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Add and Go: FRET Acceptor for Live-Cell Measurements Modulated by Externally Provided Ligand. Int J Mol Sci 2022; 23:ijms23084396. [PMID: 35457212 PMCID: PMC9026985 DOI: 10.3390/ijms23084396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 04/11/2022] [Accepted: 04/12/2022] [Indexed: 02/05/2023] Open
Abstract
A substantial number of genetically encoded fluorescent sensors rely on the changes in FRET efficiency between fluorescent cores, measured in ratiometric mode, with acceptor photobleaching or by changes in fluorescence lifetime. We report on a modulated FRET acceptor allowing for simplified one-channel FRET measurement based on a previously reported fluorogen-activating protein, DiB1. Upon the addition of the cell-permeable chromophore, the fluorescence of the donor-fluorescent protein mNeonGreen decreases, allowing for a simplified one-channel FRET measurement. The reported chemically modulated FRET acceptor is compatible with live-cell experiments and allows for prolonged time-lapse experiments with dynamic energy transfer evaluation.
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2
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González‐Arzola K, Guerra‐Castellano A, Rivero‐Rodríguez F, Casado‐Combreras MÁ, Pérez‐Mejías G, Díaz‐Quintana A, Díaz‐Moreno I, De la Rosa MA. Mitochondrial cytochrome c shot towards histone chaperone condensates in the nucleus. FEBS Open Bio 2021; 11:2418-2440. [PMID: 33938164 PMCID: PMC8409293 DOI: 10.1002/2211-5463.13176] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 04/26/2021] [Indexed: 12/15/2022] Open
Abstract
Despite mitochondria being key for the control of cell homeostasis and fate, their role in DNA damage response is usually just regarded as an apoptotic trigger. However, growing evidence points to mitochondrial factors modulating nuclear functions. Remarkably, after DNA damage, cytochrome c (Cc) interacts in the cell nucleus with a variety of well-known histone chaperones, whose activity is competitively inhibited by the haem protein. As nuclear Cc inhibits the nucleosome assembly/disassembly activity of histone chaperones, it might indeed affect chromatin dynamics and histone deposition on DNA. Several histone chaperones actually interact with Cc Lys residues through their acidic regions, which are also involved in heterotypic interactions leading to liquid-liquid phase transitions responsible for the assembly of nuclear condensates, including heterochromatin. This relies on dynamic histone-DNA interactions that can be modulated by acetylation of specific histone Lys residues. Thus, Cc may have a major regulatory role in DNA repair by fine-tuning nucleosome assembly activity and likely nuclear condensate formation.
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Affiliation(s)
- Katiuska González‐Arzola
- Institute for Chemical Research (IIQ)Scientific Research Centre Isla de la Cartuja (cicCartuja)University of Seville – CSICSpain
| | - Alejandra Guerra‐Castellano
- Institute for Chemical Research (IIQ)Scientific Research Centre Isla de la Cartuja (cicCartuja)University of Seville – CSICSpain
| | - Francisco Rivero‐Rodríguez
- Institute for Chemical Research (IIQ)Scientific Research Centre Isla de la Cartuja (cicCartuja)University of Seville – CSICSpain
| | - Miguel Á. Casado‐Combreras
- Institute for Chemical Research (IIQ)Scientific Research Centre Isla de la Cartuja (cicCartuja)University of Seville – CSICSpain
| | - Gonzalo Pérez‐Mejías
- Institute for Chemical Research (IIQ)Scientific Research Centre Isla de la Cartuja (cicCartuja)University of Seville – CSICSpain
| | - Antonio Díaz‐Quintana
- Institute for Chemical Research (IIQ)Scientific Research Centre Isla de la Cartuja (cicCartuja)University of Seville – CSICSpain
| | - Irene Díaz‐Moreno
- Institute for Chemical Research (IIQ)Scientific Research Centre Isla de la Cartuja (cicCartuja)University of Seville – CSICSpain
| | - Miguel A. De la Rosa
- Institute for Chemical Research (IIQ)Scientific Research Centre Isla de la Cartuja (cicCartuja)University of Seville – CSICSpain
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3
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Peggion C, Massimino ML, Stella R, Bortolotto R, Agostini J, Maldi A, Sartori G, Tonello F, Bertoli A, Lopreiato R. Nucleolin Rescues TDP-43 Toxicity in Yeast and Human Cell Models. Front Cell Neurosci 2021; 15:625665. [PMID: 33912014 PMCID: PMC8072491 DOI: 10.3389/fncel.2021.625665] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 03/18/2021] [Indexed: 12/12/2022] Open
Abstract
TDP-43 is a nuclear protein involved in pivotal processes, extensively studied for its implication in neurodegenerative disorders. TDP-43 cytosolic inclusions are a common neuropathologic hallmark in amyotrophic lateral sclerosis (ALS) and related diseases, and it is now established that TDP-43 misfolding and aggregation play a key role in their etiopathology. TDP-43 neurotoxic mechanisms are not yet clarified, but the identification of proteins able to modulate TDP-43-mediated damage may be promising therapeutic targets for TDP-43 proteinopathies. Here we show by the use of refined yeast models that the nucleolar protein nucleolin (NCL) acts as a potent suppressor of TDP-43 toxicity, restoring cell viability. We provide evidence that NCL co-expression is able to alleviate TDP-43-induced damage also in human cells, further supporting its beneficial effects in a more consistent pathophysiological context. Presented data suggest that NCL could promote TDP-43 nuclear retention, reducing the formation of toxic cytosolic TDP-43 inclusions.
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Affiliation(s)
- Caterina Peggion
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | | | - Roberto Stella
- Food Safety Division, Department of Chemistry, Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, Italy
| | - Raissa Bortolotto
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Jessica Agostini
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Arianna Maldi
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Geppo Sartori
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | | | - Alessandro Bertoli
- Department of Biomedical Sciences, University of Padova, Padova, Italy.,CNR - Neuroscience Institute, Padova, Italy.,Padova Neuroscience Center, University of Padova, Padova, Italy
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4
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Live-cell nanoscopy with spontaneous blinking of conventional green fluorescent proteins. Biochem Biophys Res Commun 2019; 522:852-854. [PMID: 31801668 DOI: 10.1016/j.bbrc.2019.11.163] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 11/24/2019] [Indexed: 11/20/2022]
Abstract
Single-molecule localization microscopy with spontaneously blinking fluorescent tags holds a promise of simplified imaging setup for live-cell application. However, robust blinking has been reported for just a few fluorescent proteins. Here we report on a comparison of spontaneous blinking for three bright green fluorescent proteins, mAvicFP1, AausFP1, and mNeonGreen. mAvicFP1 outperforms other fluorescent proteins in this list in a wide range of camera exposure times and illumination intensities. We establish imaging conditions for live-cell nanoscopy and single-particle tracking with mAvicFP1.
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5
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Iarovaia OV, Minina EP, Sheval EV, Onichtchouk D, Dokudovskaya S, Razin SV, Vassetzky YS. Nucleolus: A Central Hub for Nuclear Functions. Trends Cell Biol 2019; 29:647-659. [PMID: 31176528 DOI: 10.1016/j.tcb.2019.04.003] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 04/24/2019] [Accepted: 04/26/2019] [Indexed: 12/19/2022]
Abstract
The nucleolus is the largest and most studied nuclear body, but its role in nuclear function is far from being comprehensively understood. Much work on the nucleolus has focused on its role in regulating RNA polymerase I (RNA Pol I) transcription and ribosome biogenesis; however, emerging evidence points to the nucleolus as an organizing hub for many nuclear functions, accomplished via the shuttling of proteins and nucleic acids between the nucleolus and nucleoplasm. Here, we discuss the cellular mechanisms affected by shuttling of nucleolar components, including the 3D organization of the genome, stress response, DNA repair and recombination, transcription regulation, telomere maintenance, and other essential cellular functions.
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Affiliation(s)
- Olga V Iarovaia
- Institute of Gene Biology of the Russian Academy of Sciences, 119334 Moscow, Russia; LIA 1066 LFR2O French-Russian Joint Cancer Research Laboratory, 94805 Villejuif, France
| | - Elizaveta P Minina
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Eugene V Sheval
- LIA 1066 LFR2O French-Russian Joint Cancer Research Laboratory, 94805 Villejuif, France; Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia; Faculty of Biology, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Daria Onichtchouk
- Developmental Biology Unit, Department of Biology I, University of Freiburg, Hauptstrasse 1, D-79104 Freiburg, Germany
| | - Svetlana Dokudovskaya
- LIA 1066 LFR2O French-Russian Joint Cancer Research Laboratory, 94805 Villejuif, France; UMR8126, Université Paris-Sud, CNRS, Institut Gustave Roussy, 94805 Villejuif, France
| | - Sergey V Razin
- Institute of Gene Biology of the Russian Academy of Sciences, 119334 Moscow, Russia; LIA 1066 LFR2O French-Russian Joint Cancer Research Laboratory, 94805 Villejuif, France; Faculty of Biology, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Yegor S Vassetzky
- LIA 1066 LFR2O French-Russian Joint Cancer Research Laboratory, 94805 Villejuif, France; Koltzov Institute of Developmental Biology of the Russian Academy of Sciences, 119334 Moscow, Russia; UMR8126, Université Paris-Sud, CNRS, Institut Gustave Roussy, 94805 Villejuif, France.
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6
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Kawamura K, Qi F, Meng Q, Hayashi I, Kobayashi J. Nucleolar protein nucleolin functions in replication stress-induced DNA damage responses. JOURNAL OF RADIATION RESEARCH 2019; 60:281-288. [PMID: 30839063 PMCID: PMC6530621 DOI: 10.1093/jrr/rry114] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 12/23/2018] [Indexed: 05/05/2023]
Abstract
The nucleolus contains multiple copies of ribosomal (r)DNA, which indicate sites of frequent replication stress and suggest the existence of a mechanism to prevent replication stress-related rDNA instability and the possibility that such a mechanism contributes to the whole genomic stability against replication stress. We have previously reported that nucleolin, a major nucleolar protein, is involved in ionizing radiation-induced DNA damage responses (DDRs) such as ataxia telangiectasia mutated (ATM)-dependent cell cycle checkpoints and homologous recombination (HR) repair. Here, we investigated the role of nucleolin in DDR due to replication stress. The results indicate that following replication stress, nucleolin interacted with the histone γH2AX, proliferating cell nuclear antigen (PCNA), and replication protein A (RPA)32, suggesting that it may be recruited to DNA damage sites on the replication fork. Furthermore, the knockdown of nucleolin by siRNA reduced the activation of ATM and RAD3-related (ATR) kinase and the formation of RAD51 and RPA32 foci after replication stress due to UV or camptothecin exposure, whereas nucleolin overexpression augmented ATR-dependent phosphorylation and RAD51 and RPA accumulation on chromatin. Moreover, these overexpressing cells seemed to increase repair activity and resistance to replication stress. Our results indicate that nucleolin plays an important role in replication stress-induced DDRs such as ATR activation and HR repair. Given that nucleolin overexpression is often observed in many types of cancer cells, our findings suggest that nucleolin is involved in the regulation of resistance to replication stress that may otherwise lead to tumorigenesis and it could be a possible target for chemotherapy and radiotherapy.
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Affiliation(s)
- Kasumi Kawamura
- Department of Interdisciplinary Environment, Graduate School of Human and Environmental Sciences, Kyoto University, Yoshidanihonmatsucho, Sakyo-ku, Kyoto, Japan
| | - Fei Qi
- Department of Interdisciplinary Environment, Graduate School of Human and Environmental Sciences, Kyoto University, Yoshidanihonmatsucho, Sakyo-ku, Kyoto, Japan
| | - Qingmei Meng
- Department of Interdisciplinary Environment, Graduate School of Human and Environmental Sciences, Kyoto University, Yoshidanihonmatsucho, Sakyo-ku, Kyoto, Japan
| | - Ikue Hayashi
- Graduate School of Biomedical Sciences, Hiroshima University, Kasumi1-2-3, Minamiku, Hiroshima, Japan
| | - Junya Kobayashi
- Department of Interdisciplinary Environment, Graduate School of Human and Environmental Sciences, Kyoto University, Yoshidanihonmatsucho, Sakyo-ku, Kyoto, Japan
- Department of Genome Repair Dynamics, Radiation Biology Center, Graduate School of Biostudies, Kyoto University, Yoshidakonoecho, Sakyo-ku, Kyoto, Japan
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7
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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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8
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Kumar S, Gomez EC, Chalabi-Dchar M, Rong C, Das S, Ugrinova I, Gaume X, Monier K, Mongelard F, Bouvet P. Integrated analysis of mRNA and miRNA expression in HeLa cells expressing low levels of Nucleolin. Sci Rep 2017; 7:9017. [PMID: 28827664 PMCID: PMC5567140 DOI: 10.1038/s41598-017-09353-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 07/26/2017] [Indexed: 01/30/2023] Open
Abstract
Nucleolin is an essential protein that plays important roles in the regulation of cell cycle and cell proliferation. Its expression is up regulated in many cancer cells but its molecular functions are not well characterized. Nucleolin is present in the nucleus where it regulates gene expression at the transcriptional and post-transcriptional levels. Using HeLa cells depleted in nucleolin we performed an mRNA and miRNA transcriptomics analysis to identify biological pathways involving nucleolin. Bioinformatic analysis strongly points to a role of nucleolin in lipid metabolism, and in many signaling pathways. Down regulation of nucleolin is associated with lower level of cholesterol while the amount of fatty acids is increased. This could be explained by the decreased and mis-localized expression of the transcription factor SREBP1 and the down-regulation of enzymes involved in the beta-oxidation and degradation of fatty acids. Functional classification of the miRNA-mRNA target genes revealed that deregulated miRNAs target genes involved in apoptosis, proliferation and signaling pathways. Several of these deregulated miRNAs have been shown to control lipid metabolism. This integrated transcriptomic analysis uncovers new unexpected roles for nucleolin in metabolic regulation and signaling pathways paving the way to better understand the global function of nucleolin within the cell.
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Affiliation(s)
- Sanjeev Kumar
- BioCOS Life Sciences Private Limited, AECS Layout, B-Block, Singasandra Hosur Road SAAMI Building, 851/A, 3rd Floor, Bengaluru, Karnataka, India.
| | - Elizabhet Cruz Gomez
- Université de Lyon, Centre de Recherche en Cancérologie de Lyon, Cancer Cell Plasticity Department, UMR INSERM 1052 CNRS, 5286, Centre Léon Bérard, Lyon, France
| | - Mounira Chalabi-Dchar
- Université de Lyon, Centre de Recherche en Cancérologie de Lyon, Cancer Cell Plasticity Department, UMR INSERM 1052 CNRS, 5286, Centre Léon Bérard, Lyon, France
| | - Cong Rong
- Université de Lyon, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Sadhan Das
- Université de Lyon, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Iva Ugrinova
- Institute of Molecular Biology "Acad. Roumen Tsanev" Bulgarian Academy of Sciences "Acad. G Bonchev str. bl. 21, 1113, Sofia, Bulgaria
| | - Xavier Gaume
- Université de Lyon, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Karine Monier
- Université de Lyon, Centre de Recherche en Cancérologie de Lyon, Cancer Cell Plasticity Department, UMR INSERM 1052 CNRS, 5286, Centre Léon Bérard, Lyon, France
| | - Fabien Mongelard
- Université de Lyon, Centre de Recherche en Cancérologie de Lyon, Cancer Cell Plasticity Department, UMR INSERM 1052 CNRS, 5286, Centre Léon Bérard, Lyon, France
- Université de Lyon, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Philippe Bouvet
- Université de Lyon, Centre de Recherche en Cancérologie de Lyon, Cancer Cell Plasticity Department, UMR INSERM 1052 CNRS, 5286, Centre Léon Bérard, Lyon, France.
- Université de Lyon, Ecole Normale Supérieure de Lyon, Lyon, France.
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Warren C, Shechter D. Fly Fishing for Histones: Catch and Release by Histone Chaperone Intrinsically Disordered Regions and Acidic Stretches. J Mol Biol 2017; 429:2401-2426. [PMID: 28610839 DOI: 10.1016/j.jmb.2017.06.005] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 06/05/2017] [Accepted: 06/06/2017] [Indexed: 01/21/2023]
Abstract
Chromatin is the complex of eukaryotic DNA and proteins required for the efficient compaction of the nearly 2-meter-long human genome into a roughly 10-micron-diameter cell nucleus. The fundamental repeating unit of chromatin is the nucleosome: 147bp of DNA wrapped about an octamer of histone proteins. Nucleosomes are stable enough to organize the genome yet must be dynamically displaced and reassembled to allow access to the underlying DNA for transcription, replication, and DNA damage repair. Histone chaperones are a non-catalytic group of proteins that are central to the processes of nucleosome assembly and disassembly and thus the fluidity of the ever-changing chromatin landscape. Histone chaperones are responsible for binding the highly basic histone proteins, shielding them from non-specific interactions, facilitating their deposition onto DNA, and aiding in their eviction from DNA. Although most histone chaperones perform these common functions, recent structural studies of many different histone chaperones reveal that there are few commonalities in their folds. Importantly, sequence-based predictions show that histone chaperones are highly enriched in intrinsically disordered regions (IDRs) and acidic stretches. In this review, we focus on the molecular mechanisms underpinning histone binding, selectivity, and regulation of these highly dynamic protein regions. We highlight new evidence suggesting that IDRs are often critical for histone chaperone function and play key roles in chromatin assembly and disassembly pathways.
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Affiliation(s)
- Christopher Warren
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - David Shechter
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
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10
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Buschbeck M, Hake SB. Variants of core histones and their roles in cell fate decisions, development and cancer. Nat Rev Mol Cell Biol 2017; 18:299-314. [DOI: 10.1038/nrm.2016.166] [Citation(s) in RCA: 217] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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11
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Gaume X, Place C, Delage H, Mongelard F, Monier K, Bouvet P. Expression of Nucleolin Affects Microtubule Dynamics. PLoS One 2016; 11:e0157534. [PMID: 27309529 PMCID: PMC4911123 DOI: 10.1371/journal.pone.0157534] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 06/01/2016] [Indexed: 02/01/2023] Open
Abstract
Nucleolin is present in diverse cellular compartments and is involved in a variety of cellular processes from nucleolar structure and function to intracellular trafficking, cell adhesion and migration. Recently, nucleolin has been localized at the mature centriole where it is involved in microtubule nucleation and anchoring. Although this new function of nucleolin linked to microtubule regulation has been identified, the global effects of nucleolin on microtubule dynamics have not been addressed yet. In the present study, we analyzed the roles of nucleolin protein levels on global microtubule dynamics by tracking the EB3 microtubule plus end binding protein in live cells. We have found that during microtubule growth phases, nucleolin affects both the speed and life time of polymerization and by analyzing catastrophe events, we showed that nucleolin reduces catastrophe frequency. This new property of nucleolin was then confirmed in a cold induced microtubule depolymerization experiment in which we have found that cold resistant microtubules were totally destabilized in nucleolin depleted cells. Altogether, our data demonstrate a new function of nucleolin on microtubule stabilization, thus bringing novel insights into understanding the multifunctional properties of nucleolin in healthy and cancer cells.
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Affiliation(s)
- Xavier Gaume
- Université de Lyon, Ecole normale Supérieure de Lyon, Centre de Recherche en Cancérologie de Lyon, Cancer Cell Plasticity Department, UMR INSERM 1052 CNRS 5286, Centre Léon Bérard, Lyon, France
| | - Christophe Place
- Université de Lyon, Ecole Normale Supérieure de Lyon, Université Claude Bernard, CNRS, Laboratoire de Physique, F-69342, Lyon, France
| | - Helene Delage
- Université de Lyon, Ecole normale Supérieure de Lyon, Centre de Recherche en Cancérologie de Lyon, Cancer Cell Plasticity Department, UMR INSERM 1052 CNRS 5286, Centre Léon Bérard, Lyon, France
| | - Fabien Mongelard
- Université de Lyon, Ecole normale Supérieure de Lyon, Centre de Recherche en Cancérologie de Lyon, Cancer Cell Plasticity Department, UMR INSERM 1052 CNRS 5286, Centre Léon Bérard, Lyon, France
| | - Karine Monier
- Université de Lyon, Ecole normale Supérieure de Lyon, Centre de Recherche en Cancérologie de Lyon, Cancer Cell Plasticity Department, UMR INSERM 1052 CNRS 5286, Centre Léon Bérard, Lyon, France
| | - Philippe Bouvet
- Université de Lyon, Ecole normale Supérieure de Lyon, Centre de Recherche en Cancérologie de Lyon, Cancer Cell Plasticity Department, UMR INSERM 1052 CNRS 5286, Centre Léon Bérard, Lyon, France
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12
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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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13
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Durut N, Sáez-Vásquez J. Nucleolin: dual roles in rDNA chromatin transcription. Gene 2015; 556:7-12. [PMID: 25225127 DOI: 10.1016/j.gene.2014.09.023] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 09/08/2014] [Accepted: 09/09/2014] [Indexed: 01/17/2023]
Abstract
Nucleolin is a major nucleolar protein conserved in all eukaryotic organisms. It is a multifunctional protein involved in different cellular aspects like chromatin organization and stability, DNA and RNA metabolism, assembly of ribonucleoprotein complexes, cytokinesis, cell proliferation and stress response. The multifunctionality of nucleolin is linked to its tripartite structure, post-translational modifications and its ability of shuttling from and to the nucleolus/nucleoplasm and cytoplasm. Nucleolin has been now studied for many years and its activities and properties have been described in a number of excellent reviews. Here, we overview the role of nucleolin in RNA polymerase I (RNAPI) transcription and describe recent results concerning its functional interaction with rDNA chromatin organization. For a long time, nucleolin has been associated with rRNA gene expression and pre-rRNA processing. However, the functional connection between nucleolin and active versus inactive rRNA genes is still not fully understood. Novel evidence indicates that the nucleolin protein might be required for controlling the transcriptional ON/OFF states of rDNA chromatin in both mammals and plants.
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Affiliation(s)
- Nathalie Durut
- CNRS, Laboratoire Génome et Développement des Plantes, UMR 5096, 66860 Perpignan, France; Univ. Perpignan Via Domitia, Laboratoire Génome et Développement des Plantes, UMR 5096, F-66860 Perpignan, France
| | - Julio Sáez-Vásquez
- CNRS, Laboratoire Génome et Développement des Plantes, UMR 5096, 66860 Perpignan, France; Univ. Perpignan Via Domitia, Laboratoire Génome et Développement des Plantes, UMR 5096, F-66860 Perpignan, France.
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14
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Gurard-Levin ZA, Quivy JP, Almouzni G. Histone chaperones: assisting histone traffic and nucleosome dynamics. Annu Rev Biochem 2015; 83:487-517. [PMID: 24905786 DOI: 10.1146/annurev-biochem-060713-035536] [Citation(s) in RCA: 214] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The functional organization of eukaryotic DNA into chromatin uses histones as components of its building block, the nucleosome. Histone chaperones, which are proteins that escort histones throughout their cellular life, are key actors in all facets of histone metabolism; they regulate the supply and dynamics of histones at chromatin for its assembly and disassembly. Histone chaperones can also participate in the distribution of histone variants, thereby defining distinct chromatin landscapes of importance for genome function, stability, and cell identity. Here, we discuss our current knowledge of the known histone chaperones and their histone partners, focusing on histone H3 and its variants. We then place them into an escort network that distributes these histones in various deposition pathways. Through their distinct interfaces, we show how they affect dynamics during DNA replication, DNA damage, and transcription, and how they maintain genome integrity. Finally, we discuss the importance of histone chaperones during development and describe how misregulation of the histone flow can link to disease.
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Affiliation(s)
- Zachary A Gurard-Levin
- Institut Curie, Centre de Recherche; CNRS UMR 3664; Equipe Labellisée, Ligue contre le Cancer; and Université Pierre et Marie Curie, Paris F-75248, France;
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15
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Gaume X, Tassin AM, Ugrinova I, Mongelard F, Monier K, Bouvet P. Centrosomal nucleolin is required for microtubule network organization. Cell Cycle 2015; 14:902-19. [PMID: 25590348 PMCID: PMC4614815 DOI: 10.1080/15384101.2014.1000197] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 12/11/2014] [Accepted: 12/15/2014] [Indexed: 12/22/2022] Open
Abstract
Nucleolin is a pleiotropic protein involved in a variety of cellular processes. Although multipolar spindle formation has been observed after nucleolin depletion, the roles of nucleolin in centrosome regulation and functions have not been addressed. Here we report using immunofluorescence and biochemically purified centrosomes that nucleolin co-localized only with one of the centrioles during interphase which was further identified as the mature centriole. Upon nucleolin depletion, cells exhibited an amplification of immature centriole markers surrounded by irregular pericentrin staining; these structures were exempt from maturation markers and unable to nucleate microtubules. Furthermore, the microtubule network was disorganized in these cells, exhibiting frequent non-centrosomal microtubules. At the mature centriole a reduced kinetics in the centrosomal microtubule nucleation phase was observed in live silenced cells, as well as a perturbation of microtubule anchoring. Immunoprecipitation experiments showed that nucleolin belongs to protein complexes containing 2 key centrosomal proteins, γ-tubulin and ninein, involved in microtubule nucleation and anchoring steps. Altogether, our study uncovered a new role for nucleolin in restricting microtubule nucleation and anchoring at centrosomes in interphase cells.
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Affiliation(s)
- Xavier Gaume
- Université de Lyon; Ecole Normale Supérieure de Lyon; CNRS USR 3010; Laboratoire Joliot-Curie; Lyon, France
| | - Anne-Marie Tassin
- Institute for Integrative Biology of the Cell (I2BC); CEA, CNRS, Université Paris Sud; Gif sur Yvette, France
| | - Iva Ugrinova
- Institute of Molecular Biology “Acad. Roumen Tsanev”; Bulgarian Academy of Sciences; Sofia, Bulgaria
| | - Fabien Mongelard
- Université de Lyon; Ecole Normale Supérieure de Lyon; CNRS USR 3010; Laboratoire Joliot-Curie; Lyon, France
| | - Karine Monier
- Université de Lyon; Ecole Normale Supérieure de Lyon; CNRS USR 3010; Laboratoire Joliot-Curie; Lyon, France
| | - Philippe Bouvet
- Université de Lyon; Ecole Normale Supérieure de Lyon; CNRS USR 3010; Laboratoire Joliot-Curie; Lyon, France
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Shishova KV, Lavrentyeva EA, Dobrucki JW, Zatsepina OV. Nucleolus-like bodies of fully-grown mouse oocytes contain key nucleolar proteins but are impoverished for rRNA. Dev Biol 2014; 397:267-81. [PMID: 25481757 DOI: 10.1016/j.ydbio.2014.11.022] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 11/20/2014] [Accepted: 11/22/2014] [Indexed: 11/26/2022]
Abstract
It is well known that fully-grown mammalian oocytes, rather than typical nucleoli, contain prominent but structurally homogenous bodies called "nucleolus-like bodies" (NLBs). NLBs accumulate a vast amount of material, but their biochemical composition and functions remain uncertain. To clarify the composition of the NLB material in mouse GV oocytes, we devised an assay to detect internal oocyte proteins with fluorescein-5-isothiocyanate (FITC) and applied the fluorescent RNA-binding dye acridine orange to examine whether NLBs contain RNA. Our results unequivocally show that, similarly to typical nucleoli, proteins and RNA are major constituents of transcriptionally active (or non-surrounded) NLBs as well as of transcriptionally silent (or surrounded) NLBs. We also show, by exposing fixed oocytes to a mild proteinase K treatment, that the NLB mass in oocytes of both types contains nucleolar proteins that are involved in all major steps of ribosome biogenesis, including rDNA transcription (UBF), early rRNA processing (fibrillarin), and late rRNA processing (NPM1/nucleophosmin/B23, nucleolin/C23), but none of the nuclear proteins tested, including SC35, NOBOX, topoisomerase II beta, HP1α, and H3. The ribosomal RPL26 protein was detected within the NLBs of NSN-type oocytes but is virtually absent from NLBs of SN-type oocytes. Taking into account that the major class of nucleolar RNA is ribosomal RNA (rRNA), we applied fluorescence in situ hybridization with oligonucleotide probes targeting 18S and 28S rRNAs. The results show that, in contrast to active nucleoli, NLBs of fully-grown oocytes are impoverished for the rRNAs, which is consistent with the absence of transcribed ribosomal genes in the NLB mass. Overall, the results of this study suggest that NLBs of fully-grown mammalian oocytes serve for storing major nucleolar proteins but not rRNA.
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Affiliation(s)
- Kseniya V Shishova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street, 16/10, Moscow 117997, Russian Federation.
| | - Elena A Lavrentyeva
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street, 16/10, Moscow 117997, Russian Federation; Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, GSP-1, Leninskiye Gory, MSU, 1-73, Office, Moscow 119991, Russian Federation.
| | - Jurek W Dobrucki
- Laboratory of Cell Biophysics, Faculty of Biochemistry, Biophysics, and Biotechnology, Jagiellonian University, Gronostajowa Street, 30-387 Krakow, Poland.
| | - Olga V Zatsepina
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street, 16/10, Moscow 117997, Russian Federation.
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17
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Cong R, Das S, Douet J, Wong J, Buschbeck M, Mongelard F, Bouvet P. macroH2A1 histone variant represses rDNA transcription. Nucleic Acids Res 2014; 42:181-92. [PMID: 24071584 PMCID: PMC3874179 DOI: 10.1093/nar/gkt863] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 08/30/2013] [Accepted: 09/04/2013] [Indexed: 01/21/2023] Open
Abstract
The regulation of ribosomal DNA transcription is an important step for the control of cell growth. Epigenetic marks such as DNA methylation and posttranslational modifications of canonical histones have been involved in this regulation, but much less is known about the role of histone variants. In this work, we show that the histone variant macroH2A1 is present on the promoter of methylated rDNA genes. The inhibition of the expression of macroH2A1 in human HeLa and HepG2 cells and in a mouse ES cell line resulted in an up to 5-fold increase of pre-rRNA levels. This increased accumulation of pre-rRNA is accompanied by an increase of the loading of RNA polymerase I and UBF on the rDNA without any changes in the number of active rDNA genes. The inhibition of RNA polymerase I transcription by actinomycin D or by knocking down nucleolin, induces the recruitment of macroH2A1 on the rDNA and the relocalization of macroH2A1 in the nucleolus. Interestingly, the inhibition of rDNA transcription induced by nucleolin depletion is alleviated by the inactivation of macroH2A1. These results demonstrate that macroH2A1 is a new factor involved in the regulation of rDNA transcription.
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Affiliation(s)
- Rong Cong
- Université de Lyon, Ecole Normale Supérieure de Lyon, CNRS USR 3010, Laboratoire Joliot-Curie, 69364 Lyon, France, The Institute of Predictive and Personalized Medicine of Cancer (IMPPC), 08916 Badalona, Barcelona, Spain and The Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Sadhan Das
- Université de Lyon, Ecole Normale Supérieure de Lyon, CNRS USR 3010, Laboratoire Joliot-Curie, 69364 Lyon, France, The Institute of Predictive and Personalized Medicine of Cancer (IMPPC), 08916 Badalona, Barcelona, Spain and The Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Julien Douet
- Université de Lyon, Ecole Normale Supérieure de Lyon, CNRS USR 3010, Laboratoire Joliot-Curie, 69364 Lyon, France, The Institute of Predictive and Personalized Medicine of Cancer (IMPPC), 08916 Badalona, Barcelona, Spain and The Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Jiemin Wong
- Université de Lyon, Ecole Normale Supérieure de Lyon, CNRS USR 3010, Laboratoire Joliot-Curie, 69364 Lyon, France, The Institute of Predictive and Personalized Medicine of Cancer (IMPPC), 08916 Badalona, Barcelona, Spain and The Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Marcus Buschbeck
- Université de Lyon, Ecole Normale Supérieure de Lyon, CNRS USR 3010, Laboratoire Joliot-Curie, 69364 Lyon, France, The Institute of Predictive and Personalized Medicine of Cancer (IMPPC), 08916 Badalona, Barcelona, Spain and The Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Fabien Mongelard
- Université de Lyon, Ecole Normale Supérieure de Lyon, CNRS USR 3010, Laboratoire Joliot-Curie, 69364 Lyon, France, The Institute of Predictive and Personalized Medicine of Cancer (IMPPC), 08916 Badalona, Barcelona, Spain and The Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Philippe Bouvet
- Université de Lyon, Ecole Normale Supérieure de Lyon, CNRS USR 3010, Laboratoire Joliot-Curie, 69364 Lyon, France, The Institute of Predictive and Personalized Medicine of Cancer (IMPPC), 08916 Badalona, Barcelona, Spain and The Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241, China
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Cong R, Das S, Ugrinova I, Kumar S, Mongelard F, Wong J, Bouvet P. Interaction of nucleolin with ribosomal RNA genes and its role in RNA polymerase I transcription. Nucleic Acids Res 2012; 40:9441-54. [PMID: 22859736 PMCID: PMC3479187 DOI: 10.1093/nar/gks720] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 06/04/2012] [Accepted: 07/04/2012] [Indexed: 12/13/2022] Open
Abstract
Nucleolin is a multi-functional nucleolar protein that is required for ribosomal RNA gene (rRNA) transcription in vivo, but the mechanism by which nucleolin modulates RNA polymerase I (RNAPI) transcription is not well understood. Nucleolin depletion results in an increase in the heterochromatin mark H3K9me2 and a decrease in H4K12Ac and H3K4me3 euchromatin histone marks in rRNA genes. ChIP-seq experiments identified an enrichment of nucleolin in the ribosomal DNA (rDNA) coding and promoter region. Nucleolin is preferentially associated with unmethylated rRNA genes and its depletion leads to the accumulation of RNAPI at the beginning of the transcription unit and a decrease in UBF along the coding and promoter regions. Nucleolin is able to affect the binding of transcription termination factor-1 on the promoter-proximal terminator T0, thus inhibiting the recruitment of TIP5 and HDAC1 and the establishment of a repressive heterochromatin state. These results reveal the importance of nucleolin for the maintenance of the euchromatin state and transcription elongation of rDNA.
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Affiliation(s)
- Rong Cong
- Université de Lyon, Ecole Normale Supérieure de Lyon, CNRS USR 3010, Laboratoire Joliot-Curie, 69364 Lyon, France, The Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241, China and BioCOS Life Sciences Private Limited, Biotech Park, Electronics City, Phase-1, Bangalore 560100, India
| | - Sadhan Das
- Université de Lyon, Ecole Normale Supérieure de Lyon, CNRS USR 3010, Laboratoire Joliot-Curie, 69364 Lyon, France, The Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241, China and BioCOS Life Sciences Private Limited, Biotech Park, Electronics City, Phase-1, Bangalore 560100, India
| | - Iva Ugrinova
- Université de Lyon, Ecole Normale Supérieure de Lyon, CNRS USR 3010, Laboratoire Joliot-Curie, 69364 Lyon, France, The Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241, China and BioCOS Life Sciences Private Limited, Biotech Park, Electronics City, Phase-1, Bangalore 560100, India
| | - Sanjeev Kumar
- Université de Lyon, Ecole Normale Supérieure de Lyon, CNRS USR 3010, Laboratoire Joliot-Curie, 69364 Lyon, France, The Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241, China and BioCOS Life Sciences Private Limited, Biotech Park, Electronics City, Phase-1, Bangalore 560100, India
| | - Fabien Mongelard
- Université de Lyon, Ecole Normale Supérieure de Lyon, CNRS USR 3010, Laboratoire Joliot-Curie, 69364 Lyon, France, The Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241, China and BioCOS Life Sciences Private Limited, Biotech Park, Electronics City, Phase-1, Bangalore 560100, India
| | - Jiemin Wong
- Université de Lyon, Ecole Normale Supérieure de Lyon, CNRS USR 3010, Laboratoire Joliot-Curie, 69364 Lyon, France, The Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241, China and BioCOS Life Sciences Private Limited, Biotech Park, Electronics City, Phase-1, Bangalore 560100, India
| | - Philippe Bouvet
- Université de Lyon, Ecole Normale Supérieure de Lyon, CNRS USR 3010, Laboratoire Joliot-Curie, 69364 Lyon, France, The Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241, China and BioCOS Life Sciences Private Limited, Biotech Park, Electronics City, Phase-1, Bangalore 560100, India
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Ratnakumar K, Duarte LF, LeRoy G, Hasson D, Smeets D, Vardabasso C, Bönisch C, Zeng T, Xiang B, Zhang DY, Li H, Wang X, Hake SB, Schermelleh L, Garcia BA, Bernstein E. ATRX-mediated chromatin association of histone variant macroH2A1 regulates α-globin expression. Genes Dev 2012; 26:433-8. [PMID: 22391447 DOI: 10.1101/gad.179416.111] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The histone variant macroH2A generally associates with transcriptionally inert chromatin; however, the factors that regulate its chromatin incorporation remain elusive. Here, we identify the SWI/SNF helicase ATRX (α-thalassemia/MR, X-linked) as a novel macroH2A-interacting protein. Unlike its role in assisting H3.3 chromatin deposition, ATRX acts as a negative regulator of macroH2A's chromatin association. In human erythroleukemic cells deficient for ATRX, macroH2A accumulates at the HBA gene cluster on the subtelomere of chromosome 16, coinciding with the loss of α-globin expression. Collectively, our results implicate deregulation of macroH2A's distribution as a contributing factor to the α-thalassemia phenotype of ATRX syndrome.
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Affiliation(s)
- Kajan Ratnakumar
- Department of Oncological Sciences, Mount Sinai School of Medicine, New York, NY 10029, USA
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Layat E, Sáez-Vásquez J, Tourmente S. Regulation of Pol I-transcribed 45S rDNA and Pol III-transcribed 5S rDNA in Arabidopsis. PLANT & CELL PHYSIOLOGY 2012; 53:267-76. [PMID: 22173098 DOI: 10.1093/pcp/pcr177] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The 18S, 5.8S and 25S rRNAs, which result from the 45S precursor, together with 5S rRNAs, are central components of the ribosome. The integration of one molecule of each rRNA per ribosome necessitates an elaborate coordination between transcriptions of the two ribosomal DNA (rDNA) families. Even though 5S rDNA is transcribed by RNA polymerase III and 45S rDNA by RNA polymerase I, the two rDNA families present certain similarities in their transcriptional regulation. This review aims to compare 5S and 45S rRNA genes in the plant model Arabidopsis thaliana in terms of organization, transcription and regulation, and draws parallels between the two rDNA families.
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Affiliation(s)
- Elodie Layat
- CNRS, UMR 6247 GReD, Clermont Université, INSERM U931, Aubière, France
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Pasque V, Gillich A, Garrett N, Gurdon JB. Histone variant macroH2A confers resistance to nuclear reprogramming. EMBO J 2011; 30:2373-87. [PMID: 21552206 PMCID: PMC3116279 DOI: 10.1038/emboj.2011.144] [Citation(s) in RCA: 121] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 04/13/2011] [Indexed: 01/31/2023] Open
Abstract
Gurdon and collaborators report reversible X chromosome inactivation in epiblast stem cells (EpiSCs) that seems to be determined by macroH2A1 deposition. These findings are of rather general interest as they highlight the epigenetic state of repressed loci as determinant for reprogramming efficiency. How various layers of epigenetic repression restrict somatic cell nuclear reprogramming is poorly understood. The transfer of mammalian somatic cell nuclei into Xenopus oocytes induces transcriptional reprogramming of previously repressed genes. Here, we address the mechanisms that restrict reprogramming following nuclear transfer by assessing the stability of the inactive X chromosome (Xi) in different stages of inactivation. We find that the Xi of mouse post-implantation-derived epiblast stem cells (EpiSCs) can be reversed by nuclear transfer, while the Xi of differentiated or extraembryonic cells is irreversible by nuclear transfer to oocytes. After nuclear transfer, Xist RNA is lost from chromatin of the Xi. Most epigenetic marks such as DNA methylation and Polycomb-deposited H3K27me3 do not explain the differences between reversible and irreversible Xi. Resistance to reprogramming is associated with incorporation of the histone variant macroH2A, which is retained on the Xi of differentiated cells, but absent from the Xi of EpiSCs. Our results uncover the decreased stability of the Xi in EpiSCs, and highlight the importance of combinatorial epigenetic repression involving macroH2A in restricting transcriptional reprogramming by oocytes.
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Affiliation(s)
- Vincent Pasque
- Wellcome Trust Cancer Research UK Gurdon Institute, Cambridge, UK.
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