101
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Suh H, Hazelbaker DZ, Soares LM, Buratowski S. The C-terminal domain of Rpb1 functions on other RNA polymerase II subunits. Mol Cell 2013; 51:850-8. [PMID: 24035501 DOI: 10.1016/j.molcel.2013.08.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Revised: 07/09/2013] [Accepted: 08/02/2013] [Indexed: 10/26/2022]
Abstract
The C-terminal domain (CTD) of Rpb1, the largest subunit of RNA polymerase II (RNApII), coordinates recruitment of RNA- and chromatin-modifying factors to transcription complexes. It is unclear whether the CTD communicates with the catalytic core region of Rpb1 and thus must be physically connected, or instead can function as an independent domain. To address this question, CTD was transferred to other RNApII subunits. Fusions to Rpb4 or Rpb6, two RNApII subunits located near the original position of CTD, support viability in a strain carrying a truncated Rpb1. In contrast, CTD fusion to Rpb9 on the other side of RNApII does not. Rpb4-CTD and Rpb6-CTD proteins are functional for phosphorylation and recruitment of various factors, albeit with some restrictions and minor defects. Normal CTD functions are not transferred to RNApI or RNApIII by Rbp6-CTD. These results show that, with some spatial constraints, CTD can function even when disconnected from Rpb1.
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Affiliation(s)
- Hyunsuk Suh
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
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102
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Aristizabal MJ, Negri GL, Benschop JJ, Holstege FCP, Krogan NJ, Kobor MS. High-throughput genetic and gene expression analysis of the RNAPII-CTD reveals unexpected connections to SRB10/CDK8. PLoS Genet 2013; 9:e1003758. [PMID: 24009531 PMCID: PMC3757075 DOI: 10.1371/journal.pgen.1003758] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 07/15/2013] [Indexed: 12/21/2022] Open
Abstract
The C-terminal domain (CTD) of RNA polymerase II (RNAPII) is composed of heptapeptide repeats, which play a key regulatory role in gene expression. Using genetic interaction, chromatin immunoprecipitation followed by microarrays (ChIP-on-chip) and mRNA expression analysis, we found that truncating the CTD resulted in distinct changes to cellular function. Truncating the CTD altered RNAPII occupancy, leading to not only decreases, but also increases in mRNA levels. The latter were largely mediated by promoter elements and in part were linked to the transcription factor Rpn4. The mediator subunit Cdk8 was enriched at promoters of these genes, and its removal not only restored normal mRNA and RNAPII occupancy levels, but also reduced the abnormally high cellular amounts of Rpn4. This suggested a positive role of Cdk8 in relationship to RNAPII, which contrasted with the observed negative role at the activated INO1 gene. Here, loss of CDK8 suppressed the reduced mRNA expression and RNAPII occupancy levels of CTD truncation mutants.
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Affiliation(s)
- Maria J. Aristizabal
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Gian Luca Negri
- School of Medicine and Medical Science, University College Dublin, Belfield, Dublin, Ireland
| | - Joris J. Benschop
- Molecular Cancer Research, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Frank C. P. Holstege
- Molecular Cancer Research, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Nevan J. Krogan
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, California, United States of America
| | - Michael S. Kobor
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
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103
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Affiliation(s)
- Dirk Eick
- Department of Molecular Epigenetics, Helmholtz Center Munich and Center for Integrated Protein Science Munich (CIPSM), Marchioninistrasse 25, 81377 Munich,
Germany
| | - Matthias Geyer
- Center of Advanced European Studies and Research, Group Physical Biochemistry,
Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
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104
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Cap completion and C-terminal repeat domain kinase recruitment underlie the initiation-elongation transition of RNA polymerase II. Mol Cell Biol 2013; 33:3805-16. [PMID: 23878398 DOI: 10.1128/mcb.00361-13] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
After transcription initiation, RNA polymerase (Pol) II escapes from the promoter and recruits elongation factors. The molecular basis for the initiation-elongation factor exchange during this transition remains poorly understood. Here, we used chromatin immunoprecipitation (ChIP) to elucidate the initiation-elongation transition of Pol II in the budding yeast Saccharomyces cerevisiae. We show that the early Pol II elongation factor Spt5 contributes to stable recruitment of the mRNA capping enzymes Cet1, Ceg1, and Abd1. Genome-wide occupancy for Cet1 and Ceg1 is restricted to the transcription start site (TSS), whereas occupancy for Abd1 peaks at ~110 nucleotides downstream, and occupancy for the cap-binding complex (CBC) rises subsequently. Abd1 and CBC are important for recruitment of the kinases Ctk1 and Bur1, which promote elongation and capping enzyme release. These results suggest that cap completion stimulates productive Pol II elongation.
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105
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Jeronimo C, Bataille AR, Robert F. The Writers, Readers, and Functions of the RNA Polymerase II C-Terminal Domain Code. Chem Rev 2013; 113:8491-522. [DOI: 10.1021/cr4001397] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Célia Jeronimo
- Institut de recherches cliniques de Montréal, Montréal, Québec,
Canada H2W 1R7
| | - Alain R. Bataille
- Institut de recherches cliniques de Montréal, Montréal, Québec,
Canada H2W 1R7
| | - François Robert
- Institut de recherches cliniques de Montréal, Montréal, Québec,
Canada H2W 1R7
- Département
de Médecine,
Faculté de Médecine, Université de Montréal, Montréal, Québec,
Canada H3T 1J4
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106
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Affiliation(s)
- C A Niño
- Institut Jacques Monod, Paris Diderot University , Sorbonne Paris Cité, CNRS UMR7592, Equipe labellisée Ligue contre le cancer, 15 rue Hélène Brion, 75205 Paris Cedex 13, France
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107
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Pandya-Jones A, Bhatt DM, Lin CH, Tong AJ, Smale ST, Black DL. Splicing kinetics and transcript release from the chromatin compartment limit the rate of Lipid A-induced gene expression. RNA (NEW YORK, N.Y.) 2013; 19:811-27. [PMID: 23616639 PMCID: PMC3683915 DOI: 10.1261/rna.039081.113] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 03/13/2013] [Indexed: 05/26/2023]
Abstract
The expression of eukaryotic mRNAs is achieved though an intricate series of molecular processes that provide many steps for regulating the production of a final gene product. However, the relationships between individual steps in mRNA biosynthesis and the rates at which they occur are poorly understood. By applying RNA-seq to chromatin-associated and soluble nucleoplasmic fractions of RNA from Lipid A-stimulated macrophages, we examined the timing of exon ligation and transcript release from chromatin relative to the induction of transcription. We find that for a subset of genes in the Lipid A response, the ligation of certain exon pairs is delayed relative to the synthesis of the complete transcript. In contrast, 3' end cleavage and polyadenylation occur rapidly once transcription extends through the cleavage site. Our data indicate that these transcripts with delayed splicing are not released from the chromatin fraction until all the introns have been excised. These unusual kinetics result in a chromatin-associated pool of completely transcribed and 3'-processed transcripts that are not yet fully spliced. We also find that long introns containing repressed exons that will be excluded from the final mRNA are excised particularly slowly relative to other introns in a transcript. These results indicate that the kinetics of splicing and transcript release contribute to the timing of expression for multiple genes of the inflammatory response.
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Affiliation(s)
- Amy Pandya-Jones
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, California 90025, USA
- Molecular Biology Institute, University of California, Los Angeles, California 90025, USA
| | - Dev M. Bhatt
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, California 90025, USA
- Molecular Biology Institute, University of California, Los Angeles, California 90025, USA
| | - Chia-Ho Lin
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, California 90025, USA
| | - Ann-Jay Tong
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, California 90025, USA
- Molecular Biology Institute, University of California, Los Angeles, California 90025, USA
| | - Stephen T. Smale
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, California 90025, USA
- Molecular Biology Institute, University of California, Los Angeles, California 90025, USA
| | - Douglas L. Black
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, California 90025, USA
- Molecular Biology Institute, University of California, Los Angeles, California 90025, USA
- Howard Hughes Medical Institute, University of California, Los Angeles, California 90025, USA
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108
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Abstract
Precursor mRNA splicing is one of the most highly regulated processes in metazoan species. In addition to generating vast repertoires of RNAs and proteins, splicing has a profound impact on other gene regulatory layers, including mRNA transcription, turnover, transport, and translation. Conversely, factors regulating chromatin and transcription complexes impact the splicing process. This extensive crosstalk between gene regulatory layers takes advantage of dynamic spatial, physical, and temporal organizational properties of the cell nucleus, and further emphasizes the importance of developing a multidimensional understanding of splicing control.
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109
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Hsin JP, Manley JL. The RNA polymerase II CTD coordinates transcription and RNA processing. Genes Dev 2012; 26:2119-37. [PMID: 23028141 DOI: 10.1101/gad.200303.112] [Citation(s) in RCA: 452] [Impact Index Per Article: 37.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The C-terminal domain (CTD) of the RNA polymerase II largest subunit consists of multiple heptad repeats (consensus Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7), varying in number from 26 in yeast to 52 in vertebrates. The CTD functions to help couple transcription and processing of the nascent RNA and also plays roles in transcription elongation and termination. The CTD is subject to extensive post-translational modification, most notably phosphorylation, during the transcription cycle, which modulates its activities in the above processes. Therefore, understanding the nature of CTD modifications, including how they function and how they are regulated, is essential to understanding the mechanisms that control gene expression. While the significance of phosphorylation of Ser2 and Ser5 residues has been studied and appreciated for some time, several additional modifications have more recently been added to the CTD repertoire, and insight into their function has begun to emerge. Here, we review findings regarding modification and function of the CTD, highlighting the important role this unique domain plays in coordinating gene activity.
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Affiliation(s)
- Jing-Ping Hsin
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
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110
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Mitchell JA, Clay I, Umlauf D, Chen CY, Moir CA, Eskiw CH, Schoenfelder S, Chakalova L, Nagano T, Fraser P. Nuclear RNA sequencing of the mouse erythroid cell transcriptome. PLoS One 2012; 7:e49274. [PMID: 23209567 PMCID: PMC3510205 DOI: 10.1371/journal.pone.0049274] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Accepted: 10/08/2012] [Indexed: 12/31/2022] Open
Abstract
In addition to protein coding genes a substantial proportion of mammalian genomes are transcribed. However, most transcriptome studies investigate steady-state mRNA levels, ignoring a considerable fraction of the transcribed genome. In addition, steady-state mRNA levels are influenced by both transcriptional and posttranscriptional mechanisms, and thus do not provide a clear picture of transcriptional output. Here, using deep sequencing of nuclear RNAs (nucRNA-Seq) in parallel with chromatin immunoprecipitation sequencing (ChIP-Seq) of active RNA polymerase II, we compared the nuclear transcriptome of mouse anemic spleen erythroid cells with polymerase occupancy on a genome-wide scale. We demonstrate that unspliced transcripts quantified by nucRNA-seq correlate with primary transcript frequencies measured by RNA FISH, but differ from steady-state mRNA levels measured by poly(A)-enriched RNA-seq. Highly expressed protein coding genes showed good correlation between RNAPII occupancy and transcriptional output; however, genome-wide we observed a poor correlation between transcriptional output and RNAPII association. This poor correlation is due to intergenic regions associated with RNAPII which correspond with transcription factor bound regulatory regions and a group of stable, nuclear-retained long non-coding transcripts. In conclusion, sequencing the nuclear transcriptome provides an opportunity to investigate the transcriptional landscape in a given cell type through quantification of unspliced primary transcripts and the identification of nuclear-retained long non-coding RNAs.
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Affiliation(s)
- Jennifer A Mitchell
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada.
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111
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Lenasi T, Barboric M. Mutual relationships between transcription and pre-mRNA processing in the synthesis of mRNA. WILEY INTERDISCIPLINARY REVIEWS-RNA 2012. [PMID: 23184646 DOI: 10.1002/wrna.1148] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The generation of messenger RNA (mRNA) in eukaryotes is achieved by transcription from the DNA template and pre-mRNA processing reactions of capping, splicing, and polyadenylation. Although RNA polymerase II (RNAPII) catalyzes the synthesis of pre-mRNA, it also serves as a principal coordinator of the processing reactions in the course of transcription. In this review, we focus on the interplay between transcription and cotranscriptional pre-mRNA maturation events, mediated by the recruitment of RNA processing factors to differentially phosphorylated C-terminal domain of Rbp1, the largest subunit of RNAPII. Furthermore, we highlight the bidirectional nature of the interplay by discussing the impact of RNAPII kinetics on pre-mRNA processing as well as how the processing events reach back to different phases of gene transcription.
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Affiliation(s)
- Tina Lenasi
- Institute of Biomedicine, Biochemistry and Developmental Biology, University of Helsinki, Helsinki, Finland.
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112
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Dujardin G, Lafaille C, Petrillo E, Buggiano V, Gómez Acuña LI, Fiszbein A, Godoy Herz MA, Nieto Moreno N, Muñoz MJ, Alló M, Schor IE, Kornblihtt AR. Transcriptional elongation and alternative splicing. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2012; 1829:134-40. [PMID: 22975042 DOI: 10.1016/j.bbagrm.2012.08.005] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 08/23/2012] [Accepted: 08/29/2012] [Indexed: 12/29/2022]
Abstract
Alternative splicing has emerged as a key contributor to proteome diversity, highlighting the importance of understanding its regulation. In recent years it became apparent that splicing is predominantly cotranscriptional, allowing for crosstalk between these two nuclear processes. We discuss some of the links between transcription and splicing, with special emphasis on the role played by transcription elongation in the regulation of alternative splicing events and in particular the kinetic model of alternative splicing regulation. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.
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Affiliation(s)
- Gwendal Dujardin
- Departamento de Fisiología, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
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113
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Heidemann M, Hintermair C, Voß K, Eick D. Dynamic phosphorylation patterns of RNA polymerase II CTD during transcription. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2012; 1829:55-62. [PMID: 22982363 DOI: 10.1016/j.bbagrm.2012.08.013] [Citation(s) in RCA: 202] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 08/09/2012] [Accepted: 08/29/2012] [Indexed: 12/27/2022]
Abstract
The eukaryotic RNA polymerase II (RNAPII) catalyzes the transcription of all protein encoding genes and is also responsible for the generation of small regulatory RNAs. RNAPII has evolved a unique domain composed of heptapeptide repeats with the consensus sequence Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7 at the C-terminus (CTD) of its largest subunit (Rpb1). Dynamic phosphorylation patterns of serine residues in CTD during gene transcription coordinate the recruitment of factors to the elongating RNAPII and to the nascent transcript. Recent studies identified threonine 4 and tyrosine 1 as new CTD modifications and thereby expanded the "CTD code". In this review, we focus on CTD phosphorylation and its function in the RNAPII transcription cycle. We also discuss in detail the limitations of the phosphospecific CTD antibodies, which are used in all studies. This article is part of a Special Issue entitled: RNA Polymerase II Transcript Elongation.
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Affiliation(s)
- Martin Heidemann
- Department of Molecular Epigenetics, Center for Integrated Protein Science Munich, Munich, Germany
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114
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Morgado A, Almeida F, Teixeira A, Silva AL, Romão L. Unspliced precursors of NMD-sensitive β-globin transcripts exhibit decreased steady-state levels in erythroid cells. PLoS One 2012; 7:e38505. [PMID: 22675570 PMCID: PMC3366927 DOI: 10.1371/journal.pone.0038505] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 05/07/2012] [Indexed: 11/19/2022] Open
Abstract
Nonsense-mediated mRNA decay (NMD) is a quality control mechanism that detects and rapidly degrades mRNAs carrying premature translation-termination codons (PTCs). Mammalian NMD depends on both splicing and translation, and requires recognition of the premature stop codon by the cytoplasmic ribosomes. Surprisingly, some published data have suggested that nonsense codons may also affect the nuclear metabolism of the nonsense-mutated transcripts. To determine if nonsense codons could influence nuclear events, we have directly assessed the steady-state levels of the unspliced transcripts of wild-type and PTC-containing human β-globin genes stably transfected in mouse erythroleukemia (MEL) cells, after erythroid differentiation induction, or in HeLa cells. Our analyses by ribonuclease protection assays and reverse transcription-coupled quantitative PCR show that β-globin pre-mRNAs carrying NMD-competent PTCs, but not those containing a NMD-resistant PTC, exhibit a significant decrease in their steady-state levels relatively to the wild-type or to a missense-mutated β-globin pre-mRNA. On the contrary, in HeLa cells, human β-globin pre-mRNAs carrying NMD-competent PTCs accumulate at normal levels. Functional analyses of these pre-mRNAs in MEL cells demonstrate that their low steady-state levels do not reflect significantly lower pre-mRNA stabilities when compared to the normal control. Furthermore, our results also provide evidence that the relative splicing efficiencies of intron 1 and 2 are unaffected. This set of data highlights potential nuclear pathways that might be promoter- and/or cell line-specific, which recognize the NMD-sensitive transcripts as abnormal. These specialized nuclear pathway(s) may be superimposed on the general NMD mechanism.
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Affiliation(s)
- Ana Morgado
- Departamento de Genética, Instituto Nacional de Saúde Dr. Ricardo Jorge, Lisboa, Portugal
- BioFIG–Center for Biodiversity, Functional and Integrative Genomics, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Fátima Almeida
- Departamento de Genética, Instituto Nacional de Saúde Dr. Ricardo Jorge, Lisboa, Portugal
| | - Alexandre Teixeira
- Departamento de Genética, Instituto Nacional de Saúde Dr. Ricardo Jorge, Lisboa, Portugal
- Centro de Investigação em Genética Molecular Humana, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisboa, Portugal
| | - Ana Luísa Silva
- Departamento de Genética, Instituto Nacional de Saúde Dr. Ricardo Jorge, Lisboa, Portugal
- BioFIG–Center for Biodiversity, Functional and Integrative Genomics, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Luísa Romão
- Departamento de Genética, Instituto Nacional de Saúde Dr. Ricardo Jorge, Lisboa, Portugal
- BioFIG–Center for Biodiversity, Functional and Integrative Genomics, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
- * E-mail:
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115
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Abstract
The largest subunit of RNA polymerase II, Rpb1, contains an unusual C-terminal domain (CTD) composed of numerous repeats of the YSPTSPS consensus sequence. This sequence is the target of post-translational modifications such as phosphorylation, glycosylation, methylation and transitions between stereoisomeric states, resulting in a vast combinatorial potential referred to as the CTD code. In order to gain insight into the biological significance of this code, several studies recently reported the genome-wide distribution of some of these modified polymerases and associated factors in either fission yeast (Schizosaccharomyces pombe) or budding yeast (Saccharomyces cerevisiae). The resulting occupancy maps reveal that a general RNA polymerase II transcription complex exists and undergoes uniform transitions from initiation to elongation to termination. Nevertheless, CTD phosphorylation dynamics result in a gene-specific effect on mRNA expression. In this review, we focus on the gene-specific requirement of CTD phosphorylation and discuss in more detail the case of serine 2 phosphorylation (S2P) within the CTD, a modification that is dispensable for general transcription in fission yeast but strongly affects transcription reprogramming and cell differentiation in response to environmental cues. The recent discovery of Cdk12 as a genuine CTD S2 kinase and its requirement for gene-specific expression are discussed in the wider context of metazoa.
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Affiliation(s)
- Julie Drogat
- Namur Research College-NARC, Rue de Bruxelles 61, 5000 Namur, Belgium
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116
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Bataille AR, Jeronimo C, Jacques PÉ, Laramée L, Fortin MÈ, Forest A, Bergeron M, Hanes SD, Robert F. A universal RNA polymerase II CTD cycle is orchestrated by complex interplays between kinase, phosphatase, and isomerase enzymes along genes. Mol Cell 2012; 45:158-70. [PMID: 22284676 DOI: 10.1016/j.molcel.2011.11.024] [Citation(s) in RCA: 175] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Revised: 08/18/2011] [Accepted: 11/04/2011] [Indexed: 11/17/2022]
Abstract
Transcription by RNA polymerase II (RNAPII) is coupled to mRNA processing and chromatin modifications via the C-terminal domain (CTD) of its largest subunit, consisting of multiple repeats of the heptapeptide YSPTSPS. Pioneering studies showed that CTD serines are differentially phosphorylated along genes in a prescribed pattern during the transcription cycle. Genome-wide analyses challenged this idea, suggesting that this cycle is not uniform among different genes. Moreover, the respective role of enzymes responsible for CTD modifications remains controversial. Here, we systematically profiled the location of the RNAPII phosphoisoforms in wild-type cells and mutants for most CTD modifying enzymes. Together with results of in vitro assays, these data reveal a complex interplay between the modifying enzymes, and provide evidence that the CTD cycle is uniform across genes. We also identify Ssu72 as the Ser7 phosphatase and show that proline isomerization is a key regulator of CTD dephosphorylation at the end of genes.
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Affiliation(s)
- Alain R Bataille
- Institut de recherches cliniques de Montréal, Montréal, QC H2W 1R7, Canada
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117
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Hajheidari M, Farrona S, Huettel B, Koncz Z, Koncz C. CDKF;1 and CDKD protein kinases regulate phosphorylation of serine residues in the C-terminal domain of Arabidopsis RNA polymerase II. THE PLANT CELL 2012; 24:1626-1642. [PMID: 22547781 PMCID: PMC3398568 DOI: 10.1105/tpc.112.096834;pmid:2254778] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Revised: 04/01/2012] [Accepted: 04/11/2012] [Indexed: 05/29/2023]
Abstract
Phosphorylation of conserved Y₁S₂P₃T₄S₅P₆S₇ repeats in the C-terminal domain of largest subunit of RNA polymerase II (RNAPII CTD) plays a central role in the regulation of transcription and cotranscriptional RNA processing. Here, we show that Ser phosphorylation of Arabidopsis thaliana RNAPII CTD is governed by CYCLIN-DEPENDENT KINASE F;1 (CDKF;1), a unique plant-specific CTD S₇-kinase. CDKF;1 is required for in vivo activation of functionally redundant CYCLIN-DEPENDENT KINASE Ds (CDKDs), which are major CTD S₅-kinases that also phosphorylate in vitro the S₂ and S₇ CTD residues. Inactivation of CDKF;1 causes extreme dwarfism and sterility. Inhibition of CTD S₇-phosphorylation in germinating cdkf;1 seedlings is accompanied by 3'-polyadenylation defects of pre-microRNAs and transcripts encoding key regulators of small RNA biogenesis pathways. The cdkf;1 mutation also decreases the levels of both precursor and mature small RNAs without causing global downregulation of the protein-coding transcriptome and enhances the removal of introns that carry pre-microRNA stem-loops. A triple cdkd knockout mutant is not viable, but a combination of null and weak cdkd;3 alleles in a triple cdkd123* mutant permits semidwarf growth. Germinating cdkd123* seedlings show reduced CTD S₅-phosphorylation, accumulation of uncapped precursor microRNAs, and a parallel decrease in mature microRNA. During later development of cdkd123* seedlings, however, S₇-phosphorylation and unprocessed small RNA levels decline similarly as in the cdkf;1 mutant. Taken together, cotranscriptional processing and stability of a set of small RNAs and transcripts involved in their biogenesis are sensitive to changes in the phosphorylation of RNAPII CTD by CDKF;1 and CDKDs.
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MESH Headings
- Arabidopsis/enzymology
- Arabidopsis/genetics
- Arabidopsis/growth & development
- Arabidopsis Proteins/chemistry
- Arabidopsis Proteins/genetics
- Arabidopsis Proteins/metabolism
- Biosynthetic Pathways/genetics
- Cyclin-Dependent Kinases/metabolism
- Down-Regulation/genetics
- Gene Expression Regulation, Plant
- Genes, Plant/genetics
- MicroRNAs/genetics
- MicroRNAs/metabolism
- Mutation/genetics
- Nucleic Acid Hybridization
- Phosphorylation
- Phosphoserine/metabolism
- Protein Serine-Threonine Kinases/metabolism
- Protein Structure, Tertiary
- RNA Caps/metabolism
- RNA Polymerase II/chemistry
- RNA Polymerase II/metabolism
- RNA Precursors/metabolism
- RNA Processing, Post-Transcriptional/genetics
- RNA Splicing/genetics
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Plant/biosynthesis
- RNA, Plant/genetics
- RNA, Small Interfering/genetics
- RNA, Small Interfering/metabolism
- RNA, Untranslated/genetics
- Transcription, Genetic
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Affiliation(s)
- Mohsen Hajheidari
- Department of Plant Developmental Biology, Max-Planck Institute for Plant Breeding Research, D-50829 Cologne, Germany
| | - Sara Farrona
- Department of Plant Developmental Biology, Max-Planck Institute for Plant Breeding Research, D-50829 Cologne, Germany
| | - Bruno Huettel
- Max Planck Genome Centre, Max-Planck Institute for Plant Breeding Research, D-50829 Cologne, Germany
| | - Zsuzsa Koncz
- Department of Plant Developmental Biology, Max-Planck Institute for Plant Breeding Research, D-50829 Cologne, Germany
| | - Csaba Koncz
- Department of Plant Developmental Biology, Max-Planck Institute for Plant Breeding Research, D-50829 Cologne, Germany
- Institute of Plant Biology, Biological Research Center of Hungarian Academy of Sciences, H-6723 Szeged, Hungary
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118
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Hajheidari M, Farrona S, Huettel B, Koncz Z, Koncz C. CDKF;1 and CDKD protein kinases regulate phosphorylation of serine residues in the C-terminal domain of Arabidopsis RNA polymerase II. THE PLANT CELL 2012; 24:1626-42. [PMID: 22547781 PMCID: PMC3398568 DOI: 10.1105/tpc.112.096834] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Revised: 04/01/2012] [Accepted: 04/11/2012] [Indexed: 05/19/2023]
Abstract
Phosphorylation of conserved Y₁S₂P₃T₄S₅P₆S₇ repeats in the C-terminal domain of largest subunit of RNA polymerase II (RNAPII CTD) plays a central role in the regulation of transcription and cotranscriptional RNA processing. Here, we show that Ser phosphorylation of Arabidopsis thaliana RNAPII CTD is governed by CYCLIN-DEPENDENT KINASE F;1 (CDKF;1), a unique plant-specific CTD S₇-kinase. CDKF;1 is required for in vivo activation of functionally redundant CYCLIN-DEPENDENT KINASE Ds (CDKDs), which are major CTD S₅-kinases that also phosphorylate in vitro the S₂ and S₇ CTD residues. Inactivation of CDKF;1 causes extreme dwarfism and sterility. Inhibition of CTD S₇-phosphorylation in germinating cdkf;1 seedlings is accompanied by 3'-polyadenylation defects of pre-microRNAs and transcripts encoding key regulators of small RNA biogenesis pathways. The cdkf;1 mutation also decreases the levels of both precursor and mature small RNAs without causing global downregulation of the protein-coding transcriptome and enhances the removal of introns that carry pre-microRNA stem-loops. A triple cdkd knockout mutant is not viable, but a combination of null and weak cdkd;3 alleles in a triple cdkd123* mutant permits semidwarf growth. Germinating cdkd123* seedlings show reduced CTD S₅-phosphorylation, accumulation of uncapped precursor microRNAs, and a parallel decrease in mature microRNA. During later development of cdkd123* seedlings, however, S₇-phosphorylation and unprocessed small RNA levels decline similarly as in the cdkf;1 mutant. Taken together, cotranscriptional processing and stability of a set of small RNAs and transcripts involved in their biogenesis are sensitive to changes in the phosphorylation of RNAPII CTD by CDKF;1 and CDKDs.
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MESH Headings
- Arabidopsis/enzymology
- Arabidopsis/genetics
- Arabidopsis/growth & development
- Arabidopsis Proteins/chemistry
- Arabidopsis Proteins/genetics
- Arabidopsis Proteins/metabolism
- Biosynthetic Pathways/genetics
- Cyclin-Dependent Kinases/metabolism
- Down-Regulation/genetics
- Gene Expression Regulation, Plant
- Genes, Plant/genetics
- MicroRNAs/genetics
- MicroRNAs/metabolism
- Mutation/genetics
- Nucleic Acid Hybridization
- Phosphorylation
- Phosphoserine/metabolism
- Protein Serine-Threonine Kinases/metabolism
- Protein Structure, Tertiary
- RNA Caps/metabolism
- RNA Polymerase II/chemistry
- RNA Polymerase II/metabolism
- RNA Precursors/metabolism
- RNA Processing, Post-Transcriptional/genetics
- RNA Splicing/genetics
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Plant/biosynthesis
- RNA, Plant/genetics
- RNA, Small Interfering/genetics
- RNA, Small Interfering/metabolism
- RNA, Untranslated/genetics
- Transcription, Genetic
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Affiliation(s)
- Mohsen Hajheidari
- Department of Plant Developmental Biology, Max-Planck Institute for Plant Breeding Research, D-50829 Cologne, Germany
| | - Sara Farrona
- Department of Plant Developmental Biology, Max-Planck Institute for Plant Breeding Research, D-50829 Cologne, Germany
| | - Bruno Huettel
- Max Planck Genome Centre, Max-Planck Institute for Plant Breeding Research, D-50829 Cologne, Germany
| | - Zsuzsa Koncz
- Department of Plant Developmental Biology, Max-Planck Institute for Plant Breeding Research, D-50829 Cologne, Germany
| | - Csaba Koncz
- Department of Plant Developmental Biology, Max-Planck Institute for Plant Breeding Research, D-50829 Cologne, Germany
- Institute of Plant Biology, Biological Research Center of Hungarian Academy of Sciences, H-6723 Szeged, Hungary
- Address correspondence to
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119
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Zhang DW, Rodríguez-Molina JB, Tietjen JR, Nemec CM, Ansari AZ. Emerging Views on the CTD Code. GENETICS RESEARCH INTERNATIONAL 2012; 2012:347214. [PMID: 22567385 PMCID: PMC3335543 DOI: 10.1155/2012/347214] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Accepted: 11/03/2011] [Indexed: 12/21/2022]
Abstract
The C-terminal domain (CTD) of RNA polymerase II (Pol II) consists of conserved heptapeptide repeats that function as a binding platform for different protein complexes involved in transcription, RNA processing, export, and chromatin remodeling. The CTD repeats are subject to sequential waves of posttranslational modifications during specific stages of the transcription cycle. These patterned modifications have led to the postulation of the "CTD code" hypothesis, where stage-specific patterns define a spatiotemporal code that is recognized by the appropriate interacting partners. Here, we highlight the role of CTD modifications in directing transcription initiation, elongation, and termination. We examine the major readers, writers, and erasers of the CTD code and examine the relevance of describing patterns of posttranslational modifications as a "code." Finally, we discuss major questions regarding the function of the newly discovered CTD modifications and the fundamental insights into transcription regulation that will necessarily emerge upon addressing those challenges.
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Affiliation(s)
- David W. Zhang
- Department of Biochemistry, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, USA
| | - Juan B. Rodríguez-Molina
- Department of Biochemistry, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, USA
| | - Joshua R. Tietjen
- Department of Biochemistry, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, USA
| | - Corey M. Nemec
- Department of Biochemistry, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, USA
| | - Aseem Z. Ansari
- Department of Biochemistry, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, USA
- Genome Center of Wisconsin, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, USA
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120
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mRNA 3' end processing factors: a phylogenetic comparison. Comp Funct Genomics 2012; 2012:876893. [PMID: 22400011 PMCID: PMC3287031 DOI: 10.1155/2012/876893] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 09/22/2011] [Accepted: 10/11/2011] [Indexed: 01/23/2023] Open
Abstract
Almost all eukaryotic mRNAs possess 3′ ends with a polyadenylate (poly(A)) tail. This poly(A) tail is not encoded in the genome but is added by the process of polyadenylation. Polyadenylation is a two-step process, and this process is accomplished by multisubunit protein factors. Here, we comprehensively compare the protein machinery responsible for polyadenylation of mRNAs across many evolutionary divergent species, and we have found these protein factors to be remarkably conserved in nature. These data suggest that polyadenylation of mRNAs is an ancient process.
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121
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Nuclear export as a key arbiter of "mRNA identity" in eukaryotes. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2012; 1819:566-77. [PMID: 22248619 DOI: 10.1016/j.bbagrm.2011.12.012] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Revised: 12/23/2011] [Accepted: 12/29/2011] [Indexed: 01/15/2023]
Abstract
Over the past decade, various studies have indicated that most of the eukaryotic genome is transcribed at some level. The pervasiveness of transcription might seem surprising when one considers that only a quarter of the human genome comprises genes (including exons and introns) and less than 2% codes for protein. This conundrum is partially explained by the unique evolutionary pressures that are imposed on species with small population sizes, such as eukaryotes. These conditions promote the expansion of introns and non-functional intergenic DNA, and the accumulation of cryptic transcriptional start sites. As a result, the eukaryotic gene expression machinery must effectively evaluate whether or not a transcript has all the hallmarks of a protein-coding mRNA. If a transcript contains these features, then positive feedback loops are activated to further stimulate its transcription, processing, nuclear export and ultimately, translation. However if a transcript lacks features associated with "mRNA identity", then the RNA is degraded and/or used to inhibit further transcription and translation of the gene. Here we discuss how mRNA identity is assessed by the nuclear export machinery in order to extract meaningful information from the eukaryotic genome. In the process, we provide an explanation of why certain sequences that are enriched in protein-coding genes, such as the signal sequence coding region, promote mRNA nuclear export in vertebrates. This article is part of a Special Issue entitled: Nuclear Transport and RNA Processing.
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122
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Gokhale S, Nyayanit D, Gadgil C. A systems view of the protein expression process. SYSTEMS AND SYNTHETIC BIOLOGY 2011. [PMID: 23205157 DOI: 10.1007/s11693-011-9088-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
UNLABELLED Many biological processes are regulated by changing the concentration and activity of proteins. The presence of a protein at a given subcellular location at a given time with a certain conformation is the result of an apparently sequential process. The rate of protein formation is influenced by chromatin state, and the rates of transcription, translation, and degradation. There is an exquisite control system where each stage of the process is controlled both by seemingly unregulated proteins as well as through feedbacks mediated by RNA and protein products. Here we review the biological facts and mathematical models for each stage of the protein production process. We conclude that advances in experimental techniques leading to a detailed description of the process have not been matched by mathematical models that represent the details of the process and facilitate analysis. Such an exercise is the first step towards development of a framework for a systems biology analysis of the protein production process. ELECTRONIC SUPPLEMENTARY MATERIAL The online version of this article (doi:10.1007/s11693-011-9088-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sucheta Gokhale
- Chemical Engineering Division, CSIR-National Chemical Laboratory, Pune, 411008 India
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123
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Bartkowiak B, Mackellar AL, Greenleaf AL. Updating the CTD Story: From Tail to Epic. GENETICS RESEARCH INTERNATIONAL 2011; 2011:623718. [PMID: 22567360 PMCID: PMC3335468 DOI: 10.4061/2011/623718] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Accepted: 08/10/2011] [Indexed: 12/03/2022]
Abstract
Eukaryotic RNA polymerase II (RNAPII) not only synthesizes mRNA but also coordinates transcription-related processes via its unique C-terminal repeat domain (CTD). The CTD is an RNAPII-specific protein segment consisting of repeating heptads with the consensus sequence Y1S2P3T4S5P6S7 that has been shown to be extensively post-transcriptionally modified in a coordinated, but complicated, manner. Recent discoveries of new modifications, kinases, and binding proteins have challenged previously established paradigms. In this paper, we examine results and implications of recent studies related to modifications of the CTD and the respective enzymes; we also survey characterizations of new CTD-binding proteins and their associated processes and new information regarding known CTD-binding proteins. Finally, we bring into focus new results that identify two additional CTD-associated processes: nucleocytoplasmic transport of mRNA and DNA damage and repair.
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Affiliation(s)
- Bartlomiej Bartkowiak
- Department of Biochemistry and Center for RNA Biology, Duke University Medical Center, Durham, NC 27710, USA
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124
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de la Mata M, Muñoz MJ, Alló M, Fededa JP, Schor IE, Kornblihtt AR. RNA Polymerase II Elongation at the Crossroads of Transcription and Alternative Splicing. GENETICS RESEARCH INTERNATIONAL 2011; 2011:309865. [PMID: 22567350 PMCID: PMC3335476 DOI: 10.4061/2011/309865] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Accepted: 06/23/2011] [Indexed: 11/20/2022]
Abstract
The elongation phase of transcription lies at the core of several simultaneous and coupled events leading to alternative splicing regulation. Although underestimated in the past, it is at this phase of the transcription cycle where complexes affecting the transcription machinery itself, chromatin structure, posttranscriptional gene regulation and pre-mRNA processing converge to regulate each other or simply to consolidate higher-order complexes and functions. This paper focuses on the multiple processes that take place during transcription elongation which ultimately regulate the outcome of alternative splicing decisions.
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Affiliation(s)
- Manuel de la Mata
- Laboratorio de Fisiología y Biología Molecular, Departamento de Fisiología, Biología Molecular, y Celular, IFIBYNE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, C1428EHA Buenos Aires, Argentina
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125
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David CJ, Boyne AR, Millhouse SR, Manley JL. The RNA polymerase II C-terminal domain promotes splicing activation through recruitment of a U2AF65-Prp19 complex. Genes Dev 2011; 25:972-83. [PMID: 21536736 DOI: 10.1101/gad.2038011] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Pre-mRNA splicing is frequently coupled to transcription by RNA polymerase II (RNAPII). This coupling requires the C-terminal domain of the RNAPII largest subunit (CTD), although the underlying mechanism is poorly understood. Using a biochemical complementation assay, we previously identified an activity that stimulates CTD-dependent splicing in vitro. We purified this activity and found that it consists of a complex of two well-known splicing factors: U2AF65 and the Prp19 complex (PRP19C). We provide evidence that both U2AF65 and PRP19C are required for CTD-dependent splicing activation, that U2AF65 and PRP19C interact both in vitro and in vivo, and that this interaction is required for activation of splicing. Providing the link to the CTD, we show that U2AF65 binds directly to the phosphorylated CTD, and that this interaction results in increased recruitment of U2AF65 and PRP19C to the pre-mRNA. Our results not only provide a mechanism by which the CTD enhances splicing, but also describe unexpected interactions important for splicing and its coupling to transcription.
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Affiliation(s)
- Charles J David
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
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126
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Nagaike T, Logan C, Hotta I, Rozenblatt-Rosen O, Meyerson M, Manley JL. Transcriptional activators enhance polyadenylation of mRNA precursors. Mol Cell 2011; 41:409-18. [PMID: 21329879 DOI: 10.1016/j.molcel.2011.01.022] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Revised: 11/17/2010] [Accepted: 12/24/2010] [Indexed: 12/25/2022]
Abstract
Polyadenylation of mRNA precursors is frequently coupled to transcription by RNA polymerase II. Although this coupling is known to involve interactions with the C-terminal domain of the RNA polymerase II largest subunit, the possible role of other factors is not known. Here we show that a prototypical transcriptional activator, GAL4-VP16, stimulates transcription-coupled polyadenylation in vitro. In the absence of GAL4-VP16, specifically initiated transcripts accumulated but little polyadenylation was observed, while in its presence polyadenylation was strongly enhanced. We further show that this stimulation requires the transcription elongation-associated PAF complex (PAF1c), as PAF1c depletion blocked GAL4-VP16-stimulated polyadenylation. Furthermore, knockdown of PAF subunits by siRNA resulted in decreased 3' cleavage, and nuclear export, of mRNA in vivo. Finally, we show that GAL4-VP16 interacts directly with PAF1c and recruits it to DNA templates. Our results indicate that a transcription activator can stimulate transcription-coupled 3' processing and does so via interaction with PAF1c.
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Affiliation(s)
- Takashi Nagaike
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
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127
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Structural insights to how mammalian capping enzyme reads the CTD code. Mol Cell 2011; 43:299-310. [PMID: 21683636 DOI: 10.1016/j.molcel.2011.06.001] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 04/25/2011] [Accepted: 05/08/2011] [Indexed: 12/18/2022]
Abstract
Physical interaction between the phosphorylated RNA polymerase II carboxyl-terminal domain (CTD) and cellular capping enzymes is required for efficient formation of the 5' mRNA cap, the first modification of nascent mRNA. Here, we report the crystal structure of the RNA guanylyltransferase component of mammalian capping enzyme (Mce) bound to a CTD phosphopeptide. The CTD adopts an extended β-like conformation that docks Tyr1 and Ser5-PO(4) onto the Mce nucleotidyltransferase domain. Structure-guided mutational analysis verified that the Mce-CTD interface is a tunable determinant of CTD binding and stimulation of guanylyltransferase activity, and of Mce function in vivo. The location and composition of the CTD binding site on mammalian capping enzyme is distinct from that of a yeast capping enzyme that recognizes the same CTD primary structure. Thus, capping enzymes from different taxa have evolved different strategies to read the CTD code.
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128
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Structure of the guanylyltransferase domain of human mRNA capping enzyme. Proc Natl Acad Sci U S A 2011; 108:10104-8. [PMID: 21636784 DOI: 10.1073/pnas.1106610108] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The enzyme guanylyltransferase (GTase) plays a central role in the three-step catalytic process of adding an (m7)GpppN cap cotranscriptionally to nascent mRNA (pre-mRNAs). The 5'-mRNA capping process is functionally and evolutionarily conserved from unicellular organisms to human. However, the GTases from viruses and yeast have low amino acid sequence identity (∼25%) with GTases from mammals that, in contrast, are highly conserved (∼98%). We have defined by limited proteolysis of human capping enzyme residues 229-567 as comprising the minimum enzymatically active human GTase (hGTase) domain and have determined the structure by X-ray crystallography. Seven related conformational states of hGTase exist in the crystal. The GTP-binding site is evolutionarily and structurally conserved. The positional variations of the oligonucleotide/oligosaccharide binding fold lid domain over the GTP-binding site provide snapshots of the opening and closing of the active site cleft through a swivel motion. The pattern of conserved surface residues in mammals, but not in yeast, supports the finding that the recognition of the capping apparatus by RNA polymerase II and associated transcription factors is highly conserved in mammals, and the mechanism may differ somewhat from that in yeast. The hGTase structure should help in the design of biochemical and molecular biology experiments to explore the proteinprotein and proteinRNA interactions that ensure regulated transcription of genes in humans and other mammals.
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129
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Pandya-Jones A. Pre-mRNA splicing during transcription in the mammalian system. WILEY INTERDISCIPLINARY REVIEWS-RNA 2011; 2:700-17. [PMID: 21823230 DOI: 10.1002/wrna.86] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Splicing of RNA polymerase II transcripts is a crucial step in gene expression and a key generator of mRNA diversity. Splicing and transcription have generally been studied in isolation, although in vivo pre-mRNA splicing occurs in concert with transcription. The two processes appear to be functionally connected because a number of variables that regulate transcription have been identified as also influencing splicing. However, the mechanisms that couple the two processes are largely unknown. This review highlights the observations that implicate splicing as occurring during transcription and describes the evidence supporting functional interactions between the two processes. I discuss postulated models of how splicing couples to transcription and consider the potential impact that such coupling might have on exon recognition. WIREs RNA 2011 2 700-717 DOI: 10.1002/wrna.86 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Amy Pandya-Jones
- Department of Microbiology, Immunology and Molecular Genetics, University of California Los Angeles (UCLA), USA.
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130
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Helenius K, Yang Y, Tselykh TV, Pessa HKJ, Frilander MJ, Mäkelä TP. Requirement of TFIIH kinase subunit Mat1 for RNA Pol II C-terminal domain Ser5 phosphorylation, transcription and mRNA turnover. Nucleic Acids Res 2011; 39:5025-35. [PMID: 21385826 PMCID: PMC3130277 DOI: 10.1093/nar/gkr107] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The relevance of serine 5 phosphorylation of RNA polymerase II carboxy-terminal domain during initiation has been difficult to determine in mammalian cells as no general in vivo Ser5 kinase has been identified. Here, we demonstrate that deletion of the TFIIH kinase subunit Mat1 in mouse fibroblasts leads to dramatically reduced Pol II Ser5 phosphorylation. This is associated with defective capping and reduced Ser2 phosphorylation, decreased Pol II progression into elongation and severely attenuated transcription detected through analysis of nascent mRNAs, establishing a general requirement for mammalian Mat1 in transcription. Surprisingly, the general defect in Pol II transcription in Mat1−/− fibroblasts is not reflected in the majority of steady-state mRNAs. This indicates widespread stabilization of mRNAs and points to the existence of a regulatory mechanism to stabilize mRNAs following transcriptional attenuation, thus revealing a potential caveat in similar studies limited to analysis of steady-state mRNAs.
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Affiliation(s)
- Katja Helenius
- Institute of Biotechnology, University of Helsinki, PO Box 56 Viikinkaari 9, 00014 University of Helsinki, Helsinki, Finland
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131
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Werner M, Purta E, Kaminska KH, Cymerman IA, Campbell DA, Mittra B, Zamudio JR, Sturm NR, Jaworski J, Bujnicki JM. 2'-O-ribose methylation of cap2 in human: function and evolution in a horizontally mobile family. Nucleic Acids Res 2011; 39:4756-68. [PMID: 21310715 PMCID: PMC3113572 DOI: 10.1093/nar/gkr038] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The 5′ cap of human messenger RNA consists of an inverted 7-methylguanosine linked to the first transcribed nucleotide by a unique 5′–5′ triphosphate bond followed by 2′-O-ribose methylation of the first and often the second transcribed nucleotides, likely serving to modify efficiency of transcript processing, translation and stability. We report the validation of a human enzyme that methylates the ribose of the second transcribed nucleotide encoded by FTSJD1, henceforth renamed HMTR2 to reflect function. Purified recombinant hMTr2 protein transfers a methyl group from S-adenosylmethionine to the 2′-O-ribose of the second nucleotide of messenger RNA and small nuclear RNA. Neither N7 methylation of the guanosine cap nor 2′-O-ribose methylation of the first transcribed nucleotide are required for hMTr2, but the presence of cap1 methylation increases hMTr2 activity. The hMTr2 protein is distributed throughout the nucleus and cytosol, in contrast to the nuclear hMTr1. The details of how and why specific transcripts undergo modification with these ribose methylations remains to be elucidated. The 2′-O-ribose RNA cap methyltransferases are present in varying combinations in most eukaryotic and many viral genomes. With the capping enzymes in hand their biological purpose can be ascertained.
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Affiliation(s)
- Maria Werner
- International Institute of Molecular and Cell Biology in Warsaw, ul. Ks. Trojdena 4, 02-109 Warsaw, Poland
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132
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Luco RF, Allo M, Schor IE, Kornblihtt AR, Misteli T. Epigenetics in alternative pre-mRNA splicing. Cell 2011; 144:16-26. [PMID: 21215366 DOI: 10.1016/j.cell.2010.11.056] [Citation(s) in RCA: 582] [Impact Index Per Article: 44.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Revised: 09/07/2010] [Accepted: 11/13/2010] [Indexed: 12/11/2022]
Abstract
Alternative splicing plays critical roles in differentiation, development, and disease and is a major source for protein diversity in higher eukaryotes. Analysis of alternative splicing regulation has traditionally focused on RNA sequence elements and their associated splicing factors, but recent provocative studies point to a key function of chromatin structure and histone modifications in alternative splicing regulation. These insights suggest that epigenetic regulation determines not only what parts of the genome are expressed but also how they are spliced.
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Affiliation(s)
- Reini F Luco
- National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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133
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Abstract
The main type of RNA editing in mammals is the conversion of adenosine to inosine which is translated as if it were guanosine. The enzymes that catalyze this reaction are ADARs (adenosine deaminases that act on RNA), of which there are four in mammals, two of which are catalytically inactive. ADARs edit transcripts that encode proteins expressed mainly in the CNS and editing is crucial to maintain a correctly functioning nervous system. However, the majority of editing has been found in transcripts encoding Alu repeat elements and the biological role of this editing remains a mystery. This chapter describes in detail the different ADAR enzymes and the phenotype of animals that are deficient in their activity. Besides being enzymes, ADARs are also double-stranded RNA-binding proteins, so by binding alone they can interfere with other processes such as RNA interference. Lack of editing by ADARs has been implicated in disorders such as forebrain ischemia and Amyotrophic Lateral Sclerosis (ALS) and this will also be discussed.
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Affiliation(s)
- Marion Hogg
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, Western General Hospital, Edinburgh, UK
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134
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Topisirovic I, Svitkin YV, Sonenberg N, Shatkin AJ. Cap and cap-binding proteins in the control of gene expression. WILEY INTERDISCIPLINARY REVIEWS-RNA 2010; 2:277-98. [PMID: 21957010 DOI: 10.1002/wrna.52] [Citation(s) in RCA: 276] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The 5' mRNA cap structure is essential for efficient gene expression from yeast to human. It plays a critical role in all aspects of the life cycle of an mRNA molecule. Capping occurs co-transcriptionally on the nascent pre-mRNA as it emerges from the RNA exit channel of RNA polymerase II. The cap structure protects mRNAs from degradation by exonucleases and promotes transcription, polyadenylation, splicing, and nuclear export of mRNA and U-rich, capped snRNAs. In addition, the cap structure is required for the optimal translation of the vast majority of cellular mRNAs, and it also plays a prominent role in the expression of eukaryotic, viral, and parasite mRNAs. Cap-binding proteins specifically bind to the cap structure and mediate its functions in the cell. Two major cellular cap-binding proteins have been described to date: eukaryotic translation initiation factor 4E (eIF4E) in the cytoplasm and nuclear cap binding complex (nCBC), a nuclear complex consisting of a cap-binding subunit cap-binding protein 20 (CBP 20) and an auxiliary protein cap-binding protein 80 (CBP 80). nCBC plays an important role in various aspects of nuclear mRNA metabolism such as pre-mRNA splicing and nuclear export, whereas eIF4E acts primarily as a facilitator of mRNA translation. In this review, we highlight recent findings on the role of the cap structure and cap-binding proteins in the regulation of gene expression. We also describe emerging regulatory pathways that control mRNA capping and cap-binding proteins in the cell.
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Affiliation(s)
- Ivan Topisirovic
- Department of Biochemistry and Goodman Cancer Centre, McGill University, Montréal, QC, Canada
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135
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Cooperative interaction of transcription termination factors with the RNA polymerase II C-terminal domain. Nat Struct Mol Biol 2010; 17:1195-201. [PMID: 20818393 PMCID: PMC2950884 DOI: 10.1038/nsmb.1893] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2010] [Accepted: 07/19/2010] [Indexed: 01/18/2023]
Abstract
Phosphorylation of the C-terminal domain of RNA polymerase II controls the co-transcriptional assembly of RNA processing and transcription factors. Recruitment relies on conserved CTD-interacting domains that recognize different CTD phosphoisoforms during the transcription cycle, but the molecular basis for their specificity remains unclear. We show that the CTD-interacting domains of two transcription termination factors, Rtt103 and Pcf11, achieve high affinity and specificity both by specifically recognizing the phosphorylated CTD and by cooperatively binding to neighboring CTD repeats. Single amino acid mutations at the protein-protein interface abolish cooperativity and affect recruitment at the 3′-end processing site in vivo. We suggest that this cooperativity provides a signal-response mechanism to ensure that its action is confined only to proper polyadenylation sites where Serine 2 phosphorylation density is highest.
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136
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Suh MH, Meyer PA, Gu M, Ye P, Zhang M, Kaplan CD, Lima CD, Fu J. A dual interface determines the recognition of RNA polymerase II by RNA capping enzyme. J Biol Chem 2010; 285:34027-38. [PMID: 20720002 DOI: 10.1074/jbc.m110.145110] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
RNA capping enzyme (CE) is recruited specifically to RNA polymerase II (Pol II) transcription sites to facilitate cotranscriptional 5'-capping of pre-mRNA and other Pol II transcripts. The current model to explain this specific recruitment of CE to Pol II as opposed to Pol I and Pol III rests on the interaction between CE and the phosphorylated C-terminal domain (CTD) of Pol II largest subunit Rpb1 and more specifically between the CE nucleotidyltransferase domain and the phosphorylated CTD. Through biochemical and diffraction analyses, we demonstrate the existence of a distinctive stoichiometric complex between CE and the phosphorylated Pol II (Pol IIO). Analysis of the complex revealed an additional and unexpected polymerase-CE interface (PCI) located on the multihelical Foot domain of Rpb1. We name this interface PCI1 and the previously known nucleotidyltransferase/phosphorylated CTD interface PCI2. Although PCI1 and PCI2 individually contribute to only weak interactions with CE, a dramatically stabilized and stoichiometric complex is formed when PCI1 and PCI2 are combined in cis as they occur in an intact phosphorylated Pol II molecule. Disrupting either PCI1 or PCI2 by alanine substitution or deletion diminishes CE association with Pol II and causes severe growth defects in vivo. Evidence from manipulating PCI1 indicates that the Foot domain contributes to the specificity in CE interaction with Pol II as opposed to Pol I and Pol III. Our results indicate that the dual interface based on combining PCI1 and PCI2 is required for directing CE to Pol II elongation complexes.
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Affiliation(s)
- Man-Hee Suh
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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137
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Yoshida T, Kobayashi T, Itoda M, Muto T, Miyaguchi K, Mogushi K, Shoji S, Shimokawa K, Iida S, Uetake H, Ishikawa T, Sugihara K, Mizushima H, Tanaka H. Clinical omics analysis of colorectal cancer incorporating copy number aberrations and gene expression data. Cancer Inform 2010; 9:147-61. [PMID: 20706620 PMCID: PMC2918356 DOI: 10.4137/cin.s3851] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Background: Colorectal cancer (CRC) is one of the most frequently occurring cancers in Japan, and thus a wide range of methods have been deployed to study the molecular mechanisms of CRC. In this study, we performed a comprehensive analysis of CRC, incorporating copy number aberration (CRC) and gene expression data. For the last four years, we have been collecting data from CRC cases and organizing the information as an “omics” study by integrating many kinds of analysis into a single comprehensive investigation. In our previous studies, we had experienced difficulty in finding genes related to CRC, as we observed higher noise levels in the expression data than in the data for other cancers. Because chromosomal aberrations are often observed in CRC, here, we have performed a combination of CNA analysis and expression analysis in order to identify some new genes responsible for CRC. This study was performed as part of the Clinical Omics Database Project at Tokyo Medical and Dental University. The purpose of this study was to investigate the mechanism of genetic instability in CRC by this combination of expression analysis and CNA, and to establish a new method for the diagnosis and treatment of CRC. Materials and methods: Comprehensive gene expression analysis was performed on 79 CRC cases using an Affymetrix Gene Chip, and comprehensive CNA analysis was performed using an Affymetrix DNA Sty array. To avoid the contamination of cancer tissue with normal cells, laser micro-dissection was performed before DNA/RNA extraction. Data analysis was performed using original software written in the R language. Result: We observed a high percentage of CNA in colorectal cancer, including copy number gains at 7, 8q, 13 and 20q, and copy number losses at 8p, 17p and 18. Gene expression analysis provided many candidates for CRC-related genes, but their association with CRC did not reach the level of statistical significance. The combination of CNA and gene expression analysis, together with the clinical information, suggested UGT2B28, LOC440995, CXCL6, SULT1B1, RALBP1, TYMS, RAB12, RNMT, ARHGDIB, S1000A2, ABHD2, OIT3 and ABHD12 as genes that are possibly associated with CRC. Some of these genes have already been reported as being related to CRC. TYMS has been reported as being associated with resistance to the anti-cancer drug 5-fluorouracil, and we observed a copy number increase for this gene. RALBP1, ARHGDIB and S100A2 have been reported as oncogenes, and we observed copy number increases in each. ARHGDIB has been reported as a metastasis-related gene, and our data also showed copy number increases of this gene in cases with metastasis. Conclusion: The combination of CNA analysis and gene expression analysis was a more effective method for finding genes associated with the clinicopathological classification of CRC than either analysis alone. Using this combination of methods, we were able to detect genes that have already been associated with CRC. We also identified additional candidate genes that may be new markers or targets for this form of cancer.
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Affiliation(s)
- Tsuyoshi Yoshida
- Information Center for Medical Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
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138
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Liu P, Kenney JM, Stiller JW, Greenleaf AL. Genetic organization, length conservation, and evolution of RNA polymerase II carboxyl-terminal domain. Mol Biol Evol 2010; 27:2628-41. [PMID: 20558594 DOI: 10.1093/molbev/msq151] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
With a simple tandem iterated sequence, the carboxyl terminal domain (CTD) of eukaryotic RNA polymerase II (RNAP II) serves as the central coordinator of mRNA synthesis by harmonizing a diversity of sequential interactions with transcription and processing factors. Despite intense research interest, many key questions regarding functional and evolutionary constraints on the CTD remain unanswered; for example, what selects for the canonical heptad sequence, its tandem array across organismal diversity, and constant CTD length within given species and finally and how a sequence-identical, repetitive structure can orchestrate a diversity of simultaneous and sequential, stage-dependent interactions with both modifying enzymes and binding partners? Here we examine comparative sequence evolution of 58 RNAP II CTDs from diverse taxa representing all six major eukaryotic supergroups and employ integrated evolutionary genetic, biochemical, and biophysical analyses of the yeast CTD to further clarify how this repetitive sequence must be organized for optimal RNAP II function. We find that the CTD is composed of indivisible and independent functional units that span diheptapeptides and not only a flexible conformation around each unit but also an elastic overall structure is required. More remarkably, optimal CTD function always is achieved at approximately wild-type CTD length rather than number of functional units, regardless of the characteristics of the sequence present. Our combined observations lead us to advance an updated CTD working model, in which functional, and therefore, evolutionary constraints require a flexible CTD conformation determined by the CTD sequence and tandem register to accommodate the diversity of CTD-protein interactions and a specific CTD length rather than number of functional units to correctly order and organize global CTD-protein interactions. Patterns of conservation of these features across evolutionary diversity have important implications for comparative RNAP II function in eukaryotes and can more clearly direct specific research on CTD function in currently understudied organisms.
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Affiliation(s)
- Pengda Liu
- Department of Biology, East Carolina University, USA
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139
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Ghosh A, Lima CD. Enzymology of RNA cap synthesis. WILEY INTERDISCIPLINARY REVIEWS-RNA 2010; 1:152-72. [PMID: 21956912 DOI: 10.1002/wrna.19] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The 5' guanine-N7 methyl cap is unique to cellular and viral messenger RNA (mRNA) and is the first co-transcriptional modification of mRNA. The mRNA cap plays a pivotal role in mRNA biogenesis and stability, and is essential for efficient splicing, mRNA export, and translation. Capping occurs by a series of three enzymatic reactions that results in formation of N7-methyl guanosine linked through a 5'-5' inverted triphosphate bridge to the first nucleotide of a nascent transcript. Capping of cellular mRNA occurs co-transcriptionally and in vivo requires that the capping apparatus be physically associated with the RNA polymerase II elongation complex. Certain capped mRNAs undergo further methylation to generate distinct cap structures. Although mRNA capping is conserved among viruses and eukaryotes, some viruses have adopted strategies for capping mRNA that are distinct from the cellular mRNA capping pathway.
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Affiliation(s)
- Agnidipta Ghosh
- Structural Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
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140
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RNA polymerase II C-terminal domain phosphorylation patterns in Caenorhabditis elegans operons, polycistronic gene clusters with only one promoter. Mol Cell Biol 2010; 30:3887-93. [PMID: 20498277 DOI: 10.1128/mcb.00325-10] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The heptad repeat of the RNA polymerase II (RNAPII) C-terminal domain is phosphorylated at serine 5 near gene 5' ends and serine 2 near 3' ends in order to recruit pre-mRNA processing factors. Ser-5(P) is associated with gene 5' ends to recruit capping enzymes, whereas Ser-2(P) is associated with gene 3' ends to recruit cleavage and polyadenylation factors. In the gene clusters called operons in Caenorhabditis elegans, there is generally only a single promoter, but each gene in the operon forms a 3' end by the usual mechanism. Although downstream operon genes have 5' ends, they receive their caps by trans splicing rather than by capping enzymes. Thus, they are predicted to not need Ser-5 phosphorylation. Here we show by RNAPII chromatin immunoprecipitation (ChIP) that internal operon gene 5' ends do indeed lack Ser-5(P) peaks. In contrast, Ser-2(P) peaks occur at each mRNA 3' end, where the 3'-end formation machinery binds. These results provide additional support for the idea that the serine phosphorylation of the C-terminal domain (CTD) serves to bring RNA-processing enzymes to the transcription complex. Furthermore, these results provide a novel demonstration that genes in operons are cotranscribed from a single upstream promoter.
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141
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Gu M, Rajashankar KR, Lima CD. Structure of the Saccharomyces cerevisiae Cet1-Ceg1 mRNA capping apparatus. Structure 2010; 18:216-27. [PMID: 20159466 DOI: 10.1016/j.str.2009.12.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2009] [Revised: 12/06/2009] [Accepted: 12/15/2009] [Indexed: 11/16/2022]
Abstract
The 5' guanine-N7 cap is the first cotranscriptional modification of messenger RNA. In Saccharomyces cerevisiae, the first two steps in capping are catalyzed by the RNA triphosphatase Cet1 and RNA guanylyltransferase Ceg1, which form a complex that is directly recruited to phosphorylated RNA polymerase II (RNAP IIo), primarily via contacts between RNAP IIo and Ceg1. A 3.0 A crystal structure of Cet1-Ceg1 revealed a 176 kDa heterotetrameric complex composed of one Cet1 homodimer that associates with two Ceg1 molecules via interactions between the Ceg1 oligonucleotide binding domain and an extended Cet1 WAQKW amino acid motif. The WAQKW motif is followed by a flexible linker that would allow Ceg1 to achieve conformational changes required for capping while maintaining interactions with both Cet1 and RNAP IIo. The impact of mutations as assessed through genetic analysis in S. cerevisiae is consonant with contacts observed in the Cet1-Ceg1 structure.
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Affiliation(s)
- Meigang Gu
- Structural Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
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142
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Rahl PB, Lin CY, Seila AC, Flynn RA, McCuine S, Burge CB, Sharp PA, Young RA. c-Myc regulates transcriptional pause release. Cell 2010; 141:432-45. [PMID: 20434984 DOI: 10.1016/j.cell.2010.03.030] [Citation(s) in RCA: 989] [Impact Index Per Article: 70.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2009] [Revised: 01/14/2010] [Accepted: 02/21/2010] [Indexed: 12/30/2022]
Abstract
Recruitment of the RNA polymerase II (Pol II) transcription initiation apparatus to promoters by specific DNA-binding transcription factors is well recognized as a key regulatory step in gene expression. We report here that promoter-proximal pausing is a general feature of transcription by Pol II in mammalian cells and thus an additional step where regulation of gene expression occurs. This suggests that some transcription factors recruit the transcription apparatus to promoters, whereas others effect promoter-proximal pause release. Indeed, we find that the transcription factor c-Myc, a key regulator of cellular proliferation, plays a major role in Pol II pause release rather than Pol II recruitment at its target genes. We discuss the implications of these results for the role of c-Myc amplification in human cancer.
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Affiliation(s)
- Peter B Rahl
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
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143
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The carboxy terminal domain of RNA polymerase II and alternative splicing. Trends Biochem Sci 2010; 35:497-504. [PMID: 20418102 DOI: 10.1016/j.tibs.2010.03.010] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2010] [Revised: 03/28/2010] [Accepted: 03/30/2010] [Indexed: 01/27/2023]
Abstract
Alternative splicing is controlled by cis-regulatory sequences present in the pre-mRNA and their cognate trans-acting factors, as well as by its coupling to RNA polymerase II (pol II) transcription. A unique feature of this polymerase is the presence of a highly repetitive carboxy terminal domain (CTD), which is subject to multiple regulatory post-translational modifications. CTD phosphorylation events affect the transcriptional properties of pol II and the outcome of co-transcriptional alternative splicing by mediating the effects of splicing factors and by modulating transcription elongation rates. Here, we discuss various examples of involvement of the CTD in alternative splicing regulation as well as the current methodological limitations in deciphering the detailed mechanisms of this process.
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144
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Separable functions of the fission yeast Spt5 carboxyl-terminal domain (CTD) in capping enzyme binding and transcription elongation overlap with those of the RNA polymerase II CTD. Mol Cell Biol 2010; 30:2353-64. [PMID: 20231361 DOI: 10.1128/mcb.00116-10] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
An interaction network connecting mRNA capping enzymes, the RNA polymerase II (Pol II) carboxyl-terminal domain (CTD), elongation factor Spt5, and the Cdk7 and Cdk9 protein kinases is thought to comprise a transcription elongation checkpoint. A crux of this network is Spt5, which regulates early transcription elongation and has an imputed role in pre-mRNA processing via its physical association with capping enzymes. Schizosaccharomyces pombe Spt5 has a distinctive CTD composed of tandem nonapeptide repeats of the consensus sequence (1)TPAWNSGSK(9). The Spt5 CTD binds the capping enzymes and is a substrate for threonine phosphorylation by the Cdk9 kinase. Here we report that deletion of the S. pombe Spt5 CTD results in slow growth and aberrant cell morphology. The severity of the spt5-DeltaCTD phenotype is exacerbated by truncation of the Pol II CTD and ameliorated by overexpression of the capping enzymes RNA triphosphatase and RNA guanylyltransferase. These results suggest that the Spt5 and Pol II CTDs play functionally overlapping roles in capping enzyme recruitment. We probed structure-activity relations of the Spt5 CTD by alanine scanning of the consensus nonapeptide. The T1A change abolished CTD phosphorylation by Cdk9 but did not affect CTD binding to the capping enzymes. The T1A and P2A mutations elicited cold-sensitive (cs) and temperature-sensitive (ts) growth defects and conferred sensitivity to growth inhibition by 6-azauracil that was exacerbated by partial truncations of the Pol II CTD. The T1A phenotypes were rescued by a phosphomimetic T1E change but not by capping enzyme overexpression. These results imply a positive role for Spt5 CTD phosphorylation in Pol Il transcription elongation in fission yeast, distinct from its capping enzyme interactions. Viability of yeast cells bearing both Spt5 CTD T1A and Pol II CTD S2A mutations heralds that the Cdk9 kinase has an essential target other than Spt5 and Pol II CTD-Ser2.
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145
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Donner AJ, Ebmeier CC, Taatjes DJ, Espinosa JM. CDK8 is a positive regulator of transcriptional elongation within the serum response network. Nat Struct Mol Biol 2010; 17:194-201. [PMID: 20098423 PMCID: PMC2920286 DOI: 10.1038/nsmb.1752] [Citation(s) in RCA: 272] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2009] [Accepted: 11/25/2009] [Indexed: 01/13/2023]
Abstract
The Mediator complex allows communication between transcription factors and RNA polymerase II (RNAPII). CDK8, the kinase found in some variants of Mediator, has been characterized mostly as a transcriptional repressor. Recently, CDK8 was demonstrated to be a potent oncoprotein. Here we show that CDK8 is a positive regulator of genes within the serum response network, including several members of the AP-1 and EGR family of oncogenic transcription factors. Mechanistic studies demonstrate that CDK8 is not required for RNAPII recruitment or promoter escape. Instead, CDK8 depletion leads to the appearance of slower elongation complexes carrying hypophosphorylated RNAPII. CDK8-Mediator regulates precise steps in the assembly of the RNAPII elongation complex, including the recruitment of P-TEFb and BRD4. Furthermore, CDK8-Mediator specifically interacts with P-TEFb. Thus, we uncovered a novel role for CDK8 in transcriptional regulation that may contribute to its oncogenic effects.
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Affiliation(s)
- Aaron J Donner
- Howard Hughes Medical Institute, The University of Colorado at Boulder, Boulder, Colorado, USA
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146
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Seim I, Amorim L, Walpole C, Carter S, Chopin LK, Herington AC. Ghrelin gene-related peptides: Multifunctional endocrine / autocrine modulators in health and disease. Clin Exp Pharmacol Physiol 2010; 37:125-31. [DOI: 10.1111/j.1440-1681.2009.05241.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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147
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Abstract
The 7-methylguanosine cap added to the 5′ end of mRNA is essential for efficient gene expression and cell viability. Methylation of the guanosine cap is necessary for the translation of most cellular mRNAs in all eukaryotic organisms in which it has been investigated. In some experimental systems, cap methylation has also been demonstrated to promote transcription, splicing, polyadenylation and nuclear export of mRNA. The present review discusses how the 7-methylguanosine cap is synthesized by cellular enzymes, the impact that the 7-methylguanosine cap has on biological processes, and how the mRNA cap methylation reaction is regulated.
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148
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Singh N, Ma Z, Gemmill T, Wu X, Defiglio H, Rossettini A, Rabeler C, Beane O, Morse RH, Palumbo MJ, Hanes SD. The Ess1 prolyl isomerase is required for transcription termination of small noncoding RNAs via the Nrd1 pathway. Mol Cell 2009; 36:255-66. [PMID: 19854134 DOI: 10.1016/j.molcel.2009.08.018] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Revised: 07/03/2009] [Accepted: 08/13/2009] [Indexed: 12/17/2022]
Abstract
Genome-wide studies have identified abundant small, noncoding RNAs, including small nuclear RNAs, small nucleolar RNAs (snoRNAs), cryptic unstable transcripts (CUTs), and upstream regulatory RNAs (uRNAs), that are transcribed by RNA polymerase II (pol II) and terminated by an Nrd1-dependent pathway. Here, we show that the prolyl isomerase Ess1 is required for Nrd1-dependent termination of noncoding RNAs. Ess1 binds the carboxy-terminal domain (CTD) of pol II and is thought to regulate transcription by conformational isomerization of Ser-Pro bonds within the CTD. In ess1 mutants, expression of approximately 10% of the genome was altered, due primarily to defects in termination of snoRNAs, CUTs, stable unannotated transcripts, and uRNAs. Ess1 promoted dephosphorylation of Ser5 (but not Ser2) within the CTD, most likely by the Ssu72 phosphatase. We also provide evidence for a competition between Nrd1 and Pcf11 for CTD binding that is regulated by Ess1. These data indicate that a prolyl isomerase is required for specifying the "CTD code."
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Affiliation(s)
- Navjot Singh
- Wadsworth Center, New York State Department of Health, 120 New Scotland Avenue, Albany, NY 12208, USA
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149
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Boeing S, Rigault C, Heidemann M, Eick D, Meisterernst M. RNA polymerase II C-terminal heptarepeat domain Ser-7 phosphorylation is established in a mediator-dependent fashion. J Biol Chem 2009; 285:188-96. [PMID: 19901026 DOI: 10.1074/jbc.m109.046565] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The largest subunit of RNA polymerase II (RNAPII) C-terminal heptarepeat domain (CTD) is subject to phosphorylation during initiation and elongation of transcription by RNA polymerase II. Here we study the molecular mechanisms leading to phosphorylation of Ser-7 in the human enzyme. Ser-7 becomes phosphorylated before initiation of transcription at promoter regions. We identify cyclin-dependent kinase 7 (CDK7) as one responsible kinase. Phosphorylation of both Ser-5 and Ser-7 is fully dependent on the cofactor complex Mediator. A subform of Mediator associated with an active RNAPII is critical for preinitiation complex formation and CTD phosphorylation. The Mediator-RNAPII complex independently recruits TFIIB and CDK7 to core promoter regions. CDK7 phosphorylates Ser-7 selectively in the context of an intact preinitiation complex. CDK7 is not the only kinase that can modify Ser-7 of the CTD. ChIP experiments with chemical inhibitors provide evidence that other yet to be identified kinases further phosphorylate Ser-7 in coding regions.
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Affiliation(s)
- Stefan Boeing
- Institute of Molecular Tumor Biology, University of Muenster, Robert-Koch-Strasse 43, 48149 Muenster, Germany
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150
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S-adenosyl homocysteine hydrolase is required for Myc-induced mRNA cap methylation, protein synthesis, and cell proliferation. Mol Cell Biol 2009; 29:6182-91. [PMID: 19805518 DOI: 10.1128/mcb.00973-09] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The c-Myc proto-oncogene promotes mRNA cap methylation, which is essential for almost all mRNA translation. The mRNA cap methylation reaction produces an inhibitory byproduct, S-adenosyl homocysteine. Here we report that Myc promotes upregulation of S-adenosyl homocysteine hydrolase (SAHH), an enzyme which hydrolyzes S-adenosyl homocysteine, thus neutralizing its inhibitory effects, and this is required for c-Myc-induced mRNA cap methylation. c-Myc-induced mRNA cap methylation was repressed by inhibiting the expression or activity of SAHH, whereas the same treatments did not have a significant effect on c-Myc-induced transcription or other c-Myc-dependent methylation events. The selective inhibition of mRNA cap methylation afforded by SAHH repression revealed that c-Myc-induced cap methylation could be correlated with the core c-Myc functions of protein synthesis, cell proliferation, and cell transformation.
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