scholarly journals Transcriptional control and the role of silencers in transcriptional regulation in eukaryotes

1998 ◽  
Vol 331 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Steven OGBOURNE ◽  
Toni M. ANTALIS
Keyword(s):  
Transcriptional Repression ◽  
Transcription Initiation ◽  
Transcriptional Control ◽  
Regulation Of Gene Expression ◽  
Regulatory Elements ◽  
Cellular Biology ◽  
Complete Understanding ◽  
Silencer Elements ◽  
Transcriptional Elements

Mechanisms controlling transcription and its regulation are fundamental to our understanding of molecular biology and, ultimately, cellular biology. Our knowledge of transcription initiation and integral factors such as RNA polymerase is considerable, and more recently our understanding of the involvement of enhancers and complexes such as holoenzyme and mediator has increased dramatically. However, an understanding of transcriptional repression is also essential for a complete understanding of promoter structure and the regulation of gene expression. Transcriptional repression in eukaryotes is achieved through ‘silencers ’, of which there are two types, namely ‘silencer elements ’ and ‘negative regulatory elements ’ (NREs). Silencer elements are classical, position-independent elements that direct an active repression mechanism, and NREs are position-dependent elements that direct a passive repression mechanism. In addition, ‘repressors ’ are DNA-binding trasncription factors that interact directly with silencers. A review of the recent literature reveals that it is the silencer itself and its context within a given promoter, rather than the interacting repressor, that determines the mechanism of repression. Silencers form an intrinsic part of many eukaryotic promoters and, consequently, knowledge of their interactive role with enchancers and other transcriptional elements is essential for our understanding of gene regulation in eukaryotes.

scholarly journals CarD contributes to diverse gene expression outcomes throughout the genome ofMycobacterium tuberculosis

2019 ◽  
Vol 116 (27) ◽  
pp. 13573-13581 ◽  
Author(s):  
Dennis X. Zhu ◽  
Ashley L. Garner ◽  
Eric A. Galburt ◽  
Christina L. Stallings
Keyword(s):  
Gene Expression ◽  
Transcriptional Repression ◽  
Transcription Initiation ◽  
Regulation Of Gene Expression ◽  
Kinetic Properties ◽  
E Coli ◽  
Promoter Escape ◽  
Genome Wide ◽  
Intrinsic Kinetic

The ability to regulate gene expression through transcription initiation underlies the adaptability and survival of all bacteria. Recent work has revealed that the transcription machinery in many bacteria diverges from the paradigm that has been established inEscherichia coli.Mycobacterium tuberculosis(Mtb) encodes the RNA polymerase (RNAP)-binding protein CarD, which is absent inE. colibut is required to form stable RNAP-promoter open complexes (RPo) and is essential for viability inMtb. The stabilization of RPoby CarD has been proposed to result in activation of gene expression; however, CarD has only been examined on limited promoters that do not represent the typical promoter structure inMtb. In this study, we investigate the outcome of CarD activity on gene expression fromMtbpromoters genome-wide by performing RNA sequencing on a panel of mutants that differentially affect CarD’s ability to stabilize RPo. In all CarD mutants, the majority ofMtbprotein encoding transcripts were differentially expressed, demonstrating that CarD had a global effect on gene expression. Contrary to the expected role of CarD as a transcriptional activator, mutation of CarD led to both up- and down-regulation of gene expression, suggesting that CarD can also act as a transcriptional repressor. Furthermore, we present evidence that stabilization of RPoby CarD could lead to transcriptional repression by inhibiting promoter escape, and the outcome of CarD activity is dependent on the intrinsic kinetic properties of a given promoter region. Collectively, our data support CarD’s genome-wide role of regulating diverse transcription outcomes.

scholarly journals SilencerDB: a comprehensive database of silencers

2020 ◽  
Vol 49 (D1) ◽  
pp. D221-D228
Author(s):  
Wanwen Zeng ◽  
Shengquan Chen ◽  
Xuejian Cui ◽  
Xiaoyang Chen ◽  
Zijing Gao ◽  
...  
Keyword(s):  
Transcription Initiation ◽  
Transcriptional Control ◽  
Regulatory Elements ◽  
Current Version ◽  
Machine Learning Methods ◽  
Comprehensive Database ◽  
Gene Regulatory Elements ◽  
Organ Tissue ◽  
Gene Regulatory ◽  
User Friendly

Abstract Gene regulatory elements, including promoters, enhancers, silencers, etc., control transcriptional programs in a spatiotemporal manner. Though these elements are known to be able to induce either positive or negative transcriptional control, the community has been mostly studying enhancers which amplify transcription initiation, with less emphasis given to silencers which repress gene expression. To facilitate the study of silencers and the investigation of their potential roles in transcriptional control, we developed SilencerDB (http://health.tsinghua.edu.cn/silencerdb/), a comprehensive database of silencers by manually curating silencers from 2300 published articles. The current version, SilencerDB 1.0, contains (1) 33 060 validated silencers from experimental methods, and (ii) 5 045 547 predicted silencers from state-of-the-art machine learning methods. The functionality of SilencerDB includes (a) standardized categorization of silencers in a tree-structured class hierarchy based on species, organ, tissue and cell line and (b) comprehensive annotations of silencers with the nearest gene and potential regulatory genes. SilencerDB, to the best of our knowledge, is the first comprehensive database at this scale dedicated to silencers, with reliable annotations and user-friendly interactive database features. We believe this database has the potential to enable advanced understanding of silencers in regulatory mechanisms and to empower researchers to devise diverse applications of silencers in disease development.

scholarly journals Interaction of the Srb10 Kinase with Sip4, a Transcriptional Activator of Gluconeogenic Genes in Saccharomyces cerevisiae

2001 ◽  
Vol 21 (17) ◽  
pp. 5790-5796 ◽  
Author(s):  
Olivier Vincent ◽  
Sergei Kuchin ◽  
Seung-Pyo Hong ◽  
Robert Townley ◽  
Valmik K. Vyas ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Rna Polymerase Ii ◽  
Transcriptional Repression ◽  
Transcriptional Control ◽  
Carbon Sources ◽  
Transcriptional Activator ◽  
Glucose Limitation ◽  
Cell Extracts ◽  
Rna Polymerase Ii Holoenzyme

ABSTRACT Sip4 is a Zn2Cys6 transcriptional activator that binds to the carbon source-responsive elements of gluconeogenic genes in Saccharomyces cerevisiae. The Snf1 protein kinase interacts with Sip4 and regulates its phosphorylation and activator function in response to glucose limitation; however, evidence suggested that another kinase also regulates Sip4. Here we examine the role of the Srb10 kinase, a component of the RNA polymerase II holoenzyme that has been primarily implicated in transcriptional repression but also positively regulates Gal4. We show that Srb10 is required for phosphorylation of Sip4 during growth in nonfermentable carbon sources and that the catalytic activity of Srb10 stimulates the ability of LexA-Sip4 to activate transcription of a reporter. Srb10 and Sip4 coimmunoprecipitate from cell extracts and interact in two-hybrid assays, suggesting that Srb10 regulates Sip4 directly. We also present evidence that the Srb10 and Snf1 kinases interact with different regions of Sip4. These findings support the view that the Srb10 kinase not only plays negative roles in transcriptional control but also has broad positive roles during growth in carbon sources other than glucose.

scholarly journals Sp1-Mediated Transcription of the Werner Helicase Gene Is Modulated by Rb and p53

1998 ◽  
Vol 18 (11) ◽  
pp. 6191-6200 ◽  
Author(s):  
Yukako Yamabe ◽  
Akira Shimamoto ◽  
Makoto Goto ◽  
Jun Yokota ◽  
Minoru Sugawara ◽  
...  
Keyword(s):  
Transcription Initiation ◽  
Promoter Activity ◽  
Transcriptional Control ◽  
Housekeeping Genes ◽  
Regulatory Elements ◽  
Initiation Site ◽  
Luciferase Reporter ◽  
Upstream Region ◽  
Control Element ◽  
Mrna Levels

ABSTRACT The regulation of Werner’s syndrome gene (WRN) expression was studied by characterizing the cis-regulatory elements in the promoter region and the trans-activating factors that bind to them. First, we defined the transcription initiation sites and the sequence of the 5′ upstream region (2.8 kb) ofWRN that contains a number of cis-regulatory elements, including 7 Sp1, 9 retinoblastoma control element (RCE), and 14 AP2 motifs. A region consisting of nucleotides −67 to +160 was identified as the principal promoter of WRN by reporter gene assays in HeLa cells, using a series of WRNpromoter-luciferase reporter (WRN-Luc) plasmids that contained the 5′-truncated or mutated WRN upstream regions. In particular, two Sp1 elements proximal to the transcription initiation site are indispensable for WRN promoter activity and bind specifically to Sp1 proteins. The RCE enhances WRN promoter activity. Coexpression of the WRN-Luc plasmids with various dosages of plasmids expressing Rb or p53 in Saos2 cells lacking active Rb and p53 proteins showed that the introduced Rb upregulates WRN promoter activity a maximum of 2.5-fold, while p53 downregulates it a maximum of 7-fold, both dose dependently. Consistently, the overexpressed Rb and p53 proteins also affected the endogenous WRN mRNA levels in Saos2 cells, resulting in an increase with Rb and a decrease with p53. These findings suggest that WRN expression, like that of other housekeeping genes, is directed mainly by the Sp1 transcriptional control system but is also further modulated by transcription factors, including Rb and p53, that are implicated in the cell cycle, cell senescence, and genomic instability.

scholarly journals CNBP controls transcription by unfolding DNA G-quadruplex structures

2019 ◽  
Vol 47 (15) ◽  
pp. 7901-7913 ◽  
Author(s):  
Aldana P David ◽  
Angélique Pipier ◽  
Federico Pascutti ◽  
Andrés Binolfi ◽  
Andrea M J Weiner ◽  
...  
Keyword(s):  
Transcriptional Control ◽  
Regulatory Elements ◽  
Transcription Start Sites ◽  
G4 Dna ◽  
Dna Strands ◽  
Living Organisms ◽  
And Function

Abstract Guanine-rich DNA strands can fold into non-canonical four-stranded secondary structures named G-quadruplexes (G4). Experimental evidences suggest that G4-DNA surrounding transcription start sites act as cis-regulatory elements by either stimulating or inhibiting gene transcription. Therefore, proteins able to target and regulate specific G4 formation/unfolding are crucial for G4-mediated transcriptional control. Here we present data revealing that CNBP acts in vitro as a G4-unfolding protein over a tetramolecular G4 formed by the TG4T oligonucleotide, as well as over the G4 folded in the promoters of several oncogenes. CNBP depletion in cellulo led to a reduction in the transcription of endogenous KRAS, suggesting a regulatory role of CNBP in relieving the transcriptional abrogation due to G4 formation. CNBP activity was also assayed over the evolutionary conserved G4 enhancing the transcription of NOGGIN (NOG) developmental gene. CNBP unfolded in vitro NOG G4 and experiments performed in cellulo and in vivo in developing zebrafish showed a repressive role of CNBP on the transcription of this gene by G4 unwinding. Our results shed light on the mechanisms underlying CNBP way of action, as well as reinforce the notion about the existence and function of G4s in whole living organisms.

scholarly journals Transcriptional Enhancers in Drosophila

Genetics ◽  
2020 ◽  
Vol 216 (1) ◽  
pp. 1-26 ◽  
Author(s):  
Stephen Small ◽  
David N. Arnosti
Keyword(s):  
Gene Expression ◽  
Critical Role ◽  
Regulation Of Gene Expression ◽  
Regulatory Elements ◽  
Comprehensive Analysis ◽  
Special Focus ◽  
Transcriptional Enhancers ◽  
Quantitative Understanding ◽  
Developmental Role

Key discoveries in Drosophila have shaped our understanding of cellular “enhancers.” With a special focus on the fly, this chapter surveys properties of these adaptable cis-regulatory elements, whose actions are critical for the complex spatial/temporal transcriptional regulation of gene expression in metazoa. The powerful combination of genetics, molecular biology, and genomics available in Drosophila has provided an arena in which the developmental role of enhancers can be explored. Enhancers are characterized by diverse low- or high-throughput assays, which are challenging to interpret, as not all of these methods of identifying enhancers produce concordant results. As a model metazoan, the fly offers important advantages to comprehensive analysis of the central functions that enhancers play in gene expression, and their critical role in mediating the production of phenotypes from genotype and environmental inputs. A major challenge moving forward will be obtaining a quantitative understanding of how these cis-regulatory elements operate in development and disease.

scholarly journals Limited consequences for loss of RNA-directed DNA methylation in Setaria viridis domains rearranged methyltransferase (DRM) mutants

2022 ◽  
Author(s):  
Andrew C. Read ◽  
Trevor Weiss ◽  
Peter A. Crisp ◽  
Zhikai Liang ◽  
Jaclyn Noshay ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Transcriptional Repression ◽  
Regulation Of Gene Expression ◽  
Transcriptome Profiling ◽  
Setaria Viridis ◽  
Loss Of Function ◽  
Promoter Regions ◽  
Altered Expression ◽  
Genome Methylation

The Domains Rearranged Methyltransferases (DRMs) are crucial for RNA-directed DNA methylation (RdDM) in plant species. Setaria viridis is a model monocot species with a relatively compact genome that has limited transposable element content. CRISPR-based genome editing approaches were used to create loss-of-function alleles for the two putative functional DRM genes in S. viridis to probe the role of RdDM. The analysis of drm1ab double mutant plants revealed limited morphological consequences for the loss of RdDM. Whole-genome methylation profiling provided evidence for wide-spread loss of methylation in CHH sequence contexts, particularly in regions with high CHH methylation in wild-type plants. There is also evidence for locus-specific loss of CG and CHG methylation, even in some regions that lack CHH methylation. Transcriptome profiling identified a limited number of genes with altered expression in the drm1ab mutants. The majority of genes with elevated CHH methylation directly surrounding the transcription start site or in nearby promoter regions do not have altered expression in the drm1ab mutant even when this methylation is lost, suggesting limited regulation of gene expression by RdDM. Detailed analysis of the expression of transposable elements identified several transposons that are transcriptionally activated in drm1ab mutants. These transposons likely require active RdDM for maintenance of transcriptional repression.

Transcriptional control of the oxidative stress response and implications of using plant derived molecules for therapeutic interventions in cancer

2021 ◽  
Vol 28 ◽  
Author(s):  
Asim Rizvi ◽  
Mohd. Farhan ◽  
Faisal Nabi ◽  
Rizwan Hasan Khan ◽  
Mohd. Adil ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Transcription Factors ◽  
Stress Response ◽  
Cancer Cells ◽  
Transcriptional Control ◽  
Regulation Of Gene Expression ◽  
Oxidative Stress Response ◽  
Therapeutic Interventions ◽  
Lead Compounds

: Oxidative stress response is critical for the malignant cells. It plays dual role by helping cancer cells survive and proliferate but also causing apoptosis and apoptosis like cell death. The oxidative stress response is characterized by a tight regulation of gene expression by a series of transcription factors (OSRts; oxidative stress response transcription factors). In this communication, we review the role of OSRts, notably NRF2 and p53 as well as other transcription factors, that modulate the response. We discuss how the oxidative stress response is hierarchal and controls ‘live or die’ signals. This is followed by a discussion on how plant derived molecules, including polyphenols, which are described both as prooxidants and antioxidants within the cancer cells, have been reported to affect the activities of OSRts. Deriving an example from preliminary data from our group, we discuss how plant derived molecules might modulate the oxidative stress response by causing structural perturbations in the proteinacious transcription factors, notably Nrf2 and p53. We look at this information in the light of understanding how plant derived molecules maybe used as lead compounds to develop modulators of the oxidative stress response.

scholarly journals An RNA-centric global view of Clostridioides difficile reveals broad activity of Hfq in a clinically important Gram-positive bacterium

2020 ◽  
Author(s):  
Manuela Fuchs ◽  
Vanessa Lamm-Schmidt ◽  
Falk Ponath ◽  
Laura Jenniches ◽  
Lars Barquist ◽  
...  
Keyword(s):  
Transcriptional Control ◽  
Rna Binding ◽  
Regulatory Elements ◽  
Infection Process ◽  
Positive Bacterium ◽  
Gram Positive ◽  
Target Mrnas ◽  
Clostridioides Difficile

ABSTRACTThe Gram-positive human pathogen Clostridioides difficile has emerged as the leading cause of antibiotic-associated diarrhea. Despite growing evidence for a role of Hfq in RNA-based gene regulation in C. difficile, little is known about the bacterium’s transcriptome architecture and mechanisms of post-transcriptional control. Here, we have applied a suite of RNA-centric techniques, including transcription start site mapping, transcription termination mapping and Hfq RIP-seq, to generate a single-nucleotide resolution RNA map of C. difficile 630. Our transcriptome annotation provides information about 5’ and 3’ untranslated regions, operon structures and non-coding regulators, including 42 sRNAs. These transcriptome data are accessible via an open-access browser called ‘Clost-Base’. Our results indicate functionality of many conserved riboswitches and predict novel cis-regulatory elements upstream of MDR-type ABC transporters and transcriptional regulators. Recent studies have revealed a role of sRNA-based regulation in several Gram-positive bacteria but their involvement with the RNA-binding protein Hfq remains controversial. Here, sequencing the RNA ligands of Hfq reveals in vivo association of many sRNAs along with hundreds of potential target mRNAs in C. difficile providing evidence for a global role of Hfq in post-transcriptional regulation in a Gram-positive bacterium. Through integration of Hfq-bound transcripts and computational approaches we predict regulated target mRNAs for the novel sRNA AtcS encoding several adhesins and the conserved oligopeptide transporter oppB that influences sporulation initiation in C. difficile. Overall, these findings provide a potential mechanistic explanation for increased biofilm formation and sporulation in an hfq deletion strain and lay the foundation for understanding clostridial ribo regulation with implications for the infection process.

scholarly journals The KZFP/KAP1 system controls transposable elements-embedded regulatory sequences in adult T cells

2019 ◽  
Author(s):  
Flavia Marzetta ◽  
Laia Simó-Riudalbas ◽  
Julien Duc ◽  
Evarist Planet ◽  
Sonia Verp ◽  
...  
Keyword(s):  
Gene Expression ◽  
T Cells ◽  
Transposable Elements ◽  
Transcriptional Repression ◽  
Regulation Of Gene Expression ◽  
Embryonic Stem ◽  
Cell Receptor ◽  
Regulatory Elements ◽  
Regulatory Sequences ◽  
Adult Human

ABSTRACTTransposable elements-embedded regulatory sequences (TEeRS) are subjected to early embryonic repression through sequence-specific recruitment of KRAB zinc finger proteins (KZFPs), their cofactor KAP1/TRIM28 and associated chromatin modifiers. This modulates the TEeRS-mediated regulation of gene expression in embryonic stem cells (ESCs) and leads to DNA methylation-induced silencing. However, KZFPs are broadly expressed in adult tissues, suggesting that they control TEeRS throughout life. Confirming this hypothesis, we reveal here that the KZFP/KAP1 system exerts a highly dynamic control of TEeRS in adult human CD4+ T lymphocytes. First, we observed that in these cells many TEs are still bound by KAP1, the recruitment of which is dynamically regulated upon T cell receptor stimulation. Second, we found that KAP1 depletion induces broad transcriptional alterations in T cells, with de-repression of TE-based regulatory elements leading to the illegitimate activation of nearby genes. Finally, we show that the tissue-restricted expression of KZFPs correlates with KAP1-mediated lineage-specific chromatin signatures and transcriptional repression. These data support a model where TE-targeting KZFPs and KAP1 are important regulators of gene expression in adult human cells.

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