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Yucel-Polat A, Campos-Melo D, Alikhah A, Strong MJ. Dynamic Localization of Paraspeckle Components under Osmotic Stress. Noncoding RNA 2024; 10:23. [PMID: 38668381 PMCID: PMC11053584 DOI: 10.3390/ncrna10020023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 04/05/2024] [Accepted: 04/10/2024] [Indexed: 04/29/2024] Open
Abstract
Paraspeckles are nuclear condensates formed by NEAT1_2 lncRNA and different RNA-binding proteins. In general, these membraneless organelles function in the regulation of gene expression and translation and in miRNA processing, and in doing this, they regulate cellular homeostasis and mediate pro-survival in the cell. Despite evidence showing the importance of paraspeckles in the stress response, the dynamics of paraspeckles and their components under conditions of osmotic stress remain unknown. We exposed HEK293T cells to sorbitol and examined NEAT1_2 expression using real-time PCR. Localization and quantification of the main paraspeckle components, NEAT1_2, PSPC1, NONO, and SFPQ, in different cellular compartments was performed using smFISH and immunofluorescence. Our findings showed a significant decrease in total NEAT1_2 expression in cells after osmotic stress. Sorbitol shifted the subcellular localization of NEAT1_2, PSPC1, NONO, and SFPQ from the nucleus to the cytoplasm and decreased the number and size of NEAT1_2 foci in the nucleus. PSPC1 formed immunoreactive cytoplasmic fibrils under conditions of osmotic stress, which slowly disassembled under recovery. Our study deepens the paraspeckle dynamics in response to stress, suggesting a novel role for NEAT1_2 in the cytoplasm in osmotic stress and physiological conditions.
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Affiliation(s)
- Aysegul Yucel-Polat
- Molecular Medicine Group, Schulich School of Medicine & Dentistry, Robarts Research Institute, Western University, London, ON N6A 3K7, Canada; (A.Y.-P.); (A.A.)
| | - Danae Campos-Melo
- Molecular Medicine Group, Schulich School of Medicine & Dentistry, Robarts Research Institute, Western University, London, ON N6A 3K7, Canada; (A.Y.-P.); (A.A.)
| | - Asieh Alikhah
- Molecular Medicine Group, Schulich School of Medicine & Dentistry, Robarts Research Institute, Western University, London, ON N6A 3K7, Canada; (A.Y.-P.); (A.A.)
| | - Michael J. Strong
- Molecular Medicine Group, Schulich School of Medicine & Dentistry, Robarts Research Institute, Western University, London, ON N6A 3K7, Canada; (A.Y.-P.); (A.A.)
- Department of Clinical Neurological Sciences, Schulich School of Medicine & Dentistry, Western University, London, ON N6A 3K7, Canada
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Obuse C, Hirose T. Functional domains of nuclear long noncoding RNAs: Insights into gene regulation and intracellular architecture. Curr Opin Cell Biol 2023; 85:102250. [PMID: 37806294 DOI: 10.1016/j.ceb.2023.102250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 08/12/2023] [Accepted: 09/07/2023] [Indexed: 10/10/2023]
Abstract
Recent functional research on long noncoding RNAs (lncRNAs) has revealed their significant regulatory roles in gene expression and intracellular architecture. Well-characterized examples of such lncRNAs include Xist and NEAT1_2, which play critical roles in heterochromatin formation of inactive X-chromosomes and paraspeckle assembly, in mammalian cells. Both lncRNAs possess modular domain structures with multiple functionally distinct domains that serve as platforms for specific RNA-binding proteins (RBPs), which dictate the function of each lncRNA. Some of these RBPs bind characteristic RNA structures, which can be targeted by small chemical compounds that modulate lncRNA function by perturbing the interaction of RBPs with the RNA structures. Therefore, RNA structures hidden in lncRNAs represent a novel and potent type of therapeutic target.
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Affiliation(s)
- Chikashi Obuse
- Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan; Institute for Open and Transdisciplinary Research Initiatives (OTRI), Osaka University, Suita 565-0871, Japan
| | - Tetsuro Hirose
- Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan; Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan; Institute for Open and Transdisciplinary Research Initiatives (OTRI), Osaka University, Suita 565-0871, Japan.
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Poller W, Sahoo S, Hajjar R, Landmesser U, Krichevsky AM. Exploration of the Noncoding Genome for Human-Specific Therapeutic Targets-Recent Insights at Molecular and Cellular Level. Cells 2023; 12:2660. [PMID: 37998395 PMCID: PMC10670380 DOI: 10.3390/cells12222660] [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: 10/06/2023] [Revised: 11/13/2023] [Accepted: 11/14/2023] [Indexed: 11/25/2023] Open
Abstract
While it is well known that 98-99% of the human genome does not encode proteins, but are nevertheless transcriptionally active and give rise to a broad spectrum of noncoding RNAs [ncRNAs] with complex regulatory and structural functions, specific functions have so far been assigned to only a tiny fraction of all known transcripts. On the other hand, the striking observation of an overwhelmingly growing fraction of ncRNAs, in contrast to an only modest increase in the number of protein-coding genes, during evolution from simple organisms to humans, strongly suggests critical but so far essentially unexplored roles of the noncoding genome for human health and disease pathogenesis. Research into the vast realm of the noncoding genome during the past decades thus lead to a profoundly enhanced appreciation of the multi-level complexity of the human genome. Here, we address a few of the many huge remaining knowledge gaps and consider some newly emerging questions and concepts of research. We attempt to provide an up-to-date assessment of recent insights obtained by molecular and cell biological methods, and by the application of systems biology approaches. Specifically, we discuss current data regarding two topics of high current interest: (1) By which mechanisms could evolutionary recent ncRNAs with critical regulatory functions in a broad spectrum of cell types (neural, immune, cardiovascular) constitute novel therapeutic targets in human diseases? (2) Since noncoding genome evolution is causally linked to brain evolution, and given the profound interactions between brain and immune system, could human-specific brain-expressed ncRNAs play a direct or indirect (immune-mediated) role in human diseases? Synergistic with remarkable recent progress regarding delivery, efficacy, and safety of nucleic acid-based therapies, the ongoing large-scale exploration of the noncoding genome for human-specific therapeutic targets is encouraging to proceed with the development and clinical evaluation of novel therapeutic pathways suggested by these research fields.
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Affiliation(s)
- Wolfgang Poller
- Department for Cardiology, Angiology and Intensive Care Medicine, Deutsches Herzzentrum Charité (DHZC), Charité-Universitätsmedizin Berlin, 12200 Berlin, Germany;
- Berlin-Brandenburg Center for Regenerative Therapies (BCRT), Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 13353 Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Site Berlin, 10785 Berlin, Germany
| | - Susmita Sahoo
- Cardiovascular Research Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1030, New York, NY 10029, USA;
| | - Roger Hajjar
- Gene & Cell Therapy Institute, Mass General Brigham, 65 Landsdowne St, Suite 143, Cambridge, MA 02139, USA;
| | - Ulf Landmesser
- Department for Cardiology, Angiology and Intensive Care Medicine, Deutsches Herzzentrum Charité (DHZC), Charité-Universitätsmedizin Berlin, 12200 Berlin, Germany;
- German Center for Cardiovascular Research (DZHK), Site Berlin, 10785 Berlin, Germany
- Berlin Institute of Health, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany
| | - Anna M. Krichevsky
- Department of Neurology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA;
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Takakuwa H, Yamazaki T, Souquere S, Adachi S, Yoshino H, Fujiwara N, Yamamoto T, Natsume T, Nakagawa S, Pierron G, Hirose T. Shell protein composition specified by the lncRNA NEAT1 domains dictates the formation of paraspeckles as distinct membraneless organelles. Nat Cell Biol 2023; 25:1664-1675. [PMID: 37932453 DOI: 10.1038/s41556-023-01254-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Accepted: 09/12/2023] [Indexed: 11/08/2023]
Abstract
Many membraneless organelles (MLOs) formed through phase separation play crucial roles in various cellular processes. Although these MLOs co-exist in cells, how they maintain their independence without coalescence or engulfment remains largely unknown. Here, we investigated the molecular mechanism by which paraspeckles with core-shell architecture scaffolded by NEAT1_2 long noncoding RNAs exist as distinct MLOs. We identified NEAT1 deletion mutants that assemble paraspeckles that are incorporated into nuclear speckles. Several paraspeckle proteins, including SFPQ, HNRNPF and BRG1, prevent this incorporation and thus contribute to the segregation of paraspeckles from nuclear speckles. Shell localization of these proteins in the paraspeckles, which is determined by NEAT1_2 long noncoding RNA domains, is required for this segregation process. Conversely, U2-related spliceosomal proteins are involved in internalizing the paraspeckles into nuclear speckles. This study shows that the paraspeckle shell composition dictates the independence of MLOs in the nucleus, providing insights into the importance of the shell in defining features and functions of MLOs.
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Affiliation(s)
- Hiro Takakuwa
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
- Institute for Genetic Medicine, Hokkaido University, Sapporo, Japan
| | - Tomohiro Yamazaki
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan.
| | | | - Shungo Adachi
- Department of Proteomics, National Cancer Center Research Institute, Tokyo, Japan
| | - Hyura Yoshino
- Institute for Genetic Medicine, Hokkaido University, Sapporo, Japan
| | - Naoko Fujiwara
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
| | - Tetsuya Yamamoto
- Institute for Chemical Reaction Design and Discovery, Hokkaido University, Sapporo, Japan
| | - Tohru Natsume
- Cellular and Molecular Biotechnology Research Institute, National Institute for Advanced Industrial Science and Technology, Tokyo, Japan
| | - Shinichi Nakagawa
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
| | - Gerard Pierron
- Centre National de la Recherche Scientifique, UMR-9196, Gustave Roussy, Villejuif, France
| | - Tetsuro Hirose
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan.
- Institute for Open and Transdisciplinary Research Initiatives, Osaka University, Suita, Japan.
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Cowburn D, Rout M. Improving the hole picture: towards a consensus on the mechanism of nuclear transport. Biochem Soc Trans 2023; 51:871-886. [PMID: 37099395 PMCID: PMC10212546 DOI: 10.1042/bst20220494] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 04/04/2023] [Accepted: 04/06/2023] [Indexed: 04/27/2023]
Abstract
Nuclear pore complexes (NPCs) mediate the exchange of materials between the nucleoplasm and cytoplasm, playing a key role in the separation of nucleic acids and proteins into their required compartments. The static structure of the NPC is relatively well defined by recent cryo-EM and other studies. The functional roles of dynamic components in the pore of the NPC, phenylalanyl-glycyl (FG) repeat rich nucleoporins, is less clear because of our limited understanding of highly dynamic protein systems. These proteins form a 'restrained concentrate' which interacts with and concentrates nuclear transport factors (NTRs) to provide facilitated nucleocytoplasmic transport of cargoes. Very rapid on- and off-rates among FG repeats and NTRs supports extremely fast facilitated transport, close to the rate of macromolecular diffusion in cytoplasm, while complexes without specific interactions are entropically excluded, though details on several aspects of the transport mechanism and FG repeat behaviors remain to be resolved. However, as discussed here, new technical approaches combined with more advanced modeling methods will likely provide an improved dynamic description of NPC transport, potentially at the atomic level in the near future. Such advances are likely to be of major benefit in comprehending the roles the malfunctioning NPC plays in cancer, ageing, viral diseases, and neurodegeneration.
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Affiliation(s)
- David Cowburn
- Departments of Biochemistry and Systems and Computational Biology, Albert Einstein College of Medicine, Bronx, NY 10461, U.S.A
| | - Michael Rout
- Laboratory of Cellular and Structural Biology, The Rockefeller University, New York, NY 10065, U.S.A
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Kozai T, Fernandez-Martinez J, van Eeuwen T, Gallardo P, Kapinos LE, Mazur A, Zhang W, Tempkin J, Panatala R, Delgado-Izquierdo M, Raveh B, Sali A, Chait BT, Veenhoff LM, Rout MP, Lim RYH. Dynamic molecular mechanism of the nuclear pore complex permeability barrier. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.31.535055. [PMID: 37066338 PMCID: PMC10103940 DOI: 10.1101/2023.03.31.535055] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
Nuclear pore complexes (NPCs) mediate nucleocytoplasmic transport of specific macromolecules while impeding the exchange of unsolicited material. However, key aspects of this gating mechanism remain controversial. To address this issue, we determined the nanoscopic behavior of the permeability barrier directly within yeast S. cerevisiae NPCs at transport-relevant timescales. We show that the large intrinsically disordered domains of phenylalanine-glycine repeat nucleoporins (FG Nups) exhibit highly dynamic fluctuations to create transient voids in the permeability barrier that continuously shape-shift and reseal, resembling a radial polymer brush. Together with cargo-carrying transport factors the FG domains form a feature called the central plug, which is also highly dynamic. Remarkably, NPC mutants with longer FG domains show interweaving meshwork-like behavior that attenuates nucleocytoplasmic transport in vivo. Importantly, the bona fide nanoscale NPC behaviors and morphologies are not recapitulated by in vitro FG domain hydrogels. NPCs also exclude self-assembling FG domain condensates in vivo, thereby indicating that the permeability barrier is not generated by a self-assembling phase condensate, but rather is largely a polymer brush, organized by the NPC scaffold, whose dynamic gating selectivity is strongly enhanced by the presence of transport factors.
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Affiliation(s)
- Toshiya Kozai
- Biozentrum, University of Basel, Switzerland
- Swiss Nanoscience Institute, University of Basel, Switzerland
| | - Javier Fernandez-Martinez
- Laboratory of Cellular and Structural Biology, The Rockefeller University, New York, U.S.A
- Ikerbasque, Basque Foundation for Science, Bilbao, Spain
- Instituto Biofisika (UPV/EHU, CSIC), University of the Basque Country, 48940, Leioa, Spain
| | - Trevor van Eeuwen
- Laboratory of Cellular and Structural Biology, The Rockefeller University, New York, U.S.A
| | - Paola Gallardo
- European Research Institute for the Biology of Ageing, University Medical Center Groningen, University of Groningen, Netherlands
| | | | - Adam Mazur
- Biozentrum, University of Basel, Switzerland
| | - Wenzhu Zhang
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, U.S.A
| | - Jeremy Tempkin
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, U.S.A. Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 94158, USA. Quantitative Biosciences Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | | | | | - Barak Raveh
- School of Computer Science and Engineering, The Hebrew University of Jerusalem, Israel
| | - Andrej Sali
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, U.S.A. Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 94158, USA. Quantitative Biosciences Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Brian T. Chait
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, U.S.A
| | - Liesbeth M. Veenhoff
- European Research Institute for the Biology of Ageing, University Medical Center Groningen, University of Groningen, Netherlands
| | - Michael P. Rout
- Laboratory of Cellular and Structural Biology, The Rockefeller University, New York, U.S.A
| | - Roderick Y. H. Lim
- Biozentrum, University of Basel, Switzerland
- Swiss Nanoscience Institute, University of Basel, Switzerland
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