1
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López J, Blanco S. Exploring the role of ribosomal RNA modifications in cancer. Curr Opin Genet Dev 2024; 86:102204. [PMID: 38759459 DOI: 10.1016/j.gde.2024.102204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Revised: 04/05/2024] [Accepted: 05/03/2024] [Indexed: 05/19/2024]
Abstract
Recent advances have highlighted the significant roles of post-transcriptional modifications in rRNA in various cancers. Evidence suggests that dysregulation of rRNA modifications acts as a common denominator in cancer development, with alterations in these modifications conferring competitive advantages to cancer cells. Specifically, rRNA modifications modulate protein synthesis and favor the specialized translation of oncogenic programs, thereby contributing to the formation of a protumorigenic proteome in cancer cells. These findings reveal a novel regulatory layer mediated by changes in the deposition of rRNA chemical modifications. Moreover, inhibition of these modifications in vitro and in preclinical studies demonstrates potential therapeutic applications. The recurrence of altered rRNA modification patterns across different types of cancer underscores their importance in cancer progression, proposing them as potential biomarkers and novel therapeutic targets. This review will highlight the latest insights into how post-transcriptional rRNA modifications contribute to cancer progression and summarize the main developments and ongoing challenges in this research area.
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Affiliation(s)
- Judith López
- Centro de Investigación del Cáncer and Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC) - University of Salamanca, 37007 Salamanca, Spain; Instituto de Investigación Biomédica de Salamanca (IBSAL), Hospital Universitario de Salamanca, 37007 Salamanca, Spain. https://twitter.com/@judithlopezluis
| | - Sandra Blanco
- Centro de Investigación del Cáncer and Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC) - University of Salamanca, 37007 Salamanca, Spain; Instituto de Investigación Biomédica de Salamanca (IBSAL), Hospital Universitario de Salamanca, 37007 Salamanca, Spain.
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2
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Leppik M, Pomerants L, Põldes A, Mihkelson P, Remme J, Tamm T. Loss of Conserved rRNA Modifications in the Peptidyl Transferase Center Leads to Diminished Protein Synthesis and Cell Growth in Budding Yeast. Int J Mol Sci 2024; 25:5194. [PMID: 38791231 PMCID: PMC11121408 DOI: 10.3390/ijms25105194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Revised: 05/07/2024] [Accepted: 05/08/2024] [Indexed: 05/26/2024] Open
Abstract
Ribosomal RNAs (rRNAs) are extensively modified during the transcription and subsequent maturation. Three types of modifications, 2'-O-methylation of ribose moiety, pseudouridylation, and base modifications, are introduced either by a snoRNA-driven mechanism or by stand-alone enzymes. Modified nucleotides are clustered at the functionally important sites, including peptidyl transferase center (PTC). Therefore, it has been hypothesised that the modified nucleotides play an important role in ensuring the functionality of the ribosome. In this study, we demonstrate that seven 25S rRNA modifications, including four evolutionarily conserved modifications, in the proximity of PTC can be simultaneously depleted without loss of cell viability. Yeast mutants lacking three snoRNA genes (snR34, snR52, and snR65) and/or expressing enzymatically inactive variants of spb1(D52A/E679K) and nop2(C424A/C478A) were constructed. The results show that rRNA modifications in PTC contribute collectively to efficient translation in eukaryotic cells. The deficiency of seven modified nucleotides in 25S rRNA resulted in reduced cell growth, cold sensitivity, decreased translation levels, and hyperaccurate translation, as indicated by the reduced missense and nonsense suppression. The modification m5C2870 is crucial in the absence of the other six modified nucleotides. Thus, the pattern of rRNA-modified nucleotides around the PTC is essential for optimal ribosomal translational activity and translational fidelity.
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Affiliation(s)
| | | | | | | | | | - Tiina Tamm
- Institute of Molecular and Cell Biology, University of Tartu, 51010 Tartu, Estonia; (M.L.); (L.P.); (A.P.); (P.M.); (J.R.)
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3
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Mu Y, Han J, Wu M, Li Z, DU K, Wei Y, Wu M, Huang J. Fibrillarin promotes homologous recombination repair by facilitating the recruitment of recombinase RAD51 to DNA damage sites. J Zhejiang Univ Sci B 2023; 24:1165-1173. [PMID: 38057273 PMCID: PMC10710916 DOI: 10.1631/jzus.b2300518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 10/10/2023] [Indexed: 12/08/2023]
Abstract
Eukaryotic organisms constantly face a wide range of internal and external factors that cause damage to their DNA. Failure to accurately and efficiently repair these DNA lesions can result in genomic instability and the development of tumors (Canela et al., 2017). Among the various forms of DNA damage, DNA double-strand breaks (DSBs) are particularly harmful. Two major pathways, non-homologous end joining (NHEJ) and homologous recombination (HR), are primarily responsible for repairing DSBs (Katsuki et al., 2020; Li and Yuan, 2021; Zhang and Gong, 2021; Xiang et al., 2023). NHEJ is an error-prone repair mechanism that simply joins the broken ends together (Blunt et al., 1995; Hartley et al., 1995). In contrast, HR is a precise repair process. It involves multiple proteins in eukaryotic cells, with the RAD51 recombinase being the key player, which is analogous to bacterial recombinase A (RecA) (Shinohara et al., 1992). The central event in HR is the formation of RAD51-single-stranded DNA (ssDNA) nucleoprotein filaments that facilitate homology search and DNA strand invasion, ultimately leading to the initiation of repair synthesis (Miné et al., 2007; Hilario et al., 2009; Ma et al., 2017).
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Affiliation(s)
- Yanhua Mu
- National-Local Joint Engineering Research Center of Biodiagnosis & Biotherapy, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710004, China
- The MOE Key Laboratory of Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
| | - Jinhua Han
- Zhejiang Provincial Key Lab of Geriatrics and Geriatrics Institute of Zhejiang Province, Department of Geriatrics, Zhejiang Hospital, Hangzhou 310030, China
| | - Mingjie Wu
- Trauma Center, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China
| | - Zongfang Li
- National-Local Joint Engineering Research Center of Biodiagnosis & Biotherapy, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710004, China
| | - Ke DU
- National-Local Joint Engineering Research Center of Biodiagnosis & Biotherapy, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710004, China
| | - Yameng Wei
- National-Local Joint Engineering Research Center of Biodiagnosis & Biotherapy, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710004, China
| | - Mengjie Wu
- The Affiliated Hospital of Stomatology, School of Stomatology, Zhejiang University School of Medicine, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Hangzhou 310006, China. ,
| | - Jun Huang
- Zhejiang Provincial Key Lab of Geriatrics and Geriatrics Institute of Zhejiang Province, Department of Geriatrics, Zhejiang Hospital, Hangzhou 310030, China.
- Zhejiang Provincial Key Laboratory of Cancer Molecular Cell Biology, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China.
- Department of General Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310016, China.
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4
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Yakoub G, Choi YS, Wong RP, Strauch T, Ann KJ, Cohen RE, Ulrich HD. Avidity-based biosensors for ubiquitylated PCNA reveal choreography of DNA damage bypass. SCIENCE ADVANCES 2023; 9:eadf3041. [PMID: 37672592 PMCID: PMC10482348 DOI: 10.1126/sciadv.adf3041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 08/03/2023] [Indexed: 09/08/2023]
Abstract
In eukaryotes, the posttranslational modifier ubiquitin is used to regulate the amounts, interactions, or activities of proteins in diverse pathways and signaling networks. Its effects are mediated by monoubiquitin or polyubiquitin chains of varying geometries. We describe the design, validation, and application of a series of avidity-based probes against the ubiquitylated forms of the DNA replication clamp, proliferating cell nuclear antigen (PCNA), in budding yeast. Directed against total ubiquitylated PCNA or specifically K63-polyubiquitylated PCNA, the probes are tunable in their activities and can be used either as biosensors or as inhibitors of the PCNA-dependent DNA damage bypass pathway. Used in live cells, the probes revealed the timing of PCNA ubiquitylation during damage bypass and a particular susceptibility of the ribosomal DNA locus to the activation of the pathway. Our approach is applicable to a wide range of ubiquitin-conjugated proteins, thus representing a generalizable strategy for the design of biosensors for specific (poly)ubiquitylated forms of individual substrates.
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Affiliation(s)
- George Yakoub
- Institute of Molecular Biology gGmbH, Ackermannweg 4, D-55128 Mainz, Germany
| | - Yun-Seok Choi
- Department of Biochemistry and Molecular Biology, Colorado State University, 273 MRB, 1870 Campus Delivery, Fort Collins, CO 80523-1870, USA
| | - Ronald P. Wong
- Institute of Molecular Biology gGmbH, Ackermannweg 4, D-55128 Mainz, Germany
| | - Tina Strauch
- Institute of Molecular Biology gGmbH, Ackermannweg 4, D-55128 Mainz, Germany
| | - Kezia J. Ann
- Institute of Molecular Biology gGmbH, Ackermannweg 4, D-55128 Mainz, Germany
| | - Robert E. Cohen
- Department of Biochemistry and Molecular Biology, Colorado State University, 273 MRB, 1870 Campus Delivery, Fort Collins, CO 80523-1870, USA
| | - Helle D. Ulrich
- Institute of Molecular Biology gGmbH, Ackermannweg 4, D-55128 Mainz, Germany
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5
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Sun X, Gao C, Xu X, Li M, Zhao X, Wang Y, Wang Y, Zhang S, Yan Z, Liu X, Wu C. FBL promotes cancer cell resistance to DNA damage and BRCA1 transcription via YBX1. EMBO Rep 2023; 24:e56230. [PMID: 37489617 PMCID: PMC10481664 DOI: 10.15252/embr.202256230] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 06/27/2023] [Accepted: 07/04/2023] [Indexed: 07/26/2023] Open
Abstract
Fibrillarin (FBL) is a highly conserved nucleolar methyltransferase responsible for methylation of ribosomal RNA and proteins. Here, we reveal a role for FBL in DNA damage response and its impact on cancer proliferation and sensitivity to DNA-damaging agents. FBL is highly expressed in various cancers and correlates with poor survival outcomes in cancer patients. Knockdown of FBL sensitizes tumor cells and xenografts to DNA crosslinking agents, and leads to homologous recombination-mediated DNA repair defects. We identify Y-box-binding protein-1 (YBX1) as a key interacting partner of FBL, and FBL increases the nuclear accumulation of YBX1 in response to DNA damage. We show that FBL promotes the expression of BRCA1 by increasing the binding of YBX1 to the BRCA1 promoter. Our study sheds light on the regulatory mechanism of FBL in tumorigenesis and DNA damage response, providing potential therapeutic targets to overcome chemoresistance in cancer.
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Affiliation(s)
- Xiaorui Sun
- College of Life SciencesHebei UniversityBaodingChina
| | - Congwen Gao
- College of Life SciencesHebei UniversityBaodingChina
| | - Xin Xu
- College of Life SciencesHebei UniversityBaodingChina
| | - Mengyuan Li
- College of Life SciencesHebei UniversityBaodingChina
| | - Xinhua Zhao
- College of Life SciencesHebei UniversityBaodingChina
| | - Yanan Wang
- Affiliated Hospital of Hebei UniversityBaodingChina
| | - Yun Wang
- Affiliated Hospital of Hebei UniversityBaodingChina
| | - Shun Zhang
- Affiliated Hospital of Hebei UniversityBaodingChina
| | - Zhenzhen Yan
- College of Life SciencesHebei UniversityBaodingChina
| | - Xiuhua Liu
- College of Life SciencesHebei UniversityBaodingChina
| | - Chen Wu
- College of Life SciencesHebei UniversityBaodingChina
- The Key Laboratory of Zoological Systematics and ApplicationHebei UniversityBaodingChina
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6
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Ismail S, Flemming D, Thoms M, Gomes-Filho JV, Randau L, Beckmann R, Hurt E. Emergence of the primordial pre-60S from the 90S pre-ribosome. Cell Rep 2022; 39:110640. [PMID: 35385737 PMCID: PMC8994135 DOI: 10.1016/j.celrep.2022.110640] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 02/01/2022] [Accepted: 03/16/2022] [Indexed: 01/03/2023] Open
Abstract
Synthesis of ribosomes begins in the nucleolus with formation of the 90S pre-ribosome, during which the pre-40S and pre-60S pathways diverge by pre-rRNA cleavage. However, it remains unclear how, after this uncoupling, the earliest pre-60S subunit continues to develop. Here, we reveal a large-subunit intermediate at the beginning of its construction when still linked to the 90S, the precursor to the 40S subunit. This primordial pre-60S is characterized by the SPOUT domain methyltransferase Upa1-Upa2, large α-solenoid scaffolds, Mak5, one of several RNA helicases, and two small nucleolar RNA (snoRNAs), C/D box snR190 and H/ACA box snR37. The emerging pre-60S does not efficiently disconnect from the 90S pre-ribosome in a dominant mak5 helicase mutant, allowing a 70-nm 90S-pre-60S bipartite particle to be visualized by electron microscopy. Our study provides insight into the assembly pathway when the still-connected nascent 40S and 60S subunits are beginning to separate.
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Affiliation(s)
- Sherif Ismail
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Dirk Flemming
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Matthias Thoms
- Gene Center, Ludwig-Maximilians-Universität München, Feodor-Lynen-Straße 25, 81377 Munich, Germany
| | | | - Lennart Randau
- Philipps-Universität Marburg, Karl-von-Frisch-Str. 8, 35043 Marburg, Germany
| | - Roland Beckmann
- Gene Center, Ludwig-Maximilians-Universität München, Feodor-Lynen-Straße 25, 81377 Munich, Germany.
| | - Ed Hurt
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany.
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7
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Jaafar M, Paraqindes H, Gabut M, Diaz JJ, Marcel V, Durand S. 2'O-Ribose Methylation of Ribosomal RNAs: Natural Diversity in Living Organisms, Biological Processes, and Diseases. Cells 2021; 10:1948. [PMID: 34440717 PMCID: PMC8393311 DOI: 10.3390/cells10081948] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 01/21/2023] Open
Abstract
Recent findings suggest that ribosomes, the translational machineries, can display a distinct composition depending on physio-pathological contexts. Thanks to outstanding technological breakthroughs, many studies have reported that variations of rRNA modifications, and more particularly the most abundant rRNA chemical modification, the rRNA 2'O-ribose methylation (2'Ome), intrinsically occur in many organisms. In the last 5 years, accumulating reports have illustrated that rRNA 2'Ome varies in human cell lines but also in living organisms (yeast, plant, zebrafish, mouse, human) during development and diseases. These rRNA 2'Ome variations occur either within a single cell line, organ, or patient's sample (i.e., intra-variability) or between at least two biological conditions (i.e., inter-variability). Thus, the ribosomes can tolerate the absence of 2'Ome at some specific positions. These observations question whether variations in rRNA 2'Ome could provide ribosomes with particular translational regulatory activities and functional specializations. Here, we compile recent studies supporting the heterogeneity of ribosome composition at rRNA 2'Ome level and provide an overview of the natural diversity in rRNA 2'Ome that has been reported up to now throughout the kingdom of life. Moreover, we discuss the little evidence that suggests that variations of rRNA 2'Ome can effectively impact the ribosome activity and contribute to the etiology of some human diseases.
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Affiliation(s)
| | | | | | | | - Virginie Marcel
- Inserm U1052, CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, Université de Lyon, Université Claude Bernard Lyon 1, Centre Léon Bérard, CEDEX 08, F-69373 Lyon, France; (M.J.); (H.P.); (M.G.); (J.-J.D.)
| | - Sébastien Durand
- Inserm U1052, CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, Université de Lyon, Université Claude Bernard Lyon 1, Centre Léon Bérard, CEDEX 08, F-69373 Lyon, France; (M.J.); (H.P.); (M.G.); (J.-J.D.)
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8
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Falquet B, Ölmezer G, Enkner F, Klein D, Challa K, Appanah R, Gasser SM, Rass U. Disease-associated DNA2 nuclease-helicase protects cells from lethal chromosome under-replication. Nucleic Acids Res 2020; 48:7265-7278. [PMID: 32544229 PMCID: PMC7367196 DOI: 10.1093/nar/gkaa524] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Revised: 05/21/2020] [Accepted: 06/09/2020] [Indexed: 01/28/2023] Open
Abstract
DNA2 is an essential nuclease–helicase implicated in DNA repair, lagging-strand DNA synthesis, and the recovery of stalled DNA replication forks (RFs). In Saccharomyces cerevisiae, dna2Δ inviability is reversed by deletion of the conserved helicase PIF1 and/or DNA damage checkpoint-mediator RAD9. It has been suggested that Pif1 drives the formation of long 5′-flaps during Okazaki fragment maturation, and that the essential function of Dna2 is to remove these intermediates. In the absence of Dna2, 5′-flaps are thought to accumulate on the lagging strand, resulting in DNA damage-checkpoint arrest and cell death. In line with Dna2’s role in RF recovery, we find that the loss of Dna2 results in severe chromosome under-replication downstream of endogenous and exogenous RF-stalling. Importantly, unfaithful chromosome replication in Dna2-mutant cells is exacerbated by Pif1, which triggers the DNA damage checkpoint along a pathway involving Pif1’s ability to promote homologous recombination-coupled replication. We propose that Dna2 fulfils its essential function by promoting RF recovery, facilitating replication completion while suppressing excessive RF restart by recombination-dependent replication (RDR) and checkpoint activation. The critical nature of Dna2’s role in controlling the fate of stalled RFs provides a framework to rationalize the involvement of DNA2 in Seckel syndrome and cancer.
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Affiliation(s)
- Benoît Falquet
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland.,Faculty of Natural Sciences, University of Basel, CH-4056 Basel, Switzerland
| | - Gizem Ölmezer
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland.,Faculty of Natural Sciences, University of Basel, CH-4056 Basel, Switzerland
| | - Franz Enkner
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland
| | - Dominique Klein
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland
| | - Kiran Challa
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland
| | - Rowin Appanah
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RQ, UK
| | - Susan M Gasser
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland.,Faculty of Natural Sciences, University of Basel, CH-4056 Basel, Switzerland
| | - Ulrich Rass
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland.,Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RQ, UK
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9
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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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10
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Srs2 helicase prevents the formation of toxic DNA damage during late prophase I of yeast meiosis. Chromosoma 2019; 128:453-471. [DOI: 10.1007/s00412-019-00709-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 05/07/2019] [Accepted: 05/15/2019] [Indexed: 12/24/2022]
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11
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Szatkowska R, Garcia-Albornoz M, Roszkowska K, Holman SW, Furmanek E, Hubbard SJ, Beynon RJ, Adamczyk M. Glycolytic flux in Saccharomyces cerevisiae is dependent on RNA polymerase III and its negative regulator Maf1. Biochem J 2019; 476:1053-1082. [PMID: 30885983 PMCID: PMC6448137 DOI: 10.1042/bcj20180701] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 03/11/2019] [Accepted: 03/15/2019] [Indexed: 02/07/2023]
Abstract
Protein biosynthesis is energetically costly, is tightly regulated and is coupled to stress conditions including glucose deprivation. RNA polymerase III (RNAP III)-driven transcription of tDNA genes for production of tRNAs is a key element in efficient protein biosynthesis. Here we present an analysis of the effects of altered RNAP III activity on the Saccharomyces cerevisiae proteome and metabolism under glucose-rich conditions. We show for the first time that RNAP III is tightly coupled to the glycolytic system at the molecular systems level. Decreased RNAP III activity or the absence of the RNAP III negative regulator, Maf1 elicit broad changes in the abundance profiles of enzymes engaged in fundamental metabolism in S. cerevisiae In a mutant compromised in RNAP III activity, there is a repartitioning towards amino acids synthesis de novo at the expense of glycolytic throughput. Conversely, cells lacking Maf1 protein have greater potential for glycolytic flux.
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Affiliation(s)
- Roza Szatkowska
- Chair of Drug and Cosmetics Biotechnology, Faculty of Chemistry, Warsaw University of Technology, Warsaw, Poland
| | - Manuel Garcia-Albornoz
- Division of Evolution & Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, U.K
| | - Katarzyna Roszkowska
- Chair of Drug and Cosmetics Biotechnology, Faculty of Chemistry, Warsaw University of Technology, Warsaw, Poland
| | - Stephen W Holman
- Centre for Proteome Research, Institute of Integrative Biology, University of Liverpool, Liverpool, U.K
| | - Emil Furmanek
- Chair of Drug and Cosmetics Biotechnology, Faculty of Chemistry, Warsaw University of Technology, Warsaw, Poland
| | - Simon J Hubbard
- Division of Evolution & Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, U.K
| | - Robert J Beynon
- Centre for Proteome Research, Institute of Integrative Biology, University of Liverpool, Liverpool, U.K
| | - Malgorzata Adamczyk
- Chair of Drug and Cosmetics Biotechnology, Faculty of Chemistry, Warsaw University of Technology, Warsaw, Poland
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12
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Burke MF, McLaurin DM, Logan MK, Hebert MD. Alteration of 28S rRNA 2'- O-methylation by etoposide correlates with decreased SMN phosphorylation and reduced Drosha levels. Biol Open 2019; 8:bio041848. [PMID: 30858166 PMCID: PMC6451326 DOI: 10.1242/bio.041848] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 02/28/2019] [Indexed: 12/15/2022] Open
Abstract
The most common types of modification in human rRNA are pseudouridylation and 2'-O ribose methylation. These modifications are performed by small nucleolar ribonucleoproteins (snoRNPs) which contain a guide RNA (snoRNA) that base pairs at specific sites within the rRNA to direct the modification. rRNA modifications can vary, generating ribosome heterogeneity. One possible method that can be used to regulate rRNA modifications is by controlling snoRNP activity. RNA fragments derived from some small Cajal body-specific RNAs (scaRNA 2, 9 and 17) may influence snoRNP activity. Most scaRNAs accumulate in the Cajal body - a subnuclear domain - where they participate in the biogenesis of small nuclear RNPs, but scaRNA 2, 9 and 17 generate nucleolus-enriched fragments of unclear function, and we hypothesize that these fragments form regulatory RNPs that impact snoRNP activity and modulate rRNA modifications. Our previous work has shown that SMN, Drosha and various stresses, including etoposide treatment, may alter regulatory RNP formation. Here we demonstrate that etoposide treatment decreases the phosphorylation of SMN, reduces Drosha levels and increases the 2'-O-methylation of two sites within 28S rRNA. These findings further support a role for SMN and Drosha in regulating rRNA modification, possibly by affecting snoRNP or regulatory RNP activity.
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Affiliation(s)
- Marilyn F Burke
- Department of Cell and Molecular Biology, The University of Mississippi Medical Center, Jackson, MS 39216-4505, USA
| | - Douglas M McLaurin
- Department of Cell and Molecular Biology, The University of Mississippi Medical Center, Jackson, MS 39216-4505, USA
| | - Madelyn K Logan
- Department of Cell and Molecular Biology, The University of Mississippi Medical Center, Jackson, MS 39216-4505, USA
| | - Michael D Hebert
- Department of Cell and Molecular Biology, The University of Mississippi Medical Center, Jackson, MS 39216-4505, USA
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13
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Logan MK, Burke MF, Hebert MD. Altered dynamics of scaRNA2 and scaRNA9 in response to stress correlates with disrupted nuclear organization. Biol Open 2018; 7:bio.037101. [PMID: 30177550 PMCID: PMC6176948 DOI: 10.1242/bio.037101] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Small Cajal body-specific RNAs (scaRNAs) are part of small Cajal body-specific ribonucleoproteins (scaRNPs) that modify small nuclear RNA (snRNA) in Cajal bodies (CBs). Several scaRNAs (scaRNA 2, 9 and 17) have been found to generate smaller, nucleolus-enriched fragments. We hypothesize that the fragments derived from scaRNA 2, 9 and 17 form regulatory RNPs that influence the level of modifications within rRNA by altering small nucleolar RNP (snoRNP) activity. Here we show that external factors such as DNA damaging agents can alter the scaRNA9 full length to processed fragment ratio. We also show that full-length scaRNA2 levels are likewise impacted by DNA damage, which correlates with the disruption of SMN, coilin and WRAP53 co-localization in CBs. The dynamics of scaRNA9 were also shown to be affected by Drosha levels, which suggests that this protein may participate in the biogenesis and processing of this non-coding RNA. Identification of factors that contribute to scaRNA 2, 9 and 17 processing may facilitate an assessment of how external stress can lead to changes in rRNA modifications.
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Affiliation(s)
- Madelyn K Logan
- Department of Cell and Molecular Biology, The University of Mississippi Medical Center, Jackson, MS 39216-4505, USA
| | - Marilyn F Burke
- Department of Cell and Molecular Biology, The University of Mississippi Medical Center, Jackson, MS 39216-4505, USA
| | - Michael D Hebert
- Department of Cell and Molecular Biology, The University of Mississippi Medical Center, Jackson, MS 39216-4505, USA
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14
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Lykke-Andersen S, Ardal BK, Hollensen AK, Damgaard CK, Jensen TH. Box C/D snoRNP Autoregulation by a cis-Acting snoRNA in the NOP56 Pre-mRNA. Mol Cell 2018; 72:99-111.e5. [PMID: 30220559 DOI: 10.1016/j.molcel.2018.08.017] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 06/18/2018] [Accepted: 08/09/2018] [Indexed: 01/23/2023]
Abstract
Box C/D snoRNAs constitute a class of abundant noncoding RNAs that associate with common core proteins to form catalytic snoRNPs. Most of these operate in trans to assist the maturation of rRNAs by guiding and catalyzing the 2'-O-methylation of specific nucleotides. Here, we report that the human intron-hosted box C/D snoRNA snoRD86 acts in cis as a sensor and master switch controlling levels of the limiting snoRNP core protein NOP56, which is important for proper ribosome biogenesis. Our results support a model in which snoRD86 adopts different RNP conformations that dictate the usage of nearby alternative splice donors in the NOP56 pre-mRNA. Excess snoRNP core proteins prevent further production of NOP56 and instead trigger the generation of a cytoplasmic snoRD86-containing NOP56-derived lncRNA via the nonsense-mediated decay pathway. Our findings reveal a feedback mechanism based on RNA structure that controls the precise coordination between box C/D snoRNP core proteins and global snoRNA levels.
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Affiliation(s)
- Søren Lykke-Andersen
- Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Allé 3, 8000 Aarhus C, Denmark.
| | - Britt Kidmose Ardal
- Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Allé 3, 8000 Aarhus C, Denmark
| | - Anne Kruse Hollensen
- Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Allé 3, 8000 Aarhus C, Denmark
| | - Christian Kroun Damgaard
- Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Allé 3, 8000 Aarhus C, Denmark
| | - Torben Heick Jensen
- Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Allé 3, 8000 Aarhus C, Denmark.
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15
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Leighton LJ, Bredy TW. Functional Interplay between Small Non-Coding RNAs and RNA Modification in the Brain. Noncoding RNA 2018; 4:E15. [PMID: 29880782 PMCID: PMC6027130 DOI: 10.3390/ncrna4020015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 05/23/2018] [Accepted: 05/30/2018] [Indexed: 12/11/2022] Open
Abstract
Small non-coding RNAs are essential for transcription, translation and gene regulation in all cell types, but are particularly important in neurons, with known roles in neurodevelopment, neuroplasticity and neurological disease. Many small non-coding RNAs are directly involved in the post-transcriptional modification of other RNA species, while others are themselves substrates for modification, or are functionally modulated by modification of their target RNAs. In this review, we explore the known and potential functions of several distinct classes of small non-coding RNAs in the mammalian brain, focusing on the newly recognised interplay between the epitranscriptome and the activity of small RNAs. We discuss the potential for this relationship to influence the spatial and temporal dynamics of gene activation in the brain, and predict that further research in the field of epitranscriptomics will identify interactions between small RNAs and RNA modifications which are essential for higher order brain functions such as learning and memory.
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Affiliation(s)
- Laura J Leighton
- Cognitive Neuroepigenetics Laboratory, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
| | - Timothy W Bredy
- Cognitive Neuroepigenetics Laboratory, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
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16
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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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17
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Kamal KY, Herranz R, van Loon JJWA, Medina FJ. Simulated microgravity, Mars gravity, and 2g hypergravity affect cell cycle regulation, ribosome biogenesis, and epigenetics in Arabidopsis cell cultures. Sci Rep 2018; 8:6424. [PMID: 29686401 PMCID: PMC5913308 DOI: 10.1038/s41598-018-24942-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 04/13/2018] [Indexed: 01/09/2023] Open
Abstract
Gravity is the only component of Earth environment that remained constant throughout the entire process of biological evolution. However, it is still unclear how gravity affects plant growth and development. In this study, an in vitro cell culture of Arabidopsis thaliana was exposed to different altered gravity conditions, namely simulated reduced gravity (simulated microgravity, simulated Mars gravity) and hypergravity (2g), to study changes in cell proliferation, cell growth, and epigenetics. The effects after 3, 14, and 24-hours of exposure were evaluated. The most relevant alterations were found in the 24-hour treatment, being more significant for simulated reduced gravity than hypergravity. Cell proliferation and growth were uncoupled under simulated reduced gravity, similarly, as found in meristematic cells from seedlings grown in real or simulated microgravity. The distribution of cell cycle phases was changed, as well as the levels and gene transcription of the tested cell cycle regulators. Ribosome biogenesis was decreased, according to levels and gene transcription of nucleolar proteins and the number of inactive nucleoli. Furthermore, we found alterations in the epigenetic modifications of chromatin. These results show that altered gravity effects include a serious disturbance of cell proliferation and growth, which are cellular functions essential for normal plant development.
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Affiliation(s)
- Khaled Y Kamal
- Agronomy Department, Faculty of Agriculture, Zagazig University, Zagazig, Egypt. .,Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040, Madrid, Spain.
| | - Raúl Herranz
- Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Jack J W A van Loon
- DESC (Dutch Experiment Support Center), Dept. Oral and Maxillofacial Surgery/Oral Pathology, VU University Medical Center & Academic Centre for Dentistry Amsterdam (ACTA), Gustav Mahlerlaan 3004, 1081 LA, Amsterdam, The Netherlands.,ESA-ESTEC, TEC-MMG, Keplerlaan 1, NL-2200 AG, Noordwijk, The Netherlands
| | - F Javier Medina
- Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040, Madrid, Spain
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18
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Bouffard S, Dambroise E, Brombin A, Lempereur S, Hatin I, Simion M, Corre R, Bourrat F, Joly JS, Jamen F. Fibrillarin is essential for S-phase progression and neuronal differentiation in zebrafish dorsal midbrain and retina. Dev Biol 2018; 437:1-16. [PMID: 29477341 DOI: 10.1016/j.ydbio.2018.02.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 01/11/2018] [Accepted: 02/13/2018] [Indexed: 10/18/2022]
Abstract
Fibrillarin (Fbl) is a highly conserved protein that plays an essential role in ribosome biogenesis and more particularly in the methylation of ribosomal RNAs and rDNA histones. In cellular models, FBL was shown to play an important role in tumorigenesis and stem cell differentiation. We used the zebrafish as an in vivo model to study Fbl function during embryonic development. We show here that the optic tectum and the eye are severely affected by Fbl depletion whereas ventral regions of the brain are less impacted. The morphogenesis defects are associated with impaired neural differentiation and massive apoptosis. Polysome gradient experiments show that fbl mutant larvae display defects in ribosome biogenesis and activity. Strikingly, flow cytometry analyses revealed different S-phase profiles between wild-type and mutant cells, suggesting a defect in S-phase progression.
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Affiliation(s)
- Stéphanie Bouffard
- INRA CASBAH Group, Neurosciences Paris-Saclay Institute, CNRS, Université Paris-Saclay, Université Paris-Sud, Gif-sur-Yvette, France
| | - Emilie Dambroise
- INRA CASBAH Group, Neurosciences Paris-Saclay Institute, CNRS, Université Paris-Saclay, Université Paris-Sud, Gif-sur-Yvette, France
| | - Alessandro Brombin
- INRA CASBAH Group, Neurosciences Paris-Saclay Institute, CNRS, Université Paris-Saclay, Université Paris-Sud, Gif-sur-Yvette, France
| | - Sylvain Lempereur
- Tefor Core Facility, TEFOR Infrastructure, NeuroPSI, CNRS, Gif-sur-Yvette, France; Université Paris-Est, LIGM, ESIEE, Noisy-le-Grand, France
| | - Isabelle Hatin
- Institut de Biologie Intégrative de la Cellule (I2BC), CEA, CNRS, Université Paris-Sud, Bâtiment 400, 91400 Orsay, France
| | - Matthieu Simion
- INRA CASBAH Group, Neurosciences Paris-Saclay Institute, CNRS, Université Paris-Saclay, Université Paris-Sud, Gif-sur-Yvette, France
| | - Raphaël Corre
- INRA CASBAH Group, Neurosciences Paris-Saclay Institute, CNRS, Université Paris-Saclay, Université Paris-Sud, Gif-sur-Yvette, France
| | - Franck Bourrat
- INRA CASBAH Group, Neurosciences Paris-Saclay Institute, CNRS, Université Paris-Saclay, Université Paris-Sud, Gif-sur-Yvette, France
| | - Jean-Stéphane Joly
- INRA CASBAH Group, Neurosciences Paris-Saclay Institute, CNRS, Université Paris-Saclay, Université Paris-Sud, Gif-sur-Yvette, France; Tefor Core Facility, TEFOR Infrastructure, NeuroPSI, CNRS, Gif-sur-Yvette, France
| | - Françoise Jamen
- INRA CASBAH Group, Neurosciences Paris-Saclay Institute, CNRS, Université Paris-Saclay, Université Paris-Sud, Gif-sur-Yvette, France.
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19
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Nakamura TS, Numajiri Y, Okumura Y, Hidaka J, Tanaka T, Inoue I, Suda Y, Takahashi T, Nakanishi H, Gao XD, Neiman AM, Tachikawa H. Dynamic localization of a yeast development-specific PP1 complex during prospore membrane formation is dependent on multiple localization signals and complex formation. Mol Biol Cell 2017; 28:3881-3895. [PMID: 29046399 PMCID: PMC5739302 DOI: 10.1091/mbc.e17-08-0521] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 10/06/2017] [Accepted: 10/10/2017] [Indexed: 12/27/2022] Open
Abstract
Prospore membrane formation of Saccharomyces cerevisiae provides a powerful model for understanding the mechanisms of de novo membrane formation. Protein phosphatase type1, Glc7, and a sporulation-specific targeting subunit, Gip1, show dynamic localization using multiple localization signals and regulate membrane growth during sporulation. During the developmental process of sporulation in Saccharomyces cerevisiae, membrane structures called prospore membranes are formed de novo, expand, extend, acquire a round shape, and finally become plasma membranes of the spores. GIP1 encodes a regulatory/targeting subunit of protein phosphatase type 1 that is required for sporulation. Gip1 recruits the catalytic subunit Glc7 to septin structures that form along the prospore membrane; however, the molecular basis of its localization and function is not fully understood. Here we show that Gip1 changes its localization dynamically and is required for prospore membrane extension. Gip1 first associates with the spindle pole body as the prospore membrane forms, moves onto the prospore membrane and then to the septins as the membrane extends, distributes around the prospore membrane after closure, and finally translocates into the nucleus in the maturing spore. Deletion and mutation analyses reveal distinct sequences in Gip1 that are required for different localizations and for association with Glc7. Binding to Glc7 is also required for proper localization. Strikingly, localization to the prospore membrane, but not association with septins, is important for Gip1 function. Further, our genetic analysis suggests that a Gip1–Glc7 phosphatase complex regulates prospore membrane extension in parallel to the previously reported Vps13, Spo71, Spo73 pathway.
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Affiliation(s)
- Tsuyoshi S Nakamura
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Yumi Numajiri
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Yuuya Okumura
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Junji Hidaka
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Takayuki Tanaka
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Ichiro Inoue
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Yasuyuki Suda
- Department of Molecular Cell Biology, Graduate School of Comprehensive Human Sciences and Institute of Basic Medical Sciences, University of Tsukuba, Ibaraki 305-8575, Japan
| | - Tetsuo Takahashi
- Laboratory of Glycobiology and Glycotechnology, Department of Applied Biochemistry, School of Engineering, Tokai University, Kanagawa 259-1292, Japan
| | - Hideki Nakanishi
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Xiao-Dong Gao
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Aaron M Neiman
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215
| | - Hiroyuki Tachikawa
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
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20
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Poole AR, Vicino I, Adachi H, Yu YT, Hebert MD. Regulatory RNPs: a novel class of ribonucleoproteins that potentially contribute to ribosome heterogeneity. Biol Open 2017; 6:1342-1354. [PMID: 28808137 PMCID: PMC5612246 DOI: 10.1242/bio.028092] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Many ribonucleoproteins (RNPs), which are comprised of noncoding RNA and associated proteins, are involved in essential cellular processes such as translation and pre-mRNA splicing. One class of RNP is the small Cajal body-specific RNP (scaRNP), which contributes to the biogenesis of small nuclear RNPs (snRNPs) that are central components of the spliceosome. Three scaRNAs are internally processed, generating stable nucleolus-enriched RNAs of unknown function. Here, we provide data that show that these RNAs become part of RNPs we term regulatory RNPs (regRNPs). Most modifications within rRNA (predominantly pseudouridylation and ribose 2′-O-methylation) are conducted by small nucleolar RNPs (snoRNPs), and we provide evidence that the activity of at least some of these snoRNPs is under the control of regRNPs. Because modifications within rRNA can vary in different physiological or pathological situations, rRNA modifications are thought to be the major source of ribosome heterogeneity. Our identification of regRNPs thus provides a potential mechanism for how ribosome heterogeneity may be accomplished. This work also provides additional functional connections between the Cajal body and the nucleolus. Summary: Processed scaRNAs give rise to a novel regulatory RNP, which regulates the modification of ribosomal RNA. These findings provide insight into the mechanisms governing ribosome heterogeneity.
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Affiliation(s)
- Aaron R Poole
- Department of Biochemistry, The University of Mississippi Medical Center, Jackson, MS 39216-4505, USA
| | - Ian Vicino
- Department of Biochemistry, The University of Mississippi Medical Center, Jackson, MS 39216-4505, USA
| | - Hironori Adachi
- Department of Biochemistry and Biophysics, The University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Yi-Tao Yu
- Department of Biochemistry and Biophysics, The University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Michael D Hebert
- Department of Biochemistry, The University of Mississippi Medical Center, Jackson, MS 39216-4505, USA
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21
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Principles of 60S ribosomal subunit assembly emerging from recent studies in yeast. Biochem J 2017; 474:195-214. [PMID: 28062837 DOI: 10.1042/bcj20160516] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 11/22/2016] [Accepted: 11/24/2016] [Indexed: 12/31/2022]
Abstract
Ribosome biogenesis requires the intertwined processes of folding, modification, and processing of ribosomal RNA, together with binding of ribosomal proteins. In eukaryotic cells, ribosome assembly begins in the nucleolus, continues in the nucleoplasm, and is not completed until after nascent particles are exported to the cytoplasm. The efficiency and fidelity of ribosome biogenesis are facilitated by >200 assembly factors and ∼76 different small nucleolar RNAs. The pathway is driven forward by numerous remodeling events to rearrange the ribonucleoprotein architecture of pre-ribosomes. Here, we describe principles of ribosome assembly that have emerged from recent studies of biogenesis of the large ribosomal subunit in the yeast Saccharomyces cerevisiae We describe tools that have empowered investigations of ribosome biogenesis, and then summarize recent discoveries about each of the consecutive steps of subunit assembly.
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22
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Henras AK, Plisson-Chastang C, Humbert O, Romeo Y, Henry Y. Synthesis, Function, and Heterogeneity of snoRNA-Guided Posttranscriptional Nucleoside Modifications in Eukaryotic Ribosomal RNAs. Enzymes 2017; 41:169-213. [PMID: 28601222 DOI: 10.1016/bs.enz.2017.03.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Ribosomal RNAs contain numerous 2'-O-methylated nucleosides and pseudouridines. Methylation of the 2' oxygen of ribose moieties and isomerization of uridines into pseudouridines are catalyzed by C/D and H/ACA small nucleolar ribonucleoprotein particles, respectively. We review the composition, structure, and mode of action of archaeal and eukaryotic C/D and H/ACA particles. Most rRNA modifications cluster in functionally crucial regions of the rRNAs, suggesting they play important roles in translation. Some of these modifications promote global translation efficiency or modulate translation fidelity. Strikingly, recent quantitative nucleoside modification profiling methods have revealed that a subset of modification sites is not always fully modified. The finding of such ribosome heterogeneity is in line with the concept of specialized ribosomes that could preferentially translate specific mRNAs. This emerging concept is supported by findings that some human diseases are caused by defects in the rRNA modification machinery correlated with a significant alteration of IRES-dependent translation.
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Affiliation(s)
- Anthony K Henras
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, Toulouse, France.
| | - Célia Plisson-Chastang
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Odile Humbert
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Yves Romeo
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Yves Henry
- Laboratoire de Biologie Moléculaire Eucaryote, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, Toulouse, France.
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23
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Hebert MD, Poole AR. Towards an understanding of regulating Cajal body activity by protein modification. RNA Biol 2016; 14:761-778. [PMID: 27819531 DOI: 10.1080/15476286.2016.1243649] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The biogenesis of small nuclear ribonucleoproteins (snRNPs), small Cajal body-specific RNPs (scaRNPs), small nucleolar RNPs (snoRNPs) and the telomerase RNP involves Cajal bodies (CBs). Although many components enriched in the CB contain post-translational modifications (PTMs), little is known about how these modifications impact individual protein function within the CB and, in concert with other modified factors, collectively regulate CB activity. Since all components of the CB also reside in other cellular locations, it is also important that we understand how PTMs affect the subcellular localization of CB components. In this review, we explore the current knowledge of PTMs on the activity of proteins known to enrich in CBs in an effort to highlight current progress as well as illuminate paths for future investigation.
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Affiliation(s)
- Michael D Hebert
- a Department of Biochemistry , The University of Mississippi Medical Center , Jackson , MS , USA
| | - Aaron R Poole
- a Department of Biochemistry , The University of Mississippi Medical Center , Jackson , MS , USA
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24
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Abstract
Box C/D RNAs guide site-specific 2'-O-methylation of RNAs in archaea and eukaryotes. The spacer regions between boxes C to D' and boxes C' to D contain the guide sequence that can form a stretch of base pairs with substrate RNAs. The lengths of spacer regions and guide-substrate duplexes are variable among C/D RNAs. In a previously determined structure of C/D ribonucleoprotein (RNP), a 12-nt-long spacer forms 10 bp with the substrate. How spacers and guide-substrate duplexes of other lengths are accommodated remains unknown. Here we analyze how the lengths of spacers and guide-substrate duplexes affect the modification activity and determine three structures of C/D RNPs assembled with different spacers and substrates. We show that the guide can only form a duplex of a maximum of 10 bp with the substrate during modification. Slightly shorter duplexes are tolerated, but longer duplexes must be unwound to fit into a capped protein channel for modification. Spacers with <12 nucleotides are defective, mainly because they cannot load the substrate in the active conformation. For spacers with >12 nucleotides, the excessive unpaired sequences near the box C/C' side are looped out. Our results provide insight into the substrate recognition mechanism of C/D RNA and refute the RNA-swapped model for dimeric C/D RNP.
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Affiliation(s)
- Zuxiao Yang
- College of Biological Sciences, China Agricultural University, Beijing 100193, China; National Institute of Biological Sciences, Beijing 102206, China; Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; Beijing Key Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Jinzhong Lin
- National Institute of Biological Sciences, Beijing 102206, China
| | - Keqiong Ye
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; Beijing Key Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
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25
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Shubina MY, Musinova YR, Sheval EV. Nucleolar methyltransferase fibrillarin: Evolution of structure and functions. BIOCHEMISTRY (MOSCOW) 2016; 81:941-50. [DOI: 10.1134/s0006297916090030] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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26
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Regulation of a Spindle Positioning Factor at Kinetochores by SUMO-Targeted Ubiquitin Ligases. Dev Cell 2016; 36:415-27. [PMID: 26906737 DOI: 10.1016/j.devcel.2016.01.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 12/04/2015] [Accepted: 01/14/2016] [Indexed: 12/17/2022]
Abstract
Correct function of the mitotic spindle requires balanced interplay of kinetochore and astral microtubules that mediate chromosome segregation and spindle positioning, respectively. Errors therein can cause severe defects ranging from aneuploidy to developmental disorders. Here, we describe a protein degradation pathway that functionally links astral microtubules to kinetochores via regulation of a microtubule-associated factor. We show that the yeast spindle positioning protein Kar9 localizes not only to astral but also to kinetochore microtubules, where it becomes targeted for proteasomal degradation by the SUMO-targeted ubiquitin ligases (STUbLs) Slx5-Slx8. Intriguingly, this process does not depend on preceding sumoylation of Kar9 but rather requires SUMO-dependent recruitment of STUbLs to kinetochores. Failure to degrade Kar9 leads to defects in both chromosome segregation and spindle positioning. We propose that kinetochores serve as platforms to recruit STUbLs in a SUMO-dependent manner in order to ensure correct spindle function by regulating levels of microtubule-associated proteins.
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27
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Martins JR, Bitondi MMG. The HEX 110 Hexamerin Is a Cytoplasmic and Nucleolar Protein in the Ovaries of Apis mellifera. PLoS One 2016; 11:e0151035. [PMID: 26954256 PMCID: PMC4783013 DOI: 10.1371/journal.pone.0151035] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 02/10/2016] [Indexed: 11/21/2022] Open
Abstract
Hexamerins are insect storage proteins abundantly secreted by the larval fat body into the haemolymph. The canonical role of hexamerins consists of serving as an amino acid reserve for development toward the adult stage. However, in Apis mellifera, immunofluorescence assays coupled to confocal laser-scanning microscopy, and high-throughput sequencing, have recently shown the presence of hexamerins in other organs than the fat body. These findings have led us to study these proteins with the expectation of uncovering additional functions in insect development. We show here that a honeybee hexamerin, HEX 110, localizes in the cytoplasm and nucleus of ovarian cells. In the nucleus of somatic and germline cells, HEX 110 colocalized with a nucleolar protein, fibrillarin, suggesting a structural or even regulatory function in the nucleolus. RNase A provoked the loss of HEX 110 signals in the ovarioles, indicating that the subcellular localization depends on RNA. This was reinforced by incubating ovaries with pyronin Y, a RNA-specific dye. Together, the colocalization with fibrillarin and pyronin Y, and the sensitivity to RNase, highlight unprecedented roles for HEX110 in the nucleolus, the nuclear structure harbouring the gene cluster involved in ribosomal RNA production. However, the similar patterns of HEX 110 foci distribution in the active and inactive ovaries of queens and workers preclude its association with the functional status of these organs.
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Affiliation(s)
- Juliana Ramos Martins
- Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Monte Alegre, Ribeirão Preto, São Paulo, Brazil
| | - Márcia Maria Gentile Bitondi
- Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Monte Alegre, Ribeirão Preto, São Paulo, Brazil
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28
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Falahati H, Pelham-Webb B, Blythe S, Wieschaus E. Nucleation by rRNA Dictates the Precision of Nucleolus Assembly. Curr Biol 2016; 26:277-85. [PMID: 26776729 PMCID: PMC5866055 DOI: 10.1016/j.cub.2015.11.065] [Citation(s) in RCA: 129] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 10/27/2015] [Accepted: 11/25/2015] [Indexed: 02/05/2023]
Abstract
Membrane-less organelles are intracellular compartments specialized to carry out specific cellular functions. There is growing evidence supporting the possibility that such organelles form as a new phase, separating from cytoplasm or nucleoplasm. However, a main challenge to such phase separation models is that the initial assembly, or nucleation, of the new phase is typically a highly stochastic process and does not allow for the spatiotemporal precision observed in biological systems. Here, we investigate the initial assembly of the nucleolus, a membrane-less organelle involved in different cellular functions including ribosomal biogenesis. We demonstrate that the nucleolus formation is precisely timed in D. melanogaster embryos and follows the transcription of rRNA. We provide evidence that transcription of rRNA is necessary for overcoming the highly stochastic nucleation step in the formation of the nucleolus, through a seeding mechanism. In the absence of rDNA, the nucleolar proteins studied are able to form high-concentration assemblies. However, unlike the nucleolus, these assemblies are highly variable in number, location, and time at which they form. In addition, quantitative study of the changes in the nucleoplasmic concentration and distribution of these nucleolar proteins in the wild-type embryos is consistent with the role of rRNA in seeding the nucleolus formation.
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Affiliation(s)
- Hanieh Falahati
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Bobbie Pelham-Webb
- Weill Cornell/Rockefeller/Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY 10065, USA
| | - Shelby Blythe
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA; Howard Hughes Medical Institute, Princeton University, Princeton, NJ 08544, USA
| | - Eric Wieschaus
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA; Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA; Howard Hughes Medical Institute, Princeton University, Princeton, NJ 08544, USA.
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29
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Top2 and Sgs1-Top3 Act Redundantly to Ensure rDNA Replication Termination. PLoS Genet 2015; 11:e1005697. [PMID: 26630413 PMCID: PMC4668019 DOI: 10.1371/journal.pgen.1005697] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 11/02/2015] [Indexed: 11/19/2022] Open
Abstract
Faithful DNA replication with correct termination is essential for genome stability and transmission of genetic information. Here we have investigated the potential roles of Topoisomerase II (Top2) and the RecQ helicase Sgs1 during late stages of replication. We find that cells lacking Top2 and Sgs1 (or Top3) display two different characteristics during late S/G2 phase, checkpoint activation and accumulation of asymmetric X-structures, which are both independent of homologous recombination. Our data demonstrate that checkpoint activation is caused by a DNA structure formed at the strongest rDNA replication fork barrier (RFB) during replication termination, and consistently, checkpoint activation is dependent on the RFB binding protein, Fob1. In contrast, asymmetric X-structures are formed independent of Fob1 at less strong rDNA replication fork barriers. However, both checkpoint activation and formation of asymmetric X-structures are sensitive to conditions, which facilitate fork merging and progression of replication forks through replication fork barriers. Our data are consistent with a redundant role of Top2 and Sgs1 together with Top3 (Sgs1-Top3) in replication fork merging at rDNA barriers. At RFB either Top2 or Sgs1-Top3 is essential to prevent formation of a checkpoint activating DNA structure during termination, but at less strong rDNA barriers absence of the enzymes merely delays replication fork merging, causing an accumulation of asymmetric termination structures, which are solved over time. Replication termination is the final step of the replication process, where the two replication forks converge and finally merge to form fully replicated sister chromatids. During this process topological strain in the form of DNA overwinding is generated between forks, and if not removed this strain will inhibit replication of the remaining DNA and thus faithful termination. In this study, we demonstrate that the cell has two redundant pathways to overcome topological problems during rDNA replication termination, one involving Top2 and the other involving the RecQ helicase Sgs1, in concert with Top3. In the absence of both pathways a checkpoint is activated in late S/G2 phase due to faulty replication termination at the strongest rDNA replication fork barrier (RFB). At less strong barriers termination is merely delayed under these conditions resulting in an accumulation of termination X-structures, which are solved over time.
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30
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Watanabe-Susaki K, Takada H, Enomoto K, Miwata K, Ishimine H, Intoh A, Ohtaka M, Nakanishi M, Sugino H, Asashima M, Kurisaki A. Biosynthesis of ribosomal RNA in nucleoli regulates pluripotency and differentiation ability of pluripotent stem cells. Stem Cells 2015; 32:3099-111. [PMID: 25187421 DOI: 10.1002/stem.1825] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 07/23/2014] [Indexed: 01/28/2023]
Abstract
Pluripotent stem cells have been shown to have unique nuclear properties, for example, hyperdynamic chromatin and large, condensed nucleoli. However, the contribution of the latter unique nucleolar character to pluripotency has not been well understood. Here, we show that fibrillarin (FBL), a critical methyltransferase for ribosomal RNA (rRNA) processing in nucleoli, is one of the proteins highly expressed in pluripotent embryonic stem (ES) cells. Stable expression of FBL in ES cells prolonged the pluripotent state of mouse ES cells cultured in the absence of leukemia inhibitory factor (LIF). Analyses using deletion mutants and a point mutant revealed that the methyltransferase activity of FBL regulates stem cell pluripotency. Knockdown of this gene led to significant delays in rRNA processing, growth inhibition, and apoptosis in mouse ES cells. Interestingly, both partial knockdown of FBL and treatment with actinomycin D, an inhibitor of rRNA synthesis, induced the expression of differentiation markers in the presence of LIF and promoted stem cell differentiation into neuronal lineages. Moreover, we identified p53 signaling as the regulatory pathway for pluripotency and differentiation of ES cells. These results suggest that proper activity of rRNA production in nucleoli is a novel factor for the regulation of pluripotency and differentiation ability of ES cells.
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Affiliation(s)
- Kanako Watanabe-Susaki
- Research Center for Stem Cell Engineering, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1, Tsukuba, Ibaraki, Japan
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31
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Rodriguez-Corona U, Sobol M, Rodriguez-Zapata LC, Hozak P, Castano E. Fibrillarin from Archaea to human. Biol Cell 2015; 107:159-74. [PMID: 25772805 DOI: 10.1111/boc.201400077] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 03/05/2015] [Indexed: 12/19/2022]
Abstract
Fibrillarin is an essential protein that is well known as a molecular marker of transcriptionally active RNA polymerase I. Fibrillarin methyltransferase activity is the primary known source of methylation for more than 100 methylated sites involved in the first steps of preribosomal processing and required for structural ribosome stability. High expression levels of fibrillarin have been observed in several types of cancer cells, particularly when p53 levels are reduced, because p53 is a direct negative regulator of fibrillarin transcription. Here, we show fibrillarin domain conservation, structure and interacting molecules in different cellular processes as well as with several viral proteins during virus infection.
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Affiliation(s)
- Ulises Rodriguez-Corona
- Unidad de Bioquímica y Biología molecular de plantas, Centro de Investigación Científica de Yucatán, Colonia Chuburná de Hidalgo, Mérida, Yucatan, Mexico
| | - Margarita Sobol
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Academy of Sciences of the Czech Republic, Prague 14220, Czech Republic
| | - Luis Carlos Rodriguez-Zapata
- Unidad de Biotecnología, Centro de Investigación Científica de Yucatán, Colonia Chuburná de Hidalgo, Mérida, Yucatan, Mexico
| | - Pavel Hozak
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Academy of Sciences of the Czech Republic, Prague 14220, Czech Republic
| | - Enrique Castano
- Unidad de Bioquímica y Biología molecular de plantas, Centro de Investigación Científica de Yucatán, Colonia Chuburná de Hidalgo, Mérida, Yucatan, Mexico
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32
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Stępiński D. Functional ultrastructure of the plant nucleolus. PROTOPLASMA 2014; 251:1285-306. [PMID: 24756369 PMCID: PMC4209244 DOI: 10.1007/s00709-014-0648-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 04/08/2014] [Indexed: 05/23/2023]
Abstract
Nucleoli are nuclear domains present in almost all eukaryotic cells. They not only specialize in the production of ribosomal subunits but also play roles in many fundamental cellular activities. Concerning ribosome biosynthesis, particular stages of this process, i.e., ribosomal DNA transcription, primary RNA transcript processing, and ribosome assembly proceed in precisely defined nucleolar subdomains. Although eukaryotic nucleoli are conservative in respect of their main function, clear morphological differences between these structures can be noticed between individual kingdoms. In most cases, a plant nucleolus shows well-ordered structure in which four main ultrastructural components can be distinguished: fibrillar centers, dense fibrillar component, granular component, and nucleolar vacuoles. Nucleolar chromatin is an additional crucial structural component of this organelle. Nucleolonema, although it is not always an unequivocally distinguished nucleolar domain, has often been described as a well-grounded morphological element, especially of plant nucleoli. The ratios and morphology of particular subcompartments of a nucleolus can change depending on its metabolic activity which in turn is correlated with the physiological state of a cell, cell type, cell cycle phase, as well as with environmental influence. Precise attribution of functions to particular nucleolar subregions in the process of ribosome biosynthesis is now possible using various approaches. The presented description of plant nucleolar morphology summarizes previous knowledge regarding the function of nucleoli as well as of their particular subdomains not only in the course of ribosome biosynthesis.
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Affiliation(s)
- Dariusz Stępiński
- Department of Cytophysiology, Faculty of Biology and Environmental Protection, University of Łódź, Pomorska 141/143, 90-236, Łódź, Poland,
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33
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An RNAi-based suppressor screen identifies interactors of the Myt1 ortholog of Caenorhabditis elegans. G3-GENES GENOMES GENETICS 2014; 4:2329-43. [PMID: 25298536 PMCID: PMC4267929 DOI: 10.1534/g3.114.013649] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Oocyte maturation in all species is controlled by a protein complex termed the maturation promoting factor (MPF). MPF comprises a cyclin-dependent kinase (CDK) and its partner cyclin, and it is regulated by dueling regulatory phosphorylation events on the CDK. In Caenorhabditis elegans, the Wee1/Myt1 ortholog WEE-1.3 provides the inhibitory phosphorylations on CDK-1 that keep MPF inactive and halt meiosis. Prior work has shown that depletion of WEE-1.3 in C. elegans results in precocious oocyte maturation in vivo and a highly penetrant infertility phenotype. This study sought to further define the precocious maturation phenotype and to identify novel interactors with WEE-1.3. We found that WEE-1.3 is expressed throughout the germline and in developing embryos in a perinuclear pattern, and demonstrated that oocytes in WEE-1.3–depleted germlines have begun to transcribe embryonic genes and exhibit inappropriate expression of proteins normally restricted to fertilized eggs. In addition, we performed an RNAi suppressor screen of the infertile phenotype to identify novel factors that, when co-depleted with WEE-1.3, restore fertility to these animals. We screened ∼1900 essential genes by RNAi feeding and identified 44 (∼2% of the tested genes) that are suppressors of the WEE-1.3 depletion phenotype. The suppressors include many previously unidentified players in the meiotic cell cycle and represent a pool of potential WEE-1.3 interacting proteins that function during C. elegans oocyte maturation and zygotic development.
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34
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Woolford JL, Baserga SJ. Ribosome biogenesis in the yeast Saccharomyces cerevisiae. Genetics 2013; 195:643-81. [PMID: 24190922 PMCID: PMC3813855 DOI: 10.1534/genetics.113.153197] [Citation(s) in RCA: 546] [Impact Index Per Article: 49.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 08/26/2013] [Indexed: 01/09/2023] Open
Abstract
Ribosomes are highly conserved ribonucleoprotein nanomachines that translate information in the genome to create the proteome in all cells. In yeast these complex particles contain four RNAs (>5400 nucleotides) and 79 different proteins. During the past 25 years, studies in yeast have led the way to understanding how these molecules are assembled into ribosomes in vivo. Assembly begins with transcription of ribosomal RNA in the nucleolus, where the RNA then undergoes complex pathways of folding, coupled with nucleotide modification, removal of spacer sequences, and binding to ribosomal proteins. More than 200 assembly factors and 76 small nucleolar RNAs transiently associate with assembling ribosomes, to enable their accurate and efficient construction. Following export of preribosomes from the nucleus to the cytoplasm, they undergo final stages of maturation before entering the pool of functioning ribosomes. Elaborate mechanisms exist to monitor the formation of correct structural and functional neighborhoods within ribosomes and to destroy preribosomes that fail to assemble properly. Studies of yeast ribosome biogenesis provide useful models for ribosomopathies, diseases in humans that result from failure to properly assemble ribosomes.
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Affiliation(s)
- John L. Woolford
- Department of Biological Sciences, Center for Nucleic Acids Science and Technology, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
| | - Susan J. Baserga
- Molecular Biophysics and Biochemistry, Genetics and Therapeutic Radiology, Yale University, New Haven, Connecticut 06520-8024
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35
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Lapinaite A, Simon B, Skjaerven L, Rakwalska-Bange M, Gabel F, Carlomagno T. The structure of the box C/D enzyme reveals regulation of RNA methylation. Nature 2013; 502:519-23. [PMID: 24121435 DOI: 10.1038/nature12581] [Citation(s) in RCA: 132] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 08/19/2013] [Indexed: 12/18/2022]
Abstract
Post-transcriptional modifications are essential to the cell life cycle, as they affect both pre-ribosomal RNA processing and ribosome assembly. The box C/D ribonucleoprotein enzyme that methylates ribosomal RNA at the 2'-O-ribose uses a multitude of guide RNAs as templates for the recognition of rRNA target sites. Two methylation guide sequences are combined on each guide RNA, the significance of which has remained unclear. Here we use a powerful combination of NMR spectroscopy and small-angle neutron scattering to solve the structure of the 390 kDa archaeal RNP enzyme bound to substrate RNA. We show that the two methylation guide sequences are located in different environments in the complex and that the methylation of physiological substrates targeted by the same guide RNA occurs sequentially. This structure provides a means for differential control of methylation levels at the two sites and at the same time offers an unexpected regulatory mechanism for rRNA folding.
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MESH Headings
- Apoproteins/chemistry
- Apoproteins/metabolism
- Archaeal Proteins/chemistry
- Archaeal Proteins/metabolism
- Biocatalysis
- Chromosomal Proteins, Non-Histone/metabolism
- Methylation
- Models, Molecular
- Multiprotein Complexes/chemistry
- Multiprotein Complexes/metabolism
- Nucleic Acid Conformation
- Pyrococcus furiosus/enzymology
- Pyrococcus furiosus/genetics
- RNA Folding
- RNA Processing, Post-Transcriptional
- RNA, Archaeal/chemistry
- RNA, Archaeal/genetics
- RNA, Archaeal/metabolism
- RNA, Ribosomal/chemistry
- RNA, Ribosomal/metabolism
- Ribonucleoproteins, Small Nucleolar/chemistry
- Ribonucleoproteins, Small Nucleolar/metabolism
- RNA, Small Untranslated
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Affiliation(s)
- Audrone Lapinaite
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, Meyerhofstrasse 1, D-69117 Heidelberg, Germany
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36
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Hiraga SI, Botsios S, Donze D, Donaldson AD. TFIIIC localizes budding yeast ETC sites to the nuclear periphery. Mol Biol Cell 2012; 23:2741-54. [PMID: 22496415 PMCID: PMC3395662 DOI: 10.1091/mbc.e11-04-0365] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Eukaryotic genomes contain multiple extra TFIIIC (ETC) sites that bind the TFIIIC transcription factor without recruiting RNA polymerase. TFIIIC directs the localization of Saccharomyces cerevisiae ETC sites to the nuclear periphery. Remarkably, however, perinuclear localization is not required for ETC sites to act as chromatin boundaries. Chromatin function requires specific three-dimensional architectures of chromosomes. We investigated whether Saccharomyces cerevisiae extra TFIIIC (ETC) sites, which bind the TFIIIC transcription factor but do not recruit RNA polymerase III, show specific intranuclear positioning. We show that six of the eight known S. cerevisiae ETC sites localize predominantly at the nuclear periphery, and that ETC sites retain their tethering function when moved to a new chromosomal location. Several lines of evidence indicate that TFIIIC is central to the ETC peripheral localization mechanism. Mutating or deleting the TFIIIC-binding consensus ablated ETC -site peripheral positioning, and inducing degradation of the TFIIIC subunit Tfc3 led to rapid release of an ETC site from the nuclear periphery. We find, moreover, that anchoring one TFIIIC subunit at an ectopic chromosomal site causes recruitment of others and drives peripheral tethering. Localization of ETC sites at the nuclear periphery also requires Mps3, a Sad1-UNC-84–domain protein that spans the inner nuclear membrane. Surprisingly, we find that the chromatin barrier and insulator functions of an ETC site do not depend on correct peripheral localization. In summary, TFIIIC and Mps3 together direct the intranuclear positioning of a new class of S. cerevisiae genomic loci positioned at the nuclear periphery.
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Affiliation(s)
- Shin-ichiro Hiraga
- Institute of Medical Sciences, University of Aberdeen, Aberdeen, Scotland, United Kingdom
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37
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Phipps KR, Charette JM, Baserga SJ. The small subunit processome in ribosome biogenesis—progress and prospects. WILEY INTERDISCIPLINARY REVIEWS-RNA 2012; 2:1-21. [PMID: 21318072 DOI: 10.1002/wrna.57] [Citation(s) in RCA: 129] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The small subunit (SSU) processome is a 2.2-MDa ribonucleoprotein complex involved in the processing, assembly, and maturation of the SSU of eukaryotic ribosomes. The identities of many of the factors involved in SSU biogenesis have been elucidated over the past 40 years. However, as our understanding increases, so do the number of questions about the nature of this complicated process. Cataloging the components is the first step toward understanding the molecular workings of a system. This review will focus on how identifying components of ribosome biogenesis has led to the knowledge of how these factors, protein and RNA alike, associate with one another into subcomplexes, with a concentration on the small ribosomal subunit. We will also explore how this knowledge of subcomplex assembly has informed our understanding of the workings of the ribosome synthesis system as a whole.
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Affiliation(s)
- Kathleen R Phipps
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT, USA
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38
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Boamah EK, Kotova E, Garabedian M, Jarnik M, Tulin AV. Poly(ADP-Ribose) polymerase 1 (PARP-1) regulates ribosomal biogenesis in Drosophila nucleoli. PLoS Genet 2012; 8:e1002442. [PMID: 22242017 PMCID: PMC3252306 DOI: 10.1371/journal.pgen.1002442] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Accepted: 11/14/2011] [Indexed: 11/18/2022] Open
Abstract
Poly(ADP-ribose) polymerase 1 (PARP1), a nuclear protein, utilizes NAD to synthesize poly(AD-Pribose) (pADPr), resulting in both automodification and the modification of acceptor proteins. Substantial amounts of PARP1 and pADPr (up to 50%) are localized to the nucleolus, a subnuclear organelle known as a region for ribosome biogenesis and maturation. At present, the functional significance of PARP1 protein inside the nucleolus remains unclear. Using PARP1 mutants, we investigated the function of PARP1, pADPr, and PARP1-interacting proteins in the maintenance of nucleolus structure and functions. Our analysis shows that disruption of PARP1 enzymatic activity caused nucleolar disintegration and aberrant localization of nucleolar-specific proteins. Additionally, PARP1 mutants have increased accumulation of rRNA intermediates and a decrease in ribosome levels. Together, our data suggests that PARP1 enzymatic activity is required for targeting nucleolar proteins to the proximity of precursor rRNA; hence, PARP1 controls precursor rRNA processing, post-transcriptional modification, and pre-ribosome assembly. Based on these findings, we propose a model that explains how PARP1 activity impacts nucleolar functions and, consequently, ribosomal biogenesis. Ribosome assembly happens primarily in the subnuclear organelle nucleolus. In the nucleolus, ribosomes are assembled into a multmeric complex, composed of rRNA and ribosomal proteins. Although a lot is known about ribosomes and how they function, very little is known about the mechanism that facilitates the assembly of these multimeric protein complexes in the nucleolus. Here, we provide evidence that a nuclear protein, PARP1, primarily known for its DNA damage repair and transcriptional activities, also plays a critical role in the assembly of ribosomes. Using the Drosophila model system, we show that PARP1 localization within the nucleolus impacts such nucleolar activities as rRNA processing and ribosome biogenesis. We show that, when PARP1 activity is disrupted, nucleolar proteins that normally co-localize under wild-type conditions disperse into the nucleoplasm and do not show any co-localization. We also show that some nucleolar proteins, essential for rRNA processing, also interact with pADPr, which keeps these proteins close to precursor rRNA. When PARP1 activity was disrupted, we observed precursors rRNA accumulation and a concomitant decrease in the levels of ribosomes. Together, our data suggest a novel activity for PARP1 and highlight a potential mechanism associated with ribosome biogenesis in the nucleolus.
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Affiliation(s)
- Ernest K. Boamah
- Fox Chase Cancer Center, Philadelphia, Pennsylvania, United States of America
| | - Elena Kotova
- Fox Chase Cancer Center, Philadelphia, Pennsylvania, United States of America
| | - Mikael Garabedian
- Fox Chase Cancer Center, Philadelphia, Pennsylvania, United States of America
| | - Michael Jarnik
- Fox Chase Cancer Center, Philadelphia, Pennsylvania, United States of America
| | - Alexei V. Tulin
- Fox Chase Cancer Center, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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39
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Li P, Jin H, Hoang ML, Yu HG. Tracking chromosome dynamics in live yeast cells: coordinated movement of rDNA homologs and anaphase disassembly of the nucleolus during meiosis. Chromosome Res 2011; 19:1013-26. [PMID: 22083303 DOI: 10.1007/s10577-011-9253-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
Abstract
A prerequisite for determination of chromosome dynamics in live cells is development of a method for staining or marking the chromosome of interest. We describe here a unique chromosome-tracking system that differentially marks two large chromosome segments from homologs in the budding yeast Saccharomyces cerevisiae. Using yeast genetics and the special features at the repetitive ribosomal RNA (rRNA) gene cluster, we incorporated arrays of the tet operator and the lac operator into each repeat of the two rDNA homologs by homologous recombination. Expression of tet repressor-fused green fluorescent protein and lac repressor-fused red fluorescent protein in engineered cells led to the differential labeling of rDNA homologs. Using live-cell three-dimensional fluorescence microscopy, we showed that homologs undergo contraction and expansion cycles in an actin-dependent manner during meiosis and that chromosome mobility appears to be correlated with nuclear positioning. Our observations further revealed that, in contrast to mitosis, in meiosis the yeast nucleolus, the site of rRNA processing, was disassembled upon anaphase onset, suggesting a differential regulation of the rDNA array during meiotic chromosome segregation. Because rRNA genes are highly conserved, a similar chromosome-engineering approach may be adaptable in other eukaryotes for functional assays of chromosome organization in live cells.
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Affiliation(s)
- Ping Li
- Department of Biological Science, The Florida State University, Tallahassee, FL 32306-4370, USA
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Rakitina DV, Taliansky M, Brown JWS, Kalinina NO. Two RNA-binding sites in plant fibrillarin provide interactions with various RNA substrates. Nucleic Acids Res 2011; 39:8869-80. [PMID: 21785141 PMCID: PMC3203579 DOI: 10.1093/nar/gkr594] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Fibrillarin, one of the major proteins of the nucleolus, plays several essential roles in ribosome biogenesis including pre-rRNA processing and 2′-O-ribose methylation of rRNA and snRNAs. Recently, it has been shown that fibrillarin plays a role in virus infections and is associated with viral RNPs. Here, we demonstrate the ability of recombinant fibrillarin 2 from Arabidopsis thaliana (AtFib2) to interact with RNAs of different lengths and types including rRNA, snoRNA, snRNA, siRNA and viral RNAs in vitro. Our data also indicate that AtFib2 possesses two RNA-binding sites in the central (138–179 amino acids) and C-terminal (225–281 amino acids) parts of the protein, respectively. The conserved GCVYAVEF octamer does not bind RNA directly as suggested earlier, but may assist with the proper folding of the central RNA-binding site.
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Affiliation(s)
- D. V. Rakitina
- Department of Virology and A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119991, Russia, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK and Plant Sciences Division, University of Dundee, DD2 5DA, UK
| | - Michael Taliansky
- Department of Virology and A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119991, Russia, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK and Plant Sciences Division, University of Dundee, DD2 5DA, UK
- *To whom correspondence should be addressed. Tel: +44(0)1382562731; Fax: +44 (0)1382 562426;
| | - J. W. S. Brown
- Department of Virology and A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119991, Russia, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK and Plant Sciences Division, University of Dundee, DD2 5DA, UK
| | - N. O. Kalinina
- Department of Virology and A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119991, Russia, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK and Plant Sciences Division, University of Dundee, DD2 5DA, UK
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Xue S, Wang R, Yang F, Terns RM, Terns MP, Zhang X, Maxwell ES, Li H. Structural basis for substrate placement by an archaeal box C/D ribonucleoprotein particle. Mol Cell 2010; 39:939-49. [PMID: 20864039 PMCID: PMC3572848 DOI: 10.1016/j.molcel.2010.08.022] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Revised: 04/20/2010] [Accepted: 07/16/2010] [Indexed: 01/07/2023]
Abstract
Box C/D small nucleolar and Cajal body ribonucleoprotein particles (sno/scaRNPs) direct site-specific 2'-O-methylation of ribosomal and spliceosomal RNAs and are critical for gene expression. Here we report crystal structures of an archaeal box C/D RNP containing three core proteins (fibrillarin, Nop56/58, and L7Ae) and a half-mer box C/D guide RNA paired with a substrate RNA. The structure reveals a guide-substrate RNA duplex orientation imposed by a composite protein surface and the conserved GAEK motif of Nop56/58. Molecular modeling supports a dual C/D RNP structure that closely mimics that recently visualized by electron microscopy. The substrate-bound dual RNP model predicts an asymmetric protein distribution between the RNP that binds and methylates the substrate RNA. The predicted asymmetric nature of the holoenzyme is consistent with previous biochemical data on RNP assembly and provides a simple solution for accommodating base-pairing between the C/D guide RNA and large ribosomal and spliceosomal substrate RNAs.
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Affiliation(s)
- Song Xue
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
| | - Ruiying Wang
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA
| | - Fangping Yang
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA
| | - Rebecca M. Terns
- Departments of Biochemistry and Molecular Biology, and Genetics, University of Georgia, Athens, GA 30602, USA
| | - Michael P. Terns
- Departments of Biochemistry and Molecular Biology, and Genetics, University of Georgia, Athens, GA 30602, USA
| | - Xinxin Zhang
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA
| | - E. Stuart Maxwell
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA
| | - Hong Li
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA,Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA
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Dvorácková M, Rossignol P, Shaw PJ, Koroleva OA, Doonan JH, Fajkus J. AtTRB1, a telomeric DNA-binding protein from Arabidopsis, is concentrated in the nucleolus and shows highly dynamic association with chromatin. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 61:637-49. [PMID: 19947985 DOI: 10.1111/j.1365-313x.2009.04094.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
AtTRB1, 2 and 3 are members of the SMH (single Myb histone) protein family, which comprises double-stranded DNA-binding proteins that are specific to higher plants. They are structurally conserved, containing a Myb domain at the N-terminus, a central H1/H5-like domain and a C-terminally located coiled-coil domain. AtTRB1, 2 and 3 interact through their Myb domain specifically with telomeric double-stranded DNA in vitro, while the central H1/H5-like domain interacts non-specifically with DNA sequences and mediates protein-protein interactions. Here we show that AtTRB1, 2 and 3 preferentially localize to the nucleus and nucleolus during interphase. Both the central H1/H5-like domain and the Myb domain from AtTRB1 can direct a GFP fusion protein to the nucleus and nucleolus. AtTRB1-GFP localization is cell cycle-regulated, as the level of nuclear-associated GFP diminishes during mitotic entry and GFP progressively re-associates with chromatin during anaphase/telophase. Using fluorescence recovery after photobleaching and fluorescence loss in photobleaching, we determined the dynamics of AtTRB1 interactions in vivo. The results reveal that AtTRB1 interaction with chromatin is regulated at two levels at least, one of which is coupled with cell-cycle progression, with the other involving rapid exchange.
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Affiliation(s)
- Martina Dvorácková
- Department of Cell and Developmental Biology, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK
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Song BS, Lee SH, Kim SU, Kim JS, Park JS, Kim CH, Chang KT, Han YM, Lee KK, Lee DS, Koo DB. Nucleologenesis and embryonic genome activation are defective in interspecies cloned embryos between bovine ooplasm and rhesus monkey somatic cells. BMC DEVELOPMENTAL BIOLOGY 2009; 9:44. [PMID: 19635167 PMCID: PMC2734572 DOI: 10.1186/1471-213x-9-44] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2009] [Accepted: 07/28/2009] [Indexed: 01/29/2023]
Abstract
Background Interspecies somatic cell nuclear transfer (iSCNT) has been proposed as a tool to address basic developmental questions and to improve the feasibility of cell therapy. However, the low efficiency of iSCNT embryonic development is a crucial problem when compared to in vitro fertilization (IVF) and intraspecies SCNT. Thus, we examined the effect of donor cell species on the early development of SCNT embryos after reconstruction with bovine ooplasm. Results No apparent difference in cleavage rate was found among IVF, monkey-bovine (MB)-iSCNT, and bovine-bovine (BB)-SCNT embryos. However, MB-iSCNT embryos failed to develop beyond the 8- or 16-cell stages and lacked expression of the genes involved in embryonic genome activation (EGA) at the 8-cell stage. From ultrastructural observations made during the peri-EGA period using transmission electron microscopy (TEM), we found that the nucleoli of MB-iSCNT embryos were morphologically abnormal or arrested at the primary stage of nucleologenesis. Consistent with the TEM analysis, nucleolar component proteins, such as upstream binding transcription factor, fibrillarin, nucleolin, and nucleophosmin, showed decreased expression and were structurally disorganized in MB-iSCNT embryos compared to IVF and BB-SCNT embryos, as revealed by real-time PCR and immunofluorescence confocal laser scanning microscopy, respectively. Conclusion The down-regulation of housekeeping and imprinting genes, abnormal nucleolar morphology, and aberrant patterns of nucleolar proteins during EGA resulted in developmental failure in MB-iSCNT embryos. These results provide insight into the unresolved problems of early embryonic development in iSCNT embryos.
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Affiliation(s)
- Bong-Seok Song
- Development and Differentiation Research Center, Korea Research Institute of Bioscience and Biotechnology, Gwahangno, Yuseong-gu, Daejeon, Republic of Korea.
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Chathoth KT, Ganesan G, Rao MRS. Identification of a novel nucleolin related protein (NRP) gene expressed during rat spermatogenesis. BMC Mol Biol 2009; 10:64. [PMID: 19570216 PMCID: PMC2711064 DOI: 10.1186/1471-2199-10-64] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2008] [Accepted: 07/01/2009] [Indexed: 11/17/2022] Open
Abstract
Background Nucleolin is a major nucleolar phosphoprotein involved in various steps of ribosome biogenesis in eukaryotic cells. As nucleolin plays a significant role in ribosomal RNA transcription we were interested in examining in detail the expression of nucleolin across different stages of spermatogenesis and correlate with the transcription status of ribosomal DNA in germ cells. Results By RT PCR and western blot analysis we found that nucleolin is strongly down regulated in meiotic spermatocytes and haploid germ cells. We have identified a new nucleolin related protein (NRP) gene in the rat genome, which is over expressed in the testis and is up regulated several fold in meiotic spermatocytes and haploid germ cells. The NRP protein lacks the acidic stretches in its N terminal domain, and it is encoded in rat chromosome 15 having a different genomic organization as compared to nucleolin gene present on chromosome 9. We have also found NRP genes encoded in genomes of other mammalian species. We performed run-on transcription assay where we have observed that rDNA is transcribed at much lower level in meiotic spermatocytes and haploid spermatids as compared to diploid cells. By siRNA knock down experiments we could also demonstrate that NRP can support rDNA transcription in the absence of nucleolin. Conclusion We have identified a new nucleolin variant over expressed in germ cells in rat and analyzed its domain structure. We attribute that the transcriptional activity of rDNA genes in the late spermatogenesis is due to the presence of this variant NRP. The expression of this variant in the germ cells in the absence of nucleolin, could have additional functions in the mammalian spermatogenesis which needs to be investigated further.
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Affiliation(s)
- Keerthi T Chathoth
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Banglore, India 560064, USA.
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Caporale M, Arnaud F, Mura M, Golder M, Murgia C, Palmarini M. The signal peptide of a simple retrovirus envelope functions as a posttranscriptional regulator of viral gene expression. J Virol 2009; 83:4591-604. [PMID: 19244321 PMCID: PMC2668452 DOI: 10.1128/jvi.01833-08] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2008] [Accepted: 02/17/2009] [Indexed: 12/22/2022] Open
Abstract
Retroviruses use different strategies to regulate transcription and translation and exploit the cellular machinery involved in these processes. This study shows that the signal peptide of the envelope glycoprotein (Env) of Jaagsiekte sheep retrovirus (JSRV) plays a major role in posttranscriptional viral gene expression. Expression of the JSRV Env in trans increases viral particle production by mechanisms dependent on (i) its leader sequence, (ii) an intact signal peptide cleavage site, (iii) a cis-acting RNA-responsive element located in the viral genome, (iv) Crm1, and (v) B23. The signal peptide of the JSRV Env (JSE-SP) is 80 amino acid residues in length and contains putative nuclear localization and export signals, in addition to an arginine-rich RNA binding motif. JSE-SP localizes both in the endoplasmic reticulum and in the nucleus, where it colocalizes with nucleolar markers. JSE-SP is a multifunctional protein, as it moderately enhances nuclear export of unspliced viral mRNA and considerably increases viral particle release by favoring a posttranslational step of the replication cycle.
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Affiliation(s)
- Marco Caporale
- Institute of Comparative Medicine, University of Glasgow Faculty of Veterinary Medicine, Glasgow, Scotland
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Dif1 controls subcellular localization of ribonucleotide reductase by mediating nuclear import of the R2 subunit. Mol Cell Biol 2008; 28:7156-67. [PMID: 18838542 DOI: 10.1128/mcb.01388-08] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Fidelity in DNA replication and repair requires adequate and balanced deoxyribonucleotide pools that are maintained primarily by regulation of ribonucleotide reductase (RNR). RNR is controlled via transcription, protein inhibitor association, and subcellular localization of its two subunits, R1 and R2. Saccharomyces cerevisiae Sml1 binds R1 and inhibits its activity, while Schizosaccharomyces pombe Spd1 impedes RNR holoenzyme formation by sequestering R2 in the nucleus away from the cytoplasmic R1. Here we report the identification and characterization of S. cerevisiae Dif1, a regulator of R2 nuclear localization and member of a new family of proteins sharing separate homologous domains with Spd1 and Sml1. Dif1 is localized in the cytoplasm and acts in a pathway different from the nuclear R2-anchoring protein Wtm1. Like Sml1 and Spd1, Dif1 is phosphorylated and degraded in cells encountering DNA damage, thereby relieving inhibition of RNR. A shared domain between Sml1 and Dif1 controls checkpoint kinase-mediated phosphorylation and degradation of the two proteins. Abolishing Dif1 phosphorylation stabilizes the protein and delays damage-induced nucleus-to-cytoplasm redistribution of R2. This study suggests that Dif1 is required for nuclear import of the R2 subunit and plays an essential role in regulating the dynamic RNR subcellular localization.
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Functional features of the C-terminal region of yeast ribosomal protein L5. Mol Genet Genomics 2008; 280:337-50. [PMID: 18751732 DOI: 10.1007/s00438-008-0369-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2008] [Accepted: 07/19/2008] [Indexed: 10/21/2022]
Abstract
The aim of this study was to analyze the functional importance of the C-terminus of the essential yeast ribosomal protein L5 (YrpL5). Previous studies have indicated that the C-terminal region of YrpL5 forms an alpha-helix with a positively charged surface that is involved in protein-5S rRNA interaction. Formation of an YrpL5.5S rRNA complex is a prerequisite for nuclear import of YrpL5. Here we have tested the importance of the alpha-helix and the positively charged surface for YrpL5 function in Saccharomyces cerevisiae using site directed mutagenesis in combination with functional complementation. Alterations in the sequence forming the putative alpha-helix affected the functional capacity of YrpL5. However, the effect did not correlate with a decreased ability of the protein to bind to 5S rRNA as all rpL5 mutants tested were imported to the nucleus whether or not the alpha-helix or the positively charged surface were intact. The alterations introduced in the C-terminal sequence affected the growth rate of cells expressing mutant but functional forms of YrpL5. The reduced growth rate was correlated with a reduced ribosomal content per cell indicating that the alterations introduced in the C-terminus interfered with ribosome assembly.
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Aftab MN, He H, Skogerbø G, Chen R. Microarray analysis of ncRNA expression patterns in Caenorhabditis elegans after RNAi against snoRNA associated proteins. BMC Genomics 2008; 9:278. [PMID: 18547420 PMCID: PMC2442092 DOI: 10.1186/1471-2164-9-278] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2007] [Accepted: 06/11/2008] [Indexed: 11/30/2022] Open
Abstract
Background Short non-coding RNAs (ncRNAs) perform their cellular functions in ribonucleoprotein (RNP) complexes, which are also essential for maintaining the stability of the ncRNAs. Depletion of individual protein components of non-coding ribonucleoprotein (ncRNP) particles by RNA interference (RNAi) may therefore affect expression levels of the corresponding ncRNA, and depletion of candidate associated proteins may constitute an alternative strategy when investigating ncRNA-protein interactions and ncRNA functions. Therefore, we carried out a pilot study in which the effects of RNAi against protein components of small nucleolar RNPs (snoRNPs) in Caenorhabditis elegans were observed on an ncRNA microarray. Results RNAi against individual C. elegans protein components of snoRNPs produced strongly reduced mRNA levels and distinct phenotypes for all targeted proteins. For each type of snoRNP, individual depletion of at least three of the four protein components produced significant (P ≦ 1.2 × 10-5) reductions in the expression levels of the corresponding small nucleolar RNAs (snoRNAs), whereas the expression levels of other ncRNAs were largely unaffected. The effects of depletion of individual proteins were in accordance with snoRNP structure analyses obtained in other species for all but two of the eight targeted proteins. Variations in snoRNA size, sequence and secondary structure characteristics were not systematically reflected in the affinity for individual protein component of snoRNPs. The data supported the classification of nearly all annotated snoRNAs and suggested the presence of several novel snoRNAs among unclassified short ncRNA transcripts. A number of transcripts containing canonical Sm binding element sequences (Sm Y RNAs) also showed reduced expression after depletion of protein components of C/D box snoRNPs, whereas the expression of some stem-bulge RNAs (sbRNAs) was increased after depletion of the same proteins. Conclusion The study confirms observations made for other organisms, where reduced ncRNA levels after depletion of protein components of ncRNPs were noted, and shows that such reductions in expression levels occur across entire sets of ncRNA. Thereby, the study also demonstrates the feasibility of combining RNAi against candidate proteins with ncRNA microarray analysis to investigate ncRNA-protein interactions and hence ncRNA cellular functions.
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Affiliation(s)
- Muhammad Nauman Aftab
- Bioinformatics Laboratory and National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences Beijing 100101, PR China.
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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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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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