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Aydin E, Schreiner S, Böhme J, Keil B, Weber J, Žunar B, Glatter T, Kilchert C. DEAD-box ATPase Dbp2 is the key enzyme in an mRNP assembly checkpoint at the 3'-end of genes and involved in the recycling of cleavage factors. Nat Commun 2024; 15:6829. [PMID: 39122693 PMCID: PMC11315920 DOI: 10.1038/s41467-024-51035-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Accepted: 07/24/2024] [Indexed: 08/12/2024] Open
Abstract
mRNA biogenesis in the eukaryotic nucleus is a highly complex process. The numerous RNA processing steps are tightly coordinated to ensure that only fully processed transcripts are released from chromatin for export from the nucleus. Here, we present the hypothesis that fission yeast Dbp2, a ribonucleoprotein complex (RNP) remodelling ATPase of the DEAD-box family, is the key enzyme in an RNP assembly checkpoint at the 3'-end of genes. We show that Dbp2 interacts with the cleavage and polyadenylation complex (CPAC) and localises to cleavage bodies, which are enriched for 3'-end processing factors and proteins involved in nuclear RNA surveillance. Upon loss of Dbp2, 3'-processed, polyadenylated RNAs accumulate on chromatin and in cleavage bodies, and CPAC components are depleted from the soluble pool. Under these conditions, cells display an increased likelihood to skip polyadenylation sites and a delayed transcription termination, suggesting that levels of free CPAC components are insufficient to maintain normal levels of 3'-end processing. Our data support a model in which Dbp2 is the active component of an mRNP remodelling checkpoint that licenses RNA export and is coupled to CPAC release.
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Affiliation(s)
- Ebru Aydin
- Institute of Biochemistry, Justus-Liebig University Giessen, Giessen, Germany
| | - Silke Schreiner
- Institute of Biochemistry, Justus-Liebig University Giessen, Giessen, Germany
| | - Jacqueline Böhme
- Institute of Biochemistry, Justus-Liebig University Giessen, Giessen, Germany
| | - Birte Keil
- Institute of Biochemistry, Justus-Liebig University Giessen, Giessen, Germany
| | - Jan Weber
- Institute of Biochemistry, Justus-Liebig University Giessen, Giessen, Germany
| | - Bojan Žunar
- Department of Chemistry and Biochemistry, University of Zagreb Faculty of Food Technology and Biotechnology, Zagreb, Croatia
| | - Timo Glatter
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Cornelia Kilchert
- Institute of Biochemistry, Justus-Liebig University Giessen, Giessen, Germany.
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2
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Herzel L, Ottoz DSM, Alpert T, Neugebauer KM. Splicing and transcription touch base: co-transcriptional spliceosome assembly and function. Nat Rev Mol Cell Biol 2017; 18:637-650. [PMID: 28792005 DOI: 10.1038/nrm.2017.63] [Citation(s) in RCA: 239] [Impact Index Per Article: 29.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Several macromolecular machines collaborate to produce eukaryotic messenger RNA. RNA polymerase II (Pol II) translocates along genes that are up to millions of base pairs in length and generates a flexible RNA copy of the DNA template. This nascent RNA harbours introns that are removed by the spliceosome, which is a megadalton ribonucleoprotein complex that positions the distant ends of the intron into its catalytic centre. Emerging evidence that the catalytic spliceosome is physically close to Pol II in vivo implies that transcription and splicing occur on similar timescales and that the transcription and splicing machineries may be spatially constrained. In this Review, we discuss aspects of spliceosome assembly, transcription elongation and other co-transcriptional events that allow the temporal coordination of co-transcriptional splicing.
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Affiliation(s)
- Lydia Herzel
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA.,Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Diana S M Ottoz
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA
| | - Tara Alpert
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA
| | - Karla M Neugebauer
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA
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3
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A saga of cancer epigenetics: linking epigenetics to alternative splicing. Biochem J 2017; 474:885-896. [PMID: 28270561 DOI: 10.1042/bcj20161047] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 12/29/2016] [Accepted: 01/05/2017] [Indexed: 12/14/2022]
Abstract
The discovery of an increasing number of alternative splicing events in the human genome highlighted that ∼94% of genes generate alternatively spliced transcripts that may produce different protein isoforms with diverse functions. It is now well known that several diseases are a direct and indirect consequence of aberrant splicing events in humans. In addition to the conventional mode of alternative splicing regulation by 'cis' RNA-binding sites and 'trans' RNA-binding proteins, recent literature provides enormous evidence for epigenetic regulation of alternative splicing. The epigenetic modifications may regulate alternative splicing by either influencing the transcription elongation rate of RNA polymerase II or by recruiting a specific splicing regulator via different chromatin adaptors. The epigenetic alterations and aberrant alternative splicing are known to be associated with various diseases individually, but this review discusses/highlights the latest literature on the role of epigenetic alterations in the regulation of alternative splicing and thereby cancer progression. This review also points out the need for further studies to understand the interplay between epigenetic modifications and aberrant alternative splicing in cancer progression.
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4
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Heyn P, Kalinka AT, Tomancak P, Neugebauer KM. Introns and gene expression: cellular constraints, transcriptional regulation, and evolutionary consequences. Bioessays 2014; 37:148-54. [PMID: 25400101 PMCID: PMC4654234 DOI: 10.1002/bies.201400138] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A gene's “expression profile” denotes the number of transcripts present relative to all other transcripts. The overall rate of transcript production is determined by transcription and RNA processing rates. While the speed of elongating RNA polymerase II has been characterized for many different genes and organisms, gene-architectural features – primarily the number and length of exons and introns – have recently emerged as important regulatory players. Several new studies indicate that rapidly cycling cells constrain gene-architecture toward short genes with a few introns, allowing efficient expression during short cell cycles. In contrast, longer genes with long introns exhibit delayed expression, which can serve as timing mechanisms for patterning processes. These findings indicate that cell cycle constraints drive the evolution of gene-architecture and shape the transcriptome of a given cell type. Furthermore, a tendency for short genes to be evolutionarily young hints at links between cellular constraints and the evolution of animal ontogeny.
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Affiliation(s)
- Patricia Heyn
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Edinburgh, UK
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5
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Rogulja-Ortmann A, Picao-Osorio J, Villava C, Patraquim P, Lafuente E, Aspden J, Thomsen S, Technau GM, Alonso CR. The RNA-binding protein ELAV regulates Hox RNA processing, expression and function within the Drosophila nervous system. Development 2014; 141:2046-56. [PMID: 24803653 PMCID: PMC4132933 DOI: 10.1242/dev.101519] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The regulated head-to-tail expression of Hox genes provides a coordinate system for the activation of specific programmes of cell differentiation according to axial level. Recent work indicates that Hox expression can be regulated via RNA processing but the underlying mechanisms and biological significance of this form of regulation remain poorly understood. Here we explore these issues within the developing Drosophila central nervous system (CNS). We show that the pan-neural RNA-binding protein (RBP) ELAV (Hu antigen) regulates the RNA processing patterns of the Hox gene Ultrabithorax (Ubx) within the embryonic CNS. Using a combination of biochemical, genetic and imaging approaches we demonstrate that ELAV binds to discrete elements within Ubx RNAs and that its genetic removal reduces Ubx protein expression in the CNS leading to the respecification of cellular subroutines under Ubx control, thus defining for the first time a specific cellular role of ELAV within the developing CNS. Artificial provision of ELAV in glial cells (a cell type that lacks ELAV) promotes Ubx expression, suggesting that ELAV-dependent regulation might contribute to cell type-specific Hox expression patterns within the CNS. Finally, we note that expression of abdominal A and Abdominal B is reduced in elav mutant embryos, whereas other Hox genes (Antennapedia) are not affected. Based on these results and the evolutionary conservation of ELAV and Hox genes we propose that the modulation of Hox RNA processing by ELAV serves to adapt the morphogenesis of the CNS to axial level by regulating Hox expression and consequently activating local programmes of neural differentiation.
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6
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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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7
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Threonine-4 of mammalian RNA polymerase II CTD is targeted by Polo-like kinase 3 and required for transcriptional elongation. EMBO J 2012; 31:2784-97. [PMID: 22549466 DOI: 10.1038/emboj.2012.123] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Accepted: 04/12/2012] [Indexed: 12/31/2022] Open
Abstract
Eukaryotic RNA polymerase II (Pol II) has evolved an array of heptad repeats with the consensus sequence Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7 at the carboxy-terminal domain (CTD) of the large subunit (Rpb1). Differential phosphorylation of Ser2, Ser5, and Ser7 in the 5' and 3' regions of genes coordinates the binding of transcription and RNA processing factors to the initiating and elongating polymerase complexes. Here, we report phosphorylation of Thr4 by Polo-like kinase 3 in mammalian cells. ChIPseq analyses indicate an increase of Thr4-P levels in the 3' region of genes occurring subsequently to an increase of Ser2-P levels. A Thr4/Ala mutant of Pol II displays a lethal phenotype. This mutant reveals a global defect in RNA elongation, while initiation is largely unaffected. Since Thr4 replacement mutants are viable in yeast we conclude that this amino acid has evolved an essential function(s) in the CTD of Pol II for gene transcription in mammalian cells.
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Schmid M, Jensen TH. Nuclear quality control of RNA polymerase II transcripts. WILEY INTERDISCIPLINARY REVIEWS-RNA 2012; 1:474-85. [PMID: 21956943 DOI: 10.1002/wrna.24] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Eukaryotic RNA polymerase II produces an astounding diversity of transcripts. These may need to be 5(') capped, spliced, polyadenylated, and packaged with proteins before their export to the cytoplasm. Unscheduled accumulation of any RNA species can interfere with normal RNA metabolism and poses a serious hazard to cells. Yet, given the amount of primary transcripts and the complexity of the RNA maturation process, production of aberrant RNA species is unavoidable. Cells, therefore, employ nuclear RNA quality control mechanisms to rapidly degrade, actively retain, or transcriptionally silence unwanted RNAs. Pathways that monitor mRNA production are best understood and similar pathways are employed to destroy transcriptional noise. Finally, related mechanisms also contribute to gene regulation during normal growth.
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Affiliation(s)
- Manfred Schmid
- Centre for mRNP Biogenesis and Metabolism, Department of Molecular Biology, Aarhus University, C.F. Møllers Alle, Bldg. 130, 8000 Aarhus C., Denmark
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9
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Functional cooperation between the proteins Nck and ADAP is fundamental for actin reorganization. Mol Cell Biol 2011; 31:2653-66. [PMID: 21536650 DOI: 10.1128/mcb.01358-10] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
T cell antigen receptor (TCR) activation triggers profound changes in the actin cytoskeleton. In addition to controlling cellular shape and polarity, this process regulates vital T cell responses, such as T cell adhesion, motility, and proliferation. These depend on the recruitment of the signaling proteins Nck and Wiskott-Aldrich syndrome protein (WASp) to the site of TCR activation and on the functional properties of the adapter proteins linker for activation of T cells (LAT) and SH2-domain-containing leukocyte protein of 76 kDa (SLP76). We now demonstrate that Nck is necessary but insufficient for the recruitment of WASp. We show that two pathways lead to SLP76-dependent actin rearrangement. One requires the SLP76 acidic domain, crucial to association with the Nck SH2 domain, and another requires the SLP76 SH2 domain, essential for interaction with the adhesion- and degranulation-promoting adapter protein ADAP. Functional cooperation between Nck and ADAP mediates SLP76-WASp interactions and actin rearrangement. We also reveal the molecular mechanism linking ADAP to actin reorganization.
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10
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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: 41] [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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11
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Splice-site mutations cause Rrp6-mediated nuclear retention of the unspliced RNAs and transcriptional down-regulation of the splicing-defective genes. PLoS One 2010; 5:e11540. [PMID: 20634951 PMCID: PMC2902512 DOI: 10.1371/journal.pone.0011540] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Accepted: 06/16/2010] [Indexed: 12/18/2022] Open
Abstract
Background Eukaryotic cells have developed surveillance mechanisms to prevent the expression of aberrant transcripts. An early surveillance checkpoint acts at the transcription site and prevents the release of mRNAs that carry processing defects. The exosome subunit Rrp6 is required for this checkpoint in Saccharomyces cerevisiae, but it is not known whether Rrp6 also plays a role in mRNA surveillance in higher eukaryotes. Methodology/Principal Findings We have developed an in vivo system to study nuclear mRNA surveillance in Drosophila melanogaster. We have produced S2 cells that express a human β-globin gene with mutated splice sites in intron 2 (mut β-globin). The transcripts encoded by the mut β-globin gene are normally spliced at intron 1 but retain intron 2. The levels of the mut β-globin transcripts are much lower than those of wild type (wt) ß-globin mRNAs transcribed from the same promoter. We have compared the expression of the mut and wt β-globin genes to investigate the mechanisms that down-regulate the production of defective mRNAs. Both wt and mut β-globin transcripts are processed at the 3′, but the mut β-globin transcripts are less efficiently cleaved than the wt transcripts. Moreover, the mut β-globin transcripts are less efficiently released from the transcription site, as shown by FISH, and this defect is restored by depletion of Rrp6 by RNAi. Furthermore, transcription of the mut β-globin gene is significantly impaired as revealed by ChIP experiments that measure the association of the RNA polymerase II with the transcribed genes. We have also shown that the mut β-globin gene shows reduced levels of H3K4me3. Conclusions/Significance Our results show that there are at least two surveillance responses that operate cotranscriptionally in insect cells and probably in all metazoans. One response requires Rrp6 and results in the inefficient release of defective mRNAs from the transcription site. The other response acts at the transcription level and reduces the synthesis of the defective transcripts through a mechanism that involves histone modifications.
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12
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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: 44] [Impact Index Per Article: 2.9] [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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13
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Laurent L, Wong E, Li G, Huynh T, Tsirigos A, Ong CT, Low HM, Kin Sung KW, Rigoutsos I, Loring J, Wei CL. Dynamic changes in the human methylome during differentiation. Genome Res 2010; 20:320-31. [PMID: 20133333 DOI: 10.1101/gr.101907.109] [Citation(s) in RCA: 768] [Impact Index Per Article: 51.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
DNA methylation is a critical epigenetic regulator in mammalian development. Here, we present a whole-genome comparative view of DNA methylation using bisulfite sequencing of three cultured cell types representing progressive stages of differentiation: human embryonic stem cells (hESCs), a fibroblastic differentiated derivative of the hESCs, and neonatal fibroblasts. As a reference, we compared our maps with a methylome map of a fully differentiated adult cell type, mature peripheral blood mononuclear cells (monocytes). We observed many notable common and cell-type-specific features among all cell types. Promoter hypomethylation (both CG and CA) and higher levels of gene body methylation were positively correlated with transcription in all cell types. Exons were more highly methylated than introns, and sharp transitions of methylation occurred at exon-intron boundaries, suggesting a role for differential methylation in transcript splicing. Developmental stage was reflected in both the level of global methylation and extent of non-CpG methylation, with hESC highest, fibroblasts intermediate, and monocytes lowest. Differentiation-associated differential methylation profiles were observed for developmentally regulated genes, including the HOX clusters, other homeobox transcription factors, and pluripotence-associated genes such as POU5F1, TCF3, and KLF4. Our results highlight the value of high-resolution methylation maps, in conjunction with other systems-level analyses, for investigation of previously undetectable developmental regulatory mechanisms.
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Affiliation(s)
- Louise Laurent
- UCSD Medical Center, Department of Reproductive Medicine, San Diego, California 92103, USA
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14
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Kazerouninia A, Ngo B, Martinson HG. Poly(A) signal-dependent degradation of unprocessed nascent transcripts accompanies poly(A) signal-dependent transcriptional pausing in vitro. RNA (NEW YORK, N.Y.) 2010; 16:197-210. [PMID: 19926725 PMCID: PMC2802029 DOI: 10.1261/rna.1622010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2009] [Accepted: 09/22/2009] [Indexed: 05/28/2023]
Abstract
The poly(A) signal has long been known for its role in directing the cleavage and polyadenylation of eukaryotic mRNA. In recent years its additional coordinating role in multiple related aspects of gene expression has also become increasingly clear. Here we use HeLa nuclear extracts to study two of these activities, poly(A) signal-dependent transcriptional pausing, which was originally proposed as a surveillance checkpoint, and poly(A) signal-dependent degradation (PDD) of unprocessed transcripts from weak poly(A) signals. We confirm directly, by measuring the length of RNA within isolated transcription elongation complexes, that a newly transcribed poly(A) signal reduces the rate of elongation by RNA polymerase II and causes the accumulation of elongation complexes downstream from the poly(A) signal. We then show that if the RNA in these elongation complexes contains a functional but unprocessed poly(A) signal, degradation of the transcripts ensues. The degradation depends on the unprocessed poly(A) signal being functional, and does not occur if a mutant poly(A) signal is used. We suggest that during normal 3'-end processing the uncleaved poly(A) signal continuously samples competing reaction pathways for processing and for degradation, and that in the case of weak poly(A) signals, where poly(A) site cleavage is slow, the default pathway to degradation predominates.
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Affiliation(s)
- Amir Kazerouninia
- Department of Chemistry and Biochemistry, University of California at Los Angeles, Los Angeles, California 90095-1569, USA
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15
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Pawlicki JM, Steitz JA. Nuclear networking fashions pre-messenger RNA and primary microRNA transcripts for function. Trends Cell Biol 2009; 20:52-61. [PMID: 20004579 DOI: 10.1016/j.tcb.2009.10.004] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 10/15/2009] [Accepted: 10/20/2009] [Indexed: 10/20/2022]
Abstract
The expression of protein-coding genes is enhanced by the exquisite coupling of transcription by RNA polymerase II with pre-messenger RNA processing reactions, such as 5'-end capping, splicing and 3'-end formation. Integration between cotranscriptional processing events extends beyond the nucleus, as proteins that bind cotranscriptionally can affect the localization, translation and degradation of the mature messenger RNA. MicroRNAs are RNA polymerase II transcripts with crucial roles in the regulation of gene expression. Recent data demonstrate that processing of primary microRNA transcripts might be yet another cotranscriptional event that is woven into this elaborate nuclear network. This review discusses the extensive molecular interactions that couple the earliest steps in gene expression and therefore influence the final fate and function of the mature messenger RNA or microRNA produced.
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Affiliation(s)
- Jan M Pawlicki
- Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06536, USA
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16
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Perales R, Bentley D. "Cotranscriptionality": the transcription elongation complex as a nexus for nuclear transactions. Mol Cell 2009; 36:178-91. [PMID: 19854129 DOI: 10.1016/j.molcel.2009.09.018] [Citation(s) in RCA: 286] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Revised: 07/07/2009] [Accepted: 08/06/2009] [Indexed: 12/27/2022]
Abstract
Much of the complex process of RNP biogenesis takes place at the gene cotranscriptionally. The target for RNA binding and processing factors is, therefore, not a solitary RNA molecule but, rather, a transcription elongation complex (TEC) comprising the growing nascent RNA and RNA polymerase traversing a chromatin template with associated passenger proteins. RNA maturation factors are not the only nuclear machines whose work is organized cotranscriptionally around the TEC scaffold. Additionally, DNA repair, covalent chromatin modification, "gene gating" at the nuclear pore, Ig gene hypermutation, and sister chromosome cohesion have all been demonstrated or suggested to involve a cotranscriptional component. From this perspective, TECs can be viewed as potent "community organizers" within the nucleus.
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Affiliation(s)
- Roberto Perales
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, UCHSC, MS8101, P.O. Box 6511, Aurora CO, 80045, USA
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17
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Fabian Z, O’Brien P, Pajęcka K, Fearnhead HO. TPCK-induced apoptosis and labelling of the largest subunit of RNA polymerase II in Jurkat cells. Apoptosis 2009; 14:1154-64. [DOI: 10.1007/s10495-009-0386-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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18
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Rigo F, Martinson HG. Polyadenylation releases mRNA from RNA polymerase II in a process that is licensed by splicing. RNA (NEW YORK, N.Y.) 2009; 15:823-36. [PMID: 19304926 PMCID: PMC2673064 DOI: 10.1261/rna.1409209] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
When transcription is coupled to pre-mRNA processing in HeLa nuclear extracts nascent transcripts become attached to RNA polymerase II during assembly of the cleavage/polyadenylation apparatus (CPA), and are not released even after cleavage at the poly(A) site. Here we show that these cleaved transcripts are anchored to the polymerase at their 3' ends by the CPA or, when introns are present, by the larger 3'-terminal exon definition complex (EDC), which consists of splicing factors complexed with the CPA. Poly(A) addition releases the RNA from the polymerase when the RNA is anchored only by the CPA. When anchored by the EDC, poly(A) addition remains a requirement, but it triggers release only after being licensed by splicing. The process by which RNA must first be attached to the polymerase by the EDC, and then can only be released following dual inputs from splicing and polyadenylation, provides an obvious opportunity for surveillance as the RNA enters the transport pathway.
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Affiliation(s)
- Frank Rigo
- Department of Chemistry and Biochemistry, University of California at Los Angeles, Los Angeles, California 90095-1569, USA
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19
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Yoh SM, Lucas JS, Jones KA. The Iws1:Spt6:CTD complex controls cotranscriptional mRNA biosynthesis and HYPB/Setd2-mediated histone H3K36 methylation. Genes Dev 2009; 22:3422-34. [PMID: 19141475 DOI: 10.1101/gad.1720008] [Citation(s) in RCA: 185] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Many steps in gene expression and mRNA biosynthesis are coupled to transcription elongation and organized through the C-terminal domain (CTD) of the large subunit of RNA polymerase II (RNAPII). We showed recently that Spt6, a transcription elongation factor and histone H3 chaperone, binds to the Ser2P CTD and recruits Iws1 and the REF1/Aly mRNA export adaptor to facilitate mRNA export. Here we show that Iws1 also recruits the HYPB/Setd2 histone methyltransferase to the RNAPII elongation complex and is required for H3K36 trimethylation (H3K36me3) across the transcribed region of the c-Myc, HIV-1, and PABPC1 genes in vivo. Interestingly, knockdown of either Iws1 or HYPB/Setd2 also enhanced H3K27me3 at the 5' end of the PABPC1 gene, and depletion of Iws1, but not HYPB/Setd2, increased histone acetylation across the coding regions at the HIV-1 and PABPC1 genes in vivo. Knockdown of HYPB/Setd2, like Iws1, induced bulk HeLa poly(A)+ mRNAs to accumulate in the nucleus. In vitro, recombinant Spt6 binds selectively to a stretch of uninterrupted consensus repeats located in the N-terminal half of the CTD and recruits Iws1. Thus Iws1 connects two distinct CTD-binding proteins, Spt6 and HYPB/Setd2, in a megacomplex that affects mRNA export as well as the histone modification state of active genes.
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Affiliation(s)
- Sunnie M Yoh
- Regulatory Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
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20
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Wang IF, Wu LS, Shen CKJ. TDP-43: an emerging new player in neurodegenerative diseases. Trends Mol Med 2008; 14:479-85. [PMID: 18929508 DOI: 10.1016/j.molmed.2008.09.001] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Revised: 09/01/2008] [Accepted: 09/01/2008] [Indexed: 12/12/2022]
Abstract
Until a couple of years ago, TAR-DNA-binding protein-43 (TDP-43) was a relatively unknown nuclear protein implicated in transcriptional repression and splicing. Since 2006, when the protein was reported to be present in inclusions in the neurons and/or glial cells of a range of neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), frontotemporal lobar degeneration with ubiquitin-positive, tau- and alpha-synuclein-negative inclusions (FTLD-U) and Alzheimer's disease (AD), many reports on the medical aspects of TDP-43 have been published. Here, we summarize the current literature on TDP-43, focusing on recent studies that provide clues to the function of TDP-43. Using this information and database analysis, we also suggest a molecular and cellular model for possible events in normal and diseased neurons in relation to the emerging importance of the function and dysfunction of this protein as a target for basic as well as translational research.
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Affiliation(s)
- I-Fan Wang
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
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21
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Quality control of mRNP in the nucleus. Chromosoma 2008; 117:419-29. [PMID: 18563427 DOI: 10.1007/s00412-008-0166-4] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2008] [Revised: 05/03/2008] [Accepted: 05/05/2008] [Indexed: 12/30/2022]
Abstract
Formation of functional mRNA-protein particles requires a plethora of nuclear cotranscriptional and posttranscriptional RNA processing and packaging steps. Faithful execution of these events is closely monitored by surveillance systems that prevent nuclear export of, and/or rapidly degrade, faulty transcripts. Parts of this quality control also serve to eliminate a large number of noncoding RNAs produced by RNA polymerase II. Here, we discuss which aberrant features trigger messenger ribonucleoprotein quality control, how the process is executed, and how it is connected to the transcription machinery and the nuclear pore complex.
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22
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Chapman RD, Heidemann M, Hintermair C, Eick D. Molecular evolution of the RNA polymerase II CTD. Trends Genet 2008; 24:289-96. [PMID: 18472177 DOI: 10.1016/j.tig.2008.03.010] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2008] [Revised: 03/19/2008] [Accepted: 03/20/2008] [Indexed: 11/19/2022]
Abstract
In higher eukaryotes, an unusual C-terminal domain (CTD) is crucial to the function of RNA polymerase II in transcription. The CTD consists of multiple heptapeptide repeats; differences in the number of repeats between organisms and their degree of conservation have intrigued researchers for two decades. Here, we review the evolution of the CTD at the molecular level. Several primitive motifs have been integrated into compound heptads that can be readily amplified. The selection of phosphorylatable residues in the heptad repeat provided the opportunity for advanced gene regulation in eukaryotes. Current findings suggest that the CTD should be considered as a collection of continuous overlapping motifs as opposed to a specific functional unit defined by a heptad.
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Affiliation(s)
- Rob D Chapman
- Institute for Clinical Molecular Biology and Tumour Genetics, Helmholtz Center for Environmental Health, Center for Integrated Protein Science (CiPSM), D-81377 Munich, Germany.
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23
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Egloff S, Murphy S. Cracking the RNA polymerase II CTD code. Trends Genet 2008; 24:280-8. [PMID: 18457900 DOI: 10.1016/j.tig.2008.03.008] [Citation(s) in RCA: 289] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2008] [Revised: 03/20/2008] [Accepted: 03/20/2008] [Indexed: 01/24/2023]
Abstract
The carboxyl-terminal domain (CTD) of the largest subunit of RNA polymerase II comprises multiple tandem conserved heptapeptide repeats, unique to this eukaryotic RNA polymerase. This unusual structure provides a docking platform for factors involved in various co-transcriptional events. Recruitment of the appropriate factors at different stages of the transcription cycle is achieved through changing patterns of post-translational modification of the CTD repeats, which create a readable 'code'. A new phosphorylation mark both expands the CTD code and provides the first example of a CTD signal read in a gene type-specific manner. How and when is the code written and read? How does it contribute to transcription and coordinate RNA processing?
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Affiliation(s)
- Sylvain Egloff
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
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24
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de Almeida SF, Carmo-Fonseca M. The CTD role in cotranscriptional RNA processing and surveillance. FEBS Lett 2008; 582:1971-6. [PMID: 18435923 DOI: 10.1016/j.febslet.2008.04.019] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Revised: 04/13/2008] [Accepted: 04/14/2008] [Indexed: 11/24/2022]
Abstract
In higher eukaryotes, the production of mature messenger RNA that exits the nucleus to be translated into protein requires precise and extensive processing of the nascent transcript. The processing steps include 5'-end capping, splicing, and 3'-end formation. Pre-mRNA processing is coupled to transcription by mechanisms that are not well understood but involve the carboxyl-terminal domain (CTD) of the largest subunit of RNA polymerase II. This review focuses on recent findings that provide novel insight into the role of the CTD in promoting RNA processing and surveillance.
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Affiliation(s)
- Sérgio F de Almeida
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
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