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Author: Gregory T. Booth
Publisher:
ISBN:
Category :
Languages : en
Pages : 404
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Book Description
Promoter-proximal pausing of RNA Polymerase II (Pol II) is now recognized as a ubiquitous mechanism for regulating gene expression in metazoans. By capturing engaged Pol II shortly after transcription initiation, genes are primed for activation of RNA synthesis, enabling cells to rapidly alter global transcription programs. However, despite conservation of many factors involved in establishing this regulatory platform, many eukaryotes do not control gene expression through this process. Here, the examination of the global transcriptional landscape in two distantly related yeast revealed unprecedented divergence in Pol II distributions across genes. Previously undescribed pause-like profiles were identified within promoter-proximal regions of the fission yeast, Schizosaccharomyces pombe, that are sensitive to loss of the conserved elongation factor, Spt4. Thus, fission yeast might employ a variant of the system of regulation found in higher eukaryotes In flies and mammals, Pol II arrested within the promoter proximal region of a gene can only be released through the activity of a positive-transcription elongation factor (P-TEFb), composed of kinase (Cdk9) and cyclin (CycT1/2) subunits. Investigating the functional impact of Cdk9 on transcription in fission yeast revealed that, unlike most metazoan systems, Pol II in S. pombe is capable of overcoming the early elongation barrier after kinase inhibition, although not without consequence. However, fission yeast lack the metazoan-specific negative elongation factor complex (NELF) involved in pausing, perhaps limiting their ability to control the release of Pol II through phosphorylation of the elongation complex. Ultimately, by depleting pausing factors from cell lines derived from Drosophila melanogaster, it was tested whether NELF is required for P-TEFb-regulated pause escape. While global transcription is largely unaffected by the loss of NELF, upon inhibition of Cdk9, a significant amount of Pol II is aberrantly released from the pause, suggesting reduced control of this regulation. These findings suggest that NELF may have evolutionarily refined an ancestral promoter-proximal architecture of the transcription elongation complex, giving rise to a novel mechanism for gene regulation.
Author: Gregory T. Booth
Publisher:
ISBN:
Category :
Languages : en
Pages : 404
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Book Description
Promoter-proximal pausing of RNA Polymerase II (Pol II) is now recognized as a ubiquitous mechanism for regulating gene expression in metazoans. By capturing engaged Pol II shortly after transcription initiation, genes are primed for activation of RNA synthesis, enabling cells to rapidly alter global transcription programs. However, despite conservation of many factors involved in establishing this regulatory platform, many eukaryotes do not control gene expression through this process. Here, the examination of the global transcriptional landscape in two distantly related yeast revealed unprecedented divergence in Pol II distributions across genes. Previously undescribed pause-like profiles were identified within promoter-proximal regions of the fission yeast, Schizosaccharomyces pombe, that are sensitive to loss of the conserved elongation factor, Spt4. Thus, fission yeast might employ a variant of the system of regulation found in higher eukaryotes In flies and mammals, Pol II arrested within the promoter proximal region of a gene can only be released through the activity of a positive-transcription elongation factor (P-TEFb), composed of kinase (Cdk9) and cyclin (CycT1/2) subunits. Investigating the functional impact of Cdk9 on transcription in fission yeast revealed that, unlike most metazoan systems, Pol II in S. pombe is capable of overcoming the early elongation barrier after kinase inhibition, although not without consequence. However, fission yeast lack the metazoan-specific negative elongation factor complex (NELF) involved in pausing, perhaps limiting their ability to control the release of Pol II through phosphorylation of the elongation complex. Ultimately, by depleting pausing factors from cell lines derived from Drosophila melanogaster, it was tested whether NELF is required for P-TEFb-regulated pause escape. While global transcription is largely unaffected by the loss of NELF, upon inhibition of Cdk9, a significant amount of Pol II is aberrantly released from the pause, suggesting reduced control of this regulation. These findings suggest that NELF may have evolutionarily refined an ancestral promoter-proximal architecture of the transcription elongation complex, giving rise to a novel mechanism for gene regulation.
Author: Nicholas James Fuda
Publisher:
ISBN:
Category :
Languages : en
Pages : 202
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Book Description
Most gene expression is regulated at the level of transcription, and the transition from initiation to productive elongation is a key point of regulation. This transition is accompanied by pausing of transcriptionally engaged polymerase in the promoter-proximal region of several heat shock genes. Although this mechanism of regulation was long thought to be limited to a few genes, recent evidence has indicated that pausing is wide-spread in higher eukaryotes. Therefore, it is increasingly important to understand the mechanisms controlling the paused polymerase. I have investigated how the site of pausing on Hsp70 is specified using highresolution mapping of polymerase on reporter genes with shifted pausing site sequences. The results indicate that the downstream sequence dictates pause position and the overall level of pausing. I have also used RNAi knock-down in Drosophila cell culture to study the roles of several factors in establishing, maintaining, and releasing the paused polymerase. These experiments have shown GAGA factor is required for pausing on many of its target genes, and the knock-down effects indicate it is involved in establishing the pause. In contrast, Spt5, a protein previously shown to enhance pausing in vitro, reduces pausing genome-wide by increasing levels of elongating polymerase. Two kinases, P-TEFb and CDK12, function in productive elongation. Previously our lab showed that P-TEFb inhibition prevented the transition into elongation, limiting the polymerase to the 5' end of the heat shock-induced Hsp70 gene. I mapped these polymerases in high resolution to show they occupied sites further downstream than the normal pause sites, suggesting P-TEFb activity may not solely release the paused polymerase. I also determined the localization of CDK12 on active genes. Its localization downstream of P-TEFb suggests that these kinases may have distinct functions. Finally, I have examined the role of Fcp1 in Hsp70 transcription. Our lab previously showed the CTD phosphatase Fcp1 was required for optimum expression of Hsp70 mRNA. Fcp1 knock-down reduced the heat shock levels of Pol II and increased phosphorylation of nonchromatin bound Pol II, indicating that Fcp1 recycling of RNA polymerase II to an initiationcompetent form is required for optimal Hsp70 heat shock transcription.
Author: Melodi Damla Tastemel
Publisher:
ISBN:
Category :
Languages : en
Pages : 100
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Author: Hojoong Kwak
Publisher:
ISBN:
Category :
Languages : en
Pages : 183
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Book Description
Limiting RNA polymerase II (Pol II) at various stages of the transcription cycle is critical for gene regulation, which often occurs during the elongation stage at promoter proximal pause sites and in gene bodies. To determine the distribution of Pol II along genes, I used nascent transcript analysis as a general method. First, I identified the precise positions of Pol II pausing near promoters using a genome-wide nuclear run-on, called Precision Run-On sequencing (PRO-seq) in Drosophila embryonic cells. Using this, I revealed how the position of pausing is associated with initiation and promoter DNA elements. To further dissect the precise dynamics of paused Pol II, I probed the stability of paused Pol II and its termination by analyzing steady-state turn-over of the nascent transcript associated with Drosophila Hsp70 promoter. This shows that paused Pol II on Hsp70 is stable for around 5 min and can either terminate or elongate into the gene body, which is consistent with optical measurements of paused Pol II. I also examined how Pol II elongates during the time course of rapid and robust inhibition of pause escape in mouse embryonic stem cells. The analysis of the elongation rates in nearly 1,000 genes showed tight interplay between promoter proximal pausing, early elongation rates, and co-transcriptional splicing at the beginning of the genes. Finally, I demonstrate that the nascent transcriptome analysis methods can be directly extended into mammalian tissues, and show possibility of linking the study of the fundamental mechanism of Pol II into biomedical applications.
Author: Asma Issam Hatoum
Publisher:
ISBN:
Category :
Languages : en
Pages : 302
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Author: Anthony Chun-yin Chiu
Publisher:
ISBN:
Category :
Languages : en
Pages : 221
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Book Description
Transcription is one of the most fundamental processes in cells, governing the conversion of genetic information to RNA. Numerous regulatory mechanisms function to ensure that desired transcripts are being expressed. Promoters transcribe divergently, producing low-abundant upstream antisense RNAs (uaRNAs) in addition to a stable downstream RNAs. Thus, a central question is what mechanisms are sense RNAs more stable compared to most transcription events. It is proposed that an asymmetric distribution of Ul snRNP binding sites and polyadenylation site (PAS) motifs known as the UI-PAS axis regulates early termination of RNA Polymerase II. Here, we generated a conditional knockout of the essential RNA exosome subunit, Exosc3, in mouse embryonic stem cells. Removal of Exosc3 resulted in stabilization of polyadenylated uaRNAs, enhancer RNAs and long noncoding RNAs. In addition, promoter proximal pausing increased modestly upon Exosc3 removal. Interestingly, a large class of polyadenylated short transcripts in the sense direction terminate within the first intron, similar to premature termination observed upon Ul inhibition. Further investigation of these prematurely termination sites revealed they are found at the edges of stable nucleosome free regions demarcated by CpG islands and are suppressed by U1 snRNP. Interestingly, promoter-proximal Pol II pausing consists of two processes: TSS-proximal and +1 stable nucleosome pausing. Genes associated with premature termination have increased +1 stable nucleosome pausing, association of chromatin remodelers and are more sensitive to inhibition by flavopiridol or a Myc inhibitor. Additionally, the nuclear poly(A) binding protein, Pabpnl, promotes degradation of polyadenylated uaRNAs. Most Pabpnl sensitive uaRNAs are also Exosc3 substrates, and sensitivity to Pabpnl inhibition inversely correlates with the proximity of the termination site to the TSS. Interestingly, at uaRNAs and sense RNAs, Pabpnl -sensitive PAS termination events also occur near the first stable nucleosome, similar to Exosc3-sensitive PAS termination events, suggesting that Pabpnl collaborates with Exosc3 to regulate stability of polyadenylated transcripts. Hence, this supports a model whereby Ul snRNP, +1 stable nucleosomes and the degradation machinery converge to create a transcription elongation checkpoint downstream of promoter-proximal pausing.
Author: B. D. Hames
Publisher: Oxford University Press, USA
ISBN:
Category : Music
Languages : en
Pages : 238
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Book Description
This book gives a co-ordinated review of our present knowledge of eukaryotic RNA synthesis.
Author: Marc Böhning
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Transcription of protein-coding genes by RNA polymerase (Pol) II is a highly coordinated process. In metazoan cells, transcription is regulated both at the initiation step by recruitment of the Pol II machinery as well as during early elongation by promoter-proximal pausing. Prior to transcription initiation, Pol II forms short-lived clusters near active gene promoters, but the underlying molecular basis has remained unknown. Pol II possesses a disordered C-terminal heptad repeat domain (CTD) that is essential for factor recruitment during the transcription cycle. CTD length is organism-spe...
Author: Eric H. Davidson
Publisher: Elsevier
ISBN: 0080455573
Category : Science
Languages : en
Pages : 303
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Book Description
Gene regulatory networks are the most complex, extensive control systems found in nature. The interaction between biology and evolution has been the subject of great interest in recent years. The author, Eric Davidson, has been instrumental in elucidating this relationship. He is a world renowned scientist and a major contributor to the field of developmental biology. The Regulatory Genome beautifully explains the control of animal development in terms of structure/function relations of inherited regulatory DNA sequence, and the emergent properties of the gene regulatory networks composed of these sequences. New insights into the mechanisms of body plan evolution are derived from considerations of the consequences of change in developmental gene regulatory networks. Examples of crucial evidence underscore each major concept. The clear writing style explains regulatory causality without requiring a sophisticated background in descriptive developmental biology. This unique text supersedes anything currently available in the market. - The only book in the market that is solely devoted to the genomic regulatory code for animal development - Written at a conceptual level, including many novel synthetic concepts that ultimately simplify understanding - Presents a comprehensive treatment of molecular control elements that determine the function of genes - Provides a comparative treatment of development, based on principles rather than description of developmental processes - Considers the evolutionary processes in terms of the structural properties of gene regulatory networks - Includes 42 full-color descriptive figures and diagrams
Author: Tilman Heise
Publisher:
ISBN: 9781071602317
Category : Human genetics
Languages : en
Pages : 314
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Book Description
This book provides a wide spectrum of methods to study RNA chaperones in vitro, at the single molecule level, and protocols useful for cell-based assays. Beginning with a section on a number of bacterial proteins for study, the volume also explores proteins from eukaryotic cells and how to delve into the complex interactions between RNA chaperones and the folding and unfolding of proteins. Written for the highly successful Methods in Molecular Biology series, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls. Authoritative and practical, RNA Chaperones: Methods and Protocols serves as an ideal guide for scientists and students interested in RNA biology and RNA chaperones. Chapter 3 is available Open Access under a CC-BY 4.0 license via link.springer.com.
