrophoresis and tryptic phosphopeptide analysis show that MDBP-2-H1 is phosphorylated at several sites. Treatment of roosters with estradiol triggers a dephosphorylation of at least two sites in the protein. Phosphatase treatment of purified rooster MDBP-2-H1 combined with gel mobility shift assay indicates that phosphorylation of MDBP-2-H1 is essential for the binding to methylated DNA and that the dephosphorylation can occur on the protein bound to methylated DNA causing its release from DNA. Thus, these results suggest that in vivo modification of the phosphorylation status of MDBP-2-H1 caused by estradiol treatment may be a key step for the down regulation of its binding to methylated DNA. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 PMID:7731964

  17. Tunable Control of an Escherichia coli Expression System for the Overproduction of Membrane Proteins by Titrated Expression of a Mutant lac Repressor.

    Science.gov (United States)

    Kim, Seong Keun; Lee, Dae-Hee; Kim, Oh Cheol; Kim, Jihyun F; Yoon, Sung Ho

    2017-09-15

    Most inducible expression systems suffer from growth defects, leaky basal induction, and inhomogeneous expression levels within a host cell population. These difficulties are most prominent with the overproduction of membrane proteins that are toxic to host cells. Here, we developed an Escherichia coli inducible expression system for membrane protein production based on titrated expression of a mutant lac repressor (mLacI). Performance of the mLacI inducible system was evaluated in conjunction with commonly used lac operator-based expression vectors using a T7 or tac promoter. Remarkably, expression of a target gene can be titrated by the dose-dependent addition of l-rhamnose, and the expression levels were homogeneous in the cell population. The developed system was successfully applied to overexpress three membrane proteins that were otherwise difficult to produce in E. coli. This gene expression control system can be easily applied to a broad range of existing protein expression systems and should be useful in constructing genetic circuits that require precise output signals.

  18. Cellular repressor of E1A-stimulated genes is a bona fide lysosomal protein which undergoes proteolytic maturation during its biosynthesis

    International Nuclear Information System (INIS)

    Schaehs, Philipp; Weidinger, Petra; Probst, Olivia C.; Svoboda, Barbara; Stadlmann, Johannes; Beug, Hartmut; Waerner, Thomas; Mach, Lukas

    2008-01-01

    Cellular repressor of E1A-stimulated genes (CREG) has been reported to be a secretory glycoprotein implicated in cellular growth and differentiation. We now show that CREG is predominantly localized within intracellular compartments. Intracellular CREG was found to lack an N-terminal peptide present in the secreted form of the protein. In contrast to normal cells, CREG is largely secreted by fibroblasts missing both mannose 6-phosphate receptors. This is not observed in cells lacking only one of them. Mass spectrometric analysis of recombinant CREG revealed that the protein contains phosphorylated oligosaccharides at either of its two N-glycosylation sites. Cellular CREG was found to cosediment with lysosomal markers upon subcellular fractionation by density-gradient centrifugation. In fibroblasts expressing a CREG-GFP fusion construct, the heterologous protein was detected in compartments containing lysosomal proteins. Immunolocalization of endogenous CREG confirmed that intracellular CREG is localized in lysosomes. Proteolytic processing of intracellular CREG involves the action of lysosomal cysteine proteinases. These results establish that CREG is a lysosomal protein that undergoes proteolytic maturation in the course of its biosynthesis, carries the mannose 6-phosphate recognition marker and depends on the interaction with mannose 6-phosphate receptors for efficient delivery to lysosomes

  19. ATM-mediated Snail Serine 100 phosphorylation regulates cellular radiosensitivity

    International Nuclear Information System (INIS)

    Boohaker, Rebecca J.; Cui, Xiaoli; Stackhouse, Murray; Xu, Bo

    2013-01-01

    Purpose: Activation of the DNA damage responsive protein kinase ATM is a critical step for cellular survival in response to ionizing irradiation (IR). Direct targets of ATM regulating radiosensitivity remain to be fully investigated. We have recently reported that ATM phosphorylates the transcriptional repressor Snail on Serine 100. We aimed to further study the functional significance of ATM-mediated Snail phosphorylation in response to IR. Material and methods: We transfected vector-only, wild-type, the Serine 100 to alanine (S100A) or to glutamic acid (S100E) substitution of Snail into various cell lines. We assessed colony formation, γ-H2AX focus formation and the invasion index in the cells treated with or without IR. Results: We found that over-expression of the S100A mutant Snail in HeLa cells significantly increased radiosensitivity. Meanwhile the expression of S100E, a phospho-mimicking mutation, resulted in enhanced radio-resistance. Interestingly, S100E could rescue the radiosensitive phenotype in ATM-deficient cells. We also found that expression of S100E increased γ-H2AX focus formation and compromised inhibition of invasion in response to IR independent of cell survival. Conclusion: ATM-mediated Snail Serine 100 phosphorylation in response to IR plays an important part in the regulation of radiosensitivity

  20. mediation: R package for causal mediation analysis

    OpenAIRE

    Tingley, Dustin; Yamamoto, Teppei; Hirose, Kentaro; Keele, Luke; Imai, Kosuke

    2012-01-01

    In this paper, we describe the R package mediation for conducting causal mediation analysis in applied empirical research. In many scientific disciplines, the goal of researchers is not only estimating causal effects of a treatment but also understanding the process in which the treatment causally affects the outcome. Causal mediation analysis is frequently used to assess potential causal mechanisms. The mediation package implements a comprehensive suite of statistical tools for conducting su...

  1. Micro dynamics in mediation

    OpenAIRE

    Boserup, Hans

    2014-01-01

    The author has identified a number of styles in mediation, which lead to different processes and different outcomes. Through discourse and conversation analysis he examines the micro dynamics in three of these, the postmodern styles: systemic, transformative and narrative mediation. The differences between the three mediation ideologies and practice is illustrated through role play scripts enacted in each style. Mediator and providers of mediation and trainers in mediation are encouraged to a...

  2. Proteins mediating DNA loops effectively block transcription.

    Science.gov (United States)

    Vörös, Zsuzsanna; Yan, Yan; Kovari, Daniel T; Finzi, Laura; Dunlap, David

    2017-07-01

    Loops are ubiquitous topological elements formed when proteins simultaneously bind to two noncontiguous DNA sites. While a loop-mediating protein may regulate initiation at a promoter, the presence of the protein at the other site may be an obstacle for RNA polymerases (RNAP) transcribing a different gene. To test whether a DNA loop alters the extent to which a protein blocks transcription, the lac repressor (LacI) was used. The outcome of in vitro transcription along templates containing two LacI operators separated by 400 bp in the presence of LacI concentrations that produced both looped and unlooped molecules was visualized with scanning force microscopy (SFM). An analysis of transcription elongation complexes, moving for 60 s at an average of 10 nt/s on unlooped DNA templates, revealed that they more often surpassed LacI bound to the lower affinity O2 operator than to the highest affinity Os operator. However, this difference was abrogated in looped DNA molecules where LacI became a strong roadblock independently of the affinity of the operator. Recordings of transcription elongation complexes, using magnetic tweezers, confirmed that they halted for several minutes upon encountering a LacI bound to a single operator. The average pause lifetime is compatible with RNAP waiting for LacI dissociation, however, the LacI open conformation visualized in the SFM images also suggests that LacI could straddle RNAP to let it pass. Independently of the mechanism by which RNAP bypasses the LacI roadblock, the data indicate that an obstacle with looped topology more effectively interferes with transcription. © 2017 The Authors Protein Science published by Wiley Periodicals, Inc. on behalf of The Protein Society.

  3. EWS/FLI mediates transcriptional repression via NKX2.2 during oncogenic transformation in Ewing's sarcoma.

    Directory of Open Access Journals (Sweden)

    Leah A Owen

    2008-04-01

    Full Text Available EWS/FLI is a master regulator of Ewing's sarcoma formation. Gene expression studies in A673 Ewing's sarcoma cells have demonstrated that EWS/FLI downregulates more genes than it upregulates, suggesting that EWS/FLI, and/or its targets, function as transcriptional repressors. One critical EWS/FLI target, NKX2.2, is a transcription factor that contains both transcriptional activation and transcriptional repression domains, raising the possibility that it mediates portions of the EWS/FLI transcriptional signature. We now report that microarray analysis demonstrated that the transcriptional profile of NKX2.2 consists solely of downregulated genes, and overlaps with the EWS/FLI downregulated signature, suggesting that NKX2.2 mediates oncogenic transformation via transcriptional repression. Structure-function analysis revealed that the DNA binding and repressor domains in NKX2.2 are required for oncogenesis in Ewing's sarcoma cells, while the transcriptional activation domain is completely dispensable. Furthermore, blockade of TLE or HDAC function, two protein families thought to mediate the repressive function of NKX2.2, inhibited the transformed phenotype and reversed the NKX2.2 transcriptional profile in Ewing's sarcoma cells. Whole genome localization studies (ChIP-chip revealed that a significant portion of the NKX2.2-repressed gene expression signature was directly mediated by NKX2.2 binding. These data demonstrate that the transcriptional repressive function of NKX2.2 is necessary, and sufficient, for the oncogenic phenotype of Ewing's sarcoma, and suggest a therapeutic approach to this disease.

  4. Global Analysis of the Fungal Microbiome in Cystic Fibrosis Patients Reveals Loss of Function of the Transcriptional Repressor Nrg1 as a Mechanism of Pathogen Adaptation.

    Science.gov (United States)

    Kim, Sang Hu; Clark, Shawn T; Surendra, Anuradha; Copeland, Julia K; Wang, Pauline W; Ammar, Ron; Collins, Cathy; Tullis, D Elizabeth; Nislow, Corey; Hwang, David M; Guttman, David S; Cowen, Leah E

    2015-11-01

    The microbiome shapes diverse facets of human biology and disease, with the importance of fungi only beginning to be appreciated. Microbial communities infiltrate diverse anatomical sites as with the respiratory tract of healthy humans and those with diseases such as cystic fibrosis, where chronic colonization and infection lead to clinical decline. Although fungi are frequently recovered from cystic fibrosis patient sputum samples and have been associated with deterioration of lung function, understanding of species and population dynamics remains in its infancy. Here, we coupled high-throughput sequencing of the ribosomal RNA internal transcribed spacer 1 (ITS1) with phenotypic and genotypic analyses of fungi from 89 sputum samples from 28 cystic fibrosis patients. Fungal communities defined by sequencing were concordant with those defined by culture-based analyses of 1,603 isolates from the same samples. Different patients harbored distinct fungal communities. There were detectable trends, however, including colonization with Candida and Aspergillus species, which was not perturbed by clinical exacerbation or treatment. We identified considerable inter- and intra-species phenotypic variation in traits important for host adaptation, including antifungal drug resistance and morphogenesis. While variation in drug resistance was largely between species, striking variation in morphogenesis emerged within Candida species. Filamentation was uncoupled from inducing cues in 28 Candida isolates recovered from six patients. The filamentous isolates were resistant to the filamentation-repressive effects of Pseudomonas aeruginosa, implicating inter-kingdom interactions as the selective force. Genome sequencing revealed that all but one of the filamentous isolates harbored mutations in the transcriptional repressor NRG1; such mutations were necessary and sufficient for the filamentous phenotype. Six independent nrg1 mutations arose in Candida isolates from different patients

  5. Global Analysis of the Fungal Microbiome in Cystic Fibrosis Patients Reveals Loss of Function of the Transcriptional Repressor Nrg1 as a Mechanism of Pathogen Adaptation.

    Directory of Open Access Journals (Sweden)

    Sang Hu Kim

    2015-11-01

    Full Text Available The microbiome shapes diverse facets of human biology and disease, with the importance of fungi only beginning to be appreciated. Microbial communities infiltrate diverse anatomical sites as with the respiratory tract of healthy humans and those with diseases such as cystic fibrosis, where chronic colonization and infection lead to clinical decline. Although fungi are frequently recovered from cystic fibrosis patient sputum samples and have been associated with deterioration of lung function, understanding of species and population dynamics remains in its infancy. Here, we coupled high-throughput sequencing of the ribosomal RNA internal transcribed spacer 1 (ITS1 with phenotypic and genotypic analyses of fungi from 89 sputum samples from 28 cystic fibrosis patients. Fungal communities defined by sequencing were concordant with those defined by culture-based analyses of 1,603 isolates from the same samples. Different patients harbored distinct fungal communities. There were detectable trends, however, including colonization with Candida and Aspergillus species, which was not perturbed by clinical exacerbation or treatment. We identified considerable inter- and intra-species phenotypic variation in traits important for host adaptation, including antifungal drug resistance and morphogenesis. While variation in drug resistance was largely between species, striking variation in morphogenesis emerged within Candida species. Filamentation was uncoupled from inducing cues in 28 Candida isolates recovered from six patients. The filamentous isolates were resistant to the filamentation-repressive effects of Pseudomonas aeruginosa, implicating inter-kingdom interactions as the selective force. Genome sequencing revealed that all but one of the filamentous isolates harbored mutations in the transcriptional repressor NRG1; such mutations were necessary and sufficient for the filamentous phenotype. Six independent nrg1 mutations arose in Candida isolates from

  6. Identification of DNA-binding protein target sequences by physical effective energy functions: free energy analysis of lambda repressor-DNA complexes.

    Directory of Open Access Journals (Sweden)

    Caselle Michele

    2007-09-01

    Full Text Available Abstract Background Specific binding of proteins to DNA is one of the most common ways gene expression is controlled. Although general rules for the DNA-protein recognition can be derived, the ambiguous and complex nature of this mechanism precludes a simple recognition code, therefore the prediction of DNA target sequences is not straightforward. DNA-protein interactions can be studied using computational methods which can complement the current experimental methods and offer some advantages. In the present work we use physical effective potentials to evaluate the DNA-protein binding affinities for the λ repressor-DNA complex for which structural and thermodynamic experimental data are available. Results The binding free energy of two molecules can be expressed as the sum of an intermolecular energy (evaluated using a molecular mechanics forcefield, a solvation free energy term and an entropic term. Different solvation models are used including distance dependent dielectric constants, solvent accessible surface tension models and the Generalized Born model. The effect of conformational sampling by Molecular Dynamics simulations on the computed binding energy is assessed; results show that this effect is in general negative and the reproducibility of the experimental values decreases with the increase of simulation time considered. The free energy of binding for non-specific complexes, estimated using the best energetic model, agrees with earlier theoretical suggestions. As a results of these analyses, we propose a protocol for the prediction of DNA-binding target sequences. The possibility of searching regulatory elements within the bacteriophage λ genome using this protocol is explored. Our analysis shows good prediction capabilities, even in absence of any thermodynamic data and information on the naturally recognized sequence. Conclusion This study supports the conclusion that physics-based methods can offer a completely complementary

  7. Positive Regulation of Staphylococcal Enterotoxin H by Rot (Repressor of Toxin) Protein and Its Importance in Clonal Complex 81 Subtype 1 Lineage-Related Food Poisoning.

    Science.gov (United States)

    Sato'o, Yusuke; Hisatsune, Junzo; Nagasako, Yuria; Ono, Hisaya K; Omoe, Katsuhiko; Sugai, Motoyuki

    2015-11-01

    We previously demonstrated the clonal complex 81 (CC81) subtype 1 lineage is the major staphylococcal food poisoning (SFP)-associated lineage in Japan (Y. Sato'o et al., J Clin Microbiol 52:2637-2640, 2014, http://dx.doi.org/10.1128/JCM.00661-14). Strains of this lineage produce staphylococcal enterotoxin H (SEH) in addition to SEA. However, an evaluation of the risk for the recently reported SEH has not been sufficiently conducted. We first searched for staphylococcal enterotoxin (SE) genes and SE proteins in milk samples that caused a large SFP outbreak in Japan. Only SEA and SEH were detected, while there were several SE genes detected in the samples. We next designed an experimental model using a meat product to assess the productivity of SEs and found that only SEA and SEH were detectably produced in situ. Therefore, we investigated the regulation of SEH production using a CC81 subtype 1 isolate. Through mutant analysis of global regulators, we found the repressor of toxin (Rot) functioned oppositely as a stimulator of SEH production. SEA production was not affected by Rot. seh mRNA expression correlated with rot both in media and on the meat product, and the Rot protein was shown to directly bind to the seh promoter. The seh promoter sequence was predicted to form a loop structure and to hide the RNA polymerase binding sequences. We propose Rot binds to the promoter sequence of seh and unfolds the secondary structure that may lead the RNA polymerase to bind the promoter, and then seh mRNA transcription begins. This alternative Rot regulation for SEH may contribute to sufficient toxin production by the CC81 subtype 1 lineage in foods to induce SFP. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  8. 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...... in cell cycle progression, including Aurora Kinase A, that has previously been implicated in the growth of NE-like castration-resistant tumors. The analysis of prostate cancer tissue microarrays revealed that tumors with reduced expression of REST have higher probability of early recurrence, independently...... of their Gleason score. The demonstration that REST modulates AR actions in prostate epithelia and that REST expression is negatively correlated with disease recurrence after prostatectomy, invite a deeper characterization of its role in prostate carcinogenesis....

  9. Dominant negative umuD mutations decreasing RecA-mediated cleavage suggest roles for intact UmuD in modulation of SOS mutagenesis

    International Nuclear Information System (INIS)

    Battista, J.R.; Ohta, Toshihiro; Nohmi, Takehiko; Sun, W.; Walker, G.C.

    1990-01-01

    The products of the SOS-regulated umuDC operon are required for most UV and chemical mutagenesis in Escherichia coli. The UmuD protein shares homology with a family of proteins that includes LexA and several bacteriophage repressors. UmuD is posttranslationally activated for its role n mutagenesis by a RecA-mediated proteolytic cleavage that yields UmuD'. A set of missense mutants of umuD was isolated and shown to encode mutant UmuD proteins that are deficient in RecA-mediated cleavage in vivo. Most of these mutations are dominant to umuD + with respect to UV mutagenesis yet do not interfere with SOS induction. Although both UmuD and UmuD' form homodimers, the authors provide evidence that they preferentially form heterodimers. The relationship of UmuD to LexA, λ repressor, and other members of the family of proteins is discussed and possible roles intact UmuD in modulating SOS mutagenesis are discussed

  10. Pentachlorophenol induction of the Pseudomonas aeruginosa mexAB-oprM efflux operon: involvement of repressors NalC and MexR and the antirepressor ArmR.

    Directory of Open Access Journals (Sweden)

    Lisa M Starr

    Full Text Available Pentachlorophenol (PCP induced expression of the NalC repressor-regulated PA3720-armR operon and the MexR repressor-controlled mexAB-oprM multidrug efflux operon of Pseudomonas aeruginosa. PCP's induction of PA3720-armR resulted from its direct modulation of NalC, the repressor's binding to PA3720-armR promoter-containing DNA as seen in electromobility shift assays (EMSAs being obviated in the presence of this agent. The NalC binding site was localized to an inverted repeat (IR sequence upstream of PA3720-armR and overlapping a promoter region whose transcription start site was mapped. While modulation of MexR by the ArmR anti-repressor explains the upregulation of mexAB-oprM in nalC mutants hyperexpressing PA3720-armR, the induction of mexAB-oprM expression by PCP is not wholly explainable by PCP induction of PA3720-armR and subsequent ArmR modulation of MexR, inasmuch as armR deletion mutants still showed PCP-inducible mexAB-oprM expression. PCP failed, however, to induce mexAB-oprM in a mexR deletion strain, indicating that MexR was required for this, although PCP did not modulate MexR binding to mexAB-oprM promoter-containing DNA in vitro. One possibility is that MexR responds to PCP-generated in vivo effector molecules in controlling mexAB-oprM expression in response to PCP. PCP is an unlikely effector and substrate for NalC and MexAB-OprM--its impact on NalC binding to the PA3720-armR promoter DNA occurred only at high µM levels--suggesting that it mimics an intended phenolic effector/substrate(s. In this regard, plants are an abundant source of phenolic antimicrobial compounds and, so, MexAB-OprM may function to protect P. aeruginosa from plant antimicrobials that it encounters in nature.

  11. MC EMiNEM maps the interaction landscape of the Mediator.

    Directory of Open Access Journals (Sweden)

    Theresa Niederberger

    Full Text Available The Mediator is a highly conserved, large multiprotein complex that is involved essentially in the regulation of eukaryotic mRNA transcription. It acts as a general transcription factor by integrating regulatory signals from gene-specific activators or repressors to the RNA Polymerase II. The internal network of interactions between Mediator subunits that conveys these signals is largely unknown. Here, we introduce MC EMiNEM, a novel method for the retrieval of functional dependencies between proteins that have pleiotropic effects on mRNA transcription. MC EMiNEM is based on Nested Effects Models (NEMs, a class of probabilistic graphical models that extends the idea of hierarchical clustering. It combines mode-hopping Monte Carlo (MC sampling with an Expectation-Maximization (EM algorithm for NEMs to increase sensitivity compared to existing methods. A meta-analysis of four Mediator perturbation studies in Saccharomyces cerevisiae, three of which are unpublished, provides new insight into the Mediator signaling network. In addition to the known modular organization of the Mediator subunits, MC EMiNEM reveals a hierarchical ordering of its internal information flow, which is putatively transmitted through structural changes within the complex. We identify the N-terminus of Med7 as a peripheral entity, entailing only local structural changes upon perturbation, while the C-terminus of Med7 and Med19 appear to play a central role. MC EMiNEM associates Mediator subunits to most directly affected genes, which, in conjunction with gene set enrichment analysis, allows us to construct an interaction map of Mediator subunits and transcription factors.

  12. MC EMiNEM maps the interaction landscape of the Mediator.

    Science.gov (United States)

    Niederberger, Theresa; Etzold, Stefanie; Lidschreiber, Michael; Maier, Kerstin C; Martin, Dietmar E; Fröhlich, Holger; Cramer, Patrick; Tresch, Achim

    2012-01-01

    The Mediator is a highly conserved, large multiprotein complex that is involved essentially in the regulation of eukaryotic mRNA transcription. It acts as a general transcription factor by integrating regulatory signals from gene-specific activators or repressors to the RNA Polymerase II. The internal network of interactions between Mediator subunits that conveys these signals is largely unknown. Here, we introduce MC EMiNEM, a novel method for the retrieval of functional dependencies between proteins that have pleiotropic effects on mRNA transcription. MC EMiNEM is based on Nested Effects Models (NEMs), a class of probabilistic graphical models that extends the idea of hierarchical clustering. It combines mode-hopping Monte Carlo (MC) sampling with an Expectation-Maximization (EM) algorithm for NEMs to increase sensitivity compared to existing methods. A meta-analysis of four Mediator perturbation studies in Saccharomyces cerevisiae, three of which are unpublished, provides new insight into the Mediator signaling network. In addition to the known modular organization of the Mediator subunits, MC EMiNEM reveals a hierarchical ordering of its internal information flow, which is putatively transmitted through structural changes within the complex. We identify the N-terminus of Med7 as a peripheral entity, entailing only local structural changes upon perturbation, while the C-terminus of Med7 and Med19 appear to play a central role. MC EMiNEM associates Mediator subunits to most directly affected genes, which, in conjunction with gene set enrichment analysis, allows us to construct an interaction map of Mediator subunits and transcription factors.

  13. Nutrient-induced stimulation of protein synthesis in mouse skeletal muscle is limited by the mTORC1 repressor REDD1.

    Science.gov (United States)

    Gordon, Bradley S; Williamson, David L; Lang, Charles H; Jefferson, Leonard S; Kimball, Scot R

    2015-04-01

    In skeletal muscle, the nutrient-induced stimulation of protein synthesis requires signaling through the mechanistic target of rapamycin complex 1 (mTORC1). Expression of the repressor of mTORC1 signaling, regulated in development and DNA damage 1 (REDD1), is elevated in muscle during various atrophic conditions and diminished under hypertrophic conditions. The question arises as to what extent REDD1 limits the nutrient-induced stimulation of protein synthesis. The objective was to examine the role of REDD1 in limiting the response of muscle protein synthesis and mTORC1 signaling to a nutrient stimulus. Wild type REDD1 gene (REDD1(+/+)) and disruption in the REDD1 gene (REDD1(-/-)) mice were feed deprived for 16 h and randomized to remain feed deprived or refed for 15 or 60 min. The tibialis anterior was then removed for analysis of protein synthesis and mTORC1 signaling. In feed-deprived mice, protein synthesis and mTORC1 signaling were significantly lower in REDD1(+/+) than in REDD1(-/-) mice. Thirty minutes after the start of refeeding, protein synthesis in REDD1(+/+) mice was stimulated by 28%, reaching a value similar to that observed in feed-deprived REDD1(-/-) mice, and was accompanied by increased phosphorylation of mTOR (Ser2448), p70S6K1 (Thr389), and 4E-BP1 (Ser65) by 81%, 167%, and 207%, respectively. In refed REDD1(-/-) mice, phosphorylation of mTOR (Ser2448), p70S6K1 (Thr389), and 4E-BP1 (Ser65) were significantly augmented above the values observed in refed REDD1(+/+) mice by 258%, 405%, and 401%, respectively, although protein synthesis was not coordinately increased. Seventy-five minutes after refeeding, REDD1 expression in REDD1(+/+) mice was reduced (∼15% of feed-deprived REDD1(+/+) values), and protein synthesis and mTORC1 signaling were not different between refed REDD1(+/+) mice and REDD1(-/-) mice. The results show that REDD1 expression limits protein synthesis in mouse skeletal muscle by inhibiting mTORC1 signaling during periods of feed

  14. Recruitment by the Repressor Freud-1 of Histone Deacetylase-Brg1 Chromatin Remodeling Complexes to Strengthen HTR1A Gene Repression.

    Science.gov (United States)

    Souslova, Tatiana; Mirédin, Kim; Millar, Anne M; Albert, Paul R

    2017-12-01

    Five-prime repressor element under dual repression binding protein-1 (Freud-1)/CC2D1A is genetically linked to intellectual disability and implicated in neuronal development. Freud-1 represses the serotonin-1A (5-HT1A) receptor gene HTR1A by histone deacetylase (HDAC)-dependent or HDAC-independent mechanisms in 5-HT1A-negative (e.g., HEK-293) or 5-HT1A-expressing cells (SK-N-SH), respectively. To identify the underlying mechanisms, Freud-1-associated proteins were affinity-purified from HEK-293 nuclear extracts and members of the Brg1/SMARCCA chromatin remodeling and Sin3A-HDAC corepressor complexes were identified. Pull-down assays using recombinant proteins showed that Freud-1 interacts directly with the Brg1 carboxyl-terminal domain; interaction with Brg1 required the carboxyl-terminal of Freud-1. Freud-1 complexes in HEK-293 and SK-N-SH cells differed, with low levels of BAF170/SMARCC2 and BAF57/SMARCE1 in HEK-293 cells and low-undetectable BAF155/SMARCC1, Sin3A, and HDAC1/2 in SK-N-SH cells. Similarly, by quantitative chromatin immunoprecipitation, Brg1-BAF170/57 and Sin3A-HDAC complexes were observed at the HTR1A promoter in HEK-293 cells, whereas in SK-N-SH cells, Sin3A-HDAC proteins were not detected. Quantifying 5-HT1A receptor mRNA levels in cells treated with siRNA to Freud-1, Brg1, or both RNAs addressed the functional role of the Freud-1-Brg1 complex. In HEK-293 cells, 5-HT1A receptor mRNA levels were increased only when both Freud-1 and Brg1 were depleted, but in SK-N-SH cells, depletion of either protein upregulated 5-HT1A receptor RNA. Thus, recruitment by Freud-1 of Brg1, BAF155, and Sin3A-HDAC complexes appears to strengthen repression of the HTR1A gene to prevent its expression inappropriate cell types, while recruitment of the Brg1-BAF170/57 complex is permissive to 5-HT1A receptor expression. Alterations in Freud-1-Brg1 interactions in mutants associated with intellectual disability could impair gene repression leading to altered neuronal

  15. Metabolic Reprogramming Regulates the Proliferative and Inflammatory Phenotype of Adventitial Fibroblasts in Pulmonary Hypertension Through the Transcriptional Co-Repressor C-terminal Binding Protein-1

    Science.gov (United States)

    Li, Min; Riddle, Suzette; Zhang, Hui; D’Alessandro, Angelo; Flockton, Amanda; Serkova, Natalie J.; Hansen, Kirk C.; Moldvan, Radu; McKeon, B. Alexandre; Frid, Maria; Kumar, Sushil; Li, Hong; Liu, Hongbing; Cánovas, Angela; Medrano, Juan F.; Thomas, Milton G.; Iloska, Dijana; Plecita-Hlavata, Lydie; Ježek, Petr; Pullamsetti, Soni; Fini, Mehdi A.; El Kasmi, Karim C.; Zhang, Qinghong; Stenmark, Kurt R.

    2016-01-01

    Background Changes in metabolism have been suggested to contribute to the aberrant phenotype of vascular wall cells including fibroblasts in pulmonary hypertension (PH). Herein, we test the hypothesis that metabolic reprogramming to aerobic glycolysis is a critical adaptation of fibroblasts in the hypertensive vessel wall that drives proliferative and pro-inflammatory activation through a mechanism involving increased activity of the NADH-sensitive transcriptional co-repressor C-terminal binding protein 1 (CtBP1). Methods RNA-Sequencing, qPCR, 13C-NMR, fluorescence-lifetime imaging, mass spectrometry-based metabolomics and tracing experiments with U-13C-glucose were used to assess glycolytic reprogramming and to measure NADH/NAD+ ratio in bovine and human adventitial fibroblasts, and mouse lung tissues. Immunohistochemistry was utilized to assess CtBP1 expression in the whole lung tissues. CtBP1 siRNA and the pharmacologic inhibitor 4-methylthio-2-oxobutyric acid (MTOB) were utilized to abrogate CtBP1 activity in cells and hypoxic mice. Results We found adventitial fibroblasts from calves with severe hypoxia-induced PH and humans with IPAH (PH-Fibs) displayed aerobic glycolysis when cultured under normoxia, accompanied by increased free NADH and NADH/NAD+ ratios. Expression of the NADH sensor CtBP1 was increased in vivo and in vitro in fibroblasts within the pulmonary adventitia of humans with IPAH and animals with PH and cultured PH-Fibs, respectively. Decreasing NADH pharmacologically with MTOB, or genetically blocking CtBP1 using siRNA, upregulated the cyclin-dependent genes (p15 and p21) and pro-apoptotic regulators (NOXA and PERP), attenuated proliferation, corrected the glycolytic reprogramming phenotype of PH-Fibs, and augmented transcription of the anti-inflammatory gene HMOX1. ChIP analysis demonstrated that CtBP1 directly binds the HMOX1 promoter. Treatment of hypoxic mice with MTOB decreased glycolysis and expression of inflammatory genes, attenuated

  16. An analysis of the binding of repressor protein ModE to modABCD (molybdate transport) operator/promoter DNA of Escherichia coli.

    Science.gov (United States)

    Grunden, A M; Self, W T; Villain, M; Blalock, J E; Shanmugam, K T

    1999-08-20

    Expression of the modABCD operon in Escherichia coli, which codes for a molybdate-specific transporter, is repressed by ModE in vivo in a molybdate-dependent fashion. In vitro DNase I-footprinting experiments identified three distinct regions of protection by ModE-molybdate on the modA operator/promoter DNA, GTTATATT (-15 to -8; region 1), GCCTACAT (-4 to +4; region 2), and GTTACAT (+8 to +14; region 3). Within the three regions of the protected DNA, a pentamer sequence, TAYAT (Y = C or T), can be identified. DNA-electrophoretic mobility experiments showed that the protected regions 1 and 2 are essential for binding of ModE-molybdate to DNA, whereas the protected region 3 increases the affinity of the DNA to the repressor. The stoichiometry of this interaction was found to be two ModE-molybdate per modA operator DNA. ModE-molybdate at 5 nM completely protected the modABCD operator/promoter DNA from DNase I-catalyzed hydrolysis, whereas ModE alone failed to protect the DNA even at 100 nM. The apparent K(d) for the interaction between the modA operator DNA and ModE-molybdate was 0.3 nM, and the K(d) increased to 8 nM in the absence of molybdate. Among the various oxyanions tested, only tungstate replaced molybdate in the repression of modA by ModE, but the affinity of ModE-tungstate for modABCD operator DNA was 6 times lower than with ModE-molybdate. A mutant ModE(T125I) protein, which repressed modA-lac even in the absence of molybdate, protected the same region of modA operator DNA in the absence of molybdate. The apparent K(d) for the interaction between modA operator DNA and ModE(T125I) was 3 nM in the presence of molybdate and 4 nM without molybdate. The binding of molybdate to ModE resulted in a decrease in fluorescence emission, indicating a conformational change of the protein upon molybdate binding. The fluorescence emission spectra of mutant ModE proteins, ModE(T125I) and ModE(Q216*), were unaffected by molybdate. The molybdate-independent mutant Mod

  17. Wheat TILLING mutants show that the vernalization gene VRN1 down-regulates the flowering repressor VRN2 in leaves but is not essential for flowering.

    Directory of Open Access Journals (Sweden)

    Andrew Chen

    Full Text Available Most of the natural variation in wheat vernalization response is determined by allelic differences in the MADS-box transcription factor VERNALIZATION1 (VRN1. Extended exposures to low temperatures during the winter (vernalization induce VRN1 expression and promote the transition of the apical meristem to the reproductive phase. In contrast to its Arabidopsis homolog (APETALA1, which is mainly expressed in the apical meristem, VRN1 is also expressed at high levels in the leaves, but its function in this tissue is not well understood. Using tetraploid wheat lines with truncation mutations in the two homoeologous copies of VRN1 (henceforth vrn1-null mutants, we demonstrate that a central role of VRN1 in the leaves is to maintain low transcript levels of the VRN2 flowering repressor after vernalization. Transcript levels of VRN2 were gradually down-regulated during vernalization in both mutant and wild-type genotypes, but were up-regulated after vernalization only in the vrn1-null mutants. The up-regulation of VRN2 delayed flowering by repressing the transcription of FT, a flowering-integrator gene that encodes a mobile protein that is transported from the leaves to the apical meristem to induce flowering. The role of VRN2 in the delayed flowering of the vrn1-null mutant was confirmed using double vrn1-vrn2-null mutants, which flowered two months earlier than the vrn1-null mutants. Both mutants produced normal flowers and seeds demonstrating that VRN1 is not essential for wheat flowering, which contradicts current flowering models. This result does not diminish the importance of VRN1 in the seasonal regulation of wheat flowering. The up-regulation of VRN1 during winter is required to maintain low transcript levels of VRN2, accelerate the induction of FT in the leaves, and regulate a timely flowering in the spring. Our results also demonstrate the existence of redundant wheat flowering genes that may provide new targets for engineering wheat

  18. microRNA 21-mediated suppression of Sprouty1 by Pokemon affects liver cancer cell growth and proliferation.

    Science.gov (United States)

    Jin, Xiu-Li; Sun, Qin-Sheng; Liu, Feng; Yang, Hong-Wei; Liu, Min; Liu, Hong-Xia; Xu, Wei; Jiang, Yu-Yang

    2013-07-01

    Transcriptional repressor Pokemon is a critical factor in embryogenesis, development, cell proliferation, differentiation, and oncogenesis, thus behaving as an oncogene. Oncomine database suggests a potential correlation between the expressions of Pokemon and Sprouty1. This study investigated the regulatory role of Pokemon in Sprouty1 expression and the effect on liver cancer cell growth and proliferation, revealing a novel miR-21-mediated regulatory circuit. In normal (HL-7702) and cancer (QGY-7703) liver cell lines, Sprouty1 expression is inversely correlated with Pokemon levels. Targeted expression or siRNA-mediated silencing showed that Pokemon is a repressor of Sprouty1 expression at both mRNA and protein levels, but Pokemon cannot affect the promoter activity of Sprouty1. Sprouty1 is a target of miR-21 and interestingly, we found that miR-21 is up-regulated by Pokemon in liver cancer cells. Luciferase reporter assays showed that Pokemon up-regulated miR-21 transcription in a dose-dependent manner, and ChIP assay exhibited a direct binding of Pokemon to the miR-21 promoter at -747 to -399 bp. Site-directed mutagenesis of the GC boxes at -684 to -679 bp and -652 to -647 bp of miR-21 promoter abolished the regulatory activity by Pokemon. Furthermore, we found that the modulation of Pokemon and miR-21 expression affected the growth and proliferation of liver cancer cells QGY-7703. In summary, our findings demonstrate that Pokemon suppresses Sprouty1 expression through a miR-21-mediated mechanism, affecting the growth and proliferation of liver cancer cells. This study recognized miR-21 and Sprouty1 as novel targets of the Pokemon regulatory network. Copyright © 2013 Wiley Periodicals, Inc.

  19. Nordic Mediation Reseach

    DEFF Research Database (Denmark)

    A presentation of 12 studies on mediation from researchers from Denmark, Finland, Norway and Sweden.......A presentation of 12 studies on mediation from researchers from Denmark, Finland, Norway and Sweden....

  20. Bayesian Mediation Analysis

    OpenAIRE

    Yuan, Ying; MacKinnon, David P.

    2009-01-01

    This article proposes Bayesian analysis of mediation effects. Compared to conventional frequentist mediation analysis, the Bayesian approach has several advantages. First, it allows researchers to incorporate prior information into the mediation analysis, thus potentially improving the efficiency of estimates. Second, under the Bayesian mediation analysis, inference is straightforward and exact, which makes it appealing for studies with small samples. Third, the Bayesian approach is conceptua...

  1. mediation: R Package for Causal Mediation Analysis

    Directory of Open Access Journals (Sweden)

    Dustin Tingley

    2014-09-01

    Full Text Available In this paper, we describe the R package mediation for conducting causal mediation analysis in applied empirical research. In many scientific disciplines, the goal of researchers is not only estimating causal effects of a treatment but also understanding the process in which the treatment causally affects the outcome. Causal mediation analysis is frequently used to assess potential causal mechanisms. The mediation package implements a comprehensive suite of statistical tools for conducting such an analysis. The package is organized into two distinct approaches. Using the model-based approach, researchers can estimate causal mediation effects and conduct sensitivity analysis under the standard research design. Furthermore, the design-based approach provides several analysis tools that are applicable under different experimental designs. This approach requires weaker assumptions than the model-based approach. We also implement a statistical method for dealing with multiple (causally dependent mediators, which are often encountered in practice. Finally, the package also offers a methodology for assessing causal mediation in the presence of treatment noncompliance, a common problem in randomized trials.

  2. Bayesian Mediation Analysis

    Science.gov (United States)

    Yuan, Ying; MacKinnon, David P.

    2009-01-01

    In this article, we propose Bayesian analysis of mediation effects. Compared with conventional frequentist mediation analysis, the Bayesian approach has several advantages. First, it allows researchers to incorporate prior information into the mediation analysis, thus potentially improving the efficiency of estimates. Second, under the Bayesian…

  3. The functions of Mediator in Candida albicans support a role in shaping species-specific gene expression.

    Directory of Open Access Journals (Sweden)

    Nathalie Uwamahoro

    Full Text Available The Mediator complex is an essential co-regulator of RNA polymerase II that is conserved throughout eukaryotes. Here we present the first study of Mediator in the pathogenic fungus Candida albicans. We focused on the Middle domain subunit Med31, the Head domain subunit Med20, and Srb9/Med13 from the Kinase domain. The C. albicans Mediator shares some roles with model yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe, such as functions in the response to certain stresses and the role of Med31 in the expression of genes regulated by the activator Ace2. The C. albicans Mediator also has additional roles in the transcription of genes associated with virulence, for example genes related to morphogenesis and gene families enriched in pathogens, such as the ALS adhesins. Consistently, Med31, Med20, and Srb9/Med13 contribute to key virulence attributes of C. albicans, filamentation, and biofilm formation; and ALS1 is a biologically relevant target of Med31 for development of biofilms. Furthermore, Med31 affects virulence of C. albicans in the worm infection model. We present evidence that the roles of Med31 and Srb9/Med13 in the expression of the genes encoding cell wall adhesins are different between S. cerevisiae and C. albicans: they are repressors of the FLO genes in S. cerevisiae and are activators of the ALS genes in C. albicans. This suggests that Mediator subunits regulate adhesion in a distinct manner between these two distantly related fungal species.

  4. General gauge mediation

    International Nuclear Information System (INIS)

    Meade, Patrick; Seiberg, Nathan; Shih, David

    2009-01-01

    We give a general definition of gauge mediated supersymmetry breaking which encompasses all the known gauge mediation models. In particular, it includes both models with messengers as well as direct mediation models. A formalism for computing the soft terms in the generic model is presented. Such a formalism is necessary in strongly-coupled direct mediation models where perturbation theory cannot be used. It allows us to identify features of the entire class of gauge mediation models and to distinguish them from specific signatures of various subclasses. (author)

  5. Bayesian dynamic mediation analysis.

    Science.gov (United States)

    Huang, Jing; Yuan, Ying

    2017-12-01

    Most existing methods for mediation analysis assume that mediation is a stationary, time-invariant process, which overlooks the inherently dynamic nature of many human psychological processes and behavioral activities. In this article, we consider mediation as a dynamic process that continuously changes over time. We propose Bayesian multilevel time-varying coefficient models to describe and estimate such dynamic mediation effects. By taking the nonparametric penalized spline approach, the proposed method is flexible and able to accommodate any shape of the relationship between time and mediation effects. Simulation studies show that the proposed method works well and faithfully reflects the true nature of the mediation process. By modeling mediation effect nonparametrically as a continuous function of time, our method provides a valuable tool to help researchers obtain a more complete understanding of the dynamic nature of the mediation process underlying psychological and behavioral phenomena. We also briefly discuss an alternative approach of using dynamic autoregressive mediation model to estimate the dynamic mediation effect. The computer code is provided to implement the proposed Bayesian dynamic mediation analysis. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  6. CRY Drives Cyclic CK2-Mediated BMAL1 Phosphorylation to Control the Mammalian Circadian Clock.

    Directory of Open Access Journals (Sweden)

    Teruya Tamaru

    Full Text Available Intracellular circadian clocks, composed of clock genes that act in transcription-translation feedback loops, drive global rhythmic expression of the mammalian transcriptome and allow an organism to anticipate to the momentum of the day. Using a novel clock-perturbing peptide, we established a pivotal role for casein kinase (CK-2-mediated circadian BMAL1-Ser90 phosphorylation (BMAL1-P in regulating central and peripheral core clocks. Subsequent analysis of the underlying mechanism showed a novel role of CRY as a repressor for protein kinase. Co-immunoprecipitation experiments and real-time monitoring of protein-protein interactions revealed that CRY-mediated periodic binding of CK2β to BMAL1 inhibits BMAL1-Ser90 phosphorylation by CK2α. The FAD binding domain of CRY1, two C-terminal BMAL1 domains, and particularly BMAL1-Lys537 acetylation/deacetylation by CLOCK/SIRT1, were shown to be critical for CRY-mediated BMAL1-CK2β binding. Reciprocally, BMAL1-Ser90 phosphorylation is prerequisite for BMAL1-Lys537 acetylation. We propose a dual negative-feedback model in which a CRY-dependent CK2-driven posttranslational BMAL1-P-BMAL1 loop is an integral part of the core clock oscillator.

  7. Brassinosteroids Antagonize Gibberellin- and Salicylate-Mediated Root Immunity in Rice1[C][W][OA

    Science.gov (United States)

    De Vleesschauwer, David; Van Buyten, Evelien; Satoh, Kouji; Balidion, Johny; Mauleon, Ramil; Choi, Il-Ryong; Vera-Cruz, Casiana; Kikuchi, Shoshi; Höfte, Monica

    2012-01-01

    Brassinosteroids (BRs) are a unique class of plant steroid hormones that orchestrate myriad growth and developmental processes. Although BRs have long been known to protect plants from a suite of biotic and abiotic stresses, our understanding of the underlying molecular mechanisms is still rudimentary. Aiming to further decipher the molecular logic of BR-modulated immunity, we have examined the dynamics and impact of BRs during infection of rice (Oryza sativa) with the root oomycete Pythium graminicola. Challenging the prevailing view that BRs positively regulate plant innate immunity, we show that P. graminicola exploits BRs as virulence factors and hijacks the rice BR machinery to inflict disease. Moreover, we demonstrate that this immune-suppressive effect of BRs is due, at least in part, to negative cross talk with salicylic acid (SA) and gibberellic acid (GA) pathways. BR-mediated suppression of SA defenses occurred downstream of SA biosynthesis, but upstream of the master defense regulators NONEXPRESSOR OF PATHOGENESIS-RELATED GENES1 and OsWRKY45. In contrast, BR alleviated GA-directed immune responses by interfering at multiple levels with GA metabolism, resulting in indirect stabilization of the DELLA protein and central GA repressor SLENDER RICE1 (SLR1). Collectively, these data favor a model whereby P. graminicola coopts the plant BR pathway as a decoy to antagonize effectual SA- and GA-mediated defenses. Our results highlight the importance of BRs in modulating plant immunity and uncover pathogen-mediated manipulation of plant steroid homeostasis as a core virulence strategy. PMID:22353574

  8. Brassinosteroids antagonize gibberellin- and salicylate-mediated root immunity in rice.

    Science.gov (United States)

    De Vleesschauwer, David; Van Buyten, Evelien; Satoh, Kouji; Balidion, Johny; Mauleon, Ramil; Choi, Il-Ryong; Vera-Cruz, Casiana; Kikuchi, Shoshi; Höfte, Monica

    2012-04-01

    Brassinosteroids (BRs) are a unique class of plant steroid hormones that orchestrate myriad growth and developmental processes. Although BRs have long been known to protect plants from a suite of biotic and abiotic stresses, our understanding of the underlying molecular mechanisms is still rudimentary. Aiming to further decipher the molecular logic of BR-modulated immunity, we have examined the dynamics and impact of BRs during infection of rice (Oryza sativa) with the root oomycete Pythium graminicola. Challenging the prevailing view that BRs positively regulate plant innate immunity, we show that P. graminicola exploits BRs as virulence factors and hijacks the rice BR machinery to inflict disease. Moreover, we demonstrate that this immune-suppressive effect of BRs is due, at least in part, to negative cross talk with salicylic acid (SA) and gibberellic acid (GA) pathways. BR-mediated suppression of SA defenses occurred downstream of SA biosynthesis, but upstream of the master defense regulators NONEXPRESSOR OF PATHOGENESIS-RELATED GENES1 and OsWRKY45. In contrast, BR alleviated GA-directed immune responses by interfering at multiple levels with GA metabolism, resulting in indirect stabilization of the DELLA protein and central GA repressor SLENDER RICE1 (SLR1). Collectively, these data favor a model whereby P. graminicola coopts the plant BR pathway as a decoy to antagonize effectual SA- and GA-mediated defenses. Our results highlight the importance of BRs in modulating plant immunity and uncover pathogen-mediated manipulation of plant steroid homeostasis as a core virulence strategy.

  9. Inhibition of tumor cell growth by Sigma1 ligand mediated translational repression

    International Nuclear Information System (INIS)

    Kim, Felix J.; Schrock, Joel M.; Spino, Christina M.; Marino, Jacqueline C.; Pasternak, Gavril W.

    2012-01-01

    Highlights: ► Sigma1 ligand treatment mediates decrease in tumor cell mass. ► Identification of a Sigma1 ligand with reversible translational repressor actions. ► Demonstration of a role for Sigma1 in cellular protein synthesis. -- Abstract: Treatment with sigma1 receptor (Sigma1) ligands can inhibit cell proliferation in vitro and tumor growth in vivo. However, the cellular pathways engaged in response to Sigma1 ligand treatment that contribute to these outcomes remain largely undefined. Here, we show that treatment with putative antagonists of Sigma1 decreases cell mass. This effect corresponds with repressed cap-dependent translation initiation in multiple breast and prostate cancer cell lines. Sigma1 antagonist treatment suppresses phosphorylation of translational regulator proteins p70S6K, S6, and 4E-BP1. RNAi-mediated knockdown of Sigma1 also results in translational repression, consistent with the effects of antagonist treatment. Sigma1 antagonist mediated translational repression and decreased cell size are both reversible. Together, these data reveal a role for Sigma1 in tumor cell protein synthesis, and demonstrate that small molecule Sigma1 ligands can be used as modulators of protein translation.

  10. Malondialdehyde inhibits an AMPK-mediated nuclear translocation and repression activity of ALDH2 in transcription

    International Nuclear Information System (INIS)

    Choi, Ji-Woong; Kim, Jae-Hwan; Cho, Sung-Chun; Ha, Moon-Kyung; Song, Kye-Yong; Youn, Hong-Duk; Park, Sang Chul

    2011-01-01

    Research highlights: → ALDH2 is an MDA-modified protein in old rat kidney tissues. → AMPK associates with ALDH2 and triggers the nuclear localization of ALDH2. → ALDH2 serves as a general transcriptional repressor by associating with HDACs. → MDA inhibits the AMPK-mediated translocation of ALDH2 and its repression activity. -- Abstract: Aging process results from deleterious damages by reactive oxygen species, in particular, various metabolic aldehydes. Aldehyde dehydrogenase 2 (ALDH2) is one of metabolic enzymes detoxifying various aldehydes under oxidative conditions. AMP-activated protein kinase (AMPK) plays a key role in controlling metabolic process. However, little was known about the relationship of ALDH2 with AMPK under oxidative conditions. Here, we, by using MDA-specific monoclonal antibody, screened the tissues of young and old rats for MDA-modified proteins and identified an ALDH2 as a prominent MDA-modified protein band in the old rat kidney tissue. ALDH2 associates with AMPK and is phosphorylated by AMPK. In addition, AICAR, an activator of AMP-activated protein kinase, induces the nuclear translocation of ALDH2. ALDH2 in nucleus is involved in general transcription repression by association with histone deacetylases. Furthermore, MDA modification inhibited the translocation of ALDH2 and the association with AMPK, and ultimately led to de-repression of transcription in the reporter system analysis. In this study, we have demonstrated that ALDH2 acts as a transcriptional repressor in response to AMPK activation, and MDA modifies ALDH2 and inhibits repressive activity of ALDH2 in general transcription. We thus suggest that increasing amount of MDA during aging process may interrupt the nuclear function of ALDH2, modulated by AMPK.

  11. Malondialdehyde inhibits an AMPK-mediated nuclear translocation and repression activity of ALDH2 in transcription

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Ji-Woong [Department of Biomedical Sciences and Biochemistry and Molecular Biology, Seoul National University College of Medicine, 28 Yongon-dong, Chongro-gu, Seoul 110-799 (Korea, Republic of); Aging and Apoptosis Research Center (AARC), Seoul National University College of Medicine, 28 Yongon-dong, Chongro-gu, Seoul 110-799, (Korea, Republic of); Kim, Jae-Hwan [Department of Biomedical Sciences and Biochemistry and Molecular Biology, Seoul National University College of Medicine, 28 Yongon-dong, Chongro-gu, Seoul 110-799 (Korea, Republic of); Cho, Sung-Chun; Ha, Moon-Kyung [Department of Biomedical Sciences and Biochemistry and Molecular Biology, Seoul National University College of Medicine, 28 Yongon-dong, Chongro-gu, Seoul 110-799 (Korea, Republic of); Aging and Apoptosis Research Center (AARC), Seoul National University College of Medicine, 28 Yongon-dong, Chongro-gu, Seoul 110-799, (Korea, Republic of); Song, Kye-Yong [Department of Pathology, Chung-Ang University College of Medicine, Seoul 156-756 (Korea, Republic of); Youn, Hong-Duk, E-mail: hdyoun@snu.ac.kr [Department of Biomedical Sciences and Biochemistry and Molecular Biology, Seoul National University College of Medicine, 28 Yongon-dong, Chongro-gu, Seoul 110-799 (Korea, Republic of); Park, Sang Chul, E-mail: scpark@snu.ac.kr [Department of Biomedical Sciences and Biochemistry and Molecular Biology, Seoul National University College of Medicine, 28 Yongon-dong, Chongro-gu, Seoul 110-799 (Korea, Republic of); Aging and Apoptosis Research Center (AARC), Seoul National University College of Medicine, 28 Yongon-dong, Chongro-gu, Seoul 110-799, (Korea, Republic of)

    2011-01-07

    Research highlights: {yields} ALDH2 is an MDA-modified protein in old rat kidney tissues. {yields} AMPK associates with ALDH2 and triggers the nuclear localization of ALDH2. {yields} ALDH2 serves as a general transcriptional repressor by associating with HDACs. {yields} MDA inhibits the AMPK-mediated translocation of ALDH2 and its repression activity. -- Abstract: Aging process results from deleterious damages by reactive oxygen species, in particular, various metabolic aldehydes. Aldehyde dehydrogenase 2 (ALDH2) is one of metabolic enzymes detoxifying various aldehydes under oxidative conditions. AMP-activated protein kinase (AMPK) plays a key role in controlling metabolic process. However, little was known about the relationship of ALDH2 with AMPK under oxidative conditions. Here, we, by using MDA-specific monoclonal antibody, screened the tissues of young and old rats for MDA-modified proteins and identified an ALDH2 as a prominent MDA-modified protein band in the old rat kidney tissue. ALDH2 associates with AMPK and is phosphorylated by AMPK. In addition, AICAR, an activator of AMP-activated protein kinase, induces the nuclear translocation of ALDH2. ALDH2 in nucleus is involved in general transcription repression by association with histone deacetylases. Furthermore, MDA modification inhibited the translocation of ALDH2 and the association with AMPK, and ultimately led to de-repression of transcription in the reporter system analysis. In this study, we have demonstrated that ALDH2 acts as a transcriptional repressor in response to AMPK activation, and MDA modifies ALDH2 and inhibits repressive activity of ALDH2 in general transcription. We thus suggest that increasing amount of MDA during aging process may interrupt the nuclear function of ALDH2, modulated by AMPK.

  12. Causal mediation analysis with multiple mediators.

    Science.gov (United States)

    Daniel, R M; De Stavola, B L; Cousens, S N; Vansteelandt, S

    2015-03-01

    In diverse fields of empirical research-including many in the biological sciences-attempts are made to decompose the effect of an exposure on an outcome into its effects via a number of different pathways. For example, we may wish to separate the effect of heavy alcohol consumption on systolic blood pressure (SBP) into effects via body mass index (BMI), via gamma-glutamyl transpeptidase (GGT), and via other pathways. Much progress has been made, mainly due to contributions from the field of causal inference, in understanding the precise nature of statistical estimands that capture such intuitive effects, the assumptions under which they can be identified, and statistical methods for doing so. These contributions have focused almost entirely on settings with a single mediator, or a set of mediators considered en bloc; in many applications, however, researchers attempt a much more ambitious decomposition into numerous path-specific effects through many mediators. In this article, we give counterfactual definitions of such path-specific estimands in settings with multiple mediators, when earlier mediators may affect later ones, showing that there are many ways in which decomposition can be done. We discuss the strong assumptions under which the effects are identified, suggesting a sensitivity analysis approach when a particular subset of the assumptions cannot be justified. These ideas are illustrated using data on alcohol consumption, SBP, BMI, and GGT from the Izhevsk Family Study. We aim to bridge the gap from "single mediator theory" to "multiple mediator practice," highlighting the ambitious nature of this endeavor and giving practical suggestions on how to proceed. © 2014 The Authors Biometrics published by Wiley Periodicals, Inc. on behalf of International Biometric Society.

  13. The Solanum lycopersicum Zinc Finger2 Cysteine-2/Histidine-2 Repressor-Like Transcription Factor Regulates Development and Tolerance to Salinity in Tomato and Arabidopsis(1[W])

    Czech Academy of Sciences Publication Activity Database

    Hichri, I.; Muhovski, Y.; Žižková, Eva; Dobrev, Petre; Franco-Zorrilla, J.M.; Solano, R.; Lopez-Vidriero, I.; Motyka, Václav; Lutts, S.

    2014-01-01

    Roč. 164, č. 4 (2014), s. 1967-1990 ISSN 0032-0889 R&D Projects: GA ČR(CZ) GAP506/11/0774 Institutional support: RVO:61389030 Keywords : RICE ORYZA-SATIVA * AGROBACTERIUM-MEDIATED TRANSFORMATION * TARGET-SEQUENCE RECOGNITION Subject RIV: EF - Botanics Impact factor: 6.841, year: 2014

  14. Flexible Mediation Analysis With Multiple Mediators.

    Science.gov (United States)

    Steen, Johan; Loeys, Tom; Moerkerke, Beatrijs; Vansteelandt, Stijn

    2017-07-15

    The advent of counterfactual-based mediation analysis has triggered enormous progress on how, and under what assumptions, one may disentangle path-specific effects upon combining arbitrary (possibly nonlinear) models for mediator and outcome. However, current developments have largely focused on single mediators because required identification assumptions prohibit simple extensions to settings with multiple mediators that may depend on one another. In this article, we propose a procedure for obtaining fine-grained decompositions that may still be recovered from observed data in such complex settings. We first show that existing analytical approaches target specific instances of a more general set of decompositions and may therefore fail to provide a comprehensive assessment of the processes that underpin cause-effect relationships between exposure and outcome. We then outline conditions for obtaining the remaining set of decompositions. Because the number of targeted decompositions increases rapidly with the number of mediators, we introduce natural effects models along with estimation methods that allow for flexible and parsimonious modeling. Our procedure can easily be implemented using off-the-shelf software and is illustrated using a reanalysis of the World Health Organization's Large Analysis and Review of European Housing and Health Status (WHO-LARES) study on the effect of mold exposure on mental health (2002-2003). © The Author(s) 2017. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  15. Technology-Use Mediation

    DEFF Research Database (Denmark)

    Bansler, Jørgen P.; Havn, Erling C.

    2003-01-01

    This study analyzes how a group of ‘mediators’ in a large, multinational company adapted a computer-mediated communication technology (a ‘virtual workspace’) to the organizational context (and vice versa) by modifying features of the technology, providing ongoing support for users, and promoting...... appropriate conventions of use. Our findings corroborate earlier research on technology-use mediation, which suggests that such mediators can exert considerable influence on how a particular technology will be established and used in an organization. However, this study also indicates that the process...... of technology-use mediation is more complex and indeterminate than earlier literature suggests. In particular, we want to draw attention to the fact that advanced computer-mediated communication technologies are equivocal and that technology-use mediation consequently requires ongoing sensemaking (Weick 1995)....

  16. The Schizosaccharomyces pombe Mediator

    DEFF Research Database (Denmark)

    Venturi, Michela

    , Schizosaccharomyces pombe and mammalian Mediator. In our study, we have taken the S. pombe Mediator into consideration and characterized genetically and biochemically two subunits already know in S. cerevisiae, Med9 and Med11, but still not identified in the S. pombe Mediator. Genetic analysis has shown that med9......In the past several years great attention has been dedicated to the characterization of the Mediator complex in a different range of model organisms. Mediator is a conserved co-activator complex involved in transcriptional regulation and it conveys signals from regulatory transcription factors...... to the basal transcription machinery. Mediator was initially isolated from Saccharomyces cerevisiae based on its ability to render a RNA polymerase II in vitro transcription system responsive to activators. Additionally, structural studies have revealed striking structural similarities between S. cerevisiae...

  17. Freud-2/CC2D1B mediates dual repression of the serotonin-1A receptor gene.

    Science.gov (United States)

    Hadjighassem, Mahmoud R; Galaraga, Kimberly; Albert, Paul R

    2011-01-01

    The serotonin-1A (5-HT1A) receptor functions as a pre-synaptic autoreceptor in serotonin neurons that regulates their activity, and is also widely expressed on non-serotonergic neurons as a post-synaptic heteroreceptor to mediate serotonin action. The 5-HT1A receptor gene is strongly repressed by a dual repressor element (DRE), which is recognized by two proteins: Freud-1/CC2D1A and another unknown protein. Here we identify mouse Freud-2/CC2D1B as the second repressor of the 5-HT1A-DRE. Freud-2 shares 50% amino acid identity with Freud-1, and contains conserved structural domains. Mouse Freud-2 bound specifically to the rat 5-HT1A-DRE adjacent to, and partially overlapping, the Freud-1 binding site. By supershift assay using nuclear extracts from L6 myoblasts, Freud-2-DRE complexes were distinguished from Freud-1-DRE complexes. Freud-2 mRNA and protein were detected throughout mouse brain and peripheral tissues. Freud-2 repressed 5-HT1A promoter-reporter constructs in a DRE-dependent manner in non-neuronal (L6) or 5-HT1A-expressing neuronal (NG108-15, RN46A) cell models. In NG108-15 cells, knockdown of Freud-2 using a specific short-interfering RNA reduced endogenous Freud-2 protein levels and decreased Freud-2 bound to the 5-HT1A-DRE as detected by chromatin immunoprecipitation assay, but increased 5-HT1A promoter activity and 5-HT1A protein levels. Taken together, these data show that Freud-2 is the second component that, with Freud-1, mediates dual repression of the 5-HT1A receptor gene at the DRE. © 2010 The Authors. European Journal of Neuroscience © 2010 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

  18. Applied mediation analyses

    DEFF Research Database (Denmark)

    Lange, Theis; Hansen, Kim Wadt; Sørensen, Rikke

    2017-01-01

    In recent years, mediation analysis has emerged as a powerful tool to disentangle causal pathways from an exposure/treatment to clinically relevant outcomes. Mediation analysis has been applied in scientific fields as diverse as labour market relations and randomized clinical trials of heart...... disease treatments. In parallel to these applications, the underlying mathematical theory and computer tools have been refined. This combined review and tutorial will introduce the reader to modern mediation analysis including: the mathematical framework; required assumptions; and software implementation...

  19. Immunologically mediated oral diseases

    OpenAIRE

    Jimson, Sudha; Balachader, N.; Anita, N.; Babu, R.

    2015-01-01

    Immune mediated diseases of oral cavity are uncommon. The lesions may be self-limiting and undergo remission spontaneously. Among the immune mediated oral lesions the most important are lichen planus, pemphigus, erythema multiformi, epidermolysis bullosa, systemic lupus erythematosis. Cellular and humoral mediated immunity play a major role directed against epithelial and connective tissue in chronic and recurrent patterns. Confirmatory diagnosis can be made by biopsy, direct and indirect imm...

  20. Implementing general gauge mediation

    International Nuclear Information System (INIS)

    Carpenter, Linda M.; Dine, Michael; Festuccia, Guido; Mason, John D.

    2009-01-01

    Recently there has been much progress in building models of gauge mediation, often with predictions different than those of minimal gauge mediation. Meade, Seiberg, and Shih have characterized the most general spectrum which can arise in gauge-mediated models. We discuss some of the challenges of building models of general gauge mediation, especially the problem of messenger parity and issues connected with R symmetry breaking and CP violation. We build a variety of viable, weakly coupled models which exhibit some or all of the possible low energy parameters.

  1. Two-Stage Translational Control of Dentate Gyrus LTP Consolidation Is Mediated by Sustained BDNF-TrkB Signaling to MNK

    Directory of Open Access Journals (Sweden)

    Debabrata Panja

    2014-11-01

    Full Text Available BDNF signaling contributes to protein-synthesis-dependent synaptic plasticity, but the dynamics of TrkB signaling and mechanisms of translation have not been defined. Here, we show that long-term potentiation (LTP consolidation in the dentate gyrus of live rodents requires sustained (hours BDNF-TrkB signaling. Surprisingly, this sustained activation maintains an otherwise labile signaling pathway from TrkB to MAP-kinase-interacting kinase (MNK. MNK activity promotes eIF4F translation initiation complex formation and protein synthesis in mechanistically distinct early and late stages. In early-stage translation, MNK triggers release of the CYFIP1/FMRP repressor complex from the 5′-mRNA cap. In late-stage translation, MNK regulates the canonical translational repressor 4E-BP2 in a synapse-compartment-specific manner. This late stage is coupled to MNK-dependent enhanced dendritic mRNA translation. We conclude that LTP consolidation in the dentate gyrus is mediated by sustained BDNF signaling to MNK and MNK-dependent regulation of translation in two functionally and mechanistically distinct stages.

  2. Teaching Mediated Public Relations.

    Science.gov (United States)

    Kent, Michael L.

    2001-01-01

    Discusses approaches to teaching a mediated public relations course, emphasizing the World Wide Web. Outlines five course objectives, assignments and activities, evaluation, texts, and lecture topics. Argues that students mastering these course objectives will understand ethical issues relating to media use, using mediated technology in public…

  3. Fashion, Mediations & Method Assemblages

    DEFF Research Database (Denmark)

    Sommerlund, Julie; Jespersen, Astrid Pernille

    of handling multiple, fluid realities with multiple, fluid methods. Empirically, the paper works with mediation in fashion - that is efforts the active shaping of relations between producer and consumer through communication, marketing and PR. Fashion mediation is by no means simple, but organise complex...

  4. The Mediated Transparent Society

    DEFF Research Database (Denmark)

    Backer, Lise

    2001-01-01

    in the mediated transparent society. The paper concludes that, based on these analyses, the mediated panopticism working on the business segment is not an effective disciplinary apparatus, which can guarantee that business corporations are carrying out important ecological or ethical improvements....

  5. Laccase/Mediator Systems

    NARCIS (Netherlands)

    Hilgers, Roelant; Vincken, Jean Paul; Gruppen, Harry; Kabel, Mirjam A.

    2018-01-01

    Laccase-mediator systems (LMS) have been widely studied for their capacity to oxidize the nonphenolic subunits of lignin (70-90% of the polymer). The phenolic subunits (10-30% of the polymer), which can also be oxidized without mediators, have received considerably less attention. Consequently, it

  6. Activated RecA protein may induce expression of a gene that is not controlled by the LexA repressor and whose function is required for mutagenesis and repair of UV-irradiated bacteriophage lambda

    International Nuclear Information System (INIS)

    Calsou, P.; Villaverde, A.; Defais, M.

    1987-01-01

    The activated form of the RecA protein (RecA) is known to be involved in the reactivation and mutagenesis of UV-irradiated bacteriophage lambda and in the expression of the SOS response in Escherichia coli K-12. The expression of the SOS response requires cleavage of the LexA repressor by RecA and the subsequent expression of LexA-controlled genes. The evidence presented here suggests that RecA induces the expression of a gene(s) that is not under LexA control and that is also necessary for maximal repair and mutagenesis of damaged phage. This conclusion is based on the chloramphenicol sensitivity of RecA -dependent repair and mutagenesis of damaged bacteriophage lambda in lexA(Def) hosts

  7. The multitalented Mediator complex.

    Science.gov (United States)

    Carlsten, Jonas O P; Zhu, Xuefeng; Gustafsson, Claes M

    2013-11-01

    The Mediator complex is needed for regulated transcription of RNA polymerase II (Pol II)-dependent genes. Initially, Mediator was only seen as a protein bridge that conveyed regulatory information from enhancers to the promoter. Later studies have added many other functions to the Mediator repertoire. Indeed, recent findings show that Mediator influences nearly all stages of transcription and coordinates these events with concomitant changes in chromatin organization. We review the multitude of activities associated with Mediator and discuss how this complex coordinates transcription with other cellular events. We also discuss the inherent difficulties associated with in vivo characterization of a coactivator complex that can indirectly affect diverse cellular processes via changes in gene transcription. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Music, radio and mediatization

    DEFF Research Database (Denmark)

    Michelsen, Morten; Krogh, Mads

    2016-01-01

    of mediatization where media as such seem to be ascribed agency. Instead, we consider historical accounts of music–radio in order to address the complex nonlinearity of concrete processes of mediatization as they take place in the multiple meetings between a decentred notion of radio and musical life.......Mediatization has become a key concept for understanding the relations between media and other cultural and social fields. Contributing to the discussions related to the concept of mediatization, this article discusses how practices of radio and music(al life) influence each other. We follow Deacon......’s and Stanyer’s advice to supplement the concept of mediatization with ‘a series of additional concepts at lower levels of abstraction’ and suggest, in this respect, the notion of heterogeneous milieus of music–radio. Hereby, we turn away from the all-encompassing perspectives related to the concept...

  9. Lysines 72, 80 and 213 and aspartic acid 210 of the Lactococcus lactis LacR repressor are involved in the response to the inducer tagatose-6-phosphate leading to induction of lac operon expression.

    Science.gov (United States)

    van Rooijen, R J; Dechering, K J; Niek, C; Wilmink, J; de Vos, W M

    1993-02-01

    Site-directed mutagenesis of the Lactococcus lactis lacR gene was performed to identify residues in the LacR repressor that are involved in the induction of lacABCDFEGX operon expression by tagatose-6-phosphate. A putative inducer binding domain located near the C-terminus was previously postulated based on homology studies with the Escherichia coli DeoR family of repressors, which all have a phosphorylated sugar as inducer. Residues within this domain and lysine residues that are charge conserved in the DeoR family were changed into alanine or arginine. The production of the LacR mutants K72A, K80A, K80R, D210A, K213A and K213R in the LacR-deficient L.lactis strain NZ3015 resulted in repressed phospho-beta-galactosidase (LacG) activities and decreased growth rates on lactose. Gel mobility shift assays showed that the complex between a DNA fragment carrying the lac operators and LacR mutants K72A, K80A, K213A and D210A did not dissociate in the presence of tagatose-6-phosphate, in contrast to wild type LacR. Other mutations (K62A/K63A, K72R, K73A, K73R, T212A, F214R, R216R and R216K) exhibited no gross effects on inducer response. The results strongly suggest that the lysines at positions 72, 80 and 213 and aspartic acid at position 210 are involved in the induction of lac operon expression by tagatose-6-phosphate.

  10. Nutrient Control of Yeast Gametogenesis Is Mediated by TORC1, PKA and Energy Availability.

    Directory of Open Access Journals (Sweden)

    Hilla Weidberg

    2016-06-01

    Full Text Available Cell fate choices are tightly controlled by the interplay between intrinsic and extrinsic signals, and gene regulatory networks. In Saccharomyces cerevisiae, the decision to enter into gametogenesis or sporulation is dictated by mating type and nutrient availability. These signals regulate the expression of the master regulator of gametogenesis, IME1. Here we describe how nutrients control IME1 expression. We find that protein kinase A (PKA and target of rapamycin complex I (TORC1 signalling mediate nutrient regulation of IME1 expression. Inhibiting both pathways is sufficient to induce IME1 expression and complete sporulation in nutrient-rich conditions. Our ability to induce sporulation under nutrient rich conditions allowed us to show that respiration and fermentation are interchangeable energy sources for IME1 transcription. Furthermore, we find that TORC1 can both promote and inhibit gametogenesis. Down-regulation of TORC1 is required to activate IME1. However, complete inactivation of TORC1 inhibits IME1 induction, indicating that an intermediate level of TORC1 signalling is required for entry into sporulation. Finally, we show that the transcriptional repressor Tup1 binds and represses the IME1 promoter when nutrients are ample, but is released from the IME1 promoter when both PKA and TORC1 are inhibited. Collectively our data demonstrate that nutrient control of entry into sporulation is mediated by a combination of energy availability, TORC1 and PKA activities that converge on the IME1 promoter.

  11. Glucose-mediated repression of autolysis and conidiogenesis in Emericella nidulans.

    Science.gov (United States)

    Emri, Tamás; Molnár, Zsolt; Veres, Tünde; Pusztahelyi, Tünde; Dudás, Gábor; Pócsi, István

    2006-10-01

    Glucose-mediated repression of autolysis and sporulation was studied in submerged Emericellanidulans (anam. Aspergillus nidulans) cultures. Null mutation of the creA gene, which encodes the major carbon catabolite repressor CreA in E. nidulans, resulted in a hyperautolytic phenotype characterized by increased extracellular hydrolase production and dry cell mass declination. Interestingly, glucose, as well as the glucose antimetabolite 2-deoxy-d-glucose, repressed autolysis and sporulation in both the control and the creA null mutant strains suggesting that these processes were also subjected to CreA-independent carbon regulation. For example, the glucose-mediated, but CreA-independent, repression of the sporulation transcription factor BrlA was likely to contribute to the negative regulation of conidiogenesis by glucose. Although CreA played a prominent role in the regulation of autolysis via the repression of genes encoding important autolytic hydrolases like ChiB chitinase and PrtA protease the age-related production of the chitinase activity was also negatively affected by the down-regulation of brlA expression. However, neither CreA-dependent nor CreA-independent elements of carbon regulation affected the initiation and regulation of cell death in E. nidulans under carbon starvation.

  12. General resonance mediation

    International Nuclear Information System (INIS)

    McGarrie, Moritz

    2012-07-01

    We extend the framework of general gauge mediation to cases where the mediating fields have a nontrivial spectral function, as might arise from strong dynamics. We demonstrate through examples that this setup describes a broad class of possible models of gauge mediated supersymmetry breaking. A main emphasis is to give general formulas for cross sections for σ(visible → hidden) in these resonance models. We will also give formulas for soft masses, A-terms and demonstrate the framework with a holographic setup.

  13. General resonance mediation

    Energy Technology Data Exchange (ETDEWEB)

    McGarrie, Moritz

    2012-07-15

    We extend the framework of general gauge mediation to cases where the mediating fields have a nontrivial spectral function, as might arise from strong dynamics. We demonstrate through examples that this setup describes a broad class of possible models of gauge mediated supersymmetry breaking. A main emphasis is to give general formulas for cross sections for {sigma}(visible {yields} hidden) in these resonance models. We will also give formulas for soft masses, A-terms and demonstrate the framework with a holographic setup.

  14. Positively deflected anomaly mediation

    International Nuclear Information System (INIS)

    Okada, Nobuchika

    2002-01-01

    We generalize the so-called 'deflected anomaly mediation' scenario to the case where threshold corrections of heavy messengers to the sparticle squared masses are positive. A concrete model realizing this scenario is also presented. The tachyonic slepton problem can be fixed with only a pair of messengers. The resultant sparticle mass spectrum is quite different from that in the conventional deflected anomaly mediation scenario, but is similar to the one in the gauge mediation scenario. The lightest sparticle is mostly B-ino

  15. Polyarene mediators for mediated redox flow battery

    Science.gov (United States)

    Delnick, Frank M.; Ingersoll, David; Liang, Chengdu

    2018-01-02

    The fundamental charge storage mechanisms in a number of currently studied high energy redox couples are based on intercalation, conversion, or displacement reactions. With exception to certain metal-air chemistries, most often the active redox materials are stored physically in the electrochemical cell stack thereby lowering the practical gravimetric and volumetric energy density as a tradeoff to achieve reasonable power density. In a general embodiment, a mediated redox flow battery includes a series of secondary organic molecules that form highly reduced anionic radicals as reaction mediator pairs for the reduction and oxidation of primary high capacity redox species ex situ from the electrochemical cell stack. Arenes are reduced to stable anionic radicals that in turn reduce a primary anode to the charged state. The primary anode is then discharged using a second lower potential (more positive) arene. Compatible separators and solvents are also disclosed herein.

  16. Making mediation work.

    Science.gov (United States)

    Arif, Zeba

    2016-10-26

    Mediation can be an effective way of solving conflict between staff members. It signifies a willingness for people to work together to discuss their differences in a constructive way, before going down the official grievance route.

  17. Technology-Use Mediation

    DEFF Research Database (Denmark)

    Bansler, Jørgen P.; Havn, Erling C.

    2004-01-01

    Implementation of new computer-mediated communication (CMC) systems in organizations is a complex socio-technical endeavour, involving the mutual adaptation of technology and organization over time. Drawing on the analytic concept of sensemaking, this paper provides a theoretical perspective...... that deepens our understanding of how organizations appropriate new electronic communication media. The paper analyzes how a group of mediators in a large, multinational company adapted a new web-based CMC technology (a virtual workspace) to the local organizational context (and vice versa) by modifying...... features of the technology, providing ongoing support for users, and promoting appropriate conventions of use. We found that these mediators exerted considerable influence on how the technology was established and used in the organization. The mediators were not neutral facilitators of a well...

  18. Understanding Mediation Support

    OpenAIRE

    Lanz, David; Pring, Jamie; von Burg, Corinne; Zeller, Mathias

    2017-01-01

    Recent decades have witnessed increasing institutionalization of mediation support through the establishment of mediation support structures (MSS) within foreign ministries and secretariats of multilateral organizations. This study sheds light on this trend and aims to better understand the emergence, design and development of different MSS. This study analyzes six MSS, namely those established in the United Nations (UN), the Organization for Security and Co-operation in Europe (OSCE), the Eu...

  19. ENVIRONMENTAL CONFLICT MEDIATION

    Directory of Open Access Journals (Sweden)

    GABRIELA G. MIHUT

    2011-04-01

    Full Text Available At a time of global economic crisis followed by resource crisis, a period in which the world seeks alternative resources through eco-investment, environmental conflicts are inevitable. Romania is among the few countries that do not pay enough attention to environmental conflicts and to the advantages to of solving them through mediation procedure. The present paper deals with areas in which conflicts can be applied in environmental mediation and its benefits.

  20. Follistatin-mediated skeletal muscle hypertrophy is regulated by Smad3 and mTOR independently of myostatin

    Science.gov (United States)

    Winbanks, Catherine E.; Weeks, Kate L.; Thomson, Rachel E.; Sepulveda, Patricio V.; Beyer, Claudia; Qian, Hongwei; Chen, Justin L.; Allen, James M.; Lancaster, Graeme I.; Febbraio, Mark A.; Harrison, Craig A.; McMullen, Julie R.; Chamberlain, Jeffrey S.

    2012-01-01

    Follistatin is essential for skeletal muscle development and growth, but the intracellular signaling networks that regulate follistatin-mediated effects are not well defined. We show here that the administration of an adeno-associated viral vector expressing follistatin-288aa (rAAV6:Fst-288) markedly increased muscle mass and force-producing capacity concomitant with increased protein synthesis and mammalian target of rapamycin (mTOR) activation. These effects were attenuated by inhibition of mTOR or deletion of S6K1/2. Furthermore, we identify Smad3 as the critical intracellular link that mediates the effects of follistatin on mTOR signaling. Expression of constitutively active Smad3 not only markedly prevented skeletal muscle growth induced by follistatin but also potently suppressed follistatin-induced Akt/mTOR/S6K signaling. Importantly, the regulation of Smad3- and mTOR-dependent events by follistatin occurred independently of overexpression or knockout of myostatin, a key repressor of muscle development that can regulate Smad3 and mTOR signaling and that is itself inhibited by follistatin. These findings identify a critical role of Smad3/Akt/mTOR/S6K/S6RP signaling in follistatin-mediated muscle growth that operates independently of myostatin-driven mechanisms. PMID:22711699

  1. RecA-mediated cleavage activates UmuD for mutagenesis: Mechanistic relationship between transcriptional derepression and posttranslational activation

    International Nuclear Information System (INIS)

    Nohmi, Takehiko; Battista, J.R.; Dodson, L.A.; Walker, G.C.

    1988-01-01

    The products of the SOS-regulated umuDC operon are required for most UV and chemical mutagenesis in Escherichia coli. It has been shown that the UmuD protein shares homology with LexA, the repressor of the SOS genes. In this paper the authors describe a series of genetic experiments that indicate that the purpose of RecA-mediated cleavage of UmuD at its bond between Cys-24 and Gly-25 is to activate UmuD for its role in mutagenesis and that the COOH-terminal fragment of UmuD is necessary and sufficient for the role of UmuD in UV mutagenesis. Other genetic experiments are presented that (i) support the hypothesis that the primary role of Ser-60 in UmuD function is to act as a nucleophile in the RecA-mediated cleavage reaction and (ii) raise the possibility that RecA has a third role in UV mutagenesis besides mediating the cleavage of LexA and UmuD

  2. Transcription-factor-mediated DNA looping probed by high-resolution, single-molecule imaging in live E. coli cells.

    Directory of Open Access Journals (Sweden)

    Zach Hensel

    Full Text Available DNA looping mediated by transcription factors plays critical roles in prokaryotic gene regulation. The "genetic switch" of bacteriophage λ determines whether a prophage stays incorporated in the E. coli chromosome or enters the lytic cycle of phage propagation and cell lysis. Past studies have shown that long-range DNA interactions between the operator sequences O(R and O(L (separated by 2.3 kb, mediated by the λ repressor CI (accession number P03034, play key roles in regulating the λ switch. In vitro, it was demonstrated that DNA segments harboring the operator sequences formed loops in the presence of CI, but CI-mediated DNA looping has not been directly visualized in vivo, hindering a deep understanding of the corresponding dynamics in realistic cellular environments. We report a high-resolution, single-molecule imaging method to probe CI-mediated DNA looping in live E. coli cells. We labeled two DNA loci with differently colored fluorescent fusion proteins and tracked their separations in real time with ∼40 nm accuracy, enabling the first direct analysis of transcription-factor-mediated DNA looping in live cells. Combining looping measurements with measurements of CI expression levels in different operator mutants, we show quantitatively that DNA looping activates transcription and enhances repression. Further, we estimated the upper bound of the rate of conformational change from the unlooped to the looped state, and discuss how chromosome compaction may impact looping kinetics. Our results provide insights into transcription-factor-mediated DNA looping in a variety of operator and CI mutant backgrounds in vivo, and our methodology can be applied to a broad range of questions regarding chromosome conformations in prokaryotes and higher organisms.

  3. Role of 5'TG3'-interacting factors (TGIFs) in Vorinostat (HDAC inhibitor)-mediated Corneal Fibrosis Inhibition.

    Science.gov (United States)

    Sharma, Ajay; Sinha, Nishant R; Siddiqui, Saad; Mohan, Rajiv R

    2015-01-01

    We have previously reported that vorinostat, an FDA-approved, clinically used histone deacetylase (HDAC) inhibitor, attenuates corneal fibrosis in vivo in rabbits by blocking transforming growth factor β (TGFβ). The 5'TG3'-interacting factors (TGIFs) are transcriptional repressors of TGFβ1 signaling via the Smad pathway. The present study was designed to explore the expression of TGIFs in human corneal fibroblasts and to investigate their role in mediating the antifibrotic effect of vorinostat. Human corneal fibroblast cultures were generated from donor corneas. RNA isolation, cDNA preparation, and PCR were performed to detect the presence of TGIF1 and TGIF2 transcripts. The cultures were exposed to vorinostat (2.5 µM) to test its effect on TGIF mRNA and protein levels using qPCR and immunoblotting. Myofibroblast formation was induced with TGFβ1 (5 ng/ml) treatment under serum-free conditions. The changes in fibrosis parameters were quantified by measuring fibrosis marker α-smooth muscle actin (αSMA) mRNA and protein levels with qPCR, immunostaining, and immunoblotting. Smad2/3/4 and TGIF knockdowns were performed using pre-validated RNAi/siRNAs and a commercially available transfection reagent. Human corneal fibroblasts showed the expression of TGIF1 and TGIF2. Vorinostat (2.5 µM) caused a 2.8-3.3-fold increase in TGIF1 and TGIF2 mRNA levels and a 1.4-1.8-fold increase in TGIF1 and TGIF2 protein levels. Vorinostat treatment also caused a significant increase in acetylhistone H3 and acetylhistone H4. Vorinostat-induced increases in TGIF1 and TGIF2 were accompanied by a concurrent decrease in corneal fibrosis, as indicated by a decrease in αSMA mRNA by 83±7.7% and protein levels by 97±5%. The RNAi-mediated knockdown of Smad2, Smad3, and Smad4 markedly attenuated TGFβ1-evoked transdifferentiation of fibroblasts to myofibroblasts. The siRNA-mediated knockdown of TGIF1 and TGIF2 neutralized vorinostat-evoked decreases in αSMA mRNA by 31%-45% and protein

  4. A nuclear factor I-like activity and a liver-specific repressor govern estrogen-regulated in vitro transcription from the Xenopus laevis vitellogenin B1 promoter.

    Science.gov (United States)

    Corthésy, B; Cardinaux, J R; Claret, F X; Wahli, W

    1989-12-01

    A hormone-controlled in vitro transcription system derived from Xenopus liver nuclear extracts was exploited to identify novel cis-acting elements within the vitellogenin gene B1 promoter region. In addition to the already well-documented estrogen-responsive element (ERE), two elements were found within the 140 base pairs upstream of the transcription initiation site. One of them, a negative regulatory element, is responsible for the lack of promoter activity in the absence of the hormone and, as demonstrated by DNA-binding assays, interacts with a liver-specific transcription factor. The second is required in association with the estrogen-responsive element to mediate hormonal induction and is recognized by the Xenopus liver homolog of nuclear factor I.

  5. mma: An R Package for Mediation Analysis with Multiple Mediators

    OpenAIRE

    Qingzhao Yu; Bin Li

    2017-01-01

    Mediation refers to the effect transmitted by mediators that intervene in the relationship between an exposure and a response variable. Mediation analysis has been broadly studied in many fields. However, it remains a challenge for researchers to consider complicated associations among variables and to differentiate individual effects from multiple mediators. [1] proposed general definitions of mediation effects that were adaptable to all different types of response (categorical or continuous...

  6. Analysis of multiparty mediation processes

    NARCIS (Netherlands)

    Vuković, Siniša

    2013-01-01

    Crucial challenges for multiparty mediation processes include the achievement of adequate cooperation among the mediators and consequent coordination of their activities in the mediation process. Existing literature goes only as far as to make it clear that successful mediation requires necessary

  7. Mediation: The Wise Advocacy

    Directory of Open Access Journals (Sweden)

    Towseef Ahmad

    2016-01-01

    Full Text Available AbstractAdversarial litigation is not the only means of resolving disputes and settling of claims. There are various options. Alternative means of dispute resolution can save money and time, and can help to anchor and resolve the dispute while exploring valuable good offices, amicable approaches and facilitation. Mediation, as used in law, is a process of managing negotiation by a neutral third party in the form of Alternative Dispute Resolution (ADR, as a convenient way of resolving disputes between two or more parties with speediation processes. On the sidelines typically, a neutral third party, the mediator assists the parties to negotiate a settlement. The term “mediation” broadly refers to any instance in which a neutral third party helps others to reach an amicable and mutually acceptable agreement. More specifically, mediation has a structure, timetable and dynamic approaches that “ordinary” negotiations usually lack. The process helps the parties to flourish the healthy ideas which are different and distinct from the legal rights in a Court of law. It is well known in International Law also and disputants can submit their disputes to mediation in a variety of matters such as commercial, legal, diplomatic, workplace, community and family matters, which assumes a great significance and it is bricolaged within the framework of this article.Keywords: Adversarial, Litigation, Mediation, Negotiation and Amicable.

  8. Decreased expression of Freud-1/CC2D1A, a transcriptional repressor of the 5-HT1A receptor, in the prefrontal cortex of subjects with major depression.

    Science.gov (United States)

    Szewczyk, Bernadeta; Albert, Paul R; Rogaeva, Anastasia; Fitzgibbon, Heidi; May, Warren L; Rajkowska, Grazyna; Miguel-Hidalgo, Jose J; Stockmeier, Craig A; Woolverton, William L; Kyle, Patrick B; Wang, Zhixia; Austin, Mark C

    2010-09-01

    Serotonin1A (5-HT(1A)) receptors are reported altered in the brain of subjects with major depressive disorder (MDD). Recent studies have identified transcriptional regulators of the 5-HT(1A) receptor and have documented gender-specific alterations in 5-HT(1A) transcription factor and 5-HT(1A) receptors in female MDD subjects. The 5' repressor element under dual repression binding protein-1 (Freud-1) is a calcium-regulated repressor that negatively regulates the 5-HT(1A) receptor gene. This study documented the cellular expression of Freud-1 in the human prefrontal cortex (PFC) and quantified Freud-1 protein in the PFC of MDD and control subjects as well as in the PFC of rhesus monkeys chronically treated with fluoxetine. Freud-1 immunoreactivity was present in neurons and glia and was co-localized with 5-HT(1A) receptors. Freud-1 protein level was significantly decreased in the PFC of male MDD subjects (37%, p=0.02) relative to gender-matched control subjects. Freud-1 protein was also reduced in the PFC of female MDD subjects (36%, p=0.18) but was not statistically significant. When the data was combined across genders and analysed by age, the decrease in Freud-1 protein level was greater in the younger MDD subjects (48%, p=0.01) relative to age-matched controls as opposed to older depressed subjects. Similarly, 5-HT(1A) receptor protein was significantly reduced in the PFC of the younger MDD subjects (48%, p=0.01) relative to age-matched controls. Adult male rhesus monkeys administered fluoxetine daily for 39 wk revealed no significant change in cortical Freud-1 or 5-HT(1A) receptor proteins compared to vehicle-treated control monkeys. Reduced protein expression of Freud-1 in MDD subjects may reflect dysregulation of this transcription factor, which may contribute to the altered regulation of 5-HT(1A) receptors observed in subjects with MDD. These data may also suggest that reductions in Freud-1 protein expression in the PFC may be associated with early onset of

  9. Immunologically mediated oral diseases.

    Science.gov (United States)

    Jimson, Sudha; Balachader, N; Anita, N; Babu, R

    2015-04-01

    Immune mediated diseases of oral cavity are uncommon. The lesions may be self-limiting and undergo remission spontaneously. Among the immune mediated oral lesions the most important are lichen planus, pemphigus, erythema multiformi, epidermolysis bullosa, systemic lupus erythematosis. Cellular and humoral mediated immunity play a major role directed against epithelial and connective tissue in chronic and recurrent patterns. Confirmatory diagnosis can be made by biopsy, direct and indirect immunoflouresence, immune precipitation and immunoblotting. Therapeutic agents should be selected after thorough evaluation of immune status through a variety of tests and after determining any aggravating or provoking factors. Early and appropriate diagnosis is important for proper treatment planning contributing to better prognosis and better quality of life of patient.

  10. Immunologically mediated oral diseases

    Directory of Open Access Journals (Sweden)

    Sudha Jimson

    2015-01-01

    Full Text Available Immune mediated diseases of oral cavity are uncommon. The lesions may be self-limiting and undergo remission spontaneously. Among the immune mediated oral lesions the most important are lichen planus, pemphigus, erythema multiformi, epidermolysis bullosa, systemic lupus erythematosis. Cellular and humoral mediated immunity play a major role directed against epithelial and connective tissue in chronic and recurrent patterns. Confirmatory diagnosis can be made by biopsy, direct and indirect immunoflouresence, immune precipitation and immunoblotting. Therapeutic agents should be selected after thorough evaluation of immune status through a variety of tests and after determining any aggravating or provoking factors. Early and appropriate diagnosis is important for proper treatment planning contributing to better prognosis and better quality of life of patient.

  11. Causal mediation analysis with multiple causally non-ordered mediators.

    Science.gov (United States)

    Taguri, Masataka; Featherstone, John; Cheng, Jing

    2018-01-01

    In many health studies, researchers are interested in estimating the treatment effects on the outcome around and through an intermediate variable. Such causal mediation analyses aim to understand the mechanisms that explain the treatment effect. Although multiple mediators are often involved in real studies, most of the literature considered mediation analyses with one mediator at a time. In this article, we consider mediation analyses when there are causally non-ordered multiple mediators. Even if the mediators do not affect each other, the sum of two indirect effects through the two mediators considered separately may diverge from the joint natural indirect effect when there are additive interactions between the effects of the two mediators on the outcome. Therefore, we derive an equation for the joint natural indirect effect based on the individual mediation effects and their interactive effect, which helps us understand how the mediation effect works through the two mediators and relative contributions of the mediators and their interaction. We also discuss an extension for three mediators. The proposed method is illustrated using data from a randomized trial on the prevention of dental caries.

  12. Ultraviolet radiation-induced interleukin 6 release in HeLa cells is mediated via membrane events in a DNA damage-independent way.

    Science.gov (United States)

    Kulms, D; Pöppelmann, B; Schwarz, T

    2000-05-19

    Evidence exists that ultraviolet radiation (UV) affects molecular targets in the nucleus or at the cell membrane. UV-induced apoptosis was found to be mediated via DNA damage and activation of death receptors, suggesting that nuclear and membrane effects are not mutually exclusive. To determine whether participation of nuclear and membrane components is also essential for other UV responses, we studied the induction of interleukin-6 (IL-6) by UV. Exposing HeLa cells to UV at 4 degrees C, which inhibits activation of surface receptors, almost completely prevented IL-6 release. Enhanced repair of UV-mediated DNA damage by addition of the DNA repair enzyme photolyase did not affect UV-induced IL-6 production, suggesting that in this case membrane events predominant over nuclear effects. UV-induced IL-6 release is mediated via NFkappaB since the NFkappaB inhibitor MG132 or transfection of cells with a super-repressor form of the NFkappaB inhibitor IkappaB reduced IL-6 release. Transfection with a dominant negative mutant of the signaling protein TRAF-2 reduced IL-6 release upon exposure to UV, indicating that UV-induced IL-6 release is mediated by activation of the tumor necrosis factor receptor-1. These data demonstrate that UV can exert biological effects mainly by affecting cell surface receptors and that this is independent of its ability to induce nuclear DNA damage.

  13. Skeletal muscle protein synthesis and the abundance of the mRNA translation initiation repressor PDCD4 are inversely regulated by fasting and refeeding in rats.

    Science.gov (United States)

    Zargar, Sana; Moreira, Tracy S; Samimi-Seisan, Helena; Jeganathan, Senthure; Kakade, Dhanshri; Islam, Nushaba; Campbell, Jonathan; Adegoke, Olasunkanmi A J

    2011-06-01

    Optimal skeletal muscle mass is vital to human health, because defects in muscle protein metabolism underlie or exacerbate human diseases. The mammalian target of rapamycin complex 1 is critical in the regulation of mRNA translation and protein synthesis. These functions are mediated in part by the ribosomal protein S6 kinase 1 (S6K1) through mechanisms that are poorly understood. The tumor suppressor programmed cell death 4 (PDCD4) has been identified as a novel substrate of S6K1. Here, we examined 1) the expression of PDCD4 in skeletal muscle and 2) its regulation by feed deprivation (FD) and refeeding. Male rats (~100 g; n = 6) were subjected to FD for 48 h; some rats were refed for 2 h. FD suppressed muscle fractional rates of protein synthesis and Ser(67) phosphorylation of PDCD4 (-50%) but increased PDCD4 abundance (P muscle fractional rates of protein synthesis and reduced PDCD4 abundance relative to FD. Finally, when myoblasts were grown in amino acid- and serum-free medium, phenylalanine incorporation into proteins in cells depleted of PDCD4 more than doubled the values in cells with a normal level of PDCD4 (P skeletal muscle in parallel with the reduction of the abundance of this mRNA translation inhibitor.

  14. Polycomb group protein-mediated repression of transcription

    DEFF Research Database (Denmark)

    Morey, Lluís; Helin, Kristian

    2010-01-01

    The polycomb group (PcG) proteins are essential for the normal development of multicellular organisms. They form multi-protein complexes that work as transcriptional repressors of several thousand genes controlling differentiation pathways during development. How the PcG proteins work as transcri......The polycomb group (PcG) proteins are essential for the normal development of multicellular organisms. They form multi-protein complexes that work as transcriptional repressors of several thousand genes controlling differentiation pathways during development. How the PcG proteins work...... as transcriptional repressors is incompletely understood, but involves post-translational modifications of histones by two major PcG protein complexes: polycomb repressive complex 1 and polycomb repressive complex 2....

  15. Nucleosome mediated crosstalk between transcription factors at eukaryotic enhancers

    International Nuclear Information System (INIS)

    Teif, Vladimir B; Rippe, Karsten

    2011-01-01

    A recent study of transcription regulation in Drosophila embryonic development revealed a complex non-monotonic dependence of gene expression on the distance between binding sites of repressor and activator proteins at the corresponding enhancer cis-regulatory modules (Fakhouri et al 2010 Mol. Syst. Biol. 6 341). The repressor efficiency was high at small separations, low around 30 bp, reached a maximum at 50–60 bp, and decreased at larger distances to the activator binding sites. Here, we propose a straightforward explanation for the distance dependence of repressor activity by considering the effect of the presence of a nucleosome. Using a method that considers partial unwrapping of nucleosomal DNA from the histone octamer core, we calculated the dependence of activator binding on the repressor–activator distance and found a quantitative agreement with the distance dependence reported for the Drosophila enhancer element. In addition, the proposed model offers explanations for other distance-dependent effects at eukaryotic enhancers. (communication)

  16. ZEB1 Mediates Drug Resistance and EMT in p300-Deficient CRC.

    Science.gov (United States)

    Lazarova, Darina; Bordonaro, Michael

    2017-01-01

    We discuss the hypothesis that ZEB1-Wnt-p300 signaling integrates epithelial to mesenchymal transition (EMT) and resistance to histone deacetylase inhibitors (HDACis) in colorectal cancer (CRC) cells. The HDACi butyrate, derived from dietary fiber, has been linked to CRC prevention, and other HDACis have been proposed as therapeutic agents against CRC. We have previously discussed that resistance to butyrate likely contributes to colonic carcinogenesis, and we have demonstrated that butyrate resistance leads to cross-resistance to cancer therapeutic HDACis. Deregulated Wnt signaling is the major initiating event in most CRC cases. One mechanism whereby butyrate and other HDACis exert their anti-CRC effects is via Wnt signaling hyperactivation, which promotes CRC cell apoptosis. The histone acetylases (HATs) CBP and p300 are mediators of Wnt transcriptional activity, and play divergent roles in the downstream consequences of Wnt signaling. CBP-mediated Wnt signaling is associated with cell proliferation and stem cell maintenance; whereas, p300-mediated Wnt activity is associated with differentiation. We have found that CBP and p300 differentially affect the ability of butyrate to influence Wnt signaling, apoptosis, and proliferation. ZEB 1 is a Wnt signaling-targeted gene, whose product is a transcription factor expressed at the invasive front of carcinomas where it promotes malignant progression and EMT. ZEB1 is typically a transcriptional repressor; however, when associated with p300, ZEB1 enhances transcription. These changes in ZEB1 activity likely affect the cancer cell phenotype. ZEB1 has been shown to promote resistance to chemotherapeutic agents, and expression of ZEB1 is upregulated in butyrate-resistant CRC cells that lack p300 expression. Since the expression of ZEB1 correlates with poor outcomes in cancer, ZEB represents a relevant therapeutic target. Here we propose that targeting the signaling network established by ZEB1, Wnt signaling, and p300

  17. Mediation analysis with time varying exposures and mediators.

    Science.gov (United States)

    VanderWeele, Tyler J; Tchetgen Tchetgen, Eric J

    2017-06-01

    In this paper we consider causal mediation analysis when exposures and mediators vary over time. We give non-parametric identification results, discuss parametric implementation, and also provide a weighting approach to direct and indirect effects based on combining the results of two marginal structural models. We also discuss how our results give rise to a causal interpretation of the effect estimates produced from longitudinal structural equation models. When there are time-varying confounders affected by prior exposure and mediator, natural direct and indirect effects are not identified. However, we define a randomized interventional analogue of natural direct and indirect effects that are identified in this setting. The formula that identifies these effects we refer to as the "mediational g-formula." When there is no mediation, the mediational g-formula reduces to Robins' regular g-formula for longitudinal data. When there are no time-varying confounders affected by prior exposure and mediator values, then the mediational g-formula reduces to a longitudinal version of Pearl's mediation formula. However, the mediational g-formula itself can accommodate both mediation and time-varying confounders and constitutes a general approach to mediation analysis with time-varying exposures and mediators.

  18. When Memories are Mediated

    DEFF Research Database (Denmark)

    Frølunde, Lisbeth; Bjerregaard, Mette

    2013-01-01

    that are mediated through stories: told and retold as oral stories through generations, as myths or sagas, or remediated as contemporary documentary film accounts or more fictional film accounts. In these processes of retelling acts of violence, transformations of meanings across time, cultural, social...

  19. Mediated Cultural Memories

    DEFF Research Database (Denmark)

    Frølunde, Lisbeth; Bjerregaard, Mette

    2013-01-01

    generations. Acts of mass violence also construct a sort of looking glass of culturally dominant memories that are mediated through stories: retold as oral stories through generations, as myths or sagas, or remediated in contemporary documentary or fiction films. In these processes of retelling acts...

  20. Cultural mediation in museums

    Directory of Open Access Journals (Sweden)

    Gherghina Boda

    2017-12-01

    Full Text Available If we perceive the museum not only as a place of storing and conserving the patrimony, but also of transmitting it, then we can also see it as a mediator through which cultures can become collective patrimony. Tightly connected to patrimonial appropriation, mediation appears from this perspective as a process and not an end, as it manifests itself in animation, communication and making knowledge popular in relation to a precise patrimony. That is why we can see cultural mediation as a transmission, as a transformation, as an action or social project which aims at creating social bonds, the museum thus being not only a place of meeting for the public with the objects exposed, but also as a place of meeting between different cultures. Thus, cultural mediation presents itself as the most efficient means for access to culture of all categories of the public, situated as the crossroads of culture, continuous education and entertainment and is inscribed in the field of informal education.

  1. The Bensberg Mediation Model

    Directory of Open Access Journals (Sweden)

    Raluca - Marilena Mihalcioiu

    2011-05-01

    Full Text Available The basis of the conflict through the mediation represents the objectives and procedures ofmediation, mediation of a conflict. The conflict will not be disclosed to others, but the parties will be creditedthe authority to resolve the conflict, the conflict among themselves with the help of a mediator. The disputeshould be resolved by the parties with help of a third party. The parties in conflict (it may be several personsare jointly responsible for the solution. They seek together a way that leads to long-term settlement of theconflict. The assumption of responsibility in this process strengthens the confidence and the importance oftheir decision. Important is that losers usually have no peace, because they are out for revenge. Winners don’tneed peace. If both parties lose, remains disappointing, with the understanding of which the conflict isresolved, will understand each other better developed. Reconciliation is therefore a longer-term goal.Conflicts also help to clarify roles. The paper presents Bensberg Model of Mediation, because this isdeveloped as a win win solution and his possible implementation in Romanian schools.

  2. Hormonal regulation and developmental role of Krüppel homolog 1, a repressor of metamorphosis, in the silkworm Bombyx mori.

    Science.gov (United States)

    Kayukawa, Takumi; Murata, Mika; Kobayashi, Isao; Muramatsu, Daisuke; Okada, Chieko; Uchino, Keiro; Sezutsu, Hideki; Kiuchi, Makoto; Tamura, Toshiki; Hiruma, Kiyoshi; Ishikawa, Yukio; Shinoda, Tetsuro

    2014-04-01

    Juvenile hormone (JH) has an ability to repress the precocious metamorphosis of insects during their larval development. Krüppel homolog 1 (Kr-h1) is an early JH-inducible gene that mediates this action of JH; however, the fine hormonal regulation of Kr-h1 and the molecular mechanism underlying its antimetamorphic effect are little understood. In this study, we attempted to elucidate the hormonal regulation and developmental role of Kr-h1. We found that the expression of Kr-h1 in the epidermis of penultimate-instar larvae of the silkworm Bombyx mori was induced by JH secreted by the corpora allata (CA), whereas the CA were not involved in the transient induction of Kr-h1 at the prepupal stage. Tissue culture experiments suggested that the transient peak of Kr-h1 at the prepupal stage is likely to be induced cooperatively by JH derived from gland(s) other than the CA and the prepupal surge of ecdysteroid, although involvement of unknown factor(s) could not be ruled out. To elucidate the developmental role of Kr-h1, we generated transgenic silkworms overexpressing Kr-h1. The transgenic silkworms grew normally until the spinning stage, but their development was arrested at the prepupal stage. The transgenic silkworms from which the CA were removed in the penultimate instar did not undergo precocious pupation or larval-larval molt but fell into prepupal arrest. This result demonstrated that Kr-h1 is indeed involved in the repression of metamorphosis but that Kr-h1 alone is incapable of implementing normal larval molt. Moreover, the expression profiles and hormonal responses of early ecdysone-inducible genes (E74, E75, and Broad) in transgenic silkworms suggested that Kr-h1 is not involved in the JH-dependent modulation of these genes, which is associated with the control of metamorphosis. Copyright © 2014 Elsevier Inc. All rights reserved.

  3. Proto-oncogene FBI-1 (Pokemon/ZBTB7A) Represses Transcription of the Tumor Suppressor Rb Gene via Binding Competition with Sp1 and Recruitment of Co-repressors*S⃞

    Science.gov (United States)

    Jeon, Bu-Nam; Yoo, Jung-Yoon; Choi, Won-Il; Lee, Choong-Eun; Yoon, Ho-Geun; Hur, Man-Wook

    2008-01-01

    FBI-1 (also called Pokemon/ZBTB7A) is a BTB/POZ-domain Krüppel-like zinc-finger transcription factor. Recently, FBI-1 was characterized as a proto-oncogenic protein, which represses tumor suppressor ARF gene transcription. The expression of FBI-1 is increased in many cancer tissues. We found that FBI-1 potently represses transcription of the Rb gene, a tumor suppressor gene important in cell cycle arrest. FBI-1 binds to four GC-rich promoter elements (FREs) located at bp –308 to –188 of the Rb promoter region. The Rb promoter also contains two Sp1 binding sites: GC-box 1 (bp –65 to –56) and GC-box 2 (bp –18 to –9), the latter of which is also bound by FBI-1. We found that FRE3 (bp –244 to –236) is also a Sp1 binding element. FBI-1 represses transcription of the Rb gene not only by binding to the FREs, but also by competing with Sp1 at the GC-box 2 and the FRE3. By binding to the FREs and/or the GC-box, FBI-1 represses transcription of the Rb gene through its POZ-domain, which recruits a co-repressor-histone deacetylase complex and deacetylates histones H3 and H4 at the Rb gene promoter. FBI-1 inhibits C2C12 myoblast cell differentiation by repressing Rb gene expression. PMID:18801742

  4. CalA, a Cyanobacterial AbrB Protein, Interacts with the Upstream Region of hypC and Acts as a Repressor of Its Transcription in the Cyanobacterium Nostoc sp. Strain PCC 7120▿ †

    Science.gov (United States)

    Agervald, Åsa; Zhang, Xiaohui; Stensjö, Karin; Devine, Ellenor; Lindblad, Peter

    2010-01-01

    The filamentous, heterocystous, nitrogen-fixing cyanobacterium Nostoc sp. strain PCC 7120 may contain, depending on growth conditions, up to two hydrogenases directly involved in hydrogen metabolism. HypC is one out of at least seven auxiliary gene products required for synthesis of a functional hydrogenase, specifically involved in the maturation of the large subunit. In this study we present a protein, CalA (Alr0946 in the genome), belonging to the transcription regulator family AbrB, which in protein-DNA assays was found to interact with the upstream region of hypC. Transcriptional investigations showed that calA is cotranscribed with the downstream gene alr0947, which encodes a putative protease from the abortive infection superfamily, Abi. CalA was shown to interact specifically not only with the upstream region of hypC but also with its own upstream region, acting as a repressor on hypC. The bidirectional hydrogenase activity was significantly downregulated when CalA was overexpressed, demonstrating a correlation with the transcription factor, either direct or indirect. In silico studies showed that homologues to both CalA and Alr0947 are highly conserved proteins within cyanobacteria with very similar physical organizations of the corresponding structural genes. Possible functions of the cotranscribed downstream protein Alr0947 are presented. In addition, we present a three-dimensional (3D) model of the DNA binding domain of CalA and putative DNA binding mechanisms are discussed. PMID:20023111

  5. mTORC1 Targets the Translational Repressor 4E-BP2, but Not S6 Kinase 1/2, to Regulate Neural Stem Cell Self-Renewal In Vivo

    Directory of Open Access Journals (Sweden)

    Nathaniel W. Hartman

    2013-10-01

    Full Text Available The mammalian target of rapamycin complex 1 (mTORC1 integrates signals important for cell growth, and its dysregulation in neural stem cells (NSCs is implicated in several neurological disorders associated with abnormal neurogenesis and brain size. However, the function of mTORC1 on NSC self-renewal and the downstream regulatory mechanisms are ill defined. Here, we found that genetically decreasing mTORC1 activity in neonatal NSCs prevented their differentiation, resulting in reduced lineage expansion and aborted neuron production. Constitutive activation of the translational repressor 4E-BP1, which blocked cap-dependent translation, had similar effects and prevented hyperactive mTORC1 induction of NSC differentiation and promoted self-renewal. Although 4E-BP2 knockdown promoted NSC differentiation, p70 S6 kinase 1 and 2 (S6K1/S6K2 knockdown did not affect NSC differentiation but reduced NSC soma size and prevented hyperactive mTORC1-induced increase in soma size. These data demonstrate a crucial role of mTORC1 and 4E-BP for switching on and off cap-dependent translation in NSC differentiation.

  6. The Transcriptional Repressor, MtrR, of the mtrCDE Efflux Pump Operon of Neisseria gonorrhoeae Can Also Serve as an Activator of “off Target” Gene (glnE Expression

    Directory of Open Access Journals (Sweden)

    Paul J. T. Johnson

    2015-06-01

    Full Text Available MtrR is a well-characterized repressor of the Neisseria gonorrhoeae mtrCDE efflux pump operon. However, results from a previous transcriptional profiling study suggested that MtrR also represses or activates expression of at least sixty genes outside of the mtr locus. Evidence that MtrR can directly repress so-called “off target” genes has previously been reported; in particular, MtrR was shown to directly repress glnA, which encodes glutamine synthetase. In contrast, evidence for the ability of MtrR to directly activate expression of gonococcal genes has been lacking; herein, we provide such evidence. We now report that MtrR has the ability to directly activate expression of glnE, which encodes the dual functional adenyltransferase/deadenylase enzyme GlnE that modifies GlnA resulting in regulation of its role in glutamine biosynthesis. With its capacity to repress expression of glnA, the results presented herein emphasize the diverse and often opposing regulatory properties of MtrR that likely contributes to the overall physiology and metabolism of N. gonorrhoeae.

  7. PigZ, a TetR/AcrR family repressor, modulates secondary metabolism via the expression of a putative four-component resistance-nodulation-cell-division efflux pump, ZrpADBC, in Serratia sp. ATCC 39006.

    Science.gov (United States)

    Gristwood, Tamzin; Fineran, Peter C; Everson, Lee; Salmond, George P C

    2008-07-01

    The Gram-negative enterobacterium, Serratia sp. ATCC 39006 synthesizes several secondary metabolites, including prodigiosin (Pig) and a carbapenem antibiotic (Car). A complex hierarchical network of regulatory proteins control Pig and Car production. In this study we characterize a TetR family regulator, PigZ, which represses transcription of a divergently transcribed putative resistance-nodulation-cell-division (RND) efflux pump, encoded by zrp (PigZ repressed pump) ADBC, via direct binding to the zrpA-pigZ intergenic region. Unusually, this putative RND pump contains two predicted membrane fusion proteins (MFPs), ZrpA and ZrpD. A mutation in pigZ resulted in multiple phenotypic changes, including exoenzyme production, motility and differential regulation of Pig and Car production. A polar suppressor mutation, within zrpA, restored all tested phenotypes to parental strain levels, indicating that the changes observed are due to the increase in expression of ZrpADBC in the absence of the repressor, PigZ. Genomic deletions of zrpA and zrpD indicate that the MFP ZrpD, but not ZrpA, is essential for activity of the putative pump. Bioinformatic analysis revealed that putative RND efflux pumps encoding two MFP components are not uncommon, particularly among plant-associated, Gram-negative bacteria. In addition, based on phylogenetic analysis, we propose that these pairs of MFPs consist of two distinct subtypes.

  8. Axionic mirage mediation

    International Nuclear Information System (INIS)

    Nakamura, Shuntaro; Okumura, Ken-ichi; Yamaguchi, Masahiro

    2008-01-01

    Although mirage mediation is one of the most plausible mediation mechanisms of supersymmetry breaking, it suffers from two crucial problems. One is the μ/Bμ problem, and the second is the cosmological one. The former stems from the fact that the B parameter tends to be comparable with the gravitino mass, which is 2 orders of magnitude larger than the other soft masses. The latter problem is caused by the decay of the modulus whose branching ratio into the gravitino pair is sizable. In this paper, we propose a model of mirage mediation, in which Peccei-Quinn symmetry is incorporated. In this axionic mirage mediation, it is shown that the Peccei-Quinn symmetry breaking scale is dynamically determined around 10 10 GeV to 10 12 GeV due to the supersymmetry breaking effects, and the μ problem can be solved naturally. Furthermore, in our model, the lightest supersymmetric particle (LSP) is the axino, that is, the superpartner of the axion. The overabundance of the LSPs due to decays of the modulus/gravitino, which is the most serious cosmological difficulty in the mirage mediation, can be avoided if the axino is sufficiently light. The next-LSPs (NLSPs) produced by the gravitino decay eventually decay into the axino LSPs, yielding the dominant component of the axinos remaining today. It is shown that the axino with a mass of O(100) MeV is naturally realized, which can constitute the dark matter of the Universe, with a free-streaming length of the order of 0.1 Mpc. The saxion, the real scalar component of the axion supermultiplet, can also be cosmologically harmless due to the dilution of the modulus decay. The lifetime of the NLSP is relatively long, but much shorter than 1 sec, when the big-bang nucleosynthesis commences. The decay of the NLSP would provide intriguing collider signatures

  9. Interventional Effects for Mediation Analysis with Multiple Mediators.

    Science.gov (United States)

    Vansteelandt, Stijn; Daniel, Rhian M

    2017-03-01

    The mediation formula for the identification of natural (in)direct effects has facilitated mediation analyses that better respect the nature of the data, with greater consideration of the need for confounding control. The default assumptions on which it relies are strong, however. In particular, they are known to be violated when confounders of the mediator-outcome association are affected by the exposure. This complicates extensions of counterfactual-based mediation analysis to settings that involve repeatedly measured mediators, or multiple correlated mediators. VanderWeele, Vansteelandt, and Robins introduced so-called interventional (in)direct effects. These can be identified under much weaker conditions than natural (in)direct effects, but have the drawback of not adding up to the total effect. In this article, we adapt their proposal to achieve an exact decomposition of the total effect, and extend it to the multiple mediator setting. Interestingly, the proposed effects capture the path-specific effects of an exposure on an outcome that are mediated by distinct mediators, even when-as often-the structural dependence between the multiple mediators is unknown, for instance, when the direction of the causal effects between the mediators is unknown, or there may be unmeasured common causes of the mediators.

  10. Mediation analysis with multiple versions of the mediator.

    Science.gov (United States)

    Vanderweele, Tyler J

    2012-05-01

    The causal inference literature has provided definitions of direct and indirect effects based on counterfactuals that generalize the approach found in the social science literature. However, these definitions presuppose well-defined hypothetical interventions on the mediator. In many settings, there may be multiple ways to fix the mediator to a particular value, and these various hypothetical interventions may have very different implications for the outcome of interest. In this paper, we consider mediation analysis when multiple versions of the mediator are present. Specifically, we consider the problem of attempting to decompose a total effect of an exposure on an outcome into the portion through the intermediate and the portion through other pathways. We consider the setting in which there are multiple versions of the mediator but the investigator has access only to data on the particular measurement, not information on which version of the mediator may have brought that value about. We show that the quantity that is estimated as a natural indirect effect using only the available data does indeed have an interpretation as a particular type of mediated effect; however, the quantity estimated as a natural direct effect, in fact, captures both a true direct effect and an effect of the exposure on the outcome mediated through the effect of the version of the mediator that is not captured by the mediator measurement. The results are illustrated using 2 examples from the literature, one in which the versions of the mediator are unknown and another in which the mediator itself has been dichotomized.

  11. The catabolite repressor/activator, Cra, bridges a connection between carbon metabolism and host colonization in the plant drought resistance-promoting bacterium Pantoea alhagi LTYR-11Z.

    Science.gov (United States)

    Zhang, Lei; Li, Muhang; Li, Qiqi; Chen, Chaoqiong; Qu, Meng; Li, Mengyun; Wang, Yao; Shen, Xihui

    2018-04-27

    respond to specific environmental cues. The most common is nutrient availability. In this work, we unraveled the pivotal role of Cra in regulation of colonization ability of Pantoea alhagi LTYR-11Z in response to carbon source availability. Moreover, we identified three novel members of the Cra regulon involved in EPS synthesis, regulation of flagellar biosynthesis, and synthesis of c-di-GMP, and propose a working model to explain the Cra-mediated regulatory mechanism that links carbon metabolism to host colonization. This study elucidates the regulatory role of Cra in bacterial attachment and colonization of plants, which raises the possibility to extend our studies to other bacteria associated with plant and human health. Copyright © 2018 American Society for Microbiology.

  12. DNA replication factor C1 mediates genomic stability and transcriptional gene silencing in Arabidopsis

    KAUST Repository

    Liu, Qian; Wang, Junguo; Miki, Daisuke; Xia, Ran; Yu, Wenxiang; He, Junna; Zheng, Zhimin; Zhu, Jian-Kang; Gonga, Zhizhong

    2010-01-01

    Genetic screening identified a suppressor of ros1-1, a mutant of REPRESSOR OF SILENCING1 (ROS1; encoding a DNA demethylation protein). The suppressor is a mutation in the gene encoding the largest subunit of replication factor C (RFC1). This mutation of RFC1 reactivates the unlinked 35S-NPTII transgene, which is silenced in ros1 and also increases expression of the pericentromeric Athila retrotransposons named transcriptional silent information in a DNA methylationindependent manner. rfc1 is more sensitive than the wild type to the DNA-damaging agent methylmethane sulphonate and to the DNA inter- and intra- cross-linking agent cisplatin. The rfc1 mutant constitutively expresses the G2/M-specific cyclin CycB1;1 and other DNA repair-related genes. Treatment with DNA-damaging agents mimics the rfc1 mutation in releasing the silenced 35S-NPTII, suggesting that spontaneously induced genomic instability caused by the rfc1 mutation might partially contribute to the released transcriptional gene silencing (TGS). The frequency of somatic homologous recombination is significantly increased in the rfc1 mutant. Interestingly, ros1 mutants show increased telomere length, but rfc1 mutants show decreased telomere length and reduced expression of telomerase. Our results suggest that RFC1 helps mediate genomic stability and TGS in Arabidopsis thaliana. © 2010 American Society of Plant Biologists.

  13. Snail recruits Ring1B to mediate transcriptional repression and cell migration in pancreatic cancer cells.

    Science.gov (United States)

    Chen, Jiangzhi; Xu, Hong; Zou, Xiuqun; Wang, Jiamin; Zhu, Yi; Chen, Hao; Shen, Baiyong; Deng, Xiaxing; Zhou, Aiwu; Chin, Y Eugene; Rauscher, Frank J; Peng, Chenghong; Hou, Zhaoyuan

    2014-08-15

    Transcriptional repressor Snail is a master regulator of epithelial-mesenchymal transition (EMT), yet the epigenetic mechanism governing Snail to induce EMT is not well understood. Here, we report that in pancreatic ductal adenocarcinoma (PDAC), elevated levels of the ubiquitin E3 ligase Ring1B and Snail, along with elevated monoubiquitination of H2A at K119 (H2AK119Ub1), are highly correlated with poor survival. Mechanistic investigations identified Ring1B as a Snail-interacting protein and showed that the carboxyl zinc fingers of Snail recruit Ring1B and its paralog Ring1A to repress its target promoters. Simultaneous depletion of Ring1A and Ring1B in pancreatic cancer cells decreased Snail binding to the target chromatin, abolished H2AK119Ub1 modification, and thereby compromised Snail-mediated transcriptional repression and cell migration. We found that Ring1B and the SNAG-associated chromatin modifier EZH2 formed distinct protein complexes with Snail and that EZH2 was required for Snail-Ring1A/B recruitment to the target promoter. Collectively, our results unravel an epigenetic mechanism underlying transcriptional repression by Snail, suggest Ring1A/B as a candidate therapeutic target, and identify H2AK119Ub1 as a potential biomarker for PDAC diagnosis and prognosis. ©2014 American Association for Cancer Research.

  14. DNA replication factor C1 mediates genomic stability and transcriptional gene silencing in Arabidopsis

    KAUST Repository

    Liu, Qian

    2010-07-01

    Genetic screening identified a suppressor of ros1-1, a mutant of REPRESSOR OF SILENCING1 (ROS1; encoding a DNA demethylation protein). The suppressor is a mutation in the gene encoding the largest subunit of replication factor C (RFC1). This mutation of RFC1 reactivates the unlinked 35S-NPTII transgene, which is silenced in ros1 and also increases expression of the pericentromeric Athila retrotransposons named transcriptional silent information in a DNA methylationindependent manner. rfc1 is more sensitive than the wild type to the DNA-damaging agent methylmethane sulphonate and to the DNA inter- and intra- cross-linking agent cisplatin. The rfc1 mutant constitutively expresses the G2/M-specific cyclin CycB1;1 and other DNA repair-related genes. Treatment with DNA-damaging agents mimics the rfc1 mutation in releasing the silenced 35S-NPTII, suggesting that spontaneously induced genomic instability caused by the rfc1 mutation might partially contribute to the released transcriptional gene silencing (TGS). The frequency of somatic homologous recombination is significantly increased in the rfc1 mutant. Interestingly, ros1 mutants show increased telomere length, but rfc1 mutants show decreased telomere length and reduced expression of telomerase. Our results suggest that RFC1 helps mediate genomic stability and TGS in Arabidopsis thaliana. © 2010 American Society of Plant Biologists.

  15. 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.

  16. Current Directions in Mediation Analysis

    Science.gov (United States)

    MacKinnon, David P.; Fairchild, Amanda J.

    2010-01-01

    Mediating variables continue to play an important role in psychological theory and research. A mediating variable transmits the effect of an antecedent variable on to a dependent variable, thereby providing more detailed understanding of relations among variables. Methods to assess mediation have been an active area of research for the last two decades. This paper describes the current state of methods to investigate mediating variables. PMID:20157637

  17. Current Directions in Mediation Analysis

    OpenAIRE

    MacKinnon, David P.; Fairchild, Amanda J.

    2009-01-01

    Mediating variables continue to play an important role in psychological theory and research. A mediating variable transmits the effect of an antecedent variable on to a dependent variable, thereby providing more detailed understanding of relations among variables. Methods to assess mediation have been an active area of research for the last two decades. This paper describes the current state of methods to investigate mediating variables.

  18. Dissociation in mediation

    Directory of Open Access Journals (Sweden)

    Daniela Muraru

    2008-01-01

    Full Text Available This paper approaches several texts that are part of the so-called discourse of mediation, adopting a pragma-dialectical perspective of the theory of dissociation. It is an attempt to identify the uses of dissociative patterns, with special emphasis on the indicators of dissociation. The paper investigates the various uses of the concept of dissociation as a discursive technique in the argumentation on the different aspects that are involved in international conflict, such as the discussion of the notion of peace. The purpose is to identify the role of dissociation, as a device strategically used by the mediator to help the parties minimize the disagreement space, and come to a conflict resolution.

  19. [Mediation in schools].

    Science.gov (United States)

    Mickley, Angela

    2006-01-01

    In this article the guiding questions concern the objectives and effectiveness of introducing mediation into an existing school culture of dominance, competition and selection. In addition the necessity will be shown of combining conflict resolution with organisational development and the introduction of a consensual ethics and behaviour code to attain sustainable results in creating a constructive and healthy school environment. Given scarce resources and little time the decisive role of artistic methods will be looked at in providing young people with flexible methods of expressing and negotiating their interests in a changing environment of values and power structures. Some aspects of the development of nonviolent communication, conflict resolution and mediation methods in schools in Germany will be focused on with special emphasis on the type of intervention used and its long term sustainable effects.

  20. Church mediation - een vak apart

    NARCIS (Netherlands)

    Annelies Klinefelter; dr Hans A.J. Jonker

    2009-01-01

    Welke rol kan mediation in de kerk spelen in de diverse geledingen en specifieke activiteiten? In dit artikel wordt ingegaan op kerkelijke conflicten, gelaagdheid in church mediation, en specifieke dilemma's van church mediation. Daarnaast komen enkele benaderingen aan bod zoals: helende

  1. The Mediatization of Philanthropy

    OpenAIRE

    Mitchell, Matthew

    2014-01-01

    This study seeks to better understand the motivations and mechanics of individuals contributing to nonprofits organizations today.  Through the prism of our highly mediatized (Hjarvard, 2008) social environment, this study examines the individual motivations and actions of cause-champions running in the 2013 NYC marathon and fundraising through social media and offline on behalf of the Michael J Fox Foundation (MJFF).  To gain the necessary detail and understanding of these micro-actions of a...

  2. Teachers as mediators

    DEFF Research Database (Denmark)

    Dorf, Hans; Kelly, Peter; Hohmann, Ulrike

    2012-01-01

    Within the context of lower secondary English teaching in South West England, this study identifies in broad terms the competing goals between which English teachers mediate and the explicit and hidden tensions that result. To understand the interactions of competing goals, teachers’ goal...... and cultural influences on practice. Yet the teachers observed moved smoothly between goal-oriented behaviours in a continuous and comfortable style, easily and without reflecting any tensions between them. Thus, this article elaborates an account of situated English teaching....

  3. mma: An R Package for Mediation Analysis with Multiple Mediators

    Directory of Open Access Journals (Sweden)

    Qingzhao Yu

    2017-04-01

    Full Text Available Mediation refers to the effect transmitted by mediators that intervene in the relationship between an exposure and a response variable. Mediation analysis has been broadly studied in many fields. However, it remains a challenge for researchers to consider complicated associations among variables and to differentiate individual effects from multiple mediators. [1] proposed general definitions of mediation effects that were adaptable to all different types of response (categorical or continuous, exposure, or mediation variables. With these definitions, multiple mediators of different types can be considered simultaneously, and the indirect effects carried by individual mediators can be separated from the total effect. Moreover, the derived mediation analysis can be performed with general predictive models. That is, the relationships among variables can be modeled using not only generalized linear models but also nonparametric models such as the Multiple Additive Regression Trees. Therefore, more complicated variable transformations and interactions can be considered in analyzing the mediation effects. The proposed method is realized by the R package 'mma'. We illustrate in this paper the proposed method and how to use 'mma' to estimate mediation effects and make inferences.

  4. Causal Mediation Analysis of Survival Outcome with Multiple Mediators.

    Science.gov (United States)

    Huang, Yen-Tsung; Yang, Hwai-I

    2017-05-01

    Mediation analyses have been a popular approach to investigate the effect of an exposure on an outcome through a mediator. Mediation models with multiple mediators have been proposed for continuous and dichotomous outcomes. However, development of multimediator models for survival outcomes is still limited. We present methods for multimediator analyses using three survival models: Aalen additive hazard models, Cox proportional hazard models, and semiparametric probit models. Effects through mediators can be characterized by path-specific effects, for which definitions and identifiability assumptions are provided. We derive closed-form expressions for path-specific effects for the three models, which are intuitively interpreted using a causal diagram. Mediation analyses using Cox models under the rare-outcome assumption and Aalen additive hazard models consider effects on log hazard ratio and hazard difference, respectively; analyses using semiparametric probit models consider effects on difference in transformed survival time and survival probability. The three models were applied to a hepatitis study where we investigated effects of hepatitis C on liver cancer incidence mediated through baseline and/or follow-up hepatitis B viral load. The three methods show consistent results on respective effect scales, which suggest an adverse estimated effect of hepatitis C on liver cancer not mediated through hepatitis B, and a protective estimated effect mediated through the baseline (and possibly follow-up) of hepatitis B viral load. Causal mediation analyses of survival outcome with multiple mediators are developed for additive hazard and proportional hazard and probit models with utility demonstrated in a hepatitis study.

  5. Immune mediated liver failure.

    Science.gov (United States)

    Wang, Xiaojing; Ning, Qin

    2014-01-01

    Liver failure is a clinical syndrome of various etiologies, manifesting as jaundice, encephalopathy, coagulopathy and circulatory dysfunction, which result in subsequent multiorgan failure. Clinically, liver failure is classified into four categories: acute, subacute, acute-on-chronic and chronic liver failure. Massive hepatocyte death is considered to be the core event in the development of liver failure, which occurs when the extent of hepatocyte death is beyond the liver regenerative capacity. Direct damage and immune-mediated liver injury are two major factors involved in this process. Increasing evidence has suggested the essential role of immune-mediated liver injury in the pathogenesis of liver failure. Here, we review the evolved concepts concerning the mechanisms of immune-mediated liver injury in liver failure from human and animal studies. Both innate and adaptive immunity, especially the interaction of various immune cells and molecules as well as death receptor signaling system are discussed. In addition, we highlight the concept of "immune coagulation", which has been shown to be related to the disease progression and liver injury exacerbation in HBV related acute-on-chronic liver failure.

  6. Lopsided Gauge Mediation

    CERN Document Server

    De Simone, Andrea; Giudice, Gian Francesco; Pappadopulo, Duccio; Rattazzi, Riccardo

    2011-01-01

    It has been recently pointed out that the unavoidable tuning among supersymmetric parameters required to raise the Higgs boson mass beyond its experimental limit opens up new avenues for dealing with the so called $\\mu$-$B_\\mu$ problem of gauge mediation. In fact, it allows for accommodating, with no further parameter tuning, large values of $B_\\mu$ and of the other Higgs-sector soft masses, as predicted in models where both $\\mu$ and $B_\\mu$ are generated at one-loop order. This class of models, called Lopsided Gauge Mediation, offers an interesting alternative to conventional gauge mediation and is characterized by a strikingly different phenomenology, with light higgsinos, very large Higgs pseudoscalar mass, and moderately light sleptons. We discuss general parametric relations involving the fine-tuning of the model and various observables such as the chargino mass and the value of $\\tan\\beta$. We build an explicit model and we study the constraints coming from LEP and Tevatron. We show that in spite of ne...

  7. Recruitment of Mediator Complex by Cell Type and Stage-Specific Factors Required for Tissue-Specific TAF Dependent Gene Activation in an Adult Stem Cell Lineage.

    Science.gov (United States)

    Lu, Chenggang; Fuller, Margaret T

    2015-12-01

    Onset of terminal differentiation in adult stem cell lineages is commonly marked by robust activation of new transcriptional programs required to make the appropriate differentiated cell type(s). In the Drosophila male germ line stem cell lineage, the switch from proliferating spermatogonia to spermatocyte is accompanied by one of the most dramatic transcriptional changes in the fly, as over 1000 new transcripts turn on in preparation for meiosis and spermatid differentiation. Here we show that function of the coactivator complex Mediator is required for activation of hundreds of new transcripts in the spermatocyte program. Mediator appears to act in a sequential hierarchy, with the testis activating Complex (tMAC), a cell type specific form of the Mip/dREAM general repressor, required to recruit Mediator subunits to the chromatin, and Mediator function required to recruit the testis TAFs (tTAFs), spermatocyte specific homologs of subunits of TFIID. Mediator, tMAC and the tTAFs co-regulate expression of a major set of spermatid differentiation genes. The Mediator subunit Med22 binds the tMAC component Topi when the two are coexpressed in S2 cells, suggesting direct recruitment. Loss of Med22 function in spermatocytes causes meiosis I maturation arrest male infertility, similar to loss of function of the tMAC subunits or the tTAFs. Our results illuminate how cell type specific versions of the Mip/dREAM complex and the general transcription machinery cooperate to drive selective gene activation during differentiation in stem cell lineages.

  8. Recruitment of Mediator Complex by Cell Type and Stage-Specific Factors Required for Tissue-Specific TAF Dependent Gene Activation in an Adult Stem Cell Lineage.

    Directory of Open Access Journals (Sweden)

    Chenggang Lu

    2015-12-01

    Full Text Available Onset of terminal differentiation in adult stem cell lineages is commonly marked by robust activation of new transcriptional programs required to make the appropriate differentiated cell type(s. In the Drosophila male germ line stem cell lineage, the switch from proliferating spermatogonia to spermatocyte is accompanied by one of the most dramatic transcriptional changes in the fly, as over 1000 new transcripts turn on in preparation for meiosis and spermatid differentiation. Here we show that function of the coactivator complex Mediator is required for activation of hundreds of new transcripts in the spermatocyte program. Mediator appears to act in a sequential hierarchy, with the testis activating Complex (tMAC, a cell type specific form of the Mip/dREAM general repressor, required to recruit Mediator subunits to the chromatin, and Mediator function required to recruit the testis TAFs (tTAFs, spermatocyte specific homologs of subunits of TFIID. Mediator, tMAC and the tTAFs co-regulate expression of a major set of spermatid differentiation genes. The Mediator subunit Med22 binds the tMAC component Topi when the two are coexpressed in S2 cells, suggesting direct recruitment. Loss of Med22 function in spermatocytes causes meiosis I maturation arrest male infertility, similar to loss of function of the tMAC subunits or the tTAFs. Our results illuminate how cell type specific versions of the Mip/dREAM complex and the general transcription machinery cooperate to drive selective gene activation during differentiation in stem cell lineages.

  9. What carries a mediation process? Configural analysis of mediation.

    Science.gov (United States)

    von Eye, Alexander; Mun, Eun Young; Mair, Patrick

    2009-09-01

    Mediation is a process that links a predictor and a criterion via a mediator variable. Mediation can be full or partial. This well-established definition operates at the level of variables even if they are categorical. In this article, two new approaches to the analysis of mediation are proposed. Both of these approaches focus on the analysis of categorical variables. The first involves mediation analysis at the level of configurations instead of variables. Thus, mediation can be incorporated into the arsenal of methods of analysis for person-oriented research. Second, it is proposed that Configural Frequency Analysis (CFA) can be used for both exploration and confirmation of mediation relationships among categorical variables. The implications of using CFA are first that mediation hypotheses can be tested at the level of individual configurations instead of variables. Second, this approach leaves the door open for different types of mediation processes to exist within the same set. Using a data example, it is illustrated that aggregate-level analysis can overlook mediation processes that operate at the level of individual configurations.

  10. Role of 5′TG3′-interacting factors (TGIFs) in Vorinostat (HDAC inhibitor)-mediated Corneal Fibrosis Inhibition

    Science.gov (United States)

    Sharma, Ajay; Sinha, Nishant R.; Siddiqui, Saad

    2015-01-01

    Purpose We have previously reported that vorinostat, an FDA-approved, clinically used histone deacetylase (HDAC) inhibitor, attenuates corneal fibrosis in vivo in rabbits by blocking transforming growth factor β (TGFβ). The 5′TG3′-interacting factors (TGIFs) are transcriptional repressors of TGFβ1 signaling via the Smad pathway. The present study was designed to explore the expression of TGIFs in human corneal fibroblasts and to investigate their role in mediating the antifibrotic effect of vorinostat. Methods Human corneal fibroblast cultures were generated from donor corneas. RNA isolation, cDNA preparation, and PCR were performed to detect the presence of TGIF1 and TGIF2 transcripts. The cultures were exposed to vorinostat (2.5 µM) to test its effect on TGIF mRNA and protein levels using qPCR and immunoblotting. Myofibroblast formation was induced with TGFβ1 (5 ng/ml) treatment under serum-free conditions. The changes in fibrosis parameters were quantified by measuring fibrosis marker α-smooth muscle actin (αSMA) mRNA and protein levels with qPCR, immunostaining, and immunoblotting. Smad2/3/4 and TGIF knockdowns were performed using pre-validated RNAi/siRNAs and a commercially available transfection reagent. Results Human corneal fibroblasts showed the expression of TGIF1 and TGIF2. Vorinostat (2.5 µM) caused a 2.8–3.3-fold increase in TGIF1 and TGIF2 mRNA levels and a 1.4–1.8-fold increase in TGIF1 and TGIF2 protein levels. Vorinostat treatment also caused a significant increase in acetylhistone H3 and acetylhistone H4. Vorinostat-induced increases in TGIF1 and TGIF2 were accompanied by a concurrent decrease in corneal fibrosis, as indicated by a decrease in αSMA mRNA by 83±7.7% and protein levels by 97±5%. The RNAi-mediated knockdown of Smad2, Smad3, and Smad4 markedly attenuated TGFβ1-evoked transdifferentiation of fibroblasts to myofibroblasts. The siRNA-mediated knockdown of TGIF1 and TGIF2 neutralized vorinostat-evoked decreases in

  11. Urban Songlines as Mediator

    DEFF Research Database (Denmark)

    Corlin, Anne

    2016-01-01

    The aim of this paper is to present an investigation of the method The Urban Songlines Book and how it works as a mediator for mapping the experienced space. The method contains a combination of aerial maps, photographs, and interviews as a way to understand the respondent´s use, relations...... and experiences of their neighborhood and the city. Through a presentation of the origin of the method, a description of the conducted study, and an analysis of the process in relation to theories about participatory design, social design, ANT and architectural sociology, the paper reveals how this method...

  12. Sociocultural mediators of remembering

    DEFF Research Database (Denmark)

    Wagoner, Brady; Gillespie, Alex

    2014-01-01

    , questioning and deferring contribute to the transformation and conventionalization of the material. These diverse sociocultural mediators are integrated into a partially coherent recollection by participants self-reflecting, or as Bartlett termed it, turning around upon their schemas. We demonstrate...... that this self-reflection is both a social and a psychological process, occurring because participants are responding to their own utterances in the same way that they respond to the utterances of other people. These empirical findings are used to make a case for using discursive data to look not only...

  13. DNA-Mediated Electrochemistry

    Science.gov (United States)

    Gorodetsky, Alon A.; Buzzeo, Marisa C.

    2009-01-01

    The base pair stack of DNA has been demonstrated as a medium for long range charge transport chemistry both in solution and at DNA-modified surfaces. This chemistry is exquisitely sensitive to structural perturbations in the base pair stack as occur with lesions, single base mismatches, and protein binding. We have exploited this sensitivity for the development of reliable electrochemical assays based on DNA charge transport at self-assembled DNA monolayers. Here we discuss the characteristic features, applications, and advantages of DNA-mediated electrochemistry. PMID:18980370

  14. Holographic Gauge Mediation

    Energy Technology Data Exchange (ETDEWEB)

    Benini, Francesco; /Princeton U.; Dymarsky, Anatoly; /Stanford U., ITP; Franco, Sebastian; /Santa Barbara, KITP; Kachru, Shamit; Simic, Dusan; /Stanford U., ITP /SLAC; Verlinde, Herman; /Princeton, Inst. Advanced Study

    2009-06-19

    We discuss gravitational backgrounds where supersymmetry is broken at the end of a warped throat, and the SUSY-breaking is transmitted to the Standard Model via gauginos which live in (part of) the bulk of the throat geometry. We find that the leading effect arises from splittings of certain 'messenger mesons,' which are adjoint KK-modes of the D-branes supporting the Standard Model gauge group. This picture is a gravity dual of a strongly coupled field theory where SUSY is broken in a hidden sector and transmitted to the Standard Model via a relative of semi-direct gauge mediation.

  15. 45 CFR 16.18 - Mediation.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Mediation. 16.18 Section 16.18 Public Welfare... BOARD § 16.18 Mediation. (a) In cases pending before the Board. If the Board decides that mediation... mediation techniques and will provide or assist in selecting a mediator. The mediator may take any steps...

  16. Distinct roles for aryl hydrocarbon receptor nuclear translocator and ah receptor in estrogen-mediated signaling in human cancer cell lines.

    Directory of Open Access Journals (Sweden)

    Mark P Labrecque

    Full Text Available The activated AHR/ARNT complex (AHRC regulates the expression of target genes upon exposure to environmental contaminants such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD. Importantly, evidence has shown that TCDD represses estrogen receptor (ER target gene activation through the AHRC. Our data indicates that AHR and ARNT act independently from each other at non-dioxin response element sites. Therefore, we sought to determine the specific functions of AHR and ARNT in estrogen-dependent signaling in human MCF7 breast cancer and human ECC-1 endometrial carcinoma cells. Knockdown of AHR with siRNA abrogates dioxin-inducible repression of estrogen-dependent gene transcription. Intriguingly, knockdown of ARNT does not effect TCDD-mediated repression of estrogen-regulated transcription, suggesting that AHR represses ER function independently of ARNT. This theory is supported by the ability of the selective AHR modulator 3',4'-dimethoxy-α-naphthoflavone (DiMNF to repress estrogen-inducible transcription. Furthermore, basal and estrogen-activated transcription of the genes encoding cathepsin-D and pS2 are down-regulated in MCF7 cells but up-regulated in ECC-1 cells in response to loss of ARNT. These responses are mirrored at the protein level with cathepsin-D. Furthermore, knock-down of ARNT led to opposite but corresponding changes in estrogen-stimulated proliferation in both MCF7 and ECC-1 cells. We have obtained experimental evidence demonstrating a dioxin-dependent repressor function for AHR and a dioxin-independent co-activator/co-repressor function for ARNT in estrogen signalling. These results provide us with further insight into the mechanisms of transcription factor crosstalk and putative therapeutic targets in estrogen-positive cancers.

  17. Interventional effects for mediation analysis with multiple mediators

    OpenAIRE

    Vansteelandt, Stijn; Daniel, Rhian M.

    2017-01-01

    The mediation formula for the identification of natural (in)direct effects has facilitated mediation analyses that better respect the nature of the data, with greater consideration of the need for confounding control. The default assumptions on which it relies are strong, however. In particular, they are known to be violated when confounders of the mediator–outcome association are affected by the exposure. This complicates extensions of counterfactual-based mediation analysis to settings that...

  18. Interpreter-mediated dentistry.

    Science.gov (United States)

    Bridges, Susan; Drew, Paul; Zayts, Olga; McGrath, Colman; Yiu, Cynthia K Y; Wong, H M; Au, T K F

    2015-05-01

    The global movements of healthcare professionals and patient populations have increased the complexities of medical interactions at the point of service. This study examines interpreter mediated talk in cross-cultural general dentistry in Hong Kong where assisting para-professionals, in this case bilingual or multilingual Dental Surgery Assistants (DSAs), perform the dual capabilities of clinical assistant and interpreter. An initial language use survey was conducted with Polyclinic DSAs (n = 41) using a logbook approach to provide self-report data on language use in clinics. Frequencies of mean scores using a 10-point visual analogue scale (VAS) indicated that the majority of DSAs spoke mainly Cantonese in clinics and interpreted for postgraduates and professors. Conversation Analysis (CA) examined recipient design across a corpus (n = 23) of video-recorded review consultations between non-Cantonese speaking expatriate dentists and their Cantonese L1 patients. Three patterns of mediated interpreting indicated were: dentist designated expansions; dentist initiated interpretations; and assistant initiated interpretations to both the dentist and patient. The third, rather than being perceived as negative, was found to be framed either in response to patient difficulties or within the specific task routines of general dentistry. The findings illustrate trends in dentistry towards personalized care and patient empowerment as a reaction to product delivery approaches to patient management. Implications are indicated for both treatment adherence and the education of dental professionals. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Ligand Receptor-Mediated Regulation of Growth in Plants.

    Science.gov (United States)

    Haruta, Miyoshi; Sussman, Michael R

    2017-01-01

    Growth and development of multicellular organisms are coordinately regulated by various signaling pathways involving the communication of inter- and intracellular components. To form the appropriate body patterns, cellular growth and development are modulated by either stimulating or inhibiting these pathways. Hormones and second messengers help to mediate the initiation and/or interaction of the various signaling pathways in all complex multicellular eukaryotes. In plants, hormones include small organic molecules, as well as larger peptides and small proteins, which, as in animals, act as ligands and interact with receptor proteins to trigger rapid biochemical changes and induce the intracellular transcriptional and long-term physiological responses. During the past two decades, the availability of genetic and genomic resources in the model plant species, Arabidopsis thaliana, has greatly helped in the discovery of plant hormone receptors and the components of signal transduction pathways and mechanisms used by these immobile but highly complex organisms. Recently, it has been shown that two of the most important plant hormones, auxin and abscisic acid (ABA), act through signaling pathways that have not yet been recognized in animals. For example, auxins stimulate cell elongation by bringing negatively acting transcriptional repressor proteins to the proteasome to be degraded, thus unleashing the gene expression program required for increasing cell size. The "dormancy" inducing hormone, ABA, binds to soluble receptor proteins and inhibits a specific class of protein phosphatases (PP2C), which activates phosphorylation signaling leading to transcriptional changes needed for the desiccation of the seeds prior to entering dormancy. While these two hormone receptors have no known animal counterparts, there are also many similarities between animal and plant signaling pathways. For example, in plants, the largest single gene family in the genome is the protein kinase

  20. Mediation Analysis: A Practitioner's Guide.

    Science.gov (United States)

    VanderWeele, Tyler J

    2016-01-01

    This article provides an overview of recent developments in mediation analysis, that is, analyses used to assess the relative magnitude of different pathways and mechanisms by which an exposure may affect an outcome. Traditional approaches to mediation in the biomedical and social sciences are described. Attention is given to the confounding assumptions required for a causal interpretation of direct and indirect effect estimates. Methods from the causal inference literature to conduct mediation in the presence of exposure-mediator interactions, binary outcomes, binary mediators, and case-control study designs are presented. Sensitivity analysis techniques for unmeasured confounding and measurement error are introduced. Discussion is given to extensions to time-to-event outcomes and multiple mediators. Further flexible modeling strategies arising from the precise counterfactual definitions of direct and indirect effects are also described. The focus throughout is on methodology that is easily implementable in practice across a broad range of potential applications.

  1. A higher form (of) mediation

    International Nuclear Information System (INIS)

    Verlinde, Herman; Wang, L-T; Yavin, Itay; Wijnholt, Martijn

    2008-01-01

    We exhibit a simple and robust mechanism for bulk mediation of supersymmetry breaking between hidden and visible sectors localized on geometrically separated D-branes in type II string theory. The mediation proceeds via RR p-forms that couple via linear Chern-Simons terms to the abelian vector bosons on the branes. From a 4-d low energy perspective, the mechanism reduces to U(1) mediation

  2. Mediating Trust in Terrorism Coverage

    DEFF Research Database (Denmark)

    Mogensen, Kirsten

    crisis. While the framework is presented in the context of television coverage of a terror-related crisis situation, it can equally be used in connection with all other forms of mediated trust. Key words: National crisis, risk communication, crisis management, television coverage, mediated trust.......Mass mediated risk communication can contribute to perceptions of threats and fear of “others” and/or to perceptions of trust in fellow citizens and society to overcome problems. This paper outlines a cross-disciplinary holistic framework for research in mediated trust building during an acute...

  3. Substrate mediated enzyme prodrug therapy

    DEFF Research Database (Denmark)

    Fejerskov, Betina; Jarlstad Olesen, Morten T; Zelikin, Alexander N

    2017-01-01

    Substrate mediated enzyme prodrug therapy (SMEPT) is a biomedical platform developed to perform a localized synthesis of drugs mediated by implantable biomaterials. This approach combines the benefits and at the same time offers to overcome the drawbacks for traditional pill-based drug administra......Substrate mediated enzyme prodrug therapy (SMEPT) is a biomedical platform developed to perform a localized synthesis of drugs mediated by implantable biomaterials. This approach combines the benefits and at the same time offers to overcome the drawbacks for traditional pill-based drug...

  4. The Strategic Mediator

    DEFF Research Database (Denmark)

    Rossignoli, Cecilia; Carugati, Andrea; Mola, Lapo

    2009-01-01

    process. Through the study of services evolving over time we show that, as marketplaces support increasingly complex business processes, the market participants begin to privilege the well connected small number to the convenience of the openness to the entire market. The participants see the marketplace......The last 10 years have witnessed the emergence of electronic marketplaces as players that leverage new technologies to facilitate B2B internet-mediated collaborative business. Nowadays these players are augmenting their services from simple intermediation to include new inter......-organizational relationships. The interest of this paper is to investigate the shift in the role and evolution of services proposed by e-marketplaces in response to the demands of the market participants. We carried out a longitudinal qualitative field study of an e-marketplace providing the outsourcing of the procurement...

  5. Mediating Potency and Fear

    DEFF Research Database (Denmark)

    Christiansen, Steen Ledet

    2018-01-01

    Action movies participate in the administration of fear [Virilio, P., 2012. The administration of fear. Translated by Ames Hodges. Los Angeles, CA: Semiotext(e)], and the networked affects of contemporary warfare [Anderson, B., 2013. Targeting affective life from above: morale and airpower. In: P......’ [Shaviro, S., 2010. Post-cinematic affect. Winchester: Zero Books]. These intensity effects mediate between the age of terror's ecology of fear [Massumi, Brian, 2002. Parables for the virtual: movement, affect, sensation. Durham: Duke University Press] and our bodies. Rather than producing fear, action...... movies work to dispel fear by producing potency and bolstering resolve. We can thus understand action movies as participating in the biopolitical effects of contemporary warfare. Affect is globalized and intensified through action movies’ aesthetics, with the aim of producing a kind of drone subject...

  6. Den sundhedsfremmende mediator

    DEFF Research Database (Denmark)

    Læssøe, Jeppe

    2009-01-01

      Mediatorer er en relativ ny aktør-type og job-funktion, som passer godt ind i det dynamiske videns- og netværkssamfund. I sundhedsfremmende arbejde med vægt på borgernes deltagelse kan mediatorer spille en nøglerolle. Det er derfor vigtigt begrebsmæssigt at kunne skelne mellem forskellige typer...... mediering samt mellem forskellige mediator-roller og tilhørsforhold. Det er også vigtigt at være bevidst om de centrale kvaliteter, risici og dilemmaer, som mediering indebærer i forhold til involvering af borgerne. Denne artikel rummer et bud på en sådan nuanceret begrebsliggørelse og refleksion, relateret...

  7. Soluble lymphocytic mediators

    Science.gov (United States)

    Pick, E.

    1974-01-01

    The effect of a number of drugs on the production of macrophage migration inhibitory factor (MIF) by antigen-stimulated sensitized guinea-pig lymph node cells was studied. The drugs were present during the entire culture period and eliminated from supernatants by dialysis. It was found that MIF secretion is inhibited by exogenous dibutyryl cyclic AMP and by theophylline and chlorphenesin, two agents raising the endogenous level of cyclic AMP. On the other hand, isoproterenol, which stimulates cyclic AMP generation in several tissues, did not block MIF production. The formation of the mediator was also suppressed by the microfilament-affecting drug, cytochalasin B. The microtubular disruptive agents, colchicine and vinblastine sulphate, did not influence MIF production. It is concluded that: (a) endogenous cyclic AMP may act as a regulator of MIF production; (b) the activity of contractile microfilaments is probably required for MIF formation; and (c) microtubules are not involved in the secretory process. PMID:4369184

  8. Protein- mediated enamel mineralization

    Science.gov (United States)

    Moradian-Oldak, Janet

    2012-01-01

    Enamel is a hard nanocomposite bioceramic with significant resilience that protects the mammalian tooth from external physical and chemical damages. The remarkable mechanical properties of enamel are associated with its hierarchical structural organization and its thorough connection with underlying dentin. This dynamic mineralizing system offers scientists a wealth of information that allows the study of basic principals of organic matrix-mediated biomineralization and can potentially be utilized in the fields of material science and engineering for development and design of biomimetic materials. This chapter will provide a brief overview of enamel hierarchical structure and properties as well as the process and stages of amelogenesis. Particular emphasis is given to current knowledge of extracellular matrix protein and proteinases, and the structural chemistry of the matrix components and their putative functions. The chapter will conclude by discussing the potential of enamel for regrowth. PMID:22652761

  9. Mediating environmental disputes

    Energy Technology Data Exchange (ETDEWEB)

    Lake, L.M.

    1977-09-01

    Environmental disputes and lawsuits are examined. Site-specific disputes focus on visible physical phenomena, such as a power plant or local river, and have an immediacy and intensity about them that make it politically hazardous for public officials to assume responsibility for resolving them. As new precedents in environmental case law become less frequent and the number of disputes increases, alternative processes for environmental conflict resolution, such as third-party intervention, become appropriate. Third-party intervention techniques of fact finding, conflict avoidance, conciliation and mediation have been applied to international, labor, prison, school, racial, and hospital disputes. Underlying concepts are described. Two case studies, the Snoqualmie Dam dispute in Washington and the West Side Highway dispute in New York City, illustrate the basic elements associated with third-party intervention. 1 map, 17 references.

  10. Mediatization and Government Communication

    DEFF Research Database (Denmark)

    Laursen, Bo; Valentini, Chiara

    2015-01-01

    do not tend to get a media coverage that matches the EU’s considerable influence on European citizens’ daily lives. This study, which is based on in-depth interviews with European Parliament press officers, concludes that these professionals are indeed attuned to a “media logic......Social actors see exposure in the news media as attractive for publicity purposes and are under pressure to adapt their press work to a “media logic” to be attractive sources for journalists and editors. This article investigates the European Parliament’s press officers’ professional practices...... in the light of mediatization and government communication theories. Without one pan-European public sphere, the European Parliament, like the other European Union (EU) institutions, competes with national actors for the news media’s attention in the EU’s twenty-eight national public spheres, where EU affairs...

  11. The mediation procedure in Romania

    Directory of Open Access Journals (Sweden)

    Alexandrina Zaharia

    2009-06-01

    Full Text Available The mediation activity as an alternative way of solving conflicts occupies an important place in modernsociety. Currently, the mediation reached its maturity worldwide being adopted without reservations.The future of solving conflicts is undoubtedly closely related to mediation. XXth century is the century of solvingconflicts amiably outside the court room. In Romania and the mediation profession were regulated by the Law no.192/2006, on the basis of the idea that mediation is one of the major themes of the reform strategy of the judicialsystem 2005-2007. By adopting the mentioned law it was followed the idea of reducing the volume of activitycourts, and therefore, relieve them of as many cases, with the direct effect on the quality of justice. Mediation is avoluntary process in which the parties with a neutral and impartial third party, without power of decision - themediator - who is qualified to assist the parties to negotiate, facilitating the communication between them andhelping them to reach a unanimous effective and sustainable agreement. The parties may resort to mediation beforeor after triggering a trial. Mediation can be applied, in principle, on any type of conflict. However, theRomanian legislator has established special stipulations on conflict mediation in criminal, civil and familylaw. Although not expressly provided, the stipulations regarding the civil conflicts and also apply to commercialconflicts. Therefore, the mediation is applicable to most types of lawsuits, except those relating to personalrights. As a "win- win" principle, the mediation does not convert any of the parties defeated or victorious; allthose involved have gained by applying this procedure.

  12. The role of apoptosis repressor with a CARD domain (ARC) in the therapeutic resistance of renal cell carcinoma (RCC): the crucial role of ARC in the inhibition of extrinsic and intrinsic apoptotic signalling.

    Science.gov (United States)

    Toth, Csaba; Funke, Sarah; Nitsche, Vanessa; Liverts, Anna; Zlachevska, Viktoriya; Gasis, Marcia; Wiek, Constanze; Hanenberg, Helmut; Mahotka, Csaba; Schirmacher, Peter; Heikaus, Sebastian

    2017-05-02

    Renal cell carcinomas (RCCs) display broad resistance against conventional radio- and chemotherapies, which is due at least in part to impairments in both extrinsic and intrinsic apoptotic pathways. One important anti-apoptotic factor that is strongly overexpressed in RCCs and known to inhibit both apoptotic pathways is ARC (apoptosis repressor with a CARD domain). Expression and subcellular distribution of ARC in RCC tissue samples and RCC cell lines were determined by immunohistochemistry and fluorescent immunohistochemistry, respectively. Extrinsic and intrinsic apoptosis signalling were induced by TRAIL (TNF-related apoptosis-inducing ligand), ABT-263 or topotecan. ARC knock-down was performed in clearCa-12 cells using lentiviral transduction of pGIPZ. shRNAmir constructs. Extrinsic respectively intrinsic apoptosis were induced by TRAIL (TNF-related apoptosis-inducing ligand), ABT263 or topotecan. Potential synergistic effects were tested by pre-treatment with topotecan and subsequent treatment with ABT263. Activation of different caspases and mitochondrial depolarisation (JC-1 staining) were analysed by flow cytometry. Protein expression of Bcl-2 family members and ARC in RCC cell lines was measured by Western blotting. Statistical analysis was performed by Student's t-test. Regarding the extrinsic pathway, ARC knockdown strongly enhanced TRAIL-induced apoptosis by increasing the activation level of caspase-8. Regarding the intrinsic pathway, ARC, which was only weakly expressed in the nuclei of RCCs in vivo, exerted its anti-apoptotic effect by impairing mitochondrial activation rather than inhibiting p53. Topotecan- and ABT-263-induced apoptosis was strongly enhanced following ARC knockdown in RCC cell lines. In addition, topotecan pre-treatment enhanced ABT-263-induced apoptosis and this effect was amplified in ARC-knockdown cells. Taken together, our results are the first to demonstrate the importance of ARC protein in the inhibition of both the extrinsic

  13. Interaction between repressor Opi1p and ER membrane protein Scs2p facilitates transit of phosphatidic acid from the ER to mitochondria and is essential for INO1 gene expression in the presence of choline.

    Science.gov (United States)

    Gaspar, Maria L; Chang, Yu-Fang; Jesch, Stephen A; Aregullin, Manuel; Henry, Susan A

    2017-11-10

    In the yeast Saccharomyces cerevisiae , the Opi1p repressor controls the expression of INO1 via the Opi1p/Ino2p-Ino4p regulatory circuit. Inositol depletion favors Opi1p interaction with both Scs2p and phosphatidic acid at the endoplasmic reticulum (ER) membrane. Inositol supplementation, however, favors the translocation of Opi1p from the ER into the nucleus, where it interacts with the Ino2p-Ino4p complex, attenuating transcription of INO1 A strain devoid of Scs2p ( scs2 Δ) and a mutant, OPI1FFAT , lacking the ability to interact with Scs2p were utilized to examine the specific role(s) of the Opi1p-Scs2p interaction in the regulation of INO1 expression and overall lipid metabolism. Loss of the Opi1p-Scs2p interaction reduced INO1 expression and conferred inositol auxotrophy. Moreover, inositol depletion in strains lacking this interaction resulted in Opi1p being localized to sites of lipid droplet formation, coincident with increased synthesis of triacylglycerol. Supplementation of choline to inositol-depleted growth medium led to decreased TAG synthesis in all three strains. However, in strains lacking the Opi1p-Scs2p interaction, Opi1p remained in the nucleus, preventing expression of INO1 These data support the conclusion that a specific pool of phosphatidic acid, associated with lipid droplet formation in the perinuclear ER, is responsible for the initial rapid exit of Opi1p from the nucleus to the ER and is required for INO1 expression in the presence of choline. Moreover, the mitochondria-specific phospholipid, cardiolipin, was significantly reduced in both strains compromised for Opi1p-Scs2p interaction, indicating that this interaction is required for the transfer of phosphatidic acid from the ER to the mitochondria for cardiolipin synthesis. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  14. Anomaly mediation deformed by axion

    Energy Technology Data Exchange (ETDEWEB)

    Nakayama, Kazunori, E-mail: kazunori@hep-th.phys.s.u-tokyo.ac.jp [Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Kavli Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa 277-8583 (Japan); Yanagida, Tsutomu T. [Kavli Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa 277-8583 (Japan)

    2013-05-13

    We show that in supersymmetric axion models the axion supermultiplet obtains a sizable F-term due to a non-supersymmetric dynamics and it generally gives the gaugino masses comparable to the anomaly mediation contribution. Thus the gaugino mass relation predicted by the anomaly mediation effect can be significantly modified in the presence of axion to solve the strong CP problem.

  15. Theorizing with/out "Mediators".

    Science.gov (United States)

    Roth, Wolff-Michael; Jornet, Alfredo

    2017-01-05

    Mediation is one of the most often cited concepts in current cultural-historical theory literature, in which cultural actions and artifacts are often characterized as mediators standing between situational stimuli and behavioral responses. Most often presented as a means to overcome Cartesian dualism between subject and object, and between individual and society, some scholars have nonetheless raised criticism suggesting that such mediators are problematic for a dialectical psychology that takes a unit analysis (monist) approach. In fact, Spinoza develops a monist theory of mind and body that goes without and even excludes every form of mediation. In this study, we follow up on the latter criticisms and explore what we consider to be problematic uses of the notion of mediation as an analytical construct in the literature. We elaborate an empirically grounded discussion on the ways the concept of mediation may lead to dualistic readings; and we offer an alternative account where the notion of mediator is not needed. We conclude discussing prospects for and implications of a cultural-historical theory where the notion of mediation no longer is invoked to account for human action and development.

  16. The retinoblastoma protein as a transcriptional repressor

    DEFF Research Database (Denmark)

    Helin, K; Ed, H

    1993-01-01

    The retinoblastoma protein (pRB) is one of the best-studied tumour suppressor gene products. Its loss during the genesis of many human tumours, its inactivation by several DNA tumour virus oncoproteins, and its ability to inhibit cell growth when introduced into dividing cells all suggest that p...

  17. Comments on general gauge mediation

    International Nuclear Information System (INIS)

    Intriligator, Kenneth; Sudano, Matthew

    2008-01-01

    There has been interest in generalizing models of gauge mediation of supersymmetry breaking. As shown by Meade, Seiberg, and Shih (MSS), the soft masses of general gauge mediation can be expressed in terms of the current two-point functions of the susy-breaking sector. We here give a simple extension of their result which provides, for general gauge mediation, the full effective potential for squark pseudo-D-flat directions. The effective potential reduces to the sfermion soft masses near the origin, and the full potential, away from the origin, can be useful for cosmological applications. We also generalize the soft masses and effective potential to allow for general gauge mediation by Higgsed gauge groups. Finally, we discuss general gauge mediation in the limit of small F-terms, and how the results of MSS connect with the analytic continuation in superspace results, based on a spurion analysis.

  18. Practical Guide to Civil Mediation

    CERN Document Server

    2006-01-01

    The Permanent Mission of Switzerland has informed CERN that the Département des Institutions of the Republic and Canton of Geneva and the Groupement suisse des Magistrats pour la médiation (GEMME) - Swiss Association of Magistrates for Mediation have published a multilingual Practical Guide to Civil Mediation (including English). In this context, the Swiss Mission has underlined the benefits of resorting to mediation, especially for the personnel of international organizations, and which the Secretary-General of the GEMME has summarised as follows: it is a private process not requiring the waiver of the parties' immunities; the confidentiality of the mediation process is guaranteed both by the mediator and the parties to it; the search for an amicable settlement does not need to be determined by reference to law (provided that public order is respected); the process is faster (2 to 3 sessions), less costly and more flexible than civil or arbitration procedures; in order to reinforce the agreeme...

  19. Practical Guide to Civil Mediation

    CERN Multimedia

    2006-01-01

    The Permanent Mission of Switzerland has informed CERN that the Département des Institutions of the Republic and Canton of Geneva and the Groupement suisse des Magistrats pour la médiation (GEMME) - Swiss Association of Magistrates for Mediation have published a multilingual Practical Guide to Civil Mediation (including English). In this context, the Swiss Mission has underlined the benefits of resorting to mediation, especially for the personnel of International Organizations, and which the Secretary-General of the GEMME has summarised as follows: it is a private process not requiring the waiver of the parties' immunities; the confidentiality of the mediation process is guaranteed both by the mediator and the parties to it; the search for an amicable settlement does not need to be determined by reference to law (provided that public order is respected); the process is faster (2 to 3 sessions), less costly and more flexible than civil or arbitration procedures; in order to reinforce the agreem...

  20. 29 CFR 35.32 - Mediation.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 1 2010-07-01 2010-07-01 true Mediation. 35.32 Section 35.32 Labor Office of the Secretary... Mediation. (a) Referral to mediation. CRC will promptly refer to the Federal Mediation and Conciliation Service or the mediation agency designated by the Secretary of Health and Human Services under 45 CFR part...

  1. 22 CFR 143.33 - Mediation.

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Mediation. 143.33 Section 143.33 Foreign... Mediation. (a) Referral of complaints for mediation. The agency will refer to the Federal Mediation and... participate in the mediation process to the extent necessary to reach an agreement or make an informed...

  2. 29 CFR 1203.1 - Mediation services.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 4 2010-07-01 2010-07-01 false Mediation services. 1203.1 Section 1203.1 Labor Regulations Relating to Labor (Continued) NATIONAL MEDIATION BOARD APPLICATIONS FOR SERVICE § 1203.1 Mediation services. Applications for the mediation services of the National Mediation Board under section 5, First, of the Railway...

  3. 34 CFR 81.13 - Mediation.

    Science.gov (United States)

    2010-07-01

    ... 34 Education 1 2010-07-01 2010-07-01 false Mediation. 81.13 Section 81.13 Education Office of the... Mediation. (a) Voluntary mediation is available for proceedings that are pending before the OALJ. (b) A... mediation by filing a motion with the ALJ assigned to the case. The OALJ arranges for a mediator if the...

  4. 24 CFR 3288.35 - Mediation.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false Mediation. 3288.35 Section 3288.35...-Administered States § 3288.35 Mediation. (a) Mediator. The dispute resolution provider will provide for the... identifies any other party that should be included in the mediation, the mediator will contact the other...

  5. 44 CFR 7.942 - Mediation.

    Science.gov (United States)

    2010-10-01

    ... 44 Emergency Management and Assistance 1 2010-10-01 2010-10-01 false Mediation. 7.942 Section 7..., Conciliation, and Enforcement Procedures § 7.942 Mediation. (a) FEMA will promptly refer to a mediation agency... participate in the mediation process to the extent necessary to reach an agreement or for the mediator to make...

  6. 32 CFR 776.38 - Mediation.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 5 2010-07-01 2010-07-01 false Mediation. 776.38 Section 776.38 National... Professional Conduct § 776.38 Mediation. (a) Mediation: (1) A covered attorney may act as a mediator between... mediation, including the advantages and risks involved, and the effect on the attorney-client...

  7. 29 CFR 1202.1 - Mediation.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 4 2010-07-01 2010-07-01 false Mediation. 1202.1 Section 1202.1 Labor Regulations Relating to Labor (Continued) NATIONAL MEDIATION BOARD RULES OF PROCEDURE § 1202.1 Mediation. The mediation..., or where conferences are refused. The National Mediation Board may proffer its services in case any...

  8. Microbially mediated mineral carbonation

    Science.gov (United States)

    Power, I. M.; Wilson, S. A.; Dipple, G. M.; Southam, G.

    2010-12-01

    Mineral carbonation involves silicate dissolution and carbonate precipitation, which are both natural processes that microorganisms are able to mediate in near surface environments (Ferris et al., 1994; Eq. 1). (Ca,Mg)SiO3 + 2H2CO3 + H2O → (Ca,Mg)CO3 + H2O + H4SiO4 + O2 (1) Cyanobacteria are photoautotrophs with cell surface characteristics and metabolic processes involving inorganic carbon that can induce carbonate precipitation. This occurs partly by concentrating cations within their net-negative cell envelope and through the alkalinization of their microenvironment (Thompson & Ferris, 1990). Regions with mafic and ultramafic bedrock, such as near Atlin, British Columbia, Canada, represent the best potential sources of feedstocks for mineral carbonation. The hydromagnesite playas near Atlin are a natural biogeochemical model for the carbonation of magnesium silicate minerals (Power et al., 2009). Field-based studies at Atlin and corroborating laboratory experiments demonstrate the ability of a microbial consortium dominated by filamentous cyanobacteria to induce the precipitation of carbonate minerals. Phototrophic microbes, such as cyanobacteria, have been proposed as a means for producing biodiesel and other value added products because of their efficiency as solar collectors and low requirement for valuable, cultivable land in comparison to crops (Dismukes et al., 2008). Carbonate precipitation and biomass production could be facilitated using specifically designed ponds to collect waters rich in dissolved cations (e.g., Mg2+ and Ca2+), which would allow for evapoconcentration and provide an appropriate environment for growth of cyanobacteria. Microbially mediated carbonate precipitation does not require large quantities of energy or chemicals needed for industrial systems that have been proposed for rapid carbon capture and storage via mineral carbonation (e.g., Lackner et al., 1995). Therefore, this biogeochemical approach may represent a readily

  9. Nanoparticle mediated micromotor motion

    Science.gov (United States)

    Liu, Mei; Liu, Limei; Gao, Wenlong; Su, Miaoda; Ge, Ya; Shi, Lili; Zhang, Hui; Dong, Bin; Li, Christopher Y.

    2015-03-01

    In this paper, we report the utilization of nanoparticles to mediate the motion of a polymer single crystal catalytic micromotor. Micromotors have been fabricated by directly self-assembling functional nanoparticles (platinum and iron oxide nanoparticles) onto one or both sides of two-dimensional polymer single crystals. We show that the moving velocity of these micromotors in fluids can be readily tuned by controlling the nanoparticles' surface wettability and catalytic activity. A 3 times velocity increase has been achieved for a hydrophobic micromotor as opposed to the hydrophilic ones. Furthermore, we demonstrate that the catalytic activity of platinum nanoparticles inside the micromotor can be enhanced by their synergetic interactions with iron oxide nanoparticles and an electric field. Both strategies lead to dramatically increased moving velocities, with the highest value reaching ~200 μm s-1. By decreasing the nanoparticles' surface wettability and increasing their catalytic activity, a maximum of a ~10-fold increase in the moving speed of the nanoparticle based micromotor can be achieved. Our results demonstrate the advantages of using nanoparticles in micromotor systems.In this paper, we report the utilization of nanoparticles to mediate the motion of a polymer single crystal catalytic micromotor. Micromotors have been fabricated by directly self-assembling functional nanoparticles (platinum and iron oxide nanoparticles) onto one or both sides of two-dimensional polymer single crystals. We show that the moving velocity of these micromotors in fluids can be readily tuned by controlling the nanoparticles' surface wettability and catalytic activity. A 3 times velocity increase has been achieved for a hydrophobic micromotor as opposed to the hydrophilic ones. Furthermore, we demonstrate that the catalytic activity of platinum nanoparticles inside the micromotor can be enhanced by their synergetic interactions with iron oxide nanoparticles and an electric

  10. Novel function of transcription factor Nrf2 as an inhibitor of RON tyrosine kinase receptor-mediated cancer cell invasion.

    Science.gov (United States)

    Thangasamy, Amalraj; Rogge, Jessica; Krishnegowda, Naveen K; Freeman, James W; Ammanamanchi, Sudhakar

    2011-09-16

    Recepteur d' origine nantais (RON), a tyrosine kinase receptor, is aberrantly expressed in human tumors and promotes cancer cell invasion. RON receptor activation is also associated with resistance to tamoxifen treatment in breast cancer cells. Nrf2 is a positive regulator of cytoprotective genes. Using chromatin immunoprecipitation (ChIP) and site-directed mutagenesis studies of the RON promoter, we identified Nrf2 as a negative regulator of RON gene expression. High Nrf2 and low RON expression was observed in normal mammary tissue whereas high RON and low or undetectable expression of Nrf2 was observed in breast tumors. The Nrf2 inducer sulforaphane (SFN) as well as ectopic Nrf2 expression or knock-down of the Nrf2 negative regulator keap1, which stabilizes Nrf2, inhibited RON expression and invasion of carcinoma cells. Consequently, our studies identified a novel functional role for Nrf2 as a "repressor" and RON kinase as a molecular target of SFN, which mediates the anti-tumor effects of SFN. These results are not limited to breast cancer cells since the Nrf2 inducer SFN stabilized Nrf2 and inhibited RON expression in carcinoma cells from various tumor types.

  11. Pnrc2 regulates 3'UTR-mediated decay of segmentation clock-associated transcripts during zebrafish segmentation.

    Science.gov (United States)

    Gallagher, Thomas L; Tietz, Kiel T; Morrow, Zachary T; McCammon, Jasmine M; Goldrich, Michael L; Derr, Nicolas L; Amacher, Sharon L

    2017-09-01

    Vertebrate segmentation is controlled by the segmentation clock, a molecular oscillator that regulates gene expression and cycles rapidly. The expression of many genes oscillates during segmentation, including hairy/Enhancer of split-related (her or Hes) genes, which encode transcriptional repressors that auto-inhibit their own expression, and deltaC (dlc), which encodes a Notch ligand. We previously identified the tortuga (tor) locus in a zebrafish forward genetic screen for genes involved in cyclic transcript regulation and showed that cyclic transcripts accumulate post-splicing in tor mutants. Here we show that cyclic mRNA accumulation in tor mutants is due to loss of pnrc2, which encodes a proline-rich nuclear receptor co-activator implicated in mRNA decay. Using an inducible in vivo reporter system to analyze transcript stability, we find that the her1 3'UTR confers Pnrc2-dependent instability to a heterologous transcript. her1 mRNA decay is Dicer-independent and likely employs a Pnrc2-Upf1-containing mRNA decay complex. Surprisingly, despite accumulation of cyclic transcripts in pnrc2-deficient embryos, we find that cyclic protein is expressed normally. Overall, we show that Pnrc2 promotes 3'UTR-mediated decay of developmentally-regulated segmentation clock transcripts and we uncover an additional post-transcriptional regulatory layer that ensures oscillatory protein expression in the absence of cyclic mRNA decay. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Nanos-mediated repression of hid protects larval sensory neurons after a global switch in sensitivity to apoptotic signals.

    Science.gov (United States)

    Bhogal, Balpreet; Plaza-Jennings, Amara; Gavis, Elizabeth R

    2016-06-15

    Dendritic arbor morphology is a key determinant of neuronal function. Once established, dendrite branching patterns must be maintained as the animal develops to ensure receptive field coverage. The translational repressors Nanos (Nos) and Pumilio (Pum) are required to maintain dendrite growth and branching of Drosophila larval class IV dendritic arborization (da) neurons, but their specific regulatory role remains unknown. We show that Nos-Pum-mediated repression of the pro-apoptotic gene head involution defective (hid) is required to maintain a balance of dendritic growth and retraction in class IV da neurons and that upregulation of hid results in decreased branching because of an increase in caspase activity. The temporal requirement for nos correlates with an ecdysone-triggered switch in sensitivity to apoptotic stimuli that occurs during the mid-L3 transition. We find that hid is required during pupariation for caspase-dependent pruning of class IV da neurons and that Nos and Pum delay pruning. Together, these results suggest that Nos and Pum provide a crucial neuroprotective regulatory layer to ensure that neurons behave appropriately in response to developmental cues. © 2016. Published by The Company of Biologists Ltd.

  13. Estimation of Causal Mediation Effects for a Dichotomous Outcome in Multiple-Mediator Models using the Mediation Formula

    OpenAIRE

    Wang, Wei; Nelson, Suchitra; Albert, Jeffrey M.

    2013-01-01

    Mediators are intermediate variables in the causal pathway between an exposure and an outcome. Mediation analysis investigates the extent to which exposure effects occur through these variables, thus revealing causal mechanisms. In this paper, we consider the estimation of the mediation effect when the outcome is binary and multiple mediators of different types exist. We give a precise definition of the total mediation effect as well as decomposed mediation effects through individual or sets ...

  14. Lentiviral-mediated targeted NF-kappaB blockade in dorsal spinal cord glia attenuates sciatic nerve injury-induced neuropathic pain in the rat.

    Science.gov (United States)

    Meunier, Alice; Latrémolière, Alban; Dominguez, Elisa; Mauborgne, Annie; Philippe, Stéphanie; Hamon, Michel; Mallet, Jacques; Benoliel, Jean-Jacques; Pohl, Michel

    2007-04-01

    Neuropathic pain developing after peripheral nerve injury is associated with altered neuronal and glial cell functions in the spinal cord. Activated glia produces algogenic mediators, exacerbating pain. Among the different intracellular pathways possibly involved in the modified glial function, the nuclear factor kappaB (NF-kappaB) system is of particular interest, as numerous genes encoding inflammation- and pain-related molecules are controlled by this transcription factor. NF-kappaB is a pleiotropic factor also involved in central nervous system homeostasy. To study its role in chronic pain, it is thus essential to inhibit the NF-kappaB pathway selectively in activated spinal glial cells. Here, we show that when restricted to spinal cord and targeted to glial cells, lentiviral vector-mediated delivery of NF-kappaB super- repressor IkappaBalpha resulted in an inhibition of the NF-kappaB pathway activated in the rat spinal cord after sciatic nerve injury (chronic constriction injury, CCI). Concomitantly, IkappaBalpha overproduction prevented the enhanced expression of interleukin-6 and of inducible nitric oxide synthase associated with chronic constriction injury and resulted in prolonged antihyperalgesic and antiallodynic effects. These data show that targeted blockade of NF-kappaB activity in spinal glia efficiently alleviates pain behavior in CCI rats, demonstrating the active participation of the glial NF-kappaB pathway in the development of neuropathic pain after peripheral nerve injury.

  15. Lentiviral-mediated Targeted NF-κB Blockade in Dorsal Spinal Cord Glia Attenuates Sciatic Nerve Injury-induced Neuropathic Pain in the Rat.

    Science.gov (United States)

    Meunier, Alice; Latrémolière, Alban; Dominguez, Elisa; Mauborgne, Annie; Philippe, Stéphanie; Hamon, Michel; Mallet, Jacques; Benoliel, Jean-Jacques; Pohl, Michel

    2007-04-01

    Neuropathic pain developing after peripheral nerve injury is associated with altered neuronal and glial cell functions in the spinal cord. Activated glia produces algogenic mediators, exacerbating pain. Among the different intracellular pathways possibly involved in the modified glial function, the nuclear factor κB (NF-κB) system is of particular interest, as numerous genes encoding inflammation- and pain-related molecules are controlled by this transcription factor. NF-κB is a pleiotropic factor also involved in central nervous system homeostasy. To study its role in chronic pain, it is thus essential to inhibit the NF-κB pathway selectively in activated spinal glial cells. Here, we show that when restricted to spinal cord and targeted to glial cells, lentiviral vector-mediated delivery of NF-κB super- repressor IκBα resulted in an inhibition of the NF-κB pathway activated in the rat spinal cord after sciatic nerve injury (chronic constriction injury, CCI). Concomitantly, IκBα overproduction prevented the enhanced expression of interleukin-6 and of inducible nitric oxide synthase associated with chronic constriction injury and resulted in prolonged antihyperalgesic and antiallodynic effects. These data show that targeted blockade of NF-κB activity in spinal glia efficiently alleviates pain behavior in CCI rats, demonstrating the active participation of the glial NF-κB pathway in the development of neuropathic pain after peripheral nerve injury. Copyright © 2007 The American Society of Gene Therapy. Published by Elsevier Inc. All rights reserved.

  16. Mediation of information and educational mediation: conceptual discussions

    Directory of Open Access Journals (Sweden)

    Helena Célia de Souza Sacerdote

    2016-04-01

    Full Text Available Introduction: This is systematization of theoretical and methodological contributions related to the concepts of mediation information and pedagogical mediation in the literature. Objective: To understand possible intersection of information science and Online Education with regard to these concepts to check that both can be considered as analogous in its essence and practice. Methodology: Literature review based on literature by consulting the scientific productions selected in search of SciELO.ORG databases and EBSCO Host, the portal of CAPES / MEC and Google Scholar. Results: The most cited concepts in information science and education were de Almeida Junior (2009 and Masetto (2013, respectively. Conclusion: It is observed that the concept of mediation can move interchangeably between both areas. This is because the evidence found in the productions of the last five years indicate that the concept of information of mediation seems to have found its bases in education (educational psychology.

  17. The mediatization of ethical consumption

    DEFF Research Database (Denmark)

    Eskjær, Mikkel Fugl

    2013-01-01

    Over the years, mediatization studies have investigated the influence of media in numerous sections of contemporary society. One area that has received limited attention is the mediatization of consumption, particularly issues concerning ethical consumption. This article presents a study of how...... mediatization is transforming modern consumption and contributing to the mainstreaming of ethical consumption. Based on a study of a Danish online eco-store, the article argues that modern ethical consumption increasingly depends on new media practices to present sustainable consumption as practical...

  18. Assay of mast cell mediators

    DEFF Research Database (Denmark)

    Rådinger, Madeleine; Jensen, Bettina M; Swindle, Emily

    2015-01-01

    Mediator release from activated mast cells is a major initiator of the symptomology associated with allergic disorders such as anaphylaxis and asthma. Thus, methods to monitor the generation and release of such mediators have widespread applicability in studies designed to understand the processes...... regulating mast cell activation and for the identification of therapeutic approaches to block mast cell-driven disease. In this chapter, we discuss approaches used for the determination of mast cell degranulation, lipid-derived inflammatory mediator production, and cytokine/chemokine gene expression as well...

  19. Doing statistical mediation and moderation

    CERN Document Server

    Jose, Paul E

    2013-01-01

    Written in a friendly, conversational style, this book offers a hands-on approach to statistical mediation and moderation for both beginning researchers and those familiar with modeling. Starting with a gentle review of regression-based analysis, Paul Jose covers basic mediation and moderation techniques before moving on to advanced topics in multilevel modeling, structural equation modeling, and hybrid combinations, such as moderated mediation. User-friendly features include numerous graphs and carefully worked-through examples; ""Helpful Suggestions"" about procedures and pitfalls; ""Knowled

  20. Estimation of causal mediation effects for a dichotomous outcome in multiple-mediator models using the mediation formula.

    Science.gov (United States)

    Wang, Wei; Nelson, Suchitra; Albert, Jeffrey M

    2013-10-30

    Mediators are intermediate variables in the causal pathway between an exposure and an outcome. Mediation analysis investigates the extent to which exposure effects occur through these variables, thus revealing causal mechanisms. In this paper, we consider the estimation of the mediation effect when the outcome is binary and multiple mediators of different types exist. We give a precise definition of the total mediation effect as well as decomposed mediation effects through individual or sets of mediators using the potential outcomes framework. We formulate a model of joint distribution (probit-normal) using continuous latent variables for any binary mediators to account for correlations among multiple mediators. A mediation formula approach is proposed to estimate the total mediation effect and decomposed mediation effects based on this parametric model. Estimation of mediation effects through individual or subsets of mediators requires an assumption involving the joint distribution of multiple counterfactuals. We conduct a simulation study that demonstrates low bias of mediation effect estimators for two-mediator models with various combinations of mediator types. The results also show that the power to detect a nonzero total mediation effect increases as the correlation coefficient between two mediators increases, whereas power for individual mediation effects reaches a maximum when the mediators are uncorrelated. We illustrate our approach by applying it to a retrospective cohort study of dental caries in adolescents with low and high socioeconomic status. Sensitivity analysis is performed to assess the robustness of conclusions regarding mediation effects when the assumption of no unmeasured mediator-outcome confounders is violated. Copyright © 2013 John Wiley & Sons, Ltd.

  1. Estimation of Causal Mediation Effects for a Dichotomous Outcome in Multiple-Mediator Models using the Mediation Formula

    Science.gov (United States)

    Nelson, Suchitra; Albert, Jeffrey M.

    2013-01-01

    Mediators are intermediate variables in the causal pathway between an exposure and an outcome. Mediation analysis investigates the extent to which exposure effects occur through these variables, thus revealing causal mechanisms. In this paper, we consider the estimation of the mediation effect when the outcome is binary and multiple mediators of different types exist. We give a precise definition of the total mediation effect as well as decomposed mediation effects through individual or sets of mediators using the potential outcomes framework. We formulate a model of joint distribution (probit-normal) using continuous latent variables for any binary mediators to account for correlations among multiple mediators. A mediation formula approach is proposed to estimate the total mediation effect and decomposed mediation effects based on this parametric model. Estimation of mediation effects through individual or subsets of mediators requires an assumption involving the joint distribution of multiple counterfactuals. We conduct a simulation study that demonstrates low bias of mediation effect estimators for two-mediator models with various combinations of mediator types. The results also show that the power to detect a non-zero total mediation effect increases as the correlation coefficient between two mediators increases, while power for individual mediation effects reaches a maximum when the mediators are uncorrelated. We illustrate our approach by applying it to a retrospective cohort study of dental caries in adolescents with low and high socioeconomic status. Sensitivity analysis is performed to assess the robustness of conclusions regarding mediation effects when the assumption of no unmeasured mediator-outcome confounders is violated. PMID:23650048

  2. Mediation analysis with multiple versions of the mediator

    OpenAIRE

    VanderWeele, Tyler J.

    2012-01-01

    The causal inference literature has provided definitions of direct and indirect effects based on counterfactuals that generalize the approach found in the social science literature. However, these definitions presuppose well defined hypothetical interventions on the mediator. In many settings there may be multiple ways to fix the mediator to a particular value and these different hypothetical interventions may have very different implications for the outcome of interest. In this paper we cons...

  3. Pathogenicity Island Cross Talk Mediated by Recombination Directionality Factors Facilitates Excision from the Chromosome.

    Science.gov (United States)

    Carpenter, Megan R; Rozovsky, Sharon; Boyd, E Fidelma

    2015-12-14

    Pathogenicity islands (PAIs) are mobile integrated genetic elements (MIGEs) that contain a diverse range of virulence factors and are essential in the evolution of pathogenic bacteria. PAIs are widespread among bacteria and integrate into the host genome, commonly at a tRNA locus, via integrase-mediated site-specific recombination. The excision of PAIs is the first step in the horizontal transfer of these elements and is not well understood. In this study, we examined the role of recombination directionality factors (RDFs) and their relationship with integrases in the excision of two PAIs essential for Vibrio cholerae host colonization: Vibrio pathogenicity island 1 (VPI-1) and VPI-2. VPI-1 does not contain an RDF, which allowed us to answer the question of whether RDFs are an absolute requirement for excision. We found that an RDF was required for efficient excision of VPI-2 but not VPI-1 and that RDFs can induce excision of both islands. Expression data revealed that the RDFs act as transcriptional repressors to both VPI-1- and VPI-2-encoded integrases. We demonstrated that the RDFs Vibrio excision factor A (VefA) and VefB bind at the attachment sites (overlapping the int promoter region) of VPI-1 and VPI-2, thus supporting this mode of integrase repression. In addition, V. cholerae RDFs are promiscuous due to their dual functions of promoting excision of both VPI-1 and VPI-2 and acting as negative transcriptional regulators of the integrases. This is the first demonstration of cross talk between PAIs mediated via RDFs which reveals the complex interactions that occur between separately acquired MIGEs. Deciphering the mechanisms of pathogenicity island excision is necessary for understanding the evolution and spread of these elements to their nonpathogenic counterparts. Such mechanistic insight would assist in predicting the mobility of uncharacterized genetic elements. This study identified extensive RDF-mediated cross talk between two nonhomologous VPIs and

  4. Dimensional reduction in anomaly mediation

    International Nuclear Information System (INIS)

    Boyda, Ed; Murayama, Hitoshi; Pierce, Aaron

    2002-01-01

    We offer a guide to dimensional reduction in theories with anomaly-mediated supersymmetry breaking. Evanescent operators proportional to ε arise in the bare Lagrangian when it is reduced from d=4 to d=4-2ε dimensions. In the course of a detailed diagrammatic calculation, we show that inclusion of these operators is crucial. The evanescent operators conspire to drive the supersymmetry-breaking parameters along anomaly-mediation trajectories across heavy particle thresholds, guaranteeing the ultraviolet insensitivity

  5. Epoxide-mediated differential packaging of Cif and other virulence factors into outer membrane vesicles.

    Science.gov (United States)

    Ballok, Alicia E; Filkins, Laura M; Bomberger, Jennifer M; Stanton, Bruce A; O'Toole, George A

    2014-10-01

    Pseudomonas aeruginosa produces outer membrane vesicles (OMVs) that contain a number of secreted bacterial proteins, including phospholipases, alkaline phosphatase, and the CFTR inhibitory factor (Cif). Previously, Cif, an epoxide hydrolase, was shown to be regulated at the transcriptional level by epoxides, which serve as ligands of the repressor, CifR. Here, we tested whether epoxides have an effect on Cif levels in OMVs. We showed that growth of P. aeruginosa in the presence of specific epoxides but not a hydrolysis product increased Cif packaging into OMVs in a CifR-independent fashion. The outer membrane protein, OprF, was also increased under these conditions, but alkaline phosphatase activity was not significantly altered. Additionally, we demonstrated that OMV shape and density were affected by epoxide treatment, with two distinct vesicle fractions present when cells were treated with epibromohydrin (EBH), a model epoxide. Vesicles isolated from the two density fractions exhibited different protein profiles in Western blotting and silver staining. We have shown that a variety of clinically or host-relevant treatments, including antibiotics, also alter the proteins packaged in OMVs. Proteomic analysis of purified OMVs followed by an analysis of transposon mutant OMVs yielded mutants with altered vesicle packaging. Finally, epithelial cell cytotoxicity was reduced in the vesicles formed in the presence of EBH, suggesting that this epoxide alters the function of the OMVs. Our data support a model whereby clinically or host-relevant signals mediate differential packaging of virulence factors in OMVs, which results in functional consequences for host-pathogen interactions. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  6. Transcription factor activating protein 2 beta (TFAP2B) mediates noradrenergic neuronal differentiation in neuroblastoma.

    Science.gov (United States)

    Ikram, Fakhera; Ackermann, Sandra; Kahlert, Yvonne; Volland, Ruth; Roels, Frederik; Engesser, Anne; Hertwig, Falk; Kocak, Hayriye; Hero, Barbara; Dreidax, Daniel; Henrich, Kai-Oliver; Berthold, Frank; Nürnberg, Peter; Westermann, Frank; Fischer, Matthias

    2016-02-01

    Neuroblastoma is an embryonal pediatric tumor that originates from the developing sympathetic nervous system and shows a broad range of clinical behavior, ranging from fatal progression to differentiation into benign ganglioneuroma. In experimental neuroblastoma systems, retinoic acid (RA) effectively induces neuronal differentiation, and RA treatment has been therefore integrated in current therapies. However, the molecular mechanisms underlying differentiation are still poorly understood. We here investigated the role of transcription factor activating protein 2 beta (TFAP2B), a key factor in sympathetic nervous system development, in neuroblastoma pathogenesis and differentiation. Microarray analyses of primary neuroblastomas (n = 649) demonstrated that low TFAP2B expression was significantly associated with unfavorable prognostic markers as well as adverse patient outcome. We also found that low TFAP2B expression was strongly associated with CpG methylation of the TFAP2B locus in primary neuroblastomas (n = 105) and demethylation with 5-aza-2'-deoxycytidine resulted in induction of TFAP2B expression in vitro, suggesting that TFAP2B is silenced by genomic methylation. Tetracycline inducible re-expression of TFAP2B in IMR-32 and SH-EP neuroblastoma cells significantly impaired proliferation and cell cycle progression. In IMR-32 cells, TFAP2B induced neuronal differentiation, which was accompanied by up-regulation of the catecholamine biosynthesizing enzyme genes DBH and TH, and down-regulation of MYCN and REST, a master repressor of neuronal genes. By contrast, knockdown of TFAP2B by lentiviral transduction of shRNAs abrogated RA-induced neuronal differentiation of SH-SY5Y and SK-N-BE(2)c neuroblastoma cells almost completely. Taken together, our results suggest that TFAP2B is playing a vital role in retaining RA responsiveness and mediating noradrenergic neuronal differentiation in neuroblastoma. Copyright © 2015 Federation of European Biochemical Societies

  7. Bombyx mori E26 transformation-specific 2 (BmEts2), an Ets family protein, represses Bombyx mori Rels (BmRels)-mediated promoter activation of antimicrobial peptide genes in the silkworm Bombyx mori.

    Science.gov (United States)

    Tanaka, H; Sagisaka, A; Suzuki, N; Yamakawa, M

    2016-10-01

    E26 transformation-specific (Ets) family transcription factors are known to play roles in various biological phenomena, including immunity, in vertebrates. However, the mechanisms by which Ets proteins contribute to immunity in invertebrates remain poorly understood. In this study, we identified a cDNA encoding BmEts2, which is a putative orthologue of Drosophila Yan and human translocation-ets-leukemia/Ets-variant gene 6, from the silkworm Bombyx mori. Expression of the BmEts2 gene was significantly increased in the fat bodies of silkworm larvae in response to injection with Escherichia coli and Staphylococcus aureus. BmEts2 overexpression dramatically repressed B. mori Rels (BmRels)-mediated promoter activation of antimicrobial peptide genes in silkworm cells. Conversely, gene knockdown of BmEts2 significantly enhanced BmRels activity. In addition, two κB sites located on the 5' upstream region of cecropin B1 were found to be involved in the repression of BmRels-mediated promoter activation. Protein-competition analysis further demonstrated that BmEts2 competitively inhibited binding of BmRels to κB sites. Overall, BmEts2 acts as a repressor of BmRels-mediated transactivation of antimicrobial protein genes by inhibiting the binding of BmRels to κB sites. © 2016 The Royal Entomological Society.

  8. Application of a fuzzy neural network model in predicting polycyclic aromatic hydrocarbon-mediated perturbations of the Cyp1b1 transcriptional regulatory network in mouse skin

    Energy Technology Data Exchange (ETDEWEB)

    Larkin, Andrew [Department of Environmental and Molecular Toxicology, Oregon State University (United States); Department of Statistics, Oregon State University (United States); Superfund Research Center, Oregon State University (United States); Siddens, Lisbeth K. [Department of Environmental and Molecular Toxicology, Oregon State University (United States); Superfund Research Center, Oregon State University (United States); Krueger, Sharon K. [Superfund Research Center, Oregon State University (United States); Linus Pauling Institute, Oregon State University (United States); Tilton, Susan C.; Waters, Katrina M. [Superfund Research Center, Oregon State University (United States); Computational Biology and Bioinformatics Group, Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Williams, David E., E-mail: david.williams@oregonstate.edu [Department of Environmental and Molecular Toxicology, Oregon State University (United States); Superfund Research Center, Oregon State University (United States); Linus Pauling Institute, Oregon State University (United States); Environmental Health Sciences Center, Oregon State University, Corvallis, OR 97331 (United States); Baird, William M. [Department of Environmental and Molecular Toxicology, Oregon State University (United States); Superfund Research Center, Oregon State University (United States); Environmental Health Sciences Center, Oregon State University, Corvallis, OR 97331 (United States)

    2013-03-01

    Polycyclic aromatic hydrocarbons (PAHs) are present in the environment as complex mixtures with components that have diverse carcinogenic potencies and mostly unknown interactive effects. Non-additive PAH interactions have been observed in regulation of cytochrome P450 (CYP) gene expression in the CYP1 family. To better understand and predict biological effects of complex mixtures, such as environmental PAHs, an 11 gene input-1 gene output fuzzy neural network (FNN) was developed for predicting PAH-mediated perturbations of dermal Cyp1b1 transcription in mice. Input values were generalized using fuzzy logic into low, medium, and high fuzzy subsets, and sorted using k-means clustering to create Mamdani logic functions for predicting Cyp1b1 mRNA expression. Model testing was performed with data from microarray analysis of skin samples from FVB/N mice treated with toluene (vehicle control), dibenzo[def,p]chrysene (DBC), benzo[a]pyrene (BaP), or 1 of 3 combinations of diesel particulate extract (DPE), coal tar extract (CTE) and cigarette smoke condensate (CSC) using leave-one-out cross-validation. Predictions were within 1 log{sub 2} fold change unit of microarray data, with the exception of the DBC treatment group, where the unexpected down-regulation of Cyp1b1 expression was predicted but did not reach statistical significance on the microarrays. Adding CTE to DPE was predicted to increase Cyp1b1 expression, whereas adding CSC to CTE and DPE was predicted to have no effect, in agreement with microarray results. The aryl hydrocarbon receptor repressor (Ahrr) was determined to be the most significant input variable for model predictions using back-propagation and normalization of FNN weights. - Highlights: ► Tested a model to predict PAH mixture-mediated changes in Cyp1b1 expression ► Quantitative predictions in agreement with microarrays for Cyp1b1 induction ► Unexpected difference in expression between DBC and other treatments predicted ► Model predictions

  9. Canonical TGF-β Signaling Negatively Regulates Neuronal Morphogenesis through TGIF/Smad Complex-Mediated CRMP2 Suppression.

    Science.gov (United States)

    Nakashima, Hideyuki; Tsujimura, Keita; Irie, Koichiro; Ishizu, Masataka; Pan, Miao; Kameda, Tomonori; Nakashima, Kinichi

    2018-05-16

    Functional neuronal connectivity requires proper neuronal morphogenesis and its dysregulation causes neurodevelopmental diseases. Transforming growth factor-β (TGF-β) family cytokines play pivotal roles in development, but little is known about their contribution to morphological development of neurons. Here we show that the Smad-dependent canonical signaling of TGF-β family cytokines negatively regulates neuronal morphogenesis during brain development. Mechanistically, activated Smads form a complex with transcriptional repressor TG-interacting factor (TGIF), and downregulate the expression of a neuronal polarity regulator, collapsin response mediator protein 2. We also demonstrate that TGF-β family signaling inhibits neurite elongation of human induced pluripotent stem cell-derived neurons. Furthermore, the expression of TGF-β receptor 1, Smad4, or TGIF, which have mutations found in patients with neurodevelopmental disorders, disrupted neuronal morphogenesis in both mouse (male and female) and human (female) neurons. Together, these findings suggest that the regulation of neuronal morphogenesis by an evolutionarily conserved function of TGF-β signaling is involved in the pathogenesis of neurodevelopmental diseases. SIGNIFICANCE STATEMENT Canonical transforming growth factor-β (TGF-β) signaling plays a crucial role in multiple organ development, including brain, and mutations in components of the signaling pathway associated with several human developmental disorders. In this study, we found that Smads/TG-interacting factor-dependent canonical TGF-β signaling regulates neuronal morphogenesis through the suppression of collapsin response mediator protein-2 (CRMP2) expression during brain development, and that function of this signaling is evolutionarily conserved in the mammalian brain. Mutations in canonical TGF-β signaling factors identified in patients with neurodevelopmental disorders disrupt the morphological development of neurons. Thus, our

  10. 22 CFR 218.33 - Mediation.

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Mediation. 218.33 Section 218.33 Foreign... § 218.33 Mediation. (a) Referral of complaints for mediation. The agency will refer to the Federal Mediation and Conciliation Service all complaints that: (1) fall within the jurisdiction of these...

  11. 15 CFR 923.54 - Mediation.

    Science.gov (United States)

    2010-01-01

    ... 15 Commerce and Foreign Trade 3 2010-01-01 2010-01-01 false Mediation. 923.54 Section 923.54... Mediation. (a) Section 307(h) of the Act provides for mediation of serious disagreement between any Federal... cases, mediation by the Secretary, with the assistance of the Executive Office of the President, may be...

  12. 10 CFR 4.333 - Mediation.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Mediation. 4.333 Section 4.333 Energy NUCLEAR REGULATORY... Investigation, Conciliation, and Enforcement Procedures § 4.333 Mediation. (a) Referral of complaints for mediation. NRC will refer to a mediation agency designated by the Secretary of the Department of Health and...

  13. 45 CFR 1156.16 - Mediation.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 3 2010-10-01 2010-10-01 false Mediation. 1156.16 Section 1156.16 Public Welfare... Procedures § 1156.16 Mediation. (a) Referral of complaints for mediation. The Endowment will promptly refer all complaints to the agency designated by the Secretary of HHS to manage the mediation process that...

  14. 15 CFR 930.111 - OCRM mediation.

    Science.gov (United States)

    2010-01-01

    ... 15 Commerce and Foreign Trade 3 2010-01-01 2010-01-01 false OCRM mediation. 930.111 Section 930... FEDERAL CONSISTENCY WITH APPROVED COASTAL MANAGEMENT PROGRAMS Secretarial Mediation § 930.111 OCRM mediation. The availability of mediation does not preclude use by the parties of alternative means for...

  15. 14 CFR 1252.402 - Mediation.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Mediation. 1252.402 Section 1252.402... Procedures § 1252.402 Mediation. (a) Referral of complaints for mediation. NASA will refer to the Federal Mediation and Conciliation Service all complaints that: (1) Fall within the jurisdiction of the Act and...

  16. 10 CFR 1040.89-6 - Mediation.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Mediation. 1040.89-6 Section 1040.89-6 Energy DEPARTMENT... Enforcement Procedures § 1040.89-6 Mediation. (a) Referral of complaints for mediation. DOE will refer to the Federal Mediation and Conciliation Service, in accordance with 45 CFR 90.43(c)(3), all complaints that: (1...

  17. 34 CFR 110.32 - Mediation.

    Science.gov (United States)

    2010-07-01

    ... 34 Education 1 2010-07-01 2010-07-01 false Mediation. 110.32 Section 110.32 Education Regulations..., Conciliation, and Enforcement Procedures § 110.32 Mediation. (a) ED promptly refers to the Federal Mediation and Conciliation Service or to the mediation agency designated by the Secretary of Health and Human...

  18. 7 CFR 780.9 - Mediation.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 7 2010-01-01 2010-01-01 false Mediation. 780.9 Section 780.9 Agriculture Regulations... PROGRAMS APPEAL REGULATIONS § 780.9 Mediation. (a) Any request for mediation must be submitted after... once: (1) If resolution of an adverse decision is not achieved in mediation, a participant may exercise...

  19. 24 CFR 146.35 - Mediation.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false Mediation. 146.35 Section 146.35... ASSISTANCE Investigation, Settlement, and Enforcement Procedures § 146.35 Mediation. (a) HUD shall refer to the Federal Mediation and Conciliation Service, a mediation agency designated by the Secretary of...

  20. 7 CFR 614.11 - Mediation.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 6 2010-01-01 2010-01-01 false Mediation. 614.11 Section 614.11 Agriculture... AGRICULTURE CONSERVATION OPERATIONS NRCS APPEAL PROCEDURES § 614.11 Mediation. (a) A participant who wishes to pursue mediation must file request for mediation under this part with the NRCS official designated in the...

  1. 15 CFR 20.12 - Mediation.

    Science.gov (United States)

    2010-01-01

    ... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Mediation. 20.12 Section 20.12... Procedures § 20.12 Mediation. (a) DOC will refer to a mediation service designated by the Secretary all... further processing. (b) Both the complainant and the recipient shall participate in the mediation process...

  2. 38 CFR 18.543 - Mediation.

    Science.gov (United States)

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2010-07-01 2010-07-01 false Mediation. 18.543 Section... Enforcement Procedures § 18.543 Mediation. (a) Referral of complaints for mediation. VA will refer to the Federal Mediation and Conciliation Service all complaints that: (1) Fall within the jurisdiction of the...

  3. Mediation in Schools: Tapping the Potential

    Science.gov (United States)

    Hendry, Richard

    2010-01-01

    This article explores the developing role of mediation as a conflict resolution process in schools. It gives an accepted definition and clarifies the purposes of mediation, outlining the range of contexts in and beyond schools in which mediation is already offered as a formal intervention. The typical process of mediation itself is described. The…

  4. Mediation and Counseling Services: A Viable Partnership

    Science.gov (United States)

    Hodges, Shannon

    2009-01-01

    Mediation has become common in many areas of society, including marital dissolution, community disputes, governmental agencies, and business and industry. Though higher education has been slower than society to adopt mediation services, campus mediation is becoming increasingly more common. This article explains why mediation is a viable…

  5. 45 CFR 91.43 - Mediation.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Mediation. 91.43 Section 91.43 Public Welfare... Enforcement Procedures § 91.43 Mediation. (a) HHS will promptly refer to a mediation agency designated by the... mediation process to the extent necessary to reach an agreement or make an informed judgment that an...

  6. 43 CFR 17.332 - Mediation.

    Science.gov (United States)

    2010-10-01

    ... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false Mediation. 17.332 Section 17.332 Public..., and Enforcement Procedures § 17.332 Mediation. (a) Referral of complaints for mediation. DOI will... participate in the mediation process to the extent necessary to reach an agreement or make an informed...

  7. Neutrality in mediation: an ambiguous ethical value

    OpenAIRE

    Bailey, Paul

    2014-01-01

    Mediator neutrality would appear, by definition, to be a necessary and required ethical principle for all mediators to practice. But what is meant by neutrality in mediation? Is it practically possible to be completely neutral between parties in mediation while at the same time being fair to both of them? This paper attempts to answer these two questions.

  8. 7 CFR 900.108 - Mediator's report.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Mediator's report. 900.108 Section 900.108 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Mediator's report. The mediator, upon the completion of mediation proceedings, shall submit to the...

  9. Strongly coupled semidirect mediation of supersymmetry breaking

    International Nuclear Information System (INIS)

    Ibe, M.; Izawa, K.-I.; Nakai, Y.

    2009-01-01

    Strongly coupled semidirect gauge mediation models of supersymmetry breaking through massive mediators with standard-model charges are investigated by means of composite degrees of freedom. Sizable mediation is realized to generate the standard-model gaugino masses for a small mediator mass without breaking the standard-model symmetries.

  10. Gaugino-assisted anomaly mediation

    International Nuclear Information System (INIS)

    Kribs, Graham D.

    2001-01-01

    I present a model of supersymmetry breaking mediated through a small extra dimension. Standard model matter multiplets and a supersymmetry-breaking (or 'hidden') sector are confined to opposite four-dimensional boundaries while gauge multiplets live in the bulk. The hidden sector does not contain a singlet and the dominant contribution to gaugino masses is via anomaly-mediated supersymmetry breaking. Scalar masses get contributions from both anomaly mediation and a tiny hard breaking of supersymmetry by operators on the hidden-sector boundary. These operators contribute to scalar masses at one loop and in most of parameter space, their contribution dominates. Thus it is easy to make all squared scalar masses positive. As no additional fields or symmetries are required below the Planck scale, this is among the simplest working models of anomaly mediation. The gaugino spectrum is left untouched and the phenomenology of the model is roughly similar to anomaly mediated supersymmetry breaking with a universal scalar mass added. Finally, the main differences in the spectrum between this model and other approaches are identified. This talk is based on work [1] done in collaboration with David E. Kaplan

  11. Gaugino-Assisted Anomaly Mediation

    International Nuclear Information System (INIS)

    Kaplan, David Elazzar; Kribs, Graham D.

    2000-01-01

    We present a model of supersymmetry breaking mediated through a small extra dimension. Standard model matter multiplets and a supersymmetry-breaking (or ''hidden'') sector are confined to opposite four-dimensional boundaries while gauge multiplets live in the bulk. The hidden sector does not contain a singlet and the dominant contribution to gaugino masses is via anomaly-mediated supersymmetry breaking. Scalar masses get contributions from both anomaly mediation and a tiny hard breaking of supersymmetry by operators on the hidden-sector boundary. These operators contribute to scalar masses at one loop and in most of parameter space, their contribution dominates. Thus it is easy to make all squared scalar masses positive. As no additional fields or symmetries are required below the Planck scale, we consider this the simplest working model of anomaly mediation. The gaugino spectrum is left untouched and the phenomenology of the model is roughly similar to anomaly mediated supersymmetry breaking with a universal scalar mass added. We identify the main differences in the spectrum between this model and other approaches. We also discuss mechanisms for generating the μ term and constraints on additional bulk fields. (author)

  12. Three tasks for mediatization research

    DEFF Research Database (Denmark)

    Ekstrøm, Mats; Fornäs, Johan; Jansson, André

    2016-01-01

    Based on the interdisciplinary experience of a Swedish research committee, this article discusses critical conceptual issues raised by the current debate on mediatization – a concept that holds great potential to constitute a space for synthesized understandings of media-related social transforma......Based on the interdisciplinary experience of a Swedish research committee, this article discusses critical conceptual issues raised by the current debate on mediatization – a concept that holds great potential to constitute a space for synthesized understandings of media-related social...... that mediatization researchers have sometimes formulated too grand claims as to mediatization’s status as a unitary approach, a meta-theory or a paradigm. Such claims have led to problematic confusions around the concept and should be abandoned in favour of a more open agenda. In line with such a call for openness...

  13. Gauge mediated mini-split

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Timothy [Institute of Theoretical Science, University of Oregon,Eugene, OR 97403 (United States); Craig, Nathaniel [Department of Physics, University of California,Santa Barbara, CA 93106 (United States); Knapen, Simon [Berkeley Center for Theoretical Physics,University of California, Berkeley, CA 94720 (United States); Theoretical Physics Group,Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2016-03-15

    We propose a simple model of split supersymmetry from gauge mediation. This model features gauginos that are parametrically a loop factor lighter than scalars, accommodates a Higgs boson mass of 125 GeV, and incorporates a simple solution to the μ−b{sub μ} problem. The gaugino mass suppression can be understood as resulting from collective symmetry breaking. Imposing collider bounds on μ and requiring viable electroweak symmetry breaking implies small a-terms and small tan β — the stop mass ranges from 10{sup 5} to 10{sup 8} GeV. In contrast with models with anomaly + gravity mediation (which also predict a one-loop loop suppression for gaugino masses), our gauge mediated scenario predicts aligned squark masses and a gravitino LSP. Gluinos, electroweakinos and Higgsinos can be accessible at the LHC and/or future colliders for a wide region of the allowed parameter space.

  14. Mediation in Legal English Teaching

    Directory of Open Access Journals (Sweden)

    Chovancová Barbora

    2016-06-01

    Full Text Available Mediation is a language activity that has been unjustly neglected when preparing law students for their future professional careers. When trained in a professional context, students need to develop and improve complex communicative skills. These include not only the traditional language skills such as reading, writing, listening and speaking, but also more advanced skills such as summarizing, providing definitions, changing registers etc. All these are involved in the students’ acquisition of ‘soft skills’ that are particularly important for students of law since much of their future work involves interpersonal lawyer-client interaction. This article argues that mediation is a crucial (though previously underestimated skill and that law-oriented ESP instruction should provide training aimed at developing this skill. Showing a practical application of this approach, the paper demonstrates that mediation can be successfully integrated in the legal English syllabus and make the learning of legal English more effective.

  15. Radical-Mediated Enzymatic Polymerizations

    Science.gov (United States)

    Zavada, Scott R.; Battsengel, Tsatsral; Scott, Timothy F.

    2016-01-01

    Polymerization reactions are commonly effected by exposing monomer formulations to some initiation stimulus such as elevated temperature, light, or a chemical reactant. Increasingly, these polymerization reactions are mediated by enzymes―catalytic proteins―owing to their reaction efficiency under mild conditions as well as their environmental friendliness. The utilization of enzymes, particularly oxidases and peroxidases, for generating radicals via reduction-oxidation mechanisms is especially common for initiating radical-mediated polymerization reactions, including vinyl chain-growth polymerization, atom transfer radical polymerization, thiol–ene step-growth polymerization, and polymerization via oxidative coupling. While enzyme-mediated polymerization is useful for the production of materials intended for subsequent use, it is especially well-suited for in situ polymerizations, where the polymer is formed in the place where it will be utilized. Such polymerizations are especially useful for biomedical adhesives and for sensing applications. PMID:26848652

  16. Mediatization Theory and Digital Media

    DEFF Research Database (Denmark)

    Finnemann, Niels Ole

    2011-01-01

    In the 20th century, the term "media logic" was introduced to denote the influence of independent mass media on political systems and other institutions. In recent years the idea has been reworked and labelled "mediatization" to widen the framework by including new media and new areas of applicat......In the 20th century, the term "media logic" was introduced to denote the influence of independent mass media on political systems and other institutions. In recent years the idea has been reworked and labelled "mediatization" to widen the framework by including new media and new areas...

  17. Surfactant-Mediated Growth Revisited

    International Nuclear Information System (INIS)

    Meyerheim, H. L.; Sander, D.; Popescu, R.; Pan, W.; Kirschner, J.; Popa, I.

    2007-01-01

    The x-ray structure analysis of the oxygen-surfactant-mediated growth of Ni on Cu(001) identifies up to 0.15 monolayers of oxygen in subsurface octahedral sites. This questions the validity of the general view that surfactant oxygen floats on top of the growing Ni film. Rather, the surfactant action is ascribed to an oxygen-enriched zone extending over the two topmost layers. Surface stress measurements support this finding. Our results have important implications for the microscopic understanding of surfactant-mediated growth and the change of the magnetic anisotropy of the Ni films

  18. Playful mediation and virtual sociality

    Directory of Open Access Journals (Sweden)

    Sihem NAJJAR

    2010-01-01

    Full Text Available As a space of sociability, virtual games, especially online role playing games, allow us to capture the interest of the playfulness in social life, but they are means by which users are able to experiment their relationship to others. The virtual games as a mediation device, constitute a "pretext" to forge friendships, develop love relationships, improve language skills, discover other cultures, etc. Based on a sociological survey of Tunisian Internet users (both sexes fans of virtual games we try to show how playful mediation is producing a multifaceted virtual sociality inherent in our contemporary societies.

  19. Family education and television mediation

    Directory of Open Access Journals (Sweden)

    Paz CÁNOVAS LEONHARDT

    2010-07-01

    Full Text Available This article try to deal with the complex influence of television viewing in the process of socialization of children and adolescents, focusing our attention on the importance of the family as the mediator-educator agency of particular relevance. Once analyzed the basic theoretical assumptions, we deepened in reality under study by providing data about how the studied population lives television and what extent parental mediation influences and affects the process. The article concludes with some reflections and pedagogical suggestions which trying to help to the optimization of the educational reality.

  20. Dynamical Messengers for Gauge Mediation

    Energy Technology Data Exchange (ETDEWEB)

    Hook, Anson; Torroba, Gonzalo; /SLAC /Stanford U., Phys. Dept.

    2011-08-17

    We construct models of indirect gauge mediation where the dynamics responsible for breaking supersymmetry simultaneously generates a weakly coupled subsector of messengers. This provides a microscopic realization of messenger gauge mediation where the messenger and hidden sector fields are unified into a single sector. The UV theory is SQCD with massless and massive quarks plus singlets, and at low energies it flows to a weakly coupled quiver gauge theory. One node provides the primary source of supersymmetry breaking, which is then transmitted to the node giving rise to the messenger fields. These models break R-symmetry spontaneously, produce realistic gaugino and sfermion masses, and give a heavy gravitino.

  1. 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

    2017-10-27

    2,3,7,8-Tetrachlorodibenzo- p -dioxin and related compounds are extraordinarily potent environmental toxic pollutants. Most of the 2,3,7,8-tetrachlorodibenzo- p -dioxin toxicities are mediated by aryl hydrocarbon receptor (AhR), a ligand-dependent transcription factor belonging to the basic helix-loop-helix (bHLH) Per-ARNT-Sim (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, because of 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, whereas 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. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  2. Mediating Multilingual Children's Language Resources

    Science.gov (United States)

    Potts, D.; Moran, M. J.

    2013-01-01

    The everyday reality of children's multilingualism is a significant resource for expanding students' perspectives on the world, but many questions remain regarding the negotiation of these resources in mainstream classrooms. Drawing on research from a long-term Canadian study of multiliterate pedagogies, this paper explores mediation of home…

  3. Trilinear-augmented gaugino mediation

    DEFF Research Database (Denmark)

    Heisig, Jan; Kersten, Jörn; Murphy, Nick

    2017-01-01

    We consider a gaugino-mediated supersymmetry breaking scenario where in addition to the gauginos the Higgs fields couple directly to the field that breaks supersymmetry. This yields non-vanishing trilinear scalar couplings in general, which can lead to large mixing in the stop sector providing...

  4. Anomaly mediation in superstring theory

    Energy Technology Data Exchange (ETDEWEB)

    Conlon, Joseph P. [Rudolf Peierls Center for Theoretical Physics, Oxford (United Kingdom); Balliol College, Oxford (United Kingdom); Goodsell, Mark [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Palti, Eran [Centre de Physique Theoretique, Ecole Polytechnique, CNRS, Palaiseau (France)

    2010-08-15

    We study anomaly mediated supersymmetry breaking in type IIB string theory and use our results to test the supergravity formula for anomaly mediated gaugino masses. We compute 1-loop gaugino masses for models of D3-branes on orbifold singularities with 3-form fluxes by calculating the annulus correlator of 3-form flux and two gauginos in the zero momentum limit. Consistent with supergravity expectations we find both anomalous and running contributions to 1-loop gaugino masses. For background Neveu-Schwarz H-flux we find an exact match with the supergravity formula. For Ramond-Ramond flux there is an off-shell ambiguity that precludes a full matching. The anomaly mediated gaugino masses, while determined by the infrared spectrum, arise from an explicit sum over UV open string winding modes. We also calculate brane-to-brane tree-level gravity mediated gaugino masses and show that there are two contributions coming from the dilaton and from the twisted modes, which are suppressed by the full T{sup 6} volume and the untwisted T{sup 2} volume respectively. (orig.)

  5. Sonic mediations: body, sound, technology

    NARCIS (Netherlands)

    Birdsall, C.; Enns, A.

    2008-01-01

    Sonic Mediations: Body, Sound, Technology is a collection of original essays that represents an invaluable contribution to the burgeoning field of sound studies. While sound is often posited as having a bridging function, as a passive in-between, this volume invites readers to rethink the concept of

  6. Diselenolane-mediated cellular uptake.

    Science.gov (United States)

    Chuard, Nicolas; Poblador-Bahamonde, Amalia I; Zong, Lili; Bartolami, Eline; Hildebrandt, Jana; Weigand, Wolfgang; Sakai, Naomi; Matile, Stefan

    2018-02-21

    The emerging power of thiol-mediated uptake with strained disulfides called for a move from sulfur to selenium. We report that according to results with fluorescent model substrates, cellular uptake with 1,2-diselenolanes exceeds uptake with 1,2-dithiolanes and epidithiodiketopiperazines with regard to efficiency as well as intracellular localization. The diselenide analog of lipoic acid performs best. This 1,2-diselenolane delivers fluorophores efficiently to the cytosol of HeLa Kyoto cells, without detectable endosomal capture as with 1,2-dithiolanes or dominant escape into the nucleus as with epidithiodiketopiperazines. Diselenolane-mediated cytosolic delivery is non-toxic (MTT assay), sensitive to temperature but insensitive to inhibitors of endocytosis (chlorpromazine, methyl-β-cyclodextrin, wortmannin, cytochalasin B) and conventional thiol-mediated uptake (Ellman's reagent), and to serum. Selenophilicity, the extreme CSeSeC dihedral angle of 0° and the high but different acidity of primary and secondary selenols might all contribute to uptake. Thiol-exchange affinity chromatography is introduced as operational mimic of thiol-mediated uptake that provides, in combination with rate enhancement of DTT oxidation, direct experimental evidence for existence and nature of the involved selenosulfides.

  7. Mediated Encryption: Analysis and Design

    Directory of Open Access Journals (Sweden)

    I. Elashry1

    2015-01-01

    Full Text Available Boneh, Ding and Tsudik presented identity-based mediated RSA encryption and signature systems in which the users are not allowed to decrypt/sign messages without the authorisation of a security mediator.We show that ID-MRSA is not secure and we present a secure modified version of it which is as efficient as the original system. We also propose a generic mediated encryption that translates any identity based encryption to a mediated version of this IBE. It envelops an IBE encrypted message using a user’s identity into an IBE envelope using the identity of the SEM. We present two security models based on the role of the adversary whether it is a revoked user or a hacked SEM. We prove that GME is as secure as the SEM’s IBE against a revoked user and as secure as the user’s IBE against a hacked SEM. We also present two implementations of GME based on Boneh-Franklin FullIBE system which is a pairing-based system and Boneh, Gentry and Hamburg (BGH system which is pairing-free system.

  8. Crime fiction and mediatized religion

    DEFF Research Database (Denmark)

    Hansen, Kim Toft

    Scandinavian media where religion has become mediatized. Consumers of popular culture no longer endorse confidence in institutionalized religion, but that does not mean that people are losing faith: Faith only seems to adjust itself and tiptoe into popular media and popular fiction. Hence, this paper seeks...

  9. Mediation –Voluntary or Mandatory Procedure

    Directory of Open Access Journals (Sweden)

    Angelica ROSU

    2010-03-01

    Full Text Available Part of modifications brought through 370/2009 Act to the 192/2006 Law concerning mediation and structure of mediator profession have been interpreted as establishing a preliminary mediation procedure before intimating the courts of law, in civil and commercial matters. This interpretation is in excess of operative legal provisions. Although the law in modified form stipulates the compulsoriness of judicial authorities and other jurisdictional bodies to inform the parties about the possibility and the dvantages of using mediation procedure and the obligation to guide the parties to resort at mediation, this circumstances does not affect the mediation particular voluntary nature.

  10. Profession of mediator as the professional provider of the mediation process

    Directory of Open Access Journals (Sweden)

    Jernej Šoštar

    2017-03-01

    Full Text Available The civil mediation programme, which is a court-connected programme, established as a form of alternative dispute resolution, is increasingly gaining ground as a field with its own theoretical and practical knowledge, principles and basic rules. Mediation has already set up its own body of knowledge, based on studies, classification of cases and the analyses of the results. In this article, we examine whether in the context of the development of mediation in Slovenia we might already talk about the profession of the mediator, defined as a provider of the mediation process. We examine the court-connected civil mediation and mediators who mediate at the court-connected civil mediation, and define them theoretically. By interviewing the mediation experts and mediators we examine their opinions about mediators and the court mediation. We examine the legal basis for the court-connected mediation programmes in Slovenia as well as in the European Union. Proceeding from our findings we conclude that the legal regulation of the court mediation in Slovenia is well established, and that the mediators of the court-connected civil mediation programmes can be accepted as the professional providers of the mediation process.

  11. Genomic responses to arsenic in the cyanobacterium Synechocystis sp. PCC 6803.

    Directory of Open Access Journals (Sweden)

    Ana María Sánchez-Riego

    Full Text Available Arsenic is a ubiquitous contaminant and a toxic metalloid which presents two main redox states in nature: arsenite [As(III] and arsenate [As(V]. Arsenic resistance in Synechocystis sp. strain PCC 6803 is mediated by the arsBHC operon and two additional arsenate reductases encoded by the arsI1 and arsI2 genes. Here we describe the genome-wide responses to the presence of arsenate and arsenite in wild type and mutants in the arsenic resistance system. Both forms of arsenic produced similar responses in the wild type strain, including induction of several stress related genes and repression of energy generation processes. These responses were transient in the wild type strain but maintained in time in an arsB mutant strain, which lacks the arsenite transporter. In contrast, the responses observed in a strain lacking all arsenate reductases were somewhat different and included lower induction of genes involved in metal homeostasis and Fe-S cluster biogenesis, suggesting that these two processes are targeted by arsenite in the wild type strain. Finally, analysis of the arsR mutant strain revealed that ArsR seems to only control 5 genes in the genome. Furthermore, the arsR mutant strain exhibited hypersentivity to nickel, copper and cadmium and this phenotype was suppressed by mutation in arsB but not in arsC gene suggesting that overexpression of arsB is detrimental in the presence of these metals in the media.

  12. Ratio-of-Mediator-Probability Weighting for Causal Mediation Analysis in the Presence of Treatment-by-Mediator Interaction

    Science.gov (United States)

    Hong, Guanglei; Deutsch, Jonah; Hill, Heather D.

    2015-01-01

    Conventional methods for mediation analysis generate biased results when the mediator--outcome relationship depends on the treatment condition. This article shows how the ratio-of-mediator-probability weighting (RMPW) method can be used to decompose total effects into natural direct and indirect effects in the presence of treatment-by-mediator…

  13. Mediation Works: An Action Research Study Evaluating the Peer Mediation Program from the Eyes of Mediators and Faculty

    Science.gov (United States)

    Cook, Jacqueline Yvonne; Boes, Susan R.

    2013-01-01

    A literature review was conducted to understand how mediators and faculty view a Peer Mediation Program (PMP). The review identified four subgroups: mediators, teachers, administrators, and school counselors as well as their views on the success or lack of success of PMPs. The research also reflects how to best engage stakeholders in the mediation…

  14. Expression of arsenic resistance genes in the obligate anaerobe Bacteroides vulgatus ATCC 8482, a gut microbiome bacterium.

    Science.gov (United States)

    Li, Jiaojiao; Mandal, Goutam; Rosen, Barry P

    2016-06-01

    The response of the obligate anaerobe Bacteroides vulgatus ATCC 8482, a common human gut microbiota, to arsenic was determined. B. vulgatus ATCC 8482 is highly resistant to pentavalent As(V) and methylarsenate (MAs(V)). It is somewhat more sensitive to trivalent inorganic As(III) but 100-fold more sensitive to methylarsenite (MAs(III)) than to As(III). B. vulgatus ATCC 8482 has eight continuous genes in its genome that we demonstrate form an arsenical-inducible transcriptional unit. The first gene of this ars operon, arsR, encodes a putative ArsR As(III)-responsive transcriptional repressor. The next three genes encode proteins of unknown function. The remaining genes, arsDABC, have well-characterized roles in detoxification of inorganic arsenic, but there are no known genes for MAs(III) resistance. Expression of each gene after exposure to trivalent and pentavalent inorganic and methylarsenicals was analyzed. MAs(III) was the most effective inducer. The arsD gene was the most highly expressed of the ars operon genes. These results demonstrate that this anaerobic microbiome bacterium has arsenic-responsive genes that confer resistance to inorganic arsenic and may be responsible for the organism's ability to maintain its prevalence in the gut following dietary exposure to inorganic arsenic. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Parameter space of general gauge mediation

    International Nuclear Information System (INIS)

    Rajaraman, Arvind; Shirman, Yuri; Smidt, Joseph; Yu, Felix

    2009-01-01

    We study a subspace of General Gauge Mediation (GGM) models which generalize models of gauge mediation. We find superpartner spectra that are markedly different from those of typical gauge and gaugino mediation scenarios. While typical gauge mediation predictions of either a neutralino or stau next-to-lightest supersymmetric particle (NLSP) are easily reproducible with the GGM parameters, chargino and sneutrino NLSPs are generic for many reasonable choices of GGM parameters.

  16. Mediation Analysis in Psychosomatic Medicine Research

    OpenAIRE

    Lockhart, Ginger; MacKinnon, David P.; Ohlrich, Vanessa

    2010-01-01

    This article presents an overview of statistical mediation analysis and its application to psychosomatic medicine research. The article begins with a description of the major approaches to mediation analysis and an evaluation of the strengths and limits of each. Emphasis is placed on longitudinal mediation models, and an application using latent growth modeling is presented. The article concludes with a description of recent developments in mediation analysis and suggestions for the use of me...

  17. Mediator oxidation systems in organic electrosynthesis

    International Nuclear Information System (INIS)

    Ogibin, Yurii N; Elinson, Michail N; Nikishin, Gennady I

    2009-01-01

    The data on the use of mediator oxidation systems activated by electric current (anodic or parallel anodic and cathodic) in organic electrosynthesis are considered and generalised. Electrochemical activation of these systems permits successful application of catalytic versions and easy scaling of mediator-promoted processes. Chemical and environmental advantages of electrochemical processes catalysed by mediator oxidation systems are demonstrated. Examples of the application of organic and inorganic mediators for the oxidation of various classes of organic compounds under conditions of electrolysis are given.

  18. LEGAL CULTURES AND MEDIATION. INTERACTIONS AND EVOLUTIONS

    Directory of Open Access Journals (Sweden)

    Claudiu Ramon D. BUTCULESCU

    2014-05-01

    Full Text Available Mediation, as an alternative dispute resolution method, is closely connected with the system of legal cultures. Mediation is an important link between legal culture and the judicial system. Mediation also acts as an interface between internal legal culture and external legal culture. This paper addresses the issues regarding the links and interactions between mediation and legal cultures, as well as the effects that arise from these interactions.

  19. Agrobacterium tumefaciens-Mediated Transformation

    DEFF Research Database (Denmark)

    Frandsen, Rasmus John Normand

    2015-01-01

    The use of Agrobacterium tumefaciens-mediated transformation for achieving genetic transformation of fungi has steadily increased over the last decade, and has proven to be almost universally applicable technique once suitable selection markers have been developed. In recent years the major...... technical advances has been made within the initial steps of the process, more specifically the efficient construction of plasmids for performing targeted genome modifications. This chapter provides a generic protocol for performing genetic transformation of ascomycetes via A. tumefaciens......-mediated transformation (AMT) and guidelines for optimizing the AMT process with new fungal species. The chapter also includes a highly efficient vector construction system based on Uracil Specific Excisions Reagent (USER) cloning and specific PCR generated building blocks, which can be combined ad hoc to create complex...

  20. Introduction: Mediating and Remediating Death

    DEFF Research Database (Denmark)

    Christensen, Dorthe Refslund; Sandvik, Kjetil

    2014-01-01

    In this second volume we explore how people, groups and institutions deal with death through processes of mediation (the presentation of something through media), remediation (the representation of one medium in another, see below) and mediatization (the process through which core elements...... of a social or cultural activity assume media form, see below). The volume presents a wide variety of ethnographies of death from Norway, Finland, Sweden, the US, Papua New Guinea, Bosnia and Hercegovina, Libya, Tibet, Uganda and Denmark as well as a number of online sites and social media material....... These are analyzed through a vast number of theoretical and analytical perspectives in order to investigate how very diverse practices surrounding death and dying - mourning and commemoration, ritualization, politicization, re-enactment, traditionalization, activism or documentarism: private or public, offline...

  1. Mediatization: a concept, multiple voices

    Directory of Open Access Journals (Sweden)

    Pedro Gilberto GOMES

    2016-12-01

    Full Text Available Mediatization has become increasingly a key concept, fundamental, essential to describe the present and the history of media and communicative change taking place. Thus, it became part of a whole, one can not see them as a separate sphere. In this perspective, the media coverage is used as a concept to describe the process of expansion of the different technical means and consider the interrelationships between the communicative change, means and sociocultural change. However, although many researchers use the concept of mediatization, each gives you the meaning that best suits your needs. Thus, the concept of media coverage is treated with multiple voices. This paper discusses this problem and present a preliminary pre-position on the matter.

  2. 41 CFR 101-8.717 - Mediation.

    Science.gov (United States)

    2010-07-01

    ... 41 Public Contracts and Property Management 2 2010-07-01 2010-07-01 true Mediation. 101-8.717... FINANCIAL ASSISTANCE 8.7-Discrimination Prohibited on the Basis of Age § 101-8.717 Mediation. (a) GSA promptly refers to the mediation agency designated by the Secretary, HHS, all sufficient complaints that...

  3. 34 CFR 303.419 - Mediation.

    Science.gov (United States)

    2010-07-01

    ... 34 Education 2 2010-07-01 2010-07-01 false Mediation. 303.419 Section 303.419 Education... DISABILITIES Procedural Safeguards Mediation and Due Process Procedures for Parents and Children § 303.419 Mediation. (a) General. Each State shall ensure that procedures are established and implemented to allow...

  4. 45 CFR 617.10 - Mediation.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 3 2010-10-01 2010-10-01 false Mediation. 617.10 Section 617.10 Public Welfare... OF AGE IN PROGRAMS OR ACTIVITIES RECEIVING FEDERAL FINANCIAL ASSISTANCE FROM NSF § 617.10 Mediation. (a) NSF will refer to the Federal Mediation and Conciliation Service all complaints that fall within...

  5. 34 CFR 300.506 - Mediation.

    Science.gov (United States)

    2010-07-01

    ... 34 Education 2 2010-07-01 2010-07-01 false Mediation. 300.506 Section 300.506 Education... DISABILITIES Procedural Safeguards Due Process Procedures for Parents and Children § 300.506 Mediation. (a... due process complaint, to resolve disputes through a mediation process. (b) Requirements. The...

  6. Single-Level and Multilevel Mediation Analysis

    Science.gov (United States)

    Tofighi, Davood; Thoemmes, Felix

    2014-01-01

    Mediation analysis is a statistical approach used to examine how the effect of an independent variable on an outcome is transmitted through an intervening variable (mediator). In this article, we provide a gentle introduction to single-level and multilevel mediation analyses. Using single-level data, we demonstrate an application of structural…

  7. 7 CFR 900.109 - Mediation agreement.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Mediation agreement. 900.109 Section 900.109 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing... Mediation agreement. An agreement arrived at by mediation shall not become effective until approved by the...

  8. The Merits of Using Longitudinal Mediation

    Science.gov (United States)

    Jose, Paul E.

    2016-01-01

    Many of the mediation analyses reported in the literature are based on concurrent or single-occasion data sets. The 2 overarching themes of the present article are: Results of concurrent mediations are inherently ambiguous, and researchers would be wise to conduct mediations on longitudinal data sets instead. An example included here demonstrates…

  9. 13 CFR 117.12 - Mediation.

    Science.gov (United States)

    2010-01-01

    ... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Mediation. 117.12 Section 117.12... Mediation. (a) SBA shall, after ensuring that the complaint falls within the coverage of this Act and all... clearly within an exception, promptly refer the complaint to the Federal Mediation and Conciliation...

  10. 7 CFR 400.94 - Mediation.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 6 2010-01-01 2010-01-01 false Mediation. 400.94 Section 400.94 Agriculture... AGRICULTURE GENERAL ADMINISTRATIVE REGULATIONS Appeal Procedure § 400.94 Mediation. For adverse decisions only: (a) Appellants have the right to seek mediation or other forms of alternative dispute resolution in...

  11. Causal Mediation Analysis: Warning! Assumptions Ahead

    Science.gov (United States)

    Keele, Luke

    2015-01-01

    In policy evaluations, interest may focus on why a particular treatment works. One tool for understanding why treatments work is causal mediation analysis. In this essay, I focus on the assumptions needed to estimate mediation effects. I show that there is no "gold standard" method for the identification of causal mediation effects. In…

  12. Methods for Mediation Analysis with Missing Data

    Science.gov (United States)

    Zhang, Zhiyong; Wang, Lijuan

    2013-01-01

    Despite wide applications of both mediation models and missing data techniques, formal discussion of mediation analysis with missing data is still rare. We introduce and compare four approaches to dealing with missing data in mediation analysis including list wise deletion, pairwise deletion, multiple imputation (MI), and a two-stage maximum…

  13. Axino dark matter in mirage mediation

    International Nuclear Information System (INIS)

    Nakamura, Shuntaro; Okumura, Ken-ichi; Yamaguchi, Masahiro

    2009-01-01

    The mirage mediation of supersymmetry breaking is a phenomenologically quite interesting possibility, however, it suffers from two major problems: the moduli-induced gravitino problem and the μ-Bμ problem. In this paper, we propose that the axionic extension of mirage mediation, axionic mirage mediation can solve both problems simultaneously. We address the cosmological consequences of the scenario extensively.

  14. Mediation in complex multi-party disputes

    NARCIS (Netherlands)

    Kamminga, Y.P.; Blohorn-Brenneur, B.

    2013-01-01

    Mediation is on the rise but it is lagging behind in certain fields such as in the resolution of complex disputes. This article addresses how biases in the decision-making process for selecting either mediation or litigation surrounding dispute resolution works in the disadvantage of mediation. It

  15. Direct mediation, duality and unification

    International Nuclear Information System (INIS)

    Abel, Steven; Khoze, Valentin V.

    2008-01-01

    It is well-known that in scenarios with direct gauge mediation of supersymmetry breaking the messenger fields significantly affect the running of Standard Model couplings and introduce Landau poles which are difficult to avoid. Among other things, this appears to remove any possibility of a meaningful unification prediction and is often viewed as a strong argument against direct mediation. We propose two ways that Seiberg duality can circumvent this problem. In the first, which we call 'deflected-unification', the SUSY-breaking hidden sector is a magnetic theory which undergoes a Seiberg duality to an electric phase. Importantly, the electric version has fewer fundamental degrees of freedom coupled to the MSSM compared to the magnetic formulation. This changes the β-functions of the MSSM gauge couplings so as to push their Landau poles above the unification scale. We show that this scenario is realised for recently suggested models of gauge mediation based on a metastable SCQD-type hidden sector directly coupled to MSSM. The second possibility for avoiding Landau poles, which we call 'dual-unification', begins with the observation that, if the mediating fields fall into complete SU(5) multiplets, then the MSSM+messengers exhibits a fake unification at unphysical values of the gauge couplings. We show that, in known examples of electric/magnetic duals, such a fake unification in the magnetic theory reflects a real unification in the electric theory. We therefore propose that the Standard Model could itself be a magnetic dual of some unknown electric theory in which the true unification takes place. This scenario maintains the unification prediction (and unification scale) even in the presence of Landau poles in the magnetic theory below the GUT scale. We further note that this dual realization of grand unification can explain why Nature appears to unify, but the proton does not decay.

  16. The pathway by which the yeast protein kinase Snf1p controls acquisition of sodium tolerance is different from that mediating glucose regulation.

    Science.gov (United States)

    Ye, Tian; Elbing, Karin; Hohmann, Stefan

    2008-09-01

    It recently became apparent that the highly conserved Snf1p protein kinase plays roles in controlling different cellular processes in the yeast Saccharomyces cerevisiae, in addition to its well-known function in glucose repression/derepression. We have previously reported that Snf1p together with Gis4p controls ion homeostasis by regulating expression of ENA1, which encodes the Ena1p Na(+) extrusion system. In this study we found that Snf1p is rapidly phosphorylated when cells are exposed to NaCl and this phosphorylation is required for the role of Snf1p in Na(+) tolerance. In contrast to activation by low glucose levels, the salt-induced phosphorylation of Snf1p promoted neither phosphorylation nor nuclear export of the Mig1p repressor. The mechanism that prevents Mig1p phosphorylation by active Snf1p under salt stress does not involve either hexokinase PII or the Gis4p regulator. Instead, Snf1p may mediate upregulation of ENA1 expression via the repressor Nrg1p. Activation of Snf1p in response to glucose depletion requires any of the three upstream protein kinases Sak1p, Tos3p and Elm1p, with Sak1p playing the most prominent role. The same upstream kinases were required for salt-induced Snf1p phosphorylation, and also under these conditions Sak1p played the most prominent role. Unexpectedly, however, it appears that Elm1p plays a dual role in acquisition of salt tolerance by activating Snf1p and in a presently unknown parallel pathway. Together, these results indicate that under salt stress Snf1p takes part in a different pathway from that during glucose depletion and this role is performed together as well as in parallel with its upstream kinase Elm1p. Snf1p appears to be part of a wider functional network than previously anticipated and the full complexity of this network remains to be elucidated.

  17. Minimal ancilla mediated quantum computation

    International Nuclear Information System (INIS)

    Proctor, Timothy J.; Kendon, Viv

    2014-01-01

    Schemes of universal quantum computation in which the interactions between the computational elements, in a computational register, are mediated by some ancillary system are of interest due to their relevance to the physical implementation of a quantum computer. Furthermore, reducing the level of control required over both the ancillary and register systems has the potential to simplify any experimental implementation. In this paper we consider how to minimise the control needed to implement universal quantum computation in an ancilla-mediated fashion. Considering computational schemes which require no measurements and hence evolve by unitary dynamics for the global system, we show that when employing an ancilla qubit there are certain fixed-time ancilla-register interactions which, along with ancilla initialisation in the computational basis, are universal for quantum computation with no additional control of either the ancilla or the register. We develop two distinct models based on locally inequivalent interactions and we then discuss the relationship between these unitary models and the measurement-based ancilla-mediated models known as ancilla-driven quantum computation. (orig.)

  18. Male-mediated developmental toxicity

    Directory of Open Access Journals (Sweden)

    Diana Anderson

    2014-02-01

    Full Text Available Male-mediated developmental toxicity has been of concern for many years. The public became aware of male-mediated developmental toxicity in the early 1990s when it was reported that men working at Sellafield might be causing leukemia in their children. Human and animal studies have contributed to our current understanding of male-mediated effects. Animal studies in the 1980s and 1990s suggested that genetic damage after radiation and chemical exposure might be transmitted to offspring. With the increasing understanding that there is histone retention and modification, protamine incorporation into the chromatin and DNA methylation in mature sperm and that spermatozoal RNA transcripts can play important roles in the epigenetic state of sperm, heritable studies began to be viewed differently. Recent reports using molecular approaches have demonstrated that DNA damage can be transmitted to babies from smoking fathers, and expanded simple tandem repeats minisatellite mutations were found in the germline of fathers who were exposed to radiation from the Chernobyl nuclear power plant disaster. In epidemiological studies, it is possible to clarify whether damage is transmitted to the sons after exposure of the fathers. Paternally transmitted damage to the offspring is now recognized as a complex issue with genetic as well as epigenetic components.

  19. Substrate mediated enzyme prodrug therapy.

    Directory of Open Access Journals (Sweden)

    Betina Fejerskov

    Full Text Available In this report, we detail Substrate Mediated Enzyme Prodrug Therapy (SMEPT as a novel approach in drug delivery which relies on enzyme-functionalized cell culture substrates to achieve a localized conversion of benign prodrug(s into active therapeutics with subsequent delivery to adhering cells or adjacent tissues. For proof-of-concept SMEPT, we use surface adhered micro-structured physical hydrogels based on poly(vinyl alcohol, β-glucuronidase enzyme and glucuronide prodrugs. We demonstrate enzymatic activity mediated by the assembled hydrogel samples and illustrate arms of control over rate of release of model fluorescent cargo. SMEPT was not impaired by adhering cells and afforded facile time - and dose - dependent uptake of the in situ generated fluorescent cargo by hepatic cells, HepG2. With the use of a glucuronide derivative of an anticancer drug, SN-38, SMEPT afforded a decrease in cell viability to a level similar to that achieved using parent drug. Finally, dose response was achieved using SMEPT and administration of judiciously chosen concentration of SN-38 glucuronide prodrug thus revealing external control over drug delivery using drug eluting surface. We believe that this highly adaptable concept will find use in diverse biomedical applications, specifically surface mediated drug delivery and tissue engineering.

  20. Mediators and Metaphorical Analysis: A Phenomenological Study of Florida Family Court Mediators

    Science.gov (United States)

    Storrow, Rebecca A.

    2012-01-01

    Florida family court mediation programs have typically been assessed with quantitative analysis. To understand the complexity of the experience of being a family mediator, it was necessary to explore how mediators practiced through qualitative research. Metaphors have been considered to be representations of mediators' mental models regarding…

  1. Mediation – Mandatory Information and Facultative Applicability

    Directory of Open Access Journals (Sweden)

    Monica Pocora

    2015-12-01

    Full Text Available Considering that mediation is a facilitating way to access the alternative solving of litigations in conciliatory terms, the study is encouraging using the mediation and providing a balanced relationship between mediation and judiciary procedures. As an aftermath of summary definition, we can say that role of mediation is to overcome the communicative barriers in order to solve the conflict and save the fact situation on both parts. The study aims at analyzing objectively all consequences of both solving ways of litigations: traditional one, through the law court and mediation, with the advantages derived from them (celerity vs. time consuming, expensive judiciary proceedings vs. low costs, etc.

  2. Transcriptomic profiling-based mutant screen reveals three new transcription factors mediating menadione resistance in Neurospora crassa.

    Science.gov (United States)

    Zhu, Jufen; Yu, Xinxu; Xie, Baogui; Gu, Xiaokui; Zhang, Zhenying; Li, Shaojie

    2013-06-01

    To gain insight into the regulatory mechanisms of oxidative stress responses in filamentous fungi, the genome-wide transcriptional response of Neurospora crassa to menadione was analysed by digital gene expression (DGE) profiling, which identified 779 upregulated genes and 576 downregulated genes. Knockout mutants affecting 130 highly-upregulated genes were tested for menadione sensitivity, which revealed that loss of the transcription factor siderophore regulation (SRE) (a transcriptional repressor for siderophore biosynthesis), catatase-3, cytochrome c peroxidase or superoxide dismutase 1 copper chaperone causes hypersensitivity to menadione. Deletion of sre dramatically increased transcription of the siderophore biosynthesis gene ono and the siderophore iron transporter gene sit during menadione stress, suggesting that SRE is required for repression of iron uptake under oxidative stress conditions. Contrary to its phenotype, the sre deletion mutant showed higher transcriptional levels of genes encoding reactive oxygen species (ROS) scavengers than wild type during menadione stress, which implies that the mutant suffers a higher level of oxidative stress than wild type. Uncontrolled iron uptake in the sre mutant might exacerbate cellular oxidative stress. This is the first report of a negative regulator of iron assimilation participating in the fungal oxidative stress response. In addition to SRE, eight other transcription factor genes were also menadione-responsive but their single gene knockout mutants showed wild-type menadione sensitivity. Two of them, named as mit-2 (menadione induced transcription factor-2) and mit-4 (menadione induced transcription factor-4), were selected for double mutant analysis. The double mutant was hypersensitive to menadione. Similarly, the double mutation of mit-2 and sre also had additive effects on menadione sensitivity, suggesting multiple transcription factors mediate oxidative stress resistance in an additive manner

  3. DREAM mediates cAMP-dependent, Ca2+-induced stimulation of GFAP gene expression and regulates cortical astrogliogenesis.

    Science.gov (United States)

    Cebolla, Beatriz; Fernández-Pérez, Antonio; Perea, Gertrudis; Araque, Alfonso; Vallejo, Mario

    2008-06-25

    In the developing mouse brain, once the generation of neurons is mostly completed during the prenatal period, precisely coordinated signals act on competent neural precursors to direct their differentiation into astrocytes, which occurs mostly after birth. Among these signals, those provided by neurotrophic cytokines and bone morphogenetic proteins appear to have a key role in triggering the neurogenic to gliogenic switch and in regulating astrocyte numbers. In addition, we have reported previously that the neurotrophic peptide pituitary adenylate cyclase-activating polypeptide (PACAP) is able to promote astrocyte differentiation of cortical precursors via activation of a cAMP-dependent pathway. Signals acting on progenitor cells of the developing cortex to generate astrocytes activate glial fibrillary acidic protein (GFAP) gene expression, but the transcriptional mechanisms that regulate this activation are unclear. Here, we identify the previously known transcriptional repressor downstream regulatory element antagonist modulator (DREAM) as an activator of GFAP gene expression. We found that DREAM occupies specific sites on the GFAP promoter before and after differentiation is initiated by exposure of cortical progenitor cells to PACAP. PACAP raises intracellular calcium concentration via a mechanism that requires cAMP, and DREAM-mediated transactivation of the GFAP gene requires the integrity of calcium-binding domains. Cortical progenitor cells from dream(-/-) mice fail to express GFAP in response to PACAP. Moreover, the neonatal cortex of dream(-/-) mice exhibits a reduced number of astrocytes and increased number of neurons. These results identify the PACAP-cAMP-Ca(2+)-DREAM cascade as a new pathway to activate GFAP gene expression during astrocyte differentiation.

  4. The transcription factor DREAM represses A20 and mediates inflammation

    OpenAIRE

    Tiruppathi, Chinnaswamy; Soni, Dheeraj; Wang, Dong-Mei; Xue, Jiaping; Singh, Vandana; Thippegowda, Prabhakar B.; Cheppudira, Bopaiah P.; Mishra, Rakesh K.; DebRoy, Auditi; Qian, Zhijian; Bachmaier, Kurt; Zhao, Youyang; Christman, John W.; Vogel, Stephen M.; Ma, Averil

    2014-01-01

    Here we show that the transcription-repressor DREAM binds to the A20 promoter to repress the expression of A20, the deubiquitinase suppressing inflammatory NF-κB signaling. DREAM-deficient (Dream−/− ) mice displayed persistent and unchecked A20 expression in response to endotoxin. DREAM functioned by transcriptionally repressing A20 through binding to downstream regulatory elements (DREs). In contrast, USF1 binding to the DRE-associated E-box domain activated A20 expression in response to inf...

  5. Immunoglobulin E-Mediated Autoimmunity

    Directory of Open Access Journals (Sweden)

    Marcus Maurer

    2018-04-01

    Full Text Available The study of autoimmunity mediated by immunoglobulin E (IgE autoantibodies, which may be termed autoallergy, is in its infancy. It is now recognized that systemic lupus erythematosus, bullous pemphigoid (BP, and chronic urticaria, both spontaneous and inducible, are most likely to be mediated, at least in part, by IgE autoantibodies. The situation in other conditions, such as autoimmune uveitis, rheumatoid arthritis, hyperthyroid Graves’ disease, autoimmune pancreatitis, and even asthma, is far less clear but evidence for autoallergy is accumulating. To be certain of an autoallergic mechanism, it is necessary to identify both IgE autoantibodies and their targets as has been done with the transmembrane protein BP180 and the intracellular protein BP230 in BP and IL-24 in chronic spontaneous urticaria. Also, IgE-targeted therapies, such as anti-IgE, must have been shown to be of benefit to patients as has been done with both of these conditions. This comprehensive review of the literature on IgE-mediated autoallergy focuses on three related questions. What do we know about the prevalence of IgE autoantibodies and their targets in different diseases? What do we know about the relevance of IgE autoantibodies in different diseases? What do we know about the cellular and molecular effects of IgE autoantibodies? In addition to providing answers to these questions, based on a broad review of the literature, we outline the current gaps of knowledge in our understanding of IgE autoantibodies and describe approaches to address them.

  6. Hydrological models are mediating models

    Science.gov (United States)

    Babel, L. V.; Karssenberg, D.

    2013-08-01

    Despite the increasing role of models in hydrological research and decision-making processes, only few accounts of the nature and function of models exist in hydrology. Earlier considerations have traditionally been conducted while making a clear distinction between physically-based and conceptual models. A new philosophical account, primarily based on the fields of physics and economics, transcends classes of models and scientific disciplines by considering models as "mediators" between theory and observations. The core of this approach lies in identifying models as (1) being only partially dependent on theory and observations, (2) integrating non-deductive elements in their construction, and (3) carrying the role of instruments of scientific enquiry about both theory and the world. The applicability of this approach to hydrology is evaluated in the present article. Three widely used hydrological models, each showing a different degree of apparent physicality, are confronted to the main characteristics of the "mediating models" concept. We argue that irrespective of their kind, hydrological models depend on both theory and observations, rather than merely on one of these two domains. Their construction is additionally involving a large number of miscellaneous, external ingredients, such as past experiences, model objectives, knowledge and preferences of the modeller, as well as hardware and software resources. We show that hydrological models convey the role of instruments in scientific practice by mediating between theory and the world. It results from these considerations that the traditional distinction between physically-based and conceptual models is necessarily too simplistic and refers at best to the stage at which theory and observations are steering model construction. The large variety of ingredients involved in model construction would deserve closer attention, for being rarely explicitly presented in peer-reviewed literature. We believe that devoting

  7. Mediated electrochemical hazardous waste destruction

    International Nuclear Information System (INIS)

    Hickman, R.G.; Farmer, J.C.; Wang, F.T.

    1992-03-01

    There are few permitted processes for mixed waste (radioactive plus chemically hazardous) treatment. We are developing an electrochemical process, based upon mediated electrochemical oxidation (MEO), that converts toxic organic components of mixed waste to water, carbon dioxide, and chloride or chloride precipitates. Aggressive oxidizer ions such as Ag 2+ , Co 3+ , or Fe 3+ are produced at an anode. These can attack organic molecules directly, and may also produce hydroxyl free radicals that promote destruction. Solid and liquid radioactive waste streams containing only inorganic radionuclide forms may be treated with existing technology and prepared for final disposal. The coulombic efficiency of the process has been determined, as well as the destruction efficiency for ethylene glycol, a surrogate waste. In addition, hazardous organic materials are becoming very expensive to dispose of and when they are combined with transuranic radioactive elements no processes are presently permitted. Mediated electrochemical oxidation is an ambient- temperature aqueous-phase process that can be used to oxidize organic components of mixed wastes. Problems associated with incineration, such as high-temperature volatilization of radionuclides, are avoided. Historically, Ag(II) has been used as a mediator in this process. Fe(III) and Co(III) are attractive alternatives to Ag(II) since they form soluble chlorides during the destruction of chlorinated solvents. Furthermore, silver itself is toxic heavy metal. Quantitative data have been obtained for the complete oxidation of ethylene glycol by Fe(III) and Co(III). Though ethylene glycol is a nonhalogenated organic, these data have enabled us to make direct comparisons of activities of Fe(III) and Co(III) with Ag(II). Very good quantitative data for the oxidation of ethylene glycol by Ag(II) had already been collected

  8. Mediation for resolving family disputes

    Directory of Open Access Journals (Sweden)

    Kamenecka-Usova M.

    2016-01-01

    Full Text Available Nowadays the understanding of the institute of marriage and its importance in the society has changed. Marriage is no longer assumed to be a commitment for a lifetime. As the principle of equality has replaced hierarchy as the guiding principle of family law it gave more grounds for family disputes and it became socially acceptable to leave marriages that are intolerable or merely unfulfilling. The aim of this article is to suggest an alternative dispute resolution method-mediation as a worthy option for resolving family conflicts.

  9. Trilinear-augmented gaugino mediation

    Energy Technology Data Exchange (ETDEWEB)

    Heisig, Jan [Institute for Theoretical Particle Physics and Cosmology, RWTH Aachen University,52056 Aachen (Germany); Kersten, Jörn [Department of Physics and Technology, University of Bergen,5020 Bergen (Norway); Murphy, Nick [CP-Origins, University of Southern Denmark,5230 Odense M (Denmark); Strümke, Inga [Department of Physics and Technology, University of Bergen,5020 Bergen (Norway)

    2017-05-02

    We consider a gaugino-mediated supersymmetry breaking scenario where in addition to the gauginos the Higgs fields couple directly to the field that breaks supersymmetry. This yields non-vanishing trilinear scalar couplings in general, which can lead to large mixing in the stop sector providing a sufficiently large Higgs mass. Using the most recent release of FeynHiggs, we show the implications on the parameter space. Assuming a gravitino LSP, we find allowed points with a neutralino, sneutrino or stau NLSP. We test these points against the results of Run 1 of the LHC, considering in particular searches for heavy stable charged particles.

  10. Trilinear-augmented gaugino mediation

    International Nuclear Information System (INIS)

    Heisig, Jan; Kersten, Jörn; Murphy, Nick; Strümke, Inga

    2017-01-01

    We consider a gaugino-mediated supersymmetry breaking scenario where in addition to the gauginos the Higgs fields couple directly to the field that breaks supersymmetry. This yields non-vanishing trilinear scalar couplings in general, which can lead to large mixing in the stop sector providing a sufficiently large Higgs mass. Using the most recent release of FeynHiggs, we show the implications on the parameter space. Assuming a gravitino LSP, we find allowed points with a neutralino, sneutrino or stau NLSP. We test these points against the results of Run 1 of the LHC, considering in particular searches for heavy stable charged particles.

  11. Ideal crop plant architecture is mediated by tassels replace upper ears1, a BTB/POZ ankyrin repeat gene directly targeted by TEOSINTE BRANCHED1.

    Science.gov (United States)

    Dong, Zhaobin; Li, Wei; Unger-Wallace, Erica; Yang, Jinliang; Vollbrecht, Erik; Chuck, George

    2017-10-10

    Axillary branch suppression is a favorable trait bred into many domesticated crop plants including maize compared with its highly branched wild ancestor teosinte. Branch suppression in maize was achieved through selection of a gain of function allele of the teosinte branched1 (tb1) transcription factor that acts as a repressor of axillary bud growth. Previous work indicated that other loci may function epistatically with tb1 and may be responsible for some of its phenotypic effects. Here, we show that tb1 mediates axillary branch suppression through direct activation of the tassels replace upper ears1 ( tru1 ) gene that encodes an ankyrin repeat domain protein containing a BTB/POZ motif necessary for protein-protein interactions. The expression of TRU1 and TB1 overlap in axillary buds, and TB1 binds to two locations in the tru1 gene as shown by chromatin immunoprecipitation and gel shifts. In addition, nucleotide diversity surveys indicate that tru1 , like tb1 , was a target of selection. In modern maize, TRU1 is highly expressed in the leaf trace vasculature of axillary internodes, while in teosinte, this expression is highly reduced or absent. This increase in TRU1 expression levels in modern maize is supported by comparisons of relative protein levels with teosinte as well as by quantitative measurements of mRNA levels. Hence, a major innovation in creating ideal maize plant architecture originated from ectopic overexpression of tru1 in axillary branches, a critical step in mediating the effects of domestication by tb1.

  12. Mediation designs for tobacco prevention research

    Science.gov (United States)

    MacKinnon, David P.; Taborga, Marcia P.; Morgan-Lopez, Antonio A.

    2010-01-01

    This paper describes research designs and statistical analyses to investigate how tobacco prevention programs achieve their effects on tobacco use. A theoretical approach to program development and evaluation useful for any prevention program guides the analysis. The theoretical approach focuses on action theory for how the program affects mediating variables and on conceptual theory for how mediating variables are related to tobacco use. Information on the mediating mechanisms by which tobacco prevention programs achieve effects is useful for the development of efficient programs and provides a test of the theoretical basis of prevention efforts. Examples of these potential mediating mechanisms are described including mediated effects through attitudes, social norms, beliefs about positive consequences, and accessibility to tobacco. Prior research provides evidence that changes in social norms are a critical mediating mechanism for successful tobacco prevention. Analysis of mediating variables in single group designs with multiple mediators are described as well as multiple group randomized designs which are the most likely to accurately uncover important mediating mechanisms. More complicated dismantling and constructive designs are described and illustrated based on current findings from tobacco research. Mediation analysis for categorical outcomes and more complicated statistical methods are outlined. PMID:12324176

  13. The Mediator complex and transcription regulation

    Science.gov (United States)

    Poss, Zachary C.; Ebmeier, Christopher C.

    2013-01-01

    The Mediator complex is a multi-subunit assembly that appears to be required for regulating expression of most RNA polymerase II (pol II) transcripts, which include protein-coding and most non-coding RNA genes. Mediator and pol II function within the pre-initiation complex (PIC), which consists of Mediator, pol II, TFIIA, TFIIB, TFIID, TFIIE, TFIIF and TFIIH and is approximately 4.0 MDa in size. Mediator serves as a central scaffold within the PIC and helps regulate pol II activity in ways that remain poorly understood. Mediator is also generally targeted by sequence-specific, DNA-binding transcription factors (TFs) that work to control gene expression programs in response to developmental or environmental cues. At a basic level, Mediator functions by relaying signals from TFs directly to the pol II enzyme, thereby facilitating TF-dependent regulation of gene expression. Thus, Mediator is essential for converting biological inputs (communicated by TFs) to physiological responses (via changes in gene expression). In this review, we summarize an expansive body of research on the Mediator complex, with an emphasis on yeast and mammalian complexes. We focus on the basics that underlie Mediator function, such as its structure and subunit composition, and describe its broad regulatory influence on gene expression, ranging from chromatin architecture to transcription initiation and elongation, to mRNA processing. We also describe factors that influence Mediator structure and activity, including TFs, non-coding RNAs and the CDK8 module. PMID:24088064

  14. Transporter-mediated biofuel secretion.

    Science.gov (United States)

    Doshi, Rupak; Nguyen, Tuan; Chang, Geoffrey

    2013-05-07

    Engineering microorganisms to produce biofuels is currently among the most promising strategies in renewable energy. However, harvesting these organisms for extracting biofuels is energy- and cost-intensive, limiting the commercial feasibility of large-scale production. Here, we demonstrate the use of a class of transport proteins of pharmacological interest to circumvent the need to harvest biomass during biofuel production. We show that membrane-embedded transporters, better known to efflux lipids and drugs, can be used to mediate the secretion of intracellularly synthesized model isoprenoid biofuel compounds to the extracellular milieu. Transporter-mediated biofuel secretion sustainably maintained an approximate three- to fivefold boost in biofuel production in our Escherichia coli test system. Because the transporters used in this study belong to the ubiquitous ATP-binding cassette protein family, we propose their use as "plug-and-play" biofuel-secreting systems in a variety of bacteria, cyanobacteria, diatoms, yeast, and algae used for biofuel production. This investigation showcases the potential of expressing desired membrane transport proteins in cell factories to achieve the export or import of substances of economic, environmental, or therapeutic importance.

  15. Multifunctional Curcumin Mediate Multitherapeutic Effects.

    Science.gov (United States)

    Shehzad, Adeeb; Qureshi, Munibah; Anwar, Muhammad Nabeel; Lee, Young Sup

    2017-09-01

    Inflammation can promote the development of arthritis, obesity, cardiovascular, type II diabetes, pancreatitis, metabolic and neurodegenerative diseases, and certain types of cancer. Compounds isolated from plants have been practiced since ancient times for curing various ailments including inflammatory disorders and to support normal physiological functions. Curcumin (diferuloylmethane) is a yellow coloring agent, extracted from turmeric that has been used for the prevention and treatment of various inflammatory diseases. Numerous studies have shown that curcumin modulate multiple molecular targets and can be translated to the clinics for multiple therapeutic processes. There is compelling evidence that curcumin can block cell proliferation, invasion, and angiogenesis as well as reduced the prolonged survival of cancer cells. Curcumin mediates anti-inflammatory effect through downregulation of inflammatory cytokines, transcription factors, protein kinases, and enzymes that promote inflammation and development of chronic diseases. In addition, curcumin induces apoptosis through mitochondrial and receptor-mediated pathways by activating caspase cascades. Curcumin is a safe and nontoxic drug that has been reported to be well tolerated. Available clinical trials support the potential role of curcumin for treatment of various inflammatory disorders. However, curcumin's efficacy is hindered by poor absorption and low bioavailability, which limit its translation into clinics. This review outlines the potential pharmacological and clinical role of curcumin, which provide a gateway for the beneficial role of plant isolated compounds in treatment of various inflammatory diseases and cancer. © 2017 Institute of Food Technologists®.

  16. Desperately Trying to Mediate Immediacy

    Directory of Open Access Journals (Sweden)

    Andreas Oliver Schellewald

    2018-01-01

    Full Text Available Evermore aspects of contemporary cultures, societies and human life appear to be changed through processes of digitization and mediatization. A great body of work is touching on these processes of change. However, not many discuss aspects of leisure and aesthetics. And if they do so, seldom regarding bodily and worldly aspects. This paper thus seeks to discuss such changes alongside the phenomenon of esports. More precisely, the paper situates the aesthetic dimension and practices of watching and doing esports in contemporary cultures and societies, focusing on lived experiences (ästhetisches Erleben in digital and mediated contexts. The failing attempt to understand, the attempt to re-present and Gelassenheit (composure or serenity are introduced as modes of coping with immediate aesthetic experiences. Here, especially the constitutive transition from a physical to a meta-physical dimension of reality will be grasped on. By that, ongoing philosophical debates about the constitution of reality and being can be supported in their progress.

  17. Direct detection with dark mediators

    Energy Technology Data Exchange (ETDEWEB)

    Curtin, David; Surujon, Ze' ev [C. N. Yang Institute for Theoretical Physics, Stony Brook University, Stony Brook, NY 11794 (United States); Tsai, Yuhsin [Physics Department, University of California Davis, Davis, CA 95616 (United States)

    2014-11-10

    We introduce dark mediator Dark Matter (dmDM) where the dark and visible sectors are connected by at least one light mediator ϕ carrying the same dark charge that stabilizes DM. ϕ is coupled to the Standard Model via an operator q{sup ¯}qϕϕ{sup ⁎}/Λ, and to dark matter via a Yukawa coupling y{sub χ}χ{sup c¯}χϕ. Direct detection is realized as the 2→3 process χN→χ{sup ¯}Nϕ at tree-level for m{sub ϕ}≲10 keV and small Yukawa coupling, or alternatively as a loop-induced 2→2 process χN→χN. We explore the direct-detection consequences of this scenario and find that a heavy O(100 GeV) dmDM candidate fakes different O(10 GeV) standard WIMPs in different experiments. Large portions of the dmDM parameter space are detectable above the irreducible neutrino background and not yet excluded by any bounds. Interestingly, for the m{sub ϕ} range leading to novel direct detection phenomenology, dmDM is also a form of Self-Interacting Dark Matter (SIDM), which resolves inconsistencies between dwarf galaxy observations and numerical simulations.

  18. Robust Mediation Analysis Based on Median Regression

    Science.gov (United States)

    Yuan, Ying; MacKinnon, David P.

    2014-01-01

    Mediation analysis has many applications in psychology and the social sciences. The most prevalent methods typically assume that the error distribution is normal and homoscedastic. However, this assumption may rarely be met in practice, which can affect the validity of the mediation analysis. To address this problem, we propose robust mediation analysis based on median regression. Our approach is robust to various departures from the assumption of homoscedasticity and normality, including heavy-tailed, skewed, contaminated, and heteroscedastic distributions. Simulation studies show that under these circumstances, the proposed method is more efficient and powerful than standard mediation analysis. We further extend the proposed robust method to multilevel mediation analysis, and demonstrate through simulation studies that the new approach outperforms the standard multilevel mediation analysis. We illustrate the proposed method using data from a program designed to increase reemployment and enhance mental health of job seekers. PMID:24079925

  19. Legal and Psychological Aspects of Mediation

    Directory of Open Access Journals (Sweden)

    Dobrokhotova E. N.

    2016-01-01

    Full Text Available The article focuses on gradual innovation of mediation into the practice of social conflict resolution in the light of legal and psychological means of mediation. While mediation is perceived as a conflictological concept and is more widely used in dispute settlement and resolution, a new interdisciplinary field of theoretical knowledge with its own conceptual framework as well as a new professional and practical field are beginning to form both in Russia and in other countries. As theoretical and practical aspects of innovation in mediation require consolidation not only for its national development but also for the guaranteed international cooperation, the article touches upon some of the particular theoretical issues of the topic in question: terminological consistency, consolidation of the system of mediation principles, the phenomenon of juridisation of mediation and its limits.

  20. Regulation of metabolism by the Mediator complex.

    Science.gov (United States)

    Youn, Dou Yeon; Xiaoli, Alus M; Pessin, Jeffrey E; Yang, Fajun

    2016-01-01

    The Mediator complex was originally discovered in yeast, but it is conserved in all eukaryotes. Its best-known function is to regulate RNA polymerase II-dependent gene transcription. Although the mechanisms by which the Mediator complex regulates transcription are often complicated by the context-dependent regulation, this transcription cofactor complex plays a pivotal role in numerous biological pathways. Biochemical, molecular, and physiological studies using cancer cell lines or model organisms have established the current paradigm of the Mediator functions. However, the physiological roles of the mammalian Mediator complex remain poorly defined, but have attracted a great interest in recent years. In this short review, we will summarize some of the reported functions of selective Mediator subunits in the regulation of metabolism. These intriguing findings suggest that the Mediator complex may be an important player in nutrient sensing and energy balance in mammals.

  1. DISTANCE LEARNERSÕ PERCEPTIONS OF COMPUTER MEDIATED COMMUNICATION

    OpenAIRE

    Mujgan Bozkaya; Irem Erdem Aydin

    2011-01-01

    In this study, perspectives of the first year students in the completely online Information Management Associate Degree Program at Anadolu University regarding computer as a communication medium were investigated. StudentsÕ perspectives on computer-mediated communications were analyzed in the light of three different views in the area of computer-mediated communications: The first view suggests that face-to-face settings are better communication environments compared to computer-mediated envi...

  2. Community Mediation. A Model for Romania

    Directory of Open Access Journals (Sweden)

    Christian Radu CHEREJI

    2014-02-01

    Full Text Available Community mediation takes all forms and shapes all over the world. In order to better understand its limitations in adapting to different contexts, we have compared the evolution of community mediation services in two totally different systems, USA and Sri Lanka. Based on this analysis and the results of a research conducted in Cluj-Napoca in the fall of 2013, we have recommended a community mediation model suitable for the current Romanian social, economic and cultural framework.

  3. Parental mediation and cyberbullying - a longitudinal study.

    Science.gov (United States)

    Chng, Grace S; Liau, Albert; Khoo, Angeline; Li, Dongdong

    2014-01-01

    Parents use active and restrictive mediation strategies to guide and regulate children's online participation and the online risks they encounter. However, changes in parental mediation do occur over time and the effectiveness of these strategies on cyberbullying demands for further empirical investigation. The current study addresses these issues with a sample of 1084 students (49% girls) in a longitudinal, three-wave design. Gender differences were tested via multi-group analyses. Longitudinal growth models showed that parental use of both active and restrictive mediation decreased over time. For both types of mediation, the mean rate of change had a significant effect on boys' engagement in cyberbullying, but not for girls. Initial levels of restrictive mediation, but not active mediation, were found to be significantly predictive of cyberbullying in both genders. Girls had higher initial levels of both parental mediation types in comparison to boys. The results reveal that the effectiveness of active and restrictive mediation in relation to students' cyberbullying differs and informs us on gender differences. The implications of these results for parental education in online mediation are discussed.

  4. Digital methods for mediated discourse analysis

    DEFF Research Database (Denmark)

    Kjær, Malene; Larsen, Malene Charlotte

    2015-01-01

    , restrictions or privately mediated settings. Having used mediated discourse analysis (Scollon 2002, Scollon & Scollon, 2004) as a framework in two different research projects, we show how the framework, in correlation with digital resources for data gathering, provides new understandings of 1) the daily......In this paper we discuss methodological strategies for collecting multimodal data using digital resources. The aim is to show how digital resources can provide ethnographic insights into mediated actions (Scollon, 2002) that can otherwise be difficult to observe or engage in, due to, for instance......) and online questionnaire data in order to capture mediated actions and discourses in practice....

  5. Transcription regulation by the Mediator complex.

    Science.gov (United States)

    Soutourina, Julie

    2018-04-01

    Alterations in the regulation of gene expression are frequently associated with developmental diseases or cancer. Transcription activation is a key phenomenon in the regulation of gene expression. In all eukaryotes, mediator of RNA polymerase II transcription (Mediator), a large complex with modular organization, is generally required for transcription by RNA polymerase II, and it regulates various steps of this process. The main function of Mediator is to transduce signals from the transcription activators bound to enhancer regions to the transcription machinery, which is assembled at promoters as the preinitiation complex (PIC) to control transcription initiation. Recent functional studies of Mediator with the use of structural biology approaches and functional genomics have revealed new insights into Mediator activity and its regulation during transcription initiation, including how Mediator is recruited to transcription regulatory regions and how it interacts and cooperates with PIC components to assist in PIC assembly. Novel roles of Mediator in the control of gene expression have also been revealed by showing its connection to the nuclear pore and linking Mediator to the regulation of gene positioning in the nuclear space. Clear links between Mediator subunits and disease have also encouraged studies to explore targeting of this complex as a potential therapeutic approach in cancer and fungal infections.

  6. Computer-Mediated Communication Systems

    Directory of Open Access Journals (Sweden)

    Bin Yu

    2011-10-01

    Full Text Available The essence of communication is to exchange and share information. Computers provide a new medium to human communication. CMC system, composed of human and computers, absorbs and then extends the advantages of all former formats of communication, embracing the instant interaction of oral communication, the abstract logics of printing dissemination, and the vivid images of movie and television. It also creates a series of new communication formats, such as Hyper Text, Multimedia etc. which are the information organizing methods, and cross-space message delivering patterns. Benefiting from the continuous development of technique and mechanism, the computer-mediated communication makes the dream of transmitting information cross space and time become true, which will definitely have a great impact on our social lives.

  7. Lepton-flavor violating mediators

    Energy Technology Data Exchange (ETDEWEB)

    Galon, Iftah; Kwa, Anna [Department of Physics & Astronomy, University of California,Irvine, CA 92697 (United States); Tanedo, Philip [Department of Physics & Astronomy, University of California,Riverside, CA 92521 (United States)

    2017-03-13

    We present a framework where dark matter interacts with the Standard Model through a light, spin-0 mediator that couples chirally to pairs of different-flavor leptons. This flavor violating final state weakens bounds on new physics coupled to leptons from terrestrial experiments and cosmic-ray measurements. As an example, we apply this framework to construct a model for the Fermi-LAT excess of GeV γ-rays from the galactic center. We comment on the viability of this portal for self-interacting dark matter explanations of small scale structure anomalies and embeddings in flavor models. Models of this type are shown to be compatible with the muon anomalous magnetic moment anomaly. We review current experimental constraints and identify possible future theoretical and experimental directions.

  8. Phenomenological aspects of mirage mediation

    Energy Technology Data Exchange (ETDEWEB)

    Loewen, Valeri

    2009-07-15

    We consider the possibility that string theory vacua with spontaneously broken supersymmetry and a small positive cosmological constant arise due to hidden sector matter interactions, known as F-uplifting/F-downlifting. We analyze this procedure in a model-independent way in the context of type IIB and heterotic string theory. Our investigation shows that the uplifting/downlifting sector has very important consequences for the resulting phenomenology. Not only does it adjust the vacuum energy, but it can also participate in the process of moduli stabilization. In addition, we find that this sector is the dominant source of supersymmetry breaking. It leads to a hybrid mediation scheme and its signature is a relaxed mirage pattern of the soft supersymmetry breaking terms. The low energy spectra exhibit distinct phenomenological properties and di er from conventional schemes considered so far. (orig.)

  9. Phenomenological aspects of mirage mediation

    International Nuclear Information System (INIS)

    Loewen, Valeri

    2009-07-01

    We consider the possibility that string theory vacua with spontaneously broken supersymmetry and a small positive cosmological constant arise due to hidden sector matter interactions, known as F-uplifting/F-downlifting. We analyze this procedure in a model-independent way in the context of type IIB and heterotic string theory. Our investigation shows that the uplifting/downlifting sector has very important consequences for the resulting phenomenology. Not only does it adjust the vacuum energy, but it can also participate in the process of moduli stabilization. In addition, we find that this sector is the dominant source of supersymmetry breaking. It leads to a hybrid mediation scheme and its signature is a relaxed mirage pattern of the soft supersymmetry breaking terms. The low energy spectra exhibit distinct phenomenological properties and di er from conventional schemes considered so far. (orig.)

  10. Lepton-mediated electroweak baryogenesis

    International Nuclear Information System (INIS)

    Chung, Daniel J. H.; Garbrecht, Bjorn; Ramsey-Musolf, Michael J.; Tulin, Sean

    2010-01-01

    We investigate the impact of the tau and bottom Yukawa couplings on the transport dynamics for electroweak baryogenesis in supersymmetric extensions of the standard model. Although it has generally been assumed in the literature that all Yukawa interactions except those involving the top quark are negligible, we find that the tau and bottom Yukawa interaction rates are too fast to be neglected. We identify an illustrative 'lepton-mediated electroweak baryogenesis' scenario in which the baryon asymmetry is induced mainly through the presence of a left-handed leptonic charge. We derive analytic formulas for the computation of the baryon asymmetry that, in light of these effects, are qualitatively different from those in the established literature. In this scenario, for fixed CP-violating phases, the baryon asymmetry has opposite sign compared to that calculated using established formulas.

  11. Vasoactive mediators and splanchnic perfusion.

    Science.gov (United States)

    Reilly, P M; Bulkley, G B

    1993-02-01

    To provide an overview of the splanchnic hemodynamic response to circulatory shock. Previous studies performed in our own laboratory, as well as a computer-assisted search of the English language literature (MEDLINE, 1966 to 1991), followed by a selective review of pertinent articles. Studies were selected that demonstrated relevance to the splanchnic hemodynamic response to circulatory shock, either by investigating the pathophysiology or documenting the sequelae. Article selection included clinical studies as well as studies in appropriate animal models. Pertinent data were abstracted from the cited articles. The splanchnic hemodynamic response to circulatory shock is characterized by a selective vasoconstriction of the mesenteric vasculature mediated largely by the renin-angiotensin axis. This vasospasm, while providing a natural selective advantage to the organism in mild-to-moderate shock (preserving relative perfusion of the heart, kidneys, and brain), may, in more severe shock, cause consequent loss of the gut epithelial barrier, or even hemorrhagic gastritis, ischemic colitis, or ischemic hepatitis. From a physiologic standpoint, nonpulsatile cardiopulmonary bypass, a controlled form of circulatory shock, has been found experimentally to significantly increase circulating levels of angiotensin II, the hormone responsible for this selective splanchnic vasoconstriction. While angiotensin II has been viewed primarily as the mediator responsible for the increased total vascular resistance seen during (and after) cardiopulmonary bypass, it may also cause the disproportionate decrease in mesenteric perfusion, as measured in human subjects by intraluminal gastric tonometry and galactose clearance by the liver, as well as the consequent development of the multiple organ failure syndrome seen in 1% to 5% of patients after cardiac surgery.

  12. Mediated electrochemical hazardous waste destruction

    International Nuclear Information System (INIS)

    Hickman, R.G.; Farmer, J.C.; Wang, F.T.

    1991-08-01

    There are few permitted processes for mixed waste (radioactive plus chemically hazardous) treatment. We are developing electrochemical processes that convert the toxic organic components of mixed waste to water, carbon dioxide, an innocuous anions such as chloride. Aggressive oxidizer ions such as Ag 2+ or Ce +4 are produced at an anode. These can attack the organic molecules directly. They can also attack water which yields hydroxyl free radicals that in turn attack the organic molecules. The condensed (i.e., solid and/or liquid) effluent streams contain the inorganic radionuclide forms. These may be treated with existing technology and prepared for final disposal. Kinetics and the extent of destruction of some toxic organics have been measured. Depending on how the process is operated, coulombic efficiency can be nearly 100%. In addition, hazardous organic materials are becoming very expensive to dispose of and when they are combined with transuranic radioactive elements no processes are presently permitted. Mediated electrochemical oxidation is an ambient-temperature aqueous-phase process that can be used to oxidize organic components of mixed wastes. Problems associated with incineration, such as high-temperature volatilization of radionuclides, are avoided. Historically, Ag (2) has been used as a mediator in this process. Fe(6) and Co(3) are attractive alternatives to Ag(2) since they form soluble chlorides during the destruction of chlorinated solvents. Furthermore, silver itself is a toxic heavy metal. Quantitative data has been obtained for the complete oxidation of ethylene glycol by Fe(6) and Co(3). Though ethylene glycol is a nonhalogenated organic, this data has enabled us to make direct comparisons of activities of Fe(6) and Co(3) with Ag(2). Very good quantitative data for the oxidation of ethylene glycol by Ag(2) had already been collected. 4 refs., 6 figs

  13. Designing business rules for mediation : a process towards agent-mediated business coordination

    OpenAIRE

    Zhao, Z.; Dignum, M.V.; Dignum, F.P.M.

    2008-01-01

    Business process integration is a very active research area, in which mediation is one of the fundamental architectural choices. Mediators have difficulties to design mediation services that meet the requirements of the different stakeholders. Business rules play an important role in the decision process of mediation. In this paper, we analyze the role of business rules in the decision process, and use some examples to illustrate how business rules should be designed in order to help the deci...

  14. MEDIATOR18 and MEDIATOR20 confer susceptibility to Fusarium oxysporum in Arabidopsis thaliana

    OpenAIRE

    Fallath, Thorya; Kidd, Brendan N.; Stiller, Jiri; Davoine, Celine; Bj?rklund, Stefan; Manners, John M.; Kazan, Kemal; Schenk, Peer M.

    2017-01-01

    The conserved protein complex known as Mediator conveys transcriptional signals by acting as an intermediary between transcription factors and RNA polymerase II. As a result, Mediator subunits play multiple roles in regulating developmental as well as abiotic and biotic stress pathways. In this report we identify the head domain subunits MEDIATOR18 and MEDIATOR20 as important susceptibility factors for Fusarium oxysporum infection in Arabidopsis thaliana. Mutants of MED18 and MED20 display do...

  15. Forms of Mediation: The Case of Interpreter-Mediated Interactions in Medical Systems

    Science.gov (United States)

    Baraldi, Claudio

    2009-01-01

    This paper analyses the forms of mediation in interlinguistic interactions performed in Italian healthcare services and in contexts of migration. The literature encourages dialogic transformative mediation, empowering participants' voices and changing cultural presuppositions in social systems. It may be doubtful, however, whether mediation can…

  16. Designing business rules for mediation : a process towards agent-mediated business coordination

    NARCIS (Netherlands)

    Zhao, Z.; Dignum, M.V.; Dignum, F.P.M.

    2008-01-01

    Business process integration is a very active research area, in which mediation is one of the fundamental architectural choices. Mediators have difficulties to design mediation services that meet the requirements of the different stakeholders. Business rules play an important role in the

  17. Factor affecting Agrobacterium -mediated transformation of rice ...

    African Journals Online (AJOL)

    Potato is a very important food crop and is adversely affected by fungus. Agrobacterium-mediated transformation can play an important role in the improvement of potato. The present study was conducted to optimize the different factors affecting Agrobacterium-mediated transformation of chitinase gene. Nodes were used as ...

  18. Regional Organisations and International Mediation: The ...

    African Journals Online (AJOL)

    Regional Organisations and International Mediation: The Effectiveness of Insider Mediators. ... During the last two decades of the twentieth century, the world witnessed an increasing number of regional conflict management efforts undertaken by regional inter-governmental organisations. There are therefore strong reasons ...

  19. Parent Mediation Empowers Sibling Conflict Resolution

    Science.gov (United States)

    Ross, Hildy S.; Lazinski, Marysia J.

    2014-01-01

    Research Findings: For the current study, formal mediation procedures were adapted for families and parents were trained and asked to mediate their children's disputes; control group parents intervened as they normally would. Conflict negotiations with parents and their children (ages 3½-11 years) occurring 3 and 7 weeks following training, and…

  20. Semiotic Mediation within an AT Frame

    Science.gov (United States)

    Maracci, Mirko; Mariotti, Maria Alessandra

    2013-01-01

    This article is meant to present a specific elaboration of the notion of mediation in relation to the use of artefacts to enhance mathematics teaching and learning: the elaboration offered by the Theory of Semiotic Mediation. In particular, it provides an explicit model--consistent with the activity-actions-operations framework--of the actions…