1
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Qin J, Garus A, Autexier C. The C-terminal extension of dyskerin is a dyskeratosis congenita mutational hotspot that modulates interaction with telomerase RNA and subcellular localization. Hum Mol Genet 2024; 33:318-332. [PMID: 37879098 PMCID: PMC10840380 DOI: 10.1093/hmg/ddad180] [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: 08/24/2023] [Revised: 10/09/2023] [Accepted: 10/20/2023] [Indexed: 10/27/2023] Open
Abstract
Dyskerin is a component of the human telomerase complex and is involved in stabilizing the human telomerase RNA (hTR). Many mutations in the DKC1 gene encoding dyskerin are found in X-linked dyskeratosis congenita (X-DC), a premature aging disorder and other related diseases. The C-terminal extension (CTE) of dyskerin contributes to its interaction with the molecular chaperone SHQ1 during the early stage of telomerase biogenesis. Disease mutations in this region were proposed to disrupt dyskerin-SHQ1 interaction and destabilize dyskerin, reducing hTR levels indirectly. However, biochemical evidence supporting this hypothesis is still lacking. In addition, the effects of many CTE disease mutations on hTR have not been examined. In this study, we tested eight dyskerin CTE variants and showed that they failed to maintain hTR levels. These mutants showed slightly reduced but not abolished interaction with SHQ1, and caused defective binding to hTR. Deletion of the CTE further reduced binding to hTR, and perturbed localization of dyskerin to the Cajal bodies and the nucleolus, and the interaction with TCAB1 as well as GAR1. Our findings suggest impaired dyskerin-hTR interaction in cells as a previously overlooked mechanism through which dyskerin CTE mutations cause X-DC and related telomere syndromes.
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Affiliation(s)
- Jian Qin
- Department of Anatomy and Cell Biology, McGill University, 3640 University Street, Montreal, Quebec, QC H3A 0C7, Canada
- Lady Davis Institute, Jewish General Hospital, 3755 Chem, de la Côte-Sainte-Catherine, Montréal, QC H3T 1E2, Canada
| | - Alexandre Garus
- Department of Anatomy and Cell Biology, McGill University, 3640 University Street, Montreal, Quebec, QC H3A 0C7, Canada
- Lady Davis Institute, Jewish General Hospital, 3755 Chem, de la Côte-Sainte-Catherine, Montréal, QC H3T 1E2, Canada
| | - Chantal Autexier
- Department of Anatomy and Cell Biology, McGill University, 3640 University Street, Montreal, Quebec, QC H3A 0C7, Canada
- Lady Davis Institute, Jewish General Hospital, 3755 Chem, de la Côte-Sainte-Catherine, Montréal, QC H3T 1E2, Canada
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2
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Klump BM, Perez GI, Patrick EM, Adams-Boone K, Cohen SB, Han L, Yu K, Schmidt JC. TCAB1 prevents nucleolar accumulation of the telomerase RNA to facilitate telomerase assembly. Cell Rep 2023; 42:112577. [PMID: 37267110 PMCID: PMC10569210 DOI: 10.1016/j.celrep.2023.112577] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2023] [Revised: 03/27/2023] [Accepted: 05/12/2023] [Indexed: 06/04/2023] Open
Abstract
Localization of a variety of RNAs to non-membrane-bound cellular compartments such as nucleoli and Cajal bodies is critical for their stability and function. The molecular mechanisms that underly the recruitment and exclusion of RNAs from these phase-separated organelles is incompletely understood. Telomerase is a ribonucleoprotein composed of the reverse transcriptase protein telomerase reverse transcriptase (TERT), the telomerase RNA (TR), and several auxiliary proteins, including TCAB1. Here we show that in the absence of TCAB1, a large fraction of TR is tightly bound to the nucleolus, while TERT is largely excluded from the nucleolus, reducing telomerase assembly. This suggests that nuclear compartmentalization by the non-membrane-bound nucleolus counteracts telomerase assembly, and TCAB1 is required to retain TR in the nucleoplasm. Our work provides insight into the mechanism and functional consequences of RNA recruitment to organelles formed by phase separation and demonstrates that TCAB1 plays an important role in telomerase assembly.
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Affiliation(s)
- Basma M Klump
- Institute for Quantitative Health Sciences and Engineering, Michigan State University, East Lansing, MI, USA; College of Osteopathic Medicine, Michigan State University, East Lansing, MI, USA; Cellular and Molecular Biology Graduate Program, College of Natural Sciences, Michigan State University, East Lansing, MI, USA
| | - Gloria I Perez
- Institute for Quantitative Health Sciences and Engineering, Michigan State University, East Lansing, MI, USA
| | - Eric M Patrick
- Institute for Quantitative Health Sciences and Engineering, Michigan State University, East Lansing, MI, USA
| | - Kate Adams-Boone
- Institute for Quantitative Health Sciences and Engineering, Michigan State University, East Lansing, MI, USA
| | - Scott B Cohen
- Children's Medical Research Institute and University of Sydney, Westmead, NSW 2145, Australia
| | - Li Han
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA
| | - Kefei Yu
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA
| | - Jens C Schmidt
- Institute for Quantitative Health Sciences and Engineering, Michigan State University, East Lansing, MI, USA; Department of Obstetrics, Gynecology, and Reproductive Biology, Michigan State University, East Lansing, MI, USA.
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3
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Sochacka M, Karelus R, Opalinski L, Krowarsch D, Biadun M, Otlewski J, Zakrzewska M. FGF12 is a novel component of the nucleolar NOLC1/TCOF1 ribosome biogenesis complex. Cell Commun Signal 2022; 20:182. [PMID: 36411431 PMCID: PMC9677703 DOI: 10.1186/s12964-022-01000-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 10/26/2022] [Indexed: 11/22/2022] Open
Abstract
Among the FGF proteins, the least characterized superfamily is the group of fibroblast growth factor homologous factors (FHFs). To date, the main role of FHFs has been primarily seen in the modulation of voltage-gated ion channels, but a full picture of the function of FHFs inside the cell is far from complete. In the present study, we focused on identifying novel FGF12 binding partners to indicate its intracellular functions. Among the identified proteins, a significant number were nuclear proteins, especially RNA-binding proteins involved in translational processes, such as ribosomal processing and modification. We have demonstrated that FGF12 is localized to the nucleolus, where it interacts with NOLC1 and TCOF1, proteins involved in the assembly of functional ribosomes. Interactions with both NOLC1 and TCOF1 are unique to FGF12, as other FHF proteins only bind to TCOF1. The formation of nucleolar FGF12 complexes with NOLC1 and TCOF1 is phosphorylation-dependent and requires the C-terminal region of FGF12. Surprisingly, NOLC1 and TCOF1 are unable to interact with each other in the absence of FGF12. Taken together, our data link FHF proteins to nucleoli for the first time and suggest a novel and unexpected role for FGF12 in ribosome biogenesis. Video Abstract.
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Affiliation(s)
- Martyna Sochacka
- grid.8505.80000 0001 1010 5103Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383 Wrocław, Poland
| | - Radoslaw Karelus
- grid.8505.80000 0001 1010 5103Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383 Wrocław, Poland
| | - Lukasz Opalinski
- grid.8505.80000 0001 1010 5103Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383 Wrocław, Poland
| | - Daniel Krowarsch
- grid.8505.80000 0001 1010 5103Department of Protein Biotechnology, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383 Wrocław, Poland
| | - Martyna Biadun
- grid.8505.80000 0001 1010 5103Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383 Wrocław, Poland
| | - Jacek Otlewski
- grid.8505.80000 0001 1010 5103Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383 Wrocław, Poland
| | - Malgorzata Zakrzewska
- grid.8505.80000 0001 1010 5103Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383 Wrocław, Poland
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4
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Cockman ME, Sugimoto Y, Pegg HB, Masson N, Salah E, Tumber A, Flynn HR, Kirkpatrick JM, Schofield CJ, Ratcliffe PJ. Widespread hydroxylation of unstructured lysine-rich protein domains by JMJD6. Proc Natl Acad Sci U S A 2022; 119:e2201483119. [PMID: 35930668 PMCID: PMC9371714 DOI: 10.1073/pnas.2201483119] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 06/24/2022] [Indexed: 11/18/2022] Open
Abstract
The Jumonji domain-containing protein JMJD6 is a 2-oxoglutarate-dependent dioxygenase associated with a broad range of biological functions. Cellular studies have implicated the enzyme in chromatin biology, transcription, DNA repair, mRNA splicing, and cotranscriptional processing. Although not all studies agree, JMJD6 has been reported to catalyze both hydroxylation of lysine residues and demethylation of arginine residues. However, despite extensive study and indirect evidence for JMJD6 catalysis in many cellular processes, direct assignment of JMJD6 catalytic substrates has been limited. Examination of a reported site of proline hydroxylation within a lysine-rich region of the tandem bromodomain protein BRD4 led us to conclude that hydroxylation was in fact on lysine and catalyzed by JMJD6. This prompted a wider search for JMJD6-catalyzed protein modifications deploying mass spectrometric methods designed to improve the analysis of such lysine-rich regions. Using lysine derivatization with propionic anhydride to improve the analysis of tryptic peptides and nontryptic proteolysis, we report 150 sites of JMJD6-catalyzed lysine hydroxylation on 48 protein substrates, including 19 sites of hydroxylation on BRD4. Most hydroxylations were within lysine-rich regions that are predicted to be unstructured; in some, multiple modifications were observed on adjacent lysine residues. Almost all of the JMJD6 substrates defined in these studies have been associated with membraneless organelle formation. Given the reported roles of lysine-rich regions in subcellular partitioning by liquid-liquid phase separation, our findings raise the possibility that JMJD6 may play a role in regulating such processes in response to stresses, including hypoxia.
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Affiliation(s)
- Matthew E. Cockman
- Hypoxia Biology Laboratory, Francis Crick Institute, London, NW1 1AT, United Kingdom
| | - Yoichiro Sugimoto
- Hypoxia Biology Laboratory, Francis Crick Institute, London, NW1 1AT, United Kingdom
| | - Hamish B. Pegg
- Hypoxia Biology Laboratory, Francis Crick Institute, London, NW1 1AT, United Kingdom
| | - Norma Masson
- Ludwig Institute for Cancer Research, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX3 7DQ, United Kingdom
| | - Eidarus Salah
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, OX1 3TA, United Kingdom
| | - Anthony Tumber
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, OX1 3TA, United Kingdom
| | - Helen R. Flynn
- Hypoxia Biology Laboratory, Francis Crick Institute, London, NW1 1AT, United Kingdom
| | - Joanna M. Kirkpatrick
- Hypoxia Biology Laboratory, Francis Crick Institute, London, NW1 1AT, United Kingdom
| | - Christopher J. Schofield
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, OX1 3TA, United Kingdom
| | - Peter J. Ratcliffe
- Hypoxia Biology Laboratory, Francis Crick Institute, London, NW1 1AT, United Kingdom
- Ludwig Institute for Cancer Research, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX3 7DQ, United Kingdom
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Kiss DJ, Oláh J, Tóth G, Varga M, Stirling A, Menyhárd DK, Ferenczy GG. The Structure-Derived Mechanism of Box H/ACA Pseudouridine Synthase Offers a Plausible Paradigm for Programmable RNA Editing. ACS Catal 2022. [DOI: 10.1021/acscatal.1c04870] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Dóra Judit Kiss
- Medicinal Chemistry Research Group, Research Centre for Natural Sciences, Magyar tudósok krt. 2, H-1117 Budapest, Hungary
| | - Julianna Oláh
- Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Műegyetem rakpart 3, H-1111 Budapest, Hungary
| | - Gergely Tóth
- Institute of Chemistry, ELTE Eötvös Loránd University, Pázmány P. stny. 1/a, H-1117 Budapest, Hungary
| | - Máté Varga
- Department of Genetics, ELTE Eötvös Loránd University, Pázmány P. stny. 1/c, H-1117 Budapest, Hungary
| | - András Stirling
- Theoretical Chemistry Research Group, Research Centre for Natural Sciences, Magyar tudósok krt. 2, H-1117 Budapest, Hungary
| | - Dóra K. Menyhárd
- MTA-ELTE Protein Modelling Research Group, Institute of Chemistry, ELTE Eötvös Loránd University, Pázmány P. stny. 1/a, H-1117 Budapest, Hungary
| | - György G. Ferenczy
- Medicinal Chemistry Research Group, Research Centre for Natural Sciences, Magyar tudósok krt. 2, H-1117 Budapest, Hungary
- Department of Biophysics and Radiation Biology, Semmelweis University, Tűzoltó u. 37-47, H-1094 Budapest, Hungary
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6
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Garus A, Autexier C. Dyskerin: an essential pseudouridine synthase with multifaceted roles in ribosome biogenesis, splicing, and telomere maintenance. RNA (NEW YORK, N.Y.) 2021; 27:1441-1458. [PMID: 34556550 PMCID: PMC8594475 DOI: 10.1261/rna.078953.121] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Dyskerin and its homologs are ancient and conserved enzymes that catalyze the most common post-transcriptional modification found in cells, pseudouridylation. The resulting pseudouridines provide stability to RNA molecules and regulate ribosome biogenesis and splicing events. Dyskerin does not act independently-it is the core component of a protein heterotetramer, which associates with RNAs that contain the H/ACA motif. The variety of H/ACA RNAs that guide the function of this ribonucleoprotein (RNP) complex highlights the diversity of cellular processes in which dyskerin participates. When associated with small nucleolar (sno) RNAs, it regulates ribosomal (r) RNAs and ribosome biogenesis. By interacting with small Cajal body (sca) RNAs, it targets small nuclear (sn) RNAs to regulate pre-mRNA splicing. As a component of the telomerase holoenzyme, dyskerin binds to the telomerase RNA to modulate telomere maintenance. In a disease context, dyskerin malfunction can result in multiple detrimental phenotypes. Mutations in DKC1, the gene that encodes dyskerin, cause the premature aging syndrome X-linked dyskeratosis congenita (X-DC), a still incurable disorder that typically leads to bone marrow failure. In this review, we present the classical and most recent findings on this essential protein, discussing the evolutionary, structural, and functional aspects of dyskerin and the H/ACA RNP. The latest research underscores the role that dyskerin plays in the regulation of gene expression, translation efficiency, and telomere maintenance, along with the impacts that defective dyskerin has on aging, cell proliferation, haematopoietic potential, and cancer.
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Affiliation(s)
- Alexandre Garus
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, H3A 0C7, Canada
- Jewish General Hospital, Lady Davis Institute, Montreal, Quebec, H3T 1E2, Canada
| | - Chantal Autexier
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, H3A 0C7, Canada
- Jewish General Hospital, Lady Davis Institute, Montreal, Quebec, H3T 1E2, Canada
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7
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SUMOylation- and GAR1-Dependent Regulation of Dyskerin Nuclear and Subnuclear Localization. Mol Cell Biol 2021; 41:MCB.00464-20. [PMID: 33526451 DOI: 10.1128/mcb.00464-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 01/20/2021] [Indexed: 12/29/2022] Open
Abstract
The nuclear and subnuclear compartmentalization of the telomerase-associated protein and H/ACA ribonucleoprotein component dyskerin is an important although incompletely understood aspect of H/ACA ribonucleoprotein function. Four SUMOylation sites were previously identified in the C-terminal nuclear/nucleolar localization signal (N/NoLS) of dyskerin. We found that a cytoplasmic localized C-terminal truncation variant of dyskerin lacking most of the C-terminal N/NoLS represents an under-SUMOylated variant of dyskerin compared to wild-type dyskerin. We demonstrate that mimicking constitutive SUMOylation of dyskerin using a SUMO3 fusion construct can drive nuclear accumulation of this variant and that the SUMO site K467 in this N/NoLS is particularly important for the subnuclear localization of dyskerin to the nucleolus in a mature H/ACA complex assembly- and SUMO-dependent manner. We also characterize a novel SUMO-interacting motif in the mature H/ACA complex component GAR1 that mediates the interaction between dyskerin and GAR1. Mislocalization of dyskerin, either in the cytoplasm or excluded from the nucleolus, disrupts dyskerin function and leads to reduced interaction of dyskerin with the telomerase RNA. These data indicate a role for dyskerin C-terminal N/NoLS SUMOylation in regulating the nuclear and subnuclear localization of dyskerin, which is essential for dyskerin function as both a telomerase-associated protein and as an H/ACA ribonucleoprotein.
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8
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Elsharawy KA, Mohammed OJ, Aleskandarany MA, Hyder A, El-Gammal HL, Abou-Dobara MI, Green AR, Dalton LW, Rakha EA. The nucleolar-related protein Dyskerin pseudouridine synthase 1 (DKC1) predicts poor prognosis in breast cancer. Br J Cancer 2020; 123:1543-1552. [PMID: 32868896 PMCID: PMC7653035 DOI: 10.1038/s41416-020-01045-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 07/28/2020] [Accepted: 08/13/2020] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Hypertrophy of the nucleolus is a distinctive cytological feature of malignant cells and corresponds to aggressive behaviour. This study aimed to identify the key gene associated with nucleolar prominence (NP) in breast cancer (BC) and determine its prognostic significance. METHODS From The Cancer Genome Atlas (TCGA) cohort, digital whole slide images identified cancers having NP served as label and an information theory algorithm was applied to find which mRNA gene best explained NP. Dyskerin Pseudouridine Synthase 1 (DKC1) was identified. DKC1 expression was assessed using mRNA data of Molecular Taxonomy of Breast Cancer International Consortium (METABRIC, n = 1980) and TCGA (n = 855). DKC1 protein expression was assessed using immunohistochemistry in Nottingham BC cohort (n = 943). RESULTS Nuclear and nucleolar expressions of DKC1 protein were significantly associated with higher tumour grade (p < 0.0001), high nucleolar score (p < 0.001) and poor Nottingham Prognostic Index (p < 0.0001). High DKC1 expression was associated with shorter BC-specific survival (BCSS). In multivariate analysis, DKC1 mRNA and protein expressions were independent risk factors for BCSS (p < 0.01). CONCLUSION DKC1 expression is strongly correlated with NP and its overexpression in BC is associated with unfavourable clinicopathological characteristics and poor outcome. This has been a detailed example in the correlation of phenotype with genotype.
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Affiliation(s)
- Khloud A Elsharawy
- Nottingham Breast Cancer Research Centre, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham Biodiscovery Institute, University Park, Nottingham, UK
- Faculty of Science, Damietta University, Damietta, Egypt
| | - Omar J Mohammed
- Nottingham Breast Cancer Research Centre, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham Biodiscovery Institute, University Park, Nottingham, UK
| | - Mohammed A Aleskandarany
- Nottingham Breast Cancer Research Centre, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham Biodiscovery Institute, University Park, Nottingham, UK
| | - Ayman Hyder
- Faculty of Science, Damietta University, Damietta, Egypt
| | | | | | - Andrew R Green
- Nottingham Breast Cancer Research Centre, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham Biodiscovery Institute, University Park, Nottingham, UK
| | - Leslie W Dalton
- Department of Histopathology, South Austin Hospital, Austin, TX, USA
| | - Emad A Rakha
- Nottingham Breast Cancer Research Centre, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham Biodiscovery Institute, University Park, Nottingham, UK.
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9
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MacNeil DE, Lambert-Lanteigne P, Autexier C. N-terminal residues of human dyskerin are required for interactions with telomerase RNA that prevent RNA degradation. Nucleic Acids Res 2019; 47:5368-5380. [PMID: 30931479 PMCID: PMC6547437 DOI: 10.1093/nar/gkz233] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 03/19/2019] [Accepted: 03/25/2019] [Indexed: 12/16/2022] Open
Abstract
The telomerase holoenzyme responsible for maintaining telomeres in vertebrates requires many components in vivo, including dyskerin. Dyskerin binds and regulates the accumulation of the human telomerase RNA, hTR, as well as other non-coding RNAs that share the conserved H/ACA box motif. The precise mechanism by which dyskerin controls hTR levels is unknown, but is evidenced by defective hTR accumulation caused by substitutions in dyskerin, that are observed in the X-linked telomere biology disorder dyskeratosis congenita (X-DC). To understand the role of dyskerin in hTR accumulation, we analyzed X-DC substitutions K39E and K43E in the poorly characterized dyskerin N-terminus, and A353V within the canonical RNA binding domain (the PUA). These variants exhibited impaired binding to hTR and polyadenylated hTR species, while interactions with other H/ACA RNAs appear largely unperturbed by the N-terminal substitutions. hTR accumulation and telomerase activity defects of dyskerin-deficient cells were rescued by wildtype dyskerin but not the variants. hTR 3′ extended or polyadenylated species did not accumulate, suggesting hTR precursor degradation occurs upstream of mature complex assembly in the absence of dyskerin binding. Our findings demonstrate that the dyskerin-hTR interaction mediated by PUA and N-terminal residues of dyskerin is crucial to prevent unchecked hTR degradation.
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Affiliation(s)
- Deanna E MacNeil
- Jewish General Hospital of McGill University, Lady Davis Institute, Montreal, Quebec H3T 1E2, Canada.,Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec H3A 0C7, Canada
| | - Patrick Lambert-Lanteigne
- Jewish General Hospital of McGill University, Lady Davis Institute, Montreal, Quebec H3T 1E2, Canada
| | - Chantal Autexier
- Jewish General Hospital of McGill University, Lady Davis Institute, Montreal, Quebec H3T 1E2, Canada.,Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec H3A 0C7, Canada
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10
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MacNeil DE, Bensoussan HJ, Autexier C. Telomerase Regulation from Beginning to the End. Genes (Basel) 2016; 7:genes7090064. [PMID: 27649246 PMCID: PMC5042394 DOI: 10.3390/genes7090064] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 08/25/2016] [Accepted: 08/26/2016] [Indexed: 12/11/2022] Open
Abstract
The vast body of literature regarding human telomere maintenance is a true testament to the importance of understanding telomere regulation in both normal and diseased states. In this review, our goal was simple: tell the telomerase story from the biogenesis of its parts to its maturity as a complex and function at its site of action, emphasizing new developments and how they contribute to the foundational knowledge of telomerase and telomere biology.
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Affiliation(s)
- Deanna Elise MacNeil
- Bloomfield Centre for Research in Aging, Lady Davis Institute for Medical Research, Jewish General Hospital, 3755 Côte Ste-Catherine Road, Montréal, QC H3T 1E2, Canada.
- Room M-29, Department of Anatomy and Cell Biology, McGill University, 3640 University Street, Montréal, QC H3A 0C7, Canada.
| | - Hélène Jeanne Bensoussan
- Bloomfield Centre for Research in Aging, Lady Davis Institute for Medical Research, Jewish General Hospital, 3755 Côte Ste-Catherine Road, Montréal, QC H3T 1E2, Canada.
- Room M-29, Department of Anatomy and Cell Biology, McGill University, 3640 University Street, Montréal, QC H3A 0C7, Canada.
| | - Chantal Autexier
- Bloomfield Centre for Research in Aging, Lady Davis Institute for Medical Research, Jewish General Hospital, 3755 Côte Ste-Catherine Road, Montréal, QC H3T 1E2, Canada.
- Room M-29, Department of Anatomy and Cell Biology, McGill University, 3640 University Street, Montréal, QC H3A 0C7, Canada.
- Department of Experimental Medicine, McGill University, 1110 Pins Avenue West, Room 101, Montréal, QC H3A 1A3, Canada.
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11
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GSE4, a Small Dyskerin- and GSE24.2-Related Peptide, Induces Telomerase Activity, Cell Proliferation and Reduces DNA Damage, Oxidative Stress and Cell Senescence in Dyskerin Mutant Cells. PLoS One 2015; 10:e0142980. [PMID: 26571381 PMCID: PMC4646510 DOI: 10.1371/journal.pone.0142980] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 10/29/2015] [Indexed: 02/04/2023] Open
Abstract
Dyskeratosis congenita is an inherited disease caused by mutations in genes coding for telomeric components. It was previously reported that expression of a dyskerin-derived peptide, GSE24.2, increases telomerase activity, regulates gene expression and decreases DNA damage and oxidative stress in dyskeratosis congenita patient cells. The biological activity of short peptides derived from GSE24.2 was tested and one of them, GSE4, that probed to be active, was further characterized in this article. Expression of this eleven amino acids long peptide increased telomerase activity and reduced DNA damage, oxidative stress and cell senescence in dyskerin-mutated cells. GSE4 expression also activated c-myc and TERT promoters and increase of c-myc, TERT and TERC expression. The level of biological activity of GSE4 was similar to that obtained by GSE24.2 expression. Incorporation of a dyskerin nuclear localization signal to GSE24.2 did not change its activity on promoter regulation and DNA damage protection. However, incorporation of a signal that increases the rate of nucleolar localization impaired GSE24.2 activity. Incorporation of the dyskerin nuclear localization signal to GSE4 did not alter its biological activity. Mutation of the Aspartic Acid residue that is conserved in the pseudouridine synthase domain present in GSE4 did not impair its activity, except for the repression of c-myc promoter activity and the decrease of c-myc, TERT and TERC gene expression in dyskerin-mutated cells. These results indicated that GSE4 could be of great therapeutic interest for treatment of dyskeratosis congenita patients.
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12
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Cerrudo CS, Mengual Gómez DL, Gómez DE, Ghiringhelli PD. Novel insights into the evolution and structural characterization of dyskerin using comprehensive bioinformatics analysis. J Proteome Res 2015; 14:874-87. [PMID: 25540932 DOI: 10.1021/pr500956k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Dyskerin is a conserved nucleolar protein. Several related genetic diseases are caused by defects in dyskerin. We hypothesized that having a comprehensive bioinformatic analysis of dyskerin will help to develop new drugs for this diseases. We predicted protein domains and compared sequences and structures to detect the universe of dyskerin-like proteins. We identified conserved features of shared domains in the three superkingdoms. We analyzed the phylogenetic diversity, confirming that there is a strong structural conservation. Also, we studied the relationship of dyskerin-like proteins with other proteins through an integrative protein-protein interaction approach. Most of them are conserved among homologous eukaryotic and archaeal proteins. Our results highlighted the preservation of proteins interacting with dyskerin. We identified conserved dyskerin interactor proteins between the different eukaryotes organisms. Furthermore, we studied the existence of dyskerin-like proteins in different species. Also, we compared and analyzed the secondary structure with the hydrophobic profile, confirming that all have hydrophilic properties highly conserved among proteins. The greatest difference was observed in the NTE and CTE regions. Another aspect studied was the comparison and analysis of tertiary structures. In our knowledge, this is the first time that these analyses were performed in such a comprehensive manner.
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Affiliation(s)
- Carolina Susana Cerrudo
- Laboratory of Genetic Engineering and Cellular and Molecular Biology, Department of Science and Technology, Quilmes National University , Roque Saenz Peña 352, 1876 Bernal, Buenos Aires, Argentine
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13
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Qin W, Chen Z, Zhang Y, Yan R, Yan G, Li S, Zhong H, Lin S. Nom1 mediates pancreas development by regulating ribosome biogenesis in zebrafish. PLoS One 2014; 9:e100796. [PMID: 24967912 PMCID: PMC4072693 DOI: 10.1371/journal.pone.0100796] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 05/29/2014] [Indexed: 11/18/2022] Open
Abstract
Ribosome biogenesis is an important biological process for proper cellular function and development. Defects leading to improper ribosome biogenesis can cause diseases such as Diamond-Blackfan anemia and Shwachman-Bodian-Diamond syndrome. Nucleolar proteins are a large family of proteins and are involved in many cellular processes, including the regulation of ribosome biogenesis. Through a forward genetic screen and positional cloning, we identified and characterized a zebrafish line carrying mutation in nucleolar protein with MIF4G domain 1 (nom1), which encodes a conserved nulceolar protein with a role in pre-rRNA processing. Zebrafish nom1 mutants exhibit major defects in endoderm development, especially in exocrine pancreas. Further studies revealed that impaired proliferation of ptf1a-expressing pancreatic progenitor cells mainly contributed to the phenotype. RNA-seq and molecular analysis showed that ribosome biogenesis and pre-mRNA splicing were both affected in the mutant embryos. Several defects of ribosome assembly have been shown to have a p53-dependent mechanism. In the nom1 mutant, loss of p53 did not rescue the pancreatic defect, suggesting a p53-independent role. Further studies indicate that protein phosphatase 1 alpha, an interacting protein to Nom1, could partially rescue the pancreatic defect in nom1 morphants if a human nucleolar localization signal sequence was artificially added. This suggests that targeting Pp1α into the nucleolus by Nom1 is important for pancreatic proliferation. Altogether, our studies revealed a new mechanism involving Nom1 in controlling vertebrate exocrine pancreas formation.
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Affiliation(s)
- Wei Qin
- Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, China
| | - Zelin Chen
- Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, China
| | - Yihan Zhang
- Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, China
| | - Ruibin Yan
- Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, China
| | - Guanrong Yan
- Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, China
| | - Song Li
- Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, China
| | - Hanbing Zhong
- Department of Biology, South University of Science and Technology of China, Shenzhen, Guangdong, China
| | - Shuo Lin
- Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, China
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, California, United States of America
- * E-mail:
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14
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Abstract
This review summarizes the current understanding of the role of nuclear bodies in regulating gene expression. The compartmentalization of cellular processes, such as ribosome biogenesis, RNA processing, cellular response to stress, transcription, modification and assembly of spliceosomal snRNPs, histone gene synthesis and nuclear RNA retention, has significant implications for gene regulation. These functional nuclear domains include the nucleolus, nuclear speckle, nuclear stress body, transcription factory, Cajal body, Gemini of Cajal body, histone locus body and paraspeckle. We herein review the roles of nuclear bodies in regulating gene expression and their relation to human health and disease.
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Affiliation(s)
| | - Cornelius F. Boerkoel
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-604-875-2157; Fax: +1-604-875-2376
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Fernandez-Garcia I, Marcos T, Muñoz-Barrutia A, Serrano D, Pio R, Montuenga LM, Ortiz-de-Solorzano C. Multiscale in situ analysis of the role of dyskerin in lung cancer cells. Integr Biol (Camb) 2013; 5:402-13. [PMID: 23233094 DOI: 10.1039/c2ib20219k] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Dyskerin is one of the three subunits of the telomerase ribonucleoprotein (RNP) complex. Very little is known about the role of dyskerin in the biology of the telomeres in cancer cells. In this study, we use a quantitative, multiscale 3D image-based in situ method and several molecular techniques to show that dyskerin is overexpressed in lung cancer cell lines. Furthermore, we show that dyskerin expression correlates with telomere length both at the cell population level--cells with higher dyskerin expression have short telomeres--and at the single cell level--the shortest telomeres of the cell are spatially associated with areas of concentration of dyskerin proteins. Using this in vitro model, we also show that exogenous increase in dyskerin expression confers resistance to telomere shortening caused by a telomerase inactivating drug. Finally, we show that resistance is achieved by the recovery of telomerase activity associated with dyskerin. In summary, using a novel multiscale image-based in situ method, we show that, in lung cancer cell lines, dyskerin responds to continuous telomere attrition by increasing the telomerase RNP activity, which in turn provides resistance to telomere shortening.
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Affiliation(s)
- Ignacio Fernandez-Garcia
- Oncology Division, Center for Applied Medical Research, CIMA, University of Navarra, Avda. Pio XII 55, Pamplona 31008, Spain
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16
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Brault ME, Lauzon C, Autexier C. Dyskeratosis congenita mutations in dyskerin SUMOylation consensus sites lead to impaired telomerase RNA accumulation and telomere defects. Hum Mol Genet 2013; 22:3498-507. [PMID: 23660516 DOI: 10.1093/hmg/ddt204] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Mutations in the dyskerin gene (DKC1) cause X-linked dyskeratosis congenita (DC), a rare and fatal premature aging syndrome characterized by defective telomere maintenance. Dyskerin is a highly conserved nucleolar protein, and a component of the human telomerase complex that is essential for human telomerase RNA (hTR) stability. However, its regulation remains poorly understood. Here, we report that dyskerin can be modified by small ubiquitin-like modifiers (SUMOs). We find that human DC-causing mutations in highly conserved dyskerin SUMOylation consensus sites lead to impaired hTR accumulation, telomerase activity and telomere maintenance. Finally, we show that modification of dyskerin by SUMOylation is required for its stability. Our findings provide the first evidence that dyskerin stability is regulated by SUMOylation and that mutations altering dyskerin SUMOylation can lead to defects in telomere maintenance that are characteristics of DC.
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Affiliation(s)
- Marie Eve Brault
- Bloomfield Centre for Research in Aging, Lady Davis Institute for Medical Research, Jewish General Hospital, 3775 Côte Ste Catherine Road, Montréal, QC H3T 1E2, Canada
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17
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Machado-Pinilla R, Liger D, Leulliot N, Meier UT. Mechanism of the AAA+ ATPases pontin and reptin in the biogenesis of H/ACA RNPs. RNA (NEW YORK, N.Y.) 2012; 18:1833-45. [PMID: 22923768 PMCID: PMC3446707 DOI: 10.1261/rna.034942.112] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The AAA+ ATPases pontin and reptin function in a staggering array of cellular processes including chromatin remodeling, transcriptional regulation, DNA damage repair, and assembly of macromolecular complexes, such as RNA polymerase II and small nucleolar (sno) RNPs. However, the molecular mechanism for all of these AAA+ ATPase associated activities is unknown. Here we document that, during the biogenesis of H/ACA RNPs (including telomerase), the assembly factor SHQ1 holds the pseudouridine synthase NAP57/dyskerin in a viselike grip, and that pontin and reptin (as components of the R2TP complex) are required to pry NAP57 from SHQ1. Significantly, the NAP57 domain captured by SHQ1 harbors most mutations underlying X-linked dyskeratosis congenita (X-DC) implicating the interface between the two proteins as a target of this bone marrow failure syndrome. Homing in on the essential first steps of H/ACA RNP biogenesis, our findings provide the first insight into the mechanism of action of pontin and reptin in the assembly of macromolecular complexes.
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Affiliation(s)
- Rosario Machado-Pinilla
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Dominique Liger
- Institut de Biochimie et de Biophysique Moléculaire et Cellulaire, Université de Paris-Sud, CNRS-UMR8619, IFR115, 91405 Orsay Cedex, France
| | - Nicolas Leulliot
- Laboratoire de Cristallographie et RMN Biologiques, UMR CNRS 8015, Université Paris Descartes, Sorbonne Paris Cité, Faculté des Sciences Pharmaceutiques et Biologiques, 75006 Paris, France
| | - U. Thomas Meier
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
- Corresponding authorE-mail
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Cantara S, Capuano S, Capezzone M, Benigni M, Pisu M, Marchisotta S, Pacini F. Lack of mutations of the telomerase RNA component in familial papillary thyroid cancer with short telomeres. Thyroid 2012; 22:363-8. [PMID: 22304389 DOI: 10.1089/thy.2011.0109] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND The occurrence of familial papillary thyroid cancer (FPTC) is well established but no susceptibility genes for this disease have been discovered. Our group has recently demonstrated that patients with FPTC have shorter telomeres, not associated with mutations in telomerase reverse transcriptase, gene than patients with sporadic papillary thyroid cancer (SPTC), healthy subjects (HS), and unaffected family members (UFMs). Several diseases, however, have short telomeres associated with mutations in the telomerase RNA component (TERC) gene or in the shelterin complex (POT1, RAP1, TIN2, TPP1, TRF1, and TRF2) genes. The objective of the present study was to verify whether short telomeres observed in FPTC patients were related to mutations in TERC or shelterin genes. METHODS Sixty-six patients with FPTC, 46 UFMs, 111 patients with SPTC, and 153 HS were analyzed by polymerase chain reaction followed by denaturing high performance liquid chromatography analysis and direct sequencing for the presence of TERC or shelterin gene mutations. When present, single-nucleotide polymorphisms were tested by χ(2) analysis at the genotypic, allelic, and haplotypic levels. RESULTS The entire sequence of the TERC gene was analyzed with particular attention to known mutations known to be associated with short telomeres. All samples appeared to be homozygous wild type for A-771G, C-99G, G305A, G322A, C323T, C408G, G450A, T467C, G508A, A514G, G623A, and C727G substitutions and for the 378Δ→3' deletion in the TERC gene. In addition, upon analysis of all samples for shelterin proteins, we observed a significant decrease in POT1 and RAP1 protein expression in the blood of FPTC patients compared with SPTC subjects. However, no mutations or polymorphisms were found when in the coding sequences of both genes. CONCLUSIONS To our knowledge this is the first study of TERC mutations or alterations in the shelterin complex in relation to FPTC. Shorter telomeres observed in FPTC are not linked to mutations or polymorphisms in TERC, POT1, or RAP1 genes.
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Affiliation(s)
- Silvia Cantara
- Section of Endocrinology & Metabolism, Department of Internal Medicine, Endocrinology & Metabolism, and Biochemistry, University of Siena, Siena, Italy.
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Kar B, Liu B, Zhou Z, Lam YW. Quantitative nucleolar proteomics reveals nuclear re-organization during stress- induced senescence in mouse fibroblast. BMC Cell Biol 2011; 12:33. [PMID: 21835027 PMCID: PMC3163619 DOI: 10.1186/1471-2121-12-33] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Accepted: 08/11/2011] [Indexed: 12/21/2022] Open
Abstract
Background Nucleolus is the most prominent mammalian organelle within the nucleus which is also the site for ribosomal biogenesis. There have been many reports indicating the involvement of nucleolus in the process of aging. Several proteins related to aging have been shown to localize in the nucleolus, which suggests the role of this organelle in senescence. Results In this study, we used quantitative mass spectrometry to map the flux of proteins into and out of the nucleolus during the induction of senescence in cultured mammalian cells. Changes in the abundance of 344 nucleolar proteins in sodium butyrate-induced senescence in NIH3T3 cells were studied by SILAC (stable isotope labeling by amino acids in cell culture)-based mass spectrometry. Biochemically, we have validated the proteomic results and confirmed that B23 (nucleophosmin) protein was down-regulated, while poly (ADP-ribose) polymerase (PARP) and nuclear DNA helicase II (NDH II/DHX9/RHA) were up-regulated in the nucleolus upon treatment with sodium butyrate. Accumulation of chromatin in the nucleolus was also observed, by both proteomics and microscopy, in sodium butyrate-treated cells. Similar observations were found in other models of senescence, namely, in mitoxantrone- (MTX) treated cells and primary fibroblasts from the Lamin A knockout mice. Conclusion Our data indicate an extensive nuclear organization during senescence and suggest that the redistribution of B23 protein and chromatin can be used as an important marker for senescence.
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Affiliation(s)
- Bishnupriya Kar
- Department of Biology and Chemistry, City University of Hong Kong, 88 Tat Chee Avenue, Hong Kong.
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20
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Németh A, Längst G. Genome organization in and around the nucleolus. Trends Genet 2011; 27:149-56. [DOI: 10.1016/j.tig.2011.01.002] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 01/03/2011] [Accepted: 01/04/2011] [Indexed: 10/18/2022]
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21
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Kishore S, Luber S, Zavolan M. Deciphering the role of RNA-binding proteins in the post-transcriptional control of gene expression. Brief Funct Genomics 2010; 9:391-404. [PMID: 21127008 DOI: 10.1093/bfgp/elq028] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Eukaryotic cells express a large variety of ribonucleic acid-(RNA)-binding proteins (RBPs) with diverse affinity and specificity towards target RNAs that play a crucial role in almost every aspect of RNA metabolism. In addition, specific domains in RBPs impart catalytic activity or mediate protein-protein interactions, making RBPs versatile regulators of gene expression. In this review, we elaborate on recent experimental and computational approaches that have increased our understanding of RNA-protein interactions and their role in cellular function. We review aspects of gene expression that are modulated post-transcriptionally by RBPs, namely the stability of polymerase II-derived mRNA transcripts and their rate of translation into proteins. We further highlight the extensive regulatory networks of RBPs that implement a combinatorial control of gene expression. Taking cues from the recent development in the field, we argue that understanding spatio-temporal RNA-protein association on a transcriptome level will provide invaluable and unexpected insights into the regulatory codes that define growth, differentiation and disease.
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22
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Németh A, Conesa A, Santoyo-Lopez J, Medina I, Montaner D, Péterfia B, Solovei I, Cremer T, Dopazo J, Längst G. Initial genomics of the human nucleolus. PLoS Genet 2010; 6:e1000889. [PMID: 20361057 PMCID: PMC2845662 DOI: 10.1371/journal.pgen.1000889] [Citation(s) in RCA: 279] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Accepted: 03/01/2010] [Indexed: 12/28/2022] Open
Abstract
We report for the first time the genomics of a nuclear compartment of the eukaryotic cell. 454 sequencing and microarray analysis revealed the pattern of nucleolus-associated chromatin domains (NADs) in the linear human genome and identified different gene families and certain satellite repeats as the major building blocks of NADs, which constitute about 4% of the genome. Bioinformatic evaluation showed that NAD–localized genes take part in specific biological processes, like the response to other organisms, odor perception, and tissue development. 3D FISH and immunofluorescence experiments illustrated the spatial distribution of NAD–specific chromatin within interphase nuclei and its alteration upon transcriptional changes. Altogether, our findings describe the nature of DNA sequences associated with the human nucleolus and provide insights into the function of the nucleolus in genome organization and establishment of nuclear architecture. It is becoming increasingly clear that the nuclear organization and location of genes in metazoan organisms is not random. Functionally related genes are often found next to each other in the linear genome, and distant DNA elements or DNA regions residing on different chromosomes may reside in specific nuclear compartments. The largest nuclear compartment is the nucleolus with its shell of perinucleolar DNA. The nature of the nucleolus-associated DNA, the targeting mechanism, and the cellular function of this subset of genomic DNA are not known. In the present study we report for the first time the high-resolution analysis of a nuclear compartment by sequencing, microarray analysis, and single-cell analysis. We have characterized the nucleolus-associated DNA on sequence level and by 3D microscopy and have determined common elements and the molecular function of this compartment.
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Affiliation(s)
- Attila Németh
- Department of Biochemistry III, University of Regensburg, Regensburg, Germany
| | - Ana Conesa
- Department of Bioinformatics and Genomics, Centro de Investigación Príncipe Felipe, Valencia, Spain
| | - Javier Santoyo-Lopez
- Department of Bioinformatics and Genomics, Centro de Investigación Príncipe Felipe, Valencia, Spain
| | - Ignacio Medina
- Department of Bioinformatics and Genomics, Centro de Investigación Príncipe Felipe, Valencia, Spain
| | - David Montaner
- Department of Bioinformatics and Genomics, Centro de Investigación Príncipe Felipe, Valencia, Spain
| | - Bálint Péterfia
- Department of Biochemistry III, University of Regensburg, Regensburg, Germany
| | - Irina Solovei
- Department of Biology II, Ludwig-Maximilians University of Munich, Planegg-Martinsried, Germany
| | - Thomas Cremer
- Department of Biology II, Ludwig-Maximilians University of Munich, Planegg-Martinsried, Germany
| | - Joaquin Dopazo
- Department of Bioinformatics and Genomics, Centro de Investigación Príncipe Felipe, Valencia, Spain
| | - Gernot Längst
- Department of Biochemistry III, University of Regensburg, Regensburg, Germany
- * E-mail:
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Grozdanov PN, Roy S, Kittur N, Meier UT. SHQ1 is required prior to NAF1 for assembly of H/ACA small nucleolar and telomerase RNPs. RNA (NEW YORK, N.Y.) 2009; 15:1188-97. [PMID: 19383767 PMCID: PMC2685518 DOI: 10.1261/rna.1532109] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Assembly of H/ACA RNPs in yeast is aided by at least two accessory factors, Naf1p and Shq1p. Although the function of Naf1p and its human ortholog NAF1 has been delineated in detail, that of Shq1p and its putative human ortholog SHQ1 remains obscure. We demonstrate that SHQ1 indeed functions in the biogenesis of human H/ACA RNPs and we dissect its mechanism of action. Like NAF1, SHQ1 binds the major H/ACA core protein and pseudouridine synthase NAP57 (aka dyskerin) but precedes the assembly role of NAF1 at nascent H/ACA RNAs because the interaction of SHQ1 with NAP57 in vivo and in vitro precludes that of NAF1 and of the other H/ACA core proteins that are present at the sites of H/ACA RNA transcription. The N-terminal heat shock protein 20-like CS domain of SHQ1 is dispensable for NAP57 binding. Consistent with its role as an assembly factor, SHQ1 localizes to the nucleoplasm and is excluded from nucleoli and Cajal bodies, the sites of mature H/ACA RNPs. In an in vitro assembly system of functional H/ACA RNPs that is dependent on NAF1, excess recombinant SHQ1 interferes with assembly. Importantly, knockdown of cellular SHQ1 prevents accumulation of a newly synthesized H/ACA reporter RNA and generally reduces the levels of endogenous H/ACA RNAs including telomerase RNA. In summary, the sequential action of SHQ1 and NAF1 is required for functional assembly of H/ACA RNPs in vivo and in vitro. This step-wise process could serve as an efficient means of quality control during H/ACA RNP assembly.
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Affiliation(s)
- Petar N Grozdanov
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461, USA
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25
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Dyskeratosis congenita: The diverse clinical presentation of mutations in the telomerase complex. Biochimie 2008; 90:122-30. [DOI: 10.1016/j.biochi.2007.07.017] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2007] [Accepted: 07/22/2007] [Indexed: 12/23/2022]
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Lermontova I, Schubert V, Börnke F, Macas J, Schubert I. Arabidopsis CBF5 interacts with the H/ACA snoRNP assembly factor NAF1. PLANT MOLECULAR BIOLOGY 2007; 65:615-26. [PMID: 17712600 DOI: 10.1007/s11103-007-9226-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2007] [Accepted: 08/09/2007] [Indexed: 05/11/2023]
Abstract
The conserved protein CBF5, initially regarded as a centromere binding protein in yeast and higher plants, was later found within nucleoli and in Cajal bodies of yeast and metazoa. There, it is assumed to be involved in posttranscriptional pseudouridinylation of various RNA species that might be important for RNA processing. We found EYFP-labeled CBF5 of A. thaliana to be located within nucleoli and Cajal bodies, but neither at centromeres nor somewhere else on chromosomes. Arabidopsis mutants carrying a homozygous T-DNA insertion at the CBF5 locus were lethal. Yeast two-hybrid and mRNA expression analyses demonstrated that AtCBF5 is co-expressed and interacts with a previously uncharacterized protein containing a conserved NAF1 domain, presumably involved in H/ACA box snoRNP biogenesis. The homologous yeast protein has been shown to contribute to RNA pseudouridinylation. Thus, AtCBF5 might have an essential function in RNA processing rather than being a kinetochore protein.
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Affiliation(s)
- Inna Lermontova
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), 06466 Gatersleben, Germany.
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27
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Boisvert FM, van Koningsbruggen S, Navascués J, Lamond AI. The multifunctional nucleolus. Nat Rev Mol Cell Biol 2007; 8:574-85. [PMID: 17519961 DOI: 10.1038/nrm2184] [Citation(s) in RCA: 1143] [Impact Index Per Article: 67.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The nucleolus is a distinct subnuclear compartment that was first observed more than 200 years ago. Nucleoli assemble around the tandemly repeated ribosomal DNA gene clusters and 28S, 18S and 5.8S ribosomal RNAs (rRNAs) are transcribed as a single precursor, which is processed and assembled with the 5S rRNA into ribosome subunits. Although the nucleolus is primarily associated with ribosome biogenesis, several lines of evidence now show that it has additional functions. Some of these functions, such as regulation of mitosis, cell-cycle progression and proliferation, many forms of stress response and biogenesis of multiple ribonucleoprotein particles, will be discussed, as will the relation of the nucleolus to human diseases.
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MESH Headings
- Animals
- Cell Nucleolus/chemistry
- Cell Nucleolus/genetics
- Cell Nucleolus/metabolism
- Cell Nucleolus/physiology
- Cell Nucleolus/ultrastructure
- DNA, Ribosomal/analysis
- DNA, Ribosomal/biosynthesis
- Fluorescent Dyes
- Humans
- Indoles
- Microscopy, Fluorescence
- Mitosis
- Models, Biological
- Nucleolus Organizer Region/physiology
- Nucleolus Organizer Region/ultrastructure
- RNA Precursors/metabolism
- RNA, Ribosomal/genetics
- RNA, Ribosomal/metabolism
- RNA, Ribosomal, 18S/genetics
- RNA, Ribosomal, 18S/metabolism
- RNA, Ribosomal, 28S/genetics
- RNA, Ribosomal, 28S/metabolism
- RNA, Ribosomal, 5.8S/genetics
- RNA, Ribosomal, 5.8S/metabolism
- RNA, Ribosomal, 5S/biosynthesis
- RNA, Ribosomal, 5S/genetics
- RNA, Small Nucleolar/genetics
- RNA, Small Nucleolar/metabolism
- Ribonucleoproteins/genetics
- Ribonucleoproteins/metabolism
- Ribosomes/genetics
- Ribosomes/metabolism
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28
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The coding/non-coding overlapping architecture of the gene encoding the Drosophila pseudouridine synthase. BMC Mol Biol 2007; 8:15. [PMID: 17328797 PMCID: PMC1821038 DOI: 10.1186/1471-2199-8-15] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2006] [Accepted: 02/28/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In eukaryotic cells, each molecule of H/ACA small nucleolar RNA (snoRNA) assembles with four evolutionarily conserved core proteins to compose a specific ribonucleoprotein particle. One of the four core components has pseudouridine synthase activity and catalyzes the conversion of a selected uridine to pseudouridine. Members of the pseudouridine synthase family are highly conserved. In addition to catalyzing pseudouridylation of target RNAs, they carry out a variety of essential functions related to ribosome biogenesis and, in mammals, to telomere maintenance. To investigate further the molecular mechanisms underlying the expression of pseudouridine synthase genes, we analyzed the transcriptional activity of the Drosophila member of this family in great detail. RESULTS The Drosophila gene for pseudouridine synthase, minifly/Nop60b (mfl), encodes two novel mRNAs ending at a downstream poly(A) site. One species is characterized only by an extended 3'-untranslated region (3'UTR), while a minor mRNA encodes a variant protein that represents the first example of an alternative subform described for any member of the family to date. The rare spliced variant is detected mainly in females and is predicted to have distinct functional properties. We also report that a cluster comprising four isoforms of a C/D box snoRNA and two highly related copies of a small ncRNA gene of unknown function is intron-encoded at the gene-variable 3'UTRs. Because this arrangement, the alternative 3' ends allow mfl not only to produce two distinct protein subforms, but also to release different ncRNAs. Intriguingly, accumulation of all these intron-encoded RNAs was found to be sex-biased and quantitatively modulated throughout development and, within the ovaries, the ncRNAs of unknown function were found not ubiquitously expressed. CONCLUSION Our results expand the repertoire of coding/non-coding transcripts derived from the gene encoding Drosophila pseudouridine synthase. This gene exhibits a complex and interlaced organization, and its genetic information may be expressed as different protein subforms and/or ncRNAs that may potentially contribute to its biological functions.
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Kittur N, Darzacq X, Roy S, Singer RH, Meier UT. Dynamic association and localization of human H/ACA RNP proteins. RNA (NEW YORK, N.Y.) 2006; 12:2057-62. [PMID: 17135485 PMCID: PMC1664726 DOI: 10.1261/rna.249306] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Mammalian H/ACA RNPs are essential for ribosome biogenesis, pre-mRNA splicing, and telomere maintenance. To form mature RNA-protein complexes, one H/ACA RNA associates with four core proteins. In the cell, this process is assisted by at least one nuclear assembly factor, NAF1. Here we report several unanticipated dynamic aspects of H/ACA RNP proteins. First, when overexpressed, NAF1 delocalizes to the cytoplasm. However, its nucleocytoplasmic shuttling properties remain unaffected. These observations demonstrate a subtle equilibrium between NAF1 expression levels and the availability of NAF1 nuclear binding sites. Second, although NAF1 is excluded from mature RNPs in nucleoli and Cajal bodies, NAF1 associates with mature H/ACA RNA in cell lysates. This association occurs post-lysis because it is observed even when NAF1 and the H/ACA RNA are expressed in separate cells. This documents a protein-RNP association in cell lysates that is absent from intact cells. Third, in similar experiments, all H/ACA core proteins, except NAP57, exchange with their exogenous counterparts, portraying an unexpected dynamic picture of H/ACA RNPs. Finally, the irreversible association of only NAP57 with H/ACA RNA and the conundrum that only NAP57 is mutated in X-linked dyskeratosis congenita (even though most core proteins are required for maintaining H/ACA RNAs) may be more than a coincidence.
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Affiliation(s)
- Nupur Kittur
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York, New York 10461, USA
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30
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Normand C, Capeyrou R, Quevillon-Cheruel S, Mougin A, Henry Y, Caizergues-Ferrer M. Analysis of the binding of the N-terminal conserved domain of yeast Cbf5p to a box H/ACA snoRNA. RNA (NEW YORK, N.Y.) 2006; 12:1868-82. [PMID: 16931875 PMCID: PMC1581976 DOI: 10.1261/rna.141206] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
During ribosome biogenesis, the RNA precursor to mature rRNAs undergoes numerous post-transcriptional chemical modifications of bases, including conversions of uridines to pseudouridines. In archaea and eukaryotes, these conversions are performed by box H/ACA small ribonucleoprotein particles (box H/ACA RNPs), which contain a small guide RNA responsible for the selection of substrate uridines and four proteins, including the pseudouridine synthase, Cbf5p. So far, no in vitro reconstitution of eukaryotic box H/ACA RNPs from purified components has been achieved, principally due to difficulties in purifying recombinant eukaryotic Cbf5p. In this study, we present the purification of a truncated derivative of yeast Cbf5p (Cbf5(Delta)p) that retains the highly conserved TRUB and PUA domains. We have used band retardation assays to show that Cbf5(Delta)p on its own binds to box H/ACA small nucleolar (sno)RNAs. We demonstrate that the conserved H and ACA boxes enhance the affinity of the protein for the snoRNA. Furthermore, like its archaeal homologs, Cbf5(Delta)p can bind to a single stem-loop-box ACA RNA. Finally, we report the first enzymatic footprinting analysis of a Cbf5-RNA complex. Our results are compatible with the view that two molecules of Cbf5p interact with a binding platform constituted by the 5' end of the RNA, the single-stranded hinge domain containing the conserved H box, and the 3' end of the molecule, including the conserved ACA box.
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MESH Headings
- Amino Acid Sequence
- Base Sequence
- Binding Sites/genetics
- Conserved Sequence
- Hydro-Lyases/chemistry
- Hydro-Lyases/genetics
- Hydro-Lyases/metabolism
- Microtubule-Associated Proteins/chemistry
- Microtubule-Associated Proteins/genetics
- Microtubule-Associated Proteins/metabolism
- Molecular Sequence Data
- Nucleic Acid Conformation
- Protein Binding
- Protein Footprinting
- Protein Structure, Tertiary
- RNA, Fungal/chemistry
- RNA, Fungal/genetics
- RNA, Fungal/metabolism
- RNA, Small Nucleolar/chemistry
- RNA, Small Nucleolar/genetics
- RNA, Small Nucleolar/metabolism
- Recombinant Proteins/chemistry
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Ribonucleases
- Ribonucleoproteins, Small Nuclear/chemistry
- Ribonucleoproteins, Small Nuclear/genetics
- Ribonucleoproteins, Small Nuclear/metabolism
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
- Saccharomyces cerevisiae Proteins/chemistry
- Saccharomyces cerevisiae Proteins/genetics
- Saccharomyces cerevisiae Proteins/metabolism
- Sequence Homology, Amino Acid
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Affiliation(s)
- Christophe Normand
- Equipe Labellisée Ligue Nationale contre le Cancer, Laboratoire de Biologie Moléculaire Eucaryote, UMR5099, CNRS-Université Paul Sabatier, IFR 109, Toulouse, France, European Union
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31
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Zhang S, Shi M, Hui CC, Rommens JM. Loss of the mouse ortholog of the shwachman-diamond syndrome gene (Sbds) results in early embryonic lethality. Mol Cell Biol 2006; 26:6656-63. [PMID: 16914746 PMCID: PMC1592835 DOI: 10.1128/mcb.00091-06] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mutations in SBDS are responsible for Shwachman-Diamond syndrome (SDS), a disorder with clinical features of exocrine pancreatic insufficiency, bone marrow failure, and skeletal abnormalities. SBDS is a highly conserved protein whose function remains largely unknown. We identified and investigated the expression pattern of the murine ortholog. Variation in levels was observed, but Sbds was found to be expressed in all embryonic stages and most adult tissues. Higher expression levels were associated with rapid proliferation. A targeted disruption of Sbds was generated in order to understand the consequences of its loss in an in vivo model. Consistent with recessive disease inheritance for SDS, Sbds(+/-) mice have normal phenotypes, indistinguishable from those of their wild-type littermates. However, the development of Sbds(-/-) embryos arrests prior to embryonic day 6.5, with muted epiblast formation leading to early lethality. This finding is consistent with the absence of patients who are homozygous for early truncating mutations. Sbds is an essential gene for early mammalian development, with an expression pattern consistent with a critical role in cell proliferation.
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Affiliation(s)
- Siyi Zhang
- Research Institute, Program in Genetics and Genomic Biology, Room 15-313 TMDT, 101 College Street, East Tower, Toronto, Ontario M5G 1L7, Canada
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32
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Hernandez-Verdun D. The nucleolus: a model for the organization of nuclear functions. Histochem Cell Biol 2006; 126:135-48. [PMID: 16835752 DOI: 10.1007/s00418-006-0212-3] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/07/2006] [Indexed: 10/24/2022]
Abstract
Nucleoli are the prominent contrasted structures of the cell nucleus. In the nucleolus, ribosomal RNAs (rRNAs) are synthesized, processed and assembled with ribosomal proteins. The size and organization of the nucleolus are directly related to ribosome production. The organization of the nucleolus reveals the functional compartmentation of the nucleolar machineries that depends on nucleolar activity. When this activity is blocked, disrupted or impossible, the nucleolar proteins have the capacity to interact independently of the processing activity. In addition, nucleoli are dynamic structures in which nucleolar proteins rapidly associate and dissociate with nucleolar components in continuous exchanges with the nucleoplasm. At the time of nucleolar assembly, the processing machineries are recruited in a regulated manner in time and space, controlled by different kinases and form intermediate structures, the prenucleolar bodies. The participation of stable pre-rRNAs in nucleolar assembly was demonstrated after mitosis and during development but this is an intriguing observation since the role of these pre-rRNAs is presently unknown. A brief report on the nucleolus and diseases is proposed as well as of nucleolar functions different from ribosome biogenesis.
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Affiliation(s)
- Danièle Hernandez-Verdun
- Nuclei and Cell Cycle, Institut Jacques Monod, CNRS, Université Paris VI, Université Paris VII, 2 place Jussieu, 75251 Paris Cedex 05, France.
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Abstract
Dyskeratosis congenita (DC) is a rare inherited multi-system disorder. Although DC is classically characterized by mucocutaneous features, the vast majority of patients develop hematologic abnormalities, and in its occult form the disease can present as aplastic anemia. The gene responsible for the X-linked form of the disease encodes a protein involved in ribosome biogenesis and in stabilizing the telomerase complex, while the autosomal dominant form is caused by mutations in the core RNA component of telomerase. It has been suggested that DC is primarily a disease of defective telomere maintenance. Premature shortening of telomeres resulting in a limited proliferative potential of stem cells would explain the pathology observed in DC, as the affected tissues are those that require constant renewal.
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Affiliation(s)
- Tom Vulliamy
- Department of Haematology, Division of Investigative Science, Faculty of Medicine, Imperial College, Hammersmith Hospital, London, UK.
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Fernandes Gomes M, Pinheiro de Abreu P, de Freitas Banzi C, de Oliveira Nogueira T. Interdisciplinary approach to treat dyskeratosis congenita associated with severe aplastic anemia: A case report. SPECIAL CARE IN DENTISTRY 2006; 26:81-4. [PMID: 16681244 DOI: 10.1111/j.1754-4505.2006.tb01515.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This paper reports on a 4-year-old male who had dyskeratosis congenita and who acquired severe aplastic anemia. The patient developed hyperpigmentation of the face, neck and chest region, arms, shoulders and legs. In addition, he had dry skin, deformed fingernails and toenails, sparse hair and eyebrows and hyperkeratosis of the dorsum of the hands and feet. Laboratory and histological analysis revealed severe pancytopenia and dyserythropoiesis of red blood cells, hypocellularity of white blood cells and decreased megakaryocytes with dysplasia. The intraoral examination identified bleeding gums; petechiae of the palate, tongue and cheek mucosa; and an atrophic, smooth and shining dorsal surface of the tongue. There were deep carious lesions in the deciduous mandibular molars and maxillary anterior teeth; as well as mobility of mandibular left canine, which had bone loss. The treatment for oral lesions included diet changes, improved oral hygiene, and extraction of the deciduous teeth destroyed by caries.
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Affiliation(s)
- Mônica Fernandes Gomes
- Department of Biosciences and Oral Diagnosis, São Jose dos Campos Dental School - São Paulo State University - UNESP, Brazil.
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35
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Yang H, Henning D, Valdez BC. Functional interaction between RNA helicase II/Gu(alpha) and ribosomal protein L4. FEBS J 2005; 272:3788-802. [PMID: 16045751 DOI: 10.1111/j.1742-4658.2005.04811.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
RNA helicase II/Gu(alpha) is a multifunctional nucleolar protein involved in ribosomal RNA processing in Xenopus laevis oocytes and mammalian cells. Downregulation of Gu(alpha) using small interfering RNA (siRNA) in HeLa cells resulted in 80% inhibition of both 18S and 28S rRNA production. The mechanisms underlying this effect remain unclear. Here we show that in mammalian cells, Gu(alpha) physically interacts with ribosomal protein L4 (RPL4), a component of 60S ribosome large subunit. The ATPase activity of Gu(alpha) is important for this interaction and is also necessary for the function of Gu(alpha) in the production of both 18S and 28S rRNAs. Knocking down RPL4 expression using siRNA in mouse LAP3 cells inhibits the production of 47/45S, 32S, 28S, and 18S rRNAs. This inhibition is reversed by exogenous expression of wild-type human RPL4 protein but not the mutant form lacking Gu(alpha)-interacting motif. These observations have suggested that the function of Gu(alpha) in rRNA processing is at least partially dependent on its ability to interact with RPL4.
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Affiliation(s)
- Hushan Yang
- Department of Pharmacology, Baylor College of Medicine, Houston, TX 77030, USA
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36
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Charpentier B, Muller S, Branlant C. Reconstitution of archaeal H/ACA small ribonucleoprotein complexes active in pseudouridylation. Nucleic Acids Res 2005; 33:3133-44. [PMID: 15933208 PMCID: PMC1142404 DOI: 10.1093/nar/gki630] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Pseudouridine (Ψ) are frequently modified residues in RNA. In Eukarya, their formation is catalyzed by enzymes or by ribonucleoprotein complexes (RNPs) containing H/ACA snoRNAs. H/ACA sRNA and putative ORFs for H/ACA sRNP proteins (L7Ae, aCBF5, aNOP10 and aGAR1) were found in Archaea. Here, by using Pyrococcus abyssi recombinant proteins and an in vitro transcribed P.abyssi H/ACA sRNA, we obtained the first complete in vitro reconstitution of an active H/ACA RNP. Both L7Ae and the aCBF5 RNA:Ψ synthase bind directly the sRNA; aCBF5 also interacts directly and independently with aNOP10 and aGAR1. Presence of aCBF5, aNOP10 and a U residue at the pseudouridylation site in the target RNA are required for RNA target recruitment. In agreement, we found that the aCBF5–aNOP10 pair is the minimal set of proteins needed for the formation of a particle active for pseudouridylation. However, particles more efficient in targeted pseudouridylation can be formed with the addition of proteins L7Ae and/or aGAR1. Although necessary for optimal activity, the conserved ACA motif in the sRNA was found to be not essential.
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Affiliation(s)
- Bruno Charpentier
- Laboratoire de Maturation des ARN et Enzymologie Moléculaire, UMR 7567 UHP-CNRS, Université des Sciences et Techniques Henri Poincaré Nancy I 54506 Vandoeuvre-Lès-Nancy cedex, France.
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Meier UT. The many facets of H/ACA ribonucleoproteins. Chromosoma 2005; 114:1-14. [PMID: 15770508 PMCID: PMC4313906 DOI: 10.1007/s00412-005-0333-9] [Citation(s) in RCA: 215] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2004] [Revised: 01/31/2005] [Accepted: 02/01/2005] [Indexed: 10/25/2022]
Abstract
The H/ACA ribonucleoproteins (RNPs) are known as one of the two major classes of small nucleolar RNPs. They predominantly guide the site-directed pseudouridylation of target RNAs, such as ribosomal and spliceosomal small nuclear RNAs. In addition, they process ribosomal RNA and stabilize vertebrate telomerase RNA. Taken together, the function of H/ACA RNPs is essential for ribosome biogenesis, pre-mRNA splicing, and telomere maintenance. Every cell contains 100-200 different species of H/ACA RNPs, each consisting of the same four core proteins and one function-specifying H/ACA RNA. Most of these RNPs reside in nucleoli and Cajal bodies and mediate the isomerization of specific uridines to pseudouridines. Catalysis of the reaction is mediated by the putative pseudouridylase NAP57 (dyskerin, Cbf5p). Unexpectedly, mutations in this housekeeping enzyme are the major determinants of the inherited bone marrow failure syndrome dyskeratosis congenita. This review details the many diverse functions of H/ACA RNPs, some yet to be uncovered, with an emphasis on the role of the RNP proteins. The multiple functions of H/ACA RNPs appear to be reflected in the complex phenotype of dyskeratosis congenita.
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Affiliation(s)
- U Thomas Meier
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
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Hawse JR, Hejtmancik JF, Horwitz J, Kantorow M. Identification and functional clustering of global gene expression differences between age-related cataract and clear human lenses and aged human lenses. Exp Eye Res 2005; 79:935-40. [PMID: 15642332 PMCID: PMC1351355 DOI: 10.1016/j.exer.2004.04.007] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2004] [Accepted: 04/07/2004] [Indexed: 10/26/2022]
Abstract
We have examined the gene expression profiles of young, old and cataractous human lenses in order to differentiate those gene expression changes specific for cataract from those also associated with lens aging. Differentially expressed transcripts were identified by oligonucleotide microarray analysis and clustered according to their known functions. Four hundred and twelve transcripts that are increased and 919 transcripts that are decreased were identified at the 2-fold or greater level between epithelia isolated from cataract relative to clear lenses while 182 transcripts that are increased and 547 transcripts that are decreased were identified at the 2-fold or greater level between young and old lens epithelia. Comparison of the cataract gene expression changes with those detected in lens aging revealed that only 3 transcripts exhibited similar trends in gene expression. These data suggest that cataract- and age-specific changes in gene expression do not overlap and provide evidence for multiple cataract- and age-specific gene expression changes in the human lens.
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Affiliation(s)
- J R Hawse
- Department of Biomedical Sciences, Charles E. Schmidt College of Science, Florida Atlantic University, 777 Glades Road, PO Box 3091, Boca Raton, FL 33431-0991, USA
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Abstract
Dyskeratosis congenita (DC) is an inherited bone marrow failure syndrome exhibiting considerable clinical and genetic heterogeneity. X-linked recessive, autosomal dominant and autosomal recessive forms are recognised. The gene mutated in X-linked DC (DKC1) encodes a highly conserved nucleolar protein called dyskerin. Dyskerin associates with the H/ACA class of small nucleolar RNAs which are important in guiding the conversion of uracil to pseudouracil in ribosomal RNA. Dyskerin also associates with the RNA component of telomerase (hTR) which is important in the maintenance of telomeres. Mutations in hTR were recently demonstrated in patients with autosomal dominant DC and in a subset of patients with aplastic anaemia (AA) but without other diagnostic features of DC. This discovery demonstrates that both DC and a subset of AA are due to a defect in telomerase. The link between DC and AA and in turn to defective telomerase suggests that treatments directed at correction of telomerase activity might benefit DC/AA patients who do not respond to conventional therapy.
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Affiliation(s)
- Inderjeet Dokal
- Department of Haematology-Division of Investigative Science, Faculty of Medicine, Imperial College, Hammersmith Hospital, Commonwealth Building, London, UK.
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Wang C, Meier UT. Architecture and assembly of mammalian H/ACA small nucleolar and telomerase ribonucleoproteins. EMBO J 2004; 23:1857-67. [PMID: 15044956 PMCID: PMC394235 DOI: 10.1038/sj.emboj.7600181] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2004] [Accepted: 03/03/2004] [Indexed: 11/08/2022] Open
Abstract
Mammalian H/ACA small nucleolar RNAs and telomerase RNA share common sequence and secondary structure motifs that form ribonucleoprotein particles (RNPs) with the same four core proteins, NAP57 (also dyskerin or in yeast Cbf5p), GAR1, NHP2, and NOP10. The assembly and molecular interactions of the components of H/ACA RNPs are unknown. Using in vitro transcription/translation in combination with immunoprecipitation of core proteins, UV-crosslinking, and electrophoretic mobility shift assays, we demonstrate the following. NOP10 associates with NAP57 as a prerequisite for NHP2 binding. Although NHP2 on its own binds RNA nonspecifically, this NAP57-NOP10-NHP2 core trimer specifically recognizes H/ACA RNAs. GAR1 associates independently with NAP57 near the pseudouridylase core of mature H/ACA RNPs. In contrast to other RNPs whose assembly is initiated by protein-RNA interactions, the four H/ACA core proteins form a protein-only particle that associates with H/ACA RNAs. Nonetheless, functional H/ACA snoRNPs assembled in cytosolic extracts are stable and do not exchange their RNA components, suggesting that new particle formation requires de novo synthesis.
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Affiliation(s)
- Chen Wang
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, NY, USA
| | - U Thomas Meier
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, NY, USA
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA. Tel.: +1 718 430 3294; Fax: +1 718 430 8996; E-mail:
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Abstract
In plants, as in all eukaryotes, centromeres are chromatin domains that govern the transmission of nuclear chromosomes to the next generation of cells/individuals. The DNA composition and sequence organization of centromeres has recently been elucidated for a few plant species. Although there is little sequence conservation among centromeres, they usually contain tandem repeats and retroelements. The occurrence of neocentromeres reinforces the idea that the positions of centromeres are determined epigenetically. In contrast to centromeric DNA, structural and transient kinetochoric proteins are highly conserved among eukaryotes. Candidate sequences have been identified for a dozen putative kinetochore protein homologues, and some have been localized to plant centromeres. The kinetochore protein CENH3, which substitutes histone H3 within centromeric nucleosomes, co-immunoprecipitates preferentially with centromeric sequences. The mechanism(s) of centromere assembly and the functional implication of (peri-)centromeric modifications of chromatin remain to be elucidated.
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Affiliation(s)
- Andreas Houben
- Chromosome Structure and Function Group, 06466 Gatersleben, Germany.
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Montanaro L, Tazzari PL, Derenzini M. Enhanced telomere shortening in transformed lymphoblasts from patients with X linked dyskeratosis. J Clin Pathol 2003; 56:583-6. [PMID: 12890806 PMCID: PMC1770038 DOI: 10.1136/jcp.56.8.583] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AIM Dyskeratosis congenita (DC) is characterised by the failure of those tissues that are rapidly dividing in the adult, particularly the skin, mucosae, and haemopoietic system. The X linked form of the disease is caused by mutations of the DKC1 gene, which encodes dyskerin, a protein that is necessary for the function of telomerase. Cultured DC lymphoblastoid cells are characterised by a reduced expansion of the cell population because of the progressive increase in apoptosis compared with the number of cell divisions. This report aimed to verify whether this is caused by a defect in telomerase function. METHODS Variations in telomere length over time were evaluated in two cultured lymphoblastoid cell lines derived from patients with X linked DC and control cells derived from a non-affected individual. In addition, the effect of inhibiting poly (ADP-ribose) polymerase (PARP), which is involved in the cellular response to excessive telomere shortening, was assessed. One DC cell line and the control cells were treated with the specific PARP inhibitor 1,5-dihydroxyquinoline (IQ). RESULTS In DC cells the increase in cell death was associated with progressive telomere shortening, and this was not seen in the control cells. Treatment with IQ delayed the increase of apoptosis in DC cells. CONCLUSIONS These observations indicate that the reduced expansion that characterises cultured cells obtained from patients with X linked DC is caused by premature telomere shortening.
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Affiliation(s)
- L Montanaro
- Università degli Studi di Bologna, Dipartimento di Patologia Sperimentale, via S. Giacomo 14, 40126 Bologna, Italy.
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Lam YW, Lyon CE, Lamond AI. Large-scale isolation of Cajal bodies from HeLa cells. Mol Biol Cell 2002; 13:2461-73. [PMID: 12134083 PMCID: PMC117327 DOI: 10.1091/mbc.02-03-0034] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2001] [Revised: 02/20/2002] [Accepted: 04/05/2002] [Indexed: 11/11/2022] Open
Abstract
The Cajal body (CB) is a conserved, dynamic nuclear structure that is implicated in various cellular processes, such as the maturation of splicing small nuclear ribonucleoproteins and the assembly of transcription complexes. Here, we report the first procedure for the large-scale purification of CBs from HeLa cell nuclei, resulting in an approximately 750-fold enrichment of the CB marker protein p80-coilin. Immunofluorescence, immunoblotting, and mass spectrometric analyses showed that the composition of the isolated CBs was similar to that of CBs in situ. The morphology and structure of the isolated CBs, as judged by transmission and scanning electron microscopy analysis, are also similar to those of CBs in situ. This protocol demonstrates the feasibility of isolating intact distinct classes of subnuclear bodies from cultured cells in sufficient yield and purity to allow detailed characterization of their molecular composition, structure, and properties.
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Affiliation(s)
- Yun Wah Lam
- Wellcome Trust Biocentre, MSI/WTB Complex, University of Dundee, Dundee DD1 4HN, Scotland, United Kingdom
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Salowsky R, Heiss NS, Benner A, Wittig R, Poustka A. Basal transcription activity of the dyskeratosis congenita gene is mediated by Sp1 and Sp3 and a patient mutation in a Sp1 binding site is associated with decreased promoter activity. Gene 2002; 293:9-19. [PMID: 12137939 DOI: 10.1016/s0378-1119(02)00725-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The multisystem disorder dyskeratosis congenita (DKC) is caused by mutations in the DKC1 gene. The protein dyskerin is a component of the box H+ACA small nucleolar RNAs (snoRNAs) and is also functionally associated with the RNA component of the human telomerase. The majority of mutations are missense mutations, although single examples of non-coding mutations have been described. One of these is a point mutation in a putative Sp1 binding site in the 5'-upstream region of the DKC1 gene which presumably represents the promoter region of the gene. In this report, we compare the promoter sequences of both the human and mouse genes and provide a first functional characterisation of the human DKC1 promoter. This includes a characterisation of the disease-associated implications caused by the mutation identified in one patient. By reporter gene analysis, functional regions of the DKC1 promoter were delineated. The core promoter region critical for basal level of transcription was found to lie at -10 to -180. Bandshift- and supershift experiments clearly demonstrated a mutual binding of transcription factors Sp1 and Sp3 to two of five putative GC-box/Sp1-binding sites located within the core promoter region. An additional GC-box interacts only with the Sp1 transcription factor. Further, we provide evidence that the DKC1 mutation in one of the Sp1 binding sites results in reduced promoter activity.
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Affiliation(s)
- Rüdiger Salowsky
- Division of Molecular Genome Analysis, Deutsches Krebsforschungszentrum (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
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46
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Abstract
The intent of this review is to describe what is known and unknown about telomerase in somatic cells of the human organism. First, we consider the telomerase enzyme. Human telomerase ribonucleoproteins undergo at least three stages of cellular biogenesis: accumulation, catalytic activation and recruitment to the telomere. Next, we describe the patterns of telomerase regulation in the human soma. Telomerase activation in some cell types appears to offset proliferation-dependent telomere shortening, delaying but not defeating the inherent mitotic clock. Finally, we elaborate the connection between telomerase misregulation and human disease, in the contexts of inappropriate telomerase activation and telomerase deficiency. We discuss how our current perspectives on telomerase function could be applied to improving human health.
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Affiliation(s)
- Kathleen Collins
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California, CA 94720-3204, USA.
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Montanaro L, Chillà A, Trerè D, Pession A, Govoni M, Tazzari PL, Derenzini M. Increased mortality rate and not impaired ribosomal biogenesis is responsible for proliferative defect in dyskeratosis congenita cell lines. J Invest Dermatol 2002; 118:193-8. [PMID: 11851894 DOI: 10.1046/j.0022-202x.2001.01634.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
X-linked dyskeratosis congenita is a rare inherited disorder mainly characterized by progressive changes in proliferating epidermal, mucosal, and bone marrow tissues that commonly emerge after 10 y of life. It is caused by mutations of the DKC1 gene, which codes for dyskerin, a protein that may play a role in ribosomal biogenesis. In order to verify whether the defects of proliferating tissues observed in dyskeratosis congenita are due to an altered ribosome synthesis, we studied ribosomal biogenesis in relation to cell proliferation in two lymphoblastoid cell lines from dyskeratosis congenita patients and in one control line. We observed that in the dyskeratosis congenita cell lines the rRNA transcription and maturation and proliferative capability remained unimpaired. Increasing the number of cell cycles, however, leads to a steep rise in the apoptotic fraction of dyskeratosis congenita cells, which is not observed in controls. These findings demonstrate that whereas dyskeratosis congenita cell lines do not display proliferation defects, they do show progressively increasing levels of apoptosis in relation to the number of cell divisions. This concept is consistent with (i) the delayed onset of dyskeratosis congenita proliferating-tissue defects, which do not emerge during embrional development as would be expected with ribosomal biogenesis alterations, and (ii) with the increasing severity of the proliferating-tissue defects over time.
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Affiliation(s)
- Lorenzo Montanaro
- Dipartimento di Patologia Sperimentale, Università degli Studi di Bologna, Bologna, Italy.
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48
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Dokal I. The Inherited Bone Marrow Failure Syndromes: Fanconi Anemia, Dyskeratosis Congenita and Diamond‐Blackfan Anemia. ACTA ACUST UNITED AC 2001. [DOI: 10.1046/j.1468-0734.2000.00015.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Inderjeet Dokal
- Department of Haematology, Hammersmith Hospital and Imperial College School of Medicine, London, UK
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Ogris M, Carlisle RC, Bettinger T, Seymour LW. Melittin enables efficient vesicular escape and enhanced nuclear access of nonviral gene delivery vectors. J Biol Chem 2001; 276:47550-5. [PMID: 11600500 DOI: 10.1074/jbc.m108331200] [Citation(s) in RCA: 176] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Entry of exogenously applied DNA into the cytoplasm and subsequent transport into the nucleus are major cellular barriers for nonviral gene delivery vectors. To overcome these barriers, we have covalently attached the cationic peptide melittin to poly(ethylenimine) (PEI). This conjugate condensed DNA into small, discrete particles (<100 nm in diameter), and the membrane lytic activity of melittin enabled efficient release of the DNA into the cytoplasm, as monitored by fluorescence microscopy and flow cytometry. Compared with PEI, the transfection activity was strongly increased within a broad range of cell lines and types tested, including different tumor cell lines but also primary hepatocytes and human umbilical vein endothelial cells. The early onset of gene expression (within 4 h, reaching maximal values after 12 h) and the high reporter gene expression achieved in slowly dividing or confluent cells suggested a further role of melittin after releasing the DNA into the cytoplasm. Intracytoplasmic microinjection of melittin-containing PEI.DNA complexes into fibroblasts produced 40% cellular frequency of reporter gene expression that was inhibitable by co-injection of wheat germ agglutinin, whereas simple PEI.DNA complexes showed only 10%. These data suggest that melittin enables release of nonviral gene transfer particles into the cytoplasm and also enhances their transport into the nucleus, possibly via the cationic cluster KRKR near the C terminus of the peptide.
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Affiliation(s)
- M Ogris
- Cancer Research Campaign Institute for Cancer Studies, University of Birmingham, Vincent Drive, Birmingham B15 2TA, United Kingdom.
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Isaac C, Pollard JW, Meier UT. Intranuclear endoplasmic reticulum induced by Nopp140 mimics the nucleolar channel system of human endometrium. J Cell Sci 2001; 114:4253-64. [PMID: 11739657 DOI: 10.1242/jcs.114.23.4253] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Exogenous expression of the characteristic repeat domain of the nucleolar chaperone Nopp140 induces the formation of intranuclear structures, termed R-rings. Here, the R-rings are identified as extensive stacks of membrane cisternae in the otherwise membrane-free nucleus. They consist of bona fide endoplasmic reticulum (ER) containing integral membrane proteins of the smooth and rough ER. Although lacking nuclear pore complexes and lamina, the R-rings derive specifically from the inner nuclear membrane. These findings are consistent with the idea that all transmembrane proteins synthesized in the ER and the outer nuclear membrane can freely diffuse through the pore membrane domain into the inner membrane. Uniquely, the soluble transfected Nopp140 is directly involved in the generation of these membrane stacks as it localizes to the electron dense matrix in which they are embedded. The only well-documented example of intranuclear membrane proliferation is the nucleolar channel system of the postovulation human endometrium. The transient emergence of the nucleolar channel system correlates precisely with the readiness of the endometrium for the implantation of the fertilized egg. The nucleolar channel system exhibits an ultrastructure that is indistinguishable from R-rings, and nuclei of human endometrium harbor Nopp140 and ER marker containing structures. Therefore, the nucleolar channel system appears to be identical to the R-rings, suggesting a role for Nopp140 in human reproduction.
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Affiliation(s)
- C Isaac
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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