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Chapter Category: RNA
From the book RNA Exosome
The Exosome and Heterochromatin
Multilevel Regulation of Gene Silencing
Sarah Coy and Lidia Vasiljeva
Heterochromatic silencing is important for repressing gene expression, protecting cells against viral invasion, maintaining DNA integrity and for proper chromosome segregation. Recently, it has become apparent that expression of eukaryotic genomes is far more complex than had previously been anticipated. Strikingly, it has emerged that most of the genome is transcribed including intergenic regions and heterochromatin, calling for us to re‑address the question of how gene silencing is regulated and re‑evaluate the concept of heterochromatic regions of the genome being transcriptionally inactive. Although heterochromatic silencing can be regulated at the transcriptional level, RNA degrading activities supplied either by the exosome complex or RNAi also significantly contribute to this process. The exosome also regulates noncoding RNAs (ncRNAs) involved in the establishment of heterochromatin, further underscoring its role as the major cellular machinery involved in RNA processing and turn‑over. This multilevel control of the transcriptome may be utilized to ensure greater accuracy of gene expression and allow distinction between functional transcripts and background noise. In this chapter, we will discuss the regulation of gene silencing across species, with special emphasis on the exosome’s contribution to the process. We will also discuss the links between transcriptional and posttranscriptional mechanisms for gene silencing and their impact on the regulation of eukaryotic transcriptomes.
- ISBN: 978-1-4419-7840-0
- Publication date: December 2, 2010
- Series: Special Books
RNA Exosome
Edited by: Torben Heick Jensen
More chapters from the book:
One of the most versatile RNA degradation machines in eukaryotes is the 3'‑5' RNA exosome. It consists of nine conserved subunits forming the core complex, which associates with active ribonucleases, RNA binding proteins, helicases and additional co-factors. While yeast and human exosome...
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This chapter reviews the present state of knowledge on the activity of enzymes that function with the RNA exosome in the nucleus. In this compartment, the exosome interacts physically and functionally with the exoribonuclease Rrp6 and several cofactors, most prominently Rrp47 and the TRAMP...
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The Exosome and Heterochromatin
Multilevel Regulation of Gene Silencing
Sarah Coy and Lidia VasiljevaHeterochromatic silencing is important for repressing gene expression, protecting cells against viral invasion, maintaining DNA integrity and for proper chromosome segregation. Recently, it has become apparent that expression of eukaryotic genomes is far more complex than had previously been...
Catalytic Properties of the Eukaryotic Exosome
Aleksander Chlebowski, Rafał Tomecki, María Eugenia Gas López, Bertrand Séraphin and Andrzej DziembowskiThe eukaryotic exosome complex is built around the backbone of a 9‑subunit ring similar to phosporolytic ribonucleases such as RNase PH and polynucleotide phosphorylase (PNPase). Unlike those enzymes, the ring is devoid of any detectable catalytic activities, with the possible exception of...
Over the last few years, the development of large‑scale technologies has radically modified our conception of genome‑wide transcriptional control by unveiling an unexpected high complexity of the eukaryotic transcriptome. In organisms ranging from yeast to human, a considerable number of...
Functions of the Cytoplasmic Exosome
Daneen Schaeffer, Amanda Clark, A. Alejandra Klauer, Borislava Tsanova and Ambro van HoofThe exosome consists of a core of ten essential proteins that includes the ribonuclease Rrp44p and is present in both the cytoplasm and nucleus of eukaryotic cells. The cytoplasmic exosome has been extensively characterized in the budding yeast Saccharomyces cerevisiae and some...
The archaeal exosome contains three heterodimeric RNase PH subunits, forming a hexamer with RNase activity; on top sits a trimer of two different SI domain proteins. In animals and yeast, six different, but related subunits form the RNase PH‑like core, but these lack enzyme activity; there...