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Sample records for brms1 transcriptional repression

  1. Phosphorylation of RelA/p65 promotes DNMT-1 recruitment to chromatin and represses transcription of the tumor metastasis suppressor gene BRMS1

    OpenAIRE

    Liu, Yuan; Mayo, Marty W.; Nagji, Alykhan S.; Smith, Philip W.; Ramsey, Catherine S.; Li, Duo; David R Jones

    2011-01-01

    The majority of patients with lung cancer present with metastatic disease. Chronic inflammation and subsequent activation of NF-κB have been associated the development of cancers. The RelA/p65 subunit of NF-κB is typically associated with transcriptional activation. In this report we show that RelA/p65 can function as an active transcriptional repressor through enhanced methylation of the BRMS1 metastasis suppressor gene promoter via direct recruitment of DNMT-1 to chromatin in response to TN...

  2. Cytoplasmic BRMS1 expression in malignant melanoma is associated with increased disease-free survival

    Directory of Open Access Journals (Sweden)

    Slipicevic Ana

    2012-02-01

    Full Text Available Abstract Background/aims Breast cancer metastasis suppressor 1 (BRMS1 blocks metastasis in melanoma xenografts; however, its usefulness as a biomarker in human melanomas has not been widely studied. The goal was to measure BRMS1 expression in benign nevi, primary and metastatic melanomas and evaluate its impact on disease progression and prognosis. Methods Paraffin-embedded tissue from 155 primary melanomas, 69 metastases and 15 nevi was examined for BRMS1 expression using immunohistochemistry. siRNA mediated BRMS1 down-regulation was used to study impact on invasion and migration in melanoma cell lines. Results A significantly higher percentage of nevi (87%, compared to primary melanomas (20% and metastases (48%, expressed BRMS1 in the nucelus (p Waf1/Cip1 (p = 0.009. Cytoplasmic score index was inversely associated with nuclear p-Akt (p = 0.013 and positively associated with cytoplasmic p-ERK1/2 expression (p = 0.033. Nuclear BRMS1 expression in ≥ 10% of primary melanoma cells was associated with thicker tumors (p = 0.016 and decreased relapse-free period (p = 0.043. Nuclear BRMS1 was associated with expression of fatty acid binding protein 7 (FABP7; p = 0.011, a marker of invasion in melanomas. In line with this, repression of BRMS1 expression reduced the ability of melanoma cells to migrate and invade in vitro. Conclusion Our data suggest that BRMS1 is localized in cytoplasm and nucleus of melanocytic cells and that cellular localization determines its in vivo effect. We hypothesize that cytoplasmic BRMS1 restricts melanoma progression while nuclear BRMS1 possibly promotes melanoma cell invasion. Please see related article: http://www.biomedcentral.com/1741-7015/10/19

  3. Low BRMS1 expression promotes nasopharyngeal carcinoma metastasis in vitro and in vivo and is associated with poor patient survival

    International Nuclear Information System (INIS)

    Breast cancer metastasis suppressor 1 (BRMS1) is a metastasis suppressor gene. This study aimed to investigate the impact of BRMS1 on metastasis in nasopharyngeal carcinoma (NPC) and to evaluate the prognostic significance of BRMS1 in NPC patients. BRMS1 expression was examined in NPC cell lines using quantitative reverse transcription-polymerase chain reaction and Western blotting. NPC cells stably expressing BRMS1 were used to perform wound healing and invasion assays in vitro and a murine xenograft assay in vivo. Immunohistochemical staining was performed in 274 paraffin-embedded NPC specimens divided into a training set (n = 120) and a testing set (n = 154). BRMS1 expression was down-regulated in NPC cell lines. Overexpression of BRMS1 significantly reversed the metastatic phenotype of NPC cells in vitro and in vivo. Importantly, low BRMS1 expression was associated with poor distant metastasis-free survival (DMFS, P < 0.001) and poor overall survival (OS, P < 0.001) in the training set; these results were validated in the testing set and overall patient population. Cox regression analysis demonstrated that low BRMS1 expression was an independent prognostic factor for DMFS and OS in NPC. Low expression of the metastasis suppressor BRMS1 may be an independent prognostic factor for poor prognosis in NPC patients

  4. Cytoplasmic BRMS1 expression in malignant melanoma is associated with increased disease-free survival

    International Nuclear Information System (INIS)

    -free period (p = 0.043). Nuclear BRMS1 was associated with expression of fatty acid binding protein 7 (FABP7; p = 0.011), a marker of invasion in melanomas. In line with this, repression of BRMS1 expression reduced the ability of melanoma cells to migrate and invade in vitro. Our data suggest that BRMS1 is localized in cytoplasm and nucleus of melanocytic cells and that cellular localization determines its in vivo effect. We hypothesize that cytoplasmic BRMS1 restricts melanoma progression while nuclear BRMS1 possibly promotes melanoma cell invasion. Please see related article: http://www.biomedcentral.com/1741-7015/10/19

  5. Expression of metastasis suppressor BRMS1 in breast cancer cells results in a marked delay in cellular adhesion to matrix

    Science.gov (United States)

    Metastatic dissemination is a multi-step process that depends on cancer cells’ ability to respond to microenvironmental cues by adapting adhesion abilities and undergoing cytoskeletal rearrangement. Breast Cancer Metastasis Suppressor 1 (BRMS1) affects several steps of the metastatic cascade: it dec...

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

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    Wen-feng Shi

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

  7. BRMS1和 Survivin 在乳腺癌中的表达及临床意义%Expression and clinical significance of BRMS1 and Survivin in breast cancer

    Institute of Scientific and Technical Information of China (English)

    王大勇

    2014-01-01

    Objective To investigate the expression and clinical significance of BRMS1 and Survivin in breast cancer,and to explore the correlation between them and their effects on the pathogenesis ,development,metastasis and prognosis of breast cancer.Methods The expression levels of BRMS1 and Survivin were detected by immunohistochemistry in 160 cases of breast cancer,70 cases of mammary glands benign proliferative lesions and 40 cases of normal tissues adjacent to breast cancer.The data was analyzed together with clinical pathological parameters .Results The positive expression rates of BRMS1in breast cancer, mammary glands benign proliferative lesions and normal tissues adjacent to breast cancer were 34.4%,81.4%,95.0%,respectively,the positive expression rates of BRMS1 in breast cancer were significantly decreased ,as compared with those in mammary glands benign proliferative lesions and normal tissues adjacent to breast cancer ( P <0.05).However the positive expression rates of Survivin in breast cancer ,mammary glands benign proliferative lesions and normal tissues adjacent to breast cancer were 78.8%,17.1%,0,respectively,the positive expression rates of Survivin breast cancer were significantly increased,as compared with those in mammary glands benign proliferative lesions and normal tissues adjacent to breast cancer ( P <0.05).The abnormal expression of BRMS1 and Survivin in breast cancer tissue was correlated to TNM clinical stage and lymph node metastasis .Survivin was also related to histological grade .The abnormal expression of BRMS1 and Survivin in breast cancer tissue was not related to patient's age and tumor's size,but the expression of BRMS1 was negatively correlated with that of Survivin .Conclusion BRMS1 and Survivin play an important role in the carcinogenesis , development,metastasis and prognosis of breast cancer ,which can be used as the markers in diagnosis and prognosis evaluation of breast cancer.%目的:观察BRMS1和Survivin在人乳腺癌组

  8. Hairy Transcriptional Repression Targets and Cofactor Recruitment in Drosophila

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    Bianchi-Frias Daniella

    2004-01-01

    Full Text Available Members of the widely conserved Hairy/Enhancer of split family of basic Helix-Loop-Helix repressors are essential for proper Drosophila and vertebrate development and are misregulated in many cancers. While a major step forward in understanding the molecular mechanism(s surrounding Hairy-mediated repression was made with the identification of Groucho, Drosophila C-terminal binding protein (dCtBP, and Drosophila silent information regulator 2 (dSir2 as Hairy transcriptional cofactors, the identity of Hairy target genes and the rules governing cofactor recruitment are relatively unknown. We have used the chromatin profiling method DamID to perform a global and systematic search for direct transcriptional targets for Drosophila Hairy and the genomic recruitment sites for three of its cofactors: Groucho, dCtBP, and dSir2. Each of the proteins was tethered to Escherichia coli DNA adenine methyltransferase, permitting methylation proximal to in vivo binding sites in both Drosophila Kc cells and early embryos. This approach identified 40 novel genomic targets for Hairy in Kc cells, as well as 155 loci recruiting Groucho, 107 loci recruiting dSir2, and wide genomic binding of dCtBP to 496 loci. We also adapted DamID profiling such that we could use tightly gated collections of embryos (2-6 h and found 20 Hairy targets related to early embryogenesis. As expected of direct targets, all of the putative Hairy target genes tested show Hairy-dependent expression and have conserved consensus C-box-containing sequences that are directly bound by Hairy in vitro. The distribution of Hairy targets in both the Kc cell and embryo DamID experiments corresponds to Hairy binding sites in vivo on polytene chromosomes. Similarly, the distributions of loci recruiting each of Hairy's cofactors are detected as cofactor binding sites in vivo on polytene chromosomes. We have identified 59 putative transcriptional targets of Hairy. In addition to finding putative targets for

  9. Mechanisms of transcriptional repression by histone lysine methylation

    DEFF Research Database (Denmark)

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

    During development, covalent modification of both, histones and DNA contribute to the specification and maintenance of cell identity. Repressive modifications are thought to stabilize cell type specific gene expression patterns, reducing the likelihood of reactivation of lineage-unrelated genes. ...

  10. Four chromo-domain proteins of Schizosaccharomyces pombe differentially repress transcription at various chromosomal locations.

    OpenAIRE

    Thon, G.; Verhein-Hansen, J.

    2000-01-01

    Transcription is repressed in regions of the fission yeast genome close to centromeres, telomeres, or the silent mating-type cassettes mat2-P and mat3-M. The repression involves the chromo-domain proteins Swi6 and Clr4. We report that two other chromo-domain proteins, Chp1 and Chp2, are also important for these position effects. Chp1 showed a specificity for centromeric regions. Its essentiality for the transcriptional repression of centromeric markers correlates with its importance for chrom...

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

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    Carlos Farkas

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

  12. Activator control of nucleosome occupancy in activation and repression of transcription.

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    Gene O Bryant

    2008-12-01

    Full Text Available The relationship between chromatin structure and gene expression is a subject of intense study. The universal transcriptional activator Gal4 removes promoter nucleosomes as it triggers transcription, but how it does so has remained obscure. The reverse process, repression of transcription, has often been correlated with the presence of nucleosomes. But it is not known whether nucleosomes are required for that effect. A new quantitative assay describes, for any given location, the fraction of DNA molecules in the population that bears a nucleosome at any given instant. This allows us to follow the time courses of nucleosome removal and reformation, in wild-type and mutant cells, upon activation (by galactose and repression (by glucose of the GAL genes of yeast. We show that upon being freed of its inhibitor Gal80 by the action of galactose, Gal4 quickly recruits SWI/SNF to the genes, and that nucleosome "remodeler" rapidly removes promoter nucleosomes. In the absence of SWI/SNF, Gal4's action also results in nucleosome removal and the activation of transcription, but both processes are significantly delayed. Addition of glucose to cells growing in galactose represses transcription. But if galactose remains present, Gal4 continues to work, recruiting SWI/SNF and maintaining the promoter nucleosome-free despite it being repressed. This requirement for galactose is obviated in a mutant in which Gal4 works constitutively. These results show how an activator's recruiting function can control chromatin structure both during gene activation and repression. Thus, both under activating and repressing conditions, the activator can recruit an enzymatic machine that removes promoter nucleosomes. Our results show that whereas promoter nucleosome removal invariably accompanies activation, reformation of nucleosomes is not required for repression. The finding that there are two routes to nucleosome removal and activation of transcription-one that requires the

  13. Proto-oncogene FBI-1 Represses Transcription of p21CIP1 by Inhibition of Transcription Activation by p53 and Sp1*S⃞

    OpenAIRE

    Choi, Won-Il; Jeon, Bu-Nam; Yun, Chae-Ok; Kim, Pyung-Hwan; Kim, Sung-Eun; Choi, Kang-Yell; Kim, Se Hoon; Hur, Man-Wook

    2009-01-01

    Aberrant transcriptional repression through chromatin remodeling and histone deacetylation has been postulated as the driving force for tumorigenesis. FBI-1 (formerly called Pokemon) is a member of the POK family of transcriptional repressors. Recently, FBI-1 was characterized as a critical oncogenic factor that specifically represses transcription of the tumor suppressor gene ARF, potentially leading indirectly to p53 inactivation. Our investigations on transcriptiona...

  14. Mechanisms of transcriptional repression by EWS-FLl1 in Ewing Sarcoma

    International Nuclear Information System (INIS)

    The EWS-FLI1 chimeric oncoprotein characterizing Ewing Sarcoma (ES) is a prototypic aberrant ETS transcription factor with activating and repressive gene regulatory functions. Mechanisms of transcriptional regulation, especially transcriptional repression by EWS-FLI1, are poorly understood. We report that EWS-FLI1 repressed promoters are enriched in forkhead box recognition motifs, and identify FOXO1 as a EWS-FLI1 suppressed master regulator responsible for a significant subset of EWS-FLI1 repressed genes. In addition to transcriptional FOXO1 regulation by direct promoter binding of EWS-FLI1, its subcellular localization and activity is regulated by CDK2 and AKT mediated phosphorylation downstream of EWS-FLI1. Functional restoration of nuclear FOXO1 expression in ES cells impaired proliferation and significantly reduced clonogenicity. Gene-expression profiling revealed a significant overlap between EWS-FLI1 repressed and FOXO1-activated genes. Treatment of ES cell lines with Methylseleninic acid (MSA) evoked reactivation of endogenous FOXO1 in the presence of EWS-FLI1 in a dose- and time-dependent manner and induced massive cell death which was found to be partially FOXO1-dependent. In an orthotopic xenograft mouse model, MSA increased FOXO1 expression in the tumor paralleled by a significant decrease in ES tumor growth. Together, these data suggest that a repressive sub-signature of EWS-FLI1 repressed genes precipitates suppression of FOXO1. FOXO1 re-activation by small molecules may therefore constitute a novel therapeutic strategy in the treatment of ES. (author)

  15. Selenite transiently represses transcription of photosynthesis-related genes in potato leaves.

    Science.gov (United States)

    Poggi, Valeria; Del Vescovo, Valerio; Di Sanza, Claudio; Negri, Rodolfo; Hochkoeppler, Alejandro

    2008-01-01

    A striking response of potato leaves to aspersion with selenite was observed at the transcriptional level by means of cDNA microarrays analysis. This response is characterized by a general transient repression of genes coding for components of photosynthetic systems and of other light-regulated genes. In particular, maximal repression was observed 8 h after selenite aspersion, while 24 h after the treatment a complete recovery of normal transcriptional levels was detected. Another general feature of the transcriptional response to selenite is represented by the transcriptional induction of genes related to amino acid metabolism, and to stress defense; interestingly, two genes coding for glutathione S-transferases were found early-induced upon selenite treatment. PMID:17846914

  16. 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

  17. Repression of RNA Polymerase I Transcription by the Tumor Suppressor p53

    OpenAIRE

    Zhai, Weiguo; Comai, Lucio

    2000-01-01

    The tumor suppressor protein p53 is frequently inactivated in tumors. It functions as a transcriptional activator as well as a repressor for a number of viral and cellular promoters transcribed by RNA polymerase II (Pol II) and by RNA Pol III. Moreover, it appears that p53 also suppresses RNA Pol I transcription. In this study, we examined the molecular mechanism of Pol I transcriptional inhibition by p53. We show that wild-type, but not mutant, p53 can repress Pol I transcription from a huma...

  18. Transcriptional Repression of Gata3 Is Essential for Early B Cell Commitment

    OpenAIRE

    Banerjee, Anupam; Northrup, Daniel; Boukarabila, Hanane; Jacobsen, Sten Erik W.; Allman, David

    2013-01-01

    Summary The mechanisms underlying the silencing of alternative fate potentials in very early B cell precursors remain unclear. Using gain- and loss-of-function approaches together with a synthetic Zinc-finger polypeptide (6ZFP) engineered to prevent transcription factor binding to a defined cis element, we show that the transcription factor EBF1 promotes B cell lineage commitment by directly repressing expression of the T-cell-lineage-requisite Gata3 gene. Ebf1-deficient lymphoid progenitors ...

  19. 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...

  20. Repression of the human papillomavirus type 18 enhancer by the cellular transcription factor Oct-1.

    Science.gov (United States)

    Hoppe-Seyler, F; Butz, K; zur Hausen, H

    1991-01-01

    The role of cellular factors involved in the transcriptional regulation of the cancer-associated human papillomavirus type 18 (HPV18) is yet poorly understood. The presence of an Oct-1-binding site within the HPV18 upstream regulatory region led us to investigate the influence of Oct-1 on viral transcription. Cotransfection of Oct-1 expression plasmids together with luciferase reporter constructs containing HPV18 regulatory sequences indicated that Oct-1 can transcriptionally repress the HPV18 upstream regulatory region. In contrast, heterologous control regions were not affected by Oct-1. HPV18 cis elements that can be repressed by Oct-1 mapped to a 135-bp subregion of the viral constitutive enhancer. Analysis of an Oct-1 mutant defective in DNA binding suggested that HPV18 down-modulation does not require direct binding of Oct-1 to DNA. These results make Oct-1 a candidate factor involved in the intracellular surveillance of HPV18 transcription and support the notion of a host cell mechanism that can specifically repress HPV E6-E7 transforming gene expression. Images PMID:1654457

  1. Epigenetic repression of ribosomal RNA transcription by ROCK-dependent aberrant cytoskeletal organization

    Science.gov (United States)

    Wu, Tse-Hsiang; Kuo, Yuan-Yeh; Lee, Hsiao-Hui; Kuo, Jean-Cheng; Ou, Meng-Hsin; Chang, Zee-Fen

    2016-01-01

    It is known that ribosomal RNA (rRNA) synthesis is regulated by cellular energy and proliferation status. In this study, we investigated rRNA gene transcription in response to cytoskeletal stress. Our data revealed that the cell shape constrained by isotropic but not elongated micropatterns in HeLa cells led to a significant reduction in rRNA transcription dependent on ROCK. Expression of a dominant-active form of ROCK also repressed rRNA transcription. Isotropic constraint and ROCK over-activation led to different types of aberrant F-actin organization, but their suppression effects on rRNA transcription were similarly reversed by inhibition of histone deacetylase (HDAC) or overexpression of a dominant negative form of Nesprin, which shields the signal transmitted from actin filament to the nuclear interior. We further showed that the binding of HDAC1 to the active fraction of rDNA genes is increased by ROCK over-activation, thus reducing H3K9/14 acetylation and suppressing transcription. Our results demonstrate an epigenetic control of active rDNA genes that represses rRNA transcription in response to the cytoskeletal stress. PMID:27350000

  2. ASXL1 Represses Retinoic Acid Receptor-mediated Transcription through Associating with HP1 and LSD1*

    OpenAIRE

    Lee, Sang-Wang; Cho, Yang-Sook; Na, Jung-Min; Park, Ui-Hyun; Kang, Myengmo; Kim, Eun-Joo; Um, Soo-Jong

    2009-01-01

    We previously suggested that ASXL1 (additional sex comb-like 1) functions as either a coactivator or corepressor for the retinoid receptors retinoic acid receptor (RAR) and retinoid X receptor in a cell type-specific manner. Here, we provide clues toward the mechanism underlying ASXL1-mediated repression. Transfection assays in HEK293 or H1299 cells indicated that ASXL1 alone possessing autonomous transcriptional repression activity significantly represses RAR- or retinoid X receptor-dependen...

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

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    Shadi Jafari

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

  4. PTEN Represses RNA Polymerase I Transcription by Disrupting the SL1 Complex†

    OpenAIRE

    Zhang, Cheng; Comai, Lucio; Johnson, Deborah L.

    2005-01-01

    PTEN is a tumor suppressor whose function is frequently lost in human cancer. It possesses a lipid phosphatase activity that represses the activation of PI3 kinase/Akt signaling, leading to decreased cell growth, proliferation, and survival. The potential for PTEN to regulate transcription of the large rRNAs by RNA polymerase I (RNA Pol I) was investigated. As increased synthesis of rRNAs is a hallmark of neoplastic transformation, the ability of PTEN to control the transcription of rRNAs mig...

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

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    Manuela Vanti

    2009-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-02-07

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

  8. Mycobacterium leprae induces NF-κB-dependent transcription repression in human Schwann cells

    International Nuclear Information System (INIS)

    Mycobacterium leprae, the causative agent of leprosy, invades peripheral nerve Schwann cells, resulting in deformities associated with this disease. NF-κB is an important transcription factor involved in the regulation of host immune antimicrobial responses. We aimed in this work to investigate NF-κB signaling pathways in the human ST88-14 Schwannoma cell line infected with M. leprae. Gel shift and supershift assays indicate that two NF-κB dimers, p65/p50 and p50/p50, translocate to the nucleus in Schwann cells treated with lethally irradiated M. leprae. Consistent with p65/p50 and p50/p50 activation, we observed IκB-α degradation and reduction of p105 levels. The nuclear translocation of p50/p50 complex due to M. leprae treatment correlated with repression of NF-κB-driven transcription induced by TNF-α. Moreover, thalidomide inhibited p50 homodimer nuclear translocation induced by M. leprae and consequently rescues Schwann cells from NF-κB-dependent transcriptional repression. Here, we report for the first time that M. leprae induces NF-κB activation in Schwann cells and thalidomide is able to modulate this activation

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

    Directory of Open Access Journals (Sweden)

    José Perdomo

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

  10. A response regulator that represses transcription of several virulence operons in the group A streptococcus.

    Science.gov (United States)

    Federle, M J; McIver, K S; Scott, J R

    1999-06-01

    A search for homologs of the Bacillus subtilis PhoP response regulator in the group A streptococcus (GAS) genome revealed three good candidates. Inactivation of one of these, recently identified as csrR (J. C. Levin and M. R. Wessels, Mol. Microbiol. 30:209-219, 1998), caused the strain to produce mucoid colonies and to increase transcription of hasA, the first gene in the operon for capsule synthesis. We report here that a nonpolar insertion in this gene also increased transcription of ska (encoding streptokinase), sagA (streptolysin S), and speMF (mitogenic factor) but did not affect transcription of slo (streptolysin O), mga (multiple gene regulator of GAS), emm (M protein), scpA (complement C5a peptidase), or speB or speC (pyrogenic exotoxins B and C). The amounts of streptokinase, streptolysin S, and capsule paralleled the levels of transcription of their genes in all cases. Because CsrR represses genes unrelated to those for capsule synthesis, and because CsrA-CsrB is a global regulatory system in Escherichia coli whose mechanism is unrelated to that of these genes in GAS, the locus has been renamed covR, for "control of virulence genes" in GAS. Transcription of the covR operon was also increased in the nonpolar insertion mutant, indicating that CovR represses its own synthesis as well. All phenotypes of the covR nonpolar insertion mutant were complemented by the covR gene on a plasmid. CovR acts on operons expressed both in exponential and in stationary phase, demonstrating that the CovR-CovS pathway is separate from growth phase-dependent regulation in GAS. Therefore, CovR is the first multiple-gene repressor of virulence factors described for this important human pathogen. PMID:10368137

  11. The transcription factor ATF3 is upregulated during chondrocyte differentiation and represses cyclin D1 and A gene transcription

    Directory of Open Access Journals (Sweden)

    James Claudine G

    2006-09-01

    Full Text Available Abstract Background Coordinated chondrocyte proliferation and differentiation are required for normal endochondral bone growth. Transcription factors binding to the cyclicAMP response element (CRE are known to regulate these processes. One member of this family, Activating Tanscription Factor 3 (ATF3, is expressed during skeletogenesis and acts as a transcriptional repressor, but the function of this protein in chondrogenesis is unknown. Results Here we demonstrate that Atf3 mRNA levels increase during mouse chondrocyte differentiation in vitro and in vivo. In addition, Atf3 mRNA levels are increased in response to cytochalasin D treatment, an inducer of chondrocyte maturation. This is accompanied by increased Atf3 promoter activity in cytochalasin D-treated chondrocytes. We had shown earlier that transcription of the cell cycle genes cyclin D1 and cyclin A in chondrocytes is dependent on CREs. Here we demonstrate that overexpression of ATF3 in primary mouse chondrocytes results in reduced transcription of both genes, as well as decreased activity of a CRE reporter plasmid. Repression of cyclin A transcription by ATF3 required the CRE in the cyclin A promoter. In parallel, ATF3 overexpression reduces the activity of a SOX9-dependent promoter and increases the activity of a RUNX2-dependent promoter. Conclusion Our data suggest that transcriptional induction of the Atf3 gene in maturing chondrocytes results in down-regulation of cyclin D1 and cyclin A expression as well as activation of RUNX2-dependent transcription. Therefore, ATF3 induction appears to facilitate cell cycle exit and terminal differentiation of chondrocytes.

  12. Transcriptional profiling of mouse uterus at pre-implantation stage under VEGF repression.

    Directory of Open Access Journals (Sweden)

    Yan Ji

    Full Text Available Uterus development during pre-implantation stage affects implantation process and embryo growth. Aberrant uterus development is associated with many human reproductive diseases. Among the factors regulating uterus development, vascular remodeling promoters are critical for uterus function and fertility. Vascular endothelial growth factor (VEGF, as one of the major members, has been found to be important in endothelial cell growth and blood vessel development, as well as in non-endothelial cells. VEGF mediation in reproduction has been broadly studied, but VEGF-induced transcriptional machinery during implantation window has not been systematically studied. In this study, a genetically repressed VEGF mouse model was used to analyze uterus transcriptome at gestation 2.5 (G2.5 by Solexa/Illumina's digital gene expression (DGE system. A number of 831 uterus-specific and 2398 VEGF-regulated genes were identified. Gene ontology (GO analysis indicated that genes actively involved in uterus development were members of collagen biosynthesis, cell proliferation and cell apoptosis. Uterus-specific genes were enriched in activities of phosphatidyl inositol phosphate kinase, histone H3-K36 demethylation and protein acetylation. Among VEGF-regulated genes, up-regulated were associated with RNA polymerase III activity while down-regulated were strongly related with muscle development. Comparable numbers of antisense transcripts were identified. Expression levels of the antisense transcripts were found tightly correlated with their sense expression levels, an indication of possibly non-specific transcripts generated around the active promoters and enhancers. The antisense transcripts with exceptionally high or low expression levels and the antisense transcripts under VEGF regulation were also identified. These transcripts may be important candidates in regulation of uterus development. This study provides a global survey on genes and antisense transcripts

  13. Site-Specific Oligonucleotide Binding Represses Transcription of the Human c-myc Gene in vitro

    Science.gov (United States)

    Cooney, Michael; Czernuszewicz, Graznya; Postel, Edith H.; Flint, S. Jane; Hogan, Michael E.

    1988-07-01

    A 27-base-long DNA oligonucleotide was designed that binds to duplex DNA at a single site within the 5' end of the human c-myc gene, 115 base pairs upstream from the transcription origin P1. On the basis of the physical properties of its bound complex, it was concluded that the oligonucleotide forms a colinear triplex with the duplex binding site. By means of an in vitro assay system, it was possible to show a correlation between triplex formation at -115 base pairs and repression of c-myc transcription. The possibility is discussed that triplex formation (site-specific RNA binding to a DNA duplex) could serve as the basis for an alternative program of gene control in vivo.

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

    Directory of Open Access Journals (Sweden)

    Helene Persak

    2014-02-01

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

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

    Science.gov (United States)

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

    2015-07-01

    Members of the WRKY transcription factor superfamily are essential for the regulation of many plant pathways. Functional redundancy due to duplications of WRKY transcription factors, however, complicates genetic analysis by allowing single-mutant plants to maintain wild-type phenotypes. Our analyses indicate that three group I WRKY genes, OsWRKY24, -53, and -70, act in a partially redundant manner. All three showed characteristics of typical WRKY transcription factors: each localized to nuclei and yeast one-hybrid assays indicated that they all bind to W-boxes, including those present in their own promoters. Quantitative real time-PCR (qRT-PCR) analyses indicated that the expression levels of the three WRKY genes varied in the different tissues tested. Particle bombardment-mediated transient expression analyses indicated that all three genes repress the GA and ABA signaling in a dosage-dependent manner. Combination of all three WRKY genes showed additive antagonism of ABA and GA signaling. These results suggest that these WRKY proteins function as negative transcriptional regulators of GA and ABA signaling. However, different combinations of these WRKY genes can lead to varied strengths in suppression of their targets. PMID:26025535

  16. Proto-oncogene FBI-1 represses transcription of p21CIP1 by inhibition of transcription activation by p53 and Sp1.

    Science.gov (United States)

    Choi, Won-Il; Jeon, Bu-Nam; Yun, Chae-Ok; Kim, Pyung-Hwan; Kim, Sung-Eun; Choi, Kang-Yell; Kim, Se Hoon; Hur, Man-Wook

    2009-05-01

    Aberrant transcriptional repression through chromatin remodeling and histone deacetylation has been postulated as the driving force for tumorigenesis. FBI-1 (formerly called Pokemon) is a member of the POK family of transcriptional repressors. Recently, FBI-1 was characterized as a critical oncogenic factor that specifically represses transcription of the tumor suppressor gene ARF, potentially leading indirectly to p53 inactivation. Our investigations on transcriptional repression of the p53 pathway revealed that FBI-1 represses transcription of ARF, Hdm2 (human analogue of mouse double minute oncogene), and p21CIP1 (hereafter indicated as p21) but not of p53. FBI-1 showed a more potent repressive effect on p21 than on p53. Our data suggested that FBI-1 is a master controller of the ARF-Hdm2-p53-p21 pathway, ultimately impinging on cell cycle arrest factor p21, by inhibiting upstream regulators at the transcriptional and protein levels. FBI-1 acted as a competitive transcriptional repressor of p53 and Sp1 and was shown to bind the proximal Sp1-3 GC-box and the distal p53-responsive elements of p21. Repression involved direct binding competition of FBI-1 with Sp1 and p53. FBI-1 also interacted with corepressors, such as mSin3A, NCoR, and SMRT, thereby deacetylating Ac-H3 and Ac-H4 histones at the promoter. FBI-1 caused cellular transformation, promoted cell cycle proliferation, and significantly increased the number of cells in S phase. FBI-1 is aberrantly overexpressed in many human solid tumors, particularly in adenocarcinomas and squamous carcinomas. The role of FBI-1 as a master controller of the p53 pathway therefore makes it an attractive therapeutic target. PMID:19244234

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

    LENUS (Irish Health Repository)

    Lau, Kwok-Fai

    2010-08-04

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

  18. Dynamic competition between transcription initiation and repression: Role of nonequilibrium steps in cell-to-cell heterogeneity.

    Science.gov (United States)

    Mitarai, Namiko; Semsey, Szabolcs; Sneppen, Kim

    2015-08-01

    Transcriptional repression may cause transcriptional noise by a competition between repressor and RNA polymerase binding. Although promoter activity is often governed by a single limiting step, we argue here that the size of the noise strongly depends on whether this step is the initial equilibrium binding or one of the subsequent unidirectional steps. Overall, we show that nonequilibrium steps of transcription initiation systematically increase the cell-to-cell heterogeneity in bacterial populations. In particular, this allows also weak promoters to give substantial transcriptional noise. PMID:26382435

  19. PSD-95 is post-transcriptionally repressed during early neural development by PTBP1 and PTBP2

    DEFF Research Database (Denmark)

    Zheng, Sika; Gray, Erin E; Chawla, Geetanjali;

    2012-01-01

    . Psd-95 was transcribed early in mouse embryonic brain, but most of its product transcripts were degraded. The polypyrimidine tract binding proteins PTBP1 and PTBP2 repressed Psd-95 (also known as Dlg4) exon 18 splicing, leading to premature translation termination and nonsense-mediated mRNA decay...

  20. Repression of btuB gene transcription in Escherichia coli by the GadX protein

    Directory of Open Access Journals (Sweden)

    Hu Wensi S

    2011-02-01

    Full Text Available Abstract Background BtuB (B twelve uptake is an outer membrane protein of Escherichia coli, it serves as a receptor for cobalamines uptake or bactericidal toxin entry. A decrease in the production of the BtuB protein would cause E. coli to become resistant to colicins. The production of BtuB has been shown to be regulated at the post-transcriptional level. The secondary structure switch of 5' untranslated region of butB and the intracellular concentration of adenosylcobalamin (Ado-Cbl would affect the translation efficiency and RNA stability of btuB. The transcriptional regulation of btuB expression is still unclear. Results To determine whether the btuB gene is also transcriptionally controlled by trans-acting factors, a genomic library was screened for clones that enable E. coli to grow in the presence of colicin E7, and a plasmid carrying gadX and gadY genes was isolated. The lacZ reporter gene assay revealed that these two genes decreased the btuB promoter activity by approximately 50%, and the production of the BtuB protein was reduced by approximately 90% in the presence of a plasmid carrying both gadX and gadY genes in E. coli as determined by Western blotting. Results of electrophoretic mobility assay and DNase I footprinting indicated that the GadX protein binds to the 5' untranslated region of the btuB gene. Since gadX and gadY genes are more highly expressed under acidic conditions, the transcriptional level of btuB in cells cultured in pH 7.4 or pH 5.5 medium was examined by quantitative real-time PCR to investigate the effect of GadX. The results showed the transcription of gadX with 1.4-fold increase but the level of btuB was reduced to 57%. Conclusions Through biological and biochemical analysis, we have demonstrated the GadX can directly interact with btuB promoter and affect the expression of btuB. In conclusion, this study provides the first evidence that the expression of btuB gene is transcriptionally repressed by the acid

  1. Different mechanisms contribute to the E2-mediated transcriptional repression of human papillomavirus type 18 viral oncogenes.

    Science.gov (United States)

    Demeret, C; Desaintes, C; Yaniv, M; Thierry, F

    1997-12-01

    Transcription of the human papillomavirus type 18 (HPV18) E6 and E7 oncogenes is repressed by the viral E2 protein. In C33 cells, we have previously shown that of the four E2 binding sites (E2 BS) present in the HPV18 long control region (LCR), only the binding site adjacent to the TATA box (E2 BS 1) was involved in E2-mediated repression. In the present study, we sought to determine whether this phenomenon was conserved in other cell lines. We first showed that all three E2 BS proximal to the P105 promoter were required for full repression of its activity in HeLa and HaCaT cells. Repression by E2 at E2 BS 2 occurred through the displacement of Sp1. Second, a truncated E2 product, lacking the N-terminal transactivation domain, repressed transcription more efficiently than the full-length protein. Repression was abolished when the N-terminal domain of E2 was replaced by the activation domain of VP16. The VP16-E2 chimeric protein could activate transcription from an LCR mutated in its TATA box. DNA-protein binding studies showed that E2 associates with its four binding sites in the LCR with similar affinities. However, challenge of such complexes with excess binding sites demonstrated that interaction with E2 BS 4 was the most stable while interaction with E2 BS 1 was the least stable. Furthermore, complexes with the full-length E2 were less stable than those formed with the N-terminally truncated protein. PMID:9371593

  2. Repression of Ccr9 transcription in mouse T lymphocyte progenitors by the Notch signaling pathway.

    Science.gov (United States)

    Krishnamoorthy, Veena; Carr, Tiffany; de Pooter, Renee F; Emanuelle, Akinola Olumide; Akinola, Emanuelle Olumide; Gounari, Fotini; Kee, Barbara L

    2015-04-01

    The chemokine receptor CCR9 controls the immigration of multipotent hematopoietic progenitor cells into the thymus to sustain T cell development. Postimmigration, thymocytes downregulate CCR9 and migrate toward the subcapsular zone where they recombine their TCR β-chain and γ-chain gene loci. CCR9 is subsequently upregulated and participates in the localization of thymocytes during their selection for self-tolerant receptor specificities. Although the dynamic regulation of CCR9 is essential for early T cell development, the mechanisms controlling CCR9 expression have not been determined. In this article, we show that key regulators of T cell development, Notch1 and the E protein transcription factors E2A and HEB, coordinately control the expression of Ccr9. E2A and HEB bind at two putative enhancers upstream of Ccr9 and positively regulate CCR9 expression at multiple stages of T cell development. In contrast, the canonical Notch signaling pathway prevents the recruitment of p300 to the putative Ccr9 enhancers, resulting in decreased acetylation of histone H3 and a failure to recruit RNA polymerase II to the Ccr9 promoter. Although Notch signaling modestly modulates the binding of E proteins to one of the two Ccr9 enhancers, we found that Notch signaling represses Ccr9 in T cell lymphoma lines in which Ccr9 transcription is independent of E protein function. Our data support the hypothesis that activation of Notch1 has a dominant-negative effect on Ccr9 transcription and that Notch1 and E proteins control the dynamic expression of Ccr9 during T cell development. PMID:25710912

  3. PINCH1 is transcriptional regulator in podocytes that interacts with WT1 and represses podocalyxin expression.

    Directory of Open Access Journals (Sweden)

    Dan Wang

    Full Text Available BACKGROUND: PINCH1, an adaptor protein containing five LIM domains, plays an important role in regulating the integrin-mediated cell adhesion, migration and epithelial-mesenchymal transition. PINCH1 is induced in the fibrotic kidney after injury, and it primarily localizes at the sites of focal adhesion. Whether it can translocate to the nucleus and directly participate in gene regulation is completely unknown. METHODOLOGY/PRINCIPAL FINDINGS: Using cultured glomerular podocytes as a model system, we show that PINCH1 expression was induced by TGF-β1, a fibrogenic cytokine that promotes podocyte dysfunction. Interestingly, increased PINCH1 not only localized at the sites of focal adhesions, but also underwent nuclear translocation after TGF-β1 stimulation. This nuclear translocation of PINCH1 was apparently dependent on the putative nuclear export/localization signals (NES/NLS at its C-terminus, as deletion or site-directed mutations abolished its nuclear shuttling. Co-immunoprecipitation and pull-down experiments revealed that PINCH1 interacted with Wilms tumor 1 protein (WT1, a nuclear transcription factor that is essential for regulating podocyte-specific gene expression in adult kidney. Interaction of PINCH1 and WT1 was mediated by the LIM1 domain of PINCH1 and C-terminal zinc-finger domain of WT1, which led to the suppression of the WT1-mediated podocalyxin expression in podocytes. PINCH1 also repressed podocalyxin gene transcription in a promoter-luciferase reporter assay. CONCLUSION/SIGNIFICANCE: These results indicate that PINCH1 can shuttle into the nucleus from cytoplasm in podocytes, wherein it interacts with WT1 and suppresses podocyte-specific gene expression. Our studies reveal a previously unrecognized, novel function of PINCH1, in which it acts as a transcriptional regulator through controlling specific gene expression.

  4. Different mechanisms contribute to the E2-mediated transcriptional repression of human papillomavirus type 18 viral oncogenes.

    OpenAIRE

    Demeret, C; Desaintes, C.; Yaniv, M; Thierry, F

    1997-01-01

    Transcription of the human papillomavirus type 18 (HPV18) E6 and E7 oncogenes is repressed by the viral E2 protein. In C33 cells, we have previously shown that of the four E2 binding sites (E2 BS) present in the HPV18 long control region (LCR), only the binding site adjacent to the TATA box (E2 BS 1) was involved in E2-mediated repression. In the present study, we sought to determine whether this phenomenon was conserved in other cell lines. We first showed that all three E2 BS proximal to th...

  5. Estradiol repression of tumor necrosis factor-α transcription requires estrogen receptor activation function-2 and is enhanced by coactivators

    OpenAIRE

    An, Jinping; Ribeiro, Ralff C. J.; Webb, Paul; Gustafsson, Jan-Åke; Kushner, Peter J.; Baxter, John D.; Leitman, Dale C.

    1999-01-01

    The tumor necrosis factor-α (TNF-α) promoter was used to explore the molecular mechanisms of estradiol (E2)-dependent repression of gene transcription. E2 inhibited basal activity and abolished TNF-α activation of the TNF-α promoter. The E2-inhibitory element was mapped to the −125 to −82 region of the TNF-α promoter, known as the TNF-responsive element (TNF-RE). An AP-1-like site in the TNF-RE is essential for repression activity. Estrogen receptor (ER) β is more potent than ERα at repressin...

  6. Repression of the H5 histone gene by a factor from erythrocytes that binds to the region of transcription initiation.

    OpenAIRE

    Gómez-Cuadrado, A; Rousseau, S.; Renaud, J.; Ruiz-Carrillo, A

    1992-01-01

    Expression of histone H5, like that of other erythrocyte specific proteins, declines during the latter stages of erythroid maturation because of a decrease in the rate of gene transcription. Here, we report the isolation of cIBR (chicken initiation binding repressor), a 75 kDa DNA binding glycoprotein from mature chicken erythrocytes that recognizes sequences spanning the transcription start sites of the H5 gene. cIBR was found to repress transcription from the H5 promoter in vitro and this e...

  7. Let-7b promotes alpaca hair growth via transcriptional repression of TGFβR I.

    Science.gov (United States)

    Yan, Shen; Yu, Zhang; Ning, Liu; Hai-Dong, Wang; Jian-Shan, Xie; Shu-Yuan, Gao; Jia-Qi, Cheng; Xiu-Ju, Yu; Ting, Wang; Chang-Sheng, Dong; Xiao-Yan, He

    2016-02-10

    The young male alpaca ear and the back skins were used to investigate the effect of transforming growth factor receptor-β I (TGFβR I) on alpaca hair follicles and hair growth. The expression level and location of TGFβR I in alpaca ear and dorsal skin were detected through real-time quantitative PCR (RT-PCR) and paraffin section immunohistochemical technique (ICC-P). The results shown TGFβR I was lower expression in back skin compared to ear skin and the mean density of the positive reaction in ear skin was significantly higher than back skin. The targeted relationship with let-7b was detected using the dual-luciferase reporter vector of TGFβR I, which showed a significant target relationship between let-7b and TGFβR I. After transfection with let-7b eukaryotic expression vector, the relative mRNA expression of TGFβR I in alpaca skin fibroblasts did not differ, while the relative protein level was significantly decreased. In summary, a higher TGFβR I expression level in the ear skin suggests that TGFβR I may inhibit coat hair elongation. Further studies showed TGFβR I protein was downregulated by let-7b through transcriptional repression. PMID:26611528

  8. Dlx transcription factors promote migration through repression of axon and dendrite growth.

    Science.gov (United States)

    Cobos, Inma; Borello, Ugo; Rubenstein, John L R

    2007-06-21

    In the mouse telencephalon, Dlx homeobox transcription factors are essential for the tangential migration of subpallial-derived GABAergic interneurons to neocortex. However, the mechanisms underlying this process are poorly understood. Here, we demonstrate that Dlx1/2 has a central role in restraining neurite growth of subpallial-derived immature interneurons at a stage when they migrate tangentially to cortex. In Dlx1-/-;Dlx2-/- mutants, neurite length is increased and cells fail to migrate. In Dlx1-/-;Dlx2+/- mutants, while the tangential migration of immature interneurons appears normal, they develop dendritic and axonal processes with increased length and decreased branching, and have deficits in their neocortical laminar positions. Thus, Dlx1/2 is required for coordinating programs of neurite maturation and migration. In this regard, we provide genetic evidence that in immature interneurons Dlx1/2 repression of the p21-activated serine/threonine kinase PAK3, a downstream effector of the Rho family of GTPases, is critical in restraining neurite growth and promoting tangential migration. PMID:17582329

  9. Transcriptional repression of p27 is essential for murine embryonic development.

    Science.gov (United States)

    Teratake, Youichi; Kuga, Chisa; Hasegawa, Yuta; Sato, Yoshiharu; Kitahashi, Masayasu; Fujimura, Lisa; Watanabe-Takano, Haruko; Sakamoto, Akemi; Arima, Masafumi; Tokuhisa, Takeshi; Hatano, Masahiko

    2016-01-01

    The Nczf gene has been identified as one of Ncx target genes and encodes a novel KRAB zinc-finger protein, which functions as a sequence specific transcriptional repressor. In order to elucidate Nczf functions, we generated Nczf knockout (Nczf-/-) mice. Nczf-/- mice died around embryonic day 8.5 (E8.5) with small body size and impairment of axial rotation. Histopathological analysis revealed that the cell number decreased and pyknotic cells were occasionally observed. We examined the expression of cell cycle related genes in Nczf-/- mice. p27 expression was increased in E8.0 Nczf-/- mice compared to that of wild type mice. Nczf knockdown by siRNA resulted in increased expression of p27 in mouse embryonic fibroblasts (MEFs). Furthermore, p27 promoter luciferase reporter gene analysis confirmed the regulation of p27 mRNA expression by Nczf. Nczf-/-; p27-/- double knockout mice survived until E11.5 and the defect of axial rotation was restored. These data suggest that p27 repression by Nczf is essential in the developing embryo. PMID:27196371

  10. Repression of AS2 by WOX family transcription factors is required for leaf development in Medicago and Arabidopsis

    OpenAIRE

    Zhang, Fei; Tadege, Million

    2015-01-01

    WOX transcription factors are key regulators of meristematic activity in plants. The Medicago WOX gene, STF, functions in maintenance of leaf marginal meristem, analogous to the function of WUS in the shoot apical meristem. Both STF and WUS directly repress AS2 expression in their respective domains. Ectopic expression of AS2 with WUS promoter leads to a narrow leaf phenotype and other phenotypes similar to the wus mutant. We also found that a wox1 prs wus triple mutant produces much narrower...

  11. Telomere-Mediated Plasmid Segregation in Saccharomyces Cerevisiae Involves Gene Products Required for Transcriptional Repression at Silencers and Telomeres

    OpenAIRE

    Longtine, M. S.; Enomoto, S.; Finstad, S L; Berman, J

    1993-01-01

    Plasmids that contain Saccharomyces cerevisiae TG(1-3) telomere repeat sequences (TRS plasmids) segregate efficiently during mitosis. Mutations in histone H4 reduce the efficiency of TRS-mediated plasmid segregation, suggesting that chromatin structure is involved in this process. Sir2, Sir3 and Sir4 are required for the transcriptional repression of genes located at the silent mating type loci (HML and HMR) and at telomeres (telomere position effect) and are also involved in the segregation ...

  12. Suppressors of Defective Silencing in Yeast: Effects on Transcriptional Repression at the Hmr Locus, Cell Growth and Telomere Structure

    OpenAIRE

    Sussel, L; Vannier, D; Shore, D

    1995-01-01

    To identify factors that affect transcriptional silencing at the HMR mating-type locus in yeast, we characterized a set of extragenic suppressor mutations that restore metastable repression in cells containing both a mutant silencer-binding protein (rap1(s)) and a mutated silencer element (hmrδA). A total of 57 suppressors comprising 21 different complementation groups was identified. This report describes a detailed genetic analysis of these suppressors of defective silencing (sds) mutants. ...

  13. The catenin p120ctn inhibits Kaiso-mediated transcriptional repression of the β-catenin/TCF target gene matrilysin

    International Nuclear Information System (INIS)

    The POZ-zinc finger transcription factor Kaiso was first identified as a specific binding partner for the Armadillo catenin and cell adhesion cofactor, p120ctn. Kaiso is a unique POZ protein with bi-modal DNA-binding properties; it associates with a sequence-specific DNA consensus Kaiso binding site (KBS) or methylated CpG dinucleotides, and regulates transcription of artificial promoters containing either site. Interestingly, the promoter of the Wnt/β-catenin/TCF target gene matrilysin possesses two conserved copies of the KBS, which suggested that Kaiso might regulate matrilysin expression. In this study, we demonstrate using chromatin immunoprecipitation analysis that Kaiso associates with the matrilysin promoter in vivo. Minimal promoter assays further confirmed that Kaiso specifically repressed transcription of the matrilysin promoter; mutation of the KBS element or RNAi-mediated depletion of Kaiso abrogated this effect. More importantly, Kaiso blocked β-catenin-mediated activation of the matrilysin promoter. Consistent with our previous findings, both Kaiso-DNA binding and Kaiso-mediated transcriptional repression of the matrilysin promoter were inhibited by overexpression of wild-type p120ctn, but not by a p120ctn mutant exhibiting impaired nuclear import. Collectively, our data establish Kaiso as a sequence-specific transcriptional repressor of the matrilysin promoter, and suggest that p120ctn and β-catenin act in a synergistic manner, via distinct mechanisms, to activate matrilysin expression

  14. KRAB-zinc finger proteins and KAP1 can mediate long-range transcriptional repression through heterochromatin spreading.

    Directory of Open Access Journals (Sweden)

    Anna C Groner

    2010-03-01

    Full Text Available Krüppel-associated box domain-zinc finger proteins (KRAB-ZFPs are tetrapod-specific transcriptional repressors encoded in the hundreds by the human genome. In order to explore their as yet ill-defined impact on gene expression, we developed an ectopic repressor assay, allowing the study of KRAB-mediated transcriptional regulation at hundreds of different transcriptional units. By targeting a drug-controllable KRAB-containing repressor to gene-trapping lentiviral vectors, we demonstrate that KRAB and its corepressor KAP1 can silence promoters located several tens of kilobases (kb away from their DNA binding sites, with an efficiency which is generally higher for promoters located within 15 kb or less. Silenced promoters exhibit a loss of histone H3-acetylation, an increase in H3 lysine 9 trimethylation (H3K9me3, and a drop in RNA Pol II recruitment, consistent with a block of transcriptional initiation following the establishment of silencing marks. Furthermore, we reveal that KRAB-mediated repression is established by the long-range spreading of H3K9me3 and heterochromatin protein 1 beta (HP1beta between the repressor binding site and the promoter. We confirm the biological relevance of this phenomenon by documenting KAP1-dependent transcriptional repression at an endogenous KRAB-ZFP gene cluster, where KAP1 binds to the 3' end of genes and mediates propagation of H3K9me3 and HP1beta towards their 5' end. Together, our data support a model in which KRAB/KAP1 recruitment induces long-range repression through the spread of heterochromatin. This finding not only suggests auto-regulatory mechanisms in the control of KRAB-ZFP gene clusters, but also provides important cues for interpreting future genome-wide DNA binding data of KRAB-ZFPs and KAP1.

  15. Thanatos-associated protein 7 associates with template activating factor-Ibeta and inhibits histone acetylation to repress transcription.

    Science.gov (United States)

    Macfarlan, Todd; Parker, J Brandon; Nagata, Kyosuke; Chakravarti, Debabrata

    2006-02-01

    The posttranslational modifications of histones on chromatin or a lack thereof is critical in transcriptional regulation. Emerging studies indicate a role for histone-binding proteins in transcriptional activation and repression. We have previously identified template-activating factor-Ibeta (TAF-Ibeta, also called PHAPII, SET, and I(2)(pp2A)) as a component of a cellular complex called inhibitor of acetyltransferases (INHAT) that masks histone acetylation in vitro and blocks histone acetyltransferase (HAT)-dependent transcription in living cells. TAF-Ibeta has also been shown to associate with transcription factors, including nuclear receptors, to regulate their activities. To identify novel interactors of TAF-Ibeta, we employed a yeast two-hybrid screen and identified a previously uncharacterized human protein called thanatos-associated protein-7 (THAP7), a member of a large family of THAP domain-containing putative DNA-binding proteins. In this study we demonstrate that THAP7 associates with TAF-Ibeta in vitro and map their association domains to a C-terminal predicted coiled-coil motif on THAP7 and the central region of TAF-Ibeta. Similarly, stably transfected THAP7 associates with endogenous TAF-Ibeta in intact cells. Like TAF-Ibeta, THAP7 associates with histone H3 and histone H4 and inhibits histone acetylation. The histone-interacting domain of THAP7 is sufficient for this activity in vitro. Promoter-targeted THAP7 can also recruit TAF-Ibeta and silencing mediator of retinoid and thyroid receptors/nuclear hormone receptor corepressor (NCoR) proteins to promoters, and knockdown of TAF-Ibeta by small interfering RNA relieves THAP7-mediated repression, indicating that, like nuclear hormone receptors, THAP7 may represent a novel class of transcription factor that uses TAF-Ibeta as a corepressor to maintain histones in a hypoacetylated, repressed state. PMID:16195249

  16. Positive selection of mutants defective in transcriptional repression of riboflavin synthesis by iron in the flavinogenic yeast Pichia guilliermondii.

    Science.gov (United States)

    Boretsky, Yuriy R; Kapustyak, Kostyantyn Y; Fayura, Lyubov R; Stasyk, Oleh V; Stenchuk, Mykola M; Bobak, Yaroslav P; Drobot, Lyudmyla B; Sibirny, Andriy A

    2005-06-01

    It is known for many years that iron represses synthesis of riboflavin (RF) and most of RF-synthesizing enzymes in several yeast species, known as flavinogenic yeasts. However, the mechanism of such repression is not known. We have found that iron represses transcription of RIB1 and RIB7 genes coding for the first and the last enzymes of RF biosynthesis in the model flavinogenic organism Pichia guilliermondii. To decipher molecular mechanisms of iron-dependent repression, isolation and study of the regulatory mutants defective in corresponding regulation is desirable. However, no suitable methods for isolation of such mutants were previously available. We have produced a single-point transition mutation in the RIB1 gene. The corresponding rib1-86 mutant exhibits leaky phenotype and is unable to grow in iron-sufficient minimal medium without exogenous RF. However, it can grow in minimal iron-deficient medium without RF, or in iron-sufficient medium upon introduction of the previously-isolated regulatory mutation rib81, which leads to increase in RF production. Using the rib1-86 mutant as parental strain, a collection of mutants able to grow in iron-sufficient medium without exogenous RF has been isolated. The mutants appeared to be defective in regulation of RF biosynthesis and iron homeostasis and were divided into six new complementation groups. Study of one corresponding mutant, red6, showed derepression of RIB1 mRNA synthesis in iron-sufficient medium. PMID:15925311

  17. Staphylococcus aureus RNAIII coordinately represses the synthesis of virulence factors and the transcription regulator Rot by an antisense mechanism

    Science.gov (United States)

    Boisset, Sandrine; Geissmann, Thomas; Huntzinger, Eric; Fechter, Pierre; Bendridi, Nadia; Possedko, Maria; Chevalier, Clément; Helfer, Anne Catherine; Benito, Yvonne; Jacquier, Alain; Gaspin, Christine; Vandenesch, François; Romby, Pascale

    2007-01-01

    RNAIII is the intracellular effector of the quorum-sensing system in Staphylococcus aureus. It is one of the largest regulatory RNAs (514 nucleotides long) that are known to control the expression of a large number of virulence genes. Here, we show that the 3′ domain of RNAIII coordinately represses at the post-transcriptional level, the expression of mRNAs that encode a class of virulence factors that act early in the infection process. We demonstrate that the 3′ domain acts primarily as an antisense RNA and rapidly anneals to these mRNAs, forming long RNA duplexes. The interaction between RNAIII and the mRNAs results in repression of translation initiation and triggers endoribonuclease III hydrolysis. These processes are followed by rapid depletion of the mRNA pool. In addition, we show that RNAIII and its 3′ domain mediate translational repression of rot mRNA through a limited number of base pairings involving two loop–loop interactions. Since Rot is a transcriptional regulatory protein, we proposed that RNAIII indirectly acts on many downstream genes, resulting in the activation of the synthesis of several exoproteins. These data emphasize the multitude of regulatory steps affected by RNAIII and its 3′ domain in establishing a network of S. aureus virulence factors. PMID:17545468

  18. Repression of AS2 by WOX family transcription factors is required for leaf development in Medicago and Arabidopsis.

    Science.gov (United States)

    Zhang, Fei; Tadege, Million

    2015-01-01

    WOX transcription factors are key regulators of meristematic activity in plants. The Medicago WOX gene, STF, functions in maintenance of leaf marginal meristem, analogous to the function of WUS in the shoot apical meristem. Both STF and WUS directly repress AS2 expression in their respective domains. Ectopic expression of AS2 with WUS promoter leads to a narrow leaf phenotype and other phenotypes similar to the wus mutant. We also found that a wox1 prs wus triple mutant produces much narrower leaf blades than the wox1 prs double mutant, indicating that WUS genetically interacts with WOX1 and PRS in Arabidopsis leaf blade development. Our data points to a general requirement for AS2 repression in meristematic regions to allow cell proliferation. PMID:25807065

  19. Divergence of the diapause transcriptome in apple maggot flies: winter regulation and post-winter transcriptional repression.

    Science.gov (United States)

    Meyers, Peter J; Powell, Thomas H Q; Walden, Kimberly K O; Schieferecke, Adam J; Feder, Jeffrey L; Hahn, Daniel A; Robertson, Hugh M; Berlocher, Stewart H; Ragland, Gregory J

    2016-09-01

    The duration of dormancy regulates seasonal timing in many organisms and may be modulated by day length and temperature. Though photoperiodic modulation has been well studied, temperature modulation of dormancy has received less attention. Here, we leverage genetic variation in diapause in the apple maggot fly, Rhagoletis pomonella, to test whether gene expression during winter or following spring warming regulates diapause duration. We used RNAseq to compare transcript abundance during and after simulated winter between an apple-infesting population and a hawthorn-infesting population where the apple population ends pupal diapause earlier than the hawthorn-infesting population. Marked differences in transcription between the two populations during winter suggests that the 'early' apple population is developmentally advanced compared with the 'late' hawthorn population prior to spring warming, with transcripts participating in growth and developmental processes relatively up-regulated in apple pupae during the winter cold period. Thus, regulatory differences during winter ultimately drive phenological differences that manifest themselves in the following summer. Expression and polymorphism analysis identify candidate genes in the Wnt and insulin signaling pathways that contribute to population differences in seasonality. Both populations remained in diapause and displayed a pattern of up- and then down-regulation (or vice versa) of growth-related transcripts following warming, consistent with transcriptional repression. The ability to repress growth stimulated by permissive temperatures is likely critical to avoid mismatched phenology and excessive metabolic demand. Compared with diapause studies in other insects, our results suggest some overlap in candidate genes/pathways, though the timing and direction of changes in transcription are likely species specific. PMID:27312473

  20. CAR-mediated repression of Foxo1 transcriptional activity regulates the cell cycle inhibitor p21 in mouse livers

    International Nuclear Information System (INIS)

    Highlights: • CAR activation decreased the level of Foxo1 in mouse livers. • CAR activation decreased the level of p21 in mouse livers. • CAR activation inhibited Foxo1 transcriptional activity in mouse livers. - Abstract: 1,4-Bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP), an agonist of constitutive androstane receptor (CAR), is a well-known strong primary chemical mitogen for the mouse liver. Despite extensive investigation of the role of CAR in the regulation of cell proliferation, our knowledge of the intricate mediating mechanism is incomplete. In this study, we demonstrated that long-term CAR activation by TCPOBOP increased liver-to-body weight ratio and decreased tumour suppressor Foxo1 expression and transcriptional activity, which were correlated with reduced expression of genes regulated by Foxo1, including the cell-cycle inhibitor Cdkn1a(p21), and upregulation of the cell-cycle regulator Cyclin D1. Moreover, we demonstrated the negative regulatory effect of TCPOBOP-activated CAR on the association of Foxo1 with the target Foxo1 itself and Cdkn1a(p21) promoters. Thus, we identified CAR-mediated repression of cell cycle inhibitor p21, as mediated by repression of FOXO1 expression and transcriptional activity. CAR-FOXO1 cross-talk may provide new opportunities for understanding liver diseases and developing more effective therapeutic approaches to better drug treatments

  1. Chromatin Remodeling around Nucleosome-Free Regions Leads to Repression of Noncoding RNA Transcription

    OpenAIRE

    Yadon, Adam N.; Mark, Daniel; Basom, Ryan; Delrow, Jeffrey; Whitehouse, Iestyn; Tsukiyama, Toshio

    2010-01-01

    Nucleosome-free regions (NFRs) at the 5′ and 3′ ends of genes are general sites of transcription initiation for mRNA and noncoding RNA (ncRNA). The presence of NFRs within transcriptional regulatory regions and the conserved location of transcription start sites at NFRs strongly suggest that the regulation of NFRs profoundly affects transcription initiation. To date, multiple factors are known to facilitate transcription initiation by positively regulating the formation and/or size of NFRs in...

  2. Global transcriptional analysis of nitrogen fixation and ammonium repression in root-associated Pseudomonas stutzeri A1501

    Directory of Open Access Journals (Sweden)

    Lu Wei

    2010-01-01

    Full Text Available Abstract Background Biological nitrogen fixation is highly controlled at the transcriptional level by regulatory networks that respond to the availability of fixed nitrogen. In many diazotrophs, addition of excess ammonium in the growth medium results in immediate repression of nif gene transcription. Although the regulatory cascades that control the transcription of the nif genes in proteobacteria have been well investigated, there are limited data on the kinetics of ammonium-dependent repression of nitrogen fixation. Results Here we report a global transcriptional profiling analysis of nitrogen fixation and ammonium repression in Pseudomonas stutzeri A1501, a root-associated and nitrogen-fixing bacterium. A total of 166 genes, including those coding for the global nitrogen regulation (Ntr and Nif-specific regulatory proteins, were upregulated under nitrogen fixation conditions but rapidly downregulated as early as 10 min after ammonium shock. Among these nitrogen fixation-inducible genes, 95 have orthologs in each of Azoarcus sp. BH72 and Azotobacter vinelandii AvoP. In particular, a 49-kb expression island containing nif and other associated genes was markedly downregulated by ammonium shock. Further functional characterization of pnfA, a new NifA-σ54-dependent gene chromosomally linked to nifHDK, is reported. This gene encodes a protein product with an amino acid sequence similar to that of five hypothetical proteins found only in diazotrophic strains. No noticeable differences in the transcription of nifHDK were detected between the wild type strain and pnfA mutant. However, the mutant strain exhibited a significant decrease in nitrogenase activity under microaerobic conditions and lost its ability to use nitrate as a terminal electron acceptor for the support of nitrogen fixation under anaerobic conditions. Conclusions Based on our results, we conclude that transcriptional regulation of nif gene expression in A1501 is mediated by the nif

  3. Human THAP7 is a chromatin-associated, histone tail-binding protein that represses transcription via recruitment of HDAC3 and nuclear hormone receptor corepressor.

    Science.gov (United States)

    Macfarlan, Todd; Kutney, Sara; Altman, Brian; Montross, Rebecca; Yu, Jiujiu; Chakravarti, Debabrata

    2005-02-25

    The identities of signal transducer proteins that integrate histone hypoacetylation and transcriptional repression are largely unknown. Here we demonstrate that THAP7, an uncharacterized member of the recently identified THAP (Thanatos-associated protein) family of proteins, is ubiquitously expressed, associates with chromatin, and represses transcription. THAP7 binds preferentially to hypoacetylated (un-, mono-, and diacetylated) histone H4 tails in vitro via its C-terminal 77 amino acids. Deletion of this domain, or treatment of cells with the histone deacetylase inhibitor TSA, which leads to histone hyperacetylation, partially disrupts THAP7/chromatin association in living cells. THAP7 coimmunoprecipitates with histone deacetylase 3 (HDAC3) and the nuclear hormone receptor corepressor (NCoR) and represses transcription as a Gal4 fusion protein. Chromatin immunoprecipitation assays demonstrate that these corepressors are recruited to promoters in a THAP7 dependent manner and promote histone H3 hypoacetylation. The conserved THAP domain is a key determinant for full HDAC3 association in vitro, and both the THAP domain and the histone interaction domain are important for the repressive properties of THAP7. Full repression mediated by THAP7 is also dependent on NCoR expression. We hypothesize that THAP7 is a dual function repressor protein that actively targets deacetylation of histone H3 necessary to establish transcriptional repression and functions as a signal transducer of the repressive mark of hypoacetylated histone H4. This is the first demonstration of the transcriptional regulatory properties of a human THAP domain protein, and a critical identification of a potential transducer of the repressive signal of hypoacetylated histone H4 in higher eukaryotes. PMID:15561719

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

    DEFF Research Database (Denmark)

    Herranz, Nicolás; Pasini, Diego; Díaz, Víctor M; Francí, Clara; Gutierrez, Arantxa; Dave, Natàlia; Escrivà, Maria; Hernandez-Muñoz, Inma; Di Croce, Luciano; Helin, Kristian; García de Herreros, Antonio; Peiró, Sandra

    2008-01-01

    -regulate CDH1 and partially de-represses CDH1. Chromatin immunoprecipitation assays demonstrated that Snail1 increases the binding of Suz12 to CDH1 promoter and the tri-methylation of lysine 27 in the histone 3. Moreover, Snail1 interacts with Suz12 and Ezh2 as shown by coimmunoprecipitation experiments. In...

  5. CDK11p58 represses vitamin D receptor-mediated transcriptional activation through promoting its ubiquitin-proteasome degradation

    International Nuclear Information System (INIS)

    Vitamin D receptor (VDR) is a member of the nuclear receptor superfamily and regulates transcription of target genes. In this study, we identified CDK11p58 as a novel protein involved in the regulation of VDR. CDK11p58, a member of the large family of p34cdc2-related kinases, is associated with cell cycle progression, tumorigenesis, and apoptotic signaling. Our study demonstrated that CDK11p58 interacted with VDR and repressed VDR-dependent transcriptional activation. Furthermore, overexpression of CDK11p58 decreased the stability of VDR through promoting its ubiquitin-proteasome-mediated degradation. Taken together, these results suggest that CDK11p58 is involved in the negative regulation of VDR.

  6. CDK11{sup p58} represses vitamin D receptor-mediated transcriptional activation through promoting its ubiquitin-proteasome degradation

    Energy Technology Data Exchange (ETDEWEB)

    Chi, Yayun; Hong, Yi; Zong, Hongliang; Wang, Yanlin; Zou, Weiying; Yang, Junwu; Kong, Xiangfei; Yun, Xiaojing [Gene Research Center, Shanghai Medical College and Institutes of Biomedical, Shanghai 200032 (China); Gu, Jianxin, E-mail: jxgu@shmu.edu.cn [Gene Research Center, Shanghai Medical College and Institutes of Biomedical, Shanghai 200032 (China)

    2009-08-28

    Vitamin D receptor (VDR) is a member of the nuclear receptor superfamily and regulates transcription of target genes. In this study, we identified CDK11{sup p58} as a novel protein involved in the regulation of VDR. CDK11{sup p58}, a member of the large family of p34cdc2-related kinases, is associated with cell cycle progression, tumorigenesis, and apoptotic signaling. Our study demonstrated that CDK11{sup p58} interacted with VDR and repressed VDR-dependent transcriptional activation. Furthermore, overexpression of CDK11{sup p58} decreased the stability of VDR through promoting its ubiquitin-proteasome-mediated degradation. Taken together, these results suggest that CDK11{sup p58} is involved in the negative regulation of VDR.

  7. WT1-mediated repression of the proapoptotic transcription factor ZNF224 is triggered by the BCR-ABL oncogene

    Science.gov (United States)

    Montano, Giorgia; Vidovic, Karina; Palladino, Chiara; Cesaro, Elena; Sodaro, Gaetano; Quintarelli, Concetta; De Angelis, Biagio; Errichiello, Santa; Pane, Fabrizio; Izzo, Paola; Grosso, Michela; Gullberg, Urban; Costanzo, Paola

    2015-01-01

    The Kruppel-like protein ZNF224 is a co-factor of the Wilms’ tumor 1 protein, WT1. We have previously shown that ZNF224 exerts a specific proapoptotic role in chronic myelogenous leukemia (CML) K562 cells and contributes to cytosine arabinoside-induced apoptosis, by modulating WT1-dependent transcription of apoptotic genes. Here we demonstrate that ZNF224 gene expression is down-regulated both in BCR-ABL positive cell lines and in primary CML samples and is restored after imatinib and second generation tyrosine kinase inhibitors treatment. We also show that WT1, whose expression is positively regulated by BCR-ABL, represses transcription of the ZNF224 gene. Finally, we report that ZNF224 is significantly down-regulated in patients with BCR-ABL positive chronic phase-CML showing poor response or resistance to imatinib treatment as compared to high-responder patients. Taken as a whole, our data disclose a novel pathway activated by BCR-ABL that leads to inhibition of apoptosis through the ZNF224 repression. ZNF224 could thus represent a novel promising therapeutic target in CML. PMID:26320177

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

    International Nuclear Information System (INIS)

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

  9. WNT signaling : activation, repression and fine-tuning of TCF transcription factors

    OpenAIRE

    Brantjes, H.M.

    2003-01-01

    In the absence of a Wnt signal ß-catenin is phosphorylated by GSK3-ß, in a complex also containing Axin and APC. Upon phosphorylation, ß-catenin is primed for ubiquitination and subsequent degradation by the proteasome. In the nucleus, Tcf proteins bind Groucho family members and repress target genes. When a Wnt protein reaches the cell, it associates with the transmembrane receptors Frizzled and LRP. The destruction complex of GSK3-?, APC and Axin is subsequently inactivated via Dishevelled,...

  10. Histone acetyltransferase (HAT) activity of p300 modulates human T lymphotropic virus type 1 p30II-mediated repression of LTR transcriptional activity

    International Nuclear Information System (INIS)

    Human T-lymphotropic virus type-1 (HTLV-1) is a deltaretrovirus that causes adult T cell leukemia/lymphoma, and is implicated in a variety of lymphocyte-mediated inflammatory disorders. HTLV-1 provirus has regulatory and accessory genes in four pX open reading frames. HTLV-1 pX ORF-II encodes two proteins, p13II and p30II, which are incompletely defined in virus replication or pathogenesis. We have demonstrated that pX ORF-II mutations block virus replication in vivo and that ORF-II encoded p30II, a nuclear-localizing protein that binds with CREB-binding protein (CBP)/p300, represses CREB and Tax responsive element (TRE)-mediated transcription. Herein, we have identified p30II motifs important for p300 binding and in regulating TRE-mediated transcription in the absence and presence of HTLV-1 provirus. Within amino acids 100-179 of p30II, a region important for repression of LTR-mediated transcription, we identified a single lysine residue at amino acid 106 (K3) that significantly modulates the ability of p30II to repress TRE-mediated transcription. Exogenous p300, in a dose-responsive manner, reverses p30II-dependent repression of TRE-mediated transcription, in the absence or presence of the provirus, In contrast to wild type p300, p300 HAT mutants (defective in histone acetyltransferase activity) only partially rescued p30II-mediated LTR repression. Deacetylation by histone deacetylase-1 (HDAC-1) enhanced p30II-mediated LTR repression, while inhibition of deacetylation by trichostatin A decreases p30II-mediated LTR repression. Collectively, our data indicate that HTLV-1 p30II modulates viral gene expression in a cooperative manner with p300-mediated acetylation

  11. Cold shock domain proteins repress transcription from the GM-CSF promoter.

    OpenAIRE

    Coles, L S; P. Diamond; Occhiodoro, F; Vadas, M A; Shannon, M F

    1996-01-01

    The human granulocyte-macrophage colony stimulating factor (GM-CSF) gene promoter binds a sequence-specific single-strand DNA binding protein termed NF-GMb. We previously demonstrated that the NF-GMb binding sites were required for repression of tumor necrosis factor-alpha (TNF-alpha) induction of the proximal GM-CSF promoter sequences in fibroblasts. We now describe the isolation of two different cDNA clones that encode cold shock domain (CSD) proteins with NF-GMb binding characteristics. On...

  12. Interaction of the phospholipid scramblase 1 with HIV-1 Tat results in the repression of Tat-dependent transcription

    International Nuclear Information System (INIS)

    Highlights: •PLSCR1 specifically interacted with HIV-1 Tat in vitro and in vivo. •PLSCR1 repressed Tat-dependent transactivation of the HIV-1 LTR. •Suppression of PLSCR1 expression enhanced the levels of HIV-1 transcripts. •PLSCR1 reduced the nuclear localization of Tat. -- Abstract: Human phospholipid scramblase 1 (PLSCR1) is an interferon (IFN)-stimulated gene and possesses an IFN-mediated antiviral function. We show here that PLSCR1 directly interacts with human immunodeficiency virus type-1 (HIV-1) Tat. This interaction occurs both in vitro and in vivo through amino acids 160–250 of PLSCR1. Overexpression of PLSCR1 efficiently represses the Tat-dependent transactivation of the HIV-1 long terminal repeat (LTR) and reduces the nuclear translocation of Tat. In addition, shRNA-mediated suppression of endogenous PLSCR1 expression enhances the levels of gag mRNA in an HIV-1-infected T-cell line. These findings indicate that PLSCR1 negatively regulates the Tat-dependent transactivation of the HIV-1 LTR during HIV-1 infection

  13. Interaction of the phospholipid scramblase 1 with HIV-1 Tat results in the repression of Tat-dependent transcription

    Energy Technology Data Exchange (ETDEWEB)

    Kusano, Shuichi, E-mail: skusano@m2.kufm.kagoshima-u.ac.jp; Eizuru, Yoshito

    2013-04-19

    Highlights: •PLSCR1 specifically interacted with HIV-1 Tat in vitro and in vivo. •PLSCR1 repressed Tat-dependent transactivation of the HIV-1 LTR. •Suppression of PLSCR1 expression enhanced the levels of HIV-1 transcripts. •PLSCR1 reduced the nuclear localization of Tat. -- Abstract: Human phospholipid scramblase 1 (PLSCR1) is an interferon (IFN)-stimulated gene and possesses an IFN-mediated antiviral function. We show here that PLSCR1 directly interacts with human immunodeficiency virus type-1 (HIV-1) Tat. This interaction occurs both in vitro and in vivo through amino acids 160–250 of PLSCR1. Overexpression of PLSCR1 efficiently represses the Tat-dependent transactivation of the HIV-1 long terminal repeat (LTR) and reduces the nuclear translocation of Tat. In addition, shRNA-mediated suppression of endogenous PLSCR1 expression enhances the levels of gag mRNA in an HIV-1-infected T-cell line. These findings indicate that PLSCR1 negatively regulates the Tat-dependent transactivation of the HIV-1 LTR during HIV-1 infection.

  14. CRISPathBrick: Modular Combinatorial Assembly of Type II-A CRISPR Arrays for dCas9-Mediated Multiplex Transcriptional Repression in E. coli.

    Science.gov (United States)

    Cress, Brady F; Toparlak, Ö Duhan; Guleria, Sanjay; Lebovich, Matthew; Stieglitz, Jessica T; Englaender, Jacob A; Jones, J Andrew; Linhardt, Robert J; Koffas, Mattheos A G

    2015-09-18

    Programmable control over an addressable global regulator would enable simultaneous repression of multiple genes and would have tremendous impact on the field of synthetic biology. It has recently been established that CRISPR/Cas systems can be engineered to repress gene transcription at nearly any desired location in a sequence-specific manner, but there remain only a handful of applications described to date. In this work, we report development of a vector possessing a CRISPathBrick feature, enabling rapid modular assembly of natural type II-A CRISPR arrays capable of simultaneously repressing multiple target genes in Escherichia coli. Iterative incorporation of spacers into this CRISPathBrick feature facilitates the combinatorial construction of arrays, from a small number of DNA parts, which can be utilized to generate a suite of complex phenotypes corresponding to an encoded genetic program. We show that CRISPathBrick can be used to tune expression of plasmid-based genes and repress chromosomal targets in probiotic, virulent, and commonly engineered E. coli strains. Furthermore, we describe development of pCRISPReporter, a fluorescent reporter plasmid utilized to quantify dCas9-mediated repression from endogenous promoters. Finally, we demonstrate that dCas9-mediated repression can be harnessed to assess the effect of downregulating both novel and computationally predicted metabolic engineering targets, improving the yield of a heterologous phytochemical through repression of endogenous genes. These tools provide a platform for rapid evaluation of multiplex metabolic engineering interventions. PMID:25822415

  15. Dual role of Med12 in PRC1-dependent gene repression and ncRNA-mediated transcriptional activation.

    Science.gov (United States)

    Papadopoulou, Thaleia; Kaymak, Aysegül; Sayols, Sergi; Richly, Holger

    2016-06-01

    Mediator is considered an enhancer of RNA-Polymerase II dependent transcription but its function and regulation in pluripotent mouse embryonic stem cells (mESCs) remains unresolved. One means of controlling the function of Mediator is provided by the binding of the Cdk8 module (Med12, Cdk8, Ccnc and Med13) to the core Mediator. Here we report that Med12 operates together with PRC1 to silence key developmental genes in pluripotency. At the molecular level, while PRC1 represses genes it is also required to assemble ncRNA containing Med12-Mediator complexes. In the course of cellular differentiation the H2A ubiquitin binding protein Zrf1 abrogates PRC1-Med12 binding and facilitates the association of Cdk8 with Mediator. This remodeling of Mediator-associated protein complexes converts Mediator from a transcriptional repressor to a transcriptional enhancer, which then mediates ncRNA-dependent activation of Polycomb target genes. Altogether, our data reveal how the interplay of PRC1, ncRNA and Mediator complexes controls pluripotency and cellular differentiation. PMID:27096886

  16. Phosphorylation of the leukemic oncoprotein EVI1 on serine 196 modulates DNA binding, transcriptional repression and transforming ability.

    Directory of Open Access Journals (Sweden)

    Daniel J White

    Full Text Available The EVI1 (ecotropic viral integration site 1 gene at 3q26 codes for a transcriptional regulator with an essential role in haematopoiesis. Overexpression of EVI1 in acute myeloid leukaemia (AML is frequently associated with 3q26 rearrangements and confers extremely poor prognosis. EVI1 mediates transcriptional regulation, signalling, and epigenetic modifications by interacting with DNA, proteins and protein complexes. To explore to what extent protein phosphorylation impacts on EVI1 functions, we analysed endogenous EVI1 protein from a high EVI1 expressing Fanconi anaemia (FA derived AML cell line. Mass spectrometric analysis of immunoprecipitated EVI1 revealed phosphorylation at serine 196 (S196 in the sixth zinc finger of the N-terminal zinc finger domain. Mutated EVI1 with an aspartate substitution at serine 196 (S196D, which mimics serine phosphorylation of this site, exhibited reduced DNA-binding and transcriptional repression from a gene promotor selectively targeted by the N-terminal zinc finger domain. Forced expression of the S196D mutant significantly reduced EVI1 mediated transformation of Rat1 fibroblasts. While EVI1-mediated serial replating of murine haematopoietic progenitors was maintained by EVI1-S196D, this was associated with significantly higher Evi1-trancript levels compared with WT-EVI1 or EVI1-S196A, mimicking S196 non-phosphorylated EVI1. These data suggest that EVI1 function is modulated by phosphorylation of the first zinc finger domain.

  17. The putrescine biosynthesis pathway in Lactococcus lactis is transcriptionally regulated by carbon catabolic repression, mediated by CcpA.

    Science.gov (United States)

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

    2013-07-01

    Lactococcus lactis is the lactic acid bacterium most widely used by the dairy industry as a starter for the manufacture of fermented products such as cheese and buttermilk. However, some strains produce putrescine from agmatine via the agmatine deiminase (AGDI) pathway. The proteins involved in this pathway, including those necessary for agmatine uptake and conversion into putrescine, are encoded by the aguB, aguD, aguA and aguC genes, which together form an operon. This paper reports the mechanism of regulation of putrescine biosynthesis in L. lactis. It is shown that the aguBDAC operon, which contains a cre site at the promoter of aguB (the first gene of the operon), is transcriptionally regulated by carbon catabolic repression (CCR) mediated by the catabolite control protein CcpA. PMID:23688550

  18. The Unicellular Ancestry of Groucho-Mediated Repression and the Origins of Metazoan Transcription Factors.

    Science.gov (United States)

    Copley, Richard R

    2016-01-01

    Groucho is a co-repressor that interacts with many transcription factors playing a crucial role in animal development. The evolutionary origins of Groucho are not clear. It is generally regarded as being a distinct animal-specific protein, although with similarities to the yeast Tup-like proteins. Here, it is shown that Groucho has true orthologs in unicellular relatives of animals. Based on their phylogenetic distribution, and an analysis of ligand-binding residues, these genes are unlikely to be orthologs of the fungal Tup-like genes. By identifying conserved candidate Groucho interaction motifs (GIMs) in nonmetazoan transcription factors, it is demonstrated that the details of molecular interactions between Groucho and transcription factors are likely to have been established prior to the origin of animals, but that the association of GIMs with many transcription factor types can be regarded as a metazoan innovation. PMID:27189982

  19. A gene-rich, transcriptionally active environment and the pre-deposition of repressive marks are predictive of susceptibility to KRAB/KAP1-mediated silencing

    Directory of Open Access Journals (Sweden)

    Zangger Nadine

    2011-07-01

    Full Text Available Abstract Background KRAB-ZFPs (Krüppel-associated box domain-zinc finger proteins are vertebrate-restricted transcriptional repressors encoded in the hundreds by the mouse and human genomes. They act via an essential cofactor, KAP1, which recruits effectors responsible for the formation of facultative heterochromatin. We have recently shown that KRAB/KAP1 can mediate long-range transcriptional repression through heterochromatin spreading, but also demonstrated that this process is at times countered by endogenous influences. Method To investigate this issue further we used an ectopic KRAB-based repressor. This system allowed us to tether KRAB/KAP1 to hundreds of euchromatic sites within genes, and to record its impact on gene expression. We then correlated this KRAB/KAP1-mediated transcriptional effect to pre-existing genomic and chromatin structures to identify specific characteristics making a gene susceptible to repression. Results We found that genes that were susceptible to KRAB/KAP1-mediated silencing carried higher levels of repressive histone marks both at the promoter and over the transcribed region than genes that were insensitive. In parallel, we found a high enrichment in euchromatic marks within both the close and more distant environment of these genes. Conclusion Together, these data indicate that high levels of gene activity in the genomic environment and the pre-deposition of repressive histone marks within a gene increase its susceptibility to KRAB/KAP1-mediated repression.

  20. Brd4-Independent Transcriptional Repression Function of the Papillomavirus E2 Proteins▿

    OpenAIRE

    Schweiger, Michal-Ruth; Ottinger, Matthias; You, Jianxin; Howley, Peter M.

    2007-01-01

    The papillomavirus E2 protein is a critical viral regulatory protein with transcription, DNA replication, and genome maintenance functions. We have previously identified the cellular bromodomain protein Brd4 as a major E2-interacting protein and established that it participates in tethering bovine papillomavirus type 1 E2 and viral genomes to host cell mitotic chromosomes. We have also shown that Brd4 mediates E2-dependent transcriptional activation, which is strongly inhibited by the disrupt...

  1. Role of the hinge region of glucocorticoid receptor for HEXIM1-mediated transcriptional repression

    International Nuclear Information System (INIS)

    We previously reported that HEXIM1 (hexamethylene bisacetamide-inducible protein 1), which suppresses transcription elongation via sequestration of positive transcription elongation factor b (P-TEFb) using 7SK RNA as a scaffold, directly associates with glucocorticoid receptor (GR) to suppress glucocorticoid-inducible gene activation. Here, we revealed that the hinge region of GR is essential for its interaction with HEXIM1, and that oxosteroid receptors including GR show sequence homology in their hinge region and interact with HEXIM1, whereas the other members of nuclear receptors do not. We also showed that HEXIM1 suppresses GR-mediated transcription in two ways: sequestration of P-TEFb by HEXIM1 and direct interaction between GR and HEXIM1. In contrast, peroxisome proliferator-activated receptor γ-dependent gene expression is negatively modulated by HEXIM1 solely via sequestration of P-TEFb. We, therefore, conclude that HEXIM1 may act as a gene-selective transcriptional regulator via direct interaction with certain transcriptional regulators including GR and contribute to fine-tuning of, for example, glucocorticoid-mediated biological responses

  2. Mechanisms of matrix metalloproteinase-2 (mmp-2 transcriptional repression by progesterone in jar choriocarcinoma cells

    Directory of Open Access Journals (Sweden)

    Shalev Eliezer

    2009-05-01

    Full Text Available Abstract Background Although the MMP-2 promoter lacks a canonical progesterone response element (PRE, the hormone inhibits MMP-2 expression and is part of treatment protocols in gynecological invasive pathologies, including endometriosis and endometrial hyperplasia. This study aimed to explore the mechanism by which progesterone inhibits MMP-2 expression. Methods The effect of progesterone on MMP-2 expression in the JAR human choriocarcinoma cell line was analyzed by gelatin zymography. MMP-2 transcript expression was studied using Northern blot and semi-quantitative RT-PCR. Rat promoter deletion analysis, electrophoretic mobility shift and chromatin immuno-precipitation assays were performed in order to locate the DNA binding site and the transcription factors involved in MMP-2 regulation. Results Progesterone significantly decreased secretion of pro-MMP-2 and MMP-2 transcript expression level in a dose-dependent manner. Progesterone (1 microM significantly decreased both human and rat MMP-2 promoter activity (80.1% +/- 0.3 and 81.3% +/- 0.23, respectively. Progesterone acts through the SP1 family transcription factors-binding site, located between -1433 and -1342 bp region from the transcriptional start site of the rat MMP-2 promoter, which are present in the orthologous human MMP-2 promoter. Progesterone receptor (PR, SP2, SP3 and SP4 proteins are constitutively bound to this consensus sequence. Conclusion Progesterone reducesPR and SP4 binding to the MMP-2 promoter, thereby suppressing transcription. Progesterone also promotes SP4 degradation. These novel mechanisms of MMP-2 regulation by progesterone provide the biological rationale for the use of progesterone in clinical settings associated with increased MMP-2 expression.

  3. H-NS mediated repression of CRISPR-based immunity in Escherichia coli K12 can be relieved by the transcription activator LeuO

    OpenAIRE

    Westra, Edze Rients; Pul, Ümit; Heidrich, Nadja; Jore, Matthijs Miklas; Lundgren, Magnus; Stratmann, Thomas; Wurm, Reinhild; Raine, Amanda; Mescher, Melina; Heereveld, Luc Van; Mastop, Marieke; Wagner, E. Gerhart H.; Schnetz, Karin; van der Oost, John; Wagner, Rolf

    2010-01-01

    Abstract The recently discovered prokaryotic CRISPR/Cas defense system provides immunity against viral infections and plasmid conjugation. It has been demonstrated that in Escherichia coli transcription of the Cascade genes (casABCDE) and to some extent the CRISPR array, is repressed by heat-stable nucleoid-structuring (H-NS) protein, a global transcriptional repressor. Here we elaborate on the control of the E. coli CRISPR/Cas system, and study the effect on CRISPR-based anti-vira...

  4. CsrA Participates in a PNPase Autoregulatory Mechanism by Selectively Repressing Translation of pnp Transcripts That Have Been Previously Processed by RNase III and PNPase

    OpenAIRE

    Park, Hongmarn; Yakhnin, Helen; Connolly, Michael; Romeo, Tony; Babitzke, Paul

    2015-01-01

    Csr is a conserved global regulatory system that represses or activates gene expression posttranscriptionally. CsrA of Escherichia coli is a homodimeric RNA binding protein that regulates transcription elongation, translation initiation, and mRNA stability by binding to the 5′ untranslated leader or initial coding sequence of target transcripts. pnp mRNA, encoding the 3′ to 5′ exoribonuclease polynucleotide phosphorylase (PNPase), was previously identified as a CsrA target by transcriptome se...

  5. Identification of a Boundary Domain Adjacent to the Potent Human Cytomegalovirus Enhancer That Represses Transcription of the Divergent UL127 Promoter†

    OpenAIRE

    Angulo, Ana; Kerry, David; Huang, Huang; Borst, Eva-Maria; Razinsky, Alison; Wu, Jun; Hobom, Urs; Messerle, Martin; Ghazal, Peter

    2000-01-01

    Transcriptional repression within a complex modular promoter may play a key role in determining the action of enhancer elements. In human cytomegalovirus, the major immediate-early promoter (MIEP) locus contains a highly potent and complex modular enhancer. Evidence is presented suggesting that sequences of the MIEP between nucleotide positions −556 and −673 function to prevent transcription activation by enhancer elements from the UL127 open reading frame divergent promoter. Transient transf...

  6. Identification of a boundary domain adjacent to the potent human cytomegalovirus enhancer that represses transcription of the divergent UL127 promoter

    OpenAIRE

    Angulo, A; Kerry, D; Huang, H.; Borst, E M; Razinsky, A; Wu, J.; Hobom, U; Messerle, M.; Ghazal, P

    2000-01-01

    Transcriptional repression within a complex modular promoter may play a key role in determining the action of enhancer elements. In human cytomegalovirus, the major immediate-early promoter (MIEP) locus contains a highly potent and complex modular enhancer. Evidence is presented suggesting that sequences of the MIEP between nucleotide positions -556 and -673 function to prevent transcription activation by enhancer elements from the UL127 open reading frame divergent promoter. Transient transf...

  7. H-NS-mediated repression of CRISPR-based immunity in Escherichia coli K12 can be relieved by the transcription activator LeuO

    NARCIS (Netherlands)

    Westra, E.R.; Pul, Ü.; Heidrich, N.; Jore, M.M.; Lundgren, N.M.J.; Stratmann, T.; Wurm, R.; Raine, A.; Mescher, M.; Heereveld, van L.; Mastop, M.; Wagner, E.G.H.; Schnetz, K.; Oost, van der J.; Wagner, R.; Brouns, S.J.J.

    2010-01-01

    The recently discovered prokaryotic CRISPR/Cas defence system provides immunity against viral infections and plasmid conjugation. It has been demonstrated that in Escherichia coli transcription of the Cascade genes (casABCDE) and to some extent the CRISPR array is repressed by heat-stable nucleoid-s

  8. Changing a conserved amino acid in R2R3-MYB transcription repressors results in cytoplasmic accumulation and abolishes their repressive activity in Arabidopsis.

    Science.gov (United States)

    Zhou, Meiliang; Sun, Zhanmin; Wang, Chenglong; Zhang, Xinquan; Tang, Yixiong; Zhu, Xuemei; Shao, Jirong; Wu, Yanmin

    2015-10-01

    Sub-group 4 R2R3-type MYB transcription factors, including MYB3, MYB4, MYB7 and MYB32, act as repressors in phenylpropanoid metabolism. These proteins contain the conserved MYB domain and the ethylene-responsive element binding factor-associated amphiphilic repression (EAR) repression domain. Additionally, MYB4, MYB7 and MYB32 possess a putative zinc-finger domain and a conserved GY/FDFLGL motif in their C-termini. The protein 'sensitive to ABA and drought 2' (SAD2) recognizes the nuclear pore complex, which then transports the SAD2-MYB4 complex into the nucleus. Here, we show that the conserved GY/FDFLGL motif contributes to the interaction between MYB factors and SAD2. The Asp → Asn mutation in the GY/FDFLGL motif abolishes the interaction between MYB transcription factors and SAD2, and therefore they cannot be transported into the nucleus and cannot repress their target genes. We found that MYB4(D261N) loses the capacity to repress expression of the cinnamate 4-hydroxylase (C4H) gene and biosynthesis of sinapoyl malate. Our results indicate conservation among MYB transcription factors in terms of their interaction with SAD2. Therefore, the Asp → Asn mutation may be used to engineer transcription factors. PMID:26332741

  9. Transcriptional repression of the yeast CHA1 gene requires the chromatin-remodeling complex RSC

    DEFF Research Database (Denmark)

    Moreira, José Manuel Alfonso; Holmberg, S

    1999-01-01

    absence of Sth1p/Nps1p (a homolog of Swi2p/Snf2p) or of Swh3p (a homolog of Swi3p), expression of CHA1 in non-induced cells is increased to a level comparable with that of fully induced cells. Furthermore, in non-induced cells depleted for Sth1p/Nps1p or Swh3p, a nucleosome positioned over the TATA box of......In eukaryotes, DNA is packaged into chromatin, a compact structure that must be disrupted when genes are transcribed by RNA polymerase II. For transcription to take place, chromatin is remodeled via nucleosome disruption or displacement, a fundamental transcriptional regulatory mechanism in...

  10. A metabolic phenotype in sarcoma? Repression of skeletal muscle transcription factor mondo A (Mlx- Interacting Protein)

    OpenAIRE

    Bishop, Emily; Yusuf, Alex; Stephenson, John; Airley, Rachel

    2013-01-01

    MondoA (MLX-interacting protein) is a bHLH transcription factor primarily located in skeletal muscle which drives glucose-dependent pathways such as glycolysis and the expression of TXNIP (thioredoxin-interacting protein). A Mondo-A/TXNIP feedback pathway has been defined previously which is believed to regulate the uptake of glucose by tumours in response to increased glycolysis and production of lactate1. The aim of this study was to profile MondoA protein expression...

  11. CCAAT displacement protein/cut homolog recruits G9a histone lysine methyltransferase to repress transcription

    OpenAIRE

    Nishio, Hitomi; Walsh, Martin J.

    2004-01-01

    CCAAT displacement protein/cut homolog (CDP/cut) is a highly conserved homeodomain protein that contains three cut repeat sequences. CDP/cut is a transcriptional factor for many diverse cellular and viral genes that are involved in most cellular processes, including differentiation, development, and proliferation. Here, we report that CDP/cut interacts with a histone lysine methyltransferase (HKMT), G9a, in vivo and in vitro. The deletion of the cut repeats within CDP/cut abrogates the intera...

  12. Transcriptional repression of the M channel subunit Kv7.2 in chronic nerve injury.

    Science.gov (United States)

    Rose, Kirstin; Ooi, Lezanne; Dalle, Carine; Robertson, Brian; Wood, Ian C; Gamper, Nikita

    2011-04-01

    Neuropathic pain is a severe health problem for which there is a lack of effective therapy. A frequent underlying condition of neuropathic pain is a sustained overexcitability of pain-sensing (nociceptive) sensory fibres. Therefore, the identification of mechanisms for such abnormal neuronal excitability is of utmost importance for understanding neuropathic pain. Despite much effort, an inclusive model explaining peripheral overexcitability is missing. We investigated transcriptional regulation of the Kcnq2 gene, which encodes the Kv7.2 subunit of membrane potential-stabilizing M channel, in peripheral sensory neurons in a model of neuropathic pain-partial sciatic nerve ligation (PSNL). We show that Kcnq2 is the major Kcnq gene transcript in dorsal root ganglion (DRG); immunostaining and patch-clamp recordings from acute ganglionic slices verified functional expression of Kv7.2 in small-diameter nociceptive DRG neurons. Neuropathic injury induced substantial downregulation of Kv7.2 expression. Levels of repressor element 1-silencing transcription factor (REST), which is known to suppress Kcnq2 expression, were upregulated in response to neuropathic injury identifying the likely mechanism of Kcnq2 regulation. Behavioural experiments demonstrated that neuropathic hyperalgesia following PSNL developed faster than the downregulation of Kcnq2 expression could be detected, suggesting that this transcriptional mechanism may contribute to the maintenance rather than the initiation of neuropathic pain. Importantly, the decrease in the peripheral M channel abundance could be functionally compensated by peripherally applied M channel opener flupirtine, which alleviated neuropathic hyperalgesia. Our work suggests a novel mechanism for neuropathic overexcitability and brings focus on M channels and REST as peripheral targets for the treatment of neuropathic pain. PMID:21345591

  13. Transcriptional repression of the M channel subunit Kv7.2 in chronic nerve injury

    OpenAIRE

    Rose, Kirstin; Ooi, Lezanne; Dalle, Carine; Robertson, Brian; Wood, Ian C.; Gamper, Nikita

    2011-01-01

    Neuropathic pain is a severe health problem for which there is a lack of effective therapy. A frequent underlying condition of neuropathic pain is a sustained overexcitability of pain-sensing (nociceptive) sensory fibres. Therefore, the identification of mechanisms for such abnormal neuronal excitability is of utmost importance for understanding neuropathic pain. Despite much effort, an inclusive model explaining peripheral overexcitability is missing. We investigated transcriptional regulati...

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

    Directory of Open Access Journals (Sweden)

    Huafang Ouyang

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

  15. Pokemon (FBI-1) interacts with Smad4 to repress TGF-β-induced transcriptional responses.

    Science.gov (United States)

    Yang, Yutao; Cui, Jiajun; Xue, Feng; Zhang, Chuanfu; Mei, Zhu; Wang, Yue; Bi, Mingjun; Shan, Dapeng; Meredith, Alex; Li, Hui; Xu, Zhi-Qing David

    2015-03-01

    Pokemon, an important proto-oncoprotein, is a transcriptional repressor that belongs to the POK (POZ and Krüppel) family. Smad4, a key component of TGF-β pathway, plays an essential role in TGF-β-induced transcriptional responses. In this study, we show that Pokemon can interact directly with Smad4 both in vitro and in vivo. Overexpression of Pokemon decreases TGF-β-induced transcriptional activities, whereas knockdown of Pokemon increases these activities. Interestingly, Pokemon does not affect activation of Smad2/3, formation of Smads complex, or DNA binding activity of Smad4. TGF-β1 treatment increases the interaction between Pokemon and Smad4, and also enhances the recruitment of Pokemon to Smad4-DNA complex. In addition, we also find that Pokemon recruits HDAC1 to Smad4 complex but decreases the interaction between Smad4 and p300/CBP. Taken together, all these data suggest that Pokemon is a new partner of Smad4 and plays a negative role in TGF-β pathway. PMID:25514493

  16. Analysis of the Aspergillus nidulans thaumatin-like cetA gene and evidence for transcriptional repression of pyr4 expression in the cetA-disrupted strain.

    Science.gov (United States)

    Greenstein, Shulamit; Shadkchan, Yona; Jadoun, Jeries; Sharon, Chaim; Markovich, Sarit; Osherov, Nir

    2006-01-01

    The asexual spore or conidium plays a critical role in the life cycle of many filamentous fungi. However, the process of conidial germination remains surprisingly obscure. To better understand this process at the molecular level we characterized the Aspergillus nidulans cetA gene which is uniquely transcribed in conidiating cultures and whose transcript is significantly enriched in mature conidia. CetA is a member of a novel family of fungal genes of unknown function with homology to plant thaumatin-like (PR-5) defense proteins. We demonstrate by Northern analysis that cetA is a glucose-repressible gene. Transcriptional repression is dependent on the presence of protein kinase A. Western analysis indicates that the CETA protein is absent from conidia but is highly expressed during the first 6h of germination and is secreted into the medium. Disruption of the cetA gene seemingly results in delayed germination, slow growth, abnormal hyphal branching, and cell-wall defects. However, further analysis shows that the mutant phenotype is the result of glucose-dependent transcriptional repression of the pyr4 selectable marker used to disrupt the cetA gene. This is the first time that repression of a selectable marker ("position effect") has been reported in A. nidulans, a finding that may well be of significance in the analysis and interpretation of mutant phenotypes in this organism. PMID:16376592

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-11-16

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

  18. A Response Regulator That Represses Transcription of Several Virulence Operons in the Group A Streptococcus

    OpenAIRE

    Federle, Michael J.; McIver, Kevin S.; Scott, June R.

    1999-01-01

    A search for homologs of the Bacillus subtilis PhoP response regulator in the group A streptococcus (GAS) genome revealed three good candidates. Inactivation of one of these, recently identified as csrR (J. C. Levin and M. R. Wessels, Mol. Microbiol. 30:209–219, 1998), caused the strain to produce mucoid colonies and to increase transcription of hasA, the first gene in the operon for capsule synthesis. We report here that a nonpolar insertion in this gene also increased ...

  19. Therapeutic fetal-globin inducers reduce transcriptional repression in hemoglobinopathy erythroid progenitors through distinct mechanisms.

    Science.gov (United States)

    Dai, Yan; Sangerman, Jose; Luo, Hong Yuan; Fucharoen, Suthat; Chui, David H K; Faller, Douglas V; Perrine, Susan P

    2016-01-01

    Pharmacologic augmentation of γ-globin expression sufficient to reduce anemia and clinical severity in patients with diverse hemoglobinopathies has been challenging. In studies here, representative molecules from four chemical classes, representing several distinct primary mechanisms of action, were investigated for effects on γ-globin transcriptional repressors, including components of the NuRD complex (LSD1 and HDACs 2-3), and the downstream repressor BCL11A, in erythroid progenitors from hemoglobinopathy patients. Two HDAC inhibitors (MS-275 and SB939), a short-chain fatty acid derivative (sodium dimethylbutyrate [SDMB]), and an agent identified in high-throughput screening, Benserazide, were studied. These therapeutics induced γ-globin mRNA in progenitors above same subject controls up to 20-fold, and increased F-reticulocytes up to 20%. Cellular protein levels of BCL11A, LSD-1, and KLF1 were suppressed by the compounds. Chromatin immunoprecipitation assays demonstrated a 3.6-fold reduction in LSD1 and HDAC3 occupancy in the γ-globin gene promoter with Benserazide exposure, 3-fold reduction in LSD-1 and HDAC2 occupancy in the γ-globin gene promoter with SDMB exposure, while markers of gene activation (histone H3K9 acetylation and H3K4 demethylation), were enriched 5.7-fold. These findings identify clinical-stage oral therapeutics which inhibit or displace major co-repressors of γ-globin gene transcription and may suggest a rationale for combination therapy to produce enhanced efficacy. PMID:26603726

  20. Quercetin represses apolipoprotein B expression by inhibiting the transcriptional activity of C/EBPβ.

    Directory of Open Access Journals (Sweden)

    Makoto Shimizu

    Full Text Available Quercetin is one of the most abundant polyphenolic flavonoids found in fruits and vegetables and has anti-oxidative and anti-obesity effects. Because the small intestine is a major absorptive organ of dietary nutrients, it is likely that highly concentrated food constituents, including polyphenols, are present in the small intestinal epithelial cells, suggesting that food factors may have a profound effect in this tissue. To identify novel targets of quercetin in the intestinal enterocytes, mRNA profiling using human intestinal epithelial Caco-2 cells was performed. We found that mRNA levels of some apolipoproteins, particularly apolipoprotein B (apoB, are downregulated in the presence of quercetin. On the exposure of Caco-2 cells to quercetin, both mRNA and protein levels of apoB were decreased. Promoter analysis of the human apoB revealed that quercetin response element is localized at the 5'-proximal promoter region, which contains a conserved CCAAT enhancer-binding protein (C/EBP-response element. We found that quercetin reduces the promoter activity of apoB, driven by the enforced expression of C/EBPβ. Quercetin had no effect on either mRNA or protein levels of C/EBPβ. In contrast, we found that quercetin inhibits the transcriptional activity of C/EBPβ but not its recruitment to the apoB promoter. On the exposure of Caco-2 cells to quercetin 3-O-glucuronide, which is in a cell-impermeable form, no notable change in apoB mRNA was observed, suggesting an intracellular action of quercetin. In vitro interaction experiments using quercetin-conjugated beads revealed that quercetin binds to C/EBPβ. Our results describe a novel regulatory mechanism of transcription of apolipoprotein genes by quercetin in the intestinal enterocytes.

  1. Dact2 represses PITX2 transcriptional activation and cell proliferation through Wnt/beta-catenin signaling during odontogenesis.

    Directory of Open Access Journals (Sweden)

    Xiao Li

    Full Text Available Dact proteins belong to the Dapper/Frodo protein family and function as cytoplasmic attenuators in Wnt and TGFβ signaling. Previous studies show that Dact1 is a potent Wnt signaling inhibitor by promoting degradation of β-catenin. We report a new mechanism for Dact2 function as an inhibitor of the canonical Wnt signaling pathway by interacting with PITX2. PITX2 is a downstream transcription factor in Wnt/β-catenin signaling, and PITX2 synergizes with Lef-1 to activate downstream genes. Immunohistochemistry verified the expression of Dact2 in the tooth epithelium, which correlated with Pitx2 epithelial expression. Dact2 loss of function and PITX2 gain of function studies reveal a feedback mechanism for controlling Dact2 expression. Pitx2 endogenously activates Dact2 expression and Dact2 feeds back to repress Pitx2 transcriptional activity. A Topflash reporter system was employed showing PITX2 activation of Wnt signaling, which is attenuated by Dact2. Transient transfections demonstrate the inhibitory effect of Dact2 on critical dental epithelial differentiation factors during tooth development. Dact2 significantly inhibits PITX2 activation of the Dlx2 and amelogenin promoters. Multiple lines of evidence conclude the inhibition is achieved by the physical interaction between Dact2 and Pitx2 proteins. The loss of function of Dact2 also reveals increased cell proliferation due to up-regulated Wnt downstream genes, cyclinD1 and cyclinD2. In summary, we have identified a novel role for Dact2 as an inhibitor of the canonical Wnt pathway in embryonic tooth development through its regulation of cell proliferation and differentiation.

  2. The transcription factor Vox represses endoderm development by interacting with Casanova and Pou2.

    Science.gov (United States)

    Zhao, Jue; Lambert, Guillaume; Meijer, Annemarie H; Rosa, Frederic M

    2013-03-01

    Endoderm and mesoderm are both formed upon activation of Nodal signaling but how endoderm differentiates from mesoderm is still poorly explored. The sox-related gene casanova (sox32) acts downstream of the Nodal signal, is essential for endoderm development and requires the co-factor Pou2 (Pou5f1, Oct3, Oct4) in this process. Conversely, BMP signals have been shown to inhibit endoderm development by an as yet unexplained mechanism. In a search for Casanova regulators in zebrafish, we identified two of its binding partners as the transcription factors Pou2 and Vox, a member of the Vent group of proteins also involved in the patterning of the gastrula. In overexpression studies we show that vox and/or Vent group genes inhibit the capacity of Casanova to induce endoderm, even in the presence of its co-factor Pou2, and that Vox acts as a repressor in this process. We further show that vox, but not other members of the Vent group, is essential for defining the proper endodermal domain size at gastrulation. In this process, vox acts downstream of BMPs. Cell fate analysis further shows that Vox plays a key role downstream of BMP signals in regulating the capacity of Nodal to induce endoderm versus mesoderm by modulating the activity of the Casanova/Pou2 regulatory system. PMID:23364327

  3. NB-LRR signaling induces translational repression of viral transcripts and the formation of RNA processing bodies through mechanisms differing from those activated by UV stress and RNAi.

    Science.gov (United States)

    Meteignier, Louis-Valentin; Zhou, Ji; Cohen, Mathias; Bhattacharjee, Saikat; Brosseau, Chantal; Caamal Chan, Maria Goretty; Robatzek, Silke; Moffett, Peter

    2016-04-01

    Plant NB-LRR proteins confer resistance to multiple pathogens, including viruses. Although the recognition of viruses by NB-LRR proteins is highly specific, previous studies have suggested that NB-LRR activation results in a response that targets all viruses in the infected cell. Using an inducible system to activate NB-LRR defenses, we find that NB-LRR signaling does not result in the degradation of viral transcripts, but rather prevents them from associating with ribosomes and translating their genetic material. This indicates that defense against viruses involves the repression of viral RNA translation. This repression is specific to viral transcripts and does not involve a global shutdown of host cell translation. As a consequence of the repression of viral RNA translation, NB-LRR responses induce a dramatic increase in the biogenesis of RNA processing bodies (PBs). We demonstrate that other pathways that induce translational repression, such as UV irradiation and RNAi, also induce PBs. However, by investigating the phosphorylation status of eIF2α and by using suppressors of RNAi we show that the mechanisms leading to PB induction by NB-LRR signaling are different from these stimuli, thus defining a distinct type of translational control and anti-viral mechanism in plants. PMID:26889008

  4. Glucose Repression of Fbp1 Transcription in Schizosaccharomyces Pombe Is Partially Regulated by Adenylate Cyclase Activation by a G Protein α Subunit Encoded by Gpa2 (Git8)

    OpenAIRE

    Nocero, M.; Isshiki, T.; Yamamoto, M.; Hoffman, C. S.

    1994-01-01

    In the fission yeast Schizosaccharomyces pombe, genetic studies have identified genes that are required for glucose repression of fbp1 transcription. The git2 gene, also known as cyr1, encodes adenylate cyclase. Adenylate cyclase converts ATP into the second messenger cAMP as part of many eukaryotic signal transduction pathways. The git1, git3, git5, git7, git8 and git10 genes act upstream of adenylate cyclase, presumably encoding an adenylate cyclase activation pathway. In mammalian cells, a...

  5. TNIP1 reduction of HSPA6 gene expression occurs in promoter regions lacking binding sites for known TNIP1-repressed transcription factors

    OpenAIRE

    Ramirez, Vincent P.; Krueger, Winfried; Aneskievich, Brian J.

    2014-01-01

    TNFα-induced protein 3-interacting protein 1 (TNIP1) represses signaling pathways initiated by specific nuclear and transmembrane receptors. This effect results in reduced activity of distinct transcription factors such as retinoic acid receptors (RAR), peroxisome-proliferator-activated receptors (PPAR), and NFκB. TNIP1-null and TNIP1-knockin defective for ubiquitin-binding mice show increased liver apoptosis, and enlarged spleen and lymph nodes, respectively. To complement current knowledge ...

  6. A human Polycomb isoform lacking the Pc box does not participate to PRC1 complexes but forms protein assemblies and represses transcription.

    Science.gov (United States)

    Völkel, Pamela; Le Faou, Perrine; Vandamme, Julien; Pira, Dorcas; Angrand, Pierre-Olivier

    2012-05-01

    Polycomb repression controls the expression of hundreds of genes involved in development and is mediated by essentially two classes of chromatin-associated protein complexes. The Polycomb repressive complex 2 (PRC2) trimethylates histone H3 at lysine 27, an epigenetic mark that serves as a docking site for the PRC1 protein complex. Drosophila core PRC1 is composed of four subunits: Polycomb (Pc), Posterior sex combs (Psc), Polyhomeotic (Ph) and Sex combs extra (Sce). Each of these proteins has multiple orthologs in vertebrates, thus generating an enormous scope for potential combinatorial diversity. In particular, mammalian genomes encode five Pc family members: CBX2, CBX4, CBX6, CBX7 and CBX8. To complicate matters further, distinct isoforms might arise from single genes. Here, we address the functional role of the two human CBX2 isoforms. Owing to different polyadenylation sites and alternative splicing events, the human CBX2 locus produces two transcripts: a 5-exon transcript that encodes the 532-amino acid CBX2-1 isoform that contains the conserved chromodomain and Pc box and a 4-exon transcript encoding a shorter isoform, CBX2-2, lacking the Pc box but still possessing a chromodomain. Using biochemical approaches and a novel in vivo imaging assay, we show that the short CBX2-2 isoform lacking the Pc box, does not participate in PRC1 protein complexes, but self-associates in vivo and forms complexes of high molecular weight. Furthermore, the CBX2 short isoform is still able to repress transcription, suggesting that Polycomb repression might occur in the absence of PRC1 formation. PMID:22419124

  7. Complex regulation of the global regulatory gene csrA: CsrA-mediated translational repression, transcription from five promoters by Eσ70 and EσS, and indirect transcriptional activation by CsrA

    OpenAIRE

    Yakhnin, Helen; Yakhnin, Alexander V.; Baker, Carol S.; Sineva, Elena; Berezin, Igor; Romeo, Tony; Babitzke, Paul

    2011-01-01

    CsrA of Escherichia coli is an RNA binding protein that globally regulates gene expression by repressing translation and/or altering the stability of target transcripts. Here we explored mechanisms that control csrA expression. Four CsrA binding sites were predicted upstream of the csrA initiation codon, one of which overlapped its Shine-Dalgarno sequence. Results from gel shift, footprint, toeprint and in vitro translation experiments indicate that CsrA binds to these four sites and represse...

  8. Metalloregulator CueR biases RNA polymerase's kinetic sampling of dead-end or open complex to repress or activate transcription.

    Science.gov (United States)

    Martell, Danya J; Joshi, Chandra P; Gaballa, Ahmed; Santiago, Ace George; Chen, Tai-Yen; Jung, Won; Helmann, John D; Chen, Peng

    2015-11-01

    Metalloregulators respond to metal ions to regulate transcription of metal homeostasis genes. MerR-family metalloregulators act on σ(70)-dependent suboptimal promoters and operate via a unique DNA distortion mechanism in which both the apo and holo forms of the regulators bind tightly to their operator sequence, distorting DNA structure and leading to transcription repression or activation, respectively. It remains unclear how these metalloregulator-DNA interactions are coupled dynamically to RNA polymerase (RNAP) interactions with DNA for transcription regulation. Using single-molecule FRET, we study how the copper efflux regulator (CueR)--a Cu(+)-responsive MerR-family metalloregulator--modulates RNAP interactions with CueR's cognate suboptimal promoter PcopA, and how RNAP affects CueR-PcopA interactions. We find that RNAP can form two noninterconverting complexes at PcopA in the absence of nucleotides: a dead-end complex and an open complex, constituting a branched interaction pathway that is distinct from the linear pathway prevalent for transcription initiation at optimal promoters. Capitalizing on this branched pathway, CueR operates via a "biased sampling" instead of "dynamic equilibrium shifting" mechanism in regulating transcription initiation; it modulates RNAP's binding-unbinding kinetics, without allowing interconversions between the dead-end and open complexes. Instead, the apo-repressor form reinforces the dominance of the dead-end complex to repress transcription, and the holo-activator form shifts the interactions toward the open complex to activate transcription. RNAP, in turn, locks CueR binding at PcopA into its specific binding mode, likely helping amplify the differences between apo- and holo-CueR in imposing DNA structural changes. Therefore, RNAP and CueR work synergistically in regulating transcription. PMID:26483469

  9. Transient viral DNA replication and repression of viral transcription are supported by the C-terminal domain of the bovine papillomavirus type 1 E1 protein.

    Science.gov (United States)

    Ferran, M C; McBride, A A

    1998-01-01

    The bovine papillomavirus type 1 E1 protein is important for viral DNA replication and transcriptional repression. It has been proposed that the full-length E1 protein consists of a small N-terminal and a larger C-terminal domain. In this study, it is shown that an E1 polypeptide containing residues 132 to 605 (which represents the C-terminal domain) is able to support transient viral DNA replication, although at a level lower than that supported by the wild-type protein. This domain can also repress E2-mediated transactivation from the P89 promoter as well as the wild-type E1 protein can. PMID:9420289

  10. The Polycomb Group Protein L3MBTL1 Represses a SMAD5-Mediated Hematopoietic Transcriptional Program in Human Pluripotent Stem Cells

    Directory of Open Access Journals (Sweden)

    Fabiana Perna

    2015-04-01

    Full Text Available Epigenetic regulation of key transcriptional programs is a critical mechanism that controls hematopoietic development, and, thus, aberrant expression patterns or mutations in epigenetic regulators occur frequently in hematologic malignancies. We demonstrate that the Polycomb protein L3MBTL1, which is monoallelically deleted in 20q- myeloid malignancies, represses the ability of stem cells to drive hematopoietic-specific transcriptional programs by regulating the expression of SMAD5 and impairing its recruitment to target regulatory regions. Indeed, knockdown of L3MBTL1 promotes the development of hematopoiesis and impairs neural cell fate in human pluripotent stem cells. We also found a role for L3MBTL1 in regulating SMAD5 target gene expression in mature hematopoietic cell populations, thereby affecting erythroid differentiation. Taken together, we have identified epigenetic priming of hematopoietic-specific transcriptional networks, which may assist in the development of therapeutic approaches for patients with anemia.

  11. The Polycomb Group Protein L3MBTL1 Represses a SMAD5-Mediated Hematopoietic Transcriptional Program in Human Pluripotent Stem Cells

    Science.gov (United States)

    Perna, Fabiana; Vu, Ly P.; Themeli, Maria; Kriks, Sonja; Hoya-Arias, Ruben; Khanin, Raya; Hricik, Todd; Mansilla-Soto, Jorge; Papapetrou, Eirini P.; Levine, Ross L.; Studer, Lorenz; Sadelain, Michel; Nimer, Stephen D.

    2015-01-01

    Summary Epigenetic regulation of key transcriptional programs is a critical mechanism that controls hematopoietic development, and, thus, aberrant expression patterns or mutations in epigenetic regulators occur frequently in hematologic malignancies. We demonstrate that the Polycomb protein L3MBTL1, which is monoallelically deleted in 20q- myeloid malignancies, represses the ability of stem cells to drive hematopoietic-specific transcriptional programs by regulating the expression of SMAD5 and impairing its recruitment to target regulatory regions. Indeed, knockdown of L3MBTL1 promotes the development of hematopoiesis and impairs neural cell fate in human pluripotent stem cells. We also found a role for L3MBTL1 in regulating SMAD5 target gene expression in mature hematopoietic cell populations, thereby affecting erythroid differentiation. Taken together, we have identified epigenetic priming of hematopoietic-specific transcriptional networks, which may assist in the development of therapeutic approaches for patients with anemia. PMID:25754204

  12. Intracellular high mobility group B1 protein (HMGB1) represses HIV-1 LTR-directed transcription in a promoter- and cell-specific manner

    International Nuclear Information System (INIS)

    We investigated whether the high mobility group B 1 (HMGB1), an abundant nuclear protein in all mammalian cells, affects HIV-1 transcription. Intracellular expression of human HMGB1 repressed HIV-1 gene expression in epithelial cells. This inhibitory effect of HMGB1 was caused by repression of long terminal repeat (LTR)-mediated transcription. Other viral promoters/enhancers, including simian virus 40 or cytomegalovirus, were not inhibited by HMGB1. In addition, HMGB1 inhibition of HIV-1 subtype C expression was dependent on the number of NFκB sites in the LTR region. The inhibitory effect of HMGB1 on viral gene expression observed in HeLa cells was confirmed by an upregulation of viral replication in the presence of antisense HMGB1 in monocytic cells. In contrast to what was found in HeLa cells and monocytic cells, endogenous HMGB1 expression did not affect HIV-1 replication in unstimulated Jurkat cells. Thus, intracellular HMGB1 affects HIV-1 LTR-directed transcription in a promoter- and cell-specific manner

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

    DEFF Research Database (Denmark)

    Ren, Guoling; Zhang, Guocui; Dong, Zhixiong; Liu, Zhiwei; Li, Lin; Feng, Yunpeng; Su, Dongmei; Zhang, Yu; Huang, Baiqu; Lu, Jun

    2008-01-01

    -immunoprecipitation assays revealed that HDAC4 and YY1 formed a complex. The chromatin immunoprecipitation (ChIP) assays verified that HDAC4 was recruited to HOXB13 promoter by YY1. Moreover, promoter truncation and point mutation studies determined that the two proximal YY1 binding sites on the HOXB13 promoter were...... essential for the recruitments of YY1 and HDAC4. Data presented in this report suggest that YY1 and HDAC4 affected cell growth by repressing transcriptional regulation of HOXB13 through an epigenetic modification of histones....

  14. 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

    OpenAIRE

    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 ...

  15. Lysine-specific demethylase 1 (LSD1 Is required for the transcriptional repression of the telomerase reverse transcriptase (hTERT gene.

    Directory of Open Access Journals (Sweden)

    Qingjun Zhu

    Full Text Available BACKGROUND: Lysine-specific demethylase 1 (LSD1, catalysing demethylation of mono- and di-methylated histone H3-K4 or K9, exhibits diverse transcriptional activities by mediating chromatin reconfiguration. The telomerase reverse transcriptase (hTERT gene, encoding an essential component for telomerase activity that is involved in cellular immortalization and transformation, is silent in most normal human cells while activated in up to 90% of human cancers. It remains to be defined how exactly the transcriptional activation of the hTERT gene occurs during the oncogenic process. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, we determined the effect of LSD1 on hTERT transcription. In normal human fibroblasts with a tight hTERT repression, a pharmacological inhibition of LSD1 led to a weak hTERT expression, and a robust induction of hTERT mRNA was observed when LSD1 and histone deacetylases (HDACs were both inhibited. Small interference RNA-mediated depletion of both LSD1 and CoREST, a co-repressor in HDAC-containing complexes, synergistically activated hTERT transcription. In cancer cells, inhibition of LSD1 activity or knocking-down of its expression led to significant increases in levels of hTERT mRNA and telomerase activity. Chromatin immunoprecipitation assay showed that LSD1 occupied the hTERT proximal promoter, and its depletion resulted in elevated di-methylation of histone H3-K4 accompanied by increased H3 acetylation locally in cancer cells. Moreover, during the differentiation of leukemic HL60 cells, the decreased hTERT expression was accompanied by the LSD1 recruitment to the hTERT promoter. CONCLUSIONS/SIGNIFICANCE: LSD1 represses hTERT transcription via demethylating H3-K4 in normal and cancerous cells, and together with HDACs, participates in the establishment of a stable repression state of the hTERT gene in normal or differentiated malignant cells. The findings contribute to better understandings of h

  16. Proto-oncogene FBI-1 (Pokemon/ZBTB7A) represses transcription of the tumor suppressor Rb gene via binding competition with Sp1 and recruitment of co-repressors.

    Science.gov (United States)

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

    2008-11-28

    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

  17. Two-component signal transduction system CBO0787/CBO0786 represses transcription from botulinum neurotoxin promoters in Clostridium botulinum ATCC 3502.

    Directory of Open Access Journals (Sweden)

    Zhen Zhang

    2013-03-01

    Full Text Available Blocking neurotransmission, botulinum neurotoxin is the most poisonous biological substance known to mankind. Despite its infamy as the scourge of the food industry, the neurotoxin is increasingly used as a pharmaceutical to treat an expanding range of muscle disorders. Whilst neurotoxin expression by the spore-forming bacterium Clostridium botulinum appears tightly regulated, to date only positive regulatory elements, such as the alternative sigma factor BotR, have been implicated in this control. The identification of negative regulators has proven to be elusive. Here, we show that the two-component signal transduction system CBO0787/CBO0786 negatively regulates botulinum neurotoxin expression. Single insertional inactivation of cbo0787 encoding a sensor histidine kinase, or of cbo0786 encoding a response regulator, resulted in significantly elevated neurotoxin gene expression levels and increased neurotoxin production. Recombinant CBO0786 regulator was shown to bind to the conserved -10 site of the core promoters of the ha and ntnh-botA operons, which encode the toxin structural and accessory proteins. Increasing concentration of CBO0786 inhibited BotR-directed transcription from the ha and ntnh-botA promoters, demonstrating direct transcriptional repression of the ha and ntnh-botA operons by CBO0786. Thus, we propose that CBO0786 represses neurotoxin gene expression by blocking BotR-directed transcription from the neurotoxin promoters. This is the first evidence of a negative regulator controlling botulinum neurotoxin production. Understanding the neurotoxin regulatory mechanisms is a major target of the food and pharmaceutical industries alike.

  18. The formamidase gene of Aspergillus nidulans: regulation by nitrogen metabolite repression and transcriptional interference by an overlapping upstream gene.

    OpenAIRE

    Fraser, J A; Davis, M A; Hynes, M J

    2001-01-01

    The ability to utilize formamide as a sole nitrogen source has been found in numerous fungi. We have cloned the fmdS gene encoding a formamidase from Aspergillus nidulans and found that it belongs to a highly conserved family of proteins separate from the major amidase families. The expression of fmdS is primarily regulated via AreA-mediated nitrogen metabolite repression and does not require the addition of exogenous inducer. Consistent with this, deletion analysis of the 5' region of fmdS h...

  19. The transcription factor GATA3 actively represses RUNX3 protein-regulated production of interferon-gamma

    OpenAIRE

    Yagi, Ryoji; Junttila, Ilkka S.; Wei, Gang; Urban, Joseph F.; Zhao, Keji; Paul, William E.; Zhu, Jinfang

    2010-01-01

    The transcription factor GATA3 is crucial for the differentiation of naïve CD4+ T cells into T helper 2 (Th2) cells. Here we show that deletion of Gata3 allowed the appearance of interferon γ (IFNγ)-producing cells in the absence of interleukin-12 (IL-12) and IFNγ. Such IFNγ production was transcription factor T-bet-independent. Another T-box-containing transcription factor Eomes, but not T-bet, was induced both in GATA3-deficient CD4+ T cells differentiated under Th2 cell conditions, and in ...

  20. GLUT1 glucose transporter gene transcription is repressed by Sp3. Evidence for a regulatory role of Sp3 during myogenesis.

    Science.gov (United States)

    Fandos, C; Sánchez-Feutrie, M; Santalucía, T; Viñals, F; Cadefau, J; Gumà, A; Cussó, R; Kaliman, P; Canicio, J; Palacín, M; Zorzano, A

    1999-11-19

    GLUT1 glucose transporters are highly expressed in proliferating and transformed cells as well as in tissues during fetal life. However, the mechanisms that regulate GLUT1 gene expression remain largely unknown. Here, we demonstrate that Sp3 proteins bind to the GLUT1 proximal promoter gene and inhibit transcriptional activity in muscle and non-muscle cells. Two different Sp3 translational products (110 and 74 kDa) derived from differential translational initiation were detected in nuclear extracts from myoblast cells, and both Sp3 protein species inhibited GLUT1 gene transcriptional activity. The inhibitory effect of Sp3 was dominant over the stimulatory effect of Sp1 on transcriptional activity of GLUT1 gene. Furthermore, abolition of Sp3 binding to the proximal promoter of GLUT1 gene completely blocked the response to Sp3. We provide evidence that the expression of Sp3 protein is subject to regulation in muscle cells and that this is likely to control GLUT1. Thus, Sp3 protein was up-regulated in the absence of changes in Sp1 early after the induction of IGF-II-dependent myogenesis. Furthermore, forced over-expression of MyoD caused an enhancement in the cellular Sp3/Sp1 ratio which was concomitant to a reduced GLUT1 expression. Later during myogenesis, Sp3 expression was substantial whereas Sp1 was markedly down-regulated. In summary, we provide direct evidence that the transcription factor Sp3 represses gene expression in non-muscle and muscle cells and this is likely to operate in fetal heart by binding to the GLUT1 gene promoter. This is the first description of a repressor of GLUT1 gene transcription. Furthermore, we propose that variations in the ratio of Sp3 versus Sp1 regulate GLUT1 promoter activity and this is crucial in the down-regulation of GLUT1 associated to myogenesis. PMID:10556032

  1. Tamoxifen represses alcohol-induced transcription of RNA polymerase III-dependent genes in breast cancer cells

    OpenAIRE

    Zhong, Qian; Shi, Ganggang; Zhang, Qingsong; Lu, Lei; Levy, Daniel; Zhong, Shuping

    2014-01-01

    Alcohol consumption in women has been associated with an increased risk of breast cancer, particular in estrogen receptor positive (ER+) cases. Deregulation of RNA polymerase III-dependent (Pol III) transcription enhances cellular tRNAs and 5S rRNA production, leading to an increase in translational capacity to promote cell transformation and tumor formation. Our recent studies demonstrated that alcohol induces Brf1 expression and Pol III gene transcription via ER. Here, we report that Tamoxi...

  2. Progesterone receptor activation downregulates GATA3 by transcriptional repression and increased protein turnover promoting breast tumor growth

    OpenAIRE

    Izzo, Franco; Mercogliano, Florencia; Venturutti, Leandro; Tkach, Mercedes; Inurrigarro, Gloria; Schillaci, Roxana; Cerchietti, Leandro; Elizalde, Patricia V.; Proietti, Cecilia J.

    2014-01-01

    Introduction The transcription factor GATA3 is involved in mammary gland development and is crucial for the maintenance of the differentiated status of luminal epithelial cells. The role of GATA3 in breast cancer as a tumor suppressor has been established, although insights into the mechanism of GATA3 expression loss are still required. Methods Chromatin immunoprecipitation assays were conducted to study progestin modulation of recruitment of transcription factors to GATA3 promoter. We perfor...

  3. Transcription from the second heavy-strand promoter of human mtDNA is repressed by transcription factor A in vitro

    OpenAIRE

    Lodeiro, Maria F.; Uchida, Akira; Bestwick, Megan; Moustafa, Ibrahim M.; Arnold, Jamie J.; Shadel, Gerald S.; Cameron, Craig E.

    2012-01-01

    Cell-based studies support the existence of two promoters on the heavy strand of mtDNA: heavy-strand promoter 1 (HSP1) and HSP2. However, transcription from HSP2 has been reported only once in a cell-free system, and never when recombinant proteins have been used. Here, we document transcription from HSP2 using an in vitro system of defined composition. An oligonucleotide template representing positions 596–685 of mtDNA was sufficient to observe transcription by the human mtRNA polymerase (PO...

  4. HuR represses Wnt/β-catenin-mediated transcriptional activity by promoting cytoplasmic localization of β-catenin

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Inae; Hur, Jung; Jeong, Sunjoo, E-mail: sjsj@dankook.ac.kr

    2015-01-30

    Highlights: • Wnt signaling as well as β-catenin overexpression enhance HuR cytoplasmic export. • HuR overexpression promotes cytoplasmic localization of β-catenin from the perinuclear fraction. • Wnt/β-catenin-mediated transcriptional activity is repressesed by HuR. - Abstract: β-Catenin is the key transcriptional activator of canonical Wnt signaling in the nucleus; thus, nuclear accumulation of β-catenin is a critical step for expressing target genes. β-Catenin accumulates in the nucleus of cancer cells where it activates oncogenic target genes. Hu antigen R (HuR) is a RNA binding protein that regulates multiple post-transcriptional processes including RNA stability. Thus, cytoplasmic HuR protein may be involved in tumorigenesis by stabilizing oncogenic transcripts, but the molecular mechanism remains unclear. Here, we observed that Wnt/β-catenin signaling induced export of the HuR protein, whereas HuR overexpression promoted accumulation of the β-catenin protein in the cytoplasm. Thus, Wnt/β-catenin-mediated transcriptional activity in the nucleus was reduced by overexpressing HuR. These results suggest novel and uncharacterized cytoplasmic β-catenin functions related to HuR-mediated RNA metabolism in cancer cells.

  5. The transcription factor GATA3 actively represses RUNX3 protein-regulated production of interferon-gamma

    Science.gov (United States)

    The transcription factor GATA3 is crucial for the differentiation of naive CD4+ T cells into T helper 2 (Th2) cells. Here, we show that deletion of Gata3 allowed the appearance of interferon-g (IFN-g)-producing cells in the absence of interleukin-12 (IL-12) and IFN-g. Such IFN-g production was tra...

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

    Science.gov (United States)

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

    2014-10-15

    In Catharanthus roseus, accumulating data highlighted the existence of a coordinated transcriptional regulation of structural genes that takes place within the secoiridoid biosynthetic branch, including the methyl erythritol phosphate (MEP) pathway and the following steps leading to secologanin. To identify transcription factors acting in these pathways, we performed a yeast one-hybrid screening using as bait a promoter region of the hydroxymethylbutenyl 4-diphosphate synthase (HDS) gene involved in the responsiveness of C. roseus cells to hormonal signals inducing monoterpene indole alkaloid (MIA) production. We identified that ZCT2, one of the three members of the zinc finger Catharanthus protein (ZCT) family, can bind to a HDS promoter region involved in hormonal responsiveness. By trans-activation assays, we demonstrated that ZCT1 and ZCT2 but not ZCT3 repress the HDS promoter activity. Gene expression analyses in C. roseus cells exposed to methyljasmonate revealed a persistence of induction of ZCT2 gene expression suggesting the existence of feed-back regulatory events acting on HDS gene expression in correlation with the MIA production. PMID:25108262

  7. Transcription factor C/EBP-β induces tumor-suppressor phosphatase PHLPP2 through repression of the miR-17-92 cluster in differentiating AML cells.

    Science.gov (United States)

    Yan, Y; Hanse, E A; Stedman, K; Benson, J M; Lowman, X H; Subramanian, S; Kelekar, A

    2016-07-01

    PHLPP2, a member of the PH-domain leucine-rich repeat protein phosphatase (PHLPP) family, which targets oncogenic kinases, has been actively investigated as a tumor suppressor in solid tumors. Little is known, however, regarding its regulation in hematological malignancies. We observed that PHLPP2 protein expression, but not its mRNA, was suppressed in late differentiation stage acute myeloid leukemia (AML) subtypes. MicroRNAs (miR or miRNAs) from the miR-17-92 cluster, oncomir-1, were shown to inhibit PHLPP2 expression and these miRNAs were highly expressed in AML cells that lacked PHLPP2 protein. Studies showed that miR-17-92 cluster regulation was, surprisingly, independent of transcription factors c-MYC and E2F in these cells; instead all-trans-retinoic acid (ATRA), a drug used for terminally differentiating AML subtypes, markedly suppressed miR-17-92 expression and increased PHLPP2 protein levels and phosphatase activity. Finally, we demonstrate that the effect of ATRA on miR-17-92 expression is mediated through its target, transcription factor C/EBPβ, which interacts with the intronic promoter of the miR-17-92 gene to inhibit transactivation of the cluster. These studies reveal a novel mechanism for upregulation of the phosphatase activity of PHLPP2 through C/EBPβ-mediated repression of the miR-17-92 cluster in terminally differentiating myeloid cells. PMID:26868909

  8. Disruption of Histone Modification and CARM1 Recruitment by Arsenic Represses Transcription at Glucocorticoid Receptor-Regulated Promoters

    OpenAIRE

    Barr, Fiona D.; Krohmer, Lori J.; Hamilton, Joshua W.; Sheldon, Lynn A.

    2009-01-01

    Chronic exposure to inorganic arsenic (iAs) found in the environment is one of the most significant and widespread environmental health risks in the U.S. and throughout the world. It is associated with a broad range of health effects from cancer to diabetes as well as reproductive and developmental anomalies. This diversity of diseases can also result from disruption of metabolic and other cellular processes regulated by steroid hormone receptors via aberrant transcriptional regulation. Signi...

  9. Transcription of lncRNA prt, clustered prt RNA sites for Mmi1 binding, and RNA polymerase II CTD phospho-sites govern the repression of pho1 gene expression under phosphate-replete conditions in fission yeast.

    Science.gov (United States)

    Chatterjee, Debashree; Sanchez, Ana M; Goldgur, Yehuda; Shuman, Stewart; Schwer, Beate

    2016-07-01

    Expression of fission yeast Pho1 acid phosphatase is repressed during growth in phosphate-rich medium. Repression is mediated by transcription of the prt locus upstream of pho1 to produce a long noncoding (lnc) prt RNA. Repression is also governed by RNA polymerase II CTD phosphorylation status, whereby inability to place a Ser7-PO4 mark (as in S7A) derepresses Pho1 expression, and inability to place a Thr4-PO4 mark (as in T4A) hyper-represses Pho1 in phosphate replete cells. Here we find that basal pho1 expression from the prt-pho1 locus is inversely correlated with the activity of the prt promoter, which resides in a 110-nucleotide DNA segment preceding the prt transcription start site. CTD mutations S7A and T4A had no effect on the activity of the prt promoter or the pho1 promoter, suggesting that S7A and T4A affect post-initiation events in prt lncRNA synthesis that make it less and more repressive of pho1, respectively. prt lncRNA contains clusters of DSR (determinant of selective removal) sequences recognized by the YTH-domain-containing protein Mmi1. Altering the nucleobase sequence of two DSR clusters in the prt lncRNA caused hyper-repression of pho1 in phosphate replete cells, concomitant with increased levels of the prt transcript. The isolated Mmi1 YTH domain binds to RNAs with single or tandem DSR elements, to the latter in a noncooperative fashion. We report the 1.75 Å crystal structure of the Mmi1 YTH domain and provide evidence that Mmi1 recognizes DSR RNA via a binding mode distinct from that of structurally homologous YTH proteins that recognize m(6)A-modified RNA. PMID:27165520

  10. Characterization of OxyR as a negative transcriptional regulator that represses catalase production in Corynebacterium diphtheriae.

    Science.gov (United States)

    Kim, Ju-Sim; Holmes, Randall K

    2012-01-01

    Corynebacterium diphtheriae and Corynebacterium glutamicum each have one gene (cat) encoding catalase. In-frame Δcat mutants of C. diphtheriae and C. glutamicum were hyper-sensitive to growth inhibition and killing by H(2)O(2). In C. diphtheriae C7(β), both catalase activity and cat transcription decreased ~2-fold during transition from exponential growth to early stationary phase. Prototypic OxyR in Escherichia coli senses oxidative stress and it activates katG transcription and catalase production in response to H(2)O(2). In contrast, exposure of C. diphtheriae C7(β) to H(2)O(2) did not stimulate transcription of cat. OxyR from C. diphtheriae and C. glutamicum have 52% similarity with E. coli OxyR and contain homologs of the two cysteine residues involved in H(2)O(2) sensing by E. coli OxyR. In-frame ΔoxyR deletion mutants of C. diphtheriae C7(β), C. diphtheriae NCTC13129, and C. glutamicum were much more resistant than their parental wild type strains to growth inhibition by H(2)O(2). In the C. diphtheriae C7(β) ΔoxyR mutant, cat transcripts were about 8-fold more abundant and catalase activity was about 20-fold greater than in the C7(β) wild type strain. The oxyR gene from C. diphtheriae or C. glutamicum, but not from E. coli, complemented the defect in ΔoxyR mutants of C. diphtheriae and C. glutamicum and decreased their H(2)O(2) resistance to the level of their parental strains. Gel-mobility shift, DNaseI footprint, and primer extension assays showed that purified OxyR from C. diphtheriae C7(β) bound, in the presence or absence of DTT, to a sequence in the cat promoter region that extends from nucleotide position -55 to -10 with respect to the +1 nucleotide in the cat ORF. These results demonstrate that OxyR from C. diphtheriae or C. glutamicum functions as a transcriptional repressor of the cat gene by a mechanism that is independent of oxidative stress induced by H(2)O(2). PMID:22438866

  11. Characterization of OxyR as a negative transcriptional regulator that represses catalase production in Corynebacterium diphtheriae.

    Directory of Open Access Journals (Sweden)

    Ju-Sim Kim

    Full Text Available Corynebacterium diphtheriae and Corynebacterium glutamicum each have one gene (cat encoding catalase. In-frame Δcat mutants of C. diphtheriae and C. glutamicum were hyper-sensitive to growth inhibition and killing by H(2O(2. In C. diphtheriae C7(β, both catalase activity and cat transcription decreased ~2-fold during transition from exponential growth to early stationary phase. Prototypic OxyR in Escherichia coli senses oxidative stress and it activates katG transcription and catalase production in response to H(2O(2. In contrast, exposure of C. diphtheriae C7(β to H(2O(2 did not stimulate transcription of cat. OxyR from C. diphtheriae and C. glutamicum have 52% similarity with E. coli OxyR and contain homologs of the two cysteine residues involved in H(2O(2 sensing by E. coli OxyR. In-frame ΔoxyR deletion mutants of C. diphtheriae C7(β, C. diphtheriae NCTC13129, and C. glutamicum were much more resistant than their parental wild type strains to growth inhibition by H(2O(2. In the C. diphtheriae C7(β ΔoxyR mutant, cat transcripts were about 8-fold more abundant and catalase activity was about 20-fold greater than in the C7(β wild type strain. The oxyR gene from C. diphtheriae or C. glutamicum, but not from E. coli, complemented the defect in ΔoxyR mutants of C. diphtheriae and C. glutamicum and decreased their H(2O(2 resistance to the level of their parental strains. Gel-mobility shift, DNaseI footprint, and primer extension assays showed that purified OxyR from C. diphtheriae C7(β bound, in the presence or absence of DTT, to a sequence in the cat promoter region that extends from nucleotide position -55 to -10 with respect to the +1 nucleotide in the cat ORF. These results demonstrate that OxyR from C. diphtheriae or C. glutamicum functions as a transcriptional repressor of the cat gene by a mechanism that is independent of oxidative stress induced by H(2O(2.

  12. Conserved sequence-specific lincRNA-steroid receptor interactions drive transcriptional repression and direct cell fate

    Energy Technology Data Exchange (ETDEWEB)

    Hudson, William H.; Pickard, Mark R.; de Vera, Ian Mitchelle S.; Kuiper, Emily G.; Mourtada-Maarabouni, Mirna; Conn, Graeme L.; Kojetin, Douglas J.; Williams, Gwyn T.; Ortlund, Eric A. [Emory-MED; (Keele); (Scripps)

    2014-12-23

    The majority of the eukaryotic genome is transcribed, generating a significant number of long intergenic noncoding RNAs (lincRNAs). Although lincRNAs represent the most poorly understood product of transcription, recent work has shown lincRNAs fulfill important cellular functions. In addition to low sequence conservation, poor understanding of structural mechanisms driving lincRNA biology hinders systematic prediction of their function. Here we report the molecular requirements for the recognition of steroid receptors (SRs) by the lincRNA growth arrest-specific 5 (Gas5), which regulates steroid-mediated transcriptional regulation, growth arrest and apoptosis. We identify the functional Gas5-SR interface and generate point mutations that ablate the SR-Gas5 lincRNA interaction, altering Gas5-driven apoptosis in cancer cell lines. Further, we find that the Gas5 SR-recognition sequence is conserved among haplorhines, with its evolutionary origin as a splice acceptor site. This study demonstrates that lincRNAs can recognize protein targets in a conserved, sequence-specific manner in order to affect critical cell functions.

  13. lncRNA-Induced Nucleosome Repositioning Reinforces Transcriptional Repression of rRNA Genes upon Hypotonic Stress

    Directory of Open Access Journals (Sweden)

    Zhongliang Zhao

    2016-03-01

    Full Text Available The activity of rRNA genes (rDNA is regulated by pathways that target the transcription machinery or alter the epigenetic state of rDNA. Previous work has established that downregulation of rRNA synthesis in quiescent cells is accompanied by upregulation of PAPAS, a long noncoding RNA (lncRNA that recruits the histone methyltransferase Suv4-20h2 to rDNA, thus triggering trimethylation of H4K20 (H4K20me3 and chromatin compaction. Here, we show that upregulation of PAPAS in response to hypoosmotic stress does not increase H4K20me3 because of Nedd4-dependent ubiquitinylation and proteasomal degradation of Suv4-20h2. Loss of Suv4-20h2 enables PAPAS to interact with CHD4, a subunit of the chromatin remodeling complex NuRD, which shifts the promoter-bound nucleosome into the transcriptional “off” position. Thus, PAPAS exerts a “stress-tailored” dual function in rDNA silencing, facilitating either Suv4-20h2-dependent chromatin compaction or NuRD-dependent changes in nucleosome positioning.

  14. Carnitine palmitoyltransferase 1A functions to repress FoxO transcription factors to allow cell cycle progression in ovarian cancer.

    Science.gov (United States)

    Shao, Huanjie; Mohamed, Esraa M; Xu, Guoyan G; Waters, Michael; Jing, Kai; Ma, Yibao; Zhang, Yan; Spiegel, Sarah; Idowu, Michael O; Fang, Xianjun

    2016-01-26

    Cancer cells rely on hyperactive de novo lipid synthesis for maintaining malignancy. Recent studies suggest involvement in cancer of fatty acid oxidation, a process functionally opposite to lipogenesis. A mechanistic link from lipid catabolism to oncogenic processes is yet to be established. Carnitine palmitoyltransferase 1 (CPT1) is a rate-limiting enzyme of fatty acid β-oxidation (FAO) that catalyzes the transfer of long-chain acyl group of the acyl-CoA ester to carnitine, thereby shuttling fatty acids into the mitochondrial matrix for β-oxidation. In the present study, we demonstrated that CPT1A was highly expressed in most ovarian cancer cell lines and primary ovarian serous carcinomas. Overexpression of CPT1A correlated with a poor overall survival of ovarian cancer patients. Inactivation of CPT1A decreased cellular ATP levels and induced cell cycle arrest at G0/G1, suggesting that ovarian cancer cells depend on or are addicted to CPT1A-mediated FAO for cell cycle progression. CPT1A deficiency also suppressed anchorage-independent growth and formation of xenografts from ovarian cancer cell lines. The cyclin-dependent kinase inhibitor p21WAF1 (p21) was identified as most consistently and robustly induced cell cycle regulator upon inactivation of CPT1A. Furthermore, p21 was transcriptionally upregulated by the FoxO transcription factors, which were in turn phosphorylated and activated by AMP-activated protein kinase and the mitogen-activated protein kinases JNK and p38. Our results established the oncogenic relevance of CPT1A and a mechanistic link from lipid catabolism to cell cycle regulation, suggesting that CPT1A could be a prognostic biomarker and rational target for therapeutic intervention of cancer. PMID:26716645

  15. The SCL/TAL1 Transcription Factor Represses the Stress Protein DDiT4/REDD1 in Human Hematopoietic Stem/Progenitor Cells.

    Science.gov (United States)

    Benyoucef, Aissa; Calvo, Julien; Renou, Laurent; Arcangeli, Marie-Laure; van den Heuvel, Anita; Amsellem, Sophie; Mehrpour, Maryam; Larghero, Jerome; Soler, Eric; Naguibneva, Irina; Pflumio, Francoise

    2015-07-01

    Hematopoietic stem/progenitor cells (HSPCs) are regulated through numerous molecular mechanisms that have not been interconnected. The transcription factor stem cell leukemia/T-cell acute leukemia 1 (TAL1) controls human HSPC but its mechanism of action is not clarified. In this study, we show that knockdown (KD) or short-term conditional over-expression (OE) of TAL1 in human HSPC ex vivo, respectively, blocks and maintains hematopoietic potentials, affecting proliferation of human HSPC. Comparative gene expression analyses of TAL1/KD and TAL1/OE human HSPC revealed modifications of cell cycle regulators as well as previously described TAL1 target genes. Interestingly an inverse correlation between TAL1 and DNA damage-induced transcript 4 (DDiT4/REDD1), an inhibitor of the mammalian target of rapamycin (mTOR) pathway, is uncovered. Low phosphorylation levels of mTOR target proteins in TAL1/KD HSPC confirmed an interplay between mTOR pathway and TAL1 in correlation with TAL1-mediated effects of HSPC proliferation. Finally chromatin immunoprecipitation experiments performed in human HSPC showed that DDiT4 is a direct TAL1 target gene. Functional analyses showed that TAL1 represses DDiT4 expression in HSPCs. These results pinpoint DDiT4/REDD1 as a novel target gene regulated by TAL1 in human HSPC and establish for the first time a link between TAL1 and the mTOR pathway in human early hematopoietic cells. Stem Cells 2015;33:2268-2279. PMID:25858676

  16. Psychiatric Risk Gene Transcription Factor 4 Regulates Intrinsic Excitability of Prefrontal Neurons via Repression of SCN10a and KCNQ1.

    Science.gov (United States)

    Rannals, Matthew D; Hamersky, Gregory R; Page, Stephanie Cerceo; Campbell, Morganne N; Briley, Aaron; Gallo, Ryan A; Phan, BaDoi N; Hyde, Thomas M; Kleinman, Joel E; Shin, Joo Heon; Jaffe, Andrew E; Weinberger, Daniel R; Maher, Brady J

    2016-04-01

    Transcription Factor 4 (TCF4) is a clinically pleiotropic gene associated with schizophrenia and Pitt-Hopkins syndrome (PTHS). To gain insight about the neurobiology of TCF4, we created an in vivo model of PTHS by suppressing Tcf4 expression in rat prefrontal neurons immediately prior to neurogenesis. This cell-autonomous genetic insult attenuated neuronal spiking by increasing the afterhyperpolarization. At the molecular level, using a novel technique called iTRAP that combined in utero electroporation and translating ribosome affinity purification, we identified increased translation of two ion channel genes, Kcnq1 and Scn10a. These ion channel candidates were validated by pharmacological rescue and molecular phenocopy. Remarkably, similar excitability deficits were observed in prefrontal neurons from a Tcf4(+/tr) mouse model of PTHS. Thus, we identify TCF4 as a regulator of neuronal intrinsic excitability in part by repression of Kcnq1 and Scn10a and suggest that this molecular function may underlie pathophysiology associated with neuropsychiatric disorders. PMID:26971948

  17. The manganese-responsive regulator MntR represses transcription of a predicted ZIP family metal ion transporter in Corynebacterium glutamicum.

    Science.gov (United States)

    Baumgart, Meike; Frunzke, Julia

    2015-01-01

    Manganese is an important trace element required as an enzyme cofactor and for protection against oxidative stress. In this study, we characterized the DtxR-type transcriptional regulator MntR (cg0741) of Corynebacterium glutamicum ATCC 13032 as a manganese-dependent repressor of the predicted ZIP family metal transporter Cg1623. Comparative transcriptome analysis of a ΔmntR strain and the wild type led to the identification of cg1623 as potential target gene of MntR which was about 50-fold upregulated when cells were grown in glucose minimal medium. Using electrophoretic mobility shift assays, a conserved 18 bp inverted repeat (TGTTCAATGCGTTGAACA) was identified as binding motif of MntR in the cg1623 promoter and confirmed by mutational analysis. Promoter fusion of Pcg1623 to eyfp confirmed that the MntR-dependent repression is only abolished in the absence of manganese. However, neither deletion of mntR nor cg1623 resulted in a significant growth phenotype in comparison to the wild type--strongly suggesting the presence of further manganese uptake and efflux systems in C. glutamicum. The control of cg1623 by the DtxR-type regulator MntR represents the first example of a predicted ZIP family protein that is regulated in a manganese-dependent manner in bacteria. PMID:25790484

  18. E2F-Rb Complexes Assemble and Inhibit cdc25A Transcription in Cervical Carcinoma Cells following Repression of Human Papillomavirus Oncogene Expression

    OpenAIRE

    Wu, Lingling; Goodwin, Edward C.; Naeger, Lisa Kay; Vigo, Elena; Galaktionov, Konstantin; Helin, Kristian; DiMaio, Daniel

    2000-01-01

    Expression of the bovine papillomavirus E2 protein in cervical carcinoma cells represses expression of integrated human papillomavirus (HPV) E6/E7 oncogenes, followed by repression of the cdc25A gene and other cellular genes required for cell cycle progression, resulting in dramatic growth arrest. To explore the mechanism of repression of cell cycle genes in cervical carcinoma cells following E6/E7 repression, we analyzed regulation of the cdc25A promoter, which contains two consensus E2F bin...

  19. Nerve Injury Diminishes Opioid Analgesia through Lysine Methyltransferase-mediated Transcriptional Repression of μ-Opioid Receptors in Primary Sensory Neurons.

    Science.gov (United States)

    Zhang, Yuhao; Chen, Shao-Rui; Laumet, Geoffroy; Chen, Hong; Pan, Hui-Lin

    2016-04-15

    The μ-opioid receptor (MOR, encoded by Oprm1) agonists are the mainstay analgesics for treating moderate to severe pain. Nerve injury causes down-regulation of MORs in the dorsal root ganglion (DRG) and diminishes the opioid effect on neuropathic pain. However, the epigenetic mechanisms underlying the diminished MOR expression caused by nerve injury are not clear. G9a (encoded by Ehmt2), a histone 3 at lysine 9 methyltransferase, is a key chromatin regulator responsible for gene silencing. In this study, we determined the role of G9a in diminished MOR expression and opioid analgesic effects in animal models of neuropathic pain. We found that nerve injury in rats induced a long-lasting reduction in the expression level of MORs in the DRG but not in the spinal cord. Nerve injury consistently increased the enrichment of the G9a product histone 3 at lysine 9 dimethylation in the promoter of Oprm1 in the DRG. G9a inhibition or siRNA knockdown fully reversed MOR expression in the injured DRG and potentiated the morphine effect on pain hypersensitivity induced by nerve injury. In mice lacking Ehmt2 in DRG neurons, nerve injury failed to reduce the expression level of MORs and the morphine effect. In addition, G9a inhibition or Ehmt2 knockout in DRG neurons normalized nerve injury-induced reduction in the inhibitory effect of the opioid on synaptic glutamate release from primary afferent nerves. Our findings indicate that G9a contributes critically to transcriptional repression of MORs in primary sensory neurons in neuropathic pain. G9a inhibitors may be used to enhance the opioid analgesic effect in the treatment of chronic neuropathic pain. PMID:26917724

  20. The Developmental Regulator Protein Gon4l Associates with Protein YY1, Co-repressor Sin3a, and Histone Deacetylase 1 and Mediates Transcriptional Repression*

    Science.gov (United States)

    Lu, Ping; Hankel, Isaiah L.; Hostager, Bruce S.; Swartzendruber, Julie A.; Friedman, Ann D.; Brenton, Janet L.; Rothman, Paul B.; Colgan, John D.

    2011-01-01

    Genetic studies involving zebrafish and mice have demonstrated that the protein Gon4l (Gon4-like) is essential for hematopoiesis. These studies also suggested that Gon4l regulates gene expression during hematopoietic development, yet the biochemical function of Gon4l has not been defined. Here, we describe the identification of factors that interact with Gon4l and may cooperate with this protein to regulate gene expression. As predicted by polypeptide sequence conservation, Gon4l interacted and co-localized with the DNA-binding protein YY1 (Yin Yang 1). Density gradient sedimentation analysis of protein lysates from mouse M12 B cells showed that Gon4l and YY1 co-sediment with the transcriptional co-repressor Sin3a and its functional partner histone deacetylase (HDAC) 1. Consistent with these results, immunoprecipitation studies showed that Gon4l associates with Sin3a, HDAC1, and YY1 as a part of complexes that form in M12 cells. Sequential immunoprecipitation studies demonstrated that Gon4l, YY1, Sin3a, and HDAC1 could all associate as components of a single complex and that a conserved domain spanning the central portion of Gon4l was required for formation of this complex. When targeted to DNA, Gon4l repressed the activity of a nearby promoter, which correlated with the ability to interact with Sin3a and HDAC1. Our data suggest that Sin3a, HDAC1, and YY1 are co-factors for Gon4l and that Gon4l may function as a platform for the assembly of complexes that regulate gene expression. PMID:21454521

  1. The developmental regulator protein Gon4l associates with protein YY1, co-repressor Sin3a, and histone deacetylase 1 and mediates transcriptional repression.

    Science.gov (United States)

    Lu, Ping; Hankel, Isaiah L; Hostager, Bruce S; Swartzendruber, Julie A; Friedman, Ann D; Brenton, Janet L; Rothman, Paul B; Colgan, John D

    2011-05-20

    Genetic studies involving zebrafish and mice have demonstrated that the protein Gon4l (Gon4-like) is essential for hematopoiesis. These studies also suggested that Gon4l regulates gene expression during hematopoietic development, yet the biochemical function of Gon4l has not been defined. Here, we describe the identification of factors that interact with Gon4l and may cooperate with this protein to regulate gene expression. As predicted by polypeptide sequence conservation, Gon4l interacted and co-localized with the DNA-binding protein YY1 (Yin Yang 1). Density gradient sedimentation analysis of protein lysates from mouse M12 B cells showed that Gon4l and YY1 co-sediment with the transcriptional co-repressor Sin3a and its functional partner histone deacetylase (HDAC) 1. Consistent with these results, immunoprecipitation studies showed that Gon4l associates with Sin3a, HDAC1, and YY1 as a part of complexes that form in M12 cells. Sequential immunoprecipitation studies demonstrated that Gon4l, YY1, Sin3a, and HDAC1 could all associate as components of a single complex and that a conserved domain spanning the central portion of Gon4l was required for formation of this complex. When targeted to DNA, Gon4l repressed the activity of a nearby promoter, which correlated with the ability to interact with Sin3a and HDAC1. Our data suggest that Sin3a, HDAC1, and YY1 are co-factors for Gon4l and that Gon4l may function as a platform for the assembly of complexes that regulate gene expression. PMID:21454521

  2. TBL1 and TBLR1 Phosphorylation on Regulated Gene Promoters Overcomes Dual CtBP and NCoR/SMRT Transcriptional Repression Checkpoints

    OpenAIRE

    Perissi, Valentina; Scafoglio, Claudio; Zhang, Jie; Ohgi, Kenneth A.; Rose, David W.; Glass, Christopher K.; Rosenfeld, Michael G.

    2008-01-01

    A key strategy to achieve regulated gene expression in higher eukaryotes is to prevent illegitimate signal-independent activation by imposing robust control on the dismissal of corepressors. Here, we report that many signaling pathways, including Notch, NFkB, and nuclear receptor ligands, are subjected to a dual repression “check point” based on distinct corepressor complexes. Gene activation requires the release of both CtBP1/2- and NCoR/SMRT-dependent repression, through the coordinate acti...

  3. Eukaryotic translation initiator protein 1A isoform, CCS-3, enhances the transcriptional repression of p21CIP1 by proto-oncogene FBI-1 (Pokemon/ZBTB7A).

    Science.gov (United States)

    Choi, Won-Il; Kim, Youngsoo; Kim, Yuri; Yu, Mi-young; Park, Jungeun; Lee, Choong-Eun; Jeon, Bu-Nam; Koh, Dong-In; Hur, Man-Wook

    2009-01-01

    FBI-1, a member of the POK (POZ and Kruppel) family of transcription factors, plays a role in differentiation, oncogenesis, and adipogenesis. eEF1A is a eukaryotic translation elongation factor involved in several cellular processes including embryogenesis, oncogenic transformation, cell proliferation, and cytoskeletal organization. CCS-3, a potential cervical cancer suppressor, is an isoform of eEF1A. We found that eEF1A forms a complex with FBI-1 by co-immunoprecipitation, SDS-PAGE, and MALDI-TOF Mass analysis of the immunoprecipitate. GST fusion protein pull-downs showed that FBI-1 directly interacts with eEF1A and CCS-3 via the zinc finger and POZ-domain of FBI-1. FBI-1 co-localizes with either eEF1A or CCS-3 at the nuclear periplasm. CCS-3 enhances transcriptional repression of the p21CIP1 gene (hereafter referred to as p21) by FBI-1. The POZ-domain of FBI-1 interacts with the co-repressors, SMRT and BCoR. We found that CCS-3 also interacts with the co-repressors independently. The molecular interaction between the co-repressors and CCS-3 at the POZ-domain of FBI-1 appears to enhance FBI-1 mediated transcriptional repression. Our data suggest that CCS-3 may be important in cell differentiation, tumorigenesis, and oncogenesis by interacting with the proto-oncogene FBI-1 and transcriptional co-repressors. PMID:19471103

  4. Glucose repression in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Kayikci, Omur; Nielsen, Jens

    2015-01-01

    Glucose is the primary source of energy for the budding yeast Saccharomyces cerevisiae. Although yeast cells can utilize a wide range of carbon sources, presence of glucose suppresses molecular activities involved in the use of alternate carbon sources as well as it represses respiration and...... gluconeogenesis. This dominant effect of glucose on yeast carbon metabolism is coordinated by several signaling and metabolic interactions that mainly regulate transcriptional activity but are also effective at post-transcriptional and post-translational levels. This review describes effects of glucose repression...... on yeast carbon metabolism with a focus on roles of the Snf3/Rgt2 glucose-sensing pathway and Snf1 signal transduction in establishment and relief of glucose repression....

  5. Repetitive elements and enforced transcriptional repression co-operate to enhance DNA methylation spreading into a promoter CpG-island

    Science.gov (United States)

    Repression of many tumor suppressor genes in cancer is concurrent with aberrantly increased DNA methylation levels at promoter CpG islands (CGIs). About one-fourth of empirically defined human promoters are surrounded by or contain clustered repetitive elements. It was previously observed that a sha...

  6. E2F-Rb complexes assemble and inhibit cdc25A transcription in cervical carcinoma cells following repression of human papillomavirus oncogene expression

    DEFF Research Database (Denmark)

    Wu, L; Goodwin, E C; Naeger, L K;

    2000-01-01

    Expression of the bovine papillomavirus E2 protein in cervical carcinoma cells represses expression of integrated human papillomavirus (HPV) E6/E7 oncogenes, followed by repression of the cdc25A gene and other cellular genes required for cell cycle progression, resulting in dramatic growth arrest....... To explore the mechanism of repression of cell cycle genes in cervical carcinoma cells following E6/E7 repression, we analyzed regulation of the cdc25A promoter, which contains two consensus E2F binding sites and a consensus E2 binding site. The wild-type E2 protein inhibited expression of a...... in the absence of E2 expression. Expression of the E2 protein also led to posttranscriptional increase in the level of E2F4, p105(Rb), and p130 and induced the formation of nuclear E2F4-p130 and E2F4-p105(Rb) complexes. This resulted in marked rearrangement of the protein complexes that formed at the...

  7. Requirements for Vibrio cholerae HapR Binding and Transcriptional Repression at the hapR Promoter Are Distinct from Those at the aphA Promoter

    OpenAIRE

    Lin, Wei; Kovacikova, Gabriela; Skorupski, Karen

    2005-01-01

    Virulence gene expression in certain strains of Vibrio cholerae is regulated in response to cell density by a quorum-sensing cascade that influences the levels of the LuxR homolog HapR through small regulatory RNAs that control the stability of its message. At high cell density, HapR represses the expression of the gene encoding the virulence gene activator AphA by binding to a site between −85 and −58 in the aphA promoter. We show here that a second binding site for HapR lies within the hapR...

  8. Hsp70-Hsp40 chaperone complex functions in controlling polarized growth by repressing Hsf1-driven heat stress-associated transcription.

    Directory of Open Access Journals (Sweden)

    Aleksandar Vjestica

    Full Text Available How the molecular mechanisms of stress response are integrated at the cellular level remains obscure. Here we show that the cellular polarity machinery in the fission yeast Schizosaccharomyces pombe undergoes dynamic adaptation to thermal stress resulting in a period of decreased Cdc42 activity and altered, monopolar growth. Cells where the heat stress-associated transcription was genetically upregulated exhibit similar growth patterning in the absence of temperature insults. We identify the Ssa2-Mas5/Hsp70-Hsp40 chaperone complex as repressor of the heat shock transcription factor Hsf1. Cells lacking this chaperone activity constitutively activate the heat-stress-associated transcriptional program. Interestingly, they also exhibit intermittent monopolar growth within a physiological temperature range and are unable to adapt to heat stress. We propose that by negatively regulating the heat stress-associated transcription, the Ssa2-Mas5 chaperone system could optimize cellular growth under different temperature regiments.

  9. Toxoplasma Effector Recruits the Mi-2/NuRD Complex to Repress STAT1 Transcription and Block IFN-γ-Dependent Gene Expression.

    Science.gov (United States)

    Olias, Philipp; Etheridge, Ronald D; Zhang, Yong; Holtzman, Michael J; Sibley, L David

    2016-07-13

    Interferon gamma (IFN-γ) is an essential mediator of host defense against intracellular pathogens, including the protozoan parasite Toxoplasma gondii. However, prior T. gondii infection blocks IFN-γ-dependent gene transcription, despite the downstream transcriptional activator STAT1 being activated and bound to cognate nuclear promoters. We identify the parasite effector that blocks STAT1-dependent transcription and show it is associated with recruitment of the Mi-2 nucleosome remodeling and deacetylase (NuRD) complex, a chromatin-modifying repressor. This secreted effector, toxoplasma inhibitor of STAT1-dependent transcription (TgIST), translocates to the host cell nucleus, where it recruits Mi-2/NuRD to STAT1-dependent promoters, resulting in altered chromatin and blocked transcription. TgIST is conserved across strains, underlying their shared ability to block IFN-γ-dependent transcription. TgIST deletion results in increased parasite clearance in IFN-γ-activated cells and reduced mouse virulence, which is restored in IFN-γ-receptor-deficient mice. These findings demonstrate the importance of both IFN-γ responses and the ability of pathogens to counteract these defenses. PMID:27414498

  10. A human Polycomb isoform lacking the Pc box does not participate to PRC1 complexes but forms protein assemblies and represses transcription

    DEFF Research Database (Denmark)

    Völkel, Pamela; Le Faou, Perrine; Vandamme, Julien;

    2012-01-01

    site for the PRC1 protein complex. Drosophila core PRC1 is composed of four subunits: Polycomb (Pc), Posterior sex combs (Psc), Polyhomeotic (Ph) and Sex combs extra (Sce). Each of these proteins has multiple orthologs in vertebrates, thus generating an enormous scope for potential combinatorial...... diversity. In particular, mammalian genomes encode five Pc family members: CBX2, CBX4, CBX6, CBX7 and CBX8. To complicate matters further, distinct isoforms might arise from single genes. Here, we address the functional role of the two human CBX2 isoforms. Owing to different polyadenylation sites...... and alternative splicing events, the human CBX2 locus produces two transcripts: a 5-exon transcript that encodes the 532-amino acid CBX2-1 isoform that contains the conserved chromodomain and Pc box and a 4-exon transcript encoding a shorter isoform, CBX2-2, lacking the Pc box but still possessing a chromodomain...

  11. Identification of the subunit of cAMP receptor protein (CRP) that functionally interacts with CytR in CRP-CytR-mediated transcriptional repression

    DEFF Research Database (Denmark)

    Meibom, K L; Kallipolitis, B H; Ebright, R H; Valentin-Hansen, P

    2000-01-01

    At promoters of the Escherichia coli CytR regulon, the cAMP receptor protein (CRP) interacts with the repressor CytR to form transcriptionally inactive CRP-CytR-promoter or (CRP)(2)-CytR-promoter complexes. Here, using "oriented heterodimer" analysis, we show that only one subunit of the CRP dimer......, the subunit proximal to CytR, functionally interacts with CytR in CRP-CytR-promoter and (CRP)(2)-CytR-promoter complexes. Our results provide information about the architecture of CRP-CytR-promoter and (CRP)(2)-CytR-promoter complexes and rule out the proposal that masking of activating region 2 of...... CRP is responsible for the transcriptional inactivity of the complexes....

  12. Beta-casein gene promoter activity is regulated by the hormone-mediated relief of transcriptional repression and a mammary-gland-specific nuclear factor.

    OpenAIRE

    Schmitt-Ney, M; Doppler, W; Ball, R K; Groner, B

    1991-01-01

    Transcription from the beta-casein milk protein gene promoter is induced by the synergistic action of glucocorticoid and prolactin hormones in the murine mammary epithelial cell line, HC11. We analyzed the binding of nuclear proteins to the promoter and determined their binding sites. Site-directed mutagenesis was used to determine the function of nuclear factor binding. During lactogenic hormone induction of HC11 cells, the binding of two nuclear factors increased. The binding of two other n...

  13. Retinoic acid-mediated repression of human papillomavirus 18 transcription and different ligand regulation of the retinoic acid receptor beta gene in non-tumorigenic and tumorigenic HeLa hybrid cells.

    Science.gov (United States)

    Bartsch, D; Boye, B; Baust, C; zur Hausen, H; Schwarz, E

    1992-01-01

    Human papillomavirus type 18 (HPV18) belongs to the group of genital papillomaviruses involved in the development of cervical carcinomas. Since retinoic acid (RA) is a key regulator of epithelial cell differentiation and a growth inhibitor in vitro of HPV18-positive HeLa cervical carcinoma cells, we have used HeLa and HeLa hybrid cells in order to analyse the effects of RA on expression of the HPV18 E6 and E7 oncogenes and of the cellular RA receptor genes RAR-beta and -gamma. We show here that RA down-regulates HPV18 mRNA levels apparently due to transcriptional repression. Transient cotransfection assays indicated that RARs negatively regulate the HPV18 upstream regulatory region and that the central enhancer can confer RA-dependent repression on a heterologous promoter. RA treatment resulted in induction of RAR-beta mRNA levels in non-tumorigenic HeLa hybrid cells, but not in tumorigenic hybrid segregants nor in HeLa cells. No alterations of the RAR-beta gene or of the HeLa RAR-beta promoter could be revealed by Southern and DNA sequence analysis, respectively. As determined by transient transfection assays, however, the RAR-beta control region was activated by RA more strongly in non-tumorigenic hybrid cells than in HeLa cells, thus indicating differences in trans-acting regulatory factors. Our data suggest that the RARs are potential negative regulators of HPV18 E6 and E7 gene expression, and that dysregulation of the RAR-beta gene either causatively contributes to or is an indicator of tumorigenicity in HeLa and HeLa hybrid cells. Images PMID:1318198

  14. CtBP1 is expressed in melanoma and represses the transcription of p16INK4a and Brca1

    OpenAIRE

    Deng, Hui; Liu, Jing; Deng, Yu; Han, Gangwen; Yiqun G Shellman; Robinson, Steven; Tentler, John; Robinson, William; David A Norris; Wang, Xiao-Jing; Zhang, Qinghong

    2013-01-01

    Carboxyl-terminal binding protein 1 (CtBP1) has been shown to suppress the transcription of several tumor suppressors in vitro. Paradoxically, a previous report showed that CtBP1 mRNA was down-regulated in melanoma. Using immunostaining, we found that a large percentage of human melanomas were positive for CtBP1 protein. Further, we demonstrated that CtBP1 expression in melanoma cells contributes to cell proliferation and genome instability, two aspects promoting melanoma initiation and progr...

  15. The Latency-Associated Nuclear Antigen of Rhesus Monkey Rhadinovirus Inhibits Viral Replication through Repression of Orf50/Rta Transcriptional Activation

    OpenAIRE

    DeWire, Scott M.; Damania, Blossom

    2005-01-01

    Rhesus monkey rhadinovirus (RRV) is a gamma-2-herpesvirus that is closely related to Kaposi's sarcoma-associated herpesvirus/human herpesvirus-8. We have previously reported that the transcript for RRV latency-associated nuclear antigen (R-LANA) is expressed during lytic replication in rhesus fibroblasts. In this article, we report the development of a latent culture system for RRV and show that mRNA specific for R-LANA is expressed during latency as well. We have characterized the R-LANA pro...

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

    Directory of Open Access Journals (Sweden)

    Tian Fan

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

  17. Optimal Financial Repression

    OpenAIRE

    Olga A. Norkina; Sergey E. Pekarski

    2014-01-01

    Modern financial repression in advanced economies does not rely on increasing seigniorage revenue, but mostly rests upon regulatory measures to enlarge the demand for public debt that delivers extremely low or negative real interest rate. In this paper we propose the extension of the overlapping generations model to question the optimality of financial repression in the form of non-market placement of the public debt in the captive pension fund. We show that financial repression and capital i...

  18. Long non-coding RNA LINC01133 represses KLF2, P21 and E-cadherin transcription through binding with EZH2, LSD1 in non small cell lung cancer.

    Science.gov (United States)

    Zang, Chongshuang; Nie, Feng-Qi; Wang, Qian; Sun, Ming; Li, Wei; He, Jing; Zhang, Meiling; Lu, Kai-Hua

    2016-03-01

    Long non-coding RNAs are emerging as crucial regulators and prognostic markers in multiple cancers including non small cell lung cancer (NSCLC). In this study, we screened LINCO1133 as a new candidate lncRNA which promotes NSCLC development and progression, in two independent datasets (GSE18842 and GSE19804) from the Gene Expression Omnibus (GEO). LINC01133 is previously found to be over-expressed in lung squamous cell cancer (LSCC) and knockdown its expression inhibits LSCC cells invasion. However, its' molecular mechanism and downstream targets involving in regulation of cancer cells phenotype is not known. Here, we found that LINC01133 expression is up-regulated in NSCLC tissues, and its' over-expression is associated with patients poor prognosis and short survival time. LINC01133 knockdown decreased NSCLC cells proliferation, migration, invasion and induced cell cycle G1/S phase arrest and cell apoptosis. Mechanistic investigations showed that LINC01133 could interact with EZH2, LSD1 and recruit them to KLF2, P21 or E-cadherin promoter regions to repress their transcription. Furthermore, rescue experiments demonstrated that LINC01133 oncogenic function is partly through regulating KLF2. Lastly, we found that there was negative correlation between LINC01133 and KLF2, P21 or E-cadherin in NSCLC. Overall, our findings illuminate how LINC01133 over-expression confers an oncogenic function in NSCLC that may offer a novel therapy target in this disease. PMID:26840083

  19. Arabidopsis STO/BBX24 negatively regulates UV-B signaling by interacting with COP1 and repressing HY5 transcriptional activity

    Institute of Scientific and Technical Information of China (English)

    Lei Jiang; Yan Wang; Qian-Feng Li; Lars Olof Bj(o)rn; Jun-Xian He; Shao-Shan Li

    2012-01-01

    UV-B (280-315 nm) is an integral part of solar radiation and can act either as a stress inducer or as a developmental signal.In recent years,increasing attention has been paid to the Iow-fluence UV-B-induced photomorphogenic response and several key players in this response have been identified,which include UVR8 (a UV-B-specific photoreceptor),COPI (a WD40-repeat-containing RING finger protein),HY5 (a basic zipper transcription factor),and RUP1/2 (two UVR8-interacting proteins).Here we report that Arabidopsis SALT TOLERANCE (STO/BBX24),a known regulator for light signaling in plants,defines a new signaling component in UV-B-mediated photomorphogenesis.The bbx24 mutant is hypersensitive to UV-B radiation and becomes extremely dwarfed under UV-B treatment.By contrast,BBX24 overexpression transgenic lines respond much more weakly to UV-B than the bbx24 and wild-type plants.BBX24 expression is UV-B-inducible and its accumulation under UV-B requires COP1.Co-immunoprecipitation experiments indicate that BBX24 interacts with COP1 in planta upon UV-B illumination.Moreover,BBX24 interacts with HY5 and acts antagonistically with HY5 in UV-B-induced inhibition of hypocotyl elongation.Furthermore,BBX24 attenuates UV-B-induced HY5 accumulation and suppresses its transcription-activation activity.Taken together,our results reveal a previously uncharacterized function of the light-regulated BBX24 in UV-B responses and demonstrate that BBX24 functions as a negative regulator of photomorphogenic UV-B responses by interacting with both COP1 and HY5.The UV-B-inducible expression pattern and its suppression of HY5 activity suggest that BBX24 could be a new component of the feedback regulatory module of UV-B signaling in plants.

  20. Isolation of a Novel Family of C2H2 Zinc Finger Proteins Implicated in Transcriptional Repression Mediated by Chicken Ovalbumin Upstream Promoter Transcription Factor (COUP-TF) Orphan Nuclear Receptors*

    OpenAIRE

    Avram, Dorina; Fields, Andrew; Top, Karen Pretty On; Nevrivy, Daniel J.; Ishmael, Jane E.; Leid, Mark

    2000-01-01

    Two novel and related C2H2 zinc finger proteins that are highly expressed in the brain, CTIP1 and CTIP2 (COUP TF-interacting proteins 1 and 2, respectively), were isolated and shown to interact with all members of the chicken ovalbumin upstream promoter transcription factor (COUP-TF) subfamily of orphan nuclear receptors. The interaction of CTIP1 with ARP1 was studied in detail, and CTIP1 was found to harbor two independent ARP1 interaction domains, ID1 and ID2, whereas the putative AF-2 of A...

  1. RBP1 Recruits Both Histone Deacetylase-Dependent and -Independent Repression Activities to Retinoblastoma Family Proteins

    OpenAIRE

    Lai, Albert; Lee, Joseph M; Yang, Wen-Ming; DeCaprio, James A.; William G Kaelin; Seto, Edward; Branton, Philip E.

    1999-01-01

    Retinoblastoma (RB) tumor suppressor family proteins block cell proliferation in part by repressing certain E2F-specific promoters. Both histone deacetylase (HDAC)-dependent and -independent repression activities are associated with the RB “pocket.” The mechanism by which these two repression functions occupy the pocket is unknown. A known RB-binding protein, RBP1, was previously found by our group to be an active corepressor which, if overexpressed, represses E2F-mediated transcription via i...

  2. JAZF1 promotes proliferation of C2C12 cells, but retards their myogenic differentiation through transcriptional repression of MEF2C and MRF4—Implications for the role of Jazf1 variants in oncogenesis and type 2 diabetes

    Energy Technology Data Exchange (ETDEWEB)

    Yuasa, Katsutoshi; Aoki, Natsumi; Hijikata, Takao, E-mail: hijikata@musashino-u.ac.jp

    2015-08-15

    Single-nucleotide polymorphisms associated with type 2 diabetes (T2D) have been identified in Jazf1, which is also involved in the oncogenesis of endometrial stromal tumors. To understand how Jazf1 variants confer a risk of tumorigenesis and T2D, we explored the functional roles of JAZF1 and searched for JAZF1 target genes in myogenic C2C12 cells. Consistent with an increase of Jazf1 transcripts during myoblast proliferation and their decrease during myogenic differentiation in regenerating skeletal muscle, JAZF1 overexpression promoted cell proliferation, whereas it retarded myogenic differentiation. Examination of myogenic genes revealed that JAZF1 overexpression transcriptionally repressed MEF2C and MRF4 and their downstream genes. AMP deaminase1 (AMPD1) was identified as a candidate for JAZF1 target by gene array analysis. However, promoter assays of Ampd1 demonstrated that mutation of the putative binding site for the TR4/JAZF1 complex did not alleviate the repressive effects of JAZF1 on promoter activity. Instead, JAZF1-mediated repression of Ampd1 occurred through the MEF2-binding site and E-box within the Ampd1 proximal regulatory elements. Consistently, MEF2C and MRF4 expression enhanced Ampd1 promoter activity. AMPD1 overexpression and JAZF1 downregulation impaired AMPK phosphorylation, while JAZF1 overexpression also reduced it. Collectively, these results suggest that aberrant JAZF1 expression contributes to the oncogenesis and T2D pathogenesis. - Highlights: • JAZF1 promotes cell cycle progression and proliferation of myoblasts. • JAZF1 retards myogenic differentiation and hypertrophy of myotubes. • JAZF1 transcriptionally represses Mef2C and Mrf4 expression. • JAZF1 has an impact on the phosphorylation of AMPK.

  3. Cooperative Action of Cdk1/cyclin B and SIRT1 Is Required for Mitotic Repression of rRNA Synthesis

    OpenAIRE

    Voit, Renate; Seiler, Jeanette; Grummt, Ingrid

    2015-01-01

    Author Summary In metazoans, transcription is arrested during mitosis. Previous studies have established that mitotic repression of cellular transcription is mediated by Cdk1/cyclin B-dependent phosphorylation of basal transcription factors that nucleate transcription complex formation. Repression of rDNA transcription at the onset of mitosis is brought about by inactivation of the TBP-containing transcription factor SL1 by Cdk1/cyclin B-dependent phosphorylation of the TAFI110 subunit, which...

  4. Repression of the locus of the enterocyte effacement-encoded regulator of gene transcription of Escherichia coli O157:H7 by Lactobacillus reuteri culture supernatants is LuxS and strain dependent.

    Science.gov (United States)

    Jelcić, Ivan; Hüfner, Eric; Schmidt, Herbert; Hertel, Christian

    2008-05-01

    Culture supernatants of Lactobacillus reuteri ATCC 55730 repressed ler expression in Escherichia coli O157:H7 cells, but neither the strain's isogenic luxS mutant nor the L. reuteri 100-23C wild-type strain and its luxS mutant elicited a comparable effect. Furthermore, the epinephrine-mediated induction of ler expression was repressed by secreted substance(s) of L. reuteri ATCC 55730. PMID:18378666

  5. Repression of the Locus of the Enterocyte Effacement-Encoded Regulator of Gene Transcription of Escherichia coli O157:H7 by Lactobacillus reuteri Culture Supernatants Is LuxS and Strain Dependent▿

    OpenAIRE

    Jelčić, Ivan; Hüfner, Eric; Schmidt, Herbert; Hertel, Christian

    2008-01-01

    Culture supernatants of Lactobacillus reuteri ATCC 55730 repressed ler expression in Escherichia coli O157:H7 cells, but neither the strain's isogenic luxS mutant nor the L. reuteri 100-23C wild-type strain and its luxS mutant elicited a comparable effect. Furthermore, the epinephrine-mediated induction of ler expression was repressed by secreted substance(s) of L. reuteri ATCC 55730.

  6. Nuclear AXIN2 represses MYC gene expression

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-01-03

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

  7. Nuclear AXIN2 represses MYC gene expression

    International Nuclear Information System (INIS)

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

  8. Financial Repression and Structural Imbalances

    OpenAIRE

    Johansson, Anders C.; Wang, Xun

    2012-01-01

    This paper analyzes the relationship between financial repression and structural change. We present a simple theoretical model of structural transformation in which the impact of financial repression on unbalanced growth is studied. The model suggests that governments may choose to repress the financial sector to allow for continued development of the industry sector while inhibiting growth in the domestic service sector. We then present empirical evidence of financial repression having a sig...

  9. FOXP3 interactions with histone acetyltransferase and class II histone deacetylases are required for repression

    OpenAIRE

    Li, Bin; Samanta, Arabinda; Song, Xiaomin; Iacono, Kathryn T.; Bembas, Kathryn; Tao, Ran; Basu, Samik; Riley, James L.; Hancock, Wayne W.; Shen, Yuan; Saouaf, Sandra J.; Mark I. Greene

    2007-01-01

    The forkhead family protein FOXP3 acts as a repressor of transcription and is both an essential and sufficient regulator of the development and function of regulatory T cells. The molecular mechanism by which FOXP3-mediated transcriptional repression occurs remains unclear. Here, we report that transcriptional repression by FOXP3 involves a histone acetyltransferase–deacetylase complex that includes histone acetyltransferase TIP60 (Tat-interactive protein, 60 kDa) and class II histone deacety...

  10. Repression is relieved before attenuation in the trp operon of Escherichia coli as tryptophan starvation becomes increasingly severe.

    OpenAIRE

    Yanofsky, C; Kelley, R.L.; Horn, V.

    1984-01-01

    Expression of the tryptophan operon of Escherichia coli is regulated over about a 500- to 600-fold range by the combined action of repression and attenuation. Repression regulates transcription initiation in response to variation in the intracellular concentration of tryptophan. Attenuation regulates transcription termination at a site in the leader region of the operon in response to changes in the extent of charging of tRNATrp. We measured repression independently of attenuation to ascertai...

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

    Science.gov (United States)

    Du, Dan; Qi, Lei S

    2016-01-01

    Targeted modulation of transcription is necessary for understanding complex gene networks and has great potential for medical and industrial applications. CRISPR is emerging as a powerful system for targeted genome activation and repression, in addition to its use in genome editing. This protocol describes how to design, construct, and experimentally validate the function of sequence-specific single guide RNAs (sgRNAs) for sequence-specific repression (CRISPRi) or activation (CRISPRa) of transcription in mammalian cells. In this technology, the CRISPR-associated protein Cas9 is catalytically deactivated (dCas9) to provide a general platform for RNA-guided DNA targeting of any locus in the genome. Fusion of dCas9 to effector domains with distinct regulatory functions enables stable and efficient transcriptional repression or activation in mammalian cells. Delivery of multiple sgRNAs further enables activation or repression of multiple genes. By using scaffold RNAs (scRNAs), different effectors can be recruited to different genes for simultaneous activation of some and repression of others. The CRISPRi and CRISPRa methods provide powerful tools for sequence-specific control of gene expression on a genome-wide scale to aid understanding gene functions and for engineering genetic regulatory systems. PMID:26729910

  12. Cell-Context Dependent TCF/LEF Expression and Function: Alternative Tales of Repression, De-Repression and Activation Potentials

    OpenAIRE

    Mao, Catherine D.; Byers, Stephen W.

    2011-01-01

    Wnt signaling controls cell specification and fate during development and adult tissue homeostasis by converging on a small family of DNA binding factors, the T-cell factor/lymphoid enhancer factor (TCF/LEF) family. In response to Wnt signals, TCF/LEF members undergo a transcriptional switch from repression to activation mediated in part by nuclear β-catenin binding and recruitment of co-activator complexes. In mammals, the specificity and fine tuning of this transcriptional switch is also ac...

  13. Dominant negative autoregulation limits steady-state repression levels in gene networks.

    Science.gov (United States)

    Semsey, Szabolcs; Krishna, Sandeep; Erdossy, János; Horváth, Péter; Orosz, László; Sneppen, Kim; Adhya, Sankar

    2009-07-01

    Many transcription factors repress transcription of their own genes. Negative autoregulation has been shown to reduce cell-cell variation in regulatory protein levels and speed up the response time in gene networks. In this work we examined transcription regulation of the galS gene and the function of its product, the GalS protein. We observed a unique operator preference of the GalS protein characterized by dominant negative autoregulation. We show that this pattern of regulation limits the repression level of the target genes in steady states. We suggest that transcription factors with dominant negative autoregulation are designed for regulating gene expression during environmental transitions. PMID:19429616

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

    Directory of Open Access Journals (Sweden)

    John Reich

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

  15. BSAP Can Repress Enhancer Activity by Targeting PU.1 Function

    OpenAIRE

    Maitra, Shanak; Atchison, Michael

    2000-01-01

    PU.1 and BSAP are transcription factors crucial for proper B-cell development. Absence of PU.1 results in loss of B, T, and myeloid cells, while absence of BSAP results in an early block in B-cell differentiation. Both of these proteins bind to the immunoglobulin κ chain 3′ enhancer, which is developmentally regulated during B-cell differentiation. We find here that BSAP can repress 3′ enhancer activity. This repression can occur in plasmacytoma lines or in a non-B-cell line in which the enha...

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

    DEFF Research Database (Denmark)

    Laugesen, Anne; Helin, Kristian

    2014-01-01

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

  17. Functional domains of the human orphan receptor ARP-1/COUP-TFII involved in active repression and transrepression.

    OpenAIRE

    Achatz, G; Hölzl, B; Speckmayer, R; Hauser, C; Sandhofer, F; Paulweber, B.

    1997-01-01

    The orphan receptor ARP-1/COUP-TFII, a member of the chicken ovalbumin upstream promoter transcription factor (COUP-TF) subfamily of nuclear receptors, strongly represses transcriptional activity of numerous genes, including several apolipoprotein-encoding genes. Recently it has been demonstrated that the mechanism by which COUP-TFs reduce transcriptional activity involves active repression and transrepression. To map the domains of ARP-1/COUP-TFII required for repressor activity, a detailed ...

  18. Identification of a Portable Repression Domain and an E1A-Responsive Activation Domain in Pax4: a Possible Role of Pax4 as a Transcriptional Repressor in the Pancreas

    OpenAIRE

    Fujitani, Yoshio; Kajimoto, Yoshitaka; Yasuda, Tetsuyuki; Matsuoka, Taka-aki; Kaneto, Hideaki; Umayahara, Yutaka; Fujita, Noriko; Watada, Hirotaka; Miyazaki, Jun-ichi; Yamasaki, Yoshimitsu; Hori, Masatsugu

    1999-01-01

    Pax4 is a paired-domain (PD)-containing transcription factor which plays a crucial role in pancreatic β/δ-cell development. In this study, we characterized the DNA-binding and transactivation properties of mouse Pax4. Repetitive rounds of PCR-based selection led to identification of the optimal DNA-binding sequences for the PD of Pax4. In agreement with the conservation of the optimal binding sequences among the Pax family transcription factors, Pax4 could bind to the potential binding sites ...

  19. Tandem DNA-bound cAMP-CRP complexes are required for transcriptional repression of the deoP2 promoter by the CytR repressor in Escherichia coli

    DEFF Research Database (Denmark)

    Søgaard-Andersen, Lotte; Møllegaard, N E; Douthwaite, S R; Valentin-Hansen, P

    1990-01-01

    We have studied the deoP2 promoter in Escherichia coli to define features important for its interaction with the CytR repressor. As is characteristic for CytR-regulated promoters, deoP2 encodes tandem binding sites for the activating complex cAMP-CRP. One of these sites, CRP-1, overlaps the -35...... region, and is sufficient for activation; the second site, CRP-2, centred around -93, is indispensable for repression. Here we demonstrate, by means of in vivo titration, that CytR interaction with deoP2 depends not only on CRP-2, but also on CRP-1 and the length and possibly the sequence separating...... these two sites. Also, point mutations in either CRP site reduce or abolish CytR titration; however, no co-operativity is observed in the interaction of CytR with the two CRP binding sites. Furthermore, the reduction in CytR titration parallels the reduction in binding of cAMP-CRP to the mutated CRP...

  20. Genome-Scale CRISPR-Mediated Control of Gene Repression and Activation

    OpenAIRE

    Gilbert, Luke A.; Horlbeck, Max A.; Adamson, Britt; Villalta, Jacqueline E.; Chen, Yuwen; Whitehead, Evan H.; Guimaraes, Carla; Panning, Barbara; Ploegh, Hidde L.; Bassik, Michael C.; Qi, Lei S.; Kampmann, Martin; Weissman, Jonathan S.

    2014-01-01

    While the catalog of mammalian transcripts and their expression levels in different cell types and disease states is rapidly expanding, our understanding of transcript function lags behind. We present a robust technology enabling systematic investigation of the cellular consequences of repressing or inducing individual transcripts. We identify rules for specific targeting of transcriptional repressors (CRISPRi), typically achieving 90–99% knockdown with minimal off-target effects, and activat...

  1. Identification of a new isoform of the human estrogen receptor-alpha (hER-α) that is encoded by distinct transcripts and that is able to repress hER-α activation function 1

    OpenAIRE

    Flouriot, Gilles; Brand, Heike; Denger, Stefanie; Metivier, Raphaël; Kos, Martin; Reid, George; Sonntag-Buck, Vera; Gannon, Frank

    2000-01-01

    A new isoform of the human estrogen receptor-alpha (hER-α) has been identified and characterized. This 46 kDa isoform (hERα46) lacks the N-terminal 173 amino acids present in the previously characterized 66 kDa isoform (hERα66). hERα46 is encoded by a new class of hER-α transcript that lacks the first coding exon (exon 1A) of the ER-α gene. We demonstrated that these Δ1A hER-α transcripts originate from the E and F hER-α promoters and are produced by the splicing of exon 1E directly to exon 2...

  2. Protein sequestration versus Hill-type repression in circadian clock models.

    Science.gov (United States)

    Kim, Jae Kyoung

    2016-08-01

    Circadian (∼24 h) clocks are self-sustained endogenous oscillators with which organisms keep track of daily and seasonal time. Circadian clocks frequently rely on interlocked transcriptional-translational feedback loops to generate rhythms that are robust against intrinsic and extrinsic perturbations. To investigate the dynamics and mechanisms of the intracellular feedback loops in circadian clocks, a number of mathematical models have been developed. The majority of the models use Hill functions to describe transcriptional repression in a way that is similar to the Goodwin model. Recently, a new class of models with protein sequestration-based repression has been introduced. Here, the author discusses how this new class of models differs dramatically from those based on Hill-type repression in several fundamental aspects: conditions for rhythm generation, robust network designs and the periods of coupled oscillators. Consistently, these fundamental properties of circadian clocks also differ among Neurospora, Drosophila, and mammals depending on their key transcriptional repression mechanisms (Hill-type repression or protein sequestration). Based on both theoretical and experimental studies, this review highlights the importance of careful modelling of transcriptional repression mechanisms in molecular circadian clocks. PMID:27444022

  3. Repression of p15INK4b expression by Myc through association with Miz-1

    DEFF Research Database (Denmark)

    Staller, P; Peukert, K; Kiermaier, A;

    2001-01-01

    Deregulated expression of c-myc can induce cell proliferation in established cell lines and in primary mouse embryonic fibroblasts (MEFs), through a combination of both transcriptional activation and repression by Myc. Here we show that a Myc-associated transcription factor, Miz-1, arrests cells ...... p15INK4b messenger RNA in primary cells and are, as a consequence, deficient in immortalization....

  4. The unified theory of repression.

    Science.gov (United States)

    Erdelyi, Matthew Hugh

    2006-10-01

    Repression has become an empirical fact that is at once obvious and problematic. Fragmented clinical and laboratory traditions and disputed terminology have resulted in a Babel of misunderstandings in which false distinctions are imposed (e.g., between repression and suppression) and necessary distinctions not drawn (e.g., between the mechanism and the use to which it is put, defense being just one). "Repression" was introduced by Herbart to designate the (nondefensive) inhibition of ideas by other ideas in their struggle for consciousness. Freud adapted repression to the defensive inhibition of "unbearable" mental contents. Substantial experimental literatures on attentional biases, thought avoidance, interference, and intentional forgetting exist, the oldest prototype being the work of Ebbinghaus, who showed that intentional avoidance of memories results in their progressive forgetting over time. It has now become clear, as clinicians had claimed, that the inaccessible materials are often available and emerge indirectly (e.g., procedurally, implicitly). It is also now established that the Ebbinghaus retention function can be partly reversed, with resulting increases of conscious memory over time (hypermnesia). Freud's clinical experience revealed early on that exclusion from consciousness was effected not just by simple repression (inhibition) but also by a variety of distorting techniques, some deployed to degrade latent contents (denial), all eventually subsumed under the rubric of defense mechanisms ("repression in the widest sense"). Freudian and Bartlettian distortions are essentially the same, even in name, except for motive (cognitive vs. emotional), and experimentally induced false memories and other "memory illusions" are laboratory analogs of self-induced distortions. PMID:17156548

  5. Influence of Catabolite Repression and Inducer Exclusion on the Bistable Behavior of the lac Operon

    OpenAIRE

    Santillán, Moisés; Mackey, Michael C.

    2004-01-01

    A mathematical model of the lac operon which includes all of the known regulatory mechanisms, including external-glucose-dependent catabolite repression and inducer exclusion, as well as the time delays inherent to transcription and translation, is presented. With this model we investigate the influence of external glucose, by means of catabolite repression and the regulation of lactose uptake, on the bistable behavior of this system.

  6. Multiple mechanisms mediate glucose repression of the yeast GAL1 gene.

    OpenAIRE

    Lamphier, M S; Ptashne, M

    1992-01-01

    Several mechanisms contribute to the glucose repression of the GAL1 gene in Saccharomyces cerevisiae. We show that one mechanism involves the transcriptional down-regulation of the GAL4 gene and a second requires the GAL80 gene. We also examine the contribution of cis-acting negative elements in the GAL1 promoter to glucose repression. In an otherwise wild-type strain disruption of any one of these three mechanisms alleviates repression of GAL1 only 2- to 4-fold. However, in the absence of th...

  7. Gene Repression in Haloarchaea Using the CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)-Cas I-B System*

    Science.gov (United States)

    Stachler, Aris-Edda; Marchfelder, Anita

    2016-01-01

    The clustered regularly interspaced short palindromic repeats (CRISPR)-Cas system is used by bacteria and archaea to fend off foreign genetic elements. Since its discovery it has been developed into numerous applications like genome editing and regulation of transcription in eukaryotes and bacteria. For archaea currently no tools for transcriptional repression exist. Because molecular biology analyses in archaea become more and more widespread such a tool is vital for investigating the biological function of essential genes in archaea. Here we use the model archaeon Haloferax volcanii to demonstrate that its endogenous CRISPR-Cas system I-B can be harnessed to repress gene expression in archaea. Deletion of cas3 and cas6b genes results in efficient repression of transcription. crRNAs targeting the promoter region reduced transcript levels down to 8%. crRNAs targeting the reading frame have only slight impact on transcription. crRNAs that target the coding strand repress expression only down to 88%, whereas crRNAs targeting the template strand repress expression down to 8%. Repression of an essential gene results in reduction of transcription levels down to 22%. Targeting efficiencies can be enhanced by expressing a catalytically inactive Cas3 mutant. Genes can be targeted on plasmids or on the chromosome, they can be monocistronic or part of a polycistronic operon. PMID:27226589

  8. Polycomb repressive complex 1 controls uterine decidualization.

    Science.gov (United States)

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

    2016-01-01

    Uterine stromal cell decidualization is an essential part of the reproductive process. Decidual tissue development requires a highly regulated control of the extracellular tissue remodeling; however the mechanism of this regulation remains unknown. Through systematic expression studies, we detected that Cbx4/2, Rybp, and Ring1B [components of polycomb repressive complex 1 (PRC1)] are predominantly utilized in antimesometrial decidualization with polyploidy. Immunofluorescence analyses revealed that PRC1 members are co-localized with its functional histone modifier H2AK119ub1 (mono ubiquitination of histone-H2A at lysine-119) in polyploid cell. A potent small-molecule inhibitor of Ring1A/B E3-ubiquitin ligase or siRNA-mediated suppression of Cbx4 caused inhibition of H2AK119ub1, in conjunction with perturbation of decidualization and polyploidy development, suggesting a role for Cbx4/Ring1B-containing PRC1 in these processes. Analyses of genetic signatures by RNA-seq studies showed that the inhibition of PRC1 function affects 238 genes (154 up and 84 down) during decidualization. Functional enrichment analyses identified that about 38% genes primarily involved in extracellular processes are specifically targeted by PRC1. Furthermore, ~15% of upregulated genes exhibited a significant overlap with the upregulated Bmp2 null-induced genes in mice. Overall, Cbx4/Ring1B-containing PRC1 controls decidualization via regulation of extracellular gene remodeling functions and sheds new insights into underlying molecular mechanism(s) through transcriptional repression regulation. PMID:27181215

  9. Violent repression of environmental protests.

    Science.gov (United States)

    Poulos, Helen M; Haddad, Mary Alice

    2016-01-01

    As global sea levels and natural resource demands rise, people around the world are increasingly protesting environmental threats to their lives and livelihoods. What are the conditions under which these peaceful environmental protests are violently repressed? This paper uses the random forest algorithm to conduct an event analysis of grassroots environmental protests around the world. Utilizing a database of 175 grassroots environmental protests, we found that: (1) a large proportion (37 %) of the protests involved violent repression; (2) most of the violence (56 %) was directed against marginalized groups; and (3) violence was geographically concentrated the global south in Latin America and Asia. The primary predictors of violence were political empowerment, GDP per capita, industry type, the presence of marginalized groups, and geographic region. Our analysis reveals a complex relationship between governance, resource extraction, and international funding that often resulted in human rights violations against marginalized groups. PMID:27026924

  10. Mechanism and Role of SOX2 Repression in Seminoma: Relevance to Human Germline Specification.

    Science.gov (United States)

    Kushwaha, Ritu; Jagadish, Nirmala; Kustagi, Manjunath; Mendiratta, Geetu; Seandel, Marco; Soni, Rekha; Korkola, James E; Thodima, Venkata; Califano, Andrea; Bosl, George J; Chaganti, R S K

    2016-05-10

    Human male germ cell tumors (GCTs) are derived from primordial germ cells (PGCs). The master pluripotency regulator and neuroectodermal lineage effector transcription factor SOX2 is repressed in PGCs and the seminoma (SEM) subset of GCTs. The mechanism of SOX2 repression and its significance to GC and GCT development currently are not understood. Here, we show that SOX2 repression in SEM-derived TCam-2 cells is mediated by the Polycomb repressive complex (PcG) and the repressive H3K27me3 chromatin mark that are enriched at its promoter. Furthermore, SOX2 repression in TCam-2 cells can be abrogated by recruitment of the constitutively expressed H3K27 demethylase UTX to the SOX2 promoter through retinoid signaling, leading to expression of neuronal and other lineage genes. SOX17 has been shown to initiate human PGC specification, with its target PRDM1 suppressing mesendodermal genes. Our results are consistent with a role for SOX2 repression in normal germline development by suppressing neuroectodermal genes. PMID:27132888

  11. Mechanism and Role of SOX2 Repression in Seminoma: Relevance to Human Germline Specification

    Directory of Open Access Journals (Sweden)

    Ritu Kushwaha

    2016-05-01

    Full Text Available Human male germ cell tumors (GCTs are derived from primordial germ cells (PGCs. The master pluripotency regulator and neuroectodermal lineage effector transcription factor SOX2 is repressed in PGCs and the seminoma (SEM subset of GCTs. The mechanism of SOX2 repression and its significance to GC and GCT development currently are not understood. Here, we show that SOX2 repression in SEM-derived TCam-2 cells is mediated by the Polycomb repressive complex (PcG and the repressive H3K27me3 chromatin mark that are enriched at its promoter. Furthermore, SOX2 repression in TCam-2 cells can be abrogated by recruitment of the constitutively expressed H3K27 demethylase UTX to the SOX2 promoter through retinoid signaling, leading to expression of neuronal and other lineage genes. SOX17 has been shown to initiate human PGC specification, with its target PRDM1 suppressing mesendodermal genes. Our results are consistent with a role for SOX2 repression in normal germline development by suppressing neuroectodermal genes.

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

    Directory of Open Access Journals (Sweden)

    Chen U Zhang

    2014-08-01

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

  13. Hormone-induced repression of genes requires BRG1-mediated H1.2 deposition at target promoters.

    Science.gov (United States)

    Nacht, Ana Silvina; Pohl, Andy; Zaurin, Roser; Soronellas, Daniel; Quilez, Javier; Sharma, Priyanka; Wright, Roni H; Beato, Miguel; Vicent, Guillermo P

    2016-08-15

    Eukaryotic gene regulation is associated with changes in chromatin compaction that modulate access to DNA regulatory sequences relevant for transcriptional activation or repression. Although much is known about the mechanism of chromatin remodeling in hormonal gene activation, how repression is accomplished is much less understood. Here we report that in breast cancer cells, ligand-activated progesterone receptor (PR) is directly recruited to transcriptionally repressed genes involved in cell proliferation along with the kinases ERK1/2 and MSK1. PR recruits BRG1 associated with the HP1γ-LSD1 complex repressor complex, which is further anchored via binding of HP1γ to the H3K9me3 signal deposited by SUV39H2. In contrast to what is observed during gene activation, only BRG1 and not the BAF complex is recruited to repressed promoters, likely due to local enrichment of the pioneer factor FOXA1. BRG1 participates in gene repression by interacting with H1.2, facilitating its deposition and stabilizing nucleosome positioning around the transcription start site. Our results uncover a mechanism of hormone-dependent transcriptional repression and a novel role for BRG1 in progestin regulation of breast cancer cell growth. PMID:27390128

  14. Role of the proto-oncogene Pokemon in cellular transformation and ARF repression.

    Science.gov (United States)

    Maeda, Takahiro; Hobbs, Robin M; Merghoub, Taha; Guernah, Ilhem; Zelent, Arthur; Cordon-Cardo, Carlos; Teruya-Feldstein, Julie; Pandolfi, Pier Paolo

    2005-01-20

    Aberrant transcriptional repression through chromatin remodelling and histone deacetylation has been postulated to represent a driving force underlying tumorigenesis because histone deacetylase inhibitors have been found to be effective in cancer treatment. However, the molecular mechanisms by which transcriptional derepression would be linked to tumour suppression are poorly understood. Here we identify the transcriptional repressor Pokemon (encoded by the Zbtb7 gene) as a critical factor in oncogenesis. Mouse embryonic fibroblasts lacking Zbtb7 are completely refractory to oncogene-mediated cellular transformation. Conversely, Pokemon overexpression leads to overt oncogenic transformation both in vitro and in vivo in transgenic mice. Pokemon can specifically repress the transcription of the tumour suppressor gene ARF through direct binding. We find that Pokemon is aberrantly overexpressed in human cancers and that its expression levels predict biological behaviour and clinical outcome. Pokemon's critical role in cellular transformation makes it an attractive target for therapeutic intervention. PMID:15662416

  15. A bifunctional O-GlcNAc transferase governs flagellar motility through anti-repression

    OpenAIRE

    Shen, Aimee; Kamp, Heather D.; Gründling, Angelika; Darren E Higgins

    2006-01-01

    Flagellar motility is an essential mechanism by which bacteria adapt to and survive in diverse environments. Although flagella confer an advantage to many bacterial pathogens for colonization during infection, bacterial flagellins also stimulate host innate immune responses. Consequently, many bacterial pathogens down-regulate flagella production following initial infection. Listeria monocytogenes is a facultative intracellular pathogen that represses transcription of flagellar motility genes...

  16. 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...

  17. Gene Silencing Triggers Polycomb Repressive Complex 2 Recruitment to CpG Islands Genome Wide

    DEFF Research Database (Denmark)

    Riising, Eva Madi; Vacher-Comet, Itys; Leblanc, Benjamin Olivier;

    2014-01-01

    Polycomb group (PcG) proteins are required for normal differentiation and development and are frequently deregulated in cancer. PcG proteins are involved in gene silencing; however, their role in initiation and maintenance of transcriptional repression is not well defined. Here, we show that knoc...... by default to nontranscribed CGI genes to maintain their silenced state and to protect cell identity....

  18. Gibberellins repress photomorphogenesis in darkness.

    Science.gov (United States)

    Alabadí, David; Gil, Joan; Blázquez, Miguel A; García-Martínez, José L

    2004-03-01

    Plants undergo two different developmental programs depending on whether they are growing in darkness (skotomorphogenesis) or in the presence of light (photomorphogenesis). It has been proposed that the latter is the default pathway followed by many plants after germination and before the seedling emerges from soil. The transition between the two pathways is tightly regulated. The conserved COP1-based complex is central in the light-dependent repression of photomorphogenesis in darkness. Besides this control, hormones such as brassinosteroids (BRs), cytokinins, auxins, or ethylene also have been shown to regulate, to different extents, this developmental switch. In the present work, we show that the hormone gibberellin (GA) widely participates in this regulation. Studies from Arabidopsis show that both chemical and genetic reductions of endogenous GA levels partially derepress photomorphogenesis in darkness. This is based both on morphological phenotypes, such as hypocotyl elongation and hook and cotyledon opening, and on molecular phenotypes, such as misregulation of the light-controlled genes CAB2 and RbcS. Genetic studies indicate that the GA signaling elements GAI and RGA participate in these responses. Our results also suggest that GA regulation of this response partially depends on BRs. This regulation seems to be conserved across species because lowering endogenous GA levels in pea (Pisum sativum) induces full de-etiolation in darkness, which is not reverted by BR application. Our results, therefore, attribute an important role for GAs in the establishment of etiolated growth and in repression of photomorphogenesis. PMID:14963246

  19. Snai1 represses Nanog to promote embryonic stem cell differentiation

    Directory of Open Access Journals (Sweden)

    F. Galvagni

    2015-06-01

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

  20. Translational Repression of NhaR, a Novel Pathway for Multi-Tier Regulation of Biofilm Circuitry by CsrA

    OpenAIRE

    Pannuri, Archana; Yakhnin, Helen; Vakulskas, Christopher A.; Edwards, Adrianne N.; Babitzke, Paul; Romeo, Tony

    2012-01-01

    The RNA binding protein CsrA (RsmA) represses biofilm formation in several proteobacterial species. In Escherichia coli, it represses the production of the polysaccharide adhesin poly-β-1,6-N-acetyl-d-glucosamine (PGA) by binding to the pgaABCD mRNA leader, inhibiting pgaA translation, and destabilizing this transcript. In addition, CsrA represses genes responsible for the synthesis of cyclic di-GMP, an activator of PGA production. Here we determined that CsrA also represses NhaR, a LysR-type...

  1. In silico finding of Putative Cis-Acting Elements for the Tethering of Polycomb Repressive Complex2 in Human Genome

    OpenAIRE

    Hajjari, Mohammadreza; Behmanesh, Mehrdad; Jahani, Mohammad Mehdi

    2014-01-01

    Polycomb Repressive Complex2 maintains a predetermined state of transcription which constitutes a cellular memory stable over many cell divisions. Since this complex acts through the regulation of chromatin structure, it is important to understand how it is recruited to chromatin. The specific target sequences of this complex such as PRE (polycomb repressive element) have not been completely recognized in human genome. In this study, we have compared the target sequences of this complex with ...

  2. Multiple Gene Repression in Cyanobacteria Using CRISPRi.

    Science.gov (United States)

    Yao, Lun; Cengic, Ivana; Anfelt, Josefine; Hudson, Elton P

    2016-03-18

    We describe the application of clustered regularly interspaced short palindromic repeats interference (CRISPRi) for gene repression in the model cyanobacterium Synechcocystis sp. PCC 6803. The nuclease-deficient Cas9 from the type-II CRISPR/Cas of Streptrococcus pyogenes was used to repress green fluorescent protein (GFP) to negligible levels. CRISPRi was also used to repress formation of carbon storage compounds polyhydroxybutryate (PHB) and glycogen during nitrogen starvation. As an example of the potential of CRISPRi for basic and applied cyanobacteria research, we simultaneously knocked down 4 putative aldehyde reductases and dehydrogenases at 50-95% repression. This work also demonstrates that tightly repressed promoters allow for inducible and reversible CRISPRi in cyanobacteria. PMID:26689101

  3. Structure and regulatory function of plant transcription factors

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The expression of inducible genes in plants is regulated byspecific transcription factors at the transcriptional level. A typical transcription factor usually contains a DNA-binding domain, a transcription regulation domain, a dimerization site and a nuclear localization domain. These functional domains define the characteristic, localization and regulatory role of a transcription factor. Transcription factors recognize and bind to specific cis-acting elements or interact with other proteins, and then activate or repress the transcription of target genes by their functional domains. In recent years, elucidation on the structure and function of transcription factors has become an important subject in plant molecular biology.

  4. Tumor FOXP3 represses the expression of long noncoding RNA 7SL.

    Science.gov (United States)

    Yang, Yanhui; Cheng, Jingli; Ren, Huizhu; Zhao, Hui; Gong, Wei; Shan, Chunyan

    2016-04-01

    The long noncoding RNA 7SL was over-expressed in tumor cells to promote cell growth through repressing translation of P53. However, the regulatory mechanism of 7SL remains to be defined. FOXP3 was identified as a suppressor in several tumors in addition to be a marker of regulatory T cells. In this study, we detected that over-expression of FOXP3 repressed the transcription of 7SL RNA and contributed to inhibiting tumor growth. Knock down of FOXP3 in MCF-10A normal mammary breast cells up-regulated the transcription of 7SL RNA. Chromatin Immuno-precipitation (ChIP) analysis showed that FOXP3 directly bound to the Forkhead/HNF-3 domain DNA binding sites (-789 to -795) relative to the transcription start site. Meanwhile, Luciferase analysis showed that FOXP3 repressed the full-length 7SL promoter activity, but this suppressive effect was reversed after mutation of the FOXP3 binding site. Further studies showed that FOXP3 promoted the expression of P53 at translational levels through repressing 7SL RNA. In conclusion, this study suggests that 7SL RNA is a direct target of FOXP3 and may be involved in the formation of FOXP3/P53 feedback loop. PMID:26718402

  5. RUNX1 represses the erythroid gene expression program during megakaryocytic differentiation.

    Science.gov (United States)

    Kuvardina, Olga N; Herglotz, Julia; Kolodziej, Stephan; Kohrs, Nicole; Herkt, Stefanie; Wojcik, Bartosch; Oellerich, Thomas; Corso, Jasmin; Behrens, Kira; Kumar, Ashok; Hussong, Helge; Urlaub, Henning; Koch, Joachim; Serve, Hubert; Bonig, Halvard; Stocking, Carol; Rieger, Michael A; Lausen, Jörn

    2015-06-01

    The activity of antagonizing transcription factors represents a mechanistic paradigm of bidirectional lineage-fate control during hematopoiesis. At the megakaryocytic/erythroid bifurcation, the cross-antagonism of krueppel-like factor 1 (KLF1) and friend leukemia integration 1 (FLI1) has such a decisive role. However, how this antagonism is resolved during lineage specification is poorly understood. We found that runt-related transcription factor 1 (RUNX1) inhibits erythroid differentiation of murine megakaryocytic/erythroid progenitors and primary human CD34(+) progenitor cells. We show that RUNX1 represses the erythroid gene expression program during megakaryocytic differentiation by epigenetic repression of the erythroid master regulator KLF1. RUNX1 binding to the KLF1 locus is increased during megakaryocytic differentiation and counterbalances the activating role of T-cell acute lymphocytic leukemia 1 (TAL1). We found that corepressor recruitment by RUNX1 contributes to a block of the KLF1-dependent erythroid gene expression program. Our data indicate that the repressive function of RUNX1 influences the balance between erythroid and megakaryocytic differentiation by shifting the balance between KLF1 and FLI1 in the direction of FLI1. Taken together, we show that RUNX1 is a key player within a network of transcription factors that represses the erythroid gene expression program. PMID:25911237

  6. A TATA sequence-dependent transcriptional repressor activity associated with mammalian transcription factor IIA.

    OpenAIRE

    Aso, T.; Serizawa, H; Conaway, R C; Conaway, J W

    1994-01-01

    In the process of characterizing cellular proteins that modulate basal transcription by RNA polymerase II, we identified a novel repressor activity specific for promoters containing consensus TATA boxes. This activity strongly represses TATA-binding protein (TBP)-dependent transcription initiation from core promoter elements containing a consensus TATA sequence, but activates TBP-dependent transcription from core promoter elements lacking a consensus TATA sequence. Purification of this activi...

  7. ATF3 represses PPARγ expression and inhibits adipocyte differentiation

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-11-07

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

  8. Repression of arterial genes in hemogenic endothelium is sufficient for haematopoietic fate acquisition.

    Science.gov (United States)

    Lizama, Carlos O; Hawkins, John S; Schmitt, Christopher E; Bos, Frank L; Zape, Joan P; Cautivo, Kelly M; Borges Pinto, Hugo; Rhyner, Alexander M; Yu, Hui; Donohoe, Mary E; Wythe, Joshua D; Zovein, Ann C

    2015-01-01

    Changes in cell fate and identity are essential for endothelial-to-haematopoietic transition (EHT), an embryonic process that generates the first adult populations of haematopoietic stem cells (HSCs) from hemogenic endothelial cells. Dissecting EHT regulation is a critical step towards the production of in vitro derived HSCs. Yet, we do not know how distinct endothelial and haematopoietic fates are parsed during the transition. Here we show that genes required for arterial identity function later to repress haematopoietic fate. Tissue-specific, temporally controlled, genetic loss of arterial genes (Sox17 and Notch1) during EHT results in increased production of haematopoietic cells due to loss of Sox17-mediated repression of haematopoietic transcription factors (Runx1 and Gata2). However, the increase in EHT can be abrogated by increased Notch signalling. These findings demonstrate that the endothelial haematopoietic fate switch is actively repressed in a population of endothelial cells, and that derepression of these programs augments haematopoietic output. PMID:26204127

  9. Pluripotency factor binding and Tsix expression act synergistically to repress Xist in undifferentiated embryonic stem cells

    Directory of Open Access Journals (Sweden)

    Nesterova Tatyana B

    2011-10-01

    Full Text Available Abstract Background Expression of Xist, the master regulator of X chromosome inactivation, is extinguished in pluripotent cells, a process that has been linked to programmed X chromosome reactivation. The key pluripotency transcription factors Nanog, Oct4 and Sox2 are implicated in Xist gene extinction, at least in part through binding to an element located in Xist intron 1. Other pathways, notably repression by the antisense RNA Tsix, may also be involved. Results Here we employ a transgene strategy to test the role of the intron 1 element and Tsix in repressing Xist in ES cells. We find that deletion of the intron 1 element causes a small increase in Xist expression and that simultaneous deletion of the antisense regulator Tsix enhances this effect. Conclusion We conclude that Tsix and pluripotency factors act synergistically to repress Xist in undifferentiated embryonic stem cells. Double mutants do not exhibit maximal levels of Xist expression, indicating that other pathways also play a role.

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

    Directory of Open Access Journals (Sweden)

    Francesca Corlazzoli

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

  11. Repression by RB1 characterizes genes involved in the penultimate stage of erythroid development.

    Science.gov (United States)

    Zhang, Ji; Loyd, Melanie R; Randall, Mindy S; Morris, John J; Shah, Jayesh G; Ney, Paul A

    2015-01-01

    Retinoblastoma-1 (RB1), and the RB1-related proteins p107 and p130, are key regulators of the cell cycle. Although RB1 is required for normal erythroid development in vitro, it is largely dispensable for erythropoiesis in vivo. The modest phenotype caused by RB1 deficiency in mice raises questions about redundancy within the RB1 family, and the role of RB1 in erythroid differentiation. Here we show that RB1 is the major pocket protein that regulates terminal erythroid differentiation. Erythroid cells lacking all pocket proteins exhibit the same cell cycle defects as those deficient for RB1 alone. RB1 has broad repressive effects on gene transcription in erythroid cells. As a group, RB1-repressed genes are generally well expressed but downregulated at the final stage of erythroid development. Repression correlates with E2F binding, implicating E2Fs in the recruitment of RB1 to repressed genes. Merging differential and time-dependent changes in expression, we define a group of approximately 800 RB1-repressed genes. Bioinformatics analysis shows that this list is enriched for terms related to the cell cycle, but also for terms related to terminal differentiation. Some of these have not been previously linked to RB1. These results expand the range of processes potentially regulated by RB1, and suggest that a principal role of RB1 in development is coordinating the events required for terminal differentiation. PMID:26397180

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

    International Nuclear Information System (INIS)

    Highlights: • We designed TALE–SID fusion proteins to target AXIN2 and MYC. • TALE–SIDs bound the chromosomal AXIN2 and MYC genes and repressed their expression. • TALE–SIDs repress β-cateninS45F-dependent AXIN2 and MYC transcription. - Abstract: Designer TALEs (dTALEs) are chimeric transcription factors that can be engineered to regulate gene expression in mammalian cells. Whether dTALEs can block gene transcription downstream of signal transduction cascades, however, has yet to be fully explored. Here we tested whether dTALEs can be used to target genes whose expression is controlled by Wnt/β-catenin signaling. TALE DNA binding domains were engineered to recognize sequences adjacent to Wnt responsive enhancer elements (WREs) that control expression of axis inhibition protein 2 (AXIN2) and c-MYC (MYC). These custom DNA binding domains were linked to the mSin3A interaction domain (SID) to generate TALE–SID chimeric repressors. The TALE–SIDs repressed luciferase reporter activity, bound their genomic target sites, and repressed AXIN2 and MYC expression in HEK293 cells. We generated a novel HEK293 cell line to determine whether the TALE–SIDs could function downstream of oncogenic Wnt/β-catenin signaling. Treating these cells with doxycycline and tamoxifen stimulates nuclear accumulation of a stabilized form of β-catenin found in a subset of colorectal cancers. The TALE–SIDs repressed AXIN2 and MYC expression in these cells, which suggests that dTALEs could offer an effective therapeutic strategy for the treatment of colorectal cancer

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-04-18

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

  14. Repression: Finding Our Way in the Maze of Concepts

    OpenAIRE

    Garssen, Bert

    2007-01-01

    Repression is associated in the literature with terms such as non-expression, emotional control, rationality, anti-emotionality, defensiveness and restraint. Whether these terms are synonymous with repression, indicate a variation, or are essentially different from repression is uncertain. To clarify this obscured view on repression, this paper indicates the similarities and differences between these concepts. Repression is the general term that is used to describe the tendency to inhibit the...

  15. The HTLV-1 Tax oncoprotein represses Ku80 gene expression.

    Science.gov (United States)

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

    2011-07-20

    The HTLV-I oncoprotein Tax interferes with DNA double strand break repair. Since non-homologous end joining (NHEJ) is a major pathway used to repair DNA double strand breaks we examined the effect of Tax on this pathway, with particular interest in the expression and function of Ku80, a critical component of the NHEJ pathway. Tax expression decreased Ku80 mRNA and protein levels, and repressed transcription from the Ku80 promoter. Conversely, Ku80 mRNA increased following siRNA knockdown of Tax in HTLV-I infected cells. Tax expression was associated with an elevated number of micronuclei and nucleoplasmic bridges, hallmarks of improper DNA double strand break repair. Our studies identified Tax as a transcriptional repressor of Ku80 that correlates with decreased DNA repair function. The reduction of Ku80 transcription by Tax may deplete the cell of an essential DNA break binding protein, resulting in reduced repair of DNA double strand breaks and accumulation genomic mutations. PMID:21571351

  16. DELLA proteins interact with FLC to repress flowering transition

    Institute of Scientific and Technical Information of China (English)

    Hongwei Guo

    2016-01-01

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

  17. p53 represses human papillomavirus type 16 DNA replication via the viral E2 protein

    OpenAIRE

    Morgan Iain M; Taylor Ewan R; Kowalczyk Anna M; Brown Craig; Gaston Kevin

    2008-01-01

    Abstract Background Human papillomavirus (HPV) DNA replication can be inhibited by the cellular tumour suppressor protein p53. However, the mechanism through which p53 inhibits viral replication and the role that this might play in the HPV life cycle are not known. The papillomavirus E2 protein is required for efficient HPV DNA replication and also regulates viral gene expression. E2 represses transcription of the HPV E6 and E7 oncogenes and can thereby modulate indirectly host cell prolifera...

  18. Smad4 suppresses the tumorigenesis and aggressiveness of neuroblastoma through repressing the expression of heparanase

    Science.gov (United States)

    Qu, Hongxia; Zheng, Liduan; Jiao, Wanju; Mei, Hong; Li, Dan; Song, Huajie; Fang, Erhu; Wang, Xiaojing; Li, Shiwang; Huang, Kai; Tong, Qiangsong

    2016-01-01

    Heparanase (HPSE) is the only endo-β-D-glucuronidase that is correlated with the progression of neuroblastoma (NB), the most common extracranial malignancy in childhood. However, the mechanisms underlying HPSE expression in NB still remain largely unknown. Herein, through analyzing cis-regulatory elements and mining public microarray datasets, we identified SMAD family member 4 (Smad4) as a crucial transcription regulator of HPSE in NB. We demonstrated that Smad4 repressed the HPSE expression at the transcriptional levels in NB cells. Mechanistically, Smad4 suppressed the HPSE expression through directly binding to its promoter and repressing the lymphoid enhancer binding factor 1 (LEF1)-facilitated transcription of HPSE via physical interaction. Gain- and loss-of-function studies demonstrated that Smad4 inhibited the growth, invasion, metastasis, and angiogenesis of NB cells in vitro and in vivo. Restoration of HPSE expression prevented the NB cells from changes in these biological features induced by Smad4. In clinical NB specimens, Smad4 was under-expressed and inversely correlated with HPSE levels, while LEF1 was highly expressed and positively correlated with HPSE expression. Patients with high Smad4 expression, low LEF1 or HPSE levels had greater survival probability. These results demonstrate that Smad4 suppresses the tumorigenesis and aggressiveness of NB through repressing the HPSE expression. PMID:27595937

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

    OpenAIRE

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

    2014-01-01

    The transcription factor Tal1 is a critical activator or repressor of gene expression in hematopoiesis and leukaemia. The mechanism by which Tal1 differentially influences transcription of distinct genes is not fully understood. Here we show that Tal1 interacts with the peptidylarginine deiminase IV (PADI4). We demonstrate that PADI4 can act as an epigenetic coactivator through influencing H3R2me2a. At the Tal1/PADI4 target gene IL6ST the repressive H3R2me2a mark triggered by PRMT6 is counter...

  20. Repression of Runx2 by Androgen Receptor (AR) in Osteoblasts and Prostate Cancer Cells: AR Binds Runx2 and Abrogates Its Recruitment to DNA

    OpenAIRE

    Baniwal, Sanjeev K.; Khalid, Omar; Sir, Donna; Buchanan, Grant; Coetzee, Gerhard A.; Frenkel, Baruch

    2009-01-01

    Runx2 and androgen receptor (AR) are master transcription factors with pivotal roles in bone metabolism and prostate cancer (PCa). We dissected AR-mediated repression of Runx2 in dihydrotestosterone (DHT)-treated osteoblastic and PCa cells using reporter assays and endogenous Runx2 target genes. Repression required DHT, but not AR’s transactivation function, and was associated with nuclear colocalization of the two proteins. Runx2 and AR coimmunoprecipitated and interacted directly in glutath...

  1. Glucose-induced repression of PPARalpha gene expression in pancreatic beta-cells involves PP2A activation and AMPK inactivation

    DEFF Research Database (Denmark)

    Ravnskjaer, Kim; Boergesen, Michael; Dalgaard, Louise T;

    2006-01-01

    mechanism underlying this transcriptional repression by glucose remains unclear. Here we report that glucose-induced repression of PPARalpha gene expression in INS-1E cells is independent of beta-cell excitation and insulin secretion but requires activation of protein phosphatase 2A in a process involving...... AMPKalpha1 using RNAi suppressed PPARalpha expression, thereby mimicking the effect of glucose. These results indicate that activation of protein phosphatase 2A and subsequent inactivation of AMPK is necessary for glucose repression of PPARalpha expression in pancreatic beta-cells....

  2. Prdm5 Regulates Collagen Gene Transcription by Association with RNA Polymerase II in Developing Bone

    DEFF Research Database (Denmark)

    Galli, Giorgio Giacomo; Honnens de Lichtenberg, Kristian; Carrara, Matteo;

    2012-01-01

    PRDM family members are transcriptional regulators involved in tissue specific differentiation. PRDM5 has been reported to predominantly repress transcription, but a characterization of its molecular functions in a relevant biological context is lacking. We demonstrate here that Prdm5 is highly e...... transcriptional program necessary to the proper assembly of osteoblastic extracellular matrix....

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

    International Nuclear Information System (INIS)

    Highlights: ► Corepressor Alien interacts with histone methyltransferase ESET in vivo. ► Alien/ESET complex is recruited to nTRE of T3-responsive gene by liganded TRβ1. ► ESET-mediated H3K9 methylation is required for liganded TRβ1-repressed transcription. ► ESET is involved in T3-repressed G1/S phase transition and proliferation. -- Abstract: The ligand-bound thyroid hormone receptor (TR) is known to repress via a negative TRE (nTRE) the expression of E2F1, a key transcription factor that controls the G1/S phase transition. Alien has been identified as a novel interacting factor of E2F1 and acts as a corepressor of E2F1. The detailed molecular mechanism by which Alien inhibits E2F1 gene expression remains unclear. Here, we report that the histone H3 lysine 9 (H3K9) methyltransferase (HMT) ESET is an integral component of the corepressor Alien complex and the Alien/ESET complex is recruited to both sites, the E2F1 and the nTRE site of the E2F1 gene while the recruitment to the negative thyroid hormone response element (nTRE) is induced by the ligand-bound TRβ1 within the E2F1 gene promoter. We show that, overexpression of ESET promotes, whereas knockdown of ESET releases, the inhibition of TRβ1-regulated gene transcription upon T3 stimulation; and H3K9 methylation is required for TRβ1-repressed transcription. Furthermore, depletion of ESET impairs thyroid hormone-repressed proliferation as well as the G1/S transition of the cell cycle. Taken together, our data indicate that ESET is involved in TRβ1-mediated transcription repression and provide a molecular basis of thyroid hormone-induced repression of proliferation.

  4. Nitrogen Catabolite Repression in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Hofman-Bang, H Jacob Peider

    1999-01-01

    In Saccharomyces cerevisiae the expression of all known nitrogen catabolite pathways are regulated by four regulators known as Gln3, Gat1, Da180, and Deh1. This is known as nitrogen catabolite repression (NCR). They bind to motifs in the promoter region to the consensus sequence S' GATAA 3'. Gln3...

  5. Noise in transcription negative feedback loops: simulation and experimental analysis

    OpenAIRE

    Dublanche, Yann; Michalodimitrakis, Konstantinos; Kümmerer, Nico; Foglierini, Mathilde; Serrano, Luis

    2006-01-01

    Negative feedback loops have been invoked as a way to control and decrease transcriptional noise. Here, we have built three circuits to test the effect of negative feedback loops on transcriptional noise of an autoregulated gene encoding a transcription factor (TF) and a downstream gene (DG), regulated by this TF. Experimental analysis shows that self-repression decreases noise compared to expression from a non-regulated promoter. Interestingly enough, we find that noise minimization by negat...

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

    Science.gov (United States)

    Martin, David; Kim, Yung-Hae; Sever, Dror; Mao, Chai-An; Haefliger, Jacques-Antoine; Grapin-Botton, Anne

    2015-09-15

    To contribute to devise successful beta-cell differentiation strategies for the cure of Type 1 diabetes we sought to uncover barriers that restrict endocrine fate acquisition by studying the role of the transcriptional repressor REST in the developing pancreas. Rest expression is prevented in neurons and in endocrine cells, which is necessary for their normal function. During development, REST represses a subset of genes in the neuronal differentiation program and Rest is down-regulated as neurons differentiate. Here, we investigate the role of REST in the differentiation of pancreatic endocrine cells, which are molecularly close to neurons. We show that Rest is widely expressed in pancreas progenitors and that it is down-regulated in differentiated endocrine cells. Sustained expression of REST in Pdx1(+) progenitors impairs the differentiation of endocrine-committed Neurog3(+) progenitors, decreases beta and alpha cell mass by E18.5, and triggers diabetes in adulthood. Conditional inactivation of Rest in Pdx1(+) progenitors is not sufficient to trigger endocrine differentiation but up-regulates a subset of differentiation genes. Our results show that the transcriptional repressor REST is active in pancreas progenitors where it gates the activation of part of the beta cell differentiation program. PMID:26156633

  7. Conservation of uORF repressiveness and sequence features in mouse, human and zebrafish.

    Science.gov (United States)

    Chew, Guo-Liang; Pauli, Andrea; Schier, Alexander F

    2016-01-01

    Upstream open reading frames (uORFs) are ubiquitous repressive genetic elements in vertebrate mRNAs. While much is known about the regulation of individual genes by their uORFs, the range of uORF-mediated translational repression in vertebrate genomes is largely unexplored. Moreover, it is unclear whether the repressive effects of uORFs are conserved across species. To address these questions, we analyse transcript sequences and ribosome profiling data from human, mouse and zebrafish. We find that uORFs are depleted near coding sequences (CDSes) and have initiation contexts that diminish their translation. Linear modelling reveals that sequence features at both uORFs and CDSes modulate the translation of CDSes. Moreover, the ratio of translation over 5' leaders and CDSes is conserved between human and mouse, and correlates with the number of uORFs. These observations suggest that the prevalence of vertebrate uORFs may be explained by their conserved role in repressing CDS translation. PMID:27216465

  8. The N-CoR/Histone Deacetylase 3 Complex Is Required for Repression by Thyroid Hormone Receptor

    OpenAIRE

    Ishizuka, Takahiro; Lazar, Mitchell A.

    2003-01-01

    Nuclear receptor corepressors (N-CoR) and silencing mediator for retinoid and thyroid receptors (SMRT) have both been implicated in thyroid hormone receptor (TR)-mediated repression. Here we show that endogenous N-CoR, TBL1, and histone deacetylase 3 (HDAC3), but not HDAC1, -2, or -4, are recruited to a stably integrated reporter gene repressed by unliganded TR as well as the orphan receptor RevErb. Unliganded TR also recruits this complex to a transiently transfected reporter, and transcript...

  9. The Escherichia coli OxyS regulatory RNA represses fhlA translation by blocking ribosome binding.

    OpenAIRE

    Altuvia, S; Zhang, A.; Argaman, L; Tiwari, A; Storz, G.

    1998-01-01

    OxyS is a small untranslated RNA which is induced in response to oxidative stress in Escherichia coli. This novel RNA acts as a global regulator to activate or repress the expression of as many as 40 genes, including the fhlA-encoded transcriptional activator and the rpoS-encoded sigma(s) subunit of RNA polymerase. Deletion analysis of OxyS showed that different domains of the small RNA are required for the regulation of fhlA and rpoS. We examined the mechanism of OxyS repression of fhlA and ...

  10. Involvement of sigmaS accumulation in repression of the flhDC operon in acidic phospholipid-deficient mutants of Escherichia coli.

    Science.gov (United States)

    Uchiyama, Junji; Nobue, Yuka; Zhao, Hong; Matsuzaki, Hiroshi; Nagahama, Hideki; Matsuoka, Satoshi; Matsumoto, Kouji; Hara, Hiroshi

    2010-06-01

    Escherichia coli pgsA mutations, which cause acidic phospholipid deficiency, repress transcription of the flagellar master operon flhDC, and thus impair flagellar formation and motility. The molecular mechanism of the strong repression of flhDC transcription in the mutant cells, however, has not yet been clarified. In order to shed light on this mechanism we isolated genes which, when supplied in multicopy, suppress the repression of flhD, and found that three genes, gadW, metE and yeaB, were capable of suppression. Taking into account a previous report that gadW represses sigma(S) production, the level of sigma(S) in the pgsA3 mutant was examined. We found that pgsA3 cells had a high level of sigma(S) and that introduction of a gadW plasmid into pgsA3 cells did reduce the sigma(S) level. The pgsA3 cells exhibited a sharp increase in sigma(S) levels that can only be partially attributed to the slight increase in rpoS transcription; the largest part of the effect is due to a post-transcriptional accumulation of sigma(S). GadW in multicopy exerts its effect by post-transcriptionally downregulating sigma(S). YeaB and MetE in multicopy also exert their effect via sigma(S). Disruption of rpoS caused an increase of the flhD mRNA level, and induction from P(trc)-rpoS repressed the flhD mRNA level. The strong repression of flhD transcription in pgsA3 mutant cells is thus suggested to be caused by the accumulated sigma(S). PMID:20185506

  11. Methylation of H2AR29 is a novel repressive PRMT6 target

    Directory of Open Access Journals (Sweden)

    Waldmann Tanja

    2011-07-01

    Full Text Available Abstract Background Covalent histone modifications are central to all DNA-dependent processes. Modifications of histones H3 and H4 are becoming well characterised, but knowledge of how H2A modifications regulate chromatin dynamics and gene expression is still very limited. Results To understand the function of H2A modifications, we performed a systematic analysis of the histone H2A methylation status. We identified and functionally characterised two new methylation sites in H2A: R11 (H2AR11 and R29 (H2AR29. Using an unbiased biochemical approach in combination with candidate assays we showed that protein arginine methyltransferase (PRMT 1 and PRMT6 are unique in their ability to catalyse these modifications. Importantly we found that H2AR29me2 is specifically enriched at genes repressed by PRMT6, implicating H2AR29me2 in transcriptional repression. Conclusions Our data establishes R11 and R29 as new arginine methylation sites in H2A. We identified the specific modifying enzymes involved, and uncovered a novel functional role of H2AR29me2 in gene silencing in vivo. Thus this work reveals novel insights into the function of H2A methylation and in the mechanisms of PRMT6-mediated transcriptional repression.

  12. The three operators of the lac operon cooperate in repression.

    OpenAIRE

    Oehler, S; Eismann, E R; Krämer, H; Müller-Hill, B

    1990-01-01

    We tested the effect of systematic destruction of all three lac operators of the chromosomal lac operon of Escherichia coli on repression by Lac repressor. Absence of just one 'pseudo-operator' O2 or O3 decreases repression by wild-type tetrameric Lac repressor approximately 2- to 3-fold; absence of both 'pseudo-operators' decreases repression greater than 50-fold. O1 alone represses under these conditions only approximately 20-fold. Dimeric active Lac repressor (iadi) represses the wild-type...

  13. RNAi and heterochromatin repress centromeric meiotic recombination

    DEFF Research Database (Denmark)

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

    2010-01-01

    During meiosis, the formation of viable haploid gametes from diploid precursors requires that each homologous chromosome pair be properly segregated to produce an exact haploid set of chromosomes. Genetic recombination, which provides a physical connection between homologous chromosomes, is....... Surprisingly, one mutant derepressed for recombination in the heterochromatic mating-type region during meiosis and several mutants derepressed for centromeric gene expression during mitotic growth are not derepressed for centromeric recombination during meiosis. These results reveal a complex relation between...... types of repression by heterochromatin. Our results also reveal a previously undemonstrated role for RNAi and heterochromatin in the repression of meiotic centromeric recombination and, potentially, in the prevention of birth defects by maintenance of proper chromosome segregation during meiosis....

  14. Cancer, acute stress disorder, and repressive coping

    DEFF Research Database (Denmark)

    Pedersen, Anette Fischer; Zachariae, Robert

    2010-01-01

    The purpose of this study was to investigate the association between repressive coping style and Acute Stress Disorder (ASD) in a sample of cancer patients. A total of 112 cancer patients recently diagnosed with cancer participated in the study. ASD was assessed by the Stanford Acute Stress...... Reaction Questionnaire, and repressive coping was assessed by a combination of scores from the Marlowe-Crowne Social Desirability Scale, and the Bendig version of the Taylor Manifest Anxiety Scale. Significantly fewer patients classified as "repressors" were diagnosed with ASD compared to patients...... classified as "non-repressors". However, further investigations revealed that the lower incidence of ASD in repressors apparently was caused by a low score on anxiety and not by an interaction effect between anxiety and defensiveness. Future studies have to investigate whether different psychological...

  15. Tbx3 represses PTEN and is over-expressed in head and neck squamous cell carcinoma

    Directory of Open Access Journals (Sweden)

    Burgucu Durmus

    2012-10-01

    Full Text Available Abstract Background Despite advances in diagnostic and treatment strategies, head and neck squamous cell cancer (HNSCC constitutes one of the worst cancer types in terms of prognosis. PTEN is one of the tumour suppressors whose expression and/or activity have been found to be reduced in HNSCC, with rather low rates of mutations within the PTEN gene (6-8%. We reasoned that low expression levels of PTEN might be due to a transcriptional repression governed by an oncogene. Tbx2 and Tbx3, both of which are transcriptional repressors, have been found to be amplified or over-expressed in various cancer types. Thus, we hypothesize that Tbx3 may be over expressed in HNSCC and may repress PTEN, thus leading to cancer formation and/or progression. Methods Using immunohistochemistry and quantitative PCR (qPCR, protein and mRNA levels of PTEN and Tbx3 were identified in samples excised from cancerous and adjacent normal tissues from 33 patients who were diagnosed with HNSCC. In addition, HeLa and HEK cell lines were transfected with a Tbx3 expressing plasmid and endogenous PTEN mRNA and protein levels were determined via qPCR and flow cytometry. Transcription assays were performed to demonstrate effects of Tbx3 on PTEN promoter activity. Mann–Whitney, Spearman’s Correlation and Wilcoxon signed-rank tests were used to analyze the data. Results We demonstrate that in HNSCC samples, Tbx3 mRNA levels are increased with respect to their normal tissue counterparts (p Conclusions We show that Tbx3 is up-regulated in tissue samples of HNSCC patients and that Tbx3 represses PTEN transcription. Thus, our data not only reveals a new mechanism that may be important in cancer formation, but also suggests that Tbx3 can be used as a potential biomarker in cancer.

  16. Repression and substitutive formation: the relationship between Freud's concepts reconsidered.

    Science.gov (United States)

    Zepf, Siegfried

    2012-06-01

    This paper examines Freud's concept of repression and the relationship between repression and substitutive formation as it presents itself in Freud's writings. The author shows that Freud gives at least four different meanings to the term "repression": Freud uses it interchangeably with defense, as a consciously intended forgetting, as a specific unconscious mechanism of defense, and to describe the consequence of defense mechanisms leading to substitutive formations. The inconsistencies in this relationship are discussed and clarified, and Freud's economic and linguistic attempts at founding repression are subjected to critique; the need of a primal repression as a necessary condition for repression proper is pointed out. In developing Freud's linguistic foundation of repression further, the author presents defense as a semantic displacement. Ideas are excluded from the realm of the concepts that belong to them historically. These presentations become unconscious, that is, repressed, in that they can no longer be identified as "cases" of these conceptual internal contents. At the same time they are displaced into the extensions of concepts whose internal contents do not belong to them originally. It is by virtue of the internal contents of these concepts that the displaced elements as substitutive formations once again attain consciousness, albeit a false one. The author suggests dismissing repression as a specific defense mechanism of its own; to reversing Freud's thesis that repression, as a rule, creates a substitutive formation into its opposite; and recognizing that the mechanisms used to build substitutes, as a rule, create repression. PMID:22712593

  17. Multi-Faceted Characterization of a Novel LuxR-Repressible Promoter Library for Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Susanna Zucca

    Full Text Available The genetic elements regulating the natural quorum sensing (QS networks of several microorganisms are widely used in synthetic biology to control the behaviour of single cells and engineered bacterial populations via ad-hoc constructed synthetic circuits. A number of novel engineering-inspired biological functions have been implemented and model systems have also been constructed to improve the knowledge on natural QS systems. Synthetic QS-based parts, such as promoters, have been reported in literature, to provide biological components with functions that are not present in nature, like modified induction logic or activation/repression by additional molecules. In this work, a library of promoters that can be repressed by the LuxR protein in presence of the QS autoinducer N-3-oxohexanoyl-L-homoserine lactone (AHL was reported for Escherichia coli, to expand the toolkit of genetic parts that can be used to engineer novel synthetic QS-based systems. The library was constructed via polymerase chain reaction with highly constrained degenerate oligonucleotides, designed according to the consensus -35 and -10 sequences of a previously reported constitutive promoter library of graded strength, to maximize the probability of obtaining functional clones. All the promoters have a lux box between the -35 and -10 regions, to implement a LuxR-repressible behaviour. Twelve unique library members of graded strength (about 100-fold activity range were selected to form the final library and they were characterized in several genetic contexts, such as in different plasmids, via different reporter genes, in presence of a LuxR expression cassette in different positions and in response to different AHL concentrations. The new obtained regulatory parts and corresponding data can be exploited by synthetic biologists to implement an artificial AHL-dependent repression of transcription in genetic circuits. The target transcriptional activity can be selected among the

  18. Organizer-Derived WOX5 Signal Maintains Root Columella Stem Cells through Chromatin-Mediated Repression of CDF4 Expression.

    Science.gov (United States)

    Pi, Limin; Aichinger, Ernst; van der Graaff, Eric; Llavata-Peris, Cristina I; Weijers, Dolf; Hennig, Lars; Groot, Edwin; Laux, Thomas

    2015-06-01

    Stem cells in plants and animals are maintained pluripotent by signals from adjacent niche cells. In plants, WUSCHEL HOMEOBOX (WOX) transcription factors are central regulators of stem cell maintenance in different meristem types, yet their molecular mode of action has remained elusive. Here we show that in the Arabidopsis root meristem, the WOX5 protein moves from the root niche organizer, the quiescent center, into the columella stem cells, where it directly represses the transcription factor gene CDF4. This creates a gradient of CDF4 transcription, which promotes differentiation opposite to the WOX5 gradient, allowing stem cell daughter cells to exit the stem cell state. We further show that WOX5 represses CDF4 transcription by recruiting TPL/TPR co-repressors and the histone deacetylase HDA19, which consequently induces histone deacetylation at the CDF4 regulatory region. Our results show that chromatin-mediated repression of differentiation programs is a common strategy in plant and animal stem cell niches. PMID:26028217

  19. Transcriptional Regulation of Plant Secondary Metabolism

    Institute of Scientific and Technical Information of China (English)

    Chang-Qing Yang; Xin Fang; Xiu-Ming Wu; Ying-Bo Mao; Ling-Jian Wang; Xiao-Ya Chen

    2012-01-01

    Plant secondary metabolites play critical roles in plant-environment interactions.They are synthesized in different organs or tissues at particular developmental stages,and in response to various environmental stimuli,both biotic and abiotic.Accordingly,corresponding genes are regulated at the transcriptional level by multiple transcription factors.Several families of transcription factors have been identified to participate in controlling the biosynthesis and accumulation of secondary metabolites.These regulators integrate internal (often developmental) and external signals,bind to corresponding cis-elements — which are often in the promoter regions — to activate or repress the expression of enzyme-coding genes,and some of them interact with other transcription factors to form a complex.In this review,we summarize recent research in these areas,with an emphasis on newly-identified transcription factors and their functions in metabolism regulation.

  20. Tbx3 represses PTEN and is over-expressed in head and neck squamous cell carcinoma

    International Nuclear Information System (INIS)

    Despite advances in diagnostic and treatment strategies, head and neck squamous cell cancer (HNSCC) constitutes one of the worst cancer types in terms of prognosis. PTEN is one of the tumour suppressors whose expression and/or activity have been found to be reduced in HNSCC, with rather low rates of mutations within the PTEN gene (6-8%). We reasoned that low expression levels of PTEN might be due to a transcriptional repression governed by an oncogene. Tbx2 and Tbx3, both of which are transcriptional repressors, have been found to be amplified or over-expressed in various cancer types. Thus, we hypothesize that Tbx3 may be over expressed in HNSCC and may repress PTEN, thus leading to cancer formation and/or progression. Using immunohistochemistry and quantitative PCR (qPCR), protein and mRNA levels of PTEN and Tbx3 were identified in samples excised from cancerous and adjacent normal tissues from 33 patients who were diagnosed with HNSCC. In addition, HeLa and HEK cell lines were transfected with a Tbx3 expressing plasmid and endogenous PTEN mRNA and protein levels were determined via qPCR and flow cytometry. Transcription assays were performed to demonstrate effects of Tbx3 on PTEN promoter activity. Mann–Whitney, Spearman’s Correlation and Wilcoxon signed-rank tests were used to analyze the data. We demonstrate that in HNSCC samples, Tbx3 mRNA levels are increased with respect to their normal tissue counterparts (p<0.001), whereas PTEN mRNA levels are significantly reduced in cancer tissues. Moreover, Tbx3 protein is also increased in HNSCC tissue sections. Over-expression of Tbx3 in HeLa and HEK cell lines causes reduction in endogenous PTEN mRNA and protein levels. In addition, transcription activity assays reveal that Tbx3 is capable of repressing both the basal and induced promoter activity of PTEN. We show that Tbx3 is up-regulated in tissue samples of HNSCC patients and that Tbx3 represses PTEN transcription. Thus, our data not only reveals a new

  1. Design and characterization of a dual-mode promoter with activation and repression capability for tuning gene expression in yeast.

    Science.gov (United States)

    Mazumder, Mostafizur; McMillen, David R

    2014-08-01

    Modularity in controlling gene expression artificially is becoming an essential aspect of synthetic biology. Artificial transcriptional control of gene expression is one of the most well-developed methods for the design of novel synthetic regulatory networks. Such networks are intended to help understand natural cellular phenomena and to enable new biotechnological applications. Promoter sequence manipulation with cis-regulatory elements is a key approach to control gene expression transcriptionally. Here, we have designed a promoter that can be both activated and repressed, as a contribution to the library of synthetic biological 'parts'. Starting with the minimal cytochrome C (minCYC) promoter in yeast, we incorporated five steroid hormone responsive elements (SHREs) and one lac operator site, respectively, upstream and downstream of the TATA box. This allows activation through the testosterone-responsive androgen receptor, and repression through the LacI repressor. Exposure to varying concentrations of testosterone (to vary activation) and IPTG (to vary repression) demonstrated the ability to tune the promoter's output curve over a wide range. By integrating activating and repressing signals, the promoter permits a useful form of signal integration, and we are optimistic that it will serve as a component in future regulatory networks, including feedback controllers. PMID:25056312

  2. STENOFOLIA recruits TOPLESS to repress ASYMMETRIC LEAVES2 at the leaf margin and promote leaf blade outgrowth in Medicago truncatula.

    Science.gov (United States)

    Zhang, Fei; Wang, Yewei; Li, Guifen; Tang, Yuhong; Kramer, Elena M; Tadege, Million

    2014-02-01

    The Medicago truncatula WUSCHEL-related homeobox (WOX) gene, STENOFOLIA (STF), plays a key role in leaf blade outgrowth by promoting cell proliferation at the adaxial-abaxial junction. STF functions primarily as a transcriptional repressor, but the underlying molecular mechanism is unknown. Here, we report the identification of a protein interaction partner and a direct target, shedding light on the mechanism of STF function. Two highly conserved motifs in the C-terminal domain of STF, the WUSCHEL (WUS) box and the STF box, cooperatively recruit TOPLESS (Mt-TPL) family corepressors, and this recruitment is required for STF function, as deletion of these two domains (STFdel) impaired blade outgrowth whereas fusing Mt-TPL to STFdel restored function. The homeodomain motif is required for direct repression of ASYMMETRIC LEAVES2 (Mt-AS2), silencing of which partially rescues the stf mutant phenotype. STF and LAMINALESS1 (LAM1) are functional orthologs. A single amino acid (Asn to Ile) substitution in the homeodomain abolished the repression of Mt-AS2 and STF's ability to complement the lam1 mutant of Nicotiana sylvestris. Our data together support a model in which STF recruits corepressors to transcriptionally repress its targets during leaf blade morphogenesis. We propose that recruitment of TPL/TPL-related proteins may be a common mechanism in the repressive function of modern/WUS clade WOX genes. PMID:24585835

  3. Repression of the DNA-binding inhibitor Id3 by Blimp-1 limits CD8+ T cell memory formation

    Science.gov (United States)

    Ji, Yun; Pos, Zoltan; Rao, Mahadev; Klebanoff, Christopher A.; Yu, Zhiya; Sukumar, Madhusudhanan; Reger, Robert N.; Palmer, Douglas C.; Borman, Zachary A.; Muranski, Pawel; Wang, Ena; Schrump, David S.; Marincola, Francesco M.; Restifo, Nicholas P.; Gattinoni, Luca

    2011-01-01

    Blimp-1 is a transcriptional repressor that promotes the differentiation of CD8+ T cells into short-lived KLRG-1+ effector cells (SLEC), but how it operates remains poorly defined. Here we show that Blimp-1 binds and represses the Id3 promoter in SLEC. Repression of Id3 by Blimp-1 was dispensable for SLEC development but limited their capacity to persist as memory cells. Enforced expression of Id3 was sufficient to rescue SLEC survival and enhanced recall responses. Id3 function was mediated in part through inhibition of E2a transcriptional activity and induction of genes regulating genome stability. These findings identify a Blimp-1-Id3-E2a axis as a key molecular switch that determines whether effector CD8+ T cells are programmed to die or enter the memory pool. PMID:22057288

  4. Repression of the albumin gene in Novikoff hepatoma cells

    International Nuclear Information System (INIS)

    Novikoff hepatoma cells have lost their capacity to synthesize albumin. As a first approach to study the mechanisms underlying this event, in vitro translation in a reticulocyte system was performed using total polyadenylated mRNA from rat liver and Novikoff hepatoma cells. Immunoprecipitation of the in vitro translation products with albumin-specific antibody revealed a total lack of albumin synthesis in Novikoff hepatoma, suggesting the absence of functional albumin mRNA in these cells. Titration experiments using as probe albumin cDNA cloned in pBR322 plasmid demonstrated the absence of albumin-specific sequences in both polysomal and nuclear polyadenylated and total RNA from Novikoff cells. This albumin recombinant plasmid was obtained by screening a rat liver cDNA library with albumin [/sup 32/P]cDNA reverse transcribed from immuno-precipitated mRNA. The presence of an albumin-specific gene insert was documented with translation assays as well as by restriction mapping. Repression of the albumin gene at the transcriptional level was further demonstrated by RNA blotting experiments using the cloned albumin cDNA probe. Genomic DNA blots using the cloned albumin cDNA as probe did not reveal any large-scale deletions, insertions, or rearrangements in the albumin gene, suggesting that the processes involved in the suppression of albumin mRNA synthesis do not involve extensive genomic rearrangements

  5. Angiogenesis is repressed by ethanol exposure during chick embryonic development.

    Science.gov (United States)

    Wang, Guang; Zhong, Shan; Zhang, Shi-Yao; Ma, Zheng-Lai; Chen, Jian-Long; Lu, Wen-Hui; Cheng, Xin; Chuai, Manli; Lee, Kenneth Ka Ho; Lu, Da-Xiang; Yang, Xuesong

    2016-05-01

    It is now known that excess alcohol consumption during pregnancy can cause fetal alcohol syndrome to develop. However, it is not known whether excess ethanol exposure could directly affect angiogenesis in the embryo or angiogenesis being indirectly affected because of ethanol-induced fetal alcohol syndrome. Using the chick yolk sac membrane (YSM) model, we demonstrated that ethanol exposure dramatically inhibited angiogenesis in the YSM of 9-day-old chick embryos, in a dose-dependent manner. Likewise, the anti-angiogenesis effect of ethanol could be seen in the developing vessel plexus (at the same extra-embryonic regions) during earlier stages of embryo development. The anti-angiogenic effect of ethanol was found associated with excess reactive oxygen species (ROS) production; as glutathione peroxidase activity increased while superoxide dismutase 1 and 2 activities decreased in the YSMs. We further validated this observation by exposing chick embryos to 2,2'-azobis-amidinopropane dihydrochloride (a ROS inducer) and obtained a similar anti-angiogenesis effect as ethanol treatment. Semiquantitative reverse transcription-polymerase chain reaction analysis of the experimental YSMs revealed that expression of angiogenesis-related genes, vascular endothelial growth factor and its receptor, fibroblast growth factor 2 and hypoxia-inducible factor, were all repressed following ethanol and 2,2'-azobis-amidinopropane dihydrochloride treatment. In summary, our results suggest that excess ethanol exposure inhibits embryonic angiogenesis through promoting superfluous ROS production during embryo development. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26177723

  6. An endogenous growth model of money, banking, and financial repression

    OpenAIRE

    Espinosa, Marco; Yip, Chong K.

    1996-01-01

    In this paper, we develop an endogenous growth model with financial intermediation to examine the effects of financial repression on growth, inflation, and welfare. By limiting the liquidity provision, binding reserve requirements always suppress economic growth while their effect on inflation is a function, among other things, of the degree of repression. For example, contrary to previous claims, if financial repression is severe enough so that an informal financial sector emerges, liberaliz...

  7. Repression: finding our way in the maze of concepts.

    Science.gov (United States)

    Garssen, Bert

    2007-12-01

    Repression is associated in the literature with terms such as non-expression, emotional control, rationality, anti-emotionality, defensiveness and restraint. Whether these terms are synonymous with repression, indicate a variation, or are essentially different from repression is uncertain. To clarify this obscured view on repression, this paper indicates the similarities and differences between these concepts. Repression is the general term that is used to describe the tendency to inhibit the experience and the expression of negative feelings or unpleasant cognitions in order to prevent one's positive self-image from being threatened ('repressive coping style'). The terms self-deception versus other-deception, and socially related versus personally related repression refer to what is considered to be different aspects of repression. Defensiveness is a broader concept that includes both anxious defensiveness and repression; the essential difference is whether negative emotions are reported or not. Concepts that are sometimes associated with repression, but which are conceptually different, are also discussed in this paper: The act of suppression, 'repressed memories,' habitual suppression, concealment, type C coping pattern, type D personality, denial, alexithymia and blunting. Consequences for research: (1) When summarizing findings reported in the literature, it is essential to determine which concepts the findings represent. This is rarely made explicit, and failure to do so may lead to drawing the wrong conclusions (2) It is advisable to use scales based on different aspects of repression (3) Whether empirical findings substantiate the similarities and differences between concepts described in this paper will need to be shown. PMID:17653842

  8. Gene expression in self-repressing system with multiple gene copies.

    Science.gov (United States)

    Miekisz, Jacek; Szymańska, Paulina

    2013-02-01

    We analyze a simple model of a self-repressing system with multiple gene copies. Protein molecules may bound to DNA promoters and block their own transcription. We derive analytical expressions for the variance of the number of protein molecules in the stationary state in the self-consistent mean-field approximation. We show that the Fano factor (the variance divided by the mean value) is bigger for the one-gene case than for two gene copies and the difference decreases to zero as frequencies of binding and unbinding increase to infinity. PMID:23354928

  9. Gene Expression in Self-repressing System with Multiple Gene Copies

    OpenAIRE

    Miȩkisz, Jacek; Szymańska, Paulina

    2013-01-01

    We analyze a simple model of a self-repressing system with multiple gene copies. Protein molecules may bound to DNA promoters and block their own transcription. We derive analytical expressions for the variance of the number of protein molecules in the stationary state in the self-consistent mean-field approximation. We show that the Fano factor (the variance divided by the mean value) is bigger for the one-gene case than for two gene copies and the difference decreases to zero as frequencies...

  10. Repression of a mating type cassette in the fission yeast by four DNA elements

    DEFF Research Database (Denmark)

    Ekwall, K; Nielsen, O; Ruusala, T;

    1991-01-01

    difference between the active and the silent stage of the P determinant is controlled by four repressive elements that are located at the silent locus. There are two elements to the left and two to the right of the mating type cassette. Both elements to the left and either one of the two elements to the...... right are required for an effective blockage of transcription. When they are combined, the four elements define a highly efficient silencer functionally similar to the HMRE and HMLE and HMLI silencers in Saccharomyces cerevisiae. In addition, the DNA surrounding the silent P locus confers symmetric...

  11. Mutations that relieve nutritional repression of the Bacillus subtilis dipeptide permease operon.

    OpenAIRE

    Slack, F J; Mueller, J P; Sonenshein, A L

    1993-01-01

    The Bacillus subtilis dciA operon encodes a dipeptide transport complex that is induced rapidly as cells enter stationary phase and initiate sporulation. Expression of this operon in growing cells is repressed by glucose, by a mixture of amino acids, and by the AbrB protein. A genetic screen was devised to identify mutations that allow inappropriate expression from the dciA promoter during growth. These mutations resulted in increased dciA transcription during growth in nutrient broth, in min...

  12. NR2F1 disrupts synergistic activation of the MTTP gene transcription by HNF-4α and HNF-1α

    OpenAIRE

    DAI, KEZHI; Hussain, M. Mahmood

    2012-01-01

    Regulation of microsomal triglyceride transfer protein (MTP) expression mainly occurs at the transcriptional level. We have previously shown that MTTP gene expression was repressed in nondifferentiated intestinal cells by nuclear receptor 2 family 1 (NR2F1). However, mechanisms involved in the repression of MTP by NR2F1 were not elucidated. Here, we show that MTP expression requires hepatic nuclear factor (HNF)-4α transcription factor. Different HNF-1 proteins synergistically enhance MTP prom...

  13. Kaiso is a key regulator of spleen germinal center formation by repressing Bcl6 expression in splenocytes

    Energy Technology Data Exchange (ETDEWEB)

    Koh, Dong-In; Yoon, Jae-Hyeon; Kim, Min-Kyeong; An, Haemin; Kim, Min-Young; Hur, Man-Wook, E-mail: mwhur2@yuhs.ac

    2013-12-13

    Highlights: •Knockout of Kaiso results in concordant high expression of Bcl6 and c-Myc in spleen. •Kaiso binds the Bcl6 promoter and represses Bcl6 transcription by recruiting NCoR. •Upregulated Bcl6 increases splenocyte proliferation and causes large diffused GC. •Cell cycle-inhibition genes such as Cdkn1b and Cdkn1a are repressed by Bcl6. -- Abstract: Kaiso was previously described as a methylated DNA-binding protein and a transcription repressor interacting with the corepressor protein complex NCoR. In the current study, we show that generation-3 Kaiso knockout mice show a phenotype of splenomegaly and large diffused germinal centers (GC). In the spleens of Kaiso knockout mice, Bcl6 (a transcriptional repressor that plays a critical role in GC development in spleen) and c-Myc were highly expressed, while the cell cycle arrest genes p27 (CDKN1B), p21 (CDKN1A) and Gadd45a were downregulated. Chromatin immunoprecipitation (ChIP) and transcription assays suggested that Kaiso represses Bcl6 expression, and in Kaiso knockout mice, derepressed Bcl6 increased cell proliferation by suppressing p27 (CDKN1B), p21 (CDKN1A) and Gadd45a, while upregulating the oncogene c-Myc. Further evidence for Kaiso regulation of splenomegaly was provided by B lymphocyte Ramos cells, in which ectopic KAISO repressed BCL6 and c-MYC expression, while concomitantly increasing the expression of the cell cycle arrestors p21, p27 and Gadd45a. In summary, derepressed Bcl6 expression may be responsible for increases in GC cell proliferation and splenomegaly of Kaiso knockout mice.

  14. Kaiso is a key regulator of spleen germinal center formation by repressing Bcl6 expression in splenocytes

    International Nuclear Information System (INIS)

    Highlights: •Knockout of Kaiso results in concordant high expression of Bcl6 and c-Myc in spleen. •Kaiso binds the Bcl6 promoter and represses Bcl6 transcription by recruiting NCoR. •Upregulated Bcl6 increases splenocyte proliferation and causes large diffused GC. •Cell cycle-inhibition genes such as Cdkn1b and Cdkn1a are repressed by Bcl6. -- Abstract: Kaiso was previously described as a methylated DNA-binding protein and a transcription repressor interacting with the corepressor protein complex NCoR. In the current study, we show that generation-3 Kaiso knockout mice show a phenotype of splenomegaly and large diffused germinal centers (GC). In the spleens of Kaiso knockout mice, Bcl6 (a transcriptional repressor that plays a critical role in GC development in spleen) and c-Myc were highly expressed, while the cell cycle arrest genes p27 (CDKN1B), p21 (CDKN1A) and Gadd45a were downregulated. Chromatin immunoprecipitation (ChIP) and transcription assays suggested that Kaiso represses Bcl6 expression, and in Kaiso knockout mice, derepressed Bcl6 increased cell proliferation by suppressing p27 (CDKN1B), p21 (CDKN1A) and Gadd45a, while upregulating the oncogene c-Myc. Further evidence for Kaiso regulation of splenomegaly was provided by B lymphocyte Ramos cells, in which ectopic KAISO repressed BCL6 and c-MYC expression, while concomitantly increasing the expression of the cell cycle arrestors p21, p27 and Gadd45a. In summary, derepressed Bcl6 expression may be responsible for increases in GC cell proliferation and splenomegaly of Kaiso knockout mice

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

    Science.gov (United States)

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

  16. ATRX represses alternative lengthening of telomeres.

    Science.gov (United States)

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

    2015-06-30

    The unlimited proliferation of cancer cells requires a mechanism to prevent telomere shortening. Alternative Lengthening of Telomeres (ALT) is an homologous recombination-mediated mechanism of telomere elongation used in tumors, including osteosarcomas, soft tissue sarcoma subtypes, and glial brain tumors. Mutations in the ATRX/DAXX chromatin remodeling complex have been reported in tumors and cell lines that use the ALT mechanism, suggesting that ATRX may be an ALT repressor. We show here that knockout or knockdown of ATRX in mortal cells or immortal telomerase-positive cells is insufficient to activate ALT. Notably, however, in SV40-transformed mortal fibroblasts ATRX loss results in either a significant increase in the proportion of cell lines activating ALT (instead of telomerase) or in a significant decrease in the time prior to ALT activation. These data indicate that loss of ATRX function cooperates with one or more as-yet unidentified genetic or epigenetic alterations to activate ALT. Moreover, transient ATRX expression in ALT-positive/ATRX-negative cells represses ALT activity. These data provide the first direct, functional evidence that ATRX represses ALT. PMID:26001292

  17. Reconstruction and logical modeling of glucose repression signaling pathways in Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    Oliveira Ana

    2009-01-01

    Full Text Available Abstract Background In the yeast Saccharomyces cerevisiae, the presence of high levels of glucose leads to an array of down-regulatory effects known as glucose repression. This process is complex due to the presence of feedback loops and crosstalk between different pathways, complicating the use of intuitive approaches to analyze the system. Results We established a logical model of yeast glucose repression, formalized as a hypergraph. The model was constructed based on verified regulatory interactions and it includes 50 gene transcripts, 22 proteins, 5 metabolites and 118 hyperedges. We computed the logical steady states of all nodes in the network in order to simulate wildtype and deletion mutant responses to different sugar availabilities. Evaluation of the model predictive power was achieved by comparing changes in the logical state of gene nodes with transcriptome data. Overall, we observed 71% true predictions, and analyzed sources of errors and discrepancies for the remaining. Conclusion Though the binary nature of logical (Boolean models entails inherent limitations, our model constitutes a primary tool for storing regulatory knowledge, searching for incoherencies in hypotheses and evaluating the effect of deleting regulatory elements involved in glucose repression.

  18. Integrative analysis of histone ChIP-seq and transcription data using Bayesian mixture models

    DEFF Research Database (Denmark)

    Klein, Hans-Ulrich; Schäfer, Martin; Porse, Bo T; Hasemann, Marie S; Ickstadt, Katja; Dugas, Martin

    2014-01-01

    Histone modifications are a key epigenetic mechanism to activate or repress the transcription of genes. Datasets of matched transcription data and histone modification data obtained by ChIP-seq exist, but methods for integrative analysis of both data types are still rare. Here, we present a novel...

  19. Identification of uniquely expressed transcription factors in highly purified B-cell lymphoma samples

    DEFF Research Database (Denmark)

    Andréasson, Ulrika; Edén, Patrik; Peterson, Carsten; Högerkorp, Carl-Magnus; Jerkeman, Mats; Andersen, Niels Smedegaard; Berglund, Mattias; Sundström, Christer; Rosenquist, Richard; Borrebaeck, Carl A K; Ek, Sara

    2010-01-01

    Transcription factors (TFs) are critical for B-cell differentiation, affecting gene expression both by repression and transcriptional activation. Still, this information is not used for classification of B-cell lymphomas (BCLs). Traditionally, BCLs are diagnosed based on a phenotypic resemblance ...

  20. Repression of the nuclear receptor small heterodimer partner by steatotic drugs and in advanced nonalcoholic fatty liver disease.

    Science.gov (United States)

    Benet, Marta; Guzmán, Carla; Pisonero-Vaquero, Sandra; García-Mediavilla, M Victoria; Sánchez-Campos, Sonia; Martínez-Chantar, M Luz; Donato, M Teresa; Castell, José Vicente; Jover, Ramiro

    2015-04-01

    The small heterodimer partner (SHP) (NR0B2) is an atypical nuclear receptor that lacks a DNA-binding domain. It interacts with and inhibits many transcription factors, affecting key metabolic processes, including bile acid, cholesterol, fatty acid, and drug metabolism. Our aim was to determine the influence of steatotic drugs and nonalcoholic fatty liver disease (NAFLD) on SHP expression and investigate the potential mechanisms. SHP was found to be repressed by steatotic drugs (valproate, doxycycline, tetracycline, and cyclosporin A) in cultured hepatic cells and the livers of different animal models of NAFLD: iatrogenic (tetracycline-treated rats), genetic (glycine N-methyltransferase-deficient mice), and nutritional (mice fed a methionine- and choline-deficient diet). Among the different transcription factors investigated, CCAAT-enhancer-binding protein α (C/EBPα) showed the strongest dominant-repressive effect on SHP expression in HepG2 and human hepatocytes. Reporter assays revealed that the inhibitory effect of C/EBPα and steatotic drugs colocalize between -340 and -509 base pair of the SHP promoter, and mutation of a predicted C/EBPα response element at -473 base pair abolished SHP repression by both C/EBPα and drugs. Moreover, inhibition of major stress signaling pathways demonstrated that the mitogen-activated protein kinase kinase 1/2 pathway activates, while the phosphatidylinositol 3 kinase pathway represses SHP in a C/EBP-dependent manner. We conclude that SHP is downregulated by several steatotic drugs and in advanced NAFLD. These conditions can activate signals that target C/EBPα and consequently repress SHP, thus favoring the progression and severity of NAFLD. PMID:25576488

  1. The CovR response regulator of group A streptococcus (GAS) acts directly to repress its own promoter.

    Science.gov (United States)

    Gusa, Asiya A; Scott, June R

    2005-06-01

    The CovR/S (CsrR/S) two component system is a global regulator of virulence gene expression in the group A streptococcus (GAS, Streptococcus pyogenes). The response regulator, CovR, regulates about 15% of the genes of GAS, including its own operon. Using in vitro DNA binding assays with purified CovR protein, we found that CovR binds a DNA fragment including the covR promoter (Pcov). DNaseI footprint analyses showed that phosphorylation of CovR enhanced and extended the protected regions. The proposed CovR consensus binding sequence (ATTARA) was present at most, but not all protected regions. The effect of replacing the two thymine residues in the consensus binding sequence (CB) with guanine residues was evaluated both in vitro and in vivo. Most, but not all, CB mutations reduced binding of CovR in vitro. Using a transcriptional reporter introduced in single copy into the GAS chromosome, we found that mutations at each CB completely or partially relieved CovR-mediated repression in vivo. This suggests that CovR regulation of Pcov is direct. Further support for this conclusion comes from use of an in vitro GAS transcription system in which CovR was sufficient to mediate repression of Pcov. This repression was enhanced by phosphorylation of the protein. In addition, we found that the CovR binding region overlapping the promoter was essential for wild type repression of Pcov both in vitro and in vivo, suggesting that promoter occlusion is a primary mechanism of Pcov repression by CovR. PMID:15882414

  2. H3K9 methyltransferase G9a negatively regulates UHRF1 transcription during leukemia cell differentiation

    OpenAIRE

    Kim, Kee-Beom; Son, Hye-Ju; Choi, Sulji; Hahm, Ja Young; Jung, Hyeonsoo; Baek, Hee Jo; Kook, Hoon; Hahn, Yoonsoo; Kook, Hyun; Seo, Sang-Beom

    2015-01-01

    Histone H3K9 methyltransferase (HMTase) G9a-mediated transcriptional repression is a major epigenetic silencing mechanism. UHRF1 (ubiquitin-like with PHD and ring finger domains 1) binds to hemimethylated DNA and plays an essential role in the maintenance of DNA methylation. Here, we provide evidence that UHRF1 is transcriptionally downregulated by H3K9 HMTase G9a. We found that increased expression of G9a along with transcription factor YY1 specifically represses UHRF1 transcription during T...

  3. 致病性不同的两种流感病毒NS1蛋白对人源细胞IFN-β转录抑制的比较%Comparison of Transcriptional Repression on IFN-β with Two Different Kinds of Pathogenic Influenza Virus NS1 Proteins

    Institute of Scientific and Technical Information of China (English)

    于佳; 王雨; 李宏岳; 张翠竹; 曹又佳

    2012-01-01

    The NS1 protein is a key virulence factor encoded by influenza A virus, which developed multiple ways to antagonize the host immune defense. During the viral infection, NS1 could down regulate the transcription of IFN-β to block the induced signaling pathway, by impressing the activity of NF-kB and IRF3. Using RT-PCR, reporter assay and virus titration assay, the NSl-a, which sourced from high pathogenic avian influenza virus, could more efficiently suppress the transcription of IFN-β and help VSV replication, compared with NSl-h sourced from low pathogenic human influenza virus. This difference might root from their discrepant ability of blocking the NF-kB and IRF3, but unrelated to the IFN induced transcription of ISG. The result may provide clues for investigating the relationship between NS1 and pathogenicity of influenza virus.%A型流感病毒编码的NS1蛋白是病毒关键的致病因子,可以通过多种机制拮抗宿主抗病毒反应.病毒感染过程中,NS1通过抑制NF-κB和IRF3两种转录因子的活性,下调IFN-β转录水平以阻断其诱导的信号通路.实验选取病毒母本致病性不同的两种NS1蛋白(NS1-a,NS1-h),通过RT-PCR、报告基因和VSV病毒滴度等实验证明高致病性禽流感病毒NS1-a与普通人流感病毒NS1-h相比,表现出较强的抑制IFN-β转录能力,并有效帮助VSV病毒复制.此差异源于NS1-a更加有效抑制NF-κB活性以及IRF3激活后的入核行为,与IFN诱导的ISG转录无关.所得结果为阐释流感病毒致病性与NS1的密切关系提供线索.

  4. Control of the Type 3 Secretion System in Vibrio harveyi by Quorum Sensing through Repression of ExsA ▿ ‡

    Science.gov (United States)

    Waters, Christopher M.; Wu, Julie T.; Ramsey, Meghan E.; Harris, Rebecca C.; Bassler, Bonnie L.

    2010-01-01

    The type 3 secretion system (T3SS) genes of Vibrio harveyi are activated at low cell density and repressed at high cell density by quorum sensing (QS). Repression requires LuxR, the master transcriptional regulator of QS-controlled genes. Here, we determine the mechanism underlying the LuxR repression of the T3SS system. Using a fluorescence-based cell sorting approach, we isolated V. harveyi mutants that are unable to express T3SS genes at low cell density and identified two mutations in the V. harveyi exsBA operon. While LuxR directly represses the expression of exsBA, complementation and epistasis analyses reveal that it is the repression of exsA expression, but not exsB expression, that is responsible for the QS-mediated repression of T3SS genes at high cell density. The present work further defines the genes in the V. harveyi QS regulon and elucidates a mechanism demonstrating how multiple regulators can be linked in series to direct the expression of QS target genes specifically at low or high cell density. PMID:20543047

  5. Transcriptional stochasticity in gene expression.

    Science.gov (United States)

    Lipniacki, Tomasz; Paszek, Pawel; Marciniak-Czochra, Anna; Brasier, Allan R; Kimmel, Marek

    2006-01-21

    Due to the small number of copies of molecular species involved, such as DNA, mRNA and regulatory proteins, gene expression is a stochastic phenomenon. In eukaryotic cells, the stochastic effects primarily originate in regulation of gene activity. Transcription can be initiated by a single transcription factor binding to a specific regulatory site in the target gene. Stochasticity of transcription factor binding and dissociation is then amplified by transcription and translation, since target gene activation results in a burst of mRNA molecules, and each mRNA copy serves as a template for translating numerous protein molecules. In the present paper, we explore a mathematical approach to stochastic modeling. In this approach, the ordinary differential equations with a stochastic component for mRNA and protein levels in a single cells yield a system of first-order partial differential equations (PDEs) for two-dimensional probability density functions (pdf). We consider the following examples: Regulation of a single auto-repressing gene, and regulation of a system of two mutual repressors and of an activator-repressor system. The resulting PDEs are approximated by a system of many ordinary equations, which are then numerically solved. PMID:16039671

  6. Plant callus: mechanisms of induction and repression.

    Science.gov (United States)

    Ikeuchi, Momoko; Sugimoto, Keiko; Iwase, Akira

    2013-09-01

    Plants develop unorganized cell masses like callus and tumors in response to various biotic and abiotic stimuli. Since the historical discovery that the combination of two growth-promoting hormones, auxin and cytokinin, induces callus from plant explants in vitro, this experimental system has been used extensively in both basic research and horticultural applications. The molecular basis of callus formation has long been obscure, but we are finally beginning to understand how unscheduled cell proliferation is suppressed during normal plant development and how genetic and environmental cues override these repressions to induce callus formation. In this review, we will first provide a brief overview of callus development in nature and in vitro and then describe our current knowledge of genetic and epigenetic mechanisms underlying callus formation. PMID:24076977

  7. EZH2 regulates neuroepithelium structure and neuroblast proliferation by repressing p21

    Science.gov (United States)

    Akizu, Naiara; García, María Alejandra; Estarás, Conchi; Fueyo, Raquel; Badosa, Carmen; de la Cruz, Xavier

    2016-01-01

    The function of EZH2 as a transcription repressor is well characterized. However, its role during vertebrate development is still poorly understood, particularly in neurogenesis. Here, we uncover the role of EZH2 in controlling the integrity of the neural tube and allowing proper progenitor proliferation. We demonstrate that knocking down the EZH2 in chick embryo neural tubes unexpectedly disrupts the neuroepithelium (NE) structure, correlating with alteration of the Rho pathway, and reduces neural progenitor proliferation. Moreover, we use transcriptional profiling and functional assays to show that EZH2-mediated repression of p21WAF1/CIP1 contributes to both processes. Accordingly, overexpression of cytoplasmic p21WAF1/CIP1 induces NE structural alterations and p21WAF1/CIP1 suppression rescues proliferation defects and partially compensates for the structural alterations and the Rho activity. Overall, our findings describe a new role of EZH2 in controlling the NE integrity in the neural tube to allow proper progenitor proliferation.

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

    Science.gov (United States)

    Zhang, Linlin; Reed, Robert D.

    2016-01-01

    Butterfly eyespot colour patterns are a key example of how a novel trait can appear in association with the co-option of developmental patterning genes. Little is known, however, about how, or even whether, co-opted genes function in eyespot development. Here we use CRISPR/Cas9 genome editing to determine the roles of two co-opted transcription factors that are expressed during early eyespot determination. We found that deletions in a single gene, spalt, are sufficient to reduce or completely delete eyespot colour patterns, thus demonstrating a positive regulatory role for this gene in eyespot determination. Conversely, and contrary to previous predictions, deletions in Distal-less (Dll) result in an increase in the size and number of eyespots, illustrating a repressive role for this gene in eyespot development. Altogether our results show that the presence, absence and shape of butterfly eyespots can be controlled by the activity of two co-opted transcription factors. PMID:27302525

  9. p53 represses human papillomavirus type 16 DNA replication via the viral E2 protein

    Directory of Open Access Journals (Sweden)

    Morgan Iain M

    2008-01-01

    Full Text Available Abstract Background Human papillomavirus (HPV DNA replication can be inhibited by the cellular tumour suppressor protein p53. However, the mechanism through which p53 inhibits viral replication and the role that this might play in the HPV life cycle are not known. The papillomavirus E2 protein is required for efficient HPV DNA replication and also regulates viral gene expression. E2 represses transcription of the HPV E6 and E7 oncogenes and can thereby modulate indirectly host cell proliferation and survival. In addition, the E2 protein from HPV 16 has been shown to bind p53 and to be capable of inducing apoptosis independently of E6 and E7. Results Here we use a panel of E2 mutants to confirm that mutations which block the induction of apoptosis via this E6/E7-independent pathway, have little or no effect on the induction of apoptosis by the E6/E7-dependent pathway. Although these mutations in E2 do not affect the ability of the protein to mediate HPV DNA replication, they do abrogate the repressive effects of p53 on the transcriptional activity of E2 and prevent the inhibition of E2-dependent HPV DNA replication by p53. Conclusion These data suggest that p53 down-regulates HPV 16 DNA replication via the E2 protein.

  10. A Maternal System Initiating the Zygotic Developmental Program through Combinatorial Repression in the Ascidian Embryo

    Science.gov (United States)

    Oda-Ishii, Izumi; Kubo, Atsushi; Kari, Willi; Suzuki, Nobuhiro; Rothbächer, Ute

    2016-01-01

    Maternal factors initiate the zygotic developmental program in animal embryos. In embryos of the chordate, Ciona intestinalis, three maternal factors—Gata.a, β-catenin, and Zic-r.a—are required to establish three domains of gene expression at the 16-cell stage; the animal hemisphere, vegetal hemisphere, and posterior vegetal domains. Here, we show how the maternal factors establish these domains. First, only β-catenin and its effector transcription factor, Tcf7, are required to establish the vegetal hemisphere domain. Second, genes specifically expressed in the posterior vegetal domain have additional repressive cis-elements that antagonize the activity of β-catenin/Tcf7. This antagonizing activity is suppressed by Zic-r.a, which is specifically localized in the posterior vegetal domain and binds to DNA indirectly through the interaction with Tcf7. Third, Gata.a directs specific gene expression in the animal hemisphere domain, because β-catenin/Tcf7 weakens the Gata.a-binding activity for target sites through a physical interaction in the vegetal cells. Thus, repressive regulation through protein-protein interactions among the maternal transcription factors is essential to establish the first distinct domains of gene expression in the chordate embryo. PMID:27152625

  11. YB1 binds to and represses the p16 tumor suppressor gene.

    Science.gov (United States)

    Kotake, Yojiro; Ozawa, Yuichi; Harada, Masanori; Kitagawa, Kyoko; Niida, Hiroyuki; Morita, Yasutaka; Tanaka, Kenji; Suda, Takafumi; Kitagawa, Masatoshi

    2013-11-01

    Y box binding protein 1 (YB1) has multiple functions associated with drug resistance, cell proliferation and metastasis through transcriptional and translational regulation. Increased expression of YB1 is closely related to tumor growth and aggressiveness. We showed that YB1 protein levels were decreased through replicative and premature senescence and were correlated with increased expression levels of p16(INK) (4A) tumor suppressor gene. Depletion of YB1 was associated with increased levels of p16 in human and murine primary cells. Forced expression of YB1 in mouse embryonic fibroblasts resulted in decreased expression of p16 and increased cell proliferation. Senescence-associated expression of β-galactosidase was repressed in YB1-over-expressing cells. Chromatin immunoprecipitation assays showed that YB1 directly associates with the p16 promoter. Taken together, all our findings indicate that YB1 directly binds to and represses p16 transcription, subsequently resulting in the promotion of cell growth and prevention of cellular senescence. PMID:24165022

  12. The Transcription Repressor REST in Adult Neurons: Physiology, Pathology, and Diseases 1,2,3

    OpenAIRE

    Baldelli, Pietro; Meldolesi, Jacopo

    2015-01-01

    Abstract REST [RE1-silencing transcription factor (also called neuron-restrictive silencer factor)] is known to repress thousands of possible target genes, many of which are neuron specific. To date, REST repression has been investigated mostly in stem cells and differentiating neurons. Current evidence demonstrates its importance in adult neurons as well. Low levels of REST, which are acquired during differentiation, govern the expression of specific neuronal phenotypes. REST-dependent genes...

  13. CRISPR-Mediated Modular RNA-Guided Regulation of Transcription in Eukaryotes

    OpenAIRE

    Gilbert, Luke A.; Larson, Matthew H.; Morsut, Leonardo; Liu, Zairan; Brar, Gloria A.; Torres, Sandra E.; Stern-Ginossar, Noam; Brandman, Onn; Whitehead, Evan H.; Doudna, Jennifer A.; Lim, Wendell A.; Weissman, Jonathan S.; Qi, Lei S.

    2013-01-01

    The genetic interrogation and reprogramming of cells requires methods for robust and precise targeting of genes for expression or repression. The CRISPR-associated catalytically inactive dCas9 protein offers a general platform for RNA-guided DNA targeting. Here we show that fusion of dCas9 to effector domains with distinct regulatory functions enables stable and efficient transcriptional repression or activation in human and yeast cells with the site of delivey determined solely by a co-expre...

  14. Effects of cytosine methylation on transcription factor binding sites

    KAUST Repository

    Medvedeva, Yulia A

    2014-03-26

    Background: DNA methylation in promoters is closely linked to downstream gene repression. However, whether DNA methylation is a cause or a consequence of gene repression remains an open question. If it is a cause, then DNA methylation may affect the affinity of transcription factors (TFs) for their binding sites (TFBSs). If it is a consequence, then gene repression caused by chromatin modification may be stabilized by DNA methylation. Until now, these two possibilities have been supported only by non-systematic evidence and they have not been tested on a wide range of TFs. An average promoter methylation is usually used in studies, whereas recent results suggested that methylation of individual cytosines can also be important.Results: We found that the methylation profiles of 16.6% of cytosines and the expression profiles of neighboring transcriptional start sites (TSSs) were significantly negatively correlated. We called the CpGs corresponding to such cytosines " traffic lights" We observed a strong selection against CpG " traffic lights" within TFBSs. The negative selection was stronger for transcriptional repressors as compared with transcriptional activators or multifunctional TFs as well as for core TFBS positions as compared with flanking TFBS positions.Conclusions: Our results indicate that direct and selective methylation of certain TFBS that prevents TF binding is restricted to special cases and cannot be considered as a general regulatory mechanism of transcription. 2013 Medvedeva et al.; licensee BioMed Central Ltd.

  15. Repression of death consciousness and the psychedelic trip

    OpenAIRE

    Varsha Dutta

    2012-01-01

    Death is our most repressed consciousness, it inheres our condition as the primordial fear. Perhaps it was necessary that this angst be repressed in man or he would be hurled against the dark forces of nature. Modern ethos was built on this edifice, where the ′denial of death′ while ′embracing one′s symbolic immortality′ would be worshipped, so this ideology simply overturned and repressed looking into the morass of the inevitable when it finally announced itself. Once this slowly pieced its ...

  16. Epigenetic distortion to VDR transcriptional regulation in prostate cancer cells

    OpenAIRE

    Singh, Prashant K.; Doig, Craig L.; Dhiman, Vineet K; Turner, Bryan M.; Smiraglia, Dominic J; Campbell, Moray J.

    2012-01-01

    The current study aimed to examine the gene specific mechanisms by which the actions of the vitamin D receptor (VDR) are distorted in prostate cancer. Transcriptional responses toward the VDR ligand, 1α,25(OH)2D3, were examined in non-malignant prostate epithelial cells (RWPE-1) and compared to the 1α,25(OH)2D3-recalcitrant prostate cancer cells (PC-3). Time resolved transcriptional studies for two VDR target genes revealed selective attenuation and repression of VDR transcriptional responses...

  17. Transcription factor CTCF and mammalian genome organization

    Directory of Open Access Journals (Sweden)

    Kotova E. S.

    2014-07-01

    Full Text Available The CTCF transcription factor is thought to be one of the main participants in various gene regulatory networks including transcription activation and repression, formation of independently functioning chromatin domains, regulation of imprinting etc. Sequencing of human and other genomes opened up a possibility to ascertain the genomic distribution of CTCF binding sites and to identify CTCF-dependent cis-regulatory elements, including insulators. In the review, we summarized recent data on CTCF functioning within a framework of the chromatin loop domain hypothesis of large-scale regulation of the genome activity. Its fundamental properties allow CTCF to serve as a transcription factor, an insulator protein and a dispersed genome-wide demarcation tool able to recruit various factors that emerge in response to diverse external and internal signals, and thus to exert its signal-specific function(s.

  18. Repressed BMP signaling reactivates NKL homeobox gene MSX1 in a T-ALL subset.

    Science.gov (United States)

    Nagel, Stefan; Ehrentraut, Stefan; Meyer, Corinna; Kaufmann, Maren; Drexler, Hans G; MacLeod, Roderick A F

    2015-02-01

    In T-cell acute lymphoblastic leukemia (T-ALL), several members of the NK-like (NKL) homeobox genes are aberrantly expressed. Here, we have analyzed the activity of NKL homeobox gene MSX1 using pediatric T-ALL in silico data, detecting overexpression in 11% of patients. Quantification of MSX1 transcripts in a panel of 24 T-ALL cell lines demonstrated overexpression in two examples. Comparative expression profiling indicated inhibition of the bone morphogenetic protein (BMP) signaling pathway, which was shown to inhibit MSX1 transcription. In the LOUCY cell line we identified conspicuous expression of CHRDL1 encoding a BMP inhibitor which mediated activation of MSX1. Promoter analyses demonstrated activation of CHRDL1 by oncogenic PITX1. Furthermore, knockdown and overexpression studies of hematopoietic transcription factors demonstrated that GATA2 and FOXC1 mediate activation and GATA3, LEF1, TAL1 and TOX repression of MSX1 transcription. Collectively, our findings suggest that MSX1 is physiologically restricted to lymphoid progenitors. The identification of deregulated BMP signaling may provide novel therapeutic options for the treatment of T-ALL. PMID:24844359

  19. Signaling by Tyrosine Kinases Negatively Regulates the Interaction between Transcription Factors and SMRT (Silencing Mediator of Retinoic Acid and Thyroid Hormone Receptor) Corepressor

    OpenAIRE

    Hong, Suk-Hyun; Wong, Chi-Wai; Privalsky, Martin L.

    1998-01-01

    Nuclear hormone receptors are hormone-regulated transcription factors that bind to specific sites on DNA and modulate the expression of adjacent target genes. Many nuclear hormone receptors display bimodal transcriptional properties; thyroid hormone receptors, for example, typically repress target gene expression in the absence of hormone, but activate target gene expression in the presence of hormone. The ability to repress is closely linked to the ability of the apo-receptor to physically b...

  20. How salicylic acid takes transcriptional control over jasmonic acid signaling

    Directory of Open Access Journals (Sweden)

    Lotte eCaarls

    2015-03-01

    Full Text Available Transcriptional regulation is a central process in plant immunity. The induction or repression of defense genes is orchestrated by signaling networks that are directed by plant hormones of which salicylic acid (SA and jasmonic acid (JA are the major players. Extensive cross-communication between the hormone signaling pathways allows for fine tuning of transcriptional programs, determining resistance to invaders and trade-offs with plant development. Here, we give an overview of how SA can control transcriptional reprogramming of JA-induced genes in Arabidopsis thaliana. SA can influence activity and/or localization of transcriptional regulators by post-translational modifications of transcription factors and co-regulators. SA-induced redox changes, mediated by thioredoxins and glutaredoxins, modify transcriptional regulators that are involved in suppression of JA-dependent genes, such as NPR1 and TGA transcription factors, which affects their localization or DNA binding activity. Furthermore, SA can mediate sequestering of JA-responsive transcription factors away from their target genes by stalling them in the cytosol or in complexes with repressor proteins in the nucleus. SA also affects JA-induced transcription by inducing degradation of transcription factors with an activating role in JA signaling, as was shown for the ERF transcription factor ORA59. Additionally, SA can induce negative regulators, among which WRKY transcription factors, that can directly or indirectly inhibit JA-responsive gene expression. Finally, at the DNA level, modification of histones by SA-dependent factors can result in repression of JA-responsive genes. These diverse and complex regulatory mechanisms affect important signaling hubs in the integration of hormone signaling networks. Some pathogens have evolved effectors that highjack hormone crosstalk mechanisms for their own good, which are described in this review as well.

  1. Expression of the MOZ-TIF2 oncoprotein in mice represses senescence.

    Science.gov (United States)

    Largeot, Anne; Perez-Campo, Flor Maria; Marinopoulou, Elli; Lie-a-Ling, Michael; Kouskoff, Valerie; Lacaud, Georges

    2016-04-01

    The MOZ-TIF2 translocation, which fuses monocytic leukemia zinc finger protein (MOZ) histone acetyltransferase (HAT) with the nuclear co-activator TIF2, is associated with the development of acute myeloid leukemia. We recently found that in the absence of MOZ HAT activity, p16(INK4a) transcriptional levels are significantly increased, triggering an early entrance into replicative senescence. Because oncogenic fusion proteins must bypass cellular safeguard mechanisms, such as senescence and apoptosis, to induce leukemia, we hypothesized that this repressive activity of MOZ over p16(INK4a) transcription could be preserved, or even reinforced, in MOZ leukemogenic fusion proteins, such as MOZ-TIF2. We describe here that, indeed, MOZ-TIF2 silences expression of the CDKN2A locus (p16(INK4a) and p19(ARF)), inhibits the triggering of senescence and enhances proliferation, providing conditions favorable to the development of leukemia. Furthermore, we describe that abolishing the MOZ HAT activity of the fusion protein leads to a significant increase in expression of the CDKN2A locus and the number of hematopoietic progenitors undergoing senescence. Finally, we report that inhibition of senescence by MOZ-TIF2 is associated with increased apoptosis, suggesting a role for the fusion protein in p53 apoptosis-versus-senescence balance. Our results underscore the importance of the HAT activity of MOZ, preserved in the fusion protein, for repression of the CDKN2A locus transcription and the subsequent block of senescence, a necessary step for the survival of leukemic cells. PMID:26854485

  2. Mutations that relieve nutritional repression of the Bacillus subtilis dipeptide permease operon.

    Science.gov (United States)

    Slack, F J; Mueller, J P; Sonenshein, A L

    1993-08-01

    The Bacillus subtilis dciA operon encodes a dipeptide transport complex that is induced rapidly as cells enter stationary phase and initiate sporulation. Expression of this operon in growing cells is repressed by glucose, by a mixture of amino acids, and by the AbrB protein. A genetic screen was devised to identify mutations that allow inappropriate expression from the dciA promoter during growth. These mutations resulted in increased dciA transcription during growth in nutrient broth, in minimal amino acids medium, and in minimal glucose medium. Some of the mutations, called dcs (dciA control site), were cloned and shown by sequence analysis to cluster near the start site of dciA transcription. Primer extension and in vitro transcription analysis revealed that the dcs mutations did not create a new promoter. These mutations may therefore disrupt an operator site necessary for the binding of a negative regulator responsive to the nutritional state of the cell. The dcs mutant promoters were still subject to AbrB control, suggesting that the dciA operon is regulated by at least two proteins, AbrB and a nutritionally responsive regulator. The gene(s) for the putative nutritional regulator may be defined by the cod (control of dciA) mutations, which appeared to relieve amino acid and glucose repression of dciA by altering a diffusible factor. An abrB cod double mutant exhibited high-level expression of dciA during exponential growth phase. PMID:8335620

  3. PPARγ partial agonist GQ-16 strongly represses a subset of genes in 3T3-L1 adipocytes

    Energy Technology Data Exchange (ETDEWEB)

    Milton, Flora Aparecida [Faculdade de Ciências da Saúde, Laboratório de Farmacologia Molecular, Universidade de Brasília (Brazil); Genomic Medicine, Houston Methodist Research Institute, Houston, TX (United States); Cvoro, Aleksandra [Genomic Medicine, Houston Methodist Research Institute, Houston, TX (United States); Amato, Angelica A. [Faculdade de Ciências da Saúde, Laboratório de Farmacologia Molecular, Universidade de Brasília (Brazil); Sieglaff, Douglas H.; Filgueira, Carly S.; Arumanayagam, Anithachristy Sigamani [Genomic Medicine, Houston Methodist Research Institute, Houston, TX (United States); Caro Alves de Lima, Maria do; Rocha Pitta, Ivan [Laboratório de Planejamento e Síntese de Fármacos – LPSF, Universidade Federal de Pernambuco (Brazil); Assis Rocha Neves, Francisco de [Faculdade de Ciências da Saúde, Laboratório de Farmacologia Molecular, Universidade de Brasília (Brazil); Webb, Paul, E-mail: pwebb@HoustonMethodist.org [Genomic Medicine, Houston Methodist Research Institute, Houston, TX (United States)

    2015-08-28

    Thiazolidinediones (TZDs) are peroxisome proliferator-activated receptor gamma (PPARγ) agonists that improve insulin resistance but trigger side effects such as weight gain, edema, congestive heart failure and bone loss. GQ-16 is a PPARγ partial agonist that improves glucose tolerance and insulin sensitivity in mouse models of obesity and diabetes without inducing weight gain or edema. It is not clear whether GQ-16 acts as a partial agonist at all PPARγ target genes, or whether it displays gene-selective actions. To determine how GQ-16 influences PPARγ activity on a gene by gene basis, we compared effects of rosiglitazone (Rosi) and GQ-16 in mature 3T3-L1 adipocytes using microarray and qRT-PCR. Rosi changed expression of 1156 genes in 3T3-L1, but GQ-16 only changed 89 genes. GQ-16 generally showed weak effects upon Rosi induced genes, consistent with partial agonist actions, but a subset of modestly Rosi induced and strongly repressed genes displayed disproportionately strong GQ-16 responses. PPARγ partial agonists MLR24 and SR1664 also exhibit disproportionately strong effects on transcriptional repression. We conclude that GQ-16 displays a continuum of weak partial agonist effects but efficiently represses some negatively regulated PPARγ responsive genes. Strong repressive effects could contribute to physiologic actions of GQ-16. - Highlights: • GQ-16 is an insulin sensitizing PPARγ ligand with reduced harmful side effects. • GQ-16 displays a continuum of weak partial agonist activities at PPARγ-induced genes. • GQ-16 exerts strong repressive effects at a subset of genes. • These inhibitor actions should be evaluated in models of adipose tissue inflammation.

  4. PPARγ partial agonist GQ-16 strongly represses a subset of genes in 3T3-L1 adipocytes

    International Nuclear Information System (INIS)

    Thiazolidinediones (TZDs) are peroxisome proliferator-activated receptor gamma (PPARγ) agonists that improve insulin resistance but trigger side effects such as weight gain, edema, congestive heart failure and bone loss. GQ-16 is a PPARγ partial agonist that improves glucose tolerance and insulin sensitivity in mouse models of obesity and diabetes without inducing weight gain or edema. It is not clear whether GQ-16 acts as a partial agonist at all PPARγ target genes, or whether it displays gene-selective actions. To determine how GQ-16 influences PPARγ activity on a gene by gene basis, we compared effects of rosiglitazone (Rosi) and GQ-16 in mature 3T3-L1 adipocytes using microarray and qRT-PCR. Rosi changed expression of 1156 genes in 3T3-L1, but GQ-16 only changed 89 genes. GQ-16 generally showed weak effects upon Rosi induced genes, consistent with partial agonist actions, but a subset of modestly Rosi induced and strongly repressed genes displayed disproportionately strong GQ-16 responses. PPARγ partial agonists MLR24 and SR1664 also exhibit disproportionately strong effects on transcriptional repression. We conclude that GQ-16 displays a continuum of weak partial agonist effects but efficiently represses some negatively regulated PPARγ responsive genes. Strong repressive effects could contribute to physiologic actions of GQ-16. - Highlights: • GQ-16 is an insulin sensitizing PPARγ ligand with reduced harmful side effects. • GQ-16 displays a continuum of weak partial agonist activities at PPARγ-induced genes. • GQ-16 exerts strong repressive effects at a subset of genes. • These inhibitor actions should be evaluated in models of adipose tissue inflammation

  5. Repressive coping and alexithymia in idiopathic environmental intolerance

    DEFF Research Database (Denmark)

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

    2010-01-01

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

  6. Legitimation, Kooptation und Repression im NS-Regime

    OpenAIRE

    Bialas, Wolfgang

    2012-01-01

    "This essay deals with the interplay between cooptation, legitimation, and repression with a special emphasis on the Nazi attitude and the behavior towards politically indifferent Germans. It analyzes the ideological framework of justification for the repressive Nazi politics that were also used to recruit followers who had a clean conscience and felt they were doing the right thing. Nazi ideology rejected the bourgeois - Christian concepts of universal human rights and dignity as anachronist...

  7. Relaxation of glycine receptor and onconeural gene transcription control in NRSF deficient small cell lung cancer cell lines.

    NARCIS (Netherlands)

    Neumann, S.B.; Seitz, R.; Gorzella, A.; Heister, A.J.; Doeberitz, M.K.; Becker, C.M.

    2004-01-01

    Negative regulation of many neuronal genes is mediated by the neuron-restrictive silencer factor (NRSF/repressor element-1 binding transcription factor, REST), which binds to the neuron-restrictive silencer element (NRSE/repressor element-1, RE-1) and thereby represses transcription of neuronal gene

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

    Directory of Open Access Journals (Sweden)

    Leoni Livia

    2008-06-01

    Full Text Available Abstract Background In Pseudomonas fluorescens ST, the promoter of the styrene catabolic operon, PstyA, is induced by styrene and is subject to catabolite repression. PstyA regulation relies on the StyS/StyR two-component system and on the IHF global regulator. The phosphorylated response regulator StyR (StyR-P activates PstyA in inducing conditions when it binds to the high-affinity site STY2, located about -40 bp from the transcription start point. A cis-acting element upstream of STY2, named URE, contains a low-affinity StyR-P binding site (STY1, overlapping the IHF binding site. Deletion of the URE led to a decrease of promoter activity in inducing conditions and to a partial release of catabolite repression. This study was undertaken to assess the relative role played by IHF and StyR-P on the URE, and to clarify if PstyA catabolite repression could rely on the interplay of these regulators. Results StyR-P and IHF compete for binding to the URE region. PstyA full activity in inducing conditions is achieved when StyR-P and IHF bind to site STY2 and to the URE, respectively. Under catabolite repression conditions, StyR-P binds the STY1 site, replacing IHF at the URE region. StyR-P bound to both STY1 and STY2 sites oligomerizes, likely promoting the formation of a DNA loop that closes the promoter in a repressed conformation. We found that StyR and IHF protein levels did not change in catabolite repression conditions, implying that PstyA repression is achieved through an increase in the StyR-P/StyR ratio. Conclusion We propose a model according to which the activity of the PstyA promoter is determined by conformational changes. An open conformation is operative in inducing conditions when StyR-P is bound to STY2 site and IHF to the URE. Under catabolite repression conditions StyR-P cellular levels would increase, displacing IHF from the URE and closing the promoter in a repressed conformation. The balance between the open and the closed

  9. Inflammatory stimuli promote growth and invasion of pancreatic cancer cells through NF-κB pathway dependent repression of PP2Ac.

    Science.gov (United States)

    Tao, Min; Liu, Lu; Shen, Meng; Zhi, Qiaoming; Gong, Fei-Ran; Zhou, Binhua P; Wu, Yadi; Liu, Haiyan; Chen, Kai; Shen, Bairong; Wu, Meng-Yao; Shou, Liu-Mei; Li, Wei

    2016-01-01

    Previous studies have indicated that inflammatory stimulation represses protein phosphatase 2A (PP2A), a well-known tumor suppressor. However, whether PP2A repression participates in pancreatic cancer progression has not been verified. We used lipopolysaccharide (LPS) and macrophage-conditioned medium (MCM) to establish in vitro inflammation models, and investigated whether inflammatory stimuli affect pancreatic cancer cell growth and invasion PP2A catalytic subunit (PP2Ac)-dependently. Via nude mouse models of orthotopic tumor xenografts and dibutyltin dichloride (DBTC)-induced chronic pancreatitis, we evaluated the effect of an inflammatory microenvironment on PP2Ac expression in vivo. We cloned the PP2Acα and PP2Acβ isoform promoters to investigate the PP2Ac transcriptional regulation mechanisms. MCM accelerated pancreatic cancer cell growth; MCM and LPS promoted cell invasion. DBTC promoted xenograft growth and metastasis, induced tumor-associated macrophage infiltration, promoted angiogenesis, activated the nuclear factor-κB (NF-κB) pathway, and repressed PP2Ac expression. In vitro, LPS and MCM downregulated PP2Ac mRNA and protein. PP2Acα overexpression attenuated JNK, ERK, PKC, and IKK phosphorylation, and impaired LPS/MCM-stimulated cell invasion and MCM-promoted cell growth. LPS and MCM activated the NF-κB pathway in vitro. LPS and MCM induced IKK and IκB phosphorylation, leading to p65/RelA nuclear translocation and transcriptional activation. Overexpression of the dominant negative forms of IKKα attenuated LPS and MCM downregulation of PP2Ac, suggesting inflammatory stimuli repress PP2Ac expression NF-κB pathway-dependently. Luciferase reporter gene assay verified that LPS and MCM downregulated PP2Ac transcription through an NF-κB-dependent pathway. Our study presents a new mechanism in inflammation-driven cancer progression through NF-κB pathway-dependent PP2Ac repression. PMID:26761431

  10. Transcriptional regulation by Polycomb group proteins

    DEFF Research Database (Denmark)

    Di Croce, Luciano; Helin, Kristian

    2013-01-01

    Polycomb group (PcG) proteins are epigenetic regulators of transcription that have key roles in stem-cell identity, differentiation and disease. Mechanistically, they function within multiprotein complexes, called Polycomb repressive complexes (PRCs), which modify histones (and other proteins) and...... silence target genes. The dynamics of PRC1 and PRC2 components has been the focus of recent research. Here we discuss our current knowledge of the PRC complexes, how they are targeted to chromatin and how the high diversity of the PcG proteins allows these complexes to influence cell identity....

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

    Directory of Open Access Journals (Sweden)

    Karen D. Cowden Dahl

    2009-11-01

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

  12. Tumor protein 53-induced nuclear protein 1 (TP53INP1 enhances p53 function and represses tumorigenesis

    Directory of Open Access Journals (Sweden)

    Jeyran eShahbazi

    2013-05-01

    Full Text Available Tumor protein 53-induced nuclear protein 1 (TP53INP1 is a stress-induced p53 target gene whose expression is modulated by transcription factors such as p53, p73 and E2F1. TP53INP1 gene encodes two isoforms of TP53INP1 proteins, TP53INP1α and TP53INP1β, both of which appear to be key elements in p53 function. When associated with homeodomain-interacting protein kinase-2 (HIPK2, TP53INP1 phosphorylates p53 protein at Serine 46, enhances p53 protein stability and its transcriptional activity, leading to transcriptional activation of p53 target genes such as p21, PIG-3 and MDM2, cell growth arrest and apoptosis upon DNA damage stress. The anti-proliferative and pro-apoptotic activities of TP53INP1 indicate that TP53INP1 has an important role in cellular homeostasis and DNA damage response. Deficiency in TP53INP1 expression results in increased tumorigenesis; while TP53INP1 expression is repressed during early stages of cancer by factors such as miR-155. This review aims to summarize the roles of TP53INP1 in blocking tumor progression through p53-dependant and p53-independent pathways, as well as the elements which repress TP53INP1 expression, hence highlighting its potential as a therapeutic target in cancer treatment.

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

    Science.gov (United States)

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

    2014-05-01

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

  14. AP-2α suppresses skeletal myoblast proliferation and represses fibroblast growth factor receptor 1 promoter activity

    International Nuclear Information System (INIS)

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

  15. A systems biology approach to study glucose repression in the yeast Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Westergaard, Steen Lund; Soberano de Oliveira, Ana Paula; Bro, Christoffer;

    2007-01-01

    repression of a wide range of genes involved to utilization of alternative carbon sources. In this work, we applied a systems biology approach to study the interaction between these two pathways. Through genome-wide transcription analysis of strains with disruption of HXK2, GRR1, MIG1, the combination of MIG......1 and MIG2, and the parentel strain, we identified 393 genes to have significantly changed expression levels. To identify co-regulation patterns in the different strains we applied principal component analysis. Disruption of either GRR1 or HXK2 were both found to have profound effects on...... reporter metabolites, and found that there is a high degree of consistency between the identified reporter metabolites and the physiological effects observed in the different mutants . Our systems biology approach points to close interaction between the two pathways, and our metabolism driven analysis of...

  16. Characterization of a novel radiation-inducible transcript, uscA, and analysis of its transcriptional regulation

    International Nuclear Information System (INIS)

    The transcriptional expression of the uscA promote (PuscA) only occurred under aerobic conditions and a dose of 2Gy maximally activated transcription of PuscA. However, various environmental stress including physical shocks (pH, temperature, osmotic shock), DNA damaging agents (UV and MMC) or oxidative stressagents (paraquat, menadione, and H2O2) didn't cause the transcriptional activationof PuscA. The transcription of uscA was initiated at 170 bp upstream of the cyoA start codon, and ended around the ampG stop codon. The size of uscA was determined through reverse transcription assay, approximately 250 bp. The deletion analysis of uscA promoter demonstrates that radiation inducibility of PuscA is mediated by sequences present between -20 and +111 relativeto +1 of PuscA and radiation causes PuscA activation thorough permitting the expression that is repressed under non-irradiated conditions

  17. Transcriptional control of stem cell maintenance in the Drosophila intestine.

    Science.gov (United States)

    Bardin, Allison J; Perdigoto, Carolina N; Southall, Tony D; Brand, Andrea H; Schweisguth, François

    2010-03-01

    Adult stem cells maintain tissue homeostasis by controlling the proper balance of stem cell self-renewal and differentiation. The adult midgut of Drosophila contains multipotent intestinal stem cells (ISCs) that self-renew and produce differentiated progeny. Control of ISC identity and maintenance is poorly understood. Here we find that transcriptional repression of Notch target genes by a Hairless-Suppressor of Hairless complex is required for ISC maintenance, and identify genes of the Enhancer of split complex [E(spl)-C] as the major targets of this repression. In addition, we find that the bHLH transcription factor Daughterless is essential to maintain ISC identity and that bHLH binding sites promote ISC-specific enhancer activity. We propose that Daughterless-dependent bHLH activity is important for the ISC fate and that E(spl)-C factors inhibit this activity to promote differentiation. PMID:20147375

  18. The Saccharomyces cerevisiae ADR1 gene is a positive regulator of transcription of genes encoding peroxisomal proteins.

    OpenAIRE

    M. Simon; Adam, G.; Rapatz, W; Spevak, W; Ruis, H

    1991-01-01

    Expression of the CTA1 gene of Saccharomyces cerevisiae, encoding catalase A, the peroxisomal catalase of this yeast, is sensitive to glucose repression. A DNA fragment cloned as a multicopy plasmid suppressing the glucose repression of CTA1 transcription was demonstrated to contain the ADR1 gene. Multiple copies of ADR1 increased catalase A formation not only on 10% glucose, but also on ethanol medium and in the presence of oleic acid, an inducer of peroxisome proliferation. Compared with wi...

  19. GW4064, an Agonist of Farnesoid X Receptor, Represses CYP3A4 Expression in Human Hepatocytes by Inducing Small Heterodimer Partner Expression

    OpenAIRE

    Zhang, Shu; Pan, Xian; Jeong, Hyunyoung

    2015-01-01

    Farnesoid X receptor (FXR) functions as a regulator of bile acid and lipid homeostasis and is recognized as a promising therapeutic target for metabolic diseases. The biologic function of FXR is mediated in part by a small heterodimer partner (SHP); ligand-activated FXR enhances SHP expression, and SHP in turn represses the activity of multiple transcription factors. This study aimed to investigate the effect of FXR activation on expression of the major drug-metabolizing enzyme CYP3A4. The ef...

  20. DOF AFFECTING GERMINATION 2 is a positive regulator of light-mediated seed germination and is repressed by DOF AFFECTING GERMINATION 1.

    OpenAIRE

    Santopolo, Silvia; Boccaccini, Alessandra; Lorrai, Riccardo; Ruta, Veronica; Capauto, Davide; Minutello, Emanuele; Serino, Giovanna; Costantino, Paolo; Vittorioso, Paola

    2015-01-01

    Background The transcription factor DOF AFFECTING GERMINATION1 (DAG1) is a repressor of the light-mediated seed germination process. DAG1 acts downstream PHYTOCHROME INTERACTING FACTOR3-LIKE 5 (PIL5), the master repressor, and negatively regulates gibberellin biosynthesis by directly repressing the biosynthetic gene AtGA3ox1. The Dof protein DOF AFFECTING GERMINATION (DAG2) shares a high degree of aminoacidic identity with DAG1. While DAG1 inactivation considerably increases the germination c...

  1. Bach2 represses effector programmes to stabilize Treg-mediated immune homeostasis

    Science.gov (United States)

    Roychoudhuri, Rahul; Hirahara, Kiyoshi; Mousavi, Kambiz; Clever, David; Klebanoff, Christopher A.; Bonelli, Michael; Sciume, Giuseppe; Zare, Hossein; Vahedi, Golnaz; Dema, Barbara; Yu, Zhiya; Liu, Hui; Takahashi, Hayato; Rao, Mahadev; Muranski, Pawel; Crompton, Joseph G.; Punkosdy, George; Bedognetti, Davide; Wang, Ena; Hoffmann, Victoria; Rivera, Juan; Marincola, Francesco M.; Nakamura, Atsushi; Sartorelli, Vittorio; Kanno, Yuka; Gattinoni, Luca; Muto, Akihiko; Igarashi, Kazuhiko; O’Shea, John J.; Restifo, Nicholas P.

    2013-01-01

    Through their functional diversification, distinct lineages of CD4+ T cells play key roles in either driving or constraining immune-mediated pathology. Transcription factors are critical in the generation of cellular diversity, and negative regulators antagonistic to alternate fates often act in conjunction with positive regulators to stabilize lineage commitment1. Genetic polymorphisms within a single locus encoding the transcription factor BACH2 are associated with numerous autoimmune and allergic diseases including asthma2, Crohn’s disease3–4, coeliac disease5, vitiligo6, multiple sclerosis7 and type 1 diabetes8. While these associations point to a shared mechanism underlying susceptibility to diverse immune-mediated diseases, a function for Bach2 in the maintenance of immune homeostasis has not been established. Here, we define Bach2 as a broad regulator of immune activation that stabilizes immunoregulatory capacity while repressing the differentiation programmes of multiple effector lineages in CD4+ T cells. Bach2 was required for efficient formation of regulatory (Treg) cells and consequently for suppression of lethal inflammation in a manner that was Treg cell dependent. Assessment of the genome-wide function of Bach2, however, revealed that it represses genes associated with effector cell differentiation. Consequently, its absence during Treg polarization resulted in inappropriate diversion to effector lineages. In addition, Bach2 constrained full effector differentiation within Th1, Th2 and Th17 cell lineages. These findings identify Bach2 as a key regulator of CD4+ T-cell differentiation that prevents inflammatory disease by controlling the balance between tolerance and immunity. PMID:23728300

  2. Involvement of a Putative Cyclic AMP Receptor Protein (CRP)-Like Binding Sequence and a CRP-Like Protein in Glucose-Mediated Catabolite Repression of thn Genes in Rhodococcus sp. Strain TFB

    OpenAIRE

    Tomás-Gallardo, Laura; Santero, Eduardo; Floriano, Belén

    2012-01-01

    Glucose catabolite repression of tetralin catabolic genes in Rhodococcus sp. strain TFB was shown to be exerted by a protein homologous to transcriptional regulators of the cyclic AMP receptor (CRP)-FNR family. The protein was detected bound to putative CRP-like boxes localized at the promoters of the thnA1 and thnS genes.

  3. Involvement of a putative cyclic amp receptor protein (CRP)-like binding sequence and a CRP-like protein in glucose-mediated catabolite repression of thn genes in Rhodococcus sp. strain TFB.

    Science.gov (United States)

    Tomás-Gallardo, Laura; Santero, Eduardo; Floriano, Belén

    2012-08-01

    Glucose catabolite repression of tetralin catabolic genes in Rhodococcus sp. strain TFB was shown to be exerted by a protein homologous to transcriptional regulators of the cyclic AMP receptor (CRP)-FNR family. The protein was detected bound to putative CRP-like boxes localized at the promoters of the thnA1 and thnS genes. PMID:22636000

  4. Transcriptional control of stem cell maintenance in the Drosophila intestine

    OpenAIRE

    Bardin, Allison J.; Perdigoto, Carolina N.; Southall, Tony D.; Brand, Andrea H; Schweisguth, François

    2010-01-01

    Adult stem cells maintain tissue homeostasis by controlling the proper balance of stem cell self-renewal and differentiation. The adult midgut of Drosophila contains multipotent intestinal stem cells (ISCs) that self-renew and produce differentiated progeny. Control of ISC identity and maintenance is poorly understood. Here we find that transcriptional repression of Notch target genes by a Hairless-Suppressor of Hairless complex is required for ISC maintenance, and identify genes of the Enhan...

  5. TRANSCRIPTIONAL REGULATION OF BONE MARROW THROMBOPOIETIN BY PLATELET PROTEINS

    OpenAIRE

    McIntosh, Bryan; Kaushansky, Kenneth

    2008-01-01

    Platelet production is regulated primarily by the cytokine thrombopoietin (TPO). Although TPO is expressed in several different tissues, only in the bone marrow has the level of expression been reported to increase in response to reduced numbers of platelets. In these studies we demonstrate that platelet granule proteins are able to transcriptionally repress TPO mRNA expression in a marrow stromal cell line as well as in primary bone marrow stromal cell cultures. Like TPO mRNA, secretion of T...

  6. A novel CRE recombinase assay for quantification of GAL10-non coding RNA suppression on transcriptional leakage.

    Science.gov (United States)

    Zacharioudakis, Ioannis; Tzamarias, Dimitris

    2016-05-13

    Eukaryotic promoters are tightly regulated and often securely repressed. However, recent reports indicated that transcripts originating from the strictly regulated GAL1-10 promoter can be detected by single-yeast cell imaging under repressive conditions. Such leaky, noisy transcription events were suppressed by a long non-coding RNA (GAL10-ncRNA) transcribed within the GAL1-10 locus. It was further suggested that GAL10-ncRNA repression of GAL1-10 promoter leakage tunes the bimodal expression pattern of the GAL network. Independent evidence has indicated that GAL10-ncRNA transcription establishes a repressive chromatin structure through the Set2 histone methyl-transferase and the Rpd3s histone deacetylase complex. In this report we set up a novel, simple genetic Cre recombinase assay in order to readily quantify transcriptional leakage from tightly repressed promoters. By applying this method we demonstrate that GAL10-ncRNA, Set2p and Rpd3p all suppress leaky GAL1-10 driven transcription. However, GAL10-ncRNA repression is not mediated by Set2p or Rpd3p. Moreover, as opposed to GAL10-ncRNA transcription, Set2 and Rpd3 do not influence the bimodal expression of GAL genes, despite their effect on GAL1-10 promoter leakage. We suggest that GAL10-ncRNA tunes the expression of GAL genes by additional mechanisms besides suppressing leaky transcription from the GAL1-10 promoter. PMID:27073161

  7. Prdm12 specifies V1 interneurons through cross-repressive interactions with Dbx1 and Nkx6 genes in Xenopus.

    Science.gov (United States)

    Thélie, Aurore; Desiderio, Simon; Hanotel, Julie; Quigley, Ian; Van Driessche, Benoit; Rodari, Anthony; Borromeo, Mark D; Kricha, Sadia; Lahaye, François; Croce, Jenifer; Cerda-Moya, Gustavo; Ordoño Fernandez, Jesús; Bolle, Barbara; Lewis, Katharine E; Sander, Maike; Pierani, Alessandra; Schubert, Michael; Johnson, Jane E; Kintner, Christopher R; Pieler, Tomas; Van Lint, Carine; Henningfeld, Kristine A; Bellefroid, Eric J; Van Campenhout, Claude

    2015-10-01

    V1 interneurons are inhibitory neurons that play an essential role in vertebrate locomotion. The molecular mechanisms underlying their genesis remain, however, largely undefined. Here, we show that the transcription factor Prdm12 is selectively expressed in p1 progenitors of the hindbrain and spinal cord in the frog embryo, and that a similar restricted expression profile is observed in the nerve cord of other vertebrates as well as of the cephalochordate amphioxus. Using frog, chick and mice, we analyzed the regulation of Prdm12 and found that its expression in the caudal neural tube is dependent on retinoic acid and Pax6, and that it is restricted to p1 progenitors, due to the repressive action of Dbx1 and Nkx6-1/2 expressed in the adjacent p0 and p2 domains. Functional studies in the frog, including genome-wide identification of its targets by RNA-seq and ChIP-Seq, reveal that vertebrate Prdm12 proteins act as a general determinant of V1 cell fate, at least in part, by directly repressing Dbx1 and Nkx6 genes. This probably occurs by recruiting the methyltransferase G9a, an activity that is not displayed by the amphioxus Prdm12 protein. Together, these findings indicate that Prdm12 promotes V1 interneurons through cross-repressive interactions with Dbx1 and Nkx6 genes, and suggest that this function might have only been acquired after the split of the vertebrate and cephalochordate lineages. PMID:26443638

  8. Octamerization of lambda CI repressor is needed for effective repression of P(RM) and efficient switching from lysogeny.

    Science.gov (United States)

    Dodd, I B; Perkins, A J; Tsemitsidis, D; Egan, J B

    2001-11-15

    The CI repressor of bacteriophage lambda is a model for the role of cooperativity in the efficient functioning of genetic switches. Pairs of CI dimers interact to cooperatively occupy adjacent operator sites at O(R) and at O(L). These CI tetramers repress the lytic promoters and activate transcription of the cI gene from P(RM). CI is also able to octamerize, forming a large DNA loop between O(R) and O(L), but the physiological role of this is unclear. Another puzzle is that, although a dimer of CI is able to repress P(RM) by binding to the third operator at O(R), O(R)3, this binding seems too weak to affect CI production in the lysogenic state. Here we show that repression of P(RM) at lysogenic CI concentrations is absolutely dependent on O(L), in this case 3.8 kb away. A mutant defective in this CI negative autoregulation forms a lysogen with elevated CI levels that cannot efficiently switch from lysogeny to lytic development. Our results invalidate previous evidence that Cro binding to O(R)3 is important in prophage induction. We propose the octameric CI:O(R)-O(L) complex increases the affinity of CI for O(R)3 by allowing a CI tetramer to link O(R)3 and the third operator at O(L), O(L)3. PMID:11711436

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

    Science.gov (United States)

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

    2016-01-01

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

  10. Reduced specificity of negative autobiographical memories in repressive coping.

    Science.gov (United States)

    Geraerts, Elke; Dritschel, Barbara; Kreplin, Ute; Miyagawa, Liv; Waddington, Joanne

    2012-12-01

    The current study examined memory specificity of autobiographical memories in individuals with and without a repressive coping style. It seems conceivable that reduced memory specificity may be a way to reduce accessibility of negative experiences, one of the hallmark features of a repressive coping style. It was therefore hypothesized that repressors would show reduced specificity when retrieving negative memories. In order to study memory specificity, participants (N = 103) performed the autobiographical memory test. Results showed that individuals with a repressive coping style were significantly less specific in retrieving negative experiences, relative to control groups of low anxious, high anxious, and defensive high anxious individuals. This result was restricted to negative memory retrieval, as participants did not differ in memory specificity for positive experiences. These results show that repressors retrieve negative autobiographical memories in an overgeneral way, possibly in order to avoid negative affect. PMID:23200428

  11. Transcript analysis of nrrF, a Fur repressed sRNA of Neisseria gonorrhoeae

    Science.gov (United States)

    Like most microorganisms, Neisseria gonorrhoeae alters gene expression in response to iron availability. The ferric uptake regulator Fur has been shown to be involved in controlling this response, but the extent of this involvement remains unknown. It is known that in addition to working directly to...

  12. The TR2 and TR4 orphan nuclear receptors repress Gata1 transcription

    OpenAIRE

    Tanabe, Osamu; Shen, Yannan; Liu, Qinghui; Campbell, Andrew D.; Kuroha, Takashi; Yamamoto, Masayuki; Engel, James Douglas

    2007-01-01

    When the orphan nuclear receptors TR2 and TR4, the DNA-binding subunits of the DRED repressor complex, are forcibly expressed in erythroid cells of transgenic mice, embryos exhibit a transient mid-gestational anemia as a consequence of a reduction in the number of primitive erythroid cells. GATA-1 mRNA is specifically diminished in the erythroid cells of these TR2/TR4 transgenic embryos as it is in human CD34+ progenitor cells transfected with forcibly expressed TR2/TR4. In contrast, in loss-...

  13. Multiple Phytochrome-Interacting bHLH Transcription Factors Repress Premature Seedling Photomorphogenesis in Darkness

    Science.gov (United States)

    An important contributing factor to the success of terrestrial flowering plants in colonizing the land was the evolution of a developmental strategy, termed skotomorphogenesis, whereby postgerminative seedlings emerging from buried seed grow vigorously upward in the subterranean darkness toward the ...

  14. FOXP3 Regulates Sensitivity of Cancer Cells to Irradiation by Transcriptional Repression of BRCA1

    OpenAIRE

    Li, Weiquan; Katoh, Hiroto; Wang, Lizhong; Yu, Xiaochun; Du, Zhanwen; Yan, Xiaoli; Zheng, Pan; Liu, Yang

    2013-01-01

    FOXP3 is an X-linked tumor suppressor gene and a master regulator in T regulatory cell function. This gene has been found to be mutated frequently in breast and prostate cancers and to inhibit tumor cell growth, but its functional significance in DNA repair has not been studied. We found that FOXP3 silencing stimulates homologous recombination-mediated DNA repair and also repair of γ-irradiation-induced DNA damage. Expression profiling and chromatin-immunoprecipitation analyses revealed that ...

  15. Poly(ADP-Ribose) Polymerase 1 Promotes Transcriptional Repression of Integrated Retroviruses

    OpenAIRE

    Bueno, Murilo T. D.; Reyes, Daniel; Valdes, Luis; Saheba, Adarsh; Urias, Eduardo; Mendoza, Crystal; Fregoso, Oliver I.; de Llano, Manuel

    2013-01-01

    Poly(ADP-ribose) polymerase 1 (PARP-1) is a cellular enzyme with a fundamental role in DNA repair and the regulation of chromatin structure, processes involved in the cellular response to retroviral DNA integration. However, the function of PARP-1 in retroviral DNA integration is controversial, probably due to the functional redundancy of the PARP family in mammalian cells. We evaluated the function of PARP-1 in retroviral infection using the chicken B lymphoblastoid cell line DT40. These cel...

  16. Functionality of unliganded VDR in breast cancer cells: repressive action on CYP24 basal transcription

    OpenAIRE

    Alimirah, Fatouma; Vaishnav, Avani; McCormick, Michael; Echchgadda, Ibtissam; Chatterjee, Bandana; Mehta, Rajendra G.; Peng, Xinjian

    2010-01-01

    It is well-established that CYP24, an immediate target gene of VDR is upregulated by VDR ligands. This study is focused on the functional role of unliganded VDR by investigating the correlation between the expression of VDR protein and basal mRNA levels of CYP24 in breast cancer cell lines. Analyses of multiple breast cancer cell lines demonstrated an inverse correlation between VDR protein expression and CYP24 mRNA expression levels; while in the presence of ligand, VDR protein level was pos...

  17. Cooperative activation of transcription by bovine papillomavirus type 1 E2 can occur over a large distance.

    OpenAIRE

    Thierry, F; Dostatni, N; Arnos, F; Yaniv, M

    1990-01-01

    The viral transcriptional factors encoded by the E2 open reading frame bind to the specific DNA sequence elements ACCGNNNNCGGT, allowing activation or repression of transcription. We have analyzed bovine papillomavirus type 1 E2 transactivation using recombinant genes containing E2-binding sites inserted at either 3' or 5' positions relative to the heterologous transcriptional initiation site of the herpes simplex virus thymidine kinase gene. In these hybrid plasmids, strong transactivation r...

  18. The JNKs differentially regulate RNA polymerase III transcription by coordinately modulating the expression of all TFIIIB subunits

    OpenAIRE

    Zhong and, Shuping; Johnson, Deborah L.

    2009-01-01

    RNA polymerase (pol) III-dependent transcription is subject to stringent regulation by tumor suppressors and oncogenic proteins and enhanced RNA pol III transcription is essential for cellular transformation and tumorigenesis. Since the c-Jun N-terminal kinases (JNKs) display both oncogenic and tumor suppressor properties, the roles of these proteins in regulating RNA pol III transcription were examined. In both mouse and human cells, loss or reduction in JNK1 expression represses RNA pol III...

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

    Directory of Open Access Journals (Sweden)

    Balliet John W

    2006-06-01

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

  20. Analysis of the upstream activating sequence and site of carbon and nitrogen source repression in the promoter of an early-induced sporulation gene of Bacillus subtilis.

    OpenAIRE

    Frisby, D; Zuber, P

    1991-01-01

    The transcription from the spoVG promoter of Bacillus subtilis is induced at the start of the stationary phase of growth and is dependent on the expression of the spoOA, spoOB, and spoOH genes. It is repressed in cells grown in the presence of excess glucose and glutamine and is under the negative control of the abrB gene. The spoOA and spoOB gene products function to suppress the negative control exerted by abrB. Transcription initiation requires the form of RNA polymerase holoenzyme that co...

  1. Targeted regulation of imprinted genes by synthetic zinc-finger transcription factors.

    Science.gov (United States)

    Jouvenot, Y; Ginjala, V; Zhang, L; Liu, P-Q; Oshimura, M; Feinberg, A P; Wolffe, A P; Ohlsson, Rolf; Gregory, P D

    2003-03-01

    Epigenetic control of transcription is essential for mammalian development and its deregulation causes human disease. For example, loss of proper imprinting control at the IGF2-H19 domain is a hallmark of cancer and Beckwith-Wiedemann syndrome, with no targeted therapeutic approaches available. To address this deficiency, we engineered zinc-finger transcription proteins (ZFPs) that specifically activate or repress the IGF2 and H19 genes in a domain-dependent manner. Importantly, we used these ZFPs successfully to reactivate the transcriptionally silent IGF2 and H19 alleles, thus overriding the natural mechanism of imprinting and validating an entirely novel avenue for 'transcription therapy' of human disease. PMID:12621455

  2. Roles of histones and nucleosomes in gene transcription

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This article reviews the latest research developments in the field of eukaryotic gene regulation by the structural alterations of chromatin and nucleosomes. The following issues are briefly addressed: (ⅰ) nucleosome and histone modifications by both the ATP-dependent remodel- ing com-plexes and the histone acetyltransferases and their roles in gene activation; (ⅱ) competitive binding of histones and transcription factors on gene promoters, and transcription repression by nucleosomes; and (ⅲ) influences of linker histone H1 on gene regulation. Meanwhile, the significance and impact of these new research progresses, as well as issues worthwhile for further study are commented.

  3. CONSTITUTIVE PHOTOMORPHOGENIC 10 (COP10 Contributes to Floral Repression under Non-Inductive Short Days in Arabidopsis

    Directory of Open Access Journals (Sweden)

    Min-Young Kang

    2015-11-01

    Full Text Available In Arabidopsis, CONSTITUTIVE PHOTOMORPHOGENIC/DE-ETIOLATED/FUSCA (COP/DET/FUS genes act in repression of photomorphogenesis in darkness, and recent reports revealed that some of these genes, such as COP1 and DET1, also have important roles in controlling flowering time and circadian rhythm. The COP/DET/FUS protein COP10 interacts with DET1 and DNA DAMAGE-BINDING PROTEIN 1 (DDB1 to form a CDD complex and represses photomorphogenesis in darkness. The cop10-4 mutants flower normally in inductive long days (LD but early in non-inductive short days (SD compared with wild type (WT; however, the role of COP10 remains unknown. Here, we investigate the role of COP10 in SD-dependent floral repression. Reverse transcription-quantitative PCR revealed that in SD, expression of the LD-dependent floral inducers GI, FKF1, and FT significantly increased in cop10-4 mutants, compared with WT. This suggests that COP10 mainly regulates FT expression in a CO-independent manner. We also show that COP10 interacts with GI in vitro and in vivo, suggesting that COP10 could also affect GI function at the posttranslational level. Moreover, FLC expression was repressed drastically in cop10-4 mutants and COP10 interacts with MULTICOPY SUPPRESSOR OF IRA1 4 (MSI4/FVE (MSI4/FVE, which epigenetically inhibits FLC expression. These data suggest that COP10 contributes to delaying flowering in the photoperiod and autonomous pathways by downregulating FT expression under SD.

  4. Aurora kinase B activity is modulated by thyroid hormone during transcriptional activation of pituitary genes

    OpenAIRE

    Tardáguila, Manuel; González-Gugel, Elena; Sánchez-Pacheco, Aurora

    2011-01-01

    Covalent histone modifications clearly play an essential role in ligand-dependent transcriptional regulation by nuclear receptors. One of the predominant mechanisms used by nuclear receptors to activate or repress target-gene transcription is the recruitment of coregulatory factors capable of covalently modify the amino terminal ends of histones. Here we show that the thyroid hormone (T3) produces a rapid increase in histone H3Ser10 phosphorylation (H3Ser10ph) concomitant to the rapid displac...

  5. HISTONE H3 LYSINE 9 METHYLTRANSFERASE G9a IS A TRANSCRIPTIONAL COACTIVATOR FOR NUCLEAR RECEPTORS*

    OpenAIRE

    David Y. Lee; Northrop, Jeffrey P.; Kuo, Min-Hao; Stallcup, Michael R.

    2006-01-01

    Methylation of Lys-9 of histone H3 has been associated with repression of transcription. G9a is a histone H3 Lys-9 methyltransferase localized in euchromatin and acts as a corepressor for specific transcription factors. Here we demonstrate that G9a also functions as a coactivator for nuclear receptors, cooperating synergistically with nuclear receptor coactivators GRIP1, CARM1, and p300 in transient transfection assays. This synergy depends strongly on the arginine-specific protein methyltran...

  6. Alk Is a Transcriptional Target of LMO4 and ERα that Promotes Cocaine Sensitization and Reward

    OpenAIRE

    Lasek, Amy W.; Gesch, Julie; Giorgetti, Francesco; Kharazia, Viktor; Heberlein, Ulrike

    2011-01-01

    Previously, we showed that the mouse LIM-domain only 4 (Lmo4) gene, which encodes a protein containing two zinc-finger LIM domains that interact with various DNA-binding transcription factors, attenuates behavioral sensitivity to repeated cocaine administration. Here we show that transcription of anaplastic lymphoma kinase (Alk) is repressed by LMO4 in the striatum and that Alk promotes the development of cocaine sensitization and conditioned place preference, a measure of cocaine reward. Sin...

  7. Transcripts of Vp-1 homeologues are misspliced in modern wheat and ancestral species

    OpenAIRE

    McKibbin, Rowan S.; Wilkinson, Mark D; Bailey, Paul C.; Flintham, John E.; Andrew, Lucy M.; Lazzeri, Paul A.; Gale, Mike D.; Lenton, John R.; Holdsworth, Michael J.

    2002-01-01

    The maize (Zea mays) Viviparous 1 (Vp1) transcription factor has been shown previously to be a major regulator of seed development, simultaneously activating embryo maturation and repressing germination. Hexaploid bread wheat (Triticum aestivum) caryopses are characterized by relatively weak embryo dormancy and are susceptible to preharvest sprouting (PHS), a phenomenon that is phenotypically similar to the maize vp1 mutation. Analysis of Vp-1 transcript structure in wheat embryos during grai...

  8. Repression of Fgf signaling by sprouty1-2 regulates cortical patterning in two distinct regions and times.

    Science.gov (United States)

    Faedo, Andrea; Borello, Ugo; Rubenstein, John L R

    2010-03-17

    A fundamental question in developmental biology is how signaling pathways establish a transcription factor code that controls cell proliferation, regional fate and cell fate. Morphogenesis of the rostral telencephalon is controlled in part by Fgf signaling from the rostral patterning center. How Fgf signaling is regulated in the telencephalon is critical for understanding cerebral cortex formation. Here we show that mouse Sprouty1 and Sprouty2 (Spry1-2), which encode negative feedback regulators of Fgf signaling, are affecting cortical proliferation, differentiation, and the expression of genes regulating progenitor identity in the ventricular zone. In addition, Spry2 has a later function in regulating the MAPK pathway, proliferation, and gene expression in the cortex at mid-neurogenesis. Finally, we provide evidence that Coup-TFI, a transcription factor that promotes caudal fate, does so through repressing Fgf signaling, in part by promoting Spry expression. PMID:20237272

  9. Repression of Fgf-Signaling by Sprouty1-2 Regulates Cortical Patterning in Two Distinct Regions and Times

    Science.gov (United States)

    Faedo, Andrea; Borello, Ugo; Rubenstein, John L. R.

    2010-01-01

    A fundamental question in developmental biology is how signaling pathways establish a transcription factor code that controls cell proliferation, regional fate and cell fate. Morphogenesis of the rostral telencephalon is controlled in part by Fgf-signaling from the rostral patterning center (RPC). How Fgf signaling is regulated in the telencephalon is critical for understanding cerebral cortex formation. Here we show that mouse Sprouty1 and Sprouty2 (Spry1-2), which encode negative feedback regulators of Fgf signaling, are affecting cortical proliferation, differentiation, and the expression of genes regulating progenitor identity in the ventricular zone. In addition, Spry2 has a later function in regulating the MAPK pathway, proliferation and gene expression in the cortex at mid-neurogenesis. Finally, we provide evidence that Coup-TFI, a transcription factor that promotes caudal fate, does so through repressing Fgf-signaling, in part by promoting Spry expression. PMID:20237272

  10. The origin recognition complex links replication, sister chromatid cohesion and transcriptional silencing in Saccharomyces cerevisiae

    NARCIS (Netherlands)

    Suter, Bernhard; Tong, Amy; Chang, Michael; Yu, Lisa; Brown, Grant W; Boone, Charles; Rine, Jasper

    2004-01-01

    Mutations in genes encoding the origin recognition complex (ORC) of Saccharomyces cerevisiae affect initiation of DNA replication and transcriptional repression at the silent mating-type loci. To explore the function of ORC in more detail, a screen for genetic interactions was undertaken using large

  11. Polyvinyl chloride catheters with repressed migration of plasticizers

    Czech Academy of Sciences Publication Activity Database

    Sedláček, T.; Polášková, M.; Kašpárková, V.; Filip, Petr; Sáha, P.

    Larnaca : Polymer Processing Society, 2009, s. 243. [Polymer Processing Society Europe/Africa Regional Meeting. Larnaca (GR), 18.10.2009-21.10.2009] Institutional research plan: CEZ:AV0Z20600510 Keywords : Polyvinyl chloride * catheter * repressed migration of plasticizers Subject RIV: BK - Fluid Dynamics

  12. Repressive Policy of the Soviet Government During World War II

    OpenAIRE

    Konstantin N. Maksimov; Irina V. Lidzhieva

    2014-01-01

    The article features wide range of sources dealing with deportation of a number of Nations in the years of the great Patriotic war. The authors note that the repressive policy of the Soviet state, as well as the reason for the deportation of the peoples in the first half of XX century are rooted in the nature of the totalitarian mode.

  13. Addressing the repressed needs of the Arabic client.

    Science.gov (United States)

    Dwairy, M

    1997-01-01

    In comparison to families in Western society, the traditional Arabic family plays a relatively greater role in providing support for adult progeny. This serves to condition adult offspring to continue to comply with the will and values of the family. Therefore, in exchange for familial support, Arabic individuals learn to repress authentic needs and emotions, and within that process they relinquish the need for self-actualization. Arabic society discourages individualism and opposes self-actualization by means of simultaneous punishment and moralization. Thus, there is a relatively greater development of the social value system (or superego) and comparatively less development of the self (or ego). In comparison to Western society, Arabic individuals continue to experience greater oppression during adulthood. Given these cultural differences, the processes of reliving and activating repressed needs and emotions, which ultimately serves to promote self-actualization, will transform intrapsychic conflicts into interpersonal and social ones. Thus, personal actions typically encouraged during Western psychotherapy are likely to produce significant social oppression. Indeed, promoting awareness of repressed needs and emotions often leads the Arabic client to become more helpless, because such wishes will rarely be socially sanctioned or satisfactorily fulfilled. Therefore, when addressing repressed needs and emotions in psychotherapy, ego strength, cultural identity, and degree of strictness of the client's family of origin must be considered. PMID:9231529

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

    Directory of Open Access Journals (Sweden)

    Nicole Kohrs

    2016-03-01

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

  15. Scaffold protein enigma homolog 1 overcomes the repression of myogenesis activation by inhibitor of DNA binding 2.

    Science.gov (United States)

    Nakatani, Miyuki; Ito, Jumpei; Koyama, Riko; Iijima, Masumi; Yoshimoto, Nobuo; Niimi, Tomoaki; Kuroda, Shun'ichi; Maturana, Andrés D

    2016-05-27

    Enigma Homolog 1 (ENH1) is a scaffold protein for signaling proteins and transcription factors. Previously, we reported that ENH1 overexpression promotes the differentiation of C2C12 myoblasts. However, the molecular mechanism underlying the role of ENH1 in the C2C12 cells differentiation remains elusive. ENH1 was shown to inhibit the proliferation of neuroblastoma cells by sequestering Inhibitor of DNA binding protein 2 (Id2) in the cytosol. Id2 is a repressor of basic Helix-Loop-Helix transcription factors activity and prevents myogenesis. Here, we found that ENH1 overcome the Id2 repression of C2C12 cells myogenic differentiation and that ENH1 overexpression promotes mice satellite cells activation, the first step toward myogenic differentiation. In addition, we show that ENH1 interacted with Id2 in C2C12 cells and mice satellite cells. Collectively, our results suggest that ENH1 plays an important role in the activation of myogenesis through the repression of Id2 activity. PMID:27114303

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

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  17. Evidence That the Transcriptional Regulators Sin3 and Rpd3, and a Novel Gene (Sds3) with Similar Functions, Are Involved in Transcriptional Silencing in S. Cerevisiae

    OpenAIRE

    Vannier, D; Balderes, D; Shore, D

    1996-01-01

    In a screen for extragenic suppressors of a silencing defective rap1(s) hmrΔA strain, recessive mutations in 21 different genes were found that restored repression to HMR. We describe the characterization of three of these SDS (suppressors of defective silencing) genes. SDS16 and SDS6 are known transcriptional modifiers, SIN3(RPD1/UME4/SDI1/GAM2) and RPD3(SDI2), respectively, while the third is a novel gene, SDS3. SDS3 shares the meiotic functions of SIN3 and RPD3 in that it represses IME2 in...

  18. Characterization of an antagonistic switch between histone H3 lysine 27 methylation and acetylation in the transcriptional regulation of Polycomb group target genes

    DEFF Research Database (Denmark)

    Pasini, Diego; Malatesta, Martina; Jung, Hye Ryung; Valfridsson, Julian Osmond A; Willer, Anton; Olsson, Linda; Skotte, Julie; Wutz, Anton; Porse, Bo; Jensen, Ole Nørregaard; Helin, Kristian

    2010-01-01

    Polycomb group (PcG) proteins are transcriptional repressors, which regulate proliferation and cell fate decisions during development, and their deregulated expression is a frequent event in human tumours. The Polycomb repressive complex 2 (PRC2) catalyzes trimethylation (me3) of histone H3 lysine...... 27 (K27), and it is believed that this activity mediates transcriptional repression. Despite the recent progress in understanding PcG function, the molecular mechanisms by which the PcG proteins repress transcription, as well as the mechanisms that lead to the activation of PcG target genes are....... The methylation to acetylation switch correlates with the transcriptional activation of PcG target genes, both during ES cell differentiation and in MLL-AF9-transduced hematopoietic stem cells. Moreover, we provide evidence that the acetylation of H3K27 is catalyzed by the acetyltransferases p300 and...

  19. Distance determination by GIY-YIG intron endonucleases: discrimination between repression and cleavage functions.

    Science.gov (United States)

    Liu, Qingqing; Derbyshire, Victoria; Belfort, Marlene; Edgell, David R

    2006-01-01

    GIY-YIG homing endonucleases are modular proteins, with conserved N-terminal catalytic domains connected by linkers to C-terminal DNA-binding domains. I-TevI, the T4 phage GIY-YIG intron endonuclease, functions both in promoting td intron homing, and in acting as a transcriptional autorepressor. Repression is achieved by binding to an operator, which is cleaved at 100-fold reduced efficiency relative to the intronless homing site. The linker includes a zinc finger, which functions in distance determination, to constrain the catalytic domain to cleave the homing site at a fixed position. Here we show that I-BmoI, a related GIY-YIG endonuclease lacking a zinc finger, also possesses some cleavage distance discrimination. Furthermore, hybrid endonucleases constructed by swapping the domains of I-BmoI and I-TevI are active, precise and demonstrate that features other than the zinc finger facilitate distance determination. Most importantly, I-TevI zinc finger mutants cleave the operator more efficiently than the homing site, the converse of wild-type protein. These results are consistent with the zinc finger acting as a measuring device, directing efficient cleavage of the homing site to promote intron mobility, while reducing cleavage at the operator to ensure transcriptional autorepression and phage viability. PMID:16582101

  20. Molecular physiology of the dynamic regulation of carbon catabolite repression in Escherichia coli.

    Science.gov (United States)

    Borirak, Orawan; Bekker, Martijn; Hellingwerf, Klaas J

    2014-06-01

    We report on the use of the chemostat as an optimal device to create time-invariant conditions that allow accurate sampling for various omics assays in Escherichia coli, in combination with recording of the dynamics of the physiological transition in the organism under study that accompany the initiation of glucose repression. E. coli cells respond to the addition of glucose not only with the well-known transcriptional response, as was revealed through quantitative PCR analysis of the transcript levels of key genes from the CRP (cAMP receptor protein) regulon, but also with an increased growth rate and a transient decrease in the efficiency of its aerobic catabolism. Less than half of a doubling time is required for the organism to recover to maximal values of growth rate and efficiency. Furthermore, calculations based on our results show that the specific glucose uptake rate (qs) and the H(+)/e(-) ratio increase proportionally, up to a growth rate of 0.4 h(-1), whilst biomass yield on glucose (Yx / s) drops during the first 15 min, followed by a gradual recovery. Surprisingly, the growth yields after the recovery phase show values even higher than the maximum theoretical yield. Possible explanations for these high yields are discussed. PMID:24603062

  1. MicroRNA-155 promotes atherosclerosis by repressing Bcl6 in macrophages.

    Science.gov (United States)

    Nazari-Jahantigh, Maliheh; Wei, Yuanyuan; Noels, Heidi; Akhtar, Shamima; Zhou, Zhe; Koenen, Rory R; Heyll, Kathrin; Gremse, Felix; Kiessling, Fabian; Grommes, Jochen; Weber, Christian; Schober, Andreas

    2012-11-01

    Macrophages in atherosclerotic plaques drive inflammatory responses, degrade lipoproteins, and phagocytose dead cells. MicroRNAs (miRs) control the differentiation and activity of macrophages by regulating the signaling of key transcription factors. However, the functional role of macrophage-related miRs in the immune response during atherogenesis is unknown. Here, we report that miR-155 is specifically expressed in atherosclerotic plaques and proinflammatory macrophages, where it was induced by treatment with mildly oxidized LDL (moxLDL) and IFN-γ. Leukocyte-specific Mir155 deficiency reduced plaque size and number of lesional macrophages after partial carotid ligation in atherosclerotic (Apoe-/-) mice. In macrophages stimulated with moxLDL/IFN-γ in vitro, and in lesional macrophages, loss of Mir155 reduced the expression of the chemokine CCL2, which promotes the recruitment of monocytes to atherosclerotic plaques. Additionally, we found that miR-155 directly repressed expression of BCL6, a transcription factor that attenuates proinflammatory NF-κB signaling. Silencing of Bcl6 in mice harboring Mir155-/- macrophages enhanced plaque formation and CCL2 expression. Taken together, these data demonstrated that miR-155 plays a key role in atherogenic programming of macrophages to sustain and enhance vascular inflammation. PMID:23041630

  2. Autoregulatory and repressive inputs localize Hydra Wnt3 to the head organizer

    Science.gov (United States)

    Nakamura, Yukio; Tsiairis, Charisios D.; Özbek, Suat; Holstein, Thomas W.

    2011-01-01

    Polarized Wnt signaling along the primary body axis is a conserved property of axial patterning in bilaterians and prebilaterians, and depends on localized sources of Wnt ligands. However, the mechanisms governing the localized Wnt expression that emerged early in evolution are poorly understood. Here we find in the cnidarian Hydra that two functionally distinct cis-regulatory elements control the head organizer-associated Hydra Wnt3 (HyWnt3). An autoregulatory element, which mediates direct inputs of Wnt/β-catenin signaling, highly activates HyWnt3 transcription in the head region. In contrast, a repressor element is necessary and sufficient to restrict the activity of the autoregulatory element, thereby allowing the organizer-specific expression. Our results reveal that a combination of autoregulation and repression is crucial for establishing a Wnt-expressing organizing center in a basal metazoan. We suggest that this transcriptional control is an evolutionarily old strategy in the formation of Wnt signaling centers and metazoan axial patterning. PMID:21576458

  3. p53 Represses the Oncogenic Sno-MiR-28 Derived from a SnoRNA.

    Directory of Open Access Journals (Sweden)

    Feng Yu

    Full Text Available p53 is a master tumour repressor that participates in vast regulatory networks, including feedback loops involving microRNAs (miRNAs that regulate p53 and that themselves are direct p53 transcriptional targets. We show here that a group of polycistronic miRNA-like non-coding RNAs derived from small nucleolar RNAs (sno-miRNAs are transcriptionally repressed by p53 through their host gene, SNHG1. The most abundant of these, sno-miR-28, directly targets the p53-stabilizing gene, TAF9B. Collectively, p53, SNHG1, sno-miR-28 and TAF9B form a regulatory loop which affects p53 stability and downstream p53-regulated pathways. In addition, SNHG1, SNORD28 and sno-miR-28 are all significantly upregulated in breast tumours and the overexpression of sno-miR-28 promotes breast epithelial cell proliferation. This research has broadened our knowledge of the crosstalk between small non-coding RNA pathways and roles of sno-miRNAs in p53 regulation.

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

    DEFF Research Database (Denmark)

    Södersten, Erik; Feyder, Michael; Lerdrup, Mads;

    2014-01-01

    Polycomb group (PcG) proteins bind to and repress genes in embryonic stem cells through lineage commitment to the terminal differentiated state. PcG repressed genes are commonly characterized by the presence of the epigenetic histone mark H3K27me3, catalyzed by the Polycomb repressive complex 2. ...

  5. Unintended Consequences of Repression: Alliance Formation in South Korea's Democracy Movement (1970-1979)

    Science.gov (United States)

    Chang, Paul Y.

    2008-01-01

    Research regarding the impact of repression on social movements has yielded conflicting findings; some argue that repression decreases the total quantity of protest events while others argue that it motivates protest. To move beyond this impasse, various scholars have suggested exploring how repression influences the quality of social movements.…

  6. Cell cycle-dependent regulation of RNA polymerase I transcription: The nucleolar transcription factor UBF is inactive in mitosis and early G1

    OpenAIRE

    Klein, Joachim; Grummt, Ingrid

    1999-01-01

    Transcription of ribosomal RNA genes by RNA polymerase (pol) I oscillates during the cell cycle, being maximal in S and G2 phase, repressed during mitosis, and gradually recovering during G1 progression. We have shown that transcription initiation factor (TIF)-IB/SL1 is inactivated during mitosis by cdc2/cyclin B-directed phosphorylation of TAFI110. In this study, we have monitored reactivation of transcription after exit from mitosis. We demonstrate that the pol I factor UBF is also inactiva...

  7. Nascent transcription affected by RNA polymerase IV in Zea mays.

    Science.gov (United States)

    Erhard, Karl F; Talbot, Joy-El R B; Deans, Natalie C; McClish, Allison E; Hollick, Jay B

    2015-04-01

    All eukaryotes use three DNA-dependent RNA polymerases (RNAPs) to create cellular RNAs from DNA templates. Plants have additional RNAPs related to Pol II, but their evolutionary role(s) remain largely unknown. Zea mays (maize) RNA polymerase D1 (RPD1), the largest subunit of RNA polymerase IV (Pol IV), is required for normal plant development, paramutation, transcriptional repression of certain transposable elements (TEs), and transcriptional regulation of specific alleles. Here, we define the nascent transcriptomes of rpd1 mutant and wild-type (WT) seedlings using global run-on sequencing (GRO-seq) to identify the broader targets of RPD1-based regulation. Comparisons of WT and rpd1 mutant GRO-seq profiles indicate that Pol IV globally affects transcription at both transcriptional start sites and immediately downstream of polyadenylation addition sites. We found no evidence of divergent transcription from gene promoters as seen in mammalian GRO-seq profiles. Statistical comparisons identify genes and TEs whose transcription is affected by RPD1. Most examples of significant increases in genic antisense transcription appear to be initiated by 3'-proximal long terminal repeat retrotransposons. These results indicate that maize Pol IV specifies Pol II-based transcriptional regulation for specific regions of the maize genome including genes having developmental significance. PMID:25653306

  8. The multicopy gene Sly represses the sex chromosomes in the male mouse germline after meiosis.

    Science.gov (United States)

    Cocquet, Julie; Ellis, Peter J I; Yamauchi, Yasuhiro; Mahadevaiah, Shantha K; Affara, Nabeel A; Ward, Monika A; Burgoyne, Paul S

    2009-11-01

    Studies of mice with Y chromosome long arm deficiencies suggest that the male-specific region (MSYq) encodes information required for sperm differentiation and postmeiotic sex chromatin repression (PSCR). Several genes have been identified on MSYq, but because they are present in more than 40 copies each, their functions cannot be investigated using traditional gene targeting. Here, we generate transgenic mice producing small interfering RNAs that specifically target the transcripts of the MSYq-encoded multicopy gene Sly (Sycp3-like Y-linked). Microarray analyses performed on these Sly-deficient males and on MSYq-deficient males show a remarkable up-regulation of sex chromosome genes in spermatids. SLY protein colocalizes with the X and Y chromatin in spermatids of normal males, and Sly deficiency leads to defective repressive marks on the sex chromatin, such as reduced levels of the heterochromatin protein CBX1 and of histone H3 methylated at lysine 9. Sly-deficient mice, just like MSYq-deficient mice, have severe impairment of sperm differentiation and are near sterile. We propose that their spermiogenesis phenotype is a consequence of the change in spermatid gene expression following Sly deficiency. To our knowledge, this is the first successful targeted disruption of the function of a multicopy gene (or of any Y gene). It shows that SLY has a predominant role in PSCR, either via direct interaction with the spermatid sex chromatin or via interaction with sex chromatin protein partners. Sly deficiency is the major underlying cause of the spectrum of anomalies identified 17 y ago in MSYq-deficient males. Our results also suggest that the expansion of sex-linked spermatid-expressed genes in mouse is a consequence of the enhancement of PSCR that accompanies Sly amplification. PMID:19918361

  9. EWS represses cofilin 1 expression by inducing nuclear retention of cofilin 1 mRNA.

    Science.gov (United States)

    Huang, L; Kuwahara, I; Matsumoto, K

    2014-06-01

    In Ewing's sarcoma family tumors (ESFTs), the proto-oncogene EWS that encodes an RNA-binding protein is fused by chromosomal translocation to the gene encoding one of the E-twenty six (ETS) family of transcription factors, most commonly friend leukemia virus integration 1 (FLI-1). Although EWS/FLI-1 chimeric proteins are necessary for carcinogenesis, additional events seem to be required for transformation to occur. We have previously reported that a protein product of an EWS mRNA target, whose expression is negatively regulated by EWS but not by EWS/FLI-1, contributes to ESFT development. However, the mechanism by which EWS represses protein expression remains to be elucidated. Here, we report that overexpression of full-length EWS repressed protein expression and induced nuclear retention of reporter mRNAs in a tethering assay. In contrast, when a mutant lacking the EWS C-terminal nuclear localization signal (classified as a PY-NLS) was expressed, reporter protein expression was upregulated, and the number of cells exporting reporter mRNA to the cytoplasm increased. EWS binds to the 3'-untranslated region in another mRNA target, cofilin 1 (CFL1), and negatively regulates the expression of CFL1. Overexpression of EWS induced nuclear retention of CFL1 mRNA. Furthermore, ESFT cell proliferation and metastatic potential were suppressed by small interfering RNA-mediated CFL1 knockdown. Together, our findings suggest that EWS induces nuclear retention of CFL1 mRNA, thereby suppressing expression of CFL1, and that CFL1 promotes development of ESFT. Targeting CFL1 might therefore provide another novel approach for treatment of this aggressive disease. PMID:23831569

  10. The rnc Gene Promotes Exopolysaccharide Synthesis and Represses the vicRKX Gene Expressions via MicroRNA-Size Small RNAs in Streptococcus mutans

    Science.gov (United States)

    Mao, Meng-Ying; Yang, Ying-Ming; Li, Ke-Zeng; Lei, Lei; Li, Meng; Yang, Yan; Tao, Xiang; Yin, Jia-Xin; Zhang, Ru; Ma, Xin-Rong; Hu, Tao

    2016-01-01

    Dental caries is a biofilm-dependent disease that largely relies on the ability of Streptococcus mutans to synthesize exopolysaccharides. Although the rnc gene is suggested to be involved in virulence mechanisms in many other bacteria, the information regarding it in S. mutans is very limited. Here, using deletion or overexpression mutant assay, we demonstrated that rnc in S. mutans significantly positively regulated exopolysaccharide synthesis and further altered biofilm formation. Meanwhile, the cariogenecity of S. mutans was decreased by deletion of rnc in a specific pathogen-free (SPF) rat model. Interestingly, analyzing the expression at mRNA level, we found the downstream vic locus was repressed by rnc in S. mutans. Using deep sequencing and bioinformatics analysis, for the first time, three putative microRNA-size small RNAs (msRNAs) targeting vicRKX were predicted in S. mutans. The expression levels of these msRNAs were negatively correlated with vicRKX but positively correlated with rnc, indicating rnc probably repressed vicRKX expression through msRNAs at the post-transcriptional level. In all, the results present that rnc has a potential role in the regulation of exopolysaccharide synthesis and can affect vicRKX expressions via post-transcriptional repression in S. mutans. This study provides an alternative avenue for further research aimed at preventing caries. PMID:27242713

  11. Elucidating MicroRNA Regulatory Networks Using Transcriptional, Post-transcriptional, and Histone Modification Measurements

    Directory of Open Access Journals (Sweden)

    Sara J.C. Gosline

    2016-01-01

    Full Text Available MicroRNAs (miRNAs regulate diverse biological processes by repressing mRNAs, but their modest effects on direct targets, together with their participation in larger regulatory networks, make it challenging to delineate miRNA-mediated effects. Here, we describe an approach to characterizing miRNA-regulatory networks by systematically profiling transcriptional, post-transcriptional and epigenetic activity in a pair of isogenic murine fibroblast cell lines with and without Dicer expression. By RNA sequencing (RNA-seq and CLIP (crosslinking followed by immunoprecipitation sequencing (CLIP-seq, we found that most of the changes induced by global miRNA loss occur at the level of transcription. We then introduced a network modeling approach that integrated these data with epigenetic data to identify specific miRNA-regulated transcription factors that explain the impact of miRNA perturbation on gene expression. In total, we demonstrate that combining multiple genome-wide datasets spanning diverse regulatory modes enables accurate delineation of the downstream miRNA-regulated transcriptional network and establishes a model for studying similar networks in other systems.

  12. RNA-guided transcriptional regulation in planta via synthetic dCas9-based transcription factors

    KAUST Repository

    Piatek, Agnieszka

    2014-11-14

    Targeted genomic regulation is a powerful approach to accelerate trait discovery and development in agricultural biotechnology. Bacteria and archaea use clustered regularly interspaced short palindromic repeats (CRISPRs) and CRISPR-associated (Cas) regulatory systems for adaptive molecular immunity against foreign nucleic acids introduced by invading phages and conjugative plasmids. The type II CRISPR/Cas system has been adapted for genome editing in many cell types and organisms. A recent study used the catalytically inactive Cas9 (dCas9) protein combined with guide-RNAs (gRNAs) as a DNA-targeting platform to modulate gene expression in bacterial, yeast, and human cells. Here, we modified this DNA-targeting platform for targeted transcriptional regulation in planta by developing chimeric dCas9-based transcriptional activators and repressors. To generate transcriptional activators, we fused the dCas9 C-terminus with the activation domains of EDLL and TAL effectors. To generate a transcriptional repressor, we fused the dCas9 C-terminus with the SRDX repression domain. Our data demonstrate that dCas9 fusion with the EDLL activation domain (dCas9:EDLL) and the TAL activation domain (dCas9:TAD), guided by gRNAs complementary to selected promoter elements, induce strong transcriptional activation on Bs3

  13. Nuc-ErbB3 regulates H3K27me3 levels and HMT activity to establish epigenetic repression during peripheral myelination.

    Science.gov (United States)

    Ness, Jennifer K; Skiles, Amanda A; Yap, Eng-Hui; Fajardo, Eduardo J; Fiser, Andras; Tapinos, Nikos

    2016-06-01

    Nuc-ErbB3 an alternative transcript from the ErbB3 locus binds to a specific DNA motif and associates with Schwann cell chromatin. Here we generated a nuc-ErbB3 knockin mouse that lacks nuc-ErbB3 expression in the nucleus without affecting the neuregulin-ErbB3 receptor signaling. Nuc-ErbB3 knockin mice exhibit hypermyelination and aberrant myelination at the paranodal region. This phenotype is attributed to de-repression of myelination associated gene transcription following loss of nuc-ErbB3 and histone H3K27me3 promoter occupancy. Nuc-ErbB3 knockin mice exhibit reduced association of H3K27me3 with myelination-associated gene promoters and increased RNA Pol-II rate of transcription of these genes. In addition, nuc-ErbB3 directly regulates levels of H3K27me3 in Schwann cells. Nuc-ErbB3 knockin mice exhibit significant decrease of histone H3K27me3 methyltransferase (HMT) activity and reduced levels of H3K27me3. Collectively, nuc-ErbB3 is a master transcriptional repressor, which regulates HMT activity to establish a repressive chromatin landscape on promoters of genes during peripheral myelination. GLIA 2016;64:977-992. PMID:27017927

  14. Identification of a negative response element in the human inducible nitric-oxide synthase (hiNOS) promoter: The role of NF-κB-repressing factor (NRF) in basal repression of the hiNOS gene

    Science.gov (United States)

    Feng, Xuesheng; Guo, Zhong; Nourbakhsh, Mahtab; Hauser, Hansjorg; Ganster, Ray; Shao, Lifang; Geller, David A.

    2002-01-01

    Although nuclear factor (NF)-κB plays a central role in mediating cytokine-stimulated human inducible nitric-oxide synthase (hiNOS) gene transcription, very little is known about the factors involved in silencing of the hiNOS promoter. NF-κB-repressing factor (NRF) interacts with a specific negative regulatory element (NRE) to mediate transcriptional repression of certain NF-κB responsive genes. By sequence comparison with the IFN-β and IL-8 promoters, we identified an NRE in the hiNOS promoter located at −6.7 kb upstream. In A549 and HeLa human cells, constitutive NRF mRNA expression is detected by RT-PCR. Gel shift assay showed constitutive NRF binding to the hiNOS NRE. Mutation of the −6.7-kb NRE site in the hiNOS promoter resulted in loss of NRF binding and increased basal but not cytokine-stimulated hiNOS transcription in promoter transfection experiments. Interestingly, overexpression of NRF suppressed both basal and cytokine-induced hiNOS promoter activity that depended on an intact cis-acting NRE motif. By using stably transformed HeLa cells with the tetracycline on/off expression system, reduction of cellular NRF by expressing antisense NRF increased basal iNOS promoter activity and resulted in constitutive iNOS mRNA expression. These data demonstrate that the transacting NRF protein is involved in constitutive silencing of the hiNOS gene by binding to a cis-acting NRE upstream in the hiNOS promoter. PMID:12381793

  15. Minor groove binder distamycin remodels chromatin but inhibits transcription.

    Directory of Open Access Journals (Sweden)

    Parijat Majumder

    Full Text Available The condensed structure of chromatin limits access of cellular machinery towards template DNA. This in turn represses essential processes like transcription, replication, repair and recombination. The repression is alleviated by a variety of energy dependent processes, collectively known as "chromatin remodeling". In a eukaryotic cell, a fine balance between condensed and de-condensed states of chromatin helps to maintain an optimum level of gene expression. DNA binding small molecules have the potential to perturb such equilibrium. We present herein the study of an oligopeptide antibiotic distamycin, which binds to the minor groove of B-DNA. Chromatin mobility assays and circular dichroism spectroscopy have been employed to study the effect of distamycin on chromatosomes, isolated from the liver of Sprague-Dawley rats. Our results show that distamycin is capable of remodeling both chromatosomes and reconstituted nucleosomes, and the remodeling takes place in an ATP-independent manner. Binding of distamycin to the linker and nucleosomal DNA culminates in eviction of the linker histone and the formation of a population of off-centered nucleosomes. This hints at a possible corkscrew type motion of the DNA with respect to the histone octamer. Our results indicate that distamycin in spite of remodeling chromatin, inhibits transcription from both DNA and chromatin templates. Therefore, the DNA that is made accessible due to remodeling is either structurally incompetent for transcription, or bound distamycin poses a roadblock for the transcription machinery to advance.

  16. Phosphorylation Regulates Functions of ZEB1 Transcription Factor.

    Science.gov (United States)

    Llorens, M Candelaria; Lorenzatti, Guadalupe; Cavallo, Natalia L; Vaglienti, Maria V; Perrone, Ana P; Carenbauer, Anne L; Darling, Douglas S; Cabanillas, Ana M

    2016-10-01

    ZEB1 transcription factor is important in both development and disease, including many TGFβ-induced responses, and the epithelial-to-mesenchymal transition (EMT) by which many tumors undergo metastasis. ZEB1 is differentially phosphorylated in different cell types; however the role of phosphorylation in ZEB1 activity is unknown. Luciferase reporter studies and electrophoresis mobility shift assays (EMSA) show that a decrease in phosphorylation of ZEB1 increases both DNA-binding and transcriptional repression of ZEB1 target genes. Functional analysis of ZEB1 phosphorylation site mutants near the second zinc finger domain (termed ZD2) show that increased phosphorylation (due to either PMA plus ionomycin, or IGF-1) can inhibit transcriptional repression by either a ZEB1-ZD2 domain clone, or full-length ZEB1. This approach identifies phosphosites that have a substantial effect regulating the transcriptional and DNA-binding activity of ZEB1. Immunoprecipitation with anti-ZEB1 antibodies followed by western analysis with a phospho-Threonine-Proline-specific antibody indicates that the ERK consensus site at Thr-867 is phosphorylated in ZEB1. In addition to disrupting in vitro DNA-binding measured by EMSA, IGF-1-induced MEK/ERK phosphorylation is sufficient to disrupt nuclear localization of GFP-ZEB1 fusion clones. These data suggest that phosphorylation of ZEB1 integrates TGFβ signaling with other signaling pathways such as IGF-1. J. Cell. Physiol. 231: 2205-2217, 2016. © 2016 Wiley Periodicals, Inc. PMID:26868487

  17. Stochastic model for gene transcription on Drosophila melanogaster embryos

    Science.gov (United States)

    Prata, Guilherme N.; Hornos, José Eduardo M.; Ramos, Alexandre F.

    2016-02-01

    We examine immunostaining experimental data for the formation of stripe 2 of even-skipped (eve) transcripts on D. melanogaster embryos. An estimate of the factor converting immunofluorescence intensity units into molecular numbers is given. The analysis of the eve dynamics at the region of stripe 2 suggests that the promoter site of the gene has two distinct regimes: an earlier phase when it is predominantly activated until a critical time when it becomes mainly repressed. That suggests proposing a stochastic binary model for gene transcription on D. melanogaster embryos. Our model has two random variables: the transcripts number and the state of the source of mRNAs given as active or repressed. We are able to reproduce available experimental data for the average number of transcripts. An analysis of the random fluctuations on the number of eves and their consequences on the spatial precision of stripe 2 is presented. We show that the position of the anterior or posterior borders fluctuate around their average position by ˜1 % of the embryo length, which is similar to what is found experimentally. The fitting of data by such a simple model suggests that it can be useful to understand the functions of randomness during developmental processes.

  18. High-fat medium and circadian transcription factors (cryptochrome and clock) contribute to the regulation of cholesterogenic Cyp51 and Hmgcr genes in mouse embryonic fibroblasts

    OpenAIRE

    Rozman, Damjana; Španinger, Klemen; Fink, Martina; Prosenc, Uršula

    2015-01-01

    The aim of our research was to investigate how cholesterol, unsaturated fatty acids and circadian genes affect the expression of cholesterogenic genes, Cyp51 and Hmgcr, in somatic and in embryonic fibroblast cell lines. We found that in immortal Hepa1-6 cells cholesterol represses the transcription of Hmgcr and Cyp51 for 80%, while unsaturated fatty acids have different effects: Hmgcr was repressed for 50%, but Cyp51 was unaffected by the presence of linoloeic acid. In embryonic fibroblasts t...

  19. Negative transcriptional regulation of mitochondrial transcription factor A (TFAM) by nuclear TFAM

    International Nuclear Information System (INIS)

    Highlights: • TFAM localizes in nuclei and mitochondria of neuronal cells. • Nuclear TFAM does not bind the Tfam promoter. • Nuclear TFAM reduced the Tfam promoter activity via suppressing NRF-1 activity. • A novel self-negative feedback regulation of Tfam gene expression is explored. • FAM may play different roles depending on its subcellular localizations. - Abstract: The nuclear DNA-encoded mitochondrial transcription factor A (TFAM) is synthesized in cytoplasm and transported into mitochondria. TFAM enhances both transcription and replication of mitochondrial DNA. It is unclear, however, whether TFAM plays a role in regulating nuclear gene expression. Here, we demonstrated that TFAM was localized to the nucleus and mitochondria by immunostaining, subcellular fractionation, and TFAM-green fluorescent protein hybrid protein studies. In HT22 hippocampal neuronal cells, human TFAM (hTFAM) overexpression suppressed human Tfam promoter-mediated luciferase activity in a dose-dependent manner. The mitochondria targeting sequence-deficient hTFAM also repressed Tfam promoter activity to the same degree as hTFAM. It indicated that nuclear hTFAM suppressed Tfam expression without modulating mitochondrial activity. The repression required for nuclear respiratory factor-1 (NRF-1), but hTFAM did not bind to the NRF-1 binding site of its promoter. TFAM was co-immunoprecipitated with NRF-1. Taken together, we suggest that nuclear TFAM down-regulate its own gene expression as a NRF-1 repressor, showing that TFAM may play different roles depending on its subcellular localizations

  20. Negative transcriptional regulation of mitochondrial transcription factor A (TFAM) by nuclear TFAM

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eun Jin; Kang, Young Cheol; Park, Wook-Ha; Jeong, Jae Hoon; Pak, Youngmi Kim, E-mail: ykpak@khu.ac.kr

    2014-07-18

    Highlights: • TFAM localizes in nuclei and mitochondria of neuronal cells. • Nuclear TFAM does not bind the Tfam promoter. • Nuclear TFAM reduced the Tfam promoter activity via suppressing NRF-1 activity. • A novel self-negative feedback regulation of Tfam gene expression is explored. • FAM may play different roles depending on its subcellular localizations. - Abstract: The nuclear DNA-encoded mitochondrial transcription factor A (TFAM) is synthesized in cytoplasm and transported into mitochondria. TFAM enhances both transcription and replication of mitochondrial DNA. It is unclear, however, whether TFAM plays a role in regulating nuclear gene expression. Here, we demonstrated that TFAM was localized to the nucleus and mitochondria by immunostaining, subcellular fractionation, and TFAM-green fluorescent protein hybrid protein studies. In HT22 hippocampal neuronal cells, human TFAM (hTFAM) overexpression suppressed human Tfam promoter-mediated luciferase activity in a dose-dependent manner. The mitochondria targeting sequence-deficient hTFAM also repressed Tfam promoter activity to the same degree as hTFAM. It indicated that nuclear hTFAM suppressed Tfam expression without modulating mitochondrial activity. The repression required for nuclear respiratory factor-1 (NRF-1), but hTFAM did not bind to the NRF-1 binding site of its promoter. TFAM was co-immunoprecipitated with NRF-1. Taken together, we suggest that nuclear TFAM down-regulate its own gene expression as a NRF-1 repressor, showing that TFAM may play different roles depending on its subcellular localizations.

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

    Institute of Scientific and Technical Information of China (English)

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

    2011-01-01

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

  2. Repression predicts outcome following multidisciplinary treatment of chronic pain.

    Science.gov (United States)

    Burns, J W

    2000-01-01

    This study examined whether repression predicts outcome following multidisciplinary treatment for chronic pain and whether links between anxiety and outcome are obscured by repressors. Ninety-three chronic pain patients completed a 4-week pain program. Lifting capacity, walking endurance, depression, pain severity, and activity were measured at pre- and posttreatment. Low-anxious, repressor, high-anxious, and defensive/high-anxious groups were formed from median splits of Anxiety Content (ACS) and Lie scales of the Minnesota Multiphasic Personality Inventory-2 (MMPI-2; Butcher, Dahlstrom, Graham, Tellegen, & Kaemmer, 1989). Significant ACS x Lie interactions were found for lifting capacity, depression, and pain severity changes. Planned comparisons showed that both repressors and high-anxious patients performed poorly on lifting capacity; repressors alone recovered poorly on depression and pain severity. Results imply that repression may interfere with the process and outcome of pain programs. PMID:10711590

  3. Gene activation by UV light, fungal elicitor or fungal infection in Petroselinum crispum is correlated with repression of cell cycle-related genes

    International Nuclear Information System (INIS)

    The effects of UV light or fungal elicitors on plant cells have so far been studied mostly with respect to defense-related gene activation. Here, an inverse correlation of these stimulatory effects with the activities of several cell cycle-related genes is demonstrated. Concomitant with the induction of flavonoid biosynthetic enzymes in UV-irradiated cell suspension cultures of parsley (Petroselinum crispum), total histone synthesis declined to about half the initial rate. A subclass of the histone H3 gene family was selected to demonstrate the close correlation of its expression with cell division, both in intact plants and cultured cells. Using RNA-blot and run-on transcription assays, it was shown that one arbitrarily selected subclass of each of the histone H2A, H2B, H3 and H4 gene families and of the genes encoding a p34cdc2 protein kinase and a mitotic cyclin were transcriptionally repressed in UV-irradiated as well as fungal elicitor-treated parsley cells. The timing and extent of repression differed between the two stimuli; the response to light was more transient and smaller in magnitude. These differential responses to light and elicitor were inversely correlated with the induction of phenylalanine ammonia-lyase, a key enzyme of phenylpropanoid metabolism. Essentially the same result was obtained with a defined oligopeptide elicitor, indicating that the same signaling pathway is responsible for defense-related gene activation and cell cycle-related gene repression. A temporary (UV light) or long-lasting (fungal elicitor) cessation of cell culture growth is most likely due to an arrest of cell division which may be a prerequisite for full commitment of the cells to transcriptional activation of full commitment of the cells to transcriptional activation of pathways involved in UV protection or pathogen defense. This conclusion is corroborated by the observation that the histone H3 mRNA level greatly declined around fungal infection sites in young parsley

  4. Financial Liberalization and Financial Repression in Formerly Socialist Economies

    OpenAIRE

    Cevdet Denizer; Ray M. Desai; Nikolay Gueorguiev

    2000-01-01

    The financial systems of developing countries tend to be restricted or repressed by burdensome reserve requirements, interest-rate ceilings, foreign-exchange regulations, constraints on banks? balance sheets, and the heavy financial-sector taxation. This article explores preliminary evidence from the post-communist economies of Eastern Europe and the former Soviet Union. Using data from 25 countries between 1991 and 1996, we find that the standard public-finance framework has limited applicab...

  5. ANXIETY, REPRESSION AND FORECLOSURE: SOME REMARKS TO THE CLINIC

    Directory of Open Access Journals (Sweden)

    Sonia Leite

    2009-07-01

    Full Text Available The paper focus on Freud’s studies on anxiety and highlights Lacan’s contributions to the subject. It emphasizes the clinical importance of freudian distinction between anxiety as a signal and realistic – or automatic – anxiety in order to answer the question: assuming that, concerning neurosis, what causes repression is a signal of anxiety, could it also be said that, in psychosis, it is realistic anxiety that produces foreclosure?

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    neurons and in endocrine cells, which is necessary for their normal function. During development, REST represses a subset of genes in the neuronal differentiation program and Rest is down-regulated as neurons differentiate. Here, we investigate the role of REST in the differentiation of pancreatic...... REST is active in pancreas progenitors where it gates the activation of part of the beta cell differentiation program....

  7. Political repression and child labor : theory and empirical evidence

    OpenAIRE

    Maffei, Sandro; Raabe, Nikolai; Heinrich W. Ursprung

    2004-01-01

    Most normative studies on child labor arrive at the conclusion that child labor is detrimental to social welfare. Child labor is, however, still prevalent in many developing countries even though in many of these countries it is forbidden by law. In this paper we develop a political-economic model that explains lenient enforcement of existing child labor legislation. The most important implication of our model is that in countries with repressive political regimes enforcement is more lenient ...

  8. Transcriptional regulation of the presenilin-1 gene controls gamma-secretase activity.

    Science.gov (United States)

    Lee, Sebum; Das, Hriday K

    2010-01-01

    Inhibition of basal JNK activity by JNK inhibitor SP600125 or JNK1siRNA repressed presenilin-1 (PS1) expression in SK-N-SH cells by augmenting the level of p53, a repressor of the PS1 gene (1). We now showed that repression of PS1 transcription by JNK inhibitor SP600125 inhibited gamma-secretase mediated processing of amyloid precursor protein (APP) resulting in the accumulation of C99 fragment and the reduction of secreted Abeta40 level without altering the expression of nicastrin (NCT). Co-treatment of cells with SP600125 and p53 inhibitor, pifithrin-alpha, partially nullified the suppressive effects of SP610025 on PS1 expression and secreted Abeta40 level. Suppression of JNK1 by JNK1siRNA also decreased Abeta40 level. Furthermore, overexpression of the repressors p53, ZNF237 and CHD3 of the PS1 gene also suppressed the processing of APP through repression of PS1 transcription by deacetylation of histone at the PS1 promoter. Transcriptional activator Ets2 increased PS1 protein and secreted Abeta40 levels without affecting the expression of NCT by activating PS1 transcription via hyper-acetylation of histone at the PS1 promoter. Therefore, regulation of PS1 transcription modulates gamma-secretase activity. PMID:20036849

  9. Maf1, a new player in the regulation of human RNA polymerase III transcription.

    Directory of Open Access Journals (Sweden)

    Jaime H Reina

    Full Text Available BACKGROUND: Human RNA polymerase III (pol III transcription is regulated by several factors, including the tumor suppressors P53 and Rb, and the proto-oncogene c-Myc. In yeast, which lacks these proteins, a central regulator of pol III transcription, called Maf1, has been described. Maf1 is required for repression of pol III transcription in response to several signal transduction pathways and is broadly conserved in eukaryotes. METHODOLOGY/PRINCIPAL FINDINGS: We show that human endogenous Maf1 can be co-immunoprecipitated with pol III and associates in vitro with two pol III subunits, the largest subunit RPC1 and the alpha-like subunit RPAC2. Maf1 represses pol III transcription in vitro and in vivo and is required for maximal pol III repression after exposure to MMS or rapamycin, treatments that both lead to Maf1 dephosphorylation. CONCLUSIONS/SIGNIFICANCE: These data suggest that Maf1 is a major regulator of pol III transcription in human cells.

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

    DEFF Research Database (Denmark)

    Liew, Chu Wai; Rand, Kasper Dyrberg; Simpson, Raina J Y; Yung, Wendy W; Mansfield, Robyn E; Crossley, Merlin; Proetorius-Ibba, Mette; Nerlov, Claus; Poulsen, Flemming M; Mackay, Joel P

    2006-01-01

    GATA-1 and PU.1 are transcription factors that control erythroid and myeloid development, respectively. The two proteins have been shown to function in an antagonistic fashion, with GATA-1 repressing PU.1 activity during erythropoiesis and PU.1 repressing GATA-1 function during myelopoiesis. It has...... also become clear that this functional antagonism involves direct interactions between the two proteins. However, the molecular basis for these interactions is not known, and a number of inconsistencies exist in the literature. We have used a range of biophysical methods to define the molecular details...

  11. NCoR1 Mediates Papillomavirus E8^E2C Transcriptional Repression▿ †

    OpenAIRE

    Powell, Maria L.C.; Smith, Jennifer A.; Sowa, Mathew E.; Harper, J. Wade; Iftner, Thomas; Stubenrauch, Frank; Howley, Peter M.

    2010-01-01

    The papillomavirus E2 open reading frame encodes the full-length E2 protein as well as an alternatively spliced product called E8^E2C. E8^E2C has been best studied for the high-risk human papillomaviruses, where it has been shown to regulate viral genome levels and, like the full-length E2 protein, to repress transcription from the viral promoter that directs the expression of the viral E6 and E7 oncogenes. The repression function of E8^E2C is dependent on the 12-amino-acid N-terminal sequenc...

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

    Science.gov (United States)

    Hook, Derek; Vanheule, Stijn

    2015-01-01

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

  13. Revisiting the master-signifier, or, Mandela and repression

    Directory of Open Access Journals (Sweden)

    Derek eHook

    2016-01-01

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

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

    Science.gov (United States)

    Hook, Derek; Vanheule, Stijn

    2016-01-01

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

  15. Regulation of transcription of the human presenilin-1 gene by ets transcription factors and the p53 protooncogene.

    Science.gov (United States)

    Pastorcic, M; Das, H K

    2000-11-10

    The expression of the human presenilin-1 cellular gene is suppressed by the p53 protooncogene. The rapid kinetic of the down-regulation has suggested that it may result from a primary mechanism. We show here that p53 also suppresses the transcription of a presenilin-1 promoter-chloramphenicol acetyltransferase reporter synthetic gene in transient infection assays in neuroblastoma (SK-N-SH) and hepatoma (HepG2) cell lines. Only a minimum promoter including sequences from -35 to + 6 from the transcription initiation is sufficient to confer down-regulation. We have previously defined a crucial DNA element controlling 90% of the expression of the gene within the same short area, and the identification of the transcription factors involved should also provide insights into the regulation of PS1 by p53. This region contains an Ets transcription factor binding motif, and a 2-base pair alteration within the core sequence (GGAA to TTAA) of the Ets consensus also reduced transcription by more than 90%. We now show that Ets1 and Ets2 indeed transactivate a PS1 promoter-chloramphenicol acetyltransferase reporter including the (-35 to +6) fragment. Furthermore, in vitro translated Ets2 binds specifically to the -10 Ets motif in electrophoretic mobility shift assays. Therefore, Ets1/2 factors bind specifically to the -10 Ets element and activate PS1 transcription. We also show that the coactivator p300 enhances the activation by Ets1 and Ets2 as well as the repression by p53. p300 is known to interact with p53 as well as with Ets1 and Ets2. We show that p53 does not bind directly to the PS1 promoter. Hence the repression of PS1 transcription by p53 is likely to be mediated through protein-protein interactions. PMID:10942770

  16. GW4064, an agonist of farnesoid X receptor, represses CYP3A4 expression in human hepatocytes by inducing small heterodimer partner expression.

    Science.gov (United States)

    Zhang, Shu; Pan, Xian; Jeong, Hyunyoung

    2015-05-01

    Farnesoid X receptor (FXR) functions as a regulator of bile acid and lipid homeostasis and is recognized as a promising therapeutic target for metabolic diseases. The biologic function of FXR is mediated in part by a small heterodimer partner (SHP); ligand-activated FXR enhances SHP expression, and SHP in turn represses the activity of multiple transcription factors. This study aimed to investigate the effect of FXR activation on expression of the major drug-metabolizing enzyme CYP3A4. The effects of 3-(2,6-dichlorophenyl)-4-(3'-carboxy-2-chlorostilben-4-yl)oxymethyl-5-isopropylisoxazole (GW4064), a synthetic agonist of FXR, on the expression and activity of CYP3A4 were examined in primary human hepatocytes by using quantitative real-time polymerase chain reaction and S9 phenotyping. In human hepatocytes, treatment of GW4064 (1 μM) for 48 hours resulted in a 75% decrease in CYP3A4 mRNA expression and a 25% decrease in CYP3A4 activity, accompanied by ∼3-fold increase in SHP mRNA expression. In HepG2 cells, SHP repressed transactivation of CYP3A4 promoter by pregnane X receptor (PXR), constitutive androstane receptor (CAR), and glucocorticoid receptor. Interestingly, GW4064 did not repress expression of CYP2B6, another target gene of PXR and CAR; GW4064 enhanced CYP2B6 promoter activity. In conclusion, GW4064 represses CYP3A4 expression in human hepatocytes, potentially through upregulation of SHP expression and subsequent repression of CYP3A4 promoter activity. Clinically significant drug-drug interaction involving FXR agonists and CYP3A4 substrates may occur. PMID:25725071

  17. MDM4/HIPK2/p53 cytoplasmic assembly uncovers coordinated repression of molecules with anti-apoptotic activity during early DNA damage response.

    Science.gov (United States)

    Mancini, F; Pieroni, L; Monteleone, V; Lucà, R; Fici, L; Luca, E; Urbani, A; Xiong, S; Soddu, S; Masetti, R; Lozano, G; Pontecorvi, A; Moretti, F

    2016-01-14

    The p53 inhibitor, MDM4 (MDMX) is a cytoplasmic protein with p53-activating function under DNA damage conditions. Particularly, MDM4 promotes phosphorylation of p53 at Ser46, a modification that precedes different p53 activities. We investigated the mechanism by which MDM4 promotes this p53 modification and its consequences in untransformed mammary epithelial cells and tissues. In response to severe DNA damage, MDM4 stimulates p53Ser46(P) by binding and stabilizing serine-threonine kinase HIPK2. Under these conditions, the p53-inhibitory complex, MDM4/MDM2, dissociates and this allows MDM4 to promote p53/HIPK2 functional interaction. Comparative proteomic analysis of DNA damage-treated cells versus -untreated cells evidenced a diffuse downregulation of proteins with anti-apoptotic activity, some of which were targets of p53Ser46(P)/HIPK2 repressive activity. Importantly, MDM4 depletion abolishes the downregulation of these proteins indicating the requirement of MDM4 to promote p53-mediated transcriptional repression. Consistently, MDM4-mediated HIPK2/p53 activation precedes HIPK2/p53 nuclear translocation and activity. Noteworthy, repression of these proteins was evident also in mammary glands of mice subjected to γ-irradiation and was significantly enhanced in transgenic mice overexpressing MDM4. This study evidences the flexibility of MDM2/MDM4 heterodimer, which allows the development of a positive activity of cytoplasmic MDM4 towards p53-mediated transcriptional function. Noteworthy, this activity uncovers coordinated repression of molecules with shared anti-apoptotic function which precedes active cell apoptosis and that are frequently overexpressed and/or markers of tumour phenotype in human cancer. PMID:25961923

  18. Dimethylated H3K27 Is a Repressive Epigenetic Histone Mark in the Protist Entamoeba histolytica and Is Significantly Enriched in Genes Silenced via the RNAi Pathway.

    Science.gov (United States)

    Foda, Bardees M; Singh, Upinder

    2015-08-21

    RNA interference (RNAi) is a fundamental biological process that plays a crucial role in regulation of gene expression in many organisms. Transcriptional gene silencing (TGS) is one of the important nuclear roles of RNAi. Our previous data show that Entamoeba histolytica has a robust RNAi pathway that links to TGS via Argonaute 2-2 (Ago2-2) associated 27-nucleotide small RNAs with 5'-polyphosphate termini. Here, we report the first repressive histone mark to be identified in E. histolytica, dimethylation of H3K27 (H3K27Me2), and demonstrate that it is enriched at genes that are silenced by RNAi-mediated TGS. An RNAi-silencing trigger can induce H3K27Me2 deposits at both episomal and chromosomal loci, mediating gene silencing. Our data support two phases of RNAi-mediated TGS: an active silencing phase where the RNAi trigger is present and both H3K27Me2 and Ago2-2 concurrently enrich at chromosomal loci; and an established silencing phase in which the RNAi trigger is removed, but gene silencing with H3K27Me2 enrichment persist independently of Ago2-2 deposition. Importantly, some genes display resistance to chromosomal silencing despite induction of functional small RNAs. In those situations, the RNAi-triggering plasmid that is maintained episomally gets partially silenced and has H3K27Me2 enrichment, but the chromosomal copy displays no repressive histone enrichment. Our data are consistent with a model in which H3K27Me2 is a repressive histone modification, which is strongly associated with transcriptional repression. This is the first example of an epigenetic histone modification that functions to mediate RNAi-mediated TGS in the deep-branching eukaryote E. histolytica. PMID:26149683

  19. Specific contacts of the -35 region of the galP1 promoter by RNA polymerase inhibit GalR-mediated DNA looping repression.

    Science.gov (United States)

    Csiszovszki, Zsolt; Lewis, Dale E A; Le, Phuoc; Sneppen, Kim; Semsey, Szabolcs

    2012-11-01

    The P1 promoter of the galactose operon in Escherichia coli is one of the best studied examples of 'extended -10' promoters. Recognition of the P1 promoter does not require specific contacts between RNA polymerase and its poor -35 element. To investigate whether specific recognition of the -35 element would affect the regulation of P1 by GalR, we mutagenized the -35 element of P1, isolated variants of the -35 element and studied the regulation of the mutant promoters by in vitro transcription assays and by mathematical modeling. The results show that the GalR-mediated DNA loop is less efficient in repressing P1 transcription when RNA polymerase binds to the -10 and -35 elements concomitantly. Our results suggest that promoters that lack specific -35 element recognition allow decoupling of local chromosome structure from transcription initiation. PMID:22941635

  20. Specific contacts of the −35 region of the galP1 promoter by RNA polymerase inhibit GalR-mediated DNA looping repression

    Science.gov (United States)

    Csiszovszki, Zsolt; Lewis, Dale E. A.; Le, Phuoc; Sneppen, Kim; Semsey, Szabolcs

    2012-01-01

    The P1 promoter of the galactose operon in Escherichia coli is one of the best studied examples of ‘extended −10’ promoters. Recognition of the P1 promoter does not require specific contacts between RNA polymerase and its poor −35 element. To investigate whether specific recognition of the −35 element would affect the regulation of P1 by GalR, we mutagenized the −35 element of P1, isolated variants of the −35 element and studied the regulation of the mutant promoters by in vitro transcription assays and by mathematical modeling. The results show that the GalR-mediated DNA loop is less efficient in repressing P1 transcription when RNA polymerase binds to the −10 and −35 elements concomitantly. Our results suggest that promoters that lack specific −35 element recognition allow decoupling of local chromosome structure from transcription initiation. PMID:22941635

  1. A Hox Transcription Factor Collective Binds a Highly Conserved Distal-less cis-Regulatory Module to Generate Robust Transcriptional Outcomes.

    Science.gov (United States)

    Uhl, Juli D; Zandvakili, Arya; Gebelein, Brian

    2016-04-01

    cis-regulatory modules (CRMs) generate precise expression patterns by integrating numerous transcription factors (TFs). Surprisingly, CRMs that control essential gene patterns can differ greatly in conservation, suggesting distinct constraints on TF binding sites. Here, we show that a highly conserved Distal-less regulatory element (DCRE) that controls gene expression in leg precursor cells recruits multiple Hox, Extradenticle (Exd) and Homothorax (Hth) complexes to mediate dual outputs: thoracic activation and abdominal repression. Using reporter assays, we found that abdominal repression is particularly robust, as neither individual binding site mutations nor a DNA binding deficient Hth protein abolished cooperative DNA binding and in vivo repression. Moreover, a re-engineered DCRE containing a distinct configuration of Hox, Exd, and Hth sites also mediated abdominal Hox repression. However, the re-engineered DCRE failed to perform additional segment-specific functions such as thoracic activation. These findings are consistent with two emerging concepts in gene regulation: First, the abdominal Hox/Exd/Hth factors utilize protein-protein and protein-DNA interactions to form repression complexes on flexible combinations of sites, consistent with the TF collective model of CRM organization. Second, the conserved DCRE mediates multiple cell-type specific outputs, consistent with recent findings that pleiotropic CRMs are associated with conserved TF binding and added evolutionary constraints. PMID:27058369

  2. The transcriptional repressor domain of Gli3 is intrinsically disordered.

    Directory of Open Access Journals (Sweden)

    Robert Tsanev

    Full Text Available The transcription factor Gli3 is acting mainly as a transcriptional repressor in the Sonic hedgehog signal transduction pathway. Gli3 contains a repressor domain in its N-terminus from residue G106 to E236. In this study we have characterized the intracellular structure of the Gli3 repressor domain using a combined bioinformatics and experimental approach. According to our findings the Gli3 repressor domain while being intrinsically disordered contains predicted anchor sites for partner interactions. The obvious interaction partners to test were Ski and DNA; however, with both of these the structure of Gli3 repressor domain remained disordered. To locate residues important for the repressor function we mutated several residues within the Gli3 repressor domain. Two of these, H141A and H157N, targeting predicted helical regions, significantly decreased transcriptional repression and thus identify important functional parts of the domain.

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

    Directory of Open Access Journals (Sweden)

    Atsushi Kuwahara

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

  4. Trichoderma reesei CRE1-mediated Carbon Catabolite Repression in Re-sponse to Sophorose Through RNA Sequencing Analysis.

    Science.gov (United States)

    Antoniêto, Amanda Cristina Campos; de Paula, Renato Graciano; Castro, Lílian Dos Santos; Silva-Rocha, Rafael; Persinoti, Gabriela Felix; Silva, Roberto Nascimento

    2016-04-01

    Carbon catabolite repression (CCR) mediated by CRE1 in Trichoderma reesei emerged as a mechanism by which the fungus could adapt to new environments. In the presence of readily available carbon sources such as glucose, the fungus activates this mechanism and inhibits the production of cellulolytic complex enzymes to avoid unnecessary energy expenditure. CCR has been well described for the growth of T. reesei in cellulose and glucose, however, little is known about this process when the carbon source is sophorose, one of the most potent inducers of cellulase production. Thus, we performed high-throughput RNA sequencing to better understand CCR during cellulase formation in the presence of sophorose, by comparing the mutant ∆cre1 with its parental strain, QM9414. Of the 9129 genes present in the genome of T. reesei, 184 were upregulated and 344 downregulated in the mutant strain ∆cre1 compared to QM9414. Genes belonging to the CAZy database, and those encoding transcription factors and transporters are among the gene classes that were repressed by CRE1 in the presence of sophorose; most were possible indirectly regulated by CRE1. We also observed that CRE1 activity is carbon-dependent. A recent study from our group showed that in cellulose, CRE1 repress different groups of genes when compared to sophorose. CCR differences between these carbon sources may be due to the release of cellodextrins in the cellulose polymer, resulting in different targets of CRE1 in both carbon sources. These results contribute to a better understanding of CRE1-mediated CCR in T. reesei when glucose comes from a potent inducer of cellulase production such as sophorose, which could prove useful in improving cellulase production by the biotechnology sector. PMID:27226768

  5. Repression of callus initiation by the miRNA-directed interaction of auxin-cytokinin in Arabidopsis thaliana.

    Science.gov (United States)

    Liu, Zhenhua; Li, Juan; Wang, Long; Li, Qiang; Lu, Qing; Yu, Yanchong; Li, Shuo; Bai, Ming-Yi; Hu, Yuxin; Xiang, Fengning

    2016-08-01

    In tissue culture systems plant cells can be induced to regenerate to whole plants. A particularly striking example of cellular reprogramming is seen in this regeneration process, which typically begins with the induction of an intermediate cell mass referred to as callus. The identity of the key genetic cues associated with callus formation is still largely unknown. Here a microRNA-directed phytohormonal interaction is described which represses callus initiation and formation in Arabidopsis thaliana. miR160 and ARF10 (At2g28350), a gene encoding an auxin response factor, were shown to exhibit a contrasting pattern of transcription during callus initiation from pericycle-like cells. The callus initiation is faster and more prolific in a miR160-resistant form of ARF10 (mARF10), but slower and less prolific in the transgenic line over-expressing miR160c (At5g46845), arf10 and arf10 arf16 mutants than that in the wild type. ARF10 repressed the expression of Arabidopsis Response Regulator15 (ARR15, At1g74890) via its direct binding to the gene's promoter. The loss of function of ARR15 enhanced callus initiation and partly rescued the phenotype induced by the transgene Pro35S:miR160c. Overexpression of ARR15 partly rescues the callus initiation defect of mARF10 plants. Our findings define miR160 as a key repressor of callus formation and reveal that the initiation of callus is repressed by miR160-directed interaction between auxin and cytokinin. PMID:27189514

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

    Science.gov (United States)

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

    2016-01-01

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

  7. The relationship between repressive and defensive coping styles and monocyte, eosinophile, and serum glucose levels: support for the opioid peptide hypothesis of repression.

    Science.gov (United States)

    Jamner, L D; Schwartz, G E; Leigh, H

    1988-01-01

    The opioid peptide hypothesis of repression (1) predicts that repressive coping is associated with increased functional endorphin levels in the brain, which can result in decreased immunocompetence and hyperglycemia. In a random sample of 312 patients seen at a Yale Medical School outpatient clinic, significant main effects of coping style were found for monocyte and eosinophile counts, serum glucose levels, and self-reports of medication allergies. Specifically, repressive and defensive high-anxious patients demonstrated significantly decreased monocyte counts. In addition, repressive coping was associated with elevated eosinophile counts, serum glucose levels, and self-reported reactions to medications. This behavioral, immunologic, and endocrine profile is consistent with the opioid peptide hypothesis, which provides an integrative framework for relating the attenuated emotional experience of pain and distress characteristic of repressive coping with reduced resistance to infectious and neoplastic disease. PMID:2853404

  8. PRC2 regulates RNA polymerase III transcribed non-translated RNA gene transcription through EZH2 and SUZ12 interaction with TFIIIC complex

    Institute of Scientific and Technical Information of China (English)

    Liu Chang; Li Shuai; Dai Xiaoyan; Ma Ji; Wan Junhu; Jiang Hao; Wang Peng; Liu Zhaoli; Zhang Hongquan

    2015-01-01

    Polycomb repression complex 2 ( PRC2 ) component EZH2 tri-methylates H3 K27 and exerts ep-igenetic repression on target gene expression. EZH2-mediated epigenetic control of RNA polymerase II(Pol II) transcribed coding gene transcription has been well established. However, little is known about EZH2-mediated epigenetic regulation of RNA polymerase III( Pol III) transcription. Here we present a paradigm that EZH2 is in-volved in the repression of Pol III transcription via interaction with transcriptional factor complex IIIC ( TFIIIC ) . EZH2 and H3K27 me3 cooccupy the promoter of tRNATyr, 5S rRNA and 7SL RNA genes. Depletion of EZH2 or inhibition of EZH2 methyl transferase activity led to upregulation of Pol III target gene transcription. EZH2-media-ted repression of Pol III transcribed gene expression requires presence of SUZ12 . SUZ12 was able to interact with TFIIIC complex and knockdown of SUZ12 decreased occupancy of EZH2 and H3 K27 me3 at the promoter of Pol III target genes. Our findings pointed out a previously unidentified role of PRC2 complex in suppressing transcription of Pol III transcribed non-translated RNA genes, putting Pol III on a new layer of epigenetic regulation.

  9. Interleukin 2 gene transcription is regulated by Ikaros-induced changes in histone acetylation in anergic T cells

    OpenAIRE

    Bandyopadhyay, Sanmay; Duré, Myrianne; Paroder, Monika; Soto-Nieves, Noemí; Puga, Irene; Macián, Fernando

    2007-01-01

    In T cells anergy may be evoked by an unbalanced stimulation of the T-cell receptor in the absence of costimulation. Anergic T cells are unresponsive to new antigen receptor engagement and do not produce interleukin 2. We present evidence that anergizing stimuli induce changes in histone acetylation, which mediates transcriptional repression of interleukin 2 expression. In response to calcium signaling, anergic T cells up-regulate the expression of Ikaros, a zinc finger transcription factor e...

  10. A Pyrococcus homolog of the leucine-responsive regulatory protein, LrpA, inhibits transcription by abrogating RNA polymerase recruitment

    OpenAIRE

    Dahlke, Isabell; Thomm, Michael

    2002-01-01

    The genomes of Archaea harbor homologs of the global bacterial regulator leucine-responsive regulatory protein (Lrp). Archaeal Lrp homologs are helix–turn–helix DNA-binding proteins that specifically repress the transcription of their own genes in vitro. Here, we analyze the interaction of Pyrococcus LrpA with components of the archaeal transcriptional machinery at the lrpA promoter. DNA–protein complexes can be isolated by electrophoretic mobility shift assays that contain both LrpA and the ...

  11. P-Glycoprotein/MDR1 Regulates Pokemon Gene Transcription Through p53 Expression in Human Breast Cancer Cells

    OpenAIRE

    Wei Xu; Yuyang Jiang; Xuyu Zu; Shengnan He; Zhenhua Xie; Feng Liu

    2010-01-01

    P-glycoprotein (Pgp), encoded by the multidrug resistance 1 (MDR1) gene, is an efflux transporter and plays an important role in pharmacokinetics. In this study, we demonstrated that the pokemon promoter activity, the pokemon mRNA and protein expression can be significantly inhibited by Pgp. Chromatin immunoprecipitation assay showed that Pgp can bind the pokemon prompter to repress pokemon transcription activity. Furthermore, Pgp regulated pokemon transcription activity through expression of...

  12. A dual role for zinc fingers in both DNA binding and zinc sensing by the Zap1 transcriptional activator

    OpenAIRE

    Bird, Amanda J.; Zhao, Hui; Luo, Huan; Jensen, Laran T.; Srinivasan, Chandra; Evans-Galea, Marguerite; Winge, Dennis R.; Eide, David J.

    2000-01-01

    The Zap1 transcriptional activator of Saccharomyces cerevisiae controls zinc homeostasis. Zap1 induces target gene expression in zinc-limited cells and is repressed by high zinc. One such target gene is ZAP1 itself. In this report, we examine how zinc regulates Zap1 function. First, we show that transcriptional autoregulation of Zap1 is a minor component of zinc responsiveness; most regulation of Zap1 activity occurs post-translationally. Secondly, nuclear localization of Zap1 does not change...

  13. Imipenem represses CRISPR-Cas interference of DNA acquisition through H-NS stimulation in Klebsiella pneumoniae.

    Science.gov (United States)

    Lin, Tzu-Lung; Pan, Yi-Jiun; Hsieh, Pei-Fang; Hsu, Chun-Ru; Wu, Meng-Chuan; Wang, Jin-Town

    2016-01-01

    Analysis of the genome of Klebsiella pneumoniae NTUH-K2044 strain revealed the presence of two clustered regularly interspaced short palindromic repeats (CRISPR) arrays separated with CRISPR-associated (cas) genes. Carbapenem-resistant K. pneumoniae isolates were observed to be less likely to have CRISPR-Cas than sensitive strains (5/85 vs. 22/132). Removal of the transcriptional repressor, H-NS, was shown to prevent the transformation of plasmids carrying a spacer and putative proto-spacer adjacent motif (PAM). The CRISPR-Cas system also decreased pUC-4K plasmid stability, resulting in plasmid loss from the bacteria with acquisition of new spacers. Analysis of the acquired proto-spacers in pUC-4K indicated that 5'-TTN-3' was the preferred PAM in K. pneumoniae. Treatment of cells by imipenem induced hns expression, thereby decreasing cas3 expression and consequently repressed CRISPR-Cas activity resulted in increase of plasmid stability. In conclusion, NTUH-K2044 CRISPR-Cas contributes to decrease of plasmid transformation and stability. Through repression of CRISPR-Cas activity by induced H-NS, bacteria might be more able to acquire DNA to confront the challenge of imipenem. PMID:27531594

  14. Repression of virulence genes by phosphorylation-dependent oligomerization of CsrR at target promoters in S. pyogenes.

    Science.gov (United States)

    Miller, A A; Engleberg, N C; DiRita, V J

    2001-05-01

    csrRS encodes a two-component regulatory system that represses the transcription of a number of virulence factors in Streptococcus pyogenes, including the hyaluronic acid capsule and pyrogenic exotoxin B. CsrRS-regulated virulence factors have diverse functions during pathogenesis and are differentially expressed throughout growth. This suggests that multiple signals induce CsrRS-mediated gene regulation, or that regulated genes respond differently to CsrR, or both. As a first step in dissecting the csrRS signal transduction pathway, we determined the mechanism by which CsrR mediates the repression of its target promoters. We found that phosphorylated CsrR binds directly to all but one of the promoters of its regulated genes, with different affinities. Phosphorylation of CsrR enhances both oligomerization and DNA binding. We defined the binding site of CsrR at each of the regulated promoters using DNase I and hydroxyl radical footprinting. Based on these results, we propose a model for differential regulation by CsrRS. PMID:11401704

  15. The synergistic repressive effect of NF-κB and JNK inhibitor on the clonogenic capacity of Jurkat leukemia cells.

    Directory of Open Access Journals (Sweden)

    Xinli Liu

    Full Text Available Deregulation of Nuclear Transcription Factor-κB (NF-κB and Jun N-terminal kinase (JNK signaling is commonly detected in leukemia, suggesting an important role for these two signaling pathways in the pathogenesis of leukemia. In this study, using Jurkat cells, an acute T-lymphoblastic leukemia (T-ALL cell line, we evaluated the effects of an NF-κB inhibitor and a JNK inhibitor individually and in combination on the proliferation, survival and clonogenic capacity of leukemic cells. We found that leukemic stem/progenitor cells (LSPCs were more sensitive to NF-κB inhibitor treatment than were healthy hematopoietic stem/progenitor cells (HSPCs, as shown by a reduction in the clonogenic capacity of the former. Inactivation of NF-κB leads to the activation of JNK signaling in both leukemic cells and healthy HSPCs. Interestingly, JNK inhibitor treatment enhanced the repressive effects of NF-κB inhibitor on LSPCs but prevented such repression in HSPCs. Our data suggest that JNK signaling stimulates proliferation/survival in LSPCs but is a death signal in HSPCs. The combination of NF-κB inhibitor and JNK inhibitor might provide a better treatment for T-ALL leukemia by synergistically killing LSPCs while simultaneously preventing the death of normal HPCs.

  16. The synergistic repressive effect of NF-κB and JNK inhibitor on the clonogenic capacity of Jurkat leukemia cells.

    Science.gov (United States)

    Liu, Xinli; Zhang, Jun; Li, Jing; Volk, Andrew; Breslin, Peter; Zhang, Jiwang; Zhang, Zhou

    2014-01-01

    Deregulation of Nuclear Transcription Factor-κB (NF-κB) and Jun N-terminal kinase (JNK) signaling is commonly detected in leukemia, suggesting an important role for these two signaling pathways in the pathogenesis of leukemia. In this study, using Jurkat cells, an acute T-lymphoblastic leukemia (T-ALL) cell line, we evaluated the effects of an NF-κB inhibitor and a JNK inhibitor individually and in combination on the proliferation, survival and clonogenic capacity of leukemic cells. We found that leukemic stem/progenitor cells (LSPCs) were more sensitive to NF-κB inhibitor treatment than were healthy hematopoietic stem/progenitor cells (HSPCs), as shown by a reduction in the clonogenic capacity of the former. Inactivation of NF-κB leads to the activation of JNK signaling in both leukemic cells and healthy HSPCs. Interestingly, JNK inhibitor treatment enhanced the repressive effects of NF-κB inhibitor on LSPCs but prevented such repression in HSPCs. Our data suggest that JNK signaling stimulates proliferation/survival in LSPCs but is a death signal in HSPCs. The combination of NF-κB inhibitor and JNK inhibitor might provide a better treatment for T-ALL leukemia by synergistically killing LSPCs while simultaneously preventing the death of normal HPCs. PMID:25526629

  17. The Synergistic Repressive Effect of NF-κB and JNK Inhibitor on the Clonogenic Capacity of Jurkat Leukemia Cells

    Science.gov (United States)

    Liu, Xinli; Zhang, Jun; Li, Jing; Volk, Andrew; Breslin, Peter; Zhang, Jiwang; Zhang, Zhou

    2014-01-01

    Deregulation of Nuclear Transcription Factor-κB (NF-κB) and Jun N-terminal kinase (JNK) signaling is commonly detected in leukemia, suggesting an important role for these two signaling pathways in the pathogenesis of leukemia. In this study, using Jurkat cells, an acute T-lymphoblastic leukemia (T-ALL) cell line, we evaluated the effects of an NF-κB inhibitor and a JNK inhibitor individually and in combination on the proliferation, survival and clonogenic capacity of leukemic cells. We found that leukemic stem/progenitor cells (LSPCs) were more sensitive to NF-κB inhibitor treatment than were healthy hematopoietic stem/progenitor cells (HSPCs), as shown by a reduction in the clonogenic capacity of the former. Inactivation of NF-κB leads to the activation of JNK signaling in both leukemic cells and healthy HSPCs. Interestingly, JNK inhibitor treatment enhanced the repressive effects of NF-κB inhibitor on LSPCs but prevented such repression in HSPCs. Our data suggest that JNK signaling stimulates proliferation/survival in LSPCs but is a death signal in HSPCs. The combination of NF-κB inhibitor and JNK inhibitor might provide a better treatment for T-ALL leukemia by synergistically killing LSPCs while simultaneously preventing the death of normal HPCs. PMID:25526629

  18. Receptor interconversion model of hormone action. 3. Estrogen receptor mediated repression of reporter gene activity in A431 cells.

    Science.gov (United States)

    Nag, A; Park, I; Krust, A; Smith, R G

    1990-03-20

    The chicken estrogen receptor exists in three interconvertible forms, two of which bind estradiol with high affinity and one which lacks the capacity to bind estradiol. Interconversion is regulated by reactions involving ATP/Mg2+. By cotransfecting into A431 cells estrogen receptor cDNA in an expression vector together with the pA2 (-821/-87) tk-CAT vitellogenin construct, we demonstrate that constitutive expression of chloramphenicol acetyltransferase (CAT) activity can be regulated either by selection of ligand or by modifying phosphorylation reactions in the recipient cells. In the presence of estrogen receptors, constitutive expression of CAT activity is inhibited in three situations: (i) in the absence of an estrogenic ligand; (ii) in the presence of an anti-estrogen; and (iii) in the presence of an estrogenic ligand together with 12-O-tetradecanoylphorbol 13-acetate (TPA). Estrogen receptor mediated repression of constitutive CAT activity is not observed with the pA2 (-331/-87) tk-CAT construct, indicating that DNA sequences required for repression are located between -821 and -331 base pairs upstream of the transcription initiation site. PMID:2346742

  19. Asymmetric arginine dimethylation of RelA provides a repressive mark to modulate TNFα/NF-κB response.

    Science.gov (United States)

    Reintjes, Anja; Fuchs, Julian E; Kremser, Leopold; Lindner, Herbert H; Liedl, Klaus R; Huber, Lukas A; Valovka, Taras

    2016-04-19

    Nuclear factor kappa B (NF-κB) is an inducible transcription factor that plays critical roles in immune and stress responses and is often implicated in pathologies, including chronic inflammation and cancer. Although much has been learned about NF-κB-activating pathways, the specific repression of NF-κB is far less well understood. Here we identified the type I protein arginine methyltransferase 1 (PRMT1) as a restrictive factor controlling TNFα-induced activation of NF-κB. PRMT1 forms a cellular complex with NF-κB through direct interaction with the Rel homology domain of RelA. We demonstrate that PRMT1 methylates RelA at evolutionary conserved R30, located in the DNA-binding L1 loop, which is a critical residue required for DNA binding. Asymmetric R30 dimethylation inhibits the binding of RelA to DNA and represses NF-κB target genes in response to TNFα. Molecular dynamics simulations of the DNA-bound RelA:p50 predicted structural changes in RelA caused by R30 methylation or a mutation that interferes with the stability of the DNA-NF-κB complex. Our findings provide evidence for the asymmetric arginine dimethylation of RelA and unveil a unique mechanism controlling TNFα/NF-κB signaling. PMID:27051065

  20. Repression of death consciousness and the psychedelic trip

    Directory of Open Access Journals (Sweden)

    Varsha Dutta

    2012-01-01

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

  1. Defining the genome-wide role of CRE1 during carbon catabolite repression in Trichoderma reesei using RNA-Seq analysis.

    Science.gov (United States)

    Antoniêto, Amanda Cristina Campos; dos Santos Castro, Lílian; Silva-Rocha, Rafael; Persinoti, Gabriela Felix; Silva, Roberto Nascimento

    2014-12-01

    The ascomycete Trichoderma reesei is one of the most well-studied cellulolytic fungi and is widely used by the biotechnology industry in the production of second generation bioethanol. The carbon catabolite repression (CCR) mechanism adopted by T. reesei is mediated by the transcription factor CRE1. CCR represses genes related to cellulase production when a carbon source is readily available in the medium. Using RNA sequencing, we investigated CCR during the synthesis of cellulases, comparing the T. reesei Δcre1 mutant strain with its parental strain, QM9414. Of 9129 genes in the T. reesei genome, 268 genes were upregulated and 85 were downregulated in the presence of cellulose (Avicel). In addition, 251 genes were upregulated and 230 were downregulated in the presence of a high concentration of glucose. Genes encoding cellulolytic enzymes and transcription factors and genes related to the transport of nutrients and oxidative metabolism were also targets of CCR, mediated by CRE1 in a carbon source-dependent manner. Our results also suggested that CRE1 regulates the expression of genes related to the use of copper and iron as final electron acceptors or as cofactors of enzymes that participate in biomass degradation. As a result, the final effect of CRE1-mediated transcriptional regulation is to modulate the access of cellulolytic enzymes to cellulose polymers or blocks the entry of cellulase inducers into the cell, depending on the glucose content in the medium. These results will contribute to a better understanding of the mechanism of carbon catabolite repression in T. reesei, thereby enhancing its application in several biotechnology fields. PMID:25459535

  2. Repressive coping and alexithymia in ideopathic environmental intolerance

    DEFF Research Database (Denmark)

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

    2010-01-01

    Objective To examine if the non-expression of negative emotions (i.e., repressive coping) and differences in the ability to process and regulate emotions (i.e., alexithymia) is associated with idiopathic environmental intolerance (IEI). Methods The study included participants who had previously...... and negative emotional reactions, defensiveness and difficulties identifying feelings were found, suggesting a need for exploring the influence of these emotional reactions in IEI.......) and the Taylor Manifest Anxiety Scale (TMAS), the Toronto Alexithymia Scale (TAS-20), and a negative affectivity scale (NAS). Multiple, hierarchical linear regression analyses were conducted using IEI variables as the dependent variables. Results The TMAS and MCSDS scores were independently associated...

  3. The complexity of miRNA-mediated repression

    OpenAIRE

    Wilczynska, A.; Bushell, M.

    2014-01-01

    Since their discovery 20 years ago, miRNAs have attracted much attention from all areas of biology. These short (∼22 nt) non-coding RNA molecules are highly conserved in evolution and are present in nearly all eukaryotes. They have critical roles in virtually every cellular process, particularly determination of cell fate in development and regulation of the cell cycle. Although it has long been known that miRNAs bind to mRNAs to trigger translational repression and degradation, there had bee...

  4. ANKRD1 acts as a transcriptional repressor of MMP13 via the AP-1 site.

    Science.gov (United States)

    Almodóvar-García, Karinna; Kwon, Minjae; Samaras, Susan E; Davidson, Jeffrey M

    2014-04-01

    The transcriptional cofactor ANKRD1 is sharply induced during wound repair, and its overexpression enhances healing. We recently found that global deletion of murine Ankrd1 impairs wound contraction and enhances necrosis of ischemic wounds. A quantitative PCR array of Ankrd1(-/-) (KO) fibroblasts indicated that ANKRD1 regulates MMP genes. Yeast two-hybrid and coimmunoprecipitation analyses associated ANKRD1 with nucleolin, which represses AP-1 activation of MMP13. Ankrd1 deletion enhanced both basal and phorbol 12-myristate 13-acetate (PMA)-induced MMP13 promoter activity; conversely, Ankrd1 overexpression in control cells decreased PMA-induced MMP13 promoter activity. Ankrd1 reconstitution in KO fibroblasts decreased MMP13 mRNA, while Ankrd1 knockdown increased these levels. MMP13 mRNA and protein were elevated in intact skin and wounds of KO versus Ankrd1(fl/fl) (FLOX) mice. Electrophoretic mobility shift assay gel shift patterns suggested that additional transcription factors bind to the MMP13 AP-1 site in the absence of Ankrd1, and this concept was reinforced by chromatin immunoprecipitation analysis as greater binding of c-Jun to the AP-1 site in extracts from FLOX versus KO fibroblasts. We propose that ANKRD1, in association with factors such as nucleolin, represses MMP13 transcription. Ankrd1 deletion additionally relieved MMP10 transcriptional repression. Nuclear ANKRD1 appears to modulate extracellular matrix remodeling by MMPs. PMID:24515436

  5. Matrix Gla protein repression by miR-155 promotes oncogenic signals in breast cancer MCF-7 cells.

    Science.gov (United States)

    Tiago, Daniel M; Conceição, Natércia; Caiado, Helena; Laizé, Vincent; Cancela, Maria Leonor

    2016-04-01

    MGP is a protein that was initially associated with the inhibition of calcification in skeleton, soft tissues, and arteries, but more recently also implicated in cancer. In breast cancer, higher levels of MGP mRNA were associated with poor prognosis, but since this deregulation was never demonstrated at the protein level, we postulated the involvement of a post-transcriptional regulatory mechanism. In this work we show that MGP is significantly repressed by miR-155 in breast cancer MCF-7 cells, and concomitantly there is a stimulation of cell proliferation and cell invasiveness. This study brings new insights into the putative involvement of MGP and oncomiR-155 in breast cancer, and may contribute to develop new therapeutic strategies. PMID:27009385

  6. Quality and position of the three lac operators of E. coli define efficiency of repression.

    OpenAIRE

    Oehler, S; Amouyal, M; Kolkhof, P.; von Wilcken-Bergmann, B; Müller-Hill, B

    1994-01-01

    Repression of the lac promoter may be achieved in two different ways: either by interference with the action of RNA polymerase or by interference with CAP activation. We investigated cooperative repression of the Escherichia coli lac operon by systematic conversion of its three natural operators (O1, O2 and O3) on the chromosome. We find that cooperative repression by tetrameric Lac repressor increases with both quality and proximity of the interacting operators. A short distance of 92 bp all...

  7. Polycomb-Mediated Repression and Sonic Hedgehog Signaling Interact to Regulate Merkel Cell Specification during Skin Development.

    Directory of Open Access Journals (Sweden)

    Carolina N Perdigoto

    2016-07-01

    Full Text Available An increasing amount of evidence indicates that developmental programs are tightly regulated by the complex interplay between signaling pathways, as well as transcriptional and epigenetic processes. Here, we have uncovered coordination between transcriptional and morphogen cues to specify Merkel cells, poorly understood skin cells that mediate light touch sensations. In murine dorsal skin, Merkel cells are part of touch domes, which are skin structures consisting of specialized keratinocytes, Merkel cells, and afferent neurons, and are located exclusively around primary hair follicles. We show that the developing primary hair follicle functions as a niche required for Merkel cell specification. We find that intraepidermal Sonic hedgehog (Shh signaling, initiated by the production of Shh ligand in the developing hair follicles, is required for Merkel cell specification. The importance of Shh for Merkel cell formation is further reinforced by the fact that Shh overexpression in embryonic epidermal progenitors leads to ectopic Merkel cells. Interestingly, Shh signaling is common to primary, secondary, and tertiary hair follicles, raising the possibility that there are restrictive mechanisms that regulate Merkel cell specification exclusively around primary hair follicles. Indeed, we find that loss of Polycomb repressive complex 2 (PRC2 in the epidermis results in the formation of ectopic Merkel cells that are associated with all hair types. We show that PRC2 loss expands the field of epidermal cells competent to differentiate into Merkel cells through the upregulation of key Merkel-differentiation genes, which are known PRC2 targets. Importantly, PRC2-mediated repression of the Merkel cell differentiation program requires inductive Shh signaling to form mature Merkel cells. Our study exemplifies how the interplay between epigenetic and morphogen cues regulates the complex patterning and formation of the mammalian skin structures.

  8. Polycomb-Mediated Repression and Sonic Hedgehog Signaling Interact to Regulate Merkel Cell Specification during Skin Development

    Science.gov (United States)

    Bar, Carmit; Tsai, Pai-Chi; Valdes, Victor J.; Cohen, Idan; Santoriello, Francis J.; Zhao, Dejian; Hsu, Ya-Chieh; Ezhkova, Elena

    2016-01-01

    An increasing amount of evidence indicates that developmental programs are tightly regulated by the complex interplay between signaling pathways, as well as transcriptional and epigenetic processes. Here, we have uncovered coordination between transcriptional and morphogen cues to specify Merkel cells, poorly understood skin cells that mediate light touch sensations. In murine dorsal skin, Merkel cells are part of touch domes, which are skin structures consisting of specialized keratinocytes, Merkel cells, and afferent neurons, and are located exclusively around primary hair follicles. We show that the developing primary hair follicle functions as a niche required for Merkel cell specification. We find that intraepidermal Sonic hedgehog (Shh) signaling, initiated by the production of Shh ligand in the developing hair follicles, is required for Merkel cell specification. The importance of Shh for Merkel cell formation is further reinforced by the fact that Shh overexpression in embryonic epidermal progenitors leads to ectopic Merkel cells. Interestingly, Shh signaling is common to primary, secondary, and tertiary hair follicles, raising the possibility that there are restrictive mechanisms that regulate Merkel cell specification exclusively around primary hair follicles. Indeed, we find that loss of Polycomb repressive complex 2 (PRC2) in the epidermis results in the formation of ectopic Merkel cells that are associated with all hair types. We show that PRC2 loss expands the field of epidermal cells competent to differentiate into Merkel cells through the upregulation of key Merkel-differentiation genes, which are known PRC2 targets. Importantly, PRC2-mediated repression of the Merkel cell differentiation program requires inductive Shh signaling to form mature Merkel cells. Our study exemplifies how the interplay between epigenetic and morphogen cues regulates the complex patterning and formation of the mammalian skin structures. PMID:27414999

  9. SUPPRESSOR OF PHYTOCHROME B4-#3 Represses Genes Associated with Auxin Signaling to Modulate Hypocotyl Growth.

    Science.gov (United States)

    Favero, David S; Jacques, Caitlin N; Iwase, Akira; Le, Kimberly Ngan; Zhao, Jianfei; Sugimoto, Keiko; Neff, Michael M

    2016-08-01

    Developing seedlings are well equipped to alter their growth in response to external factors in order to maximize their chances of survival. SUPPRESSOR OF PHYTOCHROME B4-#3 (SOB3) and other members of the AT-HOOK MOTIF CONTAINING NUCLEAR LOCALIZED (AHL) family of transcription factors modulate the development of Arabidopsis (Arabidopsis thaliana) by repressing hypocotyl elongation in young seedlings growing in light. However, the molecular mechanism behind how AHLs influence seedling development is largely unknown. We have identified genes associated with auxin-mediated hypocotyl elongation as downstream targets of SOB3. We found that YUCCA8 (YUC8) as well as members of the SMALL AUXIN UP-REGULATED RNA19 (SAUR19) subfamily were down-regulated in the short-hypocotyl, gain-of-function SOB3-D mutant and up-regulated in the dominant-negative, tall-hypocotyl sob3-6 mutant. SOB3-D and sob3-6 hypocotyls also exhibited altered sensitivity to the polar auxin transport inhibitor N-1-napthylphthalamic acid, suggesting a critical connection between auxin and the modulation of seedling elongation by SOB3 Finally, we found that overexpression of GREEN FLUORESCENT PROTEIN-SAUR19 in the SOB3-D line partially rescued defects in hypocotyl elongation, and SOB3 bound directly to the promoters of YUC8 and SAUR19 subfamily members. Taken together, these data indicate that SOB3 modulates hypocotyl elongation in young seedlings by directly repressing the transcription of genes associated with auxin signaling. PMID:27342309

  10. SUPPRESSOR OF PHYTOCHROME B4-#3 Represses Genes Associated with Auxin Signaling to Modulate Hypocotyl Growth1[OPEN

    Science.gov (United States)

    Iwase, Akira

    2016-01-01

    Developing seedlings are well equipped to alter their growth in response to external factors in order to maximize their chances of survival. SUPPRESSOR OF PHYTOCHROME B4-#3 (SOB3) and other members of the AT-HOOK MOTIF CONTAINING NUCLEAR LOCALIZED (AHL) family of transcription factors modulate the development of Arabidopsis (Arabidopsis thaliana) by repressing hypocotyl elongation in young seedlings growing in light. However, the molecular mechanism behind how AHLs influence seedling development is largely unknown. We have identified genes associated with auxin-mediated hypocotyl elongation as downstream targets of SOB3. We found that YUCCA8 (YUC8) as well as members of the SMALL AUXIN UP-REGULATED RNA19 (SAUR19) subfamily were down-regulated in the short-hypocotyl, gain-of-function SOB3-D mutant and up-regulated in the dominant-negative, tall-hypocotyl sob3-6 mutant. SOB3-D and sob3-6 hypocotyls also exhibited altered sensitivity to the polar auxin transport inhibitor N-1-napthylphthalamic acid, suggesting a critical connection between auxin and the modulation of seedling elongation by SOB3. Finally, we found that overexpression of GREEN FLUORESCENT PROTEIN-SAUR19 in the SOB3-D line partially rescued defects in hypocotyl elongation, and SOB3 bound directly to the promoters of YUC8 and SAUR19 subfamily members. Taken together, these data indicate that SOB3 modulates hypocotyl elongation in young seedlings by directly repressing the transcription of genes associated with auxin signaling. PMID:27342309

  11. Transcriptional regulation of nitrogen fixation by molybdenum in Azotobacter vinelandii.

    OpenAIRE

    Jacobson, M R; Premakumar, R; Bishop, P E

    1986-01-01

    Multiple genomic regions homologous to nifH were found in the diazotroph Azotobacter vinelandii. The nifHDK gene cluster, located on a 12.8-kilobase (kb) XhoI fragment and two additional XhoI fragments (7.4 and 8.4 kb) hybridized to a nifH-specific DNA template but the 7.4- and 8.4-kb fragments did not hybridize to nifD- or nifK-specific DNA probes. In vivo transcription of the nifHDK gene cluster was ammonia-repressible and required the presence of at least 50 nM molybdenum in the derepressi...

  12. Transcriptional Response of Escherichia coli to External Zinc

    OpenAIRE

    Yamamoto, Kaneyoshi; Ishihama, Akira

    2005-01-01

    Transcriptional response of Escherichia coli to extracellular zinc was studied using DNA microarray and S1 mapping assays. Addition of external zinc induced the expression of zinc exporter ZntA and inhibited the expression of zinc importer ZnuC. In the continuous presence of zinc, ZnuC repression took place at lower zinc concentrations than ZntA induction. The microarray assay indicated that the addition of excess external zinc induces the expression of many genes that are organized in the re...

  13. The transcriptional landscape

    DEFF Research Database (Denmark)

    Nielsen, Henrik

    2011-01-01

    The application of new and less biased methods to study the transcriptional output from genomes, such as tiling arrays and deep sequencing, has revealed that most of the genome is transcribed and that there is substantial overlap of transcripts derived from the two strands of DNA. In protein coding...... independent transcription from within the unit. In genomic regions separating those that encode proteins or highly abundant RNA molecules with known function, transcripts are generally of low abundance and short-lived. In most of these cases, it is unclear to what extent a function is related to transcription...

  14. Stromelysin-3 induction and interstitial collagenase repression by retinoic acid. Therapeutical implication of receptor-selective retinoids dissociating transactivation and AP-1-mediated transrepression.

    Science.gov (United States)

    Guérin, E; Ludwig, M G; Basset, P; Anglard, P

    1997-04-25

    Human stromelysin-3 and interstitial collagenase are matrix metalloproteinases whose expression by stromal cells in several types of carcinomas has been associated with cancer progression. We compared here the regulation of the expression of both proteinases by retinoids in human fibroblasts. Physiological concentrations of retinoic acid were found to simultaneously induce stromelysin-3 and repress interstitial collagenase. In both cases, the involvement of a transcriptional mechanism was supported by run-on assays. Furthermore, in transient transfection experiments, the activity of the stromelysin-3 promoter was induced by retinoic acid through endogenous receptors acting on a DR1 retinoic acid-responsive element. The ligand-dependent activation of the receptors was also investigated by using selective synthetic retinoids, and we demonstrated that retinoic acid-retinoid X receptor heterodimers were the most potent functional units controlling both stromelysin-3 induction and interstitial collagenase repression. However, specific retinoids dissociating the transactivation and the AP-1-mediated transrepression functions of the receptors were found to repress interstitial collagenase without inducing stromelysin-3. These findings indicate that such retinoids may represent efficient inhibitors of matrix metalloproteinase expression in the treatment of human carcinomas. PMID:9111003

  15. MYCN/c-MYC-induced microRNAs repress coding gene networks associated with poor outcome in MYCN/c-MYC-activated tumors.

    Science.gov (United States)

    Mestdagh, P; Fredlund, E; Pattyn, F; Schulte, J H; Muth, D; Vermeulen, J; Kumps, C; Schlierf, S; De Preter, K; Van Roy, N; Noguera, R; Laureys, G; Schramm, A; Eggert, A; Westermann, F; Speleman, F; Vandesompele, J

    2010-03-01

    Increased activity of MYC protein-family members is a common feature in many cancers. Using neuroblastoma as a tumor model, we established a microRNA (miRNA) signature for activated MYCN/c-MYC signaling in two independent primary neuroblastoma tumor cohorts and provide evidence that c-MYC and MYCN have overlapping functions. On the basis of an integrated approach including miRNA and messenger RNA (mRNA) gene expression data we show that miRNA activation contributes to widespread mRNA repression, both in c-MYC- and MYCN-activated tumors. c-MYC/MYCN-induced miRNA activation was shown to be dependent on c-MYC/MYCN promoter binding as evidenced by chromatin immunoprecipitation. Finally, we show that pathways, repressed through c-MYC/MYCN miRNA activation, are highly correlated to tumor aggressiveness and are conserved across different tumor entities suggesting that c-MYC/MYCN activate a core set of miRNAs for cooperative repression of common transcriptional programs related to disease aggressiveness. Our results uncover a widespread correlation between miRNA activation and c-MYC/MYCN-mediated coding gene expression modulation and further substantiate the overlapping functions of c-MYC and MYCN in the process of tumorigenesis. PMID:19946337

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

    Science.gov (United States)

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

    2016-01-01

    Oct4 is considered a key transcription factor for pluripotent stem cell self-renewal. It binds to specific regions within target genes to regulate their expression and is downregulated upon induction of differentiation of pluripotent stem cells; however, the mechanisms that regulate the levels of human Oct4 expression remain poorly understood. Here we show that expression of human Oct4 is directly repressed by germ cell nuclear factor (GCNF), an orphan nuclear receptor, in hES cells. Knockdown of GCNF by siRNA resulted in maintenance of Oct4 expression during RA-induced hES cell differentiation. While overexpression of GCNF promoted repression of Oct4 expression in both undifferentiated and differentiated hES cells. The level of Oct4 repression was dependent on the level of GCNF expression in a dose-dependent manner. mRNA microarray analysis demonstrated that overexpression of GCNF globally regulates gene expression in undifferentiated and differentiated hES cells. Within the group of altered genes, GCNF down-regulated 36% of the genes, and up-regulated 64% in undifferentiated hES cells. In addition, GCNF also showed a regulatory gene pattern that is different from RA treatment during hES cell differentiation. These findings increase our understanding of the mechanisms that maintain hES cell pluripotency and regulate gene expression during the differentiation process. PMID:26769970

  17. Sulforaphane causes epigenetic repression of hTERT expression in human breast cancer cell lines.

    Directory of Open Access Journals (Sweden)

    Syed M Meeran

    Full Text Available BACKGROUND: Sulforaphane (SFN, an isothiocyanate found in cruciferous vegetables, is a common dietary component that has histone deacetylase inhibition activity and exciting potential in cancer prevention. The mechanisms by which SFN imparts its chemopreventive properties are of considerable interest and little is known of its preventive potential for breast cancer. PRINCIPAL FINDINGS: We found that SFN significantly inhibits the viability and proliferation of breast cancer cells in vitro while it has negligible effects on normal breast cells. Inhibition of telomerase has received considerable attention because of its high expression in cancer cells and extremely low level of expression in normal cells. SFN treatment dose- and time-dependently inhibited human telomerase reverse transcriptase (hTERT, the catalytic regulatory subunit of telomerase, in both MCF-7 and MDA-MB-231 human breast cancer cells. DNA methyltransferases (DNMTs, especially DNMT1 and DNMT3a, were also decreased in SFN-treated breast cancer cells suggesting that SFN may repress hTERT by impacting epigenetic pathways. Down-regulation of DNMTs in response to SFN induced site-specific CpG demethylation occurring primarily in the first exon of the hTERT gene thereby facilitating CTCF binding associated with hTERT repression. Chromatin immunoprecipitation (ChIP analysis of the hTERT promoter revealed that SFN increased the level of active chromatin markers acetyl-H3, acetyl-H3K9 and acetyl-H4, whereas the trimethyl-H3K9 and trimethyl-H3K27 inactive chromatin markers were decreased in a dose-dependent manner. SFN-induced hyperacetylation facilitated the binding of many hTERT repressor proteins such as MAD1 and CTCF to the hTERT regulatory region. Depletion of CTCF using siRNA reduced the SFN-induced down-regulation of hTERT mRNA transcription in these breast cancer cells. In addition, down-regulation of hTERT expression facilitated the induction of cellular apoptosis in human breast

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-08-01

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

  20. UmuDAb: An Error-Prone Polymerase Accessory Homolog Whose N-Terminal Domain Is Required for Repression of DNA Damage Inducible Gene Expression in Acinetobacter baylyi.

    Directory of Open Access Journals (Sweden)

    Travis A Witkowski

    Full Text Available In many bacteria, the DNA damage response induces genes (SOS genes that were repressed by LexA. LexA represses transcription by binding to SOS promoters via a helix-turn-helix motif in its N-terminal domain (NTD. Upon DNA damage, LexA cleaves itself and allows induction of transcription. In Acinetobacter baumannii and Acinetobacter baylyi, multiple genes are induced by DNA damage, and although the Acinetobacter genus lacks LexA, a homolog of the error-prone polymerase subunit UmuD, called UmuDAb, regulates some DNA damage-induced genes. The mechanism of UmuDAb regulation has not been determined. We constructed UmuDAb mutant strains of A. baylyi to test whether UmuDAb mediates gene regulation through LexA-like repressor actions consisting of relief of repression through self-cleavage after DNA damage. Real-time quantitative PCR experiments in both a null umuDAb mutant and an NTD mutant showed that the DNA damage-inducible, UmuDAb-regulated gene ddrR was highly expressed even in the absence of DNA damage. Protein modeling identified a potential LexA-like helix-turn-helix structure in the UmuDAb NTD, which when disrupted, also relieved ddrR and umuDAb repression under non-inducing conditions. Mutations in a putative SOS box in the shared umuDAb-ddrR promoter region similarly relieved these genes' repression under non-inducing conditions. Conversely, cells possessing a cleavage-deficient UmuDAb were unable to induce gene expression after MMC-mediated DNA damage. This evidence of a UmuDAb repressor mechanism was contrasted with the failure of umuDAb to complement an Escherichia coli umuD mutant for UmuD error-prone DNA replication activity. Similarly, A. baumannii null umuDAb mutant cells did not have a reduced UmuD'2UmuC-mediated mutation rate after DNA damage, suggesting that although this UmuDAb protein may have evolved from a umuDC operon in this genus, it now performs a LexA-like repressor function for a sub-set of DNA damage-induced genes.

  1. Suppression of estrogen receptor transcriptional activity by connective tissue growth factor.

    Directory of Open Access Journals (Sweden)

    Long Cheng

    Full Text Available Secreted growth factors have been shown to stimulate the transcriptional activity of estrogen receptors (ER that are responsible for many biological processes. However, whether these growth factors physically interact with ER remains unclear. Here, we show for the first time that connective tissue growth factor (CTGF physically and functionally associates with ER. CTGF interacted with ER both in vitro and in vivo. CTGF interacted with ER DNA-binding domain. ER interaction region in CTGF was mapped to the thrombospondin type I repeat, a cell attachment motif. Overexpression of CTGF inhibited ER transcriptional activity as well as the expression of estrogen-responsive genes, including pS2 and cathepsin D. Reduction of endogenous CTGF with CTGF small interfering RNA enhanced ER transcriptional activity. The interaction between CTGF and ER is required for the repression of estrogen-responsive transcription by CTGF. Moreover, CTGF reduced ER protein expression, whereas the CTGF mutant that did not repress ER transcriptional activity also did not alter ER protein levels. The results suggested the transcriptional regulation of estrogen signaling through interaction between CTGF and ER, and thus may provide a novel mechanism by which cross-talk between secreted growth factor and ER signaling pathways occurs.

  2. DNA Topoisomerases maintain promoters in a state competent for transcriptional activation in Saccharomyces cerevisiae.

    Directory of Open Access Journals (Sweden)

    Jakob Madsen Pedersen

    Full Text Available To investigate the role of DNA topoisomerases in transcription, we have studied global gene expression in Saccharomyces cerevisiae cells deficient for topoisomerases I and II and performed single-gene analyses to support our findings. The genome-wide studies show a general transcriptional down-regulation upon lack of the enzymes, which correlates with gene activity but not gene length. Furthermore, our data reveal a distinct subclass of genes with a strong requirement for topoisomerases. These genes are characterized by high transcriptional plasticity, chromatin regulation, TATA box presence, and enrichment of a nucleosome at a critical position in the promoter region, in line with a repressible/inducible mode of regulation. Single-gene studies with a range of genes belonging to this group demonstrate that topoisomerases play an important role during activation of these genes. Subsequent in-depth analysis of the inducible PHO5 gene reveals that topoisomerases are essential for binding of the Pho4p transcription factor to the PHO5 promoter, which is required for promoter nucleosome removal during activation. In contrast, topoisomerases are dispensable for constitutive transcription initiation and elongation of PHO5, as well as the nuclear entrance of Pho4p. Finally, we provide evidence that topoisomerases are required to maintain the PHO5 promoter in a superhelical state, which is competent for proper activation. In conclusion, our results reveal a hitherto unknown function of topoisomerases during transcriptional activation of genes with a repressible/inducible mode of regulation.

  3. Variable coordination of cotranscribed genes in Escherichia coli following antisense repression

    Directory of Open Access Journals (Sweden)

    Kulyté Agne

    2006-11-01

    Full Text Available Abstract Background A majority of bacterial genes belong to tight clusters and operons, which complicates gene functional studies using conventional knock-out methods. Antisense agents can down-regulate the expression of genes without disrupting the genome because they bind mRNA and block its expression. However, it is unclear how antisense inhibition affects expression from genes that are cotranscribed with the target. Results To examine the effects of antisense inhibition on cotranscribed genes, we constructed a plasmid expressing the two reporter genes gfp and DsRed as one transcriptional unit. Incubation with antisense peptide nucleic acid (PNA targeted to the mRNA start codon region of either the upstream gfp or the downstream DsRed gene resulted in a complete expression discoordination from this artificial construct. The same approach was applied to the three cotranscribed genes in the endogenously expressed lac-operon (lacZ, Y and A and partial downstream expression coordination was seen when the lacZ start codon was targeted with antisense PNA. Targeting the lacY mRNA start codon region showed no effect on the upstream lacZ gene expression whereas expression from the downstream lacA gene was affected as strongly as the lacY gene. Determination of lacZ and lacY mRNA levels revealed a pattern of reduction that was similar to the Lac-proteins, indicating a relation between translation inhibition and mRNA degradation as a response to antisense PNA treatment. Conclusion The results show that antisense mediated repression of genes within operons affect cotranscribed genes to a variable degree. Target transcript stability appears to be closely related to inhibition of translation and presumably depends on translating ribosomes protecting the mRNA from intrinsic decay mechanisms. Therefore, for genes within operons and clusters it is likely that the nature of the target transcript will determine the inhibitory effects on cotranscribed genes

  4. 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.

  5. Regulatory Interactions of Csr Components: the RNA Binding Protein CsrA Activates csrB Transcription in Escherichia coli

    OpenAIRE

    Gudapaty, Seshagirirao; Suzuki, Kazushi; Wang, Xin; Babitzke, Paul; Romeo, Tony

    2001-01-01

    The global regulator CsrA (carbon storage regulator) of Escherichia coli is a small RNA binding protein that represses various metabolic pathways and processes that are induced in the stationary phase of growth, while it activates certain exponential phase functions. Both repression and activation by CsrA involve posttranscriptional mechanisms, in which CsrA binding to mRNA leads to decreased or increased transcript stability, respectively. CsrA also binds to a small untranslated RNA, CsrB, f...

  6. A Hexose Transporter Homologue Controls Glucose Repression in the Methylotrophic Yeast Hansenula polymorpha

    NARCIS (Netherlands)

    Stasyk, Oleh V.; Stasyk, Olena G.; Komduur, Janet; Veenhuis, Marten; Cregg, James M.; Sibirny, Andrei A.

    2004-01-01

    Peroxisome biogenesis and synthesis of peroxisomal enzymes in the methylotrophic yeast Hansenula polymorpha are under the strict control of glucose repression. We identified an H. polymorpha glucose catabolite repression gene (HpGCR1) that encodes a hexose transporter homologue. Deficiency in GCR1 l

  7. The Homeodomain Protein CDP Regulates Mammary-Specific Gene Transcription and Tumorigenesis

    OpenAIRE

    Zhu, Quan; Maitra, Urmila; Johnston, Dennis; Lozano, Mary; Dudley, Jaquelin P.

    2004-01-01

    The CCAAT-displacement protein (CDP) has been implicated in developmental and cell-type-specific regulation of many cellular and viral genes. We previously have shown that CDP represses mouse mammary tumor virus (MMTV) transcription in tissue culture cells. Since CDP-binding activity for the MMTV long terminal repeat declines during mammary development, we tested whether binding mutations could alter viral expression. Infection of mice with MMTV proviruses containing CDP binding site mutation...

  8. DREAM Controls the On/Off Switch of Specific Activity-Dependent Transcription Pathways

    OpenAIRE

    Mellstr??m, Britt; Sah??n, Ignasi; Ruiz Nu??o, Ana; Murtra, Patricia; G??mez Villafuertes, Rosa; Savignac, Magal??; Oliveros, Juan C.; Gonz??lez, Paz; Kastanauskaite, Asta; Knafo, Shira; Zhuo, Min; Higuera Matas, Alejandro; Errington, Michael L.; Maldonado, Rafael; De Felipe, Javier

    2014-01-01

    Changes in nuclear Ca(2+) homeostasis activate specific gene expression programs and are central to the acquisition and storage of information in the brain. DREAM (downstream regulatory element antagonist modulator), also known as calsenilin/KChIP-3 (K(+) channel interacting protein 3), is a Ca(2+)-binding protein that binds DNA and represses transcription in a Ca(2+)-dependent manner. To study the function of DREAM in the brain, we used transgenic mice expressing a Ca(2+)-insensitive/CREB-in...

  9. A chromatin activity based chemoproteomic approach reveals a transcriptional repressome for gene-specific silencing

    OpenAIRE

    Liu, Cui; Yu, Yanbao; Liu, Feng; Wei, Xin; Wrobel, John A; Gunawardena, Harsha P.; Zhou, Li; Jin, Jian; Chen, Xian

    2014-01-01

    Immune cells develop endotoxin tolerance (ET) after prolonged stimulation. ET increases the level of a repression mark H3K9me2 in the transcriptional-silent chromatin specifically associated with pro-inflammatory genes. However, it is not clear what proteins are functionally involved in this process. Here we show that a novel chromatin activity based chemoproteomic (ChaC) approach can dissect the functional chromatin protein complexes that regulate ET-associated inflammation. Using UNC0638 th...

  10. Chromatin disruption in the promoter of Bovine Leukemia Virus during transcriptional activation

    OpenAIRE

    Colin, Laurence; Dekoninck, Ann; Reichert, Michal; Calao, Miriam; Merimi, Makram; Van den Broeke, Anne; Vierendeel, Valérie; Cleuter, Yvette; Burny, Arsène; Rohr, Olivier; Van Lint, Carine

    2011-01-01

    Bovine leukemia virus expression relies on its chromatin organization after integration into the host cell genome. Proviral latency, which results from transcriptional repression in vivo, represents a viral strategy to escape the host immune system and likely allows for tumor progression. Here, we discriminated two types of latency: an easily reactivable latent state of the YR2 provirus and a ‘locked’ latent state of the L267 provirus. The defective YR2 provirus was characterized by the prese...

  11. Indolmycin-mediated inhibition and stimulation of transcription at the trp promoter of Escherichia coli.

    OpenAIRE

    Bogosian, G; Haydock, P V; Somerville, R L

    1983-01-01

    Escherichia coli cells harboring a non-attenuated trp-lac operon fusion were used to evaluate the effects of indolmycin on the initiation of transcription at the trp promoter. Indolmycin caused repression in trpR+ strains and in trpR deletion mutants, although higher effector concentrations were required in the latter situation. Plasmid-mediated elevation in tryptophanyl-tRNA synthetase reversed the inhibitory effect of indolmycin. Indolmycin did not facilitate the binding of purified Trp rep...

  12. From an electrophoretic mobility shift assay to isolated transcription factors: a fast genomic-proteomic approach

    Directory of Open Access Journals (Sweden)

    Mechtler Karl

    2010-11-01

    Full Text Available Abstract Background Hypocrea jecorina (anamorph Trichoderma reesei is a filamentous ascomycete of industrial importance due to its hydrolases (e.g., xylanases and cellulases. The regulation of gene expression can influence the composition of the hydrolase cocktail, and thus, transcription factors are a major target of current research. Here, we design an approach for identifying a repressor of a xylanase-encoding gene. Results We used streptavidin affinity chromatography to isolate the Xylanase promoter-binding protein 1 (Xpp1. The optimal conditions and templates for the chromatography step were chosen according to the results of an electrophoretic mobility shift assay performed under repressing conditions, which yielded a DNA-protein complex specific to the AGAA-box (the previously identified, tetranucleotide cis-acting element. After isolating AGAA-box binding proteins, the eluted proteins were identified with Nano-HPLC/tandem MS-coupled detection. We compared the identified peptides to sequences in the H. jecorina genome and predicted in silico the function and DNA-binding ability of the identified proteins. With the results from these analyses, we eliminated all but three candidate proteins. We verified the transcription of these candidates and tested their ability to specifically bind the AGAA-box. In the end, only one candidate protein remained. We generated this protein with in vitro translation and used an EMSA to demonstrate the existence of an AGAA-box-specific protein-DNA complex. We found that the expression of this gene is elevated under repressing conditions relative to de-repressing or inducing conditions. Conclusions We identified a putative transcription factor that is potentially involved in repressing xylanase 2 expression. We also identified two additional potential regulatory proteins that bind to the xyn2 promoter. Thus, we succeeded in identifying novel, putative transcription factors for the regulation of xylanase

  13. Transcription Factors Foxi3 and Sox2 in the Regulation of Tooth Development

    OpenAIRE

    Jussila, Maria

    2014-01-01

    Teeth are ectodermal organs, which form from the embryonic epithelium and mesenchyme. Reciprocal interactions between these two tissues, regulated by the conserved signaling pathways, guide tooth morphogenesis. Activity of each signaling pathway is mediated by transcription factors, which activate or repress target genes of the pathway. During morphogenesis, the shape of the dental epithelium undergoes dramatic changes as it proceeds though placode, bud, and cap stages, finally forming the sh...

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

    Directory of Open Access Journals (Sweden)

    Nobuo Sakata

    2014-01-01

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

  15. Pax4 is not essential for beta-cell differentiation in zebrafish embryos but modulates alpha-cell generation by repressing arx gene expression

    Directory of Open Access Journals (Sweden)

    Djiotsa Joachim

    2012-12-01

    Full Text Available Abstract Background Genetic studies in mouse have demonstrated the crucial function of PAX4 in pancreatic cell differentiation. This transcription factor specifies β- and δ-cell fate at the expense of α-cell identity by repressing Arx gene expression and ectopic expression of PAX4 in α-cells is sufficient to convert them into β-cells. Surprisingly, no Pax4 orthologous gene can be found in chicken and Xenopus tropicalis raising the question of the function of pax4 gene in lower vertebrates such as in fish. In the present study, we have analyzed the expression and the function of the orthologous pax4 gene in zebrafish. Results pax4 gene is transiently expressed in the pancreas of zebrafish embryos and is mostly restricted to endocrine precursors as well as to some differentiating δ- and ε-cells but was not detected in differentiating β-cells. pax4 knock-down in zebrafish embryos caused a significant increase in α-cells number while having no apparent effect on β- and δ-cell differentiation. This rise of α-cells is due to an up-regulation of the Arx transcription factor. Conversely, knock-down of arx caused to a complete loss of α-cells and a concomitant increase of pax4 expression but had no effect on the number of β- and δ-cells. In addition to the mutual repression between Arx and Pax4, these two transcription factors negatively regulate the transcription of their own gene. Interestingly, disruption of pax4 RNA splicing or of arx RNA splicing by morpholinos targeting exon-intron junction sites caused a blockage of the altered transcripts in cell nuclei allowing an easy characterization of the arx- and pax4-deficient cells. Such analyses demonstrated that arx knock-down in zebrafish does not lead to a switch of cell fate, as reported in mouse, but rather blocks the cells in their differentiation process towards α-cells. Conclusions In zebrafish, pax4 is not required for the generation of the first β- and δ-cells deriving from

  16. The Role of S P2, SP3 AND SP4 in The Transcriptional Regulation of The Promoter of Nuclear Encoded Mitochondrial Genes

    International Nuclear Information System (INIS)

    The GC-box is an important transcriptional regulatory element present in the promoters of many mammalian genes, and is found in most, if not all, oxidative phosphorylation (OXPHOS) promoters. In the present study we examine the effects of three Spl family members (Sp2, Sp3, and Sp4) on the adenine nucleotide translocase 2, cytochrome cl, Fl-ATPase β-subunit, and the mitochondria transcription factor (mtTFA) promoters in Drosophila SL2 cell line. Sp3, like Spl, strongly activates transcription all four promoters. SP4 stimulates, moderately, but Sp2 had no effect. In addition, Sp3 can, like Spl, inhibit transcription from the proximal promoter of the ANT2 gene through binding to the Cbox GC element. By contrast, Sp4 and Sp2 do not repress promoter activity. Furthermore, since Sp4 and Sp2 bind to the Cbox repression element on the ANT2 promoter, but do not repress transcription, inhibition of transcription cannot be explained by steric hindrance of pre-initiation complex assembly. These data suggest that different Spl family members differentially affect transcription from the OXPHOS promoters.

  17. Serum repressing efflux pump CDR1 in Candida albicans

    Directory of Open Access Journals (Sweden)

    Fan Jen-Chung

    2006-07-01

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

  18. Plant transcription factors.

    Science.gov (United States)

    Meshi, T; Iwabuchi, M

    1995-12-01

    Transcriptional regulation of gene expression relies on the recognition of promoter elements by transcription factors. In the past several years, a considerable number of (putative) transcription factors have been identified in plants. Some genes coding for these factors were isolated by south-western screening with oligonucleotides as a probe or by homology-based screening, and others were initially isolated by genetic means and subsequently identified as the genes for transcription factors. These transcription factors often form families of structurally related proteins with similar DNA-binding specificities and in addition, they are sometimes involved in related phenomena. Some groups of factors homo- and/or heterodimerize to increase the length and variability of the target sequences. Transcriptional activators, in general, comprise a modular activation domain. The activities of the transcription factors are controlled by post-translational modification, like phosphorylation and glycosylation, as well as at the levels of nuclear transport, oligomerization, etc. In this review, we will summarize the current knowledge of plant transcription factors to help understand the mechanistic aspects of the transcriptional regulation of genes. PMID:8589926

  19. Transcriptional regulation of the human ALDH1A1 promoter by the oncogenic homeoprotein TLX1/HOX11

    Directory of Open Access Journals (Sweden)

    Kim Rice

    2009-08-01

    Full Text Available The homeoprotein TLX1, which is essential to spleen organogenesis and oncogenic when aberrantly expressed in immature T cells, functions as a bifunctional transcriptional regulator, being capable of activation or repression depending on cell type and/or promoter context. However, the detailed mechanisms by which it regulates the transcription of target genes such as ALDH1A1 remains to be elucidated. We therefore functionally assessed the ability of TLX1 to regulate ALDH1A1 expression in two hematopoietic cell lines, PER-117 T-leukemic cells and human erythroleukemic (HEL cells, by use of luciferase reporter and mobility shift assays. We showed that TLX1 physically interacts with the general transcription factor TFIIB via its homeodomain, and identified two activities in respect to TLX1-mediated regulation of the CCAAT box-containing ALDH1A1 promoter. The first involved CCAAT-dependent transcriptional repression via perturbation of GATA factor-containing protein complexes assembled at a non-canonical TATA (GATA box. A structurally intact homeodomain was essential for repression by TLX1 although direct DNA binding was not required. The second activity, which involved CCAAT-independent transcriptional activation did not require an intact homeodomain, indicating that the activation and repression functions of TLX1 are distinct. These findings confirm ALDH1A1 gene regulation by TLX1 and support an indirect model for TLX1 function, in which protein-protein interactions, rather than DNA binding at specific sites, are crucial for its transcriptional activity.

  20. Cooperative binding of transcription factors promotes bimodal gene expression response.

    Directory of Open Access Journals (Sweden)

    Pablo S Gutierrez

    Full Text Available In the present work we extend and analyze the scope of our recently proposed stochastic model for transcriptional regulation, which considers an arbitrarily complex cis-regulatory system using only elementary reactions. Previously, we determined the role of cooperativity on the intrinsic fluctuations of gene expression for activating transcriptional switches, by means of master equation formalism and computer simulation. This model allowed us to distinguish between two cooperative binding mechanisms and, even though the mean expression levels were not affected differently by the acting mechanism, we showed that the associated fluctuations were different. In the present generalized model we include other regulatory functions in addition to those associated to an activator switch. Namely, we introduce repressive regulatory functions and two theoretical mechanisms that account for the biphasic response that some cis-regulatory systems show to the transcription factor concentration. We have also extended our previous master equation formalism in order to include protein production by stochastic translation of mRNA. Furthermore, we examine the graded/binary scenarios in the context of the interaction energy between transcription factors. In this sense, this is the first report to show that the cooperative binding of transcription factors to DNA promotes the "all-or-none" phenomenon observed in eukaryotic systems. In addition, we confirm that gene expression fluctuation levels associated with one of two cooperative binding mechanism never exceed the fluctuation levels of the other.

  1. A protein thermometer controls temperature-dependent transcription of flagellar motility genes in Listeria monocytogenes.

    Directory of Open Access Journals (Sweden)

    Heather D Kamp

    2011-08-01

    Full Text Available Facultative bacterial pathogens must adapt to multiple stimuli to persist in the environment or establish infection within a host. Temperature is often utilized as a signal to control expression of virulence genes necessary for infection or genes required for persistence in the environment. However, very little is known about the molecular mechanisms that allow bacteria to adapt and respond to temperature fluctuations. Listeria monocytogenes (Lm is a food-borne, facultative intracellular pathogen that uses flagellar motility to survive in the extracellular environment and to enhance initial invasion of host cells during infection. Upon entering the host, Lm represses transcription of flagellar motility genes in response to mammalian physiological temperature (37°C with a concomitant temperature-dependent up-regulation of virulence genes. We previously determined that down-regulation of flagellar motility is required for virulence and is governed by the reciprocal activities of the MogR transcriptional repressor and the bifunctional flagellar anti-repressor/glycosyltransferase, GmaR. In this study, we determined that GmaR is also a protein thermometer that controls temperature-dependent transcription of flagellar motility genes. Two-hybrid and gel mobility shift analyses indicated that the interaction between MogR and GmaR is temperature sensitive. Using circular dichroism and limited proteolysis, we determined that GmaR undergoes a temperature-dependent conformational change as temperature is elevated. Quantitative analysis of GmaR in Lm revealed that GmaR is degraded in the absence of MogR and at 37°C (when the MogR:GmaR complex is less stable. Since MogR represses transcription of all flagellar motility genes, including transcription of gmaR, changes in the stability of the MogR:GmaR anti-repression complex, due to conformational changes in GmaR, mediates repression or de-repression of flagellar motility genes in Lm. Thus, GmaR functions as

  2. DAF-16 and TCER-1 Facilitate Adaptation to Germline Loss by Restoring Lipid Homeostasis and Repressing Reproductive Physiology in C. elegans

    Science.gov (United States)

    Amrit, Francis Raj Gandhi; Steenkiste, Elizabeth Marie; Ratnappan, Ramesh; Chen, Shaw-Wen; McClendon, T. Brooke; Kostka, Dennis; Yanowitz, Judith; Olsen, Carissa Perez; Ghazi, Arjumand

    2016-01-01

    Elimination of the proliferating germline extends lifespan in C. elegans. This phenomenon provides a unique platform to understand how complex metazoans retain metabolic homeostasis when challenged with major physiological perturbations. Here, we demonstrate that two conserved transcription regulators essential for the longevity of germline-less adults, DAF-16/FOXO3A and TCER-1/TCERG1, concurrently enhance the expression of multiple genes involved in lipid synthesis and breakdown, and that both gene classes promote longevity. Lipidomic analyses revealed that key lipogenic processes, including de novo fatty acid synthesis, triglyceride production, desaturation and elongation, are augmented upon germline removal. Our data suggest that lipid anabolic and catabolic pathways are coordinately augmented in response to germline loss, and this metabolic shift helps preserve lipid homeostasis. DAF-16 and TCER-1 also perform essential inhibitory functions in germline-ablated animals. TCER-1 inhibits the somatic gene-expression program that facilitates reproduction and represses anti-longevity genes, whereas DAF-16 impedes ribosome biogenesis. Additionally, we discovered that TCER-1 is critical for optimal fertility in normal adults, suggesting that the protein acts as a switch supporting reproductive fitness or longevity depending on the presence or absence of the germline. Collectively, our data offer insights into how organisms adapt to changes in reproductive status, by utilizing the activating and repressive functions of transcription factors and coordinating fat production and degradation. PMID:26862916

  3. The interplay between the master transcription factor PU.1 and miR-424 regulates human monocyte/macrophage differentiation

    OpenAIRE

    Rosa, A.; Ballarino, M.; Sorrentino, A; Sthandier, O.; De Angelis, F. G.; Marchioni, M; Masella, B; Guarini, A.; Fatica, A.; Peschle, C; Bozzoni, I

    2007-01-01

    We describe a pathway by which the master transcription factor PU.1 regulates human monocyte/macrophage differentiation. This includes miR-424 and the transcriptional factor NFI-A. We show that PU.1 and these two components are interlinked in a finely tuned temporal and regulatory circuitry: PU.1 activates the transcription of miR-424, and this up-regulation is involved in stimulating monocyte differentiation through miR-424-dependent translational repression of NFI-A. In turn, the decrease i...

  4. c-Maf Interacts with c-Myb To Regulate Transcription of an Early Myeloid Gene during Differentiation

    OpenAIRE

    Hegde, Shrikanth P.; Kumar, Alok; Kurschner, Cornelia; Shapiro, Linda H.

    1998-01-01

    The MafB transcriptional activator plays a pivotal role in regulating lineage-specific gene expression during hematopoiesis by repressing Ets-1-mediated transcription of key erythroid-specific genes in myeloid cells. To determine the effects of Maf family proteins on the transactivation of myeloid-specific genes in myeloid cells, we tested the ability of c-Maf to influence Ets-1- and c-Myb-dependent CD13/APN transcription. Expression of c-Maf in human immature myeloblastic cells inhibited CD1...

  5. Differential regulation by iron of regA and toxA transcript accumulation in Pseudomonas aeruginosa.

    OpenAIRE

    Frank, D W; Storey, D G; Hindahl, M S; Iglewski, B H

    1989-01-01

    Iron regulation of toxA and regA transcript accumulation was examined in Pseudomonas aeruginosa PA103 containing the regA gene on a multicopy plasmid. The patterns of transcript accumulation for toxA and regA were found to be positively correlated. Dot blot and Northern (RNA) blot analysis of total RNA isolated throughout the bacterial growth cycle indicated that multiple copies of the regA gene uncoupled iron repression of the first phase of transcript accumulation for both regA and toxA gen...

  6. FOXP3 Inhibits HIV-1 Infection of CD4 T-cells via Inhibition of LTR Transcriptional Activity

    OpenAIRE

    Selliah, Nithianandan; Zhang, Mingce; White, Sara; Zoltick, Philip; Sawaya, Bassel E.; Finkel, Terri H.; Cron, Randy Q

    2008-01-01

    FOXP3 is a necessary transcription factor for the development and function of CD4+ regulatory T-cells (Tregs). The role of Tregs in HIV-1 infection remains unclear. Here, we show expression of FOXP3 in primary human CD4 T-cells significantly inhibits HIV-1 infection. Since FOXP3 inhibits NFAT activity, and NFAT proteins contribute to HIV-1 transcription, we explore a transcriptional repressive function of HIV-1 LTR by FOXP3. Over-expression of FOXP3 in primary CD4 T-cells inhibits wild-type H...

  7. Temporal Control of Plant Organ Growth by TCP Transcription Factors.

    Science.gov (United States)

    Huang, Tengbo; Irish, Vivian F

    2015-06-29

    The Arabidopsis petal is a simple laminar organ whose development is largely impervious to environmental effects, making it an excellent model for dissecting the regulation of cell-cycle progression and post-mitotic cell expansion that together sculpt organ form. Arabidopsis petals grow via basipetal waves of cell division, followed by a phase of cell expansion. RABBIT EARS (RBE) encodes a C2H2 zinc finger transcriptional repressor and is required for petal development. During the early phase of petal initiation, RBE regulates a microRNA164-dependent pathway that controls cell proliferation at the petal primordium boundaries. The effects of rbe mutations on petal lamina growth suggest that RBE is also required to regulate later developmental events during petal organogenesis. Here, we demonstrate that, early in petal development, RBE represses the transcription of a suite of CIN-TCP genes that in turn act to inhibit the number and duration of cell divisions; the temporal alleviation of that repression results in the transition from cell division to post-mitotic cell expansion and concomitant petal maturation. PMID:26073137

  8. Acute Genome-wide effects of Rosiglitazone on PPARγ transcriptional networks in Adipocytes

    DEFF Research Database (Denmark)

    Haakonsson, Anders Kristian; Madsen, Maria Stahl; Nielsen, Ronni;

    2013-01-01

    on the transcriptional network of PPARγ in adipocytes. Treatment with rosiglitazone for 1 hour leads to acute transcriptional activation as well as repression of a number of genes as determined by genome-wide RNA polymerase II occupancy. Unlike what has been shown for many other nuclear receptors......, agonist treatment does not lead to major changes in the occurrence of PPARγ binding sites. However, rosiglitazone promotes PPARγ occupancy at many preexisting sites, and this is paralleled by increased occupancy of the mediator subunit MED1. The increase in PPARγ and MED1 binding is correlated with an...

  9. PDX1 Binds and Represses Hepatic Genes to Ensure Robust Pancreatic Commitment in Differentiating Human Embryonic Stem Cells

    Directory of Open Access Journals (Sweden)

    Adrian Kee Keong Teo

    2015-04-01

    Full Text Available Inactivation of the Pancreatic and Duodenal Homeobox 1 (PDX1 gene causes pancreatic agenesis, which places PDX1 high atop the regulatory network controlling development of this indispensable organ. However, little is known about the identity of PDX1 transcriptional targets. We simulated pancreatic development by differentiating human embryonic stem cells (hESCs into early pancreatic progenitors and subjected this cell population to PDX1 chromatin immunoprecipitation sequencing (ChIP-seq. We identified more than 350 genes bound by PDX1, whose expression was upregulated on day 17 of differentiation. This group included known PDX1 targets and many genes not previously linked to pancreatic development. ChIP-seq also revealed PDX1 occupancy at hepatic genes. We hypothesized that simultaneous PDX1-driven activation of pancreatic and repression of hepatic programs underlie early divergence between pancreas and liver. In HepG2 cells and differentiating hESCs, we found that PDX1 binds and suppresses expression of endogenous liver genes. These findings rebrand PDX1 as a context-dependent transcriptional repressor and activator within the same cell type.

  10. The Transcription Factor Encyclopedia

    DEFF Research Database (Denmark)

    Yusuf, Dimas; Butland, Stefanie L; Swanson, Magdalena I;

    2012-01-01

    ABSTRACT: Here we present the Transcription Factor Encyclopedia (TFe), a new web-based compendium of mini review articles on transcription factors (TFs) that is founded on the principles of open access and collaboration. Our consortium of over 100 researchers has collectively contributed over 130...

  11. Repression of Six3 by a corepressor regulates rhodopsin expression

    OpenAIRE

    Manavathi, Bramanandam; Peng, Shaohua; Rayala, Suresh K.; Talukder, Amjad H; Wang, Minhua H.; WANG, RUI-AN; Balasenthil, Seetharaman; Agarwal, Neeraj; Frishman, Laura J.; Kumar, Rakesh

    2007-01-01

    Here, we provide gain-of-function, loss-of function, and molecular evidence supporting genetic interactions between metastasis associated protein 1 (MTA1) and Six3 and between Six3 and rhodopsin. We discovered that MTA1 physically interacts with the Six3 chromatin in a histone deacetylase-dependent manner, leading to transcriptional suppression of the Six3 gene. MTA1 is also a Six3-interacting corepressor that contributes to a self-negative regulation of Six3 transcription by Six3. In contras...

  12. Stochastic de-repression of Rhodopsins in single photoreceptors of the fly retina.

    Directory of Open Access Journals (Sweden)

    Pranidhi Sood

    2012-02-01

    Full Text Available The photoreceptors of the Drosophila compound eye are a classical model for studying cell fate specification. Photoreceptors (PRs are organized in bundles of eight cells with two major types - inner PRs involved in color vision and outer PRs involved in motion detection. In wild type flies, most PRs express a single type of Rhodopsin (Rh: inner PRs express either Rh3, Rh4, Rh5 or Rh6 and outer PRs express Rh1. In outer PRs, the K(50 homeodomain protein Dve is a key repressor that acts to ensure exclusive Rh expression. Loss of Dve results in de-repression of Rhodopsins in outer PRs, and leads to a wide distribution of expression levels. To quantify these effects, we introduce an automated image analysis method to measure Rhodopsin levels at the single cell level in 3D confocal stacks. Our sensitive methodology reveals cell-specific differences in Rhodopsin distributions among the outer PRs, observed over a developmental time course. We show that Rhodopsin distributions are consistent with a two-state model of gene expression, in which cells can be in either high or basal states of Rhodopsin production. Our model identifies a significant role of post-transcriptional regulation in establishing the two distinct states. The timescale for interconversion between basal and high states is shown to be on the order of days. Our results indicate that even in the absence of Dve, the Rhodopsin regulatory network can maintain highly stable states. We propose that the role of Dve in outer PRs is to buffer against rare fluctuations in this network.

  13. Repression of the Auxin Response Pathway Increases Arabidopsis Susceptibility to Necrotrophic Fungi

    Institute of Scientific and Technical Information of China (English)

    Francisco Llorente; Paul Muskett; Andrea Sánchez-Vallet; Gemma López; Brisa Ramos; Clara Sánchez-Rodríguez; Lucia Jordá; Jane Parker; Antonio Molina

    2008-01-01

    In plants, resistance to necrotrophic pathogens depends on the interplay between different hormone systems, such as those regulated by salicylic acid (SA), jasmonic acid (JA), ethylene, and abscisic acid. Repression of auxin signaling by the SA pathway was recently shown to contribute to antibacterial resistance. Here, we demonstrate that Arabidopsis auxin signaling mutants axrl, axr2, and axr6 that have defects in the auxin-stimulated SCF (Skpl-Cullin-F-box) ubiquitination pathway exhibit increased susceptibility to the necrotrophic fungi Plectosphaerella cucumerina and Botrytis cinerea. Also, stabilization of the auxin transcriptional repressor AXR3 that is normally targeted for removal by the SCF-ubiquitin/proteasome machinery occurs upon P. cucumerina infection. Pharmacological inhibition of auxin transport or proteasome function each compromise necrotroph resistance of wild-type plants to a similar extent as in non-treated auxin response mutants. These results suggest that auxin signaling is important for resistance to the necrotrophic fungi P. cucumerina and B. cinerea. SGTlb (one of two Arabidopsis SGT1 genes encoding HSP90/HSC70 co-chaperones) promotes the functions of SCF E3-ubiquitin ligase complexes in auxin and JA responses and resistance conditioned by certain Resistance (R) genes to biotrophic pathogens. We find that sgtlb mutants are as resistant to P. cucumerina as wild-type plants. Conversely, auxin/SCF signaling mutants are uncompromised in RPP4-triggered resistance to the obligate biotrophic oomycete, Hyaloperonospora parasitica. Thus, the predominant action of SGTlb in R gene-conditioned resistance to oomycetes appears to be at a site other than assisting SCF E3-ubiquitin ligases. However, genetic additivity of sgtlb axr1 double mutants in susceptibility to H. parasitica suggests that SCF-mediated ubiquitination contributes to limiting biotrophic pathogen colonization once plant-pathogen compatibility is established.

  14. Membrane Association and Catabolite Repression of the Sulfolobus solfataricus α-Amylase

    Directory of Open Access Journals (Sweden)

    Edith Soo

    2015-09-01

    Full Text Available Sulfolobus solfataricus is a thermoacidophilic member of the archaea whose envelope consists of an ether-linked lipid monolayer surrounded by a protein S-layer. Protein translocation across this envelope must accommodate a steep proton gradient that is subject to temperature extremes. To better understand this process in vivo, studies were conducted on the S. solfataricus glycosyl hydrolyase family 57 α-Amylase (AmyA. Cell lines harboring site specific modifications of the amyA promoter and AmyA structural domains were created by gene replacement using markerless exchange and characterized by Western blot, enzyme assay and culture-based analysis. Fusion of amyA to the malAp promoter overcame amyAp-mediated regulatory responses to media composition including glucose and amino acid repression implicating action act at the level of transcription. Deletion of the AmyA Class II N-terminal signal peptide blocked protein secretion and intracellular protein accumulation. Deletion analysis of a conserved bipartite C-terminal motif consisting of a hydrophobic region followed by several charged residues indicated the charged residues played an essential role in membrane-association but not protein secretion. Mutants lacking the C-terminal bipartite motif exhibited reduced growth rates on starch as the sole carbon and energy source; therefore, association of AmyA with the membrane improves carbohydrate utilization. Widespread occurrence of this motif in other secreted proteins of S. solfataricus and of related Crenarchaeota suggests protein association with membranes is a general trait used by these organisms to influence external processes.

  15. Structure of noncoding RNA is a determinant of function of RNA binding proteins in transcriptional regulation

    Directory of Open Access Journals (Sweden)

    Oyoshi Takanori

    2012-01-01

    Full Text Available Abstract The majority of the noncoding regions of mammalian genomes have been found to be transcribed to generate noncoding RNAs (ncRNAs, resulting in intense interest in their biological roles. During the past decade, numerous ncRNAs and aptamers have been identified as regulators of transcription. 6S RNA, first described as a ncRNA in E. coli, mimics an open promoter structure, which has a large bulge with two hairpin/stalk structures that regulate transcription through interactions with RNA polymerase. B2 RNA, which has stem-loops and unstructured single-stranded regions, represses transcription of mRNA in response to various stresses, including heat shock in mouse cells. The interaction of TLS (translocated in liposarcoma with CBP/p300 was induced by ncRNAs that bind to TLS, and this in turn results in inhibition of CBP/p300 histone acetyltransferase (HAT activity in human cells. Transcription regulator EWS (Ewing's sarcoma, which is highly related to TLS, and TLS specifically bind to G-quadruplex structures in vitro. The carboxy terminus containing the Arg-Gly-Gly (RGG repeat domains in these proteins are necessary for cis-repression of transcription activation and HAT activity by the N-terminal glutamine-rich domain. Especially, the RGG domain in the carboxy terminus of EWS is important for the G-quadruplex specific binding. Together, these data suggest that functions of EWS and TLS are modulated by specific structures of ncRNAs.

  16. Operator Sequence Alters Gene Expression Independently of Transcription Factor Occupancy in Bacteria

    Directory of Open Access Journals (Sweden)

    Hernan G. Garcia

    2012-07-01

    Full Text Available A canonical quantitative view of transcriptional regulation holds that the only role of operator sequence is to set the probability of transcription factor binding, with operator occupancy determining the level of gene expression. In this work, we test this idea by characterizing repression in vivo and the binding of RNA polymerase in vitro in experiments where operators of various sequences were placed either upstream or downstream from the promoter in Escherichia coli. Surprisingly, we find that operators with a weaker binding affinity can yield higher repression levels than stronger operators. Repressor bound to upstream operators modulates promoter escape, and the magnitude of this modulation is not correlated with the repressor-operator binding affinity. This suggests that operator sequences may modulate transcription by altering the nature of the interaction of the bound transcription factor with the transcriptional machinery, implying a new layer of sequence dependence that must be confronted in the quantitative understanding of gene expression.

  17. Reversible Histone Acetylation Involved in Transcriptional Regulation of WT1 Gene

    Institute of Scientific and Technical Information of China (English)

    Yangguang SHAO; Jun LU; Cao CHENG; Liguo CUI; Guoping ZHANG; Baiqu HUANG

    2007-01-01

    To validate the involvement of reversible histone acetylation in the transcriptional regulation of human Wilms' tumor 1 gene (WT1), we analyzed the roles of histone deacetylases (HDACs) and histone acetyltransferase in this epigenetic process. Of the six HDACs (HDAC1-6) examined, HDAC4 and HDAC5 were found to have significant repressing effects on the activity of the WT1 reporter gene, as revealed by luciferase reporter assays and quantitative real-time reverse transcription-polymerase chain reaction assays.Luciferase reporter assays showed that the histone acetyltransferase p300 was able to counteract the HDAC4/HDAC5-mediated repression and that p300/CBP synergized with transcription factors Sp1, c-Myb, and Ets-1 in activation of the WT1 reporter. Chromatin immunoprecipitation experiments showed that p300 promotes the acetylation level of histone H3 at the WT1 intronic enhancer. Based on these data, we proposed a hypothetical model for the involvement of reversible histone acetylation in transcriptional regulation of the WT1 gene. This study provides further insight into the mechanisms of transcriptional regulation of the WT1 gene and WT1-associated diseases treatment.

  18. SUMOylation can regulate the activity of ETS-like transcription factor 4.

    Science.gov (United States)

    Kaikkonen, Sanna; Makkonen, Harri; Rytinki, Miia; Palvimo, Jorma J

    2010-08-01

    ETS-like transcription factor 4 (ELK4) (a.k.a. serum response factor accessory protein 1) belongs to the ternary complex factor (TCF) subfamily of E twenty-six (ETS) domain transcription factors. Compared to the other TCF subfamily members, ELK1 and ELK3 (NET), there is limited information of the mechanisms regulating the ELK4 activity. Here, we show that the ELK4 can be covalently modified (SUMOylated) by small ubiquitin-related modifier (SUMO) 1 protein, an important regulator of signaling and transcription. SUMOylation of ELK4 was reversed by SUMO-specific proteases (SENP) 1 and 2 and stimulated by SUMO E3 ligase PIAS3. Conserved lysine residue 167 that is located in the NET inhibitory domain of ELK4 was identified as the main site of SUMO-1 conjugation. Interestingly, mutation of the K167 disrupting the SUMOylation markedly enhanced the transcriptional activity of the ELK4, but weakened its repressive function on c-fos promoter. In conclusion, our results suggest that covalent modification by SUMO-1 can regulate the activity of ELK4, contributing to the transcriptional repression by the ELK4. PMID:20637912

  19. Regulating expression of cell and tissue-specific genes by modifying transcription

    Energy Technology Data Exchange (ETDEWEB)

    Beachy, Roger N; Dai, Shunhong

    2010-06-14

    Transcriptional regulation is the primary step to control gene expression, therefore function. Such regulation is achieved primarily via a combination of the activities of the promoter cis regulatory DNA elements and trans regulatory proteins that function through binding to these DNA elements. Rice bZIP transcription factors RF2a, RF2b and RLP1 play key roles in regulating the activity of a vascular tissue specific promoter isolated from Rice Tungro Bacilliform Virus (RTBV), through their interactions with the Box II essential cis element located in the promoter (Dai et al., 2006., Dai et al., 2004., Yin et al., 1997). RF2a, RF2b and RLP1 possess multiple regulatory domains. Functional characterization reveals that those domains can activate or repress the activity of the RTBV promoter. It is equally as important to recognize that these proteins control plant development by regulating differentiation and/or function of the vascular tissues. Studies of transcriptional regulation of the RTBV promoter by this group of bZIP proteins will not only provide insights about gene expression in the vascular tissue, but also insights about general mechanisms of transcription activation and repression. The knowledge gained from this research will also enable us to develop a well-described set of tools that can be used to control expression of multiple genes in transgenic plants. We have proposed characterize the function domains of RF2a, RF2b and RLP1 and explore the biological function of the transcription repressor RLP1.

  20. The Drosophila Translational Control Element (TCE) Is Required for High-Level Transcription of Many Genes That Are Specifically Expressed in Testes

    OpenAIRE

    Katzenberger, Rebeccah J.; Elizabeth A Rach; Ashley K Anderson; Uwe Ohler; Wassarman, David A.

    2012-01-01

    To investigate the importance of core promoter elements for tissue-specific transcription of RNA polymerase II genes, we examined testis-specific transcription in Drosophila melanogaster. Bioinformatic analyses of core promoter sequences from 190 genes that are specifically expressed in testes identified a 10 bp A/T-rich motif that is identical to the translational control element (TCE). The TCE functions in the 5' untranslated region of Mst(3)CGP mRNAs to repress translation, and it also fun...

  1. RamB, the Transcriptional Regulator of Acetate Metabolism in Corynebacterium glutamicum, Is Subject to Regulation by RamA and RamB▿

    OpenAIRE

    Cramer, Annette; Auchter, Marc; Frunzke, Julia; Bott, Michael; Eikmanns, Bernhard J.

    2006-01-01

    In Corynebacterium glutamicum, the transcriptional regulator RamB negatively controls the expression of genes involved in acetate metabolism. Here we show that RamB represses its own expression by direct interaction with a 13-bp motif in the ramB promoter region. Additionally, ramB expression is subject to carbon source-dependent positive control by RamA.

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

    Directory of Open Access Journals (Sweden)

    Muñoz Encinar, Laura

    2014-12-01

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

  3. Cytokine-induced megakaryocytic differentiation is regulated by genome-wide loss of a uSTAT transcriptional program.

    Science.gov (United States)

    Park, Hyun Jung; Li, Juan; Hannah, Rebecca; Biddie, Simon; Leal-Cervantes, Ana I; Kirschner, Kristina; Flores Santa Cruz, David; Sexl, Veronika; Göttgens, Berthold; Green, Anthony R

    2016-03-15

    Metazoan development is regulated by transcriptional networks, which must respond to extracellular cues including cytokines. The JAK/STAT pathway is a highly conserved regulatory module, activated by many cytokines, in which tyrosine-phosphorylated STATs (pSTATs) function as transcription factors. However, the mechanisms by which STAT activation modulates lineage-affiliated transcriptional programs are unclear. We demonstrate that in the absence of thrombopoietin (TPO), tyrosine-unphosphorylated STAT5 (uSTAT5) is present in the nucleus where it colocalizes with CTCF and represses a megakaryocytic transcriptional program. TPO-mediated phosphorylation of STAT5 triggers its genome-wide relocation to STAT consensus sites with two distinct transcriptional consequences, loss of a uSTAT5 program that restrains megakaryocytic differentiation and activation of a canonical pSTAT5-driven program which includes regulators of apoptosis and proliferation. Transcriptional repression by uSTAT5 reflects restricted access of the megakaryocytic transcription factor ERG to target genes. These results identify a previously unrecognized mechanism of cytokine-mediated differentiation. PMID:26702099

  4. Human Pumilio Proteins Recruit Multiple Deadenylases to Efficiently Repress Messenger RNAs*

    Science.gov (United States)

    Van Etten, Jamie; Schagat, Trista L.; Hrit, Joel; Weidmann, Chase A.; Brumbaugh, Justin; Coon, Joshua J.; Goldstrohm, Aaron C.

    2012-01-01

    PUF proteins are a conserved family of eukaryotic RNA-binding proteins that regulate specific mRNAs: they control many processes including stem cell proliferation, fertility, and memory formation. PUFs repress protein expression from their target mRNAs but the mechanism by which they do so remains unclear, especially for humans. Humans possess two PUF proteins, PUM1 and PUM2, which exhibit similar RNA binding specificities. Here we report new insights into their regulatory activities and mechanisms of action. We developed functional assays to measure sequence-specific repression by PUM1 and PUM2. Both robustly inhibit translation and promote mRNA degradation. Purified PUM complexes were found to contain subunits of the CCR4-NOT (CNOT) complex, which contains multiple enzymes that catalyze mRNA deadenylation. PUMs interact with the CNOT deadenylase subunits in vitro. We used three approaches to determine the importance of deadenylases for PUM repression. First, dominant-negative mutants of CNOT7 and CNOT8 reduced PUM repression. Second, RNA interference depletion of the deadenylases alleviated PUM repression. Third, the poly(A) tail was necessary for maximal PUM repression. These findings demonstrate a conserved mechanism of PUF-mediated repression via direct recruitment of the CCR4-POP2-NOT deadenylase leading to translational inhibition and mRNA degradation. A second, deadenylation independent mechanism was revealed by the finding that PUMs repress an mRNA that lacks a poly(A) tail. Thus, human PUMs are repressors capable of deadenylation-dependent and -independent modes of repression. PMID:22955276

  5. Human Pumilio proteins recruit multiple deadenylases to efficiently repress messenger RNAs.

    Science.gov (United States)

    Van Etten, Jamie; Schagat, Trista L; Hrit, Joel; Weidmann, Chase A; Brumbaugh, Justin; Coon, Joshua J; Goldstrohm, Aaron C

    2012-10-19

    PUF proteins are a conserved family of eukaryotic RNA-binding proteins that regulate specific mRNAs: they control many processes including stem cell proliferation, fertility, and memory formation. PUFs repress protein expression from their target mRNAs but the mechanism by which they do so remains unclear, especially for humans. Humans possess two PUF proteins, PUM1 and PUM2, which exhibit similar RNA binding specificities. Here we report new insights into their regulatory activities and mechanisms of action. We developed functional assays to measure sequence-specific repression by PUM1 and PUM2. Both robustly inhibit translation and promote mRNA degradation. Purified PUM complexes were found to contain subunits of the CCR4-NOT (CNOT) complex, which contains multiple enzymes that catalyze mRNA deadenylation. PUMs interact with the CNOT deadenylase subunits in vitro. We used three approaches to determine the importance of deadenylases for PUM repression. First, dominant-negative mutants of CNOT7 and CNOT8 reduced PUM repression. Second, RNA interference depletion of the deadenylases alleviated PUM repression. Third, the poly(A) tail was necessary for maximal PUM repression. These findings demonstrate a conserved mechanism of PUF-mediated repression via direct recruitment of the CCR4-POP2-NOT deadenylase leading to translational inhibition and mRNA degradation. A second, deadenylation independent mechanism was revealed by the finding that PUMs repress an mRNA that lacks a poly(A) tail. Thus, human PUMs are repressors capable of deadenylation-dependent and -independent modes of repression. PMID:22955276

  6. Controlling transcription in human pluripotent stem cells using CRISPR-effectors.

    Science.gov (United States)

    Genga, Ryan M; Kearns, Nicola A; Maehr, René

    2016-05-15

    The ability to manipulate transcription in human pluripotent stem cells (hPSCs) is fundamental for the discovery of key genes and mechanisms governing cellular state and differentiation. Recently developed CRISPR-effector systems provide a systematic approach to rapidly test gene function in mammalian cells, including hPSCs. In this review, we discuss recent advances in CRISPR-effector technologies that have been employed to control transcription through gene activation, gene repression, and epigenome engineering. We describe an application of CRISPR-effector mediated transcriptional regulation in hPSCs by targeting a synthetic promoter driving a GFP transgene, demonstrating the ease and effectiveness of CRISPR-effector mediated transcriptional regulation in hPSCs. PMID:26525193

  7. MART-10, a newly synthesized vitamin D analog, represses metastatic potential of head and neck squamous carcinoma cells

    Science.gov (United States)

    Yang, Shih-Wei; Tsai, Chi-Ying; Pan, Yi-Chun; Yeh, Chun-Nan; Pang, Jong-Hwei S; Takano, Masashi; Kittaka, Atsushi; Juang, Horng-Heng; Chen, Tai C; Chiang, Kun-Chun

    2016-01-01

    Even with multidisciplinary treatment, the prognosis and quality of life of patients diagnosed with head and neck squamous cell carcinoma (HNSCC) are still not satisfactory. Previously, 19-Nor-2α-(3-hydroxypropyl)-1α,25(OH)2D3 (MART-10), the new brand 1α,25(OH)2D3 analog, has been demonstrated to be an effective drug to inhibit HNSCC growth in vitro. Since most cancer patients die of metastasis, in this study, the antimetastatic effect of MART-10 on HNSCC was investigated. Our results reveal that both 1α,25(OH)2D3 and MART-10 effectively repressed the migration and invasion of HNSCC cells, with MART-10 being much more potent than 1α,25(OH)2D3. The antimetastatic effect of 1α,25(OH)2D3 and MART-10 was mediated by attenuation of epithelial–mesenchymal transition (EMT), which was supported by the finding that the expression of EMT-inducing transcriptional factors, Sail and Twist, was inhibited by 1α,25(OH)2D3 and MART-10. The upregulation of E-cadherin and downregulation of N-cadherin in FaDu cells induced by both drugs further confirmed the repression of EMT. In addition, 1α,25(OH)2D3 and MART-10 treatment inhibited intracellular MMP-9 expression and extracellular MMP activity in FaDu cells. Collectively, our results suggest that the less-calcemia 1α,25(OH)2D3 analog, MART-10, is a promising drug for HNSCC treatment. Further clinical studies are warranted.

  8. THE DYNAMICS OF REPRESSIVE HABITUS LAWS: ETHNOGRAPHIC CASE STUDY IN UNWIMA

    Directory of Open Access Journals (Sweden)

    Teddy Asmara

    2015-01-01

    Full Text Available This research describes repressive legal habitus Unwima community by focusing on the issue of why they create a legal cognition such manner and how to empower them in the public domain when facing a lawsuit in court and examination process in higher education office. The results of the research with ethnographic methods and interpretative analysis, First, that repressive legal habitus is a part of the neo-feudalistic thinking in education management. Second, the empowerment of repressive legal habitus in the public domain potentially generate a legal behavior of impulsive that tends to a manipulative, coercive, veiled, and other immorality practices.

  9. The Functions of MicroRNAs: mRNA Decay and Translational Repression.

    Science.gov (United States)

    Iwakawa, Hiro-oki; Tomari, Yukihide

    2015-11-01

    MicroRNAs (miRNAs) are a class of endogenous small noncoding RNAs, which regulate complementary mRNAs by inducing translational repression and mRNA decay. Although this dual repression system seems to operate in both animals and plants, genetic and biochemical studies suggest that the mechanism underlying the miRNA-mediated silencing is different in the two kingdoms. Here, we review the recent progress in our understanding of how miRNAs mediate translational repression and mRNA decay, and discuss the contributions of the two silencing modes to the overall silencing effect in both kingdoms. PMID:26437588

  10. The TCP4 transcription factor of Arabidopsis blocks cell division in yeast at G1 → S transition

    International Nuclear Information System (INIS)

    Highlights: → TCP4 is a class II TCP transcription factor, that represses cell division in Arabidopsis. → TCP4 expression in yeast retards cell division by blocking G1 → S transition. → Genome-wide expression studies and Western analysis reveals stabilization of cell cycle inhibitor Sic1, as possible mechanism. -- Abstract: The TCP transcription factors control important aspects of plant development. Members of class I TCP proteins promote cell cycle by regulating genes directly involved in cell proliferation. In contrast, members of class II TCP proteins repress cell division. While it has been postulated that class II proteins induce differentiation signal, their exact role on cell cycle has not been studied. Here, we report that TCP4, a class II TCP protein from Arabidopsis that repress cell proliferation in developing leaves, inhibits cell division by blocking G1 → S transition in budding yeast. Cells expressing TCP4 protein with increased transcriptional activity fail to progress beyond G1 phase. By analyzing global transcriptional status of these cells, we show that expression of a number of cell cycle genes is altered. The possible mechanism of G1 → S arrest is discussed.

  11. Effect of protein kinase C inhibitor (PKCI) on radiation sensitivity and c-fos transcription activity

    International Nuclear Information System (INIS)

    The human genetic disorder ataxia-telangiectasia (AT) is a multisystem disease characterized by extreme radiosensitivity. The recent identification of the gene mutated in AT, ATM, and the demonstration that it encodes a homologous domain of phosphatidylinositol 3-kinase (PI3-K), the catalytic subunit of an enzyme involved in transmitting signals from the cell surface to the nucleus, provide support for a role of this gene in signal transduction. Although ionizing radiation was known to induce c-fos transcription, nothing is known about how ATM or PKCI mediated signal transduction pathway modulates the c-fos gene transcription and gene expression. Here we have studied the effect of PKCI on radiation sensitivity and c-fos transcription in normal and AT cells. Normal (LM217) and AT (AT58IVA) cells were transfected with PKCI expression plasmid and the overexpression and integration of PKCI was evaluated by northern blotting and polymerase chain reaction, respectively. 5 Gy of radiation was exposed to LM and AT cells transfected with PKCI expression plasmid and cells were harvested 48 hours after radiation and investigated apoptosis with TUNEL method. The c-fos transcription activity was studied by performing CAT assay of reporter gene after transfection of c-fos CAT plasmid into AT and LM cells. Our results demonstrate for the first time a role of PKCI on. the radiation sensitivity and c-fos expression in LM and AT cells. PKCI increased radiation induced apoptosis in LM cells but reduced apoptosis in AT cells. The basal c-fos transcription activity is 70 times lower in AT cells than that in LM cells. The c-fos transcription activity was repressed by overexpression of PKCI in LM cells but not in AT cells. After induction of c-fos by Ras protein, overexpression of PKCI repressed c-fos transcription in LM cells but not in AT cells. Overexpression of PKCI increased radiation sensitivity and repressed c-fos transcription in LM cells but not in AT cells. The results may be a

  12. Farnesoid X Receptor Agonist Represses Cytochrome P450 2D6 Expression by Upregulating Small Heterodimer Partner.

    Science.gov (United States)

    Pan, Xian; Lee, Yoon-Kwang; Jeong, Hyunyoung

    2015-07-01

    Cytochrome P450 2D6 (CYP2D6) is a major drug-metabolizing enzyme responsible for eliminating approximately 20% of marketed drugs. Studies have shown that differential transcriptional regulation of CYP2D6 may contribute to large interindividual variability in CYP2D6-mediated drug metabolism. However, the factors governing CYP2D6 transcription are largely unknown. We previously demonstrated small heterodimer partner (SHP) as a novel transcriptional repressor of CYP2D6 expression. SHP is a representative target gene of the farnesoid X receptor (FXR). The objective of this study is to investigate whether an agonist of FXR, 3-(2,6-dichlorophenyl)-4-(3'-carboxy-2-chlorostilben-4-yl)oxymethyl-5-isopropylisoxazole (GW4064), alters CYP2D6 expression and activity. In CYP2D6-humanized transgenic mice, GW4064 decreased hepatic CYP2D6 expression and activity (by 2-fold) while increasing SHP expression (by 2-fold) and SHP recruitment to the CYP2D6 promoter. CYP2D6 repression by GW4064 was abrogated in Shp(-/-);CYP2D6 mice, indicating a critical role of SHP in CYP2D6 regulation by GW4064. Also, GW4064 decreased CYP2D6 expression (by 2-fold) in primary human hepatocytes, suggesting that the results obtained in CYP2D6-humanized transgenic mice can be translated to humans. This proof of concept study provides evidence for CYP2D6 regulation by an inducer of SHP expression, namely, the FXR agonist GW4064. PMID:25926433

  13. LATS2 Positively Regulates Polycomb Repressive Complex 2

    Science.gov (United States)

    Torigata, Kosuke; Daisuke, Okuzaki; Mukai, Satomi; Hatanaka, Akira; Ohka, Fumiharu; Motooka, Daisuke; Nakamura, Shota; Ohkawa, Yasuyuki; Yabuta, Norikazu; Kondo, Yutaka; Nojima, Hiroshi

    2016-01-01

    LATS2, a pivotal Ser/Thr kinase of the Hippo pathway, plays important roles in many biological processes. LATS2 also function in Hippo-independent pathway, including mitosis, DNA damage response and epithelial to mesenchymal transition. However, the physiological relevance and molecular basis of these LATS2 functions remain obscure. To understand novel functions of LATS2, we constructed a LATS2 knockout HeLa-S3 cell line using TAL-effector nuclease (TALEN). Integrated omics profiling of this cell line revealed that LATS2 knockout caused genome-wide downregulation of Polycomb repressive complex 2 (PRC2) and H3K27me3. Cell-cycle analysis revealed that downregulation of PRC2 was not due to cell cycle aberrations caused by LATS2 knockout. Not LATS1, a homolog of LATS2, but LATS2 bound PRC2 on chromatin and phosphorylated it. LATS2 positively regulates histone methyltransferase activity of PRC2 and their expression at both the mRNA and protein levels. Our findings reveal a novel signal upstream of PRC2, and provide insight into the crucial role of LATS2 in coordinating the epigenome through regulation of PRC2. PMID:27434182

  14. Superoxide dismutase during glucose repression of Hansenula polymorpha CBS 4732.

    Science.gov (United States)

    Hristozova, Tsonka; Rasheva, Tanya; Nedeva, Trayana; Kujumdzieva, Anna

    2002-01-01

    Hansenula polymorpha CBS 4732 was studied during cultivation on methanol and different glucose concentrations. Activities of Cu/Zn and Mn superoxide dismutase, catalase and methanol oxidase were investigated. During cultivation on methanol, increased superoxide dismutase and catalase activities and an induced methanol oxidase were achieved. Transfer of a methanol grown culture to medium with a high glucose concentration caused growth inhibition, low consumption of carbon, nitrogen and phosphate substrates, methanol oxidase inactivation as well as decrease of catalase activity (21.8 +/- 0.61 deltaE240 x min(-1) x mg protein(-1)). At the same time, a high value for superoxide dismutase enzyme was found (42.9 +/- 0.98 U x mg protein(-1), 25% of which was represented by Mn superoxide dismutase and 75% - by the Cu/Zn type). During derepression methanol oxidase was negligible (0.005 +/- 0.0001 U x mg protein(-1)), catalase tended to be the same as in the repressed culture, while superoxide dismutase activity increased considerably (63.67 +/- 1.72 U x mg protein(-1), 69% belonging to the Cu/Zn containing enzyme). Apparently, the cycle of growth inhibition and reactivation of Hansenula polymorpha CBS 4732 cells is strongly connected with the activity of the enzyme superoxide dismutase. PMID:12064733

  15. microRNAs- powerful repression comes from small RNAs

    Institute of Scientific and Technical Information of China (English)

    MA Cong; LIU YuFei; HE Lin

    2009-01-01

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

  16. microRNAs-powerful repression comes from small RNAs

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

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

  17. Floral Induction in Arabidopsis by FLOWERING LOCUS T Requires Direct Repression of BLADE-ON-PETIOLE Genes by the Homeodomain Protein PENNYWISE.

    Science.gov (United States)

    Andrés, Fernando; Romera-Branchat, Maida; Martínez-Gallegos, Rafael; Patel, Vipul; Schneeberger, Korbinian; Jang, Seonghoe; Altmüller, Janine; Nürnberg, Peter; Coupland, George

    2015-11-01

    Flowers form on the flanks of the shoot apical meristem (SAM) in response to environmental and endogenous cues. In Arabidopsis (Arabidopsis thaliana), the photoperiodic pathway acts through FLOWERING LOCUS T (FT) to promote floral induction in response to day length. A complex between FT and the basic leucine-zipper transcription factor FD is proposed to form in the SAM, leading to activation of APETALA1 and LEAFY and thereby promoting floral meristem identity. We identified mutations that suppress FT function and recovered a new allele of the homeodomain transcription factor PENNYWISE (PNY). Genetic and molecular analyses showed that ectopic expression of BLADE-ON-PETIOLE1 (BOP1) and BOP2, which encode transcriptional coactivators, in the SAM during vegetative development, confers the late flowering of pny mutants. In wild-type plants, BOP1 and BOP2 are expressed in lateral organs close to boundaries of the SAM, whereas in pny mutants, their expression occurs in the SAM. This ectopic expression lowers FD mRNA levels, reducing responsiveness to FT and impairing activation of APETALA1 and LEAFY. We show that PNY binds to the promoters of BOP1 and BOP2, repressing their transcription. These results demonstrate a direct role for PNY in defining the spatial expression patterns of boundary genes and the significance of this process for floral induction by FT. PMID:26417007

  18. A Central Role for JNK/AP-1 Pathway in the Pro-Oxidant Effect of Pyrrolidine Dithiocarbamate through Superoxide Dismutase 1 Gene Repression and Reactive Oxygen Species Generation in Hematopoietic Human Cancer Cell Line U937

    Science.gov (United States)

    Collin, Pascal; Lomri, Abderrahim

    2015-01-01

    Pyrrolidine dithiocarbamate (PDTC) known as antioxidant and specific inhibitor of NF-κB was also described as pro-oxidant by inducing cell death and reactive oxygen species (ROS) accumulation in cancer. However, the mechanism by which PDTC indices its pro-oxidant effect is unknown. Therefore, we aimed to evaluate the effect of PDTC on the human Cu/Zn superoxide dismutase 1 (SOD1) gene transcription in hematopoietic human cancer cell line U937. We herein show for the first time that PDTC decreases SOD1 transcripts, protein and promoter activity. Furthermore, SOD1 repression by PDTC was associated with an increase in oxidative stress as evidenced by ROS production. Electrophoretic mobility-shift assays (EMSA) show that PDTC increased binding of activating protein-1 (AP-1) in dose dependent-manner suggesting that the MAPkinase up-stream of AP-1 is involved. Ectopic NF-κB p65 subunit overexpression had no effect on SOD1 transcription. In contrast, in the presence of JNK inhibitor (SP600125), p65 induced a marked increase of SOD1 promoter, suggesting that JNK pathway is up-stream of NF-κB signaling and controls negatively its activity. Indeed, using JNK deficient cells, PDTC effect was not observed nether on SOD1 transcription or enzymatic activity, nor on ROS production. Finally, PDTC represses SOD1 in U937 cells through JNK/c-Jun phosphorylation. Taken together, these results suggest that PDTC acts as pro-oxidant compound in JNK/AP-1 dependent-manner by repressing the superoxide dismutase 1 gene leading to intracellular ROS accumulation. PMID:25996379

  19. Transcription regulation of AAC3 gene encoding hypoxic isoform of ADP/ATP carrier in Saccharomyces cerevisiae

    International Nuclear Information System (INIS)

    Two repressoric regions are present in the AAC3 promoter, termed URS1 and URS2. URS1 region is responsible for a carbon source-dependent regulation and plays a role under both, aerobic and anaerobic conditions. By deletion analysis URS1 was localized into the -322/-244 region and was found that the regulation is likely exerted by the repression by non-fermentable or non-repressing fermentable carbon sources than by the activation by repressing carbon source. By computer analysis cis sequences for two potential transcription factors, Rap1 and ERA, were identified within URS1. Rap1 binding into its consensus sequence was proved, effort to find the protein binding to the ERA cis regulatory sequences has failed. By the means of mutational analysis we revealed that the regulation pathway mediating the carbon source-dependent regulation via URS1 differs according to the presence or absence of oxygen in the growth medium. Under aerobic conditions the carbon source-dependent repression is mediated by the ERA factor and the role of Rap1 is only marginal. On the contrary, under anaerobic conditions, the repression is mediated solely by Rap1. AAC1 gene product might be involved in the regulation of the AAC3 gene, the regulation pathway has not been characterized yet. (author)

  20. Microphthalmia transcription factor regulates pancreatic β-cell function.

    Science.gov (United States)

    Mazur, Magdalena A; Winkler, Marcus; Ganic, Elvira; Colberg, Jesper K; Johansson, Jenny K; Bennet, Hedvig; Fex, Malin; Nuber, Ulrike A; Artner, Isabella

    2013-08-01

    Precise regulation of β-cell function is crucial for maintaining blood glucose homeostasis. Pax6 is an essential regulator of β-cell-specific factors like insulin and Glut2. Studies in the developing eye suggest that Pax6 interacts with Mitf to regulate pigment cell differentiation. Here, we show that Mitf, like Pax6, is expressed in all pancreatic endocrine cells during mouse postnatal development and in the adult islet. A Mitf loss-of-function mutation results in improved glucose tolerance and enhanced insulin secretion but no increase in β-cell mass in adult mice. Mutant β-cells secrete more insulin in response to glucose than wild-type cells, suggesting that Mitf is involved in regulating β-cell function. In fact, the transcription of genes critical for maintaining glucose homeostasis (insulin and Glut2) and β-cell formation and function (Pax4 and Pax6) is significantly upregulated in Mitf mutant islets. The increased Pax6 expression may cause the improved β-cell function observed in Mitf mutant animals, as it activates insulin and Glut2 transcription. Chromatin immunoprecipitation analysis shows that Mitf binds to Pax4 and Pax6 regulatory regions, suggesting that Mitf represses their transcription in wild-type β-cells. We demonstrate that Mitf directly regulates Pax6 transcription and controls β-cell function. PMID:23610061

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

    NARCIS (Netherlands)

    R. Braun; R. Vliegenthart

    2008-01-01

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

  2. Repressive coping style and autonomic reactions to two experimental stressors in healthy men and women.

    Science.gov (United States)

    Jørgensen, Michael Martini; Zachariae, Robert

    2006-04-01

    Autonomic and affective responses to two different stress tasks were measured in 45 males and 74 females, categorized as repressive, true low-anxious, true high-anxious, and defensive high-anxious. Electrodermal activity (EDA) was used as a measure of sympathetic activity and the high frequency (HF) spectral component of heart rate variability as a measure of parasympathetic activity. Contrary to our predictions, reactivity of repressors did not differ from the reactivity of true low-anxious participants. The results draw attention to previous inconsistent findings within the literature on repressive coping style and autonomic nervous system dysregulation. It is suggested that future research could benefit from the use of more consistent operationalizations of the repressive coping construct and from comparing alternative measures of repressive coping within the same study. PMID:16542356

  3. The Bach Family of Transcription Factors: A Comprehensive Review.

    Science.gov (United States)

    Zhou, Yin; Wu, Haijing; Zhao, Ming; Chang, Christopher; Lu, Qianjin

    2016-06-01

    The transcription factors Bach1 and Bach2, which belong to a basic region-leucine zipper (bZip) family, repress target gene expression by forming heterodimers with small Maf proteins. With the ability to bind to heme, Bach1 and Bach2 are important in maintaining heme homeostasis in response to oxidative stress, which is characterized by high levels of reactive oxygen species (ROS) in cells and thereby induces cellular damage and senescence. The inactivation of Bach1 exerts an antioxidant effect. Thus, Bach1 may be a potential therapeutic target of oxidative stress-related diseases. Bach2 participates in oxidative stress-mediated apoptosis and is involved in macrophage-mediated innate immunity as well as the adaptive immune response. Bach1 and Bach2 promote the differentiation of common lymphoid progenitors to B cells by repressing myeloid-related genes. Bach2 is able to regulate class-switch recombination and plasma cell differentiation by altering the concentration of mitochondrial ROS during B cell differentiation. Furthermore, Bach2 maintains T cell homeostasis, influences the function of macrophages, and plays a role in autoimmunity. Bach2-controlling genes with super enhancers in T cells play a key role in immune regulation. However, in spite of new research, the role of Bach1 and Bach2 in immune cells and immune response is not completely clear, nor are their respective roles of in oxidative stress and the immune response, in particular with regard to the clinical phenotypes of autoimmune diseases. The anti-immunosenescence action of Bach and the role of epigenetic modifications of these transcription factors may be important in the mechanism of Bach transcription factors in mediating oxidative stress and cellular immunity. PMID:27052415

  4. SIRT1 IS REQUIRED FOR ANTAGONIST-INDUCED TRANSCRIPTIONAL REPRESSION OF ANDROGEN-RESPONSIVE GENES BY THE ANDROGEN RECEPTOR

    OpenAIRE

    Dai, Yan; Ngo, Duyen; Forman, Lora W.; Qin, David C.; Jacob, Johanna; Faller, Douglas V

    2007-01-01

    Androgen antagonists or androgen deprivation is a primary therapeutic modality for the treatment of prostate cancer. Invariably, however, the disease becomes progressive and unresponsive to androgen ablation therapy (hormone refractory). The molecular mechanisms by which the androgen antagonists inhibit prostate cancer proliferation are not fully defined. In this report, we demonstrate that SIRT1, a nicotinamide adenosine dinucleotide-dependent histone deacetylase linked to the regulation of ...

  5. Transcriptional Repression of the Dspp Gene Leads to Dentinogenesis Imperfecta Phenotype in Col1a1-Trps1 Transgenic Mice

    OpenAIRE

    Napierala, Dobrawa; Sun, Yao; Maciejewska, Izabela; Bertin, Terry K.; Dawson, Brian; D'Souza, Rena; Qin, Chunlin; Lee, Brendan

    2012-01-01

    Dentinogenesis imperfecta (DGI) is a hereditary defect of dentin, a calcified tissue that is the most abundant component of teeth. Most commonly, DGI is manifested as a part of osteogenesis imperfecta (OI) or the phenotype is restricted to dental findings only. In the latter case, DGI is caused by mutations in the DSPP gene, which codes for dentin sialoprotein (DSP) and dentin phosphoprotein (DPP). Although these two proteins together constitute the majority of noncollagenous proteins of the ...

  6. Transcriptional repression of the APC/C activator CCS52A1 promotes active termination of cell growth

    OpenAIRE

    Breuer, Christian; Morohashi, Kengo; Kawamura, Ayako; Takahashi, Naoki; Ishida, Takashi; Umeda, Masaaki; Grotewold, Erich; Sugimoto, Keiko

    2012-01-01

    Spatial and temporal control of cell growth is central for the morphogenesis of multicellular organisms. For some cell types that undergo extensive post-mitotic cell growth, such as neurons and hair cells, orchestrating the extent of post-mitotic cell growth with development is vital for their physiology and function. Previous studies suggested that the extent of cell growth is linked with an increase in ploidy by endoreduplication but how developmental signals control endocycling and cell gr...

  7. Transcription Factor ATAF1 in Arabidopsis Promotes Senescence by Direct Regulation of Key Chloroplast Maintenance and Senescence Transcriptional Cascades.

    Science.gov (United States)

    Garapati, Prashanth; Xue, Gang-Ping; Munné-Bosch, Sergi; Balazadeh, Salma

    2015-07-01

    Senescence represents a fundamental process of late leaf development. Transcription factors (TFs) play an important role for expression reprogramming during senescence; however, the gene regulatory networks through which they exert their functions, and their physiological integration, are still largely unknown. Here, we identify the Arabidopsis (Arabidopsis thaliana) abscisic acid (ABA)- and hydrogen peroxide-activated TF Arabidopsis thaliana activating factor1 (ATAF1) as a novel upstream regulator of senescence. ATAF1 executes its physiological role by affecting both key chloroplast maintenance and senescence-promoting TFs, namely GOLDEN2-LIKE1 (GLK1) and ORESARA1 (Arabidopsis NAC092), respectively. Notably, while ATAF1 activates ORESARA1, it represses GLK1 expression by directly binding to their promoters, thereby generating a transcriptional output that shifts the physiological balance toward the progression of senescence. We furthermore demonstrate a key role of ATAF1 for ABA- and hydrogen peroxide-induced senescence, in accordance with a direct regulatory effect on ABA homeostasis genes, including nine-CIS-epoxycarotenoid dioxygenase3 involved in ABA biosynthesis and ABC transporter G family member40, encoding an ABA transport protein. Thus, ATAF1 serves as a core transcriptional activator of senescence by coupling stress-related signaling with photosynthesis- and senescence-related transcriptional cascades. PMID:25953103

  8. Teaching microbial physiology using glucose repression phenomenon in baker's yeast as an examplele

    DEFF Research Database (Denmark)

    Vijayendran, Raghavendran; Nielsen, Jens; Olsson, Lisbeth

    2005-01-01

    switching off the genes responsible for respiration even under aerobic conditions. This phenomenon is referred to as the Crabtree effect. The present review focuses on glucose repression in S. cerevisiae from a physiological perspective. Physiological studies presented involve batch and chemostat...... experiments of the wild type and a mutant that lacks a trait partially responsible for the fermentative behavior. Various undergraduate student exercises have been (and can be) formulated to illustrate the concept of glucose repression....

  9. THE TUG OF CONFESSION AND REPRESSION IN MICHEL FOUCAULT'S THE HISTORY OF SEXUALITY

    OpenAIRE

    Preeti Puri

    2014-01-01

    Michel Foucault, the magician of ideas has illuminated many shady areas of Western intellectual history. Throughout his career he kept returning to Freud and carved to formulate a counterproject to psychoanalysis. The focal point of the present paper is to figure out whether the contemporary man is actually repressed or a manifestation of confession as vouched by Michel Foucault. To delve into the binary opposition of repression/ confession the issues focused in the present paper ...

  10. Freud's 'thought-transference', repression, and the future of psychoanalysis.

    Science.gov (United States)

    Farrell, D

    1983-01-01

    Psychoanalysts since Freud have largely neglected his important, paradigmatic ideas on the possibility of 'thought-transference' (telepathy) as an influence in mental life. A chance recording of two dreams which proved to coincide in some detail with distant reality events again suggests evidence in favour of the telepathy hypothesis. On interpretation, one of these dreams reveals even greater correspondence with the reality event and shows the mechanism of transformation of the repressed wish from latent dream content into manifest dream, utilizing a number of elements of the dream instigator, an apparently telepathically received day residue. Working with this material proceeded against very strong resistance, most evident in repeated forgetting of one or another bit of the clinical data. This has been the fate of ideas pertaining to the occult since Freud's first formulations, as is documented here by references to the early history of psychoanalysis. The issue now and for the future is whether psychoanalysis will continue to ignore the crucial question of validity in regard to the telepathy hypothesis. The psychoanalytic method is uniquely qualified to investigate so-called parapsychological phenomena and has the same obligation to do so as with other mental events. We need to examine the evidence in spite of the threat posed to our conventional understanding of the limits of the mind by the very act of acknowledging the question. If we can overcome our resistance to undertaking this task, we may find that, once again, Freud pointed the way towards discovery of a new paradigm in science. PMID:6853049

  11. 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.

  12. Transcriptional programs controlling perinatal lung maturation.

    Directory of Open Access Journals (Sweden)

    Yan Xu

    Full Text Available The timing of lung maturation is controlled precisely by complex genetic and cellular programs. Lung immaturity following preterm birth frequently results in Respiratory Distress Syndrome (RDS and Broncho-Pulmonary Dysplasia (BPD, which are leading causes of mortality and morbidity in preterm infants. Mechanisms synchronizing gestational length and lung maturation remain to be elucidated. In this study, we designed a genome-wide mRNA expression time-course study from E15.5 to Postnatal Day 0 (PN0 using lung RNAs from C57BL/6J (B6 and A/J mice that differ in gestational length by ∼30 hr (B6transcriptional networks controlling lung maturation. We identified both temporal and strain dependent gene expression patterns during lung maturation. For time dependent changes, cell adhesion, vasculature development, and lipid metabolism/transport were major bioprocesses induced during the saccular stage of lung development at E16.5-E17.5. CEBPA, PPARG, VEGFA, CAV1 and CDH1 were found to be key signaling and transcriptional regulators of these processes. Innate defense/immune responses were induced at later gestational ages (E18.5-20.5, STAT1, AP1, and EGFR being important regulators of these responses. Expression of RNAs associated with the cell cycle and chromatin assembly was repressed during prenatal lung maturation and was regulated by FOXM1, PLK1, chromobox, and high mobility group families of transcription factors. Strain dependent lung mRNA expression differences peaked at E18.5. At this time, mRNAs regulating surfactant and innate immunity were more abundantly expressed in lungs of B6 (short gestation than in A/J (long gestation mice, while expression of genes involved in chromatin assembly and histone modification were expressed at lower levels in B6 than in A/J mice. The present study systemically mapped key regulators

  13. Phytochrome and retrograde signalling pathways converge to antagonistically regulate a light-induced transcriptional network

    Science.gov (United States)

    Martín, Guiomar; Leivar, Pablo; Ludevid, Dolores; Tepperman, James M.; Quail, Peter H.; Monte, Elena

    2016-01-01

    Plastid-to-nucleus retrograde signals emitted by dysfunctional chloroplasts impact photomorphogenic development, but the molecular link between retrograde- and photosensory-receptor signalling has remained unclear. Here, we show that the phytochrome and retrograde signalling (RS) pathways converge antagonistically to regulate the expression of the nuclear-encoded transcription factor GLK1, a key regulator of a light-induced transcriptional network central to photomorphogenesis. GLK1 gene transcription is directly repressed by PHYTOCHROME-INTERACTING FACTOR (PIF)-class bHLH transcription factors in darkness, but light-activated phytochrome reverses this activity, thereby inducing expression. Conversely, we show that retrograde signals repress this induction by a mechanism independent of PIF mediation. Collectively, our data indicate that light at moderate levels acts through the plant's nuclear-localized sensory-photoreceptor system to induce appropriate photomorphogenic development, but at excessive levels, sensed through the separate plastid-localized RS system, acts to suppress such development, thus providing a mechanism for protection against photo-oxidative damage by minimizing the tissue exposure to deleterious radiation. PMID:27150909

  14. Regulating expressin of cell and tissue-specific genes by modifying transcription

    Energy Technology Data Exchange (ETDEWEB)

    Beachy, R N; Dai, Shunhong

    2009-12-15

    Transcriptional regulation is the primary step to control gene expression, therefore function. Such regulation is achieved primarily via a combination of the activities of the promoter cis regulatory DNA elements and trans regulatory proteins that function through binding to these DNA elements. Our research supported by this program has led to the identification of rice bZIP transcription factors RF2a, RF2b and RLP1 that play key roles in regulating the activity of a vascular tissue specific promoter isolated from Rice Tungro Bacilliform Virus (RTBV) through their interactions with the Box II essential cis element located in the promoter. RF2a, RF2b and RLP1 possess multiple regulatory domains. Functional characterization reveals that those domains can activate or repress the activity of the RTBV promoter. Studies of transcriptional regulation of the RTBV promoter by this group of bZIP proteins not only provide insights about gene expression in the vascular tissue, but also insights about general mechanisms of transcription activation and repression. The knowledge gained from this research will also enable us to develop a well-described set of tools that can be used to control expression of multiple genes in transgenic plants and to improve biofuel feedstock.

  15. Tcf1 and Lef1 transcription factors establish CD8(+) T cell identity through intrinsic HDAC activity.

    Science.gov (United States)

    Xing, Shaojun; Li, Fengyin; Zeng, Zhouhao; Zhao, Yunjie; Yu, Shuyang; Shan, Qiang; Li, Yalan; Phillips, Farrah C; Maina, Peterson K; Qi, Hank H; Liu, Chengyu; Zhu, Jun; Pope, R Marshall; Musselman, Catherine A; Zeng, Chen; Peng, Weiqun; Xue, Hai-Hui

    2016-06-01

    The CD4(+) and CD8(+) T cell dichotomy is essential for effective cellular immunity. How individual T cell identity is established remains poorly understood. Here we show that the high-mobility group (HMG) transcription factors Tcf1 and Lef1 are essential for repressing CD4(+) lineage-associated genes including Cd4, Foxp3 and Rorc in CD8(+) T cells. Tcf1- and Lef1-deficient CD8(+) T cells exhibit histone hyperacetylation, which can be ascribed to intrinsic histone deacetylase (HDAC) activity in Tcf1 and Lef1. Mutation of five conserved amino acids in the Tcf1 HDAC domain diminishes HDAC activity and the ability to suppress CD4(+) lineage genes in CD8(+) T cells. These findings reveal that sequence-specific transcription factors can utilize intrinsic HDAC activity to guard cell identity by repressing lineage-inappropriate genes. PMID:27111144

  16. Sodium arsenite represses the expression of myogenin in C2C12 mouse myoblast cells through histone modifications and altered expression of Ezh2, Glp, and Igf-1

    International Nuclear Information System (INIS)

    Arsenic is a toxicant commonly found in water systems and chronic exposure can result in adverse developmental effects including increased neonatal death, stillbirths, and miscarriages, low birth weight, and altered locomotor activity. Previous studies indicate that 20 nM sodium arsenite exposure to C2C12 mouse myocyte cells delayed myoblast differentiation due to reduced myogenin expression, the transcription factor that differentiates myoblasts into myotubes. In this study, several mechanisms by which arsenic could alter myogenin expression were examined. Exposing differentiating C2C12 cells to 20 nM arsenic increased H3K9 dimethylation (H3K9me2) and H3K9 trimethylation (H3K9me3) by 3-fold near the transcription start site of myogenin, which is indicative of increased repressive marks, and reduced H3K9 acetylation (H3K9Ac) by 0.5-fold, indicative of reduced permissive marks. Protein expression of Glp or Ehmt1, a H3-K9 methyltransferase, was also increased by 1.6-fold in arsenic-exposed cells. In addition to the altered histone remodeling status on the myogenin promoter, protein and mRNA levels of Igf-1, a myogenic growth factor, were significantly repressed by arsenic exposure. Moreover, a 2-fold induction of Ezh2 expression, and an increased recruitment of Ezh2 (3.3-fold) and Dnmt3a (∼ 2-fold) to the myogenin promoter at the transcription start site (− 40 to + 42), were detected in the arsenic-treated cells. Together, we conclude that the repressed myogenin expression in arsenic-exposed C2C12 cells was likely due to a combination of reduced expression of Igf-1, enhanced nuclear expression and promoter recruitment of Ezh2, and altered histone remodeling status on myogenin promoter (− 40 to + 42). -- Highlights: ► Igf-1 expression is decreased in C2C12 cells after 20 nM arsenite exposure. ► Arsenic exposure alters histone remodeling on the myogenin promoter. ► Glp expression, a H3–K9 methyltransferase, was increased in arsenic-exposed cells. ► Ezh2

  17. Sodium arsenite represses the expression of myogenin in C2C12 mouse myoblast cells through histone modifications and altered expression of Ezh2, Glp, and Igf-1

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Gia-Ming [Environmental Toxicology Graduate Program, Clemson University, 132 Long Hall, Clemson, SC 29634 (United States); Present address: The University of Chicago, Section of Hematology/Oncology, 900 E. 57th Street, Room 7134, Chicago, IL 60637 (United States); Bain, Lisa J., E-mail: lbain@clemson.edu [Environmental Toxicology Graduate Program, Clemson University, 132 Long Hall, Clemson, SC 29634 (United States); Department of Biological Sciences, Clemson University, 132 Long Hall, Clemson, SC 29634 (United States)

    2012-05-01

    Arsenic is a toxicant commonly found in water systems and chronic exposure can result in adverse developmental effects including increased neonatal death, stillbirths, and miscarriages, low birth weight, and altered locomotor activity. Previous studies indicate that 20 nM sodium arsenite exposure to C2C12 mouse myocyte cells delayed myoblast differentiation due to reduced myogenin expression, the transcription factor that differentiates myoblasts into myotubes. In this study, several mechanisms by which arsenic could alter myogenin expression were examined. Exposing differentiating C2C12 cells to 20 nM arsenic increased H3K9 dimethylation (H3K9me2) and H3K9 trimethylation (H3K9me3) by 3-fold near the transcription start site of myogenin, which is indicative of increased repressive marks, and reduced H3K9 acetylation (H3K9Ac) by 0.5-fold, indicative of reduced permissive marks. Protein expression of Glp or Ehmt1, a H3-K9 methyltransferase, was also increased by 1.6-fold in arsenic-exposed cells. In addition to the altered histone remodeling status on the myogenin promoter, protein and mRNA levels of Igf-1, a myogenic growth factor, were significantly repressed by arsenic exposure. Moreover, a 2-fold induction of Ezh2 expression, and an increased recruitment of Ezh2 (3.3-fold) and Dnmt3a (∼ 2-fold) to the myogenin promoter at the transcription start site (− 40 to + 42), were detected in the arsenic-treated cells. Together, we conclude that the repressed myogenin expression in arsenic-exposed C2C12 cells was likely due to a combination of reduced expression of Igf-1, enhanced nuclear expression and promoter recruitment of Ezh2, and altered histone remodeling status on myogenin promoter (− 40 to + 42). -- Highlights: ► Igf-1 expression is decreased in C2C12 cells after 20 nM arsenite exposure. ► Arsenic exposure alters histone remodeling on the myogenin promoter. ► Glp expression, a H3–K9 methyltransferase, was increased in arsenic-exposed cells. ► Ezh2

  18. Genetic evidence that catabolites of the Entner-Doudoroff pathway signal C source repression of the sigma54 Pu promoter of Pseudomonas putida.

    Science.gov (United States)

    Velázquez, Francisco; di Bartolo, Ilaria; de Lorenzo, Víctor

    2004-12-01

    Glucose and other C sources exert an atypical form of catabolic repression on the sigma54-dependent promoter Pu, which drives transcription of an operon for m-xylene degradation encoded by the TOL plasmid pWW0 in Pseudomonas putida. We have used a genetic approach to identify the catabolite(s) shared by all known repressive C sources that appears to act as the intracellular signal that triggers downregulation of Pu. To this end, we reconstructed from genomic data the pathways for metabolism of repressor (glucose, gluconate) and nonrepressor (fructose) C sources. Since P. putida lacks fructose-6-phosphate kinase, glucose and gluconate appear to be metabolized exclusively by the Entner-Doudoroff (ED) pathway, while fructose can be channeled through the Embden-Meyerhof (EM) route. An insertion in the gene fda (encoding fructose-1,6-bisphosphatase) that forces fructose metabolism to be routed exclusively to the ED pathway makes this sugar inhibitory for Pu. On the contrary, a crc mutation known to stimulate expression of the ED enzymes causes the promoter to be less sensitive to glucose. Interrupting the ED pathway by knocking out eda (encoding 2-dehydro-3-deoxyphosphogluconate aldolase) exacerbates the inhibitory effect of glucose in Pu. These observations pinpoint the key catabolites of the ED route, 6-phosphogluconate and/or 2-dehydro-3-deoxyphosphogluconate, as the intermediates that signal Pu repression. This notion is strengthened by the observation that 2-ketogluconate, which enters the ED pathway by conversion into these compounds, is a strong repressor of the Pu promoter. PMID:15576775

  19. Computational prediction of the Crc regulon identifies genus-wide and species-specific targets of catabolite repression control in Pseudomonas bacteria

    LENUS (Irish Health Repository)

    Browne, Patrick

    2010-11-25

    Abstract Background Catabolite repression control (CRC) is an important global control system in Pseudomonas that fine tunes metabolism in order optimise growth and metabolism in a range of different environments. The mechanism of CRC in Pseudomonas spp. centres on the binding of a protein, Crc, to an A-rich motif on the 5\\' end of an mRNA resulting in translational down-regulation of target genes. Despite the identification of several Crc targets in Pseudomonas spp. the Crc regulon has remained largely unexplored. Results In order to predict direct targets of Crc, we used a bioinformatics approach based on detection of A-rich motifs near the initiation of translation of all protein-encoding genes in twelve fully sequenced Pseudomonas genomes. As expected, our data predict that genes related to the utilisation of less preferred nutrients, such as some carbohydrates, nitrogen sources and aromatic carbon compounds are targets of Crc. A general trend in this analysis is that the regulation of transporters is conserved across species whereas regulation of specific enzymatic steps or transcriptional activators are often conserved only within a species. Interestingly, some nucleoid associated proteins (NAPs) such as HU and IHF are predicted to be regulated by Crc. This finding indicates a possible role of Crc in indirect control over a subset of genes that depend on the DNA bending properties of NAPs for expression or repression. Finally, some virulence traits such as alginate and rhamnolipid production also appear to be regulated by Crc, which links nutritional status cues with the regulation of virulence traits. Conclusions Catabolite repression control regulates a broad spectrum of genes in Pseudomonas. Some targets are genus-wide and are typically related to central metabolism, whereas other targets are species-specific, or even unique to particular strains. Further study of these novel targets will enhance our understanding of how Pseudomonas bacteria integrate

  20. Resveratrol Protects against TNF-α-Induced Injury in Human Umbilical Endothelial Cells through Promoting Sirtuin-1-Induced Repression of NF-KB and p38 MAPK.

    Science.gov (United States)

    Pan, Wei; Yu, Huizhen; Huang, Shujie; Zhu, Pengli

    2016-01-01

    Inflammation and reactive oxygen species (ROS) play important roles in the pathogenesis of atherosclerosis. Resveratrol has been shown to possess anti-inflammatory and antioxidative stress activities, but the underlying mechanisms are not fully understood. In the present study, we investigated the molecular basis associated with the protective effects of resveratrol on tumor necrosis factor-alpha (TNF-α)-induced injury in human umbilical endothelial cells (HUVECs) using a variety of approaches including a cell viability assay, reverse transcription and quantitative polymerase chain reaction, western blot, and immunofluorescence staining. We showed that TNF-α induced CD40 expression and ROS production in cultured HUVECs, which were attenuated by resveratrol treatment. Also, resveratrol increased the expression of sirtuin 1 (SIRT1); and repression of SIRT1 by small-interfering RNA (siRNA) and the SIRT1 inhibitor Ex527 reduced the inhibitory effects of resveratrol on CD40 expression and ROS generation. In addition, resveratrol downregulated the levels of p65 and phospho-p38 MAPK, but this inhibitory effect was attenuated by the suppression of SIRT1 activity. Moreover, the p38 MAPK inhibitor SD203580 and the nuclear factor (NF)-κB inhibitor pyrrolidine dithiocarbamate (PDTC) achieved similar repressive effects as resveratrol on TNF-α-induced ROS generation and CD40 expression. Thus, our study provides a mechanistic link between resveratrol and the activation of SIRT1, the latter of which is involved in resveratrol-mediated repression of the p38 MAPK/NF-κB pathway and ROS production in TNF-α-treated HUVECs. PMID:26799794