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Peggion C, Massimino ML, Pereira D, Granuzzo S, Righetto F, Bortolotto R, Agostini J, Sartori G, Bertoli A, Lopreiato R. Structural Integrity of Nucleolin Is Required to Suppress TDP-43-Mediated Cytotoxicity in Yeast and Human Cell Models. Int J Mol Sci 2023; 24:17466. [PMID: 38139294 PMCID: PMC10744044 DOI: 10.3390/ijms242417466] [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: 10/03/2023] [Revised: 11/28/2023] [Accepted: 12/09/2023] [Indexed: 12/24/2023] Open
Abstract
The Transactivating response (TAR) element DNA-binding of 43 kDa (TDP-43) is mainly implicated in the regulation of gene expression, playing multiple roles in RNA metabolism. Pathologically, it is implicated in amyotrophic lateral sclerosis and in a class of neurodegenerative diseases broadly going under the name of frontotemporal lobar degeneration (FTLD). A common hallmark of most forms of such diseases is the presence of TDP-43 insoluble inclusions in the cell cytosol. The molecular mechanisms of TDP-43-related cell toxicity are still unclear, and the contribution to cell damage from either loss of normal TDP-43 function or acquired toxic properties of protein aggregates is yet to be established. Here, we investigate the effects on cell viability of FTLD-related TDP-43 mutations in both yeast and mammalian cell models. Moreover, we focus on nucleolin (NCL) gene, recently identified as a genetic suppressor of TDP-43 toxicity, through a thorough structure/function characterization aimed at understanding the role of NCL domains in rescuing TDP-43-induced cytotoxicity. Using functional and biochemical assays, our data demonstrate that the N-terminus of NCL is necessary, but not sufficient, to exert its antagonizing effects on TDP-43, and further support the relevance of the DNA/RNA binding central region of the protein. Concurrently, data suggest the importance of the NCL nuclear localization for TDP-43 trafficking, possibly related to both TDP-43 physiology and toxicity.
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Affiliation(s)
- Caterina Peggion
- Department of Biology, University of Padova, 35131 Padova, Italy
| | | | - Daniel Pereira
- Department of Biomedical Sciences, University of Padova, 35131 Padova, Italy
- Department of Bioengineering, iBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
| | - Sara Granuzzo
- Department of Biomedical Sciences, University of Padova, 35131 Padova, Italy
| | - Francesca Righetto
- Department of Biomedical Sciences, University of Padova, 35131 Padova, Italy
| | - Raissa Bortolotto
- Department of Biomedical Sciences, University of Padova, 35131 Padova, Italy
| | - Jessica Agostini
- Department of Biomedical Sciences, University of Padova, 35131 Padova, Italy
| | - Geppo Sartori
- Department of Biomedical Sciences, University of Padova, 35131 Padova, Italy
| | - Alessandro Bertoli
- Neuroscience Institute, Consiglio Nazionale Delle Ricerche, 35131 Padova, Italy
- Department of Biomedical Sciences, University of Padova, 35131 Padova, Italy
- Padova Neuroscience Center, University of Padova, 35131 Padova, Italy
| | - Raffaele Lopreiato
- Department of Biomedical Sciences, University of Padova, 35131 Padova, Italy
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2
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Custer SK, Gilson T, Astroski JW, Nanguneri SR, Iurillo AM, Androphy EJ. COPI coatomer subunit α-COP interacts with the RNA binding protein Nucleolin via a C-terminal dilysine motif. Hum Mol Genet 2023; 32:3263-3275. [PMID: 37658769 PMCID: PMC10656708 DOI: 10.1093/hmg/ddad140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 08/07/2023] [Accepted: 08/30/2023] [Indexed: 09/05/2023] Open
Abstract
The COPI coatomer subunit α-COP has been shown to co-precipitate mRNA in multiple settings, but it was unclear whether the interaction with mRNA was direct or mediated by interaction with an adapter protein. The COPI complex often interacts with proteins via C-terminal dilysine domains. A search for candidate RNA binding proteins with C-terminal dilysine motifs yielded Nucleolin, which terminates in a KKxKxx sequence. This protein was an especially intriguing candidate as it has been identified as an interacting partner for Survival Motor Neuron protein (SMN). Loss of SMN causes the neurodegenerative disease Spinal Muscular Atrophy. We have previously shown that SMN and α-COP interact and co-migrate in axons, and that overexpression of α-COP reduced phenotypic severity in cell culture and animal models of SMA. We show here that in an mRNA independent manner, endogenous Nucleolin co-precipitates endogenous α-COP and ε-COP but not β-COP which may reflect an interaction with the so-called B-subcomplex rather a complete COPI heptamer. The ability of Nucleolin to bind to α-COP requires the presence of the C-terminal KKxKxx domain of Nucleolin. Furthermore, we have generated a point mutant in the WD40 domain of α-COP which eliminates its ability to co-precipitate Nucleolin but does not interfere with precipitation of partners mediated by non-KKxKxx motifs such as the kainate receptor subunit 2. We propose that via interaction between the C-terminal dilysine motif of Nucleolin and the WD40 domain of α-COP, Nucleolin acts an adaptor to allow α-COP to interact with a population of mRNA.
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Affiliation(s)
- Sara K Custer
- Dermatology, Indiana University School of Medicine, 545 Barnhill Drive, Emerson Hall 139, Indianapolis, IN 46202, United States
| | - Timra Gilson
- Dermatology, Indiana University School of Medicine, 545 Barnhill Drive, Emerson Hall 139, Indianapolis, IN 46202, United States
| | - Jacob W Astroski
- Dermatology, Indiana University School of Medicine, 545 Barnhill Drive, Emerson Hall 139, Indianapolis, IN 46202, United States
| | - Siddarth R Nanguneri
- Dermatology, Indiana University School of Medicine, 545 Barnhill Drive, Emerson Hall 139, Indianapolis, IN 46202, United States
| | - Alyssa M Iurillo
- Indiana University School of Medicine, 340 West 10 St, Indianapolis, IN 46202, United States
| | - Elliot J Androphy
- Dermatology, Indiana University School of Medicine, 545 Barnhill Drive, Emerson Hall 139, Indianapolis, IN 46202, United States
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3
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Sakthivel D, Brown-Suedel A, Bouchier-Hayes L. The role of the nucleolus in regulating the cell cycle and the DNA damage response. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2023; 135:203-241. [PMID: 37061332 DOI: 10.1016/bs.apcsb.2023.01.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
The nucleolus has long been perceived as the site for ribosome biogenesis, but numerous studies suggest that the nucleolus carefully sequesters crucial proteins involved in multiple cellular functions. Among these, the role of nucleolus in cell cycle regulation is the most evident. The nucleolus is the first responder of growth-related signals to mediate normal cell cycle progression. The nucleolus also senses different cellular stress insults by activating diverse pathways that arrest the cell cycle, promote DNA repair, or initiate apoptosis. Here, we review the emerging concepts on how the ribosomal and nonribosomal nucleolar proteins mediate such cellular effects.
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4
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Muñoz-Díaz E, Sáez-Vásquez J. Nuclear dynamics: Formation of bodies and trafficking in plant nuclei. FRONTIERS IN PLANT SCIENCE 2022; 13:984163. [PMID: 36082296 PMCID: PMC9445803 DOI: 10.3389/fpls.2022.984163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 08/04/2022] [Indexed: 06/01/2023]
Abstract
The existence of the nucleus distinguishes prokaryotes and eukaryotes. Apart from containing most of the genetic material, the nucleus possesses several nuclear bodies composed of protein and RNA molecules. The nucleus is separated from the cytoplasm by a double membrane, regulating the trafficking of molecules in- and outwards. Here, we investigate the composition and function of the different plant nuclear bodies and molecular clues involved in nuclear trafficking. The behavior of the nucleolus, Cajal bodies, dicing bodies, nuclear speckles, cyclophilin-containing bodies, photobodies and DNA damage foci is analyzed in response to different abiotic stresses. Furthermore, we research the literature to collect the different protein localization signals that rule nucleocytoplasmic trafficking. These signals include the different types of nuclear localization signals (NLSs) for nuclear import, and the nuclear export signals (NESs) for nuclear export. In contrast to these unidirectional-movement signals, the existence of nucleocytoplasmic shuttling signals (NSSs) allows bidirectional movement through the nuclear envelope. Likewise, nucleolar signals are also described, which mainly include the nucleolar localization signals (NoLSs) controlling nucleolar import. In contrast, few examples of nucleolar export signals, called nucleoplasmic localization signals (NpLSs) or nucleolar export signals (NoESs), have been reported. The existence of consensus sequences for these localization signals led to the generation of prediction tools, allowing the detection of these signals from an amino acid sequence. Additionally, the effect of high temperatures as well as different post-translational modifications in nuclear and nucleolar import and export is discussed.
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Affiliation(s)
- Eduardo Muñoz-Díaz
- Centre National de la Recherche Scientifique (CNRS), Laboratoire Génome et Développement des Plantes, UMR 5096, Perpignan, France
- Univ. Perpignan Via Domitia, Laboratoire Génome et Développement des Plantes, UMR 5096, Perpignan, France
| | - Julio Sáez-Vásquez
- Centre National de la Recherche Scientifique (CNRS), Laboratoire Génome et Développement des Plantes, UMR 5096, Perpignan, France
- Univ. Perpignan Via Domitia, Laboratoire Génome et Développement des Plantes, UMR 5096, Perpignan, France
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5
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Doron‐Mandel E, Koppel I, Abraham O, Rishal I, Smith TP, Buchanan CN, Sahoo PK, Kadlec J, Oses‐Prieto JA, Kawaguchi R, Alber S, Zahavi EE, Di Matteo P, Di Pizio A, Song D, Okladnikov N, Gordon D, Ben‐Dor S, Haffner‐Krausz R, Coppola G, Burlingame AL, Jungwirth P, Twiss JL, Fainzilber M. The glycine arginine-rich domain of the RNA-binding protein nucleolin regulates its subcellular localization. EMBO J 2021; 40:e107158. [PMID: 34515347 PMCID: PMC8521312 DOI: 10.15252/embj.2020107158] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 07/29/2021] [Accepted: 08/03/2021] [Indexed: 12/31/2022] Open
Abstract
Nucleolin is a multifunctional RNA Binding Protein (RBP) with diverse subcellular localizations, including the nucleolus in all eukaryotic cells, the plasma membrane in tumor cells, and the axon in neurons. Here we show that the glycine arginine rich (GAR) domain of nucleolin drives subcellular localization via protein-protein interactions with a kinesin light chain. In addition, GAR sequences mediate plasma membrane interactions of nucleolin. Both these modalities are in addition to the already reported involvement of the GAR domain in liquid-liquid phase separation in the nucleolus. Nucleolin transport to axons requires the GAR domain, and heterozygous GAR deletion mice reveal reduced axonal localization of nucleolin cargo mRNAs and enhanced sensory neuron growth. Thus, the GAR domain governs axonal transport of a growth controlling RNA-RBP complex in neurons, and is a versatile localization determinant for different subcellular compartments. Localization determination by GAR domains may explain why GAR mutants in diverse RBPs are associated with neurodegenerative disease.
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Affiliation(s)
- Ella Doron‐Mandel
- Departments of Biomolecular Sciences and Molecular NeuroscienceWeizmann Institute of ScienceRehovotIsrael
- Present address:
Department of Biological SciencesColumbia UniversityNew YorkNYUSA
| | - Indrek Koppel
- Departments of Biomolecular Sciences and Molecular NeuroscienceWeizmann Institute of ScienceRehovotIsrael
- Present address:
Department of Chemistry and BiotechnologyTallinn University of TechnologyTallinnEstonia
| | - Ofri Abraham
- Departments of Biomolecular Sciences and Molecular NeuroscienceWeizmann Institute of ScienceRehovotIsrael
| | - Ida Rishal
- Departments of Biomolecular Sciences and Molecular NeuroscienceWeizmann Institute of ScienceRehovotIsrael
| | - Terika P Smith
- Department of Biological SciencesUniversity of South CarolinaColumbiaSCUSA
| | | | - Pabitra K Sahoo
- Department of Biological SciencesUniversity of South CarolinaColumbiaSCUSA
| | - Jan Kadlec
- Institute of Organic Chemistry and BiochemistryCzech Academy of SciencesPragueCzech Republic
| | - Juan A Oses‐Prieto
- Department of Pharmaceutical ChemistryUniversity of California San FranciscoSan FranciscoCAUSA
| | - Riki Kawaguchi
- Departments of Psychiatry and NeurologySemel Institute for Neuroscience and Human BehaviorUniversity of California Los AngelesLos AngelesCAUSA
| | - Stefanie Alber
- Departments of Biomolecular Sciences and Molecular NeuroscienceWeizmann Institute of ScienceRehovotIsrael
| | - Eitan Erez Zahavi
- Departments of Biomolecular Sciences and Molecular NeuroscienceWeizmann Institute of ScienceRehovotIsrael
| | - Pierluigi Di Matteo
- Departments of Biomolecular Sciences and Molecular NeuroscienceWeizmann Institute of ScienceRehovotIsrael
| | - Agostina Di Pizio
- Departments of Biomolecular Sciences and Molecular NeuroscienceWeizmann Institute of ScienceRehovotIsrael
| | - Didi‐Andreas Song
- Departments of Biomolecular Sciences and Molecular NeuroscienceWeizmann Institute of ScienceRehovotIsrael
| | - Nataliya Okladnikov
- Departments of Biomolecular Sciences and Molecular NeuroscienceWeizmann Institute of ScienceRehovotIsrael
| | - Dalia Gordon
- Departments of Biomolecular Sciences and Molecular NeuroscienceWeizmann Institute of ScienceRehovotIsrael
| | - Shifra Ben‐Dor
- Bioinformatics UnitLife Sciences Core FacilitiesWeizmann Institute of ScienceRehovotIsrael
| | | | - Giovanni Coppola
- Departments of Psychiatry and NeurologySemel Institute for Neuroscience and Human BehaviorUniversity of California Los AngelesLos AngelesCAUSA
| | - Alma L Burlingame
- Department of Pharmaceutical ChemistryUniversity of California San FranciscoSan FranciscoCAUSA
| | - Pavel Jungwirth
- Institute of Organic Chemistry and BiochemistryCzech Academy of SciencesPragueCzech Republic
| | - Jeffery L Twiss
- Department of Biological SciencesUniversity of South CarolinaColumbiaSCUSA
| | - Mike Fainzilber
- Departments of Biomolecular Sciences and Molecular NeuroscienceWeizmann Institute of ScienceRehovotIsrael
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6
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Okuwaki M, Saotome-Nakamura A, Yoshimura M, Saito S, Hirawake-Mogi H, Sekiya T, Nagata K. RNA-recognition motifs and glycine and arginine-rich region cooperatively regulate the nucleolar localization of nucleolin. J Biochem 2021; 169:87-100. [PMID: 32785674 DOI: 10.1093/jb/mvaa095] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 08/03/2020] [Indexed: 01/11/2023] Open
Abstract
Nucleolin (NCL) is a nucleolar protein i.e. involved in the regulation of the nucleolar structure and functions, and consists of three distinct regions: the N-terminal region; the middle region, which contains four RNA-recognition motifs (RRMs); and the C-terminal glycine- and arginine-rich (GAR) region. The primary function of the RRMs and GAR is thought to be specific RNA binding. However, it is not well understood how these RNA-binding regions of NCL separately or cooperatively regulate its nucleolar localization and functions. To address this issue, we constructed mutant proteins carrying point mutations at the four RRMs individually or deletion of the C-terminal GAR region. We found that the GAR deletion and the mutations in the fourth RRM (RRM4) decreased the nucleolar localization of NCL. Biochemical analyses showed that NCL interacted directly with ribosomal RNAs (rRNAs) and G-rich oligonucleotides, and that this interaction was decreased by mutations at RRM1 and RRM4 and GAR deletion. Although GAR deletion decreased the rRNA-binding activity of NCL, the mutant was efficiently coprecipitated with rRNAs and nucleolar proteins from cell extracts. These contradictory results suggest that NCL stably localizes to the nucleoli via the interactions with rRNAs and nucleolar proteins via GAR, RRM1 and RRM4.
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Affiliation(s)
- Mitsuru Okuwaki
- Laboratory of Biochemistry, School of Pharmaceutical Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
- Department of Infection Biology, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8575, Japan
| | - Ai Saotome-Nakamura
- Department of Infection Biology, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8575, Japan
| | - Masashi Yoshimura
- Laboratory of Biochemistry, School of Pharmaceutical Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Shoko Saito
- Laboratory of Biochemistry, School of Pharmaceutical Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
- Department of Infection Biology, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8575, Japan
| | - Hiroko Hirawake-Mogi
- Laboratory of Biochemistry, School of Pharmaceutical Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Takeshi Sekiya
- Department of Infection Biology, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8575, Japan
| | - Kyosuke Nagata
- Department of Infection Biology, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8575, Japan
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7
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RNA-Binding Proteins in Acute Leukemias. Int J Mol Sci 2020; 21:ijms21103409. [PMID: 32408494 PMCID: PMC7279408 DOI: 10.3390/ijms21103409] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 05/07/2020] [Accepted: 05/10/2020] [Indexed: 12/12/2022] Open
Abstract
Acute leukemias are genetic diseases caused by translocations or mutations, which dysregulate hematopoiesis towards malignant transformation. However, the molecular mode of action is highly versatile and ranges from direct transcriptional to post-transcriptional control, which includes RNA-binding proteins (RBPs) as crucial regulators of cell fate. RBPs coordinate RNA dynamics, including subcellular localization, translational efficiency and metabolism, by binding to their target messenger RNAs (mRNAs), thereby controlling the expression of the encoded proteins. In view of the growing interest in these regulators, this review summarizes recent research regarding the most influential RBPs relevant in acute leukemias in particular. The reported RBPs, either dysregulated or as components of fusion proteins, are described with respect to their functional domains, the pathways they affect, and clinical aspects associated with their dysregulation or altered functions.
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8
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Proteins of the Nucleolus of Dictyostelium discoideum: Nucleolar Compartmentalization, Targeting Sequences, Protein Translocations and Binding Partners. Cells 2019; 8:cells8020167. [PMID: 30781559 PMCID: PMC6406644 DOI: 10.3390/cells8020167] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 02/13/2019] [Accepted: 02/15/2019] [Indexed: 12/31/2022] Open
Abstract
The nucleoli of Dictyostelium discoideum have a comparatively unique, non-canonical, localization adjacent to the inner nuclear membrane. The verified nucleolar proteins of this eukaryotic microbe are detailed while other potential proteins are introduced. Heat shock protein 32 (Hsp32), eukaryotic translation initiation factor 6 (eIF6), and tumour necrosis factor receptor-associated protein 1 (TRAP1) are essential for cell survival. NumA1, a breast cancer type 1 susceptibility protein-C Terminus domain-containing protein linked to cell cycle, functions in the regulation of nuclear number. The cell cycle checkpoint kinase 2 homologue forkhead-associated kinase A (FhkA) and BRG1-associated factor 60a homologue Snf12 are also discussed. While nucleoli appear homogeneous ultrastructurally, evidence for nucleolar subcompartments exists. Nucleolar localization sequences (NoLS) have been defined that target proteins to either the general nucleolar area or to a specific intranucleolar domain. Protein translocations during mitosis are protein-specific and support the multiple functions of the Dictyostelium nucleolus. To enrich the picture, binding partners of NumA1, the most well-characterized nucleolar protein, are examined: nucleolar Ca2+-binding protein 4a (CBP4a), nuclear puromycin-sensitive aminopeptidase A (PsaA) and Snf12. The role of Dictyostelium as a model for understanding the contribution of nucleolar proteins to various diseases and cellular stress is discussed throughout the review.
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Sen Gupta A, Joshi G, Pawar S, Sengupta K. Nucleolin modulates compartmentalization and dynamics of histone 2B-ECFP in the nucleolus. Nucleus 2018; 9:350-367. [PMID: 29943658 PMCID: PMC6165600 DOI: 10.1080/19491034.2018.1471936] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
Eukaryotic cells have 2 to 3 discrete nucleoli required for ribosome synthesis. Nucleoli are phase separated nuclear sub-organelles. Here we examined the role of nuclear Lamins and nucleolar factors in modulating the compartmentalization and dynamics of histone 2B (H2B-ECFP) in the nucleolus. Live imaging and Fluorescence Recovery After Photobleaching (FRAP) of labelled H2B, showed that the depletion of Lamin B1, Fibrillarin (FBL) or Nucleostemin (GNL3), enhances H2B-ECFP mobility in the nucleolus. Furthermore, Nucleolin knockdown significantly decreases H2B-ECFP compartmentalization in the nucleolus, while H2B-ECFP residence and mobility in the nucleolus was prolonged upon Nucleolin overexpression. Co-expression of N-terminal and RNA binding domain (RBD) deletion mutants of Nucleolin or inhibiting 45S rRNA synthesis reduces the sequestration of H2B-ECFP in the nucleolus. Taken together, these studies reveal a crucial role of Nucleolin-rRNA complex in modulating the compartmentalization, stability and dynamics of H2B within the nucleolus.
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Affiliation(s)
- Ayantika Sen Gupta
- Biology, Indian Institute of Science Education and Research (IISER), Pune, India
| | - Gaurav Joshi
- Biology, Indian Institute of Science Education and Research (IISER), Pune, India
| | - Sumit Pawar
- Biology, Indian Institute of Science Education and Research (IISER), Pune, India
| | - Kundan Sengupta
- Biology, Indian Institute of Science Education and Research (IISER), Pune, India
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10
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Jia W, Yao Z, Zhao J, Guan Q, Gao L. New perspectives of physiological and pathological functions of nucleolin (NCL). Life Sci 2017; 186:1-10. [PMID: 28751161 DOI: 10.1016/j.lfs.2017.07.025] [Citation(s) in RCA: 145] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 07/21/2017] [Accepted: 07/23/2017] [Indexed: 12/13/2022]
Abstract
Nucleolin (NCL) is a multifunctional protein that mainly localized in the nucleolus, it is also found in the nucleoplasm, cytoplasm and cell membrane. The three main structural domains allow the interaction of NCL with different proteins and RNA sequences. Moreover, specific post-translational modifications and its shuttling property also contribute to its multifunctionality. NCL has been demonstrated to be involved in a variety of aspects such as ribosome biogenesis, chromatin organization and stability, DNA and RNA metabolism, cytokinesis, cell proliferation, angiogenesis, apoptosis regulation, stress response and microRNA processing. NCL has been increasingly implicated in several pathological processes, especially in tumorigenesis and viral infection, which makes NCL a potential target for the development of anti-tumor and anti-viral strategies. In this review, we present an overview on the structure, localizations and various functions of NCL, and further describe how the multiple functions of NCL are correlated to its multiple cellular distributions.
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Affiliation(s)
- Wenyu Jia
- Department of Endocrinology, Shandong Provincial Hospital affiliated to Shandong University, Jinan, Shandong Province, PR China; Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Jinan, Shandong Province, PR China; Institute of Endocrinology and Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong Province, PR China
| | - Zhenyu Yao
- Department of Endocrinology, Shandong Provincial Hospital affiliated to Shandong University, Jinan, Shandong Province, PR China; Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Jinan, Shandong Province, PR China; Institute of Endocrinology and Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong Province, PR China
| | - Jiajun Zhao
- Department of Endocrinology, Shandong Provincial Hospital affiliated to Shandong University, Jinan, Shandong Province, PR China; Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Jinan, Shandong Province, PR China; Institute of Endocrinology and Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong Province, PR China
| | - Qingbo Guan
- Department of Endocrinology, Shandong Provincial Hospital affiliated to Shandong University, Jinan, Shandong Province, PR China; Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Jinan, Shandong Province, PR China; Institute of Endocrinology and Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong Province, PR China
| | - Ling Gao
- Department of Endocrinology, Shandong Provincial Hospital affiliated to Shandong University, Jinan, Shandong Province, PR China; Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Jinan, Shandong Province, PR China; Institute of Endocrinology and Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong Province, PR China.
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Mashreghi M, Azarpara H, Bazaz MR, Jafari A, Masoudifar A, Mirzaei H, Jaafari MR. Angiogenesis biomarkers and their targeting ligands as potential targets for tumor angiogenesis. J Cell Physiol 2017; 233:2949-2965. [DOI: 10.1002/jcp.26049] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 06/12/2017] [Indexed: 12/20/2022]
Affiliation(s)
- Mohammad Mashreghi
- NanotechnologyResearch Center; Mashhad University of Medical Sciences; Mashhad Iran
- School of Pharmacy; Mashhad University of Medical Sciences; Mashhad Iran
| | - Hassan Azarpara
- School of Medicine; Iran University of Medical Sciences; Tehran Iran
| | - Mahere R. Bazaz
- Division of Biotechnology, Faculty of Veterinary Medicine; Ferdowsi University of Mashhad; Mashhad Iran
| | - Arash Jafari
- School of Medicine; Birjand University of Medical Sciences; Birjand Iran
| | - Aria Masoudifar
- Department of Molecular Biotechnology, Cell Science Research Center; Royan Institute for Biotechnology; ACECR Isfahan Iran
| | - Hamed Mirzaei
- Department of Medical Biotechnology, School of Medicine; Mashhad University of Medical Sciences; Mashhad Iran
| | - Mahmoud R. Jaafari
- NanotechnologyResearch Center; Mashhad University of Medical Sciences; Mashhad Iran
- School of Pharmacy; Mashhad University of Medical Sciences; Mashhad Iran
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12
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Caudron-Herger M, Pankert T, Rippe K. Regulation of nucleolus assembly by non-coding RNA polymerase II transcripts. Nucleus 2017; 7:308-18. [PMID: 27416361 DOI: 10.1080/19491034.2016.1190890] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The nucleolus is a nuclear subcompartment for tightly regulated rRNA production and ribosome subunit biogenesis. It also acts as a cellular stress sensor and can release enriched factors in response to cellular stimuli. Accordingly, the content and structure of the nucleolus change dynamically, which is particularly evident during cell cycle progression: the nucleolus completely disassembles during mitosis and reassembles in interphase. Although the mechanisms that drive nucleolar (re)organization have been the subject of a number of studies, they are only partly understood. Recently, we identified Alu element-containing RNA polymerase II transcripts (aluRNAs) as important for nucleolar structure and rRNA synthesis. Integrating these findings with studies on the liquid droplet-like nature of the nucleolus leads us to propose a model on how RNA polymerase II transcripts could regulate the assembly of the nucleolus in response to external stimuli and during cell cycle progression.
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Affiliation(s)
- Maïwen Caudron-Herger
- a RNA Biology and Cancer, German Cancer Research Center (DKFZ) , Heidelberg , Germany
| | - Teresa Pankert
- b Genome Organization & Function, German Cancer Research Center (DKFZ) and BioQuant Center , Heidelberg , Germany
| | - Karsten Rippe
- b Genome Organization & Function, German Cancer Research Center (DKFZ) and BioQuant Center , Heidelberg , Germany
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13
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Shubina MY, Musinova YR, Sheval EV. Nucleolar methyltransferase fibrillarin: Evolution of structure and functions. BIOCHEMISTRY (MOSCOW) 2016; 81:941-50. [DOI: 10.1134/s0006297916090030] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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14
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Berger CM, Gaume X, Bouvet P. The roles of nucleolin subcellular localization in cancer. Biochimie 2015; 113:78-85. [PMID: 25866190 DOI: 10.1016/j.biochi.2015.03.023] [Citation(s) in RCA: 162] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 03/29/2015] [Indexed: 01/10/2023]
Abstract
Nucleolin (NCL) is one of the most abundant non ribosomal protein of the nucleolus where it plays a central role in polymerase I transcription. NCL is also found outside of the nucleolus, in the nucleoplasm, cytoplasm as well as on the cell membrane. It acts in all cell compartments to control cellular homeostasis and therefore each cellular pool of NCL can play a different role in cancer development. NCL overexpression and its increased localization at the cell membrane is a common feature of several tumor cells. In cancer cells, NCL overexpression influences cell survival, proliferation and invasion through its action on different cellular pathways. In this review, we describe how the multiple functions of NCL that are associated to its multiple cellular localization can participate to the development of cancer.
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Affiliation(s)
- Caroline Madeleine Berger
- Département de Biologie, Master Biosciences, ENS de Lyon, Lyon, France; Ecole Normale Supérieure de Lyon, Laboratoire Joliot-Curie, CNRS USR 3010, 46 allée d'Italie, 69364 Lyon Cedex 7, France
| | - Xavier Gaume
- Ecole Normale Supérieure de Lyon, Laboratoire Joliot-Curie, CNRS USR 3010, 46 allée d'Italie, 69364 Lyon Cedex 7, France
| | - Philippe Bouvet
- Ecole Normale Supérieure de Lyon, Laboratoire Joliot-Curie, CNRS USR 3010, 46 allée d'Italie, 69364 Lyon Cedex 7, France.
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15
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Muller M, Hutin S, Marigold O, Li KH, Burlingame A, Glaunsinger BA. A ribonucleoprotein complex protects the interleukin-6 mRNA from degradation by distinct herpesviral endonucleases. PLoS Pathog 2015; 11:e1004899. [PMID: 25965334 PMCID: PMC4428876 DOI: 10.1371/journal.ppat.1004899] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 04/20/2015] [Indexed: 11/21/2022] Open
Abstract
During lytic Kaposi's sarcoma-associated herpesvirus (KSHV) infection, the viral endonuclease SOX promotes widespread degradation of cytoplasmic messenger RNA (mRNA). However, select mRNAs escape SOX-induced cleavage and remain robustly expressed. Prominent among these is interleukin-6 (IL-6), a growth factor important for survival of KSHV infected B cells. IL-6 escape is notable because it contains a sequence within its 3' untranslated region (UTR) that can confer protection when transferred to a SOX-targeted mRNA, and thus overrides the endonuclease targeting mechanism. Here, we pursued how this protective RNA element functions to maintain mRNA stability. Using affinity purification and mass spectrometry, we identified a set of proteins that associate specifically with the protective element. Although multiple proteins contributed to the escape mechanism, depletion of nucleolin (NCL) most severely impacted protection. NCL was re-localized out of the nucleolus during lytic KSHV infection, and its presence in the cytoplasm was required for protection. After loading onto the IL-6 3' UTR, NCL differentially bound to the translation initiation factor eIF4H. Disrupting this interaction, or depleting eIF4H, reinstated SOX targeting of the RNA, suggesting that interactions between proteins bound to distant regions of the mRNA are important for escape. Finally, we found that the IL-6 3' UTR was also protected against mRNA degradation by the vhs endonuclease encoded by herpes simplex virus, despite the fact that its mechanism of mRNA targeting is distinct from SOX. These findings highlight how a multitude of RNA-protein interactions can impact endonuclease targeting, and identify new features underlying the regulation of the IL-6 mRNA.
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Affiliation(s)
- Mandy Muller
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, United States of America
| | - Stephanie Hutin
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, United States of America
| | - Oliver Marigold
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, United States of America
| | - Kathy H. Li
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California, United States of America
| | - Al Burlingame
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California, United States of America
| | - Britt A. Glaunsinger
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, United States of America
- Department of Cell and Molecular Biology, University of California, Berkeley, Berkeley, California, United States of America
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16
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Kenney SP, Meng XJ. Identification and fine mapping of nuclear and nucleolar localization signals within the human ribosomal protein S17. PLoS One 2015; 10:e0124396. [PMID: 25853866 PMCID: PMC4390217 DOI: 10.1371/journal.pone.0124396] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Accepted: 03/13/2015] [Indexed: 01/29/2023] Open
Abstract
Human ribosomal protein S17 (RPS17) is mutated in Diamond-Blackfan Anemia (DBA), a bone marrow disorder that fails to produce sufficient red blood cells leading to anemia. Recently, an RPS17 protein sequence was also found to be naturally inserted in the genome of hepatitis E virus (HEV) from patients chronically-infected by HEV. The role of RPS17 in HEV replication and pathogenesis remains unknown due to the lack of knowledge about how RPS17 functions at a molecular level. Understanding the biological function of RPS17 is critical for elucidating its role in virus infection and DBA disease processes. In this study we probed the subcellular distribution of normal and mutant RPS17 proteins in a human liver cell line (Huh7). RPS17 was primarily detected within the nucleus, and more specifically within the nucleoli. Using a transient expression system in which RPS17 or truncations were expressed as fusions with enhanced yellow fluorescent protein (eYFP), we were able to identify and map, for the first time, two separate nuclear localization signals (NLSs), one to the first 13 amino acids of the amino-terminus of RPS17 and the other within amino acids 30-60. Additionally, we mapped amino acid sequences required for nucleolar accumulation of RPS17 to amino acids 60-70. Amino acids 60-70 possess a di-RG motif that may be necessary for nucleolar retention of RPS17. The results from this study enhance our knowledge of RSP17 and will facilitate future mechanistic studies about the roles of RSP17 in hepatitis E and DBA disease processes.
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Affiliation(s)
- Scott P. Kenney
- Center for Molecular Medicine and Infectious Diseases, Department of Biomedical Sciences and Pathobiology, College of Veterinary Medicine, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, Virginia, United States of America
| | - Xiang-Jin Meng
- Center for Molecular Medicine and Infectious Diseases, Department of Biomedical Sciences and Pathobiology, College of Veterinary Medicine, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, Virginia, United States of America
- * E-mail:
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17
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Zhang D, Liang Y, Xie Q, Gao G, Wei J, Huang H, Li J, Gao J, Huang C. A novel post-translational modification of nucleolin, SUMOylation at Lys-294, mediates arsenite-induced cell death by regulating gadd45α mRNA stability. J Biol Chem 2015; 290:4784-4800. [PMID: 25561743 PMCID: PMC4335216 DOI: 10.1074/jbc.m114.598219] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 12/30/2014] [Indexed: 11/06/2022] Open
Abstract
Nucleolin is a ubiquitously expressed protein and participates in many important biological processes, such as cell cycle regulation and ribosomal biogenesis. The activity of nucleolin is regulated by intracellular localization and post-translational modifications, including phosphorylation, methylation, and ADP-ribosylation. Small ubiquitin-like modifier (SUMO) is a category of recently verified forms of post-translational modifications and exerts various effects on the target proteins. In the studies reported here, we discovered SUMOylational modification of human nucleolin protein at Lys-294, which facilitated the mRNA binding property of nucleolin by maintaining its nuclear localization. In response to arsenic exposure, nucleolin-SUMO was induced and promoted its binding with gadd45α mRNA, which increased gadd45α mRNA stability and protein expression, subsequently causing GADD45α-mediated cell death. On the other hand, ectopic expression of Mn-SOD attenuated the arsenite-generated superoxide radical level, abrogated nucleolin-SUMO, and in turn inhibited arsenite-induced apoptosis by reducing GADD45α expression. Collectively, our results for the first time demonstrate that nucleolin-SUMO at K294R plays a critical role in its nucleus sequestration and gadd45α mRNA binding activity. This novel biological function of nucleolin is distinct from its conventional role as a proto-oncogene. Therefore, our findings here not only reveal a new modification of nucleolin protein and its novel functional paradigm in mRNA metabolism but also expand our understanding of the dichotomous roles of nucleolin in terms of cancer development, which are dependent on multiple intracellular conditions and consequently the appropriate regulations of its modifications, including SUMOylation.
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Affiliation(s)
- Dongyun Zhang
- Nelson Institute of Environmental Medicine, New York University School of Medicine, Tuxedo, New York 10987 and; Zhejiang Provincial Key Laboratory for Technology and Application of Model Organisms, School of Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Yuguang Liang
- Nelson Institute of Environmental Medicine, New York University School of Medicine, Tuxedo, New York 10987 and
| | - Qipeng Xie
- Zhejiang Provincial Key Laboratory for Technology and Application of Model Organisms, School of Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Guangxun Gao
- Nelson Institute of Environmental Medicine, New York University School of Medicine, Tuxedo, New York 10987 and
| | - Jinlong Wei
- Zhejiang Provincial Key Laboratory for Technology and Application of Model Organisms, School of Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Haishan Huang
- Zhejiang Provincial Key Laboratory for Technology and Application of Model Organisms, School of Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Jingxia Li
- Nelson Institute of Environmental Medicine, New York University School of Medicine, Tuxedo, New York 10987 and
| | - Jimin Gao
- Zhejiang Provincial Key Laboratory for Technology and Application of Model Organisms, School of Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Chuanshu Huang
- Nelson Institute of Environmental Medicine, New York University School of Medicine, Tuxedo, New York 10987 and.
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18
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Sripinyowanich S, Chamnanmanoontham N, Udomchalothorn T, Maneeprasopsuk S, Santawee P, Buaboocha T, Qu LJ, Gu H, Chadchawan S. Overexpression of a partial fragment of the salt-responsive gene OsNUC1 enhances salt adaptation in transgenic Arabidopsis thaliana and rice (Oryza sativa L.) during salt stress. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2013; 213:67-78. [PMID: 24157209 DOI: 10.1016/j.plantsci.2013.08.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 08/12/2013] [Accepted: 08/30/2013] [Indexed: 05/08/2023]
Abstract
The rice (Oryza sativa L.) nucleolin gene, OsNUC1, transcripts were expressed in rice leaves, flowers, seeds and roots but differentially expressed within and between two pairs of salt-sensitive and salt-resistant rice lines when subjected to salt stress. Salt-resistant lines exhibited higher OsNUC1 transcript expression levels than salt-sensitive lines during 0.5% (w/v) NaCl salt stress for 6d. Two sizes of OsNUC1 full-length cDNA were found in the rice genome database and northern blot analysis confirmed their existence in rice tissues. The longer transcript (OsNUC1-L) putatively encodes for a protein with a serine rich N-terminal, RNA recognition motifs in the central domain and a glycine- and arginine-rich repeat in the C-terminal domain, while the shorter one (OsNUC1-S) putatively encodes for the similar protein without the N-terminus. Without salt stress, OsNUC1-L expressing Arabidopsis thaliana Atnuc1-L1 plants displayed a substantial but incomplete revertant phenotype, whereas OsNUC1-S expression only induced a weak effect. However, under 0.5% (w/v) NaCl salt stress they displayed a higher relative growth rate, longer root length and a lower H2O2 level than the wild type plants, suggesting a higher salt resistance. Moreover, they displayed elevated AtSOS1 and AtP5CS1 transcript levels. We propose that OsNUC1-S plays an important role in salt resistance during salt stress, a new role for nucleolin in plants.
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Affiliation(s)
- Siriporn Sripinyowanich
- Biological Sciences Program, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand; Environmental and Plant Physiology Research Unit, Department of Botany, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
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19
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Karamchand L, Kim G, Wang S, Hah HJ, Ray A, Jiddou R, Koo Lee YE, Philbert MA, Kopelman R. Modulation of hydrogel nanoparticle intracellular trafficking by multivalent surface engineering with tumor targeting peptide. NANOSCALE 2013; 5:10327-44. [PMID: 24056573 PMCID: PMC3823366 DOI: 10.1039/c3nr00908d] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Surface engineering of a hydrogel nanoparticle (NP) with the tumor-targeting ligand, F3 peptide, enhances both the NP's binding affinity for, and internalization by, nucleolin overexpressing tumor cells. Remarkably, the F3-functionalized NPs consistently exhibited significantly lower trafficking to the degradative lysosomes than the non-functionalized NPs, in the tumor cells, after internalization. This is attributed to the non-functionalized NPs, but not the F3-functionalized NPs, being co-internalized with Lysosome-associated Membrane Protein-1 (LAMP1) from the surface of the tumor cells. Furthermore, it is shown that the intracellular trafficking of the F3-functionalized NPs differs significantly from that of the molecular F3 peptides (untethered to NPs). This has important implications for designing effective, chemically-responsive, controlled-release and multifunctional nanodrugs for multi-drug-resistant cancers.
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Affiliation(s)
- Leshern Karamchand
- Department of Chemistry, University of Michigan, 930 North University Ave, Ann Arbor, Michigan 48109, USA.
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20
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On the segregation of protein ionic residues by charge type. Amino Acids 2012; 43:2231-47. [PMID: 23081700 DOI: 10.1007/s00726-012-1418-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Accepted: 10/06/2012] [Indexed: 10/27/2022]
Abstract
Based on ubiquitous presence of large ionic motifs and clusters in proteins involved in gene transcription and protein synthesis, we analyzed the distribution of ionizable sidechains in a broad selection of proteins with regulatory, metabolic, structural and adhesive functions, in agonist, antagonist, toxin and antimicrobial peptides, and in self-excising inteins and intron-derived proteins and sequence constructs. All tested groups, regardless of taxa or sequence size, show considerable segregation of ionizable sidechains into same type charge (homoionic) tracts. These segments in most cases exceed half of the sequence length and comprise more than two-thirds of all ionizable sidechains. This distribution of ionic residues apparently reflects a fundamental advantage of sorted electrostatic contacts in association of sequence elements within and between polypeptides, as well as in interaction with polynucleotides. While large ionic densities are encountered in highly interactive proteins, the average ionic density in most sets does not change appreciably with size of the homoionic segments, which supports the segregation as a modular feature favoring association.
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21
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Pickering BF, Yu D, Van Dyke MW. Nucleolin protein interacts with microprocessor complex to affect biogenesis of microRNAs 15a and 16. J Biol Chem 2011; 286:44095-44103. [PMID: 22049078 PMCID: PMC3243533 DOI: 10.1074/jbc.m111.265439] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Revised: 10/22/2011] [Indexed: 01/09/2023] Open
Abstract
MicroRNAs (miRNA) are endogenous, short, non-coding RNA that undergo a multistep biogenesis before generating the functional, mature sequence. The core components of the microprocessor complex, consisting of Drosha and DGCR8, are both necessary and sufficient for this process, although accessory proteins have been found that modulate the biogenesis of a subset of miRNA. Curiously, many of the proteins involved in miRNA biogenesis are also needed for ribosomal RNA processing. Here we show that nucleolin, another protein critical for rRNA processing, is involved in the biogenesis of microRNA 15a/16 (miR-15a/16), specifically at the primary to precursor stage of processing. Through overexpression and knockdown studies, we show that miR-15a/16 levels are directly correlated to nucleolin expression. Furthermore, we found that cellular localization is critical for the proper functioning of nucleolin in this pathway and that nucleolin directly interacts with DGCR8 and Drosha in the nucleus. Nucleolin can bind to the primary miRNA both directly and specifically. Finally, we show that in the absence of nucleolin, cell extracts are unable to process miR-15a/16 in vitro and that this can be rescued by the addition of nucleolin. Our findings offer a new protein component in the microRNA biogenesis pathway and lend insight into miRNA dysregulation in certain cancers.
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Affiliation(s)
- Brian F Pickering
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030; Cancer Biology Program, The University of Texas Graduate School of Biomedical Sciences, Houston, Texas 77030.
| | - Dihua Yu
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030; Cancer Biology Program, The University of Texas Graduate School of Biomedical Sciences, Houston, Texas 77030.
| | - Michael W Van Dyke
- Department of Chemistry and Physics, Western Carolina University, Cullowhee, North Carolina 28723
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22
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Jerke U, Tkachuk S, Kiyan J, Stepanova V, Kusch A, Hinz M, Dietz R, Haller H, Fuhrman B, Dumler I. Stat1 nuclear translocation by nucleolin upon monocyte differentiation. PLoS One 2009; 4:e8302. [PMID: 20011528 PMCID: PMC2788426 DOI: 10.1371/journal.pone.0008302] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2009] [Accepted: 11/19/2009] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Members of the signal transducer and activator of transcription (Stat) family of transcription factors traverse the nuclear membrane through a specialized structure, called the nuclear pore complex (NPC), which represents a selective filter for the import of proteins. Karyophilic molecules can bind directly to a subset of proteins of the NPC, collectively called nucleoporins. Alternatively, the transport is mediated via a carrier molecule belonging to the importin/karyopherin superfamily, which transmits the import into the nucleus through the NPC. METHODOLOGY/PRINCIPAL FINDINGS In this study, we provide evidence for an alternative Stat1 nuclear import mechanism, which is mediated by the shuttle protein nucleolin. We observed Stat1-nucleolin association, nuclear translocation and specific binding to the regulatory DNA element GAS. Using expression of nucleolin transgenes, we found that the nuclear localization signal (NLS) of nucleolin is responsible for Stat1 nuclear translocation. We show that this mechanism is utilized upon differentiation of myeloid cells and is specific for the differentiation step from monocytes to macrophages. CONCLUSIONS/SIGNIFICANCE Our data add the nucleolin-Stat1 complex as a novel functional partner for the cell differentiation program, which is uniquely poised to regulate the transcription machinery via Stat1 and nuclear metabolism via nucleolin.
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Affiliation(s)
- Uwe Jerke
- Hannover Medical School, Hannover, Germany.
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23
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Baydoun HH, Bellon M, Nicot C. HTLV-1 Yin and Yang: Rex and p30 master regulators of viral mRNA trafficking. AIDS Rev 2008; 10:195-204. [PMID: 19092975 PMCID: PMC2666328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Human retroviruses are associated with a variety of malignancies including Kaposi's sarcoma and Epstein-Barr virus-associated lymphoma in HIV infection, T-cell leukemia/lymphoma and a neurologic disorder in human T-cell lymphotropic virus type 1 (HTLV-1) infection. Both HIV and human T-cell lymphotropic virus type 1 have evolved a complex genetic organization for optimal use of their limited genome and production of all necessary structural and regulatory proteins. Use of alternative splicing is essential for balanced expression of multiple viral regulators from one genomic polycistronic RNA. In addition, nuclear export of incompletely spliced RNA is required for production of structural and enzymatic proteins and virus particles. Decisions controlling these events are largely guarded by viral proteins. In human T-cell lymphotropic virus type 1, Rex and p30 are both nuclear/nucleolar RNA binding regulatory proteins. Rex interacts with a Rex-responsive element to stimulate nuclear export of incompletely spliced RNA and increase production of virus particles. In contrast, human T-cell lymphotropic virus type 1 p30 is involved in the nuclear retention of the tax/rex mRNA leading to inhibition of virus expression and establishment of viral latency. How these two proteins, with apparently opposite functions, orchestrate virus replication and ensure vigilant control of viral gene expression is discussed.
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Affiliation(s)
- Hicham H Baydoun
- University of Kansas Medical Center, Department of Pathology and Laboratory Medicine, Center for Viral Oncology, KU Cancer Center, Kansas City, KS 66160, USA
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24
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Stepanova V, Lebedeva T, Kuo A, Yarovoi S, Tkachuk S, Zaitsev S, Bdeir K, Dumler I, Marks MS, Parfyonova Y, Tkachuk VA, Higazi AAR, Cines DB. Nuclear translocation of urokinase-type plasminogen activator. Blood 2008; 112:100-10. [PMID: 18337556 PMCID: PMC2435680 DOI: 10.1182/blood-2007-07-104455] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2007] [Accepted: 02/01/2008] [Indexed: 01/16/2023] Open
Abstract
Urokinase-type plasminogen activator (uPA) participates in diverse (patho)physiological processes through intracellular signaling events that affect cell adhesion, migration, and proliferation, although the mechanisms by which these occur are only partially understood. Here we report that upon cell binding and internalization, single-chain uPA (scuPA) translocates to the nucleus within minutes. Nuclear translocation does not involve proteolytic activation or degradation of scuPA. Neither the urokinase receptor (uPAR) nor the low-density lipoprotein-related receptor (LRP) is required for nuclear targeting. Rather, translocation involves the binding of scuPA to the nucleocytoplasmic shuttle protein nucleolin through a region containing the kringle domain. RNA interference and mutational analysis demonstrate that nucleolin is required for the nuclear transport of scuPA. Furthermore, nucleolin is required for the induction smooth muscle alpha-actin (alpha-SMA) by scuPA. These data reveal a novel pathway by which uPA is rapidly translocated to the nucleus where it might participate in regulating gene expression.
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Affiliation(s)
- Victoria Stepanova
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia 19104, USA.
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25
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Messaoudi L, Yang YG, Kinomura A, Stavreva DA, Yan G, Bortolin-Cavaillé ML, Arakawa H, Buerstedde JM, Hainaut P, Cavaillé J, Takata M, Van Dyck E. Subcellular distribution of human RDM1 protein isoforms and their nucleolar accumulation in response to heat shock and proteotoxic stress. Nucleic Acids Res 2007; 35:6571-87. [PMID: 17905820 PMCID: PMC2095821 DOI: 10.1093/nar/gkm753] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2007] [Revised: 08/28/2007] [Accepted: 09/11/2007] [Indexed: 12/11/2022] Open
Abstract
The RDM1 gene encodes a RNA recognition motif (RRM)-containing protein involved in the cellular response to the anti-cancer drug cisplatin in vertebrates. We previously reported a cDNA encoding the full-length human RDM1 protein. Here, we describe the identification of 11 human cDNAs encoding RDM1 protein isoforms. This repertoire is generated by alternative pre-mRNA splicing and differential usage of two translational start sites, resulting in proteins with long or short N-terminus and a great diversity in the exonic composition of their C-terminus. By using tagged proteins and fluorescent microscopy, we examined the subcellular distribution of full-length RDM1 (renamed RDM1alpha), and other RDM1 isoforms. We show that RDM1alpha undergoes subcellular redistribution and nucleolar accumulation in response to proteotoxic stress and mild heat shock. In unstressed cells, the long N-terminal isoforms displayed distinct subcellular distribution patterns, ranging from a predominantly cytoplasmic to almost exclusive nuclear localization, suggesting functional differences among the RDM1 proteins. However, all isoforms underwent stress-induced nucleolar accumulation. We identified nuclear and nucleolar localization determinants as well as domains conferring cytoplasmic retention to the RDM1 proteins. Finally, RDM1 null chicken DT40 cells displayed an increased sensitivity to heat shock, compared to wild-type (wt) cells, suggesting a function for RDM1 in the heat-shock response.
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Affiliation(s)
- Lydia Messaoudi
- International Agency for Research on Cancer (IARC), 150 Cours Albert Thomas, 69372 Lyon, France, Department of Human Genetics, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-Ku, Hiroshima, Japan 734-8553, Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA, Laboratoire de Biologie Moléculaire des Eucaryotes, LBME-CNRS UMR 5099 - IFR 109, Université Paul Sabatier, 118, Route de Narbonne, 31062 Toulouse, France and Institute for Molecular Radiobiology, GSF, Ingolstaedter Landstrasse 1, D-85764 Neuherberg-Munich, Germany
| | - Yun-Gui Yang
- International Agency for Research on Cancer (IARC), 150 Cours Albert Thomas, 69372 Lyon, France, Department of Human Genetics, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-Ku, Hiroshima, Japan 734-8553, Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA, Laboratoire de Biologie Moléculaire des Eucaryotes, LBME-CNRS UMR 5099 - IFR 109, Université Paul Sabatier, 118, Route de Narbonne, 31062 Toulouse, France and Institute for Molecular Radiobiology, GSF, Ingolstaedter Landstrasse 1, D-85764 Neuherberg-Munich, Germany
| | - Aiko Kinomura
- International Agency for Research on Cancer (IARC), 150 Cours Albert Thomas, 69372 Lyon, France, Department of Human Genetics, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-Ku, Hiroshima, Japan 734-8553, Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA, Laboratoire de Biologie Moléculaire des Eucaryotes, LBME-CNRS UMR 5099 - IFR 109, Université Paul Sabatier, 118, Route de Narbonne, 31062 Toulouse, France and Institute for Molecular Radiobiology, GSF, Ingolstaedter Landstrasse 1, D-85764 Neuherberg-Munich, Germany
| | - Diana A. Stavreva
- International Agency for Research on Cancer (IARC), 150 Cours Albert Thomas, 69372 Lyon, France, Department of Human Genetics, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-Ku, Hiroshima, Japan 734-8553, Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA, Laboratoire de Biologie Moléculaire des Eucaryotes, LBME-CNRS UMR 5099 - IFR 109, Université Paul Sabatier, 118, Route de Narbonne, 31062 Toulouse, France and Institute for Molecular Radiobiology, GSF, Ingolstaedter Landstrasse 1, D-85764 Neuherberg-Munich, Germany
| | - Gonghong Yan
- International Agency for Research on Cancer (IARC), 150 Cours Albert Thomas, 69372 Lyon, France, Department of Human Genetics, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-Ku, Hiroshima, Japan 734-8553, Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA, Laboratoire de Biologie Moléculaire des Eucaryotes, LBME-CNRS UMR 5099 - IFR 109, Université Paul Sabatier, 118, Route de Narbonne, 31062 Toulouse, France and Institute for Molecular Radiobiology, GSF, Ingolstaedter Landstrasse 1, D-85764 Neuherberg-Munich, Germany
| | - Marie-Line Bortolin-Cavaillé
- International Agency for Research on Cancer (IARC), 150 Cours Albert Thomas, 69372 Lyon, France, Department of Human Genetics, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-Ku, Hiroshima, Japan 734-8553, Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA, Laboratoire de Biologie Moléculaire des Eucaryotes, LBME-CNRS UMR 5099 - IFR 109, Université Paul Sabatier, 118, Route de Narbonne, 31062 Toulouse, France and Institute for Molecular Radiobiology, GSF, Ingolstaedter Landstrasse 1, D-85764 Neuherberg-Munich, Germany
| | - Hiroshi Arakawa
- International Agency for Research on Cancer (IARC), 150 Cours Albert Thomas, 69372 Lyon, France, Department of Human Genetics, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-Ku, Hiroshima, Japan 734-8553, Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA, Laboratoire de Biologie Moléculaire des Eucaryotes, LBME-CNRS UMR 5099 - IFR 109, Université Paul Sabatier, 118, Route de Narbonne, 31062 Toulouse, France and Institute for Molecular Radiobiology, GSF, Ingolstaedter Landstrasse 1, D-85764 Neuherberg-Munich, Germany
| | - Jean-Marie Buerstedde
- International Agency for Research on Cancer (IARC), 150 Cours Albert Thomas, 69372 Lyon, France, Department of Human Genetics, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-Ku, Hiroshima, Japan 734-8553, Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA, Laboratoire de Biologie Moléculaire des Eucaryotes, LBME-CNRS UMR 5099 - IFR 109, Université Paul Sabatier, 118, Route de Narbonne, 31062 Toulouse, France and Institute for Molecular Radiobiology, GSF, Ingolstaedter Landstrasse 1, D-85764 Neuherberg-Munich, Germany
| | - Pierre Hainaut
- International Agency for Research on Cancer (IARC), 150 Cours Albert Thomas, 69372 Lyon, France, Department of Human Genetics, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-Ku, Hiroshima, Japan 734-8553, Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA, Laboratoire de Biologie Moléculaire des Eucaryotes, LBME-CNRS UMR 5099 - IFR 109, Université Paul Sabatier, 118, Route de Narbonne, 31062 Toulouse, France and Institute for Molecular Radiobiology, GSF, Ingolstaedter Landstrasse 1, D-85764 Neuherberg-Munich, Germany
| | - Jérome Cavaillé
- International Agency for Research on Cancer (IARC), 150 Cours Albert Thomas, 69372 Lyon, France, Department of Human Genetics, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-Ku, Hiroshima, Japan 734-8553, Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA, Laboratoire de Biologie Moléculaire des Eucaryotes, LBME-CNRS UMR 5099 - IFR 109, Université Paul Sabatier, 118, Route de Narbonne, 31062 Toulouse, France and Institute for Molecular Radiobiology, GSF, Ingolstaedter Landstrasse 1, D-85764 Neuherberg-Munich, Germany
| | - Minoru Takata
- International Agency for Research on Cancer (IARC), 150 Cours Albert Thomas, 69372 Lyon, France, Department of Human Genetics, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-Ku, Hiroshima, Japan 734-8553, Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA, Laboratoire de Biologie Moléculaire des Eucaryotes, LBME-CNRS UMR 5099 - IFR 109, Université Paul Sabatier, 118, Route de Narbonne, 31062 Toulouse, France and Institute for Molecular Radiobiology, GSF, Ingolstaedter Landstrasse 1, D-85764 Neuherberg-Munich, Germany
| | - Eric Van Dyck
- International Agency for Research on Cancer (IARC), 150 Cours Albert Thomas, 69372 Lyon, France, Department of Human Genetics, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-Ku, Hiroshima, Japan 734-8553, Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA, Laboratoire de Biologie Moléculaire des Eucaryotes, LBME-CNRS UMR 5099 - IFR 109, Université Paul Sabatier, 118, Route de Narbonne, 31062 Toulouse, France and Institute for Molecular Radiobiology, GSF, Ingolstaedter Landstrasse 1, D-85764 Neuherberg-Munich, Germany
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Tillemans V, Leponce I, Rausin G, Dispa L, Motte P. Insights into nuclear organization in plants as revealed by the dynamic distribution of Arabidopsis SR splicing factors. THE PLANT CELL 2006; 18:3218-34. [PMID: 17114353 PMCID: PMC1693954 DOI: 10.1105/tpc.106.044529] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Serine/arginine-rich (SR) proteins are splicing regulators that share a modular structure consisting of one or two N-terminal RNA recognition motif domains and a C-terminal RS-rich domain. We investigated the dynamic localization of the Arabidopsis thaliana SR protein RSZp22, which, as we showed previously, distributes in predominant speckle-like structures and in the nucleolus. To determine the role of RSZp22 diverse domains in its nucleolar distribution, we investigated the subnuclear localization of domain-deleted mutant proteins. Our results suggest that the nucleolar localization of RSZp22 does not depend on a single targeting signal but likely involves different domains/motifs. Photobleaching experiments demonstrated the unrestricted dynamics of RSZp22 between nuclear compartments. Selective inhibitor experiments of ongoing cellular phosphorylation influenced the rates of exchange of RSZp22 between the different nuclear territories, indicating that SR protein mobility is dependent on the phosphorylation state of the cell. Furthermore, based on a leptomycin B- and fluorescence loss in photobleaching-based sensitive assay, we suggest that RSZp22 is a nucleocytoplasmic shuttling protein. Finally, with electron microscopy, we confirmed that RSp31, a plant-specific SR protein, is dynamically distributed in nucleolar cap-like structures upon phosphorylation inhibition. Our findings emphasize the high mobility of Arabidopsis SR splicing factors and provide insights into the dynamic relationships between the different nuclear compartments.
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Affiliation(s)
- Vinciane Tillemans
- Laboratory of Plant Cell and Molecular Biology, Department of Life Sciences, Institute of Botany, University of Liège, B-4000 Liège, Belgium
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27
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Ghorbel S, Sinha-Datta U, Dundr M, Brown M, Franchini G, Nicot C. Human T-cell leukemia virus type I p30 nuclear/nucleolar retention is mediated through interactions with RNA and a constituent of the 60 S ribosomal subunit. J Biol Chem 2006; 281:37150-8. [PMID: 17008317 DOI: 10.1074/jbc.m603981200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Human T-cell leukemia virus type I is the etiological agent of adult T-cell leukemia/lymphoma, an aggressive and fatal lymphoproliferative malignancy. The virus has evolved strategies to escape immune clearance by remaining latent in most infected cells in vivo. We demonstrated previously that virally encoded p30 protein is a potent post-transcriptional inhibitor of virus replication (Nicot, C., Dundr, M., Johnson, J. M., Fullen, J. R., Alonzo, N., Fukumoto, R., Princler, G. L., Derse, D., Misteli, T., and Franchini, G. (2004) Nat. Med. 10, 197-201). p30 is unable to shuttle out of the nucleus in heterokaryon assays, suggesting the existence of specific retention signals. Because suppression of virus replication relies on nuclear retention of the tax/rex mRNA by p30, determining the retention features of p30 will offer hints to break latency in infected cells and insights into new therapeutic approaches. In this study, we used live cell imaging technologies to study the kinetics of p30 and to delineate its retention signals and their function in virus replication. Notably, this is the first study to identify p30 nucleolar retention domains. Using mutants of p30 that localized in different cellular compartments, we show that post-transcriptional control of virus replication by p30 occurs in the nucleoplasm. We further demonstrate that p30 nuclear/nucleolar retention is dependent upon de novo RNA transcripts and interactions with components of the ribosomal machinery.
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Affiliation(s)
- Sofiane Ghorbel
- Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kansas City, Kansas 66160-7420, USA
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28
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Wu YL, Dudognon C, Nguyen E, Hillion J, Pendino F, Tarkanyi I, Aradi J, Lanotte M, Tong JH, Chen GQ, Ségal-Bendirdjian E. Immunodetection of human telomerase reverse-transcriptase (hTERT) re-appraised: nucleolin and telomerase cross paths. J Cell Sci 2006; 119:2797-806. [PMID: 16772337 DOI: 10.1242/jcs.03001] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The involvement of telomerase in cellular immortalization and senescence has often been assessed by means of telomerase expression at the RNA level and quantification of telomerase activity by the telomeric repeat amplification protocol assay. However, these methods either neglected the existence of various telomerase splice variants, or ignored the nonconventional functions of telomerase independent of its ability to elongate and maintain telomere length. Immunodetection of telomerase is now being recognized as a necessary approach to precisely elucidate its roles in oncogenesis and senescence. A few antibodies directed against the catalytic subunit of the human telomerase (hTERT) are currently used but their specificity is not always demonstrated. A survey of the literature showed inconsistencies and led us to comparatively re-evaluate the most frequently used antibodies. Surprisingly, mass spectrometry, two-dimensional gel analysis and immunofluorescent experiments revealed that the most frequently used hTERT immunoprobe, a mouse monoclonal antibody that was claimed to be directed against an hTERT protein epitope, in fact recognizes nucleolin rather than telomerase. Our findings have interesting implications regarding the biology of nucleolin and telomerase in the context of pathophysiological investigations recently carried out.
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Affiliation(s)
- Ying-Li Wu
- INSERM U685, Hôpital Saint-Louis, Institut d'Hématologie, 1 avenue Claude Vellefaux, 75010 Paris, France
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29
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Cloutier M, Vigneault F, Lachance D, Séguin A. Characterization of a poplar NIMA-related kinase PNek1 and its potential role in meristematic activity. FEBS Lett 2005; 579:4659-65. [PMID: 16098516 DOI: 10.1016/j.febslet.2005.07.036] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2005] [Revised: 07/11/2005] [Accepted: 07/12/2005] [Indexed: 12/14/2022]
Abstract
Meristems are sites of undifferentiated cell division, which carry on developing into functional organs. Using the two-hybrid system with a poplar 14-3-3, we uncovered poplar NIMA-related kinase 1 (PNek1) as an interacting protein. PNek1 shows high homology to the mammalian NIMA-related kinases, which are thought to be involved in cell cycle progression. Using a synchronized poplar cell suspension, we observed an accumulation of PNek1 mRNA at the G1/S transition and throughout the G2-to-M progression. Moreover, PNek1-GFP fusion protein localized in the cytoplasm and in both the nuclear and nucleolar regions. Overexpression of PNek1-GFP in Arabidopsis caused morphological abnormalities in flower and siliques. Overall, these results suggest that PNek1 is involved in plant development.
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Affiliation(s)
- Monikca Cloutier
- Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, 1055 du P.E.P.S., P.O. Box 3800, Sainte-Foy, Que., Canada
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30
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Song Z, Wu M. Identification of a novel nucleolar localization signal and a degradation signal in Survivin-deltaEx3: a potential link between nucleolus and protein degradation. Oncogene 2005; 24:2723-34. [PMID: 15735764 DOI: 10.1038/sj.onc.1208097] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
For a long time, as the most prominent subnuclear structure, nucleolus has been recognized as a main site where rRNA processing and ribosomal subunit assemblies take place. It has not been until recently that additional functions of nucleolus have begun to be proposed. In this study, we for the first time demonstrate that Survivin-deltaEx3, a novel functionally splice variant of Survivin localizes in the nucleoli where it degrades rapidly through ubiquitin-proteosome pathway. Several lines of evidences provided in this report support this finding (i) a novel nucleolar localization sequence (NoLS, MQRKPTIRRKNLRLRRK) and a novel degradation signal (aa92-aa137) within Survivin-deltaEx3 were identified (ii) proteasome inhibitors MG132 or ALLN greatly inhibits degradation of Survivin-deltaEx3 and polyubiquitination of Survivin-deltaEx3 was detected (iii) heterologous proteins such as TAT-PTD or p14ARF, when fused to this putative degradation signal, result in a significant degradation within the nucleolus. In addition, the nucleolar localization and degradation of Survivin-deltaEx3 appear to be required for its antiapoptotic function, since neither NoLS-deleted nor degradation signal-deleted Survivin-deltaEx3 retains protective effect against Doxorubicin-induced apoptosis. Thus, our results have provided evidences to suggest that besides cytosol, nucleus, endoplsmic reticulum (ER) or lysosomes, nucleolus may also operate important protein degradation pathway, which has been overlooked previously.
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Affiliation(s)
- Zhiyin Song
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, People's Republic of China
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Metz A, Soret J, Vourc'h C, Tazi J, Jolly C. A key role for stress-induced satellite III transcripts in the relocalization of splicing factors into nuclear stress granules. J Cell Sci 2005; 117:4551-8. [PMID: 15331664 DOI: 10.1242/jcs.01329] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Exposure of cells to stressful conditions results in the rapid synthesis of a subset of specialized proteins termed heat shock proteins (HSPs) which function in protecting the cell against damage. The stress-induced activation of hsp genes is controlled by the heat shock transcription factor 1 (HSF1). At the cellular level, one of the most striking effects of stress is the rapid and reversible redistribution of HSF1 into a few nuclear structures termed nuclear stress granules which form primarily on the 9q12 locus in humans. Within these structures, HSF1 binds to satellite III repeated elements and drives the RNA polymerase II-dependent transcription of these sequences into stable RNAs which remain associated with the 9q12 locus for a certain time after synthesis. Other proteins, in particular splicing factors, were also shown to relocalize to the granules upon stress. Here, we investigated the role of stress-induced satellite III transcripts in the relocalization of splicing factors to the granules. We show that the recruitment of the two serine/arginine-rich (SR) proteins SF2/ASF and SRp30c requires the presence of stress-induced satellite III transcripts. In agreement with these findings, we identified the second RNA-recognition motif (RRM2) of hSF2/ASF as the motif required for the targeting to the granules, and we showed by immunoprecipitation that the endogenous hSF2/ASF protein is present in a complex with satellite III transcripts in stressed cells in vivo. Interestingly, satellite III transcripts also immunoprecipitate together with small nuclear ribonucleoproteins (snRNPs) in vivo whereas the intronless hsp70 transcripts do not, supporting the proposal that these transcripts are subject to splicing. Altogether, these data highlight the central role for satellite III transcripts in the targeting and/or retention of splicing factors into the granules upon stress.
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Affiliation(s)
- Alexandra Metz
- INSERM U309, Institut Albert Bonniot, Domaine de la Merci, 38706 La Tronche CEDEX, France
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Kim K, Dimitrova DD, Carta KM, Saxena A, Daras M, Borowiec JA. Novel checkpoint response to genotoxic stress mediated by nucleolin-replication protein a complex formation. Mol Cell Biol 2005; 25:2463-74. [PMID: 15743838 PMCID: PMC1061594 DOI: 10.1128/mcb.25.6.2463-2474.2005] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2004] [Revised: 06/14/2004] [Accepted: 12/13/2004] [Indexed: 11/20/2022] Open
Abstract
Human replication protein A (RPA), the primary single-stranded DNA-binding protein, was previously found to be inhibited after heat shock by complex formation with nucleolin. Here we show that nucleolin-RPA complex formation is stimulated after genotoxic stresses such as treatment with camptothecin or exposure to ionizing radiation. Complex formation in vitro and in vivo requires a 63-residue glycine-arginine-rich (GAR) domain located at the extreme C terminus of nucleolin, with this domain sufficient to inhibit DNA replication in vitro. Fluorescence resonance energy transfer studies demonstrate that the nucleolin-RPA interaction after stress occurs both in the nucleoplasm and in the nucleolus. Expression of the GAR domain or a nucleolin mutant (TM) with a constitutive interaction with RPA is sufficient to inhibit entry into S phase. Increasing cellular RPA levels by overexpression of the RPA2 subunit minimizes the inhibitory effects of nucleolin GAR or TM expression on chromosomal DNA replication. The arrest is independent of p53 activation by ATM or ATR and does not involve heightened expression of p21. Our data reveal a novel cellular mechanism that represses genomic replication in response to genotoxic stress by inhibition of an essential DNA replication factor.
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Affiliation(s)
- Kyung Kim
- Department of Biochemistry, New York University School of Medicine, 550 First Ave., MSB-383, New York, NY 10016, USA
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Horke S, Reumann K, Schweizer M, Will H, Heise T. Nuclear trafficking of La protein depends on a newly identified nucleolar localization signal and the ability to bind RNA. J Biol Chem 2004; 279:26563-70. [PMID: 15060081 DOI: 10.1074/jbc.m401017200] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Here we provide evidence for an interaction-dependent subnuclear trafficking of the human La (hLa) protein, known as transient interaction partner of a variety of RNAs. Among these, precursor transcripts of certain RNAs are located in the nucleoplasm or nucleolus. Here we examined which functional domains of hLa are involved in its nuclear trafficking. By using green fluorescent-hLa fusion proteins, we discovered a nucleolar localization signal and demonstrated its functionality in a heterologous context. In addition, we revealed that the RRM2 motif of hLa is essential both for its RNA binding competence in vitro and in vivo and its exit from the nucleolus. Our data imply that hLa traffics between different subnuclear compartments, which depend decisively on a functional nucleolar localization signal as well as on RNA binding. Directed trafficking of hLa is fully consistent with its function in the maturation of precursor RNAs located in different subnuclear compartments.
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Affiliation(s)
- Sven Horke
- Heinrich-Pette-Institut fur Experimentelle Virologie und Immunologie an der Universitaat Hamburg, Martinistrasse 52, D-20251 Hamburg, Germany
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34
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Da Costa L, Tchernia G, Gascard P, Lo A, Meerpohl J, Niemeyer C, Chasis JA, Fixler J, Mohandas N. Nucleolar localization of RPS19 protein in normal cells and mislocalization due to mutations in the nucleolar localization signals in 2 Diamond-Blackfan anemia patients: potential insights into pathophysiology. Blood 2003; 101:5039-45. [PMID: 12586610 DOI: 10.1182/blood-2002-12-3878] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ribosomal protein S19 (RPS19) is frequently mutated in Diamond-Blackfan anemia (DBA), a rare congenital hypoplastic anemia. Recent studies have shown that RPS19 expression decreases during terminal erythroid differentiation. Currently no information is available on the subcellular localization of normal RPS19 and the potential effects of various RPS19 mutations on cellular localization. In the present study, using wild-type and mutant RPS19 cDNA, we explored the subcellular distribution of normal and mutant proteins in a fibroblast cell line (Cos-7 cells). RPS19 was detected primarily in the nucleus, and more specifically in the nucleoli, where RPS19 colocalized with the nucleolar protein nucleolin. Using various N-terminal and C-terminal deletion constructs, we identified 2 nucleolar localization signals (NoSs) in RPS19: the first comprising amino acids Met1 to Arg16 in the NH2-terminus and the second comprising Gly120 to Asn142 in the COOH-terminus. Importantly, 2 mutations identified in DBA patients, Val15Phe and Gly127Gln, each of which localized to 1 of the 2 NoS, failed to localize RPS19 to the nucleolus. In addition to their mislocalization, there was a dramatic decrease in the expression of the 2 mutant proteins compared to the wild type. This decrease in protein expression was specific for the mutant RPS19, since expression of other proteins was normal. The present findings enable us to document the nucleolar localization signals in RPS19 and help define the phenotypic consequences of some mutations in RPS19 in DBA.
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Affiliation(s)
- Lydie Da Costa
- Laboratoire d'Hématologie, Hôpital de Bicêtre, Le Kremlin Bicêtre, France.
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35
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Pellar GJ, DiMario PJ. Deletion and site-specific mutagenesis of nucleolin's carboxy GAR domain. Chromosoma 2003; 111:461-9. [PMID: 12707784 DOI: 10.1007/s00412-003-0231-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2002] [Revised: 11/05/2002] [Accepted: 12/06/2002] [Indexed: 11/25/2022]
Abstract
Vertebrate nucleolin is an abundant RNA-binding protein in the dense fibrillar component of active nucleoli. Nucleolin is modular in composition. Its amino-terminal third contains alternating acidic and basic domains, its middle section contains four consensus RNA-binding domains (cRBDs), and its carboxy-terminus contains a distinctive glycine/arginine-rich (GAR) domain with several RGG motifs. The arginines within these motifs are asymmetrically dimethylated. Several laboratories have shown that the GAR domain is necessary but not sufficient for the efficient localization of nucleolin to nucleoli. We examined the distribution of endogenous fibrillarin, Nopp140, and B23 when full-length and DeltaGAR nucleolin were expressed exogenously as enhanced green fluorescent protein (EGFP)-tagged fusions. Only B23 redistributed when DeltaGAR-EGFP was expressed at moderate to high levels, suggesting an in vivo interaction between nucleolin and B23. Next we substituted all ten arginines within the GAR domain of Chinese hamster ovary (CHO) nucleolin with lysines to test the hypothesis that methylation of the carboxy GAR domain is necessary for the nucleolar association of nucleolin. The lysine-substituted mutant was not an in vitro substrate for the yeast protein methyltransferase, Hmt1p/Rmt1. It was, however, able to associate properly with interphase nucleoli and with interphase pre-nucleolar bodies upon recovery from hypotonic shock. We conclude, therefore, that although the GAR domain is necessary for the efficient localization of nucleolin to nucleoli, methylation of this domain is not required for proper nucleolar localization.
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Affiliation(s)
- Gregory J Pellar
- Department of Biological Sciences, Louisiana State University, Baton Rouge 70803-1715, USA
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36
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von Kobbe C, Bohr VA. A nucleolar targeting sequence in the Werner syndrome protein resides within residues 949-1092. J Cell Sci 2002; 115:3901-7. [PMID: 12244128 DOI: 10.1242/jcs.00076] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Werner syndrome is a premature aging disorder caused by the lack of an active Werner syndrome protein (WRN). The patients suffer from many of the ailments seen at a much later stage in the life of normal individuals. WRN is a nuclear protein and contains a nuclear localization signal (NLS) in its C-terminal region. Inside the nucleus, WRN is mainly located in the nucleoli and in nuclear foci. To begin to understand the role of WRN in the nucleolus,we determined the specific regions of the protein that are responsible for this localization. We have cloned different WRN gene domains fused to enhanced green fluorescent protein (EGFP), and analyzed their intracellular distribution in living cells using confocal microscopy. The region encompassing amino acids 949-1092 of the human WRN, together with the NLS containing amino acids 1358-1432, provides the targeting to the nucleoli. This targeting is observed in three human and one mouse cell line. The NLS-containing region alone is unable to direct EGFP to the nucleoli. The results demonstrate that the human WRN contains a conserved nucleolar targeting sequence residing in a 144 amino acid region (aa 949-1092) and this provides new tools and insight into the biological function of WRN.
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Affiliation(s)
- Cayetano von Kobbe
- Laboratory of Molecular Gerontology, National Institute on Aging/NIH, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA
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Catez F, Erard M, Schaerer-Uthurralt N, Kindbeiter K, Madjar JJ, Diaz JJ. Unique motif for nucleolar retention and nuclear export regulated by phosphorylation. Mol Cell Biol 2002; 22:1126-39. [PMID: 11809804 PMCID: PMC134639 DOI: 10.1128/mcb.22.4.1126-1139.2002] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
By microinjecting purified glutathione S-transferase linked to all or parts of herpes simplex virus type 1 US11 protein into either the nucleus or the cytoplasm, we have demonstrated that this nucleolar protein exhibits a new type of localization signal controlling both retention in nucleoli and export to the cytoplasm. Saturated mutagenesis combined with computer modeling allowed us to draw the fine-structure map of this domain, revealing a new proline-rich motif harboring both activities, which are temperature dependent and regulated by phosphorylation. Finally, crossing the nuclear pore complex from the cytoplasm to the nucleus is an energy-dependent process for US11 protein, while getting to nucleoli through the nucleoplasm is energy independent.
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Affiliation(s)
- Frédéric Catez
- INSERM U369, Faculté de Médecine Lyon-René Théophile Hyacinthe Laennec, 69372 Lyon Cedex 08, France
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38
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Abstract
The Nopp140 gene of Drosophila maps within 79A5 of chromosome 3. Alternative splicing yields two variants. DmNopp140 (654 residues) is the sequence homolog of vertebrate Nopp140. Its carboxy terminus is 64% identical to that of the prototypical rat Nopp140. DmNopp140-RGG (688 residues) is identical to DmNopp140 throughout its first 551 residues, but its carboxy terminus contains a glycine/arginine-rich domain that is often found in RNA-binding proteins such as vertebrate nucleolin. Both Drosophila variants localize to nucleoli in Drosophila Schneider II cells and Xenopus oocytes, specifically within the dense fibrillar components. In HeLa cells, DmNopp140-RGG localizes to intact nucleoli, whereas DmNopp140 partitions HeLa nucleoli into phase-light and phase-dark regions. The phase-light regions contain DmNopp140 and endogenous fibrillarin, whereas the phase-dark regions contain endogenous nucleolin. When coexpressed, both Drosophila variants colocalize to HeLa cell nucleoli. Both variants fail to localize to endogenous Cajal bodies in Xenopus oocyte nuclei and in HeLa cell nuclei. Endogenous HeLa coilin, however, accumulates around the periphery of phase-light regions in cells expressing DmNopp140. The carboxy truncation (DmNopp140DeltaRGG) also fails to localize to Cajal bodies, but it forms similar phase-light regions that peripherally accumulate endogenous coilin. Conversely, we see no unusual accumulation of coilin in cells expressing DmNopp140-RGG.
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Affiliation(s)
- John M Waggener
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803-1715, USA
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39
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Gorczyca W, Smolewski P, Grabarek J, Ardelt B, Ita M, Melamed MR, Darzynkiewicz Z. Morphometry of nucleoli and expression of nucleolin analyzed by laser scanning cytometry in mitogenically stimulated lymphocytes. CYTOMETRY 2001; 45:206-13. [PMID: 11746089 DOI: 10.1002/1097-0320(20011101)45:3<206::aid-cyto1164>3.0.co;2-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
BACKGROUND Various attributes of nucleoli, including abundance of the nucleolar product (rRNA), correlate with cell-proliferative status and are useful markers for tumor diagnosis and prognosis. However, there is a paucity of methods that can quantitatively probe nucleolus. The aim of the present study was to utilize the morphometric capacity of the laser scanning cytometer (LSC) to analyze nucleoli and measure expression of the nucleolar protein nucleolin (NCL) in individual cells and correlate it with their state of proliferation. MATERIALS AND METHODS Human lymphocytes were mitogenically stimulated, and at different time points their nucleoli were detected immunocytochemically using NCL Ab. The frequency of nucleoli per nucleus, their area, and the level of expression of NCL, separately in the nuclear and nucleolar compartments, were estimated in relation to the G(0) to G(1) transition and the cell cycle progression. RESULTS During the first 24 h of stimulation, when the cells underwent G(0) to G(1) transition, their RNA content was increased nearly 8-fold, the level of NCL per nucleus also increased 8-fold, the NCL per nucleolus increased 12-fold, nucleolear area increased 3-fold, and NCL/nucleolar area increased nearly 4-fold. During the subsequent 24-48 h of stimulation, when cells were progressing through S, G(2), and M and reentering the next cycle, the number of nucleoli per nucleus was increased and a massive translocation of NCL from nucleoli to nucleoplasm was observed; its overall level per nucleus, however, still remained high, at 6-fold above of that of G(0) cells. CONCLUSIONS While high expression of NCL in the nucleolar compartment correlates with the rate of rRNA accumulation in the cell and is a sensitive marker of the G(0) to G(1) transition, the cells progressing through the remainder of the cycle are better distinguished from G(0) cells by high overall level of NCL within the nucleus. Such an analysis, when applied to tumors, may be helpful in obtaining the quantitative parameters related to the kinetic status of the tumor-cell population and tumor prognosis. The capability of LSC to measure the protein translocation between nucleolus and nucleoplasm can be used to study the function and regulatory mechanisms of other proteins that reside in these compartments.
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Affiliation(s)
- W Gorczyca
- Brander Cancer Research Institute, New York Medical College, Valhalla, New York, USA
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40
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Créancier L, Mercier P, Prats AC, Morello D. c-myc Internal ribosome entry site activity is developmentally controlled and subjected to a strong translational repression in adult transgenic mice. Mol Cell Biol 2001; 21:1833-40. [PMID: 11238920 PMCID: PMC86749 DOI: 10.1128/mcb.21.5.1833-1840.2001] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The expression of c-myc proto-oncogene, a key regulator of cell proliferation and apoptosis, is controlled at different transcriptional and posttranscriptional levels. In particular, the c-myc mRNA contains an internal ribosome entry site (IRES) able to promote translation initiation independently from the classical cap-dependent mechanism. We analyzed the variations of c-myc IRES activity ex vivo in different proliferating cell types, and in vivo in transgenic mice expressing a bicistronic dual luciferase construct. c-myc IRES efficiency was compared to that of encephalomyocarditis virus (EMCV) IRES under the same conditions. The c-myc IRES was active but with variable efficiency in all transiently transfected cell types; it was also active in the 11-day- old (E11) embryo and in some tissues of the E16 embryo. Strikingly, its activity was undetected or very low in all adult organs tested. In contrast, EMCV IRES was very active in most cell types ex vivo, as well as in embryonic and adult tissues. These data suggest a crucial role of IRES in the control of c-myc gene expression throughout development, either during embryogenesis where its activity might participate in cell proliferation or later on, where its silencing could contribute to the downregulation of c-myc expression, whose deregulation leads to tumor formation.
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Affiliation(s)
- L Créancier
- Institut National de la Santé et de la Recherche Médicale U397, Endocrinologie et Communication Cellulaire, Institut Fédératif de Recherche Louis Bugnard, C.H.U. Rangueil, 31403 Toulouse Cedex 04, France
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41
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Bacharach E, Gonsky J, Alin K, Orlova M, Goff SP. The carboxy-terminal fragment of nucleolin interacts with the nucleocapsid domain of retroviral gag proteins and inhibits virion assembly. J Virol 2000; 74:11027-39. [PMID: 11069998 PMCID: PMC113183 DOI: 10.1128/jvi.74.23.11027-11039.2000] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2000] [Accepted: 09/12/2000] [Indexed: 11/20/2022] Open
Abstract
A yeast two-hybrid screen for cellular proteins that interact with the murine leukemia virus (MuLV) Gag protein resulted in the identification of nucleolin, a host protein known to function in ribosome assembly. The interacting fusions contained the carboxy-terminal 212 amino acids of nucleolin [Nuc(212)]. The nucleocapsid (NC) portion of Gag was necessary and sufficient to mediate the binding to Nuc(212). The interaction of Gag with Nuc(212) could be demonstrated in vitro and was manifested in vivo by the NC-dependent incorporation of Nuc(212) inside MuLV virions. Overexpression of Nuc(212), but not full-length nucleolin, potently and specifically blocked MuLV virion assembly and/or release. A mutant of MuLV, selected to specifically disrupt the binding to Nuc(212), was found to be severely defective for virion assembly. This mutant harbors a single point mutation in capsid (CA) adjacent to the CA-NC junction, suggesting a role for this region in Moloney MuLV assembly. These experiments demonstrate that selection for proteins that bind assembly domain(s) can yield potent inhibitors of virion assembly. These experiments also raise the possibility that a nucleolin-Gag interaction may be involved in virion assembly.
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Affiliation(s)
- E Bacharach
- Howard Hughes Medical Institute, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA
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42
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Barneche F, Steinmetz F, Echeverrı́a M. Fibrillarin Genes Encode Both a Conserved Nucleolar Protein and a Novel Small Nucleolar RNA Involved in Ribosomal RNA Methylation inArabidopsis thaliana. J Biol Chem 2000. [DOI: 10.1016/s0021-9258(19)61499-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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43
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Warner AK, Sloboda RD. C-terminal domain of the mitotic apparatus protein p62 targets the protein to the nucleolus during interphase. CELL MOTILITY AND THE CYTOSKELETON 2000; 44:68-80. [PMID: 10470020 DOI: 10.1002/(sici)1097-0169(199909)44:1<68::aid-cm6>3.0.co;2-l] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Mitotic apparatuses from sea urchin embryos contain a protein (p62), previously shown to be required for mitotic progression. This protein localizes to the mitotic apparatus during cell division in urchin embryos and mammalian tissue culture cells. We show here by immunofluorescence that p62 is localized to the nucleus of mammalian cells during interphase and is highly concentrated in nucleoli. In addition, a fusion protein composed of full-length p62 and green fluorescent protein also localizes to nucleoli when expressed in COS-7 cells in culture. Analysis of the primary sequence of p62 reveals three distinct domains of the protein based on amino acid charge distribution: the acidic N-terminal domain, the basic C-terminal domain, and the central, M-domain, which contains alternating subdomains of clusters of acidic and basic residues. To identify the domain important for nucleolar localization during interphase, specific domains of p62 alone, or in combination with each other or with beta-galactosidase were fused to green fluorescent protein. Following confirmation of the fusion constructs by sequence analysis, the constructs were expressed in mammalian cells, expression was confirmed by immunoblotting, and the fusion proteins were localized via fluorescence microscopy. The data demonstrate that the C-terminal domain of p62 is both necessary and sufficient for the nuclear localization and nucleolar binding of p62 that is observed during interphase.
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Affiliation(s)
- A K Warner
- Department of Biological Sciences, 6044 Gilman Laboratory, Dartmouth College, Hanover, New Hampshire 03755, USA
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44
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Claussen M, Rudt F, Pieler T. Functional modules in ribosomal protein L5 for ribonucleoprotein complex formation and nucleocytoplasmic transport. J Biol Chem 1999; 274:33951-8. [PMID: 10567357 DOI: 10.1074/jbc.274.48.33951] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Ribosomal protein L5 forms a small, extraribosomal complex with 5 S ribosomal RNA, referred to as the 5 S ribonucleoprotein complex, which shuttles between nucleus and cytoplasm in Xenopus oocytes. Mapping elements in L5 that mediate nuclear protein import defines three separate such activities (L5-nuclear localization sequence (NLS)-1, -2, and -3), which are functional in both oocytes and somatic cells. RNA binding activity involves N-terminal as well as C-terminal elements of L5. In contrast to the full-length protein, none of the individual NLSs carrying L5 fragments are able to allow for the predominating accumulation in the nucleoli that is observed with the full-length protein. The separate L5-NLSs differ in respect to two activities. Firstly, only L5-NLS-1 and -3, not L5-NLS-2, are capable of promoting the nuclear transfer of a heterologous, covalently attached ribonucleoprotein complex. Secondly, only L5-NLS-1 is able to bind strongly to a variety of different import receptors; those that recognize L5-NLS-2 and -3 have yet to be identified.
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Affiliation(s)
- M Claussen
- Institut für Biochemie und Molekulare Zellbiologie, Georg-August-Universität, Humboldtallee 23, D-37073 Göttingen, Germany
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45
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Srivastava M, Pollard HB. Molecular dissection of nucleolin's role in growth and cell proliferation: new insights. FASEB J 1999. [DOI: 10.1096/fasebj.13.14.1911] [Citation(s) in RCA: 381] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Meera Srivastava
- Department of Anatomy and Cell BiologyUniformed Services University of Health Sciences Bethesda Maryland 20814 USA
| | - Harvey B. Pollard
- Department of Anatomy and Cell BiologyUniformed Services University of Health Sciences Bethesda Maryland 20814 USA
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46
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Jarrous N, Wolenski JS, Wesolowski D, Lee C, Altman S. Localization in the nucleolus and coiled bodies of protein subunits of the ribonucleoprotein ribonuclease P. J Cell Biol 1999; 146:559-72. [PMID: 10444065 PMCID: PMC2150555 DOI: 10.1083/jcb.146.3.559] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The precise location of the tRNA processing ribonucleoprotein ribonuclease P (RNase P) and the mechanism of its intranuclear distribution have not been completely delineated. We show that three protein subunits of human RNase P (Rpp), Rpp14, Rpp29 and Rpp38, are found in the nucleolus and that each can localize a reporter protein to nucleoli of cells in tissue culture. In contrast to Rpp38, which is uniformly distributed in nucleoli, Rpp14 and Rpp29 are confined to the dense fibrillar component. Rpp29 and Rpp38 possess functional, yet distinct domains required for subnucleolar localization. The subunit Rpp14 lacks such a domain and appears to be dependent on a piggyback process to reach the nucleolus. Biochemical analysis suggests that catalytically active RNase P exists in the nucleolus. We also provide evidence that Rpp29 and Rpp38 reside in coiled bodies, organelles that are implicated in the biogenesis of several other small nuclear ribonucleoproteins required for processing of precursor mRNA. Because some protein subunits of RNase P are shared by the ribosomal RNA processing ribonucleoprotein RNase MRP, these two evolutionary related holoenzymes may share common intranuclear localization and assembly pathways to coordinate the processing of tRNA and rRNA precursors.
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Affiliation(s)
- Nayef Jarrous
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520
| | - Joseph S. Wolenski
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520
| | - Donna Wesolowski
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520
| | - Christopher Lee
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520
| | - Sidney Altman
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520
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47
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Abstract
Nucleolin is a very abundant eukaryotic protein that localizes to the nucleolus, where the rDNA undergoes transcription, replication, and recombination and where rRNA processing occurs. The top (non-template) strand of the rDNA is very guanine-rich and has considerable potential to form structures stabilized by G-G pairing. We have assayed binding of endogenous and recombinant nucleolin to synthetic oligonucleotides in which G-rich regions have formed intermolecular G-G pairs to produce either two-stranded G2 or four-stranded G4 DNA. We report that nucleolin binds G-G-paired DNA with very high affinity; the dissociation constant for interaction with G4 DNA is KD = 1 nM. Two separate domains of nucleolin can interact with G-G-paired DNA, the four RNA binding domains and the C-terminal Arg-Gly-Gly repeats. Both domains bind G4 DNA with high specificity and recognize G4 DNA structure independent of sequence context. The high affinity of the nucleolin/G4 DNA interaction identifies G-G-paired structures as natural binding targets of nucleolin in the nucleolus. The ability of two independent domains of nucleolin to bind G-G-paired structures suggests that nucleolin can function as an architectural factor in rDNA transcription, replication, or recombination.
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Affiliation(s)
- L A Hanakahi
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06510-8024, USA
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48
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Abstract
Nucleolin is an abundant protein of the nucleolus. Nucleolar proteins structurally related to nucleolin are found in organisms ranging from yeast to plants and mammals. The association of several structural domains in nucleolin allows the interaction of nucleolin with different proteins and RNA sequences. Nucleolin has been implicated in chromatin structure, rDNA transcription, rRNA maturation, ribosome assembly and nucleo-cytoplasmic transport. Studies of nucleolin over the last 25 years have revealed a fascinating role for nucleolin in ribosome biogenesis. The involvement of nucleolin at multiple steps of this biosynthetic pathway suggests that it could play a key role in this highly integrated process.
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Affiliation(s)
- H Ginisty
- Laboratoire de Biologie Moléculaire Eucaryote, Institut de Biologie Cellulaire et de Génétique du CNRS, UPR 9006, 31062 Toulouse Cedex, France
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49
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Huez I, Créancier L, Audigier S, Gensac MC, Prats AC, Prats H. Two independent internal ribosome entry sites are involved in translation initiation of vascular endothelial growth factor mRNA. Mol Cell Biol 1998; 18:6178-90. [PMID: 9774635 PMCID: PMC109205 DOI: 10.1128/mcb.18.11.6178] [Citation(s) in RCA: 238] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The mRNA of vascular endothelial growth factor (VEGF), the major angiogenic growth factor, contains an unusually long (1,038 nucleotides) and structured 5' untranslated region (UTR). According to the classical translation initiation model of ribosome scanning, such a 5' UTR is expected to be a strong translation inhibitor. In vitro and bicistronic strategies were used to show that the VEGF mRNA translation was cap independent and occurred by an internal ribosome entry process. For the first time, we demonstrate that two independent internal ribosome entry sites (IRESs) are present in this 5' UTR. IRES A is located within the 300 nucleotides upstream from the AUG start codon. RNA secondary structure prediction and site-directed mutagenesis allowed the identification of a 49-nucleotide structural domain (D4) essential to IRES A activity. UV cross-linking experiments revealed that IRES A activity was correlated with binding of a 100-kDa protein to the D4 domain. IRES B is located in the first half of the 5' UTR. An element between nucleotides 379 and 483 is required for its activity. Immunoprecipitation experiments demonstrated that a main IRES B-bound protein was the polypyrimidine tract binding protein (PTB), a well-known regulator of picornavirus IRESs. However, we showed that binding of the PTB on IRES B does not seem to be correlated with its activity. Evidence is provided of an original cumulative effect of two IRESs, probably controlled by different factors, to promote an efficient initiation of translation at the same AUG codon.
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Affiliation(s)
- I Huez
- INSERM U397, Endocrinologie et Communication Cellulaire, Institut Fédératif de Recherche Louis Bugnard, CHU Rangueil, 31403 Toulouse cedex 04, France
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50
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Bouvet P, Diaz JJ, Kindbeiter K, Madjar JJ, Amalric F. Nucleolin interacts with several ribosomal proteins through its RGG domain. J Biol Chem 1998; 273:19025-9. [PMID: 9668083 DOI: 10.1074/jbc.273.30.19025] [Citation(s) in RCA: 159] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Nucleolin is one of the major nonribosomal proteins of the nucleolus. Through its four RNA-binding domains, nucleolin interacts specifically with pre-rRNA as soon as synthesis begins, but it is not found in mature cytoplasmic ribosomes. Nucleolin is able to shuttle between the cytoplasm and the nucleus. These data suggest that nucleolin might be involved in the nucleolar import of cytoplasmic components and in the assembly of pre-ribosomal particles. Here we show, using two-dimensional blots in a ligand blotting assay, that nucleolin interacts with 18 ribosomal proteins from rat (14 and 4 from the large and small subunit, respectively). The C-terminal domain of nucleolin (p50) interacts with 10 of these identified ribosomal proteins. In vitro binding assays show that the glycine-arginine rich domain of nucleolin (RGG domain) is sufficient for the interaction with one of these proteins. Interestingly, most of the proteins that interact with p50 belong to the core ribosomal proteins, which are resistant to extraction with high salt concentration. These findings suggest that nucleolin might be involved in the nucleolar targeting of some ribosomal proteins and in their assembly within pre-ribosomal particles.
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Affiliation(s)
- P Bouvet
- Laboratoire de Biologie Moléculaire Eucaryote, Institut de Biologie Cellulaire et de Génétique du CNRS, UPR 9006, 118 route de Narbonne, 31062 Toulouse Cedex, France.
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