1
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Deng X, Yao Q, Horvath A, Jiang Z, Zhao J, Fischer T, Sugiyama T. The fission yeast ortholog of Coilin, Mug174, forms Cajal body-like nuclear condensates and is essential for cellular quiescence. Nucleic Acids Res 2024; 52:9174-9192. [PMID: 38828770 DOI: 10.1093/nar/gkae463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 05/08/2024] [Accepted: 05/16/2024] [Indexed: 06/05/2024] Open
Abstract
The Cajal body, a nuclear condensate, is crucial for ribonucleoprotein assembly, including small nuclear RNPs (snRNPs). While Coilin has been identified as an integral component of Cajal bodies, its exact function remains unclear. Moreover, no Coilin ortholog has been found in unicellular organisms to date. This study unveils Mug174 (Meiosis-upregulated gene 174) as the Coilin ortholog in the fission yeast Schizosaccharomyces pombe. Mug174 forms phase-separated condensates in vitro and is often associated with the nucleolus and the cleavage body in vivo. The generation of Mug174 foci relies on the trimethylguanosine (TMG) synthase Tgs1. Moreover, Mug174 interacts with Tgs1 and U snRNAs. Deletion of the mug174+ gene in S. pombe causes diverse pleiotropic phenotypes, encompassing defects in vegetative growth, meiosis, pre-mRNA splicing, TMG capping of U snRNAs, and chromosome segregation. In addition, we identified weak homology between Mug174 and human Coilin. Notably, human Coilin expressed in fission yeast colocalizes with Mug174. Critically, Mug174 is indispensable for the maintenance of and transition from cellular quiescence. These findings highlight the Coilin ortholog in fission yeast and suggest that the Cajal body is implicated in cellular quiescence, thereby preventing human diseases.
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Affiliation(s)
- Xiaoling Deng
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Qinglian Yao
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Attila Horvath
- The John Curtin School of Medical Research, The Australian National University, Canberra 2601, Australia
| | - Ziling Jiang
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Junjie Zhao
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Tamás Fischer
- The John Curtin School of Medical Research, The Australian National University, Canberra 2601, Australia
| | - Tomoyasu Sugiyama
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
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2
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Cascio P. PA28γ, the ring that makes tumors invisible to the immune system? Biochimie 2024:S0300-9084(24)00078-6. [PMID: 38631454 DOI: 10.1016/j.biochi.2024.04.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 03/29/2024] [Accepted: 04/12/2024] [Indexed: 04/19/2024]
Abstract
PA28γ is a proteasomal interactor whose main and most known function is to stimulate the hydrolytic activity of the 20 S proteasome independently of ubiquitin and ATP. Unlike its two paralogues, PA28α and PA28β, PA28γ is largely present in the nuclear compartment and plays pivotal functions in important pathways such as cellular division, apoptosis, neoplastic transformation, chromatin structure and organization, fertility, lipid metabolism, and DNA repair mechanisms. Although it is known that a substantial fraction of PA28γ is found in the cell in a free form (i.e. not associated with 20 S), almost all of the studies so far have focused on its ability to modulate proteasomal enzymatic activities. In this respect, the ability of PA28γ to strongly stimulate degradation of proteins, especially if intrinsically disordered and therefore devoid of three-dimensional tightly folded structure, appears to be the main molecular mechanism underlying its multiple biological effects. Initial studies, conducted more than 20 years ago, came to the conclusion that among the many biological functions of PA28γ, the immunological ones were rather limited and circumscribed. In this review, we focus on recent evidence showing that PA28γ fulfills significant functions in cell-mediated acquired immunity, with a particular role in attenuating MHC class I antigen presentation, especially in relation to neoplastic transformation and autoimmune diseases.
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Affiliation(s)
- Paolo Cascio
- Department of Veterinary Sciences, University of Turin, Largo P. Braccini 2, 10095, Grugliasco, Turin, Italy.
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3
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Lettin L, Erbay B, Blair GE. Viruses and Cajal Bodies: A Critical Cellular Target in Virus Infection? Viruses 2023; 15:2311. [PMID: 38140552 PMCID: PMC10747631 DOI: 10.3390/v15122311] [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: 10/12/2023] [Revised: 11/22/2023] [Accepted: 11/23/2023] [Indexed: 12/24/2023] Open
Abstract
Nuclear bodies (NBs) are dynamic structures present in eukaryotic cell nuclei. They are not bounded by membranes and are often considered biomolecular condensates, defined structurally and functionally by the localisation of core components. Nuclear architecture can be reorganised during normal cellular processes such as the cell cycle as well as in response to cellular stress. Many plant and animal viruses target their proteins to NBs, in some cases triggering their structural disruption and redistribution. Although not all such interactions have been well characterised, subversion of NBs and their functions may form a key part of the life cycle of eukaryotic viruses that require the nucleus for their replication. This review will focus on Cajal bodies (CBs) and the viruses that target them. Since CBs are dynamic structures, other NBs (principally nucleoli and promyelocytic leukaemia, PML and bodies), whose components interact with CBs, will also be considered. As well as providing important insights into key virus-host cell interactions, studies on Cajal and associated NBs may identify novel cellular targets for development of antiviral compounds.
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Affiliation(s)
- Lucy Lettin
- School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, UK (B.E.)
| | - Bilgi Erbay
- School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, UK (B.E.)
- Moleküler Biyoloji ve Genetik Bölümü, Fen Fakültesi, Van Yuzuncu Yil University, Van 65140, Türkiye
| | - G. Eric Blair
- School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, UK (B.E.)
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4
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Musawi S, Donnio LM, Zhao Z, Magnani C, Rassinoux P, Binda O, Huang J, Jacquier A, Coudert L, Lomonte P, Martinat C, Schaeffer L, Mottet D, Côté J, Mari PO, Giglia-Mari G. Nucleolar reorganization after cellular stress is orchestrated by SMN shuttling between nuclear compartments. Nat Commun 2023; 14:7384. [PMID: 37968267 PMCID: PMC10652021 DOI: 10.1038/s41467-023-42390-4] [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: 10/13/2022] [Accepted: 10/10/2023] [Indexed: 11/17/2023] Open
Abstract
Spinal muscular atrophy is an autosomal recessive neuromuscular disease caused by mutations in the multifunctional protein Survival of Motor Neuron, or SMN. Within the nucleus, SMN localizes to Cajal bodies, which are associated with nucleoli, nuclear organelles dedicated to the first steps of ribosome biogenesis. The highly organized structure of the nucleolus can be dynamically altered by genotoxic agents. RNAP1, Fibrillarin, and nucleolar DNA are exported to the periphery of the nucleolus after genotoxic stress and, once DNA repair is fully completed, the organization of the nucleolus is restored. We find that SMN is required for the restoration of the nucleolar structure after genotoxic stress. During DNA repair, SMN shuttles from the Cajal bodies to the nucleolus. This shuttling is important for nucleolar homeostasis and relies on the presence of Coilin and the activity of PRMT1.
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Affiliation(s)
- Shaqraa Musawi
- Pathophysiology and Genetics of Neuron and Muscle (INMG-PGNM), CNRS UMR 5261, INSERM U1315, Université Claude Bernard Lyon 1, 68008, Lyon, France
- Department of Medical Laboratories Technology, College of Applied Medical Sciences, Jazan University, Jazan, Saudi Arabia
| | - Lise-Marie Donnio
- Pathophysiology and Genetics of Neuron and Muscle (INMG-PGNM), CNRS UMR 5261, INSERM U1315, Université Claude Bernard Lyon 1, 68008, Lyon, France.
| | - Zehui Zhao
- Pathophysiology and Genetics of Neuron and Muscle (INMG-PGNM), CNRS UMR 5261, INSERM U1315, Université Claude Bernard Lyon 1, 68008, Lyon, France
| | - Charlène Magnani
- Pathophysiology and Genetics of Neuron and Muscle (INMG-PGNM), CNRS UMR 5261, INSERM U1315, Université Claude Bernard Lyon 1, 68008, Lyon, France
| | - Phoebe Rassinoux
- Pathophysiology and Genetics of Neuron and Muscle (INMG-PGNM), CNRS UMR 5261, INSERM U1315, Université Claude Bernard Lyon 1, 68008, Lyon, France
| | - Olivier Binda
- Pathophysiology and Genetics of Neuron and Muscle (INMG-PGNM), CNRS UMR 5261, INSERM U1315, Université Claude Bernard Lyon 1, 68008, Lyon, France
- Faculty of Medicine, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, K1H 8M5, Ontario, Canada
| | - Jianbo Huang
- Pathophysiology and Genetics of Neuron and Muscle (INMG-PGNM), CNRS UMR 5261, INSERM U1315, Université Claude Bernard Lyon 1, 68008, Lyon, France
| | - Arnaud Jacquier
- Pathophysiology and Genetics of Neuron and Muscle (INMG-PGNM), CNRS UMR 5261, INSERM U1315, Université Claude Bernard Lyon 1, 68008, Lyon, France
| | - Laurent Coudert
- Pathophysiology and Genetics of Neuron and Muscle (INMG-PGNM), CNRS UMR 5261, INSERM U1315, Université Claude Bernard Lyon 1, 68008, Lyon, France
| | - Patrick Lomonte
- Pathophysiology and Genetics of Neuron and Muscle (INMG-PGNM), CNRS UMR 5261, INSERM U1315, Université Claude Bernard Lyon 1, 68008, Lyon, France
| | - Cécile Martinat
- INSERM/UEPS UMR 861, Paris Saclay Université, I-STEM, 91100, Corbeil-Essonnes, France
| | - Laurent Schaeffer
- Pathophysiology and Genetics of Neuron and Muscle (INMG-PGNM), CNRS UMR 5261, INSERM U1315, Université Claude Bernard Lyon 1, 68008, Lyon, France
| | - Denis Mottet
- GIGA-Molecular Biology of Diseases, Gene Expression and Cancer Laboratory, B34 + 1, University of Liege, Avenue de l'Hôpital 1, B-4000, Liège, Belgium
| | - Jocelyn Côté
- Faculty of Medicine, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, K1H 8M5, Ontario, Canada
| | - Pierre-Olivier Mari
- Pathophysiology and Genetics of Neuron and Muscle (INMG-PGNM), CNRS UMR 5261, INSERM U1315, Université Claude Bernard Lyon 1, 68008, Lyon, France
| | - Giuseppina Giglia-Mari
- Pathophysiology and Genetics of Neuron and Muscle (INMG-PGNM), CNRS UMR 5261, INSERM U1315, Université Claude Bernard Lyon 1, 68008, Lyon, France.
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5
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Watson JL, Seinkmane E, Styles CT, Mihut A, Krüger LK, McNally KE, Planelles-Herrero VJ, Dudek M, McCall PM, Barbiero S, Vanden Oever M, Peak-Chew SY, Porebski BT, Zeng A, Rzechorzek NM, Wong DCS, Beale AD, Stangherlin A, Riggi M, Iwasa J, Morf J, Miliotis C, Guna A, Inglis AJ, Brugués J, Voorhees RM, Chambers JE, Meng QJ, O'Neill JS, Edgar RS, Derivery E. Macromolecular condensation buffers intracellular water potential. Nature 2023; 623:842-852. [PMID: 37853127 PMCID: PMC10665201 DOI: 10.1038/s41586-023-06626-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 09/08/2023] [Indexed: 10/20/2023]
Abstract
Optimum protein function and biochemical activity critically depends on water availability because solvent thermodynamics drive protein folding and macromolecular interactions1. Reciprocally, macromolecules restrict the movement of 'structured' water molecules within their hydration layers, reducing the available 'free' bulk solvent and therefore the total thermodynamic potential energy of water, or water potential. Here, within concentrated macromolecular solutions such as the cytosol, we found that modest changes in temperature greatly affect the water potential, and are counteracted by opposing changes in osmotic strength. This duality of temperature and osmotic strength enables simple manipulations of solvent thermodynamics to prevent cell death after extreme cold or heat shock. Physiologically, cells must sustain their activity against fluctuating temperature, pressure and osmotic strength, which impact water availability within seconds. Yet, established mechanisms of water homeostasis act over much slower timescales2,3; we therefore postulated the existence of a rapid compensatory response. We find that this function is performed by water potential-driven changes in macromolecular assembly, particularly biomolecular condensation of intrinsically disordered proteins. The formation and dissolution of biomolecular condensates liberates and captures free water, respectively, quickly counteracting thermal or osmotic perturbations of water potential, which is consequently robustly buffered in the cytoplasm. Our results indicate that biomolecular condensation constitutes an intrinsic biophysical feedback response that rapidly compensates for intracellular osmotic and thermal fluctuations. We suggest that preserving water availability within the concentrated cytosol is an overlooked evolutionary driver of protein (dis)order and function.
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Affiliation(s)
| | | | | | - Andrei Mihut
- MRC Laboratory of Molecular Biology, Cambridge, UK
| | | | | | | | - Michal Dudek
- Wellcome Centre for Cell Matrix Research, University of Manchester, Manchester, UK
| | - Patrick M McCall
- Cluster of Excellence Physics of Life, TU Dresden, Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
- Max Planck Institute for the Physics of Complex Systems, Dresden, Germany
| | | | | | | | | | - Aiwei Zeng
- MRC Laboratory of Molecular Biology, Cambridge, UK
| | | | | | | | - Alessandra Stangherlin
- MRC Laboratory of Molecular Biology, Cambridge, UK
- Cluster of Excellence Cellular Stress Responses in Aging-associated Diseases (CECAD), Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Margot Riggi
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Janet Iwasa
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Jörg Morf
- Laboratory of Nuclear Dynamics, Babraham Institute, Cambridge, UK
| | | | - Alina Guna
- California Institute of Technology, Pasadena, CA, USA
| | | | - Jan Brugués
- Cluster of Excellence Physics of Life, TU Dresden, Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
- Max Planck Institute for the Physics of Complex Systems, Dresden, Germany
| | | | | | - Qing-Jun Meng
- Wellcome Centre for Cell Matrix Research, University of Manchester, Manchester, UK
| | | | - Rachel S Edgar
- Department of Infectious Disease, Imperial College London, London, UK.
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6
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Taliansky ME, Love AJ, Kołowerzo-Lubnau A, Smoliński DJ. Cajal bodies: Evolutionarily conserved nuclear biomolecular condensates with properties unique to plants. THE PLANT CELL 2023; 35:3214-3235. [PMID: 37202374 PMCID: PMC10473218 DOI: 10.1093/plcell/koad140] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 04/24/2023] [Accepted: 04/27/2023] [Indexed: 05/20/2023]
Abstract
Proper orchestration of the thousands of biochemical processes that are essential to the life of every cell requires highly organized cellular compartmentalization of dedicated microenvironments. There are 2 ways to create this intracellular segregation to optimize cellular function. One way is to create specific organelles, enclosed spaces bounded by lipid membranes that regulate macromolecular flux in and out of the compartment. A second way is via membraneless biomolecular condensates that form due to to liquid-liquid phase separation. Although research on these membraneless condensates has historically been performed using animal and fungal systems, recent studies have explored basic principles governing the assembly, properties, and functions of membraneless compartments in plants. In this review, we discuss how phase separation is involved in a variety of key processes occurring in Cajal bodies (CBs), a type of biomolecular condensate found in nuclei. These processes include RNA metabolism, formation of ribonucleoproteins involved in transcription, RNA splicing, ribosome biogenesis, and telomere maintenance. Besides these primary roles of CBs, we discuss unique plant-specific functions of CBs in RNA-based regulatory pathways such as nonsense-mediated mRNA decay, mRNA retention, and RNA silencing. Finally, we summarize recent progress and discuss the functions of CBs in responses to pathogen attacks and abiotic stresses, responses that may be regulated via mechanisms governed by polyADP-ribosylation. Thus, plant CBs are emerging as highly complex and multifunctional biomolecular condensates that are involved in a surprisingly diverse range of molecular mechanisms that we are just beginning to appreciate.
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Affiliation(s)
| | - Andrew J Love
- The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK
| | - Agnieszka Kołowerzo-Lubnau
- Department of Cellular and Molecular Biology, Nicolaus Copernicus University, Lwowska 1, 87-100 Torun, Poland
- Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University, Wilenska 4, 87-100 Torun, Poland
| | - Dariusz Jan Smoliński
- Department of Cellular and Molecular Biology, Nicolaus Copernicus University, Lwowska 1, 87-100 Torun, Poland
- Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University, Wilenska 4, 87-100 Torun, Poland
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7
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Feng Y, Zhang H, Han J, Cui B, Qin L, Zhang L, Li Q, Wu X, Xiao N, Zhang Y, Lin T, Liu H, Sun T. HSF4/COIL complex-dependent R-loop mediates ultraviolet-induced inflammatory skin injury. Clin Transl Med 2023; 13:e1336. [PMID: 37461263 PMCID: PMC10352565 DOI: 10.1002/ctm2.1336] [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: 12/15/2022] [Revised: 07/05/2023] [Accepted: 07/11/2023] [Indexed: 07/20/2023] Open
Abstract
Intense ultraviolet (UV) exposure can cause phototoxic reactions, such as skin inflammation, resulting in injury. UV is a direct cause of DNA damage, but the mechanisms underlying transcriptional regulation within cells after DNA damage are unclear. The bioinformatics analysis of transcriptome sequencing data from UV-irradiated and non-UV-irradiated skin showed that transcription-related proteins, such as HSF4 and COIL, mediate cellular response to UV irradiation. HSF4 and COIL can form a complex under UV irradiation, and the preference for binding target genes changed because of the presence of a large number of R-loops in cells under UV irradiation and the ability of COIL to recognize R-loops. The regulation of target genes was altered by the HSF4-COIL complex, and the expression of inflammation and ageing-related genes, such as Atg7, Tfpi, and Lims1, was enhanced. A drug screen was performed for the recognition sites of COIL and R-loop. N6-(2-hydroxyethyl)-adenosine can competitively bind COIL and inhibit the binding of COIL to the R-loop. Thus, the activation of downstream inflammation-related genes and inflammatory skin injury was inhibited.
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Affiliation(s)
- Yi‐qian Feng
- State Key Laboratory of Medicinal Chemical Biology and College of PharmacyNankai UniversityTianjinChina
| | - Heng Zhang
- State Key Laboratory of Medicinal Chemical Biology and College of PharmacyNankai UniversityTianjinChina
- Tianjin Key Laboratory of Early Druggability Evaluation of Innovative Drugs and Tianjin Key Laboratory of Molecular Drug ResearchTianjin International Joint Academy of BiomedicineTianjinChina
| | - Jing‐xia Han
- State Key Laboratory of Medicinal Chemical Biology and College of PharmacyNankai UniversityTianjinChina
- Tianjin Key Laboratory of Early Druggability Evaluation of Innovative Drugs and Tianjin Key Laboratory of Molecular Drug ResearchTianjin International Joint Academy of BiomedicineTianjinChina
| | - Bi‐jia Cui
- State Key Laboratory of Medicinal Chemical Biology and College of PharmacyNankai UniversityTianjinChina
| | - Lu‐ning Qin
- State Key Laboratory of Medicinal Chemical Biology and College of PharmacyNankai UniversityTianjinChina
| | - Lei Zhang
- State Key Laboratory of Medicinal Chemical Biology and College of PharmacyNankai UniversityTianjinChina
| | - Qing‐qing Li
- State Key Laboratory of Medicinal Chemical Biology and College of PharmacyNankai UniversityTianjinChina
| | - Xin‐ying Wu
- State Key Laboratory of Medicinal Chemical Biology and College of PharmacyNankai UniversityTianjinChina
| | - Nan‐nan Xiao
- State Key Laboratory of Medicinal Chemical Biology and College of PharmacyNankai UniversityTianjinChina
| | - Yan Zhang
- State Key Laboratory of Medicinal Chemical Biology and College of PharmacyNankai UniversityTianjinChina
| | - Ting‐ting Lin
- Medical Plastic and Cosmetic CentreTianjin Branch of National Clinical Research Center for Ocular DiseaseTianjin Medical University Eye HospitalTianjinChina
| | - Hui‐juan Liu
- State Key Laboratory of Medicinal Chemical Biology and College of PharmacyNankai UniversityTianjinChina
- Tianjin Key Laboratory of Early Druggability Evaluation of Innovative Drugs and Tianjin Key Laboratory of Molecular Drug ResearchTianjin International Joint Academy of BiomedicineTianjinChina
| | - Tao Sun
- State Key Laboratory of Medicinal Chemical Biology and College of PharmacyNankai UniversityTianjinChina
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8
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Jin X, Tanaka H, Jin M, Fujita K, Homma H, Inotsume M, Yong H, Umeda K, Kodera N, Ando T, Okazawa H. PQBP5/NOL10 maintains and anchors the nucleolus under physiological and osmotic stress conditions. Nat Commun 2023; 14:9. [PMID: 36599853 PMCID: PMC9813255 DOI: 10.1038/s41467-022-35602-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 12/13/2022] [Indexed: 01/06/2023] Open
Abstract
Polyglutamine binding protein 5 (PQBP5), also called nucleolar protein 10 (NOL10), binds to polyglutamine tract sequences and is expressed in the nucleolus. Using dynamic imaging of high-speed atomic force microscopy, we show that PQBP5/NOL10 is an intrinsically disordered protein. Super-resolution microscopy and correlative light and electron microscopy method show that PQBP5/NOL10 makes up the skeletal structure of the nucleolus, constituting the granule meshwork in the granular component area, which is distinct from other nucleolar substructures, such as the fibrillar center and dense fibrillar component. In contrast to other nucleolar proteins, which disperse to the nucleoplasm under osmotic stress conditions, PQBP5/NOL10 remains in the nucleolus and functions as an anchor for reassembly of other nucleolar proteins. Droplet and thermal shift assays show that the biophysical features of PQBP5/NOL10 remain stable under stress conditions, explaining the spatial role of this protein. PQBP5/NOL10 can be functionally depleted by sequestration with polyglutamine disease proteins in vitro and in vivo, leading to the pathological deformity or disappearance of the nucleolus. Taken together, these findings indicate that PQBP5/NOL10 is an essential protein needed to maintain the structure of the nucleolus.
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Affiliation(s)
- Xiaocen Jin
- Department of Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Hikari Tanaka
- Department of Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Meihua Jin
- Department of Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Kyota Fujita
- Department of Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Hidenori Homma
- Department of Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Maiko Inotsume
- Department of Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Huang Yong
- Department of Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Kenichi Umeda
- Nano Life Science Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan
| | - Noriyuki Kodera
- Nano Life Science Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan
| | - Toshio Ando
- Nano Life Science Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan
| | - Hitoshi Okazawa
- Department of Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.
- Center for Brain Integration Research, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.
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9
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Batnasan E, Koivukoski S, Kärkkäinen M, Latonen L. Nuclear Organization in Response to Stress: A Special Focus on Nucleoli. Results Probl Cell Differ 2022; 70:469-494. [PMID: 36348119 DOI: 10.1007/978-3-031-06573-6_17] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
In this chapter, we discuss the nuclear organization and how it responds to different types of stress. A key component in these responses is molecular traffic between the different sub-nucleolar compartments, such as nucleoplasm, chromatin, nucleoli, and various speckle and body compartments. This allows specific repair and response activities in locations where they normally are not active and serve to halt sensitive functions until the stress insult passes and inflicted damage has been repaired. We focus on mammalian cells and their nuclear organization, especially describing the central role of the nucleolus in nuclear stress responses. We describe events after multiple stress types, including DNA damage, various drugs, and toxic compounds, and discuss the involvement of macromolecular traffic between dynamic, phase-separated nuclear organelles and foci. We delineate the key proteins and non-coding RNA in the formation of stress-responsive, non-membranous nuclear organelles, many of which are relevant to the formation of and utilization in cancer treatment.
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Affiliation(s)
- Enkhzaya Batnasan
- Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland
| | - Sonja Koivukoski
- Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland
| | - Minttu Kärkkäinen
- Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland
| | - Leena Latonen
- Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland.
- Foundation for the Finnish Cancer Institute, Helsinki, Finland.
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10
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Frayssinhes JYA, Cerruti F, Laulin J, Cattaneo A, Bachi A, Apcher S, Coux O, Cascio P. PA28γ-20S proteasome is a proteolytic complex committed to degrade unfolded proteins. Cell Mol Life Sci 2021; 79:45. [PMID: 34913092 PMCID: PMC11071804 DOI: 10.1007/s00018-021-04045-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 11/15/2021] [Accepted: 11/17/2021] [Indexed: 02/07/2023]
Abstract
PA28γ is a nuclear activator of the 20S proteasome that, unlike the 19S regulatory particle, stimulates hydrolysis of several substrates in an ATP- and ubiquitin-independent manner and whose exact biological functions and molecular mechanism of action still remain elusive. In an effort to shed light on these important issues, we investigated the stimulatory effect of PA28γ on the hydrolysis of different fluorogenic peptides and folded or denatured full-length proteins by the 20S proteasome. Importantly, PA28γ was found to dramatically enhance breakdown rates by 20S proteasomes of several naturally or artificially unstructured proteins, but not of their native, folded counterparts. Furthermore, these data were corroborated by experiments in cell lines with a nucleus-tagged myelin basic protein. Finally, mass spectrometry analysis of the products generated during proteasomal degradation of two proteins demonstrated that PA28γ does not increase, but rather decreases, the variability of peptides that are potentially suitable for MHC class I antigen presentation. These unexpected findings indicate that global stimulation of the degradation of unfolded proteins may represent a more general feature of PA28γ and suggests that this proteasomal activator might play a broader role in the pathway of protein degradation than previously believed.
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Affiliation(s)
| | - Fulvia Cerruti
- Department of Veterinary Sciences, University of Turin, Largo P. Braccini 2, 10095, Grugliasco, Turin, Italy
| | - Justine Laulin
- Université Paris-Saclay, Institut Gustave Roussy, Inserm, Immunologie Des Tumeurs et Immunothérapie, Villejuif, France
| | | | - Angela Bachi
- The FIRC Institute of Molecular Oncology (IFOM), 20139, Milan, Italy
| | - Sebastien Apcher
- Université Paris-Saclay, Institut Gustave Roussy, Inserm, Immunologie Des Tumeurs et Immunothérapie, Villejuif, France
| | - Olivier Coux
- Centre de Recherche de Biologie Cellulaire de Montpellier (CRBM), CNRS UMR 5237, Université de Montpellier, 1919 Route de Mende, 34293, Montpellier, France
| | - Paolo Cascio
- Department of Veterinary Sciences, University of Turin, Largo P. Braccini 2, 10095, Grugliasco, Turin, Italy.
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11
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Speckles and paraspeckles coordinate to regulate HSV-1 genes transcription. Commun Biol 2021; 4:1207. [PMID: 34675360 PMCID: PMC8531360 DOI: 10.1038/s42003-021-02742-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 10/04/2021] [Indexed: 12/14/2022] Open
Abstract
Numbers of nuclear speckles and paraspeckles components have been demonstrated to regulate herpes simplex virus 1 (HSV-1) replication. However, how HSV-1 infection affects the two nuclear bodies, and whether this influence facilitates the expression of viral genes, remains elusive. In the current study, we found that HSV-1 infection leads to a redistribution of speckles and paraspeckles components. Serine/arginine-rich splicing factor 2 (SRSF2), the core component of speckles, was associated with multiple paraspeckles components, including nuclear paraspeckles assembly transcript 1 (NEAT1), PSPC1, and P54nrb, in HSV-1 infected cells. This association coordinates the transcription of viral genes by binding to the promoters of these genes. By association with the enhancer of zeste homolog 2 (EZH2) and P300/CBP complex, NEAT1 and SRSF2 influenced the histone modifications located near viral genes. This study elucidates the interplay between speckles and paraspeckles following HSV-1 infection and provides insight into the mechanisms by which HSV-1 utilizes host cellular nuclear bodies to facilitate its life cycle. Li & Wang report that components of nuclear speckles and paraspeckles are redistributed upon HSV-1 infection. They show that the association of Serine/arginine-rich splicing factor 2 (SRSF2) with nuclear paraspeckles assembly transcript 1 (NEAT1) coordinates the transcription of viral genes
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12
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Pecori F, Kondo N, Ogura C, Miura T, Kume M, Minamijima Y, Yamamoto K, Nishihara S. Site-specific O-GlcNAcylation of Psme3 maintains mouse stem cell pluripotency by impairing P-body homeostasis. Cell Rep 2021; 36:109361. [PMID: 34260942 DOI: 10.1016/j.celrep.2021.109361] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 04/09/2021] [Accepted: 06/17/2021] [Indexed: 12/14/2022] Open
Abstract
Mouse embryonic stem cell (ESC) pluripotency is tightly regulated by a complex network composed of extrinsic and intrinsic factors that allow proper organismal development. O-linked β-N-acetylglucosamine (O-GlcNAc) is the sole glycosylation mark found on cytoplasmic and nuclear proteins and plays a pivotal role in regulating fundamental cellular processes; however, its function in ESC pluripotency is still largely unexplored. Here, we identify O-GlcNAcylation of proteasome activator subunit 3 (Psme3) protein as a node of the ESC pluripotency network. Mechanistically, O-GlcNAc modification of serine 111 (S111) of Psme3 promotes degradation of Ddx6, which is essential for processing body (P-body) assembly, resulting in the maintenance of ESC pluripotent state. Conversely, loss of Psme3 S111 O-GlcNAcylation stabilizes Ddx6 and increases P-body levels, culminating in spontaneous exit of ESC from the pluripotent state. Our findings establish O-GlcNAcylation at S111 of Psme3 as a switch that regulates ESC pluripotency via control of P-body homeostasis.
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Affiliation(s)
- Federico Pecori
- Laboratory of Cell Biology, Department of Bioinformatics, Graduate School of Engineering, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, Japan
| | - Nanako Kondo
- Laboratory of Cell Biology, Department of Science and Engineering for Sustainable Innovation, Faculty of Science and Engineering, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, Japan
| | - Chika Ogura
- Laboratory of Cell Biology, Department of Bioinformatics, Graduate School of Engineering, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, Japan
| | - Taichi Miura
- Laboratory of Cell Biology, Department of Bioinformatics, Graduate School of Engineering, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, Japan
| | - Masahiko Kume
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan
| | - Youhei Minamijima
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan
| | - Kazuo Yamamoto
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan
| | - Shoko Nishihara
- Laboratory of Cell Biology, Department of Bioinformatics, Graduate School of Engineering, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, Japan; Laboratory of Cell Biology, Department of Science and Engineering for Sustainable Innovation, Faculty of Science and Engineering, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, Japan; Glycan & Life System Integration Center (GaLSIC), Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, Japan.
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Cascio P. PA28γ: New Insights on an Ancient Proteasome Activator. Biomolecules 2021; 11:228. [PMID: 33562807 PMCID: PMC7915322 DOI: 10.3390/biom11020228] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2021] [Revised: 02/02/2021] [Accepted: 02/03/2021] [Indexed: 02/06/2023] Open
Abstract
PA28 (also known as 11S, REG or PSME) is a family of proteasome regulators whose members are widely present in many of the eukaryotic supergroups. In jawed vertebrates they are represented by three paralogs, PA28α, PA28β, and PA28γ, which assemble as heptameric hetero (PA28αβ) or homo (PA28γ) rings on one or both extremities of the 20S proteasome cylindrical structure. While they share high sequence and structural similarities, the three isoforms significantly differ in terms of their biochemical and biological properties. In fact, PA28α and PA28β seem to have appeared more recently and to have evolved very rapidly to perform new functions that are specifically aimed at optimizing the process of MHC class I antigen presentation. In line with this, PA28αβ favors release of peptide products by proteasomes and is particularly suited to support adaptive immune responses without, however, affecting hydrolysis rates of protein substrates. On the contrary, PA28γ seems to be a slow-evolving gene that is most similar to the common ancestor of the PA28 activators family, and very likely retains its original functions. Notably, PA28γ has a prevalent nuclear localization and is involved in the regulation of several essential cellular processes including cell growth and proliferation, apoptosis, chromatin structure and organization, and response to DNA damage. In striking contrast with the activity of PA28αβ, most of these diverse biological functions of PA28γ seem to depend on its ability to markedly enhance degradation rates of regulatory protein by 20S proteasome. The present review will focus on the molecular mechanisms and biochemical properties of PA28γ, which are likely to account for its various and complex biological functions and highlight the common features with the PA28αβ paralog.
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Affiliation(s)
- Paolo Cascio
- Department of Veterinary Sciences, University of Turin, Largo P. Braccini 2, 10095 Grugliasco, Italy
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Fesquet D, Llères D, Grimaud C, Viganò C, Méchali F, Boulon S, Coux O, Bonne-Andrea C, Baldin V. The 20S proteasome activator PA28γ controls the compaction of chromatin. J Cell Sci 2021; 134:134/3/jcs257717. [PMID: 33526472 DOI: 10.1242/jcs.257717] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 12/03/2020] [Indexed: 12/16/2022] Open
Abstract
PA28γ (also known as PSME3), a nuclear activator of the 20S proteasome, is involved in the degradation of several proteins regulating cell growth and proliferation and in the dynamics of various nuclear bodies, but its precise cellular functions remain unclear. Here, using a quantitative FLIM-FRET based microscopy assay monitoring close proximity between nucleosomes in living human cells, we show that PA28γ controls chromatin compaction. We find that its depletion induces a decompaction of pericentromeric heterochromatin, which is similar to what is observed upon the knockdown of HP1β (also known as CBX1), a key factor of the heterochromatin structure. We show that PA28γ is present at HP1β-containing repetitive DNA sequences abundant in heterochromatin and, importantly, that HP1β on its own is unable to drive chromatin compaction without the presence of PA28γ. At the molecular level, we show that this novel function of PA28γ is independent of its stable interaction with the 20S proteasome, and most likely depends on its ability to maintain appropriate levels of H3K9me3 and H4K20me3, histone modifications that are involved in heterochromatin formation. Overall, our results implicate PA28γ as a key factor involved in the regulation of the higher order structure of chromatin.
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Affiliation(s)
- Didier Fesquet
- Centre de Recherche de Biologie cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, 34293 Montpellier, France
| | - David Llères
- Institut de Génétique Moléculaire de Montpellier (IGMM), Université de Montpellier, CNRS, 34293 Montpellier, France
| | - Charlotte Grimaud
- Institut de Recherche en Cancérologie de Montpellier (IRCM), INSERM U1194, Institut Régional du Cancer (ICM), Université de Montpellier, CNRS Route de Mende, 34293 Montpellier, France
| | - Cristina Viganò
- Centre de Recherche de Biologie cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, 34293 Montpellier, France
| | - Francisca Méchali
- Centre de Recherche de Biologie cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, 34293 Montpellier, France
| | - Séverine Boulon
- Centre de Recherche de Biologie cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, 34293 Montpellier, France
| | - Olivier Coux
- Centre de Recherche de Biologie cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, 34293 Montpellier, France
| | - Catherine Bonne-Andrea
- Centre de Recherche de Biologie cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, 34293 Montpellier, France
| | - Véronique Baldin
- Centre de Recherche de Biologie cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, 34293 Montpellier, France
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15
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Puente-Bedia A, Berciano MT, Tapia O, Martínez-Cué C, Lafarga M, Rueda N. Nuclear Reorganization in Hippocampal Granule Cell Neurons from a Mouse Model of Down Syndrome: Changes in Chromatin Configuration, Nucleoli and Cajal Bodies. Int J Mol Sci 2021; 22:ijms22031259. [PMID: 33514010 PMCID: PMC7865916 DOI: 10.3390/ijms22031259] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2020] [Revised: 01/16/2021] [Accepted: 01/22/2021] [Indexed: 01/05/2023] Open
Abstract
Down syndrome (DS) or trisomy of chromosome 21 (Hsa21) is characterized by impaired hippocampal-dependent learning and memory. These alterations are due to defective neurogenesis and to neuromorphological and functional anomalies of numerous neuronal populations, including hippocampal granular cells (GCs). It has been proposed that the additional gene dose in trisomic cells induces modifications in nuclear compartments and on the chromatin landscape, which could contribute to some DS phenotypes. The Ts65Dn (TS) mouse model of DS carries a triplication of 92 genes orthologous to those found in Hsa21, and shares many phenotypes with DS individuals, including cognitive and neuromorphological alterations. Considering its essential role in hippocampal memory formation, we investigated whether the triplication of this set of Hsa21 orthologous genes in TS mice modifies the nuclear architecture of their GCs. Our results show that the TS mouse presents alterations in the nuclear architecture of its GCs, affecting nuclear compartments involved in transcription and pre-rRNA and pre-mRNA processing. In particular, the GCs of the TS mouse show alterations in the nucleolar fusion pattern and the molecular assembly of Cajal bodies (CBs). Furthermore, hippocampal GCs of TS mice present an epigenetic dysregulation of chromatin that results in an increased heterochromatinization and reduced global transcriptional activity. These nuclear alterations could play an important role in the neuromorphological and/or functional alterations of the hippocampal GCs implicated in the cognitive dysfunction characteristic of TS mice.
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Affiliation(s)
- Alba Puente-Bedia
- Department of Physiology and Pharmacology, Faculty of Medicine, University of Cantabria, 39011 Santander, Spain; (A.P.-B.); (C.M.-C.)
| | - María T. Berciano
- Department of Molecular Biology, “Red sobre Enfermedades Neurodegenerativas (CIBERNED)” and University of Cantabria-IDIVAL, 39011 Santander, Spain;
| | - Olga Tapia
- Instituto de Investigación Sanitaria Valdecilla (IDIVAL), “Red sobre Enfermedades Neurodegenerativas (CIBERNED)” and Universidad Europea del Atlántico, 39011 Santander, Spain;
| | - Carmen Martínez-Cué
- Department of Physiology and Pharmacology, Faculty of Medicine, University of Cantabria, 39011 Santander, Spain; (A.P.-B.); (C.M.-C.)
| | - Miguel Lafarga
- Department of Anatomy and Cell Biology, “Red sobre Enfermedades Neurodegenerativas (CIBERNED)” and University of Cantabria-IDIVAL, 39011 Santander, Spain
- Correspondence: (M.L.); (N.R.); Tel.: +34-942201966 (N.R.); Fax: +34-942201903 (N.R.)
| | - Noemí Rueda
- Department of Physiology and Pharmacology, Faculty of Medicine, University of Cantabria, 39011 Santander, Spain; (A.P.-B.); (C.M.-C.)
- Correspondence: (M.L.); (N.R.); Tel.: +34-942201966 (N.R.); Fax: +34-942201903 (N.R.)
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16
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Machitani M, Taniguchi I, McCloskey A, Suzuki T, Ohno M. The RNA transport factor PHAX is required for proper histone H2AX expression and DNA damage response. RNA (NEW YORK, N.Y.) 2020; 26:1716-1725. [PMID: 32759388 PMCID: PMC7566570 DOI: 10.1261/rna.074625.120] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/01/2020] [Accepted: 08/02/2020] [Indexed: 06/11/2023]
Abstract
PHAX (phosphorylated adaptor for RNA export) promotes nuclear export of short transcripts of RNA polymerase II such as spliceosomal U snRNA precursors, as well as intranuclear transport of small nucleolar RNAs (snoRNAs). However, it remains unknown whether PHAX has other critical functions. Here we show that PHAX is required for efficient DNA damage response (DDR) via regulation of phosphorylated histone variant H2AX (γH2AX), a key factor for DDR. Knockdown of PHAX led to a significant reduction of H2AX mRNA levels, through inhibition of both transcription of the H2AX gene and nuclear export of H2AX mRNA, one of the shortest mRNAs in the cell. As a result, PHAX-knockdown cells become more sensitive to DNA damage due to a shortage of γH2AX. These results reveal a novel function of PHAX, which secures efficient DDR and hence genome stability.
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Affiliation(s)
- Mitsuhiro Machitani
- Institute for Frontier Life and Medical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan
- Division of Cancer Stem Cell, National Cancer Center Research Institute, Tokyo 104-0045, Japan
| | - Ichiro Taniguchi
- Institute for Frontier Life and Medical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan
| | - Asako McCloskey
- Institute for Frontier Life and Medical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan
| | - Tatsuya Suzuki
- Institute for Frontier Life and Medical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan
| | - Mutsuhito Ohno
- Institute for Frontier Life and Medical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan
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Boulpicante M, Darrigrand R, Pierson A, Salgues V, Rouillon M, Gaudineau B, Khaled M, Cattaneo A, Bachi A, Cascio P, Apcher S. Tumors escape immunosurveillance by overexpressing the proteasome activator PSME3. Oncoimmunology 2020; 9:1761205. [PMID: 32923122 PMCID: PMC7458623 DOI: 10.1080/2162402x.2020.1761205] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 04/03/2020] [Indexed: 11/09/2022] Open
Abstract
The success of CD8+ T cell-based cancer immunotherapy emphasizes the importance of understanding the mechanisms of generation of MHC-I peptide ligands and the possible pathways of tumor cell escape from immunosurveillance. Recently, we showed that peptides generated in the nucleus during a pioneer round of mRNA translation (pioneer translation products, or PTPs) are an important source of tumor specific peptides which correlates with the aberrant splicing and transcription events associated with oncogenesis. Here we show that up-regulation of PSME3 proteasome activator in cancer cells results in increased destruction of PTP-derived peptides in the nucleus thus enabling cancer cell to subvert immunosurveillance. These findings unveil a previously unexpected role for PSME3 in antigen processing and identify PSME3 as a druggable target to improve the efficacy of cancer immunotherapy.
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Affiliation(s)
- Mathilde Boulpicante
- Immunologie des Tumeurs et Immunothérapie, Université Paris-Saclay, Institut Gustave Roussy, Inserm, Villejuif, France
| | - Romain Darrigrand
- Immunologie des Tumeurs et Immunothérapie, Université Paris-Saclay, Institut Gustave Roussy, Inserm, Villejuif, France
| | - Alison Pierson
- Immunologie des Tumeurs et Immunothérapie, Université Paris-Saclay, Institut Gustave Roussy, Inserm, Villejuif, France
| | - Valérie Salgues
- Immunologie des Tumeurs et Immunothérapie, Université Paris-Saclay, Institut Gustave Roussy, Inserm, Villejuif, France
| | - Marine Rouillon
- Immunologie des Tumeurs et Immunothérapie, Université Paris-Saclay, Institut Gustave Roussy, Inserm, Villejuif, France
| | - Benoit Gaudineau
- Dynamique des Cellules Tumorales, Université Paris-Saclay, Institut Gustave Roussy, Inserm, Villejuif, France
| | - Mehdi Khaled
- Dynamique des Cellules Tumorales, Université Paris-Saclay, Institut Gustave Roussy, Inserm, Villejuif, France
| | - Angela Cattaneo
- IFOM, The FIRC Institute of Molecular Oncology, Milano, Italy
| | - Angela Bachi
- IFOM, The FIRC Institute of Molecular Oncology, Milano, Italy
| | - Paolo Cascio
- Department of Veterinary Sciences, University of Turin, 10095, Grugliasco, Turin, Italy
| | - Sébastien Apcher
- Immunologie des Tumeurs et Immunothérapie, Université Paris-Saclay, Institut Gustave Roussy, Inserm, Villejuif, France
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18
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Wang X, Meul T, Meiners S. Exploring the proteasome system: A novel concept of proteasome inhibition and regulation. Pharmacol Ther 2020; 211:107526. [PMID: 32173559 DOI: 10.1016/j.pharmthera.2020.107526] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 03/08/2020] [Indexed: 12/13/2022]
Abstract
The proteasome is a well-identified therapeutic target for cancer treatment. It acts as the main protein degradation system in the cell and degrades key mediators of cell growth, survival and function. The term "proteasome" embraces a whole family of distinct complexes, which share a common proteolytic core, the 20S proteasome, but differ by their attached proteasome activators. Each of these proteasome complexes plays specific roles in the control of cellular function. In addition, distinct proteasome interacting proteins regulate proteasome activity in subcellular compartments and in response to cellular signals. Proteasome activators and regulators may thus serve as building blocks to fine-tune proteasome function in the cell according to cellular needs. Inhibitors of the proteasome, e.g. the FDA approved drugs Velcade™, Kyprolis™, Ninlaro™, inactivate the catalytic 20S core and effectively block protein degradation of all proteasome complexes in the cell resulting in inhibition of cell growth and induction of apoptosis. Efficacy of these inhibitors, however, is hampered by their pronounced cytotoxic side-effects as well as by the emerging development of resistance to catalytic proteasome inhibitors. Targeted inhibition of distinct buiding blocks of the proteasome system, i.e. proteasome activators or regulators, represents an alternative strategy to overcome these limitations. In this review, we stress the importance of the diversity of the proteasome complexes constituting an entire proteasome system. Our building block concept provides a rationale for the defined targeting of distinct proteasome super-complexes in disease. We thereby aim to stimulate the development of innovative therapeutic approaches beyond broad catalytic proteasome inhibition.
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Affiliation(s)
- Xinyuan Wang
- Comprehensive Pneumology Center (CPC), University Hospital of the Ludwig-Maximilians-University (LMU) and Helmholtz Zentrum München, German Center for Lung Research (DZL), 81377 Munich, Germany
| | - Thomas Meul
- Comprehensive Pneumology Center (CPC), University Hospital of the Ludwig-Maximilians-University (LMU) and Helmholtz Zentrum München, German Center for Lung Research (DZL), 81377 Munich, Germany
| | - Silke Meiners
- Comprehensive Pneumology Center (CPC), University Hospital of the Ludwig-Maximilians-University (LMU) and Helmholtz Zentrum München, German Center for Lung Research (DZL), 81377 Munich, Germany.
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Yasuda S, Tsuchiya H, Kaiho A, Guo Q, Ikeuchi K, Endo A, Arai N, Ohtake F, Murata S, Inada T, Baumeister W, Fernández-Busnadiego R, Tanaka K, Saeki Y. Stress- and ubiquitylation-dependent phase separation of the proteasome. Nature 2020; 578:296-300. [DOI: 10.1038/s41586-020-1982-9] [Citation(s) in RCA: 124] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Accepted: 12/09/2019] [Indexed: 12/30/2022]
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20
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Coux O, Zieba BA, Meiners S. The Proteasome System in Health and Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1233:55-100. [DOI: 10.1007/978-3-030-38266-7_3] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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21
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Kors S, Geijtenbeek K, Reits E, Schipper-Krom S. Regulation of Proteasome Activity by (Post-)transcriptional Mechanisms. Front Mol Biosci 2019; 6:48. [PMID: 31380390 PMCID: PMC6646590 DOI: 10.3389/fmolb.2019.00048] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 06/11/2019] [Indexed: 12/23/2022] Open
Abstract
Intracellular protein synthesis, folding, and degradation are tightly controlled processes to ensure proper protein homeostasis. The proteasome is responsible for the degradation of the majority of intracellular proteins, which are often targeted for degradation via polyubiquitination. However, the degradation rate of proteins is also affected by the capacity of proteasomes to recognize and degrade these substrate proteins. This capacity is regulated by a variety of proteasome modulations including (1) changes in complex composition, (2) post-translational modifications, and (3) altered transcription of proteasomal subunits and activators. Various diseases are linked to proteasome modulation and altered proteasome function. A better understanding of these modulations may offer new perspectives for therapeutic intervention. Here we present an overview of these three proteasome modulating mechanisms to give better insight into the diversity of proteasomes.
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Affiliation(s)
- Suzan Kors
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Karlijne Geijtenbeek
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Eric Reits
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Sabine Schipper-Krom
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
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22
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Hayashi K, Matsunaga S. Heat and chilling stress induce nucleolus morphological changes. JOURNAL OF PLANT RESEARCH 2019; 132:395-403. [PMID: 30847615 PMCID: PMC7198650 DOI: 10.1007/s10265-019-01096-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2018] [Accepted: 02/12/2019] [Indexed: 05/20/2023]
Abstract
The nucleolus, where components of the ribosome are constructed, is known to play an important role in various stress responses in animals. However, little is known about the role of the plant nucleolus under environmental stresses such as heat and chilling stress. In this study, we analyzed nucleolus morphology by determining the distribution of newly synthesized rRNAs with an analog of uridine, 5-ethynyl uridine (EU). When EU was incorporated into the root of the Arabidopsis thaliana, EU signals were strongly localized in the nucleolus. The results of the short-term incorporation of EU implied that there is no compartmentation among the processes of transcription, processing, and construction of rRNAs. Nevertheless, under heat and chilling stress, EU was not incorporated into the center of the nucleolus. Morphological analyses using whole rRNA staining and differential interference contrast observations revealed speckled and round structures in the center of the nucleolus under heat and chilling stress, respectively.
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Affiliation(s)
- Kohma Hayashi
- Department of Applied Biological Science Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba, 278-8510, Japan
| | - Sachihiro Matsunaga
- Department of Applied Biological Science Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba, 278-8510, Japan.
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23
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Jonik-Nowak B, Menneteau T, Fesquet D, Baldin V, Bonne-Andrea C, Méchali F, Fabre B, Boisguerin P, de Rossi S, Henriquet C, Pugnière M, Ducoux-Petit M, Burlet-Schiltz O, Lamond AI, Fort P, Boulon S, Bousquet MP, Coux O. PIP30/FAM192A is a novel regulator of the nuclear proteasome activator PA28γ. Proc Natl Acad Sci U S A 2018; 115:E6477-E6486. [PMID: 29934401 PMCID: PMC6048556 DOI: 10.1073/pnas.1722299115] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
PA28γ is a nuclear activator of the 20S proteasome involved in the regulation of several essential cellular processes, such as cell proliferation, apoptosis, nuclear dynamics, and cellular stress response. Unlike the 19S regulator of the proteasome, which specifically recognizes ubiquitylated proteins, PA28γ promotes the degradation of several substrates by the proteasome in an ATP- and ubiquitin-independent manner. However, its exact mechanisms of action are unclear and likely involve additional partners that remain to be identified. Here we report the identification of a cofactor of PA28γ, PIP30/FAM192A. PIP30 binds directly and specifically via its C-terminal end and in an interaction stabilized by casein kinase 2 phosphorylation to both free and 20S proteasome-associated PA28γ. Its recruitment to proteasome-containing complexes depends on PA28γ and its expression increases the association of PA28γ with the 20S proteasome in cells. Further dissection of its possible roles shows that PIP30 alters PA28γ-dependent activation of peptide degradation by the 20S proteasome in vitro and negatively controls in cells the presence of PA28γ in Cajal bodies by inhibition of its association with the key Cajal body component coilin. Taken together, our data show that PIP30 deeply affects PA28γ interactions with cellular proteins, including the 20S proteasome, demonstrating that it is an important regulator of PA28γ in cells and thus a new player in the control of the multiple functions of the proteasome within the nucleus.
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Affiliation(s)
- Beata Jonik-Nowak
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, 34090 Montpellier, France
| | - Thomas Menneteau
- Institut de Pharmacologie et Biologie Structurale (IPBS), CNRS, Université de Toulouse-Université Paul Sabatier, 31062 Toulouse, France
| | - Didier Fesquet
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, 34090 Montpellier, France
| | - Véronique Baldin
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, 34090 Montpellier, France
| | - Catherine Bonne-Andrea
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, 34090 Montpellier, France
| | - Francisca Méchali
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, 34090 Montpellier, France
| | - Bertrand Fabre
- Institut de Pharmacologie et Biologie Structurale (IPBS), CNRS, Université de Toulouse-Université Paul Sabatier, 31062 Toulouse, France
| | - Prisca Boisguerin
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, 34090 Montpellier, France
| | - Sylvain de Rossi
- Montpellier Ressources Imagerie (MRI) Facility, Biocampus UMS3426, CNRS, 34090 Montpellier, France
| | - Corinne Henriquet
- Institut de Recherche en Cancérologie de Montpellier (IRCM) - INSERM U1194, Institut Régional du Cancer de Montpellier, Université de Montpellier, F-34298 Montpellier, France
| | - Martine Pugnière
- Institut de Recherche en Cancérologie de Montpellier (IRCM) - INSERM U1194, Institut Régional du Cancer de Montpellier, Université de Montpellier, F-34298 Montpellier, France
| | - Manuelle Ducoux-Petit
- Institut de Pharmacologie et Biologie Structurale (IPBS), CNRS, Université de Toulouse-Université Paul Sabatier, 31062 Toulouse, France
| | - Odile Burlet-Schiltz
- Institut de Pharmacologie et Biologie Structurale (IPBS), CNRS, Université de Toulouse-Université Paul Sabatier, 31062 Toulouse, France
| | - Angus I Lamond
- Centre for Gene Regulation and Expression, School of Life Sciences, DD1 5HL Dundee, United Kingdom
| | - Philippe Fort
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, 34090 Montpellier, France
| | - Séverine Boulon
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, 34090 Montpellier, France;
| | - Marie-Pierre Bousquet
- Institut de Pharmacologie et Biologie Structurale (IPBS), CNRS, Université de Toulouse-Université Paul Sabatier, 31062 Toulouse, France;
| | - Olivier Coux
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, 34090 Montpellier, France;
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24
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Chen QZ, Luo F, Lu MX, Li N, Teng Y, Huang QL, Zhu N, Wang GY, Yue M, Zhang Y, Feng Y, Xiong HR, Hou W. HTNV-induced upregulation of miR-146a in HUVECs promotes viral infection by modulating pro-inflammatory cytokine release. Biochem Biophys Res Commun 2017; 493:807-813. [PMID: PMID: 28843856 DOI: 10.1016/j.bbrc.2017.08.073] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 08/19/2017] [Indexed: 10/19/2022]
Abstract
Increasing research has shown a link between viruses and miRNAs, such as miRNA-146a, in regulating virus infection and replication. In the current study, the association between miR-146a and hantaan virus (HTNV) infection in human umbilical vein endothelial cells (HUVECs) was investigated, with a focus on examining the expression of pro-inflammatory cytokines. The results showed that HTNV infection promoted the production of miR-146a in HUVECs and activated nuclear factor-κB (NF-κB) signaling, along with the upregulation of pro-inflammatory cytokines, including interleukin 8 (IL-8), C-C Motif Chemokine Ligand 5 (CCL5, also RANTES), interferon-inducible protein-10 (IP-10) and interferon beta (IFN-β). Moreover, miR-146a exhibited a negative regulatory effect on the NF-κB pathway. Accordingly, a miR-146a inhibitor increased the expression of IL-8, CCL5, IP-10 and IFN-β, whereas a miR-146a mimic reduced the levels of these cytokines. Consequently, exogenous transduction of miR-146a significantly enhanced HTNV replication in HUVEC cells. We also discovered that viral proteins (NP/GP) contributed to miR-146a expression via enhancement the activity of miR-146a promoter. In conclusion, these results imply the negative regulation of miR-146a on the production of HTNV-induced pro-inflammatory cytokines contributes to virus replication, which suggest that miR-146a may be regarded as a novel therapeutic target for HTNV infection.
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Affiliation(s)
- Qing-Zhou Chen
- State Key Laboratory of Virology, Institute of Medical Virology, Hubei Province Key Laboratory of Allergy and Immunology, School of Basic Medical Sciences, Wuhan University, 185 Donghu Road, Wuhan 430071, Hubei Province, China
| | - Fan Luo
- State Key Laboratory of Virology, Institute of Medical Virology, Hubei Province Key Laboratory of Allergy and Immunology, School of Basic Medical Sciences, Wuhan University, 185 Donghu Road, Wuhan 430071, Hubei Province, China
| | - Ming-Xiang Lu
- Center for Gene Diagnosis, Zhongnan Hospital, Wuhan University, 169 Donghu Road, Wuhan 430071, Hubei Province, China
| | - Ning Li
- State Key Laboratory of Virology, Institute of Medical Virology, Hubei Province Key Laboratory of Allergy and Immunology, School of Basic Medical Sciences, Wuhan University, 185 Donghu Road, Wuhan 430071, Hubei Province, China
| | - Yan Teng
- State Key Laboratory of Virology, Institute of Medical Virology, Hubei Province Key Laboratory of Allergy and Immunology, School of Basic Medical Sciences, Wuhan University, 185 Donghu Road, Wuhan 430071, Hubei Province, China
| | - Qiu-Ling Huang
- State Key Laboratory of Virology, Institute of Medical Virology, Hubei Province Key Laboratory of Allergy and Immunology, School of Basic Medical Sciences, Wuhan University, 185 Donghu Road, Wuhan 430071, Hubei Province, China
| | - Ni Zhu
- School of Basic Medicine, Hubei University of Science and Technology, No.88 Xianning Avenue, Xianning 437100, Hubei Province, China
| | - Guan-Yi Wang
- State Key Laboratory of Virology, Institute of Medical Virology, Hubei Province Key Laboratory of Allergy and Immunology, School of Basic Medical Sciences, Wuhan University, 185 Donghu Road, Wuhan 430071, Hubei Province, China
| | - Ming Yue
- Department of Infectious Diseases, The First Affiliated Hospital of Nanjing Medical University, No.300 Guangzhou Road, Nanjing 210029, Jiangsu Province, China
| | - Yun Zhang
- Institute of Military Medical Sciences Nanjing Command, Nanjing 210002, Jiangsu Province, China
| | - Yong Feng
- State Key Laboratory of Virology, Institute of Medical Virology, Hubei Province Key Laboratory of Allergy and Immunology, School of Basic Medical Sciences, Wuhan University, 185 Donghu Road, Wuhan 430071, Hubei Province, China
| | - Hai-Rong Xiong
- State Key Laboratory of Virology, Institute of Medical Virology, Hubei Province Key Laboratory of Allergy and Immunology, School of Basic Medical Sciences, Wuhan University, 185 Donghu Road, Wuhan 430071, Hubei Province, China.
| | - Wei Hou
- State Key Laboratory of Virology, Institute of Medical Virology, Hubei Province Key Laboratory of Allergy and Immunology, School of Basic Medical Sciences, Wuhan University, 185 Donghu Road, Wuhan 430071, Hubei Province, China; School of Basic Medicine, Hubei University of Science and Technology, No.88 Xianning Avenue, Xianning 437100, Hubei Province, China.
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25
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Tapia O, Narcís JO, Riancho J, Tarabal O, Piedrafita L, Calderó J, Berciano MT, Lafarga M. Cellular bases of the RNA metabolism dysfunction in motor neurons of a murine model of spinal muscular atrophy: Role of Cajal bodies and the nucleolus. Neurobiol Dis 2017; 108:83-99. [PMID: 28823932 DOI: 10.1016/j.nbd.2017.08.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 08/01/2017] [Accepted: 08/16/2017] [Indexed: 02/06/2023] Open
Abstract
Spinal muscular atrophy (SMA) is caused by a homozygous deletion or mutation in the survival motor neuron 1 (SMN1) gene that leads to reduced levels of SMN protein resulting in degeneration of motor neurons (MNs). The best known functions of SMN is the biogenesis of spliceosomal snRNPs. Linked to this function, Cajal bodies (CBs) are involved in the assembly of spliceosomal (snRNPs) and nucleolar (snoRNPs) ribonucleoproteins required for pre-mRNA and pre-rRNA processing. Recent studies support that the interaction between CBs and nucleoli, which are especially prominent in neurons, is essential for the nucleolar rRNA homeostasis. We use the SMN∆7 murine model of type I SMA to investigate the cellular basis of the dysfunction of RNA metabolism in MNs. SMN deficiency in postnatal MNs produces a depletion of functional CBs and relocalization of coilin, which is a scaffold protein of CBs, in snRNP-free perinucleolar caps or within the nucleolus. Disruption of CBs is the earliest nuclear sign of MN degeneration. We demonstrate that depletion of CBs, with loss of CB-nucleolus interactions, induces a progressive nucleolar dysfunction in ribosome biogenesis. It includes reorganization and loss of nucleolar transcription units, segregation of dense fibrillar and granular components, retention of SUMO-conjugated proteins in intranucleolar bodies and a reactive, compensatory, up-regulation of mature 18S rRNA and genes encoding key nucleolar proteins, such as upstream binding factor, fibrillarin, nucleolin and nucleophosmin. We propose that CB depletion and nucleolar alterations are essential components of the dysfunction of RNA metabolism in SMA.
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Affiliation(s)
- Olga Tapia
- Department of Anatomy and Cell Biology and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)", University of Cantabria-IDIVAL, Santander, Spain
| | - Josep Oriol Narcís
- Department of Anatomy and Cell Biology and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)", University of Cantabria-IDIVAL, Santander, Spain
| | - Javier Riancho
- Service of Neurology, University Hospital Marqués de Valdecilla-IDIVAL-CIBERNED, Santander, Spain
| | - Olga Tarabal
- Department of Experimental Medicine, School of Medicine, University of Lleida and "Institut de Recerca Biomèdica de Lleida" (IRBLLEIDA), Lleida, Spain
| | - Lídia Piedrafita
- Department of Experimental Medicine, School of Medicine, University of Lleida and "Institut de Recerca Biomèdica de Lleida" (IRBLLEIDA), Lleida, Spain
| | - Jordi Calderó
- Department of Experimental Medicine, School of Medicine, University of Lleida and "Institut de Recerca Biomèdica de Lleida" (IRBLLEIDA), Lleida, Spain
| | - Maria T Berciano
- Department of Anatomy and Cell Biology and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)", University of Cantabria-IDIVAL, Santander, Spain
| | - Miguel Lafarga
- Department of Anatomy and Cell Biology and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)", University of Cantabria-IDIVAL, Santander, Spain.
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26
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Sawyer IA, Hager GL, Dundr M. Specific genomic cues regulate Cajal body assembly. RNA Biol 2017; 14:791-803. [PMID: 27715441 PMCID: PMC5519236 DOI: 10.1080/15476286.2016.1243648] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 09/06/2016] [Accepted: 09/27/2016] [Indexed: 02/07/2023] Open
Abstract
The assembly of specialized sub-nuclear microenvironments known as nuclear bodies (NBs) is important for promoting efficient nuclear function. In particular, the Cajal body (CB), a prominent NB that facilitates spliceosomal snRNP biogenesis, assembles in response to genomic cues. Here, we detail the factors that regulate CB assembly and structural maintenance. These include the importance of transcription at nucleating gene loci, the grouping of these genes on human chromosomes 1, 6 and 17, as well as cell cycle and biochemical regulation of CB protein function. We also speculate on the correlation between CB formation and RNA splicing levels in neurons and cancer. The timing and location of these specific molecular events is critical to CB assembly and its contribution to genome function. However, further work is required to explore the emerging biophysical characteristics of CB assembly and the impact upon subsequent genome reorganization.
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Affiliation(s)
- Iain A. Sawyer
- Department of Cell Biology, Rosalind Franklin University of Medicine & Science, Chicago Medical School, North Chicago, IL, USA
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Gordon L. Hager
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Miroslav Dundr
- Department of Cell Biology, Rosalind Franklin University of Medicine & Science, Chicago Medical School, North Chicago, IL, USA
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27
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Yersak JM, Montie HL, Chevalier-Larsen ES, Liu Y, Huang L, Rechsteiner M, Merry DE. The 11S Proteasomal Activator REGγ Impacts Polyglutamine-Expanded Androgen Receptor Aggregation and Motor Neuron Viability through Distinct Mechanisms. Front Mol Neurosci 2017; 10:159. [PMID: 28596723 PMCID: PMC5442185 DOI: 10.3389/fnmol.2017.00159] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 05/08/2017] [Indexed: 12/02/2022] Open
Abstract
Spinal and bulbar muscular atrophy (SBMA) is caused by expression of a polyglutamine (polyQ)-expanded androgen receptor (AR). The inefficient nuclear proteasomal degradation of the mutant AR results in the formation of nuclear inclusions containing amino-terminal fragments of the mutant AR. PA28γ (also referred to as REGγ) is a nuclear 11S-proteasomal activator with limited proteasome activation capabilities compared to its cytoplasmic 11S (PA28α, PA28β) counterparts. To clarify the role of REGγ in polyQ-expanded AR metabolism, we carried out genetic and biochemical studies in cell models of SBMA. Overexpression of REGγ in a PC12 cell model of SBMA increased polyQ-expanded AR aggregation and contributed to polyQ-expanded AR toxicity in the presence of dihydrotestosterone (DHT). These effects of REGγ were independent of its association with the proteasome and may be due, in part, to the decreased binding of polyQ-expanded AR by the E3 ubiquitin-ligase MDM2. Unlike its effects in PC12 cells, REGγ overexpression rescued transgenic SBMA motor neurons from DHT-induced toxicity in a proteasome binding-dependent manner, suggesting that the degradation of a specific 11S proteasome substrate or substrates promotes motor neuron viability. One potential substrate that we found to play a role in mutant AR toxicity is the splicing factor SC35. These studies reveal that, depending on the cellular context, two biological roles for REGγ impact cell viability in the face of polyQ-expanded AR; a proteasome binding-independent mechanism directly promotes mutant AR aggregation while a proteasome binding-dependent mechanism promotes cell viability. The balance between these functions likely determines REGγ effects on polyQ-expanded AR-expressing cells.
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Affiliation(s)
- Jill M. Yersak
- Department of Biochemistry and Molecular Biology, Thomas Jefferson UniversityPhiladelphia, PA, United States
| | - Heather L. Montie
- Department of Biochemistry and Molecular Biology, Thomas Jefferson UniversityPhiladelphia, PA, United States
| | - Erica S. Chevalier-Larsen
- Department of Biochemistry and Molecular Biology, Thomas Jefferson UniversityPhiladelphia, PA, United States
| | - Yuhong Liu
- Department of Biochemistry and Molecular Biology, Thomas Jefferson UniversityPhiladelphia, PA, United States
| | - Lan Huang
- Department of Microbiology and Immunology, Thomas Jefferson UniversityPhiladelphia, PA, United States
| | - Martin Rechsteiner
- Department of Biochemistry, University of Utah School of MedicineSalt Lake City, UT, United States
| | - Diane E. Merry
- Department of Biochemistry and Molecular Biology, Thomas Jefferson UniversityPhiladelphia, PA, United States
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28
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Song Y, Niu J, Yue Z, Gao R, Zhang C, Ding W. Increased chemo-sensitivity by knockdown coilin expression involved acceleration of premature cellular senescence in HeLa cells. Biochem Biophys Res Commun 2017; 489:123-129. [PMID: 28536075 DOI: 10.1016/j.bbrc.2017.05.108] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 05/19/2017] [Indexed: 12/22/2022]
Abstract
Coilin is a marker protein of the Cajal body (CB). Cajal bodies, functional nuclear structure, play important roles for the maturation of telomerase mRNAs. However, whether CB participates in the process of cell senescence is unknown. Cisplatin is a frequently used drug for the chemotherapy for various cancers, which was recently reported to be able to induce premature senescence of tumor cells. In this study, we found that when HeLa cells were treated with 2 μg/ml cisplatin for 4 days, stagnant cell growth, especially in cells stained positive of SA-β-gal, was accompanied with significant changes in CB morphologies. The removal of cisplatin allowed the recovery of normal CB appearance, but was not able to restore cells from senescent states. Knocking down coilin expression by siRNA attenuated the growth and reduced the viability of treated cells, and the decreased rate of CB formation correlated with increased staining of SA-β-gal. Interestingly, when coilin knocked-down cells exposed to cisplatin, the drug sensitivity as shown by the reduction of cell viability was significantly increased compared to the control siRNA transfection groups. Overexpression of coilin phosphomutants increased SA-β-gal fluorescence following treatments with cisplatin as compared to the wild type coilin transfection. Our results indicated that coilin was an important functional player that involved in cisplatin-induced premature cell senescence. It suggested that the modulation of coilin expression could be considered as a potential anti-tumor strategy to increase the sensitivity of chemotherapy through which drug-induced cell senescence was accelerated.
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Affiliation(s)
- Yaoyao Song
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Capital Medical University, PR China
| | - Jing Niu
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Capital Medical University, PR China; Beijing Key Laboratory for Tumor Invasion and Metastasis Research, Cancer Institute of Capital Medical University, PR China
| | - Zhixia Yue
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Capital Medical University, PR China; Hematology Oncology Center at Beijing Children's Hospital in Affiliation of Capital Medical University, PR China
| | - Ruiqi Gao
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Capital Medical University, PR China
| | - Chenguang Zhang
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Capital Medical University, PR China; Beijing Key Laboratory for Tumor Invasion and Metastasis Research, Cancer Institute of Capital Medical University, PR China
| | - Wei Ding
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Capital Medical University, PR China; Beijing Key Laboratory for Tumor Invasion and Metastasis Research, Cancer Institute of Capital Medical University, PR China; Beijing Institute of Brain Disorders, PR China.
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29
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Baculovirus FP25K Localization: Role of the Coiled-Coil Domain. J Virol 2016; 90:9582-9597. [PMID: 27512078 DOI: 10.1128/jvi.01241-16] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2016] [Accepted: 08/03/2016] [Indexed: 11/20/2022] Open
Abstract
Two types of viruses are produced during the baculovirus life cycle: budded virus (BV) and occlusion-derived virus (ODV). A particular baculovirus protein, FP25K, is involved in the switch from BV to ODV production. Previously, FP25K from the model alphabaculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV) was shown to traffic ODV envelope proteins. However, FP25K localization and the domains involved are inconclusive. Here we used a quantitative approach to study FP25K subcellular localization during infection using an AcMNPV bacmid virus that produces a functional AcMNPV FP25K-green fluorescent protein (GFP) fusion protein. During cell infection, FP25K-GFP localized primarily to the cytoplasm, particularly amorphous structures, with a small fraction being localized in the nucleus. To investigate the sequences involved in FP25K localization, an alignment of baculovirus FP25K sequences revealed that the N-terminal putative coiled-coil domain is present in all alphabaculoviruses but absent in betabaculoviruses. Structural prediction indicated a strong relatedness of AcMNPV FP25K to long interspersed element 1 (LINE-1) open reading frame 1 protein (ORF1p), which contains an N-terminal coiled-coil domain responsible for cytoplasmic retention. Point mutations and deletions of this domain lead to a change in AcMNPV FP25K localization from cytoplasmic to nuclear. The coiled-coil and C-terminal deletion viruses increased BV production. Furthermore, a betabaculovirus FP25K protein lacking this N-terminal coiled-coil domain localized predominantly to the nucleus and exhibited increased BV production. These data suggest that the acquisition of this N-terminal coiled-coil domain in FP25K is important for the evolution of alphabaculoviruses. Moreover, with the divergence of preocclusion nuclear membrane breakdown in betabaculoviruses and membrane integrity in alphabaculoviruses, this domain represents an alphabaculovirus adaptation for nuclear trafficking of occlusion-associated proteins. IMPORTANCE Baculovirus infection produces two forms of viruses: BV and ODV. Manufacturing of ODV involves trafficking of envelope proteins to the inner nuclear membrane, mediated partly through the FP25K protein. Since FP25K is present in alpha-, beta-, and gammabaculoviruses, it is uncertain if this trafficking function is conserved. In this study, we looked at alpha- and betabaculovirus FP25K trafficking by its localization. Alphabaculovirus FP25K localized primarily to the cytoplasm, whereas betabaculovirus FP25K localized to the nucleus. We found that an N-terminal coiled-coil domain present in all alphabaculovirus FP25K proteins, but absent in betabaculovirus FP25K, was critical for alphabaculovirus FP25K cytoplasmic localization. We believe that this represents an evolutionary process that partly led to the gain of function of this N-terminal coiled-coil domain in alphabaculovirus FP25K to aid in nuclear trafficking of occlusion-associated proteins. Due to betabaculovirus breakdown of the nuclear membrane before occlusion, this function is not needed, and the domain was lost or never acquired.
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30
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Hebert MD, Poole AR. Towards an understanding of regulating Cajal body activity by protein modification. RNA Biol 2016; 14:761-778. [PMID: 27819531 DOI: 10.1080/15476286.2016.1243649] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The biogenesis of small nuclear ribonucleoproteins (snRNPs), small Cajal body-specific RNPs (scaRNPs), small nucleolar RNPs (snoRNPs) and the telomerase RNP involves Cajal bodies (CBs). Although many components enriched in the CB contain post-translational modifications (PTMs), little is known about how these modifications impact individual protein function within the CB and, in concert with other modified factors, collectively regulate CB activity. Since all components of the CB also reside in other cellular locations, it is also important that we understand how PTMs affect the subcellular localization of CB components. In this review, we explore the current knowledge of PTMs on the activity of proteins known to enrich in CBs in an effort to highlight current progress as well as illuminate paths for future investigation.
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Affiliation(s)
- Michael D Hebert
- a Department of Biochemistry , The University of Mississippi Medical Center , Jackson , MS , USA
| | - Aaron R Poole
- a Department of Biochemistry , The University of Mississippi Medical Center , Jackson , MS , USA
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31
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Abstract
Cajal is commonly regarded as the father of modern neuroscience in recognition of his fundamental work on the structure of the nervous system. But Cajal also made seminal contributions to the knowledge of nuclear structure in the early 1900s, including the discovery of the "accessory body" later renamed "Cajal body" (CB). This important nuclear structure has emerged as a center for the assembly of ribonucleoproteins (RNPs) required for splicing, ribosome biogenesis and telomere maintenance. The modern era of CB research started in the 1990s with the discovery of coilin, now known as a scaffold protein of CBs, and specific probes for small nuclear RNAs (snRNAs). In this review, we summarize what we have learned in the recent decades concerning CBs in post-mitotic neurons, thereby ruling out dynamic changes in CB functions during the cell cycle. We show that CBs are particularly prominent in neurons, where they frequently associate with the nucleolus. Neuronal CBs are transcription-dependent nuclear organelles. Indeed, their number dynamically accommodates to support the high neuronal demand for splicing and ribosome biogenesis required for sustaining metabolic and bioelectrical activity. Mature neurons have canonical CBs enriched in coilin, survival motor neuron protein and snRNPs. Disruption and loss of neuronal CBs associate with severe neuronal dysfunctions in several neurological disorders such as motor neuron diseases. In particular, CB depletion in motor neurons seems to reflect a perturbation of transcription and splicing in spinal muscular atrophy, the most common genetic cause of infant mortality.
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Affiliation(s)
- Miguel Lafarga
- a Departamento de Anatomía y Biología Celular and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)" , Universidad de Cantabria-IDIVAL , Santander , Spain
| | - Olga Tapia
- a Departamento de Anatomía y Biología Celular and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)" , Universidad de Cantabria-IDIVAL , Santander , Spain
| | - Ana M Romero
- a Departamento de Anatomía y Biología Celular and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)" , Universidad de Cantabria-IDIVAL , Santander , Spain
| | - Maria T Berciano
- a Departamento de Anatomía y Biología Celular and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)" , Universidad de Cantabria-IDIVAL , Santander , Spain
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Hernández-Ibarra JA, Laredo-Cisneros MS, Mondragón-González R, Santamaría-Guayasamín N, Cisneros B. Localization of α-Dystrobrevin in Cajal Bodies and Nucleoli: A New Role for α-Dystrobrevin in the Structure/Stability of the Nucleolus. J Cell Biochem 2016; 116:2755-65. [PMID: 25959029 DOI: 10.1002/jcb.25218] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 05/05/2015] [Indexed: 11/11/2022]
Abstract
α-Dystrobrevin (α-DB) is a cytoplasmic component of the dystrophin-associated complex involved in cell signaling; however, its recently revealed nuclear localization implies a role for this protein in the nucleus. Consistent with this, we demonstrated, in a previous work that α-DB1 isoform associates with the nuclear lamin to maintain nuclei morphology. In this study, we show the distribution of the α-DB2 isoform in different subnuclear compartments of N1E115 neuronal cells, including nucleoli and Cajal bodies, where it colocalizes with B23/nucleophosmin and Nopp140 and with coilin, respectively. Recovery in a pure nucleoli fraction undoubtedly confirms the presence of α-DB2 in the nucleolus. α-DB2 redistributes in a similar fashion to that of fibrillarin and Nopp140 upon actinomycin-mediated disruption of nucleoli and to that of coilin after disorganization of Cajal bodies through ultraviolet-irradiation, with relocalization of the proteins to the corresponding reassembled structures after cessation of the insults, which implies α-DB2 in the plasticity of these nuclear bodies. That localization of α-DB2 in the nucleolus is physiologically relevant is demonstrated by the fact that downregulation of α-DB2 resulted in both altered nucleoli structure and decreased levels of B23/nucleophosmin, fibrillarin, and Nopp140. Since α-DB2 interacts with B23/nucleophosmin and overexpression of the latter protein favors nucleolar accumulation of α-DB2, it appears that targeting of α-DB2 to the nucleolus is dependent on B23/nucleophosmin. In conclusion, we show for the first time localization of α-DB2 in nucleoli and Cajal bodies and provide evidence that α-DB2 is involved in the structure of nucleoli and might modulate nucleolar functions.
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Affiliation(s)
- Jose Anselmo Hernández-Ibarra
- Departamento de Gen, é, tica y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV- IPN), Mexico City, Mexico
| | - Marco Samuel Laredo-Cisneros
- Departamento de Gen, é, tica y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV- IPN), Mexico City, Mexico
| | - Ricardo Mondragón-González
- Departamento de Gen, é, tica y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV- IPN), Mexico City, Mexico
| | - Natalie Santamaría-Guayasamín
- Departamento de Ciencias de la Vida, Carrera de Ingeniería en Biotecnología, Universidad de las Fuerzas Armadas-ESPE, Sangolquí, Ecuador
| | - Bulmaro Cisneros
- Departamento de Gen, é, tica y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV- IPN), Mexico City, Mexico
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SCFFbl12 Increases p21Waf1/Cip1 Expression Level through Atypical Ubiquitin Chain Synthesis. Mol Cell Biol 2016; 36:2182-94. [PMID: 27215384 DOI: 10.1128/mcb.00174-16] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 05/17/2016] [Indexed: 11/20/2022] Open
Abstract
The cyclin-dependent kinase (CDK) inhibitor p21 is an unstructured protein regulated by multiple turnover pathways. p21 abundance is tightly regulated, and its defect causes tumor development. However, the mechanisms that underlie the control of p21 level are not fully understood. Here, we report a novel mechanism by which a component of the SCF ubiquitin ligase, Fbl12, augments p21 via the formation of atypical ubiquitin chains. We found that Fbl12 binds and ubiquitinates p21. Unexpectedly, Fbl12 increases the expression level of p21 by enhancing the mixed-type ubiquitination, including not only K48- but also K63-linked ubiquitin chains, followed by promotion of binding between p21 and CDK2. We also found that proteasome activator PA28γ attenuates p21 ubiquitination by interacting with Fbl12. In addition, UV irradiation induces a dissociation of p21 from Fbl12 and decreases K63-linked ubiquitination, leading to p21 degradation. These data suggest that Fbl12 is a key factor that maintains adequate intracellular concentration of p21 under normal conditions. Our finding may provide a novel possibility that p21's fate is governed by diverse ubiquitin chains.
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Abstract
Initially identified as a marker of coiled bodies (now Cajal bodies or CBs), the protein coilin was discovered a quarter of century ago. Coilin is now known to scaffold the CB, but its structure and function are poorly understood. Nearly devoid of predicted structural motifs, coilin has numerous reported molecular interactions that must underlie its role in the formation and function of CBs. In this review, we summarize what we have learned in the past 25 years about coilin's structure, post-transcriptional modifications, and interactions with RNA and proteins. We show that genes with homology to human coilin are found in primitive metazoans and comment on differences among model organisms. Coilin's function in Cajal body formation and RNP metabolism will be discussed in the light of these developments.
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Affiliation(s)
- Martin Machyna
- a Department of Molecular Biophysics & Biochemistry ; Yale University ; New Haven , CT USA
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35
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Abstract
A veritable explosion of primary research papers within the past 10 years focuses on nucleolar and ribosomal stress, and for good reason: with ribosome biosynthesis consuming ~80% of a cell’s energy, nearly all metabolic and signaling pathways lead ultimately to or from the nucleolus. We begin by describing p53 activation upon nucleolar stress resulting in cell cycle arrest or apoptosis. The significance of this mechanism cannot be understated, as oncologists are now inducing nucleolar stress strategically in cancer cells as a potential anti-cancer therapy. We also summarize the human ribosomopathies, syndromes in which ribosome biogenesis or function are impaired leading to birth defects or bone narrow failures; the perplexing problem in the ribosomopathies is why only certain cells are affected despite the fact that the causative mutation is systemic. We then describe p53-independent nucleolar stress, first in yeast which lacks p53, and then in other model metazoans that lack MDM2, the critical E3 ubiquitin ligase that normally inactivates p53. Do these presumably ancient p53-independent nucleolar stress pathways remain latent in human cells? If they still exist, can we use them to target >50% of known human cancers that lack functional p53?
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Affiliation(s)
- Allison James
- a Department of Biological Sciences; Louisiana State University; Baton Rouge, LA USA
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Henriksson S, Farnebo M. On the road with WRAP53β: guardian of Cajal bodies and genome integrity. Front Genet 2015; 6:91. [PMID: 25852739 PMCID: PMC4371746 DOI: 10.3389/fgene.2015.00091] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 02/19/2015] [Indexed: 12/16/2022] Open
Abstract
The WRAP53 gene encodes both an antisense transcript (WRAP53α) that stabilizes the tumor suppressor p53 and a protein (WRAP53β) involved in maintenance of Cajal bodies, telomere elongation and DNA repair. WRAP53β is one of many proteins containing WD40 domains, known to mediate a variety of cellular processes. These proteins lack enzymatic activity, acting instead as platforms for the assembly of large complexes of proteins and RNAs thus facilitating their interactions. WRAP53β mediates site-specific interactions between Cajal body factors and DNA repair proteins. Moreover, dysfunction of this protein has been linked to premature aging, cancer and neurodegeneration. Here we summarize the current state of knowledge concerning the multifaceted roles of WRAP53β in intracellular trafficking, formation of the Cajal body, DNA repair and maintenance of genomic integrity and discuss potential crosstalk between these processes.
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Affiliation(s)
- Sofia Henriksson
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet Stockholm, Sweden
| | - Marianne Farnebo
- Department of Oncology-Pathology, Cancer Centrum Karolinska, Karolinska Institutet Stockholm, Sweden
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Stixová L, Sehnalová P, Legartová S, Suchánková J, Hrušková T, Kozubek S, Sorokin DV, Matula P, Raška I, Kovařík A, Fulneček J, Bártová E. HP1β-dependent recruitment of UBF1 to irradiated chromatin occurs simultaneously with CPDs. Epigenetics Chromatin 2014; 7:39. [PMID: 25587355 PMCID: PMC4293114 DOI: 10.1186/1756-8935-7-39] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 12/12/2014] [Indexed: 11/24/2022] Open
Abstract
Background The repair of spontaneous and induced DNA lesions is a multistep process. Depending on the type of injury, damaged DNA is recognized by many proteins specifically involved in distinct DNA repair pathways. Results We analyzed the DNA-damage response after ultraviolet A (UVA) and γ irradiation of mouse embryonic fibroblasts and focused on upstream binding factor 1 (UBF1), a key protein in the regulation of ribosomal gene transcription. We found that UBF1, but not nucleolar proteins RPA194, TCOF, or fibrillarin, was recruited to UVA-irradiated chromatin concurrently with an increase in heterochromatin protein 1β (HP1β) level. Moreover, Förster Resonance Energy Transfer (FRET) confirmed interaction between UBF1 and HP1β that was dependent on a functional chromo shadow domain of HP1β. Thus, overexpression of HP1β with a deleted chromo shadow domain had a dominant-negative effect on UBF1 recruitment to UVA-damaged chromatin. Transcription factor UBF1 also interacted directly with DNA inside the nucleolus but no interaction of UBF1 and DNA was confirmed outside the nucleolus, where UBF1 recruitment to DNA lesions appeared simultaneously with cyclobutane pyrimidine dimers; this occurrence was cell-cycle-independent. Conclusions We propose that the simultaneous presence and interaction of UBF1 and HP1β at DNA lesions is activated by the presence of cyclobutane pyrimidine dimers and mediated by the chromo shadow domain of HP1β. This might have functional significance for nucleotide excision repair. Electronic supplementary material The online version of this article (doi:10.1186/1756-8935-7-39) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lenka Stixová
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
| | - Petra Sehnalová
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
| | - Soňa Legartová
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
| | - Jana Suchánková
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
| | - Tereza Hrušková
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
| | - Stanislav Kozubek
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
| | - Dmitry V Sorokin
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic ; Faculty of Informatics, Masaryk University, Botanická 68a, 602 00 Brno, Czech Republic
| | - Pavel Matula
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic ; Faculty of Informatics, Masaryk University, Botanická 68a, 602 00 Brno, Czech Republic
| | - Ivan Raška
- Institute of Cellular Biology and Pathology, the First Faculty of Medicine, Charles University in Prague, Albertov 4, 128 01 Prague, Czech Republic
| | - Aleš Kovařík
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
| | - Jaroslav Fulneček
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
| | - Eva Bártová
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
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38
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Pawellek A, McElroy S, Samatov T, Mitchell L, Woodland A, Ryder U, Gray D, Lührmann R, Lamond AI. Identification of small molecule inhibitors of pre-mRNA splicing. J Biol Chem 2014; 289:34683-98. [PMID: 25281741 PMCID: PMC4263873 DOI: 10.1074/jbc.m114.590976] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 10/02/2014] [Indexed: 11/06/2022] Open
Abstract
Eukaryotic pre-mRNA splicing is an essential step in gene expression for all genes that contain introns. In contrast to transcription and translation, few well characterized chemical inhibitors are available with which to dissect the splicing process, particularly in cells. Therefore, the identification of specific small molecules that either inhibit or modify pre-mRNA splicing would be valuable for research and potentially also for therapeutic applications. We have screened a highly curated library of 71,504 drug-like small molecules using a high throughput in vitro splicing assay. This identified 10 new compounds that both inhibit pre-mRNA splicing in vitro and modify splicing of endogenous pre-mRNA in cells. One of these splicing modulators, DDD00107587 (termed "madrasin," i.e. 2-((7methoxy-4-methylquinazolin-2-yl)amino)-5,6-dimethylpyrimidin-4(3H)-one RNAsplicing inhibitor), was studied in more detail. Madrasin interferes with the early stages of spliceosome assembly and stalls spliceosome assembly at the A complex. Madrasin is cytotoxic at higher concentrations, although at lower concentrations it induces cell cycle arrest, promotes a specific reorganization of subnuclear protein localization, and modulates splicing of multiple pre-mRNAs in both HeLa and HEK293 cells.
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Affiliation(s)
| | - Stuart McElroy
- the Drug Discovery Unit, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom and
| | - Timur Samatov
- the Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Lee Mitchell
- the Drug Discovery Unit, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom and
| | - Andrew Woodland
- the Drug Discovery Unit, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom and
| | - Ursula Ryder
- From the Centre of Gene Regulation and Expression and
| | - David Gray
- the Drug Discovery Unit, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom and
| | - Reinhard Lührmann
- the Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
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39
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Bártová E, Foltánková V, Legartová S, Sehnalová P, Sorokin DV, Suchánková J, Kozubek S. Coilin is rapidly recruited to UVA-induced DNA lesions and γ-radiation affects localized movement of Cajal bodies. Nucleus 2014; 5:460-8. [PMID: 24859326 DOI: 10.4161/nucl.29229] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Cajal bodies are important nuclear structures containing proteins that preferentially regulate RNA-related metabolism. We investigated the cell-type specific nuclear distribution of Cajal bodies and the level of coilin, a protein of Cajal bodies, in non-irradiated and irradiated human tumor cell lines and embryonic stem (ES) cells. Cajal bodies were localized in different nuclear compartments, including DAPI-poor regions, in the proximity of chromocenters, and adjacent to nucleoli. The number of Cajal bodies per nucleus was cell cycle-dependent, with higher numbers occurring during G2 phase. Human ES cells contained a high coilin level in the nucleoplasm, but coilin-positive Cajal bodies were also identified in nuclei of mouse and human ES cells. Coilin, but not SMN, recognized UVA-induced DNA lesions, which was cell cycle-independent. Treatment with γ-radiation reduced the localized movement of Cajal bodies in many cell types and GFP-coilin fluorescence recovery after photobleaching was very fast in nucleoplasm in comparison with GFP-coilin recovery in DNA lesions. By contrast, nucleolus-localized coilin displayed very slow fluorescence recovery after photobleaching, which indicates very slow rates of protein diffusion, especially in nucleoli of mouse ES cells.
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Affiliation(s)
- Eva Bártová
- Institute of Biophysics; Academy of Sciences of the Czech Republic; Brno, Czech Republic
| | - Veronika Foltánková
- Institute of Biophysics; Academy of Sciences of the Czech Republic; Brno, Czech Republic
| | - Soňa Legartová
- Institute of Biophysics; Academy of Sciences of the Czech Republic; Brno, Czech Republic
| | - Petra Sehnalová
- Institute of Biophysics; Academy of Sciences of the Czech Republic; Brno, Czech Republic
| | - Dmitry V Sorokin
- Faculty of Informatics; Masaryk University; Brno, Czech Republic
| | - Jana Suchánková
- Institute of Biophysics; Academy of Sciences of the Czech Republic; Brno, Czech Republic
| | - Stanislav Kozubek
- Institute of Biophysics; Academy of Sciences of the Czech Republic; Brno, Czech Republic
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40
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Palanca A, Casafont I, Berciano MT, Lafarga M. Reactive nucleolar and Cajal body responses to proteasome inhibition in sensory ganglion neurons. Biochim Biophys Acta Mol Basis Dis 2013; 1842:848-59. [PMID: 24269586 DOI: 10.1016/j.bbadis.2013.11.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 11/12/2013] [Accepted: 11/13/2013] [Indexed: 12/25/2022]
Abstract
The dysfunction of the ubiquitin proteasome system has been related to a broad array of neurodegenerative disorders in which the accumulation of misfolded protein aggregates causes proteotoxicity. The ability of proteasome inhibitors to induce cell cycle arrest and apoptosis has emerged as a powerful strategy for cancer therapy. Bortezomib is a proteasome inhibitor used as an antineoplastic drug, although its neurotoxicity frequently causes a severe sensory peripheral neuropathy. In this study we used a rat model of bortezomib treatment to study the nucleolar and Cajal body responses to the proteasome inhibition in sensory ganglion neurons that are major targets of bortezomib-induced neurotoxicity. Treatment with bortezomib induced dose-dependent dissociation of protein synthesis machinery (chromatolysis) and nuclear retention of poly(A) RNA granules resulting in neuronal dysfunction. However, as a compensatory response to the proteotoxic stress, both nucleoli and Cajal bodies exhibited reactive changes. These include an increase in the number and size of nucleoli, strong nucleolar incorporation of the RNA precursor 5'-fluorouridine, and increased expression of both 45S rRNA and genes encoding nucleolar proteins UBF, fibrillarin and B23. Taken together, these findings appear to reflect the activation of the nucleolar transcription in response to proteotoxic stress Furthermore, the number of Cajal bodies, a parameter related to transcriptional activity, increases upon proteasome inhibition. We propose that nucleoli and Cajal bodies are important targets in the signaling pathways that are activated by the proteotoxic stress response to proteasome inhibition. The coordinating activity of these two organelles in the production of snRNA, snoRNA and rRNA may contribute to neuronal survival after proteasome inhibition. This article is part of a Special Issue entitled: Role of the Nucleolus in Human Disease.
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Affiliation(s)
- Ana Palanca
- Department of Anatomy and Cell Biology, University of Cantabria-IFIMAV, Santander, Spain; "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)", Santander, Spain
| | - Iñigo Casafont
- Department of Anatomy and Cell Biology, University of Cantabria-IFIMAV, Santander, Spain; "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)", Santander, Spain
| | - María T Berciano
- Department of Anatomy and Cell Biology, University of Cantabria-IFIMAV, Santander, Spain; "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)", Santander, Spain
| | - Miguel Lafarga
- Department of Anatomy and Cell Biology, University of Cantabria-IFIMAV, Santander, Spain; "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)", Santander, Spain.
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41
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Post-transcriptional regulation by poly(ADP-ribosyl)ation of the RNA-binding proteins. Int J Mol Sci 2013; 14:16168-83. [PMID: 23921685 PMCID: PMC3759905 DOI: 10.3390/ijms140816168] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 07/23/2013] [Accepted: 07/25/2013] [Indexed: 02/07/2023] Open
Abstract
Gene expression is intricately regulated at the post-transcriptional level by RNA-binding proteins (RBPs) via their interactions with pre-messenger RNA (pre-mRNA) and mRNA during development. However, very little is known about the mechanism regulating RBP activities in RNA metabolism. During the past few years, a large body of evidence has suggested that many RBPs, such as heterogeneous nuclear ribonucleoproteins (hnRNPs), undergo post-translational modification through poly(ADP-ribosyl)ation to modulate RNA processing, including splicing, polyadenylation, translation, miRNA biogenesis and rRNA processing. Accordingly, RBP poly(ADP-ribosyl)ation has been shown to be involved in stress responses, stem cell differentiation and retinal morphogenesis. Here, we summarize recent advances in understanding the biological roles of RBP poly(ADP-ribosyl)ation, as controlled by Poly(ADP-ribose) Polymerases (PARPs) and Poly(ADP-ribose) Glycohydrolase (PARG). In addition, we discuss the potential of PARP and PARG inhibitors for the treatment of RBP-related human diseases, including cancer and neurodegenerative disorders.
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42
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Hebert MD. Signals controlling Cajal body assembly and function. Int J Biochem Cell Biol 2013; 45:1314-7. [PMID: 23583661 DOI: 10.1016/j.biocel.2013.03.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 03/28/2013] [Accepted: 03/29/2013] [Indexed: 10/27/2022]
Abstract
Cajal bodies (CBs) are subnuclear domains that participate in the biogenesis of small nuclear ribonucleoproteins (snRNPs) and telomerase. CBs are found in cells with high splicing demands, such as neuronal and cancer cells. The purpose of this review is to highlight what is known about the signals that impact the formation and activity of CBs. Particular attention is paid to phosphorylation as a major regulator of CB formation and composition, but a non-biochemical mediated pathway (mechanotransduction) that impacts CBs is also discussed. Amongst the CB components, recently published work on coilin (the CB marker protein) strongly suggests that this protein, and the CB by extension, is a global sensor that responds to environmental signals. Disruption of these signals, which would result in a decreased capacity to generate snRNPs and telomerase, is predicted to be beneficial in the treatment of cancer.
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Affiliation(s)
- Michael D Hebert
- Department of Biochemistry, The University of Mississippi Medical Center, Jackson, MS 39216 4505, USA.
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43
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Proteasome activity influences UV-mediated subnuclear localization changes of NPM. PLoS One 2013; 8:e59096. [PMID: 23554979 PMCID: PMC3595268 DOI: 10.1371/journal.pone.0059096] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Accepted: 02/12/2013] [Indexed: 01/08/2023] Open
Abstract
UV damage activates cellular stress signaling pathways, causes DNA helix distortions and inhibits transcription by RNA polymerases I and II. In particular, the nucleolus, which is the site of RNA polymerase I transcription and ribosome biogenesis, disintegrates following UV damage. The disintegration is characterized by reorganization of the subnucleolar structures and change of localization of many nucleolar proteins. Here we have queried the basis of localization change of nucleophosmin (NPM), a nucleolar granular component protein, which is increasingly detected in the nucleoplasm following UV radiation. Using photobleaching experiments of NPM-fluorescent fusion protein in live human cells we show that NPM mobility increases after UV damage. However, we show that the increase in NPM nucleoplasmic abundance after UV is independent of UV-activated cellular stress and DNA damage signaling pathways. Unexpectedly, we find that proteasome activity affects NPM redistribution. NPM nucleolar expression was maintained when the UV-treated cells were exposed to proteasome inhibitors or when the expression of proteasome subunits was inhibited using RNAi. However, there was no evidence of increased NPM turnover in the UV damaged cells, or that ubiquitin or ubiquitin recycling affected NPM localization. These findings suggest that proteasome activity couples to nucleolar protein localizations in UV damage stress.
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44
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Abstract
UNLABELLED The establishment of a latent reservoir by human tumor viruses is a vital step in initiating cellular transformation and represents a major shortcoming to current therapeutic strategies and the ability to eradicate virus-infected cells. Human T-cell leukemia virus type 1 (HTLV-1) establishes a lifelong infection and is linked to adult T-cell leukemia lymphoma (ATLL). Here, we demonstrate that HTLV-1 p30 recruits the cellular proteasome activator PA28γ onto the viral tax/rex mRNA to prevent its nuclear export and suppress virus replication. Interaction of p30 with a PA28γ retaining fully functional proteasome activity is required for p30's ability to repress HTLV-1. Consistently, HTLV-1 molecular clones replicate better and produce more virus particles in PA28γ-deficient cells. These results define a unique and novel role for the cellular factor PA28γ in the control of nuclear RNA trafficking and HTLV-1–induced latency. Importantly, knockdown of PA28γ expression in ATLL cells latently infected with HTLV-1 reactivates expression of viral tax/rex RNA and the Tax protein. Because Tax is the most immunogenic viral antigen and triggers strong CTL responses, our results suggest that PA28γ-targeted therapy may reactivate virus expression from latently infected cells and allow their eradication from the host. KEY POINTS PA28γ acts as a co-repressor of HTLV-1 p30 to suppress virus replication and is required for the maintenance of viral latency. HTLV-1 has evolved a unique function mediated by its posttranscriptional repressor p30, which is not found in HTLV-2.
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45
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Velma V, Broome HJ, Hebert MD. Regulated specific proteolysis of the Cajal body marker protein coilin. Chromosoma 2012; 121:629-42. [PMID: 23064547 DOI: 10.1007/s00412-012-0387-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Revised: 09/25/2012] [Accepted: 10/03/2012] [Indexed: 12/27/2022]
Abstract
Cajal bodies (CB) are subnuclear domains that contain various proteins with diverse functions including the CB marker protein coilin. In this study, we investigate the proteolytic activity of calpain on coilin. Here, we report a 28-kDa cleaved coilin fragment detected by two coilin antibodies that is cell cycle regulated, with levels that are consistently reduced during mitosis. We further show that an in vitro calpain assay with full-length or C-terminal coilin recombinant protein releases the same size cleaved fragment. Furthermore, addition of exogenous RNA to purified coilin induces proteolysis by calpain. We also report that the relative levels of this cleaved coilin fragment are susceptible to changes induced by various cell stressors, and that coilin localization is affected by inhibition or knockdown of calpain both under normal and stressed conditions. Collectively, our data suggest that coilin is subjected to regulated specific proteolysis by calpain, and this processing may play a role in the regulation of coilin activity and CB formation.
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Affiliation(s)
- Venkatramreddy Velma
- Department of Biochemistry, The University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216-4505, USA
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46
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Velma V, Carrero ZI, Allen CB, Hebert MD. Coilin levels modulate cell cycle progression and γH2AX levels in etoposide treated U2OS cells. FEBS Lett 2012; 586:3404-9. [PMID: 22986342 DOI: 10.1016/j.febslet.2012.07.054] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Revised: 07/05/2012] [Accepted: 07/17/2012] [Indexed: 11/28/2022]
Abstract
Coilin is considered the Cajal body (CB) marker protein. In this report, we investigated the role of coilin in the DNA damage response and found that coilin reduction correlated with significantly increased levels of soluble γH2AX in etoposide treated U2OS cells. Additionally, coilin levels influenced the proliferation rate and cell cycle distribution of cells exposed to etoposide. Moreover, coilin overexpression inhibited nucleolar localization of endogenous coilin in etoposide treated U2OS cells. Collectively, these data provide additional evidence for coilin and CBs in the DNA damage response.
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Affiliation(s)
- Venkatramreddy Velma
- Department of Biochemistry, The University of Mississippi Medical Center, Jackson, MS 39216-4505, USA
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In vitro RNase and nucleic acid binding activities implicate coilin in U snRNA processing. PLoS One 2012; 7:e36300. [PMID: 22558428 PMCID: PMC3338655 DOI: 10.1371/journal.pone.0036300] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Accepted: 04/04/2012] [Indexed: 11/21/2022] Open
Abstract
Coilin is known as the marker protein for Cajal bodies (CBs), subnuclear domains important for the biogenesis of small nuclear ribonucleoproteins (snRNPs) which function in pre-mRNA splicing. CBs associate non-randomly with U1 and U2 gene loci, which produce the small nuclear RNA (snRNA) component of the respective snRNP. Despite recognition as the CB marker protein, coilin is primarily nucleoplasmic, and the function of this fraction is not fully characterized. Here we show that coilin binds double stranded DNA and has RNase activity in vitro. U1 and U2 snRNAs undergo a processing event of the primary transcript prior to incorporation in the snRNP. We find that coilin displays RNase activity within the CU region of the U2 snRNA primary transcript in vitro, and that coilin knockdown results in accumulation of the 3′ pre-processed U1 and U2 snRNA. These findings present new characteristics of coilin in vitro, and suggest additional functions of the protein in vivo.
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Zhang M, Gan L, Ren GS. REGγ is a strong candidate for the regulation of cell cycle, proliferation and the invasion by poorly differentiated thyroid carcinoma cells. Braz J Med Biol Res 2012; 45:459-65. [PMID: 22415115 PMCID: PMC3854288 DOI: 10.1590/s0100-879x2012007500035] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2011] [Accepted: 02/28/2012] [Indexed: 11/22/2022] Open
Abstract
REGγ is a proteasome activator that facilitates the degradation of small peptides. Abnormally high expression of REGγ has been observed in thyroid carcinomas. The purpose of the present study was to explore the role of REGγ in poorly differentiated thyroid carcinoma (PDTC). For this purpose, small interfering RNA (siRNA) was introduced to down-regulate the level of REGγ in the PDTC cell line SW579. Down-regulation of REGγ at the mRNA and protein levels was confirmed by RT-PCR and Western blot analyses. FACS analysis revealed cell cycle arrest at the G1/S transition, the MTT assay showed inhibition of cell proliferation, and the Transwell assay showed restricted cell invasion. Furthermore, the expression of the p21 protein was increased, the expression of proliferating cell nuclear antigen (PCNA) protein decreased, and the expression of the p27 protein was unchanged as shown by Western blot analyses. REGγ plays a critical role in the cell cycle, proliferation and invasion of SW579 cells. The alteration of p21 and PCNA proteins related to the down-regulation of REGγ suggests that p21 and PCNA participate in the process of REGγ regulation of cell cycle progression and cell proliferation. Thus, targeting REGγ has a therapeutic potential in the management of PDTC patients.
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Affiliation(s)
- M Zhang
- Department of General Surgery, The First Affiliated Hospital, Chongqing Medical University, China
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Reorganization of Cajal bodies and nucleolar targeting of coilin in motor neurons of type I spinal muscular atrophy. Histochem Cell Biol 2012; 137:657-67. [DOI: 10.1007/s00418-012-0921-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/13/2012] [Indexed: 12/21/2022]
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Carrero ZI, Velma V, Douglas HE, Hebert MD. Coilin phosphomutants disrupt Cajal body formation, reduce cell proliferation and produce a distinct coilin degradation product. PLoS One 2011; 6:e25743. [PMID: 21991343 PMCID: PMC3185009 DOI: 10.1371/journal.pone.0025743] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 09/09/2011] [Indexed: 12/17/2022] Open
Abstract
Coilin is a nuclear phosphoprotein that accumulates in Cajal bodies (CBs). CBs participate in ribonucleoprotein and telomerase biogenesis, and are often found in cells with high transcriptional demands such as neuronal and cancer cells, but can also be observed less frequently in other cell types such as fibroblasts. Many proteins enriched within the CB are phosphorylated, but it is not clear what role this modification has on the activity of these proteins in the CB. Coilin is considered to be the CB marker protein and is essential for proper CB formation and composition in mammalian cells. In order to characterize the role of coilin phosphorylation on CB formation, we evaluated various coilin phosphomutants using transient expression. Additionally, we generated inducible coilin phosphomutant cell lines that, when used in combination with endogenous coilin knockdown, allow for the expression of the phosphomutants at physiological levels. Transient expression of all coilin phosphomutants except the phosphonull mutant (OFF) significantly reduces proliferation. Interestingly, a stable cell line induced to express the coilin S489D phosphomutant displays nucleolar accumulation of the mutant and generates a N-terminal degradation product; neither of which is observed upon transient expression. A N-terminal degradation product and nucleolar localization are also observed in a stable cell line induced to express a coilin phosphonull mutant (OFF). The nucleolar localization of the S489D and OFF coilin mutants observed in the stable cell lines is decreased when endogenous coilin is reduced. Furthermore, all the phosphomutant cells lines show a significant reduction in CB formation when compared to wild-type after endogenous coilin knockdown. Cell proliferation studies on these lines reveal that only wild-type coilin and the OFF mutant are sufficient to rescue the reduction in proliferation associated with endogenous coilin depletion. These results emphasize the role of coilin phosphorylation in the formation and activity of CBs.
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Affiliation(s)
- Zunamys I. Carrero
- Department of Biochemistry, The University of Mississippi Medical Center, Jackson, Mississippi, United States of America
| | - Venkatramreddy Velma
- Department of Biochemistry, The University of Mississippi Medical Center, Jackson, Mississippi, United States of America
| | - Heather E. Douglas
- Department of Biochemistry, The University of Mississippi Medical Center, Jackson, Mississippi, United States of America
| | - Michael D. Hebert
- Department of Biochemistry, The University of Mississippi Medical Center, Jackson, Mississippi, United States of America
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