1
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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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Vos TJ, Kothe U. snR30/U17 Small Nucleolar Ribonucleoprotein: A Critical Player during Ribosome Biogenesis. Cells 2020; 9:cells9102195. [PMID: 33003357 PMCID: PMC7601244 DOI: 10.3390/cells9102195] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 09/26/2020] [Accepted: 09/28/2020] [Indexed: 11/29/2022] Open
Abstract
The small nucleolar RNA snR30 (U17 in humans) plays a unique role during ribosome synthesis. Unlike most members of the H/ACA class of guide RNAs, the small nucleolar ribonucleoprotein (snoRNP) complex assembled on snR30 does not direct pseudouridylation of ribosomal RNA (rRNA), but instead snR30 is critical for 18S rRNA processing during formation of the small subunit (SSU) of the ribosome. Specifically, snR30 is essential for three pre-rRNA cleavages at the A0/01, A1/1, and A2/2a sites in yeast and humans, respectively. Accordingly, snR30 is the only essential H/ACA guide RNA in yeast. Here, we summarize our current knowledge about the interactions and functions of snR30, discuss what remains to be elucidated, and present two non-exclusive hypotheses on the possible molecular function of snR30 during ribosome biogenesis. First, snR30 might be responsible for recruiting other proteins including endonucleases to the SSU processome. Second, snR30 may contribute to the refolding of pre-rRNA into a required conformation that serves as a checkpoint during ribosome biogenesis facilitating pre-rRNA cleavage. In both scenarios, the snR30 snoRNP may have scaffolding and RNA chaperoning activity. In conclusion, the snR30 snoRNP is a crucial player with an unknown molecular mechanism during ribosome synthesis, posing many interesting future research questions.
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Affiliation(s)
| | - Ute Kothe
- Correspondence: ; Tel.: +1-403-332-5274
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3
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Corbet GA, Parker R. RNP Granule Formation: Lessons from P-Bodies and Stress Granules. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2020; 84:203-215. [PMID: 32482896 DOI: 10.1101/sqb.2019.84.040329] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
It is now clear that cells form a wide collection of large RNA-protein assemblies, referred to as RNP granules. RNP granules exist in bacterial cells and can be found in both the cytosol and nucleus of eukaryotic cells. Recent approaches have begun to define the RNA and protein composition of a number of RNP granules. Herein, we review the composition and assembly of RNP granules, as well as how RNPs are targeted to RNP granules using stress granules and P-bodies as model systems. Taken together, these reveal that RNP granules form through the summative effects of a combination of protein-protein, protein-RNA, and RNA-RNA interactions. Similarly, the partitioning of individual RNPs into stress granules is determined by the combinatorial effects of multiple elements. Thus, RNP granules are assemblies generally dominated by combinatorial effects, thereby providing rich opportunities for biological regulation.
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Affiliation(s)
- Giulia Ada Corbet
- Department of Biochemistry, University of Colorado at Boulder, Boulder, Colorado 80309, USA
| | - Roy Parker
- Department of Biochemistry, University of Colorado at Boulder, Boulder, Colorado 80309, USA
- Howard Hughes Medical Institute, University of Colorado at Boulder, Boulder, Colorado 80309, USA
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4
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Guillen-Chable F, Rodríguez Corona U, Pereira-Santana A, Bayona A, Rodríguez-Zapata LC, Aquino C, Šebestová L, Vitale N, Hozak P, Castano E. Fibrillarin Ribonuclease Activity is Dependent on the GAR Domain and Modulated by Phospholipids. Cells 2020; 9:cells9051143. [PMID: 32384686 PMCID: PMC7290794 DOI: 10.3390/cells9051143] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 04/24/2020] [Accepted: 04/29/2020] [Indexed: 12/16/2022] Open
Abstract
Fibrillarin is a highly conserved nucleolar methyltransferase responsible for ribosomal RNA methylation across evolution from Archaea to humans. It has been reported that fibrillarin is involved in the methylation of histone H2A in nucleoli and other processes, including viral progression, cellular stress, nuclear shape, and cell cycle progression. We show that fibrillarin has an additional activity as a ribonuclease. The activity is affected by phosphoinositides and phosphatidic acid and insensitive to ribonuclease inhibitors. Furthermore, the presence of phosphatidic acid releases the fibrillarin-U3 snoRNA complex. We show that the ribonuclease activity localizes to the GAR (glycine/arginine-rich) domain conserved in a small group of RNA interacting proteins. The introduction of the GAR domain occurred in evolution in the transition from archaea to eukaryotic cells. The interaction of this domain with phospholipids may allow a phase separation of this protein in nucleoli.
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Affiliation(s)
- Francisco Guillen-Chable
- Biochemistry and Molecular Plant Biology Department, Centro de Investigación Científica de Yucatán, A.C. Calle 43 No. 130, Colonia Chuburná de Hidalgo, Mérida C.P. 97200, Yucatán, Mexico; (F.G.-C.); (U.R.C.); (A.B.); (C.A.)
| | - Ulises Rodríguez Corona
- Biochemistry and Molecular Plant Biology Department, Centro de Investigación Científica de Yucatán, A.C. Calle 43 No. 130, Colonia Chuburná de Hidalgo, Mérida C.P. 97200, Yucatán, Mexico; (F.G.-C.); (U.R.C.); (A.B.); (C.A.)
| | - Alejandro Pereira-Santana
- Industrial Biotechnology Department, Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco, A.C., Camino Arenero 1227, el Bajio, Zapopan C.P. 45019, Jalisco, Mexico;
- Dirección de Cátedras, Consejo Nacional de Ciencia y Tecnología, Av. Insurgentes Sur 1582, Alcaldia Benito Juarez C.P. 03940, Ciudad de Mexico, Mexico
| | - Andrea Bayona
- Biochemistry and Molecular Plant Biology Department, Centro de Investigación Científica de Yucatán, A.C. Calle 43 No. 130, Colonia Chuburná de Hidalgo, Mérida C.P. 97200, Yucatán, Mexico; (F.G.-C.); (U.R.C.); (A.B.); (C.A.)
| | - Luis Carlos Rodríguez-Zapata
- Biotechnology Department, Centro de Investigación Científica de Yucatán, A.C. Calle 43 No. 130, Colonia Chuburná de Hidalgo, Mérida C.P. 97200, Yucatan, Mexico;
| | - Cecilia Aquino
- Biochemistry and Molecular Plant Biology Department, Centro de Investigación Científica de Yucatán, A.C. Calle 43 No. 130, Colonia Chuburná de Hidalgo, Mérida C.P. 97200, Yucatán, Mexico; (F.G.-C.); (U.R.C.); (A.B.); (C.A.)
| | - Lenka Šebestová
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the CAS, v.v.i., Videnska 1083, 142 20 Prague, Czech Republic; (L.Š.); (P.H.)
- Faculty of Science, Charles University, Albertov 6, 128 00 Prague, Czech Republic
| | - Nicolas Vitale
- Institute of Celullar and Integrative Neuroscience (INCI), UPR-3212 The French National Centre for Scientific Research & University of Strasbourg, 67000 Strasbourg, France;
| | - Pavel Hozak
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the CAS, v.v.i., Videnska 1083, 142 20 Prague, Czech Republic; (L.Š.); (P.H.)
| | - Enrique Castano
- Biochemistry and Molecular Plant Biology Department, Centro de Investigación Científica de Yucatán, A.C. Calle 43 No. 130, Colonia Chuburná de Hidalgo, Mérida C.P. 97200, Yucatán, Mexico; (F.G.-C.); (U.R.C.); (A.B.); (C.A.)
- Correspondence:
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5
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Bizarro J, Bhardwaj A, Smith S, Meier UT. Nopp140-mediated concentration of telomerase in Cajal bodies regulates telomere length. Mol Biol Cell 2019; 30:3136-3150. [PMID: 31664887 PMCID: PMC6938241 DOI: 10.1091/mbc.e19-08-0429] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Cajal bodies (CBs) are nuclear organelles concentrating two kinds of RNA–protein complexes (RNPs), spliceosomal small nuclear (sn), and small CB-specific (sca)RNPs. Whereas the CB marker protein coilin is responsible for retaining snRNPs, the tether for scaRNPs is not known. Here we show that Nopp140, an intrinsically disordered CB phosphoprotein, is required to recruit and retain all scaRNPs in CBs. Knockdown (KD) of Nopp140 releases all scaRNPs leading to an unprecedented reduction in size of CB granules, hallmarks of CB ultrastructure. The CB-localizing protein WDR79 (aka TCAB1), which is mutated in the inherited bone marrow failure syndrome dyskeratosis congenita, is a specific component of all scaRNPs, including telomerase. Whereas mislocalization of telomerase by mutation of WDR79 leads to critically shortened telomeres, mislocalization of telomerase by Nopp140 KD leads to gradual extension of telomeres. Our studies suggest that the dynamic distribution of telomerase between CBs and nucleoplasm uniquely impacts telomere length maintenance and identify Nopp140 as a novel player in telomere biology.
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Affiliation(s)
- Jonathan Bizarro
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Amit Bhardwaj
- Department of Pathology, Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, NY 10016
| | - Susan Smith
- Department of Pathology, Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, NY 10016
| | - U Thomas Meier
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY 10461
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6
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Terns MP, Terns RM. Small nucleolar RNAs: versatile trans-acting molecules of ancient evolutionary origin. Gene Expr 2018; 10:17-39. [PMID: 11868985 PMCID: PMC5977530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
The small nucleolar RNAs (snoRNAs) are an abundant class of trans-acting RNAs that function in ribosome biogenesis in the eukaryotic nucleolus. Elegant work has revealed that most known snoRNAs guide modification of pre-ribosomal RNA (pre-rRNA) by base pairing near target sites. Other snoRNAs are involved in cleavage of pre-rRNA by mechanisms that have not yet been detailed. Moreover, our appreciation of the cellular roles of the snoRNAs is expanding with new evidence that snoRNAs also target modification of small nuclear RNAs and messenger RNAs. Many snoRNAs are produced by unorthodox modes of biogenesis including salvage from introns of pre-mRNAs. The recent discovery that homologs of snoRNAs as well as associated proteins exist in the domain Archaea indicates that the RNA-guided RNA modification system is of ancient evolutionary origin. In addition, it has become clear that the RNA component of vertebrate telomerase (an enzyme implicated in cancer and cellular senescence) is related to snoRNAs. During its evolution, vertebrate telomerase RNA appears to have co-opted a snoRNA domain that is essential for the function of telomerase RNA in vivo. The unique properties of snoRNAs are now being harnessed for basic research and therapeutic applications.
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MESH Headings
- Animals
- Base Pairing
- Biological Transport
- Cell Nucleolus/metabolism
- Cell Nucleus/metabolism
- Eukaryotic Cells/metabolism
- Evolution, Molecular
- Methylation
- Prokaryotic Cells/metabolism
- Pseudouridine/metabolism
- RNA/metabolism
- RNA Precursors/metabolism
- RNA Processing, Post-Transcriptional/genetics
- RNA, Archaeal/genetics
- RNA, Archaeal/physiology
- RNA, Catalytic/metabolism
- RNA, Messenger/metabolism
- RNA, Ribosomal/biosynthesis
- RNA, Small Nucleolar/chemistry
- RNA, Small Nucleolar/classification
- RNA, Small Nucleolar/genetics
- RNA, Small Nucleolar/metabolism
- RNA, Small Nucleolar/physiology
- Ribonucleoproteins, Small Nucleolar/metabolism
- Ribosomes/metabolism
- Species Specificity
- Structure-Activity Relationship
- Telomerase/metabolism
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Affiliation(s)
- Michael P Terns
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens 30602, USA.
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7
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Massenet S, Bertrand E, Verheggen C. Assembly and trafficking of box C/D and H/ACA snoRNPs. RNA Biol 2017; 14:680-692. [PMID: 27715451 PMCID: PMC5519232 DOI: 10.1080/15476286.2016.1243646] [Citation(s) in RCA: 118] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 09/09/2016] [Accepted: 09/27/2016] [Indexed: 12/23/2022] Open
Abstract
Box C/D and box H/ACA snoRNAs are abundant non-coding RNAs that localize in the nucleolus and mostly function as guides for nucleotide modifications. While a large pool of snoRNAs modifies rRNAs, an increasing number of snoRNAs could also potentially target mRNAs. ScaRNAs belong to a family of specific RNAs that localize in Cajal bodies and that are structurally similar to snoRNAs. Most scaRNAs are involved in snRNA modification, while telomerase RNA, which contains H/ACA motifs, functions in telomeric DNA synthesis. In this review, we describe how box C/D and H/ACA snoRNAs are processed and assembled with core proteins to form functional RNP particles. Their biogenesis involve several transport factors that first direct pre-snoRNPs to Cajal bodies, where some processing steps are believed to take place, and then to nucleoli. Assembly of core proteins involves the HSP90/R2TP chaperone-cochaperone system for both box C/D and H/ACA RNAs, but also several factors specific for each family. These assembly factors chaperone unassembled core proteins, regulate the formation and disassembly of pre-snoRNP intermediates, and control the activity of immature particles. The AAA+ ATPase RUVBL1 and RUVBL2 belong to the R2TP co-chaperones and play essential roles in snoRNP biogenesis, as well as in the formation of other macro-molecular complexes. Despite intensive research, their mechanisms of action are still incompletely understood.
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Affiliation(s)
- Séverine Massenet
- Ingénierie Moléculaire et Physiopathologie Articulaire, UMR 7365 CNRS, 9 Avenue de la forêt de Haye, 54505 Vandoeuvre-les-Nancy Cedex, France, Université de Lorraine, Campus Biologie –Santé, CS 50184, 54505 Vandoeuvre-les-Nancy Cedex, France
| | - Edouard Bertrand
- Institut de Génétique Moléculaire de Montpellier, UMR 5535 CNRS, 1919 route de Mende, 34293 Montpellier cedex 5, France, Université de Montpellier, 163 rue Auguste Broussonnet, 34090 Montpellier, France
| | - Céline Verheggen
- Institut de Génétique Moléculaire de Montpellier, UMR 5535 CNRS, 1919 route de Mende, 34293 Montpellier cedex 5, France, Université de Montpellier, 163 rue Auguste Broussonnet, 34090 Montpellier, France
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8
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Heyn P, Salmonowicz H, Rodenfels J, Neugebauer KM. Activation of transcription enforces the formation of distinct nuclear bodies in zebrafish embryos. RNA Biol 2016; 14:752-760. [PMID: 27858508 DOI: 10.1080/15476286.2016.1255397] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Nuclear bodies are cellular compartments that lack lipid bilayers and harbor specific RNAs and proteins. Recent proposals that nuclear bodies form through liquid-liquid phase separation leave the question of how different nuclear bodies maintain their distinct identities unanswered. Here we investigate Cajal bodies (CBs), histone locus bodies (HLBs) and nucleoli - involved in assembly of the splicing machinery, histone mRNA 3' end processing, and rRNA processing, respectively - in the embryos of the zebrafish, Danio rerio. We take advantage of the transcriptional silence of the 1-cell embryo and follow nuclear body appearance as zygotic transcription becomes activated. CBs are present from fertilization onwards, while HLB and nucleolar components formed foci several hours later when histone genes and rDNA became active. HLB formation was blocked by transcription inhibition, suggesting nascent histone transcripts recruit HLB components like U7 snRNP. Surprisingly, we found that U7 base-pairing with nascent histone transcripts was not required for localization to HLBs. Rather, the type of Sm ring assembled on U7 determined its targeting to HLBs or CBs; the spliceosomal Sm ring targeted snRNAs to CBs while the specialized U7 Sm-ring localized to HLBs, demonstrating the contribution of protein constituents to the distinction among nuclear bodies. Thus, nucleolar, HLB, and CB components can mix in early embryogenesis when transcription is naturally or artificially silenced. These data support a model in which transcription of specific gene loci nucleates nuclear body components with high specificity and fidelity to perform distinct regulatory functions.
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Affiliation(s)
- Patricia Heyn
- a Max Planck Institute of Molecular Cell Biology and Genetics , Dresden , Germany
| | - Hanna Salmonowicz
- a Max Planck Institute of Molecular Cell Biology and Genetics , Dresden , Germany
| | - Jonathan Rodenfels
- b Department of Molecular Biophysics & Biochemistry , Yale University , New Haven , CT , USA
| | - Karla M Neugebauer
- b Department of Molecular Biophysics & Biochemistry , Yale University , New Haven , CT , USA
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9
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Abstract
Aside from nucleoli, Cajal bodies (CBs) are the best-characterized organelles of mammalian cell nuclei. Like nucleoli, CBs concentrate ribonucleoproteins (RNPs), in particular, spliceosomal small nuclear RNPs (snRNPs) and small nucleolar RNPs (snoRNPs). In one of the best-defined functions of CBs, most of the snoRNPs are involved in site-specific modification of snRNAs. The two major modifications are pseudouridylation and 2'-O-methylation that are guided by the box H/ACA and C/D snoRNPs, respectively. This review details the modifications, their function, the mechanism of modification, and the machineries involved. We dissect the different classes of noncoding RNAs that meet in CBs, guides and substrates. Open questions and conundrums, often raised and appearing due to experimental limitations, are pointed out and discussed. The emphasis of the review is on mammalian CBs and their function in modification of noncoding RNAs.
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Affiliation(s)
- U Thomas Meier
- a Albert Einstein College of Medicine , Department of Anatomy and Structural Biology , Bronx , NY , USA
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Trinkle-Mulcahy L, Sleeman JE. The Cajal body and the nucleolus: "In a relationship" or "It's complicated"? RNA Biol 2016; 14:739-751. [PMID: 27661468 DOI: 10.1080/15476286.2016.1236169] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
From their initial identification as 'nucleolar accessory bodies' more than a century ago, the relationship between Cajal bodies and nucleoli has been a subject of interest and controversy. In this review, we seek to place recent developments in the understanding of the physical and functional relationships between the 2 structures in the context of historical observations. Biophysical models of nuclear body formation, the molecular nature of CB/nucleolus interactions and the increasing list of joint roles for CBs and nucleoli, predominantly in assembling ribonucleoprotein (RNP) complexes, are discussed.
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Affiliation(s)
- Laura Trinkle-Mulcahy
- a Department of Cellular and Molecular Medicine , Ottawa Institute of Systems Biology, University of Ottawa , Ottawa , ON , Canada
| | - Judith E Sleeman
- b BSRC Complex, School of Biology, University of St Andrews , UK
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Zheng L, Yao J, Gao F, Chen L, Zhang C, Lian L, Xie L, Wu Z, Xie L. The Subcellular Localization and Functional Analysis of Fibrillarin2, a Nucleolar Protein in Nicotiana benthamiana. BIOMED RESEARCH INTERNATIONAL 2016; 2016:2831287. [PMID: 26885505 PMCID: PMC4738988 DOI: 10.1155/2016/2831287] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 12/01/2015] [Indexed: 01/28/2023]
Abstract
Nucleolar proteins play important roles in plant cytology, growth, and development. Fibrillarin2 is a nucleolar protein of Nicotiana benthamiana (N. benthamiana). Its cDNA was amplified by RT-PCR and inserted into expression vector pEarley101 labeled with yellow fluorescent protein (YFP). The fusion protein was localized in the nucleolus and Cajal body of leaf epidermal cells of N. benthamiana. The N. benthamiana fibrillarin2 (NbFib2) protein has three functional domains (i.e., glycine and arginine rich domain, RNA-binding domain, and α-helical domain) and a nuclear localization signal (NLS) in C-terminal. The protein 3D structure analysis predicted that NbFib2 is an α/β protein. In addition, the virus induced gene silencing (VIGS) approach was used to determine the function of NbFib2. Our results showed that symptoms including growth retardation, organ deformation, chlorosis, and necrosis appeared in NbFib2-silenced N. benthamiana.
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Affiliation(s)
- Luping Zheng
- Key Laboratory of Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- Key Laboratory of Plant Virology of Fujian Province, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Jinai Yao
- Institute of Plant Protection, Fujian Provincial Academy of Agricultural Sciences, Fuzhou 350002, China
| | - Fangluan Gao
- Key Laboratory of Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- Key Laboratory of Plant Virology of Fujian Province, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Lin Chen
- Key Laboratory of Plant Virology of Fujian Province, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Chao Zhang
- Key Laboratory of Plant Virology of Fujian Province, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Lingli Lian
- Key Laboratory of Plant Virology of Fujian Province, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Liyan Xie
- Key Laboratory of Plant Virology of Fujian Province, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Zujian Wu
- Key Laboratory of Plant Virology of Fujian Province, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Lianhui Xie
- Key Laboratory of Plant Virology of Fujian Province, Fujian Agriculture and Forestry University, Fuzhou 350002, China
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12
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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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13
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Marnef A, Richard P, Pinzón N, Kiss T. Targeting vertebrate intron-encoded box C/D 2'-O-methylation guide RNAs into the Cajal body. Nucleic Acids Res 2014; 42:6616-29. [PMID: 24753405 PMCID: PMC4041459 DOI: 10.1093/nar/gku287] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 03/26/2014] [Accepted: 03/26/2014] [Indexed: 02/03/2023] Open
Abstract
Post-transcriptional pseudouridylation and 2'-O-methylation of splicesomal small nuclear ribonucleic acids (snRNAs) is mediated by box H/ACA and box C/D small Cajal body (CB)-specific ribonucleoproteins (scaRNPs), respectively. The WD-repeat protein 79 (WDR79) has been proposed to interact with both classes of modification scaRNPs and target them into the CB. The box H/ACA scaRNAs carry the common CAB box motif (consensus, ugAG) that is required for both WDR79 binding and CB-specific accumulation. Thus far, no cis-acting CB-localization element has been reported for vertebrate box C/D scaRNAs. In this study, systematic mutational analysis of the human U90 and another newly identified box C/D scaRNA, mgU2-47, demonstrated that the CB-specific accumulation of vertebrate intron-encoded box C/D scaRNAs relies on GU- or UG-dominated dinucleotide repeat sequences which are predicted to form the terminal stem-loop of the RNA apical hairpin. While the loop nucleotides are unimportant, the adjacent terminal helix that is composed mostly of consecutive G.U and U.G wobble base-pairs is essential for CB-specific localization of box C/D scaRNAs. Co-immunoprecipitation experiments confirmed that the newly identified CB localization element, called the G.U/U.G wobble stem, is crucial for in vivo association of box C/D scaRNPs with WDR79.
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Affiliation(s)
- Aline Marnef
- Laboratoire de Biologie Moléculaire Eucaryote du CNRS, UMR5099, IFR109 CNRS, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex 9, France
| | - Patrica Richard
- Laboratoire de Biologie Moléculaire Eucaryote du CNRS, UMR5099, IFR109 CNRS, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex 9, France
| | - Natalia Pinzón
- Laboratoire de Biologie Moléculaire Eucaryote du CNRS, UMR5099, IFR109 CNRS, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex 9, France
| | - Tamás Kiss
- Laboratoire de Biologie Moléculaire Eucaryote du CNRS, UMR5099, IFR109 CNRS, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex 9, France Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
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14
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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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15
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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: 142] [Impact Index Per Article: 11.8] [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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16
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Verheggen C, Bertrand E. CRM1 plays a nuclear role in transporting snoRNPs to nucleoli in higher eukaryotes. Nucleus 2012; 3:132-7. [PMID: 22555597 PMCID: PMC3383567 DOI: 10.4161/nucl.19266] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Here, we review the sn- and sno-RNA transport pathways in S. cerevisiae and humans, aiming at understanding how they evolved and how common factors can have distinct functions depending on the RNA they bind. We give a particular emphasis on Tgs1, the cap hypermethylase that is conserved from yeast to humans and appears to play a central role in both sn- and sno-RNA biogenesis. In yeast, Tgs1 hypermethylates sn- and sno-RNAs in the nucleolus. In humans, Tgs1 occurs in two forms: a long isoform (Tgs1 LF), which locates in the cytoplasm and Cajal bodies, which is predominantly associated with snRNAs and a short isoform (Tgs1 SF), which is nuclear and mainly associates with snoRNAs. We show that Tgs1 LF is exported by CRM1 and that interaction with CRM1 competes for binding with the C-terminal domain of the core protein Nop58, which contains the Nucleolar localization signal of Box C/D snoRNPs (NoLS). Our data suggest a model where CRM1 removes Tgs1 LF from snoRNPs, thereby promoting nucleolar targeting via activation of their NoLS. In this review, we argue that CRM1, while first described as an export receptor, can also control the composition of nucleoplasmic complexes. Thus, it could coordinate the fate of these complexes with the general nucleo-cytoplasmic trafficking.
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Affiliation(s)
- Celine Verheggen
- Institut de Génétique Moléculaire de Montpellier; Université Montpellier I and II; Montpellier, France
| | - Edouard Bertrand
- Institut de Génétique Moléculaire de Montpellier; Université Montpellier I and II; Montpellier, France
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17
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Pradet-Balade B, Girard C, Boulon S, Paul C, Azzag K, Bordonné R, Bertrand E, Verheggen C. CRM1 controls the composition of nucleoplasmic pre-snoRNA complexes to licence them for nucleolar transport. EMBO J 2011; 30:2205-18. [PMID: 21522132 PMCID: PMC3117649 DOI: 10.1038/emboj.2011.128] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2011] [Accepted: 03/28/2011] [Indexed: 01/04/2023] Open
Abstract
Transport of C/D snoRNPs to nucleoli involves nuclear export factors. In particular, CRM1 binds nascent snoRNPs, but its precise role remains unknown. We show here that both CRM1 and nucleocytoplasmic trafficking are required to transport snoRNPs to nucleoli, but the snoRNPs do not transit through the cytoplasm. Instead, CRM1 controls the composition of nucleoplasmic pre-snoRNP complexes. We observed that Tgs1 long form (Tgs1 LF), the long isoform of the cap hypermethylase, contains a leucine-rich nuclear export signal, shuttles in a CRM1-dependent manner, and binds to the nucleolar localization signal (NoLS) of the core snoRNP protein Nop58. In vitro data indicate that CRM1 binds Tgs1 LF and promotes its dissociation from Nop58 NoLS, and immunoprecipitation experiments from cells indicate that the association of Tgs1 LF with snoRNPs increases upon CRM1 inhibition. Thus, CRM1 appears to promote nucleolar transport of snoRNPs by removing Tgs1 LF from the Nop58 NoLS. Microarray/IP data show that this occurs on most snoRNPs, from both C/D and H/ACA families, and on the telomerase RNA. Hence, CRM1 provides a general molecular link between nuclear events and nucleocytoplasmic trafficking.
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Affiliation(s)
- Bérengère Pradet-Balade
- Institut de Génétique Moléculaire de Montpellier, UMR 5535 CNRS, Université Montpellier I and II, Montpellier Cedex 5, France
| | - Cyrille Girard
- Institut de Génétique Moléculaire de Montpellier, UMR 5535 CNRS, Université Montpellier I and II, Montpellier Cedex 5, France
| | - Séverine Boulon
- Institut de Génétique Moléculaire de Montpellier, UMR 5535 CNRS, Université Montpellier I and II, Montpellier Cedex 5, France
| | - Conception Paul
- Institut de Génétique Moléculaire de Montpellier, UMR 5535 CNRS, Université Montpellier I and II, Montpellier Cedex 5, France
| | - Karim Azzag
- Institut de Génétique Moléculaire de Montpellier, UMR 5535 CNRS, Université Montpellier I and II, Montpellier Cedex 5, France
| | - Rémy Bordonné
- Institut de Génétique Moléculaire de Montpellier, UMR 5535 CNRS, Université Montpellier I and II, Montpellier Cedex 5, France
| | - Edouard Bertrand
- Institut de Génétique Moléculaire de Montpellier, UMR 5535 CNRS, Université Montpellier I and II, Montpellier Cedex 5, France
| | - Céline Verheggen
- Institut de Génétique Moléculaire de Montpellier, UMR 5535 CNRS, Université Montpellier I and II, Montpellier Cedex 5, France
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18
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Rodor J, Jobet E, Bizarro J, Vignols F, Carles C, Suzuki T, Nakamura K, Echeverría M. AtNUFIP, an essential protein for plant development, reveals the impact of snoRNA gene organisation on the assembly of snoRNPs and rRNA methylation in Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2011; 65:807-819. [PMID: 21261762 DOI: 10.1111/j.1365-313x.2010.04468.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In all eukaryotes, C/D small nucleolar ribonucleoproteins (C/D snoRNPs) are essential for methylation and processing of ribosomal RNAs. They consist of a box C/D small nucleolar RNA (C/D snoRNA) associated with four highly conserved nucleolar proteins. Recent data in HeLa cells and yeast have revealed that assembly of these snoRNPs is directed by NUFIP protein and other auxiliary factors. Nevertheless, the precise function and biological importance of NUFIP and the other assembly factors remains unknown. In plants, few studies have focused on RNA methylation and snoRNP biogenesis. Here, we identify and characterise the AtNUFIP gene that directs assembly of C/D snoRNP. To elucidate the function of AtNUFIP in planta, we characterized atnufip mutants. These mutants are viable but have severe developmental phenotypes. Northern blot analysis of snoRNA accumulation in atnufip mutants revealed a specific degradation of C/D snoRNAs and this situation is correlated with a reduction in rRNA methylation. Remarkably, the impact of AtNUFIP depends on the structure of snoRNA genes: it is essential for the accumulation of those C/D snoRNAs encoded by polycistronic genes, but not by monocistronic or tsnoRNA genes. We propose that AtNUFIP controls the kinetics of C/D snoRNP assembly on nascent precursors to overcome snoRNA degradation of aberrant RNPs. Finally, we show that AtNUFIP has broader RNP targets, controlling the accumulation of scaRNAs that direct methylation of spliceosomal snRNA in Cajal bodies.
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MESH Headings
- Amino Acid Sequence
- Arabidopsis/genetics
- Arabidopsis/metabolism
- Arabidopsis Proteins/genetics
- Arabidopsis Proteins/metabolism
- Gene Expression Profiling
- Genetic Complementation Test
- Methylation
- Molecular Sequence Data
- Mutagenesis, Insertional
- Mutation
- Phenotype
- Plants, Genetically Modified/genetics
- Plants, Genetically Modified/metabolism
- RNA Processing, Post-Transcriptional
- RNA Stability
- RNA, Plant/chemistry
- RNA, Plant/genetics
- RNA, Plant/metabolism
- RNA, Ribosomal/chemistry
- RNA, Small Nucleolar/genetics
- RNA, Small Nucleolar/metabolism
- Ribonucleoproteins, Small Nucleolar/genetics
- Ribonucleoproteins, Small Nucleolar/metabolism
- Sequence Alignment
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Affiliation(s)
- Julie Rodor
- Laboratoire Génome et Développement des Plantes, UMR 5096 Université de Perpignan via Domitia - Centre National de la Recherche Scientifique - Institut de Recherche pour le Développement, Perpignan, France
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19
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Li ZH, Tomlinson RL, Terns RM, Terns MP. Telomerase trafficking and assembly in Xenopus oocytes. J Cell Sci 2010; 123:2464-72. [PMID: 20592184 DOI: 10.1242/jcs.063750] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The core components of telomerase are telomerase RNA (TR) and telomerase reverse transcriptase (TERT). In vertebrate cells, TR and TERT have been reported to associate with intranuclear structures, including Cajal bodies and nucleoli as well as telomeres. Here, we examined the time course of both TR localization and assembly of TR with TERT in Xenopus oocytes. The major trafficking pathway for microinjected TR is through Cajal bodies into the nucleoplasm, with a fraction of TR found in nucleoli at later time points. Telomerase assembly precedes nucleolar localization of TR, and TR mutants that do not localize to nucleoli form active enzyme, indicating that localization of TR to nucleoli is not required for assembly with TERT. Assembly of telomerase coincides with Cajal-body localization; however, assembly is also unaffected by a CAB-box mutation (which significantly reduces association with Cajal bodies), suggesting that Cajal-body localization is not important for assembly. Our results suggest that assembly of TR with TERT occurs in the nucleoplasm. Unexpectedly, however, our experiments reveal that disruption of the CAB box does not eliminate early targeting to Cajal bodies, indicating that a role for Cajal bodies in telomerase assembly cannot be excluded on the basis of existing knowledge.
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Affiliation(s)
- Zhu-Hong Li
- Department of Biochemistry, University of Georgia, Athens, GA 30602, USA
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20
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Bogolyubov D, Stepanova I, Parfenov V. Universal nuclear domains of somatic and germ cells: some lessons from oocyte interchromatin granule cluster and Cajal body structure and molecular composition. Bioessays 2009; 31:400-9. [DOI: 10.1002/bies.200800100] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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21
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Sivaramakrishnan G, Sun Y, Tan SK, Lin VCL. Dynamic localization of tripartite motif-containing 22 in nuclear and nucleolar bodies. Exp Cell Res 2009; 315:1521-32. [PMID: 19331816 DOI: 10.1016/j.yexcr.2009.01.028] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Revised: 01/21/2009] [Accepted: 01/29/2009] [Indexed: 01/08/2023]
Abstract
Tripartite motif-containing 22 (TRIM22) exhibits antiviral and growth inhibitory properties, but there has been no study on the localization and dynamics of the endogenous TRIM22 protein. We report here that TRIM22 is dramatically induced by progesterone in MDA-MB-231-derived ABC28 cells and T47D cells. This induction was associated with an increase in TRIM22 nuclear bodies (NB), and an even more prominent increase in nucleolar TRIM22 bodies. Distinct endogenous TRIM22 NB were also demonstrated in several other cell lines including MCF7 and HeLa cells. These TRIM22 NB resemble Cajal bodies, co-localized with these structures and co-immunoprecipitated with p80-coilin. However, IFNgamma-induced TRIM22 in HeLa and MCF7 cells did not form NB, implying the forms and distribution of TRIM22 are regulated by specific cellular signals. This notion is also supported by the observation that TRIM22 NB undergoes dynamic cell-cycle dependent changes in distribution such that TRIM22 NB started to form in early G0/G1 but became dispersed in the S-phase. In light of its potential antiviral and antitumor properties, the findings here provide an interesting gateway to study the relationship between the different forms and functions of TRIM22.
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Affiliation(s)
- Gayathri Sivaramakrishnan
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
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22
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Morris GE. The Cajal body. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:2108-15. [PMID: 18755223 DOI: 10.1016/j.bbamcr.2008.07.016] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Revised: 07/21/2008] [Accepted: 07/23/2008] [Indexed: 12/30/2022]
Abstract
The Cajal body, originally identified over 100 years ago as a nucleolar accessory body in neurons, has come to be identified with nucleoplasmic structures, often quite tiny, that contain coiled threads of the marker protein, coilin. The interaction of coilin with other proteins appears to increase the efficiency of several nuclear processes by concentrating their components in the Cajal body. The best-known of these processes is the modification and assembly of U snRNPs, some of which eventually form the RNA splicing machinery, or spliceosome. Over the last 10 years, research into the function of Cajal bodies has been greatly stimulated by the discovery that SMN, the protein deficient in the inherited neuromuscular disease, spinal muscular atrophy, is a Cajal body component and has an essential role in the assembly of spliceosomal U snRNPs in the cytoplasm and their delivery to the Cajal body in the nucleus.
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Affiliation(s)
- Glenn E Morris
- Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, OSWESTRY, SY10 7AG, UK.
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23
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Identification of genes that function in the biogenesis and localization of small nucleolar RNAs in Saccharomyces cerevisiae. Mol Cell Biol 2008; 28:3686-99. [PMID: 18378690 DOI: 10.1128/mcb.01115-07] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Small nucleolar RNAs (snoRNAs) orchestrate the modification and cleavage of pre-rRNA and are essential for ribosome biogenesis. Recent data suggest that after nucleoplasmic synthesis, snoRNAs transiently localize to the Cajal body (in plant and animal cells) or the homologous nucleolar body (in budding yeast) for maturation and assembly into snoRNPs prior to accumulation in their primary functional site, the nucleolus. However, little is known about the trans-acting factors important for the intranuclear trafficking and nucleolar localization of snoRNAs. Here, we describe a large-scale genetic screen to identify proteins important for snoRNA transport in Saccharomyces cerevisiae. We performed fluorescence in situ hybridization analysis to visualize U3 snoRNA localization in a collection of temperature-sensitive yeast mutants. We have identified Nop4, Prp21, Tao3, Sec14, and Htl1 as proteins important for the proper localization of U3 snoRNA. Mutations in genes encoding these proteins lead to specific defects in the targeting or retention of the snoRNA to either the nucleolar body or the nucleolus. Additional characterization of the mutants revealed impairment in specific steps of U3 snoRNA processing, demonstrating that snoRNA maturation and trafficking are linked processes.
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24
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Abstract
The nucleolus is a multifunctional compartment of the eukaryotic nucleus. Besides its well-recognised role in transcription and processing of ribosomal RNA and the assembly of ribosomal subunits, the nucleolus has functions in the processing and assembly of a variety of RNPs and is involved in cell cycle control and senescence and as a sensor of stress. Historically, nucleoli have been tenuously linked to the biogenesis and, in particular, export of mRNAs in yeast and mammalian cells. Recently, data from plants have extended the functions in which the plant nucleolus is involved to include transcriptional gene silencing as well as mRNA surveillance and nonsense-mediated decay, and mRNA export. The nucleolus in plants may therefore have important roles in the biogenesis and quality control of mRNAs.
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Affiliation(s)
- Anireddy S. N. Reddy
- Department of Biology and Program in Molecular Plant Biology, Colorado State University, Fort Collins, CO 80523 USA
| | - Maxim Golovkin
- Department of Microbiology, Thomas Jefferson University, Philadelphia, PA 19107 USA
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25
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Bertrand E, Bordonné R. Assembly and Traffic of Small Nuclear RNPs. RNA TRAFFICKING AND NUCLEAR STRUCTURE DYNAMICS 2008; 35:79-97. [PMID: 15113080 DOI: 10.1007/978-3-540-74266-1_4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Edouard Bertrand
- Institut de Génétique Moléculaire de Montpellier, CNRS UMR 5535-IFR 122, 1919 route de Mende, 34293, Montpellier Cedex 5, France.
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26
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Platani M, Lamond AI. Nuclear organisation and subnuclear bodies. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2008; 35:1-22. [PMID: 15113077 DOI: 10.1007/978-3-540-74266-1_1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Melpomeni Platani
- Wellcome Trust Biocentre, MSI/WTB Complex, DD1 5EH, Dundee, Scotland, United Kingdom
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27
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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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28
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A compartmentalized phosphorylation/dephosphorylation system that regulates U snRNA export from the nucleus. Mol Cell Biol 2007; 28:487-97. [PMID: 17967890 DOI: 10.1128/mcb.01189-07] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
PHAX (phosphorylated adaptor for RNA export) is the key regulator of U snRNA nuclear export in metazoa. Our previous work revealed that PHAX is phosphorylated in the nucleus and is exported as a component of the U snRNA export complex to the cytoplasm, where it is dephosphorylated (M. Ohno, A. Segref, A. Bachi, M. Wilm, and I. W. Mattaj, Cell 101:187-198, 2000). PHAX phosphorylation is essential for export complex assembly, whereas its dephosphorylation causes export complex disassembly. Thus, PHAX is subject to a compartmentalized phosphorylation/dephosphorylation cycle that contributes to transport directionality. However, neither essential PHAX phosphorylation sites nor the modifying enzymes that contribute to the compartmentalized system have been identified. Here, we identify PHAX phosphorylation sites that are necessary and sufficient for U snRNA export. Mutation of the phosphorylation sites inhibited U snRNA export in a dominant-negative way. We also show, by both biochemical and RNA interference knockdown experiments, that the nuclear kinase and the cytoplasmic phosphatase for PHAX are CK2 kinase and protein phosphatase 2A, respectively. Our results reveal the composition of the compartmentalized phosphorylation/dephosphorylation system that regulates U snRNA export. This finding was surprising in that such a specific system for U snRNA export regulation is composed of two such universal regulators, suggesting that this compartmentalized system is used more broadly for gene expression regulation.
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29
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30
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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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31
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Degols G, Eldin P, Mechti N. ISG20, an actor of the innate immune response. Biochimie 2007; 89:831-5. [PMID: 17445960 DOI: 10.1016/j.biochi.2007.03.006] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2006] [Accepted: 03/08/2007] [Indexed: 12/01/2022]
Abstract
The interferon (IFN) system is a major effector of the innate immunity that allows time for the subsequent establishment of an adaptive immune response against wide-range pathogens. The effectiveness of IFN to control initial infection requires the cooperation between several pathways induced in the target cells. Recent studies that highlight the implication of the 3'-5' exonuclease ISG20 (IFN Stimulated Gene product of 20 kDa) in the host's defenses against pathogens are summarised in this review.
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Affiliation(s)
- Genevieve Degols
- UMR5160 CNRS, EFS, 240 Avenue Emile Jeanbrau, 34094 Montpellier Cedex 5, France
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32
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Makarova JA, Kramerov DA. Small nucleolar RNA genes. RUSS J GENET+ 2007. [DOI: 10.1134/s1022795407020019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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33
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Abstract
Three-dimensional architectural motifs are increasingly recognized as determinants of RNA functionality. We submit that such motifs can encode spatial information. RNAs are targeted to subcellular localities in many eukaryotic cell types, and especially in neuronal and glial cells, RNAs can be transported over long distances to their final destination sites. Such RNAs contain cis-acting long-range targeting elements, and recent evidence suggests that kink-turn motifs within such elements may act as spatial codes to direct transport. Kink-turns are complex RNA motifs that feature double- and single-stranded components and introduce a signature three-dimensional structure into helical stems. We propose that the overall architectural design as well as the individual character--as specified by nucleotide identity and arrangement--of kink-turn motifs can serve as RNA targeting determinants.
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Affiliation(s)
- Henri Tiedge
- The Robert F. Furchgott Center for Neural and Behavioral Science, Department of Physiology and Pharmacology, State University of New York, Health Science Center at Brooklyn, Brooklyn, New York 11203, USA.
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34
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Espert L, Eldin P, Gongora C, Bayard B, Harper F, Chelbi-Alix MK, Bertrand E, Degols G, Mechti N. The exonuclease ISG20 mainly localizes in the nucleolus and the Cajal (Coiled) bodies and is associated with nuclear SMN protein-containing complexes. J Cell Biochem 2006; 98:1320-33. [PMID: 16514659 DOI: 10.1002/jcb.20869] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
We have previously shown that ISG20, an interferon (IFN)-induced gene, encodes a 3' to 5' exoribonuclease member of the DEDD superfamily of exonucleases. ISG20 specifically degrades single-stranded RNA. In this report, using immunofluorescence analysis, we demonstrate that in addition to a diffuse cytoplasmic and nucleoplasmic localization, the endogenous ISG20 protein was present in the nucleus both in the nucleolus and in the Cajal bodies (CBs). In addition, we show that the ectopic expression of the CBs signature protein, coilin, fused to the red fluorescent protein (coilin-dsRed) increased the number of nuclear dots containing both ISG20 and coilin-dsRed. Using electron microcopy analysis, ISG20 appeared principally concentrated in the dense fibrillar component of the nucleolus, the major site for rRNA processing. We also present evidences that ISG20 was associated with survival of motor neuron (SMN)-containing macromolecular nuclear complexes required for the biogenesis of various small nuclear ribonucleoproteins. Finally, we demonstrate that ISG20 was associated with U1 and U2 snRNAs, and U3 snoRNA. The accumulation of ISG20 in the CBs after IFN treatment strongly suggests its involvement in a new route for IFN-mediated inhibition of protein synthesis by modulating snRNA and rRNA maturation.
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Affiliation(s)
- Lucile Espert
- UMR 5160 CNRS, EFS, 240 avenue Emile Jeanbrau, 34094 Montpellier Cedex 5, France
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35
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Kiss T, Fayet E, Jády BE, Richard P, Weber M. Biogenesis and intranuclear trafficking of human box C/D and H/ACA RNPs. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2006; 71:407-17. [PMID: 17381323 DOI: 10.1101/sqb.2006.71.025] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Box C/D and H/ACA snoRNAs represent two abundant groups of small noncoding RNAs. The majority of box C/D and H/ACA snoRNAs function as guide RNAs in the site-specific 2'-O-methylation and pseudouridylation of rRNAs, respectively. The box C/D snoRNAs associate with fibrillarin, Nop56, Nop58, and 15.5K/NHPX proteins to form functional snoRNP particles, whereas all box H/ACA snoRNAs form complexes with the dyskerin, Nop10, Nhp2, and Gar1 snoRNP proteins. Recent studies demonstrate that the biogenesis of mammalian snoRNPs is a complex process that requires numerous trans-acting factors. Most vertebrate snoRNAs are posttranscriptionally processed from pre-mRNA introns, and the early steps of snoRNP assembly are physically and functionally coupled with the synthesis or splicing of the host pre-mRNA. The maturing snoRNPs follow a complicated intranuclear trafficking process that is directed by transport factors also involved in nucleocytoplasmic RNA transport. The human telomerase RNA (hTR) carries a box H/ACA RNA domain that shares a common Cajal-body-specific localization element with a subclass of box H/ACA RNAs, which direct pseudouridylation of spliceosomal snRNAs in the Cajal body. However, besides concentrating in Cajal bodies, hTR also accumulates at a small, structurally distinct subset of telomeres during S phase. This suggests that a cell-cycle-dependent, dynamic localization of hTR to telomeres may play an important regulatory role in human telomere synthesis.
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MESH Headings
- Active Transport, Cell Nucleus
- Coiled Bodies/metabolism
- Humans
- Introns
- Models, Biological
- Nucleic Acid Conformation
- RNA/genetics
- RNA/metabolism
- RNA Polymerase II/metabolism
- RNA Splicing
- RNA, Small Nucleolar/chemistry
- RNA, Small Nucleolar/genetics
- RNA, Small Nucleolar/metabolism
- Ribonucleoproteins/chemistry
- Ribonucleoproteins/genetics
- Ribonucleoproteins/metabolism
- Ribonucleoproteins, Small Nucleolar/chemistry
- Ribonucleoproteins, Small Nucleolar/genetics
- Ribonucleoproteins, Small Nucleolar/metabolism
- Telomerase/genetics
- Telomerase/metabolism
- Transcription, Genetic
- RNA, Small Untranslated
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Affiliation(s)
- T Kiss
- Laboratoire de Biologie Moléculaire Eucaryote du CNRS, UMR5099, IFR109, Toulouse, France
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36
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Borovjagin AV, Gerbi SA. An evolutionary intra-molecular shift in the preferred U3 snoRNA binding site on pre-ribosomal RNA. Nucleic Acids Res 2005; 33:4995-5005. [PMID: 16147982 PMCID: PMC1199564 DOI: 10.1093/nar/gki815] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Correct docking of U3 small nucleolar RNA (snoRNA) on pre-ribosomal RNA (pre-rRNA) is essential for rRNA processing to produce 18S rRNA. In this report, we have used Xenopus oocytes to characterize the structural requirements of the U3 snoRNA 3′-hinge interaction with region E1 of the external transcribed spacer (ETS) of pre-rRNA. This interaction is crucial for docking to initiate rRNA processing. 18S rRNA production was inhibited when fewer than 6 of the 8 bp of the U3 3′–hinge complex with the ETS could form; moreover, base pairing involving the right side of the 3′-hinge was more important than the left. Increasing the length of the U3 hinge–ETS interaction by 9 bp impaired rRNA processing. Formation of 18S rRNA was also inhibited by swapping the U3 5′- and 3′-hinge interactions with the ETS or by shifting the base pairing of the U3 3′-hinge to the sequence directly adjacent to ETS region E1. However, 18S rRNA production was partially restored by a compensatory shift that allowed the sequence adjacent to the U3 3′-hinge to pair with the eight bases directly adjacent to ETS region E1. The results suggest that the geometry of the U3 snoRNA interaction with the ETS is critical for rRNA processing.
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MESH Headings
- Animals
- Base Pairing
- Base Sequence
- Binding Sites
- Evolution, Molecular
- Molecular Sequence Data
- Mutation
- RNA Precursors/chemistry
- RNA Precursors/genetics
- RNA Precursors/metabolism
- RNA Processing, Post-Transcriptional
- RNA, Ribosomal, 18S/chemistry
- RNA, Ribosomal, 18S/genetics
- RNA, Ribosomal, 18S/metabolism
- RNA, Small Nucleolar/chemistry
- RNA, Small Nucleolar/genetics
- RNA, Small Nucleolar/metabolism
- Xenopus laevis
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Affiliation(s)
| | - Susan A. Gerbi
- To whom correspondence should be addressed. Tel: +1 401 863 2359; Fax: +1 401 863 1348;
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37
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Baker DL, Youssef OA, Chastkofsky MIR, Dy DA, Terns RM, Terns MP. RNA-guided RNA modification: functional organization of the archaeal H/ACA RNP. Genes Dev 2005; 19:1238-48. [PMID: 15870259 PMCID: PMC1132009 DOI: 10.1101/gad.1309605] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
In eukaryotes and archaea, uridines in various RNAs are converted to pseudouridines by RNA-guided RNA modification complexes termed H/ACA RNPs. Guide RNAs within the complexes base-pair with target RNAs to direct modification of specific ribonucleotides. Cbf5, a protein component of the complex, likely catalyzes the modification. However, little is known about the organization of H/ACA RNPs and the roles of the multiple proteins thought to comprise the complexes. We have reconstituted functional archaeal H/ACA RNPs from recombinant components, defined the components necessary and sufficient for function, and determined the direct RNA-protein and protein-protein interactions that occur between the components. The results provide substantial insight into the functional organization of this RNP. The functional complex requires a guide RNA and each of four proteins: Cbf5, Gar1, L7Ae, and Nop10. Two proteins interact directly with the guide RNA: L7Ae and Cbf5. L7Ae does not interact with other H/ACA RNP proteins in the absence of the RNA. We have defined two novel functions for Cbf5. Cbf5 is the protein that specifically recognizes and binds H/ACA guide RNAs. In addition, Cbf5 recruits the two other essential proteins, Gar1 and Nop10, to the pseudouridylation guide complex.
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Affiliation(s)
- Daniel L Baker
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, USA
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38
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Boulon S, Verheggen C, Jady BE, Girard C, Pescia C, Paul C, Ospina JK, Kiss T, Matera AG, Bordonné R, Bertrand E. PHAX and CRM1 are required sequentially to transport U3 snoRNA to nucleoli. Mol Cell 2004; 16:777-87. [PMID: 15574332 DOI: 10.1016/j.molcel.2004.11.013] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2004] [Revised: 08/26/2004] [Accepted: 10/13/2004] [Indexed: 10/26/2022]
Abstract
To better understand intranuclear-targeting mechanisms, we have studied the transport of U3 snoRNA in human cells. Surprisingly, we found that PHAX, the snRNA export adaptor, is highly enriched in complexes containing m7G-capped U3 precursors. In contrast, the export receptor CRM1 is predominantly bound to TMG-capped U3 species. In agreement, PHAX does not export m7G-capped U3 precursors because their caps become hypermethylated in the nucleus. Inactivation of PHAX and CRM1 shows that U3 first requires PHAX to reach Cajal bodies, and then CRM1 to be routed from there to nucleoli. Furthermore, PHAX also binds the precursors of U8 and U13 box C/D snoRNAs and telomerase RNA. PHAX was previously shown to discriminate between small versus large RNAs during export. Our data indicate that the role of PHAX in determining the identity of small RNAs extends to nonexported species, and this appears critical to promote their transport within the nucleus.
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Affiliation(s)
- Séverine Boulon
- IGMM, CNRS UMR 5535, IFR 122, 34293 Montpellier Cedex 5, France
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39
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Stanĕk D, Neugebauer KM. Detection of snRNP assembly intermediates in Cajal bodies by fluorescence resonance energy transfer. ACTA ACUST UNITED AC 2004; 166:1015-25. [PMID: 15452143 PMCID: PMC2172029 DOI: 10.1083/jcb.200405160] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Spliceosomal small nuclear ribonucleoprotein particles (snRNPs) are required for pre-mRNA splicing throughout the nucleoplasm, yet snRNPs also concentrate in Cajal bodies (CBs). To address a proposed role of CBs in snRNP assembly, we have used fluorescence resonance energy transfer (FRET) microscopy to investigate the subnuclear distribution of specific snRNP intermediates. Two distinct complexes containing the protein SART3 (p110), required for U4/U6 snRNP assembly, were localized: SART3•U6 snRNP and SART3•U4/U6 snRNP. These complexes segregated to different nuclear compartments, with SART3•U6 snRNPs exclusively in the nucleoplasm and SART3•U4/U6 snRNPs preferentially in CBs. Mutant cells lacking the CB-specific protein coilin and consequently lacking CBs exhibited increased nucleoplasmic levels of SART3•U4/U6 snRNP complexes. Reconstitution of CBs in these cells by expression of exogenous coilin restored accumulation of SART3•U4/U6 snRNP in CBs. Thus, while some U4/U6 snRNP assembly can occur in the nucleoplasm, these data provide evidence that SART3•U6 snRNPs form in the nucleoplasm and translocate to CBs where U4/U6 snRNP assembly occurs.
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Affiliation(s)
- David Stanĕk
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
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40
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Watkins NJ, Lemm I, Ingelfinger D, Schneider C, Hossbach M, Urlaub H, Lührmann R. Assembly and Maturation of the U3 snoRNP in the Nucleoplasm in a Large Dynamic Multiprotein Complex. Mol Cell 2004; 16:789-98. [PMID: 15574333 DOI: 10.1016/j.molcel.2004.11.012] [Citation(s) in RCA: 134] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2004] [Revised: 09/01/2004] [Accepted: 10/05/2004] [Indexed: 12/14/2022]
Abstract
The assembly and maturation of box C/D snoRNPs, factors essential for ribosome biogenesis, occur in the nucleoplasm. To investigate this process, we have analyzed non-snoRNP factors associated with the nucleoplasmic human U3 snoRNA. We show that both the precursor and mature length nucleoplasmic U3 snoRNAs are present in larger multiprotein complexes that contain the core box C/D proteins as well as many non-snoRNP factors linked to snoRNP assembly (TIP48, TIP49, Nopp140), RNA processing (TGS1, La, LSm4, hRrp46), and subcellular localization (CRM1, PHAX). Using RNAi, we show that most of these factors are essential for box C/D snoRNA accumulation. Furthermore, we demonstrate that the core proteins undergo a restructuring event that stabilizes their binding to the snoRNA. Importantly, restructuring, which may be mediated by the putative remodeling factor TIP49, appears to be linked to nucleolar localization. We believe that the assembly complex coordinates snoRNA processing, snoRNP assembly, restructuring, and localization.
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Affiliation(s)
- Nicholas J Watkins
- Max-Planck-Institute of Biophysical Chemistry, Am Fassberg 11, D-37070 Göttingen, Germany.
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41
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Bubulya PA, Prasanth KV, Deerinck TJ, Gerlich D, Beaudouin J, Ellisman MH, Ellenberg J, Spector DL. Hypophosphorylated SR splicing factors transiently localize around active nucleolar organizing regions in telophase daughter nuclei. ACTA ACUST UNITED AC 2004; 167:51-63. [PMID: 15479736 PMCID: PMC2172523 DOI: 10.1083/jcb.200404120] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Upon completion of mitosis, daughter nuclei assemble all of the organelles necessary for the implementation of nuclear functions. We found that upon entry into daughter nuclei, snRNPs and SR proteins do not immediately colocalize in nuclear speckles. SR proteins accumulated in patches around active nucleolar organizing regions (NORs) that we refer to as NOR-associated patches (NAPs), whereas snRNPs were enriched at other nuclear regions. NAPs formed transiently, persisting for 15–20 min before dissipating as nuclear speckles began to form in G1. In the absence of RNA polymerase II transcription, NAPs increased in size and persisted for at least 2 h, with delayed localization of SR proteins to nuclear speckles. In addition, SR proteins in NAPs are hypophosphorylated, and the SR protein kinase Clk/STY colocalizes with SR proteins in NAPs, suggesting that phosphorylation releases SR proteins from NAPs and their initial target is transcription sites. This work demonstrates a previously unrecognized role of NAPs in splicing factor trafficking and nuclear speckle biogenesis.
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Affiliation(s)
- Paula A Bubulya
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
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42
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Granneman S, Vogelzangs J, Lührmann R, van Venrooij WJ, Pruijn GJM, Watkins NJ. Role of pre-rRNA base pairing and 80S complex formation in subnucleolar localization of the U3 snoRNP. Mol Cell Biol 2004; 24:8600-10. [PMID: 15367679 PMCID: PMC516741 DOI: 10.1128/mcb.24.19.8600-8610.2004] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In the nucleolus the U3 snoRNA is recruited to the 80S pre-rRNA processing complex in the dense fibrillar component (DFC). The U3 snoRNA is found throughout the nucleolus and has been proposed to move with the preribosomes to the granular component (GC). In contrast, the localization of other RNAs, such as the U8 snoRNA, is restricted to the DFC. Here we show that the incorporation of the U3 snoRNA into the 80S processing complex is not dependent on pre-rRNA base pairing sequences but requires the B/C motif, a U3-specific protein-binding element. We also show that the binding of Mpp10 to the 80S U3 complex is dependent on sequences within the U3 snoRNA that base pair with the pre-rRNA adjacent to the initial cleavage site. Furthermore, mutations that inhibit 80S complex formation and/or the association of Mpp10 result in retention of the U3 snoRNA in the DFC. From this we propose that the GC localization of the U3 snoRNA is a direct result of its active involvement in the initial steps of ribosome biogenesis.
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Affiliation(s)
- Sander Granneman
- Department of Biochemistry, University of Nijmegen, The Netherlands
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43
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van Koningsbruggen S, Dirks RW, Mommaas AM, Onderwater JJ, Deidda G, Padberg GW, Frants RR, van der Maarel SM. FRG1P is localised in the nucleolus, Cajal bodies, and speckles. J Med Genet 2004. [DOI: 10.1136/jmg.2003.012781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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44
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Affiliation(s)
- Joseph G Gall
- Department of Embryology, Carnegie Institution of Washington, 115 West University Parkway, Baltimore, Maryland 21210, USA.
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45
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Leary DJ, Terns MP, Huang S. Components of U3 snoRNA-containing complexes shuttle between nuclei and the cytoplasm and differentially localize in nucleoli: implications for assembly and function. Mol Biol Cell 2004; 15:281-93. [PMID: 14565981 PMCID: PMC307547 DOI: 10.1091/mbc.e03-06-0363] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2003] [Revised: 07/31/2003] [Accepted: 08/26/2003] [Indexed: 11/11/2022] Open
Abstract
U3 small nucleolar RNA (snoRNA) and associated proteins are required for the processing of preribosomal RNA (pre-rRNA) and assembly of preribosomes. There are two major U3 snoRNA-containing complexes. The monoparticle contains U3 snoRNA and the core Box C/D snoRNA-associated proteins and an early preribosome-associated complex contains the monoparticle and additional factors that we refer to as preribosome-associated proteins. To address how and where the U3 snoRNA-containing preribosome assembles and how these processes are temporally and spatially regulated, we have examined the dynamics and distribution of human U3 complex-associated components in cells with active or inactive transcription of rDNA. We found that U3 complex-associated proteins shuttle between the nucleus and the cytoplasm independent of the synthesis and export of preribosomal particles, suggesting that the shuttling of these proteins may either provide opportunities for their regulation, or contribute to or modulate ribosome export. In addition, monoparticle and preribosome associated components predominantly localize to different nucleolar substructures, fibrillar components, and granular components, respectively, in active nucleoli, and partition separately into the two components during nucleolar segregation induced by inhibition of pol I transcription. Although the predominant localizations of these two sets of factors differ, there are significant areas of overlap that may represent the sites where they reside as a single complex. These results are consistent with a model in which U3 monoparticles associate with the fibrillar components of nucleoli and bind pre-rRNA during transcription, triggering recruitment of preribosome-associated proteins to assemble the complex necessary for pre-rRNA processing.
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Affiliation(s)
- Daniel J Leary
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611, USA
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46
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Newton K, Petfalski E, Tollervey D, Cáceres JF. Fibrillarin is essential for early development and required for accumulation of an intron-encoded small nucleolar RNA in the mouse. Mol Cell Biol 2003; 23:8519-27. [PMID: 14612397 PMCID: PMC262675 DOI: 10.1128/mcb.23.23.8519-8527.2003] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Fibrillarin, a protein component of C/D box small nucleolar ribonucleoproteins (snoRNPs), directs 2'-O-methylation of rRNA and is also involved in other aspects of rRNA processing. A gene trap screen in embryonic stem (ES) cells resulted in an insertion mutation in the fibrillarin gene. This insertion generated a fusion protein that contained the N-terminal 132 amino acids of fibrillarin fused to a beta-galactosidase-neomycin phosphotransferase reporter. As a result, the N-terminal GAR domain was present in the fusion protein but the methyltransferase-like domain was missing. The ES cell line with the targeted fibrillarin allele was transmitted through the mouse germ line, creating heterozygous animals. Western blot analyses showed a reduction in fibrillarin protein levels in the heterozygous knockout animals. Animals homozygous for the mutation were inviable, and massive apoptosis was observed in early Fibrillarin(-/-) embryos, showing that fibrillarin is essential for development. Fibrillarin(+/-) live-born mice displayed no obvious growth defect, but heterozygous intercrosses revealed a reduced ratio of +/- to +/+ mice, showing that some of the Fibrillarin heterozygous embryos die in utero. Analyses of tissue samples and cultured embryonic fibroblasts showed no discernible alteration in pre-rRNA processing or the level of the U3 snoRNA. However, the level of the intron-encoded box C/D snoRNA U76 was clearly reduced. This suggests a high requirement for snoRNA synthesis during an early stage in development.
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MESH Headings
- Amino Acid Sequence
- Animals
- Apoptosis/genetics
- Apoptosis/physiology
- Base Sequence
- Chromosomal Proteins, Non-Histone/deficiency
- Chromosomal Proteins, Non-Histone/genetics
- Chromosomal Proteins, Non-Histone/metabolism
- Embryonic and Fetal Development/genetics
- Embryonic and Fetal Development/physiology
- Female
- Gene Expression Regulation, Developmental
- Heterozygote
- Introns
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Molecular Sequence Data
- Mutagenesis, Insertional
- Phenotype
- Pregnancy
- RNA Processing, Post-Transcriptional
- RNA, Small Nucleolar/genetics
- RNA, Small Nucleolar/metabolism
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
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Affiliation(s)
- Kathryn Newton
- MRC Human Genetics Unit, Edinburgh EH4 2XU, United Kingdom
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47
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Qi Y, Ding B. Differential subnuclear localization of RNA strands of opposite polarity derived from an autonomously replicating viroid. THE PLANT CELL 2003; 15:2566-77. [PMID: 14555700 PMCID: PMC280561 DOI: 10.1105/tpc.016576] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2003] [Accepted: 09/13/2003] [Indexed: 05/20/2023]
Abstract
The wide variety of RNAs produced in the nucleus must be localized correctly to perform their functions. However, the mechanism of this localization is poorly understood. We report here the differential subnuclear localization of RNA strands of opposite polarity derived from the replicating Potato spindle tuber viroid (PSTVd). During replication, (+)- and (-)-strand viroid RNAs are produced. We found that in infected cultured cells and plants, the (-)-strand RNA was localized in the nucleoplasm, whereas the (+)-strand RNA was localized in the nucleolus as well as in the nucleoplasm with distinct spatial patterns. Furthermore, the presence of the (+)-PSTVd in the nucleolus caused the redistribution of a small nucleolar RNA. Our results support a model in which (1) the synthesis of the (-)- and (+)-strands of PSTVd RNAs occurs in the nucleoplasm, (2) the (-)-strand RNA is anchored in the nucleoplasm, and (3) the (+)-strand RNA is transported selectively into the nucleolus. Our results imply that the eukaryotic cell has a machinery that recognizes and localizes the opposite strands of an RNA, which may have broad ramifications in the RNA regulation of gene expression and the infection cycle of pathogenic RNAs and in the development of RNA-based methods to control gene expression as well as pathogen infection.
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Affiliation(s)
- Yijun Qi
- Department of Plant Biology and Plant Biotechnology Center, Ohio State University, Columbus, Ohio 43210, USA
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48
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Richard P, Darzacq X, Bertrand E, Jády BE, Verheggen C, Kiss T. A common sequence motif determines the Cajal body-specific localization of box H/ACA scaRNAs. EMBO J 2003; 22:4283-93. [PMID: 12912925 PMCID: PMC175784 DOI: 10.1093/emboj/cdg394] [Citation(s) in RCA: 161] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Post-transcriptional synthesis of 2'-O-methylated nucleotides and pseudouridines in Sm spliceosomal small nuclear RNAs takes place in the nucleoplasmic Cajal bodies and it is directed by guide RNAs (scaRNAs) that are structurally and functionally indistinguishable from small nucleolar RNAs (snoRNAs) directing rRNA modification in the nucleolus. The scaRNAs are synthesized in the nucleoplasm and specifically targeted to Cajal bodies. Here, mutational analysis of the human U85 box C/D-H/ACA scaRNA, followed by in situ localization, demonstrates that box H/ACA scaRNAs share a common Cajal body-specific localization signal, the CAB box. Two copies of the evolutionarily conserved CAB consensus (UGAG) are located in the terminal loops of the 5' and 3' hairpins of the box H/ACA domains of mammalian, Drosophila and plant scaRNAs. Upon alteration of the CAB boxes, mutant scaRNAs accumulate in the nucleolus. In turn, authentic snoRNAs can be targeted into Cajal bodies by addition of exogenous CAB box motifs. Our results indicate that scaRNAs represent an ancient group of small nuclear RNAs which are localized to Cajal bodies by an evolutionarily conserved mechanism.
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Affiliation(s)
- Patricia Richard
- Laboratoire de Biologie Moléculaire Eucaryote du CNRS, UMR5099, IFR109, 118 route de Narbonne, 31062 Toulouse, France
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49
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Marmier-Gourrier N, Cléry A, Senty-Ségault V, Charpentier B, Schlotter F, Leclerc F, Fournier R, Branlant C. A structural, phylogenetic, and functional study of 15.5-kD/Snu13 protein binding on U3 small nucleolar RNA. RNA (NEW YORK, N.Y.) 2003; 9:821-38. [PMID: 12810916 PMCID: PMC1370449 DOI: 10.1261/rna.2130503] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2002] [Accepted: 03/28/2003] [Indexed: 05/19/2023]
Abstract
The 15.5-kD protein and its yeast homolog Snu13p bind U4 snRNA, U3 snoRNA, and the C/D box snoRNAs. In U4 snRNA, they associate with a helix-bulge-helix (K-turn) structure. U3 snoRNA contains two conserved pairs of boxes, C'/D and B/C, which were both expected to bind the 15.5-kD/Snu13 protein. Only binding to the B/C motif was experimentally demonstrated. Here, by chemical probing of in vitro reconstituted RNA/protein complexes, we demonstrate the independent binding of the 15.5-kD/Snu13 protein to each of the two motifs. Due to a highly reduced stem I (1 bp), the K-turn structure is not formed in the naked B/C motif. However, gel-shift experiments revealed a higher affinity of Snu13p for the B/C motif, compared to the C'/D motif. A phylogenetic analysis of U3 snoRNA, coupled with an analysis of Snu13p affinity for variant yeast C'/D and B/C motifs, and a study of the functionality of a truncated yeast U3 snoRNA carrying base substitutions in the C'/D and B/C motifs, revealed that conservation of the identities of residues 2 and 3 in the B/C K-turn is more important for Snu13p binding and U3 snoRNA function, than conservation of the identities of corresponding residues in the C'/D K-turn. This suggests that binding of Snu13p to K-turns with a very short helix I imposes sequence constraints in the bulge. Altogether, the data demonstrate the strong importance of the binding of the 15.5-kD/Snu13 protein to the C'/D and B/C motifs for both U3 snoRNP assembly and activity.
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MESH Headings
- Base Sequence
- Binding Sites
- Genetic Variation
- Models, Molecular
- Molecular Sequence Data
- Nucleic Acid Conformation
- Oligodeoxyribonucleotides
- Phylogeny
- Protein Binding
- RNA, Fungal/chemistry
- RNA, Fungal/genetics
- RNA, Fungal/metabolism
- RNA, Small Nuclear/chemistry
- RNA, Small Nuclear/genetics
- RNA, Small Nuclear/metabolism
- RNA, Small Nucleolar/genetics
- Ribonucleoproteins, Small Nuclear/genetics
- Saccharomyces cerevisiae Proteins/genetics
- Templates, Genetic
- Transcription, Genetic
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Affiliation(s)
- Nathalie Marmier-Gourrier
- Laboratoire de Maturation des ARN et Enzymologie Moléculaire, UMR 7567 UHP-CNRS, Université Henri Poincaré Nancy 1, 54506 Vandoeuvre-Lès-Nancy cedex, France
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Gerbi SA, Borovjagin AV, Ezrokhi M, Lange TS. Ribosome biogenesis: role of small nucleolar RNA in maturation of eukaryotic rRNA. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2003; 66:575-90. [PMID: 12762059 DOI: 10.1101/sqb.2001.66.575] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- S A Gerbi
- Division of Biology and Medicine, Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island 02912, USA
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