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Tapken I, Detering NT, Claus P. What could be the function of the spinal muscular atrophy-causing protein SMN in macrophages? Front Immunol 2024; 15:1375428. [PMID: 38863697 PMCID: PMC11165114 DOI: 10.3389/fimmu.2024.1375428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Accepted: 05/06/2024] [Indexed: 06/13/2024] Open
Abstract
Spinal Muscular Atrophy (SMA), a neurodegenerative disorder, extends its impact beyond the nervous system. The central protein implicated in SMA, Survival Motor Neuron (SMN) protein, is ubiquitously expressed and functions in fundamental processes such as alternative splicing, translation, cytoskeletal dynamics and signaling. These processes are relevant for all cellular systems, including cells of the immune system such as macrophages. Macrophages are capable of modulating their splicing, cytoskeleton and expression profile in order to fulfil their role in tissue homeostasis and defense. However, less is known about impairment or dysfunction of macrophages lacking SMN and the subsequent impact on the immune system of SMA patients. We aimed to review the potential overlaps between SMN functions and macrophage mechanisms highlighting the need for future research, as well as the current state of research addressing the role of macrophages in SMA.
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Affiliation(s)
- Ines Tapken
- SMATHERIA gGmbH – Non-Profit Biomedical Research Institute, Hannover, Germany
- Center for Systems Neuroscience (ZSN), Hannover, Germany
| | - Nora T. Detering
- SMATHERIA gGmbH – Non-Profit Biomedical Research Institute, Hannover, Germany
- Center for Systems Neuroscience (ZSN), Hannover, Germany
| | - Peter Claus
- SMATHERIA gGmbH – Non-Profit Biomedical Research Institute, Hannover, Germany
- Center for Systems Neuroscience (ZSN), Hannover, Germany
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2
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CLK1 reorganizes the splicing factor U1-70K for early spliceosomal protein assembly. Proc Natl Acad Sci U S A 2021; 118:2018251118. [PMID: 33811140 DOI: 10.1073/pnas.2018251118] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Early spliceosome assembly requires phosphorylation of U1-70K, a constituent of the U1 small nuclear ribonucleoprotein (snRNP), but it is unclear which sites are phosphorylated, and by what enzyme, and how such modification regulates function. By profiling the proteome, we found that the Cdc2-like kinase 1 (CLK1) phosphorylates Ser-226 in the C terminus of U1-70K. This releases U1-70K from subnuclear granules facilitating interaction with U1 snRNP and the serine-arginine (SR) protein SRSF1, critical steps in establishing the 5' splice site. CLK1 breaks contacts between the C terminus and the RNA recognition motif (RRM) in U1-70K releasing the RRM to bind SRSF1. This reorganization also permits stable interactions between U1-70K and several proteins associated with U1 snRNP. Nuclear induction of the SR protein kinase 1 (SRPK1) facilitates CLK1 dissociation from U1-70K, recycling the kinase for catalysis. These studies demonstrate that CLK1 plays a vital, signal-dependent role in early spliceosomal protein assembly by contouring U1-70K for protein-protein multitasking.
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3
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Emenecker RJ, Holehouse AS, Strader LC. Emerging Roles for Phase Separation in Plants. Dev Cell 2020; 55:69-83. [PMID: 33049212 PMCID: PMC7577370 DOI: 10.1016/j.devcel.2020.09.010] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 08/19/2020] [Accepted: 09/02/2020] [Indexed: 12/12/2022]
Abstract
The plant cell internal environment is a dynamic, intricate landscape composed of many intracellular compartments. Cells organize some cellular components through formation of biomolecular condensates-non-stoichiometric assemblies of protein and/or nucleic acids. In many cases, phase separation appears to either underly or contribute to the formation of biomolecular condensates. Many canonical membraneless compartments within animal cells form in a manner that is at least consistent with phase separation, including nucleoli, stress granules, Cajal bodies, and numerous additional bodies, regulated by developmental and environmental stimuli. In this Review, we examine the emerging roles for phase separation in plants. Further, drawing on studies carried out in other organisms, we identify cellular phenomenon in plants that might also arise via phase separation. We propose that plants make use of phase separation to a much greater extent than has been previously appreciated, implicating phase separation as an evolutionarily ancient mechanism for cellular organization.
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Affiliation(s)
- Ryan J Emenecker
- Department of Biology, Washington University, St. Louis, MO 63130, USA; Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA; Center for Science and Engineering Living Systems (CSELS), Washington University, St. Louis, MO 63130, USA; Center for Engineering Mechanobiology, Washington University, St. Louis, MO 63130, USA
| | - Alex S Holehouse
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA; Center for Science and Engineering Living Systems (CSELS), Washington University, St. Louis, MO 63130, USA.
| | - Lucia C Strader
- Center for Science and Engineering Living Systems (CSELS), Washington University, St. Louis, MO 63130, USA; Center for Engineering Mechanobiology, Washington University, St. Louis, MO 63130, USA; Department of Biology, Duke University, Durham, NC 27708, USA.
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4
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Bishof I, Dammer EB, Duong DM, Kundinger SR, Gearing M, Lah JJ, Levey AI, Seyfried NT. RNA-binding proteins with basic-acidic dipeptide (BAD) domains self-assemble and aggregate in Alzheimer's disease. J Biol Chem 2018; 293:11047-11066. [PMID: 29802200 PMCID: PMC6052236 DOI: 10.1074/jbc.ra118.001747] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 05/23/2018] [Indexed: 12/12/2022] Open
Abstract
The U1 small nuclear ribonucleoprotein 70 kDa (U1-70K) and other RNA-binding proteins (RBPs) are mislocalized to cytoplasmic neurofibrillary Tau aggregates in Alzheimer's disease (AD), yet the co-aggregation mechanisms are incompletely understood. U1-70K harbors two disordered low-complexity domains (LC1 and LC2) that are necessary for aggregation in AD brain extracts. The LC1 domain contains highly repetitive basic (Arg/Lys) and acidic (Asp/Glu) residues, referred to as a basic-acidic dipeptide (BAD) domain. We report here that this domain shares many of the properties of the Gln/Asn-rich LC domains in RBPs that also aggregate in neurodegenerative disease. These properties included self-assembly into oligomers and localization to nuclear granules. Co-immunoprecipitations of recombinant U1-70K and deletions lacking the LC domain(s) followed by quantitative proteomic analyses were used to resolve functional classes of U1-70K-interacting proteins that depend on the BAD domain for their interaction. Within this interaction network, we identified a class of RBPs with BAD domains nearly identical to that found in U1-70K. Two members of this class, LUC7L3 and RBM25, required their respective BAD domains for reciprocal interactions with U1-70K and nuclear granule localization. Strikingly, a significant proportion of RBPs with BAD domains had elevated insolubility in the AD brain proteome. Furthermore, we show that the BAD domain of U1-70K can interact with Tau from AD brains but not from other tauopathies. These findings highlight a mechanistic role for BAD domains in stabilizing RBP interactions and in potentially mediating co-aggregation with the pathological AD-specific Tau isoforms.
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Affiliation(s)
- Isaac Bishof
- From the Departments of Biochemistry
- the Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Eric B Dammer
- From the Departments of Biochemistry
- the Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Duc M Duong
- From the Departments of Biochemistry
- the Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Sean R Kundinger
- From the Departments of Biochemistry
- the Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Marla Gearing
- the Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, Georgia 30322
- Pathology and Laboratory Medicine and
| | - James J Lah
- the Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, Georgia 30322
- Neurology, and
| | - Allan I Levey
- the Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, Georgia 30322
- Neurology, and
| | - Nicholas T Seyfried
- From the Departments of Biochemistry,
- the Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, Georgia 30322
- Neurology, and
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5
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Roithová A, Klimešová K, Pánek J, Will CL, Lührmann R, Staněk D, Girard C. The Sm-core mediates the retention of partially-assembled spliceosomal snRNPs in Cajal bodies until their full maturation. Nucleic Acids Res 2018; 46:3774-3790. [PMID: 29415178 PMCID: PMC5909452 DOI: 10.1093/nar/gky070] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 01/19/2018] [Accepted: 01/25/2018] [Indexed: 01/23/2023] Open
Abstract
Cajal bodies (CBs) are nuclear non-membrane bound organelles where small nuclear ribonucleoprotein particles (snRNPs) undergo their final maturation and quality control before they are released to the nucleoplasm. However, the molecular mechanism how immature snRNPs are targeted and retained in CBs has yet to be described. Here, we microinjected and expressed various snRNA deletion mutants as well as chimeric 7SK, Alu or bacterial SRP non-coding RNAs and provide evidence that Sm and SMN binding sites are necessary and sufficient for CB localization of snRNAs. We further show that Sm proteins, and specifically their GR-rich domains, are important for accumulating snRNPs in CBs. Accordingly, core snRNPs containing the Sm proteins, but not naked snRNAs, restore the formation of CBs after their depletion. Finally, we show that immature but not fully assembled snRNPs are able to induce CB formation and that microinjection of an excess of U2 snRNP-specific proteins, which promotes U2 snRNP maturation, chases U2 snRNA from CBs. We propose that the accessibility of the Sm ring represents the molecular basis for the quality control of the final maturation of snRNPs and the sequestration of immature particles in CBs.
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Affiliation(s)
- Adriana Roithová
- Institute of Molecular Genetics, Czech Academy of Sciences, Prague, Czech Republic
| | - Klára Klimešová
- Institute of Molecular Genetics, Czech Academy of Sciences, Prague, Czech Republic
| | - Josef Pánek
- Institute of Microbiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Cindy L Will
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | | | - David Staněk
- Institute of Molecular Genetics, Czech Academy of Sciences, Prague, Czech Republic
| | - Cyrille Girard
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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6
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Raimer AC, Gray KM, Matera AG. SMN - A chaperone for nuclear RNP social occasions? RNA Biol 2017; 14:701-711. [PMID: 27648855 PMCID: PMC5519234 DOI: 10.1080/15476286.2016.1236168] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 09/01/2016] [Accepted: 09/09/2016] [Indexed: 12/24/2022] Open
Abstract
Survival Motor Neuron (SMN) protein localizes to both the nucleus and the cytoplasm. Cytoplasmic SMN is diffusely localized in large oligomeric complexes with core member proteins, called Gemins. Biochemical and cell biological studies have demonstrated that the SMN complex is required for the cytoplasmic assembly and nuclear transport of Sm-class ribonucleoproteins (RNPs). Nuclear SMN accumulates with spliceosomal small nuclear (sn)RNPs in Cajal bodies, sub-domains involved in multiple facets of snRNP maturation. Thus, the SMN complex forms stable associations with both nuclear and cytoplasmic snRNPs, and plays a critical role in their biogenesis. In this review, we focus on potential functions of the nuclear SMN complex, with particular emphasis on its role within the Cajal body.
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Affiliation(s)
- Amanda C. Raimer
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Kelsey M. Gray
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - A. Gregory Matera
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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7
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Staněk D, Fox AH. Nuclear bodies: news insights into structure and function. Curr Opin Cell Biol 2017; 46:94-101. [PMID: 28577509 DOI: 10.1016/j.ceb.2017.05.001] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 04/20/2017] [Accepted: 05/10/2017] [Indexed: 02/07/2023]
Abstract
The cell nucleus contains a number of different dynamic bodies that are variously composed of proteins and generally, but not always, specific RNA molecules. Recent studies have revealed new understanding about nuclear body formation and function in different aspects of nuclear metabolism. Here, we focus on findings describing the role of nuclear bodies in the biogenesis of specific ribonucleoprotein complexes, processing of key mRNAs, and subnuclear sequestration of protein factors. We highlight how nuclear bodies are involved in stress responses, innate immunity and tumorigenesis. We further review organization of nuclear bodies and principles that govern their assembly, highlighting the pivotal role of scaffolding noncoding RNAs, and liquid-liquid phase separation, which are transforming our picture of nuclear body formation.
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Affiliation(s)
- David Staněk
- Institute of Molecular Genetics, Czech Academy of Sciences, Prague, Czech Republic
| | - Archa H Fox
- School of Human Sciences and Molecular Sciences, The University of Western Australia and Harry Perkins Institute of Medical Research, Centre for Medical Research, The University of Western Australia, Crawley, 6009 Western Australia, Australia.
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8
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Abstract
Spliceosomal snRNPs are complex particles that proceed through a fascinating maturation pathway. Several steps of this pathway are closely linked to nuclear non-membrane structures called Cajal bodies. In this review, I summarize the last 20 y of research in this field. I primarily focus on snRNP biogenesis, specifically on the steps that involve Cajal bodies. I also evaluate the contribution of the Cajal body in snRNP quality control and discuss the role of snRNPs in Cajal body formation.
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Affiliation(s)
- David Staněk
- a Institute of Molecular Genetics, Czech Academy of Sciences , Prague , Czech Republic
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9
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Abstract
A majority of human genes contain non-coding intervening sequences – introns that must be precisely excised from the pre-mRNA molecule. This event requires the coordinated action of five major small nuclear ribonucleoprotein particles (snRNPs) along with additional non-snRNP splicing proteins. Introns must be removed with nucleotidal precision, since even a single nucleotide mistake would result in a reading frame shift and production of a non-functional protein. Numerous human inherited diseases are caused by mutations that affect splicing, including mutations in proteins which are directly involved in splicing catalysis. One of the most common hereditary diseases associated with mutations in core splicing proteins is retinitis pigmentosa (RP). So far, mutations in more than 70 genes have been connected to RP. While the majority of mutated genes are expressed specifically in the retina, eight target genes encode for ubiquitous core snRNP proteins (Prpf3, Prpf4, Prpf6, Prpf8, Prpf31, and SNRNP200/Brr2) and splicing factors (RP9 and DHX38). Why mutations in spliceosomal proteins, which are essential in nearly every cell in the body, causes a disease that displays such a tissue-specific phenotype is currently a mystery. In this review, we recapitulate snRNP functions, summarize the missense mutations which are found in spliceosomal proteins as well as their impact on protein functions and discuss specific models which may explain why the retina is sensitive to these mutations.
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Affiliation(s)
- Šárka Růžičková
- a Department of RNA Biology , Institute of Molecular Genetics AS CR , Prague , Czech Republic
| | - David Staněk
- a Department of RNA Biology , Institute of Molecular Genetics AS CR , Prague , Czech Republic
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10
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Li H, Custer SK, Gilson T, Hao LT, Beattie CE, Androphy EJ. α-COP binding to the survival motor neuron protein SMN is required for neuronal process outgrowth. Hum Mol Genet 2015; 24:7295-307. [PMID: 26464491 DOI: 10.1093/hmg/ddv428] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 10/06/2015] [Indexed: 01/30/2023] Open
Abstract
Spinal muscular atrophy (SMA), a heritable neurodegenerative disease, results from insufficient levels of the survival motor neuron (SMN) protein. α-COP binds to SMN, linking the COPI vesicular transport pathway to SMA. Reduced levels of α-COP restricted development of neuronal processes in NSC-34 cells and primary cortical neurons. Remarkably, heterologous expression of human α-COP restored normal neurite length and morphology in SMN-depleted NSC-34 cells in vitro and zebrafish motor neurons in vivo. We identified single amino acid mutants of α-COP that selectively abrogate SMN binding, retain COPI-mediated Golgi-ER trafficking functionality, but were unable to support neurite outgrowth in cellular and zebrafish models of SMA. Taken together, these demonstrate the functional role of COPI association with the SMN protein in neuronal development.
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Affiliation(s)
- Hongxia Li
- Department of Dermatology, Indiana University School of Medicine, Indianapolis, IN 46202, USA and
| | - Sara K Custer
- Department of Dermatology, Indiana University School of Medicine, Indianapolis, IN 46202, USA and
| | - Timra Gilson
- Department of Dermatology, Indiana University School of Medicine, Indianapolis, IN 46202, USA and
| | - Le Thi Hao
- Department of Neuroscience, The Ohio State University, Columbus, OH 43210, USA
| | - Christine E Beattie
- Department of Neuroscience, The Ohio State University, Columbus, OH 43210, USA
| | - Elliot J Androphy
- Department of Dermatology, Indiana University School of Medicine, Indianapolis, IN 46202, USA and
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11
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Bizarro J, Dodré M, Huttin A, Charpentier B, Schlotter F, Branlant C, Verheggen C, Massenet S, Bertrand E. NUFIP and the HSP90/R2TP chaperone bind the SMN complex and facilitate assembly of U4-specific proteins. Nucleic Acids Res 2015; 43:8973-89. [PMID: 26275778 PMCID: PMC4605303 DOI: 10.1093/nar/gkv809] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 07/27/2015] [Indexed: 12/17/2022] Open
Abstract
The Sm proteins are loaded on snRNAs by the SMN complex, but how snRNP-specific proteins are assembled remains poorly characterized. U4 snRNP and box C/D snoRNPs have structural similarities. They both contain the 15.5K and proteins with NOP domains (PRP31 for U4, NOP56/58 for snoRNPs). Biogenesis of box C/D snoRNPs involves NUFIP and the HSP90/R2TP chaperone system and here, we explore the function of this machinery in U4 RNP assembly. We show that yeast Prp31 interacts with several components of the NUFIP/R2TP machinery, and that these interactions are separable from each other. In human cells, PRP31 mutants that fail to stably associate with U4 snRNA still interact with components of the NUFIP/R2TP system, indicating that these interactions precede binding of PRP31 to U4 snRNA. Knock-down of NUFIP leads to mislocalization of PRP31 and decreased association with U4. Moreover, NUFIP is associated with the SMN complex through direct interactions with Gemin3 and Gemin6. Altogether, our data suggest a model in which the NUFIP/R2TP system is connected with the SMN complex and facilitates assembly of U4 snRNP-specific proteins.
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Affiliation(s)
- Jonathan Bizarro
- Equipe labélisée Ligue contre le Cancer, Institut de Génétique Moléculaire de Montpellier, IGMM-UMR 5535 du CNRS-Université de Montpellier, 1919, route de Mende, 34293 Montpellier Cedex 5, France
| | - Maxime Dodré
- Ingénierie Moléculaire et Physiopathologie Articulaire, UMR 7365 CNRS-Université de Lorraine, Biopôle de l'Université de Lorraine, avenue de la forêt de Haye, BP 184, 54505 Vandoeuvre-les-Nancy Cedex, France
| | - Alexandra Huttin
- Ingénierie Moléculaire et Physiopathologie Articulaire, UMR 7365 CNRS-Université de Lorraine, Biopôle de l'Université de Lorraine, avenue de la forêt de Haye, BP 184, 54505 Vandoeuvre-les-Nancy Cedex, France
| | - Bruno Charpentier
- Ingénierie Moléculaire et Physiopathologie Articulaire, UMR 7365 CNRS-Université de Lorraine, Biopôle de l'Université de Lorraine, avenue de la forêt de Haye, BP 184, 54505 Vandoeuvre-les-Nancy Cedex, France
| | - Florence Schlotter
- Ingénierie Moléculaire et Physiopathologie Articulaire, UMR 7365 CNRS-Université de Lorraine, Biopôle de l'Université de Lorraine, avenue de la forêt de Haye, BP 184, 54505 Vandoeuvre-les-Nancy Cedex, France
| | - Christiane Branlant
- Ingénierie Moléculaire et Physiopathologie Articulaire, UMR 7365 CNRS-Université de Lorraine, Biopôle de l'Université de Lorraine, avenue de la forêt de Haye, BP 184, 54505 Vandoeuvre-les-Nancy Cedex, France
| | - Céline Verheggen
- Equipe labélisée Ligue contre le Cancer, Institut de Génétique Moléculaire de Montpellier, IGMM-UMR 5535 du CNRS-Université de Montpellier, 1919, route de Mende, 34293 Montpellier Cedex 5, France
| | - Séverine Massenet
- Ingénierie Moléculaire et Physiopathologie Articulaire, UMR 7365 CNRS-Université de Lorraine, Biopôle de l'Université de Lorraine, avenue de la forêt de Haye, BP 184, 54505 Vandoeuvre-les-Nancy Cedex, France
| | - Edouard Bertrand
- Equipe labélisée Ligue contre le Cancer, Institut de Génétique Moléculaire de Montpellier, IGMM-UMR 5535 du CNRS-Université de Montpellier, 1919, route de Mende, 34293 Montpellier Cedex 5, France
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12
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Yu Y, Chi B, Xia W, Gangopadhyay J, Yamazaki T, Winkelbauer-Hurt ME, Yin S, Eliasse Y, Adams E, Shaw CE, Reed R. U1 snRNP is mislocalized in ALS patient fibroblasts bearing NLS mutations in FUS and is required for motor neuron outgrowth in zebrafish. Nucleic Acids Res 2015; 43:3208-18. [PMID: 25735748 PMCID: PMC4381066 DOI: 10.1093/nar/gkv157] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 02/16/2015] [Accepted: 02/17/2015] [Indexed: 12/12/2022] Open
Abstract
Mutations in FUS cause amyotrophic lateral sclerosis (ALS), but the molecular pathways leading to neurodegeneration remain obscure. We previously found that U1 snRNP is the most abundant FUS interactor. Here, we report that components of the U1 snRNP core particle (Sm proteins and U1 snRNA), but not the mature U1 snRNP-specific proteins (U1-70K, U1A and U1C), co-mislocalize with FUS to the cytoplasm in ALS patient fibroblasts harboring mutations in the FUS nuclear localization signal (NLS). Similar results were obtained in HeLa cells expressing the ALS-causing FUS R495X NLS mutation, and mislocalization of Sm proteins is RRM-dependent. Moreover, as observed with FUS, knockdown of any of the U1 snRNP-specific proteins results in a dramatic loss of SMN-containing Gems. Significantly, knockdown of U1 snRNP in zebrafish results in motor axon truncations, a phenotype also observed with FUS, SMN and TDP-43 knockdowns. Our observations linking U1 snRNP to ALS patient cells with FUS mutations, SMN-containing Gems, and motor neurons indicate that U1 snRNP is a component of a molecular pathway associated with motor neuron disease. Linking an essential canonical splicing factor (U1 snRNP) to this pathway provides strong new evidence that splicing defects may be involved in pathogenesis and that this pathway is a potential therapeutic target.
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Affiliation(s)
- Yong Yu
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA
| | - Binkai Chi
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA
| | - Wei Xia
- Department of Marine Biotechnology, University of Maryland Baltimore County & Institute of Marine and Environmental Technology, Baltimore, MD 21042, USA
| | - Jaya Gangopadhyay
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA
| | - Tomohiro Yamazaki
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA
| | | | - Shanye Yin
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA
| | - Yoan Eliasse
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA
| | - Edward Adams
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA
| | - Christopher E Shaw
- King's College London and King's Health Partners, MRC Centre for Neurodegeneration Research, London SE5 8AF, UK
| | - Robin Reed
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA
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