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Staněk D. Coilin and Cajal bodies. Nucleus 2023; 14:2256036. [PMID: 37682044 PMCID: PMC10494742 DOI: 10.1080/19491034.2023.2256036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 08/24/2023] [Accepted: 08/28/2023] [Indexed: 09/09/2023] Open
Abstract
The nucleus of higher eukaryotes contains a number of structures that concentrate specific biomolecules and play distinct roles in nuclear metabolism. In recent years, the molecular mechanisms controlling their formation have been intensively studied. In this brief review, I focus on coilin and Cajal bodies. Coilin is a key scaffolding protein of Cajal bodies that is evolutionarily conserved in metazoans. Cajal bodies are thought to be one of the archetypal nuclear structures involved in the metabolism of several short non-coding nuclear RNAs. Yet surprisingly little is known about the structure and function of coilin, and a comprehensive model to explain the origin of Cajal bodies is also lacking. Here, I summarize recent results on Cajal bodies and coilin and discuss them in the context of the last three decades of research in this field.
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Affiliation(s)
- David Staněk
- Laboratory of RNA Biology, Institute of Molecular Genetics, Czech Academy of Sciences, Prague, Czech Republic
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2
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Bragado L, Magalnik M, Mammi P, Romero A, Gaioli N, Pozzi B, Srebrow A. SUMO conjugation regulates the activity of the Integrator complex. Nucleic Acids Res 2022; 50:12444-12461. [PMID: 36454007 PMCID: PMC9757034 DOI: 10.1093/nar/gkac1055] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 10/13/2022] [Accepted: 11/29/2022] [Indexed: 12/03/2022] Open
Abstract
RNA polymerase II (RNAPII) transcribes small nuclear RNA (snRNA) genes in close proximity to Cajal bodies, subnuclear compartments that depend on the SUMO isopeptidase USPL1 for their assembly. We show here that overexpression of USPL1 as well as of another nuclear SUMO isopeptidase, SENP6, alters snRNA 3'-end cleavage, a process carried out by the Integrator complex. Beyond its role in snRNA biogenesis, this complex is responsible for regulating the expression of different RNAPII transcripts. While several subunits of the complex are SUMO conjugation substrates, we found that the SUMOylation of the INTS11 subunit is regulated by USPL1 and SENP6. We defined Lys381, Lys462 and Lys475 as bona fide SUMO attachment sites on INTS11 and observed that SUMOylation of this protein modulates its subcellular localization and is required for Integrator activity. Moreover, while an INTS11 SUMOylation-deficient mutant is still capable of interacting with INTS4 and INTS9, its interaction with other subunits of the complex is affected. These findings point to a regulatory role for SUMO conjugation on Integrator activity and suggest the involvement of INTS11 SUMOylation in the assembly of the complex. Furthermore, this work adds Integrator-dependent RNA processing to the growing list of cellular processes regulated by SUMO conjugation.
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Affiliation(s)
- Laureano Bragado
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Fisiología, Biología Molecular y Celular, Buenos Aires, Argentina,CONICET-Universidad de Buenos Aires, Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Buenos Aires, Argentina
| | - Melina Magalnik
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Fisiología, Biología Molecular y Celular, Buenos Aires, Argentina,CONICET-Universidad de Buenos Aires, Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Buenos Aires, Argentina
| | - Pablo Mammi
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Fisiología, Biología Molecular y Celular, Buenos Aires, Argentina,CONICET-Universidad de Buenos Aires, Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Buenos Aires, Argentina
| | - Agustín Romero
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Fisiología, Biología Molecular y Celular, Buenos Aires, Argentina,CONICET-Universidad de Buenos Aires, Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Buenos Aires, Argentina
| | - Nicolás Gaioli
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Fisiología, Biología Molecular y Celular, Buenos Aires, Argentina,CONICET-Universidad de Buenos Aires, Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Buenos Aires, Argentina
| | - Berta Pozzi
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Fisiología, Biología Molecular y Celular, Buenos Aires, Argentina,CONICET-Universidad de Buenos Aires, Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Buenos Aires, Argentina
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3
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Górka S, Kubiak D, Ciesińska M, Niedojadło K, Tyburski J, Niedojadło J. Function of Cajal Bodies in Nuclear RNA Retention in A. thaliana Leaves Subjected to Hypoxia. Int J Mol Sci 2022; 23:ijms23147568. [PMID: 35886915 PMCID: PMC9321658 DOI: 10.3390/ijms23147568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 06/27/2022] [Accepted: 06/28/2022] [Indexed: 11/29/2022] Open
Abstract
Retention of RNA in the nucleus precisely regulates the time and rate of translation and controls transcriptional bursts that can generate profound variability in mRNA levels among identical cells in tissues. In this study, we investigated the function of Cajal bodies (CBs) in RNA retention in A. thaliana leaf nuclei during hypoxia stress was investigated. It was observed that in ncb-1 mutants with a complete absence of CBs, the accumulation of poly(A+) RNA in the leaf nuclei was lower than that in wt under stress. Moreover, unlike in root cells, CBs store less RNA, and RNA retention in the nuclei is much less intense. Our results reveal that the function of CBs in the accumulation of RNA in nuclei under stress depends on the plant organ. Additionally, in ncb-1, retention of introns of mRNA RPB1 (largest subunit of RNA polymerase II) mRNA was observed. However, this isoform is highly accumulated in the nucleus. It thus follows that intron retention in transcripts is more important than CBs for the accumulation of RNA in nuclei. Accumulated mRNAs with introns in the nucleus could escape transcript degradation by NMD (nonsense-mediated mRNA decay). From non-fully spliced mRNAs in ncb-1 nuclei, whose levels increase during hypoxia, introns are removed during reoxygenation. Then, the mRNA is transferred to the cytoplasm, and the RPB1 protein is translated. Despite the accumulation of isoforms in nuclei with retention of introns in reoxygenation, ncb-1 coped much worse with long hypoxia, and manifested faster yellowing and shrinkage of leaves.
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Affiliation(s)
- Sylwia Górka
- Department of Cellular and Molecular Biology, Nicolaus Copernicus University, Lwowska 1, 87-100 Toruń, Poland; (S.G.); (D.K.); (M.C.); (K.N.)
- Centre For Modern Interdisciplinary Technologies, Nicolaus Copernicus University, Wileńska 4, 87-100 Toruń, Poland
| | - Dawid Kubiak
- Department of Cellular and Molecular Biology, Nicolaus Copernicus University, Lwowska 1, 87-100 Toruń, Poland; (S.G.); (D.K.); (M.C.); (K.N.)
- Centre For Modern Interdisciplinary Technologies, Nicolaus Copernicus University, Wileńska 4, 87-100 Toruń, Poland
| | - Małgorzata Ciesińska
- Department of Cellular and Molecular Biology, Nicolaus Copernicus University, Lwowska 1, 87-100 Toruń, Poland; (S.G.); (D.K.); (M.C.); (K.N.)
| | - Katarzyna Niedojadło
- Department of Cellular and Molecular Biology, Nicolaus Copernicus University, Lwowska 1, 87-100 Toruń, Poland; (S.G.); (D.K.); (M.C.); (K.N.)
- Centre For Modern Interdisciplinary Technologies, Nicolaus Copernicus University, Wileńska 4, 87-100 Toruń, Poland
| | - Jarosław Tyburski
- Chair of Plant Physiology and Biotechnology, Nicolaus Copernicus University, Lwowska 1, 87-100 Toruń, Poland;
| | - Janusz Niedojadło
- Department of Cellular and Molecular Biology, Nicolaus Copernicus University, Lwowska 1, 87-100 Toruń, Poland; (S.G.); (D.K.); (M.C.); (K.N.)
- Centre For Modern Interdisciplinary Technologies, Nicolaus Copernicus University, Wileńska 4, 87-100 Toruń, Poland
- Correspondence:
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Roithová A, Feketová Z, Vaňáčová Š, Staněk D. DIS3L2 and LSm proteins are involved in the surveillance of Sm ring-deficient snRNAs. Nucleic Acids Res 2020; 48:6184-6197. [PMID: 32374871 PMCID: PMC7293007 DOI: 10.1093/nar/gkaa301] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 04/06/2020] [Accepted: 04/23/2020] [Indexed: 01/31/2023] Open
Abstract
Spliceosomal small nuclear ribonucleoprotein particles (snRNPs) undergo a complex maturation pathway containing multiple steps in the nucleus and in the cytoplasm. snRNP biogenesis is strictly proofread and several quality control checkpoints are placed along the pathway. Here, we analyzed the fate of small nuclear RNAs (snRNAs) that are unable to acquire a ring of Sm proteins. We showed that snRNAs lacking the Sm ring are unstable and accumulate in P-bodies in an LSm1-dependent manner. We further provide evidence that defective snRNAs without the Sm binding site are uridylated at the 3′ end and associate with DIS3L2 3′→5′ exoribonuclease and LSm proteins. Finally, inhibition of 5′→3′ exoribonuclease XRN1 increases association of ΔSm snRNAs with DIS3L2, which indicates competition and compensation between these two degradation enzymes. Together, we provide evidence that defective snRNAs without the Sm ring are uridylated and degraded by alternative pathways involving either DIS3L2 or LSm proteins and XRN1.
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Affiliation(s)
- Adriana Roithová
- Laboratory of RNA Biology, Institute of Molecular Genetics of the Czech Academy of Sciences, Videnska 1083, 14220 Prague, Czech Republic.,Faculty of Science, Charles University, 128 00 Prague, Czech Republic
| | - Zuzana Feketová
- CEITEC-Central European Institute of Technology, Masaryk University, Kamenice 5/A35, 625 00 Brno, Czech Republic
| | - Štěpánka Vaňáčová
- CEITEC-Central European Institute of Technology, Masaryk University, Kamenice 5/A35, 625 00 Brno, Czech Republic
| | - David Staněk
- Laboratory of RNA Biology, Institute of Molecular Genetics of the Czech Academy of Sciences, Videnska 1083, 14220 Prague, Czech Republic
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Albrecht TR, Shevtsov SP, Wu Y, Mascibroda LG, Peart NJ, Huang KL, Sawyer IA, Tong L, Dundr M, Wagner EJ. Integrator subunit 4 is a 'Symplekin-like' scaffold that associates with INTS9/11 to form the Integrator cleavage module. Nucleic Acids Res 2019; 46:4241-4255. [PMID: 29471365 PMCID: PMC5934644 DOI: 10.1093/nar/gky100] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 02/17/2018] [Indexed: 12/14/2022] Open
Abstract
Integrator (INT) is a transcriptional regulatory complex associated with RNA polymerase II that is required for the 3′-end processing of both UsnRNAs and enhancer RNAs. Integrator subunits 9 (INTS9) and INTS11 constitute the catalytic core of INT and are paralogues of the cleavage and polyadenylation specificity factors CPSF100 and CPSF73. While CPSF73/100 are known to associate with a third protein called Symplekin, there is no paralog of Symplekin within INT raising the question of how INTS9/11 associate with the other INT subunits. Here, we have identified that INTS4 is a specific and conserved interaction partner of INTS9/11 that does not interact with either subunit individually. Although INTS4 has no significant homology with Symplekin, it possesses N-terminal HEAT repeats similar to Symplekin but also contains a β-sheet rich C-terminal region, both of which are important to bind INTS9/11. We assess three functions of INT including UsnRNA 3′-end processing, maintenance of Cajal body structural integrity, and formation of histone locus bodies to conclude that INTS4/9/11 are the most critical of the INT subunits for UsnRNA biogenesis. Altogether, these results indicate that INTS4/9/11 compose a heterotrimeric complex that likely represents the Integrator ‘cleavage module’ responsible for its endonucleolytic activity.
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Affiliation(s)
- Todd R Albrecht
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, Galveston, TX 77550, USA
| | - Sergey P Shevtsov
- Department of Cell Biology, Rosalind Franklin University of Medicine and Science, Chicago Medical School, North Chicago, IL 60064, USA
| | - Yixuan Wu
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Lauren G Mascibroda
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, Galveston, TX 77550, USA
| | - Natoya J Peart
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, Galveston, TX 77550, USA
| | - Kai-Lieh Huang
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, Galveston, TX 77550, USA
| | - Iain A Sawyer
- Department of Cell Biology, Rosalind Franklin University of Medicine and Science, Chicago Medical School, North Chicago, IL 60064, USA.,Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Liang Tong
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Miroslav Dundr
- Department of Cell Biology, Rosalind Franklin University of Medicine and Science, Chicago Medical School, North Chicago, IL 60064, USA
| | - Eric J Wagner
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, Galveston, TX 77550, USA
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Shah FR, Bhat YA, Wani AH. Subnuclear distribution of proteins: Links with genome architecture. Nucleus 2018; 9:42-55. [PMID: 28910577 PMCID: PMC5973252 DOI: 10.1080/19491034.2017.1361578] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 07/25/2017] [Accepted: 07/26/2017] [Indexed: 02/08/2023] Open
Abstract
Metazoan genomes have a hierarchal 3-dimensional (3D) organization scaling from nucleosomes, loops, topologically associating domains (TADs), compartments, to chromosome territories. The 3D organization of genome has been linked with development, differentiation and disease. However, the principles governing the 3D chromatin architecture are just beginning to get unraveled. The nucleus has very high concentration of proteins and these proteins are either diffusely distributed throughout the nucleus, or aggregated in the form of foci/bodies/clusters/speckles or in combination of both. Several evidences suggest that the distribution of proteins within the nuclear space is linked to the organization and function of genome. Here, we describe advances made in understanding the relationship between subnuclear distribution of proteins and genome architecture.
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Affiliation(s)
- Fouziya R. Shah
- Biotechnology, School of Biological Sciences, University of Kashmir, Srinagar, India
| | - Younus A. Bhat
- Biotechnology, School of Biological Sciences, University of Kashmir, Srinagar, India
| | - Ajazul H. Wani
- Biotechnology, School of Biological Sciences, University of Kashmir, Srinagar, India
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Gruss OJ, Meduri R, Schilling M, Fischer U. UsnRNP biogenesis: mechanisms and regulation. Chromosoma 2017; 126:577-593. [PMID: 28766049 DOI: 10.1007/s00412-017-0637-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 07/14/2017] [Accepted: 07/14/2017] [Indexed: 12/24/2022]
Abstract
Macromolecular complexes composed of proteins or proteins and nucleic acids rather than individual macromolecules mediate many cellular activities. Maintenance of these activities is essential for cell viability and requires the coordinated production of the individual complex components as well as their faithful incorporation into functional entities. Failure of complex assembly may have fatal consequences and can cause severe diseases. While many macromolecular complexes can form spontaneously in vitro, they often require aid from assembly factors including assembly chaperones in the crowded cellular environment. The assembly of RNA protein complexes implicated in the maturation of pre-mRNAs (termed UsnRNPs) has proven to be a paradigm to understand the action of assembly factors and chaperones. UsnRNPs are assembled by factors united in protein arginine methyltransferase 5 (PRMT5)- and survival motor neuron (SMN)-complexes, which act sequentially in the UsnRNP production line. While the PRMT5-complex pre-arranges specific sets of proteins into stable intermediates, the SMN complex displaces assembly factors from these intermediates and unites them with UsnRNA to form the assembled RNP. Despite advanced mechanistic understanding of UsnRNP assembly, our knowledge of regulatory features of this essential and ubiquitous cellular function remains remarkably incomplete. One may argue that the process operates as a default biosynthesis pathway and does not require sophisticated regulatory cues. Simple theoretical considerations and a number of experimental data, however, indicate that regulation of UsnRNP assembly most likely happens at multiple levels. This review will not only summarize how individual components of this assembly line act mechanistically but also why, how, and when the UsnRNP workflow might be regulated by means of posttranslational modification in response to cellular signaling cues.
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Affiliation(s)
- Oliver J Gruss
- Department of Genetics, Rheinische Friedrich-Wilhelms-Universität Bonn, Karlrobert-Kreiten-Str. 13, 53115, Bonn, Germany.
| | - Rajyalakshmi Meduri
- Department of Biochemistry, University of Würzburg, Biozentrum, Am Hubland, D-97074, Würzburg, Germany
| | - Maximilian Schilling
- Department of Genetics, Rheinische Friedrich-Wilhelms-Universität Bonn, Karlrobert-Kreiten-Str. 13, 53115, Bonn, Germany
| | - Utz Fischer
- Department of Biochemistry, University of Würzburg, Biozentrum, Am Hubland, D-97074, Würzburg, Germany.
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Raimer AC, Gray KM, Matera AG. SMN - A chaperone for nuclear RNP social occasions? RNA Biol 2017; 14:701-711. [PMID: 27648855 PMCID: PMC5519234 DOI: 10.1080/15476286.2016.1236168] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 09/01/2016] [Accepted: 09/09/2016] [Indexed: 12/24/2022] Open
Abstract
Survival Motor Neuron (SMN) protein localizes to both the nucleus and the cytoplasm. Cytoplasmic SMN is diffusely localized in large oligomeric complexes with core member proteins, called Gemins. Biochemical and cell biological studies have demonstrated that the SMN complex is required for the cytoplasmic assembly and nuclear transport of Sm-class ribonucleoproteins (RNPs). Nuclear SMN accumulates with spliceosomal small nuclear (sn)RNPs in Cajal bodies, sub-domains involved in multiple facets of snRNP maturation. Thus, the SMN complex forms stable associations with both nuclear and cytoplasmic snRNPs, and plays a critical role in their biogenesis. In this review, we focus on potential functions of the nuclear SMN complex, with particular emphasis on its role within the Cajal body.
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Affiliation(s)
- Amanda C. Raimer
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Kelsey M. Gray
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - A. Gregory Matera
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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9
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Sawyer IA, Hager GL, Dundr M. Specific genomic cues regulate Cajal body assembly. RNA Biol 2017; 14:791-803. [PMID: 27715441 PMCID: PMC5519236 DOI: 10.1080/15476286.2016.1243648] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 09/06/2016] [Accepted: 09/27/2016] [Indexed: 02/07/2023] Open
Abstract
The assembly of specialized sub-nuclear microenvironments known as nuclear bodies (NBs) is important for promoting efficient nuclear function. In particular, the Cajal body (CB), a prominent NB that facilitates spliceosomal snRNP biogenesis, assembles in response to genomic cues. Here, we detail the factors that regulate CB assembly and structural maintenance. These include the importance of transcription at nucleating gene loci, the grouping of these genes on human chromosomes 1, 6 and 17, as well as cell cycle and biochemical regulation of CB protein function. We also speculate on the correlation between CB formation and RNA splicing levels in neurons and cancer. The timing and location of these specific molecular events is critical to CB assembly and its contribution to genome function. However, further work is required to explore the emerging biophysical characteristics of CB assembly and the impact upon subsequent genome reorganization.
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Affiliation(s)
- Iain A. Sawyer
- Department of Cell Biology, Rosalind Franklin University of Medicine & Science, Chicago Medical School, North Chicago, IL, USA
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Gordon L. Hager
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Miroslav Dundr
- Department of Cell Biology, Rosalind Franklin University of Medicine & Science, Chicago Medical School, North Chicago, IL, USA
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Ohtani M. Plant snRNP Biogenesis: A Perspective from the Nucleolus and Cajal Bodies. FRONTIERS IN PLANT SCIENCE 2017; 8:2184. [PMID: 29354141 PMCID: PMC5758608 DOI: 10.3389/fpls.2017.02184] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 12/12/2017] [Indexed: 05/20/2023]
Abstract
Small nuclear ribonucleoproteins (snRNPs) are protein-RNA complexes composed of specific snRNP-associated proteins along with small nuclear RNAs (snRNAs), which are non-coding RNA molecules abundant in the nucleus. snRNPs mainly function as core components of the spliceosome, the molecular machinery for pre-mRNA splicing. Thus, snRNP biogenesis is a critical issue for plants, essential for the determination of a cell's activity through the regulation of gene expression. The complex process of snRNP biogenesis is initiated by transcription of the snRNA in the nucleus, continues in the cytoplasm, and terminates back in the nucleus. Critical steps of snRNP biogenesis, such as chemical modification of the snRNA and snRNP maturation, occur in the nucleolus and its related sub-nuclear structures, Cajal bodies. In this review, I discuss roles for the nucleolus and Cajal bodies in snRNP biogenesis, and a possible linkage between the regulation of snRNP biogenesis and plant development and environmental responses.
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Affiliation(s)
- Misato Ohtani
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Japan
- RIKEN Center for Sustainable Resource Science, Yokohama, Japan
- *Correspondence: Misato Ohtani,
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Sawyer IA, Sturgill D, Sung MH, Hager GL, Dundr M. Cajal body function in genome organization and transcriptome diversity. Bioessays 2016; 38:1197-1208. [PMID: 27767214 DOI: 10.1002/bies.201600144] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Nuclear bodies contribute to non-random organization of the human genome and nuclear function. Using a major prototypical nuclear body, the Cajal body, as an example, we suggest that these structures assemble at specific gene loci located across the genome as a result of high transcriptional activity. Subsequently, target genes are physically clustered in close proximity in Cajal body-containing cells. However, Cajal bodies are observed in only a limited number of human cell types, including neuronal and cancer cells. Ultimately, Cajal body depletion perturbs splicing kinetics by reducing target small nuclear RNA (snRNA) transcription and limiting the levels of spliceosomal snRNPs, including their modification and turnover following each round of RNA splicing. As such, Cajal bodies are capable of shaping the chromatin interaction landscape and the transcriptome by influencing spliceosome kinetics. Future studies should concentrate on characterizing the direct influence of Cajal bodies upon snRNA gene transcriptional dynamics. Also see the video abstract here.
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Affiliation(s)
- Iain A Sawyer
- Department of Cell Biology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA.,Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - David Sturgill
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Myong-Hee Sung
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Gordon L Hager
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Miroslav Dundr
- Department of Cell Biology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA
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Abstract
Spliceosomal snRNPs are complex particles that proceed through a fascinating maturation pathway. Several steps of this pathway are closely linked to nuclear non-membrane structures called Cajal bodies. In this review, I summarize the last 20 y of research in this field. I primarily focus on snRNP biogenesis, specifically on the steps that involve Cajal bodies. I also evaluate the contribution of the Cajal body in snRNP quality control and discuss the role of snRNPs in Cajal body formation.
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Affiliation(s)
- David Staněk
- a Institute of Molecular Genetics, Czech Academy of Sciences , Prague , Czech Republic
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13
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Abstract
Initially identified as a marker of coiled bodies (now Cajal bodies or CBs), the protein coilin was discovered a quarter of century ago. Coilin is now known to scaffold the CB, but its structure and function are poorly understood. Nearly devoid of predicted structural motifs, coilin has numerous reported molecular interactions that must underlie its role in the formation and function of CBs. In this review, we summarize what we have learned in the past 25 years about coilin's structure, post-transcriptional modifications, and interactions with RNA and proteins. We show that genes with homology to human coilin are found in primitive metazoans and comment on differences among model organisms. Coilin's function in Cajal body formation and RNP metabolism will be discussed in the light of these developments.
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Affiliation(s)
- Martin Machyna
- a Department of Molecular Biophysics & Biochemistry ; Yale University ; New Haven , CT USA
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Sloan KE, Gleizes PE, Bohnsack MT. Nucleocytoplasmic Transport of RNAs and RNA-Protein Complexes. J Mol Biol 2015; 428:2040-59. [PMID: 26434509 DOI: 10.1016/j.jmb.2015.09.023] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 09/26/2015] [Accepted: 09/28/2015] [Indexed: 12/15/2022]
Abstract
RNAs and ribonucleoprotein complexes (RNPs) play key roles in mediating and regulating gene expression. In eukaryotes, most RNAs are transcribed, processed and assembled with proteins in the nucleus and then either function in the cytoplasm or also undergo a cytoplasmic phase in their biogenesis. This compartmentalization ensures that sequential steps in gene expression and RNP production are performed in the correct order and it allows important quality control mechanisms that prevent the involvement of aberrant RNAs/RNPs in these cellular pathways. The selective exchange of RNAs/RNPs between the nucleus and cytoplasm is enabled by nuclear pore complexes, which function as gateways between these compartments. RNA/RNP transport is facilitated by a range of nuclear transport receptors and adaptors, which are specifically recruited to their cargos and mediate interactions with nucleoporins to allow directional translocation through nuclear pore complexes. While some transport factors are only responsible for the export/import of a certain class of RNA/RNP, others are multifunctional and, in the case of large RNPs, several export factors appear to work together to bring about export. Recent structural studies have revealed aspects of the mechanisms employed by transport receptors to enable specific cargo recognition, and genome-wide approaches have provided the first insights into the diverse composition of pre-mRNPs during export. Furthermore, the regulation of RNA/RNP export is emerging as an important means to modulate gene expression under stress conditions and in disease.
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Affiliation(s)
- Katherine E Sloan
- Institute for Molecular Biology, Goettingen University Medical Department, 37073 Goettingen, Germany
| | - Pierre-Emmanuel Gleizes
- Laboratoire de Biologie Moléculaire Eucaryote, UMR 5099, Université de Toulouse-Paul Sabatier, CNRS, Toulouse, France
| | - Markus T Bohnsack
- Institute for Molecular Biology, Goettingen University Medical Department, 37073 Goettingen, Germany; Goettingen Centre for Molecular Biosciences, Georg-August-University, 37075 Goettingen, Germany.
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15
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Abstract
Chromatin, once thought to serve only as a means to package DNA, is now recognized as a major regulator of gene activity. As a result of the wide range of methods used to describe the numerous levels of chromatin organization, the terminology that has emerged to describe these organizational states is often imprecise and sometimes misleading. In this review, we discuss our current understanding of chromatin architecture and propose terms to describe the various biochemical and structural states of chromatin.
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Affiliation(s)
- Liron Even-Faitelson
- Program in Genetics and Genome Biology, The Hospital for Sick Children, 686 Bay Street, Toronto, ON, M5G 0A4, Canada
| | | | - Zahra Baghestani
- Program in Genetics and Genome Biology, The Hospital for Sick Children, 686 Bay Street, Toronto, ON, M5G 0A4, Canada
| | - David P Bazett-Jones
- Program in Genetics and Genome Biology, The Hospital for Sick Children, 686 Bay Street, Toronto, ON, M5G 0A4, Canada.
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16
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Gavrilov AA, Razin SV. Compartmentalization of the cell nucleus and spatial organization of the genome. Mol Biol 2015. [DOI: 10.1134/s0026893315010033] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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17
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Kołowerzo-Lubnau A, Niedojadło J, Świdziński M, Bednarska-Kozakiewicz E, Smoliński DJ. Transcriptional activity in diplotene larch microsporocytes, with emphasis on the diffuse stage. PLoS One 2015; 10:e0117337. [PMID: 25671569 PMCID: PMC4324999 DOI: 10.1371/journal.pone.0117337] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2014] [Accepted: 12/22/2014] [Indexed: 12/22/2022] Open
Abstract
Manuscript provides insights into the biology of long-lived plants, different from Arabidopsis, tomato or grass species that are widely studied. In the European larch the diplotene stage lasts approximately 5 months and it is possible to divide it into several substages and to observe each of them in details. The diplotene stage is a period of intensive microsporocyte growth associated with the synthesis and accumulation of different RNA and proteins. Larch microsporocytes display changes in chromatin morphology during this stage, alternating between 4 short stages of chromatin condensation (contraction) and 5 longer diffusion (relaxation) stages. The occurrence of a diplotene diffusion stage has been observed in many plant species. Interestingly, they have also been observed during spermiogenesis and oogenesis in animals. The aim of this study was to examine whether chromatin relaxation during the diplotene is accompanied by the synthesis and maturation of mRNA. The results reveal a correlation between the diffusion and chromatin decondensation, transcriptional activity. We also found decreasing amount of poly(A) mRNA synthesis in the consecutive diffusion stages. During the early diffusion stages, mRNA is intensively synthesized. In the nuclei large amounts of RNA polymerase II, and high levels of snRNPs were observed. In the late diffusion stages, the synthesized mRNA is not directly subjected to translation but it is stored in the nucleus, and later transported to the cytoplasm and translated. In the last diffusion stage, the level of poly(A) RNA is low, but that of splicing factors is still high. It appears that the mRNA synthesized in early stages is used during the diplotene stage and is not transmitted to dyad and tetrads. In contrast, splicing factors accumulate and are most likely transmitted to the dyad and tetrads, where they are used after the resumption of intense transcription. Similar meiotic process were observed during oogenesis in animals. This indicates the existence of an evolutionarily conserved mechanism of chromatin-based regulation of gene expression during meiotic prophase I.
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Affiliation(s)
- Agnieszka Kołowerzo-Lubnau
- Department of Cell Biology, Faculty of Biology and Environment Protection, Nicolaus Copernicus University, Toruń, Poland
- Centre For Modern Interdisciplinary Technologies, Nicolaus Copernicus University, Toruń, Poland
- * E-mail: (AKL); (DJS)
| | - Janusz Niedojadło
- Department of Cell Biology, Faculty of Biology and Environment Protection, Nicolaus Copernicus University, Toruń, Poland
| | - Michał Świdziński
- Department of Cell Biology, Faculty of Biology and Environment Protection, Nicolaus Copernicus University, Toruń, Poland
| | - Elżbieta Bednarska-Kozakiewicz
- Department of Cell Biology, Faculty of Biology and Environment Protection, Nicolaus Copernicus University, Toruń, Poland
| | - Dariusz J. Smoliński
- Department of Cell Biology, Faculty of Biology and Environment Protection, Nicolaus Copernicus University, Toruń, Poland
- Centre For Modern Interdisciplinary Technologies, Nicolaus Copernicus University, Toruń, Poland
- * E-mail: (AKL); (DJS)
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18
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Schertzer M, Jouravleva K, Perderiset M, Dingli F, Loew D, Le Guen T, Bardoni B, de Villartay JP, Revy P, Londoño-Vallejo A. Human regulator of telomere elongation helicase 1 (RTEL1) is required for the nuclear and cytoplasmic trafficking of pre-U2 RNA. Nucleic Acids Res 2015; 43:1834-47. [PMID: 25628358 PMCID: PMC4330364 DOI: 10.1093/nar/gku1402] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Hoyeraal-Hreidarsson syndrome (HHS) is a severe form of Dyskeratosis congenita characterized by developmental defects, bone marrow failure and immunodeficiency and has been associated with telomere dysfunction. Recently, mutations in Regulator of Telomere ELongation helicase 1 (RTEL1), a helicase first identified in Mus musculus as being responsible for the maintenance of long telomeres, have been identified in several HHS patients. Here we show that RTEL1 is required for the export and the correct cytoplasmic trafficking of the small nuclear (sn) RNA pre-U2, a component of the major spliceosome complex. RTEL1-HHS cells show abnormal subcellular partitioning of pre-U2, defects in the recycling of ribonucleotide proteins (RNP) in the cytoplasm and splicing defects. While most of these phenotypes can be suppressed by re-expressing the wild-type protein in RTEL1-HHS cells, expression of RTEL1 mutated variants in immortalized cells provokes cytoplasmic mislocalizations of pre-U2 and other RNP components, as well as splicing defects, thus phenocopying RTEL1-HHS cellular defects. Strikingly, expression of a cytoplasmic form of RTEL1 is sufficient to correct RNP mislocalizations both in RTEL1-HHS cells and in cells expressing nuclear mutated forms of RTEL1. This work unravels completely unanticipated roles for RTEL1 in RNP trafficking and strongly suggests that defects in RNP biogenesis pathways contribute to the pathology of HHS.
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Affiliation(s)
- Michael Schertzer
- Telomeres & Cancer laboratory, CNRS, 'Labellisé Ligue', Institut Curie, 26 rue d'Ulm, Paris 75248, France Sorbonne Universités, Paris 06, Paris F-75005, France PSL Research University, Paris, France
| | - Karina Jouravleva
- Telomeres & Cancer laboratory, CNRS, 'Labellisé Ligue', Institut Curie, 26 rue d'Ulm, Paris 75248, France Sorbonne Universités, Paris 06, Paris F-75005, France PSL Research University, Paris, France
| | - Mylene Perderiset
- Telomeres & Cancer laboratory, CNRS, 'Labellisé Ligue', Institut Curie, 26 rue d'Ulm, Paris 75248, France Sorbonne Universités, Paris 06, Paris F-75005, France PSL Research University, Paris, France
| | - Florent Dingli
- Laboratory of Proteomic Mass Spectrometry, Institut Curie, Paris, France
| | - Damarys Loew
- Laboratory of Proteomic Mass Spectrometry, Institut Curie, Paris, France
| | - Tangui Le Guen
- INSERM UMR 1163, Laboratory of Genome Dynamics in the Immune System, Paris, France Université Sorbonne Paris Cité, Université Paris Descartes, Institut Imagine, Paris, France
| | - Barbara Bardoni
- IPMC-CNRS UMR7275-Valbonne, France Université de Nice Sophia-Antipolis, Nice 06560, France
| | - Jean-Pierre de Villartay
- INSERM UMR 1163, Laboratory of Genome Dynamics in the Immune System, Paris, France Université Sorbonne Paris Cité, Université Paris Descartes, Institut Imagine, Paris, France
| | - Patrick Revy
- INSERM UMR 1163, Laboratory of Genome Dynamics in the Immune System, Paris, France Université Sorbonne Paris Cité, Université Paris Descartes, Institut Imagine, Paris, France
| | - Arturo Londoño-Vallejo
- Telomeres & Cancer laboratory, CNRS, 'Labellisé Ligue', Institut Curie, 26 rue d'Ulm, Paris 75248, France Sorbonne Universités, Paris 06, Paris F-75005, France PSL Research University, Paris, France
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19
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Ulianov SV, Gavrilov AA, Razin SV. Nuclear Compartments, Genome Folding, and Enhancer-Promoter Communication. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 315:183-244. [DOI: 10.1016/bs.ircmb.2014.11.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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20
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Machyna M, Kehr S, Straube K, Kappei D, Buchholz F, Butter F, Ule J, Hertel J, Stadler PF, Neugebauer KM. The coilin interactome identifies hundreds of small noncoding RNAs that traffic through Cajal bodies. Mol Cell 2014; 56:389-399. [PMID: 25514182 DOI: 10.1016/j.molcel.2014.10.004] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Revised: 08/25/2014] [Accepted: 10/02/2014] [Indexed: 12/21/2022]
Abstract
Coilin protein scaffolds Cajal bodies (CBs)-subnuclear compartments enriched in small nuclear RNAs (snRNAs)-and promotes efficient spliceosomal snRNP assembly. The molecular function of coilin, which is intrinsically disordered with no defined motifs, is poorly understood. We use UV crosslinking and immunoprecipitation (iCLIP) to determine whether mammalian coilin binds RNA in vivo and to identify targets. Robust detection of snRNA transcripts correlated with coilin ChIP-seq peaks on snRNA genes, indicating that coilin binding to nascent snRNAs is a site-specific CB nucleator. Surprisingly, several hundred small nucleolar RNAs (snoRNAs) were identified as coilin interactors, including numerous unannotated mouse and human snoRNAs. We show that all classes of snoRNAs concentrate in CBs. Moreover, snoRNAs lacking specific CB retention signals traffic through CBs en route to nucleoli, consistent with the role of CBs in small RNP assembly. Thus, coilin couples snRNA and snoRNA biogenesis, making CBs the cellular hub of small ncRNA metabolism.
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Affiliation(s)
- Martin Machyna
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany; Department of Molecular Biophysics & Biochemistry, Yale University, 333 Cedar Street, New Haven, CT 06520, USA
| | - Stephanie Kehr
- Bioinformatics Group, Department of Computer Science and Interdisciplinary Center for Bioinformatics, University of Leipzig, Haertelstrasse 16-18, 04107 Leipzig, Germany
| | - Korinna Straube
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany; Department of Molecular Biophysics & Biochemistry, Yale University, 333 Cedar Street, New Haven, CT 06520, USA
| | - Dennis Kappei
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Frank Buchholz
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Falk Butter
- Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz, Germany
| | - Jernej Ule
- Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Jana Hertel
- Bioinformatics Group, Department of Computer Science and Interdisciplinary Center for Bioinformatics, University of Leipzig, Haertelstrasse 16-18, 04107 Leipzig, Germany
| | - Peter F Stadler
- Bioinformatics Group, Department of Computer Science and Interdisciplinary Center for Bioinformatics, University of Leipzig, Haertelstrasse 16-18, 04107 Leipzig, Germany
| | - Karla M Neugebauer
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany; Department of Molecular Biophysics & Biochemistry, Yale University, 333 Cedar Street, New Haven, CT 06520, USA.
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21
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Abstract
This review summarizes the current understanding of the role of nuclear bodies in regulating gene expression. The compartmentalization of cellular processes, such as ribosome biogenesis, RNA processing, cellular response to stress, transcription, modification and assembly of spliceosomal snRNPs, histone gene synthesis and nuclear RNA retention, has significant implications for gene regulation. These functional nuclear domains include the nucleolus, nuclear speckle, nuclear stress body, transcription factory, Cajal body, Gemini of Cajal body, histone locus body and paraspeckle. We herein review the roles of nuclear bodies in regulating gene expression and their relation to human health and disease.
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Affiliation(s)
| | - Cornelius F. Boerkoel
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-604-875-2157; Fax: +1-604-875-2376
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22
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Enwerem II, Velma V, Broome HJ, Kuna M, Begum RA, Hebert MD. Coilin association with Box C/D scaRNA suggests a direct role for the Cajal body marker protein in scaRNP biogenesis. Biol Open 2014; 3:240-9. [PMID: 24659245 PMCID: PMC3988793 DOI: 10.1242/bio.20147443] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Spliceosomal small nuclear ribonucleoproteins (snRNPs) are enriched in the Cajal body (CB). Guide RNAs, known as small Cajal body-specific RNAs (scaRNAs), direct modification of the small nuclear RNA (snRNA) component of the snRNP. The protein WRAP53 binds a sequence motif (the CAB box) found in many scaRNAs and the RNA component of telomerase (hTR) and targets these RNAs to the CB. We have previously reported that coilin, the CB marker protein, associates with certain non-coding RNAs. For a more comprehensive examination of the RNAs associated with coilin, we have sequenced the RNA isolated from coilin immunocomplexes. A striking preferential association of coilin with the box C/D scaRNAs 2 and 9, which lack a CAB box, was observed. This association varied by treatment condition and WRAP53 knockdown. In contrast, reduction of WRAP53 did not alter the level of coilin association with hTR. Additional studies showed that coilin degrades/processes scaRNA 2 and 9, associates with active telomerase and can influence telomerase activity. These findings suggest that coilin plays a novel role in the biogenesis of box C/D scaRNPs and telomerase.
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Affiliation(s)
- Isioma I Enwerem
- Department of Biochemistry, The University of Mississippi Medical Center, Jackson, MS 39216-4505, USA
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23
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Abstract
One of the most amazing findings in molecular biology was the discovery that eukaryotic genes are discontinuous, with coding DNA being interrupted by stretches of non-coding sequence. The subsequent realization that the intervening regions are removed from pre-mRNA transcripts via the activity of a common set of small nuclear RNAs (snRNAs), which assemble together with associated proteins into a complex known as the spliceosome, was equally surprising. How do cells coordinate the assembly of this molecular machine? And how does the spliceosome accurately recognize exons and introns to carry out the splicing reaction? Insights into these questions have been gained by studying the life cycle of spliceosomal snRNAs from their transcription, nuclear export and re-import to their dynamic assembly into the spliceosome. This assembly process can also affect the regulation of alternative splicing and has implications for human disease.
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Affiliation(s)
- A Gregory Matera
- Department of Biology, Department of Genetics and Integrative Program for Biological and Genome Sciences, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Zefeng Wang
- Department of Pharmacology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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24
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Byron M, Hall LL, Lawrence JB. A multifaceted FISH approach to study endogenous RNAs and DNAs in native nuclear and cell structures. ACTA ACUST UNITED AC 2013; Chapter 4:Unit 4.15. [PMID: 23315927 DOI: 10.1002/0471142905.hg0415s76] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Fluorescence in situ hybridization (FISH) is not a singular technique, but a battery of powerful and versatile tools for examining the distribution of endogenous genes and RNAs in precise context with each other and in relation to specific proteins or cell structures. This unit offers the details of highly sensitive and successful protocols that were initially developed largely in our lab and honed over a number of years. Our emphasis is on analysis of nuclear RNAs and DNA to address specific biological questions about nuclear structure, pre-mRNA metabolism, or the role of noncoding RNAs; however, cytoplasmic RNA detection is also discussed. Multifaceted molecular cytological approaches bring precise resolution and sensitive multicolor detection to illuminate the organization and functional roles of endogenous genes and their RNAs within the native structure of fixed cells. Solutions to several common technical pitfalls are discussed, as are cautions regarding the judicious use of digital imaging and the rigors of analyzing and interpreting complex molecular cytological results.
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Affiliation(s)
- Meg Byron
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, USA
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25
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Machyna M, Heyn P, Neugebauer KM. Cajal bodies: where form meets function. WILEY INTERDISCIPLINARY REVIEWS-RNA 2012; 4:17-34. [PMID: 23042601 DOI: 10.1002/wrna.1139] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The cell nucleus contains dozens of subcompartments that separate biochemical processes into confined spaces. Cajal bodies (CBs) were discovered more than 100 years ago, but only extensive research in the past decades revealed the surprising complexity of molecular and cellular functions taking place in these structures. Many protein and RNA species are modified and assembled within CBs, which have emerged as a meeting place and factory for ribonucleoprotein (RNP) particles involved in splicing, ribosome biogenesis and telomere maintenance. Recently, a distinct structure near histone gene clusters--the Histone locus body (HLB)--was discovered. Involved in histone mRNA 3'-end formation, HLBs can share several components with CBs. Whether the appearance of distinct HLBs is simply a matter of altered affinity between these structures or of an alternate mode of CB assembly is unknown. However, both structures share basic assembly properties, in which transcription plays a decisive role in initiation. After this seeding event, additional components associate in random order. This appears to be a widespread mechanism for body assembly. CB assembly encompasses an additional layer of complexity, whereby a set of pre-existing substructures can be integrated into mature CBs. We propose this as a multi-seeding model of CB assembly.
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Affiliation(s)
- Martin Machyna
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
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26
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In vitro RNase and nucleic acid binding activities implicate coilin in U snRNA processing. PLoS One 2012; 7:e36300. [PMID: 22558428 PMCID: PMC3338655 DOI: 10.1371/journal.pone.0036300] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Accepted: 04/04/2012] [Indexed: 11/21/2022] Open
Abstract
Coilin is known as the marker protein for Cajal bodies (CBs), subnuclear domains important for the biogenesis of small nuclear ribonucleoproteins (snRNPs) which function in pre-mRNA splicing. CBs associate non-randomly with U1 and U2 gene loci, which produce the small nuclear RNA (snRNA) component of the respective snRNP. Despite recognition as the CB marker protein, coilin is primarily nucleoplasmic, and the function of this fraction is not fully characterized. Here we show that coilin binds double stranded DNA and has RNase activity in vitro. U1 and U2 snRNAs undergo a processing event of the primary transcript prior to incorporation in the snRNP. We find that coilin displays RNase activity within the CU region of the U2 snRNA primary transcript in vitro, and that coilin knockdown results in accumulation of the 3′ pre-processed U1 and U2 snRNA. These findings present new characteristics of coilin in vitro, and suggest additional functions of the protein in vivo.
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27
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Suzuki T, Izumi H, Ohno M. Cajal body surveillance of U snRNA export complex assembly. J Cell Biol 2010; 190:603-12. [PMID: 20733056 PMCID: PMC2928011 DOI: 10.1083/jcb.201004109] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Accepted: 07/20/2010] [Indexed: 12/11/2022] Open
Abstract
Phosphorylated adaptor for RNA export (PHAX) is the key export mediator for spliceosomal U small nuclear RNA (snRNA) precursors in metazoa. PHAX is enriched in Cajal bodies (CBs), nuclear subdomains involved in the biogenesis of small ribonucleoproteins. However, CBs' role in U snRNA export has not been demonstrated. In this study, we show that U snRNA precursors microinjected into Xenopus laevis oocyte nuclei temporarily concentrate in CBs but gradually decrease as RNA export proceeds. Inhibition of PHAX activity by the coinjection of a specific anti-PHAX antibody or a dominant-negative PHAX mutant inhibits U snRNA export and simultaneously enhances accumulation of U snRNA precursors in CBs, indicating that U snRNAs transit through CBs before export and that binding to PHAX is required for efficient exit of U snRNAs from CBs. Similar results were obtained with U snRNAs transcribed from microinjected genes. These results reveal a novel function for CBs, which ensure that U snRNA precursors are properly bound by PHAX.
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Affiliation(s)
- Tatsuya Suzuki
- Institute for Virus Research, Kyoto University, Kyoto, Japan
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28
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Abstract
Eukaryotic gene expression is an intricate multistep process, regulated within the cell nucleus through the activation or repression of RNA synthesis, processing, cytoplasmic export, and translation into protein. The major regulators of gene expression are chromatin remodeling and transcription machineries that are locally recruited to genes. However, enzymatic activities that act on genes are not ubiquitously distributed throughout the nucleoplasm, but limited to specific and spatially defined foci that promote preferred higher-order chromatin arrangements. The positioning of genes within the nuclear landscape relative to specific functional landmarks plays an important role in gene regulation and disease.
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Affiliation(s)
- Carmelo Ferrai
- Genome Function Group, MRC Clinical Sciences Centre, Imperial College School of Medicine, Hammersmith Hospital Campus, Du Cane Road, London, United Kingdom
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29
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Kołowerzo A, Smoliński DJ, Bednarska E. Poly(A) RNA a new component of Cajal bodies. PROTOPLASMA 2009; 236:13-9. [PMID: 19415452 DOI: 10.1007/s00709-009-0042-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2009] [Accepted: 03/23/2009] [Indexed: 05/10/2023]
Abstract
In European larch microsporocytes, spherical structures 0.5 to 6 microm in diameter are present in which poly(A) RNA accumulates. There were one to several bodies per cell and they were often present in the vicinity of the nucleolus. No nascent transcripts were observed within them. Splicing factors of the SR family, including protein SC35, which participates in bringing the 3' and 5' sites closer in the splicing reaction, were also not observed. The absence of the above-mentioned elements within bodies containing poly(A) RNA disqualifies them as sites of synthesis and preliminary stages of primary transcript maturation. However, they contained abundant elements of the splicing machinery commonly occurring in Cajal bodies, i.e., Sm proteins or small nuclear RNA (snRNA). The molecular composition as well as the characteristic ultrastructure of bodies containing poly(A) RNA proves that these were Cajal bodies. This is the first report of such poly(A) RNA localization.
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Affiliation(s)
- Agnieszka Kołowerzo
- Department of Cell Biology, Institute of General and Molecular Biology, Nicolaus Copernicus University, Gagarina 9, Toruń, 87-100, Poland
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30
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Patel SB, Bellini M. The assembly of a spliceosomal small nuclear ribonucleoprotein particle. Nucleic Acids Res 2008; 36:6482-93. [PMID: 18854356 PMCID: PMC2582628 DOI: 10.1093/nar/gkn658] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The U1, U2, U4, U5 and U6 small nuclear ribonucleoprotein particles (snRNPs) are essential elements of the spliceosome, the enzyme that catalyzes the excision of introns and the ligation of exons to form a mature mRNA. Since their discovery over a quarter century ago, the structure, assembly and function of spliceosomal snRNPs have been extensively studied. Accordingly, the functions of splicing snRNPs and the role of various nuclear organelles, such as Cajal bodies (CBs), in their nuclear maturation phase have already been excellently reviewed elsewhere. The aim of this review is, then, to briefly outline the structure of snRNPs and to synthesize new and exciting developments in the snRNP biogenesis pathways.
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Affiliation(s)
- Snehal Bhikhu Patel
- Biochemistry and College of Medicine and Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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31
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Abstract
How transcription affects the way specific genes are arranged within the nucleus remains to be fully understood. We examine here whether transcription occurs in discrete sites (factories) containing the required machinery and whether these sites specialize in transcribing different genes. We cotransfected plasmids encoding a common origin of replication but different transcription units into cells, where they are assembled into minichromosomes that the cellular machinery replicates and transcribes. In cells containing thousands of minichromosomes, we found (using fluorescence in situ hybridization) active templates concentrated in only a few factories that transcribe particular units depending on the promoter type and the presence of an intron. Close proximity between similar transcription units, whether on two different minichromosomes or on host chromosomes and minichromosomes, is confirmed using chromosome conformation capture. We conclude that factories specialize in producing a particular type of transcript depending on promoter type and whether or not the gene contains an intron.
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Affiliation(s)
- Meng Xu
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, England, UK
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32
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Targeted pre-mRNA modification for gene silencing and regulation. Nat Methods 2007; 5:95-100. [PMID: 18066073 DOI: 10.1038/nmeth1142] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2007] [Accepted: 11/14/2007] [Indexed: 11/08/2022]
Abstract
Most eukaryotic box C/D small nucleolar (sno) or Cajal body-specific RNAs guide base pairing with target RNAs and direct site-specific 2'-O-methylation. We designed an artificial C/D RNA to target the branch point adenosine of ACT1 pre-mRNA to block its splicing. Saccharomyces cerevisiae expressing this guide RNA gene controlled by a GAL1 promoter grew normally on dextrose but not on galactose medium. The pre-mRNA was specifically 2'-O-methylated, prohibiting maturation of ACT1 mRNA. Targeting other adenosines in this region while maintaining almost identical complementarity did not affect ACT1 mRNA level or cell growth, suggesting that targeting the branch-point adenosine was truly 2'-O-methylation-specific rather than an antisense effect; moreover, only the 3'-most branch site adenosine served as the branch point. We targeted other essential intron-containing genes, and observed a similar phenotype. We demonstrated that a Box C/D RNA can guide modification at the pre-mRNA branch point, thus silencing its expression and inducing cell death.
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33
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Wiesmeijer K, Krouwels IM, Tanke HJ, Dirks RW. Chromatin movement visualized with photoactivable GFP-labeled histone H4. Differentiation 2007; 76:83-90. [PMID: 18021258 DOI: 10.1111/j.1432-0436.2007.00234.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The cell nucleus is highly organized with chromosomes occupying discrete, partially overlapping territories, and proteins that localize to specific nuclear compartments. This spatial organization of the nucleus is considered to be dynamic in response to environmental and cellular conditions to support changes in transcriptional programs. Chromatin, however, is relatively immobile when analyzed in living cells and shows a constrained Brownian type of movement. A possible explanation for this relative immobility is that chromatin interacts with a nuclear matrix structure and/or with nuclear compartments. Here, we explore the use of photoactivatable GFP fused to histone H4 as a potential tool to analyze the mobility of chromatin at various nuclear compartments. Selective photoactivation of photoactivatable-GFP at defined nuclear regions was achieved by two-photon excitation with 820 nm light. Nuclear speckles, which are considered storage sites of splicing factors, were visualized by coexpression of a fluorescent protein fused to splicing factor SF2/ASF. The results reveal a constrained chromatin motion, which is not affected by transcriptional inhibition, and suggests an intimate interaction of chromatin with speckles.
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Affiliation(s)
- Karien Wiesmeijer
- Department of Molecular Cell Biology, Leiden University Medical Center, Postal zone S1-P, P.O. Box 9600, 2300 RC Leiden, The Netherlands
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Pombo A. Advances in imaging the interphase nucleus using thin cryosections. Histochem Cell Biol 2007; 128:97-104. [PMID: 17636315 DOI: 10.1007/s00418-007-0310-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/21/2007] [Indexed: 01/01/2023]
Abstract
The mammalian genome is partitioned amongst various chromosomes and encodes for approximately 30,000 protein-coding genes. Gene expression occurs after exit from mitosis, when chromosomes partially decondense within the cell nucleus to allow the enzymatic activities that work on chromatin to access each gene in a regulated fashion. Differential patterns of gene expression evolve during cell differentiation to give rise to the over 200 cell types in higher eukaryotes. The architectural organisation of the genome inside the interphase cell nucleus, and associated enzymatic activities, reveals dynamic and functional compartmentalization of the genome. In this review, I highlight the advantages of Tokuyasu cryosectioning on the investigation of nuclear structure and function.
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Affiliation(s)
- Ana Pombo
- Nuclear Organisation Group, MRC Clinical Sciences Centre, Imperial College School of Medicine, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK.
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35
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Matera AG, Terns RM, Terns MP. Non-coding RNAs: lessons from the small nuclear and small nucleolar RNAs. Nat Rev Mol Cell Biol 2007; 8:209-20. [PMID: 17318225 DOI: 10.1038/nrm2124] [Citation(s) in RCA: 552] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Recent advances have fuelled rapid growth in our appreciation of the tremendous number, diversity and biological importance of non-coding (nc)RNAs. Because ncRNAs typically function as ribonucleoprotein (RNP) complexes and not as naked RNAs, understanding their biogenesis is crucial to comprehending their regulation and function. The small nuclear and small nucleolar RNPs are two well studied classes of ncRNPs with elaborate assembly and trafficking pathways that provide paradigms for understanding the biogenesis of other ncRNPs.
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MESH Headings
- Animals
- Cell Nucleus/metabolism
- Humans
- Nucleic Acid Conformation
- RNA, Small Nuclear/chemistry
- RNA, Small Nuclear/genetics
- RNA, Small Nuclear/metabolism
- RNA, Small Nucleolar/chemistry
- RNA, Small Nucleolar/genetics
- RNA, Small Nucleolar/metabolism
- RNA, Untranslated/chemistry
- RNA, Untranslated/genetics
- RNA, Untranslated/metabolism
- Ribonucleoproteins, Small Nuclear/metabolism
- Ribonucleoproteins, Small Nucleolar/metabolism
- Transcription, Genetic
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Affiliation(s)
- A Gregory Matera
- Department of Genetics, Case Western Reserve University, Cleveland, Ohio 44106-4955, USA.
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36
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Wagner E, Clement SL, Lykke-Andersen J. An unconventional human Ccr4-Caf1 deadenylase complex in nuclear cajal bodies. Mol Cell Biol 2006; 27:1686-95. [PMID: 17178830 PMCID: PMC1820451 DOI: 10.1128/mcb.01483-06] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
mRNA deadenylation is a key process in the regulation of translation and mRNA turnover. In Saccharomyces cerevisiae, deadenylation is primarily carried out by the Ccr4p and Caf1p/Pop2p subunits of the Ccr4-Not complex, which is conserved in eukaryotes including humans. Here we have identified an unconventional human Ccr4-Caf1 complex containing hCcr4d and hCaf1z, distant human homologs of yeast Ccr4p and Caf1p/Pop2p, respectively. The hCcr4d-hCaf1z complex differs from conventional Ccr4-Not deadenylase complexes, because (i) hCaf1z and hCcr4d concentrate in nuclear Cajal bodies and shuttle between the nucleus and cytoplasm and (ii) the hCaf1z subunit, in addition to rapid deadenylation, subjects substrate RNAs to slow exonucleolytic degradation from the 3' end in vitro. Exogenously expressed hCaf1z shows both of those activities on reporter mRNAs in human HeLa cells and stimulates general mRNA decay when restricted to the cytoplasm by deletion of its nuclear localization signal. These observations suggest that the hCcr4d-hCaf1z complex may function either in the nucleus or in the cytoplasm after its nuclear export, to degrade polyadenylated RNAs, such as mRNAs, pre-mRNAs, or those RNAs that are polyadenylated prior to their degradation in the nucleus.
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Affiliation(s)
- Eileen Wagner
- MCD Biology, University of Colorado, Boulder, CO 80309, USA
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37
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McManus KJ, Stephens DA, Adams NM, Islam SA, Freemont PS, Hendzel MJ. The transcriptional regulator CBP has defined spatial associations within interphase nuclei. PLoS Comput Biol 2006; 2:e139. [PMID: 17054391 PMCID: PMC1617132 DOI: 10.1371/journal.pcbi.0020139] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2006] [Accepted: 09/08/2006] [Indexed: 01/19/2023] Open
Abstract
It is becoming increasingly clear that nuclear macromolecules and macromolecular complexes are compartmentalized through binding interactions into an apparent three-dimensionally ordered structure. This ordering, however, does not appear to be deterministic to the extent that chromatin and nonchromatin structures maintain a strict 3-D arrangement. Rather, spatial ordering within the cell nucleus appears to conform to stochastic rather than deterministic spatial relationships. The stochastic nature of organization becomes particularly problematic when any attempt is made to describe the spatial relationship between proteins involved in the regulation of the genome. The CREB-binding protein (CBP) is one such transcriptional regulator that, when visualised by confocal microscopy, reveals a highly punctate staining pattern comprising several hundred individual foci distributed within the nuclear volume. Markers for euchromatic sequences have similar patterns. Surprisingly, in most cases, the predicted one-to-one relationship between transcription factor and chromatin sequence is not observed. Consequently, to understand whether spatial relationships that are not coincident are nonrandom and potentially biologically important, it is necessary to develop statistical approaches. In this study, we report on the development of such an approach and apply it to understanding the role of CBP in mediating chromatin modification and transcriptional regulation. We have used nearest-neighbor distance measurements and probability analyses to study the spatial relationship between CBP and other nuclear subcompartments enriched in transcription factors, chromatin, and splicing factors. Our results demonstrate that CBP has an order of spatial association with other nuclear subcompartments. We observe closer associations between CBP and RNA polymerase II-enriched foci and SC35 speckles than nascent RNA or specific acetylated histones. Furthermore, we find that CBP has a significantly higher probability of being close to its known in vivo substrate histone H4 lysine 5 compared with the closely related H4 lysine 12. This study demonstrates that complex relationships not described by colocalization exist in the interphase nucleus and can be characterized and quantified. The subnuclear distribution of CBP is difficult to reconcile with a model where chromatin organization is the sole determinant of the nuclear organization of proteins that regulate transcription but is consistent with a close link between spatial associations and nuclear functions.
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Affiliation(s)
- Kirk J McManus
- Department of Oncology, Cross Cancer Institute, Edmonton, Alberta, Canada
| | - David A Stephens
- Department of Mathematics, Imperial College London, London, United Kingdom
| | - Niall M Adams
- Department of Mathematics, Imperial College London, London, United Kingdom
| | - Suhail A Islam
- Division of Molecular Biosciences, Imperial College London, London, United Kingdom
| | - Paul S Freemont
- Division of Molecular Biosciences, Imperial College London, London, United Kingdom
| | - Michael J Hendzel
- Department of Oncology, Cross Cancer Institute, Edmonton, Alberta, Canada
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38
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Shav-Tal Y, Darzacq X, Singer RH. Gene expression within a dynamic nuclear landscape. EMBO J 2006; 25:3469-79. [PMID: 16900099 PMCID: PMC1538565 DOI: 10.1038/sj.emboj.7601226] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2006] [Accepted: 06/07/2006] [Indexed: 01/01/2023] Open
Abstract
Molecular imaging in living cells or organisms now allows us to observe macromolecular assemblies with a time resolution sufficient to address cause-and-effect relationships on specific molecules. These emerging technologies have gained much interest from the scientific community since they have been able to reveal novel concepts in cell biology, thereby changing our vision of the cell. One main paradigm is that cells stochastically vary, thus implying that population analysis may be misleading. In fact, cells should be analyzed within time-resolved single-cell experiments rather than being compared to other cells within a population. Technological imaging developments as well as the stochastic events present in gene expression have been reviewed. Here, we discuss how the structural organization of the nucleus is revealed using noninvasive single-cell approaches, which ultimately lead to the resolution required for the analysis of highly controlled molecular processes taking place within live cells. We also describe the efforts being made towards physiological approaches within the context of living organisms.
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Affiliation(s)
- Yaron Shav-Tal
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel.
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39
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Darzacq X, Kittur N, Roy S, Shav-Tal Y, Singer RH, Meier UT. Stepwise RNP assembly at the site of H/ACA RNA transcription in human cells. ACTA ACUST UNITED AC 2006; 173:207-18. [PMID: 16618814 PMCID: PMC2063812 DOI: 10.1083/jcb.200601105] [Citation(s) in RCA: 137] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mammalian H/ACA RNPs are essential for ribosome biogenesis, premessenger RNA splicing, and telomere maintenance. These RNPs consist of four core proteins and one RNA, but it is not known how they assemble. By interrogating the site of H/ACA RNA transcription, we dissected their biogenesis in single cells and delineated the role of the non-core protein NAF1 in the process. NAF1 and all of the core proteins except GAR1 are recruited to the site of transcription. NAF1 binds one of the core proteins, NAP57, and shuttles between nucleus and cytoplasm. Both proteins are essential for stable H/ACA RNA accumulation. NAF1 and GAR1 bind NAP57 competitively, suggesting a sequential interaction. Our analyses indicate that NAF1 binds NAP57 and escorts it to the nascent H/ACA RNA and that GAR1 then replaces NAF1 to yield mature H/ACA RNPs in Cajal bodies and nucleoli.
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Affiliation(s)
- Xavier Darzacq
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine Bronx, NY 10461, USA
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40
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Stanek D, Neugebauer KM. The Cajal body: a meeting place for spliceosomal snRNPs in the nuclear maze. Chromosoma 2006; 115:343-54. [PMID: 16575476 DOI: 10.1007/s00412-006-0056-6] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2005] [Revised: 01/27/2006] [Accepted: 01/29/2006] [Indexed: 10/24/2022]
Abstract
Spliceosomal small nuclear ribonucleoprotein particles (snRNPs) are essential pre-mRNA splicing factors that consist of small nuclear RNAs (snRNAs) complexed with specific sets of proteins. A considerable body of evidence has established that snRNP assembly is accomplished after snRNA synthesis in the nucleus through a series of steps involving cytoplasmic and nuclear phases. Recent work indicates that snRNPs transiently localize to the Cajal body (CB), a nonmembrane-bound inclusion present in the nuclei of most cells, for the final steps in snRNP maturation, including snRNA base modification, U4/U6 snRNA annealing, and snRNA-protein assembly. Here, we review these findings that suggest a crucial role for CBs in the spliceosome cycle in which production of new snRNPs--and perhaps regenerated snRNPs after splicing--is promoted by the concentration of substrates in this previously mysterious subnuclear organelle. These insights allow us to speculate on the role of nuclear bodies in regulating the dynamics of RNP assembly to maintain a functional pool of factors available for key steps in gene expression.
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Affiliation(s)
- David Stanek
- Department of Cellular Biology and Pathology, First Medical Faculty, Institute of Physiology, Charles University, Academy of Sciences of the Czech Republic, Albertov 4, Prague 2, 128 00, Czech Republic.
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41
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Abstract
This review surveys what is known about the structure and function of the subnuclear domains called Cajal bodies (CBs). The major focus is on CBs in mammalian cells but we provide an overview of homologous CB structures in other organisms. We discuss the protein and RNA components of CBs, including factors recently found to associate in a cell cycle-dependent fashion or under specific metabolic or stress conditions. We also consider the dynamic properties of both CBs and their molecular components, based largely on recent data obtained thanks to the advent of improved in vivo detection and imaging methods. We discuss how these data contribute to an understanding of CB functions and highlight major questions that remain to be answered. Finally, we consider the interesting links that have emerged between CBs and alterations in nuclear structure apparent in a range of human pathologies, including cancer and inherited neurodegenerative diseases. We speculate on the relationship between CB function and molecular disease.
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Affiliation(s)
- Mario Cioce
- IRBM (Merck Research Laboratories Rome), Rome, Italy.
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42
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Sun J, Xu H, Subramony SH, Hebert MD. Interactions between coilin and PIASy partially link Cajal bodies to PML bodies. J Cell Sci 2005; 118:4995-5003. [PMID: 16219678 DOI: 10.1242/jcs.02613] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The eukaryotic nucleus contains a variety of dynamic structures, yet studies into the functional relationship of one type of subnuclear domain to another have been limited. For example, PML bodies and Cajal bodies associate, but the functional consequence of this association and the mediating factors are unknown. Here we report that an associated PML body/Cajal body can co-localize to an snRNA gene locus, with the Cajal body invariably situated between the PML body and the snRNA locus. Binding studies demonstrate that coilin (a Cajal body protein) directly interacts with PIASy (a PML body protein). Cell biological experiments using coilin and PIASy knockout cell lines demonstrate that interactions between coilin and PIASy account in part for the observed association of Cajal bodies with PML bodies. When the PIASy interaction region on coilin is deleted, the frequency of the association between Cajal bodies and PML bodies is reduced. These studies provide another example of coilin's role in the functional organization of the nucleus.
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Affiliation(s)
- Jun Sun
- Department of Neurology, The University of Mississippi Medical Center, Jackson, MS 39216-4505, USA
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43
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Xie SQ, Pombo A. Distribution of different phosphorylated forms of RNA polymerase II in relation to Cajal and PML bodies in human cells: an ultrastructural study. Histochem Cell Biol 2005; 125:21-31. [PMID: 16187066 DOI: 10.1007/s00418-005-0064-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/18/2005] [Indexed: 11/29/2022]
Abstract
The mammalian nucleus is a highly organised organelle that contains many subcompartments with roles in DNA replication and repair, gene expression and RNA processing. Cajal and promyelocytic leukaemia (PML) bodies are discrete nuclear structures with specific molecular signatures. RNA polymerase II and many transcription factors have been identified within these compartments by immunofluorescence microscopy, suggesting a role in polymerase II assembly or transcriptional activity. Here, we have examined the presence of different phosphorylated forms of polymerase II and newly made RNA in Cajal and PML bodies using high-resolution imaging of ultrathin cryosections (approximately 120 nm thick) with fluorescence and electron microscopes. We show that Cajal bodies contain polymerase II phosphorylated on Ser5, and not the Ser2-phosphorylated (active) form or newly made RNA. The presence of polymerase II in the absence of transcriptional activity suggests that Cajal bodies have roles in polymerase assembly or transport, but not in gene transcription. PML bodies contain no detectable polymerase II or nascent RNA in HeLa cells, at the resolution achieved by electron microscopy, but are often surrounded by these markers at distances>25 nm. These results support the view that although PML bodies are present in transcriptionally active areas of the nucleus, they are not generally sites of polymerase II assembly, transport or activity.
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Affiliation(s)
- Sheila Q Xie
- MRC Clinical Sciences Centre, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK
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44
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Hall MP, Huang S, Black DL. Differentiation-induced colocalization of the KH-type splicing regulatory protein with polypyrimidine tract binding protein and the c-src pre-mRNA. Mol Biol Cell 2003; 15:774-86. [PMID: 14657238 PMCID: PMC329392 DOI: 10.1091/mbc.e03-09-0692] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
We have examined the subcellular localization of the KH-type splicing regulatory protein (KSRP). KSRP is a multidomain RNA-binding protein implicated in a variety of cellular processes, including splicing in the nucleus and mRNA localization in the cytoplasm. We find that KSRP is primarily nuclear with a localization pattern that most closely resembles that of polypyrimidine tract binding protein (PTB). Colocalization experiments of KSRP with PTB in a mouse neuroblastoma cell line determined that both proteins are present in the perinucleolar compartment (PNC), as well as in other nuclear enrichments. In contrast, HeLa cells do not show prominent KSRP staining in the PNC, even though PTB labeling identified the PNC in these cells. Because both PTB and KSRP interact with the c-src transcript to affect N1 exon splicing, we examined the localization of the c-src pre-mRNA by fluorescence in situ hybridization. The src transcript is present in specific foci within the nucleus that are presumably sites of src transcription but are not generally perinucleolar. In normally cultured neuroblastoma cells, these src RNA foci contain PTB, but little KSRP. However, upon induced neuronal differentiation of these cells, KSRP occurs in the same foci with src RNA. PTB localization remains unaffected. This differentiation-induced localization of KSRP with src RNA correlates with an increase in src exon N1 inclusion. These results indicate that PTB and KSRP do indeed interact with the c-src transcript in vivo, and that these associations change with the differentiated state of the cell.
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Affiliation(s)
- Megan P. Hall
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, California 90095
| | - Sui Huang
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611
| | - Douglas L. Black
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, California 90095
- Howard Hughes Medical Institute, University of California, Los Angeles, Los Angeles, California 90095
- Corresponding author. E-mail address:
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Darzacq X, Jády BE, Verheggen C, Kiss AM, Bertrand E, Kiss T. Cajal body-specific small nuclear RNAs: a novel class of 2'-O-methylation and pseudouridylation guide RNAs. EMBO J 2002; 21:2746-56. [PMID: 12032087 PMCID: PMC126017 DOI: 10.1093/emboj/21.11.2746] [Citation(s) in RCA: 368] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Cajal (coiled) bodies are conserved subnuclear organelles that are present in the nucleoplasm of both animal and plant cells. Although Cajal bodies were first described nearly 100 years ago, their function has remained largely speculative. Here, we describe a novel class of human small nuclear RNAs that localize specifically to Cajal bodies. The small Cajal body-specific RNAs (scaRNAs) are predicted or have already been demonstrated to function as guide RNAs in site-specific synthesis of 2'-O-ribose-methylated nucleotides and pseudouridines in the RNA polymerase II-transcribed U1, U2, U4 and U5 spliceosomal small nuclear RNAs (snRNAs). Our results provide strong support for the idea that the Cajal body, this mysterious nuclear organelle, provides the cellular locale for post-transcriptional modification of spliceosomal snRNAs.
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Affiliation(s)
| | - Beáta E. Jády
- Laboratoire de Biologie Moléculaire Eucaryote du CNRS, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex,
Institut de Génétique Moléculaire, Montpellier, France and Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary Corresponding author e-mail:
| | - Céline Verheggen
- Laboratoire de Biologie Moléculaire Eucaryote du CNRS, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex,
Institut de Génétique Moléculaire, Montpellier, France and Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary Corresponding author e-mail:
| | - Arnold M. Kiss
- Laboratoire de Biologie Moléculaire Eucaryote du CNRS, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex,
Institut de Génétique Moléculaire, Montpellier, France and Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary Corresponding author e-mail:
| | - Edouard Bertrand
- Laboratoire de Biologie Moléculaire Eucaryote du CNRS, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex,
Institut de Génétique Moléculaire, Montpellier, France and Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary Corresponding author e-mail:
| | - Tamás Kiss
- Laboratoire de Biologie Moléculaire Eucaryote du CNRS, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex,
Institut de Génétique Moléculaire, Montpellier, France and Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary Corresponding author e-mail:
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46
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Verheggen C, Mouaikel J, Thiry M, Blanchard JM, Tollervey D, Bordonné R, Lafontaine DL, Bertrand E. Box C/D small nucleolar RNA trafficking involves small nucleolar RNP proteins, nucleolar factors and a novel nuclear domain. EMBO J 2001; 20:5480-90. [PMID: 11574480 PMCID: PMC125276 DOI: 10.1093/emboj/20.19.5480] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Nucleolar localization of box C/D small nucleolar (sno) RNAs requires the box C/D motif and, in vertebrates, involves transit through Cajal bodies (CB). We report that in yeast, overexpression of a box C/D reporter leads to a block in the localization pathway with snoRNA accumulation in a specific sub-nucleolar structure, the nucleolar body (NB). The human survival of motor neuron protein (SMN), a marker of gems/CB, specifically localizes to the NB when expressed in yeast, supporting similarities between these structures. Box C/D snoRNA accumulation in the NB was decreased by mutation of Srp40 and increased by mutation of Nsr1p, two related nucleolar proteins that are homologous to human Nopp140 and nucleolin, respectively. Box C/D snoRNAs also failed to accumulate in the NB, and became delocalized to the nucleoplasm, upon depletion of any of the core snoRNP proteins, Nop1p/fibrillarin, Snu13p, Nop56p and Nop5p/Nop58p. We conclude that snoRNP assembly occurs either in the nucleoplasm, or during transit of snoRNAs through the NB, followed by routing of the complete snoRNP to functional sites of ribosome synthesis.
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Affiliation(s)
| | | | - Marc Thiry
- IGMM, IFR 24, UMR 5535 du CNRS, 34293 Montpellier Cedex 5, France,
Laboratoire de biologie cellulaire et tissulaire, Université de Liège, Liège, Belgium and ICMB, The University of Edinburgh, Edinburgh EH9 3JR, UK Present address: IRMW, FNRS-Université Libre de Bruxelles, B-1070 Brussels, Belgium Corresponding author e-mail:
D.L.J.Lafontaine and E.Bertrand contributed equally to this work
| | | | - David Tollervey
- IGMM, IFR 24, UMR 5535 du CNRS, 34293 Montpellier Cedex 5, France,
Laboratoire de biologie cellulaire et tissulaire, Université de Liège, Liège, Belgium and ICMB, The University of Edinburgh, Edinburgh EH9 3JR, UK Present address: IRMW, FNRS-Université Libre de Bruxelles, B-1070 Brussels, Belgium Corresponding author e-mail:
D.L.J.Lafontaine and E.Bertrand contributed equally to this work
| | | | - Denis L.J. Lafontaine
- IGMM, IFR 24, UMR 5535 du CNRS, 34293 Montpellier Cedex 5, France,
Laboratoire de biologie cellulaire et tissulaire, Université de Liège, Liège, Belgium and ICMB, The University of Edinburgh, Edinburgh EH9 3JR, UK Present address: IRMW, FNRS-Université Libre de Bruxelles, B-1070 Brussels, Belgium Corresponding author e-mail:
D.L.J.Lafontaine and E.Bertrand contributed equally to this work
| | - Edouard Bertrand
- IGMM, IFR 24, UMR 5535 du CNRS, 34293 Montpellier Cedex 5, France,
Laboratoire de biologie cellulaire et tissulaire, Université de Liège, Liège, Belgium and ICMB, The University of Edinburgh, Edinburgh EH9 3JR, UK Present address: IRMW, FNRS-Université Libre de Bruxelles, B-1070 Brussels, Belgium Corresponding author e-mail:
D.L.J.Lafontaine and E.Bertrand contributed equally to this work
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47
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Abstract
Cajal bodies (CBs) are nuclear structures involved in RNA metabolism that accumulate high concentrations of small nuclear ribonucleoproteins (snRNPs). Notably, CBs preferentially associate with specific genomic loci in interphase human cells, including several snRNA and histone gene clusters. To uncover functional elements involved in the interaction of genes and CBs, we analyzed the expression and subcellular localization of stably transfected artificial arrays of U2 snRNA genes. Although promoter substitution arrays colocalized with CBs, constructs containing intragenic deletions did not. Additional experiments identified factors within CBs that are important for association with the native U2 genes. Inhibition of nuclear export or targeted degradation of U2 snRNPs caused a marked decrease in the levels of U2 snRNA in CBs and strongly disrupted the interaction with U2 genes. Together, the results illustrate a specific requirement for both the snRNA transcripts as well as the presence of snRNPs (or snRNP proteins) within CBs. Our data thus provide significant insight into the mechanism of CB interaction with snRNA loci, strengthening the putative role for this nuclear suborganelle in snRNP biogenesis.
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Affiliation(s)
- M R Frey
- Department of Genetics and Program in Cell Biology, Case Western Reserve University, Cleveland, OH 44106, USA
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Affiliation(s)
- T Kiss
- Laboratoire de Biologie Moléculaire Eucaryote du CNRS, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse, France.
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49
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Shopland LS, Byron M, Stein JL, Lian JB, Stein GS, Lawrence JB. Replication-dependent histone gene expression is related to Cajal body (CB) association but does not require sustained CB contact. Mol Biol Cell 2001; 12:565-76. [PMID: 11251071 PMCID: PMC30964 DOI: 10.1091/mbc.12.3.565] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Interactions between Cajal bodies (CBs) and replication-dependent histone loci occur more frequently than for other mRNA-encoding genes, but such interactions are not seen with all alleles at a given time. Because CBs contain factors required for transcriptional regulation and 3' end processing of nonpolyadenylated replication-dependent histone transcripts, we investigated whether interaction with CBs is related to metabolism of these transcripts, known to vary during the cell cycle. Our experiments revealed that a locus containing a cell cycle-independent, replacement histone gene that produces polyadenylated transcripts does not preferentially associate with CBs. Furthermore, modest but significant changes in association levels of CBs with replication-dependent histone loci mimic their cell cycle modulations in transcription and 3' end processing rates. By simultaneously visualizing replication-dependent histone genes and their nuclear transcripts for the first time, we surprisingly find that the vast majority of loci producing detectable RNA foci do not contact CBs. These studies suggest some link between CB association and unusual features of replication-dependent histone gene expression. However, sustained CB contact is not a requirement for their expression, consistent with our observations of U7 snRNP distributions. The modest correlation to gene expression instead may reflect transient gene signaling or the nucleation of small CBs at gene loci.
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Affiliation(s)
- L S Shopland
- Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA
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50
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Abstract
DNA is highly organized spatially, both within domains of chromatin along each chromosome and within the nucleus as a whole. Recent studies suggest that chromatin localization can affect transcriptional and replicational activity. The similarity between the movements of chromatin nuclear bodies suggests a common mechanism that regulates nuclear dynamics.
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Affiliation(s)
- J R Swedlow
- Division of Gene Regulation and Expression, Wellcome Trust Biocentre, University of Dundee, Dow Street, Dundee, DD1 5EH, UK.
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