scholarly journals Cockayne syndrome group A and B proteins function in rRNA transcription through nucleolin regulation

2020 ◽  
Vol 48 (5) ◽  
pp. 2473-2485 ◽  
Author(s):  
Mustafa N Okur ◽  
Jong-Hyuk Lee ◽  
Wasif Osmani ◽  
Risako Kimura ◽  
Tyler G Demarest ◽  
...  
Keyword(s):  
Ribosome Biogenesis ◽  
Accelerated Aging ◽  
Cockayne Syndrome ◽  
Rrna Synthesis ◽  
Coding Region ◽  
Molecular Features ◽  
Human Genes ◽  
Positive Regulators ◽  
Group A ◽  
Polymerase I

Abstract Cockayne Syndrome (CS) is a rare neurodegenerative disease characterized by short stature, accelerated aging and short lifespan. Mutations in two human genes, ERCC8/CSA and ERCC6/CSB, are causative for CS and their protein products, CSA and CSB, while structurally unrelated, play roles in DNA repair and other aspects of DNA metabolism in human cells. Many clinical and molecular features of CS remain poorly understood, and it was observed that CSA and CSB regulate transcription of ribosomal DNA (rDNA) genes and ribosome biogenesis. Here, we investigate the dysregulation of rRNA synthesis in CS. We report that Nucleolin (Ncl), a nucleolar protein that regulates rRNA synthesis and ribosome biogenesis, interacts with CSA and CSB. In addition, CSA induces ubiquitination of Ncl, enhances binding of CSB to Ncl, and CSA and CSB both stimulate the binding of Ncl to rDNA and subsequent rRNA synthesis. CSB and CSA also increase RNA Polymerase I loading to the coding region of the rDNA and this is Ncl dependent. These findings suggest that CSA and CSB are positive regulators of rRNA synthesis via Ncl regulation. Most CS patients carry mutations in CSA and CSB and present with similar clinical features, thus our findings provide novel insights into disease mechanism.

scholarly journals Che-1/AATF binds to RNA polymerase I machinery and sustains ribosomal RNA gene transcription

2020 ◽  
Vol 48 (11) ◽  
pp. 5891-5906 ◽  
Author(s):  
Cristina Sorino ◽  
Valeria Catena ◽  
Tiziana Bruno ◽  
Francesca De Nicola ◽  
Stefano Scalera ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Rna Polymerase ◽  
Ribosomal Rna ◽  
Ribosome Biogenesis ◽  
Cellular Proliferation ◽  
Rna Polymerase I ◽  
Rrna Synthesis ◽  
Rrna Gene ◽  
Response To Stress ◽  
Polymerase I

Abstract Originally identified as an RNA polymerase II interactor, Che-1/AATF (Che-1) has now been recognized as a multifunctional protein involved in cell-cycle regulation and cancer progression, as well as apoptosis inhibition and response to stress. This protein displays a peculiar nucleolar localization and it has recently been implicated in pre-rRNA processing and ribosome biogenesis. Here, we report the identification of a novel function of Che-1 in the regulation of ribosomal RNA (rRNA) synthesis, in both cancer and normal cells. We demonstrate that Che-1 interacts with RNA polymerase I and nucleolar upstream binding factor (UBF) and promotes RNA polymerase I-dependent transcription. Furthermore, this protein binds to the rRNA gene (rDNA) promoter and modulates its epigenetic state by contrasting the recruitment of HDAC1. Che-1 downregulation affects RNA polymerase I and UBF recruitment on rDNA and leads to reducing rDNA promoter activity and 47S pre-rRNA production. Interestingly, Che-1 depletion induces abnormal nucleolar morphology associated with re-distribution of nucleolar proteins. Finally, we show that upon DNA damage Che-1 re-localizes from rDNA to TP53 gene promoter to induce cell-cycle arrest. This previously uncharacterized function of Che-1 confirms the important role of this protein in the regulation of ribosome biogenesis, cellular proliferation and response to stress.

scholarly journals Cockayne Syndrome-Associated CSA and CSB Mutations Impair Ribosome Biogenesis, Ribosomal Protein Stability, and Global Protein Folding

Cells ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1616
Author(s):  
Mingyue Qiang ◽  
Fatima Khalid ◽  
Tamara Phan ◽  
Christina Ludwig ◽  
Karin Scharffetter-Kochanek ◽  
...  
Keyword(s):  
Ribosomal Proteins ◽  
Ribosome Biogenesis ◽  
Cellular Proliferation ◽  
Subcutaneous Fat ◽  
Cockayne Syndrome ◽  
Translation Process ◽  
Aging Body ◽  
Polymerase I ◽  
Cell Proteome ◽  
Underlying Pathophysiology

Cockayne syndrome (CS) is a developmental disorder with symptoms that are typical for the aging body, including subcutaneous fat loss, alopecia, and cataracts. Here, we show that in the cells of CS patients, RNA polymerase I transcription and the processing of the pre-rRNA are disturbed, leading to an accumulation of the 18S-E intermediate. The mature 18S rRNA level is reduced, and isolated ribosomes lack specific ribosomal proteins of the small 40S subunit. Ribosomal proteins are susceptible to unfolding and the CS cell proteome is heat-sensitive, indicating misfolded proteins and an error-prone translation process in CS cells. Pharmaceutical chaperones restored impaired cellular proliferation. Therefore, we provide evidence for severe protein synthesis malfunction, which together with a loss of proteostasis constitutes the underlying pathophysiology in CS.

scholarly journals Defining the Influence of the A12.2 Subunit on Transcription Elongation and Termination by RNA Polymerase I In Vivo

Genes ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1939
Author(s):  
Andrew M. Clarke ◽  
Abigail K. Huffines ◽  
Yvonne J. K. Edwards ◽  
Chad M. Petit ◽  
David A. Schneider
Keyword(s):  
Rna Polymerase ◽  
Ribosome Biogenesis ◽  
Transcription Elongation ◽  
5S Rdna ◽  
Rna Polymerase I ◽  
Rrna Synthesis ◽  
Rdna Gene ◽  
Pol I ◽  
Nucleotide Addition ◽  
Polymerase I

Saccharomyces cerevisiae has approximately 200 copies of the 35S rDNA gene, arranged tandemly on chromosome XII. This gene is transcribed by RNA polymerase I (Pol I) and the 35S rRNA transcript is processed to produce three of the four rRNAs required for ribosome biogenesis. An intergenic spacer (IGS) separates each copy of the 35S gene and contains the 5S rDNA gene, the origin of DNA replication, and the promoter for the adjacent 35S gene. Pol I is a 14-subunit enzyme responsible for the majority of rRNA synthesis, thereby sustaining normal cellular function and growth. The A12.2 subunit of Pol I plays a crucial role in cleavage, termination, and nucleotide addition during transcription. Deletion of this subunit causes alteration of nucleotide addition kinetics and read-through of transcription termination sites. To interrogate both of these phenomena, we performed native elongating transcript sequencing (NET-seq) with an rpa12Δ strain of S. cerevisiae and evaluated the resultant change in Pol I occupancy across the 35S gene and the IGS. Compared to wild-type (WT), we observed template sequence-specific changes in Pol I occupancy throughout the 35S gene. We also observed rpa12Δ Pol I occupancy downstream of both termination sites and throughout most of the IGS, including the 5S gene. Relative occupancy of rpa12Δ Pol I increased upstream of the promoter-proximal Reb1 binding site and dropped significantly downstream, implicating this site as a third terminator for Pol I transcription. Collectively, these high-resolution results indicate that the A12.2 subunit of Pol I plays an important role in transcription elongation and termination.

scholarly journals Nucleolar Components Involved in Ribosome Biogenesis Cycle between the Nucleolus and Nucleoplasm in Interphase Cells

2001 ◽  
Vol 153 (1) ◽  
pp. 169-176 ◽  
Author(s):  
Danyang Chen ◽  
Sui Huang
Keyword(s):  
Ribosome Biogenesis ◽  
Dynamic Properties ◽  
Ribosomal Subunit ◽  
Selective Inhibition ◽  
Rrna Synthesis ◽  
Functional Roles ◽  
Binding Factor ◽  
Upstream Binding Factor ◽  
Polymerase I ◽  
Nucleolar Components

We examined the mobilities of nucleolar components that act at various steps of the ribosome biogenesis pathway. Fluorescence recovery after photobleaching (FRAP) and fluorescence loss in photobleaching (FLIP) analyses demonstrate that factors involved in rRNA transcription (upstream-binding factor [UBF]), processing (nucleolin, fibrillarin, and RNase MRP subunits, Rpp29), and ribosome assembly (B23) exchange rapidly between the nucleoplasm and nucleolus. In contrast, the mobilities of ribosomal subunit proteins (S5, L9) are much slower. Selective inhibition of RNA polymerase I transcription does not prevent the exchanges but influences the rates of exchange differentially for different nucleolar components. These findings suggest that the rapid exchange of nucleolar components between the nucleolus and nucleoplasm may represent a new level of regulation for rRNA synthesis. The different dynamic properties of proteins involved in different steps of ribosome biogenesis imply that the nucleolar association of these proteins is due to their specific functional roles rather than simply their specific nucleolar-targeting events.

scholarly journals Novel role of the dietary flavonoid fisetin in suppressing rRNA biogenesis

2021 ◽  
Author(s):  
Sarah C. Kammerud ◽  
Brandon J. Metge ◽  
Amr R. Elhamamsy ◽  
Shannon E. Weeks ◽  
Heba A. Alsheikh ◽  
...  
Keyword(s):  
Tumor Progression ◽  
Ribosomal Rna ◽  
Ribosome Biogenesis ◽  
Negative Impact ◽  
Rrna Synthesis ◽  
Pol I ◽  
Lung Colonization ◽  
A Cell ◽  
Dietary Flavonoid ◽  
Polymerase I

AbstractThe nucleolus of a cell is a critical cellular compartment that is responsible for ribosome biogenesis and plays a central role in tumor progression. Fisetin, a nutraceutical, is a naturally occurring flavonol from the flavonoid group of polyphenols that has anti-cancer effects. Fisetin negatively impacts several signaling pathways that support tumor progression. However, effect of fisetin on the nucleolus and its functions were unknown. We observed that fisetin is able to physically enter the nucleolus. In the nucleolus, RNA polymerase I (RNA Pol I) mediates the biogenesis of ribosomal RNA. Thus, we investigated the impacts of fisetin on the nucleolus. We observed that breast tumor cells treated with fisetin show a 20–30% decreased nucleolar abundance per cell and a 30–60% downregulation of RNA Pol I transcription activity, as well as a 50–70% reduction in nascent rRNA synthesis, depending on the cell line. Our studies show that fisetin negatively influences MAPK/ERK pathway to impair RNA Pol I activity and rRNA biogenesis. Functionally, we demonstrate that fisetin acts synergistically (CI = 0.4) with RNA Pol I inhibitor, BMH-21 and shows a noteworthy negative impact (60% decrease) on lung colonization of breast cancer cells. Overall, our findings highlight the potential of ribosomal RNA (rRNA) biogenesis as a target for secondary prevention and possible treatment of metastatic disease.

scholarly journals Commuting to Work: Nucleolar Long Non-Coding RNA Control Ribosome Biogenesis from Near and Far

2021 ◽  
Vol 7 (3) ◽  
pp. 42
Author(s):  
Victoria Mamontova ◽  
Barbara Trifault ◽  
Lea Boten ◽  
Kaspar Burger
Keyword(s):  
Gene Expression ◽  
Rna Polymerase Ii ◽  
Ribosome Biogenesis ◽  
Intergenic Spacer ◽  
Cellular Growth ◽  
Rrna Synthesis ◽  
Protein Coding ◽  
Non Coding Rna ◽  
And Function ◽  
In Cis

Gene expression is an essential process for cellular growth, proliferation, and differentiation. The transcription of protein-coding genes and non-coding loci depends on RNA polymerases. Interestingly, numerous loci encode long non-coding (lnc)RNA transcripts that are transcribed by RNA polymerase II (RNAPII) and fine-tune the RNA metabolism. The nucleolus is a prime example of how different lncRNA species concomitantly regulate gene expression by facilitating the production and processing of ribosomal (r)RNA for ribosome biogenesis. Here, we summarise the current findings on how RNAPII influences nucleolar structure and function. We describe how RNAPII-dependent lncRNA can both promote nucleolar integrity and inhibit ribosomal (r)RNA synthesis by modulating the availability of rRNA synthesis factors in trans. Surprisingly, some lncRNA transcripts can directly originate from nucleolar loci and function in cis. The nucleolar intergenic spacer (IGS), for example, encodes nucleolar transcripts that counteract spurious rRNA synthesis in unperturbed cells. In response to DNA damage, RNAPII-dependent lncRNA originates directly at broken ribosomal (r)DNA loci and is processed into small ncRNA, possibly to modulate DNA repair. Thus, lncRNA-mediated regulation of nucleolar biology occurs by several modes of action and is more direct than anticipated, pointing to an intimate crosstalk of RNA metabolic events.

scholarly journals Murine erythropoietin gene: cloning, expression, and human gene homology.

1986 ◽  
Vol 6 (3) ◽  
pp. 849-858 ◽  
Author(s):  
C B Shoemaker ◽  
L D Mitsock
Keyword(s):  
Amino Acid ◽  
Genomic Library ◽  
Cdna Probe ◽  
Amino Acid Sequences ◽  
Nucleotide Sequence Analysis ◽  
Coding Region ◽  
Transcription Control ◽  
Erythroid Progenitor ◽  
Human Genes ◽  
Cell Expression

The gene for murine erythropoietin (EPO) was isolated from a mouse genomic library with a human EPO cDNA probe. Nucleotide sequence analysis permitted the identification of the murine EPO coding sequence and the prediction of the encoded amino acid sequence based on sequence conservation between the mouse and human EPO genes. Both the coding DNA and the amino acid sequences were 80% conserved between the two species. Transformation of COS-1 cells with a mammalian cell expression vector containing the murine EPO coding region resulted in secretion of murine EPO with biological activity on both murine and human erythroid progenitor cells. The transcription start site for the murine EPO gene in kidneys was determined. This permitted tentative identification of the transcription control region. The region included 140 base pairs upstream of the cap site which was over 90% conserved between the murine and human genes. Surprisingly, the first intron and much of the 5'- and 3'-untranslated sequences were also substantially conserved between the genes of the two species.

UVB radiation-induced cancer predisposition in Cockayne syndrome group A (Csa) mutant mice

DNA Repair ◽  
2002 ◽  
Vol 1 (2) ◽  
pp. 143-157 ◽  
Author(s):  
Gijsbertus T.J van der Horst ◽  
Lisiane Meira ◽  
Theo G.M.F Gorgels ◽  
Jan de Wit ◽  
Susana Velasco-Miguel ◽  
...  
Keyword(s):  
Cockayne Syndrome ◽  
Cancer Predisposition ◽  
Mutant Mice ◽  
Uvb Radiation ◽  
Radiation Induced Cancer ◽  
Group A ◽  
Radiation Induced
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